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 if (details.dummyArgs().empty()) {
903       messages_.Say(
904           "An ELEMENTAL subprogram must have at least one dummy argument"_err_en_US);
905     } else {
906       for (const Symbol *dummy : details.dummyArgs()) {
907         if (!dummy) { // C15100
908           messages_.Say(
909               "An ELEMENTAL subroutine may not have an alternate return dummy argument"_err_en_US);
910         }
911       }
912     }
913   }
914 }
915 
916 void CheckHelper::CheckDerivedType(
917     const Symbol &derivedType, const DerivedTypeDetails &details) {
918   if (details.isForwardReferenced() && !context_.HasError(derivedType)) {
919     messages_.Say("The derived type '%s' has not been defined"_err_en_US,
920         derivedType.name());
921   }
922   const Scope *scope{derivedType.scope()};
923   if (!scope) {
924     CHECK(details.isForwardReferenced());
925     return;
926   }
927   CHECK(scope->symbol() == &derivedType);
928   CHECK(scope->IsDerivedType());
929   if (derivedType.attrs().test(Attr::ABSTRACT) && // C734
930       (derivedType.attrs().test(Attr::BIND_C) || details.sequence())) {
931     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
932   }
933   if (const DeclTypeSpec * parent{FindParentTypeSpec(derivedType)}) {
934     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
935     if (!IsExtensibleType(parentDerived)) { // C705
936       messages_.Say("The parent type is not extensible"_err_en_US);
937     }
938     if (!derivedType.attrs().test(Attr::ABSTRACT) && parentDerived &&
939         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
940       ScopeComponentIterator components{*parentDerived};
941       for (const Symbol &component : components) {
942         if (component.attrs().test(Attr::DEFERRED)) {
943           if (scope->FindComponent(component.name()) == &component) {
944             SayWithDeclaration(component,
945                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
946                 parentDerived->typeSymbol().name(), component.name());
947           }
948         }
949       }
950     }
951     DerivedTypeSpec derived{derivedType.name(), derivedType};
952     derived.set_scope(*scope);
953     if (FindCoarrayUltimateComponent(derived) && // C736
954         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
955       messages_.Say(
956           "Type '%s' has a coarray ultimate component so the type at the base "
957           "of its type extension chain ('%s') must be a type that has a "
958           "coarray ultimate component"_err_en_US,
959           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
960     }
961     if (FindEventOrLockPotentialComponent(derived) && // C737
962         !(FindEventOrLockPotentialComponent(*parentDerived) ||
963             IsEventTypeOrLockType(parentDerived))) {
964       messages_.Say(
965           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
966           "at the base of its type extension chain ('%s') must either have an "
967           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
968           "LOCK_TYPE"_err_en_US,
969           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
970     }
971   }
972   if (HasIntrinsicTypeName(derivedType)) { // C729
973     messages_.Say("A derived type name cannot be the name of an intrinsic"
974                   " type"_err_en_US);
975   }
976   std::map<SourceName, SymbolRef> previous;
977   for (const auto &pair : details.finals()) {
978     SourceName source{pair.first};
979     const Symbol &ref{*pair.second};
980     if (CheckFinal(ref, source, derivedType) &&
981         std::all_of(previous.begin(), previous.end(),
982             [&](std::pair<SourceName, SymbolRef> prev) {
983               return CheckDistinguishableFinals(
984                   ref, source, *prev.second, prev.first, derivedType);
985             })) {
986       previous.emplace(source, ref);
987     }
988   }
989 }
990 
991 // C786
992 bool CheckHelper::CheckFinal(
993     const Symbol &subroutine, SourceName finalName, const Symbol &derivedType) {
994   if (!IsModuleProcedure(subroutine)) {
995     SayWithDeclaration(subroutine, finalName,
996         "FINAL subroutine '%s' of derived type '%s' must be a module procedure"_err_en_US,
997         subroutine.name(), derivedType.name());
998     return false;
999   }
1000   const Procedure *proc{Characterize(subroutine)};
1001   if (!proc) {
1002     return false; // error recovery
1003   }
1004   if (!proc->IsSubroutine()) {
1005     SayWithDeclaration(subroutine, finalName,
