1 //===-- lib/Semantics/check-declarations.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 // Static declaration checking
10 
11 #include "check-declarations.h"
12 #include "flang/Evaluate/check-expression.h"
13 #include "flang/Evaluate/fold.h"
14 #include "flang/Evaluate/tools.h"
15 #include "flang/Semantics/scope.h"
16 #include "flang/Semantics/semantics.h"
17 #include "flang/Semantics/symbol.h"
18 #include "flang/Semantics/tools.h"
19 #include "flang/Semantics/type.h"
20 #include <algorithm>
21 
22 namespace Fortran::semantics {
23 
24 using evaluate::characteristics::DummyArgument;
25 using evaluate::characteristics::DummyDataObject;
26 using evaluate::characteristics::DummyProcedure;
27 using evaluate::characteristics::FunctionResult;
28 using evaluate::characteristics::Procedure;
29 
30 class CheckHelper {
31 public:
32   explicit CheckHelper(SemanticsContext &c) : context_{c} {}
33 
34   void Check() { Check(context_.globalScope()); }
35   void Check(const ParamValue &, bool canBeAssumed);
36   void Check(const Bound &bound) { CheckSpecExpr(bound.GetExplicit()); }
37   void Check(const ShapeSpec &spec) {
38     Check(spec.lbound());
39     Check(spec.ubound());
40   }
41   void Check(const ArraySpec &);
42   void Check(const DeclTypeSpec &, bool canHaveAssumedTypeParameters);
43   void Check(const Symbol &);
44   void Check(const Scope &);
45 
46 private:
47   template <typename A> void CheckSpecExpr(const A &x) {
48     if (symbolBeingChecked_ && IsSaved(*symbolBeingChecked_)) {
49       if (!evaluate::IsConstantExpr(x)) {
50         messages_.Say(
51             "Specification expression must be constant in declaration of '%s' with the SAVE attribute"_err_en_US,
52             symbolBeingChecked_->name());
53       }
54     } else {
55       evaluate::CheckSpecificationExpr(
56           x, messages_, DEREF(scope_), context_.intrinsics());
57     }
58   }
59   template <typename A> void CheckSpecExpr(const std::optional<A> &x) {
60     if (x) {
61       CheckSpecExpr(*x);
62     }
63   }
64   template <typename A> void CheckSpecExpr(A &x) {
65     x = Fold(foldingContext_, std::move(x));
66     const A &constx{x};
67     CheckSpecExpr(constx);
68   }
69   void CheckValue(const Symbol &, const DerivedTypeSpec *);
70   void CheckVolatile(
71       const Symbol &, bool isAssociated, const DerivedTypeSpec *);
72   void CheckPointer(const Symbol &);
73   void CheckPassArg(
74       const Symbol &proc, const Symbol *interface, const WithPassArg &);
75   void CheckProcBinding(const Symbol &, const ProcBindingDetails &);
76   void CheckObjectEntity(const Symbol &, const ObjectEntityDetails &);
77   void CheckArraySpec(const Symbol &, const ArraySpec &);
78   void CheckProcEntity(const Symbol &, const ProcEntityDetails &);
79   void CheckSubprogram(const Symbol &, const SubprogramDetails &);
80   void CheckAssumedTypeEntity(const Symbol &, const ObjectEntityDetails &);
81   void CheckDerivedType(const Symbol &, const DerivedTypeDetails &);
82   void CheckGeneric(const Symbol &, const GenericDetails &);
83   std::optional<std::vector<Procedure>> Characterize(const SymbolVector &);
84   bool CheckDefinedOperator(const SourceName &, const GenericKind &,
85       const Symbol &, const Procedure &);
86   std::optional<parser::MessageFixedText> CheckNumberOfArgs(
87       const GenericKind &, std::size_t);
88   bool CheckDefinedOperatorArg(
89       const SourceName &, const Symbol &, const Procedure &, std::size_t);
90   bool CheckDefinedAssignment(const Symbol &, const Procedure &);
91   bool CheckDefinedAssignmentArg(const Symbol &, const DummyArgument &, int);
92   void CheckSpecificsAreDistinguishable(
93       const Symbol &, const GenericDetails &, const std::vector<Procedure> &);
94   void CheckEquivalenceSet(const EquivalenceSet &);
95   void CheckBlockData(const Scope &);
96 
97   void SayNotDistinguishable(
98       const SourceName &, GenericKind, const Symbol &, const Symbol &);
99   bool CheckConflicting(const Symbol &, Attr, Attr);
100   bool InPure() const {
101     return innermostSymbol_ && IsPureProcedure(*innermostSymbol_);
102   }
103   bool InFunction() const {
104     return innermostSymbol_ && IsFunction(*innermostSymbol_);
105   }
106   template <typename... A>
107   void SayWithDeclaration(const Symbol &symbol, A &&... x) {
108     if (parser::Message * msg{messages_.Say(std::forward<A>(x)...)}) {
109       if (messages_.at().begin() != symbol.name().begin()) {
110         evaluate::AttachDeclaration(*msg, symbol);
111       }
112     }
113   }
114   bool IsResultOkToDiffer(const FunctionResult &);
115 
116   SemanticsContext &context_;
117   evaluate::FoldingContext &foldingContext_{context_.foldingContext()};
118   parser::ContextualMessages &messages_{foldingContext_.messages()};
119   const Scope *scope_{nullptr};
120   // This symbol is the one attached to the innermost enclosing scope
121   // that has a symbol.
