xref: /llvm-project/flang/lib/Evaluate/check-expression.cpp (revision 67081badfc65b8b60622314dd698834ffcfdbfa9) 
1 //===-- lib/Evaluate/check-expression.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/check-expression.h"
10 #include "flang/Evaluate/characteristics.h"
11 #include "flang/Evaluate/intrinsics.h"
12 #include "flang/Evaluate/tools.h"
13 #include "flang/Evaluate/traverse.h"
14 #include "flang/Evaluate/type.h"
15 #include "flang/Semantics/semantics.h"
16 #include "flang/Semantics/symbol.h"
17 #include "flang/Semantics/tools.h"
18 #include <set>
19 #include <string>
20 
21 namespace Fortran::evaluate {
22 
23 // Constant expression predicates IsConstantExpr() & IsScopeInvariantExpr().
24 // This code determines whether an expression is a "constant expression"
25 // in the sense of section 10.1.12.  This is not the same thing as being
26 // able to fold it (yet) into a known constant value; specifically,
27 // the expression may reference derived type kind parameters whose values
28 // are not yet known.
29 //
30 // The variant form (IsScopeInvariantExpr()) also accepts symbols that are
31 // INTENT(IN) dummy arguments without the VALUE attribute.
32 template <bool INVARIANT>
33 class IsConstantExprHelper
34     : public AllTraverse<IsConstantExprHelper<INVARIANT>, true> {
35 public:
36   using Base = AllTraverse<IsConstantExprHelper, true>;
37   IsConstantExprHelper() : Base{*this} {}
38   using Base::operator();
39 
40   // A missing expression is not considered to be constant.
41   template <typename A> bool operator()(const std::optional<A> &x) const {
42     return x && (*this)(*x);
43   }
44 
45   bool operator()(const TypeParamInquiry &inq) const {
46     return INVARIANT || semantics::IsKindTypeParameter(inq.parameter());
47   }
48   bool operator()(const semantics::Symbol &symbol) const {
49     const auto &ultimate{GetAssociationRoot(symbol)};
50     return IsNamedConstant(ultimate) || IsImpliedDoIndex(ultimate) ||
51         IsInitialProcedureTarget(ultimate) ||
52         ultimate.has<semantics::TypeParamDetails>() ||
53         (INVARIANT && IsIntentIn(symbol) && !IsOptional(symbol) &&
54             !symbol.attrs().test(semantics::Attr::VALUE));
55   }
56   bool operator()(const CoarrayRef &) const { return false; }
57   bool operator()(const semantics::ParamValue &param) const {
58     return param.isExplicit() && (*this)(param.GetExplicit());
59   }
60   bool operator()(const ProcedureRef &) const;
61   bool operator()(const StructureConstructor &constructor) const {
62     for (const auto &[symRef, expr] : constructor) {
63       if (!IsConstantStructureConstructorComponent(*symRef, expr.value())) {
64         return false;
65       }
66     }
67     return true;
68   }
69   bool operator()(const Component &component) const {
70     return (*this)(component.base());
71   }
72   // Forbid integer division by zero in constants.
73   template <int KIND>
74   bool operator()(
75       const Divide<Type<TypeCategory::Integer, KIND>> &division) const {
76     using T = Type<TypeCategory::Integer, KIND>;
77     if (const auto divisor{GetScalarConstantValue<T>(division.right())}) {
78       return !divisor->IsZero() && (*this)(division.left());
79     } else {
80       return false;
81     }
82   }
83 
84   bool operator()(const Constant<SomeDerived> &) const { return true; }
85   bool operator()(const DescriptorInquiry &x) const {
86     const Symbol &sym{x.base().GetLastSymbol()};
87     return INVARIANT && !IsAllocatable(sym) &&
88         (!IsDummy(sym) ||
89             (IsIntentIn(sym) && !IsOptional(sym) &&
90                 !sym.attrs().test(semantics::Attr::VALUE)));
91   }
92 
93 private:
94   bool IsConstantStructureConstructorComponent(
95       const Symbol &, const Expr<SomeType> &) const;
96   bool IsConstantExprShape(const Shape &) const;
97 };
98 
99 template <bool INVARIANT>
100 bool IsConstantExprHelper<INVARIANT>::IsConstantStructureConstructorComponent(
101     const Symbol &component, const Expr<SomeType> &expr) const {
102   if (IsAllocatable(component)) {
103     return IsNullObjectPointer(expr);
104   } else if (IsPointer(component)) {
105     return IsNullPointer(expr) || IsInitialDataTarget(expr) ||
106         IsInitialProcedureTarget(expr);
107   } else {
108     return (*this)(expr);
109   }
110 }
111 
112 template <bool INVARIANT>
113 bool IsConstantExprHelper<INVARIANT>::operator()(
114     const ProcedureRef &call) const {
115   // LBOUND, UBOUND, and SIZE with truly constant DIM= arguments will have
116   // been rewritten into DescriptorInquiry operations.