1006         "FINAL subroutine '%s' of derived type '%s' must be a subroutine"_err_en_US,
1007         subroutine.name(), derivedType.name());
1008     return false;
1009   }
1010   if (proc->dummyArguments.size() != 1) {
1011     SayWithDeclaration(subroutine, finalName,
1012         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument"_err_en_US,
1013         subroutine.name(), derivedType.name());
1014     return false;
1015   }
1016   const auto &arg{proc->dummyArguments[0]};
1017   const Symbol *errSym{&subroutine};
1018   if (const auto *details{subroutine.detailsIf<SubprogramDetails>()}) {
1019     if (!details->dummyArgs().empty()) {
1020       if (const Symbol * argSym{details->dummyArgs()[0]}) {
1021         errSym = argSym;
1022       }
1023     }
1024   }
1025   const auto *ddo{std::get_if<DummyDataObject>(&arg.u)};
1026   if (!ddo) {
1027     SayWithDeclaration(subroutine, finalName,
1028         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument that is a data object"_err_en_US,
1029         subroutine.name(), derivedType.name());
1030     return false;
1031   }
1032   bool ok{true};
1033   if (arg.IsOptional()) {
1034     SayWithDeclaration(*errSym, finalName,
1035         "FINAL subroutine '%s' of derived type '%s' must not have an OPTIONAL dummy argument"_err_en_US,
1036         subroutine.name(), derivedType.name());
1037     ok = false;
1038   }
1039   if (ddo->attrs.test(DummyDataObject::Attr::Allocatable)) {
1040     SayWithDeclaration(*errSym, finalName,
1041         "FINAL subroutine '%s' of derived type '%s' must not have an ALLOCATABLE dummy argument"_err_en_US,
1042         subroutine.name(), derivedType.name());
1043     ok = false;
1044   }
1045   if (ddo->attrs.test(DummyDataObject::Attr::Pointer)) {
1046     SayWithDeclaration(*errSym, finalName,
1047         "FINAL subroutine '%s' of derived type '%s' must not have a POINTER dummy argument"_err_en_US,
1048         subroutine.name(), derivedType.name());
1049     ok = false;
1050   }
1051   if (ddo->intent == common::Intent::Out) {
1052     SayWithDeclaration(*errSym, finalName,
1053         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with INTENT(OUT)"_err_en_US,
1054         subroutine.name(), derivedType.name());
1055     ok = false;
1056   }
1057   if (ddo->attrs.test(DummyDataObject::Attr::Value)) {
1058     SayWithDeclaration(*errSym, finalName,
1059         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with the VALUE attribute"_err_en_US,
1060         subroutine.name(), derivedType.name());
1061     ok = false;
1062   }
1063   if (ddo->type.corank() > 0) {
1064     SayWithDeclaration(*errSym, finalName,
1065         "FINAL subroutine '%s' of derived type '%s' must not have a coarray dummy argument"_err_en_US,
1066         subroutine.name(), derivedType.name());
1067     ok = false;
1068   }
1069   if (ddo->type.type().IsPolymorphic()) {
1070     SayWithDeclaration(*errSym, finalName,
1071         "FINAL subroutine '%s' of derived type '%s' must not have a polymorphic dummy argument"_err_en_US,
1072         subroutine.name(), derivedType.name());
1073     ok = false;
1074   } else if (ddo->type.type().category() != TypeCategory::Derived ||
1075       &ddo->type.type().GetDerivedTypeSpec().typeSymbol() != &derivedType) {
1076     SayWithDeclaration(*errSym, finalName,
1077         "FINAL subroutine '%s' of derived type '%s' must have a TYPE(%s) dummy argument"_err_en_US,
1078         subroutine.name(), derivedType.name(), derivedType.name());
1079     ok = false;
1080   } else { // check that all LEN type parameters are assumed
1081     for (auto ref : OrderParameterDeclarations(derivedType)) {
1082       if (IsLenTypeParameter(*ref)) {
1083         const auto *value{
1084             ddo->type.type().GetDerivedTypeSpec().FindParameter(ref->name())};
1085         if (!value || !value->isAssumed()) {
1086           SayWithDeclaration(*errSym, finalName,
1087               "FINAL subroutine '%s' of derived type '%s' must have a dummy argument with an assumed LEN type parameter '%s=*'"_err_en_US,
1088               subroutine.name(), derivedType.name(), ref->name());
1089           ok = false;
1090         }
1091       }
1092     }
1093   }
1094   return ok;
1095 }
1096 
1097 bool CheckHelper::CheckDistinguishableFinals(const Symbol &f1,
1098     SourceName f1Name, const Symbol &f2, SourceName f2Name,
1099     const Symbol &derivedType) {
1100   const Procedure *p1{Characterize(f1)};
1101   const Procedure *p2{Characterize(f2)};
1102   if (p1 && p2) {
1103     if (characteristics::Distinguishable(*p1, *p2)) {
1104       return true;
1105     }
