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 "pointer-assignment.h"
13 #include "flang/Evaluate/check-expression.h"
14 #include "flang/Evaluate/fold.h"
15 #include "flang/Evaluate/tools.h"
16 #include "flang/Semantics/scope.h"
17 #include "flang/Semantics/semantics.h"
18 #include "flang/Semantics/symbol.h"
19 #include "flang/Semantics/tools.h"
20 #include "flang/Semantics/type.h"
21 #include <algorithm>
22 #include <map>
23 #include <string>
24 
25 namespace Fortran::semantics {
26 
27 namespace characteristics = evaluate::characteristics;
28 using characteristics::DummyArgument;
29 using characteristics::DummyDataObject;
30 using characteristics::DummyProcedure;
31 using characteristics::FunctionResult;
32 using characteristics::Procedure;
33 
34 class CheckHelper {
35 public:
36   explicit CheckHelper(SemanticsContext &c) : context_{c} {}
37   CheckHelper(SemanticsContext &c, const Scope &s) : context_{c}, scope_{&s} {}
38 
39   SemanticsContext &context() { return context_; }
40   void Check() { Check(context_.globalScope()); }
41   void Check(const ParamValue &, bool canBeAssumed);
42   void Check(const Bound &bound) { CheckSpecExpr(bound.GetExplicit()); }
43   void Check(const ShapeSpec &spec) {
44     Check(spec.lbound());
45     Check(spec.ubound());
46   }
47   void Check(const ArraySpec &);
48   void Check(const DeclTypeSpec &, bool canHaveAssumedTypeParameters);
49   void Check(const Symbol &);
50   void Check(const Scope &);
51   const Procedure *Characterize(const Symbol &);
52 
53 private:
54   template <typename A> void CheckSpecExpr(const A &x) {
55     evaluate::CheckSpecificationExpr(x, DEREF(scope_), foldingContext_);
56   }
57   void CheckValue(const Symbol &, const DerivedTypeSpec *);
58   void CheckVolatile(const Symbol &, const DerivedTypeSpec *);
59   void CheckPointer(const Symbol &);
60   void CheckPassArg(
61       const Symbol &proc, const Symbol *interface, const WithPassArg &);
62   void CheckProcBinding(const Symbol &, const ProcBindingDetails &);
63   void CheckObjectEntity(const Symbol &, const ObjectEntityDetails &);
64   void CheckPointerInitialization(const Symbol &);
65   void CheckArraySpec(const Symbol &, const ArraySpec &);
66   void CheckProcEntity(const Symbol &, const ProcEntityDetails &);
67   void CheckSubprogram(const Symbol &, const SubprogramDetails &);
68   void CheckAssumedTypeEntity(const Symbol &, const ObjectEntityDetails &);
69   void CheckDerivedType(const Symbol &, const DerivedTypeDetails &);
70   bool CheckFinal(
71       const Symbol &subroutine, SourceName, const Symbol &derivedType);
72   bool CheckDistinguishableFinals(const Symbol &f1, SourceName f1name,
73       const Symbol &f2, SourceName f2name, const Symbol &derivedType);
74   void CheckGeneric(const Symbol &, const GenericDetails &);
75   void CheckHostAssoc(const Symbol &, const HostAssocDetails &);
76   bool CheckDefinedOperator(
77       SourceName, GenericKind, const Symbol &, const Procedure &);
78   std::optional<parser::MessageFixedText> CheckNumberOfArgs(
79       const GenericKind &, std::size_t);
80   bool CheckDefinedOperatorArg(
81       const SourceName &, const Symbol &, const Procedure &, std::size_t);
82   bool CheckDefinedAssignment(const Symbol &, const Procedure &);
83   bool CheckDefinedAssignmentArg(const Symbol &, const DummyArgument &, int);
84   void CheckSpecificsAreDistinguishable(const Symbol &, const GenericDetails &);
85   void CheckEquivalenceSet(const EquivalenceSet &);
86   void CheckBlockData(const Scope &);
87   void CheckGenericOps(const Scope &);
88   bool CheckConflicting(const Symbol &, Attr, Attr);
89   void WarnMissingFinal(const Symbol &);
90   bool InPure() const {
91     return innermostSymbol_ && IsPureProcedure(*innermostSymbol_);
92   }
93   bool InElemental() const {
94     return innermostSymbol_ && innermostSymbol_->attrs().test(Attr::ELEMENTAL);
95   }
96   bool InFunction() const {
97     return innermostSymbol_ && IsFunction(*innermostSymbol_);
98   }
99   template <typename... A>
100   void SayWithDeclaration(const Symbol &symbol, A &&...x) {
101     if (parser::Message * msg{messages_.Say(std::forward<A>(x)...)}) {
102       if (messages_.at().begin() != symbol.name().begin()) {
103         evaluate::AttachDeclaration(*msg, symbol);
104       }
105     }
106   }
107   bool IsResultOkToDiffer(const FunctionResult &);
108   void CheckBindCName(const Symbol &);
109   // Check functions for defined I/O procedures
110   void CheckDefinedIoProc(
111       const Symbol &, const GenericDetails &, GenericKind::DefinedIo);
112   bool CheckDioDummyIsData(const Symbol &, const Symbol *, std::size_t);
113   void CheckDioDummyIsDerived(
114       const Symbol &, const Symbol &, GenericKind::DefinedIo ioKind);
115   void CheckDioDummyIsDefaultInteger(const Symbol &, const Symbol &);
116   void CheckDioDummyIsScalar(const Symbol &, const Symbol &);
117   void CheckDioDummyAttrs(const Symbol &, const Symbol &, Attr);
118   void CheckDioDtvArg(const Symbol &, const Symbol *, GenericKind::DefinedIo);
119   void CheckDefaultIntegerArg(const Symbol &, const Symbol *, Attr);
120   void CheckDioAssumedLenCharacterArg(
121       const Symbol &, const Symbol *, std::size_t, Attr);
122   void CheckDioVlistArg(const Symbol &, const Symbol *, std::size_t);
123   void CheckDioArgCount(
124       const Symbol &, GenericKind::DefinedIo ioKind, std::size_t);
125   struct TypeWithDefinedIo {
126     const DerivedTypeSpec *type;
127     GenericKind::DefinedIo ioKind;
128     const Symbol &proc;
129   };
130   void CheckAlreadySeenDefinedIo(
131       const DerivedTypeSpec *, GenericKind::DefinedIo, const Symbol &);
132 
133   SemanticsContext &context_;
134   evaluate::FoldingContext &foldingContext_{context_.foldingContext()};
135   parser::ContextualMessages &messages_{foldingContext_.messages()};
136   const Scope *scope_{nullptr};
137   bool scopeIsUninstantiatedPDT_{false};
138   // This symbol is the one attached to the innermost enclosing scope
139   // that has a symbol.
140   const Symbol *innermostSymbol_{nullptr};
141   // Cache of calls to Procedure::Characterize(Symbol)
142   std::map<SymbolRef, std::optional<Procedure>, SymbolAddressCompare>
143       characterizeCache_;
144   // Collection of symbols with BIND(C) names
145   std::map<std::string, SymbolRef> bindC_;
146   // Derived types that have defined input/output procedures
147   std::vector<TypeWithDefinedIo> seenDefinedIoTypes_;
148 };
149 
150 class DistinguishabilityHelper {
151 public:
152   DistinguishabilityHelper(SemanticsContext &context) : context_{context} {}
153   void Add(const Symbol &, GenericKind, const Symbol &, const Procedure &);
154   void Check(const Scope &);
155 
156 private:
157   void SayNotDistinguishable(const Scope &, const SourceName &, GenericKind,
158       const Symbol &, const Symbol &);
159   void AttachDeclaration(parser::Message &, const Scope &, const Symbol &);
160 
161   SemanticsContext &context_;
162   struct ProcedureInfo {
163     GenericKind kind;
164     const Symbol &symbol;
165     const Procedure &procedure;
166   };
167   std::map<SourceName, std::vector<ProcedureInfo>> nameToInfo_;
168 };
169 
170 void CheckHelper::Check(const ParamValue &value, bool canBeAssumed) {
171   if (value.isAssumed()) {
172     if (!canBeAssumed) { // C795, C721, C726
173       messages_.Say(
174           "An assumed (*) type parameter may be used only for a (non-statement"
175           " function) dummy argument, associate name, named constant, or"
176           " external function result"_err_en_US);
177     }
178   } else {
179     CheckSpecExpr(value.GetExplicit());
180   }
181 }
182 
183 void CheckHelper::Check(const ArraySpec &shape) {
184   for (const auto &spec : shape) {
185     Check(spec);
186   }
187 }
188 
189 void CheckHelper::Check(
190     const DeclTypeSpec &type, bool canHaveAssumedTypeParameters) {
191   if (type.category() == DeclTypeSpec::Character) {
192     Check(type.characterTypeSpec().length(), canHaveAssumedTypeParameters);
193   } else if (const DerivedTypeSpec * derived{type.AsDerived()}) {
194     for (auto &parm : derived->parameters()) {
195       Check(parm.second, canHaveAssumedTypeParameters);
196     }
197   }
198 }
199 
200 void CheckHelper::Check(const Symbol &symbol) {
201   if (context_.HasError(symbol)) {
202     return;
203   }
204   auto restorer{messages_.SetLocation(symbol.name())};
205   context_.set_location(symbol.name());
206   const DeclTypeSpec *type{symbol.GetType()};
207   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
208   bool isDone{false};
209   std::visit(
210       common::visitors{
211           [&](const UseDetails &x) { isDone = true; },
212           [&](const HostAssocDetails &x) {
213             CheckHostAssoc(symbol, x);
214             isDone = true;
215           },
216           [&](const ProcBindingDetails &x) {
217             CheckProcBinding(symbol, x);
218             isDone = true;
219           },
220           [&](const ObjectEntityDetails &x) { CheckObjectEntity(symbol, x); },
221           [&](const ProcEntityDetails &x) { CheckProcEntity(symbol, x); },
222           [&](const SubprogramDetails &x) { CheckSubprogram(symbol, x); },
223           [&](const DerivedTypeDetails &x) { CheckDerivedType(symbol, x); },
224           [&](const GenericDetails &x) { CheckGeneric(symbol, x); },
225           [](const auto &) {},
226       },
227       symbol.details());
228   if (symbol.attrs().test(Attr::VOLATILE)) {
229     CheckVolatile(symbol, derived);
230   }
231   CheckBindCName(symbol);
232   if (isDone) {
233     return; // following checks do not apply
234   }
235   if (IsPointer(symbol)) {
236     CheckPointer(symbol);
237   }
238   if (InPure()) {
239     if (IsSaved(symbol)) {
240       messages_.Say(
241           "A pure subprogram may not have a variable with the SAVE attribute"_err_en_US);
242     }
243     if (symbol.attrs().test(Attr::VOLATILE)) {
244       messages_.Say(
245           "A pure subprogram may not have a variable with the VOLATILE attribute"_err_en_US);
246     }
247     if (IsProcedure(symbol) && !IsPureProcedure(symbol) && IsDummy(symbol)) {
248       messages_.Say(
249           "A dummy procedure of a pure subprogram must be pure"_err_en_US);
250     }
251     if (!IsDummy(symbol) && !IsFunctionResult(symbol)) {
252       if (IsPolymorphicAllocatable(symbol)) {
253         SayWithDeclaration(symbol,
254             "Deallocation of polymorphic object '%s' is not permitted in a pure subprogram"_err_en_US,
255             symbol.name());
256       } else if (derived) {
257         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
258           SayWithDeclaration(*bad,
259               "Deallocation of polymorphic object '%s%s' is not permitted in a pure subprogram"_err_en_US,
260               symbol.name(), bad.BuildResultDesignatorName());
261         }
262       }
263     }
264   }
265   if (type) { // Section 7.2, paragraph 7
266     bool canHaveAssumedParameter{IsNamedConstant(symbol) ||
267         (IsAssumedLengthCharacter(symbol) && // C722
268             IsExternal(symbol)) ||
269         symbol.test(Symbol::Flag::ParentComp)};
270     if (!IsStmtFunctionDummy(symbol)) { // C726
271       if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
272         canHaveAssumedParameter |= object->isDummy() ||
273             (object->isFuncResult() &&
274                 type->category() == DeclTypeSpec::Character) ||
275             IsStmtFunctionResult(symbol); // Avoids multiple messages
276       } else {
277         canHaveAssumedParameter |= symbol.has<AssocEntityDetails>();
278       }
279     }
280     Check(*type, canHaveAssumedParameter);
281     if (InPure() && InFunction() && IsFunctionResult(symbol)) {
282       if (derived && HasImpureFinal(*derived)) { // C1584
283         messages_.Say(
284             "Result of pure function may not have an impure FINAL subroutine"_err_en_US);
285       }
286       if (type->IsPolymorphic() && IsAllocatable(symbol)) { // C1585
287         messages_.Say(
288             "Result of pure function may not be both polymorphic and ALLOCATABLE"_err_en_US);
289       }
290       if (derived) {
291         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
292           SayWithDeclaration(*bad,
293               "Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%s'"_err_en_US,
294               bad.BuildResultDesignatorName());
295         }
296       }
297     }
298   }
299   if (IsAssumedLengthCharacter(symbol) && IsExternal(symbol)) { // C723
300     if (symbol.attrs().test(Attr::RECURSIVE)) {
301       messages_.Say(
302           "An assumed-length CHARACTER(*) function cannot be RECURSIVE"_err_en_US);
303     }
304     if (symbol.Rank() > 0) {
305       messages_.Say(
306           "An assumed-length CHARACTER(*) function cannot return an array"_err_en_US);
307     }
308     if (symbol.attrs().test(Attr::PURE)) {
309       messages_.Say(
310           "An assumed-length CHARACTER(*) function cannot be PURE"_err_en_US);
311     }
312     if (symbol.attrs().test(Attr::ELEMENTAL)) {
313       messages_.Say(
314           "An assumed-length CHARACTER(*) function cannot be ELEMENTAL"_err_en_US);
315     }
316     if (const Symbol * result{FindFunctionResult(symbol)}) {
317       if (IsPointer(*result)) {
