xref: /llvm-project/flang/lib/Semantics/resolve-names.cpp (revision 9b49392d6edcdfcc59304350ebd4196be5180d4a)
1 //===-- lib/Semantics/resolve-names.cpp -----------------------------------===//
2 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3 // See https://llvm.org/LICENSE.txt for license information.
4 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5 //
6 //===----------------------------------------------------------------------===//
7 
8 #include "resolve-names.h"
9 #include "assignment.h"
10 #include "definable.h"
11 #include "mod-file.h"
12 #include "pointer-assignment.h"
13 #include "resolve-directives.h"
14 #include "resolve-names-utils.h"
15 #include "rewrite-parse-tree.h"
16 #include "flang/Common/Fortran.h"
17 #include "flang/Common/default-kinds.h"
18 #include "flang/Common/indirection.h"
19 #include "flang/Common/restorer.h"
20 #include "flang/Common/visit.h"
21 #include "flang/Evaluate/characteristics.h"
22 #include "flang/Evaluate/check-expression.h"
23 #include "flang/Evaluate/common.h"
24 #include "flang/Evaluate/fold-designator.h"
25 #include "flang/Evaluate/fold.h"
26 #include "flang/Evaluate/intrinsics.h"
27 #include "flang/Evaluate/tools.h"
28 #include "flang/Evaluate/type.h"
29 #include "flang/Parser/parse-tree-visitor.h"
30 #include "flang/Parser/parse-tree.h"
31 #include "flang/Parser/tools.h"
32 #include "flang/Semantics/attr.h"
33 #include "flang/Semantics/expression.h"
34 #include "flang/Semantics/program-tree.h"
35 #include "flang/Semantics/scope.h"
36 #include "flang/Semantics/semantics.h"
37 #include "flang/Semantics/symbol.h"
38 #include "flang/Semantics/tools.h"
39 #include "flang/Semantics/type.h"
40 #include "llvm/Support/raw_ostream.h"
41 #include <list>
42 #include <map>
43 #include <set>
44 #include <stack>
45 
46 namespace Fortran::semantics {
47 
48 using namespace parser::literals;
49 
50 template <typename T> using Indirection = common::Indirection<T>;
51 using Message = parser::Message;
52 using Messages = parser::Messages;
53 using MessageFixedText = parser::MessageFixedText;
54 using MessageFormattedText = parser::MessageFormattedText;
55 
56 class ResolveNamesVisitor;
57 class ScopeHandler;
58 
59 // ImplicitRules maps initial character of identifier to the DeclTypeSpec
60 // representing the implicit type; std::nullopt if none.
61 // It also records the presence of IMPLICIT NONE statements.
62 // When inheritFromParent is set, defaults come from the parent rules.
63 class ImplicitRules {
64 public:
65   ImplicitRules(SemanticsContext &context, const ImplicitRules *parent)
66       : parent_{parent}, context_{context},
67         inheritFromParent_{parent != nullptr} {}
68   bool isImplicitNoneType() const;
69   bool isImplicitNoneExternal() const;
70   void set_isImplicitNoneType(bool x) { isImplicitNoneType_ = x; }
71   void set_isImplicitNoneExternal(bool x) { isImplicitNoneExternal_ = x; }
72   void set_inheritFromParent(bool x) { inheritFromParent_ = x; }
73   // Get the implicit type for this name. May be null.
74   const DeclTypeSpec *GetType(
75       SourceName, bool respectImplicitNone = true) const;
76   // Record the implicit type for the range of characters [fromLetter,
77   // toLetter].
78   void SetTypeMapping(const DeclTypeSpec &type, parser::Location fromLetter,
79       parser::Location toLetter);
80 
81 private:
82   static char Incr(char ch);
83 
84   const ImplicitRules *parent_;
85   SemanticsContext &context_;
86   bool inheritFromParent_{false}; // look in parent if not specified here
87   bool isImplicitNoneType_{
88       context_.IsEnabled(common::LanguageFeature::ImplicitNoneTypeAlways)};
89   bool isImplicitNoneExternal_{false};
90   // map_ contains the mapping between letters and types that were defined
91   // by the IMPLICIT statements of the related scope. It does not contain
92   // the default Fortran mappings nor the mapping defined in parents.
93   std::map<char, common::Reference<const DeclTypeSpec>> map_;
94 
95   friend llvm::raw_ostream &operator<<(
96       llvm::raw_ostream &, const ImplicitRules &);
97   friend void ShowImplicitRule(
98       llvm::raw_ostream &, const ImplicitRules &, char);
99 };
100 
101 // scope -> implicit rules for that scope
102 using ImplicitRulesMap = std::map<const Scope *, ImplicitRules>;
103 
104 // Track statement source locations and save messages.
105 class MessageHandler {
106 public:
107   MessageHandler() { DIE("MessageHandler: default-constructed"); }
108   explicit MessageHandler(SemanticsContext &c) : context_{&c} {}
109   Messages &messages() { return context_->messages(); };
110   const std::optional<SourceName> &currStmtSource() {
111     return context_->location();
112   }
113   void set_currStmtSource(const std::optional<SourceName> &source) {
114     context_->set_location(source);
115   }
116 
117   // Emit a message associated with the current statement source.
118   Message &Say(MessageFixedText &&);
119   Message &Say(MessageFormattedText &&);
120   // Emit a message about a SourceName
121   Message &Say(const SourceName &, MessageFixedText &&);
122   // Emit a formatted message associated with a source location.
123   template <typename... A>
124   Message &Say(const SourceName &source, MessageFixedText &&msg, A &&...args) {
125     return context_->Say(source, std::move(msg), std::forward<A>(args)...);
126   }
127 
128 private:
129   SemanticsContext *context_;
130 };
131 
132 // Inheritance graph for the parse tree visitation classes that follow:
133 //   BaseVisitor
134 //   + AttrsVisitor
135 //   | + DeclTypeSpecVisitor
136 //   |   + ImplicitRulesVisitor
137 //   |     + ScopeHandler ------------------+
138 //   |       + ModuleVisitor -------------+ |
139 //   |       + GenericHandler -------+    | |
140 //   |       | + InterfaceVisitor    |    | |
141 //   |       +-+ SubprogramVisitor ==|==+ | |
142 //   + ArraySpecVisitor              |  | | |
143 //     + DeclarationVisitor <--------+  | | |
144 //       + ConstructVisitor             | | |
145 //         + ResolveNamesVisitor <------+-+-+
146 
147 class BaseVisitor {
148 public:
149   BaseVisitor() { DIE("BaseVisitor: default-constructed"); }
150   BaseVisitor(
151       SemanticsContext &c, ResolveNamesVisitor &v, ImplicitRulesMap &rules)
152       : implicitRulesMap_{&rules}, this_{&v}, context_{&c}, messageHandler_{c} {
153   }
154   template <typename T> void Walk(const T &);
155 
156   MessageHandler &messageHandler() { return messageHandler_; }
157   const std::optional<SourceName> &currStmtSource() {
158     return context_->location();
159   }
160   SemanticsContext &context() const { return *context_; }
161   evaluate::FoldingContext &GetFoldingContext() const {
162     return context_->foldingContext();
163   }
164   bool IsIntrinsic(
165       const SourceName &name, std::optional<Symbol::Flag> flag) const {
166     if (!flag) {
167       return context_->intrinsics().IsIntrinsic(name.ToString());
168     } else if (flag == Symbol::Flag::Function) {
169       return context_->intrinsics().IsIntrinsicFunction(name.ToString());
170     } else if (flag == Symbol::Flag::Subroutine) {
171       return context_->intrinsics().IsIntrinsicSubroutine(name.ToString());
172     } else {
173       DIE("expected Subroutine or Function flag");
174     }
175   }
176 
177   bool InModuleFile() const {
178     return GetFoldingContext().moduleFileName().has_value();
179   }
180 
181   // Make a placeholder symbol for a Name that otherwise wouldn't have one.
182   // It is not in any scope and always has MiscDetails.
183   void MakePlaceholder(const parser::Name &, MiscDetails::Kind);
184 
185   template <typename T> common::IfNoLvalue<T, T> FoldExpr(T &&expr) {
186     return evaluate::Fold(GetFoldingContext(), std::move(expr));
187   }
188 
189   template <typename T> MaybeExpr EvaluateExpr(const T &expr) {
190     return FoldExpr(AnalyzeExpr(*context_, expr));
191   }
192 
193   template <typename T>
194   MaybeExpr EvaluateNonPointerInitializer(
195       const Symbol &symbol, const T &expr, parser::CharBlock source) {
196     if (!context().HasError(symbol)) {
197       if (auto maybeExpr{AnalyzeExpr(*context_, expr)}) {
198         auto restorer{GetFoldingContext().messages().SetLocation(source)};
199         return evaluate::NonPointerInitializationExpr(
200             symbol, std::move(*maybeExpr), GetFoldingContext());
201       }
202     }
203     return std::nullopt;
204   }
205 
206   template <typename T> MaybeIntExpr EvaluateIntExpr(const T &expr) {
207     return semantics::EvaluateIntExpr(*context_, expr);
208   }
209 
210   template <typename T>
211   MaybeSubscriptIntExpr EvaluateSubscriptIntExpr(const T &expr) {
212     if (MaybeIntExpr maybeIntExpr{EvaluateIntExpr(expr)}) {
213       return FoldExpr(evaluate::ConvertToType<evaluate::SubscriptInteger>(
214           std::move(*maybeIntExpr)));
215     } else {
216       return std::nullopt;
217     }
218   }
219 
220   template <typename... A> Message &Say(A &&...args) {
221     return messageHandler_.Say(std::forward<A>(args)...);
222   }
223   template <typename... A>
224   Message &Say(
225       const parser::Name &name, MessageFixedText &&text, const A &...args) {
226     return messageHandler_.Say(name.source, std::move(text), args...);
227   }
228 
229 protected:
230   ImplicitRulesMap *implicitRulesMap_{nullptr};
231 
232 private:
233   ResolveNamesVisitor *this_;
234   SemanticsContext *context_;
235   MessageHandler messageHandler_;
236 };
237 
238 // Provide Post methods to collect attributes into a member variable.
239 class AttrsVisitor : public virtual BaseVisitor {
240 public:
241   bool BeginAttrs(); // always returns true
242   Attrs GetAttrs();
243   std::optional<common::CUDADataAttr> cudaDataAttr() { return cudaDataAttr_; }
244   Attrs EndAttrs();
245   bool SetPassNameOn(Symbol &);
246   void SetBindNameOn(Symbol &);
247   void Post(const parser::LanguageBindingSpec &);
248   bool Pre(const parser::IntentSpec &);
249   bool Pre(const parser::Pass &);
250 
251   bool CheckAndSet(Attr);
252 
253 // Simple case: encountering CLASSNAME causes ATTRNAME to be set.
254 #define HANDLE_ATTR_CLASS(CLASSNAME, ATTRNAME) \
255   bool Pre(const parser::CLASSNAME &) { \
256     CheckAndSet(Attr::ATTRNAME); \
257     return false; \
258   }
259   HANDLE_ATTR_CLASS(PrefixSpec::Elemental, ELEMENTAL)
260   HANDLE_ATTR_CLASS(PrefixSpec::Impure, IMPURE)
261   HANDLE_ATTR_CLASS(PrefixSpec::Module, MODULE)
262   HANDLE_ATTR_CLASS(PrefixSpec::Non_Recursive, NON_RECURSIVE)
263   HANDLE_ATTR_CLASS(PrefixSpec::Pure, PURE)
264   HANDLE_ATTR_CLASS(PrefixSpec::Recursive, RECURSIVE)
265   HANDLE_ATTR_CLASS(TypeAttrSpec::BindC, BIND_C)
266   HANDLE_ATTR_CLASS(BindAttr::Deferred, DEFERRED)
267   HANDLE_ATTR_CLASS(BindAttr::Non_Overridable, NON_OVERRIDABLE)
268   HANDLE_ATTR_CLASS(Abstract, ABSTRACT)
269   HANDLE_ATTR_CLASS(Allocatable, ALLOCATABLE)
270   HANDLE_ATTR_CLASS(Asynchronous, ASYNCHRONOUS)
271   HANDLE_ATTR_CLASS(Contiguous, CONTIGUOUS)
272   HANDLE_ATTR_CLASS(External, EXTERNAL)
273   HANDLE_ATTR_CLASS(Intrinsic, INTRINSIC)
274   HANDLE_ATTR_CLASS(NoPass, NOPASS)
275   HANDLE_ATTR_CLASS(Optional, OPTIONAL)
276   HANDLE_ATTR_CLASS(Parameter, PARAMETER)
277   HANDLE_ATTR_CLASS(Pointer, POINTER)
278   HANDLE_ATTR_CLASS(Protected, PROTECTED)
279   HANDLE_ATTR_CLASS(Save, SAVE)
280   HANDLE_ATTR_CLASS(Target, TARGET)
281   HANDLE_ATTR_CLASS(Value, VALUE)
282   HANDLE_ATTR_CLASS(Volatile, VOLATILE)
283 #undef HANDLE_ATTR_CLASS
284   bool Pre(const common::CUDADataAttr);
285 
286 protected:
287   std::optional<Attrs> attrs_;
288   std::optional<common::CUDADataAttr> cudaDataAttr_;
289 
290   Attr AccessSpecToAttr(const parser::AccessSpec &x) {
291     switch (x.v) {
292     case parser::AccessSpec::Kind::Public:
293       return Attr::PUBLIC;
294     case parser::AccessSpec::Kind::Private:
295       return Attr::PRIVATE;
296     }
297     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
298   }
299   Attr IntentSpecToAttr(const parser::IntentSpec &x) {
300     switch (x.v) {
301     case parser::IntentSpec::Intent::In:
302       return Attr::INTENT_IN;
303     case parser::IntentSpec::Intent::Out:
304       return Attr::INTENT_OUT;
305     case parser::IntentSpec::Intent::InOut:
306       return Attr::INTENT_INOUT;
307     }
308     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
309   }
310 
311 private:
312   bool IsDuplicateAttr(Attr);
313   bool HaveAttrConflict(Attr, Attr, Attr);
314   bool IsConflictingAttr(Attr);
315 
316   MaybeExpr bindName_; // from BIND(C, NAME="...")
317   bool isCDefined_{false}; // BIND(C, NAME="...", CDEFINED) extension
318   std::optional<SourceName> passName_; // from PASS(...)
319 };
320 
321 // Find and create types from declaration-type-spec nodes.
322 class DeclTypeSpecVisitor : public AttrsVisitor {
323 public:
324   using AttrsVisitor::Post;
325   using AttrsVisitor::Pre;
326   void Post(const parser::IntrinsicTypeSpec::DoublePrecision &);
327   void Post(const parser::IntrinsicTypeSpec::DoubleComplex &);
328   void Post(const parser::DeclarationTypeSpec::ClassStar &);
329   void Post(const parser::DeclarationTypeSpec::TypeStar &);
330   bool Pre(const parser::TypeGuardStmt &);
331   void Post(const parser::TypeGuardStmt &);
332   void Post(const parser::TypeSpec &);
333 
334   // Walk the parse tree of a type spec and return the DeclTypeSpec for it.
335   template <typename T>
336   const DeclTypeSpec *ProcessTypeSpec(const T &x, bool allowForward = false) {
337     auto restorer{common::ScopedSet(state_, State{})};
338     set_allowForwardReferenceToDerivedType(allowForward);
339     BeginDeclTypeSpec();
340     Walk(x);
341     const auto *type{GetDeclTypeSpec()};
342     EndDeclTypeSpec();
343     return type;
344   }
345 
346 protected:
347   struct State {
348     bool expectDeclTypeSpec{false}; // should see decl-type-spec only when true
349     const DeclTypeSpec *declTypeSpec{nullptr};
350     struct {
351       DerivedTypeSpec *type{nullptr};
352       DeclTypeSpec::Category category{DeclTypeSpec::TypeDerived};
353     } derived;
354     bool allowForwardReferenceToDerivedType{false};
355   };
356 
357   bool allowForwardReferenceToDerivedType() const {
358     return state_.allowForwardReferenceToDerivedType;
359   }
360   void set_allowForwardReferenceToDerivedType(bool yes) {
361     state_.allowForwardReferenceToDerivedType = yes;
362   }
363 
364   const DeclTypeSpec *GetDeclTypeSpec();
365   void BeginDeclTypeSpec();
366   void EndDeclTypeSpec();
367   void SetDeclTypeSpec(const DeclTypeSpec &);
368   void SetDeclTypeSpecCategory(DeclTypeSpec::Category);
369   DeclTypeSpec::Category GetDeclTypeSpecCategory() const {
370     return state_.derived.category;
371   }
372   KindExpr GetKindParamExpr(
373       TypeCategory, const std::optional<parser::KindSelector> &);
374   void CheckForAbstractType(const Symbol &typeSymbol);
375 
376 private:
377   State state_;
378 
379   void MakeNumericType(TypeCategory, int kind);
380 };
381 
382 // Visit ImplicitStmt and related parse tree nodes and updates implicit rules.
383 class ImplicitRulesVisitor : public DeclTypeSpecVisitor {
384 public:
385   using DeclTypeSpecVisitor::Post;
386   using DeclTypeSpecVisitor::Pre;
387   using ImplicitNoneNameSpec = parser::ImplicitStmt::ImplicitNoneNameSpec;
388 
389   void Post(const parser::ParameterStmt &);
390   bool Pre(const parser::ImplicitStmt &);
391   bool Pre(const parser::LetterSpec &);
392   bool Pre(const parser::ImplicitSpec &);
393   void Post(const parser::ImplicitSpec &);
394 
395   const DeclTypeSpec *GetType(
396       SourceName name, bool respectImplicitNoneType = true) {
397     return implicitRules_->GetType(name, respectImplicitNoneType);
398   }
399   bool isImplicitNoneType() const {
400     return implicitRules_->isImplicitNoneType();
401   }
402   bool isImplicitNoneType(const Scope &scope) const {
403     return implicitRulesMap_->at(&scope).isImplicitNoneType();
404   }
405   bool isImplicitNoneExternal() const {
406     return implicitRules_->isImplicitNoneExternal();
407   }
408   void set_inheritFromParent(bool x) {
409     implicitRules_->set_inheritFromParent(x);
410   }
411 
412 protected:
413   void BeginScope(const Scope &);
414   void SetScope(const Scope &);
415 
416 private:
417   // implicit rules in effect for current scope
418   ImplicitRules *implicitRules_{nullptr};
419   std::optional<SourceName> prevImplicit_;
420   std::optional<SourceName> prevImplicitNone_;
421   std::optional<SourceName> prevImplicitNoneType_;
422   std::optional<SourceName> prevParameterStmt_;
423 
424   bool HandleImplicitNone(const std::list<ImplicitNoneNameSpec> &nameSpecs);
425 };
426 
427 // Track array specifications. They can occur in AttrSpec, EntityDecl,
428 // ObjectDecl, DimensionStmt, CommonBlockObject, BasedPointer, and
429 // ComponentDecl.
430 // 1. INTEGER, DIMENSION(10) :: x
431 // 2. INTEGER :: x(10)
432 // 3. ALLOCATABLE :: x(:)
433 // 4. DIMENSION :: x(10)
434 // 5. COMMON x(10)
435 // 6. POINTER(p,x(10))
436 class ArraySpecVisitor : public virtual BaseVisitor {
437 public:
438   void Post(const parser::ArraySpec &);
439   void Post(const parser::ComponentArraySpec &);
440   void Post(const parser::CoarraySpec &);
441   void Post(const parser::AttrSpec &) { PostAttrSpec(); }
442   void Post(const parser::ComponentAttrSpec &) { PostAttrSpec(); }
443 
444 protected:
445   const ArraySpec &arraySpec();
446   void set_arraySpec(const ArraySpec arraySpec) { arraySpec_ = arraySpec; }
447   const ArraySpec &coarraySpec();
448   void BeginArraySpec();
449   void EndArraySpec();
450   void ClearArraySpec() { arraySpec_.clear(); }
451   void ClearCoarraySpec() { coarraySpec_.clear(); }
452 
453 private:
454   // arraySpec_/coarraySpec_ are populated from any ArraySpec/CoarraySpec
455   ArraySpec arraySpec_;
456   ArraySpec coarraySpec_;
457   // When an ArraySpec is under an AttrSpec or ComponentAttrSpec, it is moved
458   // into attrArraySpec_
459   ArraySpec attrArraySpec_;
460   ArraySpec attrCoarraySpec_;
461 
462   void PostAttrSpec();
463 };
464 
465 // Manages a stack of function result information.  We defer the processing
466 // of a type specification that appears in the prefix of a FUNCTION statement
467 // until the function result variable appears in the specification part
468 // or the end of the specification part.  This allows for forward references
469 // in the type specification to resolve to local names.
470 class FuncResultStack {
471 public:
472   explicit FuncResultStack(ScopeHandler &scopeHandler)
473       : scopeHandler_{scopeHandler} {}
474   ~FuncResultStack();
475 
476   struct FuncInfo {
477     FuncInfo(const Scope &s, SourceName at) : scope{s}, source{at} {}
478     const Scope &scope;
479     SourceName source;
480     // Parse tree of the type specification in the FUNCTION prefix
481     const parser::DeclarationTypeSpec *parsedType{nullptr};
482     // Name of the function RESULT in the FUNCTION suffix, if any
483     const parser::Name *resultName{nullptr};
484     // Result symbol
485     Symbol *resultSymbol{nullptr};
486     bool inFunctionStmt{false}; // true between Pre/Post of FunctionStmt
487   };
488 
489   // Completes the definition of the top function's result.
490   void CompleteFunctionResultType();
491   // Completes the definition of a symbol if it is the top function's result.
492   void CompleteTypeIfFunctionResult(Symbol &);
493 
494   FuncInfo *Top() { return stack_.empty() ? nullptr : &stack_.back(); }
495   FuncInfo &Push(const Scope &scope, SourceName at) {
496     return stack_.emplace_back(scope, at);
497   }
498   void Pop();
499 
500 private:
501   ScopeHandler &scopeHandler_;
502   std::vector<FuncInfo> stack_;
503 };
504 
505 // Manage a stack of Scopes
506 class ScopeHandler : public ImplicitRulesVisitor {
507 public:
508   using ImplicitRulesVisitor::Post;
509   using ImplicitRulesVisitor::Pre;
510 
511   Scope &currScope() { return DEREF(currScope_); }
512   // The enclosing host procedure if current scope is in an internal procedure
513   Scope *GetHostProcedure();
514   // The innermost enclosing program unit scope, ignoring BLOCK and other
515   // construct scopes.
516   Scope &InclusiveScope();
517   // The enclosing scope, skipping derived types.
518   Scope &NonDerivedTypeScope();
519 
520   // Create a new scope and push it on the scope stack.
521   void PushScope(Scope::Kind kind, Symbol *symbol);
522   void PushScope(Scope &scope);
523   void PopScope();
524   void SetScope(Scope &);
525 
526   template <typename T> bool Pre(const parser::Statement<T> &x) {
527     messageHandler().set_currStmtSource(x.source);
528     currScope_->AddSourceRange(x.source);
529     return true;
530   }
531   template <typename T> void Post(const parser::Statement<T> &) {
532     messageHandler().set_currStmtSource(std::nullopt);
533   }
534 
535   // Special messages: already declared; referencing symbol's declaration;
536   // about a type; two names & locations
537   void SayAlreadyDeclared(const parser::Name &, Symbol &);
538   void SayAlreadyDeclared(const SourceName &, Symbol &);
539   void SayAlreadyDeclared(const SourceName &, const SourceName &);
540   void SayWithReason(
541       const parser::Name &, Symbol &, MessageFixedText &&, Message &&);
542   template <typename... A>
543   Message &SayWithDecl(
544       const parser::Name &, Symbol &, MessageFixedText &&, A &&...args);
545   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
546   Message &SayDerivedType(
547       const SourceName &, MessageFixedText &&, const Scope &);
548   Message &Say2(const SourceName &, MessageFixedText &&, const SourceName &,
549       MessageFixedText &&);
550   Message &Say2(
551       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
552   Message &Say2(
553       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
554 
555   // Search for symbol by name in current, parent derived type, and
556   // containing scopes
557   Symbol *FindSymbol(const parser::Name &);
558   Symbol *FindSymbol(const Scope &, const parser::Name &);
559   // Search for name only in scope, not in enclosing scopes.
560   Symbol *FindInScope(const Scope &, const parser::Name &);
561   Symbol *FindInScope(const Scope &, const SourceName &);
562   template <typename T> Symbol *FindInScope(const T &name) {
563     return FindInScope(currScope(), name);
564   }
565   // Search for name in a derived type scope and its parents.
566   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
567   Symbol *FindInTypeOrParents(const parser::Name &);
568   Symbol *FindInScopeOrBlockConstructs(const Scope &, SourceName);
569   Symbol *FindSeparateModuleProcedureInterface(const parser::Name &);
570   void EraseSymbol(const parser::Name &);
571   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
572   // Make a new symbol with the name and attrs of an existing one
573   Symbol &CopySymbol(const SourceName &, const Symbol &);
574 
575   // Make symbols in the current or named scope
576   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
577   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
578   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
579   Symbol &MakeHostAssocSymbol(const parser::Name &, const Symbol &);
580 
581   template <typename D>
582   common::IfNoLvalue<Symbol &, D> MakeSymbol(
583       const parser::Name &name, D &&details) {
584     return MakeSymbol(name, Attrs{}, std::move(details));
585   }
586 
587   template <typename D>
588   common::IfNoLvalue<Symbol &, D> MakeSymbol(
589       const parser::Name &name, const Attrs &attrs, D &&details) {
590     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
591   }
592 
593   template <typename D>
594   common::IfNoLvalue<Symbol &, D> MakeSymbol(
595       const SourceName &name, const Attrs &attrs, D &&details) {
596     // Note: don't use FindSymbol here. If this is a derived type scope,
597     // we want to detect whether the name is already declared as a component.
598     auto *symbol{FindInScope(name)};
599     if (!symbol) {
600       symbol = &MakeSymbol(name, attrs);
601       symbol->set_details(std::move(details));
602       return *symbol;
603     }
604     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
605       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
606         if (!d->specific()) {
607           // derived type with same name as a generic
608           auto *derivedType{d->derivedType()};
609           if (!derivedType) {
610             derivedType =
611                 &currScope().MakeSymbol(name, attrs, std::move(details));
612             d->set_derivedType(*derivedType);
613           } else if (derivedType->CanReplaceDetails(details)) {
614             // was forward-referenced
615             CheckDuplicatedAttrs(name, *symbol, attrs);
616             SetExplicitAttrs(*derivedType, attrs);
617             derivedType->set_details(std::move(details));
618           } else {
619             SayAlreadyDeclared(name, *derivedType);
620           }
621           return *derivedType;
622         }
623       }
624     } else if constexpr (std::is_same_v<ProcEntityDetails, D>) {
625       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
626         if (!d->derivedType()) {
627           // procedure pointer with same name as a generic
628           auto *specific{d->specific()};
629           if (!specific) {
630             specific = &currScope().MakeSymbol(name, attrs, std::move(details));
631             d->set_specific(*specific);
632           } else {
633             SayAlreadyDeclared(name, *specific);
634           }
635           return *specific;
636         }
637       }
638     }
639     if (symbol->CanReplaceDetails(details)) {
640       // update the existing symbol
641       CheckDuplicatedAttrs(name, *symbol, attrs);
642       SetExplicitAttrs(*symbol, attrs);
643       if constexpr (std::is_same_v<SubprogramDetails, D>) {
644         // Dummy argument defined by explicit interface?
645         details.set_isDummy(IsDummy(*symbol));
646       }
647       symbol->set_details(std::move(details));
648       return *symbol;
649     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
650       CheckDuplicatedAttrs(name, *symbol, attrs);
651       SetExplicitAttrs(*symbol, attrs);
652       return *symbol;
653     } else {
654       if (!CheckPossibleBadForwardRef(*symbol)) {
655         if (name.empty() && symbol->name().empty()) {
656           // report the error elsewhere
657           return *symbol;
658         }
659         Symbol &errSym{*symbol};
660         if (auto *d{symbol->detailsIf<GenericDetails>()}) {
661           if (d->specific()) {
662             errSym = *d->specific();
663           } else if (d->derivedType()) {
664             errSym = *d->derivedType();
665           }
666         }
667         SayAlreadyDeclared(name, errSym);
668       }
669       // replace the old symbol with a new one with correct details
670       EraseSymbol(*symbol);
671       auto &result{MakeSymbol(name, attrs, std::move(details))};
672       context().SetError(result);
673       return result;
674     }
675   }
676 
677   void MakeExternal(Symbol &);
678 
679   // C815 duplicated attribute checking; returns false on error
680   bool CheckDuplicatedAttr(SourceName, Symbol &, Attr);
681   bool CheckDuplicatedAttrs(SourceName, Symbol &, Attrs);
682 
683   void SetExplicitAttr(Symbol &symbol, Attr attr) const {
684     symbol.attrs().set(attr);
685     symbol.implicitAttrs().reset(attr);
686   }
687   void SetExplicitAttrs(Symbol &symbol, Attrs attrs) const {
688     symbol.attrs() |= attrs;
689     symbol.implicitAttrs() &= ~attrs;
690   }
691   void SetImplicitAttr(Symbol &symbol, Attr attr) const {
692     symbol.attrs().set(attr);
693     symbol.implicitAttrs().set(attr);
694   }
695   void SetCUDADataAttr(
696       SourceName, Symbol &, std::optional<common::CUDADataAttr>);
697 
698 protected:
699   FuncResultStack &funcResultStack() { return funcResultStack_; }
700 
701   // Apply the implicit type rules to this symbol.
702   void ApplyImplicitRules(Symbol &, bool allowForwardReference = false);
703   bool ImplicitlyTypeForwardRef(Symbol &);
704   void AcquireIntrinsicProcedureFlags(Symbol &);
705   const DeclTypeSpec *GetImplicitType(
706       Symbol &, bool respectImplicitNoneType = true);
707   void CheckEntryDummyUse(SourceName, Symbol *);
708   bool ConvertToObjectEntity(Symbol &);
709   bool ConvertToProcEntity(Symbol &, std::optional<SourceName> = std::nullopt);
710 
711   const DeclTypeSpec &MakeNumericType(
712       TypeCategory, const std::optional<parser::KindSelector> &);
713   const DeclTypeSpec &MakeNumericType(TypeCategory, int);
714   const DeclTypeSpec &MakeLogicalType(
715       const std::optional<parser::KindSelector> &);
716   const DeclTypeSpec &MakeLogicalType(int);
717   void NotePossibleBadForwardRef(const parser::Name &);
718   std::optional<SourceName> HadForwardRef(const Symbol &) const;
719   bool CheckPossibleBadForwardRef(const Symbol &);
720 
721   bool inSpecificationPart_{false};
722   bool deferImplicitTyping_{false};
723   bool skipImplicitTyping_{false};
724   bool inEquivalenceStmt_{false};
725 
726   // Some information is collected from a specification part for deferred
727   // processing in DeclarationPartVisitor functions (e.g., CheckSaveStmts())
728   // that are called by ResolveNamesVisitor::FinishSpecificationPart().  Since
729   // specification parts can nest (e.g., INTERFACE bodies), the collected
730   // information that is not contained in the scope needs to be packaged
731   // and restorable.
732   struct SpecificationPartState {
733     std::set<SourceName> forwardRefs;
734     // Collect equivalence sets and process at end of specification part
735     std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets;
736     // Names of all common block objects in the scope
737     std::set<SourceName> commonBlockObjects;
738     // Info about SAVE statements and attributes in current scope
739     struct {
740       std::optional<SourceName> saveAll; // "SAVE" without entity list
741       std::set<SourceName> entities; // names of entities with save attr
742       std::set<SourceName> commons; // names of common blocks with save attr
743     } saveInfo;
744   } specPartState_;
745 
746   // Some declaration processing can and should be deferred to
747   // ResolveExecutionParts() to avoid prematurely creating implicitly-typed
748   // local symbols that should be host associations.
749   struct DeferredDeclarationState {
750     // The content of each namelist group
751     std::list<const parser::NamelistStmt::Group *> namelistGroups;
752   };
753   DeferredDeclarationState *GetDeferredDeclarationState(bool add = false) {
754     if (!add && deferred_.find(&currScope()) == deferred_.end()) {
755       return nullptr;
756     } else {
757       return &deferred_.emplace(&currScope(), DeferredDeclarationState{})
758                   .first->second;
759     }
760   }
761 
762   void SkipImplicitTyping(bool skip) {
763     deferImplicitTyping_ = skipImplicitTyping_ = skip;
764   }
765 
766 private:
767   Scope *currScope_{nullptr};
768   FuncResultStack funcResultStack_{*this};
769   std::map<Scope *, DeferredDeclarationState> deferred_;
770 };
771 
772 class ModuleVisitor : public virtual ScopeHandler {
773 public:
774   bool Pre(const parser::AccessStmt &);
775   bool Pre(const parser::Only &);
776   bool Pre(const parser::Rename::Names &);
777   bool Pre(const parser::Rename::Operators &);
778   bool Pre(const parser::UseStmt &);
779   void Post(const parser::UseStmt &);
780 
781   void BeginModule(const parser::Name &, bool isSubmodule);
782   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
783   void ApplyDefaultAccess();
784   Symbol &AddGenericUse(GenericDetails &, const SourceName &, const Symbol &);
785   void AddAndCheckModuleUse(SourceName, bool isIntrinsic);
786   void CollectUseRenames(const parser::UseStmt &);
787   void ClearUseRenames() { useRenames_.clear(); }
788   void ClearUseOnly() { useOnly_.clear(); }
789   void ClearModuleUses() {
790     intrinsicUses_.clear();
791     nonIntrinsicUses_.clear();
792   }
793 
794 private:
795   // The location of the last AccessStmt without access-ids, if any.
796   std::optional<SourceName> prevAccessStmt_;
797   // The scope of the module during a UseStmt
798   Scope *useModuleScope_{nullptr};
799   // Names that have appeared in a rename clause of USE statements
800   std::set<std::pair<SourceName, SourceName>> useRenames_;
801   // Names that have appeared in an ONLY clause of a USE statement
802   std::set<std::pair<SourceName, Scope *>> useOnly_;
803   // Intrinsic and non-intrinsic (explicit or not) module names that
804   // have appeared in USE statements; used for C1406 warnings.
805   std::set<SourceName> intrinsicUses_;
806   std::set<SourceName> nonIntrinsicUses_;
807 
808   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
809   // A rename in a USE statement: local => use
810   struct SymbolRename {
811     Symbol *local{nullptr};
812     Symbol *use{nullptr};
813   };
814   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
815   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
816   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
817   void DoAddUse(
818       SourceName, SourceName, Symbol &localSymbol, const Symbol &useSymbol);
819   void AddUse(const GenericSpecInfo &);
820   // Record a name appearing as the target of a USE rename clause
821   void AddUseRename(SourceName name, SourceName moduleName) {
822     useRenames_.emplace(std::make_pair(name, moduleName));
823   }
824   bool IsUseRenamed(const SourceName &name) const {
825     return useModuleScope_ && useModuleScope_->symbol() &&
826         useRenames_.find({name, useModuleScope_->symbol()->name()}) !=
827         useRenames_.end();
828   }
829   // Record a name appearing in a USE ONLY clause
830   void AddUseOnly(const SourceName &name) {
831     useOnly_.emplace(std::make_pair(name, useModuleScope_));
832   }
833   bool IsUseOnly(const SourceName &name) const {
834     return useOnly_.find({name, useModuleScope_}) != useOnly_.end();
835   }
836   Scope *FindModule(const parser::Name &, std::optional<bool> isIntrinsic,
837       Scope *ancestor = nullptr);
838 };
839 
840 class GenericHandler : public virtual ScopeHandler {
841 protected:
842   using ProcedureKind = parser::ProcedureStmt::Kind;
843   void ResolveSpecificsInGeneric(Symbol &, bool isEndOfSpecificationPart);
844   void DeclaredPossibleSpecificProc(Symbol &);
845 
846   // Mappings of generics to their as-yet specific proc names and kinds
847   using SpecificProcMapType =
848       std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>;
849   SpecificProcMapType specificsForGenericProcs_;
850   // inversion of SpecificProcMapType: maps pending proc names to generics
851   using GenericProcMapType = std::multimap<SourceName, Symbol *>;
852   GenericProcMapType genericsForSpecificProcs_;
853 };
854 
855 class InterfaceVisitor : public virtual ScopeHandler,
856                          public virtual GenericHandler {
857 public:
858   bool Pre(const parser::InterfaceStmt &);
859   void Post(const parser::InterfaceStmt &);
860   void Post(const parser::EndInterfaceStmt &);
861   bool Pre(const parser::GenericSpec &);
862   bool Pre(const parser::ProcedureStmt &);
863   bool Pre(const parser::GenericStmt &);
864   void Post(const parser::GenericStmt &);
865 
866   bool inInterfaceBlock() const;
867   bool isGeneric() const;
868   bool isAbstract() const;
869 
870 protected:
871   Symbol &GetGenericSymbol() { return DEREF(genericInfo_.top().symbol); }
872   // Add to generic the symbol for the subprogram with the same name
873   void CheckGenericProcedures(Symbol &);
874 
875 private:
876   // A new GenericInfo is pushed for each interface block and generic stmt
877   struct GenericInfo {
878     GenericInfo(bool isInterface, bool isAbstract = false)
879         : isInterface{isInterface}, isAbstract{isAbstract} {}
880     bool isInterface; // in interface block
881     bool isAbstract; // in abstract interface block
882     Symbol *symbol{nullptr}; // the generic symbol being defined
883   };
884   std::stack<GenericInfo> genericInfo_;
885   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
886   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
887   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
888   void ResolveNewSpecifics();
889 };
890 
891 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
892 public:
893   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
894   bool Pre(const parser::SubroutineStmt &);
895   bool Pre(const parser::FunctionStmt &);
896   void Post(const parser::FunctionStmt &);
897   bool Pre(const parser::EntryStmt &);
898   void Post(const parser::EntryStmt &);
899   bool Pre(const parser::InterfaceBody::Subroutine &);
900   void Post(const parser::InterfaceBody::Subroutine &);
901   bool Pre(const parser::InterfaceBody::Function &);
902   void Post(const parser::InterfaceBody::Function &);
903   bool Pre(const parser::Suffix &);
904   bool Pre(const parser::PrefixSpec &);
905   bool Pre(const parser::PrefixSpec::Attributes &);
906   void Post(const parser::PrefixSpec::Launch_Bounds &);
907   void Post(const parser::PrefixSpec::Cluster_Dims &);
908 
909   bool BeginSubprogram(const parser::Name &, Symbol::Flag,
910       bool hasModulePrefix = false,
911       const parser::LanguageBindingSpec * = nullptr,
912       const ProgramTree::EntryStmtList * = nullptr);
913   bool BeginMpSubprogram(const parser::Name &);
914   void PushBlockDataScope(const parser::Name &);
915   void EndSubprogram(std::optional<parser::CharBlock> stmtSource = std::nullopt,
916       const std::optional<parser::LanguageBindingSpec> * = nullptr,
917       const ProgramTree::EntryStmtList * = nullptr);
918 
919 protected:
920   // Set when we see a stmt function that is really an array element assignment
921   bool misparsedStmtFuncFound_{false};
922 
923 private:
924   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
925   // so that it can be replaced by a later definition.
926   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
927   void CheckExtantProc(const parser::Name &, Symbol::Flag);
928   // Create a subprogram symbol in the current scope and push a new scope.
929   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag,
930       const parser::LanguageBindingSpec * = nullptr,
931       bool hasModulePrefix = false);
932   Symbol *GetSpecificFromGeneric(const parser::Name &);
933   Symbol &PostSubprogramStmt();
934   void CreateDummyArgument(SubprogramDetails &, const parser::Name &);
935   void CreateEntry(const parser::EntryStmt &stmt, Symbol &subprogram);
936   void PostEntryStmt(const parser::EntryStmt &stmt);
937   void HandleLanguageBinding(Symbol *,
938       std::optional<parser::CharBlock> stmtSource,
939       const std::optional<parser::LanguageBindingSpec> *);
940 };
941 
942 class DeclarationVisitor : public ArraySpecVisitor,
943                            public virtual GenericHandler {
944 public:
945   using ArraySpecVisitor::Post;
946   using ScopeHandler::Post;
947   using ScopeHandler::Pre;
948 
949   bool Pre(const parser::Initialization &);
950   void Post(const parser::EntityDecl &);
951   void Post(const parser::ObjectDecl &);
952   void Post(const parser::PointerDecl &);
953   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
954   void Post(const parser::BindStmt &) { EndAttrs(); }
955   bool Pre(const parser::BindEntity &);
956   bool Pre(const parser::OldParameterStmt &);
957   bool Pre(const parser::NamedConstantDef &);
958   bool Pre(const parser::NamedConstant &);
959   void Post(const parser::EnumDef &);
960   bool Pre(const parser::Enumerator &);
961   bool Pre(const parser::AccessSpec &);
962   bool Pre(const parser::AsynchronousStmt &);
963   bool Pre(const parser::ContiguousStmt &);
964   bool Pre(const parser::ExternalStmt &);
965   bool Pre(const parser::IntentStmt &);
966   bool Pre(const parser::IntrinsicStmt &);
967   bool Pre(const parser::OptionalStmt &);
968   bool Pre(const parser::ProtectedStmt &);
969   bool Pre(const parser::ValueStmt &);
970   bool Pre(const parser::VolatileStmt &);
971   bool Pre(const parser::AllocatableStmt &) {
972     objectDeclAttr_ = Attr::ALLOCATABLE;
973     return true;
974   }
975   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
976   bool Pre(const parser::TargetStmt &) {
977     objectDeclAttr_ = Attr::TARGET;
978     return true;
979   }
980   bool Pre(const parser::CUDAAttributesStmt &);
981   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
982   void Post(const parser::DimensionStmt::Declaration &);
983   void Post(const parser::CodimensionDecl &);
984   bool Pre(const parser::TypeDeclarationStmt &);
985   void Post(const parser::TypeDeclarationStmt &);
986   void Post(const parser::IntegerTypeSpec &);
987   void Post(const parser::IntrinsicTypeSpec::Real &);
988   void Post(const parser::IntrinsicTypeSpec::Complex &);
989   void Post(const parser::IntrinsicTypeSpec::Logical &);
990   void Post(const parser::IntrinsicTypeSpec::Character &);
991   void Post(const parser::CharSelector::LengthAndKind &);
992   void Post(const parser::CharLength &);
993   void Post(const parser::LengthSelector &);
994   bool Pre(const parser::KindParam &);
995   bool Pre(const parser::VectorTypeSpec &);
996   void Post(const parser::VectorTypeSpec &);
997   bool Pre(const parser::DeclarationTypeSpec::Type &);
998   void Post(const parser::DeclarationTypeSpec::Type &);
999   bool Pre(const parser::DeclarationTypeSpec::Class &);
1000   void Post(const parser::DeclarationTypeSpec::Class &);
1001   void Post(const parser::DeclarationTypeSpec::Record &);
1002   void Post(const parser::DerivedTypeSpec &);
1003   bool Pre(const parser::DerivedTypeDef &);
1004   bool Pre(const parser::DerivedTypeStmt &);
1005   void Post(const parser::DerivedTypeStmt &);
1006   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
1007   void Post(const parser::TypeParamDefStmt &);
1008   bool Pre(const parser::TypeAttrSpec::Extends &);
1009   bool Pre(const parser::PrivateStmt &);
1010   bool Pre(const parser::SequenceStmt &);
1011   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
1012   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
1013   void Post(const parser::ComponentDecl &);
1014   void Post(const parser::FillDecl &);
1015   bool Pre(const parser::ProcedureDeclarationStmt &);
1016   void Post(const parser::ProcedureDeclarationStmt &);
1017   bool Pre(const parser::DataComponentDefStmt &); // returns false
1018   bool Pre(const parser::ProcComponentDefStmt &);
1019   void Post(const parser::ProcComponentDefStmt &);
1020   bool Pre(const parser::ProcPointerInit &);
1021   void Post(const parser::ProcInterface &);
1022   void Post(const parser::ProcDecl &);
1023   bool Pre(const parser::TypeBoundProcedurePart &);
1024   void Post(const parser::TypeBoundProcedurePart &);
1025   void Post(const parser::ContainsStmt &);
1026   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
1027   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
1028   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
1029   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
1030   bool Pre(const parser::FinalProcedureStmt &);
1031   bool Pre(const parser::TypeBoundGenericStmt &);
1032   bool Pre(const parser::StructureDef &); // returns false
1033   bool Pre(const parser::Union::UnionStmt &);
1034   bool Pre(const parser::StructureField &);
1035   void Post(const parser::StructureField &);
1036   bool Pre(const parser::AllocateStmt &);
1037   void Post(const parser::AllocateStmt &);
1038   bool Pre(const parser::StructureConstructor &);
1039   bool Pre(const parser::NamelistStmt::Group &);
1040   bool Pre(const parser::IoControlSpec &);
1041   bool Pre(const parser::CommonStmt::Block &);
1042   bool Pre(const parser::CommonBlockObject &);
1043   void Post(const parser::CommonBlockObject &);
1044   bool Pre(const parser::EquivalenceStmt &);
1045   bool Pre(const parser::SaveStmt &);
1046   bool Pre(const parser::BasedPointer &);
1047   void Post(const parser::BasedPointer &);
1048 
1049   void PointerInitialization(
1050       const parser::Name &, const parser::InitialDataTarget &);
1051   void PointerInitialization(
1052       const parser::Name &, const parser::ProcPointerInit &);
1053   void NonPointerInitialization(
1054       const parser::Name &, const parser::ConstantExpr &);
1055   void CheckExplicitInterface(const parser::Name &);
1056   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
1057 
1058   const parser::Name *ResolveDesignator(const parser::Designator &);
1059   int GetVectorElementKind(
1060       TypeCategory category, const std::optional<parser::KindSelector> &kind);
1061 
1062 protected:
1063   bool BeginDecl();
1064   void EndDecl();
1065   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
1066   // Make sure that there's an entity in an enclosing scope called Name
1067   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
1068   // Declare a LOCAL/LOCAL_INIT/REDUCE entity while setting a locality flag. If
1069   // there isn't a type specified it comes from the entity in the containing
1070   // scope, or implicit rules.
