xref: /llvm-project/flang/lib/Evaluate/characteristics.cpp (revision 09c544e76012e7559a7be7fca34aeb8584da91a7)
1 //===-- lib/Evaluate/characteristics.cpp ----------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
9 #include "flang/Evaluate/characteristics.h"
10 #include "flang/Common/indirection.h"
11 #include "flang/Evaluate/check-expression.h"
12 #include "flang/Evaluate/fold.h"
13 #include "flang/Evaluate/intrinsics.h"
14 #include "flang/Evaluate/tools.h"
15 #include "flang/Evaluate/type.h"
16 #include "flang/Parser/message.h"
17 #include "flang/Semantics/scope.h"
18 #include "flang/Semantics/symbol.h"
19 #include "flang/Semantics/tools.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <initializer_list>
22 
23 using namespace Fortran::parser::literals;
24 
25 namespace Fortran::evaluate::characteristics {
26 
27 // Copy attributes from a symbol to dst based on the mapping in pairs.
28 template <typename A, typename B>
29 static void CopyAttrs(const semantics::Symbol &src, A &dst,
30     const std::initializer_list<std::pair<semantics::Attr, B>> &pairs) {
31   for (const auto &pair : pairs) {
32     if (src.attrs().test(pair.first)) {
33       dst.attrs.set(pair.second);
34     }
35   }
36 }
37 
38 // Shapes of function results and dummy arguments have to have
39 // the same rank, the same deferred dimensions, and the same
40 // values for explicit dimensions when constant.
41 bool ShapesAreCompatible(const Shape &x, const Shape &y) {
42   if (x.size() != y.size()) {
43     return false;
44   }
45   auto yIter{y.begin()};
46   for (const auto &xDim : x) {
47     const auto &yDim{*yIter++};
48     if (xDim) {
49       if (!yDim || ToInt64(*xDim) != ToInt64(*yDim)) {
50         return false;
51       }
52     } else if (yDim) {
53       return false;
54     }
55   }
56   return true;
57 }
58 
59 bool TypeAndShape::operator==(const TypeAndShape &that) const {
60   return type_ == that.type_ && ShapesAreCompatible(shape_, that.shape_) &&
61       attrs_ == that.attrs_ && corank_ == that.corank_;
62 }
63 
64 TypeAndShape &TypeAndShape::Rewrite(FoldingContext &context) {
65   LEN_ = Fold(context, std::move(LEN_));
66   if (LEN_) {
67     if (auto n{ToInt64(*LEN_)}) {
68       type_ = DynamicType{type_.kind(), *n};
69     }
70   }
71   shape_ = Fold(context, std::move(shape_));
72   return *this;
73 }
74 
75 std::optional<TypeAndShape> TypeAndShape::Characterize(
76     const semantics::Symbol &symbol, FoldingContext &context,
77     bool invariantOnly) {
78   const auto &ultimate{symbol.GetUltimate()};
79   return common::visit(
80       common::visitors{
81           [&](const semantics::ProcEntityDetails &proc) {
82             if (proc.procInterface()) {
83               return Characterize(
84                   *proc.procInterface(), context, invariantOnly);
85             } else if (proc.type()) {
86               return Characterize(*proc.type(), context, invariantOnly);
87             } else {
88               return std::optional<TypeAndShape>{};
89             }
90           },
91           [&](const semantics::AssocEntityDetails &assoc) {
92             return Characterize(assoc, context, invariantOnly);
93           },
94           [&](const semantics::ProcBindingDetails &binding) {
95             return Characterize(binding.symbol(), context, invariantOnly);
96           },
97           [&](const auto &x) -> std::optional<TypeAndShape> {
98             using Ty = std::decay_t<decltype(x)>;
99             if constexpr (std::is_same_v<Ty, semantics::EntityDetails> ||
100                 std::is_same_v<Ty, semantics::ObjectEntityDetails> ||
101                 std::is_same_v<Ty, semantics::TypeParamDetails>) {
102               if (const semantics::DeclTypeSpec * type{ultimate.GetType()}) {
103                 if (auto dyType{DynamicType::From(*type)}) {
104                   TypeAndShape result{std::move(*dyType),
105                       GetShape(context, ultimate, invariantOnly)};
106                   result.AcquireAttrs(ultimate);
107                   result.AcquireLEN(ultimate);
108                   return std::move(result.Rewrite(context));
109                 }
110               }
111             }
112             return std::nullopt;
113           },
114       },
115       // GetUltimate() used here, not ResolveAssociations(), because
116       // we need the type/rank of an associate entity from TYPE IS,
117       // CLASS IS, or RANK statement.
118       ultimate.details());
119 }
120 
121 std::optional<TypeAndShape> TypeAndShape::Characterize(
122     const semantics::AssocEntityDetails &assoc, FoldingContext &context,
123     bool invariantOnly) {
124   std::optional<TypeAndShape> result;
125   if (auto type{DynamicType::From(assoc.type())}) {
126     if (auto rank{assoc.rank()}) {
127       if (*rank >= 0 && *rank <= common::maxRank) {
128         result = TypeAndShape{std::move(*type), Shape(*rank)};
129       }
130     } else if (auto shape{GetShape(context, assoc.expr(), invariantOnly)}) {
131       result = TypeAndShape{std::move(*type), std::move(*shape)};
132     }
133     if (result && type->category() == TypeCategory::Character) {
134       if (const auto *chExpr{UnwrapExpr<Expr<SomeCharacter>>(assoc.expr())}) {
135         if (auto len{chExpr->LEN()}) {
136           result->set_LEN(std::move(*len));
137         }
138       }
139     }
140   }
141   return Fold(context, std::move(result));
142 }
143 
144 std::optional<TypeAndShape> TypeAndShape::Characterize(
145     const semantics::DeclTypeSpec &spec, FoldingContext &context,
146     bool /*invariantOnly=*/) {
147   if (auto type{DynamicType::From(spec)}) {
148     return Fold(context, TypeAndShape{std::move(*type)});
149   } else {
150     return std::nullopt;
151   }
152 }
153 
154 std::optional<TypeAndShape> TypeAndShape::Characterize(
155     const ActualArgument &arg, FoldingContext &context, bool invariantOnly) {
156   if (const auto *expr{arg.UnwrapExpr()}) {
157     return Characterize(*expr, context, invariantOnly);
158   } else if (const Symbol * assumed{arg.GetAssumedTypeDummy()}) {
159     return Characterize(*assumed, context, invariantOnly);
160   } else {
161     return std::nullopt;
162   }
163 }
164 
165 bool TypeAndShape::IsCompatibleWith(parser::ContextualMessages &messages,
166     const TypeAndShape &that, const char *thisIs, const char *thatIs,
167     bool omitShapeConformanceCheck,
168     enum CheckConformanceFlags::Flags flags) const {
169   if (!type_.IsTkCompatibleWith(that.type_)) {
170     messages.Say(
171         "%1$s type '%2$s' is not compatible with %3$s type '%4$s'"_err_en_US,
172         thatIs, that.AsFortran(), thisIs, AsFortran());
173     return false;
174   }
175   return omitShapeConformanceCheck ||
176       CheckConformance(messages, shape_, that.shape_, flags, thisIs, thatIs)
177           .value_or(true /*fail only when nonconformance is known now*/);
178 }
179 
180 std::optional<Expr<SubscriptInteger>> TypeAndShape::MeasureElementSizeInBytes(
181     FoldingContext &foldingContext, bool align) const {
182   if (LEN_) {
183     CHECK(type_.category() == TypeCategory::Character);
184     return Fold(foldingContext,
185         Expr<SubscriptInteger>{
186             foldingContext.targetCharacteristics().GetByteSize(
187                 type_.category(), type_.kind())} *
188             Expr<SubscriptInteger>{*LEN_});
189   }
190   if (auto elementBytes{type_.MeasureSizeInBytes(foldingContext, align)}) {
191     return Fold(foldingContext, std::move(*elementBytes));
192   }
193   return std::nullopt;
194 }
195 
196 std::optional<Expr<SubscriptInteger>> TypeAndShape::MeasureSizeInBytes(
197     FoldingContext &foldingContext) const {
198   if (auto elements{GetSize(Shape{shape_})}) {
199     // Sizes of arrays (even with single elements) are multiples of
200     // their alignments.