318         messages_.Say(
319             "An assumed-length CHARACTER(*) function cannot return a POINTER"_err_en_US);
320       }
321     }
322   }
323   if (symbol.attrs().test(Attr::VALUE)) {
324     CheckValue(symbol, derived);
325   }
326   if (symbol.attrs().test(Attr::CONTIGUOUS) && IsPointer(symbol) &&
327       symbol.Rank() == 0) { // C830
328     messages_.Say("CONTIGUOUS POINTER must be an array"_err_en_US);
329   }
330   if (IsDummy(symbol)) {
331     if (IsNamedConstant(symbol)) {
332       messages_.Say(
333           "A dummy argument may not also be a named constant"_err_en_US);
334     }
335     if (!symbol.test(Symbol::Flag::InDataStmt) /*caught elsewhere*/ &&
336         IsSaved(symbol)) {
337       messages_.Say(
338           "A dummy argument may not have the SAVE attribute"_err_en_US);
339     }
340   } else if (IsFunctionResult(symbol)) {
341     if (!symbol.test(Symbol::Flag::InDataStmt) /*caught elsewhere*/ &&
342         IsSaved(symbol)) {
343       messages_.Say(
344           "A function result may not have the SAVE attribute"_err_en_US);
345     }
346   }
347   if (symbol.owner().IsDerivedType() &&
348       (symbol.attrs().test(Attr::CONTIGUOUS) &&
349           !(IsPointer(symbol) && symbol.Rank() > 0))) { // C752
350     messages_.Say(
351         "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
352   }
353   if (symbol.owner().IsModule() && IsAutomatic(symbol)) {
354     messages_.Say(
355         "Automatic data object '%s' may not appear in the specification part"
356         " of a module"_err_en_US,
357         symbol.name());
358   }
359 }
360 
361 void CheckHelper::CheckValue(
362     const Symbol &symbol, const DerivedTypeSpec *derived) { // C863 - C865
363   if (!IsDummy(symbol)) {
364     messages_.Say(
365         "VALUE attribute may apply only to a dummy argument"_err_en_US);
366   }
367   if (IsProcedure(symbol)) {
368     messages_.Say(
369         "VALUE attribute may apply only to a dummy data object"_err_en_US);
370   }
371   if (IsAssumedSizeArray(symbol)) {
372     messages_.Say(
373         "VALUE attribute may not apply to an assumed-size array"_err_en_US);
374   }
375   if (IsCoarray(symbol)) {
376     messages_.Say("VALUE attribute may not apply to a coarray"_err_en_US);
377   }
378   if (IsAllocatable(symbol)) {
379     messages_.Say("VALUE attribute may not apply to an ALLOCATABLE"_err_en_US);
380   } else if (IsPointer(symbol)) {
381     messages_.Say("VALUE attribute may not apply to a POINTER"_err_en_US);
382   }
383   if (IsIntentInOut(symbol)) {
384     messages_.Say(
385         "VALUE attribute may not apply to an INTENT(IN OUT) argument"_err_en_US);
386   } else if (IsIntentOut(symbol)) {
387     messages_.Say(
388         "VALUE attribute may not apply to an INTENT(OUT) argument"_err_en_US);
389   }
390   if (symbol.attrs().test(Attr::VOLATILE)) {
391     messages_.Say("VALUE attribute may not apply to a VOLATILE"_err_en_US);
392   }
393   if (innermostSymbol_ && IsBindCProcedure(*innermostSymbol_) &&
394       IsOptional(symbol)) {
395     messages_.Say(
396         "VALUE attribute may not apply to an OPTIONAL in a BIND(C) procedure"_err_en_US);
397   }
398   if (derived) {
399     if (FindCoarrayUltimateComponent(*derived)) {
400       messages_.Say(
401           "VALUE attribute may not apply to a type with a coarray ultimate component"_err_en_US);
402     }
403   }
404 }
405 
406 void CheckHelper::CheckAssumedTypeEntity( // C709
407     const Symbol &symbol, const ObjectEntityDetails &details) {
408   if (const DeclTypeSpec * type{symbol.GetType()};
409       type && type->category() == DeclTypeSpec::TypeStar) {
410     if (!IsDummy(symbol)) {
411       messages_.Say(
412           "Assumed-type entity '%s' must be a dummy argument"_err_en_US,
413           symbol.name());
414     } else {
415       if (symbol.attrs().test(Attr::ALLOCATABLE)) {
416         messages_.Say("Assumed-type argument '%s' cannot have the ALLOCATABLE"
417                       " attribute"_err_en_US,
418             symbol.name());
419       }
420       if (symbol.attrs().test(Attr::POINTER)) {
421         messages_.Say("Assumed-type argument '%s' cannot have the POINTER"
422                       " attribute"_err_en_US,
423             symbol.name());
424       }
425       if (symbol.attrs().test(Attr::VALUE)) {
426         messages_.Say("Assumed-type argument '%s' cannot have the VALUE"
427                       " attribute"_err_en_US,
428             symbol.name());
429       }
430       if (symbol.attrs().test(Attr::INTENT_OUT)) {
431         messages_.Say(
432             "Assumed-type argument '%s' cannot be INTENT(OUT)"_err_en_US,
433             symbol.name());
434       }
435       if (IsCoarray(symbol)) {
436         messages_.Say(
437             "Assumed-type argument '%s' cannot be a coarray"_err_en_US,
438             symbol.name());
439       }
440       if (details.IsArray() && details.shape().IsExplicitShape()) {
441         messages_.Say(
442             "Assumed-type array argument 'arg8' must be assumed shape,"
443             " assumed size, or assumed rank"_err_en_US,
444             symbol.name());
445       }
446     }
447   }
448 }
449 
450 void CheckHelper::CheckObjectEntity(
451     const Symbol &symbol, const ObjectEntityDetails &details) {
452   CheckArraySpec(symbol, details.shape());
453   Check(details.shape());
454   Check(details.coshape());
455   CheckAssumedTypeEntity(symbol, details);
456   WarnMissingFinal(symbol);
457   if (!details.coshape().empty()) {
458     bool isDeferredCoshape{details.coshape().IsDeferredShape()};
459     if (IsAllocatable(symbol)) {
460       if (!isDeferredCoshape) { // C827
461         messages_.Say("'%s' is an ALLOCATABLE coarray and must have a deferred"
462                       " coshape"_err_en_US,
463             symbol.name());
464       }
465     } else if (symbol.owner().IsDerivedType()) { // C746
466       std::string deferredMsg{
467           isDeferredCoshape ? "" : " and have a deferred coshape"};
468       messages_.Say("Component '%s' is a coarray and must have the ALLOCATABLE"
469                     " attribute%s"_err_en_US,
470           symbol.name(), deferredMsg);
471     } else {
472       if (!details.coshape().IsAssumedSize()) { // C828
473         messages_.Say(
474             "'%s' is a non-ALLOCATABLE coarray and must have an explicit coshape"_err_en_US,
475             symbol.name());
476       }
477     }
478     if (const DeclTypeSpec * type{details.type()}) {
479       if (IsBadCoarrayType(type->AsDerived())) { // C747 & C824
480         messages_.Say(
481             "Coarray '%s' may not have type TEAM_TYPE, C_PTR, or C_FUNPTR"_err_en_US,
482             symbol.name());
483       }
484     }
485   }
486   if (details.isDummy()) {
487     if (symbol.attrs().test(Attr::INTENT_OUT)) {
488       if (FindUltimateComponent(symbol, [](const Symbol &x) {
489             return IsCoarray(x) && IsAllocatable(x);
490           })) { // C846
491         messages_.Say(
492             "An INTENT(OUT) dummy argument may not be, or contain, an ALLOCATABLE coarray"_err_en_US);
493       }
494       if (IsOrContainsEventOrLockComponent(symbol)) { // C847
495         messages_.Say(
496             "An INTENT(OUT) dummy argument may not be, or contain, EVENT_TYPE or LOCK_TYPE"_err_en_US);
497       }
498     }
499     if (InPure() && !IsStmtFunction(DEREF(innermostSymbol_)) &&
500         !IsPointer(symbol) && !IsIntentIn(symbol) &&
501         !symbol.attrs().test(Attr::VALUE)) {
502       if (InFunction()) { // C1583
503         messages_.Say(
504             "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
505       } else if (IsIntentOut(symbol)) {
506         if (const DeclTypeSpec * type{details.type()}) {
507           if (type && type->IsPolymorphic()) { // C1588
508             messages_.Say(
509                 "An INTENT(OUT) dummy argument of a pure subroutine may not be polymorphic"_err_en_US);
510           } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
511             if (FindUltimateComponent(*derived, [](const Symbol &x) {
512                   const DeclTypeSpec *type{x.GetType()};
513                   return type && type->IsPolymorphic();
514                 })) { // C1588
515               messages_.Say(
516                   "An INTENT(OUT) dummy argument of a pure subroutine may not have a polymorphic ultimate component"_err_en_US);
517             }
518             if (HasImpureFinal(*derived)) { // C1587
519               messages_.Say(
520                   "An INTENT(OUT) dummy argument of a pure subroutine may not have an impure FINAL subroutine"_err_en_US);
521             }
522           }
523         }
524       } else if (!IsIntentInOut(symbol)) { // C1586
525         messages_.Say(
526             "non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute"_err_en_US);
527       }
528     }
529   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
530       symbol.attrs().test(Attr::INTENT_OUT) ||
531       symbol.attrs().test(Attr::INTENT_INOUT)) {
532     messages_.Say("INTENT attributes may apply only to a dummy "
533                   "argument"_err_en_US); // C843
534   } else if (IsOptional(symbol)) {
535     messages_.Say("OPTIONAL attribute may apply only to a dummy "
536                   "argument"_err_en_US); // C849
537   }
538   if (InElemental()) {
539     if (details.isDummy()) { // C15100
540       if (details.shape().Rank() > 0) {
541         messages_.Say(
542             "A dummy argument of an ELEMENTAL procedure must be scalar"_err_en_US);
543       }
544       if (IsAllocatable(symbol)) {
545         messages_.Say(
546             "A dummy argument of an ELEMENTAL procedure may not be ALLOCATABLE"_err_en_US);
547       }
548       if (IsCoarray(symbol)) {
549         messages_.Say(
550             "A dummy argument of an ELEMENTAL procedure may not be a coarray"_err_en_US);
551       }
552       if (IsPointer(symbol)) {
553         messages_.Say(
554             "A dummy argument of an ELEMENTAL procedure may not be a POINTER"_err_en_US);
555       }
556       if (!symbol.attrs().HasAny(Attrs{Attr::VALUE, Attr::INTENT_IN,
557               Attr::INTENT_INOUT, Attr::INTENT_OUT})) { // C15102
558         messages_.Say(
559             "A dummy argument of an ELEMENTAL procedure must have an INTENT() or VALUE attribute"_err_en_US);
560       }
561     } else if (IsFunctionResult(symbol)) { // C15101
562       if (details.shape().Rank() > 0) {
563         messages_.Say(
564             "The result of an ELEMENTAL function must be scalar"_err_en_US);
565       }
566       if (IsAllocatable(symbol)) {
567         messages_.Say(
568             "The result of an ELEMENTAL function may not be ALLOCATABLE"_err_en_US);
569       }
570       if (IsPointer(symbol)) {
571         messages_.Say(
572             "The result of an ELEMENTAL function may not be a POINTER"_err_en_US);
573       }
574     }
575   }
576   if (HasDeclarationInitializer(symbol)) { // C808; ignore DATA initialization
577     CheckPointerInitialization(symbol);
578     if (IsAutomatic(symbol)) {
579       messages_.Say(
580           "An automatic variable or component must not be initialized"_err_en_US);
581     } else if (IsDummy(symbol)) {
582       messages_.Say("A dummy argument must not be initialized"_err_en_US);
583     } else if (IsFunctionResult(symbol)) {
584       messages_.Say("A function result must not be initialized"_err_en_US);
585     } else if (IsInBlankCommon(symbol)) {
586       messages_.Say(
587           "A variable in blank COMMON should not be initialized"_en_US);
588     }
589   }
590   if (symbol.owner().kind() == Scope::Kind::BlockData) {
591     if (IsAllocatable(symbol)) {
592       messages_.Say(
593           "An ALLOCATABLE variable may not appear in a BLOCK DATA subprogram"_err_en_US);
594     } else if (IsInitialized(symbol) && !FindCommonBlockContaining(symbol)) {
595       messages_.Say(
596           "An initialized variable in BLOCK DATA must be in a COMMON block"_err_en_US);
597     }
598   }
599   if (const DeclTypeSpec * type{details.type()}) { // C708
600     if (type->IsPolymorphic() &&
601         !(type->IsAssumedType() || IsAllocatableOrPointer(symbol) ||
602             IsDummy(symbol))) {
603       messages_.Say("CLASS entity '%s' must be a dummy argument or have "
604                     "ALLOCATABLE or POINTER attribute"_err_en_US,
605           symbol.name());
606     }
607   }
608 }
609 
610 void CheckHelper::CheckPointerInitialization(const Symbol &symbol) {
611   if (IsPointer(symbol) && !context_.HasError(symbol) &&
612       !scopeIsUninstantiatedPDT_) {
613     if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
614       if (object->init()) { // C764, C765; C808
615         if (auto designator{evaluate::AsGenericExpr(symbol)}) {
616           auto restorer{messages_.SetLocation(symbol.name())};
617           context_.set_location(symbol.name());
618           CheckInitialTarget(foldingContext_, *designator, *object->init());
619         }
620       }
621     } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
622       if (proc->init() && *proc->init()) {
623         // C1519 - must be nonelemental external or module procedure,
624         // or an unrestricted specific intrinsic function.