1071   void DeclareLocalEntity(const parser::Name &, Symbol::Flag);
1072   // Declare a statement entity (i.e., an implied DO loop index for
1073   // a DATA statement or an array constructor).  If there isn't an explict
1074   // type specified, implicit rules apply. Return pointer to the new symbol,
1075   // or nullptr on error.
1076   Symbol *DeclareStatementEntity(const parser::DoVariable &,
1077       const std::optional<parser::IntegerTypeSpec> &);
1078   Symbol &MakeCommonBlockSymbol(const parser::Name &);
1079   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
1080   bool CheckUseError(const parser::Name &);
1081   void CheckAccessibility(const SourceName &, bool, Symbol &);
1082   void CheckCommonBlocks();
1083   void CheckSaveStmts();
1084   void CheckEquivalenceSets();
1085   bool CheckNotInBlock(const char *);
1086   bool NameIsKnownOrIntrinsic(const parser::Name &);
1087   void FinishNamelists();
1088 
1089   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
1090   // or nullptr in case of error.
1091   const parser::Name *ResolveStructureComponent(
1092       const parser::StructureComponent &);
1093   const parser::Name *ResolveDataRef(const parser::DataRef &);
1094   const parser::Name *ResolveName(const parser::Name &);
1095   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
1096   Symbol *NoteInterfaceName(const parser::Name &);
1097   bool IsUplevelReference(const Symbol &);
1098 
1099   std::optional<SourceName> BeginCheckOnIndexUseInOwnBounds(
1100       const parser::DoVariable &name) {
1101     std::optional<SourceName> result{checkIndexUseInOwnBounds_};
1102     checkIndexUseInOwnBounds_ = name.thing.thing.source;
1103     return result;
1104   }
1105   void EndCheckOnIndexUseInOwnBounds(const std::optional<SourceName> &restore) {
1106     checkIndexUseInOwnBounds_ = restore;
1107   }
1108   void NoteScalarSpecificationArgument(const Symbol &symbol) {
1109     mustBeScalar_.emplace(symbol);
1110   }
1111   // Declare an object or procedure entity.
1112   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1113   template <typename T>
1114   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1115     Symbol &symbol{MakeSymbol(name, attrs)};
1116     if (context().HasError(symbol) || symbol.has<T>()) {
1117       return symbol; // OK or error already reported
1118     } else if (symbol.has<UnknownDetails>()) {
1119       symbol.set_details(T{});
1120       return symbol;
1121     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1122       symbol.set_details(T{std::move(*details)});
1123       return symbol;
1124     } else if (std::is_same_v<EntityDetails, T> &&
1125         (symbol.has<ObjectEntityDetails>() ||
1126             symbol.has<ProcEntityDetails>())) {
1127       return symbol; // OK
1128     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1129       Say(name.source,
1130           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1131           name.source, GetUsedModule(*details).name());
1132     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1133       if (details->kind() == SubprogramKind::Module) {
1134         Say2(name,
1135             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1136             symbol, "Module procedure definition"_en_US);
1137       } else if (details->kind() == SubprogramKind::Internal) {
1138         Say2(name,
1139             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1140             symbol, "Internal procedure definition"_en_US);
1141       } else {
1142         DIE("unexpected kind");
1143       }
1144     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1145         symbol.has<ProcEntityDetails>()) {
1146       SayWithDecl(
1147           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1148     } else if (std::is_same_v<ProcEntityDetails, T> &&
1149         symbol.has<ObjectEntityDetails>()) {
1150       if (FindCommonBlockContaining(symbol)) {
1151         SayWithDecl(name, symbol,
1152             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1153       } else {
1154         SayWithDecl(
1155             name, symbol, "'%s' is already declared as an object"_err_en_US);
1156       }
1157     } else if (!CheckPossibleBadForwardRef(symbol)) {
1158       SayAlreadyDeclared(name, symbol);
1159     }
1160     context().SetError(symbol);
1161     return symbol;
1162   }
1163 
1164 private:
1165   // The attribute corresponding to the statement containing an ObjectDecl
1166   std::optional<Attr> objectDeclAttr_;
1167   // Info about current character type while walking DeclTypeSpec.
1168   // Also captures any "*length" specifier on an individual declaration.
1169   struct {
1170     std::optional<ParamValue> length;
1171     std::optional<KindExpr> kind;
1172   } charInfo_;
1173   // Info about current derived type or STRUCTURE while walking
1174   // DerivedTypeDef / StructureDef
1175   struct {
1176     const parser::Name *extends{nullptr}; // EXTENDS(name)
1177     bool privateComps{false}; // components are private by default
1178     bool privateBindings{false}; // bindings are private by default
1179     bool sawContains{false}; // currently processing bindings
1180     bool sequence{false}; // is a sequence type
1181     const Symbol *type{nullptr}; // derived type being defined
1182     bool isStructure{false}; // is a DEC STRUCTURE
1183   } derivedTypeInfo_;
1184   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
1185   // the interface name, if any.
1186   const parser::Name *interfaceName_{nullptr};
1187   // Map type-bound generic to binding names of its specific bindings
1188   std::multimap<Symbol *, const parser::Name *> genericBindings_;
1189   // Info about current ENUM
1190   struct EnumeratorState {
1191     // Enum value must hold inside a C_INT (7.6.2).
1192     std::optional<int> value{0};
1193   } enumerationState_;
1194   // Set for OldParameterStmt processing
1195   bool inOldStyleParameterStmt_{false};
1196   // Set when walking DATA & array constructor implied DO loop bounds
1197   // to warn about use of the implied DO intex therein.
1198   std::optional<SourceName> checkIndexUseInOwnBounds_;
1199   bool isVectorType_{false};
1200   UnorderedSymbolSet mustBeScalar_;
1201 
1202   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
1203   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
1204   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
1205   Symbol &DeclareProcEntity(
1206       const parser::Name &, Attrs, const Symbol *interface);
1207   void SetType(const parser::Name &, const DeclTypeSpec &);
1208   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
1209   std::optional<DerivedTypeSpec> ResolveExtendsType(
1210       const parser::Name &, const parser::Name *);
1211   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
1212   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1213   bool OkToAddComponent(const parser::Name &, const Symbol *extends = nullptr);
1214   ParamValue GetParamValue(
1215       const parser::TypeParamValue &, common::TypeParamAttr attr);
1216   void CheckCommonBlockDerivedType(
1217       const SourceName &, const Symbol &, UnorderedSymbolSet &);
1218   Attrs HandleSaveName(const SourceName &, Attrs);
1219   void AddSaveName(std::set<SourceName> &, const SourceName &);
1220   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1221   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1222   void Initialization(const parser::Name &, const parser::Initialization &,
1223       bool inComponentDecl);
1224   bool PassesLocalityChecks(
1225       const parser::Name &name, Symbol &symbol, Symbol::Flag flag);
1226   bool CheckForHostAssociatedImplicit(const parser::Name &);
1227   bool HasCycle(const Symbol &, const Symbol *interface);
1228   bool MustBeScalar(const Symbol &symbol) const {
1229     return mustBeScalar_.find(symbol) != mustBeScalar_.end();
1230   }
1231   void DeclareIntrinsic(const parser::Name &);
1232 };
1233 
1234 // Resolve construct entities and statement entities.
1235 // Check that construct names don't conflict with other names.
1236 class ConstructVisitor : public virtual DeclarationVisitor {
1237 public:
1238   bool Pre(const parser::ConcurrentHeader &);
1239   bool Pre(const parser::LocalitySpec::Local &);
1240   bool Pre(const parser::LocalitySpec::LocalInit &);
1241   bool Pre(const parser::LocalitySpec::Reduce &);
1242   bool Pre(const parser::LocalitySpec::Shared &);
1243   bool Pre(const parser::AcSpec &);
1244   bool Pre(const parser::AcImpliedDo &);
1245   bool Pre(const parser::DataImpliedDo &);
1246   bool Pre(const parser::DataIDoObject &);
1247   bool Pre(const parser::DataStmtObject &);
1248   bool Pre(const parser::DataStmtValue &);
1249   bool Pre(const parser::DoConstruct &);
1250   void Post(const parser::DoConstruct &);
1251   bool Pre(const parser::ForallConstruct &);
1252   void Post(const parser::ForallConstruct &);
1253   bool Pre(const parser::ForallStmt &);
1254   void Post(const parser::ForallStmt &);
1255   bool Pre(const parser::BlockConstruct &);
1256   void Post(const parser::Selector &);
1257   void Post(const parser::AssociateStmt &);
1258   void Post(const parser::EndAssociateStmt &);
1259   bool Pre(const parser::Association &);
1260   void Post(const parser::SelectTypeStmt &);
1261   void Post(const parser::SelectRankStmt &);
1262   bool Pre(const parser::SelectTypeConstruct &);
1263   void Post(const parser::SelectTypeConstruct &);
1264   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1265   void Post(const parser::SelectTypeConstruct::TypeCase &);
1266   // Creates Block scopes with neither symbol name nor symbol details.
1267   bool Pre(const parser::SelectRankConstruct::RankCase &);
1268   void Post(const parser::SelectRankConstruct::RankCase &);
1269   bool Pre(const parser::TypeGuardStmt::Guard &);
1270   void Post(const parser::TypeGuardStmt::Guard &);
1271   void Post(const parser::SelectRankCaseStmt::Rank &);
1272   bool Pre(const parser::ChangeTeamStmt &);
1273   void Post(const parser::EndChangeTeamStmt &);
1274   void Post(const parser::CoarrayAssociation &);
1275 
1276   // Definitions of construct names
1277   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1278   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1279   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1280   bool Pre(const parser::LabelDoStmt &) {
1281     return false; // error recovery
1282   }
1283   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1284   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1285   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1286   bool Pre(const parser::SelectRankConstruct &);
1287   void Post(const parser::SelectRankConstruct &);
1288   bool Pre(const parser::SelectRankStmt &x) {
1289     return CheckDef(std::get<0>(x.t));
1290   }
1291   bool Pre(const parser::SelectTypeStmt &x) {
1292     return CheckDef(std::get<0>(x.t));
1293   }
1294 
1295   // References to construct names
1296   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1297   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1298   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1299   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1300   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1301   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1302   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1303   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1304   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1305   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1306   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1307   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1308   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1309   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1310   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1311 
1312   void HandleImpliedAsynchronousInScope(const parser::Block &);
1313 
1314 private:
1315   // R1105 selector -> expr | variable
1316   // expr is set in either case unless there were errors
1317   struct Selector {
1318     Selector() {}
1319     Selector(const SourceName &source, MaybeExpr &&expr)
1320         : source{source}, expr{std::move(expr)} {}
1321     operator bool() const { return expr.has_value(); }
1322     parser::CharBlock source;
1323     MaybeExpr expr;
1324   };
1325   // association -> [associate-name =>] selector
1326   struct Association {
1327     const parser::Name *name{nullptr};
1328     Selector selector;
1329   };
1330   std::vector<Association> associationStack_;
1331   Association *currentAssociation_{nullptr};
1332 
1333   template <typename T> bool CheckDef(const T &t) {
1334     return CheckDef(std::get<std::optional<parser::Name>>(t));
1335   }
1336   template <typename T> void CheckRef(const T &t) {
1337     CheckRef(std::get<std::optional<parser::Name>>(t));
1338   }
1339   bool CheckDef(const std::optional<parser::Name> &);
1340   void CheckRef(const std::optional<parser::Name> &);
1341   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1342   const DeclTypeSpec &ToDeclTypeSpec(
1343       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1344   Symbol *MakeAssocEntity();
1345   void SetTypeFromAssociation(Symbol &);
1346   void SetAttrsFromAssociation(Symbol &);
1347   Selector ResolveSelector(const parser::Selector &);
1348   void ResolveIndexName(const parser::ConcurrentControl &control);
1349   void SetCurrentAssociation(std::size_t n);
1350   Association &GetCurrentAssociation();
1351   void PushAssociation();
1352   void PopAssociation(std::size_t count = 1);
1353 };
1354 
1355 // Create scopes for OpenACC constructs
1356 class AccVisitor : public virtual DeclarationVisitor {
1357 public:
1358   void AddAccSourceRange(const parser::CharBlock &);
1359 
1360   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1361 
1362   bool Pre(const parser::OpenACCBlockConstruct &);
1363   void Post(const parser::OpenACCBlockConstruct &);
1364   bool Pre(const parser::OpenACCCombinedConstruct &);
1365   void Post(const parser::OpenACCCombinedConstruct &);
1366   bool Pre(const parser::AccBeginBlockDirective &x) {
1367     AddAccSourceRange(x.source);
1368     return true;
1369   }
1370   void Post(const parser::AccBeginBlockDirective &) {
1371     messageHandler().set_currStmtSource(std::nullopt);
1372   }
1373   bool Pre(const parser::AccEndBlockDirective &x) {
1374     AddAccSourceRange(x.source);
1375     return true;
1376   }
1377   void Post(const parser::AccEndBlockDirective &) {
1378     messageHandler().set_currStmtSource(std::nullopt);
1379   }
1380   bool Pre(const parser::AccBeginLoopDirective &x) {
1381     AddAccSourceRange(x.source);
1382     return true;
1383   }
1384   void Post(const parser::AccBeginLoopDirective &x) {
1385     messageHandler().set_currStmtSource(std::nullopt);
1386   }
1387 };
1388 
1389 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1390   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1391   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1392   switch (beginDir.v) {
1393   case llvm::acc::Directive::ACCD_data:
1394   case llvm::acc::Directive::ACCD_host_data:
1395   case llvm::acc::Directive::ACCD_kernels:
1396   case llvm::acc::Directive::ACCD_parallel:
1397   case llvm::acc::Directive::ACCD_serial:
1398     return true;
1399   default:
1400     return false;
1401   }
1402 }
1403 
1404 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1405   messageHandler().set_currStmtSource(source);
1406   currScope().AddSourceRange(source);
1407 }
1408 
1409 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1410   if (NeedsScope(x)) {
1411     PushScope(Scope::Kind::OpenACCConstruct, nullptr);
1412   }
1413   return true;
1414 }
1415 
1416 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1417   if (NeedsScope(x)) {
1418     PopScope();
1419   }
1420 }
1421 
1422 bool AccVisitor::Pre(const parser::OpenACCCombinedConstruct &x) {
1423   PushScope(Scope::Kind::OpenACCConstruct, nullptr);
1424   return true;
1425 }
1426 
1427 void AccVisitor::Post(const parser::OpenACCCombinedConstruct &x) { PopScope(); }
1428 
1429 // Create scopes for OpenMP constructs
1430 class OmpVisitor : public virtual DeclarationVisitor {
1431 public:
1432   void AddOmpSourceRange(const parser::CharBlock &);
1433 
1434   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1435 
1436   bool Pre(const parser::OpenMPRequiresConstruct &x) {
1437     AddOmpSourceRange(x.source);
1438     return true;
1439   }
1440   bool Pre(const parser::OmpSimpleStandaloneDirective &x) {
1441     AddOmpSourceRange(x.source);
1442     return true;
1443   }
1444   bool Pre(const parser::OpenMPBlockConstruct &);
1445   void Post(const parser::OpenMPBlockConstruct &);
1446   bool Pre(const parser::OmpBeginBlockDirective &x) {
1447     AddOmpSourceRange(x.source);
1448     return true;
1449   }
1450   void Post(const parser::OmpBeginBlockDirective &) {
1451     messageHandler().set_currStmtSource(std::nullopt);
1452   }
1453   bool Pre(const parser::OmpEndBlockDirective &x) {
1454     AddOmpSourceRange(x.source);
1455     return true;
1456   }
1457   void Post(const parser::OmpEndBlockDirective &) {
1458     messageHandler().set_currStmtSource(std::nullopt);
1459   }
1460 
1461   bool Pre(const parser::OpenMPLoopConstruct &) {
1462     PushScope(Scope::Kind::OtherConstruct, nullptr);
1463     return true;
1464   }
1465   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1466   bool Pre(const parser::OmpBeginLoopDirective &x) {
1467     AddOmpSourceRange(x.source);
1468     return true;
1469   }
1470   void Post(const parser::OmpBeginLoopDirective &) {
1471     messageHandler().set_currStmtSource(std::nullopt);
1472   }
1473   bool Pre(const parser::OmpEndLoopDirective &x) {
1474     AddOmpSourceRange(x.source);
1475     return true;
1476   }
1477   void Post(const parser::OmpEndLoopDirective &) {
1478     messageHandler().set_currStmtSource(std::nullopt);
1479   }
1480 
1481   bool Pre(const parser::OpenMPSectionsConstruct &) {
1482     PushScope(Scope::Kind::OtherConstruct, nullptr);
1483     return true;
1484   }
1485   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1486   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1487     AddOmpSourceRange(x.source);
1488     return true;
1489   }
1490   void Post(const parser::OmpBeginSectionsDirective &) {
1491     messageHandler().set_currStmtSource(std::nullopt);
1492   }
1493   bool Pre(const parser::OmpEndSectionsDirective &x) {
1494     AddOmpSourceRange(x.source);
1495     return true;
1496   }
1497   void Post(const parser::OmpEndSectionsDirective &) {
1498     messageHandler().set_currStmtSource(std::nullopt);
1499   }
1500   bool Pre(const parser::OmpCriticalDirective &x) {
1501     AddOmpSourceRange(x.source);
1502     return true;
1503   }
1504   void Post(const parser::OmpCriticalDirective &) {
1505     messageHandler().set_currStmtSource(std::nullopt);
1506   }
1507   bool Pre(const parser::OmpEndCriticalDirective &x) {
1508     AddOmpSourceRange(x.source);
1509     return true;
1510   }
1511   void Post(const parser::OmpEndCriticalDirective &) {
1512     messageHandler().set_currStmtSource(std::nullopt);
1513   }
1514   bool Pre(const parser::OpenMPThreadprivate &) {
1515     SkipImplicitTyping(true);
1516     return true;
1517   }
1518   void Post(const parser::OpenMPThreadprivate &) { SkipImplicitTyping(false); }
1519   bool Pre(const parser::OpenMPDeclareTargetConstruct &) {
1520     SkipImplicitTyping(true);
1521     return true;
1522   }
1523   void Post(const parser::OpenMPDeclareTargetConstruct &) {
1524     SkipImplicitTyping(false);
1525   }
1526   bool Pre(const parser::OpenMPDeclarativeAllocate &) {
1527     SkipImplicitTyping(true);
1528     return true;
1529   }
1530   void Post(const parser::OpenMPDeclarativeAllocate &) {
1531     SkipImplicitTyping(false);
1532   }
1533   bool Pre(const parser::OpenMPDeclarativeConstruct &x) {
1534     AddOmpSourceRange(x.source);
1535     return true;
1536   }
1537   void Post(const parser::OpenMPDeclarativeConstruct &) {
1538     messageHandler().set_currStmtSource(std::nullopt);
1539   }
1540   bool Pre(const parser::OpenMPAtomicConstruct &x) {
1541     return common::visit(common::visitors{[&](const auto &u) -> bool {
1542       AddOmpSourceRange(u.source);
1543       return true;
1544     }},
1545         x.u);
1546   }
1547   void Post(const parser::OpenMPAtomicConstruct &) {
1548     messageHandler().set_currStmtSource(std::nullopt);
1549   }
1550 };
1551 
1552 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1553   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1554   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1555   switch (beginDir.v) {
1556   case llvm::omp::Directive::OMPD_master:
1557   case llvm::omp::Directive::OMPD_ordered:
1558   case llvm::omp::Directive::OMPD_taskgroup:
1559     return false;
1560   default:
1561     return true;
1562   }
1563 }
1564 
1565 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1566   messageHandler().set_currStmtSource(source);
1567   currScope().AddSourceRange(source);
1568 }
1569 
1570 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1571   if (NeedsScope(x)) {
1572     PushScope(Scope::Kind::OtherConstruct, nullptr);
1573   }
1574   return true;
1575 }
1576 
1577 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1578   if (NeedsScope(x)) {
1579     PopScope();
1580   }
1581 }
1582 
1583 // Walk the parse tree and resolve names to symbols.
1584 class ResolveNamesVisitor : public virtual ScopeHandler,
1585                             public ModuleVisitor,
1586                             public SubprogramVisitor,
1587                             public ConstructVisitor,
1588                             public OmpVisitor,
1589                             public AccVisitor {
1590 public:
1591   using AccVisitor::Post;
1592   using AccVisitor::Pre;
1593   using ArraySpecVisitor::Post;
1594   using ConstructVisitor::Post;
1595   using ConstructVisitor::Pre;
1596   using DeclarationVisitor::Post;
1597   using DeclarationVisitor::Pre;
1598   using ImplicitRulesVisitor::Post;
1599   using ImplicitRulesVisitor::Pre;
1600   using InterfaceVisitor::Post;
1601   using InterfaceVisitor::Pre;
1602   using ModuleVisitor::Post;
1603   using ModuleVisitor::Pre;
1604   using OmpVisitor::Post;
1605   using OmpVisitor::Pre;
1606   using ScopeHandler::Post;
1607   using ScopeHandler::Pre;
1608   using SubprogramVisitor::Post;
1609   using SubprogramVisitor::Pre;
1610 
1611   ResolveNamesVisitor(
1612       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1613       : BaseVisitor{context, *this, rules}, topScope_{top} {
1614     PushScope(top);
1615   }
1616 
1617   Scope &topScope() const { return topScope_; }
1618 
1619   // Default action for a parse tree node is to visit children.
1620   template <typename T> bool Pre(const T &) { return true; }
1621   template <typename T> void Post(const T &) {}
1622 
1623   bool Pre(const parser::SpecificationPart &);
1624   bool Pre(const parser::Program &);
1625   void Post(const parser::Program &);
1626   bool Pre(const parser::ImplicitStmt &);
1627   void Post(const parser::PointerObject &);
1628   void Post(const parser::AllocateObject &);
1629   bool Pre(const parser::PointerAssignmentStmt &);
1630   void Post(const parser::Designator &);
1631   void Post(const parser::SubstringInquiry &);
1632   template <typename A, typename B>
1633   void Post(const parser::LoopBounds<A, B> &x) {
1634     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1635   }
1636   void Post(const parser::ProcComponentRef &);
1637   bool Pre(const parser::FunctionReference &);
1638   bool Pre(const parser::CallStmt &);
1639   bool Pre(const parser::ImportStmt &);
1640   void Post(const parser::TypeGuardStmt &);
1641   bool Pre(const parser::StmtFunctionStmt &);
1642   bool Pre(const parser::DefinedOpName &);
1643   bool Pre(const parser::ProgramUnit &);
1644   void Post(const parser::AssignStmt &);
1645   void Post(const parser::AssignedGotoStmt &);
1646   void Post(const parser::CompilerDirective &);
1647 
1648   // These nodes should never be reached: they are handled in ProgramUnit
1649   bool Pre(const parser::MainProgram &) {
1650     llvm_unreachable("This node is handled in ProgramUnit");
1651   }
1652   bool Pre(const parser::FunctionSubprogram &) {
1653     llvm_unreachable("This node is handled in ProgramUnit");
1654   }
1655   bool Pre(const parser::SubroutineSubprogram &) {
1656     llvm_unreachable("This node is handled in ProgramUnit");
1657   }
1658   bool Pre(const parser::SeparateModuleSubprogram &) {
1659     llvm_unreachable("This node is handled in ProgramUnit");
1660   }
1661   bool Pre(const parser::Module &) {
1662     llvm_unreachable("This node is handled in ProgramUnit");
1663   }
1664   bool Pre(const parser::Submodule &) {
1665     llvm_unreachable("This node is handled in ProgramUnit");
1666   }
1667   bool Pre(const parser::BlockData &) {
1668     llvm_unreachable("This node is handled in ProgramUnit");
1669   }
1670 
1671   void NoteExecutablePartCall(Symbol::Flag, SourceName, bool hasCUDAChevrons);
1672 
1673   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1674 
1675 private:
1676   // Kind of procedure we are expecting to see in a ProcedureDesignator
1677   std::optional<Symbol::Flag> expectedProcFlag_;
1678   std::optional<SourceName> prevImportStmt_;
1679   Scope &topScope_;
1680 
1681   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1682   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1683   void CreateObjectSymbols(const std::list<parser::ObjectDecl> &, Attr);
1684   void CreateGeneric(const parser::GenericSpec &);
1685   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1686   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1687   void CheckImports();
1688   void CheckImport(const SourceName &, const SourceName &);
1689   void HandleCall(Symbol::Flag, const parser::Call &);
1690   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1691   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1692   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1693   void ResolveSpecificationParts(ProgramTree &);
1694   void AddSubpNames(ProgramTree &);
1695   bool BeginScopeForNode(const ProgramTree &);
1696   void EndScopeForNode(const ProgramTree &);
1697   void FinishSpecificationParts(const ProgramTree &);
1698   void FinishExecutionParts(const ProgramTree &);
1699   void FinishDerivedTypeInstantiation(Scope &);
1700   void ResolveExecutionParts(const ProgramTree &);
1701   void UseCUDABuiltinNames();
1702   void HandleDerivedTypesInImplicitStmts(const parser::ImplicitPart &,
1703       const std::list<parser::DeclarationConstruct> &);
1704 };
1705 
1706 // ImplicitRules implementation
1707 
1708 bool ImplicitRules::isImplicitNoneType() const {
1709   if (isImplicitNoneType_) {
1710     return true;
1711   } else if (map_.empty() && inheritFromParent_) {
1712     return parent_->isImplicitNoneType();
1713   } else {
1714     return false; // default if not specified
1715   }
1716 }
1717 
1718 bool ImplicitRules::isImplicitNoneExternal() const {
1719   if (isImplicitNoneExternal_) {
1720     return true;
1721   } else if (inheritFromParent_) {
1722     return parent_->isImplicitNoneExternal();
1723   } else {
1724     return false; // default if not specified
1725   }
1726 }
1727 
1728 const DeclTypeSpec *ImplicitRules::GetType(
1729     SourceName name, bool respectImplicitNoneType) const {
1730   char ch{name.begin()[0]};
1731   if (isImplicitNoneType_ && respectImplicitNoneType) {
1732     return nullptr;
1733   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1734     return &*it->second;
1735   } else if (inheritFromParent_) {
1736     return parent_->GetType(name, respectImplicitNoneType);
1737   } else if (ch >= 'i' && ch <= 'n') {
1738     return &context_.MakeNumericType(TypeCategory::Integer);
1739   } else if (ch >= 'a' && ch <= 'z') {
1740     return &context_.MakeNumericType(TypeCategory::Real);
1741   } else {
1742     return nullptr;
1743   }
1744 }
1745 
1746 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1747     parser::Location fromLetter, parser::Location toLetter) {
1748   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1749     auto res{map_.emplace(ch, type)};
1750     if (!res.second) {
1751       context_.Say(parser::CharBlock{fromLetter},
1752           "More than one implicit type specified for '%c'"_err_en_US, ch);
1753     }
1754     if (ch == *toLetter) {
1755       break;
1756     }
1757   }
1758 }
1759 
1760 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1761 // Return '\0' for the char after 'z'.
1762 char ImplicitRules::Incr(char ch) {
1763   switch (ch) {
1764   case 'i':
1765     return 'j';
1766   case 'r':
1767     return 's';
1768   case 'z':
1769     return '\0';
1770   default:
1771     return ch + 1;
1772   }
1773 }
1774 
1775 llvm::raw_ostream &operator<<(
1776     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1777   o << "ImplicitRules:\n";
1778   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1779     ShowImplicitRule(o, implicitRules, ch);
1780   }
1781   ShowImplicitRule(o, implicitRules, '_');
1782   ShowImplicitRule(o, implicitRules, '$');
1783   ShowImplicitRule(o, implicitRules, '@');
1784   return o;
1785 }
1786 void ShowImplicitRule(
1787     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1788   auto it{implicitRules.map_.find(ch)};
1789   if (it != implicitRules.map_.end()) {
1790     o << "  " << ch << ": " << *it->second << '\n';
1791   }
1792 }
1793 
1794 template <typename T> void BaseVisitor::Walk(const T &x) {
1795   parser::Walk(x, *this_);
1796 }
1797 
1798 void BaseVisitor::MakePlaceholder(
1799     const parser::Name &name, MiscDetails::Kind kind) {
1800   if (!name.symbol) {
1801     name.symbol = &context_->globalScope().MakeSymbol(
1802         name.source, Attrs{}, MiscDetails{kind});
1803   }
1804 }
1805 
1806 // AttrsVisitor implementation
1807 
1808 bool AttrsVisitor::BeginAttrs() {
1809   CHECK(!attrs_ && !cudaDataAttr_);
1810   attrs_ = Attrs{};
1811   return true;
1812 }
1813 Attrs AttrsVisitor::GetAttrs() {
1814   CHECK(attrs_);
1815   return *attrs_;
1816 }
1817 Attrs AttrsVisitor::EndAttrs() {
1818   Attrs result{GetAttrs()};
1819   attrs_.reset();
1820   cudaDataAttr_.reset();
1821   passName_ = std::nullopt;
1822   bindName_.reset();
1823   isCDefined_ = false;
1824   return result;
1825 }
1826 
1827 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1828   if (!passName_) {
1829     return false;
1830   }
1831   common::visit(common::visitors{
1832                     [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1833                     [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1834                     [](auto &) { common::die("unexpected pass name"); },
1835                 },
1836       symbol.details());
1837   return true;
1838 }
1839 
1840 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1841   if ((!attrs_ || !attrs_->test(Attr::BIND_C)) &&
1842       !symbol.attrs().test(Attr::BIND_C)) {
1843     return;
1844   }
1845   symbol.SetIsCDefined(isCDefined_);
1846   std::optional<std::string> label{
1847       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1848   // 18.9.2(2): discard leading and trailing blanks
1849   if (label) {
1850     symbol.SetIsExplicitBindName(true);
1851     auto first{label->find_first_not_of(" ")};
1852     if (first == std::string::npos) {
1853       // Empty NAME= means no binding at all (18.10.2p2)
1854       return;
1855     }
1856     auto last{label->find_last_not_of(" ")};
1857     label = label->substr(first, last - first + 1);
1858   } else if (symbol.GetIsExplicitBindName()) {
1859     // don't try to override explicit binding name with default
1860     return;
1861   } else if (ClassifyProcedure(symbol) == ProcedureDefinitionClass::Internal) {
1862     // BIND(C) does not give an implicit binding label to internal procedures.
1863     return;
1864   } else {
1865     label = symbol.name().ToString();
1866   }
1867   // Checks whether a symbol has two Bind names.
1868   std::string oldBindName;
1869   if (const auto *bindName{symbol.GetBindName()}) {
1870     oldBindName = *bindName;
1871   }
1872   symbol.SetBindName(std::move(*label));
1873   if (!oldBindName.empty()) {
1874     if (const std::string * newBindName{symbol.GetBindName()}) {
1875       if (oldBindName != *newBindName) {
1876         Say(symbol.name(),
1877             "The entity '%s' has multiple BIND names ('%s' and '%s')"_err_en_US,
1878             symbol.name(), oldBindName, *newBindName);
1879       }
1880     }
1881   }
1882 }
1883 
1884 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1885   if (CheckAndSet(Attr::BIND_C)) {
1886     if (const auto &name{
1887             std::get<std::optional<parser::ScalarDefaultCharConstantExpr>>(
1888                 x.t)}) {
1889       bindName_ = EvaluateExpr(*name);
1890     }
1891     isCDefined_ = std::get<bool>(x.t);
1892   }
1893 }
1894 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1895   CheckAndSet(IntentSpecToAttr(x));
1896   return false;
1897 }
1898 bool AttrsVisitor::Pre(const parser::Pass &x) {
1899   if (CheckAndSet(Attr::PASS)) {
1900     if (x.v) {
1901       passName_ = x.v->source;
1902       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1903     }
1904   }
1905   return false;
1906 }
1907 
1908 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1909 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1910   CHECK(attrs_);
1911   if (attrs_->test(attrName)) {
1912     context().Warn(common::LanguageFeature::RedundantAttribute,
1913         currStmtSource().value(),
1914         "Attribute '%s' cannot be used more than once"_warn_en_US,
1915         AttrToString(attrName));
1916     return true;
1917   }
1918   return false;
1919 }
1920 
1921 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1922 // name attributes that cannot be used on the same declaration
1923 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1924   CHECK(attrs_);
1925   if ((attrName == attr1 && attrs_->test(attr2)) ||
1926       (attrName == attr2 && attrs_->test(attr1))) {
1927     Say(currStmtSource().value(),
1928         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1929         AttrToString(attr1), AttrToString(attr2));
1930     return true;
1931   }
1932   return false;
1933 }
1934 // C759, C1543
1935 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1936   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1937       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1938       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1939       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1940       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1941       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1942       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1943 }
1944 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1945   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1946     return false;
1947   }
1948   attrs_->set(attrName);
1949   return true;
1950 }
1951 bool AttrsVisitor::Pre(const common::CUDADataAttr x) {
1952   if (cudaDataAttr_.value_or(x) != x) {
1953     Say(currStmtSource().value(),
1954         "CUDA data attributes '%s' and '%s' may not both be specified"_err_en_US,
1955         common::EnumToString(*cudaDataAttr_), common::EnumToString(x));
1956   }
1957   cudaDataAttr_ = x;
1958   return false;
1959 }
1960 
1961 // DeclTypeSpecVisitor implementation
1962 
1963 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1964   return state_.declTypeSpec;
1965 }
1966 
1967 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1968   CHECK(!state_.expectDeclTypeSpec);
1969   CHECK(!state_.declTypeSpec);
1970   state_.expectDeclTypeSpec = true;
1971 }
1972 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1973   CHECK(state_.expectDeclTypeSpec);
1974   state_ = {};
1975 }
1976 
1977 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1978     DeclTypeSpec::Category category) {
1979   CHECK(state_.expectDeclTypeSpec);
1980   state_.derived.category = category;
1981 }
1982 
1983 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1984   BeginDeclTypeSpec();
1985   return true;
1986 }
1987 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1988   EndDeclTypeSpec();
1989 }
1990 
1991 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1992   // Record the resolved DeclTypeSpec in the parse tree for use by
1993   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1994   // The grammar ensures that it's an intrinsic or derived type spec,
1995   // not TYPE(*) or CLASS(*) or CLASS(T).
1996   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1997     switch (spec->category()) {
1998     case DeclTypeSpec::Numeric:
1999     case DeclTypeSpec::Logical:
2000     case DeclTypeSpec::Character:
2001       typeSpec.declTypeSpec = spec;
2002       break;
2003     case DeclTypeSpec::TypeDerived:
2004       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
2005         CheckForAbstractType(derived->typeSymbol()); // C703
2006         typeSpec.declTypeSpec = spec;
2007       }
2008       break;
2009     default:
2010       CRASH_NO_CASE;
2011     }
2012   }
2013 }
2014 
2015 void DeclTypeSpecVisitor::Post(
2016     const parser::IntrinsicTypeSpec::DoublePrecision &) {
2017   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
2018 }
2019 void DeclTypeSpecVisitor::Post(
2020     const parser::IntrinsicTypeSpec::DoubleComplex &) {
2021   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
2022 }
2023 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
2024   SetDeclTypeSpec(context().MakeNumericType(category, kind));
2025 }
2026 
2027 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
2028   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
2029     Say("ABSTRACT derived type may not be used here"_err_en_US);
2030   }
2031 }
2032 
2033 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
2034   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
2035 }
2036 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
2037   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
2038 }
2039 
2040 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
2041 // and save it in state_.declTypeSpec.
2042 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
2043   CHECK(state_.expectDeclTypeSpec);
2044   CHECK(!state_.declTypeSpec);
2045   state_.declTypeSpec = &declTypeSpec;
2046 }
2047 
2048 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
2049     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2050   return AnalyzeKindSelector(context(), category, kind);
2051 }
2052 
2053 // MessageHandler implementation
2054 
2055 Message &MessageHandler::Say(MessageFixedText &&msg) {
2056   return context_->Say(currStmtSource().value(), std::move(msg));
2057 }
2058 Message &MessageHandler::Say(MessageFormattedText &&msg) {
2059   return context_->Say(currStmtSource().value(), std::move(msg));
2060 }
2061 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
2062   return Say(name, std::move(msg), name);
2063 }
2064 
2065 // ImplicitRulesVisitor implementation
2066 
2067 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
2068   prevParameterStmt_ = currStmtSource();
2069 }
2070 
2071 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
2072   bool result{
2073       common::visit(common::visitors{
2074                         [&](const std::list<ImplicitNoneNameSpec> &y) {
2075                           return HandleImplicitNone(y);
2076                         },
2077                         [&](const std::list<parser::ImplicitSpec> &) {
2078                           if (prevImplicitNoneType_) {
2079                             Say("IMPLICIT statement after IMPLICIT NONE or "
2080                                 "IMPLICIT NONE(TYPE) statement"_err_en_US);
2081                             return false;
2082                           }
2083                           implicitRules_->set_isImplicitNoneType(false);
2084                           return true;
2085                         },
2086                     },
2087           x.u)};
2088   prevImplicit_ = currStmtSource();
2089   return result;
2090 }
2091 
2092 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
2093   auto loLoc{std::get<parser::Location>(x.t)};
2094   auto hiLoc{loLoc};
2095   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
2096     hiLoc = *hiLocOpt;
2097     if (*hiLoc < *loLoc) {
2098       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
2099           std::string(hiLoc, 1), std::string(loLoc, 1));
2100       return false;
2101     }
2102   }
2103   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
2104   return false;
2105 }
2106 
2107 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
2108   BeginDeclTypeSpec();
2109   set_allowForwardReferenceToDerivedType(true);
2110   return true;
2111 }
2112 
2113 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
2114   set_allowForwardReferenceToDerivedType(false);
2115   EndDeclTypeSpec();
2116 }
2117 
2118 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
2119   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
2120   prevImplicit_ = std::nullopt;
2121   prevImplicitNone_ = std::nullopt;
2122   prevImplicitNoneType_ = std::nullopt;
2123   prevParameterStmt_ = std::nullopt;
2124 }
2125 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
2126   // find or create implicit rules for this scope
2127   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
2128   SetScope(scope);
2129 }
2130 
2131 // TODO: for all of these errors, reference previous statement too
2132 bool ImplicitRulesVisitor::HandleImplicitNone(
2133     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
2134   if (prevImplicitNone_) {
2135     Say("More than one IMPLICIT NONE statement"_err_en_US);
2136     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
2137     return false;
2138   }
2139   if (prevParameterStmt_) {
2140     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
2141     return false;
2142   }
2143   prevImplicitNone_ = currStmtSource();
2144   bool implicitNoneTypeNever{
2145       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
2146   if (nameSpecs.empty()) {
2147     if (!implicitNoneTypeNever) {
2148       prevImplicitNoneType_ = currStmtSource();
2149       implicitRules_->set_isImplicitNoneType(true);
2150       if (prevImplicit_) {
2151         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
2152         return false;
2153       }
2154     }
2155   } else {
2156     int sawType{0};
2157     int sawExternal{0};
2158     for (const auto noneSpec : nameSpecs) {
2159       switch (noneSpec) {
2160       case ImplicitNoneNameSpec::External:
2161         implicitRules_->set_isImplicitNoneExternal(true);
2162         ++sawExternal;
2163         break;
2164       case ImplicitNoneNameSpec::Type:
2165         if (!implicitNoneTypeNever) {
2166           prevImplicitNoneType_ = currStmtSource();
2167           implicitRules_->set_isImplicitNoneType(true);
2168           if (prevImplicit_) {
2169             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
2170             return false;
2171           }
2172           ++sawType;
2173         }
2174         break;
2175       }
2176     }
2177     if (sawType > 1) {
2178       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
2179       return false;
2180     }
2181     if (sawExternal > 1) {
2182       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
2183       return false;
2184     }
2185   }
2186   return true;
2187 }
2188 
2189 // ArraySpecVisitor implementation
2190 
2191 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
2192   CHECK(arraySpec_.empty());
2193   arraySpec_ = AnalyzeArraySpec(context(), x);
2194 }
2195 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
2196   CHECK(arraySpec_.empty());
2197   arraySpec_ = AnalyzeArraySpec(context(), x);
2198 }
2199 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
2200   CHECK(coarraySpec_.empty());
2201   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
2202 }
2203 
2204 const ArraySpec &ArraySpecVisitor::arraySpec() {
2205   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
2206 }
2207 const ArraySpec &ArraySpecVisitor::coarraySpec() {
2208   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
2209 }
2210 void ArraySpecVisitor::BeginArraySpec() {
2211   CHECK(arraySpec_.empty());
2212   CHECK(coarraySpec_.empty());
2213   CHECK(attrArraySpec_.empty());
2214   CHECK(attrCoarraySpec_.empty());
2215 }
2216 void ArraySpecVisitor::EndArraySpec() {
2217   CHECK(arraySpec_.empty());
2218   CHECK(coarraySpec_.empty());
2219   attrArraySpec_.clear();
2220   attrCoarraySpec_.clear();
2221 }
2222 void ArraySpecVisitor::PostAttrSpec() {
2223   // Save dimension/codimension from attrs so we can process array/coarray-spec
2224   // on the entity-decl
2225   if (!arraySpec_.empty()) {
2226     if (attrArraySpec_.empty()) {
2227       attrArraySpec_ = arraySpec_;
2228       arraySpec_.clear();
2229     } else {
2230       Say(currStmtSource().value(),
2231           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
2232     }
2233   }
2234   if (!coarraySpec_.empty()) {
2235     if (attrCoarraySpec_.empty()) {
2236       attrCoarraySpec_ = coarraySpec_;
2237       coarraySpec_.clear();
2238     } else {
2239       Say(currStmtSource().value(),
2240           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
2241     }
2242   }
2243 }
2244 
2245 // FuncResultStack implementation
2246 
2247 FuncResultStack::~FuncResultStack() { CHECK(stack_.empty()); }
2248 
2249 void FuncResultStack::CompleteFunctionResultType() {
2250   // If the function has a type in the prefix, process it now.
2251   FuncInfo *info{Top()};
2252   if (info && &info->scope == &scopeHandler_.currScope()) {
2253     if (info->parsedType && info->resultSymbol) {
2254       scopeHandler_.messageHandler().set_currStmtSource(info->source);
2255       if (const auto *type{
2256               scopeHandler_.ProcessTypeSpec(*info->parsedType, true)}) {
2257         Symbol &symbol{*info->resultSymbol};
2258         if (!scopeHandler_.context().HasError(symbol)) {
2259           if (symbol.GetType()) {
2260             scopeHandler_.Say(symbol.name(),
2261                 "Function cannot have both an explicit type prefix and a RESULT suffix"_err_en_US);
2262             scopeHandler_.context().SetError(symbol);
2263           } else {
2264             symbol.SetType(*type);
2265           }
2266         }
2267       }
2268       info->parsedType = nullptr;
2269     }
2270   }
2271 }
2272 
2273 // Called from ConvertTo{Object/Proc}Entity to cope with any appearance
2274 // of the function result in a specification expression.
2275 void FuncResultStack::CompleteTypeIfFunctionResult(Symbol &symbol) {
2276   if (FuncInfo * info{Top()}) {
2277     if (info->resultSymbol == &symbol) {
2278       CompleteFunctionResultType();
2279     }
2280   }
2281 }
2282 
2283 void FuncResultStack::Pop() {
2284   if (!stack_.empty() && &stack_.back().scope == &scopeHandler_.currScope()) {
2285     stack_.pop_back();
2286   }
2287 }
2288 
2289 // ScopeHandler implementation
2290 
2291 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
2292   SayAlreadyDeclared(name.source, prev);
2293 }
2294 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
2295   if (context().HasError(prev)) {
2296     // don't report another error about prev
2297   } else {
2298     if (const auto *details{prev.detailsIf<UseDetails>()}) {
2299       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
2300           .Attach(details->location(),
2301               "It is use-associated with '%s' in module '%s'"_en_US,
2302               details->symbol().name(), GetUsedModule(*details).name());
2303     } else {
2304       SayAlreadyDeclared(name, prev.name());
2305     }
2306     context().SetError(prev);
2307   }
2308 }
2309 void ScopeHandler::SayAlreadyDeclared(
2310     const SourceName &name1, const SourceName &name2) {
2311   if (name1.begin() < name2.begin()) {
2312     SayAlreadyDeclared(name2, name1);
2313   } else {
2314     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
2315         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
2316   }
2317 }
2318 
2319 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
2320     MessageFixedText &&msg1, Message &&msg2) {
2321   bool isFatal{msg1.IsFatal()};
2322   Say(name, std::move(msg1), symbol.name()).Attach(std::move(msg2));
2323   context().SetError(symbol, isFatal);
2324 }
2325 
2326 template <typename... A>
2327 Message &ScopeHandler::SayWithDecl(const parser::Name &name, Symbol &symbol,
2328     MessageFixedText &&msg, A &&...args) {
2329   auto &message{
2330       Say(name.source, std::move(msg), symbol.name(), std::forward<A>(args)...)
2331           .Attach(symbol.name(),
2332               symbol.test(Symbol::Flag::Implicit)
2333                   ? "Implicit declaration of '%s'"_en_US
2334                   : "Declaration of '%s'"_en_US,
2335               name.source)};
2336   if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
2337     if (auto usedAsProc{proc->usedAsProcedureHere()}) {
2338       if (usedAsProc->begin() != symbol.name().begin()) {
2339         message.Attach(*usedAsProc, "Referenced as a procedure"_en_US);
2340       }
2341     }
2342   }
2343   return message;
2344 }
2345 
2346 void ScopeHandler::SayLocalMustBeVariable(
2347     const parser::Name &name, Symbol &symbol) {
2348   SayWithDecl(name, symbol,
2349       "The name '%s' must be a variable to appear"
2350       " in a locality-spec"_err_en_US);
2351 }
2352 
2353 Message &ScopeHandler::SayDerivedType(
2354     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2355   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2356   return Say(name, std::move(msg), name, typeSymbol.name())
2357       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2358           typeSymbol.name());
2359 }
2360 Message &ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2361     const SourceName &name2, MessageFixedText &&msg2) {
2362   return Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2363 }
2364 Message &ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2365     Symbol &symbol, MessageFixedText &&msg2) {
2366   bool isFatal{msg1.IsFatal()};
2367   Message &result{Say2(name, std::move(msg1), symbol.name(), std::move(msg2))};
2368   context().SetError(symbol, isFatal);
2369   return result;
2370 }
2371 Message &ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2372     Symbol &symbol, MessageFixedText &&msg2) {
2373   bool isFatal{msg1.IsFatal()};
2374   Message &result{
2375       Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2))};
2376   context().SetError(symbol, isFatal);
2377   return result;
2378 }
2379 
2380 // This is essentially GetProgramUnitContaining(), but it can return
2381 // a mutable Scope &, it ignores statement functions, and it fails
2382 // gracefully for error recovery (returning the original Scope).