122   const Symbol *innermostSymbol_{nullptr};
123   const Symbol *symbolBeingChecked_{nullptr};
124 };
125 
126 void CheckHelper::Check(const ParamValue &value, bool canBeAssumed) {
127   if (value.isAssumed()) {
128     if (!canBeAssumed) { // C795, C721, C726
129       messages_.Say(
130           "An assumed (*) type parameter may be used only for a (non-statement"
131           " function) dummy argument, associate name, named constant, or"
132           " external function result"_err_en_US);
133     }
134   } else {
135     CheckSpecExpr(value.GetExplicit());
136   }
137 }
138 
139 void CheckHelper::Check(const ArraySpec &shape) {
140   for (const auto &spec : shape) {
141     Check(spec);
142   }
143 }
144 
145 void CheckHelper::Check(
146     const DeclTypeSpec &type, bool canHaveAssumedTypeParameters) {
147   if (type.category() == DeclTypeSpec::Character) {
148     Check(type.characterTypeSpec().length(), canHaveAssumedTypeParameters);
149   } else if (const DerivedTypeSpec * derived{type.AsDerived()}) {
150     for (auto &parm : derived->parameters()) {
151       Check(parm.second, canHaveAssumedTypeParameters);
152     }
153   }
154 }
155 
156 void CheckHelper::Check(const Symbol &symbol) {
157   if (context_.HasError(symbol)) {
158     return;
159   }
160   const DeclTypeSpec *type{symbol.GetType()};
161   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
162   auto restorer{messages_.SetLocation(symbol.name())};
163   context_.set_location(symbol.name());
164   bool isAssociated{symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()};
165   if (symbol.attrs().test(Attr::VOLATILE)) {
166     CheckVolatile(symbol, isAssociated, derived);
167   }
168   if (isAssociated) {
169     return; // only care about checking VOLATILE on associated symbols
170   }
171   if (IsPointer(symbol)) {
172     CheckPointer(symbol);
173   }
174   std::visit(
175       common::visitors{
176           [&](const ProcBindingDetails &x) { CheckProcBinding(symbol, x); },
177           [&](const ObjectEntityDetails &x) { CheckObjectEntity(symbol, x); },
178           [&](const ProcEntityDetails &x) { CheckProcEntity(symbol, x); },
179           [&](const SubprogramDetails &x) { CheckSubprogram(symbol, x); },
180           [&](const DerivedTypeDetails &x) { CheckDerivedType(symbol, x); },
181           [&](const GenericDetails &x) { CheckGeneric(symbol, x); },
182           [](const auto &) {},
183       },
184       symbol.details());
185   if (InPure()) {
186     if (IsSaved(symbol)) {
187       messages_.Say(
188           "A pure subprogram may not have a variable with the SAVE attribute"_err_en_US);
189     }
190     if (symbol.attrs().test(Attr::VOLATILE)) {
191       messages_.Say(
192           "A pure subprogram may not have a variable with the VOLATILE attribute"_err_en_US);
193     }
194     if (IsProcedure(symbol) && !IsPureProcedure(symbol) && IsDummy(symbol)) {
195       messages_.Say(
196           "A dummy procedure of a pure subprogram must be pure"_err_en_US);
197     }
198     if (!IsDummy(symbol) && !IsFunctionResult(symbol)) {
199       if (IsPolymorphicAllocatable(symbol)) {
200         SayWithDeclaration(symbol,
201             "Deallocation of polymorphic object '%s' is not permitted in a pure subprogram"_err_en_US,
202             symbol.name());
203       } else if (derived) {
204         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
205           SayWithDeclaration(*bad,
206               "Deallocation of polymorphic object '%s%s' is not permitted in a pure subprogram"_err_en_US,
207               symbol.name(), bad.BuildResultDesignatorName());
208         }
209       }
210     }
211   }
212   if (type) { // Section 7.2, paragraph 7
213     bool canHaveAssumedParameter{IsNamedConstant(symbol) ||
214         (IsAssumedLengthCharacter(symbol) && // C722
215             IsExternal(symbol)) ||
216         symbol.test(Symbol::Flag::ParentComp)};
217     if (!IsStmtFunctionDummy(symbol)) { // C726
218       if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
219         canHaveAssumedParameter |= object->isDummy() ||
220             (object->isFuncResult() &&
221                 type->category() == DeclTypeSpec::Character) ||
222             IsStmtFunctionResult(symbol); // Avoids multiple messages
223       } else {
224         canHaveAssumedParameter |= symbol.has<AssocEntityDetails>();
225       }
226     }
227     Check(*type, canHaveAssumedParameter);
228     if (InPure() && InFunction() && IsFunctionResult(symbol)) {
229       if (derived && HasImpureFinal(*derived)) { // C1584
230         messages_.Say(
231             "Result of pure function may not have an impure FINAL subroutine"_err_en_US);
232       }
233       if (type->IsPolymorphic() && IsAllocatable(symbol)) { // C1585
234         messages_.Say(
235             "Result of pure function may not be both polymorphic and ALLOCATABLE"_err_en_US);
236       }
237       if (derived) {
238         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
239           SayWithDeclaration(*bad,
240               "Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%s'"_err_en_US,
241               bad.BuildResultDesignatorName());
242         }
243       }
244     }
245   }
246   if (IsAssumedLengthCharacter(symbol) && IsExternal(symbol)) { // C723
247     if (symbol.attrs().test(Attr::RECURSIVE)) {
248       messages_.Say(
249           "An assumed-length CHARACTER(*) function cannot be RECURSIVE"_err_en_US);
250     }
251     if (symbol.Rank() > 0) {
252       messages_.Say(
253           "An assumed-length CHARACTER(*) function cannot return an array"_err_en_US);
254     }
255     if (symbol.attrs().test(Attr::PURE)) {
256       messages_.Say(
257           "An assumed-length CHARACTER(*) function cannot be PURE"_err_en_US);
258     }
259     if (symbol.attrs().test(Attr::ELEMENTAL)) {
260       messages_.Say(
261           "An assumed-length CHARACTER(*) function cannot be ELEMENTAL"_err_en_US);
262     }
263     if (const Symbol * result{FindFunctionResult(symbol)}) {
264       if (IsPointer(*result)) {
265         messages_.Say(
266             "An assumed-length CHARACTER(*) function cannot return a POINTER"_err_en_US);
267       }
268     }
269   }
270   if (symbol.attrs().test(Attr::VALUE)) {
271     CheckValue(symbol, derived);
272   }
273   if (symbol.attrs().test(Attr::CONTIGUOUS) && IsPointer(symbol) &&
274       symbol.Rank() == 0) { // C830
275     messages_.Say("CONTIGUOUS POINTER must be an array"_err_en_US);
276   }
277   if (IsDummy(symbol)) {
278     if (IsNamedConstant(symbol)) {
279       messages_.Say(
280           "A dummy argument may not also be a named constant"_err_en_US);
281     }
282     if (IsSaved(symbol)) {
283       messages_.Say(
284           "A dummy argument may not have the SAVE attribute"_err_en_US);
285     }
286   }
287   if (symbol.owner().IsDerivedType() &&
288       (symbol.attrs().test(Attr::CONTIGUOUS) &&
289           !(IsPointer(symbol) && symbol.Rank() > 0))) { // C752
290     messages_.Say(
291         "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
292   }
293 }
294 
295 void CheckHelper::CheckValue(
296     const Symbol &symbol, const DerivedTypeSpec *derived) { // C863 - C865
297   if (!IsDummy(symbol)) {
298     messages_.Say(
299         "VALUE attribute may apply only to a dummy argument"_err_en_US);
300   }
301   if (IsProcedure(symbol)) {
302     messages_.Say(
303         "VALUE attribute may apply only to a dummy data object"_err_en_US);
304   }
305   if (IsAssumedSizeArray(symbol)) {
306     messages_.Say(
307         "VALUE attribute may not apply to an assumed-size array"_err_en_US);
308   }
309   if (IsCoarray(symbol)) {
310     messages_.Say("VALUE attribute may not apply to a coarray"_err_en_US);
311   }
312   if (IsAllocatable(symbol)) {
313     messages_.Say("VALUE attribute may not apply to an ALLOCATABLE"_err_en_US);
314   } else if (IsPointer(symbol)) {