625         const Symbol &ultimate{(*proc->init())->GetUltimate()};
626         if (ultimate.attrs().test(Attr::INTRINSIC)) {
627           if (!context_.intrinsics().IsSpecificIntrinsicFunction(
628                   ultimate.name().ToString())) { // C1030
629             context_.Say(
630                 "Intrinsic procedure '%s' is not a specific intrinsic permitted for use as the initializer for procedure pointer '%s'"_err_en_US,
631                 ultimate.name(), symbol.name());
632           }
633         } else if (!ultimate.attrs().test(Attr::EXTERNAL) &&
634             ultimate.owner().kind() != Scope::Kind::Module) {
635           context_.Say("Procedure pointer '%s' initializer '%s' is neither "
636                        "an external nor a module procedure"_err_en_US,
637               symbol.name(), ultimate.name());
638         } else if (ultimate.attrs().test(Attr::ELEMENTAL)) {
639           context_.Say("Procedure pointer '%s' cannot be initialized with the "
640                        "elemental procedure '%s"_err_en_US,
641               symbol.name(), ultimate.name());
642         } else {
643           // TODO: Check the "shalls" in the 15.4.3.6 paragraphs 7-10.
644         }
645       }
646     }
647   }
648 }
649 
650 // The six different kinds of array-specs:
651 //   array-spec     -> explicit-shape-list | deferred-shape-list
652 //                     | assumed-shape-list | implied-shape-list
653 //                     | assumed-size | assumed-rank
654 //   explicit-shape -> [ lb : ] ub
655 //   deferred-shape -> :
656 //   assumed-shape  -> [ lb ] :
657 //   implied-shape  -> [ lb : ] *
658 //   assumed-size   -> [ explicit-shape-list , ] [ lb : ] *
659 //   assumed-rank   -> ..
660 // Note:
661 // - deferred-shape is also an assumed-shape
662 // - A single "*" or "lb:*" might be assumed-size or implied-shape-list
663 void CheckHelper::CheckArraySpec(
664     const Symbol &symbol, const ArraySpec &arraySpec) {
665   if (arraySpec.Rank() == 0) {
666     return;
667   }
668   bool isExplicit{arraySpec.IsExplicitShape()};
669   bool isDeferred{arraySpec.IsDeferredShape()};
670   bool isImplied{arraySpec.IsImpliedShape()};
671   bool isAssumedShape{arraySpec.IsAssumedShape()};
672   bool isAssumedSize{arraySpec.IsAssumedSize()};
673   bool isAssumedRank{arraySpec.IsAssumedRank()};
674   std::optional<parser::MessageFixedText> msg;
675   if (symbol.test(Symbol::Flag::CrayPointee) && !isExplicit && !isAssumedSize) {
676     msg = "Cray pointee '%s' must have must have explicit shape or"
677           " assumed size"_err_en_US;
678   } else if (IsAllocatableOrPointer(symbol) && !isDeferred && !isAssumedRank) {
679     if (symbol.owner().IsDerivedType()) { // C745
680       if (IsAllocatable(symbol)) {
681         msg = "Allocatable array component '%s' must have"
682               " deferred shape"_err_en_US;
683       } else {
684         msg = "Array pointer component '%s' must have deferred shape"_err_en_US;
685       }
686     } else {
687       if (IsAllocatable(symbol)) { // C832
688         msg = "Allocatable array '%s' must have deferred shape or"
689               " assumed rank"_err_en_US;
690       } else {
691         msg = "Array pointer '%s' must have deferred shape or"
692               " assumed rank"_err_en_US;
693       }
694     }
695   } else if (IsDummy(symbol)) {
696     if (isImplied && !isAssumedSize) { // C836
697       msg = "Dummy array argument '%s' may not have implied shape"_err_en_US;
698     }
699   } else if (isAssumedShape && !isDeferred) {
700     msg = "Assumed-shape array '%s' must be a dummy argument"_err_en_US;
701   } else if (isAssumedSize && !isImplied) { // C833
702     msg = "Assumed-size array '%s' must be a dummy argument"_err_en_US;
703   } else if (isAssumedRank) { // C837
704     msg = "Assumed-rank array '%s' must be a dummy argument"_err_en_US;
705   } else if (isImplied) {
706     if (!IsNamedConstant(symbol)) { // C835, C836
707       msg = "Implied-shape array '%s' must be a named constant or a "
708             "dummy argument"_err_en_US;
709     }
710   } else if (IsNamedConstant(symbol)) {
711     if (!isExplicit && !isImplied) {
712       msg = "Named constant '%s' array must have constant or"
713             " implied shape"_err_en_US;
714     }
715   } else if (!IsAllocatableOrPointer(symbol) && !isExplicit) {
716     if (symbol.owner().IsDerivedType()) { // C749
717       msg = "Component array '%s' without ALLOCATABLE or POINTER attribute must"
718             " have explicit shape"_err_en_US;
719     } else { // C816
720       msg = "Array '%s' without ALLOCATABLE or POINTER attribute must have"
721             " explicit shape"_err_en_US;
722     }
723   }
724   if (msg) {
725     context_.Say(std::move(*msg), symbol.name());
726   }
727 }
728 
729 void CheckHelper::CheckProcEntity(
730     const Symbol &symbol, const ProcEntityDetails &details) {
731   if (details.isDummy()) {
732     if (!symbol.attrs().test(Attr::POINTER) && // C843
733         (symbol.attrs().test(Attr::INTENT_IN) ||
734             symbol.attrs().test(Attr::INTENT_OUT) ||
735             symbol.attrs().test(Attr::INTENT_INOUT))) {
736       messages_.Say("A dummy procedure without the POINTER attribute"
737                     " may not have an INTENT attribute"_err_en_US);
738     }
739     if (InElemental()) { // C15100
740       messages_.Say(
741           "An ELEMENTAL subprogram may not have a dummy procedure"_err_en_US);
742     }
743     const Symbol *interface { details.interface().symbol() };
744     if (!symbol.attrs().test(Attr::INTRINSIC) &&
745         (symbol.attrs().test(Attr::ELEMENTAL) ||
746             (interface && !interface->attrs().test(Attr::INTRINSIC) &&
747                 interface->attrs().test(Attr::ELEMENTAL)))) {
748       // There's no explicit constraint or "shall" that we can find in the
749       // standard for this check, but it seems to be implied in multiple
750       // sites, and ELEMENTAL non-intrinsic actual arguments *are*
751       // explicitly forbidden.  But we allow "PROCEDURE(SIN)::dummy"
752       // because it is explicitly legal to *pass* the specific intrinsic
753       // function SIN as an actual argument.
754       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
755     }
756   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
757       symbol.attrs().test(Attr::INTENT_OUT) ||
758       symbol.attrs().test(Attr::INTENT_INOUT)) {
759     messages_.Say("INTENT attributes may apply only to a dummy "
760                   "argument"_err_en_US); // C843
761   } else if (IsOptional(symbol)) {
762     messages_.Say("OPTIONAL attribute may apply only to a dummy "
763                   "argument"_err_en_US); // C849
764   } else if (symbol.owner().IsDerivedType()) {
765     if (!symbol.attrs().test(Attr::POINTER)) { // C756
766       const auto &name{symbol.name()};
767       messages_.Say(name,
768           "Procedure component '%s' must have POINTER attribute"_err_en_US,
769           name);
770     }
771     CheckPassArg(symbol, details.interface().symbol(), details);
772   }
773   if (symbol.attrs().test(Attr::POINTER)) {
774     CheckPointerInitialization(symbol);
775     if (const Symbol * interface{details.interface().symbol()}) {
776       if (interface->attrs().test(Attr::INTRINSIC)) {
777         if (!context_.intrinsics().IsSpecificIntrinsicFunction(
778                 interface->name().ToString())) { // C1515
779           messages_.Say(
780               "Intrinsic procedure '%s' is not a specific intrinsic permitted for use as the definition of the interface to procedure pointer '%s'"_err_en_US,
781               interface->name(), symbol.name());
782         }
783       } else if (interface->attrs().test(Attr::ELEMENTAL)) {
784         messages_.Say("Procedure pointer '%s' may not be ELEMENTAL"_err_en_US,
785             symbol.name()); // C1517
786       }
787     }
788   } else if (symbol.attrs().test(Attr::SAVE)) {
789     messages_.Say(
790         "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US,
791         symbol.name());
792   }
793 }
794 
795 // When a module subprogram has the MODULE prefix the following must match
796 // with the corresponding separate module procedure interface body:
797 // - C1549: characteristics and dummy argument names
798 // - C1550: binding label
799 // - C1551: NON_RECURSIVE prefix
800 class SubprogramMatchHelper {
801 public:
802   explicit SubprogramMatchHelper(CheckHelper &checkHelper)
803       : checkHelper{checkHelper} {}
804 
805   void Check(const Symbol &, const Symbol &);
806 
807 private:
808   SemanticsContext &context() { return checkHelper.context(); }
809   void CheckDummyArg(const Symbol &, const Symbol &, const DummyArgument &,
810       const DummyArgument &);
811   void CheckDummyDataObject(const Symbol &, const Symbol &,
812       const DummyDataObject &, const DummyDataObject &);
813   void CheckDummyProcedure(const Symbol &, const Symbol &,
814       const DummyProcedure &, const DummyProcedure &);
815   bool CheckSameIntent(
816       const Symbol &, const Symbol &, common::Intent, common::Intent);
817   template <typename... A>
818   void Say(
819       const Symbol &, const Symbol &, parser::MessageFixedText &&, A &&...);
820   template <typename ATTRS>
821   bool CheckSameAttrs(const Symbol &, const Symbol &, ATTRS, ATTRS);
822   bool ShapesAreCompatible(const DummyDataObject &, const DummyDataObject &);
823   evaluate::Shape FoldShape(const evaluate::Shape &);
824   std::string AsFortran(DummyDataObject::Attr attr) {
825     return parser::ToUpperCaseLetters(DummyDataObject::EnumToString(attr));
826   }
827   std::string AsFortran(DummyProcedure::Attr attr) {
828     return parser::ToUpperCaseLetters(DummyProcedure::EnumToString(attr));
829   }
830 
831   CheckHelper &checkHelper;
832 };
833 
834 // 15.6.2.6 para 3 - can the result of an ENTRY differ from its function?