201     if (auto elementBytes{
202             MeasureElementSizeInBytes(foldingContext, GetRank(shape_) > 0)}) {
203       return Fold(
204           foldingContext, std::move(*elements) * std::move(*elementBytes));
205     }
206   }
207   return std::nullopt;
208 }
209 
210 void TypeAndShape::AcquireAttrs(const semantics::Symbol &symbol) {
211   if (IsAssumedShape(symbol)) {
212     attrs_.set(Attr::AssumedShape);
213   }
214   if (IsDeferredShape(symbol)) {
215     attrs_.set(Attr::DeferredShape);
216   }
217   if (const auto *object{
218           symbol.GetUltimate().detailsIf<semantics::ObjectEntityDetails>()}) {
219     corank_ = object->coshape().Rank();
220     if (object->IsAssumedRank()) {
221       attrs_.set(Attr::AssumedRank);
222     }
223     if (object->IsAssumedSize()) {
224       attrs_.set(Attr::AssumedSize);
225     }
226     if (object->IsCoarray()) {
227       attrs_.set(Attr::Coarray);
228     }
229   }
230 }
231 
232 void TypeAndShape::AcquireLEN() {
233   if (auto len{type_.GetCharLength()}) {
234     LEN_ = std::move(len);
235   }
236 }
237 
238 void TypeAndShape::AcquireLEN(const semantics::Symbol &symbol) {
239   if (type_.category() == TypeCategory::Character) {
240     if (auto len{DataRef{symbol}.LEN()}) {
241       LEN_ = std::move(*len);
242     }
243   }
244 }
245 
246 std::string TypeAndShape::AsFortran() const {
247   return type_.AsFortran(LEN_ ? LEN_->AsFortran() : "");
248 }
249 
250 llvm::raw_ostream &TypeAndShape::Dump(llvm::raw_ostream &o) const {
251   o << type_.AsFortran(LEN_ ? LEN_->AsFortran() : "");
252   attrs_.Dump(o, EnumToString);
253   if (!shape_.empty()) {
254     o << " dimension";
255     char sep{'('};
256     for (const auto &expr : shape_) {
257       o << sep;
258       sep = ',';
259       if (expr) {
260         expr->AsFortran(o);
261       } else {
262         o << ':';
263       }
264     }
265     o << ')';
266   }
267   return o;
268 }
269 
270 bool DummyDataObject::operator==(const DummyDataObject &that) const {
271   return type == that.type && attrs == that.attrs && intent == that.intent &&
272       coshape == that.coshape && cudaDataAttr == that.cudaDataAttr;
273   ;
274 }
275 
276 static bool AreCompatibleDummyDataObjectShapes(const Shape &x, const Shape &y) {
277   int n{GetRank(x)};
278   if (n != GetRank(y)) {
279     return false;
280   }
281   auto xIter{x.begin()};
282   auto yIter{y.begin()};
283   for (; n-- > 0; ++xIter, ++yIter) {
284     if (auto xVal{ToInt64(*xIter)}) {
285       if (auto yVal{ToInt64(*yIter)}) {
286         if (*xVal != *yVal) {
287           return false;
288         }
289       }
290     }
291   }
292   return true;
293 }
294 
295 bool DummyDataObject::IsCompatibleWith(
296     const DummyDataObject &actual, std::string *whyNot) const {
297   if (!AreCompatibleDummyDataObjectShapes(type.shape(), actual.type.shape())) {
298     if (whyNot) {
299       *whyNot = "incompatible dummy data object shapes";
300     }
301     return false;
302   }
303   if (!type.type().IsTkLenCompatibleWith(actual.type.type())) {
304     if (whyNot) {
305       *whyNot = "incompatible dummy data object types: "s +
306           type.type().AsFortran() + " vs " + actual.type.type().AsFortran();
307     }
308     return false;
309   }
310   if (type.type().IsPolymorphic() != actual.type.type().IsPolymorphic()) {
311     if (whyNot) {
312       *whyNot = "incompatible dummy data object polymorphism: "s +
313           type.type().AsFortran() + " vs " + actual.type.type().AsFortran();
314     }
315     return false;
316   }
317   if (type.type().category() == TypeCategory::Character) {
318     if (actual.type.type().IsAssumedLengthCharacter() !=
319         type.type().IsAssumedLengthCharacter()) {
320       if (whyNot) {
321         *whyNot = "assumed-length character vs explicit-length character";
322       }
323       return false;
324     }
325     if (!type.type().IsAssumedLengthCharacter() && type.LEN() &&
326         actual.type.LEN()) {
327       auto len{ToInt64(*type.LEN())};
328       auto actualLen{ToInt64(*actual.type.LEN())};
329       if (len.has_value() != actualLen.has_value()) {
330         if (whyNot) {
331           *whyNot = "constant-length vs non-constant-length character dummy "
332                     "arguments";
333         }
334         return false;
335       } else if (len && *len != *actualLen) {
336         if (whyNot) {
337           *whyNot = "character dummy arguments with distinct lengths";
338         }
339         return false;
340       }
341     }
342   }
343   if (!IdenticalSignificantAttrs(attrs, actual.attrs) ||
344       type.attrs() != actual.type.attrs()) {
345     if (whyNot) {
346       *whyNot = "incompatible dummy data object attributes";
347     }
348     return false;
349   }
350   if (intent != actual.intent) {
351     if (whyNot) {
352       *whyNot = "incompatible dummy data object intents";
353     }
354     return false;
355   }
356   if (coshape != actual.coshape) {
357     if (whyNot) {
358       *whyNot = "incompatible dummy data object coshapes";
359     }
360     return false;
361   }
362   if (ignoreTKR != actual.ignoreTKR) {
363     if (whyNot) {
364       *whyNot = "incompatible !DIR$ IGNORE_TKR directives";
365     }
366   }
367   if (!attrs.test(Attr::Value) &&
368       !common::AreCompatibleCUDADataAttrs(
369           cudaDataAttr, actual.cudaDataAttr, ignoreTKR)) {
370     if (whyNot) {
371       *whyNot = "incompatible CUDA data attributes";
372     }
373   }
374   return true;
375 }
376 
377 static common::Intent GetIntent(const semantics::Attrs &attrs) {
378   if (attrs.test(semantics::Attr::INTENT_IN)) {
379     return common::Intent::In;
380   } else if (attrs.test(semantics::Attr::INTENT_OUT)) {
381     return common::Intent::Out;
382   } else if (attrs.test(semantics::Attr::INTENT_INOUT)) {
383     return common::Intent::InOut;
384   } else {
385     return common::Intent::Default;
386   }
387 }
388 
389 std::optional<DummyDataObject> DummyDataObject::Characterize(
390     const semantics::Symbol &symbol, FoldingContext &context) {
391   if (const auto *object{symbol.detailsIf<semantics::ObjectEntityDetails>()};
392       object || symbol.has<semantics::EntityDetails>()) {
393     if (auto type{TypeAndShape::Characterize(
394             symbol, context, /*invariantOnly=*/false)}) {
395       std::optional<DummyDataObject> result{std::move(*type)};
396       using semantics::Attr;
397       CopyAttrs<DummyDataObject, DummyDataObject::Attr>(symbol, *result,
398           {
399               {Attr::OPTIONAL, DummyDataObject::Attr::Optional},
400               {Attr::ALLOCATABLE, DummyDataObject::Attr::Allocatable},
401               {Attr::ASYNCHRONOUS, DummyDataObject::Attr::Asynchronous},
402               {Attr::CONTIGUOUS, DummyDataObject::Attr::Contiguous},
403               {Attr::VALUE, DummyDataObject::Attr::Value},
404               {Attr::VOLATILE, DummyDataObject::Attr::Volatile},
405               {Attr::POINTER, DummyDataObject::Attr::Pointer},
406               {Attr::TARGET, DummyDataObject::Attr::Target},
407           });
408       result->intent = GetIntent(symbol.attrs());
409       result->ignoreTKR = GetIgnoreTKR(symbol);
410       if (object) {
411         result->cudaDataAttr = object->cudaDataAttr();
412         if (!result->cudaDataAttr &&
413             !result->attrs.test(DummyDataObject::Attr::Value) &&
414             semantics::IsCUDADeviceContext(&symbol.owner())) {
415           result->cudaDataAttr = common::CUDADataAttr::Device;
416         }
417       }
418       return result;
419     }
420   }
421   return std::nullopt;
422 }
423 
424 bool DummyDataObject::CanBePassedViaImplicitInterface() const {
425   if ((attrs &
426           Attrs{Attr::Allocatable, Attr::Asynchronous, Attr::Optional,
427               Attr::Pointer, Attr::Target, Attr::Value, Attr::Volatile})
428           .any()) {
429     return false; // 15.4.2.2(3)(a)
430   } else if ((type.attrs() &
431                  TypeAndShape::Attrs{TypeAndShape::Attr::AssumedShape,
432                      TypeAndShape::Attr::AssumedRank,
433                      TypeAndShape::Attr::Coarray})
434                  .any()) {
435     return false; // 15.4.2.2(3)(b-d)
436   } else if (type.type().IsPolymorphic()) {
437     return false; // 15.4.2.2(3)(f)
438   } else if (cudaDataAttr) {
439     return false;
440   } else if (const auto *derived{GetDerivedTypeSpec(type.type())}) {
441     return derived->parameters().empty(); // 15.4.2.2(3)(e)
442   } else {
443     return true;
444   }
445 }
446 
447 llvm::raw_ostream &DummyDataObject::Dump(llvm::raw_ostream &o) const {
448   attrs.Dump(o, EnumToString);
449   if (intent != common::Intent::Default) {
450     o << "INTENT(" << common::EnumToString(intent) << ')';
451   }
452   type.Dump(o);
453   if (!coshape.empty()) {
454     char sep{'['};
455     for (const auto &expr : coshape) {
456       expr.AsFortran(o << sep);
457       sep = ',';
458     }
459   }
460   if (cudaDataAttr) {
461     o << " cudaDataAttr: " << common::EnumToString(*cudaDataAttr);
462   }
463   if (!ignoreTKR.empty()) {
464     ignoreTKR.Dump(o << ' ', common::EnumToString);
465   }
466   return o;
467 }
468 
469 DummyProcedure::DummyProcedure(Procedure &&p)
470     : procedure{new Procedure{std::move(p)}} {}
471 
472 bool DummyProcedure::operator==(const DummyProcedure &that) const {
473   return attrs == that.attrs && intent == that.intent &&
474       procedure.value() == that.procedure.value();
475 }
476 
477 bool DummyProcedure::IsCompatibleWith(
478     const DummyProcedure &actual, std::string *whyNot) const {
479   if (attrs != actual.attrs) {
480     if (whyNot) {
481       *whyNot = "incompatible dummy procedure attributes";
482     }
483     return false;
484   }
485   if (intent != actual.intent) {
486     if (whyNot) {
487       *whyNot = "incompatible dummy procedure intents";
488     }
489     return false;
490   }
491   if (!procedure.value().IsCompatibleWith(actual.procedure.value(), whyNot)) {
492     if (whyNot) {
493       *whyNot = "incompatible dummy procedure interfaces: "s + *whyNot;
494     }
495     return false;
496   }
497   return true;
498 }
499 
500 bool DummyProcedure::CanBePassedViaImplicitInterface() const {
501   if ((attrs & Attrs{Attr::Optional, Attr::Pointer}).any()) {
502     return false; // 15.4.2.2(3)(a)
503   }
504   return true;
505 }
506 
507 static std::string GetSeenProcs(
508     const semantics::UnorderedSymbolSet &seenProcs) {
509   // Sort the symbols so that they appear in the same order on all platforms
510   auto ordered{semantics::OrderBySourcePosition(seenProcs)};
511   std::string result;
512   llvm::interleave(
513       ordered,
514       [&](const SymbolRef p) { result += '\'' + p->name().ToString() + '\''; },
515       [&]() { result += ", "; });
516   return result;
517 }
518 
519 // These functions with arguments of type UnorderedSymbolSet are used with
520 // mutually recursive calls when characterizing a Procedure, a DummyArgument,
521 // or a DummyProcedure to detect circularly defined procedures as required by
522 // 15.4.3.6, paragraph 2.