117   if (const auto *intrinsic{std::get_if<SpecificIntrinsic>(&call.proc().u)}) {
118     const characteristics::Procedure &proc{intrinsic->characteristics.value()};
119     if (intrinsic->name == "kind" ||
120         intrinsic->name == IntrinsicProcTable::InvalidName ||
121         call.arguments().empty() || !call.arguments()[0]) {
122       // kind is always a constant, and we avoid cascading errors by considering
123       // invalid calls to intrinsics to be constant
124       return true;
125     } else if (intrinsic->name == "lbound") {
126       auto base{ExtractNamedEntity(call.arguments()[0]->UnwrapExpr())};
127       return base && IsConstantExprShape(GetLBOUNDs(*base));
128     } else if (intrinsic->name == "ubound") {
129       auto base{ExtractNamedEntity(call.arguments()[0]->UnwrapExpr())};
130       return base && IsConstantExprShape(GetUBOUNDs(*base));
131     } else if (intrinsic->name == "shape" || intrinsic->name == "size") {
132       auto shape{GetShape(call.arguments()[0]->UnwrapExpr())};
133       return shape && IsConstantExprShape(*shape);
134     } else if (proc.IsPure()) {
135       for (const auto &arg : call.arguments()) {
136         if (!arg) {
137           return false;
138         } else if (const auto *expr{arg->UnwrapExpr()};
139                    !expr || !(*this)(*expr)) {
140           return false;
141         }
142       }
143       return true;
144     }
145     // TODO: STORAGE_SIZE
146   }
147   return false;
148 }
149 
150 template <bool INVARIANT>
151 bool IsConstantExprHelper<INVARIANT>::IsConstantExprShape(
152     const Shape &shape) const {
153   for (const auto &extent : shape) {
154     if (!(*this)(extent)) {
155       return false;
156     }
157   }
158   return true;
159 }
160 
161 template <typename A> bool IsConstantExpr(const A &x) {
162   return IsConstantExprHelper<false>{}(x);
163 }
164 template bool IsConstantExpr(const Expr<SomeType> &);
165 template bool IsConstantExpr(const Expr<SomeInteger> &);
166 template bool IsConstantExpr(const Expr<SubscriptInteger> &);
167 template bool IsConstantExpr(const StructureConstructor &);
168 
169 // IsScopeInvariantExpr()
170 template <typename A> bool IsScopeInvariantExpr(const A &x) {
171   return IsConstantExprHelper<true>{}(x);
172 }
173 template bool IsScopeInvariantExpr(const Expr<SomeType> &);
174 template bool IsScopeInvariantExpr(const Expr<SomeInteger> &);
175 template bool IsScopeInvariantExpr(const Expr<SubscriptInteger> &);
176 
177 // IsActuallyConstant()
178 struct IsActuallyConstantHelper {
179   template <typename A> bool operator()(const A &) { return false; }
180   template <typename T> bool operator()(const Constant<T> &) { return true; }
181   template <typename T> bool operator()(const Parentheses<T> &x) {
182     return (*this)(x.left());
183   }
184   template <typename T> bool operator()(const Expr<T> &x) {
185     return common::visit([=](const auto &y) { return (*this)(y); }, x.u);
186   }
187   bool operator()(const Expr<SomeType> &x) {
188     return common::visit([this](const auto &y) { return (*this)(y); }, x.u);
189   }
190   bool operator()(const StructureConstructor &x) {
191     for (const auto &pair : x) {
192       const Expr<SomeType> &y{pair.second.value()};
193       const auto sym{pair.first};
194       const bool compIsConstant{(*this)(y)};
195       // If an allocatable component is initialized by a constant,
196       // the structure constructor is not a constant.
197       if ((!compIsConstant && !IsNullPointer(y)) ||
198           (compIsConstant && IsAllocatable(sym))) {
199         return false;
200       }
201     }
202     return true;
203   }
204   template <typename A> bool operator()(const A *x) { return x && (*this)(*x); }
205   template <typename A> bool operator()(const std::optional<A> &x) {
206     return x && (*this)(*x);
207   }
208 };
209 
210 template <typename A> bool IsActuallyConstant(const A &x) {
211   return IsActuallyConstantHelper{}(x);
212 }
213 
214 template bool IsActuallyConstant(const Expr<SomeType> &);
215 template bool IsActuallyConstant(const Expr<SomeInteger> &);
216 template bool IsActuallyConstant(const Expr<SubscriptInteger> &);
217 template bool IsActuallyConstant(const std::optional<Expr<SubscriptInteger>> &);
218 
219 // Object pointer initialization checking predicate IsInitialDataTarget().
220 // This code determines whether an expression is allowable as the static
221 // data address used to initialize a pointer with "=> x".  See C765.
222 class IsInitialDataTargetHelper
223     : public AllTraverse<IsInitialDataTargetHelper, true> {
224 public:
225   using Base = AllTraverse<IsInitialDataTargetHelper, true>;
226   using Base::operator();
227   explicit IsInitialDataTargetHelper(parser::ContextualMessages *m)
228       : Base{*this}, messages_{m} {}
229 
230   bool emittedMessage() const { return emittedMessage_; }
231 
232   bool operator()(const BOZLiteralConstant &) const { return false; }
233   bool operator()(const NullPointer &) const { return true; }
234   template <typename T> bool operator()(const Constant<T> &) const {
235     return false;
236   }
237   bool operator()(const semantics::Symbol &symbol) {
238     // This function checks only base symbols, not components.
239     const Symbol &ultimate{symbol.GetUltimate()};
240     if (const auto *assoc{
241             ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
242       if (const auto &expr{assoc->expr()}) {
243         if (IsVariable(*expr)) {
244           return (*this)(*expr);
245         } else if (messages_) {
246           messages_->Say(
247               "An initial data target may not be an associated expression ('%s')"_err_en_US,
248               ultimate.name());
249           emittedMessage_ = true;
250         }
251       }
252       return false;
253     } else if (!CheckVarOrComponent(ultimate)) {
254       return false;
255     } else if (!ultimate.attrs().test(semantics::Attr::TARGET)) {
256       if (messages_) {
257         messages_->Say(
258             "An initial data target may not be a reference to an object '%s' that lacks the TARGET attribute"_err_en_US,
259             ultimate.name());
260         emittedMessage_ = true;
261       }
262       return false;
263     } else if (!IsSaved(ultimate)) {
264       if (messages_) {
265         messages_->Say(
266             "An initial data target may not be a reference to an object '%s' that lacks the SAVE attribute"_err_en_US,
267             ultimate.name());
268         emittedMessage_ = true;
269       }
270       return false;
271     } else {
272       return true;
273     }
274   }
275   bool operator()(const StaticDataObject &) const { return false; }
276   bool operator()(const TypeParamInquiry &) const { return false; }
277   bool operator()(const Triplet &x) const {
278     return IsConstantExpr(x.lower()) && IsConstantExpr(x.upper()) &&
279         IsConstantExpr(x.stride());
280   }
281   bool operator()(const Subscript &x) const {
282     return common::visit(common::visitors{
283                              [&](const Triplet &t) { return (*this)(t); },
284                              [&](const auto &y) {
285                                return y.value().Rank() == 0 &&
286                                    IsConstantExpr(y.value());
287                              },
288                          },
289         x.u);
290   }
291   bool operator()(const CoarrayRef &) const { return false; }
292   bool operator()(const Component &x) {
293     return CheckVarOrComponent(x.GetLastSymbol()) && (*this)(x.base());
294   }
295   bool operator()(const Substring &x) const {
296     return IsConstantExpr(x.lower()) && IsConstantExpr(x.upper()) &&
297         (*this)(x.parent());
298   }
299   bool operator()(const DescriptorInquiry &) const { return false; }
300   template <typename T> bool operator()(const ArrayConstructor<T> &) const {
301     return false;
302   }
303   bool operator()(const StructureConstructor &) const { return false; }
304   template <typename D, typename R, typename... O>