835 bool CheckHelper::IsResultOkToDiffer(const FunctionResult &result) {
836   if (result.attrs.test(FunctionResult::Attr::Allocatable) ||
837       result.attrs.test(FunctionResult::Attr::Pointer)) {
838     return false;
839   }
840   const auto *typeAndShape{result.GetTypeAndShape()};
841   if (!typeAndShape || typeAndShape->Rank() != 0) {
842     return false;
843   }
844   auto category{typeAndShape->type().category()};
845   if (category == TypeCategory::Character ||
846       category == TypeCategory::Derived) {
847     return false;
848   }
849   int kind{typeAndShape->type().kind()};
850   return kind == context_.GetDefaultKind(category) ||
851       (category == TypeCategory::Real &&
852           kind == context_.doublePrecisionKind());
853 }
854 
855 void CheckHelper::CheckSubprogram(
856     const Symbol &symbol, const SubprogramDetails &details) {
857   if (const Symbol * iface{FindSeparateModuleSubprogramInterface(&symbol)}) {
858     SubprogramMatchHelper{*this}.Check(symbol, *iface);
859   }
860   if (const Scope * entryScope{details.entryScope()}) {
861     // ENTRY 15.6.2.6, esp. C1571
862     std::optional<parser::MessageFixedText> error;
863     const Symbol *subprogram{entryScope->symbol()};
864     const SubprogramDetails *subprogramDetails{nullptr};
865     if (subprogram) {
866       subprogramDetails = subprogram->detailsIf<SubprogramDetails>();
867     }
868     if (entryScope->kind() != Scope::Kind::Subprogram) {
869       error = "ENTRY may appear only in a subroutine or function"_err_en_US;
870     } else if (!(entryScope->parent().IsGlobal() ||
871                    entryScope->parent().IsModule() ||
872                    entryScope->parent().IsSubmodule())) {
873       error = "ENTRY may not appear in an internal subprogram"_err_en_US;
874     } else if (FindSeparateModuleSubprogramInterface(subprogram)) {
875       error = "ENTRY may not appear in a separate module procedure"_err_en_US;
876     } else if (subprogramDetails && details.isFunction() &&
877         subprogramDetails->isFunction() &&
878         !context_.HasError(details.result()) &&
879         !context_.HasError(subprogramDetails->result())) {
880       auto result{FunctionResult::Characterize(
881           details.result(), context_.foldingContext())};
882       auto subpResult{FunctionResult::Characterize(
883           subprogramDetails->result(), context_.foldingContext())};
884       if (result && subpResult && *result != *subpResult &&
885           (!IsResultOkToDiffer(*result) || !IsResultOkToDiffer(*subpResult))) {
886         error =
887             "Result of ENTRY is not compatible with result of containing function"_err_en_US;
888       }
889     }
890     if (error) {
891       if (auto *msg{messages_.Say(symbol.name(), *error)}) {
892         if (subprogram) {
893           msg->Attach(subprogram->name(), "Containing subprogram"_en_US);
894         }
895       }
896     }
897   }
898   if (symbol.attrs().test(Attr::ELEMENTAL)) {
899     // See comment on the similar check in CheckProcEntity()
900     if (details.isDummy()) {
901       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
902     } else {
903       for (const Symbol *dummy : details.dummyArgs()) {
904         if (!dummy) { // C15100
905           messages_.Say(
906               "An ELEMENTAL subroutine may not have an alternate return dummy argument"_err_en_US);
907         }
908       }
909     }
910   }
911 }
912 
913 void CheckHelper::CheckDerivedType(
914     const Symbol &derivedType, const DerivedTypeDetails &details) {
915   if (details.isForwardReferenced() && !context_.HasError(derivedType)) {
916     messages_.Say("The derived type '%s' has not been defined"_err_en_US,
917         derivedType.name());
918   }
919   const Scope *scope{derivedType.scope()};
920   if (!scope) {
921     CHECK(details.isForwardReferenced());
922     return;
923   }
924   CHECK(scope->symbol() == &derivedType);
925   CHECK(scope->IsDerivedType());
926   if (derivedType.attrs().test(Attr::ABSTRACT) && // C734
927       (derivedType.attrs().test(Attr::BIND_C) || details.sequence())) {
928     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
929   }
930   if (const DeclTypeSpec * parent{FindParentTypeSpec(derivedType)}) {
931     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
932     if (!IsExtensibleType(parentDerived)) { // C705
933       messages_.Say("The parent type is not extensible"_err_en_US);
934     }
935     if (!derivedType.attrs().test(Attr::ABSTRACT) && parentDerived &&
936         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
937       ScopeComponentIterator components{*parentDerived};
938       for (const Symbol &component : components) {
939         if (component.attrs().test(Attr::DEFERRED)) {
940           if (scope->FindComponent(component.name()) == &component) {
941             SayWithDeclaration(component,
942                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
943                 parentDerived->typeSymbol().name(), component.name());
944           }
945         }
946       }
947     }
948     DerivedTypeSpec derived{derivedType.name(), derivedType};
949     derived.set_scope(*scope);
950     if (FindCoarrayUltimateComponent(derived) && // C736
951         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
952       messages_.Say(
953           "Type '%s' has a coarray ultimate component so the type at the base "
954           "of its type extension chain ('%s') must be a type that has a "
955           "coarray ultimate component"_err_en_US,
956           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
957     }
958     if (FindEventOrLockPotentialComponent(derived) && // C737
959         !(FindEventOrLockPotentialComponent(*parentDerived) ||
960             IsEventTypeOrLockType(parentDerived))) {
961       messages_.Say(
962           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
963           "at the base of its type extension chain ('%s') must either have an "
964           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
965           "LOCK_TYPE"_err_en_US,
966           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
967     }
968   }
969   if (HasIntrinsicTypeName(derivedType)) { // C729
970     messages_.Say("A derived type name cannot be the name of an intrinsic"
971                   " type"_err_en_US);
972   }
973   std::map<SourceName, SymbolRef> previous;
974   for (const auto &pair : details.finals()) {
975     SourceName source{pair.first};
976     const Symbol &ref{*pair.second};
977     if (CheckFinal(ref, source, derivedType) &&
978         std::all_of(previous.begin(), previous.end(),
979             [&](std::pair<SourceName, SymbolRef> prev) {
980               return CheckDistinguishableFinals(
981                   ref, source, *prev.second, prev.first, derivedType);
982             })) {
983       previous.emplace(source, ref);
984     }
985   }
986 }
987 
988 // C786
989 bool CheckHelper::CheckFinal(
990     const Symbol &subroutine, SourceName finalName, const Symbol &derivedType) {
991   if (!IsModuleProcedure(subroutine)) {
992     SayWithDeclaration(subroutine, finalName,
993         "FINAL subroutine '%s' of derived type '%s' must be a module procedure"_err_en_US,
994         subroutine.name(), derivedType.name());
995     return false;
996   }
997   const Procedure *proc{Characterize(subroutine)};
998   if (!proc) {
999     return false; // error recovery
1000   }
1001   if (!proc->IsSubroutine()) {
1002     SayWithDeclaration(subroutine, finalName,
1003         "FINAL subroutine '%s' of derived type '%s' must be a subroutine"_err_en_US,
1004         subroutine.name(), derivedType.name());
1005     return false;
1006   }
1007   if (proc->dummyArguments.size() != 1) {
1008     SayWithDeclaration(subroutine, finalName,
1009         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument"_err_en_US,
1010         subroutine.name(), derivedType.name());
1011     return false;
1012   }
1013   const auto &arg{proc->dummyArguments[0]};
1014   const Symbol *errSym{&subroutine};
1015   if (const auto *details{subroutine.detailsIf<SubprogramDetails>()}) {
1016     if (!details->dummyArgs().empty()) {
1017       if (const Symbol * argSym{details->dummyArgs()[0]}) {
1018         errSym = argSym;
1019       }
1020     }
1021   }
1022   const auto *ddo{std::get_if<DummyDataObject>(&arg.u)};
1023   if (!ddo) {
1024     SayWithDeclaration(subroutine, finalName,
1025         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument that is a data object"_err_en_US,
1026         subroutine.name(), derivedType.name());
1027     return false;
1028   }
1029   bool ok{true};
1030   if (arg.IsOptional()) {
1031     SayWithDeclaration(*errSym, finalName,
1032         "FINAL subroutine '%s' of derived type '%s' must not have an OPTIONAL dummy argument"_err_en_US,
1033         subroutine.name(), derivedType.name());
1034     ok = false;
1035   }
1036   if (ddo->attrs.test(DummyDataObject::Attr::Allocatable)) {
1037     SayWithDeclaration(*errSym, finalName,
1038         "FINAL subroutine '%s' of derived type '%s' must not have an ALLOCATABLE dummy argument"_err_en_US,
1039         subroutine.name(), derivedType.name());
1040     ok = false;
1041   }
1042   if (ddo->attrs.test(DummyDataObject::Attr::Pointer)) {
1043     SayWithDeclaration(*errSym, finalName,
1044         "FINAL subroutine '%s' of derived type '%s' must not have a POINTER dummy argument"_err_en_US,
1045         subroutine.name(), derivedType.name());
1046     ok = false;
1047   }
1048   if (ddo->intent == common::Intent::Out) {
1049     SayWithDeclaration(*errSym, finalName,
1050         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with INTENT(OUT)"_err_en_US,
1051         subroutine.name(), derivedType.name());
1052     ok = false;
1053   }
1054   if (ddo->attrs.test(DummyDataObject::Attr::Value)) {
1055     SayWithDeclaration(*errSym, finalName,
1056         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with the VALUE attribute"_err_en_US,
1057         subroutine.name(), derivedType.name());
1058     ok = false;
1059   }
1060   if (ddo->type.corank() > 0) {
1061     SayWithDeclaration(*errSym, finalName,
1062         "FINAL subroutine '%s' of derived type '%s' must not have a coarray dummy argument"_err_en_US,
1063         subroutine.name(), derivedType.name());
1064     ok = false;
1065   }
1066   if (ddo->type.type().IsPolymorphic()) {
1067     SayWithDeclaration(*errSym, finalName,
1068         "FINAL subroutine '%s' of derived type '%s' must not have a polymorphic dummy argument"_err_en_US,
1069         subroutine.name(), derivedType.name());
1070     ok = false;
1071   } else if (ddo->type.type().category() != TypeCategory::Derived ||
1072       &ddo->type.type().GetDerivedTypeSpec().typeSymbol() != &derivedType) {
1073     SayWithDeclaration(*errSym, finalName,
1074         "FINAL subroutine '%s' of derived type '%s' must have a TYPE(%s) dummy argument"_err_en_US,
1075         subroutine.name(), derivedType.name(), derivedType.name());
1076     ok = false;
1077   } else { // check that all LEN type parameters are assumed
1078     for (auto ref : OrderParameterDeclarations(derivedType)) {
1079       if (IsLenTypeParameter(*ref)) {
1080         const auto *value{
1081             ddo->type.type().GetDerivedTypeSpec().FindParameter(ref->name())};
1082         if (!value || !value->isAssumed()) {
1083           SayWithDeclaration(*errSym, finalName,
1084               "FINAL subroutine '%s' of derived type '%s' must have a dummy argument with an assumed LEN type parameter '%s=*'"_err_en_US,
1085               subroutine.name(), derivedType.name(), ref->name());
1086           ok = false;
1087         }
1088       }
1089     }
1090   }
1091   return ok;
1092 }
1093 
1094 bool CheckHelper::CheckDistinguishableFinals(const Symbol &f1,
1095     SourceName f1Name, const Symbol &f2, SourceName f2Name,
1096     const Symbol &derivedType) {
1097   const Procedure *p1{Characterize(f1)};
1098   const Procedure *p2{Characterize(f2)};
1099   if (p1 && p2) {
1100     if (characteristics::Distinguishable(*p1, *p2)) {
1101       return true;
1102     }
1103     if (auto *msg{messages_.Say(f1Name,
1104             "FINAL subroutines '%s' and '%s' of derived type '%s' cannot be distinguished by rank or KIND type parameter value"_err_en_US,
1105             f1Name, f2Name, derivedType.name())}) {
1106       msg->Attach(f2Name, "FINAL declaration of '%s'"_en_US, f2.name())
1107           .Attach(f1.name(), "Definition of '%s'"_en_US, f1Name)
1108           .Attach(f2.name(), "Definition of '%s'"_en_US, f2Name);
1109     }
1110   }
1111   return false;
1112 }
1113 
1114 void CheckHelper::CheckHostAssoc(
1115     const Symbol &symbol, const HostAssocDetails &details) {
1116   const Symbol &hostSymbol{details.symbol()};
1117   if (hostSymbol.test(Symbol::Flag::ImplicitOrError)) {
1118     if (details.implicitOrSpecExprError) {
1119       messages_.Say("Implicitly typed local entity '%s' not allowed in"
1120                     " specification expression"_err_en_US,
1121           symbol.name());
1122     } else if (details.implicitOrExplicitTypeError) {
1123       messages_.Say(
1124           "No explicit type declared for '%s'"_err_en_US, symbol.name());
1125     }
1126   }
1127 }
1128 
1129 void CheckHelper::CheckGeneric(
1130     const Symbol &symbol, const GenericDetails &details) {
1131   CheckSpecificsAreDistinguishable(symbol, details);
1132   std::visit(common::visitors{
1133                  [&](const GenericKind::DefinedIo &io) {
1134                    CheckDefinedIoProc(symbol, details, io);
1135                  },
1136                  [](const auto &) {},
1137              },
1138       details.kind().u);