523 static std::optional<DummyArgument> CharacterizeDummyArgument(
524     const semantics::Symbol &symbol, FoldingContext &context,
525     semantics::UnorderedSymbolSet seenProcs);
526 static std::optional<FunctionResult> CharacterizeFunctionResult(
527     const semantics::Symbol &symbol, FoldingContext &context,
528     semantics::UnorderedSymbolSet seenProcs);
529 
530 static std::optional<Procedure> CharacterizeProcedure(
531     const semantics::Symbol &original, FoldingContext &context,
532     semantics::UnorderedSymbolSet seenProcs) {
533   const auto &symbol{ResolveAssociations(original)};
534   if (seenProcs.find(symbol) != seenProcs.end()) {
535     std::string procsList{GetSeenProcs(seenProcs)};
536     context.messages().Say(symbol.name(),
537         "Procedure '%s' is recursively defined.  Procedures in the cycle:"
538         " %s"_err_en_US,
539         symbol.name(), procsList);
540     return std::nullopt;
541   }
542   seenProcs.insert(symbol);
543   auto result{common::visit(
544       common::visitors{
545           [&](const semantics::SubprogramDetails &subp)
546               -> std::optional<Procedure> {
547             Procedure result;
548             if (subp.isFunction()) {
549               if (auto fr{CharacterizeFunctionResult(
550                       subp.result(), context, seenProcs)}) {
551                 result.functionResult = std::move(fr);
552               } else {
553                 return std::nullopt;
554               }
555             } else {
556               result.attrs.set(Procedure::Attr::Subroutine);
557             }
558             for (const semantics::Symbol *arg : subp.dummyArgs()) {
559               if (!arg) {
560                 if (subp.isFunction()) {
561                   return std::nullopt;
562                 } else {
563                   result.dummyArguments.emplace_back(AlternateReturn{});
564                 }
565               } else if (auto argCharacteristics{CharacterizeDummyArgument(
566                              *arg, context, seenProcs)}) {
567                 result.dummyArguments.emplace_back(
568                     std::move(argCharacteristics.value()));
569               } else {
570                 return std::nullopt;
571               }
572             }
573             result.cudaSubprogramAttrs = subp.cudaSubprogramAttrs();
574             return std::move(result);
575           },
576           [&](const semantics::ProcEntityDetails &proc)
577               -> std::optional<Procedure> {
578             if (symbol.attrs().test(semantics::Attr::INTRINSIC)) {
579               // Fails when the intrinsic is not a specific intrinsic function
580               // from F'2018 table 16.2.  In order to handle forward references,
581               // attempts to use impermissible intrinsic procedures as the
582               // interfaces of procedure pointers are caught and flagged in
583               // declaration checking in Semantics.
584               auto intrinsic{context.intrinsics().IsSpecificIntrinsicFunction(
585                   symbol.name().ToString())};
586               if (intrinsic && intrinsic->isRestrictedSpecific) {
587                 intrinsic.reset(); // Exclude intrinsics from table 16.3.
588               }
589               return intrinsic;
590             }
591             if (const semantics::Symbol *
592                 interfaceSymbol{proc.procInterface()}) {
593               auto result{
594                   CharacterizeProcedure(*interfaceSymbol, context, seenProcs)};
595               if (result && (IsDummy(symbol) || IsPointer(symbol))) {
596                 // Dummy procedures and procedure pointers may not be
597                 // ELEMENTAL, but we do accept the use of elemental intrinsic
598                 // functions as their interfaces.
599                 result->attrs.reset(Procedure::Attr::Elemental);
600               }
601               return result;
602             } else {
603               Procedure result;
604               result.attrs.set(Procedure::Attr::ImplicitInterface);
605               const semantics::DeclTypeSpec *type{proc.type()};
606               if (symbol.test(semantics::Symbol::Flag::Subroutine)) {
607                 // ignore any implicit typing
608                 result.attrs.set(Procedure::Attr::Subroutine);
609                 if (proc.isCUDAKernel()) {
610                   result.cudaSubprogramAttrs =
611                       common::CUDASubprogramAttrs::Global;
612                 }
613               } else if (type) {
614                 if (auto resultType{DynamicType::From(*type)}) {
615                   result.functionResult = FunctionResult{*resultType};
616                 } else {
617                   return std::nullopt;
618                 }
619               } else if (symbol.test(semantics::Symbol::Flag::Function)) {
620                 return std::nullopt;
621               }
622               // The PASS name, if any, is not a characteristic.
623               return std::move(result);
624             }
625           },
626           [&](const semantics::ProcBindingDetails &binding) {
627             if (auto result{CharacterizeProcedure(
628                     binding.symbol(), context, seenProcs)}) {
629               if (binding.symbol().attrs().test(semantics::Attr::INTRINSIC)) {
630                 result->attrs.reset(Procedure::Attr::Elemental);
631               }
632               if (!symbol.attrs().test(semantics::Attr::NOPASS)) {
633                 auto passName{binding.passName()};
634                 for (auto &dummy : result->dummyArguments) {
635                   if (!passName || dummy.name.c_str() == *passName) {
636                     dummy.pass = true;
637                     break;
638                   }
639                 }
640               }
641               return result;
642             } else {
643               return std::optional<Procedure>{};
644             }
645           },
646           [&](const semantics::UseDetails &use) {
647             return CharacterizeProcedure(use.symbol(), context, seenProcs);
648           },
649           [](const semantics::UseErrorDetails &) {
650             // Ambiguous use-association will be handled later during symbol
651             // checks, ignore UseErrorDetails here without actual symbol usage.