2383 template <typename T> static T &GetInclusiveScope(T &scope) {
2384   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2385     switch (s->kind()) {
2386     case Scope::Kind::Module:
2387     case Scope::Kind::MainProgram:
2388     case Scope::Kind::Subprogram:
2389     case Scope::Kind::BlockData:
2390       if (!s->IsStmtFunction()) {
2391         return *s;
2392       }
2393       break;
2394     default:;
2395     }
2396   }
2397   return scope;
2398 }
2399 
2400 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2401 
2402 Scope *ScopeHandler::GetHostProcedure() {
2403   Scope &parent{InclusiveScope().parent()};
2404   switch (parent.kind()) {
2405   case Scope::Kind::Subprogram:
2406     return &parent;
2407   case Scope::Kind::MainProgram:
2408     return &parent;
2409   default:
2410     return nullptr;
2411   }
2412 }
2413 
2414 Scope &ScopeHandler::NonDerivedTypeScope() {
2415   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2416 }
2417 
2418 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2419   PushScope(currScope().MakeScope(kind, symbol));
2420 }
2421 void ScopeHandler::PushScope(Scope &scope) {
2422   currScope_ = &scope;
2423   auto kind{currScope_->kind()};
2424   if (kind != Scope::Kind::BlockConstruct &&
2425       kind != Scope::Kind::OtherConstruct) {
2426     BeginScope(scope);
2427   }
2428   // The name of a module or submodule cannot be "used" in its scope,
2429   // as we read 19.3.1(2), so we allow the name to be used as a local
2430   // identifier in the module or submodule too.  Same with programs
2431   // (14.1(3)) and BLOCK DATA.
2432   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2433       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2434     if (auto *symbol{scope.symbol()}) {
2435       // Create a dummy symbol so we can't create another one with the same
2436       // name. It might already be there if we previously pushed the scope.
2437       SourceName name{symbol->name()};
2438       if (!FindInScope(scope, name)) {
2439         auto &newSymbol{MakeSymbol(name)};
2440         if (kind == Scope::Kind::Subprogram) {
2441           // Allow for recursive references.  If this symbol is a function
2442           // without an explicit RESULT(), this new symbol will be discarded
2443           // and replaced with an object of the same name.
2444           newSymbol.set_details(HostAssocDetails{*symbol});
2445         } else {
2446           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2447         }
2448       }
2449     }
2450   }
2451 }
2452 void ScopeHandler::PopScope() {
2453   CHECK(currScope_ && !currScope_->IsGlobal());
2454   // Entities that are not yet classified as objects or procedures are now
2455   // assumed to be objects.
2456   // TODO: Statement functions
2457   for (auto &pair : currScope()) {
2458     ConvertToObjectEntity(*pair.second);
2459   }
2460   funcResultStack_.Pop();
2461   // If popping back into a global scope, pop back to the main global scope.
2462   SetScope(currScope_->parent().IsGlobal() ? context().globalScope()
2463                                            : currScope_->parent());
2464 }
2465 void ScopeHandler::SetScope(Scope &scope) {
2466   currScope_ = &scope;
2467   ImplicitRulesVisitor::SetScope(InclusiveScope());
2468 }
2469 
2470 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2471   return FindSymbol(currScope(), name);
2472 }
2473 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2474   if (scope.IsDerivedType()) {
2475     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2476       if (symbol->has<TypeParamDetails>()) {
2477         return Resolve(name, symbol);
2478       }
2479     }
2480     return FindSymbol(scope.parent(), name);
2481   } else {
2482     // In EQUIVALENCE statements only resolve names in the local scope, see
2483     // 19.5.1.4, paragraph 2, item (10)
2484     return Resolve(name,
2485         inEquivalenceStmt_ ? FindInScope(scope, name)
2486                            : scope.FindSymbol(name.source));
2487   }
2488 }
2489 
2490 Symbol &ScopeHandler::MakeSymbol(
2491     Scope &scope, const SourceName &name, Attrs attrs) {
2492   if (Symbol * symbol{FindInScope(scope, name)}) {
2493     CheckDuplicatedAttrs(name, *symbol, attrs);
2494     SetExplicitAttrs(*symbol, attrs);
2495     return *symbol;
2496   } else {
2497     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2498     CHECK(pair.second); // name was not found, so must be able to add
2499     return *pair.first->second;
2500   }
2501 }
2502 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2503   return MakeSymbol(currScope(), name, attrs);
2504 }
2505 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2506   return Resolve(name, MakeSymbol(name.source, attrs));
2507 }
2508 Symbol &ScopeHandler::MakeHostAssocSymbol(
2509     const parser::Name &name, const Symbol &hostSymbol) {
2510   Symbol &symbol{*NonDerivedTypeScope()
2511                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2512                       .first->second};
2513   name.symbol = &symbol;
2514   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2515   // These attributes can be redundantly reapplied without error
2516   // on the host-associated name, at most once (C815).
2517   symbol.implicitAttrs() =
2518       symbol.attrs() & Attrs{Attr::ASYNCHRONOUS, Attr::VOLATILE};
2519   // SAVE statement in the inner scope will create a new symbol.
2520   // If the host variable is used via host association,
2521   // we have to propagate whether SAVE is implicit in the host scope.
2522   // Otherwise, verifications that do not allow explicit SAVE
2523   // attribute would fail.
2524   symbol.implicitAttrs() |= hostSymbol.implicitAttrs() & Attrs{Attr::SAVE};
2525   symbol.flags() = hostSymbol.flags();
2526   return symbol;
2527 }
2528 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2529   CHECK(!FindInScope(name));
2530   return MakeSymbol(currScope(), name, symbol.attrs());
2531 }
2532 
2533 // Look for name only in scope, not in enclosing scopes.
2534 
2535 Symbol *ScopeHandler::FindInScope(
2536     const Scope &scope, const parser::Name &name) {
2537   return Resolve(name, FindInScope(scope, name.source));
2538 }
2539 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2540   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2541   for (const std::string &n : GetAllNames(context(), name)) {
2542     auto it{scope.find(SourceName{n})};
2543     if (it != scope.end()) {
2544       return &*it->second;
2545     }
2546   }
2547   return nullptr;
2548 }
2549 
2550 // Find a component or type parameter by name in a derived type or its parents.
2551 Symbol *ScopeHandler::FindInTypeOrParents(
2552     const Scope &scope, const parser::Name &name) {
2553   return Resolve(name, scope.FindComponent(name.source));
2554 }
2555 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2556   return FindInTypeOrParents(currScope(), name);
2557 }
2558 Symbol *ScopeHandler::FindInScopeOrBlockConstructs(
2559     const Scope &scope, SourceName name) {
2560   if (Symbol * symbol{FindInScope(scope, name)}) {
2561     return symbol;
2562   }
2563   for (const Scope &child : scope.children()) {
2564     if (child.kind() == Scope::Kind::BlockConstruct) {
2565       if (Symbol * symbol{FindInScopeOrBlockConstructs(child, name)}) {
2566         return symbol;
2567       }
2568     }
2569   }
2570   return nullptr;
2571 }
2572 
2573 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2574   currScope().erase(name.source);
2575   name.symbol = nullptr;
2576 }
2577 
2578 static bool NeedsType(const Symbol &symbol) {
2579   return !symbol.GetType() &&
2580       common::visit(common::visitors{
2581                         [](const EntityDetails &) { return true; },
2582                         [](const ObjectEntityDetails &) { return true; },
2583                         [](const AssocEntityDetails &) { return true; },
2584                         [&](const ProcEntityDetails &p) {
2585                           return symbol.test(Symbol::Flag::Function) &&
2586                               !symbol.attrs().test(Attr::INTRINSIC) &&
2587                               !p.type() && !p.procInterface();
2588                         },
2589                         [](const auto &) { return false; },
2590                     },
2591           symbol.details());
2592 }
2593 
2594 void ScopeHandler::ApplyImplicitRules(
2595     Symbol &symbol, bool allowForwardReference) {
2596   funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2597   if (context().HasError(symbol) || !NeedsType(symbol)) {
2598     return;
2599   }
2600   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2601     if (!skipImplicitTyping_) {
2602       symbol.set(Symbol::Flag::Implicit);
2603       symbol.SetType(*type);
2604     }
2605     return;
2606   }
2607   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2608     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2609     if (symbol.test(Symbol::Flag::Function)) {
2610       functionOrSubroutineFlag = Symbol::Flag::Function;
2611     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2612       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2613     }
2614     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2615       // type will be determined in expression semantics
2616       AcquireIntrinsicProcedureFlags(symbol);
2617       return;
2618     }
2619   }
2620   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2621     return;
2622   }
2623   if (const auto *entity{symbol.detailsIf<EntityDetails>()};
2624       entity && entity->isDummy()) {
2625     // Dummy argument, no declaration or reference; if it turns
2626     // out to be a subroutine, it's fine, and if it is a function
2627     // or object, it'll be caught later.
2628     return;
2629   }
2630   if (deferImplicitTyping_) {
2631     return;
2632   }
2633   if (!context().HasError(symbol)) {
2634     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2635     context().SetError(symbol);
2636   }
2637 }
2638 
2639 // Extension: Allow forward references to scalar integer dummy arguments
2640 // or variables in COMMON to appear in specification expressions under
2641 // IMPLICIT NONE(TYPE) when what would otherwise have been their implicit
2642 // type is default INTEGER.
2643 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2644   if (!inSpecificationPart_ || context().HasError(symbol) ||
2645       !(IsDummy(symbol) || FindCommonBlockContaining(symbol)) ||
2646       symbol.Rank() != 0 ||
2647       !context().languageFeatures().IsEnabled(
2648           common::LanguageFeature::ForwardRefImplicitNone)) {
2649     return false;
2650   }
2651   const DeclTypeSpec *type{
2652       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2653   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2654     return false;
2655   }
2656   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2657   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2658     return false;
2659   }
2660   if (!ConvertToObjectEntity(symbol)) {
2661     return false;
2662   }
2663   // TODO: check no INTENT(OUT) if dummy?
2664   context().Warn(common::LanguageFeature::ForwardRefImplicitNone, symbol.name(),
2665       "'%s' was used without (or before) being explicitly typed"_warn_en_US,
2666       symbol.name());
2667   symbol.set(Symbol::Flag::Implicit);
2668   symbol.SetType(*type);
2669   return true;
2670 }
2671 
2672 // Ensure that the symbol for an intrinsic procedure is marked with
2673 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2674 // appropriate.
2675 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2676   SetImplicitAttr(symbol, Attr::INTRINSIC);
2677   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2678   case evaluate::IntrinsicClass::elementalFunction:
2679   case evaluate::IntrinsicClass::elementalSubroutine:
2680     SetExplicitAttr(symbol, Attr::ELEMENTAL);
2681     SetExplicitAttr(symbol, Attr::PURE);
2682     break;
2683   case evaluate::IntrinsicClass::impureSubroutine:
2684     break;
2685   default:
2686     SetExplicitAttr(symbol, Attr::PURE);
2687   }
2688 }
2689 
2690 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2691     Symbol &symbol, bool respectImplicitNoneType) {
2692   const Scope *scope{&symbol.owner()};
2693   if (scope->IsGlobal()) {
2694     scope = &currScope();
2695   }
2696   scope = &GetInclusiveScope(*scope);
2697   const auto *type{implicitRulesMap_->at(scope).GetType(
2698       symbol.name(), respectImplicitNoneType)};
2699   if (type) {
2700     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2701       // Resolve any forward-referenced derived type; a quick no-op else.
2702       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2703       instantiatable.Instantiate(currScope());
2704     }
2705   }
2706   return type;
2707 }
2708 
2709 void ScopeHandler::CheckEntryDummyUse(SourceName source, Symbol *symbol) {
2710   if (!inSpecificationPart_ && symbol &&
2711       symbol->test(Symbol::Flag::EntryDummyArgument)) {
2712     Say(source,
2713         "Dummy argument '%s' may not be used before its ENTRY statement"_err_en_US,
2714         symbol->name());
2715     symbol->set(Symbol::Flag::EntryDummyArgument, false);
2716   }
2717 }
2718 
2719 // Convert symbol to be a ObjectEntity or return false if it can't be.
2720 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2721   if (symbol.has<ObjectEntityDetails>()) {
2722     // nothing to do
2723   } else if (symbol.has<UnknownDetails>()) {
2724     // These are attributes that a name could have picked up from
2725     // an attribute statement or type declaration statement.
2726     if (symbol.attrs().HasAny({Attr::EXTERNAL, Attr::INTRINSIC})) {
2727       return false;
2728     }
2729     symbol.set_details(ObjectEntityDetails{});
2730   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2731     if (symbol.attrs().HasAny({Attr::EXTERNAL, Attr::INTRINSIC})) {
2732       return false;
2733     }
2734     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2735     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2736   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2737     return useDetails->symbol().has<ObjectEntityDetails>();
2738   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2739     return hostDetails->symbol().has<ObjectEntityDetails>();
2740   } else {
2741     return false;
2742   }
2743   return true;
2744 }
2745 // Convert symbol to be a ProcEntity or return false if it can't be.
2746 bool ScopeHandler::ConvertToProcEntity(
2747     Symbol &symbol, std::optional<SourceName> usedHere) {
2748   if (symbol.has<ProcEntityDetails>()) {
2749   } else if (symbol.has<UnknownDetails>()) {
2750     symbol.set_details(ProcEntityDetails{});
2751   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2752     if (IsFunctionResult(symbol) &&
2753         !(IsPointer(symbol) && symbol.attrs().test(Attr::EXTERNAL))) {
2754       // Don't turn function result into a procedure pointer unless both
2755       // POINTER and EXTERNAL
2756       return false;
2757     }
2758     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2759     symbol.set_details(ProcEntityDetails{std::move(*details)});
2760     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2761       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2762       symbol.set(Symbol::Flag::Function);
2763     }
2764   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2765     return useDetails->symbol().has<ProcEntityDetails>();
2766   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2767     return hostDetails->symbol().has<ProcEntityDetails>();
2768   } else {
2769     return false;
2770   }
2771   auto &proc{symbol.get<ProcEntityDetails>()};
2772   if (usedHere && !proc.usedAsProcedureHere()) {
2773     proc.set_usedAsProcedureHere(*usedHere);
2774   }
2775   return true;
2776 }
2777 
2778 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2779     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2780   KindExpr value{GetKindParamExpr(category, kind)};
2781   if (auto known{evaluate::ToInt64(value)}) {
2782     return MakeNumericType(category, static_cast<int>(*known));
2783   } else {
2784     return currScope_->MakeNumericType(category, std::move(value));
2785   }
2786 }
2787 
2788 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2789     TypeCategory category, int kind) {
2790   return context().MakeNumericType(category, kind);
2791 }
2792 
2793 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2794     const std::optional<parser::KindSelector> &kind) {
2795   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2796   if (auto known{evaluate::ToInt64(value)}) {
2797     return MakeLogicalType(static_cast<int>(*known));
2798   } else {
2799     return currScope_->MakeLogicalType(std::move(value));
2800   }
2801 }
2802 
2803 const DeclTypeSpec &ScopeHandler::MakeLogicalType(int kind) {
2804   return context().MakeLogicalType(kind);
2805 }
2806 
2807 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2808   if (inSpecificationPart_ && !deferImplicitTyping_ && name.symbol) {
2809     auto kind{currScope().kind()};
2810     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2811         kind == Scope::Kind::BlockConstruct) {
2812       bool isHostAssociated{&name.symbol->owner() == &currScope()
2813               ? name.symbol->has<HostAssocDetails>()
2814               : name.symbol->owner().Contains(currScope())};
2815       if (isHostAssociated) {
2816         specPartState_.forwardRefs.insert(name.source);
2817       }
2818     }
2819   }
2820 }
2821 
2822 std::optional<SourceName> ScopeHandler::HadForwardRef(
2823     const Symbol &symbol) const {
2824   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2825   if (iter != specPartState_.forwardRefs.end()) {
2826     return *iter;
2827   }
2828   return std::nullopt;
2829 }
2830 
2831 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2832   if (!context().HasError(symbol)) {
2833     if (auto fwdRef{HadForwardRef(symbol)}) {
2834       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2835       if (outer && symbol.has<UseDetails>() &&
2836           &symbol.GetUltimate() == &outer->GetUltimate()) {
2837         // e.g. IMPORT of host's USE association
2838         return false;
2839       }
2840       Say(*fwdRef,
2841           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2842           *fwdRef)
2843           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2844       context().SetError(symbol);
2845       return true;
2846     }
2847     if ((IsDummy(symbol) || FindCommonBlockContaining(symbol)) &&
2848         isImplicitNoneType() && symbol.test(Symbol::Flag::Implicit) &&
2849         !context().HasError(symbol)) {
2850       // Dummy or COMMON was implicitly typed despite IMPLICIT NONE(TYPE) in
2851       // ApplyImplicitRules() due to use in a specification expression,
2852       // and no explicit type declaration appeared later.
2853       Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2854       context().SetError(symbol);
2855       return true;
2856     }
2857   }
2858   return false;
2859 }
2860 
2861 void ScopeHandler::MakeExternal(Symbol &symbol) {
2862   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2863     SetImplicitAttr(symbol, Attr::EXTERNAL);
2864     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2865       Say(symbol.name(),
2866           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2867           symbol.name());
2868     }
2869   }
2870 }
2871 
2872 bool ScopeHandler::CheckDuplicatedAttr(
2873     SourceName name, Symbol &symbol, Attr attr) {
2874   if (attr == Attr::SAVE) {
2875     // checked elsewhere
2876   } else if (symbol.attrs().test(attr)) { // C815
2877     if (symbol.implicitAttrs().test(attr)) {
2878       // Implied attribute is now confirmed explicitly
2879       symbol.implicitAttrs().reset(attr);
2880     } else {
2881       Say(name, "%s attribute was already specified on '%s'"_err_en_US,
2882           EnumToString(attr), name);
2883       return false;
2884     }
2885   }
2886   return true;
2887 }
2888 
2889 bool ScopeHandler::CheckDuplicatedAttrs(
2890     SourceName name, Symbol &symbol, Attrs attrs) {
2891   bool ok{true};
2892   attrs.IterateOverMembers(
2893       [&](Attr x) { ok &= CheckDuplicatedAttr(name, symbol, x); });
2894   return ok;
2895 }
2896 
2897 void ScopeHandler::SetCUDADataAttr(SourceName source, Symbol &symbol,
2898     std::optional<common::CUDADataAttr> attr) {
2899   if (attr) {
2900     ConvertToObjectEntity(symbol);
2901     if (auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
2902       if (*attr != object->cudaDataAttr().value_or(*attr)) {
2903         Say(source,
2904             "'%s' already has another CUDA data attribute ('%s')"_err_en_US,
2905             symbol.name(),
2906             std::string{common::EnumToString(*object->cudaDataAttr())}.c_str());
2907       } else {
2908         object->set_cudaDataAttr(attr);
2909       }
2910     } else {
2911       Say(source,
2912           "'%s' is not an object and may not have a CUDA data attribute"_err_en_US,
2913           symbol.name());
2914     }
2915   }
2916 }
2917 
2918 // ModuleVisitor implementation
2919 
2920 bool ModuleVisitor::Pre(const parser::Only &x) {
2921   common::visit(common::visitors{
2922                     [&](const Indirection<parser::GenericSpec> &generic) {
2923                       GenericSpecInfo genericSpecInfo{generic.value()};
2924                       AddUseOnly(genericSpecInfo.symbolName());
2925                       AddUse(genericSpecInfo);
2926                     },
2927                     [&](const parser::Name &name) {
2928                       AddUseOnly(name.source);
2929                       Resolve(name, AddUse(name.source, name.source).use);
2930                     },
2931                     [&](const parser::Rename &rename) { Walk(rename); },
2932                 },
2933       x.u);
2934   return false;
2935 }
2936 
2937 void ModuleVisitor::CollectUseRenames(const parser::UseStmt &useStmt) {
2938   auto doRename{[&](const parser::Rename &rename) {
2939     if (const auto *names{std::get_if<parser::Rename::Names>(&rename.u)}) {
2940       AddUseRename(std::get<1>(names->t).source, useStmt.moduleName.source);
2941     }
2942   }};
2943   common::visit(
2944       common::visitors{
2945           [&](const std::list<parser::Rename> &renames) {
2946             for (const auto &rename : renames) {
2947               doRename(rename);
2948             }
2949           },
2950           [&](const std::list<parser::Only> &onlys) {
2951             for (const auto &only : onlys) {
2952               if (const auto *rename{std::get_if<parser::Rename>(&only.u)}) {
2953                 doRename(*rename);
2954               }
2955             }
2956           },
2957       },
2958       useStmt.u);
2959 }
2960 
2961 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2962   const auto &localName{std::get<0>(x.t)};
2963   const auto &useName{std::get<1>(x.t)};
2964   SymbolRename rename{AddUse(localName.source, useName.source)};
2965   Resolve(useName, rename.use);
2966   Resolve(localName, rename.local);
2967   return false;
2968 }
2969 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2970   const parser::DefinedOpName &local{std::get<0>(x.t)};
2971   const parser::DefinedOpName &use{std::get<1>(x.t)};
2972   GenericSpecInfo localInfo{local};
2973   GenericSpecInfo useInfo{use};
2974   if (IsIntrinsicOperator(context(), local.v.source)) {
2975     Say(local.v,
2976         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2977   } else if (IsLogicalConstant(context(), local.v.source)) {
2978     Say(local.v,
2979         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2980   } else {
2981     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2982     useInfo.Resolve(rename.use);
2983     localInfo.Resolve(rename.local);
2984   }
2985   return false;
2986 }
2987 
2988 // Set useModuleScope_ to the Scope of the module being used.
2989 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2990   std::optional<bool> isIntrinsic;
2991   if (x.nature) {
2992     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2993   } else if (currScope().IsModule() && currScope().symbol() &&
2994       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2995     // Intrinsic modules USE only other intrinsic modules
2996     isIntrinsic = true;
2997   }
2998   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2999   if (!useModuleScope_) {
3000     return false;
3001   }
3002   AddAndCheckModuleUse(x.moduleName.source,
3003       useModuleScope_->parent().kind() == Scope::Kind::IntrinsicModules);
3004   // use the name from this source file
3005   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
3006   return true;
3007 }
3008 
3009 void ModuleVisitor::Post(const parser::UseStmt &x) {
3010   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
3011     // Not a use-only: collect the names that were used in renames,
3012     // then add a use for each public name that was not renamed.
3013     std::set<SourceName> useNames;
3014     for (const auto &rename : *list) {
3015       common::visit(common::visitors{
3016                         [&](const parser::Rename::Names &names) {
3017                           useNames.insert(std::get<1>(names.t).source);
3018                         },
3019                         [&](const parser::Rename::Operators &ops) {
3020                           useNames.insert(std::get<1>(ops.t).v.source);
3021                         },
3022                     },
3023           rename.u);
3024     }
3025     for (const auto &[name, symbol] : *useModuleScope_) {
3026       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
3027           (!symbol->implicitAttrs().test(Attr::INTRINSIC) ||
3028               symbol->has<UseDetails>()) &&
3029           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
3030         SourceName location{x.moduleName.source};
3031         if (auto *localSymbol{FindInScope(name)}) {
3032           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
3033         } else {
3034           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
3035         }
3036       }
3037     }
3038   }
3039   useModuleScope_ = nullptr;
3040 }
3041 
3042 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
3043     const SourceName &localName, const SourceName &useName) {
3044   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
3045 }
3046 
3047 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
3048     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
3049   if (!useModuleScope_) {
3050     return {}; // error occurred finding module
3051   }
3052   if (!useSymbol) {
3053     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
3054         useModuleScope_->GetName().value());
3055     return {};
3056   }
3057   if (useSymbol->attrs().test(Attr::PRIVATE) &&
3058       !FindModuleFileContaining(currScope())) {
3059     // Privacy is not enforced in module files so that generic interfaces
3060     // can be resolved to private specific procedures in specification
3061     // expressions.
3062     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
3063         useModuleScope_->GetName().value());
3064     return {};
3065   }
3066   auto &localSymbol{MakeSymbol(localName)};
3067   DoAddUse(useName, localName, localSymbol, *useSymbol);
3068   return {&localSymbol, useSymbol};
3069 }
3070 
3071 // symbol must be either a Use or a Generic formed by merging two uses.
3072 // Convert it to a UseError with this additional location.
3073 static bool ConvertToUseError(
3074     Symbol &symbol, const SourceName &location, const Scope &module) {
3075   const auto *useDetails{symbol.detailsIf<UseDetails>()};
3076   if (!useDetails) {
3077     if (auto *genericDetails{symbol.detailsIf<GenericDetails>()}) {
3078       if (!genericDetails->uses().empty()) {
3079         useDetails = &genericDetails->uses().at(0)->get<UseDetails>();
3080       }
3081     }
3082   }
3083   if (useDetails) {
3084     symbol.set_details(
3085         UseErrorDetails{*useDetails}.add_occurrence(location, module));
3086     return true;
3087   } else {
3088     return false;
3089   }
3090 }
3091 
3092 void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
3093     Symbol &originalLocal, const Symbol &useSymbol) {
3094   Symbol *localSymbol{&originalLocal};
3095   if (auto *details{localSymbol->detailsIf<UseErrorDetails>()}) {
3096     details->add_occurrence(location, *useModuleScope_);
3097     return;
3098   }
3099   const Symbol &useUltimate{useSymbol.GetUltimate()};
3100   const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
3101   if (localSymbol->has<UnknownDetails>()) {
3102     if (useGeneric &&
3103         ((useGeneric->specific() &&
3104              IsProcedurePointer(*useGeneric->specific())) ||
3105             (useGeneric->derivedType() &&
3106                 useUltimate.name() != localSymbol->name()))) {
3107       // We are use-associating a generic that either shadows a procedure
3108       // pointer or shadows a derived type with a distinct name.
3109       // Local references that might be made to the procedure pointer should
3110       // use a UseDetails symbol for proper data addressing, and a derived
3111       // type needs to be in scope with its local name.  So create an
3112       // empty local generic now into which the use-associated generic may
3113       // be copied.
3114       localSymbol->set_details(GenericDetails{});
3115       localSymbol->get<GenericDetails>().set_kind(useGeneric->kind());
3116     } else { // just create UseDetails
3117       localSymbol->set_details(UseDetails{localName, useSymbol});
3118       localSymbol->attrs() =
3119           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE, Attr::SAVE};
3120       localSymbol->implicitAttrs() =
3121           localSymbol->attrs() & Attrs{Attr::ASYNCHRONOUS, Attr::VOLATILE};
3122       localSymbol->flags() = useSymbol.flags();
3123       return;
3124     }
3125   }
3126 
3127   Symbol &localUltimate{localSymbol->GetUltimate()};
3128   if (&localUltimate == &useUltimate) {
3129     // use-associating the same symbol again -- ok
3130     return;
3131   }
3132 
3133   // There are many possible combinations of symbol types that could arrive
3134   // with the same (local) name vie USE association from distinct modules.
3135   // Fortran allows a generic interface to share its name with a derived type,
3136   // or with the name of a non-generic procedure (which should be one of the
3137   // generic's specific procedures).  Implementing all these possibilities is
3138   // complicated.
3139   // Error cases are converted into UseErrorDetails symbols to trigger error
3140   // messages when/if bad combinations are actually used later in the program.
3141   // The error cases are:
3142   //   - two distinct derived types
3143   //   - two distinct non-generic procedures
3144   //   - a generic and a non-generic that is not already one of its specifics
3145   //   - anything other than a derived type, non-generic procedure, or
3146   //     generic procedure being combined with something other than an
3147   //     prior USE association of itself
3148   auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
3149   Symbol *localDerivedType{nullptr};
3150   if (localUltimate.has<DerivedTypeDetails>()) {
3151     localDerivedType = &localUltimate;
3152   } else if (localGeneric) {
3153     if (auto *dt{localGeneric->derivedType()};
3154         dt && !dt->attrs().test(Attr::PRIVATE)) {
3155       localDerivedType = dt;
3156     }
3157   }
3158   const Symbol *useDerivedType{nullptr};
3159   if (useUltimate.has<DerivedTypeDetails>()) {
3160     useDerivedType = &useUltimate;
3161   } else if (useGeneric) {
3162     if (const auto *dt{useGeneric->derivedType()};
3163         dt && !dt->attrs().test(Attr::PRIVATE)) {
3164       useDerivedType = dt;
3165     }
3166   }
3167 
3168   Symbol *localProcedure{nullptr};
3169   if (localGeneric) {
3170     if (localGeneric->specific() &&
3171         !localGeneric->specific()->attrs().test(Attr::PRIVATE)) {
3172       localProcedure = localGeneric->specific();
3173     }
3174   } else if (IsProcedure(localUltimate)) {
3175     localProcedure = &localUltimate;
3176   }
3177   const Symbol *useProcedure{nullptr};
3178   if (useGeneric) {
3179     if (useGeneric->specific() &&
3180         !useGeneric->specific()->attrs().test(Attr::PRIVATE)) {
3181       useProcedure = useGeneric->specific();
3182     }
3183   } else if (IsProcedure(useUltimate)) {
3184     useProcedure = &useUltimate;
3185   }
3186 
3187   // Creates a UseErrorDetails symbol in the current scope for a
3188   // current UseDetails symbol, but leaves the UseDetails in the
3189   // scope's name map.
3190   auto CreateLocalUseError{[&]() {
3191     EraseSymbol(*localSymbol);
3192     CHECK(localSymbol->has<UseDetails>());
3193     UseErrorDetails details{localSymbol->get<UseDetails>()};
3194     details.add_occurrence(location, *useModuleScope_);
3195     Symbol *newSymbol{&MakeSymbol(localName, Attrs{}, std::move(details))};
3196     // Restore *localSymbol in currScope
3197     auto iter{currScope().find(localName)};
3198     CHECK(iter != currScope().end() && &*iter->second == newSymbol);
3199     iter->second = MutableSymbolRef{*localSymbol};
3200     return newSymbol;
3201   }};
3202 
3203   // When two derived types arrived, try to combine them.
3204   const Symbol *combinedDerivedType{nullptr};
3205   if (!useDerivedType) {
3206     combinedDerivedType = localDerivedType;
3207   } else if (!localDerivedType) {
3208     if (useDerivedType->name() == localName) {
3209       combinedDerivedType = useDerivedType;
3210     } else {
3211       combinedDerivedType =
3212           &currScope().MakeSymbol(localSymbol->name(), useDerivedType->attrs(),
3213               UseDetails{localSymbol->name(), *useDerivedType});
3214     }
3215   } else if (&localDerivedType->GetUltimate() ==
3216       &useDerivedType->GetUltimate()) {
3217     combinedDerivedType = localDerivedType;
3218   } else {
3219     const Scope *localScope{localDerivedType->GetUltimate().scope()};
3220     const Scope *useScope{useDerivedType->GetUltimate().scope()};
3221     if (localScope && useScope && localScope->derivedTypeSpec() &&
3222         useScope->derivedTypeSpec() &&
3223         evaluate::AreSameDerivedType(
3224             *localScope->derivedTypeSpec(), *useScope->derivedTypeSpec())) {
3225       combinedDerivedType = localDerivedType;
3226     } else {
3227       // Create a local UseErrorDetails for the ambiguous derived type
3228       if (localGeneric) {
3229         combinedDerivedType = CreateLocalUseError();
3230       } else {
3231         ConvertToUseError(*localSymbol, location, *useModuleScope_);
3232         combinedDerivedType = localSymbol;
3233       }
3234     }
3235     if (!localGeneric && !useGeneric) {
3236       return; // both symbols are derived types; done
3237     }
3238   }
3239 
3240   auto AreSameProcedure{[&](const Symbol &p1, const Symbol &p2) {
3241     if (&p1 == &p2) {
3242       return true;
3243     } else if (p1.name() != p2.name()) {
3244       return false;
3245     } else if (p1.attrs().test(Attr::INTRINSIC) ||
3246         p2.attrs().test(Attr::INTRINSIC)) {
3247       return p1.attrs().test(Attr::INTRINSIC) &&
3248           p2.attrs().test(Attr::INTRINSIC);
3249     } else if (!IsProcedure(p1) || !IsProcedure(p2)) {
3250       return false;
3251     } else if (IsPointer(p1) || IsPointer(p2)) {
3252       return false;
3253     } else if (const auto *subp{p1.detailsIf<SubprogramDetails>()};
3254                subp && !subp->isInterface()) {
3255       return false; // defined in module, not an external
3256     } else if (const auto *subp{p2.detailsIf<SubprogramDetails>()};
3257                subp && !subp->isInterface()) {
3258       return false; // defined in module, not an external
3259     } else {
3260       // Both are external interfaces, perhaps to the same procedure
3261       auto class1{ClassifyProcedure(p1)};
3262       auto class2{ClassifyProcedure(p2)};
3263       if (class1 == ProcedureDefinitionClass::External &&
3264           class2 == ProcedureDefinitionClass::External) {
3265         auto chars1{evaluate::characteristics::Procedure::Characterize(
3266             p1, GetFoldingContext())};
3267         auto chars2{evaluate::characteristics::Procedure::Characterize(
3268             p2, GetFoldingContext())};
3269         // same procedure interface defined identically in two modules?
3270         return chars1 && chars2 && *chars1 == *chars2;
3271       } else {
3272         return false;
3273       }
3274     }
3275   }};
3276 
3277   // When two non-generic procedures arrived, try to combine them.
3278   const Symbol *combinedProcedure{nullptr};
3279   if (!localProcedure) {
3280     combinedProcedure = useProcedure;
3281   } else if (!useProcedure) {
3282     combinedProcedure = localProcedure;
3283   } else {
3284     if (AreSameProcedure(
3285             localProcedure->GetUltimate(), useProcedure->GetUltimate())) {
3286       if (!localGeneric && !useGeneric) {
3287         return; // both symbols are non-generic procedures
3288       }
3289       combinedProcedure = localProcedure;
3290     }
3291   }
3292 
3293   // Prepare to merge generics
3294   bool cantCombine{false};
3295   if (localGeneric) {
3296     if (useGeneric || useDerivedType) {
3297     } else if (&useUltimate == &BypassGeneric(localUltimate).GetUltimate()) {
3298       return; // nothing to do; used subprogram is local's specific
3299     } else if (useUltimate.attrs().test(Attr::INTRINSIC) &&
3300         useUltimate.name() == localSymbol->name()) {
3301       return; // local generic can extend intrinsic
3302     } else {
3303       for (const auto &ref : localGeneric->specificProcs()) {
3304         if (&ref->GetUltimate() == &useUltimate) {
3305           return; // used non-generic is already a specific of local generic
3306         }
3307       }
3308       cantCombine = true;
3309     }
3310   } else if (useGeneric) {
3311     if (localDerivedType) {
3312     } else if (&localUltimate == &BypassGeneric(useUltimate).GetUltimate() ||
3313         (localSymbol->attrs().test(Attr::INTRINSIC) &&
3314             localUltimate.name() == useUltimate.name())) {
3315       // Local is the specific of the used generic or an intrinsic with the
3316       // same name; replace it.
3317       EraseSymbol(*localSymbol);
3318       Symbol &newSymbol{MakeSymbol(localName,
3319           useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
3320           UseDetails{localName, useUltimate})};
3321       newSymbol.flags() = useSymbol.flags();
3322       return;
3323     } else {
3324       for (const auto &ref : useGeneric->specificProcs()) {
3325         if (&ref->GetUltimate() == &localUltimate) {
3326           return; // local non-generic is already a specific of used generic
3327         }
3328       }
3329       cantCombine = true;
3330     }
3331   } else {
3332     cantCombine = true;
3333   }
3334 
3335   // If symbols are not combinable, create a use error.
3336   if (cantCombine) {
3337     if (!ConvertToUseError(*localSymbol, location, *useModuleScope_)) {
3338       Say(location,
3339           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
3340           localName)
3341           .Attach(localSymbol->name(), "Previous declaration of '%s'"_en_US,
3342               localName);
3343     }
3344     return;
3345   }
3346 
3347   // At this point, there must be at least one generic interface.
3348   CHECK(localGeneric || (useGeneric && (localDerivedType || localProcedure)));
3349 
3350   // Ensure that a use-associated specific procedure that is a procedure
3351   // pointer is properly represented as a USE association of an entity.
3352   if (IsProcedurePointer(useProcedure)) {
3353     Symbol &combined{currScope().MakeSymbol(localSymbol->name(),
3354         useProcedure->attrs(), UseDetails{localName, *useProcedure})};
3355     combined.flags() |= useProcedure->flags();
3356     combinedProcedure = &combined;
3357   }
3358 
3359   if (localGeneric) {
3360     // Create a local copy of a previously use-associated generic so that
3361     // it can be locally extended without corrupting the original.
3362     if (localSymbol->has<UseDetails>()) {
3363       GenericDetails generic;
3364       generic.CopyFrom(DEREF(localGeneric));
3365       EraseSymbol(*localSymbol);
3366       Symbol &newSymbol{MakeSymbol(
3367           localSymbol->name(), localSymbol->attrs(), std::move(generic))};
3368       newSymbol.flags() = localSymbol->flags();
3369       localGeneric = &newSymbol.get<GenericDetails>();
3370       localGeneric->AddUse(*localSymbol);
3371       localSymbol = &newSymbol;
3372     }
3373     if (useGeneric) {
3374       // Combine two use-associated generics
3375       localSymbol->attrs() =
3376           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
3377       localSymbol->flags() = useSymbol.flags();
3378       AddGenericUse(*localGeneric, localName, useUltimate);
3379       localGeneric->clear_derivedType();
3380       localGeneric->CopyFrom(*useGeneric);
3381     }
3382     localGeneric->clear_derivedType();
3383     if (combinedDerivedType) {
3384       localGeneric->set_derivedType(*const_cast<Symbol *>(combinedDerivedType));
3385     }
3386     localGeneric->clear_specific();
3387     if (combinedProcedure) {
3388       localGeneric->set_specific(*const_cast<Symbol *>(combinedProcedure));
3389     }
3390   } else {
3391     CHECK(localSymbol->has<UseDetails>());
3392     // Create a local copy of the use-associated generic, then extend it
3393     // with the combined derived type &/or non-generic procedure.
3394     GenericDetails generic;
3395     generic.CopyFrom(*useGeneric);
3396     EraseSymbol(*localSymbol);
3397     Symbol &newSymbol{MakeSymbol(localName,
3398         useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
3399         std::move(generic))};
3400     newSymbol.flags() = useUltimate.flags();
3401     auto &newUseGeneric{newSymbol.get<GenericDetails>()};
3402     AddGenericUse(newUseGeneric, localName, useUltimate);
3403     newUseGeneric.AddUse(*localSymbol);
3404     if (combinedDerivedType) {
3405       if (const auto *oldDT{newUseGeneric.derivedType()}) {
3406         CHECK(&oldDT->GetUltimate() == &combinedDerivedType->GetUltimate());
3407       } else {
3408         newUseGeneric.set_derivedType(
3409             *const_cast<Symbol *>(combinedDerivedType));
3410       }
3411     }
3412     if (combinedProcedure) {
3413       newUseGeneric.set_specific(*const_cast<Symbol *>(combinedProcedure));
3414     }
3415   }
3416 }
3417 
3418 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
3419   if (useModuleScope_) {
3420     const auto &name{info.symbolName()};
3421     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
3422     info.Resolve(rename.use);
3423   }
3424 }
3425 
3426 // Create a UseDetails symbol for this USE and add it to generic
3427 Symbol &ModuleVisitor::AddGenericUse(
3428     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
3429   Symbol &newSymbol{
3430       currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol})};
3431   generic.AddUse(newSymbol);
3432   return newSymbol;
3433 }
3434 
3435 // Enforce F'2023 C1406 as a warning
3436 void ModuleVisitor::AddAndCheckModuleUse(SourceName name, bool isIntrinsic) {
3437   if (isIntrinsic) {
3438     if (auto iter{nonIntrinsicUses_.find(name)};
3439         iter != nonIntrinsicUses_.end()) {
3440       if (auto *msg{context().Warn(common::LanguageFeature::MiscUseExtensions,
3441               name,
3442               "Should not USE the intrinsic module '%s' in the same scope as a USE of the non-intrinsic module"_port_en_US,
3443               name)}) {
3444         msg->Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
3445       }
3446     }
3447     intrinsicUses_.insert(name);
3448   } else {
3449     if (auto iter{intrinsicUses_.find(name)}; iter != intrinsicUses_.end()) {
3450       if (auto *msg{context().Warn(common::LanguageFeature::MiscUseExtensions,
3451               name,
3452               "Should not USE the non-intrinsic module '%s' in the same scope as a USE of the intrinsic module"_port_en_US,
3453               name)}) {
3454         msg->Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
3455       }
3456     }
3457     nonIntrinsicUses_.insert(name);
3458   }
3459 }
3460 
3461 bool ModuleVisitor::BeginSubmodule(
3462     const parser::Name &name, const parser::ParentIdentifier &parentId) {
3463   const auto &ancestorName{std::get<parser::Name>(parentId.t)};
3464   Scope *parentScope{nullptr};
3465   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
3466   if (ancestor) {
3467     if (const auto &parentName{
3468             std::get<std::optional<parser::Name>>(parentId.t)}) {
3469       parentScope = FindModule(*parentName, false /*not intrinsic*/, ancestor);
3470     } else {
3471       parentScope = ancestor;
3472     }
3473   }
3474   if (parentScope) {
3475     PushScope(*parentScope);
3476   } else {
3477     // Error recovery: there's no ancestor scope, so create a dummy one to
3478     // hold the submodule's scope.
3479     SourceName dummyName{context().GetTempName(currScope())};
3480     Symbol &dummySymbol{MakeSymbol(dummyName, Attrs{}, ModuleDetails{false})};
3481     PushScope(Scope::Kind::Module, &dummySymbol);
3482     parentScope = &currScope();
3483   }
3484   BeginModule(name, true);
3485   set_inheritFromParent(false); // submodules don't inherit parents' implicits
3486   if (ancestor && !ancestor->AddSubmodule(name.source, currScope())) {
3487     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
3488         ancestorName.source, name.source);
3489   }
3490   return true;
3491 }
3492 
3493 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
3494   // Submodule symbols are not visible in their parents' scopes.
3495   Symbol &symbol{isSubmodule ? Resolve(name,
3496                                    currScope().MakeSymbol(name.source, Attrs{},
3497                                        ModuleDetails{true}))
3498                              : MakeSymbol(name, ModuleDetails{false})};
3499   auto &details{symbol.get<ModuleDetails>()};
3500   PushScope(Scope::Kind::Module, &symbol);
3501   details.set_scope(&currScope());
3502   prevAccessStmt_ = std::nullopt;
3503 }
3504 
3505 // Find a module or submodule by name and return its scope.
3506 // If ancestor is present, look for a submodule of that ancestor module.
3507 // May have to read a .mod file to find it.
3508 // If an error occurs, report it and return nullptr.
3509 Scope *ModuleVisitor::FindModule(const parser::Name &name,
3510     std::optional<bool> isIntrinsic, Scope *ancestor) {
3511   ModFileReader reader{context()};
3512   Scope *scope{
3513       reader.Read(name.source, isIntrinsic, ancestor, /*silent=*/false)};
3514   if (!scope) {
3515     return nullptr;
3516   }
3517   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
3518     Say(name, "Module '%s' cannot USE itself"_err_en_US);
3519   }
3520   Resolve(name, scope->symbol());
3521   return scope;
3522 }
3523 
3524 void ModuleVisitor::ApplyDefaultAccess() {
3525   const auto *moduleDetails{
3526       DEREF(currScope().symbol()).detailsIf<ModuleDetails>()};
3527   CHECK(moduleDetails);
3528   Attr defaultAttr{
3529       DEREF(moduleDetails).isDefaultPrivate() ? Attr::PRIVATE : Attr::PUBLIC};
3530   for (auto &pair : currScope()) {
3531     Symbol &symbol{*pair.second};
3532     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
3533       Attr attr{defaultAttr};
3534       if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
3535         if (generic->derivedType()) {
3536           // If a generic interface has a derived type of the same
3537           // name that has an explicit accessibility attribute, then
3538           // the generic must have the same accessibility.
3539           if (generic->derivedType()->attrs().test(Attr::PUBLIC)) {
3540             attr = Attr::PUBLIC;
3541           } else if (generic->derivedType()->attrs().test(Attr::PRIVATE)) {
3542             attr = Attr::PRIVATE;
3543           }
3544         }
3545       }
3546       SetImplicitAttr(symbol, attr);
3547     }
3548   }
3549 }
3550 
3551 // InterfaceVistor implementation
3552 
3553 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
3554   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
3555   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
3556   return BeginAttrs();
3557 }
3558 
3559 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
3560 
3561 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
3562   ResolveNewSpecifics();
3563   genericInfo_.pop();
3564 }
3565 
3566 // Create a symbol in genericSymbol_ for this GenericSpec.
3567 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
3568   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
3569     SetGenericSymbol(*symbol);
3570   }
3571   return false;
3572 }
3573 
3574 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
3575   if (!isGeneric()) {
3576     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
3577   } else {
3578     auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
3579     const auto &names{std::get<std::list<parser::Name>>(x.t)};
3580     AddSpecificProcs(names, kind);
3581   }
3582   return false;
3583 }
3584 
3585 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
3586   genericInfo_.emplace(/*isInterface*/ false);
3587   return BeginAttrs();
3588 }
3589 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
3590   auto attrs{EndAttrs()};
3591   if (Symbol * symbol{GetGenericInfo().symbol}) {
3592     SetExplicitAttrs(*symbol, attrs);
3593   }
3594   const auto &names{std::get<std::list<parser::Name>>(x.t)};
3595   AddSpecificProcs(names, ProcedureKind::Procedure);
3596   ResolveNewSpecifics();
3597   genericInfo_.pop();
3598 }
3599 
3600 bool InterfaceVisitor::inInterfaceBlock() const {
3601   return !genericInfo_.empty() && GetGenericInfo().isInterface;
3602 }
3603 bool InterfaceVisitor::isGeneric() const {
3604   return !genericInfo_.empty() && GetGenericInfo().symbol;
3605 }
3606 bool InterfaceVisitor::isAbstract() const {
3607   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
3608 }
3609 
3610 void InterfaceVisitor::AddSpecificProcs(
3611     const std::list<parser::Name> &names, ProcedureKind kind) {
3612   if (Symbol * symbol{GetGenericInfo().symbol};
3613       symbol && symbol->has<GenericDetails>()) {
3614     for (const auto &name : names) {
3615       specificsForGenericProcs_.emplace(symbol, std::make_pair(&name, kind));
3616       genericsForSpecificProcs_.emplace(name.source, symbol);
3617     }
3618   }
3619 }
3620 
3621 // By now we should have seen all specific procedures referenced by name in
3622 // this generic interface. Resolve those names to symbols.