1106     if (auto *msg{messages_.Say(f1Name,
1107             "FINAL subroutines '%s' and '%s' of derived type '%s' cannot be distinguished by rank or KIND type parameter value"_err_en_US,
1108             f1Name, f2Name, derivedType.name())}) {
1109       msg->Attach(f2Name, "FINAL declaration of '%s'"_en_US, f2.name())
1110           .Attach(f1.name(), "Definition of '%s'"_en_US, f1Name)
1111           .Attach(f2.name(), "Definition of '%s'"_en_US, f2Name);
1112     }
1113   }
1114   return false;
1115 }
1116 
1117 void CheckHelper::CheckHostAssoc(
1118     const Symbol &symbol, const HostAssocDetails &details) {
1119   const Symbol &hostSymbol{details.symbol()};
1120   if (hostSymbol.test(Symbol::Flag::ImplicitOrError)) {
1121     if (details.implicitOrSpecExprError) {
1122       messages_.Say("Implicitly typed local entity '%s' not allowed in"
1123                     " specification expression"_err_en_US,
1124           symbol.name());
1125     } else if (details.implicitOrExplicitTypeError) {
1126       messages_.Say(
1127           "No explicit type declared for '%s'"_err_en_US, symbol.name());
1128     }
1129   }
1130 }
1131 
1132 void CheckHelper::CheckGeneric(
1133     const Symbol &symbol, const GenericDetails &details) {
1134   CheckSpecificsAreDistinguishable(symbol, details);
1135   std::visit(common::visitors{
1136                  [&](const GenericKind::DefinedIo &io) {
1137                    CheckDefinedIoProc(symbol, details, io);
1138                  },
1139                  [](const auto &) {},
1140              },
1141       details.kind().u);
1142 }
1143 
1144 // Check that the specifics of this generic are distinguishable from each other
1145 void CheckHelper::CheckSpecificsAreDistinguishable(
1146     const Symbol &generic, const GenericDetails &details) {
1147   GenericKind kind{details.kind()};
1148   const SymbolVector &specifics{details.specificProcs()};
1149   std::size_t count{specifics.size()};
1150   if (count < 2 || !kind.IsName()) {
1151     return;
1152   }
1153   DistinguishabilityHelper helper{context_};
1154   for (const Symbol &specific : specifics) {
1155     if (const Procedure * procedure{Characterize(specific)}) {
1156       helper.Add(generic, kind, specific, *procedure);
1157     }
1158   }
1159   helper.Check(generic.owner());
1160 }
1161 
1162 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
1163   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1164   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1165   return Tristate::No ==
1166       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
1167 }
1168 
1169 static bool ConflictsWithIntrinsicOperator(
1170     const GenericKind &kind, const Procedure &proc) {
1171   if (!kind.IsIntrinsicOperator()) {
1172     return false;
1173   }
1174   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1175   auto type0{arg0.type()};
1176   if (proc.dummyArguments.size() == 1) { // unary
1177     return std::visit(
1178         common::visitors{
1179             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
1180             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
1181             [](const auto &) -> bool { DIE("bad generic kind"); },
1182         },
1183         kind.u);
1184   } else { // binary
1185     int rank0{arg0.Rank()};
1186     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1187     auto type1{arg1.type()};
1188     int rank1{arg1.Rank()};
1189     return std::visit(
1190         common::visitors{
1191             [&](common::NumericOperator) {
1192               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
1193             },
1194             [&](common::LogicalOperator) {
1195               return IsIntrinsicLogical(type0, rank0, type1, rank1);
1196             },
1197             [&](common::RelationalOperator opr) {
1198               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
1199             },
1200             [&](GenericKind::OtherKind x) {
1201               CHECK(x == GenericKind::OtherKind::Concat);
1202               return IsIntrinsicConcat(type0, rank0, type1, rank1);
1203             },
1204             [](const auto &) -> bool { DIE("bad generic kind"); },
1205         },
1206         kind.u);
1207   }
1208 }
1209 
1210 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
1211 bool CheckHelper::CheckDefinedOperator(SourceName opName, GenericKind kind,
1212     const Symbol &specific, const Procedure &proc) {
1213   if (context_.HasError(specific)) {
1214     return false;
1215   }
1216   std::optional<parser::MessageFixedText> msg;
1217   auto checkDefinedOperatorArgs{