652             return std::optional<Procedure>{};
653           },
654           [&](const semantics::HostAssocDetails &assoc) {
655             return CharacterizeProcedure(assoc.symbol(), context, seenProcs);
656           },
657           [&](const semantics::GenericDetails &generic) {
658             if (const semantics::Symbol * specific{generic.specific()}) {
659               return CharacterizeProcedure(*specific, context, seenProcs);
660             } else {
661               return std::optional<Procedure>{};
662             }
663           },
664           [&](const semantics::EntityDetails &) {
665             context.messages().Say(
666                 "Procedure '%s' is referenced before being sufficiently defined in a context where it must be so"_err_en_US,
667                 symbol.name());
668             return std::optional<Procedure>{};
669           },
670           [&](const semantics::SubprogramNameDetails &) {
671             context.messages().Say(
672                 "Procedure '%s' is referenced before being sufficiently defined in a context where it must be so"_err_en_US,
673                 symbol.name());
674             return std::optional<Procedure>{};
675           },
676           [&](const auto &) {
677             context.messages().Say(
678                 "'%s' is not a procedure"_err_en_US, symbol.name());
679             return std::optional<Procedure>{};
680           },
681       },
682       symbol.details())};
683   if (result && !symbol.has<semantics::ProcBindingDetails>()) {
684     CopyAttrs<Procedure, Procedure::Attr>(symbol, *result,
685         {
686             {semantics::Attr::BIND_C, Procedure::Attr::BindC},
687         });
688     CopyAttrs<Procedure, Procedure::Attr>(DEREF(GetMainEntry(&symbol)), *result,
689         {
690             {semantics::Attr::ELEMENTAL, Procedure::Attr::Elemental},
691         });
692     if (IsPureProcedure(symbol) || // works for ENTRY too
693         (!IsExplicitlyImpureProcedure(symbol) &&
694             result->attrs.test(Procedure::Attr::Elemental))) {
695       result->attrs.set(Procedure::Attr::Pure);
696     }
697   }
698   return result;
699 }
700 
701 static std::optional<DummyProcedure> CharacterizeDummyProcedure(
702     const semantics::Symbol &symbol, FoldingContext &context,
703     semantics::UnorderedSymbolSet seenProcs) {
704   if (auto procedure{CharacterizeProcedure(symbol, context, seenProcs)}) {
705     // Dummy procedures may not be elemental.  Elemental dummy procedure
706     // interfaces are errors when the interface is not intrinsic, and that
707     // error is caught elsewhere.  Elemental intrinsic interfaces are
708     // made non-elemental.
709     procedure->attrs.reset(Procedure::Attr::Elemental);
710     DummyProcedure result{std::move(procedure.value())};
711     CopyAttrs<DummyProcedure, DummyProcedure::Attr>(symbol, result,
712         {
713             {semantics::Attr::OPTIONAL, DummyProcedure::Attr::Optional},
714             {semantics::Attr::POINTER, DummyProcedure::Attr::Pointer},
715         });
716     result.intent = GetIntent(symbol.attrs());
717     return result;
718   } else {
719     return std::nullopt;
720   }
721 }
722 
723 llvm::raw_ostream &DummyProcedure::Dump(llvm::raw_ostream &o) const {
724   attrs.Dump(o, EnumToString);
725   if (intent != common::Intent::Default) {
726     o << "INTENT(" << common::EnumToString(intent) << ')';
727   }
728   procedure.value().Dump(o);
729   return o;
730 }
731 
732 llvm::raw_ostream &AlternateReturn::Dump(llvm::raw_ostream &o) const {
733   return o << '*';
734 }
735 
736 DummyArgument::~DummyArgument() {}
737 
738 bool DummyArgument::operator==(const DummyArgument &that) const {
739   return u == that.u; // name and passed-object usage are not characteristics
740 }
741 
742 bool DummyArgument::IsCompatibleWith(
743     const DummyArgument &actual, std::string *whyNot) const {
744   if (const auto *ifaceData{std::get_if<DummyDataObject>(&u)}) {
745     if (const auto *actualData{std::get_if<DummyDataObject>(&actual.u)}) {
746       return ifaceData->IsCompatibleWith(*actualData, whyNot);
747     }
748     if (whyNot) {
749       *whyNot = "one dummy argument is an object, the other is not";
750     }
751   } else if (const auto *ifaceProc{std::get_if<DummyProcedure>(&u)}) {
752     if (const auto *actualProc{std::get_if<DummyProcedure>(&actual.u)}) {
753       return ifaceProc->IsCompatibleWith(*actualProc, whyNot);
754     }
755     if (whyNot) {
756       *whyNot = "one dummy argument is a procedure, the other is not";
757     }
758   } else {
759     CHECK(std::holds_alternative<AlternateReturn>(u));
760     if (std::holds_alternative<AlternateReturn>(actual.u)) {
761       return true;
762     }
763     if (whyNot) {
764       *whyNot = "one dummy argument is an alternate return, the other is not";
765     }
766   }
767   return false;
768 }
769 
770 static std::optional<DummyArgument> CharacterizeDummyArgument(
771     const semantics::Symbol &symbol, FoldingContext &context,
772     semantics::UnorderedSymbolSet seenProcs) {
773   auto name{symbol.name().ToString()};
774   if (symbol.has<semantics::ObjectEntityDetails>() ||
775       symbol.has<semantics::EntityDetails>()) {
776     if (auto obj{DummyDataObject::Characterize(symbol, context)}) {
777       return DummyArgument{std::move(name), std::move(obj.value())};
778     }
779   } else if (auto proc{
780                  CharacterizeDummyProcedure(symbol, context, seenProcs)}) {
781     return DummyArgument{std::move(name), std::move(proc.value())};
782   }
783   return std::nullopt;
784 }
785 
786 std::optional<DummyArgument> DummyArgument::FromActual(
787     std::string &&name, const Expr<SomeType> &expr, FoldingContext &context) {
788   return common::visit(
789       common::visitors{
790           [&](const BOZLiteralConstant &) {
791             DummyDataObject obj{
792                 TypeAndShape{DynamicType::TypelessIntrinsicArgument()}};
793             obj.attrs.set(DummyDataObject::Attr::DeducedFromActual);
794             return std::make_optional<DummyArgument>(
795                 std::move(name), std::move(obj));
796           },
797           [&](const NullPointer &) {
798             DummyDataObject obj{
799                 TypeAndShape{DynamicType::TypelessIntrinsicArgument()}};
800             obj.attrs.set(DummyDataObject::Attr::DeducedFromActual);
801             return std::make_optional<DummyArgument>(
802                 std::move(name), std::move(obj));
803           },
804           [&](const ProcedureDesignator &designator) {
805             if (auto proc{Procedure::Characterize(designator, context)}) {
806               return std::make_optional<DummyArgument>(
807                   std::move(name), DummyProcedure{std::move(*proc)});
808             } else {
809               return std::optional<DummyArgument>{};
810             }
811           },
812           [&](const ProcedureRef &call) {
813             if (auto proc{Procedure::Characterize(call, context)}) {
814               return std::make_optional<DummyArgument>(
815                   std::move(name), DummyProcedure{std::move(*proc)});
816             } else {
817               return std::optional<DummyArgument>{};
818             }
819           },
820           [&](const auto &) {
821             if (auto type{TypeAndShape::Characterize(expr, context)}) {
822               DummyDataObject obj{std::move(*type)};
823               obj.attrs.set(DummyDataObject::Attr::DeducedFromActual);
824               return std::make_optional<DummyArgument>(
825                   std::move(name), std::move(obj));
826             } else {
827               return std::optional<DummyArgument>{};
828             }
829           },
830       },
831       expr.u);
832 }
833 
834 std::optional<DummyArgument> DummyArgument::FromActual(
835     std::string &&name, const ActualArgument &arg, FoldingContext &context) {
836   if (const auto *expr{arg.UnwrapExpr()}) {
837     return FromActual(std::move(name), *expr, context);
838   } else if (arg.GetAssumedTypeDummy()) {
839     return std::nullopt;
840   } else {
841     return DummyArgument{AlternateReturn{}};
842   }
843 }
844 
845 bool DummyArgument::IsOptional() const {
846   return common::visit(
847       common::visitors{
848           [](const DummyDataObject &data) {
849             return data.attrs.test(DummyDataObject::Attr::Optional);
850           },
851           [](const DummyProcedure &proc) {
852             return proc.attrs.test(DummyProcedure::Attr::Optional);
853           },
854           [](const AlternateReturn &) { return false; },
855       },
856       u);
857 }
858 
859 void DummyArgument::SetOptional(bool value) {
860   common::visit(common::visitors{
861                     [value](DummyDataObject &data) {
862                       data.attrs.set(DummyDataObject::Attr::Optional, value);
863                     },
864                     [value](DummyProcedure &proc) {
865                       proc.attrs.set(DummyProcedure::Attr::Optional, value);
866                     },
867                     [](AlternateReturn &) { DIE("cannot set optional"); },
868                 },
869       u);
870 }
871 
872 void DummyArgument::SetIntent(common::Intent intent) {
873   common::visit(common::visitors{
874                     [intent](DummyDataObject &data) { data.intent = intent; },
875                     [intent](DummyProcedure &proc) { proc.intent = intent; },
876                     [](AlternateReturn &) { DIE("cannot set intent"); },
877                 },
878       u);
879 }
880 
881 common::Intent DummyArgument::GetIntent() const {
882   return common::visit(
883       common::visitors{
884           [](const DummyDataObject &data) { return data.intent; },
885           [](const DummyProcedure &proc) { return proc.intent; },
886           [](const AlternateReturn &) -> common::Intent {
887             DIE("Alternate returns have no intent");
888           },
889       },
890       u);
891 }
892 
893 bool DummyArgument::CanBePassedViaImplicitInterface() const {
894   if (const auto *object{std::get_if<DummyDataObject>(&u)}) {
895     return object->CanBePassedViaImplicitInterface();