1139 }
1140 
1141 // Check that the specifics of this generic are distinguishable from each other
1142 void CheckHelper::CheckSpecificsAreDistinguishable(
1143     const Symbol &generic, const GenericDetails &details) {
1144   GenericKind kind{details.kind()};
1145   const SymbolVector &specifics{details.specificProcs()};
1146   std::size_t count{specifics.size()};
1147   if (count < 2 || !kind.IsName()) {
1148     return;
1149   }
1150   DistinguishabilityHelper helper{context_};
1151   for (const Symbol &specific : specifics) {
1152     if (const Procedure * procedure{Characterize(specific)}) {
1153       helper.Add(generic, kind, specific, *procedure);
1154     }
1155   }
1156   helper.Check(generic.owner());
1157 }
1158 
1159 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
1160   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1161   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1162   return Tristate::No ==
1163       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
1164 }
1165 
1166 static bool ConflictsWithIntrinsicOperator(
1167     const GenericKind &kind, const Procedure &proc) {
1168   if (!kind.IsIntrinsicOperator()) {
1169     return false;
1170   }
1171   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1172   auto type0{arg0.type()};
1173   if (proc.dummyArguments.size() == 1) { // unary
1174     return std::visit(
1175         common::visitors{
1176             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
1177             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
1178             [](const auto &) -> bool { DIE("bad generic kind"); },
1179         },
1180         kind.u);
1181   } else { // binary
1182     int rank0{arg0.Rank()};
1183     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1184     auto type1{arg1.type()};
1185     int rank1{arg1.Rank()};
1186     return std::visit(
1187         common::visitors{
1188             [&](common::NumericOperator) {
1189               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
1190             },
1191             [&](common::LogicalOperator) {
1192               return IsIntrinsicLogical(type0, rank0, type1, rank1);
1193             },
1194             [&](common::RelationalOperator opr) {
1195               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
1196             },
1197             [&](GenericKind::OtherKind x) {
1198               CHECK(x == GenericKind::OtherKind::Concat);
1199               return IsIntrinsicConcat(type0, rank0, type1, rank1);
1200             },
1201             [](const auto &) -> bool { DIE("bad generic kind"); },
1202         },
1203         kind.u);
1204   }
1205 }
1206 
1207 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
1208 bool CheckHelper::CheckDefinedOperator(SourceName opName, GenericKind kind,
1209     const Symbol &specific, const Procedure &proc) {
1210   if (context_.HasError(specific)) {
1211     return false;
1212   }
1213   std::optional<parser::MessageFixedText> msg;
1214   auto checkDefinedOperatorArgs{
1215       [&](SourceName opName, const Symbol &specific, const Procedure &proc) {
1216         bool arg0Defined{CheckDefinedOperatorArg(opName, specific, proc, 0)};
1217         bool arg1Defined{CheckDefinedOperatorArg(opName, specific, proc, 1)};
1218         return arg0Defined && arg1Defined;
1219       }};
1220   if (specific.attrs().test(Attr::NOPASS)) { // C774
1221     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
1222   } else if (!proc.functionResult.has_value()) {
1223     msg = "%s procedure '%s' must be a function"_err_en_US;
1224   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
1225     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
1226           " result"_err_en_US;
1227   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
1228     msg = std::move(m);
1229   } else if (!checkDefinedOperatorArgs(opName, specific, proc)) {
1230     return false; // error was reported
1231   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
1232     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
1233   } else {
1234     return true; // OK
1235   }
1236   SayWithDeclaration(
1237       specific, std::move(*msg), MakeOpName(opName), specific.name());
1238   context_.SetError(specific);
1239   return false;
1240 }
1241 
1242 // If the number of arguments is wrong for this intrinsic operator, return
1243 // false and return the error message in msg.
1244 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
1245     const GenericKind &kind, std::size_t nargs) {
1246   if (!kind.IsIntrinsicOperator()) {
1247     return std::nullopt;
1248   }
1249   std::size_t min{2}, max{2}; // allowed number of args; default is binary
1250   std::visit(common::visitors{
1251                  [&](const common::NumericOperator &x) {
1252                    if (x == common::NumericOperator::Add ||
1253                        x == common::NumericOperator::Subtract) {
1254                      min = 1; // + and - are unary or binary
1255                    }
1256                  },
1257                  [&](const common::LogicalOperator &x) {
1258                    if (x == common::LogicalOperator::Not) {
1259                      min = 1; // .NOT. is unary
1260                      max = 1;
1261                    }
1262                  },
1263                  [](const common::RelationalOperator &) {
1264                    // all are binary
1265                  },
1266                  [](const GenericKind::OtherKind &x) {
1267                    CHECK(x == GenericKind::OtherKind::Concat);
1268                  },
1269                  [](const auto &) { DIE("expected intrinsic operator"); },
1270              },
1271       kind.u);
1272   if (nargs >= min && nargs <= max) {
1273     return std::nullopt;
1274   } else if (max == 1) {
1275     return "%s function '%s' must have one dummy argument"_err_en_US;
1276   } else if (min == 2) {
1277     return "%s function '%s' must have two dummy arguments"_err_en_US;
1278   } else {
1279     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
1280   }
1281 }
1282 
1283 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
1284     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
1285   if (pos >= proc.dummyArguments.size()) {
1286     return true;
1287   }
1288   auto &arg{proc.dummyArguments.at(pos)};
1289   std::optional<parser::MessageFixedText> msg;
1290   if (arg.IsOptional()) {
1291     msg = "In %s function '%s', dummy argument '%s' may not be"
1292           " OPTIONAL"_err_en_US;
1293   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
1294              dataObject == nullptr) {
1295     msg = "In %s function '%s', dummy argument '%s' must be a"
1296           " data object"_err_en_US;
1297   } else if (dataObject->intent != common::Intent::In &&
1298       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1299     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
1300           " or VALUE attribute"_err_en_US;
1301   }
1302   if (msg) {
1303     SayWithDeclaration(symbol, std::move(*msg),
1304         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
1305     return false;
1306   }
1307   return true;
1308 }
1309 
1310 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
1311 bool CheckHelper::CheckDefinedAssignment(
1312     const Symbol &specific, const Procedure &proc) {
1313   if (context_.HasError(specific)) {
1314     return false;
1315   }
1316   std::optional<parser::MessageFixedText> msg;
1317   if (specific.attrs().test(Attr::NOPASS)) { // C774
1318     msg = "Defined assignment procedure '%s' may not have"
1319           " NOPASS attribute"_err_en_US;
1320   } else if (!proc.IsSubroutine()) {
1321     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
1322   } else if (proc.dummyArguments.size() != 2) {
1323     msg = "Defined assignment subroutine '%s' must have"
1324           " two dummy arguments"_err_en_US;
1325   } else if (!CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0) |
1326       !CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)) {
1327     return false; // error was reported
1328   } else if (ConflictsWithIntrinsicAssignment(proc)) {
1329     msg = "Defined assignment subroutine '%s' conflicts with"
1330           " intrinsic assignment"_err_en_US;
1331   } else {
1332     return true; // OK
1333   }
1334   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
1335   context_.SetError(specific);
1336   return false;
1337 }
1338 
1339 bool CheckHelper::CheckDefinedAssignmentArg(
1340     const Symbol &symbol, const DummyArgument &arg, int pos) {
1341   std::optional<parser::MessageFixedText> msg;
1342   if (arg.IsOptional()) {
1343     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1344           " may not be OPTIONAL"_err_en_US;
1345   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
1346     if (pos == 0) {
1347       if (dataObject->intent != common::Intent::Out &&
1348           dataObject->intent != common::Intent::InOut) {
1349         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
1350               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
1351       }
1352     } else if (pos == 1) {
1353       if (dataObject->intent != common::Intent::In &&
1354           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1355         msg =
1356             "In defined assignment subroutine '%s', second dummy"
1357             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1358       }
1359     } else {
1360       DIE("pos must be 0 or 1");
1361     }
1362   } else {
1363     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1364           " must be a data object"_err_en_US;
1365   }
1366   if (msg) {
1367     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1368     context_.SetError(symbol);
1369     return false;
1370   }
1371   return true;
1372 }
1373 
1374 // Report a conflicting attribute error if symbol has both of these attributes
1375 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1376   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1377     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1378         symbol.name(), AttrToString(a1), AttrToString(a2));
1379     return true;
1380   } else {
1381     return false;
1382   }
1383 }
1384 
1385 void CheckHelper::WarnMissingFinal(const Symbol &symbol) {
1386   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
1387   if (!object || IsPointer(symbol)) {
1388     return;
1389   }
1390   const DeclTypeSpec *type{object->type()};
1391   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
1392   const Symbol *derivedSym{derived ? &derived->typeSymbol() : nullptr};
1393   int rank{object->shape().Rank()};
1394   const Symbol *initialDerivedSym{derivedSym};
1395   while (const auto *derivedDetails{
1396       derivedSym ? derivedSym->detailsIf<DerivedTypeDetails>() : nullptr}) {
1397     if (!derivedDetails->finals().empty() &&
1398         !derivedDetails->GetFinalForRank(rank)) {
1399       if (auto *msg{derivedSym == initialDerivedSym
1400                   ? messages_.Say(symbol.name(),
1401                         "'%s' of derived type '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1402                         symbol.name(), derivedSym->name(), rank)
1403                   : messages_.Say(symbol.name(),
1404                         "'%s' of derived type '%s' extended from '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1405                         symbol.name(), initialDerivedSym->name(),
1406                         derivedSym->name(), rank)}) {
1407         msg->Attach(derivedSym->name(),
1408             "Declaration of derived type '%s'"_en_US, derivedSym->name());
1409       }
1410       return;
1411     }
1412     derived = derivedSym->GetParentTypeSpec();
1413     derivedSym = derived ? &derived->typeSymbol() : nullptr;
1414   }
1415 }
1416 
1417 const Procedure *CheckHelper::Characterize(const Symbol &symbol) {
1418   auto it{characterizeCache_.find(symbol)};
1419   if (it == characterizeCache_.end()) {
1420     auto pair{characterizeCache_.emplace(SymbolRef{symbol},
1421         Procedure::Characterize(symbol, context_.foldingContext()))};
1422     it = pair.first;
1423   }
1424   return common::GetPtrFromOptional(it->second);
1425 }
1426 
1427 void CheckHelper::CheckVolatile(const Symbol &symbol,
1428     const DerivedTypeSpec *derived) { // C866 - C868
1429   if (IsIntentIn(symbol)) {
1430     messages_.Say(
1431         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1432   }
1433   if (IsProcedure(symbol)) {
1434     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1435   }
1436   if (symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()) {
1437     const Symbol &ultimate{symbol.GetUltimate()};
1438     if (IsCoarray(ultimate)) {
1439       messages_.Say(
1440           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1441     }
1442     if (derived) {
1443       if (FindCoarrayUltimateComponent(*derived)) {
1444         messages_.Say(
1445             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1446       }
1447     }
1448   }
1449 }
1450 
1451 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1452   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1453   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1454   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1455   // Prohibit constant pointers.  The standard does not explicitly prohibit
1456   // them, but the PARAMETER attribute requires a entity-decl to have an
1457   // initialization that is a constant-expr, and the only form of
1458   // initialization that allows a constant-expr is the one that's not a "=>"
1459   // pointer initialization.  See C811, C807, and section 8.5.13.