3623 void GenericHandler::ResolveSpecificsInGeneric(
3624     Symbol &generic, bool isEndOfSpecificationPart) {
3625   auto &details{generic.get<GenericDetails>()};
3626   UnorderedSymbolSet symbolsSeen;
3627   for (const Symbol &symbol : details.specificProcs()) {
3628     symbolsSeen.insert(symbol.GetUltimate());
3629   }
3630   auto range{specificsForGenericProcs_.equal_range(&generic)};
3631   SpecificProcMapType retain;
3632   for (auto it{range.first}; it != range.second; ++it) {
3633     const parser::Name *name{it->second.first};
3634     auto kind{it->second.second};
3635     const Symbol *symbol{isEndOfSpecificationPart
3636             ? FindSymbol(*name)
3637             : FindInScope(generic.owner(), *name)};
3638     ProcedureDefinitionClass defClass{ProcedureDefinitionClass::None};
3639     const Symbol *specific{symbol};
3640     const Symbol *ultimate{nullptr};
3641     if (symbol) {
3642       // Subtlety: when *symbol is a use- or host-association, the specific
3643       // procedure that is recorded in the GenericDetails below must be *symbol,
3644       // not the specific procedure shadowed by a generic, because that specific
3645       // procedure may be a symbol from another module and its name unavailable
3646       // to emit to a module file.
3647       const Symbol &bypassed{BypassGeneric(*symbol)};
3648       if (symbol == &symbol->GetUltimate()) {
3649         specific = &bypassed;
3650       }
3651       ultimate = &bypassed.GetUltimate();
3652       defClass = ClassifyProcedure(*ultimate);
3653     }
3654     std::optional<MessageFixedText> error;
3655     if (defClass == ProcedureDefinitionClass::Module) {
3656       // ok
3657     } else if (kind == ProcedureKind::ModuleProcedure) {
3658       error = "'%s' is not a module procedure"_err_en_US;
3659     } else {
3660       switch (defClass) {
3661       case ProcedureDefinitionClass::Intrinsic:
3662       case ProcedureDefinitionClass::External:
3663       case ProcedureDefinitionClass::Internal:
3664       case ProcedureDefinitionClass::Dummy:
3665       case ProcedureDefinitionClass::Pointer:
3666         break;
3667       case ProcedureDefinitionClass::None:
3668         error = "'%s' is not a procedure"_err_en_US;
3669         break;
3670       default:
3671         error =
3672             "'%s' is not a procedure that can appear in a generic interface"_err_en_US;
3673         break;
3674       }
3675     }
3676     if (error) {
3677       if (isEndOfSpecificationPart) {
3678         Say(*name, std::move(*error));
3679       } else {
3680         // possible forward reference, catch it later
3681         retain.emplace(&generic, std::make_pair(name, kind));
3682       }
3683     } else if (!ultimate) {
3684     } else if (symbolsSeen.insert(*ultimate).second /*true if added*/) {
3685       // When a specific procedure is a USE association, that association
3686       // is saved in the generic's specifics, not its ultimate symbol,
3687       // so that module file output of interfaces can distinguish them.
3688       details.AddSpecificProc(*specific, name->source);
3689     } else if (specific == ultimate) {
3690       Say(name->source,
3691           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
3692           name->source, MakeOpName(generic.name()));
3693     } else {
3694       Say(name->source,
3695           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
3696           ultimate->name(), ultimate->owner().GetName().value(),
3697           MakeOpName(generic.name()));
3698     }
3699   }
3700   specificsForGenericProcs_.erase(range.first, range.second);
3701   specificsForGenericProcs_.merge(std::move(retain));
3702 }
3703 
3704 void GenericHandler::DeclaredPossibleSpecificProc(Symbol &proc) {
3705   auto range{genericsForSpecificProcs_.equal_range(proc.name())};
3706   for (auto iter{range.first}; iter != range.second; ++iter) {
3707     ResolveSpecificsInGeneric(*iter->second, false);
3708   }
3709 }
3710 
3711 void InterfaceVisitor::ResolveNewSpecifics() {
3712   if (Symbol * generic{genericInfo_.top().symbol};
3713       generic && generic->has<GenericDetails>()) {
3714     ResolveSpecificsInGeneric(*generic, false);
3715   }
3716 }
3717 
3718 // Mixed interfaces are allowed by the standard.
3719 // If there is a derived type with the same name, they must all be functions.
3720 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
3721   ResolveSpecificsInGeneric(generic, true);
3722   auto &details{generic.get<GenericDetails>()};
3723   if (auto *proc{details.CheckSpecific()}) {
3724     context().Warn(common::UsageWarning::HomonymousSpecific,
3725         proc->name().begin() > generic.name().begin() ? proc->name()
3726                                                       : generic.name(),
3727         "'%s' should not be the name of both a generic interface and a procedure unless it is a specific procedure of the generic"_warn_en_US,
3728         generic.name());
3729   }
3730   auto &specifics{details.specificProcs()};
3731   if (specifics.empty()) {
3732     if (details.derivedType()) {
3733       generic.set(Symbol::Flag::Function);
3734     }
3735     return;
3736   }
3737   const Symbol *function{nullptr};
3738   const Symbol *subroutine{nullptr};
3739   for (const Symbol &specific : specifics) {
3740     if (!function && specific.test(Symbol::Flag::Function)) {
3741       function = &specific;
3742     } else if (!subroutine && specific.test(Symbol::Flag::Subroutine)) {
3743       subroutine = &specific;
3744       if (details.derivedType() &&
3745           context().ShouldWarn(
3746               common::LanguageFeature::SubroutineAndFunctionSpecifics) &&
3747           !InModuleFile()) {
3748         SayDerivedType(generic.name(),
3749             "Generic interface '%s' should only contain functions due to derived type with same name"_warn_en_US,
3750             *details.derivedType()->GetUltimate().scope())
3751             .set_languageFeature(
3752                 common::LanguageFeature::SubroutineAndFunctionSpecifics);
3753       }
3754     }
3755     if (function && subroutine) { // F'2023 C1514
3756       if (auto *msg{context().Warn(
3757               common::LanguageFeature::SubroutineAndFunctionSpecifics,
3758               generic.name(),
3759               "Generic interface '%s' has both a function and a subroutine"_warn_en_US,
3760               generic.name())}) {
3761         msg->Attach(function->name(), "Function declaration"_en_US)
3762             .Attach(subroutine->name(), "Subroutine declaration"_en_US);
3763       }
3764       break;
3765     }
3766   }
3767   if (function && !subroutine) {
3768     generic.set(Symbol::Flag::Function);
3769   } else if (subroutine && !function) {
3770     generic.set(Symbol::Flag::Subroutine);
3771   }
3772 }
3773 
3774 // SubprogramVisitor implementation
3775 
3776 // Return false if it is actually an assignment statement.
3777 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
3778   const auto &name{std::get<parser::Name>(x.t)};
3779   const DeclTypeSpec *resultType{nullptr};
3780   // Look up name: provides return type or tells us if it's an array
3781   if (auto *symbol{FindSymbol(name)}) {
3782     Symbol &ultimate{symbol->GetUltimate()};
3783     if (ultimate.has<ObjectEntityDetails>() ||
3784         ultimate.has<AssocEntityDetails>() ||
3785         CouldBeDataPointerValuedFunction(&ultimate) ||
3786         (&symbol->owner() == &currScope() && IsFunctionResult(*symbol))) {
3787       misparsedStmtFuncFound_ = true;
3788       return false;
3789     }
3790     if (IsHostAssociated(*symbol, currScope())) {
3791       context().Warn(common::LanguageFeature::StatementFunctionExtensions,
3792           name.source,
3793           "Name '%s' from host scope should have a type declaration before its local statement function definition"_port_en_US,
3794           name.source);
3795       MakeSymbol(name, Attrs{}, UnknownDetails{});
3796     } else if (auto *entity{ultimate.detailsIf<EntityDetails>()};
3797                entity && !ultimate.has<ProcEntityDetails>()) {
3798       resultType = entity->type();
3799       ultimate.details() = UnknownDetails{}; // will be replaced below
3800     } else {
3801       misparsedStmtFuncFound_ = true;
3802     }
3803   }
3804   if (misparsedStmtFuncFound_) {
3805     Say(name,
3806         "'%s' has not been declared as an array or pointer-valued function"_err_en_US);
3807     return false;
3808   }
3809   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
3810   symbol.set(Symbol::Flag::StmtFunction);
3811   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
3812   auto &details{symbol.get<SubprogramDetails>()};
3813   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
3814     ObjectEntityDetails dummyDetails{true};
3815     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
3816       if (auto *d{dummySymbol->GetType()}) {
3817         dummyDetails.set_type(*d);
3818       }
3819     }
3820     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
3821     ApplyImplicitRules(dummy);
3822     details.add_dummyArg(dummy);
3823   }
3824   ObjectEntityDetails resultDetails;
3825   if (resultType) {
3826     resultDetails.set_type(*resultType);
3827   }
3828   resultDetails.set_funcResult(true);
3829   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
3830   result.flags().set(Symbol::Flag::StmtFunction);
3831   ApplyImplicitRules(result);
3832   details.set_result(result);
3833   // The analysis of the expression that constitutes the body of the
3834   // statement function is deferred to FinishSpecificationPart() so that
3835   // all declarations and implicit typing are complete.
3836   PopScope();
3837   return true;
3838 }
3839 
3840 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3841   if (suffix.resultName) {
3842     if (IsFunction(currScope())) {
3843       if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3844         if (info->inFunctionStmt) {
3845           info->resultName = &suffix.resultName.value();
3846         } else {
3847           // will check the result name in Post(EntryStmt)
3848         }
3849       }
3850     } else {
3851       Message &msg{Say(*suffix.resultName,
3852           "RESULT(%s) may appear only in a function"_err_en_US)};
3853       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3854         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3855       }
3856     }
3857   }
3858   // LanguageBindingSpec deferred to Post(EntryStmt) or, for FunctionStmt,
3859   // all the way to EndSubprogram().
3860   return false;
3861 }
3862 
3863 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3864   // Save this to process after UseStmt and ImplicitPart
3865   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3866     if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3867       if (info->parsedType) { // C1543
3868         Say(currStmtSource().value_or(info->source),
3869             "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3870       } else {
3871         info->parsedType = parsedType;
3872         if (auto at{currStmtSource()}) {
3873           info->source = *at;
3874         }
3875       }
3876     } else {
3877       Say(currStmtSource().value(),
3878           "SUBROUTINE prefix cannot specify a type"_err_en_US);
3879     }
3880     return false;
3881   } else {
3882     return true;
3883   }
3884 }
3885 
3886 bool SubprogramVisitor::Pre(const parser::PrefixSpec::Attributes &attrs) {
3887   if (auto *subp{currScope().symbol()
3888               ? currScope().symbol()->detailsIf<SubprogramDetails>()
3889               : nullptr}) {
3890     for (auto attr : attrs.v) {
3891       if (auto current{subp->cudaSubprogramAttrs()}) {
3892         if (attr == *current ||
3893             (*current == common::CUDASubprogramAttrs::HostDevice &&
3894                 (attr == common::CUDASubprogramAttrs::Host ||
3895                     attr == common::CUDASubprogramAttrs::Device))) {
3896           context().Warn(common::LanguageFeature::RedundantAttribute,
3897               currStmtSource().value(),
3898               "ATTRIBUTES(%s) appears more than once"_warn_en_US,
3899               common::EnumToString(attr));
3900         } else if ((attr == common::CUDASubprogramAttrs::Host ||
3901                        attr == common::CUDASubprogramAttrs::Device) &&
3902             (*current == common::CUDASubprogramAttrs::Host ||
3903                 *current == common::CUDASubprogramAttrs::Device ||
3904                 *current == common::CUDASubprogramAttrs::HostDevice)) {
3905           // HOST,DEVICE or DEVICE,HOST -> HostDevice
3906           subp->set_cudaSubprogramAttrs(
3907               common::CUDASubprogramAttrs::HostDevice);
3908         } else {
3909           Say(currStmtSource().value(),
3910               "ATTRIBUTES(%s) conflicts with earlier ATTRIBUTES(%s)"_err_en_US,
3911               common::EnumToString(attr), common::EnumToString(*current));
3912         }
3913       } else {
3914         subp->set_cudaSubprogramAttrs(attr);
3915       }
3916     }
3917     if (auto attrs{subp->cudaSubprogramAttrs()}) {
3918       if (*attrs == common::CUDASubprogramAttrs::Global ||
3919           *attrs == common::CUDASubprogramAttrs::Device) {
3920         const Scope &scope{currScope()};
3921         const Scope *mod{FindModuleContaining(scope)};
3922         if (mod && mod->GetName().value() == "cudadevice") {
3923           return false;
3924         }
3925         // Implicitly USE the cudadevice module by copying its symbols in the
3926         // current scope.
3927         const Scope &cudaDeviceScope{context().GetCUDADeviceScope()};
3928         for (auto sym : cudaDeviceScope.GetSymbols()) {
3929           if (!currScope().FindSymbol(sym->name())) {
3930             auto &localSymbol{MakeSymbol(
3931                 sym->name(), Attrs{}, UseDetails{sym->name(), *sym})};
3932             localSymbol.flags() = sym->flags();
3933           }
3934         }
3935       }
3936     }
3937   }
3938   return false;
3939 }
3940 
3941 void SubprogramVisitor::Post(const parser::PrefixSpec::Launch_Bounds &x) {
3942   std::vector<std::int64_t> bounds;
3943   bool ok{true};
3944   for (const auto &sicx : x.v) {
3945     if (auto value{evaluate::ToInt64(EvaluateExpr(sicx))}) {
3946       bounds.push_back(*value);
3947     } else {
3948       ok = false;
3949     }
3950   }
3951   if (!ok || bounds.size() < 2 || bounds.size() > 3) {
3952     Say(currStmtSource().value(),
3953         "Operands of LAUNCH_BOUNDS() must be 2 or 3 integer constants"_err_en_US);
3954   } else if (auto *subp{currScope().symbol()
3955                      ? currScope().symbol()->detailsIf<SubprogramDetails>()
3956                      : nullptr}) {
3957     if (subp->cudaLaunchBounds().empty()) {
3958       subp->set_cudaLaunchBounds(std::move(bounds));
3959     } else {
3960       Say(currStmtSource().value(),
3961           "LAUNCH_BOUNDS() may only appear once"_err_en_US);
3962     }
3963   }
3964 }
3965 
3966 void SubprogramVisitor::Post(const parser::PrefixSpec::Cluster_Dims &x) {
3967   std::vector<std::int64_t> dims;
3968   bool ok{true};
3969   for (const auto &sicx : x.v) {
3970     if (auto value{evaluate::ToInt64(EvaluateExpr(sicx))}) {
3971       dims.push_back(*value);
3972     } else {
3973       ok = false;
3974     }
3975   }
3976   if (!ok || dims.size() != 3) {
3977     Say(currStmtSource().value(),
3978         "Operands of CLUSTER_DIMS() must be three integer constants"_err_en_US);
3979   } else if (auto *subp{currScope().symbol()
3980                      ? currScope().symbol()->detailsIf<SubprogramDetails>()
3981                      : nullptr}) {
3982     if (subp->cudaClusterDims().empty()) {
3983       subp->set_cudaClusterDims(std::move(dims));
3984     } else {
3985       Say(currStmtSource().value(),
3986           "CLUSTER_DIMS() may only appear once"_err_en_US);
3987     }
3988   }
3989 }
3990 
3991 static bool HasModulePrefix(const std::list<parser::PrefixSpec> &prefixes) {
3992   for (const auto &prefix : prefixes) {
3993     if (std::holds_alternative<parser::PrefixSpec::Module>(prefix.u)) {
3994       return true;
3995     }
3996   }
3997   return false;
3998 }
3999 
4000 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
4001   const auto &stmtTuple{
4002       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t};
4003   return BeginSubprogram(std::get<parser::Name>(stmtTuple),
4004       Symbol::Flag::Subroutine,
4005       HasModulePrefix(std::get<std::list<parser::PrefixSpec>>(stmtTuple)));
4006 }
4007 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &x) {
4008   const auto &stmt{std::get<parser::Statement<parser::SubroutineStmt>>(x.t)};
4009   EndSubprogram(stmt.source,
4010       &std::get<std::optional<parser::LanguageBindingSpec>>(stmt.statement.t));
4011 }
4012 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
4013   const auto &stmtTuple{
4014       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t};
4015   return BeginSubprogram(std::get<parser::Name>(stmtTuple),
4016       Symbol::Flag::Function,
4017       HasModulePrefix(std::get<std::list<parser::PrefixSpec>>(stmtTuple)));
4018 }
4019 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &x) {
4020   const auto &stmt{std::get<parser::Statement<parser::FunctionStmt>>(x.t)};
4021   const auto &maybeSuffix{
4022       std::get<std::optional<parser::Suffix>>(stmt.statement.t)};
4023   EndSubprogram(stmt.source, maybeSuffix ? &maybeSuffix->binding : nullptr);
4024 }
4025 
4026 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &stmt) {
4027   BeginAttrs();
4028   Walk(std::get<std::list<parser::PrefixSpec>>(stmt.t));
4029   Walk(std::get<parser::Name>(stmt.t));
4030   Walk(std::get<std::list<parser::DummyArg>>(stmt.t));
4031   // Don't traverse the LanguageBindingSpec now; it's deferred to EndSubprogram.
4032   Symbol &symbol{PostSubprogramStmt()};
4033   SubprogramDetails &details{symbol.get<SubprogramDetails>()};
4034   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
4035     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
4036       CreateDummyArgument(details, *dummyName);
4037     } else {
4038       details.add_alternateReturn();
4039     }
4040   }
4041   return false;
4042 }
4043 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
4044   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
4045   CHECK(!info.inFunctionStmt);
4046   info.inFunctionStmt = true;
4047   if (auto at{currStmtSource()}) {
4048     info.source = *at;
4049   }
4050   return BeginAttrs();
4051 }
4052 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
4053 
4054 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
4055   const auto &name{std::get<parser::Name>(stmt.t)};
4056   Symbol &symbol{PostSubprogramStmt()};
4057   SubprogramDetails &details{symbol.get<SubprogramDetails>()};
4058   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
4059     CreateDummyArgument(details, dummyName);
4060   }
4061   const parser::Name *funcResultName;
4062   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
4063   CHECK(info.inFunctionStmt);
4064   info.inFunctionStmt = false;
4065   bool distinctResultName{
4066       info.resultName && info.resultName->source != name.source};
4067   if (distinctResultName) {
4068     // Note that RESULT is ignored if it has the same name as the function.
4069     // The symbol created by PushScope() is retained as a place-holder
4070     // for error detection.
4071     funcResultName = info.resultName;
4072   } else {
4073     EraseSymbol(name); // was added by PushScope()
4074     funcResultName = &name;
4075   }
4076   if (details.isFunction()) {
4077     CHECK(context().HasError(currScope().symbol()));
4078   } else {
4079     // RESULT(x) can be the same explicitly-named RESULT(x) as an ENTRY
4080     // statement.
4081     Symbol *result{nullptr};
4082     if (distinctResultName) {
4083       if (auto iter{currScope().find(funcResultName->source)};
4084           iter != currScope().end()) {
4085         Symbol &entryResult{*iter->second};
4086         if (IsFunctionResult(entryResult)) {
4087           result = &entryResult;
4088         }
4089       }
4090     }
4091     if (result) {
4092       Resolve(*funcResultName, *result);
4093     } else {
4094       // add function result to function scope
4095       EntityDetails funcResultDetails;
4096       funcResultDetails.set_funcResult(true);
4097       result = &MakeSymbol(*funcResultName, std::move(funcResultDetails));
4098     }
4099     info.resultSymbol = result;
4100     details.set_result(*result);
4101   }
4102   // C1560.
4103   if (info.resultName && !distinctResultName) {
4104     context().Warn(common::UsageWarning::HomonymousResult,
4105         info.resultName->source,
4106         "The function name should not appear in RESULT; references to '%s' "
4107         "inside the function will be considered as references to the "
4108         "result only"_warn_en_US,
4109         name.source);
4110     // RESULT name was ignored above, the only side effect from doing so will be
4111     // the inability to make recursive calls. The related parser::Name is still
4112     // resolved to the created function result symbol because every parser::Name
4113     // should be resolved to avoid internal errors.
4114     Resolve(*info.resultName, info.resultSymbol);
4115   }
4116   name.symbol = &symbol; // must not be function result symbol
4117   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
4118   // has a RESULT() suffix.
4119   info.resultName = nullptr;
4120 }
4121 
4122 Symbol &SubprogramVisitor::PostSubprogramStmt() {
4123   Symbol &symbol{*currScope().symbol()};
4124   SetExplicitAttrs(symbol, EndAttrs());
4125   if (symbol.attrs().test(Attr::MODULE)) {
4126     symbol.attrs().set(Attr::EXTERNAL, false);
4127     symbol.implicitAttrs().set(Attr::EXTERNAL, false);
4128   }
4129   return symbol;
4130 }
4131 
4132 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
4133   if (const auto &suffix{std::get<std::optional<parser::Suffix>>(stmt.t)}) {
4134     Walk(suffix->binding);
4135   }
4136   PostEntryStmt(stmt);
4137   EndAttrs();
4138 }
4139 
4140 void SubprogramVisitor::CreateDummyArgument(
4141     SubprogramDetails &details, const parser::Name &name) {
4142   Symbol *dummy{FindInScope(name)};
4143   if (dummy) {
4144     if (IsDummy(*dummy)) {
4145       if (dummy->test(Symbol::Flag::EntryDummyArgument)) {
4146         dummy->set(Symbol::Flag::EntryDummyArgument, false);
4147       } else {
4148         Say(name,
4149             "'%s' appears more than once as a dummy argument name in this subprogram"_err_en_US,
4150             name.source);
4151         return;
4152       }
4153     } else {
4154       SayWithDecl(name, *dummy,
4155           "'%s' may not appear as a dummy argument name in this subprogram"_err_en_US);
4156       return;
4157     }
4158   } else {
4159     dummy = &MakeSymbol(name, EntityDetails{true});
4160   }
4161   details.add_dummyArg(DEREF(dummy));
4162 }
4163 
4164 void SubprogramVisitor::CreateEntry(
4165     const parser::EntryStmt &stmt, Symbol &subprogram) {
4166   const auto &entryName{std::get<parser::Name>(stmt.t)};
4167   Scope &outer{currScope().parent()};
4168   Symbol::Flag subpFlag{subprogram.test(Symbol::Flag::Function)
4169           ? Symbol::Flag::Function
4170           : Symbol::Flag::Subroutine};
4171   Attrs attrs;
4172   const auto &suffix{std::get<std::optional<parser::Suffix>>(stmt.t)};
4173   bool hasGlobalBindingName{outer.IsGlobal() && suffix && suffix->binding &&
4174       std::get<std::optional<parser::ScalarDefaultCharConstantExpr>>(
4175           suffix->binding->t)
4176           .has_value()};
4177   if (!hasGlobalBindingName) {
4178     if (Symbol * extant{FindSymbol(outer, entryName)}) {
4179       if (!HandlePreviousCalls(entryName, *extant, subpFlag)) {
4180         if (outer.IsTopLevel()) {
4181           Say2(entryName,
4182               "'%s' is already defined as a global identifier"_err_en_US,
4183               *extant, "Previous definition of '%s'"_en_US);
4184         } else {
4185           SayAlreadyDeclared(entryName, *extant);
4186         }
4187         return;
4188       }
4189       attrs = extant->attrs();
4190     }
4191   }
4192   std::optional<SourceName> distinctResultName;
4193   if (suffix && suffix->resultName &&
4194       suffix->resultName->source != entryName.source) {
4195     distinctResultName = suffix->resultName->source;
4196   }
4197   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
4198     attrs.set(Attr::PUBLIC);
4199   }
4200   Symbol *entrySymbol{nullptr};
4201   if (hasGlobalBindingName) {
4202     // Hide the entry's symbol in a new anonymous global scope so
4203     // that its name doesn't clash with anything.
4204     Symbol &symbol{MakeSymbol(outer, context().GetTempName(outer), Attrs{})};
4205     symbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
4206     Scope &hidden{outer.MakeScope(Scope::Kind::Global, &symbol)};
4207     entrySymbol = &MakeSymbol(hidden, entryName.source, attrs);
4208   } else {
4209     entrySymbol = FindInScope(outer, entryName.source);
4210     if (entrySymbol) {
4211       if (auto *generic{entrySymbol->detailsIf<GenericDetails>()}) {
4212         if (auto *specific{generic->specific()}) {
4213           // Forward reference to ENTRY from a generic interface
4214           entrySymbol = specific;
4215           CheckDuplicatedAttrs(entryName.source, *entrySymbol, attrs);
4216           SetExplicitAttrs(*entrySymbol, attrs);
4217         }
4218       }
4219     } else {
4220       entrySymbol = &MakeSymbol(outer, entryName.source, attrs);
4221     }
4222   }
4223   SubprogramDetails entryDetails;
4224   entryDetails.set_entryScope(currScope());
4225   entrySymbol->set(subpFlag);
4226   if (subpFlag == Symbol::Flag::Function) {
4227     Symbol *result{nullptr};
4228     EntityDetails resultDetails;
4229     resultDetails.set_funcResult(true);
4230     if (distinctResultName) {
4231       // An explicit RESULT() can also be an explicit RESULT()
4232       // of the function or another ENTRY.
4233       if (auto iter{currScope().find(suffix->resultName->source)};
4234           iter != currScope().end()) {
4235         result = &*iter->second;
4236       }
4237       if (!result) {
4238         result =
4239             &MakeSymbol(*distinctResultName, Attrs{}, std::move(resultDetails));
4240       } else if (!result->has<EntityDetails>()) {
4241         Say(*distinctResultName,
4242             "ENTRY cannot have RESULT(%s) that is not a variable"_err_en_US,
4243             *distinctResultName)
4244             .Attach(result->name(), "Existing declaration of '%s'"_en_US,
4245                 result->name());
4246         result = nullptr;
4247       }
4248       if (result) {
4249         Resolve(*suffix->resultName, *result);
4250       }
4251     } else {
4252       result = &MakeSymbol(entryName.source, Attrs{}, std::move(resultDetails));
4253     }
4254     if (result) {
4255       entryDetails.set_result(*result);
4256     }
4257   }
4258   if (subpFlag == Symbol::Flag::Subroutine || distinctResultName) {
4259     Symbol &assoc{MakeSymbol(entryName.source)};
4260     assoc.set_details(HostAssocDetails{*entrySymbol});
4261     assoc.set(Symbol::Flag::Subroutine);
4262   }
4263   Resolve(entryName, *entrySymbol);
4264   std::set<SourceName> dummies;
4265   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
4266     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
4267       auto pair{dummies.insert(dummyName->source)};
4268       if (!pair.second) {
4269         Say(*dummyName,
4270             "'%s' appears more than once as a dummy argument name in this ENTRY statement"_err_en_US,
4271             dummyName->source);
4272         continue;
4273       }
4274       Symbol *dummy{FindInScope(*dummyName)};
4275       if (dummy) {
4276         if (!IsDummy(*dummy)) {
4277           evaluate::AttachDeclaration(
4278               Say(*dummyName,
4279                   "'%s' may not appear as a dummy argument name in this ENTRY statement"_err_en_US,
4280                   dummyName->source),
4281               *dummy);
4282           continue;
4283         }
4284       } else {
4285         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
4286         dummy->set(Symbol::Flag::EntryDummyArgument);
4287       }
4288       entryDetails.add_dummyArg(DEREF(dummy));
4289     } else if (subpFlag == Symbol::Flag::Function) { // C1573
4290       Say(entryName,
4291           "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
4292       break;
4293     } else {
4294       entryDetails.add_alternateReturn();
4295     }
4296   }
4297   entrySymbol->set_details(std::move(entryDetails));
4298 }
4299 
4300 void SubprogramVisitor::PostEntryStmt(const parser::EntryStmt &stmt) {
4301   // The entry symbol should have already been created and resolved
4302   // in CreateEntry(), called by BeginSubprogram(), with one exception (below).
4303   const auto &name{std::get<parser::Name>(stmt.t)};
4304   Scope &inclusiveScope{InclusiveScope()};
4305   if (!name.symbol) {
4306     if (inclusiveScope.kind() != Scope::Kind::Subprogram) {
4307       Say(name.source,
4308           "ENTRY '%s' may appear only in a subroutine or function"_err_en_US,
4309           name.source);
4310     } else if (FindSeparateModuleSubprogramInterface(inclusiveScope.symbol())) {
4311       Say(name.source,
4312           "ENTRY '%s' may not appear in a separate module procedure"_err_en_US,
4313           name.source);
4314     } else {
4315       // C1571 - entry is nested, so was not put into the program tree; error
4316       // is emitted from MiscChecker in semantics.cpp.
4317     }
4318     return;
4319   }
4320   Symbol &entrySymbol{*name.symbol};
4321   if (context().HasError(entrySymbol)) {
4322     return;
4323   }
4324   if (!entrySymbol.has<SubprogramDetails>()) {
4325     SayAlreadyDeclared(name, entrySymbol);
4326     return;
4327   }
4328   SubprogramDetails &entryDetails{entrySymbol.get<SubprogramDetails>()};
4329   CHECK(entryDetails.entryScope() == &inclusiveScope);
4330   SetCUDADataAttr(name.source, entrySymbol, cudaDataAttr());
4331   entrySymbol.attrs() |= GetAttrs();
4332   SetBindNameOn(entrySymbol);
4333   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
4334     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
4335       if (Symbol * dummy{FindInScope(*dummyName)}) {
4336         if (dummy->test(Symbol::Flag::EntryDummyArgument)) {
4337           const auto *subp{dummy->detailsIf<SubprogramDetails>()};
4338           if (subp && subp->isInterface()) { // ok
4339           } else if (!dummy->has<EntityDetails>() &&
4340               !dummy->has<ObjectEntityDetails>() &&
4341               !dummy->has<ProcEntityDetails>()) {
4342             SayWithDecl(*dummyName, *dummy,
4343                 "ENTRY dummy argument '%s' was previously declared as an item that may not be used as a dummy argument"_err_en_US);
4344           }
4345           dummy->set(Symbol::Flag::EntryDummyArgument, false);
4346         }
4347       }
4348     }
4349   }
4350 }
4351 
4352 Symbol *ScopeHandler::FindSeparateModuleProcedureInterface(
4353     const parser::Name &name) {
4354   auto *symbol{FindSymbol(name)};
4355   if (symbol && symbol->has<SubprogramNameDetails>()) {
4356     const Scope *parent{nullptr};
4357     if (currScope().IsSubmodule()) {
4358       parent = currScope().symbol()->get<ModuleDetails>().parent();
4359     }
4360     symbol = parent ? FindSymbol(*parent, name) : nullptr;
4361   }
4362   if (symbol) {
4363     if (auto *generic{symbol->detailsIf<GenericDetails>()}) {
4364       symbol = generic->specific();
4365     }
4366   }
4367   if (const Symbol * defnIface{FindSeparateModuleSubprogramInterface(symbol)}) {
4368     // Error recovery in case of multiple definitions
4369     symbol = const_cast<Symbol *>(defnIface);
4370   }
4371   if (!IsSeparateModuleProcedureInterface(symbol)) {
4372     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
4373     symbol = nullptr;
4374   }
4375   return symbol;
4376 }
4377 
4378 // A subprogram declared with MODULE PROCEDURE
4379 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
4380   Symbol *symbol{FindSeparateModuleProcedureInterface(name)};
4381   if (!symbol) {
4382     return false;
4383   }
4384   if (symbol->owner() == currScope() && symbol->scope()) {
4385     // This is a MODULE PROCEDURE whose interface appears in its host.
4386     // Convert the module procedure's interface into a subprogram.
4387     SetScope(DEREF(symbol->scope()));
4388     symbol->get<SubprogramDetails>().set_isInterface(false);
4389     name.symbol = symbol;
4390   } else {
4391     // Copy the interface into a new subprogram scope.
4392     EraseSymbol(name);
4393     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
4394     PushScope(Scope::Kind::Subprogram, &newSymbol);
4395     auto &newSubprogram{newSymbol.get<SubprogramDetails>()};
4396     newSubprogram.set_moduleInterface(*symbol);
4397     auto &subprogram{symbol->get<SubprogramDetails>()};
4398     if (const auto *name{subprogram.bindName()}) {
4399       newSubprogram.set_bindName(std::string{*name});
4400     }
4401     newSymbol.attrs() |= symbol->attrs();
4402     newSymbol.set(symbol->test(Symbol::Flag::Subroutine)
4403             ? Symbol::Flag::Subroutine
4404             : Symbol::Flag::Function);
4405     MapSubprogramToNewSymbols(*symbol, newSymbol, currScope());
4406   }
4407   return true;
4408 }
4409 
4410 // A subprogram or interface declared with SUBROUTINE or FUNCTION
4411 bool SubprogramVisitor::BeginSubprogram(const parser::Name &name,
4412     Symbol::Flag subpFlag, bool hasModulePrefix,
4413     const parser::LanguageBindingSpec *bindingSpec,
4414     const ProgramTree::EntryStmtList *entryStmts) {
4415   bool isValid{true};
4416   if (hasModulePrefix && !currScope().IsModule() &&
4417       !currScope().IsSubmodule()) { // C1547
4418     Say(name,
4419         "'%s' is a MODULE procedure which must be declared within a "
4420         "MODULE or SUBMODULE"_err_en_US);
4421     // Don't return here because it can be useful to have the scope set for
4422     // other semantic checks run before we print the errors
4423     isValid = false;
4424   }
4425   Symbol *moduleInterface{nullptr};
4426   if (isValid && hasModulePrefix && !inInterfaceBlock()) {
4427     moduleInterface = FindSeparateModuleProcedureInterface(name);
4428     if (moduleInterface && &moduleInterface->owner() == &currScope()) {
4429       // Subprogram is MODULE FUNCTION or MODULE SUBROUTINE with an interface
4430       // previously defined in the same scope.
4431       if (GenericDetails *
4432           generic{DEREF(FindSymbol(name)).detailsIf<GenericDetails>()}) {
4433         generic->clear_specific();
4434         name.symbol = nullptr;
4435       } else {
4436         EraseSymbol(name);
4437       }
4438     }
4439   }
4440   Symbol &newSymbol{
4441       PushSubprogramScope(name, subpFlag, bindingSpec, hasModulePrefix)};
4442   if (moduleInterface) {
4443     newSymbol.get<SubprogramDetails>().set_moduleInterface(*moduleInterface);
4444     if (moduleInterface->attrs().test(Attr::PRIVATE)) {
4445       SetImplicitAttr(newSymbol, Attr::PRIVATE);
4446     } else if (moduleInterface->attrs().test(Attr::PUBLIC)) {
4447       SetImplicitAttr(newSymbol, Attr::PUBLIC);
4448     }
4449   }
4450   if (entryStmts) {
4451     for (const auto &ref : *entryStmts) {
4452       CreateEntry(*ref, newSymbol);
4453     }
4454   }
4455   return true;
4456 }
4457 
4458 void SubprogramVisitor::HandleLanguageBinding(Symbol *symbol,
4459     std::optional<parser::CharBlock> stmtSource,
4460     const std::optional<parser::LanguageBindingSpec> *binding) {
4461   if (binding && *binding && symbol) {
4462     // Finally process the BIND(C,NAME=name) now that symbols in the name
4463     // expression will resolve to local names if needed.
4464     auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
4465     auto originalStmtSource{messageHandler().currStmtSource()};
4466     messageHandler().set_currStmtSource(stmtSource);
4467     BeginAttrs();
4468     Walk(**binding);
4469     SetBindNameOn(*symbol);
4470     symbol->attrs() |= EndAttrs();
4471     messageHandler().set_currStmtSource(originalStmtSource);
4472   }
4473 }
4474 
4475 void SubprogramVisitor::EndSubprogram(
4476     std::optional<parser::CharBlock> stmtSource,
4477     const std::optional<parser::LanguageBindingSpec> *binding,
4478     const ProgramTree::EntryStmtList *entryStmts) {
4479   HandleLanguageBinding(currScope().symbol(), stmtSource, binding);
4480   if (entryStmts) {
4481     for (const auto &ref : *entryStmts) {
4482       const parser::EntryStmt &entryStmt{*ref};
4483       if (const auto &suffix{
4484               std::get<std::optional<parser::Suffix>>(entryStmt.t)}) {
4485         const auto &name{std::get<parser::Name>(entryStmt.t)};
4486         HandleLanguageBinding(name.symbol, name.source, &suffix->binding);
4487       }
4488     }
4489   }
4490   if (inInterfaceBlock() && currScope().symbol()) {
4491     DeclaredPossibleSpecificProc(*currScope().symbol());
4492   }
4493   PopScope();
4494 }
4495 
4496 bool SubprogramVisitor::HandlePreviousCalls(
4497     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
4498   // If the extant symbol is a generic, check its homonymous specific
4499   // procedure instead if it has one.
4500   if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
4501     return generic->specific() &&
4502         HandlePreviousCalls(name, *generic->specific(), subpFlag);
4503   } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
4504              !proc->isDummy() &&
4505              !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
4506     // There's a symbol created for previous calls to this subprogram or
4507     // ENTRY's name.  We have to replace that symbol in situ to avoid the
4508     // obligation to rewrite symbol pointers in the parse tree.
4509     if (!symbol.test(subpFlag)) {
4510       auto other{subpFlag == Symbol::Flag::Subroutine
4511               ? Symbol::Flag::Function
4512               : Symbol::Flag::Subroutine};
4513       // External statements issue an explicit EXTERNAL attribute.
4514       if (symbol.attrs().test(Attr::EXTERNAL) &&
4515           !symbol.implicitAttrs().test(Attr::EXTERNAL)) {
4516         // Warn if external statement previously declared.
4517         context().Warn(common::LanguageFeature::RedundantAttribute, name.source,
4518             "EXTERNAL attribute was already specified on '%s'"_warn_en_US,
4519             name.source);
4520       } else if (symbol.test(other)) {
4521         Say2(name,
4522             subpFlag == Symbol::Flag::Function
4523                 ? "'%s' was previously called as a subroutine"_err_en_US
4524                 : "'%s' was previously called as a function"_err_en_US,
4525             symbol, "Previous call of '%s'"_en_US);
4526       } else {
4527         symbol.set(subpFlag);
4528       }
4529     }
4530     EntityDetails entity;
4531     if (proc->type()) {
4532       entity.set_type(*proc->type());
4533     }
4534     symbol.details() = std::move(entity);
4535     return true;
4536   } else {
4537     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
4538   }
4539 }
4540 
4541 void SubprogramVisitor::CheckExtantProc(
4542     const parser::Name &name, Symbol::Flag subpFlag) {
4543   if (auto *prev{FindSymbol(name)}) {
4544     if (IsDummy(*prev)) {
4545     } else if (auto *entity{prev->detailsIf<EntityDetails>()};
4546                IsPointer(*prev) && entity && !entity->type()) {
4547       // POINTER attribute set before interface
4548     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
4549       // Procedures in an INTERFACE block do not resolve to symbols
4550       // in scopes between the global scope and the current scope.
4551     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
4552       SayAlreadyDeclared(name, *prev);
4553     }
4554   }
4555 }
4556 
4557 Symbol &SubprogramVisitor::PushSubprogramScope(const parser::Name &name,
4558     Symbol::Flag subpFlag, const parser::LanguageBindingSpec *bindingSpec,
4559     bool hasModulePrefix) {
4560   Symbol *symbol{GetSpecificFromGeneric(name)};
4561   if (!symbol) {
4562     if (bindingSpec && currScope().IsGlobal() &&
4563         std::get<std::optional<parser::ScalarDefaultCharConstantExpr>>(
4564             bindingSpec->t)
4565             .has_value()) {
4566       // Create this new top-level subprogram with a binding label
4567       // in a new global scope, so that its symbol's name won't clash
4568       // with another symbol that has a distinct binding label.
4569       PushScope(Scope::Kind::Global,
4570           &MakeSymbol(context().GetTempName(currScope()), Attrs{},
4571               MiscDetails{MiscDetails::Kind::ScopeName}));
4572     }
4573     CheckExtantProc(name, subpFlag);
4574     symbol = &MakeSymbol(name, SubprogramDetails{});
4575   }
4576   symbol->ReplaceName(name.source);
4577   symbol->set(subpFlag);
4578   PushScope(Scope::Kind::Subprogram, symbol);
4579   if (subpFlag == Symbol::Flag::Function) {
4580     funcResultStack().Push(currScope(), name.source);
4581   }
4582   if (inInterfaceBlock()) {
4583     auto &details{symbol->get<SubprogramDetails>()};
4584     details.set_isInterface();
4585     if (isAbstract()) {
4586       SetExplicitAttr(*symbol, Attr::ABSTRACT);
4587     } else if (hasModulePrefix) {
4588       SetExplicitAttr(*symbol, Attr::MODULE);
4589     } else {
4590       MakeExternal(*symbol);
4591     }
4592     if (isGeneric()) {
4593       Symbol &genericSymbol{GetGenericSymbol()};
4594       if (auto *details{genericSymbol.detailsIf<GenericDetails>()}) {
4595         details->AddSpecificProc(*symbol, name.source);
4596       } else {
4597         CHECK(context().HasError(genericSymbol));
4598       }
4599     }
4600     set_inheritFromParent(false); // interfaces don't inherit, even if MODULE
4601   }
4602   if (Symbol * found{FindSymbol(name)};
4603       found && found->has<HostAssocDetails>()) {
4604     found->set(subpFlag); // PushScope() created symbol
4605   }
4606   return *symbol;
4607 }
4608 
4609 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
4610   if (auto *prev{FindSymbol(name)}) {
4611     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
4612       if (prev->test(Symbol::Flag::Subroutine) ||
4613           prev->test(Symbol::Flag::Function)) {
4614         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
4615             "Previous call of '%s'"_en_US);
4616       }
4617       EraseSymbol(name);
4618     }
4619   }
4620   if (name.source.empty()) {
4621     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
4622     PushScope(Scope::Kind::BlockData, nullptr);
4623   } else {
4624     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
4625   }
4626 }
4627 
4628 // If name is a generic, return specific subprogram with the same name.
4629 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
4630   // Search for the name but don't resolve it
4631   if (auto *symbol{currScope().FindSymbol(name.source)}) {
4632     if (symbol->has<SubprogramNameDetails>()) {
4633       if (inInterfaceBlock()) {
4634         // Subtle: clear any MODULE flag so that the new interface
4635         // symbol doesn't inherit it and ruin the ability to check it.
4636         symbol->attrs().reset(Attr::MODULE);
4637       }
4638     } else if (auto *details{symbol->detailsIf<GenericDetails>()}) {
4639       // found generic, want specific procedure
4640       auto *specific{details->specific()};
4641       Attrs moduleAttr;
4642       if (inInterfaceBlock()) {
4643         if (specific) {
4644           // Defining an interface in a generic of the same name which is
4645           // already shadowing another procedure.  In some cases, the shadowed
4646           // procedure is about to be replaced.
4647           if (specific->has<SubprogramNameDetails>() &&
4648               specific->attrs().test(Attr::MODULE)) {
4649             // The shadowed procedure is a separate module procedure that is
4650             // actually defined later in this (sub)module.
4651             // Define its interface now as a new symbol.
4652             moduleAttr.set(Attr::MODULE);
4653             specific = nullptr;
4654           } else if (&specific->owner() != &symbol->owner()) {
4655             // The shadowed procedure was from an enclosing scope and will be
4656             // overridden by this interface definition.
4657             specific = nullptr;
4658           }
4659           if (!specific) {
4660             details->clear_specific();
4661           }
4662         } else if (const auto *dType{details->derivedType()}) {
4663           if (&dType->owner() != &symbol->owner()) {
4664             // The shadowed derived type was from an enclosing scope and
4665             // will be overridden by this interface definition.
4666             details->clear_derivedType();
4667           }
4668         }
4669       }
4670       if (!specific) {
4671         specific = &currScope().MakeSymbol(
4672             name.source, std::move(moduleAttr), SubprogramDetails{});
4673         if (details->derivedType()) {
4674           // A specific procedure with the same name as a derived type
4675           SayAlreadyDeclared(name, *details->derivedType());
4676         } else {
4677           details->set_specific(Resolve(name, *specific));
4678         }
4679       } else if (isGeneric()) {
4680         SayAlreadyDeclared(name, *specific);
4681       }
4682       if (specific->has<SubprogramNameDetails>()) {
4683         specific->set_details(Details{SubprogramDetails{}});
4684       }
4685       return specific;
4686     }
4687   }
4688   return nullptr;
4689 }
4690 
4691 // DeclarationVisitor implementation
4692 
4693 bool DeclarationVisitor::BeginDecl() {
4694   BeginDeclTypeSpec();
4695   BeginArraySpec();
4696   return BeginAttrs();
4697 }
4698 void DeclarationVisitor::EndDecl() {
4699   EndDeclTypeSpec();
4700   EndArraySpec();
4701   EndAttrs();
4702 }
4703 
4704 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
4705   return HadUseError(context(), name.source, name.symbol);
4706 }
4707 
4708 // Report error if accessibility of symbol doesn't match isPrivate.
4709 void DeclarationVisitor::CheckAccessibility(
4710     const SourceName &name, bool isPrivate, Symbol &symbol) {
4711   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
4712     Say2(name,
4713         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
4714         symbol, "Previous declaration of '%s'"_en_US);
4715   }
4716 }
4717 
4718 bool DeclarationVisitor::Pre(const parser::TypeDeclarationStmt &x) {
4719   BeginDecl();
4720   // If INTRINSIC appears as an attr-spec, handle it now as if the
4721   // names had appeared on an INTRINSIC attribute statement beforehand.