315     messages_.Say("VALUE attribute may not apply to a POINTER"_err_en_US);
316   }
317   if (IsIntentInOut(symbol)) {
318     messages_.Say(
319         "VALUE attribute may not apply to an INTENT(IN OUT) argument"_err_en_US);
320   } else if (IsIntentOut(symbol)) {
321     messages_.Say(
322         "VALUE attribute may not apply to an INTENT(OUT) argument"_err_en_US);
323   }
324   if (symbol.attrs().test(Attr::VOLATILE)) {
325     messages_.Say("VALUE attribute may not apply to a VOLATILE"_err_en_US);
326   }
327   if (innermostSymbol_ && IsBindCProcedure(*innermostSymbol_) &&
328       IsOptional(symbol)) {
329     messages_.Say(
330         "VALUE attribute may not apply to an OPTIONAL in a BIND(C) procedure"_err_en_US);
331   }
332   if (derived) {
333     if (FindCoarrayUltimateComponent(*derived)) {
334       messages_.Say(
335           "VALUE attribute may not apply to a type with a coarray ultimate component"_err_en_US);
336     }
337   }
338 }
339 
340 void CheckHelper::CheckAssumedTypeEntity( // C709
341     const Symbol &symbol, const ObjectEntityDetails &details) {
342   if (const DeclTypeSpec * type{symbol.GetType()};
343       type && type->category() == DeclTypeSpec::TypeStar) {
344     if (!IsDummy(symbol)) {
345       messages_.Say(
346           "Assumed-type entity '%s' must be a dummy argument"_err_en_US,
347           symbol.name());
348     } else {
349       if (symbol.attrs().test(Attr::ALLOCATABLE)) {
350         messages_.Say("Assumed-type argument '%s' cannot have the ALLOCATABLE"
351                       " attribute"_err_en_US,
352             symbol.name());
353       }
354       if (symbol.attrs().test(Attr::POINTER)) {
355         messages_.Say("Assumed-type argument '%s' cannot have the POINTER"
356                       " attribute"_err_en_US,
357             symbol.name());
358       }
359       if (symbol.attrs().test(Attr::VALUE)) {
360         messages_.Say("Assumed-type argument '%s' cannot have the VALUE"
361                       " attribute"_err_en_US,
362             symbol.name());
363       }
364       if (symbol.attrs().test(Attr::INTENT_OUT)) {
365         messages_.Say(
366             "Assumed-type argument '%s' cannot be INTENT(OUT)"_err_en_US,
367             symbol.name());
368       }
369       if (IsCoarray(symbol)) {
370         messages_.Say(
371             "Assumed-type argument '%s' cannot be a coarray"_err_en_US,
372             symbol.name());
373       }
374       if (details.IsArray() && details.shape().IsExplicitShape()) {
375         messages_.Say(
376             "Assumed-type array argument 'arg8' must be assumed shape,"
377             " assumed size, or assumed rank"_err_en_US,
378             symbol.name());
379       }
380     }
381   }
382 }
383 
384 void CheckHelper::CheckObjectEntity(
385     const Symbol &symbol, const ObjectEntityDetails &details) {
386   CHECK(!symbolBeingChecked_);
387   symbolBeingChecked_ = &symbol; // for specification expr checks
388   CheckArraySpec(symbol, details.shape());
389   Check(details.shape());
390   Check(details.coshape());
391   CheckAssumedTypeEntity(symbol, details);
392   symbolBeingChecked_ = nullptr;
393   if (!details.coshape().empty()) {
394     bool isDeferredShape{details.coshape().IsDeferredShape()};
395     if (IsAllocatable(symbol)) {
396       if (!isDeferredShape) { // C827
397         messages_.Say("'%s' is an ALLOCATABLE coarray and must have a deferred"
398                       " coshape"_err_en_US,
399             symbol.name());
400       }
401     } else if (symbol.owner().IsDerivedType()) { // C746
402       std::string deferredMsg{
403           isDeferredShape ? "" : " and have a deferred coshape"};
404       messages_.Say("Component '%s' is a coarray and must have the ALLOCATABLE"
405                     " attribute%s"_err_en_US,
406           symbol.name(), deferredMsg);
407     } else {
408       if (!details.coshape().IsAssumedSize()) { // C828
409         messages_.Say(
410             "Component '%s' is a non-ALLOCATABLE coarray and must have"
411             " an explicit coshape"_err_en_US,
412             symbol.name());
413       }
414     }
415   }
416   if (details.isDummy()) {
417     if (symbol.attrs().test(Attr::INTENT_OUT)) {
418       if (FindUltimateComponent(symbol, [](const Symbol &x) {
419             return IsCoarray(x) && IsAllocatable(x);
420           })) { // C846
421         messages_.Say(
422             "An INTENT(OUT) dummy argument may not be, or contain, an ALLOCATABLE coarray"_err_en_US);
423       }
424       if (IsOrContainsEventOrLockComponent(symbol)) { // C847
425         messages_.Say(
426             "An INTENT(OUT) dummy argument may not be, or contain, EVENT_TYPE or LOCK_TYPE"_err_en_US);
427       }
428     }
429     if (InPure() && !IsStmtFunction(DEREF(innermostSymbol_)) &&
430         !IsPointer(symbol) && !IsIntentIn(symbol) &&
431         !symbol.attrs().test(Attr::VALUE)) {
432       if (InFunction()) { // C1583
433         messages_.Say(
434             "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
435       } else if (IsIntentOut(symbol)) {
436         if (const DeclTypeSpec * type{details.type()}) {
437           if (type && type->IsPolymorphic()) { // C1588
438             messages_.Say(
439                 "An INTENT(OUT) dummy argument of a pure subroutine may not be polymorphic"_err_en_US);
440           } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
441             if (FindUltimateComponent(*derived, [](const Symbol &x) {
442                   const DeclTypeSpec *type{x.GetType()};
443                   return type && type->IsPolymorphic();
444                 })) { // C1588
445               messages_.Say(
446                   "An INTENT(OUT) dummy argument of a pure subroutine may not have a polymorphic ultimate component"_err_en_US);
447             }
448             if (HasImpureFinal(*derived)) { // C1587
449               messages_.Say(
450                   "An INTENT(OUT) dummy argument of a pure subroutine may not have an impure FINAL subroutine"_err_en_US);
451             }
452           }
453         }
454       } else if (!IsIntentInOut(symbol)) { // C1586
455         messages_.Say(
456             "non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute"_err_en_US);
457       }
458     }
459   }
460   if (symbol.owner().kind() != Scope::Kind::DerivedType &&
461       IsInitialized(symbol)) {
462     if (details.commonBlock()) {
463       if (details.commonBlock()->name().empty()) {
464         messages_.Say(
465             "A variable in blank COMMON should not be initialized"_en_US);
466       }
467     } else if (symbol.owner().kind() == Scope::Kind::BlockData) {
468       if (IsAllocatable(symbol)) {
469         messages_.Say(
470             "An ALLOCATABLE variable may not appear in a BLOCK DATA subprogram"_err_en_US);
471       } else {
472         messages_.Say(
473             "An initialized variable in BLOCK DATA must be in a COMMON block"_err_en_US);
474       }
475     }
476   }
477   if (const DeclTypeSpec * type{details.type()}) { // C708
478     if (type->IsPolymorphic() &&
479         !(type->IsAssumedType() || IsAllocatableOrPointer(symbol) ||
480             IsDummy(symbol))) {
481       messages_.Say("CLASS entity '%s' must be a dummy argument or have "
482                     "ALLOCATABLE or POINTER attribute"_err_en_US,
483           symbol.name());
484     }
485   }
486 }
487 
488 // The six different kinds of array-specs:
489 //   array-spec     -> explicit-shape-list | deferred-shape-list
490 //                     | assumed-shape-list | implied-shape-list
491 //                     | assumed-size | assumed-rank
492 //   explicit-shape -> [ lb : ] ub
493 //   deferred-shape -> :
494 //   assumed-shape  -> [ lb ] :
495 //   implied-shape  -> [ lb : ] *
496 //   assumed-size   -> [ explicit-shape-list , ] [ lb : ] *
497 //   assumed-rank   -> ..