305   bool operator()(const Operation<D, R, O...> &) const {
306     return false;
307   }
308   template <typename T> bool operator()(const Parentheses<T> &x) const {
309     return (*this)(x.left());
310   }
311   bool operator()(const ProcedureRef &x) const {
312     if (const SpecificIntrinsic * intrinsic{x.proc().GetSpecificIntrinsic()}) {
313       return intrinsic->characteristics.value().attrs.test(
314           characteristics::Procedure::Attr::NullPointer);
315     }
316     return false;
317   }
318   bool operator()(const Relational<SomeType> &) const { return false; }
319 
320 private:
321   bool CheckVarOrComponent(const semantics::Symbol &symbol) {
322     const Symbol &ultimate{symbol.GetUltimate()};
323     const char *unacceptable{nullptr};
324     if (ultimate.Corank() > 0) {
325       unacceptable = "a coarray";
326     } else if (IsAllocatable(ultimate)) {
327       unacceptable = "an ALLOCATABLE";
328     } else if (IsPointer(ultimate)) {
329       unacceptable = "a POINTER";
330     } else {
331       return true;
332     }
333     if (messages_) {
334       messages_->Say(
335           "An initial data target may not be a reference to %s '%s'"_err_en_US,
336           unacceptable, ultimate.name());
337       emittedMessage_ = true;
338     }
339     return false;
340   }
341 
342   parser::ContextualMessages *messages_;
343   bool emittedMessage_{false};
344 };
345 
346 bool IsInitialDataTarget(
347     const Expr<SomeType> &x, parser::ContextualMessages *messages) {
348   IsInitialDataTargetHelper helper{messages};
349   bool result{helper(x)};
350   if (!result && messages && !helper.emittedMessage()) {
351     messages->Say(
352         "An initial data target must be a designator with constant subscripts"_err_en_US);
353   }
354   return result;
355 }
356 
357 bool IsInitialProcedureTarget(const semantics::Symbol &symbol) {
358   const auto &ultimate{symbol.GetUltimate()};
359   return common::visit(
360       common::visitors{
361           [&](const semantics::SubprogramDetails &subp) {
362             return !subp.isDummy() && !subp.stmtFunction() &&
363                 symbol.owner().kind() != semantics::Scope::Kind::MainProgram &&
364                 symbol.owner().kind() != semantics::Scope::Kind::Subprogram;
365           },
366           [](const semantics::SubprogramNameDetails &x) {
367             return x.kind() != semantics::SubprogramKind::Internal;
368           },
369           [&](const semantics::ProcEntityDetails &proc) {
370             return !semantics::IsPointer(ultimate) && !proc.isDummy();
371           },
372           [](const auto &) { return false; },
373       },
374       ultimate.details());
375 }
376 
377 bool IsInitialProcedureTarget(const ProcedureDesignator &proc) {
378   if (const auto *intrin{proc.GetSpecificIntrinsic()}) {
379     return !intrin->isRestrictedSpecific;
380   } else if (proc.GetComponent()) {
381     return false;
382   } else {
383     return IsInitialProcedureTarget(DEREF(proc.GetSymbol()));
384   }
385 }
386 
387 bool IsInitialProcedureTarget(const Expr<SomeType> &expr) {
388   if (const auto *proc{std::get_if<ProcedureDesignator>(&expr.u)}) {
389     return IsInitialProcedureTarget(*proc);
390   } else {
391     return IsNullProcedurePointer(expr);
392   }
393 }
394 
395 // Converts, folds, and then checks type, rank, and shape of an
396 // initialization expression for a named constant, a non-pointer
397 // variable static initialization, a component default initializer,
398 // a type parameter default value, or instantiated type parameter value.
399 std::optional<Expr<SomeType>> NonPointerInitializationExpr(const Symbol &symbol,
400     Expr<SomeType> &&x, FoldingContext &context,
401     const semantics::Scope *instantiation) {
402   CHECK(!IsPointer(symbol));
403   if (auto symTS{
404           characteristics::TypeAndShape::Characterize(symbol, context)}) {
405     auto xType{x.GetType()};
406     auto converted{ConvertToType(symTS->type(), Expr<SomeType>{x})};
407     if (!converted &&
408         symbol.owner().context().IsEnabled(
409             common::LanguageFeature::LogicalIntegerAssignment)) {
410       converted = DataConstantConversionExtension(context, symTS->type(), x);
411       if (converted &&
412           symbol.owner().context().ShouldWarn(
413               common::LanguageFeature::LogicalIntegerAssignment)) {
414         context.messages().Say(
415             "nonstandard usage: initialization of %s with %s"_port_en_US,
416             symTS->type().AsFortran(), x.GetType().value().AsFortran());
417       }
418     }
419     if (converted) {
420       auto folded{Fold(context, std::move(*converted))};
421       if (IsActuallyConstant(folded)) {
422         int symRank{GetRank(symTS->shape())};
423         if (IsImpliedShape(symbol)) {
424           if (folded.Rank() == symRank) {
425             return ArrayConstantBoundChanger{
426                 std::move(*AsConstantExtents(
427                     context, GetRawLowerBounds(context, NamedEntity{symbol})))}
428                 .ChangeLbounds(std::move(folded));
429           } else {
430             context.messages().Say(
431                 "Implied-shape parameter '%s' has rank %d but its initializer has rank %d"_err_en_US,
432                 symbol.name(), symRank, folded.Rank());
433           }
434         } else if (auto extents{AsConstantExtents(context, symTS->shape())}) {
435           if (folded.Rank() == 0 && symRank == 0) {
436             // symbol and constant are both scalars
437             return {std::move(folded)};
438           } else if (folded.Rank() == 0 && symRank > 0) {
439             // expand the scalar constant to an array
440             return ScalarConstantExpander{std::move(*extents),
441                 AsConstantExtents(
442                     context, GetRawLowerBounds(context, NamedEntity{symbol}))}
443                 .Expand(std::move(folded));
444           } else if (auto resultShape{GetShape(context, folded)}) {
445             if (CheckConformance(context.messages(), symTS->shape(),
446                     *resultShape, CheckConformanceFlags::None,
447                     "initialized object", "initialization expression")
448                     .value_or(false /*fail if not known now to conform*/)) {
449               // make a constant array with adjusted lower bounds
450               return ArrayConstantBoundChanger{
451                   std::move(*AsConstantExtents(context,
452                       GetRawLowerBounds(context, NamedEntity{symbol})))}
453                   .ChangeLbounds(std::move(folded));
454             }
455           }
456         } else if (IsNamedConstant(symbol)) {
457           if (IsExplicitShape(symbol)) {
458             context.messages().Say(
459                 "Named constant '%s' array must have constant shape"_err_en_US,
460                 symbol.name());
461           } else {
462             // Declaration checking handles other cases
463           }
464         } else {
465           context.messages().Say(
466               "Shape of initialized object '%s' must be constant"_err_en_US,
467               symbol.name());
468         }
469       } else if (IsErrorExpr(folded)) {
470       } else if (IsLenTypeParameter(symbol)) {
471         return {std::move(folded)};
472       } else if (IsKindTypeParameter(symbol)) {
473         if (instantiation) {
474           context.messages().Say(
475               "Value of kind type parameter '%s' (%s) must be a scalar INTEGER constant"_err_en_US,
476               symbol.name(), folded.AsFortran());
477         } else {
478           return {std::move(folded)};
479         }
480       } else if (IsNamedConstant(symbol)) {
481         if (symbol.name() == "numeric_storage_size" &&
482             symbol.owner().IsModule() &&
483             DEREF(symbol.owner().symbol()).name() == "iso_fortran_env") {
484           // Very special case: numeric_storage_size is not folded until
485           // it read from the iso_fortran_env module file, as its value
486           // depends on compilation options.