4722   for (const auto &attr : std::get<std::list<parser::AttrSpec>>(x.t)) {
4723     if (std::holds_alternative<parser::Intrinsic>(attr.u)) {
4724       for (const auto &decl : std::get<std::list<parser::EntityDecl>>(x.t)) {
4725         DeclareIntrinsic(parser::GetFirstName(decl));
4726       }
4727       break;
4728     }
4729   }
4730   return true;
4731 }
4732 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
4733   EndDecl();
4734 }
4735 
4736 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
4737   DeclareObjectEntity(std::get<parser::Name>(x.t));
4738 }
4739 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
4740   DeclareObjectEntity(std::get<parser::Name>(x.t));
4741 }
4742 
4743 bool DeclarationVisitor::Pre(const parser::Initialization &) {
4744   // Defer inspection of initializers to Initialization() so that the
4745   // symbol being initialized will be available within the initialization
4746   // expression.
4747   return false;
4748 }
4749 
4750 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
4751   const auto &name{std::get<parser::ObjectName>(x.t)};
4752   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
4753   attrs.set(Attr::INTRINSIC, false); // dealt with in Pre(TypeDeclarationStmt)
4754   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
4755   symbol.ReplaceName(name.source);
4756   SetCUDADataAttr(name.source, symbol, cudaDataAttr());
4757   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4758     ConvertToObjectEntity(symbol) || ConvertToProcEntity(symbol);
4759     symbol.set(
4760         Symbol::Flag::EntryDummyArgument, false); // forestall excessive errors
4761     Initialization(name, *init, false);
4762   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
4763     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
4764   }
4765   if (auto *scopeSymbol{currScope().symbol()})
4766     if (auto *details{scopeSymbol->detailsIf<DerivedTypeDetails>()})
4767       if (details->isDECStructure())
4768         details->add_component(symbol);
4769 }
4770 
4771 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
4772   const auto &name{std::get<parser::Name>(x.t)};
4773   if (const auto &deferredShapeSpecs{
4774           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
4775     CHECK(arraySpec().empty());
4776     BeginArraySpec();
4777     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
4778     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
4779     symbol.ReplaceName(name.source);
4780     EndArraySpec();
4781   } else {
4782     if (const auto *symbol{FindInScope(name)}) {
4783       const auto *subp{symbol->detailsIf<SubprogramDetails>()};
4784       if (!symbol->has<UseDetails>() && // error caught elsewhere
4785           !symbol->has<ObjectEntityDetails>() &&
4786           !symbol->has<ProcEntityDetails>() &&
4787           !symbol->CanReplaceDetails(ObjectEntityDetails{}) &&
4788           !symbol->CanReplaceDetails(ProcEntityDetails{}) &&
4789           !(subp && subp->isInterface())) {
4790         Say(name, "'%s' cannot have the POINTER attribute"_err_en_US);
4791       }
4792     }
4793     HandleAttributeStmt(Attr::POINTER, std::get<parser::Name>(x.t));
4794   }
4795 }
4796 
4797 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
4798   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
4799   auto &name{std::get<parser::Name>(x.t)};
4800   Symbol *symbol;
4801   if (kind == parser::BindEntity::Kind::Object) {
4802     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
4803   } else {
4804     symbol = &MakeCommonBlockSymbol(name);
4805     SetExplicitAttr(*symbol, Attr::BIND_C);
4806   }
4807   // 8.6.4(1)
4808   // Some entities such as named constant or module name need to checked
4809   // elsewhere. This is to skip the ICE caused by setting Bind name for non-name
4810   // things such as data type and also checks for procedures.
4811   if (symbol->has<CommonBlockDetails>() || symbol->has<ObjectEntityDetails>() ||
4812       symbol->has<EntityDetails>()) {
4813     SetBindNameOn(*symbol);
4814   } else {
4815     Say(name,
4816         "Only variable and named common block can be in BIND statement"_err_en_US);
4817   }
4818   return false;
4819 }
4820 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
4821   inOldStyleParameterStmt_ = true;
4822   Walk(x.v);
4823   inOldStyleParameterStmt_ = false;
4824   return false;
4825 }
4826 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
4827   auto &name{std::get<parser::NamedConstant>(x.t).v};
4828   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
4829   ConvertToObjectEntity(symbol);
4830   auto *details{symbol.detailsIf<ObjectEntityDetails>()};
4831   if (!details || symbol.test(Symbol::Flag::CrayPointer) ||
4832       symbol.test(Symbol::Flag::CrayPointee)) {
4833     SayWithDecl(
4834         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
4835     return false;
4836   }
4837   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
4838   if (details->init() || symbol.test(Symbol::Flag::InDataStmt)) {
4839     Say(name, "Named constant '%s' already has a value"_err_en_US);
4840   }
4841   if (inOldStyleParameterStmt_) {
4842     // non-standard extension PARAMETER statement (no parentheses)
4843     Walk(expr);
4844     auto folded{EvaluateExpr(expr)};
4845     if (details->type()) {
4846       SayWithDecl(name, symbol,
4847           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
4848     } else if (folded) {
4849       auto at{expr.thing.value().source};
4850       if (evaluate::IsActuallyConstant(*folded)) {
4851         if (const auto *type{currScope().GetType(*folded)}) {
4852           if (type->IsPolymorphic()) {
4853             Say(at, "The expression must not be polymorphic"_err_en_US);
4854           } else if (auto shape{ToArraySpec(
4855                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
4856             // The type of the named constant is assumed from the expression.
4857             details->set_type(*type);
4858             details->set_init(std::move(*folded));
4859             details->set_shape(std::move(*shape));
4860           } else {
4861             Say(at, "The expression must have constant shape"_err_en_US);
4862           }
4863         } else {
4864           Say(at, "The expression must have a known type"_err_en_US);
4865         }
4866       } else {
4867         Say(at, "The expression must be a constant of known type"_err_en_US);
4868       }
4869     }
4870   } else {
4871     // standard-conforming PARAMETER statement (with parentheses)
4872     ApplyImplicitRules(symbol);
4873     Walk(expr);
4874     if (auto converted{EvaluateNonPointerInitializer(
4875             symbol, expr, expr.thing.value().source)}) {
4876       details->set_init(std::move(*converted));
4877     }
4878   }
4879   return false;
4880 }
4881 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
4882   const parser::Name &name{x.v};
4883   if (!FindSymbol(name)) {
4884     Say(name, "Named constant '%s' not found"_err_en_US);
4885   } else {
4886     CheckUseError(name);
4887   }
4888   return false;
4889 }
4890 
4891 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
4892   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
4893   Symbol *symbol{FindInScope(name)};
4894   if (symbol && !symbol->has<UnknownDetails>()) {
4895     // Contrary to named constants appearing in a PARAMETER statement,
4896     // enumerator names should not have their type, dimension or any other
4897     // attributes defined before they are declared in the enumerator statement,
4898     // with the exception of accessibility.
4899     // This is not explicitly forbidden by the standard, but they are scalars
4900     // which type is left for the compiler to chose, so do not let users try to
4901     // tamper with that.
4902     SayAlreadyDeclared(name, *symbol);
4903     symbol = nullptr;
4904   } else {
4905     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
4906     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
4907     symbol->SetType(context().MakeNumericType(
4908         TypeCategory::Integer, evaluate::CInteger::kind));
4909   }
4910 
4911   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
4912           enumerator.t)}) {
4913     Walk(*init); // Resolve names in expression before evaluation.
4914     if (auto value{EvaluateInt64(context(), *init)}) {
4915       // Cast all init expressions to C_INT so that they can then be
4916       // safely incremented (see 7.6 Note 2).
4917       enumerationState_.value = static_cast<int>(*value);
4918     } else {
4919       Say(name,
4920           "Enumerator value could not be computed "
4921           "from the given expression"_err_en_US);
4922       // Prevent resolution of next enumerators value
4923       enumerationState_.value = std::nullopt;
4924     }
4925   }
4926 
4927   if (symbol) {
4928     if (enumerationState_.value) {
4929       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
4930           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
4931     } else {
4932       context().SetError(*symbol);
4933     }
4934   }
4935 
4936   if (enumerationState_.value) {
4937     (*enumerationState_.value)++;
4938   }
4939   return false;
4940 }
4941 
4942 void DeclarationVisitor::Post(const parser::EnumDef &) {
4943   enumerationState_ = EnumeratorState{};
4944 }
4945 
4946 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
4947   Attr attr{AccessSpecToAttr(x)};
4948   if (!NonDerivedTypeScope().IsModule()) { // C817
4949     Say(currStmtSource().value(),
4950         "%s attribute may only appear in the specification part of a module"_err_en_US,
4951         EnumToString(attr));
4952   }
4953   CheckAndSet(attr);
4954   return false;
4955 }
4956 
4957 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
4958   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
4959 }
4960 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
4961   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
4962 }
4963 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
4964   HandleAttributeStmt(Attr::EXTERNAL, x.v);
4965   for (const auto &name : x.v) {
4966     auto *symbol{FindSymbol(name)};
4967     if (!ConvertToProcEntity(DEREF(symbol), name.source)) {
4968       // Check if previous symbol is an interface.
4969       if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
4970         if (details->isInterface()) {
4971           // Warn if interface previously declared.
4972           context().Warn(common::LanguageFeature::RedundantAttribute,
4973               name.source,
4974               "EXTERNAL attribute was already specified on '%s'"_warn_en_US,
4975               name.source);
4976         }
4977       } else {
4978         SayWithDecl(
4979             name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
4980       }
4981     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
4982       Say(symbol->name(),
4983           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
4984           symbol->name());
4985     }
4986   }
4987   return false;
4988 }
4989 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
4990   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
4991   auto &names{std::get<std::list<parser::Name>>(x.t)};
4992   return CheckNotInBlock("INTENT") && // C1107
4993       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
4994 }
4995 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
4996   for (const auto &name : x.v) {
4997     DeclareIntrinsic(name);
4998   }
4999   return false;
5000 }
5001 void DeclarationVisitor::DeclareIntrinsic(const parser::Name &name) {
5002   HandleAttributeStmt(Attr::INTRINSIC, name);
5003   if (!IsIntrinsic(name.source, std::nullopt)) {
5004     Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
5005   }
5006   auto &symbol{DEREF(FindSymbol(name))};
5007   if (symbol.has<GenericDetails>()) {
5008     // Generic interface is extending intrinsic; ok
5009   } else if (!ConvertToProcEntity(symbol, name.source)) {
5010     SayWithDecl(
5011         name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
5012   } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
5013     Say(symbol.name(),
5014         "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
5015         symbol.name());
5016   } else {
5017     if (symbol.GetType()) {
5018       // These warnings are worded so that they should make sense in either
5019       // order.
5020       if (auto *msg{context().Warn(
5021               common::UsageWarning::IgnoredIntrinsicFunctionType, symbol.name(),
5022               "Explicit type declaration ignored for intrinsic function '%s'"_warn_en_US,
5023               symbol.name())}) {
5024         msg->Attach(name.source,
5025             "INTRINSIC statement for explicitly-typed '%s'"_en_US, name.source);
5026       }
5027     }
5028     if (!symbol.test(Symbol::Flag::Function) &&
5029         !symbol.test(Symbol::Flag::Subroutine)) {
5030       if (context().intrinsics().IsIntrinsicFunction(name.source.ToString())) {
5031         symbol.set(Symbol::Flag::Function);
5032       } else if (context().intrinsics().IsIntrinsicSubroutine(
5033                      name.source.ToString())) {
5034         symbol.set(Symbol::Flag::Subroutine);
5035       }
5036     }
5037   }
5038 }
5039 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
5040   return CheckNotInBlock("OPTIONAL") && // C1107
5041       HandleAttributeStmt(Attr::OPTIONAL, x.v);
5042 }
5043 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
5044   return HandleAttributeStmt(Attr::PROTECTED, x.v);
5045 }
5046 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
5047   return CheckNotInBlock("VALUE") && // C1107
5048       HandleAttributeStmt(Attr::VALUE, x.v);
5049 }
5050 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
5051   return HandleAttributeStmt(Attr::VOLATILE, x.v);
5052 }
5053 bool DeclarationVisitor::Pre(const parser::CUDAAttributesStmt &x) {
5054   auto attr{std::get<common::CUDADataAttr>(x.t)};
5055   for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
5056     auto *symbol{FindInScope(name)};
5057     if (symbol && symbol->has<UseDetails>()) {
5058       Say(currStmtSource().value(),
5059           "Cannot apply CUDA data attribute to use-associated '%s'"_err_en_US,
5060           name.source);
5061     } else {
5062       if (!symbol) {
5063         symbol = &MakeSymbol(name, ObjectEntityDetails{});
5064       }
5065       SetCUDADataAttr(name.source, *symbol, attr);
5066     }
5067   }
5068   return false;
5069 }
5070 // Handle a statement that sets an attribute on a list of names.
5071 bool DeclarationVisitor::HandleAttributeStmt(
5072     Attr attr, const std::list<parser::Name> &names) {
5073   for (const auto &name : names) {
5074     HandleAttributeStmt(attr, name);
5075   }
5076   return false;
5077 }
5078 Symbol &DeclarationVisitor::HandleAttributeStmt(
5079     Attr attr, const parser::Name &name) {
5080   auto *symbol{FindInScope(name)};
5081   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
5082     // these can be set on a symbol that is host-assoc or use-assoc
5083     if (!symbol &&
5084         (currScope().kind() == Scope::Kind::Subprogram ||
5085             currScope().kind() == Scope::Kind::BlockConstruct)) {
5086       if (auto *hostSymbol{FindSymbol(name)}) {
5087         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
5088       }
5089     }
5090   } else if (symbol && symbol->has<UseDetails>()) {
5091     if (symbol->GetUltimate().attrs().test(attr)) {
5092       context().Warn(common::LanguageFeature::RedundantAttribute,
5093           currStmtSource().value(),
5094           "Use-associated '%s' already has '%s' attribute"_warn_en_US,
5095           name.source, EnumToString(attr));
5096     } else {
5097       Say(currStmtSource().value(),
5098           "Cannot change %s attribute on use-associated '%s'"_err_en_US,
5099           EnumToString(attr), name.source);
5100     }
5101     return *symbol;
5102   }
5103   if (!symbol) {
5104     symbol = &MakeSymbol(name, EntityDetails{});
5105   }
5106   if (CheckDuplicatedAttr(name.source, *symbol, attr)) {
5107     HandleSaveName(name.source, Attrs{attr});
5108     SetExplicitAttr(*symbol, attr);
5109   }
5110   return *symbol;
5111 }
5112 // C1107
5113 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
5114   if (currScope().kind() == Scope::Kind::BlockConstruct) {
5115     Say(MessageFormattedText{
5116         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
5117     return false;
5118   } else {
5119     return true;
5120   }
5121 }
5122 
5123 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
5124   CHECK(objectDeclAttr_);
5125   const auto &name{std::get<parser::ObjectName>(x.t)};
5126   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
5127 }
5128 
5129 // Declare an entity not yet known to be an object or proc.
5130 Symbol &DeclarationVisitor::DeclareUnknownEntity(
5131     const parser::Name &name, Attrs attrs) {
5132   if (!arraySpec().empty() || !coarraySpec().empty()) {
5133     return DeclareObjectEntity(name, attrs);
5134   } else {
5135     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
5136     if (auto *type{GetDeclTypeSpec()}) {
5137       SetType(name, *type);
5138     }
5139     charInfo_.length.reset();
5140     if (symbol.attrs().test(Attr::EXTERNAL)) {
5141       ConvertToProcEntity(symbol);
5142     } else if (symbol.attrs().HasAny(Attrs{Attr::ALLOCATABLE,
5143                    Attr::ASYNCHRONOUS, Attr::CONTIGUOUS, Attr::PARAMETER,
5144                    Attr::SAVE, Attr::TARGET, Attr::VALUE, Attr::VOLATILE})) {
5145       ConvertToObjectEntity(symbol);
5146     }
5147     if (attrs.test(Attr::BIND_C)) {
5148       SetBindNameOn(symbol);
5149     }
5150     return symbol;
5151   }
5152 }
5153 
5154 bool DeclarationVisitor::HasCycle(
5155     const Symbol &procSymbol, const Symbol *interface) {
5156   SourceOrderedSymbolSet procsInCycle;
5157   procsInCycle.insert(procSymbol);
5158   while (interface) {
5159     if (procsInCycle.count(*interface) > 0) {
5160       for (const auto &procInCycle : procsInCycle) {
5161         Say(procInCycle->name(),
5162             "The interface for procedure '%s' is recursively defined"_err_en_US,
5163             procInCycle->name());
5164         context().SetError(*procInCycle);
5165       }
5166       return true;
5167     } else if (const auto *procDetails{
5168                    interface->detailsIf<ProcEntityDetails>()}) {
5169       procsInCycle.insert(*interface);
5170       interface = procDetails->procInterface();
5171     } else {
5172       break;
5173     }
5174   }
5175   return false;
5176 }
5177 
5178 Symbol &DeclarationVisitor::DeclareProcEntity(
5179     const parser::Name &name, Attrs attrs, const Symbol *interface) {
5180   Symbol *proc{nullptr};
5181   if (auto *extant{FindInScope(name)}) {
5182     if (auto *d{extant->detailsIf<GenericDetails>()}; d && !d->derivedType()) {
5183       // procedure pointer with same name as a generic
5184       if (auto *specific{d->specific()}) {
5185         SayAlreadyDeclared(name, *specific);
5186       } else {
5187         // Create the ProcEntityDetails symbol in the scope as the "specific()"
5188         // symbol behind an existing GenericDetails symbol of the same name.
5189         proc = &Resolve(name,
5190             currScope().MakeSymbol(name.source, attrs, ProcEntityDetails{}));
5191         d->set_specific(*proc);
5192       }
5193     }
5194   }
5195   Symbol &symbol{proc ? *proc : DeclareEntity<ProcEntityDetails>(name, attrs)};
5196   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
5197     if (context().HasError(symbol)) {
5198     } else if (HasCycle(symbol, interface)) {
5199       return symbol;
5200     } else if (interface && (details->procInterface() || details->type())) {
5201       SayWithDecl(name, symbol,
5202           "The interface for procedure '%s' has already been declared"_err_en_US);
5203       context().SetError(symbol);
5204     } else if (interface) {
5205       details->set_procInterfaces(
5206           *interface, BypassGeneric(interface->GetUltimate()));
5207       if (interface->test(Symbol::Flag::Function)) {
5208         symbol.set(Symbol::Flag::Function);
5209       } else if (interface->test(Symbol::Flag::Subroutine)) {
5210         symbol.set(Symbol::Flag::Subroutine);
5211       }
5212     } else if (auto *type{GetDeclTypeSpec()}) {
5213       SetType(name, *type);
5214       symbol.set(Symbol::Flag::Function);
5215     }
5216     SetBindNameOn(symbol);
5217     SetPassNameOn(symbol);
5218   }
5219   return symbol;
5220 }
5221 
5222 Symbol &DeclarationVisitor::DeclareObjectEntity(
5223     const parser::Name &name, Attrs attrs) {
5224   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
5225   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
5226     if (auto *type{GetDeclTypeSpec()}) {
5227       SetType(name, *type);
5228     }
5229     if (!arraySpec().empty()) {
5230       if (details->IsArray()) {
5231         if (!context().HasError(symbol)) {
5232           Say(name,
5233               "The dimensions of '%s' have already been declared"_err_en_US);
5234           context().SetError(symbol);
5235         }
5236       } else if (MustBeScalar(symbol)) {
5237         context().Warn(common::UsageWarning::PreviousScalarUse, name.source,
5238             "'%s' appeared earlier as a scalar actual argument to a specification function"_warn_en_US,
5239             name.source);
5240       } else if (details->init() || symbol.test(Symbol::Flag::InDataStmt)) {
5241         Say(name, "'%s' was initialized earlier as a scalar"_err_en_US);
5242       } else {
5243         details->set_shape(arraySpec());
5244       }
5245     }
5246     if (!coarraySpec().empty()) {
5247       if (details->IsCoarray()) {
5248         if (!context().HasError(symbol)) {
5249           Say(name,
5250               "The codimensions of '%s' have already been declared"_err_en_US);
5251           context().SetError(symbol);
5252         }
5253       } else {
5254         details->set_coshape(coarraySpec());
5255       }
5256     }
5257     SetBindNameOn(symbol);
5258   }
5259   ClearArraySpec();
5260   ClearCoarraySpec();
5261   charInfo_.length.reset();
5262   return symbol;
5263 }
5264 
5265 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
5266   if (!isVectorType_) {
5267     SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
5268   }
5269 }
5270 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
5271   if (!isVectorType_) {
5272     SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
5273   }
5274 }
5275 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
5276   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
5277 }
5278 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
5279   SetDeclTypeSpec(MakeLogicalType(x.kind));
5280 }
5281 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
5282   if (!charInfo_.length) {
5283     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
5284   }
5285   if (!charInfo_.kind) {
5286     charInfo_.kind =
5287         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
5288   }
5289   SetDeclTypeSpec(currScope().MakeCharacterType(
5290       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
5291   charInfo_ = {};
5292 }
5293 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
5294   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
5295   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
5296   if (intKind &&
5297       !context().targetCharacteristics().IsTypeEnabled(
5298           TypeCategory::Character, *intKind)) { // C715, C719
5299     Say(currStmtSource().value(),
5300         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
5301     charInfo_.kind = std::nullopt; // prevent further errors
5302   }
5303   if (x.length) {
5304     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
5305   }
5306 }
5307 void DeclarationVisitor::Post(const parser::CharLength &x) {
5308   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
5309     charInfo_.length = ParamValue{
5310         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
5311   } else {
5312     charInfo_.length = GetParamValue(
5313         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
5314   }
5315 }
5316 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
5317   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
5318     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
5319   }
5320 }
5321 
5322 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
5323   if (const auto *kind{std::get_if<
5324           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
5325           &x.u)}) {
5326     const parser::Name &name{kind->thing.thing.thing};
5327     if (!FindSymbol(name)) {
5328       Say(name, "Parameter '%s' not found"_err_en_US);
5329     }
5330   }
5331   return false;
5332 }
5333 
5334 int DeclarationVisitor::GetVectorElementKind(
5335     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
5336   KindExpr value{GetKindParamExpr(category, kind)};
5337   if (auto known{evaluate::ToInt64(value)}) {
5338     return static_cast<int>(*known);
5339   }
5340   common::die("Vector element kind must be known at compile-time");
5341 }
5342 
5343 bool DeclarationVisitor::Pre(const parser::VectorTypeSpec &) {
5344   // PowerPC vector types are allowed only on Power architectures.
5345   if (!currScope().context().targetCharacteristics().isPPC()) {
5346     Say(currStmtSource().value(),
5347         "Vector type is only supported for PowerPC"_err_en_US);
5348     isVectorType_ = false;
5349     return false;
5350   }
5351   isVectorType_ = true;
5352   return true;
5353 }
5354 // Create semantic::DerivedTypeSpec for Vector types here.
5355 void DeclarationVisitor::Post(const parser::VectorTypeSpec &x) {
5356   llvm::StringRef typeName;
5357   llvm::SmallVector<ParamValue> typeParams;
5358   DerivedTypeSpec::Category vectorCategory;
5359 
5360   isVectorType_ = false;
5361   common::visit(
5362       common::visitors{
5363           [&](const parser::IntrinsicVectorTypeSpec &y) {
5364             vectorCategory = DerivedTypeSpec::Category::IntrinsicVector;
5365             int vecElemKind = 0;
5366             typeName = "__builtin_ppc_intrinsic_vector";
5367             common::visit(
5368                 common::visitors{
5369                     [&](const parser::IntegerTypeSpec &z) {
5370                       vecElemKind = GetVectorElementKind(
5371                           TypeCategory::Integer, std::move(z.v));
5372                       typeParams.push_back(ParamValue(
5373                           static_cast<common::ConstantSubscript>(
5374                               common::VectorElementCategory::Integer),
5375                           common::TypeParamAttr::Kind));
5376                     },
5377                     [&](const parser::IntrinsicTypeSpec::Real &z) {
5378                       vecElemKind = GetVectorElementKind(
5379                           TypeCategory::Real, std::move(z.kind));
5380                       typeParams.push_back(
5381                           ParamValue(static_cast<common::ConstantSubscript>(
5382                                          common::VectorElementCategory::Real),
5383                               common::TypeParamAttr::Kind));
5384                     },
5385                     [&](const parser::UnsignedTypeSpec &z) {
5386                       vecElemKind = GetVectorElementKind(
5387                           TypeCategory::Integer, std::move(z.v));
5388                       typeParams.push_back(ParamValue(
5389                           static_cast<common::ConstantSubscript>(
5390                               common::VectorElementCategory::Unsigned),
5391                           common::TypeParamAttr::Kind));
5392                     },
5393                 },
5394                 y.v.u);
5395             typeParams.push_back(
5396                 ParamValue(static_cast<common::ConstantSubscript>(vecElemKind),
5397                     common::TypeParamAttr::Kind));
5398           },
5399           [&](const parser::VectorTypeSpec::PairVectorTypeSpec &y) {
5400             vectorCategory = DerivedTypeSpec::Category::PairVector;
5401             typeName = "__builtin_ppc_pair_vector";
5402           },
5403           [&](const parser::VectorTypeSpec::QuadVectorTypeSpec &y) {
5404             vectorCategory = DerivedTypeSpec::Category::QuadVector;
5405             typeName = "__builtin_ppc_quad_vector";
5406           },
5407       },
5408       x.u);
5409 
5410   auto ppcBuiltinTypesScope = currScope().context().GetPPCBuiltinTypesScope();
5411   if (!ppcBuiltinTypesScope) {
5412     common::die("INTERNAL: The __ppc_types module was not found ");
5413   }
5414 
5415   auto iter{ppcBuiltinTypesScope->find(
5416       semantics::SourceName{typeName.data(), typeName.size()})};
5417   if (iter == ppcBuiltinTypesScope->cend()) {
5418     common::die("INTERNAL: The __ppc_types module does not define "
5419                 "the type '%s'",
5420         typeName.data());
5421   }
5422 
5423   const semantics::Symbol &typeSymbol{*iter->second};
5424   DerivedTypeSpec vectorDerivedType{typeName.data(), typeSymbol};
5425   vectorDerivedType.set_category(vectorCategory);
5426   if (typeParams.size()) {
5427     vectorDerivedType.AddRawParamValue(nullptr, std::move(typeParams[0]));
5428     vectorDerivedType.AddRawParamValue(nullptr, std::move(typeParams[1]));
5429     vectorDerivedType.CookParameters(GetFoldingContext());
5430   }
5431 
5432   if (const DeclTypeSpec *
5433       extant{ppcBuiltinTypesScope->FindInstantiatedDerivedType(
5434           vectorDerivedType, DeclTypeSpec::Category::TypeDerived)}) {
5435     // This derived type and parameter expressions (if any) are already present
5436     // in the __ppc_intrinsics scope.
5437     SetDeclTypeSpec(*extant);
5438   } else {
5439     DeclTypeSpec &type{ppcBuiltinTypesScope->MakeDerivedType(
5440         DeclTypeSpec::Category::TypeDerived, std::move(vectorDerivedType))};
5441     DerivedTypeSpec &derived{type.derivedTypeSpec()};
5442     auto restorer{
5443         GetFoldingContext().messages().SetLocation(currStmtSource().value())};
5444     derived.Instantiate(*ppcBuiltinTypesScope);
5445     SetDeclTypeSpec(type);
5446   }
5447 }
5448 
5449 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
5450   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
5451   return true;
5452 }
5453 
5454 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
5455   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
5456   if (const Symbol * derivedSymbol{derivedName.symbol}) {
5457     CheckForAbstractType(*derivedSymbol); // C706
5458   }
5459 }
5460 
5461 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
5462   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
5463   return true;
5464 }
5465 
5466 void DeclarationVisitor::Post(
5467     const parser::DeclarationTypeSpec::Class &parsedClass) {
5468   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
5469   if (auto spec{ResolveDerivedType(typeName)};
5470       spec && !IsExtensibleType(&*spec)) { // C705
5471     SayWithDecl(typeName, *typeName.symbol,
5472         "Non-extensible derived type '%s' may not be used with CLASS"
5473         " keyword"_err_en_US);
5474   }
5475 }
5476 
5477 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
5478   const auto &typeName{std::get<parser::Name>(x.t)};
5479   auto spec{ResolveDerivedType(typeName)};
5480   if (!spec) {
5481     return;
5482   }
5483   bool seenAnyName{false};
5484   for (const auto &typeParamSpec :
5485       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
5486     const auto &optKeyword{
5487         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
5488     std::optional<SourceName> name;
5489     if (optKeyword) {
5490       seenAnyName = true;
5491       name = optKeyword->v.source;
5492     } else if (seenAnyName) {
5493       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
5494       continue;
5495     }
5496     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
5497     // The expressions in a derived type specifier whose values define
5498     // non-defaulted type parameters are evaluated (folded) in the enclosing
5499     // scope.  The KIND/LEN distinction is resolved later in
5500     // DerivedTypeSpec::CookParameters().
5501     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
5502     if (!param.isExplicit() || param.GetExplicit()) {
5503       spec->AddRawParamValue(
5504           common::GetPtrFromOptional(optKeyword), std::move(param));
5505     }
5506   }
5507   // The DerivedTypeSpec *spec is used initially as a search key.
5508   // If it turns out to have the same name and actual parameter
5509   // value expressions as another DerivedTypeSpec in the current
5510   // scope does, then we'll use that extant spec; otherwise, when this
5511   // spec is distinct from all derived types previously instantiated
5512   // in the current scope, this spec will be moved into that collection.
5513   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
5514   auto category{GetDeclTypeSpecCategory()};
5515   if (dtDetails.isForwardReferenced()) {
5516     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
5517     SetDeclTypeSpec(type);
5518     return;
5519   }
5520   // Normalize parameters to produce a better search key.
5521   spec->CookParameters(GetFoldingContext());
5522   if (!spec->MightBeParameterized()) {
5523     spec->EvaluateParameters(context());
5524   }
5525   if (const DeclTypeSpec *
5526       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
5527     // This derived type and parameter expressions (if any) are already present
5528     // in this scope.
5529     SetDeclTypeSpec(*extant);
5530   } else {
5531     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
5532     DerivedTypeSpec &derived{type.derivedTypeSpec()};
5533     if (derived.MightBeParameterized() &&
5534         currScope().IsParameterizedDerivedType()) {
5535       // Defer instantiation; use the derived type's definition's scope.
5536       derived.set_scope(DEREF(spec->typeSymbol().scope()));
5537     } else if (&currScope() == spec->typeSymbol().scope()) {
5538       // Direct recursive use of a type in the definition of one of its
5539       // components: defer instantiation
5540     } else {
5541       auto restorer{
5542           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
5543       derived.Instantiate(currScope());
5544     }
5545     SetDeclTypeSpec(type);
5546   }
5547   // Capture the DerivedTypeSpec in the parse tree for use in building
5548   // structure constructor expressions.
5549   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
5550 }
5551 
5552 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
5553   const auto &typeName{rec.v};
5554   if (auto spec{ResolveDerivedType(typeName)}) {
5555     spec->CookParameters(GetFoldingContext());
5556     spec->EvaluateParameters(context());
5557     if (const DeclTypeSpec *
5558         extant{currScope().FindInstantiatedDerivedType(
5559             *spec, DeclTypeSpec::TypeDerived)}) {
5560       SetDeclTypeSpec(*extant);
5561     } else {
5562       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
5563           typeName.source);
5564     }
5565   }
5566 }
5567 
5568 // The descendents of DerivedTypeDef in the parse tree are visited directly
5569 // in this Pre() routine so that recursive use of the derived type can be
5570 // supported in the components.
5571 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
5572   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
5573   Walk(stmt);
5574   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
5575   auto &scope{currScope()};
5576   CHECK(scope.symbol());
5577   CHECK(scope.symbol()->scope() == &scope);
5578   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
5579   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
5580     if (auto *symbol{FindInScope(scope, paramName)}) {
5581       if (auto *details{symbol->detailsIf<TypeParamDetails>()}) {
5582         if (!details->attr()) {
5583           Say(paramName,
5584               "No definition found for type parameter '%s'"_err_en_US); // C742
5585         }
5586       }
5587     }
5588   }
5589   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
5590   const auto &componentDefs{
5591       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
5592   Walk(componentDefs);
5593   if (derivedTypeInfo_.sequence) {
5594     details.set_sequence(true);
5595     if (componentDefs.empty()) {
5596       // F'2023 C745 - not enforced by any compiler
5597       context().Warn(common::LanguageFeature::EmptySequenceType, stmt.source,
5598           "A sequence type should have at least one component"_warn_en_US);
5599     }
5600     if (!details.paramDeclOrder().empty()) { // C740
5601       Say(stmt.source,
5602           "A sequence type may not have type parameters"_err_en_US);
5603     }
5604     if (derivedTypeInfo_.extends) { // C735
5605       Say(stmt.source,
5606           "A sequence type may not have the EXTENDS attribute"_err_en_US);
5607     }
5608   }
5609   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
5610   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
5611   details.set_isForwardReferenced(false);
5612   derivedTypeInfo_ = {};
5613   PopScope();
5614   return false;
5615 }
5616 
5617 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
5618   return BeginAttrs();
5619 }
5620 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
5621   auto &name{std::get<parser::Name>(x.t)};
5622   // Resolve the EXTENDS() clause before creating the derived
5623   // type's symbol to foil attempts to recursively extend a type.
5624   auto *extendsName{derivedTypeInfo_.extends};
5625   std::optional<DerivedTypeSpec> extendsType{
5626       ResolveExtendsType(name, extendsName)};
5627   DerivedTypeDetails derivedTypeDetails;
5628   // Catch any premature structure constructors within the definition
5629   derivedTypeDetails.set_isForwardReferenced(true);
5630   auto &symbol{MakeSymbol(name, GetAttrs(), std::move(derivedTypeDetails))};
5631   symbol.ReplaceName(name.source);
5632   derivedTypeInfo_.type = &symbol;
5633   PushScope(Scope::Kind::DerivedType, &symbol);
5634   if (extendsType) {
5635     // Declare the "parent component"; private if the type is.
5636     // Any symbol stored in the EXTENDS() clause is temporarily
5637     // hidden so that a new symbol can be created for the parent
5638     // component without producing spurious errors about already
5639     // existing.
5640     const Symbol &extendsSymbol{extendsType->typeSymbol()};
5641     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
5642     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
5643       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
5644       comp.attrs().set(
5645           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
5646       comp.implicitAttrs().set(
5647           Attr::PRIVATE, extendsSymbol.implicitAttrs().test(Attr::PRIVATE));
5648       comp.set(Symbol::Flag::ParentComp);
5649       DeclTypeSpec &type{currScope().MakeDerivedType(
5650           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
5651       type.derivedTypeSpec().set_scope(DEREF(extendsSymbol.scope()));
5652       comp.SetType(type);
5653       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
5654       details.add_component(comp);
5655     }
5656   }
5657   // Create symbols now for type parameters so that they shadow names
5658   // from the enclosing specification part.
5659   if (auto *details{symbol.detailsIf<DerivedTypeDetails>()}) {
5660     for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
5661       if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{})}) {
5662         details->add_paramNameOrder(*symbol);
5663       }
5664     }
5665   }
5666   EndAttrs();
5667 }
5668 
5669 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
5670   auto *type{GetDeclTypeSpec()};
5671   DerivedTypeDetails *derivedDetails{nullptr};
5672   if (Symbol * dtSym{currScope().symbol()}) {
5673     derivedDetails = dtSym->detailsIf<DerivedTypeDetails>();
5674   }
5675   auto attr{std::get<common::TypeParamAttr>(x.t)};
5676   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
5677     auto &name{std::get<parser::Name>(decl.t)};
5678     if (Symbol * symbol{FindInScope(currScope(), name)}) {
5679       if (auto *paramDetails{symbol->detailsIf<TypeParamDetails>()}) {
5680         if (!paramDetails->attr()) {
5681           paramDetails->set_attr(attr);
5682           SetType(name, *type);
5683           if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
5684                   decl.t)}) {
5685             if (auto maybeExpr{AnalyzeExpr(context(), *init)}) {
5686               if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
5687                 paramDetails->set_init(std::move(*intExpr));
5688               }
5689             }
5690           }
5691           if (derivedDetails) {
5692             derivedDetails->add_paramDeclOrder(*symbol);
5693           }
5694         } else {
5695           Say(name,
5696               "Type parameter '%s' was already declared in this derived type"_err_en_US);
5697         }
5698       }
5699     } else {
5700       Say(name, "'%s' is not a parameter of this derived type"_err_en_US);
5701     }
5702   }
5703   EndDecl();
5704 }
5705 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
5706   if (derivedTypeInfo_.extends) {
5707     Say(currStmtSource().value(),
5708         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
5709   } else {
5710     derivedTypeInfo_.extends = &x.v;
5711   }
5712   return false;
5713 }
5714 
5715 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
5716   if (!currScope().parent().IsModule()) {
5717     Say("PRIVATE is only allowed in a derived type that is"
5718         " in a module"_err_en_US); // C766
5719   } else if (derivedTypeInfo_.sawContains) {
5720     derivedTypeInfo_.privateBindings = true;
5721   } else if (!derivedTypeInfo_.privateComps) {
5722     derivedTypeInfo_.privateComps = true;
5723   } else { // C738
5724     context().Warn(common::LanguageFeature::RedundantAttribute,
5725         "PRIVATE should not appear more than once in derived type components"_warn_en_US);
5726   }
5727   return false;
5728 }
5729 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
5730   if (derivedTypeInfo_.sequence) { // C738
5731     context().Warn(common::LanguageFeature::RedundantAttribute,
5732         "SEQUENCE should not appear more than once in derived type components"_warn_en_US);
5733   }
5734   derivedTypeInfo_.sequence = true;
5735   return false;
5736 }
5737 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
5738   const auto &name{std::get<parser::Name>(x.t)};
5739   auto attrs{GetAttrs()};
5740   if (derivedTypeInfo_.privateComps &&
5741       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
5742     attrs.set(Attr::PRIVATE);
5743   }
5744   if (const auto *declType{GetDeclTypeSpec()}) {
5745     if (const auto *derived{declType->AsDerived()}) {
5746       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
5747         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
5748           Say("Recursive use of the derived type requires "
5749               "POINTER or ALLOCATABLE"_err_en_US);
5750         }
5751       }
5752       // TODO: This would be more appropriate in CheckDerivedType()
5753       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
5754         std::string ultimateName{it.BuildResultDesignatorName()};
5755         // Strip off the leading "%"
5756         if (ultimateName.length() > 1) {
5757           ultimateName.erase(0, 1);
5758           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
5759             evaluate::AttachDeclaration(
5760                 Say(name.source,
5761                     "A component with a POINTER or ALLOCATABLE attribute may "
5762                     "not "
5763                     "be of a type with a coarray ultimate component (named "
5764                     "'%s')"_err_en_US,
5765                     ultimateName),
5766                 derived->typeSymbol());
5767           }
5768           if (!arraySpec().empty() || !coarraySpec().empty()) {
5769             evaluate::AttachDeclaration(
5770                 Say(name.source,
5771                     "An array or coarray component may not be of a type with a "
5772                     "coarray ultimate component (named '%s')"_err_en_US,
5773                     ultimateName),
5774                 derived->typeSymbol());
5775           }
5776         }
5777       }
5778     }
5779   }
5780   if (OkToAddComponent(name)) {
5781     auto &symbol{DeclareObjectEntity(name, attrs)};
5782     SetCUDADataAttr(name.source, symbol, cudaDataAttr());
5783     if (symbol.has<ObjectEntityDetails>()) {
5784       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
5785         Initialization(name, *init, true);
5786       }
5787     }
5788     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
5789   }
5790   ClearArraySpec();
5791   ClearCoarraySpec();
5792 }
5793 void DeclarationVisitor::Post(const parser::FillDecl &x) {
5794   // Replace "%FILL" with a distinct generated name
5795   const auto &name{std::get<parser::Name>(x.t)};
5796   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
5797   if (OkToAddComponent(name)) {
5798     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
5799     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
5800   }
5801   ClearArraySpec();
5802 }
5803 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &x) {
5804   CHECK(!interfaceName_);
5805   const auto &procAttrSpec{std::get<std::list<parser::ProcAttrSpec>>(x.t)};
5806   for (const parser::ProcAttrSpec &procAttr : procAttrSpec) {
5807     if (auto *bindC{std::get_if<parser::LanguageBindingSpec>(&procAttr.u)}) {
5808       if (std::get<std::optional<parser::ScalarDefaultCharConstantExpr>>(
5809               bindC->t)
5810               .has_value()) {
5811         if (std::get<std::list<parser::ProcDecl>>(x.t).size() > 1) {
5812           Say(context().location().value(),
5813               "A procedure declaration statement with a binding name may not declare multiple procedures"_err_en_US);
5814         }
5815         break;
5816       }
5817     }
5818   }
5819   return BeginDecl();
5820 }
5821 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
5822   interfaceName_ = nullptr;
5823   EndDecl();
5824 }
5825 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
5826   // Overrides parse tree traversal so as to handle attributes first,
5827   // so POINTER & ALLOCATABLE enable forward references to derived types.
5828   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
5829   set_allowForwardReferenceToDerivedType(
5830       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
5831   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
5832   set_allowForwardReferenceToDerivedType(false);
5833   if (derivedTypeInfo_.sequence) { // C740
5834     if (const auto *declType{GetDeclTypeSpec()}) {
5835       if (!declType->AsIntrinsic() && !declType->IsSequenceType() &&
5836           !InModuleFile()) {
5837         if (GetAttrs().test(Attr::POINTER) &&
5838             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
5839           context().Warn(common::LanguageFeature::PointerInSeqType,
5840               "A sequence type data component that is a pointer to a non-sequence type is not standard"_port_en_US);
5841         } else {
5842           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
5843         }
5844       }
5845     }
5846   }
5847   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
5848   return false;
5849 }
5850 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
5851   CHECK(!interfaceName_);
5852   return true;
5853 }
5854 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
5855   interfaceName_ = nullptr;
5856 }
5857 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
5858   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
5859     return !NameIsKnownOrIntrinsic(*name) && !CheckUseError(*name);
5860   } else {
5861     const auto &null{DEREF(std::get_if<parser::NullInit>(&x.u))};
5862     Walk(null);
5863     if (auto nullInit{EvaluateExpr(null)}) {
5864       if (!evaluate::IsNullPointer(*nullInit)) {
5865         Say(null.v.value().source,
5866             "Procedure pointer initializer must be a name or intrinsic NULL()"_err_en_US);
5867       }
5868     }
5869     return false;
5870   }
5871 }
5872 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
5873   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
5874     interfaceName_ = name;
5875     NoteInterfaceName(*name);
5876   }
5877 }
5878 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
5879   const auto &name{std::get<parser::Name>(x.t)};
5880   // Don't use BypassGeneric or GetUltimate on this symbol, they can
5881   // lead to unusable names in module files.
5882   const Symbol *procInterface{
5883       interfaceName_ ? interfaceName_->symbol : nullptr};
5884   auto attrs{HandleSaveName(name.source, GetAttrs())};
5885   DerivedTypeDetails *dtDetails{nullptr};
5886   if (Symbol * symbol{currScope().symbol()}) {
5887     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
5888   }
5889   if (!dtDetails) {
5890     attrs.set(Attr::EXTERNAL);
5891   }
5892   Symbol &symbol{DeclareProcEntity(name, attrs, procInterface)};
5893   SetCUDADataAttr(name.source, symbol, cudaDataAttr()); // for error
5894   symbol.ReplaceName(name.source);
5895   if (dtDetails) {
5896     dtDetails->add_component(symbol);
5897   }
5898   DeclaredPossibleSpecificProc(symbol);
5899 }
5900 
5901 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
5902   derivedTypeInfo_.sawContains = true;
5903   return true;
5904 }
5905 
5906 // Resolve binding names from type-bound generics, saved in genericBindings_.