1218       [&](SourceName opName, const Symbol &specific, const Procedure &proc) {
1219         bool arg0Defined{CheckDefinedOperatorArg(opName, specific, proc, 0)};
1220         bool arg1Defined{CheckDefinedOperatorArg(opName, specific, proc, 1)};
1221         return arg0Defined && arg1Defined;
1222       }};
1223   if (specific.attrs().test(Attr::NOPASS)) { // C774
1224     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
1225   } else if (!proc.functionResult.has_value()) {
1226     msg = "%s procedure '%s' must be a function"_err_en_US;
1227   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
1228     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
1229           " result"_err_en_US;
1230   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
1231     msg = std::move(m);
1232   } else if (!checkDefinedOperatorArgs(opName, specific, proc)) {
1233     return false; // error was reported
1234   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
1235     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
1236   } else {
1237     return true; // OK
1238   }
1239   SayWithDeclaration(
1240       specific, std::move(*msg), MakeOpName(opName), specific.name());
1241   context_.SetError(specific);
1242   return false;
1243 }
1244 
1245 // If the number of arguments is wrong for this intrinsic operator, return
1246 // false and return the error message in msg.
1247 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
1248     const GenericKind &kind, std::size_t nargs) {
1249   if (!kind.IsIntrinsicOperator()) {
1250     return std::nullopt;
1251   }
1252   std::size_t min{2}, max{2}; // allowed number of args; default is binary
1253   std::visit(common::visitors{
1254                  [&](const common::NumericOperator &x) {
1255                    if (x == common::NumericOperator::Add ||
1256                        x == common::NumericOperator::Subtract) {
1257                      min = 1; // + and - are unary or binary
1258                    }
1259                  },
1260                  [&](const common::LogicalOperator &x) {
1261                    if (x == common::LogicalOperator::Not) {
1262                      min = 1; // .NOT. is unary
1263                      max = 1;
1264                    }
1265                  },
1266                  [](const common::RelationalOperator &) {
1267                    // all are binary
1268                  },
1269                  [](const GenericKind::OtherKind &x) {
1270                    CHECK(x == GenericKind::OtherKind::Concat);
1271                  },
1272                  [](const auto &) { DIE("expected intrinsic operator"); },
1273              },
1274       kind.u);
1275   if (nargs >= min && nargs <= max) {
1276     return std::nullopt;
1277   } else if (max == 1) {
1278     return "%s function '%s' must have one dummy argument"_err_en_US;
1279   } else if (min == 2) {
1280     return "%s function '%s' must have two dummy arguments"_err_en_US;
1281   } else {
1282     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
1283   }
1284 }
1285 
1286 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
1287     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
1288   if (pos >= proc.dummyArguments.size()) {
1289     return true;
1290   }
1291   auto &arg{proc.dummyArguments.at(pos)};
1292   std::optional<parser::MessageFixedText> msg;
1293   if (arg.IsOptional()) {
1294     msg = "In %s function '%s', dummy argument '%s' may not be"
1295           " OPTIONAL"_err_en_US;
1296   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
1297              dataObject == nullptr) {
1298     msg = "In %s function '%s', dummy argument '%s' must be a"
1299           " data object"_err_en_US;
1300   } else if (dataObject->intent != common::Intent::In &&
1301       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1302     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
1303           " or VALUE attribute"_err_en_US;
1304   }
1305   if (msg) {
1306     SayWithDeclaration(symbol, std::move(*msg),
1307         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
1308     return false;
1309   }
1310   return true;
1311 }
1312 
1313 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
1314 bool CheckHelper::CheckDefinedAssignment(
1315     const Symbol &specific, const Procedure &proc) {
1316   if (context_.HasError(specific)) {
1317     return false;
1318   }
1319   std::optional<parser::MessageFixedText> msg;
1320   if (specific.attrs().test(Attr::NOPASS)) { // C774
1321     msg = "Defined assignment procedure '%s' may not have"
1322           " NOPASS attribute"_err_en_US;