896   } else if (const auto *proc{std::get_if<DummyProcedure>(&u)}) {
897     return proc->CanBePassedViaImplicitInterface();
898   } else {
899     return true;
900   }
901 }
902 
903 bool DummyArgument::IsTypelessIntrinsicDummy() const {
904   const auto *argObj{std::get_if<characteristics::DummyDataObject>(&u)};
905   return argObj && argObj->type.type().IsTypelessIntrinsicArgument();
906 }
907 
908 llvm::raw_ostream &DummyArgument::Dump(llvm::raw_ostream &o) const {
909   if (!name.empty()) {
910     o << name << '=';
911   }
912   if (pass) {
913     o << " PASS";
914   }
915   common::visit([&](const auto &x) { x.Dump(o); }, u);
916   return o;
917 }
918 
919 FunctionResult::FunctionResult(DynamicType t) : u{TypeAndShape{t}} {}
920 FunctionResult::FunctionResult(TypeAndShape &&t) : u{std::move(t)} {}
921 FunctionResult::FunctionResult(Procedure &&p) : u{std::move(p)} {}
922 FunctionResult::~FunctionResult() {}
923 
924 bool FunctionResult::operator==(const FunctionResult &that) const {
925   return attrs == that.attrs && cudaDataAttr == that.cudaDataAttr &&
926       u == that.u;
927 }
928 
929 static std::optional<FunctionResult> CharacterizeFunctionResult(
930     const semantics::Symbol &symbol, FoldingContext &context,
931     semantics::UnorderedSymbolSet seenProcs) {
932   if (const auto *object{symbol.detailsIf<semantics::ObjectEntityDetails>()}) {
933     if (auto type{TypeAndShape::Characterize(
934             symbol, context, /*invariantOnly=*/false)}) {
935       FunctionResult result{std::move(*type)};
936       CopyAttrs<FunctionResult, FunctionResult::Attr>(symbol, result,
937           {
938               {semantics::Attr::ALLOCATABLE, FunctionResult::Attr::Allocatable},
939               {semantics::Attr::CONTIGUOUS, FunctionResult::Attr::Contiguous},
940               {semantics::Attr::POINTER, FunctionResult::Attr::Pointer},
941           });
942       result.cudaDataAttr = object->cudaDataAttr();
943       return result;
944     }
945   } else if (auto maybeProc{
946                  CharacterizeProcedure(symbol, context, seenProcs)}) {
947     FunctionResult result{std::move(*maybeProc)};
948     result.attrs.set(FunctionResult::Attr::Pointer);
949     return result;
950   }
951   return std::nullopt;
952 }
953 
954 std::optional<FunctionResult> FunctionResult::Characterize(
955     const Symbol &symbol, FoldingContext &context) {
956   semantics::UnorderedSymbolSet seenProcs;
957   return CharacterizeFunctionResult(symbol, context, seenProcs);
958 }
959 
960 bool FunctionResult::IsAssumedLengthCharacter() const {
961   if (const auto *ts{std::get_if<TypeAndShape>(&u)}) {
962     return ts->type().IsAssumedLengthCharacter();
963   } else {
964     return false;
965   }
966 }
967 
968 bool FunctionResult::CanBeReturnedViaImplicitInterface() const {
969   if (attrs.test(Attr::Pointer) || attrs.test(Attr::Allocatable)) {
970     return false; // 15.4.2.2(4)(b)
971   } else if (cudaDataAttr) {
972     return false;
973   } else if (const auto *typeAndShape{GetTypeAndShape()}) {
974     if (typeAndShape->Rank() > 0) {
975       return false; // 15.4.2.2(4)(a)
976     } else {
977       const DynamicType &type{typeAndShape->type()};
978       switch (type.category()) {
979       case TypeCategory::Character:
980         if (type.knownLength()) {
981           return true;
982         } else if (const auto *param{type.charLengthParamValue()}) {
983           if (const auto &expr{param->GetExplicit()}) {
984             return IsConstantExpr(*expr); // 15.4.2.2(4)(c)
985           } else if (param->isAssumed()) {
986             return true;
987           }
988         }
989         return false;
990       case TypeCategory::Derived:
991         if (!type.IsPolymorphic()) {
992           const auto &spec{type.GetDerivedTypeSpec()};
993           for (const auto &pair : spec.parameters()) {
994             if (const auto &expr{pair.second.GetExplicit()}) {
995               if (!IsConstantExpr(*expr)) {
996                 return false; // 15.4.2.2(4)(c)
997               }
998             }
999           }
1000           return true;
1001         }
1002         return false;
1003       default:
1004         return true;
1005       }
1006     }
1007   } else {
1008     return false; // 15.4.2.2(4)(b) - procedure pointer
1009   }
1010 }
1011 
1012 static std::optional<std::string> AreIncompatibleFunctionResultShapes(
1013     const Shape &x, const Shape &y) {
1014   int rank{GetRank(x)};
1015   if (int yrank{GetRank(y)}; yrank != rank) {
1016     return "rank "s + std::to_string(rank) + " vs " + std::to_string(yrank);
1017   }
1018   for (int j{0}; j < rank; ++j) {
1019     if (x[j] && y[j] && !(*x[j] == *y[j])) {
1020       return x[j]->AsFortran() + " vs " + y[j]->AsFortran();
1021     }
1022   }
1023   return std::nullopt;
1024 }
1025 
1026 bool FunctionResult::IsCompatibleWith(
1027     const FunctionResult &actual, std::string *whyNot) const {
1028   Attrs actualAttrs{actual.attrs};
1029   if (!attrs.test(Attr::Contiguous)) {
1030     actualAttrs.reset(Attr::Contiguous);
1031   }
1032   if (attrs != actualAttrs) {
1033     if (whyNot) {
1034       *whyNot = "function results have incompatible attributes";
1035     }
1036   } else if (cudaDataAttr != actual.cudaDataAttr) {
1037     if (whyNot) {
1038       *whyNot = "function results have incompatible CUDA data attributes";
1039     }
1040   } else if (const auto *ifaceTypeShape{std::get_if<TypeAndShape>(&u)}) {
1041     if (const auto *actualTypeShape{std::get_if<TypeAndShape>(&actual.u)}) {
1042       std::optional<std::string> details;
1043       if (ifaceTypeShape->Rank() != actualTypeShape->Rank()) {
1044         if (whyNot) {
1045           *whyNot = "function results have distinct ranks";
1046         }
1047       } else if (!attrs.test(Attr::Allocatable) && !attrs.test(Attr::Pointer) &&
1048           (details = AreIncompatibleFunctionResultShapes(
1049                ifaceTypeShape->shape(), actualTypeShape->shape()))) {
1050         if (whyNot) {
1051           *whyNot = "function results have distinct extents (" + *details + ')';
1052         }
1053       } else if (ifaceTypeShape->type() != actualTypeShape->type()) {
1054         if (ifaceTypeShape->type().category() !=
1055             actualTypeShape->type().category()) {
1056         } else if (ifaceTypeShape->type().category() ==
1057             TypeCategory::Character) {
1058           if (ifaceTypeShape->type().kind() == actualTypeShape->type().kind()) {
1059             if (IsAssumedLengthCharacter() ||
1060                 actual.IsAssumedLengthCharacter()) {
1061               return true;
1062             } else {
1063               const auto *ifaceLenParam{
1064                   ifaceTypeShape->type().charLengthParamValue()};
1065               const auto *actualLenParam{
1066                   actualTypeShape->type().charLengthParamValue()};
1067               if (ifaceLenParam && actualLenParam &&
1068                   *ifaceLenParam == *actualLenParam) {
1069                 return true;
1070               }
1071             }
1072           }
1073         } else if (ifaceTypeShape->type().category() == TypeCategory::Derived) {
1074           if (ifaceTypeShape->type().IsPolymorphic() ==
1075                   actualTypeShape->type().IsPolymorphic() &&
1076               !ifaceTypeShape->type().IsUnlimitedPolymorphic() &&
1077               !actualTypeShape->type().IsUnlimitedPolymorphic() &&
1078               AreSameDerivedType(ifaceTypeShape->type().GetDerivedTypeSpec(),
1079                   actualTypeShape->type().GetDerivedTypeSpec())) {
1080             return true;
1081           }
1082         }
1083         if (whyNot) {
1084           *whyNot = "function results have distinct types: "s +
1085               ifaceTypeShape->type().AsFortran() + " vs "s +
1086               actualTypeShape->type().AsFortran();
1087         }
1088       } else {
1089         return true;
1090       }
1091     } else {
1092       if (whyNot) {
1093         *whyNot = "function result type and shape are not known";
1094       }
1095     }
1096   } else {
1097     const auto *ifaceProc{std::get_if<CopyableIndirection<Procedure>>(&u)};
1098     CHECK(ifaceProc != nullptr);
1099     if (const auto *actualProc{
1100             std::get_if<CopyableIndirection<Procedure>>(&actual.u)}) {
1101       if (ifaceProc->value().IsCompatibleWith(actualProc->value(), whyNot)) {
1102         return true;
1103       }
1104       if (whyNot) {
1105         *whyNot =
1106             "function results are incompatible procedure pointers: "s + *whyNot;
1107       }
1108     } else {
1109       if (whyNot) {
1110         *whyNot =
1111             "one function result is a procedure pointer, the other is not";
1112       }
1113     }
1114   }
1115   return false;
1116 }
1117 
1118 llvm::raw_ostream &FunctionResult::Dump(llvm::raw_ostream &o) const {
1119   attrs.Dump(o, EnumToString);
1120   common::visit(common::visitors{
1121                     [&](const TypeAndShape &ts) { ts.Dump(o); },
1122                     [&](const CopyableIndirection<Procedure> &p) {
1123                       p.value().Dump(o << " procedure(") << ')';
1124                     },
1125                 },
1126       u);
1127   if (cudaDataAttr) {
1128     o << " cudaDataAttr: " << common::EnumToString(*cudaDataAttr);
1129   }
1130   return o;
1131 }
1132 
1133 Procedure::Procedure(FunctionResult &&fr, DummyArguments &&args, Attrs a)
1134     : functionResult{std::move(fr)}, dummyArguments{std::move(args)}, attrs{a} {
1135 }
1136 Procedure::Procedure(DummyArguments &&args, Attrs a)
1137     : dummyArguments{std::move(args)}, attrs{a} {}
1138 Procedure::~Procedure() {}
1139 
1140 bool Procedure::operator==(const Procedure &that) const {
1141   return attrs == that.attrs && functionResult == that.functionResult &&
1142       dummyArguments == that.dummyArguments &&
1143       cudaSubprogramAttrs == that.cudaSubprogramAttrs;
1144 }
1145 
1146 bool Procedure::IsCompatibleWith(const Procedure &actual, std::string *whyNot,
1147     const SpecificIntrinsic *specificIntrinsic) const {
1148   // 15.5.2.9(1): if dummy is not pure, actual need not be.