5907 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
5908   // track specifics seen for the current generic to detect duplicates:
5909   const Symbol *currGeneric{nullptr};
5910   std::set<SourceName> specifics;
5911   for (const auto &[generic, bindingName] : genericBindings_) {
5912     if (generic != currGeneric) {
5913       currGeneric = generic;
5914       specifics.clear();
5915     }
5916     auto [it, inserted]{specifics.insert(bindingName->source)};
5917     if (!inserted) {
5918       Say(*bindingName, // C773
5919           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
5920           bindingName->source, generic->name())
5921           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
5922       continue;
5923     }
5924     auto *symbol{FindInTypeOrParents(*bindingName)};
5925     if (!symbol) {
5926       Say(*bindingName, // C772
5927           "Binding name '%s' not found in this derived type"_err_en_US);
5928     } else if (!symbol->has<ProcBindingDetails>()) {
5929       SayWithDecl(*bindingName, *symbol, // C772
5930           "'%s' is not the name of a specific binding of this type"_err_en_US);
5931     } else {
5932       generic->get<GenericDetails>().AddSpecificProc(
5933           *symbol, bindingName->source);
5934     }
5935   }
5936   genericBindings_.clear();
5937 }
5938 
5939 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
5940   if (derivedTypeInfo_.sequence) {
5941     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
5942   }
5943 }
5944 
5945 void DeclarationVisitor::Post(
5946     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
5947   if (GetAttrs().test(Attr::DEFERRED)) { // C783
5948     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
5949   }
5950   for (auto &declaration : x.declarations) {
5951     auto &bindingName{std::get<parser::Name>(declaration.t)};
5952     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
5953     const parser::Name &procedureName{optName ? *optName : bindingName};
5954     Symbol *procedure{FindSymbol(procedureName)};
5955     if (!procedure) {
5956       procedure = NoteInterfaceName(procedureName);
5957     }
5958     if (procedure) {
5959       const Symbol &bindTo{BypassGeneric(*procedure)};
5960       if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{bindTo})}) {
5961         SetPassNameOn(*s);
5962         if (GetAttrs().test(Attr::DEFERRED)) {
5963           context().SetError(*s);
5964         }
5965       }
5966     }
5967   }
5968 }
5969 
5970 void DeclarationVisitor::CheckBindings(
5971     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
5972   CHECK(currScope().IsDerivedType());
5973   for (auto &declaration : tbps.declarations) {
5974     auto &bindingName{std::get<parser::Name>(declaration.t)};
5975     if (Symbol * binding{FindInScope(bindingName)}) {
5976       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
5977         const Symbol &ultimate{details->symbol().GetUltimate()};
5978         const Symbol &procedure{BypassGeneric(ultimate)};
5979         if (&procedure != &ultimate) {
5980           details->ReplaceSymbol(procedure);
5981         }
5982         if (!CanBeTypeBoundProc(procedure)) {
5983           if (details->symbol().name() != binding->name()) {
5984             Say(binding->name(),
5985                 "The binding of '%s' ('%s') must be either an accessible "
5986                 "module procedure or an external procedure with "
5987                 "an explicit interface"_err_en_US,
5988                 binding->name(), details->symbol().name());
5989           } else {
5990             Say(binding->name(),
5991                 "'%s' must be either an accessible module procedure "
5992                 "or an external procedure with an explicit interface"_err_en_US,
5993                 binding->name());
5994           }
5995           context().SetError(*binding);
5996         }
5997       }
5998     }
5999   }
6000 }
6001 
6002 void DeclarationVisitor::Post(
6003     const parser::TypeBoundProcedureStmt::WithInterface &x) {
6004   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
6005     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
6006   }
6007   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
6008     for (auto &bindingName : x.bindingNames) {
6009       if (auto *s{
6010               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
6011         SetPassNameOn(*s);
6012         if (!GetAttrs().test(Attr::DEFERRED)) {
6013           context().SetError(*s);
6014         }
6015       }
6016     }
6017   }
6018 }
6019 
6020 bool DeclarationVisitor::Pre(const parser::FinalProcedureStmt &x) {
6021   if (currScope().IsDerivedType() && currScope().symbol()) {
6022     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
6023       for (const auto &subrName : x.v) {
6024         Symbol *symbol{FindSymbol(subrName)};
6025         if (!symbol) {
6026           // FINAL procedures must be module subroutines
6027           symbol = &MakeSymbol(
6028               currScope().parent(), subrName.source, Attrs{Attr::MODULE});
6029           Resolve(subrName, symbol);
6030           symbol->set_details(ProcEntityDetails{});
6031           symbol->set(Symbol::Flag::Subroutine);
6032         }
6033         if (auto pair{details->finals().emplace(subrName.source, *symbol)};
6034             !pair.second) { // C787
6035           Say(subrName.source,
6036               "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
6037               subrName.source)
6038               .Attach(pair.first->first,
6039                   "earlier appearance of this FINAL subroutine"_en_US);
6040         }
6041       }
6042     }
6043   }
6044   return false;
6045 }
6046 
6047 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
6048   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
6049   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
6050   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
6051   GenericSpecInfo info{genericSpec.value()};
6052   SourceName symbolName{info.symbolName()};
6053   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
6054                             : derivedTypeInfo_.privateBindings};
6055   auto *genericSymbol{FindInScope(symbolName)};
6056   if (genericSymbol) {
6057     if (!genericSymbol->has<GenericDetails>()) {
6058       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
6059     }
6060   } else {
6061     // look in ancestor types for a generic of the same name
6062     for (const auto &name : GetAllNames(context(), symbolName)) {
6063       if (Symbol * inherited{currScope().FindComponent(SourceName{name})}) {
6064         if (inherited->has<GenericDetails>()) {
6065           CheckAccessibility(symbolName, isPrivate, *inherited); // C771
6066         } else {
6067           Say(symbolName,
6068               "Type bound generic procedure '%s' may not have the same name as a non-generic symbol inherited from an ancestor type"_err_en_US)
6069               .Attach(inherited->name(), "Inherited symbol"_en_US);
6070         }
6071         break;
6072       }
6073     }
6074   }
6075   if (genericSymbol) {
6076     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
6077   } else {
6078     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
6079     if (!genericSymbol) {
6080       return false;
6081     }
6082     if (isPrivate) {
6083       SetExplicitAttr(*genericSymbol, Attr::PRIVATE);
6084     }
6085   }
6086   for (const parser::Name &bindingName : bindingNames) {
6087     genericBindings_.emplace(genericSymbol, &bindingName);
6088   }
6089   info.Resolve(genericSymbol);
6090   return false;
6091 }
6092 
6093 // DEC STRUCTUREs are handled thus to allow for nested definitions.
6094 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
6095   const auto &structureStatement{
6096       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
6097   auto saveDerivedTypeInfo{derivedTypeInfo_};
6098   derivedTypeInfo_ = {};
6099   derivedTypeInfo_.isStructure = true;
6100   derivedTypeInfo_.sequence = true;
6101   Scope *previousStructure{nullptr};
6102   if (saveDerivedTypeInfo.isStructure) {
6103     previousStructure = &currScope();
6104     PopScope();
6105   }
6106   const parser::StructureStmt &structStmt{structureStatement.statement};
6107   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
6108   if (!name) {
6109     // Construct a distinct generated name for an anonymous structure
6110     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
6111     mutableName.emplace(
6112         parser::Name{context().GetTempName(currScope()), nullptr});
6113   }
6114   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
6115   symbol.ReplaceName(name->source);
6116   symbol.get<DerivedTypeDetails>().set_sequence(true);
6117   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
6118   derivedTypeInfo_.type = &symbol;
6119   PushScope(Scope::Kind::DerivedType, &symbol);
6120   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
6121   Walk(fields);
6122   PopScope();
6123   // Complete the definition
6124   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
6125   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
6126   derivedTypeSpec.CookParameters(GetFoldingContext());
6127   derivedTypeSpec.EvaluateParameters(context());
6128   DeclTypeSpec &type{currScope().MakeDerivedType(
6129       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
6130   type.derivedTypeSpec().Instantiate(currScope());
6131   // Restore previous structure definition context, if any
6132   derivedTypeInfo_ = saveDerivedTypeInfo;
6133   if (previousStructure) {
6134     PushScope(*previousStructure);
6135   }
6136   // Handle any entity declarations on the STRUCTURE statement
6137   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
6138   if (!decls.empty()) {
6139     BeginDecl();
6140     SetDeclTypeSpec(type);
6141     Walk(decls);
6142     EndDecl();
6143   }
6144   return false;
6145 }
6146 
6147 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
6148   Say("support for UNION"_todo_en_US); // TODO
6149   return true;
6150 }
6151 
6152 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
6153   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
6154           x.u)) {
6155     BeginDecl();
6156   }
6157   return true;
6158 }
6159 
6160 void DeclarationVisitor::Post(const parser::StructureField &x) {
6161   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
6162           x.u)) {
6163     EndDecl();
6164   }
6165 }
6166 
6167 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
6168   BeginDeclTypeSpec();
6169   return true;
6170 }
6171 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
6172   EndDeclTypeSpec();
6173 }
6174 
6175 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
6176   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
6177   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
6178   if (!type) {
6179     return false;
6180   }
6181   const DerivedTypeSpec *spec{type->AsDerived()};
6182   const Scope *typeScope{spec ? spec->scope() : nullptr};
6183   if (!typeScope) {
6184     return false;
6185   }
6186 
6187   // N.B C7102 is implicitly enforced by having inaccessible types not
6188   // being found in resolution.
6189   // More constraints are enforced in expression.cpp so that they
6190   // can apply to structure constructors that have been converted
6191   // from misparsed function references.
6192   for (const auto &component :
6193       std::get<std::list<parser::ComponentSpec>>(x.t)) {
6194     // Visit the component spec expression, but not the keyword, since
6195     // we need to resolve its symbol in the scope of the derived type.
6196     Walk(std::get<parser::ComponentDataSource>(component.t));
6197     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
6198       FindInTypeOrParents(*typeScope, kw->v);
6199     }
6200   }
6201   return false;
6202 }
6203 
6204 bool DeclarationVisitor::Pre(const parser::BasedPointer &) {
6205   BeginArraySpec();
6206   return true;
6207 }
6208 
6209 void DeclarationVisitor::Post(const parser::BasedPointer &bp) {
6210   const parser::ObjectName &pointerName{std::get<0>(bp.t)};
6211   auto *pointer{FindSymbol(pointerName)};
6212   if (!pointer) {
6213     pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
6214   } else if (!ConvertToObjectEntity(*pointer)) {
6215     SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
6216   } else if (IsNamedConstant(*pointer)) {
6217     SayWithDecl(pointerName, *pointer,
6218         "'%s' is a named constant and may not be a Cray pointer"_err_en_US);
6219   } else if (pointer->Rank() > 0) {
6220     SayWithDecl(
6221         pointerName, *pointer, "Cray pointer '%s' must be a scalar"_err_en_US);
6222   } else if (pointer->test(Symbol::Flag::CrayPointee)) {
6223     Say(pointerName,
6224         "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
6225   }
6226   pointer->set(Symbol::Flag::CrayPointer);
6227   const DeclTypeSpec &pointerType{MakeNumericType(
6228       TypeCategory::Integer, context().defaultKinds().subscriptIntegerKind())};
6229   const auto *type{pointer->GetType()};
6230   if (!type) {
6231     pointer->SetType(pointerType);
6232   } else if (*type != pointerType) {
6233     Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
6234         pointerName.source, pointerType.AsFortran());
6235   }
6236   const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
6237   DeclareObjectEntity(pointeeName);
6238   if (Symbol * pointee{pointeeName.symbol}) {
6239     if (!ConvertToObjectEntity(*pointee)) {
6240       return;
6241     }
6242     if (IsNamedConstant(*pointee)) {
6243       Say(pointeeName,
6244           "'%s' is a named constant and may not be a Cray pointee"_err_en_US);
6245       return;
6246     }
6247     if (pointee->test(Symbol::Flag::CrayPointer)) {
6248       Say(pointeeName,
6249           "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
6250     } else if (pointee->test(Symbol::Flag::CrayPointee)) {
6251       Say(pointeeName, "'%s' was already declared as a Cray pointee"_err_en_US);
6252     } else {
6253       pointee->set(Symbol::Flag::CrayPointee);
6254     }
6255     if (const auto *pointeeType{pointee->GetType()}) {
6256       if (const auto *derived{pointeeType->AsDerived()}) {
6257         if (!IsSequenceOrBindCType(derived)) {
6258           context().Warn(common::LanguageFeature::NonSequenceCrayPointee,
6259               pointeeName.source,
6260               "Type of Cray pointee '%s' is a derived type that is neither SEQUENCE nor BIND(C)"_warn_en_US,
6261               pointeeName.source);
6262         }
6263       }
6264     }
6265     currScope().add_crayPointer(pointeeName.source, *pointer);
6266   }
6267 }
6268 
6269 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
6270   if (!CheckNotInBlock("NAMELIST")) { // C1107
6271     return false;
6272   }
6273   const auto &groupName{std::get<parser::Name>(x.t)};
6274   auto *groupSymbol{FindInScope(groupName)};
6275   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
6276     groupSymbol = &MakeSymbol(groupName, NamelistDetails{});
6277     groupSymbol->ReplaceName(groupName.source);
6278   }
6279   // Name resolution of group items is deferred to FinishNamelists()
6280   // so that host association is handled correctly.
6281   GetDeferredDeclarationState(true)->namelistGroups.emplace_back(&x);
6282   return false;
6283 }
6284 
6285 void DeclarationVisitor::FinishNamelists() {
6286   if (auto *deferred{GetDeferredDeclarationState()}) {
6287     for (const parser::NamelistStmt::Group *group : deferred->namelistGroups) {
6288       if (auto *groupSymbol{FindInScope(std::get<parser::Name>(group->t))}) {
6289         if (auto *details{groupSymbol->detailsIf<NamelistDetails>()}) {
6290           for (const auto &name : std::get<std::list<parser::Name>>(group->t)) {
6291             auto *symbol{FindSymbol(name)};
6292             if (!symbol) {
6293               symbol = &MakeSymbol(name, ObjectEntityDetails{});
6294               ApplyImplicitRules(*symbol);
6295             } else if (!ConvertToObjectEntity(symbol->GetUltimate())) {
6296               SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
6297               context().SetError(*groupSymbol);
6298             }
6299             symbol->GetUltimate().set(Symbol::Flag::InNamelist);
6300             details->add_object(*symbol);
6301           }
6302         }
6303       }
6304     }
6305     deferred->namelistGroups.clear();
6306   }
6307 }
6308 
6309 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
6310   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
6311     auto *symbol{FindSymbol(*name)};
6312     if (!symbol) {
6313       Say(*name, "Namelist group '%s' not found"_err_en_US);
6314     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
6315       SayWithDecl(
6316           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
6317     }
6318   }
6319   return true;
6320 }
6321 
6322 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
6323   CheckNotInBlock("COMMON"); // C1107
6324   return true;
6325 }
6326 
6327 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
6328   BeginArraySpec();
6329   return true;
6330 }
6331 
6332 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
6333   const auto &name{std::get<parser::Name>(x.t)};
6334   DeclareObjectEntity(name);
6335   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
6336   if (!pair.second) {
6337     const SourceName &prev{*pair.first};
6338     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
6339         "Previous occurrence of '%s' in a COMMON block"_en_US);
6340   }
6341 }
6342 
6343 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
6344   // save equivalence sets to be processed after specification part
6345   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
6346     for (const std::list<parser::EquivalenceObject> &set : x.v) {
6347       specPartState_.equivalenceSets.push_back(&set);
6348     }
6349   }
6350   return false; // don't implicitly declare names yet
6351 }
6352 
6353 void DeclarationVisitor::CheckEquivalenceSets() {
6354   EquivalenceSets equivSets{context()};
6355   inEquivalenceStmt_ = true;
6356   for (const auto *set : specPartState_.equivalenceSets) {
6357     const auto &source{set->front().v.value().source};
6358     if (set->size() <= 1) { // R871
6359       Say(source, "Equivalence set must have more than one object"_err_en_US);
6360     }
6361     for (const parser::EquivalenceObject &object : *set) {
6362       const auto &designator{object.v.value()};
6363       // The designator was not resolved when it was encountered, so do it now.
6364       // AnalyzeExpr causes array sections to be changed to substrings as needed
6365       Walk(designator);
6366       if (AnalyzeExpr(context(), designator)) {
6367         equivSets.AddToSet(designator);
6368       }
6369     }
6370     equivSets.FinishSet(source);
6371   }
6372   inEquivalenceStmt_ = false;
6373   for (auto &set : equivSets.sets()) {
6374     if (!set.empty()) {
6375       currScope().add_equivalenceSet(std::move(set));
6376     }
6377   }
6378   specPartState_.equivalenceSets.clear();
6379 }
6380 
6381 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
6382   if (x.v.empty()) {
6383     specPartState_.saveInfo.saveAll = currStmtSource();
6384     currScope().set_hasSAVE();
6385   } else {
6386     for (const parser::SavedEntity &y : x.v) {
6387       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
6388       const auto &name{std::get<parser::Name>(y.t)};
6389       if (kind == parser::SavedEntity::Kind::Common) {
6390         MakeCommonBlockSymbol(name);
6391         AddSaveName(specPartState_.saveInfo.commons, name.source);
6392       } else {
6393         HandleAttributeStmt(Attr::SAVE, name);
6394       }
6395     }
6396   }
6397   return false;
6398 }
6399 
6400 void DeclarationVisitor::CheckSaveStmts() {
6401   for (const SourceName &name : specPartState_.saveInfo.entities) {
6402     auto *symbol{FindInScope(name)};
6403     if (!symbol) {
6404       // error was reported
6405     } else if (specPartState_.saveInfo.saveAll) {
6406       // C889 - note that pgi, ifort, xlf do not enforce this constraint
6407       if (context().ShouldWarn(common::LanguageFeature::RedundantAttribute)) {
6408         Say2(name,
6409             "Explicit SAVE of '%s' is redundant due to global SAVE statement"_warn_en_US,
6410             *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US)
6411             .set_languageFeature(common::LanguageFeature::RedundantAttribute);
6412       }
6413     } else if (!IsSaved(*symbol)) {
6414       SetExplicitAttr(*symbol, Attr::SAVE);
6415     }
6416   }
6417   for (const SourceName &name : specPartState_.saveInfo.commons) {
6418     if (auto *symbol{currScope().FindCommonBlock(name)}) {
6419       auto &objects{symbol->get<CommonBlockDetails>().objects()};
6420       if (objects.empty()) {
6421         if (currScope().kind() != Scope::Kind::BlockConstruct) {
6422           Say(name,
6423               "'%s' appears as a COMMON block in a SAVE statement but not in"
6424               " a COMMON statement"_err_en_US);
6425         } else { // C1108
6426           Say(name,
6427               "SAVE statement in BLOCK construct may not contain a"
6428               " common block name '%s'"_err_en_US);
6429         }
6430       } else {
6431         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
6432           if (!IsSaved(*object)) {
6433             SetImplicitAttr(*object, Attr::SAVE);
6434           }
6435         }
6436       }
6437     }
6438   }
6439   specPartState_.saveInfo = {};
6440 }
6441 
6442 // Record SAVEd names in specPartState_.saveInfo.entities.
6443 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
6444   if (attrs.test(Attr::SAVE)) {
6445     AddSaveName(specPartState_.saveInfo.entities, name);
6446   }
6447   return attrs;
6448 }
6449 
6450 // Record a name in a set of those to be saved.
6451 void DeclarationVisitor::AddSaveName(
6452     std::set<SourceName> &set, const SourceName &name) {
6453   auto pair{set.insert(name)};
6454   if (!pair.second &&
6455       context().ShouldWarn(common::LanguageFeature::RedundantAttribute)) {
6456     Say2(name, "SAVE attribute was already specified on '%s'"_warn_en_US,
6457         *pair.first, "Previous specification of SAVE attribute"_en_US)
6458         .set_languageFeature(common::LanguageFeature::RedundantAttribute);
6459   }
6460 }
6461 
6462 // Check types of common block objects, now that they are known.
6463 void DeclarationVisitor::CheckCommonBlocks() {
6464   // check for empty common blocks
6465   for (const auto &pair : currScope().commonBlocks()) {
6466     const auto &symbol{*pair.second};
6467     if (symbol.get<CommonBlockDetails>().objects().empty() &&
6468         symbol.attrs().test(Attr::BIND_C)) {
6469       Say(symbol.name(),
6470           "'%s' appears as a COMMON block in a BIND statement but not in"
6471           " a COMMON statement"_err_en_US);
6472     }
6473   }
6474   // check objects in common blocks
6475   for (const auto &name : specPartState_.commonBlockObjects) {
6476     const auto *symbol{currScope().FindSymbol(name)};
6477     if (!symbol) {
6478       continue;
6479     }
6480     const auto &attrs{symbol->attrs()};
6481     if (attrs.test(Attr::ALLOCATABLE)) {
6482       Say(name,
6483           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
6484     } else if (attrs.test(Attr::BIND_C)) {
6485       Say(name,
6486           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
6487     } else if (IsNamedConstant(*symbol)) {
6488       Say(name,
6489           "A named constant '%s' may not appear in a COMMON block"_err_en_US);
6490     } else if (IsDummy(*symbol)) {
6491       Say(name,
6492           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
6493     } else if (symbol->IsFuncResult()) {
6494       Say(name,
6495           "Function result '%s' may not appear in a COMMON block"_err_en_US);
6496     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
6497       if (type->category() == DeclTypeSpec::ClassStar) {
6498         Say(name,
6499             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
6500       } else if (const auto *derived{type->AsDerived()}) {
6501         if (!IsSequenceOrBindCType(derived)) {
6502           Say(name,
6503               "Derived type '%s' in COMMON block must have the BIND or"
6504               " SEQUENCE attribute"_err_en_US);
6505         }
6506         UnorderedSymbolSet typeSet;
6507         CheckCommonBlockDerivedType(name, derived->typeSymbol(), typeSet);
6508       }
6509     }
6510   }
6511   specPartState_.commonBlockObjects = {};
6512 }
6513 
6514 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
6515   return Resolve(name, currScope().MakeCommonBlock(name.source));
6516 }
6517 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
6518     const std::optional<parser::Name> &name) {
6519   if (name) {
6520     return MakeCommonBlockSymbol(*name);
6521   } else {
6522     return MakeCommonBlockSymbol(parser::Name{});
6523   }
6524 }
6525 
6526 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
6527   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
6528 }
6529 
6530 // Check if this derived type can be in a COMMON block.
6531 void DeclarationVisitor::CheckCommonBlockDerivedType(const SourceName &name,
6532     const Symbol &typeSymbol, UnorderedSymbolSet &typeSet) {
6533   if (auto iter{typeSet.find(SymbolRef{typeSymbol})}; iter != typeSet.end()) {
6534     return;
6535   }
6536   typeSet.emplace(typeSymbol);
6537   if (const auto *scope{typeSymbol.scope()}) {
6538     for (const auto &pair : *scope) {
6539       const Symbol &component{*pair.second};
6540       if (component.attrs().test(Attr::ALLOCATABLE)) {
6541         Say2(name,
6542             "Derived type variable '%s' may not appear in a COMMON block"
6543             " due to ALLOCATABLE component"_err_en_US,
6544             component.name(), "Component with ALLOCATABLE attribute"_en_US);
6545         return;
6546       }
6547       const auto *details{component.detailsIf<ObjectEntityDetails>()};
6548       if (component.test(Symbol::Flag::InDataStmt) ||
6549           (details && details->init())) {
6550         Say2(name,
6551             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
6552             component.name(), "Component with default initialization"_en_US);
6553         return;
6554       }
6555       if (details) {
6556         if (const auto *type{details->type()}) {
6557           if (const auto *derived{type->AsDerived()}) {
6558             const Symbol &derivedTypeSymbol{derived->typeSymbol()};
6559             CheckCommonBlockDerivedType(name, derivedTypeSymbol, typeSet);
6560           }
6561         }
6562       }
6563     }
6564   }
6565 }
6566 
6567 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
6568     const parser::Name &name) {
6569   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
6570           name.source.ToString())}) {
6571     // Unrestricted specific intrinsic function names (e.g., "cos")
6572     // are acceptable as procedure interfaces.  The presence of the
6573     // INTRINSIC flag will cause this symbol to have a complete interface
6574     // recreated for it later on demand, but capturing its result type here
6575     // will make GetType() return a correct result without having to
6576     // probe the intrinsics table again.
6577     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
6578     SetImplicitAttr(symbol, Attr::INTRINSIC);
6579     CHECK(interface->functionResult.has_value());
6580     evaluate::DynamicType dyType{
6581         DEREF(interface->functionResult->GetTypeAndShape()).type()};
6582     CHECK(common::IsNumericTypeCategory(dyType.category()));
6583     const DeclTypeSpec &typeSpec{
6584         MakeNumericType(dyType.category(), dyType.kind())};
6585     ProcEntityDetails details;
6586     details.set_type(typeSpec);
6587     symbol.set_details(std::move(details));
6588     symbol.set(Symbol::Flag::Function);
6589     if (interface->IsElemental()) {
6590       SetExplicitAttr(symbol, Attr::ELEMENTAL);
6591     }
6592     if (interface->IsPure()) {
6593       SetExplicitAttr(symbol, Attr::PURE);
6594     }
6595     Resolve(name, symbol);
6596     return true;
6597   } else {
6598     return false;
6599   }
6600 }
6601 
6602 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
6603 bool DeclarationVisitor::PassesSharedLocalityChecks(
6604     const parser::Name &name, Symbol &symbol) {
6605   if (!IsVariableName(symbol)) {
6606     SayLocalMustBeVariable(name, symbol); // C1124
6607     return false;
6608   }
6609   if (symbol.owner() == currScope()) { // C1125 and C1126
6610     SayAlreadyDeclared(name, symbol);
6611     return false;
6612   }
6613   return true;
6614 }
6615 
6616 // Checks for locality-specs LOCAL, LOCAL_INIT, and REDUCE
6617 bool DeclarationVisitor::PassesLocalityChecks(
6618     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6619   bool isReduce{flag == Symbol::Flag::LocalityReduce};
6620   const char *specName{
6621       flag == Symbol::Flag::LocalityLocalInit ? "LOCAL_INIT" : "LOCAL"};
6622   if (IsAllocatable(symbol) && !isReduce) { // F'2023 C1130
6623     SayWithDecl(name, symbol,
6624         "ALLOCATABLE variable '%s' not allowed in a %s locality-spec"_err_en_US,
6625         specName);
6626     return false;
6627   }
6628   if (IsOptional(symbol)) { // F'2023 C1130-C1131
6629     SayWithDecl(name, symbol,
6630         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
6631     return false;
6632   }
6633   if (IsIntentIn(symbol)) { // F'2023 C1130-C1131
6634     SayWithDecl(name, symbol,
6635         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
6636     return false;
6637   }
6638   if (IsFinalizable(symbol) && !isReduce) { // F'2023 C1130
6639     SayWithDecl(name, symbol,
6640         "Finalizable variable '%s' not allowed in a %s locality-spec"_err_en_US,
6641         specName);
6642     return false;
6643   }
6644   if (evaluate::IsCoarray(symbol) && !isReduce) { // F'2023 C1130
6645     SayWithDecl(name, symbol,
6646         "Coarray '%s' not allowed in a %s locality-spec"_err_en_US, specName);
6647     return false;
6648   }
6649   if (const DeclTypeSpec * type{symbol.GetType()}) {
6650     if (type->IsPolymorphic() && IsDummy(symbol) && !IsPointer(symbol) &&
6651         !isReduce) { // F'2023 C1130
6652       SayWithDecl(name, symbol,
6653           "Nonpointer polymorphic argument '%s' not allowed in a %s locality-spec"_err_en_US,
6654           specName);
6655       return false;
6656     }
6657   }
6658   if (symbol.attrs().test(Attr::ASYNCHRONOUS) && isReduce) { // F'2023 C1131
6659     SayWithDecl(name, symbol,
6660         "ASYNCHRONOUS variable '%s' not allowed in a REDUCE locality-spec"_err_en_US);
6661     return false;
6662   }
6663   if (symbol.attrs().test(Attr::VOLATILE) && isReduce) { // F'2023 C1131
6664     SayWithDecl(name, symbol,
6665         "VOLATILE variable '%s' not allowed in a REDUCE locality-spec"_err_en_US);
6666     return false;
6667   }
6668   if (IsAssumedSizeArray(symbol)) { // F'2023 C1130-C1131
6669     SayWithDecl(name, symbol,
6670         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
6671     return false;
6672   }
6673   if (std::optional<Message> whyNot{WhyNotDefinable(
6674           name.source, currScope(), DefinabilityFlags{}, symbol)}) {
6675     SayWithReason(name, symbol,
6676         "'%s' may not appear in a locality-spec because it is not definable"_err_en_US,
6677         std::move(whyNot->set_severity(parser::Severity::Because)));
6678     return false;
6679   }
6680   return PassesSharedLocalityChecks(name, symbol);
6681 }
6682 
6683 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
6684     const parser::Name &name) {
6685   Symbol *prev{FindSymbol(name)};
6686   if (!prev) {
6687     // Declare the name as an object in the enclosing scope so that
6688     // the name can't be repurposed there later as something else.
6689     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
6690     ConvertToObjectEntity(*prev);
6691     ApplyImplicitRules(*prev);
6692   }
6693   return *prev;
6694 }
6695 
6696 void DeclarationVisitor::DeclareLocalEntity(
6697     const parser::Name &name, Symbol::Flag flag) {
6698   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
6699   if (PassesLocalityChecks(name, prev, flag)) {
6700     if (auto *symbol{&MakeHostAssocSymbol(name, prev)}) {
6701       symbol->set(flag);
6702     }
6703   }
6704 }
6705 
6706 Symbol *DeclarationVisitor::DeclareStatementEntity(
6707     const parser::DoVariable &doVar,
6708     const std::optional<parser::IntegerTypeSpec> &type) {
6709   const parser::Name &name{doVar.thing.thing};
6710   const DeclTypeSpec *declTypeSpec{nullptr};
6711   if (auto *prev{FindSymbol(name)}) {
6712     if (prev->owner() == currScope()) {
6713       SayAlreadyDeclared(name, *prev);
6714       return nullptr;
6715     }
6716     name.symbol = nullptr;
6717     // F'2023 19.4 p5 ambiguous rule about outer declarations
6718     declTypeSpec = prev->GetType();
6719   }
6720   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
6721   if (!symbol.has<ObjectEntityDetails>()) {
6722     return nullptr; // error was reported in DeclareEntity
6723   }
6724   if (type) {
6725     declTypeSpec = ProcessTypeSpec(*type);
6726   }
6727   if (declTypeSpec) {
6728     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
6729     // declaration of this implied DO loop control variable.
6730     auto restorer{
6731         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
6732     SetType(name, *declTypeSpec);
6733   } else {
6734     ApplyImplicitRules(symbol);
6735   }
6736   return Resolve(name, &symbol);
6737 }
6738 
6739 // Set the type of an entity or report an error.
6740 void DeclarationVisitor::SetType(
6741     const parser::Name &name, const DeclTypeSpec &type) {
6742   CHECK(name.symbol);
6743   auto &symbol{*name.symbol};
6744   if (charInfo_.length) { // Declaration has "*length" (R723)
6745     auto length{std::move(*charInfo_.length)};
6746     charInfo_.length.reset();
6747     if (type.category() == DeclTypeSpec::Character) {
6748       auto kind{type.characterTypeSpec().kind()};
6749       // Recurse with correct type.
6750       SetType(name,
6751           currScope().MakeCharacterType(std::move(length), std::move(kind)));
6752       return;
6753     } else { // C753
6754       Say(name,
6755           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
6756     }
6757   }
6758   if (auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
6759     if (proc->procInterface()) {
6760       Say(name,
6761           "'%s' has an explicit interface and may not also have a type"_err_en_US);
6762       context().SetError(symbol);
6763       return;
6764     }
6765   }
6766   auto *prevType{symbol.GetType()};
6767   if (!prevType) {
6768     if (symbol.test(Symbol::Flag::InDataStmt) && isImplicitNoneType()) {
6769       context().Warn(common::LanguageFeature::ForwardRefImplicitNoneData,
6770           name.source,
6771           "'%s' appeared in a DATA statement before its type was declared under IMPLICIT NONE(TYPE)"_port_en_US,
6772           name.source);
6773     }
6774     symbol.SetType(type);
6775   } else if (symbol.has<UseDetails>()) {
6776     // error recovery case, redeclaration of use-associated name
6777   } else if (HadForwardRef(symbol)) {
6778     // error recovery after use of host-associated name
6779   } else if (!symbol.test(Symbol::Flag::Implicit)) {
6780     SayWithDecl(
6781         name, symbol, "The type of '%s' has already been declared"_err_en_US);
6782     context().SetError(symbol);
6783   } else if (type != *prevType) {
6784     SayWithDecl(name, symbol,
6785         "The type of '%s' has already been implicitly declared"_err_en_US);
6786     context().SetError(symbol);
6787   } else {
6788     symbol.set(Symbol::Flag::Implicit, false);
6789   }
6790 }
6791 
6792 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
6793     const parser::Name &name) {
6794   Scope &outer{NonDerivedTypeScope()};
6795   Symbol *symbol{FindSymbol(outer, name)};
6796   Symbol *ultimate{symbol ? &symbol->GetUltimate() : nullptr};
6797   auto *generic{ultimate ? ultimate->detailsIf<GenericDetails>() : nullptr};
6798   if (generic) {
6799     if (Symbol * genDT{generic->derivedType()}) {
6800       symbol = genDT;
6801       generic = nullptr;
6802     }
6803   }
6804   if (!symbol || symbol->has<UnknownDetails>() ||
6805       (generic && &ultimate->owner() == &outer)) {
6806     if (allowForwardReferenceToDerivedType()) {
6807       if (!symbol) {
6808         symbol = &MakeSymbol(outer, name.source, Attrs{});
6809         Resolve(name, *symbol);
6810       } else if (generic) {
6811         // forward ref to type with later homonymous generic
6812         symbol = &outer.MakeSymbol(name.source, Attrs{}, UnknownDetails{});
6813         generic->set_derivedType(*symbol);
6814         name.symbol = symbol;
6815       }
6816       DerivedTypeDetails details;
6817       details.set_isForwardReferenced(true);
6818       symbol->set_details(std::move(details));
6819     } else { // C732
6820       Say(name, "Derived type '%s' not found"_err_en_US);
6821       return std::nullopt;
6822     }
6823   } else if (&DEREF(symbol).owner() != &outer &&
6824       !ultimate->has<GenericDetails>()) {
6825     // Prevent a later declaration in this scope of a host-associated
6826     // type name.
6827     outer.add_importName(name.source);
6828   }
6829   if (CheckUseError(name)) {
6830     return std::nullopt;
6831   } else if (symbol->GetUltimate().has<DerivedTypeDetails>()) {
6832     return DerivedTypeSpec{name.source, *symbol};
6833   } else {
6834     Say(name, "'%s' is not a derived type"_err_en_US);
6835     return std::nullopt;
6836   }
6837 }
6838 
6839 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
6840     const parser::Name &typeName, const parser::Name *extendsName) {
6841   if (extendsName) {
6842     if (typeName.source == extendsName->source) {
6843       Say(extendsName->source,
6844           "Derived type '%s' cannot extend itself"_err_en_US);
6845     } else if (auto dtSpec{ResolveDerivedType(*extendsName)}) {
6846       if (!dtSpec->IsForwardReferenced()) {
6847         return dtSpec;
6848       }
6849       Say(typeName.source,
6850           "Derived type '%s' cannot extend type '%s' that has not yet been defined"_err_en_US,
6851           typeName.source, extendsName->source);
6852     }
6853   }
6854   return std::nullopt;
6855 }
6856 
6857 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
6858   // The symbol is checked later by CheckExplicitInterface() and
6859   // CheckBindings().  It can be a forward reference.
6860   if (!NameIsKnownOrIntrinsic(name)) {
6861     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
6862     Resolve(name, symbol);
6863   }
6864   return name.symbol;
6865 }
6866 
6867 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
6868   if (const Symbol * symbol{name.symbol}) {
6869     const Symbol &ultimate{symbol->GetUltimate()};
6870     if (!context().HasError(*symbol) && !context().HasError(ultimate) &&
6871         !BypassGeneric(ultimate).HasExplicitInterface()) {
6872       Say(name,
6873           "'%s' must be an abstract interface or a procedure with an explicit interface"_err_en_US,
6874           symbol->name());
6875     }
6876   }
6877 }
6878 
6879 // Create a symbol for a type parameter, component, or procedure binding in
6880 // the current derived type scope. Return false on error.
6881 Symbol *DeclarationVisitor::MakeTypeSymbol(
6882     const parser::Name &name, Details &&details) {
6883   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
6884 }
6885 Symbol *DeclarationVisitor::MakeTypeSymbol(
6886     const SourceName &name, Details &&details) {
6887   Scope &derivedType{currScope()};
6888   CHECK(derivedType.IsDerivedType());
6889   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
6890     Say2(name,
6891         "Type parameter, component, or procedure binding '%s'"
6892         " already defined in this type"_err_en_US,
6893         *symbol, "Previous definition of '%s'"_en_US);
6894     return nullptr;
6895   } else {
6896     auto attrs{GetAttrs()};
6897     // Apply binding-private-stmt if present and this is a procedure binding
6898     if (derivedTypeInfo_.privateBindings &&
6899         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
6900         std::holds_alternative<ProcBindingDetails>(details)) {
6901       attrs.set(Attr::PRIVATE);
6902     }
6903     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
6904     SetCUDADataAttr(name, result, cudaDataAttr());
6905     return &result;
6906   }
6907 }
6908 
6909 // Return true if it is ok to declare this component in the current scope.
6910 // Otherwise, emit an error and return false.
6911 bool DeclarationVisitor::OkToAddComponent(
6912     const parser::Name &name, const Symbol *extends) {
6913   for (const Scope *scope{&currScope()}; scope;) {
6914     CHECK(scope->IsDerivedType());
6915     if (auto *prev{FindInScope(*scope, name.source)}) {
6916       std::optional<parser::MessageFixedText> msg;
6917       std::optional<common::UsageWarning> warning;
6918       if (context().HasError(*prev)) { // don't pile on
6919       } else if (extends) {
6920         msg = "Type cannot be extended as it has a component named"
6921               " '%s'"_err_en_US;
6922       } else if (CheckAccessibleSymbol(currScope(), *prev)) {
6923         // inaccessible component -- redeclaration is ok
6924         if (context().ShouldWarn(
6925                 common::UsageWarning::RedeclaredInaccessibleComponent)) {
6926           msg =
6927               "Component '%s' is inaccessibly declared in or as a parent of this derived type"_warn_en_US;
6928           warning = common::UsageWarning::RedeclaredInaccessibleComponent;
6929         }
6930       } else if (prev->test(Symbol::Flag::ParentComp)) {
6931         msg =
6932             "'%s' is a parent type of this type and so cannot be a component"_err_en_US;
6933       } else if (scope == &currScope()) {
6934         msg =
6935             "Component '%s' is already declared in this derived type"_err_en_US;
6936       } else {
6937         msg =
6938             "Component '%s' is already declared in a parent of this derived type"_err_en_US;
6939       }
6940       if (msg) {
6941         auto &said{Say2(name, std::move(*msg), *prev,
6942             "Previous declaration of '%s'"_en_US)};
6943         if (msg->severity() == parser::Severity::Error) {
6944           Resolve(name, *prev);
6945           return false;
6946         }
6947         if (warning) {
6948           said.set_usageWarning(*warning);
6949         }
6950       }
6951     }
6952     if (scope == &currScope() && extends) {
6953       // The parent component has not yet been added to the scope.
6954       scope = extends->scope();
6955     } else {
6956       scope = scope->GetDerivedTypeParent();
6957     }
6958   }
6959   return true;
6960 }
6961 
6962 ParamValue DeclarationVisitor::GetParamValue(
6963     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
6964   return common::visit(
6965       common::visitors{
6966           [=](const parser::ScalarIntExpr &x) { // C704
6967             return ParamValue{EvaluateIntExpr(x), attr};
6968           },
6969           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
6970           [=](const parser::TypeParamValue::Deferred &) {
6971             return ParamValue::Deferred(attr);
6972           },
6973       },
6974       x.u);
6975 }
6976 
6977 // ConstructVisitor implementation
6978 
6979 void ConstructVisitor::ResolveIndexName(
6980     const parser::ConcurrentControl &control) {
6981   const parser::Name &name{std::get<parser::Name>(control.t)};
6982   auto *prev{FindSymbol(name)};
6983   if (prev) {
6984     if (prev->owner() == currScope()) {
6985       SayAlreadyDeclared(name, *prev);
6986       return;
6987     } else if (prev->owner().kind() == Scope::Kind::Forall &&
6988         context().ShouldWarn(
6989             common::LanguageFeature::OddIndexVariableRestrictions)) {
6990       SayWithDecl(name, *prev,
6991           "Index variable '%s' should not also be an index in an enclosing FORALL or DO CONCURRENT"_port_en_US)
6992           .set_languageFeature(
6993               common::LanguageFeature::OddIndexVariableRestrictions);
6994     }
6995     name.symbol = nullptr;
6996   }
6997   auto &symbol{DeclareObjectEntity(name)};
6998   if (symbol.GetType()) {
6999     // type came from explicit type-spec
7000   } else if (!prev) {
7001     ApplyImplicitRules(symbol);
7002   } else {
7003     // Odd rules in F'2023 19.4 paras 6 & 8.
7004     Symbol &prevRoot{prev->GetUltimate()};
7005     if (const auto *type{prevRoot.GetType()}) {
7006       symbol.SetType(*type);
7007     } else {
7008       ApplyImplicitRules(symbol);
7009     }
7010     if (prevRoot.has<ObjectEntityDetails>() ||
7011         ConvertToObjectEntity(prevRoot)) {
7012       if (prevRoot.IsObjectArray() &&
7013           context().ShouldWarn(
7014               common::LanguageFeature::OddIndexVariableRestrictions)) {
7015         SayWithDecl(name, *prev,
7016             "Index variable '%s' should be scalar in the enclosing scope"_port_en_US)
7017             .set_languageFeature(
7018                 common::LanguageFeature::OddIndexVariableRestrictions);
7019       }
7020     } else if (!prevRoot.has<CommonBlockDetails>() &&
7021         context().ShouldWarn(
7022             common::LanguageFeature::OddIndexVariableRestrictions)) {
7023       SayWithDecl(name, *prev,
7024           "Index variable '%s' should be a scalar object or common block if it is present in the enclosing scope"_port_en_US)
7025           .set_languageFeature(
7026               common::LanguageFeature::OddIndexVariableRestrictions);
7027     }
7028   }
7029   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
7030 }
7031 
7032 // We need to make sure that all of the index-names get declared before the
7033 // expressions in the loop control are evaluated so that references to the
7034 // index-names in the expressions are correctly detected.
7035 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
7036   BeginDeclTypeSpec();
7037   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
7038   const auto &controls{
7039       std::get<std::list<parser::ConcurrentControl>>(header.t)};
7040   for (const auto &control : controls) {
7041     ResolveIndexName(control);
7042   }
7043   Walk(controls);
7044   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
7045   EndDeclTypeSpec();
7046   return false;
7047 }
7048 
7049 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
7050   for (auto &name : x.v) {
7051     DeclareLocalEntity(name, Symbol::Flag::LocalityLocal);
7052   }
7053   return false;
7054 }
7055 
7056 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
7057   for (auto &name : x.v) {
7058     DeclareLocalEntity(name, Symbol::Flag::LocalityLocalInit);
7059   }
7060   return false;
7061 }
7062 
7063 bool ConstructVisitor::Pre(const parser::LocalitySpec::Reduce &x) {
7064   for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
7065     DeclareLocalEntity(name, Symbol::Flag::LocalityReduce);
7066   }
7067   return false;
7068 }
7069 
7070 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
7071   for (const auto &name : x.v) {
7072     if (!FindSymbol(name)) {
7073       context().Warn(common::UsageWarning::ImplicitShared, name.source,
7074           "Variable '%s' with SHARED locality implicitly declared"_warn_en_US,
7075           name.source);
7076     }
7077     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
7078     if (PassesSharedLocalityChecks(name, prev)) {
7079       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
7080     }
7081   }
7082   return false;
7083 }
7084 
7085 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
7086   ProcessTypeSpec(x.type);
7087   Walk(x.values);
7088   return false;
7089 }
7090 
7091 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
7092 // enclosing ac-implied-do
7093 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
7094   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
7095   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
7096   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
7097   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
7098   // F'2018 has the scope of the implied DO variable covering the entire
7099   // implied DO production (19.4(5)), which seems wrong in cases where the name
7100   // of the implied DO variable appears in one of the bound expressions. Thus
7101   // this extension, which shrinks the scope of the variable to exclude the
7102   // expressions in the bounds.
7103   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
7104   Walk(bounds.lower);
7105   Walk(bounds.upper);
7106   Walk(bounds.step);
7107   EndCheckOnIndexUseInOwnBounds(restore);
7108   PushScope(Scope::Kind::ImpliedDos, nullptr);
7109   DeclareStatementEntity(bounds.name, type);
7110   Walk(values);
7111   PopScope();
7112   return false;
7113 }
7114 
7115 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
7116   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
7117   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
7118   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
7119   // See comment in Pre(AcImpliedDo) above.
7120   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
7121   Walk(bounds.lower);
7122   Walk(bounds.upper);
7123   Walk(bounds.step);
7124   EndCheckOnIndexUseInOwnBounds(restore);
7125   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
7126   if (pushScope) {
7127     PushScope(Scope::Kind::ImpliedDos, nullptr);
7128   }
7129   DeclareStatementEntity(bounds.name, type);
7130   Walk(objects);
7131   if (pushScope) {
7132     PopScope();
7133   }
7134   return false;
7135 }
7136 
7137 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
7138 // statement so that the predicate IsInitialized() will be true
7139 // during semantic analysis before the symbol's initializer is constructed.
7140 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
7141   common::visit(
7142       common::visitors{
7143           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
7144             Walk(y.thing.value());
7145             const parser::Name &first{parser::GetFirstName(y.thing.value())};
7146             if (first.symbol) {
7147               first.symbol->set(Symbol::Flag::InDataStmt);
7148             }
7149           },
7150           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
7151       },
7152       x.u);
7153   return false;
7154 }
7155 
7156 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
7157   // Subtle: DATA statements may appear in both the specification and
7158   // execution parts, but should be treated as if in the execution part
7159   // for purposes of implicit variable declaration vs. host association.
7160   // When a name first appears as an object in a DATA statement, it should
7161   // be implicitly declared locally as if it had been assigned.
7162   auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
7163   common::visit(
7164       common::visitors{
7165           [&](const Indirection<parser::Variable> &y) {
7166             auto restorer{common::ScopedSet(deferImplicitTyping_, true)};
7167             Walk(y.value());
7168             const parser::Name &first{parser::GetFirstName(y.value())};
7169             if (first.symbol) {
7170               first.symbol->set(Symbol::Flag::InDataStmt);
7171             }
7172           },
7173           [&](const parser::DataImpliedDo &y) {
7174             PushScope(Scope::Kind::ImpliedDos, nullptr);
7175             Walk(y);
7176             PopScope();
7177           },
7178       },
7179       x.u);
7180   return false;
7181 }
7182 
7183 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
7184   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
7185   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
7186   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
7187     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
7188       if (const Symbol * symbol{FindSymbol(*name)};
7189           symbol && symbol->GetUltimate().has<DerivedTypeDetails>()) {
7190         mutableData.u = elem->ConvertToStructureConstructor(
7191             DerivedTypeSpec{name->source, *symbol});
7192       }
7193     }
7194   }
7195   return true;
7196 }
7197 
7198 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
7199   if (x.IsDoConcurrent()) {
7200     // The new scope has Kind::Forall for index variable name conflict
7201     // detection with nested FORALL/DO CONCURRENT constructs in
7202     // ResolveIndexName().