487           return {std::move(folded)};
488         }
489         context.messages().Say(
490             "Value of named constant '%s' (%s) cannot be computed as a constant value"_err_en_US,
491             symbol.name(), folded.AsFortran());
492       } else {
493         context.messages().Say(
494             "Initialization expression for '%s' (%s) cannot be computed as a constant value"_err_en_US,
495             symbol.name(), folded.AsFortran());
496       }
497     } else if (xType) {
498       context.messages().Say(
499           "Initialization expression cannot be converted to declared type of '%s' from %s"_err_en_US,
500           symbol.name(), xType->AsFortran());
501     } else {
502       context.messages().Say(
503           "Initialization expression cannot be converted to declared type of '%s'"_err_en_US,
504           symbol.name());
505     }
506   }
507   return std::nullopt;
508 }
509 
510 // Specification expression validation (10.1.11(2), C1010)
511 class CheckSpecificationExprHelper
512     : public AnyTraverse<CheckSpecificationExprHelper,
513           std::optional<std::string>> {
514 public:
515   using Result = std::optional<std::string>;
516   using Base = AnyTraverse<CheckSpecificationExprHelper, Result>;
517   explicit CheckSpecificationExprHelper(const semantics::Scope &s,
518       FoldingContext &context, bool forElementalFunctionResult)
519       : Base{*this}, scope_{s}, context_{context},
520         forElementalFunctionResult_{forElementalFunctionResult} {}
521   using Base::operator();
522 
523   Result operator()(const CoarrayRef &) const { return "coindexed reference"; }
524 
525   Result operator()(const semantics::Symbol &symbol) const {
526     const auto &ultimate{symbol.GetUltimate()};
527     if (const auto *assoc{
528             ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
529       return (*this)(assoc->expr());
530     } else if (semantics::IsNamedConstant(ultimate) ||
531         ultimate.owner().IsModule() || ultimate.owner().IsSubmodule()) {
532       return std::nullopt;
533     } else if (scope_.IsDerivedType() &&
534         IsVariableName(ultimate)) { // C750, C754
535       return "derived type component or type parameter value not allowed to "
536              "reference variable '"s +
537           ultimate.name().ToString() + "'";
538     } else if (IsDummy(ultimate)) {
539       if (!inInquiry_ && forElementalFunctionResult_) {
540         return "dependence on value of dummy argument '"s +
541             ultimate.name().ToString() + "'";
542       } else if (ultimate.attrs().test(semantics::Attr::OPTIONAL)) {
543         return "reference to OPTIONAL dummy argument '"s +
544             ultimate.name().ToString() + "'";
545       } else if (!inInquiry_ &&
546           ultimate.attrs().test(semantics::Attr::INTENT_OUT)) {
547         return "reference to INTENT(OUT) dummy argument '"s +
548             ultimate.name().ToString() + "'";
549       } else if (ultimate.has<semantics::ObjectEntityDetails>()) {
550         return std::nullopt;
551       } else {
552         return "dummy procedure argument";
553       }
554     } else if (&symbol.owner() != &scope_ || &ultimate.owner() != &scope_) {
555       return std::nullopt; // host association is in play
556     } else if (const auto *object{
557                    ultimate.detailsIf<semantics::ObjectEntityDetails>()}) {
558       if (object->commonBlock()) {
559         return std::nullopt;
560       }
561     }
562     if (inInquiry_) {
563       return std::nullopt;
564     } else {
565       return "reference to local entity '"s + ultimate.name().ToString() + "'";
566     }
567   }
568 
569   Result operator()(const Component &x) const {
570     // Don't look at the component symbol.
571     return (*this)(x.base());
572   }
573   Result operator()(const ArrayRef &x) const {
574     if (auto result{(*this)(x.base())}) {
575       return result;
576     }
577     // The subscripts don't get special protection for being in a
578     // specification inquiry context;
579     auto restorer{common::ScopedSet(inInquiry_, false)};
580     return (*this)(x.subscript());
581   }
582   Result operator()(const Substring &x) const {
583     if (auto result{(*this)(x.parent())}) {
584       return result;
585     }
586     // The bounds don't get special protection for being in a
587     // specification inquiry context;
588     auto restorer{common::ScopedSet(inInquiry_, false)};
589     if (auto result{(*this)(x.lower())}) {
590       return result;
591     }
592     return (*this)(x.upper());
593   }
594   Result operator()(const DescriptorInquiry &x) const {
595     // Many uses of SIZE(), LBOUND(), &c. that are valid in specification
596     // expressions will have been converted to expressions over descriptor
597     // inquiries by Fold().