1460   CheckConflicting(symbol, Attr::POINTER, Attr::PARAMETER);
1461   if (symbol.Corank() > 0) {
1462     messages_.Say(
1463         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1464         symbol.name());
1465   }
1466 }
1467 
1468 // C760 constraints on the passed-object dummy argument
1469 // C757 constraints on procedure pointer components
1470 void CheckHelper::CheckPassArg(
1471     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1472   if (proc.attrs().test(Attr::NOPASS)) {
1473     return;
1474   }
1475   const auto &name{proc.name()};
1476   if (!interface) {
1477     messages_.Say(name,
1478         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1479         name);
1480     return;
1481   }
1482   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1483   if (!subprogram) {
1484     messages_.Say(name,
1485         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1486         interface->name());
1487     return;
1488   }
1489   std::optional<SourceName> passName{details.passName()};
1490   const auto &dummyArgs{subprogram->dummyArgs()};
1491   if (!passName) {
1492     if (dummyArgs.empty()) {
1493       messages_.Say(name,
1494           proc.has<ProcEntityDetails>()
1495               ? "Procedure component '%s' with no dummy arguments"
1496                 " must have NOPASS attribute"_err_en_US
1497               : "Procedure binding '%s' with no dummy arguments"
1498                 " must have NOPASS attribute"_err_en_US,
1499           name);
1500       context_.SetError(*interface);
1501       return;
1502     }
1503     Symbol *argSym{dummyArgs[0]};
1504     if (!argSym) {
1505       messages_.Say(interface->name(),
1506           "Cannot use an alternate return as the passed-object dummy "
1507           "argument"_err_en_US);
1508       return;
1509     }
1510     passName = dummyArgs[0]->name();
1511   }
1512   std::optional<int> passArgIndex{};
1513   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1514     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1515       passArgIndex = i;
1516       break;
1517     }
1518   }
1519   if (!passArgIndex) { // C758
1520     messages_.Say(*passName,
1521         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1522         *passName, interface->name());
1523     return;
1524   }
1525   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1526   std::optional<parser::MessageFixedText> msg;
1527   if (!passArg.has<ObjectEntityDetails>()) {
1528     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1529           " must be a data object"_err_en_US;
1530   } else if (passArg.attrs().test(Attr::POINTER)) {
1531     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1532           " may not have the POINTER attribute"_err_en_US;
1533   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1534     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1535           " may not have the ALLOCATABLE attribute"_err_en_US;
1536   } else if (passArg.attrs().test(Attr::VALUE)) {
1537     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1538           " may not have the VALUE attribute"_err_en_US;
1539   } else if (passArg.Rank() > 0) {
1540     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1541           " must be scalar"_err_en_US;
1542   }
1543   if (msg) {
1544     messages_.Say(name, std::move(*msg), passName.value(), name);
1545     return;
1546   }
1547   const DeclTypeSpec *type{passArg.GetType()};
1548   if (!type) {
1549     return; // an error already occurred
1550   }
1551   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1552   const DerivedTypeSpec *derived{type->AsDerived()};
1553   if (!derived || derived->typeSymbol() != typeSymbol) {
1554     messages_.Say(name,
1555         "Passed-object dummy argument '%s' of procedure '%s'"
1556         " must be of type '%s' but is '%s'"_err_en_US,
1557         passName.value(), name, typeSymbol.name(), type->AsFortran());
1558     return;
1559   }
1560   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1561     messages_.Say(name,
1562         type->IsPolymorphic()
1563             ? "Passed-object dummy argument '%s' of procedure '%s'"
1564               " may not be polymorphic because '%s' is not extensible"_err_en_US
1565             : "Passed-object dummy argument '%s' of procedure '%s'"
1566               " must be polymorphic because '%s' is extensible"_err_en_US,
1567         passName.value(), name, typeSymbol.name());
1568     return;
1569   }
1570   for (const auto &[paramName, paramValue] : derived->parameters()) {
1571     if (paramValue.isLen() && !paramValue.isAssumed()) {
1572       messages_.Say(name,
1573           "Passed-object dummy argument '%s' of procedure '%s'"
1574           " has non-assumed length parameter '%s'"_err_en_US,
1575           passName.value(), name, paramName);
1576     }
1577   }
1578 }
1579 
1580 void CheckHelper::CheckProcBinding(
1581     const Symbol &symbol, const ProcBindingDetails &binding) {
1582   const Scope &dtScope{symbol.owner()};
1583   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1584   if (symbol.attrs().test(Attr::DEFERRED)) {
1585     if (const Symbol * dtSymbol{dtScope.symbol()}) {
1586       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1587         SayWithDeclaration(*dtSymbol,
1588             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1589             dtSymbol->name());
1590       }
1591     }
1592     if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1593       messages_.Say(
1594           "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1595           symbol.name());
1596     }
1597   }
1598   if (binding.symbol().attrs().test(Attr::INTRINSIC) &&
1599       !context_.intrinsics().IsSpecificIntrinsicFunction(
1600           binding.symbol().name().ToString())) {
1601     messages_.Say(
1602         "Intrinsic procedure '%s' is not a specific intrinsic permitted for use in the definition of binding '%s'"_err_en_US,
1603         binding.symbol().name(), symbol.name());
1604   }
1605   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1606     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1607       SayWithDeclaration(*overridden,
1608           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1609           symbol.name());
1610     }
1611     if (const auto *overriddenBinding{
1612             overridden->detailsIf<ProcBindingDetails>()}) {
1613       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1614         SayWithDeclaration(*overridden,
1615             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1616         return;
1617       }
1618       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1619           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1620         SayWithDeclaration(*overridden,
1621             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1622         return;
1623       }
1624       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1625       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1626         SayWithDeclaration(*overridden,
1627             isNopass
1628                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1629                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1630       } else {
1631         const auto *bindingChars{Characterize(binding.symbol())};
1632         const auto *overriddenChars{Characterize(overriddenBinding->symbol())};
1633         if (bindingChars && overriddenChars) {
1634           if (isNopass) {
1635             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1636               SayWithDeclaration(*overridden,
1637                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1638             }
1639           } else if (!context_.HasError(binding.symbol())) {
1640             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1641             int overriddenPassIndex{
1642                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1643             if (passIndex != overriddenPassIndex) {
1644               SayWithDeclaration(*overridden,
1645                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1646             } else if (!bindingChars->CanOverride(
1647                            *overriddenChars, passIndex)) {
1648               SayWithDeclaration(*overridden,
1649                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1650             }
1651           }
1652         }
1653       }
1654       if (symbol.attrs().test(Attr::PRIVATE) &&
1655           overridden->attrs().test(Attr::PUBLIC)) {
1656         SayWithDeclaration(*overridden,
1657             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1658       }
1659     } else {
1660       SayWithDeclaration(*overridden,
1661           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1662     }
1663   }
1664   CheckPassArg(symbol, &binding.symbol(), binding);
1665 }
1666 
1667 void CheckHelper::Check(const Scope &scope) {
1668   scope_ = &scope;
1669   common::Restorer<const Symbol *> restorer{innermostSymbol_, innermostSymbol_};
1670   if (const Symbol * symbol{scope.symbol()}) {
1671     innermostSymbol_ = symbol;
1672   }
1673   if (scope.IsParameterizedDerivedTypeInstantiation()) {
1674     auto restorer{common::ScopedSet(scopeIsUninstantiatedPDT_, false)};
1675     auto restorer2{context_.foldingContext().messages().SetContext(
1676         scope.instantiationContext().get())};
1677     for (const auto &pair : scope) {
1678       CheckPointerInitialization(*pair.second);
1679     }
1680   } else {
1681     auto restorer{common::ScopedSet(
1682         scopeIsUninstantiatedPDT_, scope.IsParameterizedDerivedType())};
1683     for (const auto &set : scope.equivalenceSets()) {
1684       CheckEquivalenceSet(set);
1685     }
1686     for (const auto &pair : scope) {
1687       Check(*pair.second);
1688     }
1689     for (const Scope &child : scope.children()) {
1690       Check(child);
1691     }
1692     if (scope.kind() == Scope::Kind::BlockData) {
1693       CheckBlockData(scope);
1694     }
1695     CheckGenericOps(scope);
1696   }
1697 }
1698 
1699 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1700   auto iter{
1701       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1702         return FindCommonBlockContaining(object.symbol) != nullptr;
1703       })};
1704   if (iter != set.end()) {
1705     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1706     for (auto &object : set) {
1707       if (&object != &*iter) {
1708         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1709           if (details->commonBlock()) {
1710             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1711               if (auto *msg{messages_.Say(object.symbol.name(),
1712                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1713                 msg->Attach(iter->symbol.name(),
1714                        "Other object in EQUIVALENCE set"_en_US)
1715                     .Attach(details->commonBlock()->name(),
1716                         "COMMON block containing '%s'"_en_US,
1717                         object.symbol.name())
1718                     .Attach(commonBlock.name(),
1719                         "COMMON block containing '%s'"_en_US,
1720                         iter->symbol.name());
1721               }
1722             }
1723           } else {
1724             // Mark all symbols in the equivalence set with the same COMMON
1725             // block to prevent spurious error messages about initialization
1726             // in BLOCK DATA outside COMMON
1727             details->set_commonBlock(commonBlock);
1728           }
1729         }
1730       }
1731     }
1732   }
1733   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1734 }
1735 
1736 void CheckHelper::CheckBlockData(const Scope &scope) {
1737   // BLOCK DATA subprograms should contain only named common blocks.
1738   // C1415 presents a list of statements that shouldn't appear in
1739   // BLOCK DATA, but so long as the subprogram contains no executable
1740   // code and allocates no storage outside named COMMON, we're happy
1741   // (e.g., an ENUM is strictly not allowed).
1742   for (const auto &pair : scope) {
1743     const Symbol &symbol{*pair.second};
1744     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1745             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1746             symbol.has<SubprogramDetails>() ||
1747             symbol.has<ObjectEntityDetails>() ||
1748             (symbol.has<ProcEntityDetails>() &&
1749                 !symbol.attrs().test(Attr::POINTER)))) {
1750       messages_.Say(symbol.name(),
1751           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1752           symbol.name());
1753     }
1754   }
1755 }
1756 
1757 // Check distinguishability of generic assignment and operators.