498 // Note:
499 // - deferred-shape is also an assumed-shape
500 // - A single "*" or "lb:*" might be assumed-size or implied-shape-list
501 void CheckHelper::CheckArraySpec(
502     const Symbol &symbol, const ArraySpec &arraySpec) {
503   if (arraySpec.Rank() == 0) {
504     return;
505   }
506   bool isExplicit{arraySpec.IsExplicitShape()};
507   bool isDeferred{arraySpec.IsDeferredShape()};
508   bool isImplied{arraySpec.IsImpliedShape()};
509   bool isAssumedShape{arraySpec.IsAssumedShape()};
510   bool isAssumedSize{arraySpec.IsAssumedSize()};
511   bool isAssumedRank{arraySpec.IsAssumedRank()};
512   std::optional<parser::MessageFixedText> msg;
513   if (symbol.test(Symbol::Flag::CrayPointee) && !isExplicit && !isAssumedSize) {
514     msg = "Cray pointee '%s' must have must have explicit shape or"
515           " assumed size"_err_en_US;
516   } else if (IsAllocatableOrPointer(symbol) && !isDeferred && !isAssumedRank) {
517     if (symbol.owner().IsDerivedType()) { // C745
518       if (IsAllocatable(symbol)) {
519         msg = "Allocatable array component '%s' must have"
520               " deferred shape"_err_en_US;
521       } else {
522         msg = "Array pointer component '%s' must have deferred shape"_err_en_US;
523       }
524     } else {
525       if (IsAllocatable(symbol)) { // C832
526         msg = "Allocatable array '%s' must have deferred shape or"
527               " assumed rank"_err_en_US;
528       } else {
529         msg = "Array pointer '%s' must have deferred shape or"
530               " assumed rank"_err_en_US;
531       }
532     }
533   } else if (IsDummy(symbol)) {
534     if (isImplied && !isAssumedSize) { // C836
535       msg = "Dummy array argument '%s' may not have implied shape"_err_en_US;
536     }
537   } else if (isAssumedShape && !isDeferred) {
538     msg = "Assumed-shape array '%s' must be a dummy argument"_err_en_US;
539   } else if (isAssumedSize && !isImplied) { // C833
540     msg = "Assumed-size array '%s' must be a dummy argument"_err_en_US;
541   } else if (isAssumedRank) { // C837
542     msg = "Assumed-rank array '%s' must be a dummy argument"_err_en_US;
543   } else if (isImplied) {
544     if (!IsNamedConstant(symbol)) { // C836
545       msg = "Implied-shape array '%s' must be a named constant"_err_en_US;
546     }
547   } else if (IsNamedConstant(symbol)) {
548     if (!isExplicit && !isImplied) {
549       msg = "Named constant '%s' array must have explicit or"
550             " implied shape"_err_en_US;
551     }
552   } else if (!IsAllocatableOrPointer(symbol) && !isExplicit) {
553     if (symbol.owner().IsDerivedType()) { // C749
554       msg = "Component array '%s' without ALLOCATABLE or POINTER attribute must"
555             " have explicit shape"_err_en_US;
556     } else { // C816
557       msg = "Array '%s' without ALLOCATABLE or POINTER attribute must have"
558             " explicit shape"_err_en_US;
559     }
560   }
561   if (msg) {
562     context_.Say(std::move(*msg), symbol.name());
563   }
564 }
565 
566 void CheckHelper::CheckProcEntity(
567     const Symbol &symbol, const ProcEntityDetails &details) {
568   if (details.isDummy()) {
569     const Symbol *interface{details.interface().symbol()};
570     if (!symbol.attrs().test(Attr::INTRINSIC) &&
571         (symbol.attrs().test(Attr::ELEMENTAL) ||
572             (interface && !interface->attrs().test(Attr::INTRINSIC) &&
573                 interface->attrs().test(Attr::ELEMENTAL)))) {
574       // There's no explicit constraint or "shall" that we can find in the
575       // standard for this check, but it seems to be implied in multiple
576       // sites, and ELEMENTAL non-intrinsic actual arguments *are*
577       // explicitly forbidden.  But we allow "PROCEDURE(SIN)::dummy"
578       // because it is explicitly legal to *pass* the specific intrinsic
579       // function SIN as an actual argument.
580       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
581     }
582   } else if (symbol.owner().IsDerivedType()) {
583     if (!symbol.attrs().test(Attr::POINTER)) { // C756
584       const auto &name{symbol.name()};
585       messages_.Say(name,
586           "Procedure component '%s' must have POINTER attribute"_err_en_US,
587           name);
588     }
589     CheckPassArg(symbol, details.interface().symbol(), details);
590   }
591   if (symbol.attrs().test(Attr::POINTER)) {
592     if (const Symbol * interface{details.interface().symbol()}) {
593       if (interface->attrs().test(Attr::ELEMENTAL) &&
594           !interface->attrs().test(Attr::INTRINSIC)) {
595         messages_.Say("Procedure pointer '%s' may not be ELEMENTAL"_err_en_US,
596             symbol.name()); // C1517
597       }
598     }
599   }
600 }
601 
602 // When a module subprogram has the MODULE prefix the following must match
603 // with the corresponding separate module procedure interface body:
604 // - C1549: characteristics and dummy argument names
605 // - C1550: binding label
606 // - C1551: NON_RECURSIVE prefix
607 class SubprogramMatchHelper {
608 public:
609   explicit SubprogramMatchHelper(SemanticsContext &context)
610       : context{context} {}
611 
612   void Check(const Symbol &, const Symbol &);
613 
614 private:
615   void CheckDummyArg(const Symbol &, const Symbol &, const DummyArgument &,
616       const DummyArgument &);
617   void CheckDummyDataObject(const Symbol &, const Symbol &,
618       const DummyDataObject &, const DummyDataObject &);
619   void CheckDummyProcedure(const Symbol &, const Symbol &,
620       const DummyProcedure &, const DummyProcedure &);
621   bool CheckSameIntent(
622       const Symbol &, const Symbol &, common::Intent, common::Intent);
623   template <typename... A>
624   void Say(
625       const Symbol &, const Symbol &, parser::MessageFixedText &&, A &&...);
626   template <typename ATTRS>
627   bool CheckSameAttrs(const Symbol &, const Symbol &, ATTRS, ATTRS);
628   bool ShapesAreCompatible(const DummyDataObject &, const DummyDataObject &);
629   evaluate::Shape FoldShape(const evaluate::Shape &);
630   std::string AsFortran(DummyDataObject::Attr attr) {
631     return parser::ToUpperCaseLetters(DummyDataObject::EnumToString(attr));
632   }
633   std::string AsFortran(DummyProcedure::Attr attr) {
634     return parser::ToUpperCaseLetters(DummyProcedure::EnumToString(attr));
635   }
636 
637   SemanticsContext &context;
638 };
639 
640 // 15.6.2.6 para 3 - can the result of an ENTRY differ from its function?