598     // Catch REAL, ALLOCATABLE :: X(:); REAL :: Y(SIZE(X))
599     if (IsPermissibleInquiry(
600             x.base().GetFirstSymbol(), x.base().GetLastSymbol(), x.field())) {
601       auto restorer{common::ScopedSet(inInquiry_, true)};
602       return (*this)(x.base());
603     } else if (IsConstantExpr(x)) {
604       return std::nullopt;
605     } else {
606       return "non-constant descriptor inquiry not allowed for local object";
607     }
608   }
609 
610   Result operator()(const TypeParamInquiry &inq) const {
611     if (scope_.IsDerivedType()) {
612       if (!IsConstantExpr(inq) &&
613           inq.base() /* X%T, not local T */) { // C750, C754
614         return "non-constant reference to a type parameter inquiry not allowed "
615                "for derived type components or type parameter values";
616       }
617     } else if (inq.base() &&
618         IsInquiryAlwaysPermissible(inq.base()->GetFirstSymbol())) {
619       auto restorer{common::ScopedSet(inInquiry_, true)};
620       return (*this)(inq.base());
621     } else if (!IsConstantExpr(inq)) {
622       return "non-constant type parameter inquiry not allowed for local object";
623     }
624     return std::nullopt;
625   }
626 
627   Result operator()(const ProcedureRef &x) const {
628     bool inInquiry{false};
629     if (const auto *symbol{x.proc().GetSymbol()}) {
630       const Symbol &ultimate{symbol->GetUltimate()};
631       if (!semantics::IsPureProcedure(ultimate)) {
632         return "reference to impure function '"s + ultimate.name().ToString() +
633             "'";
634       }
635       if (semantics::IsStmtFunction(ultimate)) {
636         return "reference to statement function '"s +
637             ultimate.name().ToString() + "'";
638       }
639       if (scope_.IsDerivedType()) { // C750, C754
640         return "reference to function '"s + ultimate.name().ToString() +
641             "' not allowed for derived type components or type parameter"
642             " values";
643       }
644       if (auto procChars{characteristics::Procedure::Characterize(
645               x.proc(), context_, /*emitError=*/true)}) {
646         const auto iter{std::find_if(procChars->dummyArguments.begin(),
647             procChars->dummyArguments.end(),
648             [](const characteristics::DummyArgument &dummy) {
649               return std::holds_alternative<characteristics::DummyProcedure>(
650                   dummy.u);
651             })};
652         if (iter != procChars->dummyArguments.end()) {
653           return "reference to function '"s + ultimate.name().ToString() +
654               "' with dummy procedure argument '" + iter->name + '\'';
655         }
656       }
657       // References to internal functions are caught in expression semantics.
658       // TODO: other checks for standard module procedures
659     } else { // intrinsic
660       const SpecificIntrinsic &intrin{DEREF(x.proc().GetSpecificIntrinsic())};
661       inInquiry = context_.intrinsics().GetIntrinsicClass(intrin.name) ==
662           IntrinsicClass::inquiryFunction;
663       if (scope_.IsDerivedType()) { // C750, C754
664         if ((context_.intrinsics().IsIntrinsic(intrin.name) &&
665                 badIntrinsicsForComponents_.find(intrin.name) !=
666                     badIntrinsicsForComponents_.end())) {
667           return "reference to intrinsic '"s + intrin.name +
668               "' not allowed for derived type components or type parameter"
669               " values";
670         }
671         if (inInquiry && !IsConstantExpr(x)) {
672           return "non-constant reference to inquiry intrinsic '"s +
673               intrin.name +
674               "' not allowed for derived type components or type"
675               " parameter values";
676         }
677       }
678       // Type-determined inquiries (DIGITS, HUGE, &c.) will have already been
679       // folded and won't arrive here.  Inquiries that are represented with
680       // DescriptorInquiry operations (LBOUND) are checked elsewhere.  If a
681       // call that makes it to here satisfies the requirements of a constant
682       // expression (as Fortran defines it), it's fine.
683       if (IsConstantExpr(x)) {
684         return std::nullopt;
685       }
686       if (intrin.name == "present") {
687         return std::nullopt; // always ok
688       }
689       // Catch CHARACTER(:), ALLOCATABLE :: X; CHARACTER(LEN(X)) :: Y
690       if (inInquiry && x.arguments().size() >= 1) {
691         if (const auto &arg{x.arguments().at(0)}) {
692           if (auto dataRef{ExtractDataRef(*arg, true, true)}) {
693             if (intrin.name == "allocated" || intrin.name == "associated" ||
694                 intrin.name == "is_contiguous") { // ok
695             } else if (intrin.name == "len" &&
696                 IsPermissibleInquiry(dataRef->GetFirstSymbol(),
697                     dataRef->GetLastSymbol(),
698                     DescriptorInquiry::Field::Len)) { // ok
699             } else if (intrin.name == "lbound" &&
700                 IsPermissibleInquiry(dataRef->GetFirstSymbol(),
701                     dataRef->GetLastSymbol(),
702                     DescriptorInquiry::Field::LowerBound)) { // ok
703             } else if ((intrin.name == "shape" || intrin.name == "size" ||
704                            intrin.name == "sizeof" ||
705                            intrin.name == "storage_size" ||
706                            intrin.name == "ubound") &&
707                 IsPermissibleInquiry(dataRef->GetFirstSymbol(),
708                     dataRef->GetLastSymbol(),
709                     DescriptorInquiry::Field::Extent)) { // ok
710             } else {
711               return "non-constant inquiry function '"s + intrin.name +
712                   "' not allowed for local object";
713             }
714           }
715         }
716       }
717     }
718     auto restorer{common::ScopedSet(inInquiry_, inInquiry)};
719     return (*this)(x.arguments());
720   }
721 
722 private:
723   const semantics::Scope &scope_;
724   FoldingContext &context_;
725   // Contextual information: this flag is true when in an argument to
726   // an inquiry intrinsic like SIZE().