1758 // For these, generics and generic bindings must be considered together.
1759 void CheckHelper::CheckGenericOps(const Scope &scope) {
1760   DistinguishabilityHelper helper{context_};
1761   auto addSpecifics{[&](const Symbol &generic) {
1762     const auto *details{generic.GetUltimate().detailsIf<GenericDetails>()};
1763     if (!details) {
1764       return;
1765     }
1766     GenericKind kind{details->kind()};
1767     if (!kind.IsAssignment() && !kind.IsOperator()) {
1768       return;
1769     }
1770     const SymbolVector &specifics{details->specificProcs()};
1771     const std::vector<SourceName> &bindingNames{details->bindingNames()};
1772     for (std::size_t i{0}; i < specifics.size(); ++i) {
1773       const Symbol &specific{*specifics[i]};
1774       if (const Procedure * proc{Characterize(specific)}) {
1775         auto restorer{messages_.SetLocation(bindingNames[i])};
1776         if (kind.IsAssignment()) {
1777           if (!CheckDefinedAssignment(specific, *proc)) {
1778             continue;
1779           }
1780         } else {
1781           if (!CheckDefinedOperator(generic.name(), kind, specific, *proc)) {
1782             continue;
1783           }
1784         }
1785         helper.Add(generic, kind, specific, *proc);
1786       }
1787     }
1788   }};
1789   for (const auto &pair : scope) {
1790     const Symbol &symbol{*pair.second};
1791     addSpecifics(symbol);
1792     const Symbol &ultimate{symbol.GetUltimate()};
1793     if (ultimate.has<DerivedTypeDetails>()) {
1794       if (const Scope * typeScope{ultimate.scope()}) {
1795         for (const auto &pair2 : *typeScope) {
1796           addSpecifics(*pair2.second);
1797         }
1798       }
1799     }
1800   }
1801   helper.Check(scope);
1802 }
1803 
1804 static const std::string *DefinesBindCName(const Symbol &symbol) {
1805   const auto *subp{symbol.detailsIf<SubprogramDetails>()};
1806   if ((subp && !subp->isInterface()) || symbol.has<ObjectEntityDetails>()) {
1807     // Symbol defines data or entry point
1808     return symbol.GetBindName();
1809   } else {
1810     return nullptr;
1811   }
1812 }
1813 
1814 // Check that BIND(C) names are distinct
1815 void CheckHelper::CheckBindCName(const Symbol &symbol) {
1816   if (const std::string * name{DefinesBindCName(symbol)}) {
1817     auto pair{bindC_.emplace(*name, symbol)};
1818     if (!pair.second) {
1819       const Symbol &other{*pair.first->second};
1820       if (DefinesBindCName(other) && !context_.HasError(other)) {
1821         if (auto *msg{messages_.Say(
1822                 "Two symbols have the same BIND(C) name '%s'"_err_en_US,
1823                 *name)}) {
1824           msg->Attach(other.name(), "Conflicting symbol"_en_US);
1825         }
1826         context_.SetError(symbol);
1827         context_.SetError(other);
1828       }
1829     }
1830   }
1831 }
1832 
1833 bool CheckHelper::CheckDioDummyIsData(
1834     const Symbol &subp, const Symbol *arg, std::size_t position) {
1835   if (arg && arg->detailsIf<ObjectEntityDetails>()) {
1836     return true;
1837   } else {
1838     if (arg) {
1839       messages_.Say(arg->name(),
1840           "Dummy argument '%s' must be a data object"_err_en_US, arg->name());
1841     } else {
1842       messages_.Say(subp.name(),
1843           "Dummy argument %d of '%s' must be a data object"_err_en_US, position,
1844           subp.name());
1845     }
1846     return false;
1847   }
1848 }
1849 
1850 void CheckHelper::CheckAlreadySeenDefinedIo(const DerivedTypeSpec *derivedType,
1851     GenericKind::DefinedIo ioKind, const Symbol &proc) {
1852   for (TypeWithDefinedIo definedIoType : seenDefinedIoTypes_) {
1853     if (*derivedType == *definedIoType.type && ioKind == definedIoType.ioKind &&
1854         proc != definedIoType.proc) {
1855       SayWithDeclaration(proc, definedIoType.proc.name(),
1856           "Derived type '%s' already has defined input/output procedure"
1857           " '%s'"_err_en_US,
1858           derivedType->name(),
1859           parser::ToUpperCaseLetters(GenericKind::EnumToString(ioKind)));
1860       return;
1861     }
1862   }
1863   seenDefinedIoTypes_.emplace_back(
1864       TypeWithDefinedIo{derivedType, ioKind, proc});
1865 }
1866 
1867 void CheckHelper::CheckDioDummyIsDerived(
1868     const Symbol &subp, const Symbol &arg, GenericKind::DefinedIo ioKind) {
1869   if (const DeclTypeSpec * type{arg.GetType()}) {
1870     if (const DerivedTypeSpec * derivedType{type->AsDerived()}) {
1871       CheckAlreadySeenDefinedIo(derivedType, ioKind, subp);
1872       bool isPolymorphic{type->IsPolymorphic()};
1873       if (isPolymorphic != IsExtensibleType(derivedType)) {
1874         messages_.Say(arg.name(),
1875             "Dummy argument '%s' of a defined input/output procedure must be %s when the derived type is %s"_err_en_US,
1876             arg.name(), isPolymorphic ? "TYPE()" : "CLASS()",
1877             isPolymorphic ? "not extensible" : "extensible");
1878       }
1879     } else {
1880       messages_.Say(arg.name(),
1881           "Dummy argument '%s' of a defined input/output procedure must have a"
1882           " derived type"_err_en_US,
1883           arg.name());
1884     }
1885   }
1886 }
1887 
1888 void CheckHelper::CheckDioDummyIsDefaultInteger(
1889     const Symbol &subp, const Symbol &arg) {
1890   if (const DeclTypeSpec * type{arg.GetType()};
1891       type && type->IsNumeric(TypeCategory::Integer)) {
1892     if (const auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
1893         kind && *kind == context_.GetDefaultKind(TypeCategory::Integer)) {
1894       return;
1895     }
1896   }
1897   messages_.Say(arg.name(),
1898       "Dummy argument '%s' of a defined input/output procedure"
1899       " must be an INTEGER of default KIND"_err_en_US,
1900       arg.name());
1901 }
1902 
1903 void CheckHelper::CheckDioDummyIsScalar(const Symbol &subp, const Symbol &arg) {
1904   if (arg.Rank() > 0 || arg.Corank() > 0) {
1905     messages_.Say(arg.name(),
1906         "Dummy argument '%s' of a defined input/output procedure"
1907         " must be a scalar"_err_en_US,
1908         arg.name());
1909   }
1910 }
1911 
1912 void CheckHelper::CheckDioDtvArg(
1913     const Symbol &subp, const Symbol *arg, GenericKind::DefinedIo ioKind) {
1914   // Dtv argument looks like: dtv-type-spec, INTENT(INOUT) :: dtv
1915   if (CheckDioDummyIsData(subp, arg, 0)) {
1916     CheckDioDummyIsDerived(subp, *arg, ioKind);
1917     CheckDioDummyAttrs(subp, *arg,
1918         ioKind == GenericKind::DefinedIo::ReadFormatted ||
1919                 ioKind == GenericKind::DefinedIo::ReadUnformatted
1920             ? Attr::INTENT_INOUT
1921             : Attr::INTENT_IN);
1922   }
1923 }
1924 
1925 void CheckHelper::CheckDefaultIntegerArg(
1926     const Symbol &subp, const Symbol *arg, Attr intent) {
1927   // Argument looks like: INTEGER, INTENT(intent) :: arg
1928   if (CheckDioDummyIsData(subp, arg, 1)) {
1929     CheckDioDummyIsDefaultInteger(subp, *arg);
1930     CheckDioDummyIsScalar(subp, *arg);
1931     CheckDioDummyAttrs(subp, *arg, intent);
1932   }
1933 }
1934 
1935 void CheckHelper::CheckDioAssumedLenCharacterArg(const Symbol &subp,
1936     const Symbol *arg, std::size_t argPosition, Attr intent) {
1937   // Argument looks like: CHARACTER (LEN=*), INTENT(intent) :: (iotype OR iomsg)
1938   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1939     CheckDioDummyAttrs(subp, *arg, intent);
1940     if (!IsAssumedLengthCharacter(*arg)) {
1941       messages_.Say(arg->name(),
1942           "Dummy argument '%s' of a defined input/output procedure"
1943           " must be assumed-length CHARACTER"_err_en_US,
1944           arg->name());
1945     }
1946   }
1947 }
1948 
1949 void CheckHelper::CheckDioVlistArg(
1950     const Symbol &subp, const Symbol *arg, std::size_t argPosition) {
1951   // Vlist argument looks like: INTEGER, INTENT(IN) :: v_list(:)
1952   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1953     CheckDioDummyIsDefaultInteger(subp, *arg);
1954     CheckDioDummyAttrs(subp, *arg, Attr::INTENT_IN);
1955     if (const auto *objectDetails{arg->detailsIf<ObjectEntityDetails>()}) {
1956       if (objectDetails->shape().IsDeferredShape()) {
1957         return;
1958       }
1959     }
1960     messages_.Say(arg->name(),
1961         "Dummy argument '%s' of a defined input/output procedure must be"
1962         " deferred shape"_err_en_US,
1963         arg->name());
1964   }
1965 }
1966 
1967 void CheckHelper::CheckDioArgCount(
1968     const Symbol &subp, GenericKind::DefinedIo ioKind, std::size_t argCount) {
1969   const std::size_t requiredArgCount{
1970       (std::size_t)(ioKind == GenericKind::DefinedIo::ReadFormatted ||
1971                   ioKind == GenericKind::DefinedIo::WriteFormatted
1972               ? 6
1973               : 4)};
1974   if (argCount != requiredArgCount) {
1975     SayWithDeclaration(subp,
1976         "Defined input/output procedure '%s' must have"
1977         " %d dummy arguments rather than %d"_err_en_US,
1978         subp.name(), requiredArgCount, argCount);
1979     context_.SetError(subp);
1980   }
1981 }
1982 
1983 void CheckHelper::CheckDioDummyAttrs(
1984     const Symbol &subp, const Symbol &arg, Attr goodIntent) {
1985   // Defined I/O procedures can't have attributes other than INTENT
1986   Attrs attrs{arg.attrs()};
1987   if (!attrs.test(goodIntent)) {
1988     messages_.Say(arg.name(),
1989         "Dummy argument '%s' of a defined input/output procedure"
1990         " must have intent '%s'"_err_en_US,
1991         arg.name(), AttrToString(goodIntent));
1992   }
1993   attrs = attrs - Attr::INTENT_IN - Attr::INTENT_OUT - Attr::INTENT_INOUT;
1994   if (!attrs.empty()) {
1995     messages_.Say(arg.name(),
1996         "Dummy argument '%s' of a defined input/output procedure may not have"
1997         " any attributes"_err_en_US,
1998         arg.name());
1999   }
2000 }
2001 
2002 // Enforce semantics for defined input/output procedures (12.6.4.8.2) and C777
2003 void CheckHelper::CheckDefinedIoProc(const Symbol &symbol,
2004     const GenericDetails &details, GenericKind::DefinedIo ioKind) {
2005   for (auto ref : details.specificProcs()) {
2006     const auto *binding{ref->detailsIf<ProcBindingDetails>()};
2007     const Symbol &specific{*(binding ? &binding->symbol() : &*ref)};
2008     if (ref->attrs().test(Attr::NOPASS)) { // C774
2009       messages_.Say("Defined input/output procedure '%s' may not have NOPASS "
2010                     "attribute"_err_en_US,
2011           ref->name());
2012       context_.SetError(*ref);
2013     }
2014     if (const auto *subpDetails{specific.detailsIf<SubprogramDetails>()}) {
2015       const std::vector<Symbol *> &dummyArgs{subpDetails->dummyArgs()};
2016       CheckDioArgCount(specific, ioKind, dummyArgs.size());
2017       int argCount{0};
2018       for (auto *arg : dummyArgs) {
2019         switch (argCount++) {
2020         case 0:
2021           // dtv-type-spec, INTENT(INOUT) :: dtv
2022           CheckDioDtvArg(specific, arg, ioKind);
2023           break;
2024         case 1:
2025           // INTEGER, INTENT(IN) :: unit
2026           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_IN);
2027           break;
2028         case 2:
2029           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2030               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2031             // CHARACTER (LEN=*), INTENT(IN) :: iotype
2032             CheckDioAssumedLenCharacterArg(
2033                 specific, arg, argCount, Attr::INTENT_IN);
2034           } else {
2035             // INTEGER, INTENT(OUT) :: iostat
2036             CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2037           }
2038           break;
2039         case 3:
2040           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2041               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2042             // INTEGER, INTENT(IN) :: v_list(:)
2043             CheckDioVlistArg(specific, arg, argCount);
2044           } else {
2045             // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2046             CheckDioAssumedLenCharacterArg(
2047                 specific, arg, argCount, Attr::INTENT_INOUT);
2048           }
2049           break;
2050         case 4:
2051           // INTEGER, INTENT(OUT) :: iostat
2052           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2053           break;