1149   // Ditto with elemental.
1150   Attrs actualAttrs{actual.attrs};
1151   if (!attrs.test(Attr::Pure)) {
1152     actualAttrs.reset(Attr::Pure);
1153   }
1154   if (!attrs.test(Attr::Elemental) && specificIntrinsic) {
1155     actualAttrs.reset(Attr::Elemental);
1156   }
1157   Attrs differences{attrs ^ actualAttrs};
1158   differences.reset(Attr::Subroutine); // dealt with specifically later
1159   if (!differences.empty()) {
1160     if (whyNot) {
1161       auto sep{": "s};
1162       *whyNot = "incompatible procedure attributes";
1163       differences.IterateOverMembers([&](Attr x) {
1164         *whyNot += sep + std::string{EnumToString(x)};
1165         sep = ", ";
1166       });
1167     }
1168   } else if ((IsFunction() && actual.IsSubroutine()) ||
1169       (IsSubroutine() && actual.IsFunction())) {
1170     if (whyNot) {
1171       *whyNot =
1172           "incompatible procedures: one is a function, the other a subroutine";
1173     }
1174   } else if (functionResult && actual.functionResult &&
1175       !functionResult->IsCompatibleWith(*actual.functionResult, whyNot)) {
1176   } else if (cudaSubprogramAttrs != actual.cudaSubprogramAttrs) {
1177     if (whyNot) {
1178       *whyNot = "incompatible CUDA subprogram attributes";
1179     }
1180   } else if (dummyArguments.size() != actual.dummyArguments.size()) {
1181     if (whyNot) {
1182       *whyNot = "distinct numbers of dummy arguments";
1183     }
1184   } else {
1185     for (std::size_t j{0}; j < dummyArguments.size(); ++j) {
1186       // Subtlety: the dummy/actual distinction must be reversed for this
1187       // compatibility test in order to correctly check extended vs.
1188       // base types.  Example:
1189       //   subroutine s1(base); subroutine s2(extended)
1190       //   procedure(s1), pointer :: p
1191       //   p => s2 ! an error, s2 is more restricted, can't handle "base"
1192       if (!actual.dummyArguments[j].IsCompatibleWith(
1193               dummyArguments[j], whyNot)) {
1194         if (whyNot) {
1195           *whyNot = "incompatible dummy argument #"s + std::to_string(j + 1) +
1196               ": "s + *whyNot;
1197         }
1198         return false;
1199       }
1200     }
1201     return true;
1202   }
1203   return false;
1204 }
1205 
1206 int Procedure::FindPassIndex(std::optional<parser::CharBlock> name) const {
1207   int argCount{static_cast<int>(dummyArguments.size())};
1208   int index{0};
1209   if (name) {
1210     while (index < argCount && *name != dummyArguments[index].name.c_str()) {
1211       ++index;
1212     }
1213   }
1214   CHECK(index < argCount);
1215   return index;
1216 }
1217 
1218 bool Procedure::CanOverride(
1219     const Procedure &that, std::optional<int> passIndex) const {
1220   // A pure procedure may override an impure one (7.5.7.3(2))
1221   if ((that.attrs.test(Attr::Pure) && !attrs.test(Attr::Pure)) ||
1222       that.attrs.test(Attr::Elemental) != attrs.test(Attr::Elemental) ||
1223       functionResult != that.functionResult) {
1224     return false;
1225   }
1226   int argCount{static_cast<int>(dummyArguments.size())};
1227   if (argCount != static_cast<int>(that.dummyArguments.size())) {
1228     return false;
1229   }
1230   for (int j{0}; j < argCount; ++j) {
1231     if (passIndex && j == *passIndex) {
1232       if (!that.dummyArguments[j].IsCompatibleWith(dummyArguments[j])) {
1233         return false;
1234       }
1235     } else if (dummyArguments[j] != that.dummyArguments[j]) {
1236       return false;
1237     }
1238   }
1239   return true;
1240 }
1241 
1242 std::optional<Procedure> Procedure::Characterize(
1243     const semantics::Symbol &original, FoldingContext &context) {
1244   semantics::UnorderedSymbolSet seenProcs;
1245   return CharacterizeProcedure(original, context, seenProcs);
1246 }
1247 
1248 std::optional<Procedure> Procedure::Characterize(
1249     const ProcedureDesignator &proc, FoldingContext &context) {
1250   if (const auto *symbol{proc.GetSymbol()}) {
1251     if (auto result{
1252             characteristics::Procedure::Characterize(*symbol, context)}) {
1253       return result;
1254     }
1255   } else if (const auto *intrinsic{proc.GetSpecificIntrinsic()}) {
1256     return intrinsic->characteristics.value();
1257   }
1258   return std::nullopt;
1259 }
1260 
1261 std::optional<Procedure> Procedure::Characterize(
1262     const ProcedureRef &ref, FoldingContext &context) {
1263   if (auto callee{Characterize(ref.proc(), context)}) {
1264     if (callee->functionResult) {
1265       if (const Procedure *
1266           proc{callee->functionResult->IsProcedurePointer()}) {
1267         return {*proc};
1268       }
1269     }
1270   }
1271   return std::nullopt;
1272 }
1273 
1274 std::optional<Procedure> Procedure::Characterize(
1275     const Expr<SomeType> &expr, FoldingContext &context) {
1276   if (const auto *procRef{UnwrapProcedureRef(expr)}) {
1277     return Characterize(*procRef, context);
1278   } else if (const auto *procDesignator{
1279                  std::get_if<ProcedureDesignator>(&expr.u)}) {
1280     return Characterize(*procDesignator, context);
1281   } else if (const Symbol * symbol{UnwrapWholeSymbolOrComponentDataRef(expr)}) {
1282     return Characterize(*symbol, context);
1283   } else {
1284     context.messages().Say(
1285         "Expression '%s' is not a procedure"_err_en_US, expr.AsFortran());
1286     return std::nullopt;
1287   }
1288 }
1289 
1290 std::optional<Procedure> Procedure::FromActuals(const ProcedureDesignator &proc,
1291     const ActualArguments &args, FoldingContext &context) {
1292   auto callee{Characterize(proc, context)};
1293   if (callee) {
1294     if (callee->dummyArguments.empty() &&
1295         callee->attrs.test(Procedure::Attr::ImplicitInterface)) {
1296       int j{0};
1297       for (const auto &arg : args) {
1298         ++j;
1299         if (arg) {
1300           if (auto dummy{DummyArgument::FromActual(
1301                   "x"s + std::to_string(j), *arg, context)}) {
1302             callee->dummyArguments.emplace_back(std::move(*dummy));
1303             continue;
1304           }
1305         }
1306         callee.reset();
1307         break;
1308       }
1309     }
1310   }
1311   return callee;
1312 }
1313 
1314 bool Procedure::CanBeCalledViaImplicitInterface() const {
1315   // TODO: Pass back information on why we return false
1316   if (attrs.test(Attr::Elemental) || attrs.test(Attr::BindC)) {
1317     return false; // 15.4.2.2(5,6)
1318   } else if (cudaSubprogramAttrs &&
1319       *cudaSubprogramAttrs != common::CUDASubprogramAttrs::Host &&
1320       *cudaSubprogramAttrs != common::CUDASubprogramAttrs::Global) {
1321     return false;
1322   } else if (IsFunction() &&
1323       !functionResult->CanBeReturnedViaImplicitInterface()) {
1324     return false;
1325   } else {
1326     for (const DummyArgument &arg : dummyArguments) {
1327       if (!arg.CanBePassedViaImplicitInterface()) {
1328         return false;
1329       }
1330     }
1331     return true;
1332   }
1333 }
1334 
1335 llvm::raw_ostream &Procedure::Dump(llvm::raw_ostream &o) const {
1336   attrs.Dump(o, EnumToString);
1337   if (functionResult) {
1338     functionResult->Dump(o << "TYPE(") << ") FUNCTION";
1339   } else if (attrs.test(Attr::Subroutine)) {
1340     o << "SUBROUTINE";
1341   } else {
1342     o << "EXTERNAL";
1343   }
1344   char sep{'('};
1345   for (const auto &dummy : dummyArguments) {
1346     dummy.Dump(o << sep);
1347     sep = ',';
1348   }
1349   o << (sep == '(' ? "()" : ")");
1350   if (cudaSubprogramAttrs) {
1351     o << " cudaSubprogramAttrs: " << common::EnumToString(*cudaSubprogramAttrs);
1352   }
1353   return o;
1354 }
1355 
1356 // Utility class to determine if Procedures, etc. are distinguishable
1357 class DistinguishUtils {
1358 public:
1359   explicit DistinguishUtils(const common::LanguageFeatureControl &features)
1360       : features_{features} {}
1361 
1362   // Are these procedures distinguishable for a generic name?