1323   } else if (!proc.IsSubroutine()) {
1324     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
1325   } else if (proc.dummyArguments.size() != 2) {
1326     msg = "Defined assignment subroutine '%s' must have"
1327           " two dummy arguments"_err_en_US;
1328   } else if (!CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0) |
1329       !CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)) {
1330     return false; // error was reported
1331   } else if (ConflictsWithIntrinsicAssignment(proc)) {
1332     msg = "Defined assignment subroutine '%s' conflicts with"
1333           " intrinsic assignment"_err_en_US;
1334   } else {
1335     return true; // OK
1336   }
1337   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
1338   context_.SetError(specific);
1339   return false;
1340 }
1341 
1342 bool CheckHelper::CheckDefinedAssignmentArg(
1343     const Symbol &symbol, const DummyArgument &arg, int pos) {
1344   std::optional<parser::MessageFixedText> msg;
1345   if (arg.IsOptional()) {
1346     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1347           " may not be OPTIONAL"_err_en_US;
1348   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
1349     if (pos == 0) {
1350       if (dataObject->intent != common::Intent::Out &&
1351           dataObject->intent != common::Intent::InOut) {
1352         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
1353               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
1354       }
1355     } else if (pos == 1) {
1356       if (dataObject->intent != common::Intent::In &&
1357           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1358         msg =
1359             "In defined assignment subroutine '%s', second dummy"
1360             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1361       }
1362     } else {
1363       DIE("pos must be 0 or 1");
1364     }
1365   } else {
1366     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1367           " must be a data object"_err_en_US;
1368   }
1369   if (msg) {
1370     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1371     context_.SetError(symbol);
1372     return false;
1373   }
1374   return true;
1375 }
1376 
1377 // Report a conflicting attribute error if symbol has both of these attributes
1378 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1379   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1380     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1381         symbol.name(), AttrToString(a1), AttrToString(a2));
1382     return true;
1383   } else {
1384     return false;
1385   }
1386 }
1387 
1388 void CheckHelper::WarnMissingFinal(const Symbol &symbol) {
1389   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
1390   if (!object || IsPointer(symbol)) {
1391     return;
1392   }
1393   const DeclTypeSpec *type{object->type()};
1394   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
1395   const Symbol *derivedSym{derived ? &derived->typeSymbol() : nullptr};
1396   int rank{object->shape().Rank()};
1397   const Symbol *initialDerivedSym{derivedSym};
1398   while (const auto *derivedDetails{
1399       derivedSym ? derivedSym->detailsIf<DerivedTypeDetails>() : nullptr}) {
1400     if (!derivedDetails->finals().empty() &&
1401         !derivedDetails->GetFinalForRank(rank)) {
1402       if (auto *msg{derivedSym == initialDerivedSym
1403                   ? messages_.Say(symbol.name(),
1404                         "'%s' of derived type '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1405                         symbol.name(), derivedSym->name(), rank)
1406                   : messages_.Say(symbol.name(),
1407                         "'%s' of derived type '%s' extended from '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1408                         symbol.name(), initialDerivedSym->name(),
1409                         derivedSym->name(), rank)}) {
1410         msg->Attach(derivedSym->name(),
1411             "Declaration of derived type '%s'"_en_US, derivedSym->name());
1412       }
1413       return;
1414     }
1415     derived = derivedSym->GetParentTypeSpec();
1416     derivedSym = derived ? &derived->typeSymbol() : nullptr;
1417   }
1418 }
1419 
1420 const Procedure *CheckHelper::Characterize(const Symbol &symbol) {
1421   auto it{characterizeCache_.find(symbol)};
1422   if (it == characterizeCache_.end()) {
1423     auto pair{characterizeCache_.emplace(SymbolRef{symbol},
1424         Procedure::Characterize(symbol, context_.foldingContext()))};
1425     it = pair.first;
1426   }
1427   return common::GetPtrFromOptional(it->second);