2054         case 5:
2055           // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2056           CheckDioAssumedLenCharacterArg(
2057               specific, arg, argCount, Attr::INTENT_INOUT);
2058           break;
2059         default:;
2060         }
2061       }
2062     }
2063   }
2064 }
2065 
2066 void SubprogramMatchHelper::Check(
2067     const Symbol &symbol1, const Symbol &symbol2) {
2068   const auto details1{symbol1.get<SubprogramDetails>()};
2069   const auto details2{symbol2.get<SubprogramDetails>()};
2070   if (details1.isFunction() != details2.isFunction()) {
2071     Say(symbol1, symbol2,
2072         details1.isFunction()
2073             ? "Module function '%s' was declared as a subroutine in the"
2074               " corresponding interface body"_err_en_US
2075             : "Module subroutine '%s' was declared as a function in the"
2076               " corresponding interface body"_err_en_US);
2077     return;
2078   }
2079   const auto &args1{details1.dummyArgs()};
2080   const auto &args2{details2.dummyArgs()};
2081   int nargs1{static_cast<int>(args1.size())};
2082   int nargs2{static_cast<int>(args2.size())};
2083   if (nargs1 != nargs2) {
2084     Say(symbol1, symbol2,
2085         "Module subprogram '%s' has %d args but the corresponding interface"
2086         " body has %d"_err_en_US,
2087         nargs1, nargs2);
2088     return;
2089   }
2090   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
2091   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
2092     Say(symbol1, symbol2,
2093         nonRecursive1
2094             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
2095               " the corresponding interface body does not"_err_en_US
2096             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
2097               "the corresponding interface body does"_err_en_US);
2098   }
2099   const std::string *bindName1{details1.bindName()};
2100   const std::string *bindName2{details2.bindName()};
2101   if (!bindName1 && !bindName2) {
2102     // OK - neither has a binding label
2103   } else if (!bindName1) {
2104     Say(symbol1, symbol2,
2105         "Module subprogram '%s' does not have a binding label but the"
2106         " corresponding interface body does"_err_en_US);
2107   } else if (!bindName2) {
2108     Say(symbol1, symbol2,
2109         "Module subprogram '%s' has a binding label but the"
2110         " corresponding interface body does not"_err_en_US);
2111   } else if (*bindName1 != *bindName2) {
2112     Say(symbol1, symbol2,
2113         "Module subprogram '%s' has binding label '%s' but the corresponding"
2114         " interface body has '%s'"_err_en_US,
2115         *details1.bindName(), *details2.bindName());
2116   }
2117   const Procedure *proc1{checkHelper.Characterize(symbol1)};
2118   const Procedure *proc2{checkHelper.Characterize(symbol2)};
2119   if (!proc1 || !proc2) {
2120     return;
2121   }
2122   if (proc1->functionResult && proc2->functionResult &&
2123       *proc1->functionResult != *proc2->functionResult) {
2124     Say(symbol1, symbol2,
2125         "Return type of function '%s' does not match return type of"
2126         " the corresponding interface body"_err_en_US);
2127   }
2128   for (int i{0}; i < nargs1; ++i) {
2129     const Symbol *arg1{args1[i]};
2130     const Symbol *arg2{args2[i]};
2131     if (arg1 && !arg2) {
2132       Say(symbol1, symbol2,
2133           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
2134           " but the corresponding argument in the interface body is"_err_en_US,
2135           i + 1);
2136     } else if (!arg1 && arg2) {
2137       Say(symbol1, symbol2,
2138           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
2139           " the corresponding argument in the interface body is not"_err_en_US,
2140           i + 1);
2141     } else if (arg1 && arg2) {
2142       SourceName name1{arg1->name()};
2143       SourceName name2{arg2->name()};
2144       if (name1 != name2) {
2145         Say(*arg1, *arg2,
2146             "Dummy argument name '%s' does not match corresponding name '%s'"
2147             " in interface body"_err_en_US,
2148             name2);
2149       } else {
2150         CheckDummyArg(
2151             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
2152       }
2153     }
2154   }
2155 }
2156 
2157 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
2158     const Symbol &symbol2, const DummyArgument &arg1,
2159     const DummyArgument &arg2) {
2160   std::visit(common::visitors{
2161                  [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
2162                    CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
2163                  },
2164                  [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
2165                    CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
2166                  },
2167                  [&](const DummyDataObject &, const auto &) {
2168                    Say(symbol1, symbol2,
2169                        "Dummy argument '%s' is a data object; the corresponding"
2170                        " argument in the interface body is not"_err_en_US);
2171                  },
2172                  [&](const DummyProcedure &, const auto &) {
2173                    Say(symbol1, symbol2,
2174                        "Dummy argument '%s' is a procedure; the corresponding"
2175                        " argument in the interface body is not"_err_en_US);
2176                  },
2177                  [&](const auto &, const auto &) {
2178                    llvm_unreachable("Dummy arguments are not data objects or"
2179                                     "procedures");
2180                  },
2181              },
2182       arg1.u, arg2.u);
2183 }
2184 
2185 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
2186     const Symbol &symbol2, const DummyDataObject &obj1,
2187     const DummyDataObject &obj2) {
2188   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
2189   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
2190   } else if (obj1.type.type() != obj2.type.type()) {
2191     Say(symbol1, symbol2,
2192         "Dummy argument '%s' has type %s; the corresponding argument in the"
2193         " interface body has type %s"_err_en_US,
2194         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
2195   } else if (!ShapesAreCompatible(obj1, obj2)) {
2196     Say(symbol1, symbol2,
2197         "The shape of dummy argument '%s' does not match the shape of the"
2198         " corresponding argument in the interface body"_err_en_US);
2199   }
2200   // TODO: coshape
2201 }
2202 
2203 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
2204     const Symbol &symbol2, const DummyProcedure &proc1,
2205     const DummyProcedure &proc2) {
2206   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
2207   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
2208   } else if (proc1 != proc2) {
2209     Say(symbol1, symbol2,
2210         "Dummy procedure '%s' does not match the corresponding argument in"
2211         " the interface body"_err_en_US);
2212   }
2213 }
2214 
2215 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
2216     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
2217   if (intent1 == intent2) {
2218     return true;
2219   } else {
2220     Say(symbol1, symbol2,
2221         "The intent of dummy argument '%s' does not match the intent"
2222         " of the corresponding argument in the interface body"_err_en_US);
2223     return false;
2224   }
2225 }
2226 
2227 // Report an error referring to first symbol with declaration of second symbol
2228 template <typename... A>
2229 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
2230     parser::MessageFixedText &&text, A &&...args) {
2231   auto &message{context().Say(symbol1.name(), std::move(text), symbol1.name(),
2232       std::forward<A>(args)...)};
2233   evaluate::AttachDeclaration(message, symbol2);
2234 }
2235 
2236 template <typename ATTRS>
2237 bool SubprogramMatchHelper::CheckSameAttrs(
2238     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
2239   if (attrs1 == attrs2) {
2240     return true;
2241   }
2242   attrs1.IterateOverMembers([&](auto attr) {
2243     if (!attrs2.test(attr)) {
2244       Say(symbol1, symbol2,
2245           "Dummy argument '%s' has the %s attribute; the corresponding"
2246           " argument in the interface body does not"_err_en_US,
2247           AsFortran(attr));
2248     }
2249   });
2250   attrs2.IterateOverMembers([&](auto attr) {
2251     if (!attrs1.test(attr)) {
2252       Say(symbol1, symbol2,
2253           "Dummy argument '%s' does not have the %s attribute; the"
2254           " corresponding argument in the interface body does"_err_en_US,
2255           AsFortran(attr));
2256     }
2257   });
2258   return false;
2259 }
2260 
2261 bool SubprogramMatchHelper::ShapesAreCompatible(
2262     const DummyDataObject &obj1, const DummyDataObject &obj2) {
2263   return characteristics::ShapesAreCompatible(
2264       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
2265 }
2266 
2267 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
2268   evaluate::Shape result;
2269   for (const auto &extent : shape) {
2270     result.emplace_back(
2271         evaluate::Fold(context().foldingContext(), common::Clone(extent)));
2272   }
2273   return result;
2274 }
2275 
2276 void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
2277     const Symbol &specific, const Procedure &procedure) {
2278   if (!context_.HasError(specific)) {
2279     nameToInfo_[generic.name()].emplace_back(
2280         ProcedureInfo{kind, specific, procedure});
2281   }
2282 }
2283 
2284 void DistinguishabilityHelper::Check(const Scope &scope) {
2285   for (const auto &[name, info] : nameToInfo_) {
2286     auto count{info.size()};
2287     for (std::size_t i1{0}; i1 < count - 1; ++i1) {
2288       const auto &[kind, symbol, proc]{info[i1]};
2289       for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
2290         auto distinguishable{kind.IsName()
2291                 ? evaluate::characteristics::Distinguishable
2292                 : evaluate::characteristics::DistinguishableOpOrAssign};
2293         if (!distinguishable(proc, info[i2].procedure)) {
2294           SayNotDistinguishable(GetTopLevelUnitContaining(scope), name, kind,
2295               symbol, info[i2].symbol);
2296         }
2297       }
2298     }
2299   }
2300 }
2301 
2302 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
2303     const SourceName &name, GenericKind kind, const Symbol &proc1,
2304     const Symbol &proc2) {
2305   std::string name1{proc1.name().ToString()};
2306   std::string name2{proc2.name().ToString()};
2307   if (kind.IsOperator() || kind.IsAssignment()) {
2308     // proc1 and proc2 may come from different scopes so qualify their names
2309     if (proc1.owner().IsDerivedType()) {
2310       name1 = proc1.owner().GetName()->ToString() + '%' + name1;
2311     }
2312     if (proc2.owner().IsDerivedType()) {
2313       name2 = proc2.owner().GetName()->ToString() + '%' + name2;
2314     }
2315   }
2316   parser::Message *msg;
2317   if (scope.sourceRange().Contains(name)) {
2318     msg = &context_.Say(name,
2319         "Generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2320         MakeOpName(name), name1, name2);
2321   } else {
2322     msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
2323         "USE-associated generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2324         MakeOpName(name), name1, name2);
2325   }
2326   AttachDeclaration(*msg, scope, proc1);
2327   AttachDeclaration(*msg, scope, proc2);
2328 }
2329 
2330 // `evaluate::AttachDeclaration` doesn't handle the generic case where `proc`
2331 // comes from a different module but is not necessarily use-associated.
2332 void DistinguishabilityHelper::AttachDeclaration(
2333     parser::Message &msg, const Scope &scope, const Symbol &proc) {
2334   const Scope &unit{GetTopLevelUnitContaining(proc)};
2335   if (unit == scope) {
2336     evaluate::AttachDeclaration(msg, proc);
2337   } else {
2338     msg.Attach(unit.GetName().value(),
2339         "'%s' is USE-associated from module '%s'"_en_US, proc.name(),
2340         unit.GetName().value());
2341   }
2342 }
2343 
2344 void CheckDeclarations(SemanticsContext &context) {
2345   CheckHelper{context}.Check();
2346 }
2347 } // namespace Fortran::semantics
2348