641 bool CheckHelper::IsResultOkToDiffer(const FunctionResult &result) {
642   if (result.attrs.test(FunctionResult::Attr::Allocatable) ||
643       result.attrs.test(FunctionResult::Attr::Pointer)) {
644     return false;
645   }
646   const auto *typeAndShape{result.GetTypeAndShape()};
647   if (!typeAndShape || typeAndShape->Rank() != 0) {
648     return false;
649   }
650   auto category{typeAndShape->type().category()};
651   if (category == TypeCategory::Character ||
652       category == TypeCategory::Derived) {
653     return false;
654   }
655   int kind{typeAndShape->type().kind()};
656   return kind == context_.GetDefaultKind(category) ||
657       (category == TypeCategory::Real &&
658           kind == context_.doublePrecisionKind());
659 }
660 
661 void CheckHelper::CheckSubprogram(
662     const Symbol &symbol, const SubprogramDetails &details) {
663   if (const Symbol * iface{FindSeparateModuleSubprogramInterface(&symbol)}) {
664     SubprogramMatchHelper{context_}.Check(symbol, *iface);
665   }
666   if (const Scope * entryScope{details.entryScope()}) {
667     // ENTRY 15.6.2.6, esp. C1571
668     std::optional<parser::MessageFixedText> error;
669     const Symbol *subprogram{entryScope->symbol()};
670     const SubprogramDetails *subprogramDetails{nullptr};
671     if (subprogram) {
672       subprogramDetails = subprogram->detailsIf<SubprogramDetails>();
673     }
674     if (entryScope->kind() != Scope::Kind::Subprogram) {
675       error = "ENTRY may appear only in a subroutine or function"_err_en_US;
676     } else if (!(entryScope->parent().IsGlobal() ||
677                    entryScope->parent().IsModule() ||
678                    entryScope->parent().IsSubmodule())) {
679       error = "ENTRY may not appear in an internal subprogram"_err_en_US;
680     } else if (FindSeparateModuleSubprogramInterface(subprogram)) {
681       error = "ENTRY may not appear in a separate module procedure"_err_en_US;
682     } else if (subprogramDetails && details.isFunction() &&
683         subprogramDetails->isFunction()) {
684       auto result{FunctionResult::Characterize(
685           details.result(), context_.intrinsics())};
686       auto subpResult{FunctionResult::Characterize(
687           subprogramDetails->result(), context_.intrinsics())};
688       if (result && subpResult && *result != *subpResult &&
689           (!IsResultOkToDiffer(*result) || !IsResultOkToDiffer(*subpResult))) {
690         error =
691             "Result of ENTRY is not compatible with result of containing function"_err_en_US;
692       }
693     }
694     if (error) {
695       if (auto *msg{messages_.Say(symbol.name(), *error)}) {
696         if (subprogram) {
697           msg->Attach(subprogram->name(), "Containing subprogram"_en_US);
698         }
699       }
700     }
701   }
702 }
703 
704 void CheckHelper::CheckDerivedType(
705     const Symbol &symbol, const DerivedTypeDetails &details) {
706   const Scope *scope{symbol.scope()};
707   if (!scope) {
708     CHECK(details.isForwardReferenced());
709     return;
710   }
711   CHECK(scope->symbol() == &symbol);
712   CHECK(scope->IsDerivedType());
713   if (symbol.attrs().test(Attr::ABSTRACT) && // C734
714       (symbol.attrs().test(Attr::BIND_C) || details.sequence())) {
715     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
716   }
717   if (const DeclTypeSpec * parent{FindParentTypeSpec(symbol)}) {
718     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
719     if (!IsExtensibleType(parentDerived)) { // C705
720       messages_.Say("The parent type is not extensible"_err_en_US);
721     }
722     if (!symbol.attrs().test(Attr::ABSTRACT) && parentDerived &&
723         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
724       ScopeComponentIterator components{*parentDerived};
725       for (const Symbol &component : components) {
726         if (component.attrs().test(Attr::DEFERRED)) {
727           if (scope->FindComponent(component.name()) == &component) {
728             SayWithDeclaration(component,
729                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
730                 parentDerived->typeSymbol().name(), component.name());
731           }
732         }
733       }
734     }
735     DerivedTypeSpec derived{symbol.name(), symbol};
736     derived.set_scope(*scope);
737     if (FindCoarrayUltimateComponent(derived) && // C736
738         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
739       messages_.Say(
740           "Type '%s' has a coarray ultimate component so the type at the base "
741           "of its type extension chain ('%s') must be a type that has a "
742           "coarray ultimate component"_err_en_US,
743           symbol.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
744     }
745     if (FindEventOrLockPotentialComponent(derived) && // C737
746         !(FindEventOrLockPotentialComponent(*parentDerived) ||
747             IsEventTypeOrLockType(parentDerived))) {
748       messages_.Say(
749           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
750           "at the base of its type extension chain ('%s') must either have an "
751           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
752           "LOCK_TYPE"_err_en_US,
753           symbol.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
754     }
755   }
756   if (HasIntrinsicTypeName(symbol)) { // C729
757     messages_.Say("A derived type name cannot be the name of an intrinsic"
758                   " type"_err_en_US);
759   }
760 }
761 
762 void CheckHelper::CheckGeneric(
763     const Symbol &symbol, const GenericDetails &details) {
764   const SymbolVector &specifics{details.specificProcs()};
765   const auto &bindingNames{details.bindingNames()};
766   std::optional<std::vector<Procedure>> procs{Characterize(specifics)};
767   if (!procs) {
768     return;
769   }
770   bool ok{true};
771   if (details.kind().IsIntrinsicOperator()) {
772     for (std::size_t i{0}; i < specifics.size(); ++i) {
773       auto restorer{messages_.SetLocation(bindingNames[i])};
774       ok &= CheckDefinedOperator(
775           symbol.name(), details.kind(), specifics[i], (*procs)[i]);
776     }
777   }
778   if (details.kind().IsAssignment()) {
779     for (std::size_t i{0}; i < specifics.size(); ++i) {
780       auto restorer{messages_.SetLocation(bindingNames[i])};
781       ok &= CheckDefinedAssignment(specifics[i], (*procs)[i]);
782     }
783   }
784   if (ok) {
785     CheckSpecificsAreDistinguishable(symbol, details, *procs);
786   }
787 }
788 
789 // Check that the specifics of this generic are distinguishable from each other
790 void CheckHelper::CheckSpecificsAreDistinguishable(const Symbol &generic,
791     const GenericDetails &details, const std::vector<Procedure> &procs) {
792   const SymbolVector &specifics{details.specificProcs()};
793   std::size_t count{specifics.size()};
794   if (count < 2) {
795     return;
796   }
797   GenericKind kind{details.kind()};
798   auto distinguishable{kind.IsAssignment() || kind.IsOperator()
799           ? evaluate::characteristics::DistinguishableOpOrAssign
800           : evaluate::characteristics::Distinguishable};
801   for (std::size_t i1{0}; i1 < count - 1; ++i1) {
802     auto &proc1{procs[i1]};
803     for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
804       auto &proc2{procs[i2]};
805       if (!distinguishable(proc1, proc2)) {
806         SayNotDistinguishable(
807             generic.name(), kind, specifics[i1], specifics[i2]);
808       }
809     }
810   }
811 }
812 
813 void CheckHelper::SayNotDistinguishable(const SourceName &name,
814     GenericKind kind, const Symbol &proc1, const Symbol &proc2) {
815   auto &&text{kind.IsDefinedOperator()
816           ? "Generic operator '%s' may not have specific procedures '%s'"
817             " and '%s' as their interfaces are not distinguishable"_err_en_US
818           : "Generic '%s' may not have specific procedures '%s'"
819             " and '%s' as their interfaces are not distinguishable"_err_en_US};
820   auto &msg{
821       context_.Say(name, std::move(text), name, proc1.name(), proc2.name())};
822   evaluate::AttachDeclaration(msg, proc1);
823   evaluate::AttachDeclaration(msg, proc2);
824 }
825 
826 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
827   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
828   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
829   return Tristate::No ==
830       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
831 }
832 
833 static bool ConflictsWithIntrinsicOperator(
834     const GenericKind &kind, const Procedure &proc) {
835   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
836   auto type0{arg0.type()};
837   if (proc.dummyArguments.size() == 1) { // unary
838     return std::visit(
839         common::visitors{
840             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
841             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
842             [](const auto &) -> bool { DIE("bad generic kind"); },
843         },
844         kind.u);
845   } else { // binary
846     int rank0{arg0.Rank()};
847     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
848     auto type1{arg1.type()};
849     int rank1{arg1.Rank()};
850     return std::visit(
851         common::visitors{
852             [&](common::NumericOperator) {
853               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
854             },
855             [&](common::LogicalOperator) {
856               return IsIntrinsicLogical(type0, rank0, type1, rank1);
857             },
858             [&](common::RelationalOperator opr) {
859               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
860             },
861             [&](GenericKind::OtherKind x) {
862               CHECK(x == GenericKind::OtherKind::Concat);
863               return IsIntrinsicConcat(type0, rank0, type1, rank1);
864             },
865             [](const auto &) -> bool { DIE("bad generic kind"); },
866         },
867         kind.u);
868   }
869 }
870 
871 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
872 bool CheckHelper::CheckDefinedOperator(const SourceName &opName,
873     const GenericKind &kind, const Symbol &specific, const Procedure &proc) {
874   std::optional<parser::MessageFixedText> msg;
875   if (specific.attrs().test(Attr::NOPASS)) { // C774
876     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
877   } else if (!proc.functionResult.has_value()) {
878     msg = "%s procedure '%s' must be a function"_err_en_US;
879   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
880     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
881           " result"_err_en_US;
882   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
883     msg = std::move(m);
884   } else if (!CheckDefinedOperatorArg(opName, specific, proc, 0) |
885       !CheckDefinedOperatorArg(opName, specific, proc, 1)) {
886     return false; // error was reported
887   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
888     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
889   } else {
890     return true; // OK
891   }
892   SayWithDeclaration(specific, std::move(msg.value()),
893       parser::ToUpperCaseLetters(opName.ToString()), specific.name());
894   return false;
895 }
896 
897 // If the number of arguments is wrong for this intrinsic operator, return
898 // false and return the error message in msg.