1363   bool Distinguishable(const Procedure &, const Procedure &) const;
1364   // Are these procedures distinguishable for a generic operator or assignment?
1365   bool DistinguishableOpOrAssign(const Procedure &, const Procedure &) const;
1366 
1367 private:
1368   struct CountDummyProcedures {
1369     CountDummyProcedures(const DummyArguments &args) {
1370       for (const DummyArgument &arg : args) {
1371         if (std::holds_alternative<DummyProcedure>(arg.u)) {
1372           total += 1;
1373           notOptional += !arg.IsOptional();
1374         }
1375       }
1376     }
1377     int total{0};
1378     int notOptional{0};
1379   };
1380 
1381   bool Rule3Distinguishable(const Procedure &, const Procedure &) const;
1382   const DummyArgument *Rule1DistinguishingArg(
1383       const DummyArguments &, const DummyArguments &) const;
1384   int FindFirstToDistinguishByPosition(
1385       const DummyArguments &, const DummyArguments &) const;
1386   int FindLastToDistinguishByName(
1387       const DummyArguments &, const DummyArguments &) const;
1388   int CountCompatibleWith(const DummyArgument &, const DummyArguments &) const;
1389   int CountNotDistinguishableFrom(
1390       const DummyArgument &, const DummyArguments &) const;
1391   bool Distinguishable(const DummyArgument &, const DummyArgument &) const;
1392   bool Distinguishable(const DummyDataObject &, const DummyDataObject &) const;
1393   bool Distinguishable(const DummyProcedure &, const DummyProcedure &) const;
1394   bool Distinguishable(const FunctionResult &, const FunctionResult &) const;
1395   bool Distinguishable(
1396       const TypeAndShape &, const TypeAndShape &, common::IgnoreTKRSet) const;
1397   bool IsTkrCompatible(const DummyArgument &, const DummyArgument &) const;
1398   bool IsTkCompatible(const DummyDataObject &, const DummyDataObject &) const;
1399   const DummyArgument *GetAtEffectivePosition(
1400       const DummyArguments &, int) const;
1401   const DummyArgument *GetPassArg(const Procedure &) const;
1402 
1403   const common::LanguageFeatureControl &features_;
1404 };
1405 
1406 // Simpler distinguishability rules for operators and assignment
1407 bool DistinguishUtils::DistinguishableOpOrAssign(
1408     const Procedure &proc1, const Procedure &proc2) const {
1409   if ((proc1.IsFunction() && proc2.IsSubroutine()) ||
1410       (proc1.IsSubroutine() && proc2.IsFunction())) {
1411     return true;
1412   }
1413   auto &args1{proc1.dummyArguments};
1414   auto &args2{proc2.dummyArguments};
1415   if (args1.size() != args2.size()) {
1416     return true; // C1511: distinguishable based on number of arguments
1417   }
1418   for (std::size_t i{0}; i < args1.size(); ++i) {
1419     if (Distinguishable(args1[i], args2[i])) {
1420       return true; // C1511, C1512: distinguishable based on this arg
1421     }
1422   }
1423   return false;
1424 }
1425 
1426 bool DistinguishUtils::Distinguishable(
1427     const Procedure &proc1, const Procedure &proc2) const {
1428   if ((proc1.IsFunction() && proc2.IsSubroutine()) ||
1429       (proc1.IsSubroutine() && proc2.IsFunction())) {
1430     return true;
1431   }
1432   auto &args1{proc1.dummyArguments};
1433   auto &args2{proc2.dummyArguments};
1434   auto count1{CountDummyProcedures(args1)};
1435   auto count2{CountDummyProcedures(args2)};
1436   if (count1.notOptional > count2.total || count2.notOptional > count1.total) {
1437     return true; // distinguishable based on C1514 rule 2
1438   }
1439   if (Rule3Distinguishable(proc1, proc2)) {
1440     return true; // distinguishable based on C1514 rule 3
1441   }
1442   if (Rule1DistinguishingArg(args1, args2)) {
1443     return true; // distinguishable based on C1514 rule 1
1444   }
1445   int pos1{FindFirstToDistinguishByPosition(args1, args2)};
1446   int name1{FindLastToDistinguishByName(args1, args2)};
1447   if (pos1 >= 0 && pos1 <= name1) {
1448     return true; // distinguishable based on C1514 rule 4
1449   }
1450   int pos2{FindFirstToDistinguishByPosition(args2, args1)};
1451   int name2{FindLastToDistinguishByName(args2, args1)};
1452   if (pos2 >= 0 && pos2 <= name2) {
1453     return true; // distinguishable based on C1514 rule 4
1454   }
1455   if (proc1.cudaSubprogramAttrs != proc2.cudaSubprogramAttrs) {
1456     return true;
1457   }
1458   return false;
1459 }
1460 
1461 // C1514 rule 3: Procedures are distinguishable if both have a passed-object
1462 // dummy argument and those are distinguishable.
1463 bool DistinguishUtils::Rule3Distinguishable(
1464     const Procedure &proc1, const Procedure &proc2) const {
1465   const DummyArgument *pass1{GetPassArg(proc1)};
1466   const DummyArgument *pass2{GetPassArg(proc2)};
1467   return pass1 && pass2 && Distinguishable(*pass1, *pass2);
1468 }
1469 
1470 // Find a non-passed-object dummy data object in one of the argument lists
1471 // that satisfies C1514 rule 1. I.e. x such that:
1472 // - m is the number of dummy data objects in one that are nonoptional,
1473 //   are not passed-object, that x is TKR compatible with
1474 // - n is the number of non-passed-object dummy data objects, in the other
1475 //   that are not distinguishable from x
1476 // - m is greater than n
1477 const DummyArgument *DistinguishUtils::Rule1DistinguishingArg(
1478     const DummyArguments &args1, const DummyArguments &args2) const {
1479   auto size1{args1.size()};
1480   auto size2{args2.size()};
1481   for (std::size_t i{0}; i < size1 + size2; ++i) {
1482     const DummyArgument &x{i < size1 ? args1[i] : args2[i - size1]};
1483     if (!x.pass && std::holds_alternative<DummyDataObject>(x.u)) {
1484       if (CountCompatibleWith(x, args1) >
1485               CountNotDistinguishableFrom(x, args2) ||
1486           CountCompatibleWith(x, args2) >
1487               CountNotDistinguishableFrom(x, args1)) {
1488         return &x;
1489       }
1490     }
1491   }
1492   return nullptr;
1493 }
1494 
1495 // Find the index of the first nonoptional non-passed-object dummy argument
1496 // in args1 at an effective position such that either:
1497 // - args2 has no dummy argument at that effective position
1498 // - the dummy argument at that position is distinguishable from it
1499 int DistinguishUtils::FindFirstToDistinguishByPosition(
1500     const DummyArguments &args1, const DummyArguments &args2) const {
1501   int effective{0}; // position of arg1 in list, ignoring passed arg
1502   for (std::size_t i{0}; i < args1.size(); ++i) {
1503     const DummyArgument &arg1{args1.at(i)};
1504     if (!arg1.pass && !arg1.IsOptional()) {
1505       const DummyArgument *arg2{GetAtEffectivePosition(args2, effective)};
1506       if (!arg2 || Distinguishable(arg1, *arg2)) {
1507         return i;
1508       }
1509     }
1510     effective += !arg1.pass;
1511   }
1512   return -1;
1513 }
1514 
1515 // Find the index of the last nonoptional non-passed-object dummy argument
1516 // in args1 whose name is such that either:
1517 // - args2 has no dummy argument with that name
1518 // - the dummy argument with that name is distinguishable from it
1519 int DistinguishUtils::FindLastToDistinguishByName(
1520     const DummyArguments &args1, const DummyArguments &args2) const {
1521   std::map<std::string, const DummyArgument *> nameToArg;
1522   for (const auto &arg2 : args2) {
1523     nameToArg.emplace(arg2.name, &arg2);
1524   }
1525   for (int i = args1.size() - 1; i >= 0; --i) {
1526     const DummyArgument &arg1{args1.at(i)};
1527     if (!arg1.pass && !arg1.IsOptional()) {
1528       auto it{nameToArg.find(arg1.name)};
1529       if (it == nameToArg.end() || Distinguishable(arg1, *it->second)) {
1530         return i;
1531       }
1532     }
1533   }
1534   return -1;
1535 }
1536 
1537 // Count the dummy data objects in args that are nonoptional, are not
1538 // passed-object, and that x is TKR compatible with
1539 int DistinguishUtils::CountCompatibleWith(
1540     const DummyArgument &x, const DummyArguments &args) const {
1541   return llvm::count_if(args, [&](const DummyArgument &y) {
1542     return !y.pass && !y.IsOptional() && IsTkrCompatible(x, y);
1543   });
1544 }
1545 
1546 // Return the number of dummy data objects in args that are not
1547 // distinguishable from x and not passed-object.