727   mutable bool inInquiry_{false};
728   bool forElementalFunctionResult_{false}; // F'2023 C15121
729   const std::set<std::string> badIntrinsicsForComponents_{
730       "allocated", "associated", "extends_type_of", "present", "same_type_as"};
731 
732   bool IsInquiryAlwaysPermissible(const semantics::Symbol &) const;
733   bool IsPermissibleInquiry(const semantics::Symbol &firstSymbol,
734       const semantics::Symbol &lastSymbol,
735       DescriptorInquiry::Field field) const;
736 };
737 
738 bool CheckSpecificationExprHelper::IsInquiryAlwaysPermissible(
739     const semantics::Symbol &symbol) const {
740   if (&symbol.owner() != &scope_ || symbol.has<semantics::UseDetails>() ||
741       symbol.owner().kind() == semantics::Scope::Kind::Module ||
742       semantics::FindCommonBlockContaining(symbol) ||
743       symbol.has<semantics::HostAssocDetails>()) {
744     return true; // it's nonlocal
745   } else if (semantics::IsDummy(symbol) && !forElementalFunctionResult_) {
746     return true;
747   } else {
748     return false;
749   }
750 }
751 
752 bool CheckSpecificationExprHelper::IsPermissibleInquiry(
753     const semantics::Symbol &firstSymbol, const semantics::Symbol &lastSymbol,
754     DescriptorInquiry::Field field) const {
755   if (IsInquiryAlwaysPermissible(firstSymbol)) {
756     return true;
757   }
758   // Inquiries on local objects may not access a deferred bound or length.
759   // (This code used to be a switch, but it proved impossible to write it
760   // thus without running afoul of bogus warnings from different C++
761   // compilers.)
762   if (field == DescriptorInquiry::Field::Rank) {
763     return true; // always known
764   }
765   const auto *object{lastSymbol.detailsIf<semantics::ObjectEntityDetails>()};
766   if (field == DescriptorInquiry::Field::LowerBound ||
767       field == DescriptorInquiry::Field::Extent ||
768       field == DescriptorInquiry::Field::Stride) {
769     return object && !object->shape().CanBeDeferredShape();
770   }
771   if (field == DescriptorInquiry::Field::Len) {
772     return object && object->type() &&
773         object->type()->category() == semantics::DeclTypeSpec::Character &&
774         !object->type()->characterTypeSpec().length().isDeferred();
775   }
776   return false;
777 }
778 
779 template <typename A>
780 void CheckSpecificationExpr(const A &x, const semantics::Scope &scope,
781     FoldingContext &context, bool forElementalFunctionResult) {
782   if (auto why{CheckSpecificationExprHelper{
783           scope, context, forElementalFunctionResult}(x)}) {
784     context.messages().Say("Invalid specification expression%s: %s"_err_en_US,
785         forElementalFunctionResult ? " for elemental function result" : "",
786         *why);
787   }
788 }
789 
790 template void CheckSpecificationExpr(const Expr<SomeType> &,
791     const semantics::Scope &, FoldingContext &,
792     bool forElementalFunctionResult);
793 template void CheckSpecificationExpr(const Expr<SomeInteger> &,
794     const semantics::Scope &, FoldingContext &,
795     bool forElementalFunctionResult);
796 template void CheckSpecificationExpr(const Expr<SubscriptInteger> &,
797     const semantics::Scope &, FoldingContext &,
798     bool forElementalFunctionResult);
799 template void CheckSpecificationExpr(const std::optional<Expr<SomeType>> &,
800     const semantics::Scope &, FoldingContext &,
801     bool forElementalFunctionResult);
802 template void CheckSpecificationExpr(const std::optional<Expr<SomeInteger>> &,
803     const semantics::Scope &, FoldingContext &,
804     bool forElementalFunctionResult);
805 template void CheckSpecificationExpr(
806     const std::optional<Expr<SubscriptInteger>> &, const semantics::Scope &,
807     FoldingContext &, bool forElementalFunctionResult);
808 
809 // IsContiguous() -- 9.5.4
810 class IsContiguousHelper
811     : public AnyTraverse<IsContiguousHelper, std::optional<bool>> {
812 public:
813   using Result = std::optional<bool>; // tri-state
814   using Base = AnyTraverse<IsContiguousHelper, Result>;
815   explicit IsContiguousHelper(FoldingContext &c) : Base{*this}, context_{c} {}
816   using Base::operator();
817 
818   template <typename T> Result operator()(const Constant<T> &) const {
819     return true;
820   }
821   Result operator()(const StaticDataObject &) const { return true; }
822   Result operator()(const semantics::Symbol &symbol) const {
823     const auto &ultimate{symbol.GetUltimate()};
824     if (ultimate.attrs().test(semantics::Attr::CONTIGUOUS)) {
825       return true;
826     } else if (!IsVariable(symbol)) {
827       return true;
828     } else if (ultimate.Rank() == 0) {
829       // Extension: accept scalars as a degenerate case of
830       // simple contiguity to allow their use in contexts like
831       // data targets in pointer assignments with remapping.
832       return true;
833     } else if (const auto *details{
834                    ultimate.detailsIf<semantics::AssocEntityDetails>()}) {
835       // RANK(*) associating entity is contiguous.
836       if (details->IsAssumedSize()) {
837         return true;
838       } else {
839         return Base::operator()(ultimate); // use expr
840       }
841     } else if (semantics::IsPointer(ultimate) ||
842         semantics::IsAssumedShape(ultimate) || IsAssumedRank(ultimate)) {
843       return std::nullopt;
844     } else if (ultimate.has<semantics::ObjectEntityDetails>()) {
845       return true;
846     } else {
847       return Base::operator()(ultimate);
848     }
849   }
850 
851   Result operator()(const ArrayRef &x) const {
852     if (x.Rank() == 0) {
853       return true; // scalars considered contiguous
854     }
855     int subscriptRank{0};
856     auto baseLbounds{GetLBOUNDs(context_, x.base())};
857     auto baseUbounds{GetUBOUNDs(context_, x.base())};
858     auto subscripts{CheckSubscripts(
859         x.subscript(), subscriptRank, &baseLbounds, &baseUbounds)};
860     if (!subscripts.value_or(false)) {
861       return subscripts; // subscripts not known to be contiguous
862     } else if (subscriptRank > 0) {
863       // a(1)%b(:,:) is contiguous if and only if a(1)%b is contiguous.
864       return (*this)(x.base());
865     } else {
866       // a(:)%b(1,1) is (probably) not contiguous.
867       return std::nullopt;
868     }
869   }
870   Result operator()(const CoarrayRef &x) const {
871     int rank{0};
872     return CheckSubscripts(x.subscript(), rank).has_value();
873   }
874   Result operator()(const Component &x) const {
875     if (x.base().Rank() == 0) {
876       return (*this)(x.GetLastSymbol());
877     } else {
878       if (Result baseIsContiguous{(*this)(x.base())}) {
879         if (!*baseIsContiguous) {
880           return false;
881         }
882         // TODO could be true if base contiguous and this is only component, or
883         // if base has only one element?