899 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
900     const GenericKind &kind, std::size_t nargs) {
901   std::size_t min{2}, max{2}; // allowed number of args; default is binary
902   std::visit(common::visitors{
903                  [&](const common::NumericOperator &x) {
904                    if (x == common::NumericOperator::Add ||
905                        x == common::NumericOperator::Subtract) {
906                      min = 1; // + and - are unary or binary
907                    }
908                  },
909                  [&](const common::LogicalOperator &x) {
910                    if (x == common::LogicalOperator::Not) {
911                      min = 1; // .NOT. is unary
912                      max = 1;
913                    }
914                  },
915                  [](const common::RelationalOperator &) {
916                    // all are binary
917                  },
918                  [](const GenericKind::OtherKind &x) {
919                    CHECK(x == GenericKind::OtherKind::Concat);
920                  },
921                  [](const auto &) { DIE("expected intrinsic operator"); },
922              },
923       kind.u);
924   if (nargs >= min && nargs <= max) {
925     return std::nullopt;
926   } else if (max == 1) {
927     return "%s function '%s' must have one dummy argument"_err_en_US;
928   } else if (min == 2) {
929     return "%s function '%s' must have two dummy arguments"_err_en_US;
930   } else {
931     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
932   }
933 }
934 
935 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
936     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
937   if (pos >= proc.dummyArguments.size()) {
938     return true;
939   }
940   auto &arg{proc.dummyArguments.at(pos)};
941   std::optional<parser::MessageFixedText> msg;
942   if (arg.IsOptional()) {
943     msg = "In %s function '%s', dummy argument '%s' may not be"
944           " OPTIONAL"_err_en_US;
945   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
946              dataObject == nullptr) {
947     msg = "In %s function '%s', dummy argument '%s' must be a"
948           " data object"_err_en_US;
949   } else if (dataObject->intent != common::Intent::In &&
950       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
951     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
952           " or VALUE attribute"_err_en_US;
953   }
954   if (msg) {
955     SayWithDeclaration(symbol, std::move(*msg),
956         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
957     return false;
958   }
959   return true;
960 }
961 
962 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
963 bool CheckHelper::CheckDefinedAssignment(
964     const Symbol &specific, const Procedure &proc) {
965   std::optional<parser::MessageFixedText> msg;
966   if (specific.attrs().test(Attr::NOPASS)) { // C774
967     msg = "Defined assignment procedure '%s' may not have"
968           " NOPASS attribute"_err_en_US;
969   } else if (!proc.IsSubroutine()) {
970     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
971   } else if (proc.dummyArguments.size() != 2) {
972     msg = "Defined assignment subroutine '%s' must have"
973           " two dummy arguments"_err_en_US;
974   } else if (!CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0) |
975       !CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)) {
976     return false; // error was reported
977   } else if (ConflictsWithIntrinsicAssignment(proc)) {
978     msg = "Defined assignment subroutine '%s' conflicts with"
979           " intrinsic assignment"_err_en_US;
980   } else {
981     return true; // OK
982   }
983   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
984   return false;
985 }
986 
987 bool CheckHelper::CheckDefinedAssignmentArg(
988     const Symbol &symbol, const DummyArgument &arg, int pos) {
989   std::optional<parser::MessageFixedText> msg;
990   if (arg.IsOptional()) {
991     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
992           " may not be OPTIONAL"_err_en_US;
993   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
994     if (pos == 0) {
995       if (dataObject->intent != common::Intent::Out &&
996           dataObject->intent != common::Intent::InOut) {
997         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
998               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
999       }
1000     } else if (pos == 1) {
1001       if (dataObject->intent != common::Intent::In &&
1002           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1003         msg =
1004             "In defined assignment subroutine '%s', second dummy"
1005             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1006       }
1007     } else {
1008       DIE("pos must be 0 or 1");
1009     }
1010   } else {
1011     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1012           " must be a data object"_err_en_US;
1013   }
1014   if (msg) {
1015     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1016     return false;
1017   }
1018   return true;
1019 }
1020 
1021 // Report a conflicting attribute error if symbol has both of these attributes
1022 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1023   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1024     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1025         symbol.name(), EnumToString(a1), EnumToString(a2));
1026     return true;
1027   } else {
1028     return false;
1029   }
1030 }
1031 
1032 std::optional<std::vector<Procedure>> CheckHelper::Characterize(
1033     const SymbolVector &specifics) {
1034   std::vector<Procedure> result;
1035   for (const Symbol &specific : specifics) {
1036     auto proc{Procedure::Characterize(specific, context_.intrinsics())};
1037     if (!proc || context_.HasError(specific)) {
1038       return std::nullopt;
1039     }
1040     result.emplace_back(*proc);
1041   }
1042   return result;
1043 }
1044 
1045 void CheckHelper::CheckVolatile(const Symbol &symbol, bool isAssociated,
1046     const DerivedTypeSpec *derived) { // C866 - C868
1047   if (IsIntentIn(symbol)) {
1048     messages_.Say(
1049         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1050   }
1051   if (IsProcedure(symbol)) {
1052     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1053   }
1054   if (isAssociated) {
1055     const Symbol &ultimate{symbol.GetUltimate()};
1056     if (IsCoarray(ultimate)) {
1057       messages_.Say(
1058           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1059     }
1060     if (derived) {
1061       if (FindCoarrayUltimateComponent(*derived)) {
1062         messages_.Say(
1063             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1064       }
1065     }
1066   }
1067 }
1068 
1069 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1070   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1071   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1072   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1073   if (symbol.Corank() > 0) {
1074     messages_.Say(
1075         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1076         symbol.name());
1077   }
1078 }
1079 
1080 // C760 constraints on the passed-object dummy argument
1081 // C757 constraints on procedure pointer components
1082 void CheckHelper::CheckPassArg(
1083     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1084   if (proc.attrs().test(Attr::NOPASS)) {
1085     return;
1086   }
1087   const auto &name{proc.name()};
1088   if (!interface) {
1089     messages_.Say(name,
1090         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1091         name);
1092     return;
1093   }
1094   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1095   if (!subprogram) {
1096     messages_.Say(name,
1097         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1098         interface->name());
1099     return;
1100   }
1101   std::optional<SourceName> passName{details.passName()};
1102   const auto &dummyArgs{subprogram->dummyArgs()};
1103   if (!passName) {
1104     if (dummyArgs.empty()) {
1105       messages_.Say(name,
1106           proc.has<ProcEntityDetails>()
1107               ? "Procedure component '%s' with no dummy arguments"
1108                 " must have NOPASS attribute"_err_en_US
1109               : "Procedure binding '%s' with no dummy arguments"
1110                 " must have NOPASS attribute"_err_en_US,
1111           name);
1112       return;
1113     }
1114     passName = dummyArgs[0]->name();
1115   }
1116   std::optional<int> passArgIndex{};
1117   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1118     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1119       passArgIndex = i;
1120       break;
1121     }
1122   }
1123   if (!passArgIndex) { // C758
1124     messages_.Say(*passName,
1125         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1126         *passName, interface->name());
1127     return;
1128   }