7203     PushScope(Scope::Kind::Forall, nullptr);
7204   }
7205   return true;
7206 }
7207 void ConstructVisitor::Post(const parser::DoConstruct &x) {
7208   if (x.IsDoConcurrent()) {
7209     PopScope();
7210   }
7211 }
7212 
7213 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
7214   PushScope(Scope::Kind::Forall, nullptr);
7215   return true;
7216 }
7217 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
7218 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
7219   PushScope(Scope::Kind::Forall, nullptr);
7220   return true;
7221 }
7222 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
7223 
7224 bool ConstructVisitor::Pre(const parser::BlockConstruct &x) {
7225   const auto &[blockStmt, specPart, execPart, endBlockStmt] = x.t;
7226   Walk(blockStmt);
7227   CheckDef(blockStmt.statement.v);
7228   PushScope(Scope::Kind::BlockConstruct, nullptr);
7229   Walk(specPart);
7230   HandleImpliedAsynchronousInScope(execPart);
7231   Walk(execPart);
7232   Walk(endBlockStmt);
7233   PopScope();
7234   CheckRef(endBlockStmt.statement.v);
7235   return false;
7236 }
7237 
7238 void ConstructVisitor::Post(const parser::Selector &x) {
7239   GetCurrentAssociation().selector = ResolveSelector(x);
7240 }
7241 
7242 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
7243   CheckDef(x.t);
7244   PushScope(Scope::Kind::OtherConstruct, nullptr);
7245   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
7246   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
7247     SetCurrentAssociation(nthLastAssoc);
7248     if (auto *symbol{MakeAssocEntity()}) {
7249       const MaybeExpr &expr{GetCurrentAssociation().selector.expr};
7250       if (ExtractCoarrayRef(expr)) { // C1103
7251         Say("Selector must not be a coindexed object"_err_en_US);
7252       }
7253       if (evaluate::IsAssumedRank(expr)) {
7254         Say("Selector must not be assumed-rank"_err_en_US);
7255       }
7256       SetTypeFromAssociation(*symbol);
7257       SetAttrsFromAssociation(*symbol);
7258     }
7259   }
7260   PopAssociation(assocCount);
7261 }
7262 
7263 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
7264   PopScope();
7265   CheckRef(x.v);
7266 }
7267 
7268 bool ConstructVisitor::Pre(const parser::Association &x) {
7269   PushAssociation();
7270   const auto &name{std::get<parser::Name>(x.t)};
7271   GetCurrentAssociation().name = &name;
7272   return true;
7273 }
7274 
7275 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
7276   CheckDef(x.t);
7277   PushScope(Scope::Kind::OtherConstruct, nullptr);
7278   PushAssociation();
7279   return true;
7280 }
7281 
7282 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
7283   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
7284   const auto &name{std::get<parser::Name>(decl.t)};
7285   if (auto *symbol{FindInScope(name)}) {
7286     const auto &selector{std::get<parser::Selector>(x.t)};
7287     if (auto sel{ResolveSelector(selector)}) {
7288       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
7289       if (!whole || whole->Corank() == 0) {
7290         Say(sel.source, // C1116
7291             "Selector in coarray association must name a coarray"_err_en_US);
7292       } else if (auto dynType{sel.expr->GetType()}) {
7293         if (!symbol->GetType()) {
7294           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
7295         }
7296       }
7297     }
7298   }
7299 }
7300 
7301 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
7302   PopAssociation();
7303   PopScope();
7304   CheckRef(x.t);
7305 }
7306 
7307 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
7308   PushAssociation();
7309   return true;
7310 }
7311 
7312 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
7313   PopAssociation();
7314 }
7315 
7316 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
7317   auto &association{GetCurrentAssociation()};
7318   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
7319     // This isn't a name in the current scope, it is in each TypeGuardStmt
7320     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
7321     association.name = &*name;
7322     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
7323       Say("Selector must not be a coindexed object"_err_en_US);
7324     }
7325     if (association.selector.expr) {
7326       auto exprType{association.selector.expr->GetType()};
7327       if (exprType && !exprType->IsPolymorphic()) { // C1159
7328         Say(association.selector.source,
7329             "Selector '%s' in SELECT TYPE statement must be "
7330             "polymorphic"_err_en_US);
7331       }
7332     }
7333   } else {
7334     if (const Symbol *
7335         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
7336       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
7337       if (!IsVariableName(*whole)) {
7338         Say(association.selector.source, // C901
7339             "Selector is not a variable"_err_en_US);
7340         association = {};
7341       }
7342       if (const DeclTypeSpec * type{whole->GetType()}) {
7343         if (!type->IsPolymorphic()) { // C1159
7344           Say(association.selector.source,
7345               "Selector '%s' in SELECT TYPE statement must be "
7346               "polymorphic"_err_en_US);
7347         }
7348       }
7349     } else {
7350       Say(association.selector.source, // C1157
7351           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
7352       association = {};
7353     }
7354   }
7355 }
7356 
7357 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
7358   auto &association{GetCurrentAssociation()};
7359   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
7360     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
7361     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
7362     association.name = &*name;
7363   }
7364 }
7365 
7366 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
7367   PushScope(Scope::Kind::OtherConstruct, nullptr);
7368   return true;
7369 }
7370 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
7371   PopScope();
7372 }
7373 
7374 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
7375   PushScope(Scope::Kind::OtherConstruct, nullptr);
7376   return true;
7377 }
7378 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
7379   PopScope();
7380 }
7381 
7382 bool ConstructVisitor::Pre(const parser::TypeGuardStmt::Guard &x) {
7383   if (std::holds_alternative<parser::DerivedTypeSpec>(x.u)) {
7384     // CLASS IS (t)
7385     SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
7386   }
7387   return true;
7388 }
7389 
7390 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
7391   if (auto *symbol{MakeAssocEntity()}) {
7392     if (std::holds_alternative<parser::Default>(x.u)) {
7393       SetTypeFromAssociation(*symbol);
7394     } else if (const auto *type{GetDeclTypeSpec()}) {
7395       symbol->SetType(*type);
7396     }
7397     SetAttrsFromAssociation(*symbol);
7398   }
7399 }
7400 
7401 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
7402   if (auto *symbol{MakeAssocEntity()}) {
7403     SetTypeFromAssociation(*symbol);
7404     auto &details{symbol->get<AssocEntityDetails>()};
7405     // Don't call SetAttrsFromAssociation() for SELECT RANK.
7406     Attrs selectorAttrs{
7407         evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
7408     Attrs attrsToKeep{Attr::ASYNCHRONOUS, Attr::TARGET, Attr::VOLATILE};
7409     if (const auto *rankValue{
7410             std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
7411       // RANK(n)
7412       if (auto expr{EvaluateIntExpr(*rankValue)}) {
7413         if (auto val{evaluate::ToInt64(*expr)}) {
7414           details.set_rank(*val);
7415           attrsToKeep |= Attrs{Attr::ALLOCATABLE, Attr::POINTER};
7416         } else {
7417           Say("RANK() expression must be constant"_err_en_US);
7418         }
7419       }
7420     } else if (std::holds_alternative<parser::Star>(x.u)) {
7421       // RANK(*): assumed-size
7422       details.set_IsAssumedSize();
7423     } else {
7424       CHECK(std::holds_alternative<parser::Default>(x.u));
7425       // RANK DEFAULT: assumed-rank
7426       details.set_IsAssumedRank();
7427       attrsToKeep |= Attrs{Attr::ALLOCATABLE, Attr::POINTER};
7428     }
7429     symbol->attrs() |= selectorAttrs & attrsToKeep;
7430   }
7431 }
7432 
7433 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
7434   PushAssociation();
7435   return true;
7436 }
7437 
7438 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
7439   PopAssociation();
7440 }
7441 
7442 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
7443   if (x && !x->symbol) {
7444     // Construct names are not scoped by BLOCK in the standard, but many,
7445     // but not all, compilers do treat them as if they were so scoped.
7446     if (Symbol * inner{FindInScope(currScope(), *x)}) {
7447       SayAlreadyDeclared(*x, *inner);
7448     } else {
7449       if (context().ShouldWarn(common::LanguageFeature::BenignNameClash)) {
7450         if (Symbol *
7451             other{FindInScopeOrBlockConstructs(InclusiveScope(), x->source)}) {
7452           SayWithDecl(*x, *other,
7453               "The construct name '%s' should be distinct at the subprogram level"_port_en_US)
7454               .set_languageFeature(common::LanguageFeature::BenignNameClash);
7455         }
7456       }
7457       MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
7458     }
7459   }
7460   return true;
7461 }
7462 
7463 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
7464   if (x) {
7465     // Just add an occurrence of this name; checking is done in ValidateLabels
7466     FindSymbol(*x);
7467   }
7468 }
7469 
7470 // Make a symbol for the associating entity of the current association.
7471 Symbol *ConstructVisitor::MakeAssocEntity() {
7472   Symbol *symbol{nullptr};
7473   auto &association{GetCurrentAssociation()};
7474   if (association.name) {
7475     symbol = &MakeSymbol(*association.name, UnknownDetails{});
7476     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
7477       Say(*association.name, // C1102
7478           "The associate name '%s' is already used in this associate statement"_err_en_US);
7479       return nullptr;
7480     }
7481   } else if (const Symbol *
7482       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
7483     symbol = &MakeSymbol(whole->name());
7484   } else {
7485     return nullptr;
7486   }
7487   if (auto &expr{association.selector.expr}) {
7488     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
7489   } else {
7490     symbol->set_details(AssocEntityDetails{});
7491   }
7492   return symbol;
7493 }
7494 
7495 // Set the type of symbol based on the current association selector.
7496 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
7497   auto &details{symbol.get<AssocEntityDetails>()};
7498   const MaybeExpr *pexpr{&details.expr()};
7499   if (!*pexpr) {
7500     pexpr = &GetCurrentAssociation().selector.expr;
7501   }
7502   if (*pexpr) {
7503     const SomeExpr &expr{**pexpr};
7504     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
7505       if (const auto *charExpr{
7506               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
7507                   expr)}) {
7508         symbol.SetType(ToDeclTypeSpec(std::move(*type),
7509             FoldExpr(common::visit(
7510                 [](const auto &kindChar) { return kindChar.LEN(); },
7511                 charExpr->u))));
7512       } else {
7513         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
7514       }
7515     } else {
7516       // BOZ literals, procedure designators, &c. are not acceptable
7517       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
7518     }
7519   }
7520 }
7521 
7522 // If current selector is a variable, set some of its attributes on symbol.
7523 // For ASSOCIATE, CHANGE TEAM, and SELECT TYPE only; not SELECT RANK.
7524 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
7525   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
7526   symbol.attrs() |=
7527       attrs & Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE};
7528   if (attrs.test(Attr::POINTER)) {
7529     SetImplicitAttr(symbol, Attr::TARGET);
7530   }
7531 }
7532 
7533 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
7534     const parser::Selector &x) {
7535   return common::visit(common::visitors{
7536                            [&](const parser::Expr &expr) {
7537                              return Selector{expr.source, EvaluateExpr(x)};
7538                            },
7539                            [&](const parser::Variable &var) {
7540                              return Selector{var.GetSource(), EvaluateExpr(x)};
7541                            },
7542                        },
7543       x.u);
7544 }
7545 
7546 // Set the current association to the nth to the last association on the
7547 // association stack.  The top of the stack is at n = 1.  This allows access
7548 // to the interior of a list of associations at the top of the stack.
7549 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
7550   CHECK(n > 0 && n <= associationStack_.size());
7551   currentAssociation_ = &associationStack_[associationStack_.size() - n];
7552 }
7553 
7554 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
7555   CHECK(currentAssociation_);
7556   return *currentAssociation_;
7557 }
7558 
7559 void ConstructVisitor::PushAssociation() {
7560   associationStack_.emplace_back(Association{});
7561   currentAssociation_ = &associationStack_.back();
7562 }
7563 
7564 void ConstructVisitor::PopAssociation(std::size_t count) {
7565   CHECK(count > 0 && count <= associationStack_.size());
7566   associationStack_.resize(associationStack_.size() - count);
7567   currentAssociation_ =
7568       associationStack_.empty() ? nullptr : &associationStack_.back();
7569 }
7570 
7571 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
7572     evaluate::DynamicType &&type) {
7573   switch (type.category()) {
7574     SWITCH_COVERS_ALL_CASES
7575   case common::TypeCategory::Integer:
7576   case common::TypeCategory::Real:
7577   case common::TypeCategory::Complex:
7578     return context().MakeNumericType(type.category(), type.kind());
7579   case common::TypeCategory::Logical:
7580     return context().MakeLogicalType(type.kind());
7581   case common::TypeCategory::Derived:
7582     if (type.IsAssumedType()) {
7583       return currScope().MakeTypeStarType();
7584     } else if (type.IsUnlimitedPolymorphic()) {
7585       return currScope().MakeClassStarType();
7586     } else {
7587       return currScope().MakeDerivedType(
7588           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
7589                                : DeclTypeSpec::TypeDerived,
7590           common::Clone(type.GetDerivedTypeSpec())
7591 
7592       );
7593     }
7594   case common::TypeCategory::Character:
7595     CRASH_NO_CASE;
7596   }
7597 }
7598 
7599 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
7600     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
7601   CHECK(type.category() == common::TypeCategory::Character);
7602   if (length) {
7603     return currScope().MakeCharacterType(
7604         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
7605         KindExpr{type.kind()});
7606   } else {
7607     return currScope().MakeCharacterType(
7608         ParamValue::Deferred(common::TypeParamAttr::Len),
7609         KindExpr{type.kind()});
7610   }
7611 }
7612 
7613 class ExecutionPartSkimmerBase {
7614 public:
7615   template <typename A> bool Pre(const A &) { return true; }
7616   template <typename A> void Post(const A &) {}
7617 
7618   bool InNestedBlockConstruct() const { return blockDepth_ > 0; }
7619 
7620   bool Pre(const parser::AssociateConstruct &) {
7621     PushScope();
7622     return true;
7623   }
7624   void Post(const parser::AssociateConstruct &) { PopScope(); }
7625   bool Pre(const parser::Association &x) {
7626     Hide(std::get<parser::Name>(x.t));
7627     return true;
7628   }
7629   bool Pre(const parser::BlockConstruct &) {
7630     PushScope();
7631     ++blockDepth_;
7632     return true;
7633   }
7634   void Post(const parser::BlockConstruct &) {
7635     --blockDepth_;
7636     PopScope();
7637   }
7638   bool Pre(const parser::EntityDecl &x) {
7639     Hide(std::get<parser::ObjectName>(x.t));
7640     return true;
7641   }
7642   void Post(const parser::ImportStmt &x) {
7643     if (x.kind == common::ImportKind::None ||
7644         x.kind == common::ImportKind::Only) {
7645       if (!nestedScopes_.front().importOnly.has_value()) {
7646         nestedScopes_.front().importOnly.emplace();
7647       }
7648       for (const auto &name : x.names) {
7649         nestedScopes_.front().importOnly->emplace(name.source);
7650       }
7651     } else {
7652       // no special handling needed for explicit names or IMPORT, ALL
7653     }
7654   }
7655   void Post(const parser::UseStmt &x) {
7656     if (const auto *onlyList{std::get_if<std::list<parser::Only>>(&x.u)}) {
7657       for (const auto &only : *onlyList) {
7658         if (const auto *name{std::get_if<parser::Name>(&only.u)}) {
7659           Hide(*name);
7660         } else if (const auto *rename{std::get_if<parser::Rename>(&only.u)}) {
7661           if (const auto *names{
7662                   std::get_if<parser::Rename::Names>(&rename->u)}) {
7663             Hide(std::get<0>(names->t));
7664           }
7665         }
7666       }
7667     } else {
7668       // USE may or may not shadow symbols in host scopes
7669       nestedScopes_.front().hasUseWithoutOnly = true;
7670     }
7671   }
7672   bool Pre(const parser::DerivedTypeStmt &x) {
7673     Hide(std::get<parser::Name>(x.t));
7674     PushScope();
7675     return true;
7676   }
7677   void Post(const parser::DerivedTypeDef &) { PopScope(); }
7678   bool Pre(const parser::SelectTypeConstruct &) {
7679     PushScope();
7680     return true;
7681   }
7682   void Post(const parser::SelectTypeConstruct &) { PopScope(); }
7683   bool Pre(const parser::SelectTypeStmt &x) {
7684     if (const auto &maybeName{std::get<1>(x.t)}) {
7685       Hide(*maybeName);
7686     }
7687     return true;
7688   }
7689   bool Pre(const parser::SelectRankConstruct &) {
7690     PushScope();
7691     return true;
7692   }
7693   void Post(const parser::SelectRankConstruct &) { PopScope(); }
7694   bool Pre(const parser::SelectRankStmt &x) {
7695     if (const auto &maybeName{std::get<1>(x.t)}) {
7696       Hide(*maybeName);
7697     }
7698     return true;
7699   }
7700 
7701 protected:
7702   bool IsHidden(SourceName name) {
7703     for (const auto &scope : nestedScopes_) {
7704       if (scope.locals.find(name) != scope.locals.end()) {
7705         return true; // shadowed by nested declaration
7706       }
7707       if (scope.hasUseWithoutOnly) {
7708         break;
7709       }
7710       if (scope.importOnly &&
7711           scope.importOnly->find(name) == scope.importOnly->end()) {
7712         return true; // not imported
7713       }
7714     }
7715     return false;
7716   }
7717 
7718   void EndWalk() { CHECK(nestedScopes_.empty()); }
7719 
7720 private:
7721   void PushScope() { nestedScopes_.emplace_front(); }
7722   void PopScope() { nestedScopes_.pop_front(); }
7723   void Hide(const parser::Name &name) {
7724     nestedScopes_.front().locals.emplace(name.source);
7725   }
7726 
7727   int blockDepth_{0};
7728   struct NestedScopeInfo {
7729     bool hasUseWithoutOnly{false};
7730     std::set<SourceName> locals;
7731     std::optional<std::set<SourceName>> importOnly;
7732   };
7733   std::list<NestedScopeInfo> nestedScopes_;
7734 };
7735 
7736 class ExecutionPartAsyncIOSkimmer : public ExecutionPartSkimmerBase {
7737 public:
7738   explicit ExecutionPartAsyncIOSkimmer(SemanticsContext &context)
7739       : context_{context} {}
7740 
7741   void Walk(const parser::Block &block) {
7742     parser::Walk(block, *this);
7743     EndWalk();
7744   }
7745 
7746   const std::set<SourceName> asyncIONames() const { return asyncIONames_; }
7747 
7748   using ExecutionPartSkimmerBase::Post;
7749   using ExecutionPartSkimmerBase::Pre;
7750 
7751   bool Pre(const parser::IoControlSpec::Asynchronous &async) {
7752     if (auto folded{evaluate::Fold(
7753             context_.foldingContext(), AnalyzeExpr(context_, async.v))}) {
7754       if (auto str{
7755               evaluate::GetScalarConstantValue<evaluate::Ascii>(*folded)}) {
7756         for (char ch : *str) {
7757           if (ch != ' ') {
7758             inAsyncIO_ = ch == 'y' || ch == 'Y';
7759             break;
7760           }
7761         }
7762       }
7763     }
7764     return true;
7765   }
7766   void Post(const parser::ReadStmt &) { inAsyncIO_ = false; }
7767   void Post(const parser::WriteStmt &) { inAsyncIO_ = false; }
7768   void Post(const parser::IoControlSpec::Size &size) {
7769     if (const auto *designator{
7770             std::get_if<common::Indirection<parser::Designator>>(
7771                 &size.v.thing.thing.u)}) {
7772       NoteAsyncIODesignator(designator->value());
7773     }
7774   }
7775   void Post(const parser::InputItem &x) {
7776     if (const auto *var{std::get_if<parser::Variable>(&x.u)}) {
7777       if (const auto *designator{
7778               std::get_if<common::Indirection<parser::Designator>>(&var->u)}) {
7779         NoteAsyncIODesignator(designator->value());
7780       }
7781     }
7782   }
7783   void Post(const parser::OutputItem &x) {
7784     if (const auto *expr{std::get_if<parser::Expr>(&x.u)}) {
7785       if (const auto *designator{
7786               std::get_if<common::Indirection<parser::Designator>>(&expr->u)}) {
7787         NoteAsyncIODesignator(designator->value());
7788       }
7789     }
7790   }
7791 
7792 private:
7793   void NoteAsyncIODesignator(const parser::Designator &designator) {
7794     if (inAsyncIO_ && !InNestedBlockConstruct()) {
7795       const parser::Name &name{parser::GetFirstName(designator)};
7796       if (!IsHidden(name.source)) {
7797         asyncIONames_.insert(name.source);
7798       }
7799     }
7800   }
7801 
7802   SemanticsContext &context_;
7803   bool inAsyncIO_{false};
7804   std::set<SourceName> asyncIONames_;
7805 };
7806 
7807 // Any data list item or SIZE= specifier of an I/O data transfer statement
7808 // with ASYNCHRONOUS="YES" implicitly has the ASYNCHRONOUS attribute in the
7809 // local scope.
7810 void ConstructVisitor::HandleImpliedAsynchronousInScope(
7811     const parser::Block &block) {
7812   ExecutionPartAsyncIOSkimmer skimmer{context()};
7813   skimmer.Walk(block);
7814   for (auto name : skimmer.asyncIONames()) {
7815     if (Symbol * symbol{currScope().FindSymbol(name)}) {
7816       if (!symbol->attrs().test(Attr::ASYNCHRONOUS)) {
7817         if (&symbol->owner() != &currScope()) {
7818           symbol = &*currScope()
7819                          .try_emplace(name, HostAssocDetails{*symbol})
7820                          .first->second;
7821         }
7822         if (symbol->has<AssocEntityDetails>()) {
7823           symbol = const_cast<Symbol *>(&GetAssociationRoot(*symbol));
7824         }
7825         SetImplicitAttr(*symbol, Attr::ASYNCHRONOUS);
7826       }
7827     }
7828   }
7829 }
7830 
7831 // ResolveNamesVisitor implementation
7832 
7833 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
7834   HandleCall(Symbol::Flag::Function, x.v);
7835   return false;
7836 }
7837 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
7838   HandleCall(Symbol::Flag::Subroutine, x.call);
7839   Walk(x.chevrons);
7840   return false;
7841 }
7842 
7843 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
7844   auto &scope{currScope()};
7845   // Check C896 and C899: where IMPORT statements are allowed
7846   switch (scope.kind()) {
7847   case Scope::Kind::Module:
7848     if (scope.IsModule()) {
7849       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
7850       return false;
7851     } else if (x.kind == common::ImportKind::None) {
7852       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
7853       return false;
7854     }
7855     break;
7856   case Scope::Kind::MainProgram:
7857     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
7858     return false;
7859   case Scope::Kind::Subprogram:
7860     if (scope.parent().IsGlobal()) {
7861       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
7862       return false;
7863     }
7864     break;
7865   case Scope::Kind::BlockData: // C1415 (in part)
7866     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
7867     return false;
7868   default:;
7869   }
7870   if (auto error{scope.SetImportKind(x.kind)}) {
7871     Say(std::move(*error));
7872   }
7873   for (auto &name : x.names) {
7874     if (Symbol * outer{FindSymbol(scope.parent(), name)}) {
7875       scope.add_importName(name.source);
7876       if (Symbol * symbol{FindInScope(name)}) {
7877         if (outer->GetUltimate() == symbol->GetUltimate()) {
7878           context().Warn(common::LanguageFeature::BenignNameClash, name.source,
7879               "The same '%s' is already present in this scope"_port_en_US,
7880               name.source);
7881         } else {
7882           Say(name,
7883               "A distinct '%s' is already present in this scope"_err_en_US)
7884               .Attach(symbol->name(), "Previous declaration of '%s'"_en_US)
7885               .Attach(outer->name(), "Declaration of '%s' in host scope"_en_US);
7886         }
7887       }
7888     } else {
7889       Say(name, "'%s' not found in host scope"_err_en_US);
7890     }
7891   }
7892   prevImportStmt_ = currStmtSource();
7893   return false;
7894 }
7895 
7896 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
7897     const parser::StructureComponent &x) {
7898   return FindComponent(ResolveDataRef(x.base), x.component);
7899 }
7900 
7901 const parser::Name *DeclarationVisitor::ResolveDesignator(
7902     const parser::Designator &x) {
7903   return common::visit(
7904       common::visitors{
7905           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
7906           [&](const parser::Substring &x) {
7907             Walk(std::get<parser::SubstringRange>(x.t).t);
7908             return ResolveDataRef(std::get<parser::DataRef>(x.t));
7909           },
7910       },
7911       x.u);
7912 }
7913 
7914 const parser::Name *DeclarationVisitor::ResolveDataRef(
7915     const parser::DataRef &x) {
7916   return common::visit(
7917       common::visitors{
7918           [=](const parser::Name &y) { return ResolveName(y); },
7919           [=](const Indirection<parser::StructureComponent> &y) {
7920             return ResolveStructureComponent(y.value());
7921           },
7922           [&](const Indirection<parser::ArrayElement> &y) {
7923             Walk(y.value().subscripts);
7924             const parser::Name *name{ResolveDataRef(y.value().base)};
7925             if (name && name->symbol) {
7926               if (!IsProcedure(*name->symbol)) {
7927                 ConvertToObjectEntity(*name->symbol);
7928               } else if (!context().HasError(*name->symbol)) {
7929                 SayWithDecl(*name, *name->symbol,
7930                     "Cannot reference function '%s' as data"_err_en_US);
7931                 context().SetError(*name->symbol);
7932               }
7933             }
7934             return name;
7935           },
7936           [&](const Indirection<parser::CoindexedNamedObject> &y) {
7937             Walk(y.value().imageSelector);
7938             return ResolveDataRef(y.value().base);
7939           },
7940       },
7941       x.u);
7942 }
7943 
7944 // If implicit types are allowed, ensure name is in the symbol table.
7945 // Otherwise, report an error if it hasn't been declared.
7946 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
7947   FindSymbol(name);
7948   if (CheckForHostAssociatedImplicit(name)) {
7949     NotePossibleBadForwardRef(name);
7950     return &name;
7951   }
7952   if (Symbol * symbol{name.symbol}) {
7953     if (CheckUseError(name)) {
7954       return nullptr; // reported an error
7955     }
7956     NotePossibleBadForwardRef(name);
7957     symbol->set(Symbol::Flag::ImplicitOrError, false);
7958     if (IsUplevelReference(*symbol)) {
7959       MakeHostAssocSymbol(name, *symbol);
7960     } else if (IsDummy(*symbol) ||
7961         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
7962       CheckEntryDummyUse(name.source, symbol);
7963       ConvertToObjectEntity(*symbol);
7964       ApplyImplicitRules(*symbol);
7965     } else if (const auto *tpd{symbol->detailsIf<TypeParamDetails>()};
7966                tpd && !tpd->attr()) {
7967       Say(name,
7968           "Type parameter '%s' was referenced before being declared"_err_en_US,
7969           name.source);
7970       context().SetError(*symbol);
7971     }
7972     if (checkIndexUseInOwnBounds_ &&
7973         *checkIndexUseInOwnBounds_ == name.source && !InModuleFile()) {
7974       context().Warn(common::LanguageFeature::ImpliedDoIndexScope, name.source,
7975           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_port_en_US,
7976           name.source);
7977     }
7978     return &name;
7979   }
7980   if (isImplicitNoneType() && !deferImplicitTyping_) {
7981     Say(name, "No explicit type declared for '%s'"_err_en_US);
7982     return nullptr;
7983   }
7984   // Create the symbol, then ensure that it is accessible
7985   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
7986     Say(name,
7987         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
7988         name.source);
7989   }
7990   MakeSymbol(InclusiveScope(), name.source, Attrs{});
7991   auto *symbol{FindSymbol(name)};
7992   if (!symbol) {
7993     Say(name,
7994         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
7995     return nullptr;
7996   }
7997   ConvertToObjectEntity(*symbol);
7998   ApplyImplicitRules(*symbol);
7999   NotePossibleBadForwardRef(name);
8000   return &name;
8001 }
8002 
8003 // A specification expression may refer to a symbol in the host procedure that
8004 // is implicitly typed. Because specification parts are processed before
8005 // execution parts, this may be the first time we see the symbol. It can't be a
8006 // local in the current scope (because it's in a specification expression) so
8007 // either it is implicitly declared in the host procedure or it is an error.
8008 // We create a symbol in the host assuming it is the former; if that proves to
8009 // be wrong we report an error later in CheckDeclarations().
8010 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
8011     const parser::Name &name) {
8012   if (!inSpecificationPart_ || inEquivalenceStmt_) {
8013     return false;
8014   }
8015   if (name.symbol) {
8016     ApplyImplicitRules(*name.symbol, true);
8017   }
8018   if (Scope * host{GetHostProcedure()}; host && !isImplicitNoneType(*host)) {
8019     Symbol *hostSymbol{nullptr};
8020     if (!name.symbol) {
8021       if (currScope().CanImport(name.source)) {
8022         hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
8023         ConvertToObjectEntity(*hostSymbol);
8024         ApplyImplicitRules(*hostSymbol);
8025         hostSymbol->set(Symbol::Flag::ImplicitOrError);
8026       }
8027     } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
8028       hostSymbol = name.symbol;
8029     }
8030     if (hostSymbol) {
8031       Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
8032       if (auto *assoc{symbol.detailsIf<HostAssocDetails>()}) {
8033         if (isImplicitNoneType()) {
8034           assoc->implicitOrExplicitTypeError = true;
8035         } else {
8036           assoc->implicitOrSpecExprError = true;
8037         }
8038         return true;
8039       }
8040     }
8041   }
8042   return false;
8043 }
8044 
8045 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
8046   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
8047   if (symbolUnit == GetProgramUnitContaining(currScope())) {
8048     return false;
8049   } else {
8050     Scope::Kind kind{symbolUnit.kind()};
8051     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
8052   }
8053 }
8054 
8055 // base is a part-ref of a derived type; find the named component in its type.
8056 // Also handles intrinsic type parameter inquiries (%kind, %len) and
8057 // COMPLEX component references (%re, %im).
8058 const parser::Name *DeclarationVisitor::FindComponent(
8059     const parser::Name *base, const parser::Name &component) {
8060   if (!base || !base->symbol) {
8061     return nullptr;
8062   }
8063   if (auto *misc{base->symbol->detailsIf<MiscDetails>()}) {
8064     if (component.source == "kind") {
8065       if (misc->kind() == MiscDetails::Kind::ComplexPartRe ||
8066           misc->kind() == MiscDetails::Kind::ComplexPartIm ||
8067           misc->kind() == MiscDetails::Kind::KindParamInquiry ||
8068           misc->kind() == MiscDetails::Kind::LenParamInquiry) {
8069         // x%{re,im,kind,len}%kind
8070         MakePlaceholder(component, MiscDetails::Kind::KindParamInquiry);
8071         return &component;
8072       }
8073     }
8074   }
8075   CheckEntryDummyUse(base->source, base->symbol);
8076   auto &symbol{base->symbol->GetUltimate()};
8077   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
8078     SayWithDecl(*base, symbol,
8079         "'%s' is not an object and may not be used as the base of a component reference or type parameter inquiry"_err_en_US);
8080     return nullptr;
8081   }
8082   auto *type{symbol.GetType()};
8083   if (!type) {
8084     return nullptr; // should have already reported error
8085   }
8086   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
8087     auto category{intrinsic->category()};
8088     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
8089     if (component.source == "kind") {
8090       miscKind = MiscDetails::Kind::KindParamInquiry;
8091     } else if (category == TypeCategory::Character) {
8092       if (component.source == "len") {
8093         miscKind = MiscDetails::Kind::LenParamInquiry;
8094       }
8095     } else if (category == TypeCategory::Complex) {
8096       if (component.source == "re") {
8097         miscKind = MiscDetails::Kind::ComplexPartRe;
8098       } else if (component.source == "im") {
8099         miscKind = MiscDetails::Kind::ComplexPartIm;
8100       }
8101     }
8102     if (miscKind != MiscDetails::Kind::None) {
8103       MakePlaceholder(component, miscKind);
8104       return &component;
8105     }
8106   } else if (DerivedTypeSpec * derived{type->AsDerived()}) {
8107     derived->Instantiate(currScope()); // in case of forward referenced type
8108     if (const Scope * scope{derived->scope()}) {
8109       if (Resolve(component, scope->FindComponent(component.source))) {
8110         if (auto msg{CheckAccessibleSymbol(currScope(), *component.symbol)}) {
8111           context().Say(component.source, *msg);
8112         }
8113         return &component;
8114       } else {
8115         SayDerivedType(component.source,
8116             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
8117       }
8118     }
8119     return nullptr;
8120   }
8121   if (symbol.test(Symbol::Flag::Implicit)) {
8122     Say(*base,
8123         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
8124   } else {
8125     SayWithDecl(
8126         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
8127   }
8128   return nullptr;
8129 }
8130 
8131 void DeclarationVisitor::Initialization(const parser::Name &name,
8132     const parser::Initialization &init, bool inComponentDecl) {
8133   // Traversal of the initializer was deferred to here so that the
8134   // symbol being declared can be available for use in the expression, e.g.:
8135   //   real, parameter :: x = tiny(x)
8136   if (!name.symbol) {
8137     return;
8138   }
8139   Symbol &ultimate{name.symbol->GetUltimate()};
8140   // TODO: check C762 - all bounds and type parameters of component
8141   // are colons or constant expressions if component is initialized
8142   common::visit(
8143       common::visitors{
8144           [&](const parser::ConstantExpr &expr) {
8145             Walk(expr);
8146             if (IsNamedConstant(ultimate) || inComponentDecl) {
8147               NonPointerInitialization(name, expr);
8148             } else {
8149               // Defer analysis so forward references to nested subprograms
8150               // can be properly resolved when they appear in structure
8151               // constructors.
8152               ultimate.set(Symbol::Flag::InDataStmt);
8153             }
8154           },
8155           [&](const parser::NullInit &null) { // => NULL()
8156             Walk(null);
8157             if (auto nullInit{EvaluateExpr(null)}) {
8158               if (!evaluate::IsNullPointer(*nullInit)) { // C813
8159                 Say(null.v.value().source,
8160                     "Pointer initializer must be intrinsic NULL()"_err_en_US);
8161               } else if (IsPointer(ultimate)) {
8162                 if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
8163                   CHECK(!object->init());
8164                   object->set_init(std::move(*nullInit));
8165                 } else if (auto *procPtr{
8166                                ultimate.detailsIf<ProcEntityDetails>()}) {
8167                   CHECK(!procPtr->init());
8168                   procPtr->set_init(nullptr);
8169                 }
8170               } else {
8171                 Say(name,
8172                     "Non-pointer component '%s' initialized with null pointer"_err_en_US);
8173               }
8174             }
8175           },
8176           [&](const parser::InitialDataTarget &target) {
8177             // Defer analysis to the end of the specification part
8178             // so that forward references and attribute checks like SAVE
8179             // work better.
8180             auto restorer{common::ScopedSet(deferImplicitTyping_, true)};
8181             Walk(target);
8182             ultimate.set(Symbol::Flag::InDataStmt);
8183           },
8184           [&](const std::list<Indirection<parser::DataStmtValue>> &values) {
8185             // Handled later in data-to-inits conversion
8186             ultimate.set(Symbol::Flag::InDataStmt);
8187             Walk(values);
8188           },
8189       },
8190       init.u);
8191 }
8192 
8193 void DeclarationVisitor::PointerInitialization(
8194     const parser::Name &name, const parser::InitialDataTarget &target) {
8195   if (name.symbol) {
8196     Symbol &ultimate{name.symbol->GetUltimate()};
8197     if (!context().HasError(ultimate)) {
8198       if (IsPointer(ultimate)) {
8199         Walk(target);
8200         if (MaybeExpr expr{EvaluateExpr(target)}) {
8201           // Validation is done in declaration checking.
8202           if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
8203             CHECK(!details->init());
8204             details->set_init(std::move(*expr));
8205             ultimate.set(Symbol::Flag::InDataStmt, false);
8206           } else if (auto *details{ultimate.detailsIf<ProcEntityDetails>()}) {
8207             // something like "REAL, EXTERNAL, POINTER :: p => t"
8208             if (evaluate::IsNullProcedurePointer(*expr)) {
8209               CHECK(!details->init());
8210               details->set_init(nullptr);
8211             } else if (const Symbol *
8212                 targetSymbol{evaluate::UnwrapWholeSymbolDataRef(*expr)}) {
8213               CHECK(!details->init());
8214               details->set_init(*targetSymbol);
8215             } else {
8216               Say(name,
8217                   "Procedure pointer '%s' must be initialized with a procedure name or NULL()"_err_en_US);
8218               context().SetError(ultimate);
8219             }
8220           }
8221         }
8222       } else {
8223         Say(name,
8224             "'%s' is not a pointer but is initialized like one"_err_en_US);
8225         context().SetError(ultimate);
8226       }
8227     }
8228   }
8229 }
8230 void DeclarationVisitor::PointerInitialization(
8231     const parser::Name &name, const parser::ProcPointerInit &target) {
8232   if (name.symbol) {
8233     Symbol &ultimate{name.symbol->GetUltimate()};
8234     if (!context().HasError(ultimate)) {
8235       if (IsProcedurePointer(ultimate)) {
8236         auto &details{ultimate.get<ProcEntityDetails>()};
8237         CHECK(!details.init());
8238         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
8239           Walk(target);
8240           if (!CheckUseError(*targetName) && targetName->symbol) {
8241             // Validation is done in declaration checking.
8242             details.set_init(*targetName->symbol);
8243           }
8244         } else { // explicit NULL
8245           details.set_init(nullptr);
8246         }
8247       } else {
8248         Say(name,
8249             "'%s' is not a procedure pointer but is initialized "
8250             "like one"_err_en_US);
8251         context().SetError(ultimate);
8252       }
8253     }
8254   }
8255 }
8256 
8257 void DeclarationVisitor::NonPointerInitialization(
8258     const parser::Name &name, const parser::ConstantExpr &expr) {
8259   if (!context().HasError(name.symbol)) {
8260     Symbol &ultimate{name.symbol->GetUltimate()};
8261     if (!context().HasError(ultimate)) {
8262       if (IsPointer(ultimate)) {
8263         Say(name,
8264             "'%s' is a pointer but is not initialized like one"_err_en_US);
8265       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
8266         if (details->init()) {
8267           SayWithDecl(name, *name.symbol,
8268               "'%s' has already been initialized"_err_en_US);
8269         } else if (IsAllocatable(ultimate)) {
8270           Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
8271         } else if (ultimate.owner().IsParameterizedDerivedType()) {
8272           // Save the expression for per-instantiation analysis.
8273           details->set_unanalyzedPDTComponentInit(&expr.thing.value());
8274         } else if (MaybeExpr folded{EvaluateNonPointerInitializer(
8275                        ultimate, expr, expr.thing.value().source)}) {
8276           details->set_init(std::move(*folded));
8277           ultimate.set(Symbol::Flag::InDataStmt, false);
8278         }
8279       } else {
8280         Say(name, "'%s' is not an object that can be initialized"_err_en_US);
8281       }
8282     }
8283   }
8284 }
8285 
8286 void ResolveNamesVisitor::HandleCall(
8287     Symbol::Flag procFlag, const parser::Call &call) {
8288   common::visit(
8289       common::visitors{
8290           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
8291           [&](const parser::ProcComponentRef &x) {
8292             Walk(x);
8293             const parser::Name &name{x.v.thing.component};
8294             if (Symbol * symbol{name.symbol}) {
8295               if (IsProcedure(*symbol)) {
8296                 SetProcFlag(name, *symbol, procFlag);
8297               }
8298             }
8299           },
8300       },
8301       std::get<parser::ProcedureDesignator>(call.t).u);
8302   const auto &arguments{std::get<std::list<parser::ActualArgSpec>>(call.t)};
8303   Walk(arguments);
8304   // Once an object has appeared in a specification function reference as
8305   // a whole scalar actual argument, it cannot be (re)dimensioned later.
8306   // The fact that it appeared to be a scalar may determine the resolution
8307   // or the result of an inquiry intrinsic function or generic procedure.
8308   if (inSpecificationPart_) {
8309     for (const auto &argSpec : arguments) {
8310       const auto &actual{std::get<parser::ActualArg>(argSpec.t)};
8311       if (const auto *expr{
8312               std::get_if<common::Indirection<parser::Expr>>(&actual.u)}) {
8313         if (const auto *designator{
8314                 std::get_if<common::Indirection<parser::Designator>>(
8315                     &expr->value().u)}) {
8316           if (const auto *dataRef{
8317                   std::get_if<parser::DataRef>(&designator->value().u)}) {
8318             if (const auto *name{std::get_if<parser::Name>(&dataRef->u)};
8319                 name && name->symbol) {
8320               const Symbol &symbol{*name->symbol};
8321               const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
8322               if (symbol.has<EntityDetails>() ||
8323                   (object && !object->IsArray())) {
8324                 NoteScalarSpecificationArgument(symbol);
8325               }
8326             }
8327           }
8328         }
8329       }
8330     }
8331   }
8332 }
8333 
8334 void ResolveNamesVisitor::HandleProcedureName(
8335     Symbol::Flag flag, const parser::Name &name) {
8336   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
8337   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
8338   if (!symbol) {
8339     if (IsIntrinsic(name.source, flag)) {
8340       symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
8341       SetImplicitAttr(*symbol, Attr::INTRINSIC);
8342     } else if (const auto ppcBuiltinScope =
8343                    currScope().context().GetPPCBuiltinsScope()) {
8344       // Check if it is a builtin from the predefined module
8345       symbol = FindSymbol(*ppcBuiltinScope, name);
8346       if (!symbol) {
8347         symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
8348       }
8349     } else {
8350       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
8351     }
8352     Resolve(name, *symbol);
8353     ConvertToProcEntity(*symbol, name.source);
8354     if (!symbol->attrs().test(Attr::INTRINSIC)) {
8355       if (CheckImplicitNoneExternal(name.source, *symbol)) {
8356         MakeExternal(*symbol);
8357         // Create a place-holder HostAssocDetails symbol to preclude later
8358         // use of this name as a local symbol; but don't actually use this new
8359         // HostAssocDetails symbol in expressions.
8360         MakeHostAssocSymbol(name, *symbol);
8361         name.symbol = symbol;
8362       }
8363     }
8364     CheckEntryDummyUse(name.source, symbol);
8365     SetProcFlag(name, *symbol, flag);
8366   } else if (CheckUseError(name)) {
8367     // error was reported
8368   } else {
8369     symbol = &symbol->GetUltimate();
8370     if (!name.symbol ||
8371         (name.symbol->has<HostAssocDetails>() && symbol->owner().IsGlobal() &&
8372             (symbol->has<ProcEntityDetails>() ||
8373                 (symbol->has<SubprogramDetails>() &&
8374                     symbol->scope() /*not ENTRY*/)))) {
8375       name.symbol = symbol;
8376     }
8377     CheckEntryDummyUse(name.source, symbol);
8378     bool convertedToProcEntity{ConvertToProcEntity(*symbol, name.source)};
8379     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
8380         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
8381       AcquireIntrinsicProcedureFlags(*symbol);
8382     }
8383     if (!SetProcFlag(name, *symbol, flag)) {
8384       return; // reported error
8385     }
8386     CheckImplicitNoneExternal(name.source, *symbol);
8387     if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
8388         symbol->has<AssocEntityDetails>()) {
8389       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
8390       // here as procedure-designators because this means the related
8391       // FunctionReference are mis-parsed structure constructors or array
8392       // references that will be fixed later when analyzing expressions.
8393     } else if (symbol->has<ObjectEntityDetails>()) {
8394       // Symbols with ObjectEntityDetails are also accepted because this can be
8395       // a mis-parsed array reference that will be fixed later. Ensure that if
8396       // this is a symbol from a host procedure, a symbol with HostAssocDetails
8397       // is created for the current scope.
8398       // Operate on non ultimate symbol so that HostAssocDetails are also
8399       // created for symbols used associated in the host procedure.
8400       ResolveName(name);
8401     } else if (symbol->test(Symbol::Flag::Implicit)) {
8402       Say(name,
8403           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
8404     } else {
8405       SayWithDecl(name, *symbol,
8406           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
8407     }
8408   }
8409 }
8410 
8411 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
8412     const SourceName &name, const Symbol &symbol) {
8413   if (symbol.has<ProcEntityDetails>() && isImplicitNoneExternal() &&
8414       !symbol.attrs().test(Attr::EXTERNAL) &&
8415       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
8416     Say(name,
8417         "'%s' is an external procedure without the EXTERNAL attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
8418     return false;
8419   }
8420   return true;
8421 }
8422 
8423 // Variant of HandleProcedureName() for use while skimming the executable
8424 // part of a subprogram to catch calls to dummy procedures that are part
8425 // of the subprogram's interface, and to mark as procedures any symbols
8426 // that might otherwise have been miscategorized as objects.
8427 void ResolveNamesVisitor::NoteExecutablePartCall(
8428     Symbol::Flag flag, SourceName name, bool hasCUDAChevrons) {
8429   // Subtlety: The symbol pointers in the parse tree are not set, because
8430   // they might end up resolving elsewhere (e.g., construct entities in
8431   // SELECT TYPE).
8432   if (Symbol * symbol{currScope().FindSymbol(name)}) {
8433     Symbol::Flag other{flag == Symbol::Flag::Subroutine
8434             ? Symbol::Flag::Function
8435             : Symbol::Flag::Subroutine};
8436     if (!symbol->test(other)) {
8437       ConvertToProcEntity(*symbol, name);
8438       if (auto *details{symbol->detailsIf<ProcEntityDetails>()}) {
8439         symbol->set(flag);
8440         if (IsDummy(*symbol)) {
8441           SetImplicitAttr(*symbol, Attr::EXTERNAL);
8442         }
8443         ApplyImplicitRules(*symbol);
8444         if (hasCUDAChevrons) {
8445           details->set_isCUDAKernel();
8446         }
8447       }
8448     }
8449   }
8450 }
8451 
8452 static bool IsLocallyImplicitGlobalSymbol(
8453     const Symbol &symbol, const parser::Name &localName) {
8454   if (symbol.owner().IsGlobal()) {
8455     const auto *subp{symbol.detailsIf<SubprogramDetails>()};
8456     const Scope *scope{
8457         subp && subp->entryScope() ? subp->entryScope() : symbol.scope()};
8458     return !(scope && scope->sourceRange().Contains(localName.source));
8459   }
8460   return false;
8461 }
8462 
8463 static bool TypesMismatchIfNonNull(
8464     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
8465   return type1 && type2 && *type1 != *type2;
8466 }
8467 
8468 // Check and set the Function or Subroutine flag on symbol; false on error.