884       }
885       return std::nullopt;
886     }
887   }
888   Result operator()(const ComplexPart &x) const {
889     return x.complex().Rank() == 0;
890   }
891   Result operator()(const Substring &) const { return std::nullopt; }
892 
893   Result operator()(const ProcedureRef &x) const {
894     if (auto chars{characteristics::Procedure::Characterize(
895             x.proc(), context_, /*emitError=*/true)}) {
896       if (chars->functionResult) {
897         const auto &result{*chars->functionResult};
898         if (!result.IsProcedurePointer()) {
899           if (result.attrs.test(
900                   characteristics::FunctionResult::Attr::Contiguous)) {
901             return true;
902           }
903           if (!result.attrs.test(
904                   characteristics::FunctionResult::Attr::Pointer)) {
905             return true;
906           }
907           if (const auto *type{result.GetTypeAndShape()};
908               type && type->Rank() == 0) {
909             return true; // pointer to scalar
910           }
911           // Must be non-CONTIGUOUS pointer to array
912         }
913       }
914     }
915     return std::nullopt;
916   }
917 
918   Result operator()(const NullPointer &) const { return true; }
919 
920 private:
921   // Returns "true" for a provably empty or simply contiguous array section;
922   // return "false" for a provably nonempty discontiguous section or for use
923   // of a vector subscript.
924   std::optional<bool> CheckSubscripts(const std::vector<Subscript> &subscript,
925       int &rank, const Shape *baseLbounds = nullptr,
926       const Shape *baseUbounds = nullptr) const {
927     bool anyTriplet{false};
928     rank = 0;
929     // Detect any provably empty dimension in this array section, which would
930     // render the whole section empty and therefore vacuously contiguous.
931     std::optional<bool> result;
932     bool mayBeEmpty{false};
933     auto dims{subscript.size()};
934     std::vector<bool> knownPartialSlice(dims, false);
935     for (auto j{dims}; j-- > 0;) {
936       std::optional<ConstantSubscript> dimLbound;
937       std::optional<ConstantSubscript> dimUbound;
938       std::optional<ConstantSubscript> dimExtent;
939       if (baseLbounds && j < baseLbounds->size()) {
940         if (const auto &lb{baseLbounds->at(j)}) {
941           dimLbound = ToInt64(Fold(context_, Expr<SubscriptInteger>{*lb}));
942         }
943       }
944       if (baseUbounds && j < baseUbounds->size()) {
945         if (const auto &ub{baseUbounds->at(j)}) {
946           dimUbound = ToInt64(Fold(context_, Expr<SubscriptInteger>{*ub}));
947         }
948       }
949       if (dimLbound && dimUbound) {
950         if (*dimLbound <= *dimUbound) {
951           dimExtent = *dimUbound - *dimLbound + 1;
952         } else {
953           // This is an empty dimension.
954           result = true;
955           dimExtent = 0;
956         }
957       }
958 
959       if (const auto *triplet{std::get_if<Triplet>(&subscript[j].u)}) {
960         ++rank;
961         if (auto stride{ToInt64(triplet->stride())}) {
962           const Expr<SubscriptInteger> *lowerBound{triplet->GetLower()};
963           const Expr<SubscriptInteger> *upperBound{triplet->GetUpper()};
964           std::optional<ConstantSubscript> lowerVal{lowerBound
965                   ? ToInt64(Fold(context_, Expr<SubscriptInteger>{*lowerBound}))
966                   : dimLbound};
967           std::optional<ConstantSubscript> upperVal{upperBound
968                   ? ToInt64(Fold(context_, Expr<SubscriptInteger>{*upperBound}))
969                   : dimUbound};
970           if (lowerVal && upperVal) {
971             if (*lowerVal < *upperVal) {
972               if (*stride < 0) {
973                 result = true; // empty dimension
974               } else if (!result && *stride > 1 &&
975                   *lowerVal + *stride <= *upperVal) {
976                 result = false; // discontiguous if not empty
977               }
978             } else if (*lowerVal > *upperVal) {
979               if (*stride > 0) {
980                 result = true; // empty dimension
981               } else if (!result && *stride < 0 &&
982                   *lowerVal + *stride >= *upperVal) {
983                 result = false; // discontiguous if not empty
984               }
985             } else {
986               mayBeEmpty = true;
987             }
988           } else {
989             mayBeEmpty = true;
990           }
991         } else {
992           mayBeEmpty = true;
993         }
994       } else if (subscript[j].Rank() > 0) {
995         ++rank;
996         if (!result) {
997           result = false; // vector subscript
998         }
999         mayBeEmpty = true;
1000       } else {
1001         // Scalar subscript.
1002         if (dimExtent && *dimExtent > 1) {
1003           knownPartialSlice[j] = true;
1004         }
1005       }
1006     }
1007     if (rank == 0) {
1008       result = true; // scalar
1009     }
1010     if (result) {
1011       return result;
1012     }
1013     // Not provably discontiguous at this point.
1014     // Return "true" if simply contiguous, otherwise nullopt.
1015     for (auto j{subscript.size()}; j-- > 0;) {
1016       if (const auto *triplet{std::get_if<Triplet>(&subscript[j].u)}) {
1017         auto stride{ToInt64(triplet->stride())};
1018         if (!stride || stride != 1) {
1019           return std::nullopt;
1020         } else if (anyTriplet) {
1021           if (triplet->GetLower() || triplet->GetUpper()) {
1022             // all triplets before the last one must be just ":" for
1023             // simple contiguity
1024             return std::nullopt;
1025           }
1026         } else {
1027           anyTriplet = true;
1028         }
1029         ++rank;
1030       } else if (anyTriplet) {
1031         // If the section cannot be empty, and this dimension's
1032         // scalar subscript is known not to cover the whole
1033         // dimension, then the array section is provably
1034         // discontiguous.