1129   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1130   std::optional<parser::MessageFixedText> msg;
1131   if (!passArg.has<ObjectEntityDetails>()) {
1132     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1133           " must be a data object"_err_en_US;
1134   } else if (passArg.attrs().test(Attr::POINTER)) {
1135     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1136           " may not have the POINTER attribute"_err_en_US;
1137   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1138     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1139           " may not have the ALLOCATABLE attribute"_err_en_US;
1140   } else if (passArg.attrs().test(Attr::VALUE)) {
1141     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1142           " may not have the VALUE attribute"_err_en_US;
1143   } else if (passArg.Rank() > 0) {
1144     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1145           " must be scalar"_err_en_US;
1146   }
1147   if (msg) {
1148     messages_.Say(name, std::move(*msg), passName.value(), name);
1149     return;
1150   }
1151   const DeclTypeSpec *type{passArg.GetType()};
1152   if (!type) {
1153     return; // an error already occurred
1154   }
1155   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1156   const DerivedTypeSpec *derived{type->AsDerived()};
1157   if (!derived || derived->typeSymbol() != typeSymbol) {
1158     messages_.Say(name,
1159         "Passed-object dummy argument '%s' of procedure '%s'"
1160         " must be of type '%s' but is '%s'"_err_en_US,
1161         passName.value(), name, typeSymbol.name(), type->AsFortran());
1162     return;
1163   }
1164   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1165     messages_.Say(name,
1166         type->IsPolymorphic()
1167             ? "Passed-object dummy argument '%s' of procedure '%s'"
1168               " may not be polymorphic because '%s' is not extensible"_err_en_US
1169             : "Passed-object dummy argument '%s' of procedure '%s'"
1170               " must be polymorphic because '%s' is extensible"_err_en_US,
1171         passName.value(), name, typeSymbol.name());
1172     return;
1173   }
1174   for (const auto &[paramName, paramValue] : derived->parameters()) {
1175     if (paramValue.isLen() && !paramValue.isAssumed()) {
1176       messages_.Say(name,
1177           "Passed-object dummy argument '%s' of procedure '%s'"
1178           " has non-assumed length parameter '%s'"_err_en_US,
1179           passName.value(), name, paramName);
1180     }
1181   }
1182 }
1183 
1184 void CheckHelper::CheckProcBinding(
1185     const Symbol &symbol, const ProcBindingDetails &binding) {
1186   const Scope &dtScope{symbol.owner()};
1187   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1188   if (const Symbol * dtSymbol{dtScope.symbol()}) {
1189     if (symbol.attrs().test(Attr::DEFERRED)) {
1190       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1191         SayWithDeclaration(*dtSymbol,
1192             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1193             dtSymbol->name());
1194       }
1195       if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1196         messages_.Say(
1197             "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1198             symbol.name());
1199       }
1200     }
1201   }
1202   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1203     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1204       SayWithDeclaration(*overridden,
1205           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1206           symbol.name());
1207     }
1208     if (const auto *overriddenBinding{
1209             overridden->detailsIf<ProcBindingDetails>()}) {
1210       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1211         SayWithDeclaration(*overridden,
1212             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1213         return;
1214       }
1215       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1216           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1217         SayWithDeclaration(*overridden,
1218             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1219         return;
1220       }
1221       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1222       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1223         SayWithDeclaration(*overridden,
1224             isNopass
1225                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1226                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1227       } else {
1228         auto bindingChars{evaluate::characteristics::Procedure::Characterize(
1229             binding.symbol(), context_.intrinsics())};
1230         auto overriddenChars{evaluate::characteristics::Procedure::Characterize(
1231             overriddenBinding->symbol(), context_.intrinsics())};
1232         if (bindingChars && overriddenChars) {
1233           if (isNopass) {
1234             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1235               SayWithDeclaration(*overridden,
1236                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1237             }
1238           } else {
1239             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1240             int overriddenPassIndex{
1241                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1242             if (passIndex != overriddenPassIndex) {
1243               SayWithDeclaration(*overridden,
1244                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1245             } else if (!bindingChars->CanOverride(
1246                            *overriddenChars, passIndex)) {
1247               SayWithDeclaration(*overridden,
1248                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1249             }
1250           }
1251         }
1252       }
1253       if (symbol.attrs().test(Attr::PRIVATE) &&
1254           overridden->attrs().test(Attr::PUBLIC)) {
1255         SayWithDeclaration(*overridden,
1256             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1257       }
1258     } else {
1259       SayWithDeclaration(*overridden,
1260           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1261     }
1262   }
1263   CheckPassArg(symbol, &binding.symbol(), binding);
1264 }
1265 
1266 void CheckHelper::Check(const Scope &scope) {
1267   scope_ = &scope;
1268   common::Restorer<const Symbol *> restorer{innermostSymbol_};
1269   if (const Symbol * symbol{scope.symbol()}) {
1270     innermostSymbol_ = symbol;
1271   } else if (scope.IsDerivedType()) {
1272     return; // PDT instantiations have null symbol()
1273   }
1274   for (const auto &set : scope.equivalenceSets()) {
1275     CheckEquivalenceSet(set);
1276   }
1277   for (const auto &pair : scope) {
1278     Check(*pair.second);
1279   }
1280   for (const Scope &child : scope.children()) {
1281     Check(child);
1282   }
1283   if (scope.kind() == Scope::Kind::BlockData) {
1284     CheckBlockData(scope);
1285   }
1286 }
1287 
1288 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1289   auto iter{
1290       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1291         return FindCommonBlockContaining(object.symbol) != nullptr;
1292       })};
1293   if (iter != set.end()) {
1294     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1295     for (auto &object : set) {
1296       if (&object != &*iter) {
1297         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1298           if (details->commonBlock()) {
1299             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1300               if (auto *msg{messages_.Say(object.symbol.name(),
1301                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1302                 msg->Attach(iter->symbol.name(),
1303                        "Other object in EQUIVALENCE set"_en_US)
1304                     .Attach(details->commonBlock()->name(),
1305                         "COMMON block containing '%s'"_en_US,
1306                         object.symbol.name())
1307                     .Attach(commonBlock.name(),
1308                         "COMMON block containing '%s'"_en_US,
1309                         iter->symbol.name());
1310               }
1311             }
1312           } else {
1313             // Mark all symbols in the equivalence set with the same COMMON
1314             // block to prevent spurious error messages about initialization
1315             // in BLOCK DATA outside COMMON
1316             details->set_commonBlock(commonBlock);
1317           }
1318         }
1319       }
1320     }
1321   }
1322   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1323 }
1324 
1325 void CheckHelper::CheckBlockData(const Scope &scope) {
1326   // BLOCK DATA subprograms should contain only named common blocks.
1327   // C1415 presents a list of statements that shouldn't appear in
1328   // BLOCK DATA, but so long as the subprogram contains no executable
1329   // code and allocates no storage outside named COMMON, we're happy
1330   // (e.g., an ENUM is strictly not allowed).