8469 bool ResolveNamesVisitor::SetProcFlag(
8470     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
8471   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
8472     SayWithDecl(
8473         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
8474     context().SetError(symbol);
8475     return false;
8476   } else if (symbol.test(Symbol::Flag::Subroutine) &&
8477       flag == Symbol::Flag::Function) {
8478     SayWithDecl(
8479         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
8480     context().SetError(symbol);
8481     return false;
8482   } else if (flag == Symbol::Flag::Function &&
8483       IsLocallyImplicitGlobalSymbol(symbol, name) &&
8484       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
8485     SayWithDecl(name, symbol,
8486         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
8487     return false;
8488   } else if (symbol.has<ProcEntityDetails>()) {
8489     symbol.set(flag); // in case it hasn't been set yet
8490     if (flag == Symbol::Flag::Function) {
8491       ApplyImplicitRules(symbol);
8492     }
8493     if (symbol.attrs().test(Attr::INTRINSIC)) {
8494       AcquireIntrinsicProcedureFlags(symbol);
8495     }
8496   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
8497     SayWithDecl(
8498         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
8499     context().SetError(symbol);
8500   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
8501     AcquireIntrinsicProcedureFlags(symbol);
8502   }
8503   return true;
8504 }
8505 
8506 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
8507   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
8508   if (!currScope().IsModule()) { // C869
8509     Say(currStmtSource().value(),
8510         "%s statement may only appear in the specification part of a module"_err_en_US,
8511         EnumToString(accessAttr));
8512     return false;
8513   }
8514   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
8515   if (accessIds.empty()) {
8516     if (prevAccessStmt_) { // C869
8517       Say("The default accessibility of this module has already been declared"_err_en_US)
8518           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
8519     }
8520     prevAccessStmt_ = currStmtSource();
8521     auto *moduleDetails{DEREF(currScope().symbol()).detailsIf<ModuleDetails>()};
8522     DEREF(moduleDetails).set_isDefaultPrivate(accessAttr == Attr::PRIVATE);
8523   } else {
8524     for (const auto &accessId : accessIds) {
8525       GenericSpecInfo info{accessId.v.value()};
8526       auto *symbol{FindInScope(info.symbolName())};
8527       if (!symbol && !info.kind().IsName()) {
8528         symbol = &MakeSymbol(info.symbolName(), Attrs{}, GenericDetails{});
8529       }
8530       info.Resolve(&SetAccess(info.symbolName(), accessAttr, symbol));
8531     }
8532   }
8533   return false;
8534 }
8535 
8536 // Set the access specification for this symbol.
8537 Symbol &ModuleVisitor::SetAccess(
8538     const SourceName &name, Attr attr, Symbol *symbol) {
8539   if (!symbol) {
8540     symbol = &MakeSymbol(name);
8541   }
8542   Attrs &attrs{symbol->attrs()};
8543   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
8544     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
8545     Attr prev{attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE};
8546     if (attr != prev) {
8547       Say(name,
8548           "The accessibility of '%s' has already been specified as %s"_err_en_US,
8549           MakeOpName(name), EnumToString(prev));
8550     } else {
8551       context().Warn(common::LanguageFeature::RedundantAttribute, name,
8552           "The accessibility of '%s' has already been specified as %s"_warn_en_US,
8553           MakeOpName(name), EnumToString(prev));
8554     }
8555   } else {
8556     attrs.set(attr);
8557   }
8558   return *symbol;
8559 }
8560 
8561 static bool NeedsExplicitType(const Symbol &symbol) {
8562   if (symbol.has<UnknownDetails>()) {
8563     return true;
8564   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
8565     return !details->type();
8566   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
8567     return !details->type();
8568   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
8569     return !details->procInterface() && !details->type();
8570   } else {
8571     return false;
8572   }
8573 }
8574 
8575 void ResolveNamesVisitor::HandleDerivedTypesInImplicitStmts(
8576     const parser::ImplicitPart &implicitPart,
8577     const std::list<parser::DeclarationConstruct> &decls) {
8578   // Detect derived type definitions and create symbols for them now if
8579   // they appear in IMPLICIT statements so that these forward-looking
8580   // references will not be ambiguous with host associations.
8581   std::set<SourceName> implicitDerivedTypes;
8582   for (const auto &ipStmt : implicitPart.v) {
8583     if (const auto *impl{std::get_if<
8584             parser::Statement<common::Indirection<parser::ImplicitStmt>>>(
8585             &ipStmt.u)}) {
8586       if (const auto *specs{std::get_if<std::list<parser::ImplicitSpec>>(
8587               &impl->statement.value().u)}) {
8588         for (const auto &spec : *specs) {
8589           const auto &declTypeSpec{
8590               std::get<parser::DeclarationTypeSpec>(spec.t)};
8591           if (const auto *dtSpec{common::visit(
8592                   common::visitors{
8593                       [](const parser::DeclarationTypeSpec::Type &x) {
8594                         return &x.derived;
8595                       },
8596                       [](const parser::DeclarationTypeSpec::Class &x) {
8597                         return &x.derived;
8598                       },
8599                       [](const auto &) -> const parser::DerivedTypeSpec * {
8600                         return nullptr;
8601                       }},
8602                   declTypeSpec.u)}) {
8603             implicitDerivedTypes.emplace(
8604                 std::get<parser::Name>(dtSpec->t).source);
8605           }
8606         }
8607       }
8608     }
8609   }
8610   if (!implicitDerivedTypes.empty()) {
8611     for (const auto &decl : decls) {
8612       if (const auto *spec{
8613               std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
8614         if (const auto *dtDef{
8615                 std::get_if<common::Indirection<parser::DerivedTypeDef>>(
8616                     &spec->u)}) {
8617           const parser::DerivedTypeStmt &dtStmt{
8618               std::get<parser::Statement<parser::DerivedTypeStmt>>(
8619                   dtDef->value().t)
8620                   .statement};
8621           const parser::Name &name{std::get<parser::Name>(dtStmt.t)};
8622           if (implicitDerivedTypes.find(name.source) !=
8623                   implicitDerivedTypes.end() &&
8624               !FindInScope(name)) {
8625             DerivedTypeDetails details;
8626             details.set_isForwardReferenced(true);
8627             Resolve(name, MakeSymbol(name, std::move(details)));
8628             implicitDerivedTypes.erase(name.source);
8629           }
8630         }
8631       }
8632     }
8633   }
8634 }
8635 
8636 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
8637   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
8638       implicitPart, decls] = x.t;
8639   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
8640   auto stateRestorer{
8641       common::ScopedSet(specPartState_, SpecificationPartState{})};
8642   Walk(accDecls);
8643   Walk(ompDecls);
8644   Walk(compilerDirectives);
8645   for (const auto &useStmt : useStmts) {
8646     CollectUseRenames(useStmt.statement.value());
8647   }
8648   Walk(useStmts);
8649   UseCUDABuiltinNames();
8650   ClearUseRenames();
8651   ClearUseOnly();
8652   ClearModuleUses();
8653   Walk(importStmts);
8654   HandleDerivedTypesInImplicitStmts(implicitPart, decls);
8655   Walk(implicitPart);
8656   for (const auto &decl : decls) {
8657     if (const auto *spec{
8658             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
8659       PreSpecificationConstruct(*spec);
8660     }
8661   }
8662   Walk(decls);
8663   FinishSpecificationPart(decls);
8664   return false;
8665 }
8666 
8667 void ResolveNamesVisitor::UseCUDABuiltinNames() {
8668   if (FindCUDADeviceContext(&currScope())) {
8669     for (const auto &[name, symbol] : context().GetCUDABuiltinsScope()) {
8670       if (!FindInScope(name)) {
8671         auto &localSymbol{MakeSymbol(name)};
8672         localSymbol.set_details(UseDetails{name, *symbol});
8673         localSymbol.flags() = symbol->flags();
8674       }
8675     }
8676   }
8677 }
8678 
8679 // Initial processing on specification constructs, before visiting them.
8680 void ResolveNamesVisitor::PreSpecificationConstruct(
8681     const parser::SpecificationConstruct &spec) {
8682   common::visit(
8683       common::visitors{
8684           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
8685             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
8686           },
8687           [&](const Indirection<parser::InterfaceBlock> &y) {
8688             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
8689                 y.value().t)};
8690             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
8691               CreateGeneric(*spec);
8692             }
8693           },
8694           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
8695             common::visit(
8696                 common::visitors{
8697                     [&](const common::Indirection<parser::CommonStmt> &z) {
8698                       CreateCommonBlockSymbols(z.value());
8699                     },
8700                     [&](const common::Indirection<parser::TargetStmt> &z) {
8701                       CreateObjectSymbols(z.value().v, Attr::TARGET);
8702                     },
8703                     [](const auto &) {},
8704                 },
8705                 y.statement.u);
8706           },
8707           [](const auto &) {},
8708       },
8709       spec.u);
8710 }
8711 
8712 void ResolveNamesVisitor::CreateCommonBlockSymbols(
8713     const parser::CommonStmt &commonStmt) {
8714   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
8715     const auto &[name, objects] = block.t;
8716     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
8717     for (const auto &object : objects) {
8718       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
8719       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
8720         details->set_commonBlock(commonBlock);
8721         commonBlock.get<CommonBlockDetails>().add_object(obj);
8722       }
8723     }
8724   }
8725 }
8726 
8727 void ResolveNamesVisitor::CreateObjectSymbols(
8728     const std::list<parser::ObjectDecl> &decls, Attr attr) {
8729   for (const parser::ObjectDecl &decl : decls) {
8730     SetImplicitAttr(DeclareEntity<ObjectEntityDetails>(
8731                         std::get<parser::ObjectName>(decl.t), Attrs{}),
8732         attr);
8733   }
8734 }
8735 
8736 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
8737   auto info{GenericSpecInfo{x}};
8738   SourceName symbolName{info.symbolName()};
8739   if (IsLogicalConstant(context(), symbolName)) {
8740     Say(symbolName,
8741         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
8742     return;
8743   }
8744   GenericDetails genericDetails;
8745   Symbol *existing{nullptr};
8746   // Check all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
8747   for (const std::string &n : GetAllNames(context(), symbolName)) {
8748     existing = currScope().FindSymbol(SourceName{n});
8749     if (existing) {
8750       break;
8751     }
8752   }
8753   if (existing) {
8754     Symbol &ultimate{existing->GetUltimate()};
8755     if (auto *existingGeneric{ultimate.detailsIf<GenericDetails>()}) {
8756       if (&existing->owner() == &currScope()) {
8757         if (const auto *existingUse{existing->detailsIf<UseDetails>()}) {
8758           // Create a local copy of a use associated generic so that
8759           // it can be locally extended without corrupting the original.
8760           genericDetails.CopyFrom(*existingGeneric);
8761           if (existingGeneric->specific()) {
8762             genericDetails.set_specific(*existingGeneric->specific());
8763           }
8764           AddGenericUse(
8765               genericDetails, existing->name(), existingUse->symbol());
8766         } else if (existing == &ultimate) {
8767           // Extending an extant generic in the same scope
8768           info.Resolve(existing);
8769           return;
8770         } else {
8771           // Host association of a generic is handled elsewhere
8772           CHECK(existing->has<HostAssocDetails>());
8773         }
8774       } else {
8775         // Create a new generic for this scope.
8776       }
8777     } else if (ultimate.has<SubprogramDetails>() ||
8778         ultimate.has<SubprogramNameDetails>()) {
8779       genericDetails.set_specific(*existing);
8780     } else if (ultimate.has<ProcEntityDetails>()) {
8781       if (existing->name() != symbolName ||
8782           !ultimate.attrs().test(Attr::INTRINSIC)) {
8783         genericDetails.set_specific(*existing);
8784       }
8785     } else if (ultimate.has<DerivedTypeDetails>()) {
8786       genericDetails.set_derivedType(*existing);
8787     } else if (&existing->owner() == &currScope()) {
8788       SayAlreadyDeclared(symbolName, *existing);
8789       return;
8790     }
8791     if (&existing->owner() == &currScope()) {
8792       EraseSymbol(*existing);
8793     }
8794   }
8795   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
8796 }
8797 
8798 void ResolveNamesVisitor::FinishSpecificationPart(
8799     const std::list<parser::DeclarationConstruct> &decls) {
8800   misparsedStmtFuncFound_ = false;
8801   funcResultStack().CompleteFunctionResultType();
8802   CheckImports();
8803   for (auto &pair : currScope()) {
8804     auto &symbol{*pair.second};
8805     if (inInterfaceBlock()) {
8806       ConvertToObjectEntity(symbol);
8807     }
8808     if (NeedsExplicitType(symbol)) {
8809       ApplyImplicitRules(symbol);
8810     }
8811     if (IsDummy(symbol) && isImplicitNoneType() &&
8812         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
8813       Say(symbol.name(),
8814           "No explicit type declared for dummy argument '%s'"_err_en_US);
8815       context().SetError(symbol);
8816     }
8817     if (symbol.has<GenericDetails>()) {
8818       CheckGenericProcedures(symbol);
8819     }
8820     if (!symbol.has<HostAssocDetails>()) {
8821       CheckPossibleBadForwardRef(symbol);
8822     }
8823     // Propagate BIND(C) attribute to procedure entities from their interfaces,
8824     // but not the NAME=, even if it is empty (which would be a reasonable
8825     // and useful behavior, actually).  This interpretation is not at all
8826     // clearly described in the standard, but matches the behavior of several
8827     // other compilers.
8828     if (auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
8829         !proc->isDummy() && !IsPointer(symbol) &&
8830         !symbol.attrs().test(Attr::BIND_C)) {
8831       if (const Symbol * iface{proc->procInterface()};
8832           iface && IsBindCProcedure(*iface)) {
8833         SetImplicitAttr(symbol, Attr::BIND_C);
8834         SetBindNameOn(symbol);
8835       }
8836     }
8837   }
8838   currScope().InstantiateDerivedTypes();
8839   for (const auto &decl : decls) {
8840     if (const auto *statement{std::get_if<
8841             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
8842             &decl.u)}) {
8843       messageHandler().set_currStmtSource(statement->source);
8844       AnalyzeStmtFunctionStmt(statement->statement.value());
8845     }
8846   }
8847   // TODO: what about instantiations in BLOCK?
8848   CheckSaveStmts();
8849   CheckCommonBlocks();
8850   if (!inInterfaceBlock()) {
8851     // TODO: warn for the case where the EQUIVALENCE statement is in a
8852     // procedure declaration in an interface block
8853     CheckEquivalenceSets();
8854   }
8855 }
8856 
8857 // Analyze the bodies of statement functions now that the symbols in this
8858 // specification part have been fully declared and implicitly typed.
8859 // (Statement function references are not allowed in specification
8860 // expressions, so it's safe to defer processing their definitions.)
8861 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
8862     const parser::StmtFunctionStmt &stmtFunc) {
8863   const auto &name{std::get<parser::Name>(stmtFunc.t)};
8864   Symbol *symbol{name.symbol};
8865   auto *details{symbol ? symbol->detailsIf<SubprogramDetails>() : nullptr};
8866   if (!details || !symbol->scope() ||
8867       &symbol->scope()->parent() != &currScope() || details->isInterface() ||
8868       details->isDummy() || details->entryScope() ||
8869       details->moduleInterface() || symbol->test(Symbol::Flag::Subroutine)) {
8870     return; // error recovery
8871   }
8872   // Resolve the symbols on the RHS of the statement function.
8873   PushScope(*symbol->scope());
8874   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(stmtFunc.t)};
8875   Walk(parsedExpr);
8876   PopScope();
8877   if (auto expr{AnalyzeExpr(context(), stmtFunc)}) {
8878     if (auto type{evaluate::DynamicType::From(*symbol)}) {
8879       if (auto converted{evaluate::ConvertToType(*type, std::move(*expr))}) {
8880         details->set_stmtFunction(std::move(*converted));
8881       } else {
8882         Say(name.source,
8883             "Defining expression of statement function '%s' cannot be converted to its result type %s"_err_en_US,
8884             name.source, type->AsFortran());
8885       }
8886     } else {
8887       details->set_stmtFunction(std::move(*expr));
8888     }
8889   }
8890   if (!details->stmtFunction()) {
8891     context().SetError(*symbol);
8892   }
8893 }
8894 
8895 void ResolveNamesVisitor::CheckImports() {
8896   auto &scope{currScope()};
8897   switch (scope.GetImportKind()) {
8898   case common::ImportKind::None:
8899     break;
8900   case common::ImportKind::All:
8901     // C8102: all entities in host must not be hidden
8902     for (const auto &pair : scope.parent()) {
8903       auto &name{pair.first};
8904       std::optional<SourceName> scopeName{scope.GetName()};
8905       if (!scopeName || name != *scopeName) {
8906         CheckImport(prevImportStmt_.value(), name);
8907       }
8908     }
8909     break;
8910   case common::ImportKind::Default:
8911   case common::ImportKind::Only:
8912     // C8102: entities named in IMPORT must not be hidden
8913     for (auto &name : scope.importNames()) {
8914       CheckImport(name, name);
8915     }
8916     break;
8917   }
8918 }
8919 
8920 void ResolveNamesVisitor::CheckImport(
8921     const SourceName &location, const SourceName &name) {
8922   if (auto *symbol{FindInScope(name)}) {
8923     const Symbol &ultimate{symbol->GetUltimate()};
8924     if (&ultimate.owner() == &currScope()) {
8925       Say(location, "'%s' from host is not accessible"_err_en_US, name)
8926           .Attach(symbol->name(), "'%s' is hidden by this entity"_because_en_US,
8927               symbol->name());
8928     }
8929   }
8930 }
8931 
8932 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
8933   return CheckNotInBlock("IMPLICIT") && // C1107
8934       ImplicitRulesVisitor::Pre(x);
8935 }
8936 
8937 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
8938   common::visit(common::visitors{
8939                     [&](const parser::Name &x) { ResolveName(x); },
8940                     [&](const parser::StructureComponent &x) {
8941                       ResolveStructureComponent(x);
8942                     },
8943                 },
8944       x.u);
8945 }
8946 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
8947   common::visit(common::visitors{
8948                     [&](const parser::Name &x) { ResolveName(x); },
8949                     [&](const parser::StructureComponent &x) {
8950                       ResolveStructureComponent(x);
8951                     },
8952                 },
8953       x.u);
8954 }
8955 
8956 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
8957   const auto &dataRef{std::get<parser::DataRef>(x.t)};
8958   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
8959   const auto &expr{std::get<parser::Expr>(x.t)};
8960   ResolveDataRef(dataRef);
8961   Symbol *ptrSymbol{parser::GetLastName(dataRef).symbol};
8962   Walk(bounds);
8963   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
8964   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
8965     if (NameIsKnownOrIntrinsic(*name)) {
8966       if (Symbol * symbol{name->symbol}) {
8967         if (IsProcedurePointer(ptrSymbol) &&
8968             !ptrSymbol->test(Symbol::Flag::Function) &&
8969             !ptrSymbol->test(Symbol::Flag::Subroutine)) {
8970           if (symbol->test(Symbol::Flag::Function)) {
8971             ApplyImplicitRules(*ptrSymbol);
8972           }
8973         }
8974         // If the name is known because it is an object entity from a host
8975         // procedure, create a host associated symbol.
8976         if (symbol->GetUltimate().has<ObjectEntityDetails>() &&
8977             IsUplevelReference(*symbol)) {
8978           MakeHostAssocSymbol(*name, *symbol);
8979         }
8980       }
8981       return false;
8982     }
8983     // Can also reference a global external procedure here
8984     if (auto it{context().globalScope().find(name->source)};
8985         it != context().globalScope().end()) {
8986       Symbol &global{*it->second};
8987       if (IsProcedure(global)) {
8988         Resolve(*name, global);
8989         return false;
8990       }
8991     }
8992     if (IsProcedurePointer(parser::GetLastName(dataRef).symbol) &&
8993         !FindSymbol(*name)) {
8994       // Unknown target of procedure pointer must be an external procedure
8995       Symbol &symbol{MakeSymbol(
8996           context().globalScope(), name->source, Attrs{Attr::EXTERNAL})};
8997       symbol.implicitAttrs().set(Attr::EXTERNAL);
8998       Resolve(*name, symbol);
8999       ConvertToProcEntity(symbol, name->source);
9000       return false;
9001     }
9002   }
9003   Walk(expr);
9004   return false;
9005 }
9006 void ResolveNamesVisitor::Post(const parser::Designator &x) {
9007   ResolveDesignator(x);
9008 }
9009 void ResolveNamesVisitor::Post(const parser::SubstringInquiry &x) {
9010   Walk(std::get<parser::SubstringRange>(x.v.t).t);
9011   ResolveDataRef(std::get<parser::DataRef>(x.v.t));
9012 }
9013 
9014 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
9015   ResolveStructureComponent(x.v.thing);
9016 }
9017 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
9018   DeclTypeSpecVisitor::Post(x);
9019   ConstructVisitor::Post(x);
9020 }
9021 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
9022   if (HandleStmtFunction(x)) {
9023     return false;
9024   } else {
9025     // This is an array element or pointer-valued function assignment:
9026     // resolve the names of indices/arguments
9027     const auto &names{std::get<std::list<parser::Name>>(x.t)};
9028     for (auto &name : names) {
9029       ResolveName(name);
9030     }
9031     return true;
9032   }
9033 }
9034 
9035 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
9036   const parser::Name &name{x.v};
9037   if (FindSymbol(name)) {
9038     // OK
9039   } else if (IsLogicalConstant(context(), name.source)) {
9040     Say(name,
9041         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
9042   } else {
9043     // Resolved later in expression semantics
9044     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
9045   }
9046   return false;
9047 }
9048 
9049 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
9050   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
9051     CheckEntryDummyUse(name->source, name->symbol);
9052     ConvertToObjectEntity(DEREF(name->symbol));
9053   }
9054 }
9055 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
9056   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
9057     CheckEntryDummyUse(name->source, name->symbol);
9058     ConvertToObjectEntity(DEREF(name->symbol));
9059   }
9060 }
9061 
9062 void ResolveNamesVisitor::Post(const parser::CompilerDirective &x) {
9063   if (std::holds_alternative<parser::CompilerDirective::VectorAlways>(x.u)) {
9064     return;
9065   }
9066   if (const auto *tkr{
9067           std::get_if<std::list<parser::CompilerDirective::IgnoreTKR>>(&x.u)}) {
9068     if (currScope().IsTopLevel() ||
9069         GetProgramUnitContaining(currScope()).kind() !=
9070             Scope::Kind::Subprogram) {
9071       Say(x.source,
9072           "!DIR$ IGNORE_TKR directive must appear in a subroutine or function"_err_en_US);
9073       return;
9074     }
9075     if (!inSpecificationPart_) {
9076       Say(x.source,
9077           "!DIR$ IGNORE_TKR directive must appear in the specification part"_err_en_US);
9078       return;
9079     }
9080     if (tkr->empty()) {
9081       Symbol *symbol{currScope().symbol()};
9082       if (SubprogramDetails *
9083           subp{symbol ? symbol->detailsIf<SubprogramDetails>() : nullptr}) {
9084         subp->set_defaultIgnoreTKR(true);
9085       }
9086     } else {
9087       for (const parser::CompilerDirective::IgnoreTKR &item : *tkr) {
9088         common::IgnoreTKRSet set;
9089         if (const auto &maybeList{
9090                 std::get<std::optional<std::list<const char *>>>(item.t)}) {
9091           for (const char *p : *maybeList) {
9092             if (p) {
9093               switch (*p) {
9094               case 't':
9095                 set.set(common::IgnoreTKR::Type);
9096                 break;
9097               case 'k':
9098                 set.set(common::IgnoreTKR::Kind);
9099                 break;
9100               case 'r':
9101                 set.set(common::IgnoreTKR::Rank);
9102                 break;
9103               case 'd':
9104                 set.set(common::IgnoreTKR::Device);
9105                 break;
9106               case 'm':
9107                 set.set(common::IgnoreTKR::Managed);
9108                 break;
9109               case 'c':
9110                 set.set(common::IgnoreTKR::Contiguous);
9111                 break;
9112               case 'a':
9113                 set = common::ignoreTKRAll;
9114                 break;
9115               default:
9116                 Say(x.source,
9117                     "'%c' is not a valid letter for !DIR$ IGNORE_TKR directive"_err_en_US,
9118                     *p);
9119                 set = common::ignoreTKRAll;
9120                 break;
9121               }
9122             }
9123           }
9124           if (set.empty()) {
9125             Say(x.source,
9126                 "!DIR$ IGNORE_TKR directive may not have an empty parenthesized list of letters"_err_en_US);
9127           }
9128         } else { // no (list)
9129           set = common::ignoreTKRAll;
9130           ;
9131         }
9132         const auto &name{std::get<parser::Name>(item.t)};
9133         Symbol *symbol{FindSymbol(name)};
9134         if (!symbol) {
9135           symbol = &MakeSymbol(name, Attrs{}, ObjectEntityDetails{});
9136         }
9137         if (symbol->owner() != currScope()) {
9138           SayWithDecl(
9139               name, *symbol, "'%s' must be local to this subprogram"_err_en_US);
9140         } else {
9141           ConvertToObjectEntity(*symbol);
9142           if (auto *object{symbol->detailsIf<ObjectEntityDetails>()}) {
9143             object->set_ignoreTKR(set);
9144           } else {
9145             SayWithDecl(name, *symbol, "'%s' must be an object"_err_en_US);
9146           }
9147         }
9148       }
9149     }
9150   } else if (context().ShouldWarn(common::UsageWarning::IgnoredDirective)) {
9151     Say(x.source, "Unrecognized compiler directive was ignored"_warn_en_US)
9152         .set_usageWarning(common::UsageWarning::IgnoredDirective);
9153   }
9154 }
9155 
9156 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
9157   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
9158           x.u)) {
9159     // TODO: global directives
9160     return true;
9161   }
9162   if (std::holds_alternative<
9163           common::Indirection<parser::OpenACCRoutineConstruct>>(x.u)) {
9164     ResolveAccParts(context(), x, &topScope_);
9165     return false;
9166   }
9167   ProgramTree &root{ProgramTree::Build(x, context())};
9168   SetScope(topScope_);
9169   ResolveSpecificationParts(root);
9170   FinishSpecificationParts(root);
9171   ResolveExecutionParts(root);
9172   FinishExecutionParts(root);
9173   ResolveAccParts(context(), x, /*topScope=*/nullptr);
9174   ResolveOmpParts(context(), x);
9175   return false;
9176 }
9177 
9178 template <typename A> std::set<SourceName> GetUses(const A &x) {
9179   std::set<SourceName> uses;
9180   if constexpr (!std::is_same_v<A, parser::CompilerDirective> &&
9181       !std::is_same_v<A, parser::OpenACCRoutineConstruct>) {
9182     const auto &spec{std::get<parser::SpecificationPart>(x.t)};
9183     const auto &unitUses{std::get<
9184         std::list<parser::Statement<common::Indirection<parser::UseStmt>>>>(
9185         spec.t)};
9186     for (const auto &u : unitUses) {
9187       uses.insert(u.statement.value().moduleName.source);
9188     }
9189   }
9190   return uses;
9191 }
9192 
9193 bool ResolveNamesVisitor::Pre(const parser::Program &x) {
9194   std::map<SourceName, const parser::ProgramUnit *> modules;
9195   std::set<SourceName> uses;
9196   bool disordered{false};
9197   for (const auto &progUnit : x.v) {
9198     if (const auto *indMod{
9199             std::get_if<common::Indirection<parser::Module>>(&progUnit.u)}) {
9200       const parser::Module &mod{indMod->value()};
9201       const auto &moduleStmt{
9202           std::get<parser::Statement<parser::ModuleStmt>>(mod.t)};
9203       const SourceName &name{moduleStmt.statement.v.source};
9204       if (auto iter{modules.find(name)}; iter != modules.end()) {
9205         Say(name,
9206             "Module '%s' appears multiple times in a compilation unit"_err_en_US)
9207             .Attach(iter->first, "First definition of module"_en_US);
9208         return true;
9209       }
9210       modules.emplace(name, &progUnit);
9211       if (auto iter{uses.find(name)}; iter != uses.end()) {
9212         if (context().ShouldWarn(common::LanguageFeature::MiscUseExtensions)) {
9213           Say(name,
9214               "A USE statement referencing module '%s' appears earlier in this compilation unit"_port_en_US,
9215               name)
9216               .Attach(*iter, "First USE of module"_en_US);
9217         }
9218         disordered = true;
9219       }
9220     }
9221     for (SourceName used : common::visit(
9222              [](const auto &indUnit) { return GetUses(indUnit.value()); },
9223              progUnit.u)) {
9224       uses.insert(used);
9225     }
9226   }
9227   if (!disordered) {
9228     return true;
9229   }
9230   // Process modules in topological order
9231   std::vector<const parser::ProgramUnit *> moduleOrder;
9232   while (!modules.empty()) {
9233     bool ok;
9234     for (const auto &pair : modules) {
9235       const SourceName &name{pair.first};
9236       const parser::ProgramUnit &progUnit{*pair.second};
9237       const parser::Module &m{
9238           std::get<common::Indirection<parser::Module>>(progUnit.u).value()};
9239       ok = true;
9240       for (const SourceName &use : GetUses(m)) {
9241         if (modules.find(use) != modules.end()) {
9242           ok = false;
9243           break;
9244         }
9245       }
9246       if (ok) {
9247         moduleOrder.push_back(&progUnit);
9248         modules.erase(name);
9249         break;
9250       }
9251     }
9252     if (!ok) {
9253       Message *msg{nullptr};
9254       for (const auto &pair : modules) {
9255         if (msg) {
9256           msg->Attach(pair.first, "Module in a cycle"_en_US);
9257         } else {
9258           msg = &Say(pair.first,
9259               "Some modules in this compilation unit form one or more cycles of dependence"_err_en_US);
9260         }
9261       }
9262       return false;
9263     }
9264   }
9265   // Modules can be ordered.  Process them first, and then all of the other
9266   // program units.
9267   for (const parser::ProgramUnit *progUnit : moduleOrder) {
9268     Walk(*progUnit);
9269   }
9270   for (const auto &progUnit : x.v) {
9271     if (!std::get_if<common::Indirection<parser::Module>>(&progUnit.u)) {
9272       Walk(progUnit);
9273     }
9274   }
9275   return false;
9276 }
9277 
9278 // References to procedures need to record that their symbols are known
9279 // to be procedures, so that they don't get converted to objects by default.
9280 class ExecutionPartCallSkimmer : public ExecutionPartSkimmerBase {
9281 public:
9282   explicit ExecutionPartCallSkimmer(ResolveNamesVisitor &resolver)
9283       : resolver_{resolver} {}
9284 
9285   void Walk(const parser::ExecutionPart &exec) {
9286     parser::Walk(exec, *this);
9287     EndWalk();
9288   }
9289 
9290   using ExecutionPartSkimmerBase::Post;
9291   using ExecutionPartSkimmerBase::Pre;
9292 
9293   void Post(const parser::FunctionReference &fr) {
9294     NoteCall(Symbol::Flag::Function, fr.v, false);
9295   }
9296   void Post(const parser::CallStmt &cs) {
9297     NoteCall(Symbol::Flag::Subroutine, cs.call, cs.chevrons.has_value());
9298   }
9299 
9300 private:
9301   void NoteCall(
9302       Symbol::Flag flag, const parser::Call &call, bool hasCUDAChevrons) {
9303     auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
9304     if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
9305       if (!IsHidden(name->source)) {
9306         resolver_.NoteExecutablePartCall(flag, name->source, hasCUDAChevrons);
9307       }
9308     }
9309   }
9310 
9311   ResolveNamesVisitor &resolver_;
9312 };
9313 
9314 // Build the scope tree and resolve names in the specification parts of this
9315 // node and its children
9316 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
9317   if (node.isSpecificationPartResolved()) {
9318     return; // been here already
9319   }
9320   node.set_isSpecificationPartResolved();
9321   if (!BeginScopeForNode(node)) {
9322     return; // an error prevented scope from being created
9323   }
9324   Scope &scope{currScope()};
9325   node.set_scope(scope);
9326   AddSubpNames(node);
9327   common::visit(
9328       [&](const auto *x) {
9329         if (x) {
9330           Walk(*x);
9331         }
9332       },
9333       node.stmt());
9334   Walk(node.spec());
9335   // If this is a function, convert result to an object. This is to prevent the
9336   // result from being converted later to a function symbol if it is called
9337   // inside the function.
9338   // If the result is function pointer, then ConvertToObjectEntity will not
9339   // convert the result to an object, and calling the symbol inside the function
9340   // will result in calls to the result pointer.
9341   // A function cannot be called recursively if RESULT was not used to define a
9342   // distinct result name (15.6.2.2 point 4.).
9343   if (Symbol * symbol{scope.symbol()}) {
9344     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
9345       if (details->isFunction()) {
9346         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
9347       }
9348     }
9349   }
9350   if (node.IsModule()) {
9351     ApplyDefaultAccess();
9352   }
9353   for (auto &child : node.children()) {
9354     ResolveSpecificationParts(child);
9355   }
9356   if (node.exec()) {
9357     ExecutionPartCallSkimmer{*this}.Walk(*node.exec());
9358     HandleImpliedAsynchronousInScope(node.exec()->v);
9359   }
9360   EndScopeForNode(node);
9361   // Ensure that every object entity has a type.
9362   bool inModule{node.GetKind() == ProgramTree::Kind::Module ||
9363       node.GetKind() == ProgramTree::Kind::Submodule};
9364   for (auto &pair : *node.scope()) {
9365     Symbol &symbol{*pair.second};
9366     if (inModule && symbol.attrs().test(Attr::EXTERNAL) && !IsPointer(symbol) &&
9367         !symbol.test(Symbol::Flag::Function) &&
9368         !symbol.test(Symbol::Flag::Subroutine)) {
9369       // in a module, external proc without return type is subroutine
9370       symbol.set(
9371           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
9372     }
9373     ApplyImplicitRules(symbol);
9374   }
9375 }
9376 
9377 // Add SubprogramNameDetails symbols for module and internal subprograms and
9378 // their ENTRY statements.
9379 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
9380   auto kind{
9381       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
9382   for (auto &child : node.children()) {
9383     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
9384     if (child.HasModulePrefix()) {
9385       SetExplicitAttr(symbol, Attr::MODULE);
9386     }
9387     if (child.bindingSpec()) {
9388       SetExplicitAttr(symbol, Attr::BIND_C);
9389     }
9390     auto childKind{child.GetKind()};
9391     if (childKind == ProgramTree::Kind::Function) {
9392       symbol.set(Symbol::Flag::Function);
9393     } else if (childKind == ProgramTree::Kind::Subroutine) {
9394       symbol.set(Symbol::Flag::Subroutine);
9395     } else {
9396       continue; // make ENTRY symbols only where valid
9397     }
9398     for (const auto &entryStmt : child.entryStmts()) {
9399       SubprogramNameDetails details{kind, child};
9400       auto &symbol{
9401           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
9402       symbol.set(child.GetSubpFlag());
9403       if (child.HasModulePrefix()) {
9404         SetExplicitAttr(symbol, Attr::MODULE);
9405       }
9406       if (child.bindingSpec()) {
9407         SetExplicitAttr(symbol, Attr::BIND_C);
9408       }
9409     }
9410   }
9411   for (const auto &generic : node.genericSpecs()) {
9412     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
9413       if (currScope().find(name->source) != currScope().end()) {
9414         // If this scope has both a generic interface and a contained
9415         // subprogram with the same name, create the generic's symbol
9416         // now so that any other generics of the same name that are pulled
9417         // into scope later via USE association will properly merge instead
9418         // of raising a bogus error due a conflict with the subprogram.
9419         CreateGeneric(*generic);
9420       }
9421     }
9422   }
9423 }
9424 
9425 // Push a new scope for this node or return false on error.
9426 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
9427   switch (node.GetKind()) {
9428     SWITCH_COVERS_ALL_CASES
9429   case ProgramTree::Kind::Program:
9430     PushScope(Scope::Kind::MainProgram,
9431         &MakeSymbol(node.name(), MainProgramDetails{}));
9432     return true;
9433   case ProgramTree::Kind::Function:
9434   case ProgramTree::Kind::Subroutine:
9435     return BeginSubprogram(node.name(), node.GetSubpFlag(),
9436         node.HasModulePrefix(), node.bindingSpec(), &node.entryStmts());
9437   case ProgramTree::Kind::MpSubprogram:
9438     return BeginMpSubprogram(node.name());
9439   case ProgramTree::Kind::Module:
9440     BeginModule(node.name(), false);
9441     return true;
9442   case ProgramTree::Kind::Submodule:
9443     return BeginSubmodule(node.name(), node.GetParentId());
9444   case ProgramTree::Kind::BlockData:
9445     PushBlockDataScope(node.name());
9446     return true;
9447   }
9448 }
9449 
9450 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
9451   std::optional<parser::CharBlock> stmtSource;
9452   const std::optional<parser::LanguageBindingSpec> *binding{nullptr};
9453   common::visit(
9454       common::visitors{
9455           [&](const parser::Statement<parser::FunctionStmt> *stmt) {
9456             if (stmt) {
9457               stmtSource = stmt->source;
9458               if (const auto &maybeSuffix{
9459                       std::get<std::optional<parser::Suffix>>(
9460                           stmt->statement.t)}) {
9461                 binding = &maybeSuffix->binding;
9462               }
9463             }
9464           },
9465           [&](const parser::Statement<parser::SubroutineStmt> *stmt) {
9466             if (stmt) {
9467               stmtSource = stmt->source;
9468               binding = &std::get<std::optional<parser::LanguageBindingSpec>>(
9469                   stmt->statement.t);
9470             }
9471           },
9472           [](const auto *) {},
9473       },
9474       node.stmt());
9475   EndSubprogram(stmtSource, binding, &node.entryStmts());
9476 }
9477 
9478 // Some analyses and checks, such as the processing of initializers of
9479 // pointers, are deferred until all of the pertinent specification parts
9480 // have been visited.  This deferred processing enables the use of forward
9481 // references in these circumstances.
9482 // Data statement objects with implicit derived types are finally
9483 // resolved here.
9484 class DeferredCheckVisitor {
9485 public:
9486   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
9487       : resolver_{resolver} {}
9488 
9489   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
9490 
9491   template <typename A> bool Pre(const A &) { return true; }
9492   template <typename A> void Post(const A &) {}
9493 
9494   void Post(const parser::DerivedTypeStmt &x) {
9495     const auto &name{std::get<parser::Name>(x.t)};
9496     if (Symbol * symbol{name.symbol}) {
9497       if (Scope * scope{symbol->scope()}) {
9498         if (scope->IsDerivedType()) {
9499           CHECK(outerScope_ == nullptr);
9500           outerScope_ = &resolver_.currScope();
9501           resolver_.SetScope(*scope);
9502         }
9503       }
9504     }
9505   }
9506   void Post(const parser::EndTypeStmt &) {
9507     if (outerScope_) {
9508       resolver_.SetScope(*outerScope_);
9509       outerScope_ = nullptr;
9510     }
9511   }
9512 
9513   void Post(const parser::ProcInterface &pi) {
9514     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
9515       resolver_.CheckExplicitInterface(*name);
9516     }
9517   }
9518   bool Pre(const parser::EntityDecl &decl) {
9519     Init(std::get<parser::Name>(decl.t),
9520         std::get<std::optional<parser::Initialization>>(decl.t));
9521     return false;
9522   }
9523   bool Pre(const parser::ComponentDecl &decl) {
9524     Init(std::get<parser::Name>(decl.t),
9525         std::get<std::optional<parser::Initialization>>(decl.t));
9526     return false;
9527   }
9528   bool Pre(const parser::ProcDecl &decl) {
9529     if (const auto &init{
9530             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
9531       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
9532     }
9533     return false;
9534   }
9535   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
9536     resolver_.CheckExplicitInterface(tbps.interfaceName);
9537   }
9538   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
9539     if (outerScope_) {
9540       resolver_.CheckBindings(tbps);
9541     }
9542   }
9543   bool Pre(const parser::DataStmtObject &) {
9544     ++dataStmtObjectNesting_;
9545     return true;
9546   }
9547   void Post(const parser::DataStmtObject &) { --dataStmtObjectNesting_; }
9548   void Post(const parser::Designator &x) {
9549     if (dataStmtObjectNesting_ > 0) {
9550       resolver_.ResolveDesignator(x);
9551     }
9552   }
9553 
9554 private:
9555   void Init(const parser::Name &name,
9556       const std::optional<parser::Initialization> &init) {
9557     if (init) {
9558       if (const auto *target{
9559               std::get_if<parser::InitialDataTarget>(&init->u)}) {
9560         resolver_.PointerInitialization(name, *target);
9561       } else if (const auto *expr{
9562                      std::get_if<parser::ConstantExpr>(&init->u)}) {
9563         if (name.symbol) {
9564           if (const auto *object{name.symbol->detailsIf<ObjectEntityDetails>()};
9565               !object || !object->init()) {
9566             resolver_.NonPointerInitialization(name, *expr);
9567           }
9568         }
9569       }
9570     }
9571   }
9572 
9573   ResolveNamesVisitor &resolver_;
9574   Scope *outerScope_{nullptr};
9575   int dataStmtObjectNesting_{0};
9576 };
9577 
9578 // Perform checks and completions that need to happen after all of
9579 // the specification parts but before any of the execution parts.
9580 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
9581   if (!node.scope()) {
9582     return; // error occurred creating scope
9583   }
9584   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
9585   SetScope(*node.scope());
9586   // The initializers of pointers and non-PARAMETER objects, the default
9587   // initializers of components, and non-deferred type-bound procedure
9588   // bindings have not yet been traversed.
9589   // We do that now, when any forward references that appeared
9590   // in those initializers will resolve to the right symbols without
9591   // incurring spurious errors with IMPLICIT NONE or forward references
9592   // to nested subprograms.
9593   DeferredCheckVisitor{*this}.Walk(node.spec());
9594   for (Scope &childScope : currScope().children()) {
9595     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
9596       FinishDerivedTypeInstantiation(childScope);
9597     }
9598   }
9599   for (const auto &child : node.children()) {
9600     FinishSpecificationParts(child);
9601   }
9602 }
9603 
9604 void ResolveNamesVisitor::FinishExecutionParts(const ProgramTree &node) {
9605   if (node.scope()) {
9606     SetScope(*node.scope());
9607     if (node.exec()) {
9608       DeferredCheckVisitor{*this}.Walk(*node.exec());
9609     }
9610     for (const auto &child : node.children()) {
9611       FinishExecutionParts(child);
9612     }
9613   }
9614 }
9615 
9616 // Duplicate and fold component object pointer default initializer designators
9617 // using the actual type parameter values of each particular instantiation.
9618 // Validation is done later in declaration checking.
9619 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
9620   CHECK(scope.IsDerivedType() && !scope.symbol());
9621   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
9622     spec->Instantiate(currScope());
9623     const Symbol &origTypeSymbol{spec->typeSymbol()};
9624     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
9625       CHECK(origTypeScope->IsDerivedType() &&
9626           origTypeScope->symbol() == &origTypeSymbol);
9627       auto &foldingContext{GetFoldingContext()};
9628       auto restorer{foldingContext.WithPDTInstance(*spec)};
9629       for (auto &pair : scope) {
9630         Symbol &comp{*pair.second};
9631         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
9632         if (IsPointer(comp)) {
9633           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
9634             auto origDetails{origComp.get<ObjectEntityDetails>()};
9635             if (const MaybeExpr & init{origDetails.init()}) {
9636               SomeExpr newInit{*init};
9637               MaybeExpr folded{FoldExpr(std::move(newInit))};
9638               details->set_init(std::move(folded));
9639             }
9640           }
9641         }
9642       }
9643     }
9644   }
9645 }
9646 
9647 // Resolve names in the execution part of this node and its children
9648 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
9649   if (!node.scope()) {
9650     return; // error occurred creating scope
9651   }
9652   SetScope(*node.scope());
9653   if (const auto *exec{node.exec()}) {
9654     Walk(*exec);
9655   }
9656   FinishNamelists();
9657   if (node.IsModule()) {
9658     // A second final pass to catch new symbols added from implicitly
9659     // typed names in NAMELIST groups or the specification parts of
9660     // module subprograms.
9661     ApplyDefaultAccess();
9662   }
9663   PopScope(); // converts unclassified entities into objects
9664   for (const auto &child : node.children()) {
9665     ResolveExecutionParts(child);
9666   }
9667 }
9668 
9669 void ResolveNamesVisitor::Post(const parser::Program &x) {
9670   // ensure that all temps were deallocated
9671   CHECK(!attrs_);
9672   CHECK(!cudaDataAttr_);
9673   CHECK(!GetDeclTypeSpec());
9674   // Top-level resolution to propagate information across program units after
9675   // each of them has been resolved separately.
9676   ResolveOmpTopLevelParts(context(), x);
9677 }
9678 
9679 // A singleton instance of the scope -> IMPLICIT rules mapping is
9680 // shared by all instances of ResolveNamesVisitor and accessed by this
9681 // pointer when the visitors (other than the top-level original) are
9682 // constructed.
9683 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
9684 
9685 bool ResolveNames(
9686     SemanticsContext &context, const parser::Program &program, Scope &top) {
9687   ImplicitRulesMap implicitRulesMap;
9688   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
9689   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
9690   return !context.AnyFatalError();
9691 }
9692 
9693 // Processes a module (but not internal) function when it is referenced
9694 // in a specification expression in a sibling procedure.
9695 void ResolveSpecificationParts(
9696     SemanticsContext &context, const Symbol &subprogram) {
9697   auto originalLocation{context.location()};
9698   ImplicitRulesMap implicitRulesMap;
9699   bool localImplicitRulesMap{false};
9700   if (!sharedImplicitRulesMap) {
9701     sharedImplicitRulesMap = &implicitRulesMap;
9702     localImplicitRulesMap = true;
9703   }
9704   ResolveNamesVisitor visitor{
9705       context, *sharedImplicitRulesMap, context.globalScope()};
9706   const auto &details{subprogram.get<SubprogramNameDetails>()};
9707   ProgramTree &node{details.node()};
9708   const Scope &moduleScope{subprogram.owner()};
9709   if (localImplicitRulesMap) {
9710     visitor.BeginScope(const_cast<Scope &>(moduleScope));
9711   } else {
9712     visitor.SetScope(const_cast<Scope &>(moduleScope));
9713   }
9714   visitor.ResolveSpecificationParts(node);
9715   context.set_location(std::move(originalLocation));
9716   if (localImplicitRulesMap) {
9717     sharedImplicitRulesMap = nullptr;
9718   }
9719 }
9720 
9721 } // namespace Fortran::semantics
9722