1548 int DistinguishUtils::CountNotDistinguishableFrom(
1549     const DummyArgument &x, const DummyArguments &args) const {
1550   return llvm::count_if(args, [&](const DummyArgument &y) {
1551     return !y.pass && std::holds_alternative<DummyDataObject>(y.u) &&
1552         !Distinguishable(y, x);
1553   });
1554 }
1555 
1556 bool DistinguishUtils::Distinguishable(
1557     const DummyArgument &x, const DummyArgument &y) const {
1558   if (x.u.index() != y.u.index()) {
1559     return true; // different kind: data/proc/alt-return
1560   }
1561   return common::visit(
1562       common::visitors{
1563           [&](const DummyDataObject &z) {
1564             return Distinguishable(z, std::get<DummyDataObject>(y.u));
1565           },
1566           [&](const DummyProcedure &z) {
1567             return Distinguishable(z, std::get<DummyProcedure>(y.u));
1568           },
1569           [&](const AlternateReturn &) { return false; },
1570       },
1571       x.u);
1572 }
1573 
1574 bool DistinguishUtils::Distinguishable(
1575     const DummyDataObject &x, const DummyDataObject &y) const {
1576   using Attr = DummyDataObject::Attr;
1577   if (Distinguishable(x.type, y.type, x.ignoreTKR | y.ignoreTKR)) {
1578     return true;
1579   } else if (x.attrs.test(Attr::Allocatable) && y.attrs.test(Attr::Pointer) &&
1580       y.intent != common::Intent::In) {
1581     return true;
1582   } else if (y.attrs.test(Attr::Allocatable) && x.attrs.test(Attr::Pointer) &&
1583       x.intent != common::Intent::In) {
1584     return true;
1585   } else if (!common::AreCompatibleCUDADataAttrs(
1586                  x.cudaDataAttr, y.cudaDataAttr, x.ignoreTKR | y.ignoreTKR)) {
1587     return true;
1588   } else if (features_.IsEnabled(
1589                  common::LanguageFeature::DistinguishableSpecifics) &&
1590       (x.attrs.test(Attr::Allocatable) || x.attrs.test(Attr::Pointer)) &&
1591       (y.attrs.test(Attr::Allocatable) || y.attrs.test(Attr::Pointer)) &&
1592       (x.type.type().IsUnlimitedPolymorphic() !=
1593               y.type.type().IsUnlimitedPolymorphic() ||
1594           x.type.type().IsPolymorphic() != y.type.type().IsPolymorphic())) {
1595     // Extension: Per 15.5.2.5(2), an allocatable/pointer dummy and its
1596     // corresponding actual argument must both or neither be polymorphic,
1597     // and must both or neither be unlimited polymorphic.  So when exactly
1598     // one of two dummy arguments is polymorphic or unlimited polymorphic,
1599     // any actual argument that is admissible to one of them cannot also match
1600     // the other one.
1601     return true;
1602   } else {
1603     return false;
1604   }
1605 }
1606 
1607 bool DistinguishUtils::Distinguishable(
1608     const DummyProcedure &x, const DummyProcedure &y) const {
1609   const Procedure &xProc{x.procedure.value()};
1610   const Procedure &yProc{y.procedure.value()};
1611   if (Distinguishable(xProc, yProc)) {
1612     return true;
1613   } else {
1614     const std::optional<FunctionResult> &xResult{xProc.functionResult};
1615     const std::optional<FunctionResult> &yResult{yProc.functionResult};
1616     return xResult ? !yResult || Distinguishable(*xResult, *yResult)
1617                    : yResult.has_value();
1618   }
1619 }
1620 
1621 bool DistinguishUtils::Distinguishable(
1622     const FunctionResult &x, const FunctionResult &y) const {
1623   if (x.u.index() != y.u.index()) {
1624     return true; // one is data object, one is procedure
1625   }
1626   if (x.cudaDataAttr != y.cudaDataAttr) {
1627     return true;
1628   }
1629   return common::visit(
1630       common::visitors{
1631           [&](const TypeAndShape &z) {
1632             return Distinguishable(
1633                 z, std::get<TypeAndShape>(y.u), common::IgnoreTKRSet{});
1634           },
1635           [&](const CopyableIndirection<Procedure> &z) {
1636             return Distinguishable(z.value(),
1637                 std::get<CopyableIndirection<Procedure>>(y.u).value());
1638           },
1639       },
1640       x.u);
1641 }
1642 
1643 bool DistinguishUtils::Distinguishable(const TypeAndShape &x,
1644     const TypeAndShape &y, common::IgnoreTKRSet ignoreTKR) const {
1645   if (!x.type().IsTkCompatibleWith(y.type(), ignoreTKR) &&
1646       !y.type().IsTkCompatibleWith(x.type(), ignoreTKR)) {
1647     return true;
1648   }
1649   if (ignoreTKR.test(common::IgnoreTKR::Rank)) {
1650   } else if (x.attrs().test(TypeAndShape::Attr::AssumedRank) ||
1651       y.attrs().test(TypeAndShape::Attr::AssumedRank)) {
1652   } else if (x.Rank() != y.Rank()) {
1653     return true;
1654   }
1655   return false;
1656 }
1657 
1658 // Compatibility based on type, kind, and rank
1659 
1660 bool DistinguishUtils::IsTkrCompatible(
1661     const DummyArgument &x, const DummyArgument &y) const {
1662   const auto *obj1{std::get_if<DummyDataObject>(&x.u)};
1663   const auto *obj2{std::get_if<DummyDataObject>(&y.u)};
1664   return obj1 && obj2 && IsTkCompatible(*obj1, *obj2) &&
1665       (obj1->type.Rank() == obj2->type.Rank() ||
1666           obj1->type.attrs().test(TypeAndShape::Attr::AssumedRank) ||
1667           obj2->type.attrs().test(TypeAndShape::Attr::AssumedRank) ||
1668           obj1->ignoreTKR.test(common::IgnoreTKR::Rank) ||
1669           obj2->ignoreTKR.test(common::IgnoreTKR::Rank));
1670 }
1671 
1672 bool DistinguishUtils::IsTkCompatible(
1673     const DummyDataObject &x, const DummyDataObject &y) const {
1674   return x.type.type().IsTkCompatibleWith(
1675       y.type.type(), x.ignoreTKR | y.ignoreTKR);
1676 }
1677 
1678 // Return the argument at the given index, ignoring the passed arg
1679 const DummyArgument *DistinguishUtils::GetAtEffectivePosition(
1680     const DummyArguments &args, int index) const {
1681   for (const DummyArgument &arg : args) {
1682     if (!arg.pass) {
1683       if (index == 0) {
1684         return &arg;
1685       }
1686       --index;
1687     }
1688   }
1689   return nullptr;
1690 }
1691 
1692 // Return the passed-object dummy argument of this procedure, if any
1693 const DummyArgument *DistinguishUtils::GetPassArg(const Procedure &proc) const {
1694   for (const auto &arg : proc.dummyArguments) {
1695     if (arg.pass) {
1696       return &arg;
1697     }
1698   }
1699   return nullptr;
1700 }
1701 
1702 bool Distinguishable(const common::LanguageFeatureControl &features,
1703     const Procedure &x, const Procedure &y) {
1704   return DistinguishUtils{features}.Distinguishable(x, y);
1705 }
1706 
1707 bool DistinguishableOpOrAssign(const common::LanguageFeatureControl &features,
1708     const Procedure &x, const Procedure &y) {
1709   return DistinguishUtils{features}.DistinguishableOpOrAssign(x, y);
1710 }
1711 
1712 DEFINE_DEFAULT_CONSTRUCTORS_AND_ASSIGNMENTS(DummyArgument)
1713 DEFINE_DEFAULT_CONSTRUCTORS_AND_ASSIGNMENTS(DummyProcedure)
1714 DEFINE_DEFAULT_CONSTRUCTORS_AND_ASSIGNMENTS(FunctionResult)
1715 DEFINE_DEFAULT_CONSTRUCTORS_AND_ASSIGNMENTS(Procedure)
1716 } // namespace Fortran::evaluate::characteristics
1717 
1718 template class Fortran::common::Indirection<
1719     Fortran::evaluate::characteristics::Procedure, true>;
1720