1331   for (const auto &pair : scope) {
1332     const Symbol &symbol{*pair.second};
1333     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1334             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1335             symbol.has<SubprogramDetails>() ||
1336             symbol.has<ObjectEntityDetails>() ||
1337             (symbol.has<ProcEntityDetails>() &&
1338                 !symbol.attrs().test(Attr::POINTER)))) {
1339       messages_.Say(symbol.name(),
1340           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1341           symbol.name());
1342     }
1343   }
1344 }
1345 
1346 void SubprogramMatchHelper::Check(
1347     const Symbol &symbol1, const Symbol &symbol2) {
1348   const auto details1{symbol1.get<SubprogramDetails>()};
1349   const auto details2{symbol2.get<SubprogramDetails>()};
1350   if (details1.isFunction() != details2.isFunction()) {
1351     Say(symbol1, symbol2,
1352         details1.isFunction()
1353             ? "Module function '%s' was declared as a subroutine in the"
1354               " corresponding interface body"_err_en_US
1355             : "Module subroutine '%s' was declared as a function in the"
1356               " corresponding interface body"_err_en_US);
1357     return;
1358   }
1359   const auto &args1{details1.dummyArgs()};
1360   const auto &args2{details2.dummyArgs()};
1361   int nargs1{static_cast<int>(args1.size())};
1362   int nargs2{static_cast<int>(args2.size())};
1363   if (nargs1 != nargs2) {
1364     Say(symbol1, symbol2,
1365         "Module subprogram '%s' has %d args but the corresponding interface"
1366         " body has %d"_err_en_US,
1367         nargs1, nargs2);
1368     return;
1369   }
1370   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
1371   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
1372     Say(symbol1, symbol2,
1373         nonRecursive1
1374             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
1375               " the corresponding interface body does not"_err_en_US
1376             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
1377               "the corresponding interface body does"_err_en_US);
1378   }
1379   MaybeExpr bindName1{details1.bindName()};
1380   MaybeExpr bindName2{details2.bindName()};
1381   if (bindName1.has_value() != bindName2.has_value()) {
1382     Say(symbol1, symbol2,
1383         bindName1.has_value()
1384             ? "Module subprogram '%s' has a binding label but the corresponding"
1385               " interface body does not"_err_en_US
1386             : "Module subprogram '%s' does not have a binding label but the"
1387               " corresponding interface body does"_err_en_US);
1388   } else if (bindName1) {
1389     std::string string1{bindName1->AsFortran()};
1390     std::string string2{bindName2->AsFortran()};
1391     if (string1 != string2) {
1392       Say(symbol1, symbol2,
1393           "Module subprogram '%s' has binding label %s but the corresponding"
1394           " interface body has %s"_err_en_US,
1395           string1, string2);
1396     }
1397   }
1398   auto proc1{Procedure::Characterize(symbol1, context.intrinsics())};
1399   auto proc2{Procedure::Characterize(symbol2, context.intrinsics())};
1400   if (!proc1 || !proc2) {
1401     return;
1402   }
1403   if (proc1->functionResult && proc2->functionResult &&
1404       *proc1->functionResult != *proc2->functionResult) {
1405     Say(symbol1, symbol2,
1406         "Return type of function '%s' does not match return type of"
1407         " the corresponding interface body"_err_en_US);
1408   }
1409   for (int i{0}; i < nargs1; ++i) {
1410     const Symbol *arg1{args1[i]};
1411     const Symbol *arg2{args2[i]};
1412     if (arg1 && !arg2) {
1413       Say(symbol1, symbol2,
1414           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
1415           " but the corresponding argument in the interface body is"_err_en_US,
1416           i + 1);
1417     } else if (!arg1 && arg2) {
1418       Say(symbol1, symbol2,
1419           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
1420           " the corresponding argument in the interface body is not"_err_en_US,
1421           i + 1);
1422     } else if (arg1 && arg2) {
1423       SourceName name1{arg1->name()};
1424       SourceName name2{arg2->name()};
1425       if (name1 != name2) {
1426         Say(*arg1, *arg2,
1427             "Dummy argument name '%s' does not match corresponding name '%s'"
1428             " in interface body"_err_en_US,
1429             name2);
1430       } else {
1431         CheckDummyArg(
1432             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
1433       }
1434     }
1435   }
1436 }
1437 
1438 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
1439     const Symbol &symbol2, const DummyArgument &arg1,
1440     const DummyArgument &arg2) {
1441   std::visit(common::visitors{
1442                  [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
1443                    CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
1444                  },
1445                  [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
1446                    CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
1447                  },
1448                  [&](const DummyDataObject &, const auto &) {
1449                    Say(symbol1, symbol2,
1450                        "Dummy argument '%s' is a data object; the corresponding"
1451                        " argument in the interface body is not"_err_en_US);
1452                  },
1453                  [&](const DummyProcedure &, const auto &) {
1454                    Say(symbol1, symbol2,
1455                        "Dummy argument '%s' is a procedure; the corresponding"
1456                        " argument in the interface body is not"_err_en_US);
1457                  },
1458                  [&](const auto &, const auto &) { DIE("can't happen"); },
1459              },
1460       arg1.u, arg2.u);
1461 }
1462 
1463 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
1464     const Symbol &symbol2, const DummyDataObject &obj1,
1465     const DummyDataObject &obj2) {
1466   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
1467   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
1468   } else if (obj1.type.type() != obj2.type.type()) {
1469     Say(symbol1, symbol2,
1470         "Dummy argument '%s' has type %s; the corresponding argument in the"
1471         " interface body has type %s"_err_en_US,
1472         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
1473   } else if (!ShapesAreCompatible(obj1, obj2)) {
1474     Say(symbol1, symbol2,
1475         "The shape of dummy argument '%s' does not match the shape of the"
1476         " corresponding argument in the interface body"_err_en_US);
1477   }
1478   // TODO: coshape
1479 }
1480 
1481 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
1482     const Symbol &symbol2, const DummyProcedure &proc1,
1483     const DummyProcedure &proc2) {
1484   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
1485   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
1486   } else if (proc1 != proc2) {
1487     Say(symbol1, symbol2,
1488         "Dummy procedure '%s' does not match the corresponding argument in"
1489         " the interface body"_err_en_US);
1490   }
1491 }
1492 
1493 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
1494     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
1495   if (intent1 == intent2) {
1496     return true;
1497   } else {
1498     Say(symbol1, symbol2,
1499         "The intent of dummy argument '%s' does not match the intent"
1500         " of the corresponding argument in the interface body"_err_en_US);
1501     return false;
1502   }
1503 }
1504 
1505 // Report an error referring to first symbol with declaration of second symbol
1506 template <typename... A>
1507 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
1508     parser::MessageFixedText &&text, A &&... args) {
1509   auto &message{context.Say(symbol1.name(), std::move(text), symbol1.name(),
1510       std::forward<A>(args)...)};
1511   evaluate::AttachDeclaration(message, symbol2);
1512 }
1513 
1514 template <typename ATTRS>
1515 bool SubprogramMatchHelper::CheckSameAttrs(
1516     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
1517   if (attrs1 == attrs2) {
1518     return true;
1519   }
1520   attrs1.IterateOverMembers([&](auto attr) {
1521     if (!attrs2.test(attr)) {
1522       Say(symbol1, symbol2,
1523           "Dummy argument '%s' has the %s attribute; the corresponding"
1524           " argument in the interface body does not"_err_en_US,
1525           AsFortran(attr));
1526     }
1527   });
1528   attrs2.IterateOverMembers([&](auto attr) {
1529     if (!attrs1.test(attr)) {
1530       Say(symbol1, symbol2,
1531           "Dummy argument '%s' does not have the %s attribute; the"
1532           " corresponding argument in the interface body does"_err_en_US,
1533           AsFortran(attr));
1534     }
1535   });
1536   return false;
1537 }
1538 
1539 bool SubprogramMatchHelper::ShapesAreCompatible(
1540     const DummyDataObject &obj1, const DummyDataObject &obj2) {
1541   return evaluate::characteristics::ShapesAreCompatible(
1542       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
1543 }
1544 
1545 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
1546   evaluate::Shape result;
1547   for (const auto &extent : shape) {
1548     result.emplace_back(
1549         evaluate::Fold(context.foldingContext(), common::Clone(extent)));
1550   }
1551   return result;
1552 }
1553 
1554 void CheckDeclarations(SemanticsContext &context) {
1555   CheckHelper{context}.Check();
1556 }
1557 
1558 } // namespace Fortran::semantics
1559