1035         return (mayBeEmpty || !knownPartialSlice[j])
1036             ? std::nullopt
1037             : std::make_optional(false);
1038       }
1039     }
1040     return true; // simply contiguous
1041   }
1042 
1043   FoldingContext &context_;
1044 };
1045 
1046 template <typename A>
1047 std::optional<bool> IsContiguous(const A &x, FoldingContext &context) {
1048   return IsContiguousHelper{context}(x);
1049 }
1050 
1051 template std::optional<bool> IsContiguous(
1052     const Expr<SomeType> &, FoldingContext &);
1053 template std::optional<bool> IsContiguous(const ArrayRef &, FoldingContext &);
1054 template std::optional<bool> IsContiguous(const Substring &, FoldingContext &);
1055 template std::optional<bool> IsContiguous(const Component &, FoldingContext &);
1056 template std::optional<bool> IsContiguous(
1057     const ComplexPart &, FoldingContext &);
1058 template std::optional<bool> IsContiguous(const CoarrayRef &, FoldingContext &);
1059 template std::optional<bool> IsContiguous(const Symbol &, FoldingContext &);
1060 
1061 // IsErrorExpr()
1062 struct IsErrorExprHelper : public AnyTraverse<IsErrorExprHelper, bool> {
1063   using Result = bool;
1064   using Base = AnyTraverse<IsErrorExprHelper, Result>;
1065   IsErrorExprHelper() : Base{*this} {}
1066   using Base::operator();
1067 
1068   bool operator()(const SpecificIntrinsic &x) {
1069     return x.name == IntrinsicProcTable::InvalidName;
1070   }
1071 };
1072 
1073 template <typename A> bool IsErrorExpr(const A &x) {
1074   return IsErrorExprHelper{}(x);
1075 }
1076 
1077 template bool IsErrorExpr(const Expr<SomeType> &);
1078 
1079 // C1577
1080 // TODO: Also check C1579 & C1582 here
1081 class StmtFunctionChecker
1082     : public AnyTraverse<StmtFunctionChecker, std::optional<parser::Message>> {
1083 public:
1084   using Result = std::optional<parser::Message>;
1085   using Base = AnyTraverse<StmtFunctionChecker, Result>;
1086   StmtFunctionChecker(const Symbol &sf, FoldingContext &context)
1087       : Base{*this}, sf_{sf}, context_{context} {
1088     if (!context_.languageFeatures().IsEnabled(
1089             common::LanguageFeature::StatementFunctionExtensions)) {
1090       severity_ = parser::Severity::Error;
1091     } else if (context_.languageFeatures().ShouldWarn(
1092                    common::LanguageFeature::StatementFunctionExtensions)) {
1093       severity_ = parser::Severity::Portability;
1094     }
1095   }
1096   using Base::operator();
1097 
1098   template <typename T> Result operator()(const ArrayConstructor<T> &) const {
1099     if (severity_) {
1100       auto msg{
1101           "Statement function '%s' should not contain an array constructor"_port_en_US};
1102       msg.set_severity(*severity_);
1103       return parser::Message{sf_.name(), std::move(msg), sf_.name()};
1104     } else {
1105       return std::nullopt;
1106     }
1107   }
1108   Result operator()(const StructureConstructor &) const {
1109     if (severity_) {
1110       auto msg{
1111           "Statement function '%s' should not contain a structure constructor"_port_en_US};
1112       msg.set_severity(*severity_);
1113       return parser::Message{sf_.name(), std::move(msg), sf_.name()};
1114     } else {
1115       return std::nullopt;
1116     }
1117   }
1118   Result operator()(const TypeParamInquiry &) const {
1119     if (severity_) {
1120       auto msg{
1121           "Statement function '%s' should not contain a type parameter inquiry"_port_en_US};
1122       msg.set_severity(*severity_);
1123       return parser::Message{sf_.name(), std::move(msg), sf_.name()};
1124     } else {
1125       return std::nullopt;
1126     }
1127   }
1128   Result operator()(const ProcedureDesignator &proc) const {
1129     if (const Symbol * symbol{proc.GetSymbol()}) {
1130       const Symbol &ultimate{symbol->GetUltimate()};
1131       if (const auto *subp{
1132               ultimate.detailsIf<semantics::SubprogramDetails>()}) {
1133         if (subp->stmtFunction() && &ultimate.owner() == &sf_.owner()) {
1134           if (ultimate.name().begin() > sf_.name().begin()) {
1135             return parser::Message{sf_.name(),
1136                 "Statement function '%s' may not reference another statement function '%s' that is defined later"_err_en_US,
1137                 sf_.name(), ultimate.name()};
1138           }
1139         }
1140       }
1141       if (auto chars{characteristics::Procedure::Characterize(
1142               proc, context_, /*emitError=*/true)}) {
1143         if (!chars->CanBeCalledViaImplicitInterface()) {
1144           if (severity_) {
1145             auto msg{
1146                 "Statement function '%s' should not reference function '%s' that requires an explicit interface"_port_en_US};
1147             msg.set_severity(*severity_);
1148             return parser::Message{
1149                 sf_.name(), std::move(msg), sf_.name(), symbol->name()};
1150           }
1151         }
1152       }
1153     }
1154     if (proc.Rank() > 0) {
1155       if (severity_) {
1156         auto msg{
1157             "Statement function '%s' should not reference a function that returns an array"_port_en_US};
1158         msg.set_severity(*severity_);
1159         return parser::Message{sf_.name(), std::move(msg), sf_.name()};
1160       }
1161     }
1162     return std::nullopt;
1163   }
1164   Result operator()(const ActualArgument &arg) const {
1165     if (const auto *expr{arg.UnwrapExpr()}) {
1166       if (auto result{(*this)(*expr)}) {
1167         return result;
1168       }
1169       if (expr->Rank() > 0 && !UnwrapWholeSymbolOrComponentDataRef(*expr)) {
1170         if (severity_) {
1171           auto msg{
1172               "Statement function '%s' should not pass an array argument that is not a whole array"_port_en_US};
1173           msg.set_severity(*severity_);
1174           return parser::Message{sf_.name(), std::move(msg), sf_.name()};
1175         }
1176       }
1177     }
1178     return std::nullopt;
1179   }
1180 
1181 private:
1182   const Symbol &sf_;
1183   FoldingContext &context_;
1184   std::optional<parser::Severity> severity_;
1185 };
1186 
1187 std::optional<parser::Message> CheckStatementFunction(
1188     const Symbol &sf, const Expr<SomeType> &expr, FoldingContext &context) {
1189   return StmtFunctionChecker{sf, context}(expr);
1190 }
1191 
1192 } // namespace Fortran::evaluate
1193