1428 }
1429 
1430 void CheckHelper::CheckVolatile(const Symbol &symbol,
1431     const DerivedTypeSpec *derived) { // C866 - C868
1432   if (IsIntentIn(symbol)) {
1433     messages_.Say(
1434         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1435   }
1436   if (IsProcedure(symbol)) {
1437     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1438   }
1439   if (symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()) {
1440     const Symbol &ultimate{symbol.GetUltimate()};
1441     if (IsCoarray(ultimate)) {
1442       messages_.Say(
1443           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1444     }
1445     if (derived) {
1446       if (FindCoarrayUltimateComponent(*derived)) {
1447         messages_.Say(
1448             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1449       }
1450     }
1451   }
1452 }
1453 
1454 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1455   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1456   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1457   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1458   // Prohibit constant pointers.  The standard does not explicitly prohibit
1459   // them, but the PARAMETER attribute requires a entity-decl to have an
1460   // initialization that is a constant-expr, and the only form of
1461   // initialization that allows a constant-expr is the one that's not a "=>"
1462   // pointer initialization.  See C811, C807, and section 8.5.13.
1463   CheckConflicting(symbol, Attr::POINTER, Attr::PARAMETER);
1464   if (symbol.Corank() > 0) {
1465     messages_.Say(
1466         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1467         symbol.name());
1468   }
1469 }
1470 
1471 // C760 constraints on the passed-object dummy argument
1472 // C757 constraints on procedure pointer components
1473 void CheckHelper::CheckPassArg(
1474     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1475   if (proc.attrs().test(Attr::NOPASS)) {
1476     return;
1477   }
1478   const auto &name{proc.name()};
1479   if (!interface) {
1480     messages_.Say(name,
1481         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1482         name);
1483     return;
1484   }
1485   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1486   if (!subprogram) {
1487     messages_.Say(name,
1488         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1489         interface->name());
1490     return;
1491   }
1492   std::optional<SourceName> passName{details.passName()};
1493   const auto &dummyArgs{subprogram->dummyArgs()};
1494   if (!passName) {
1495     if (dummyArgs.empty()) {
1496       messages_.Say(name,
1497           proc.has<ProcEntityDetails>()
1498               ? "Procedure component '%s' with no dummy arguments"
1499                 " must have NOPASS attribute"_err_en_US
1500               : "Procedure binding '%s' with no dummy arguments"
1501                 " must have NOPASS attribute"_err_en_US,
1502           name);
1503       context_.SetError(*interface);
1504       return;
1505     }
1506     Symbol *argSym{dummyArgs[0]};
1507     if (!argSym) {
1508       messages_.Say(interface->name(),
1509           "Cannot use an alternate return as the passed-object dummy "
1510           "argument"_err_en_US);
1511       return;
1512     }
1513     passName = dummyArgs[0]->name();
1514   }
1515   std::optional<int> passArgIndex{};
1516   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1517     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1518       passArgIndex = i;
1519       break;
1520     }
1521   }
1522   if (!passArgIndex) { // C758
1523     messages_.Say(*passName,
1524         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1525         *passName, interface->name());
1526     return;
1527   }
1528   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1529   std::optional<parser::MessageFixedText> msg;
1530   if (!passArg.has<ObjectEntityDetails>()) {
1531     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1532           " must be a data object"_err_en_US;
1533   } else if (passArg.attrs().test(Attr::POINTER)) {
1534     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1535           " may not have the POINTER attribute"_err_en_US;
1536   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1537     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1538           " may not have the ALLOCATABLE attribute"_err_en_US;
1539   } else if (passArg.attrs().test(Attr::VALUE)) {
1540     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1541           " may not have the VALUE attribute"_err_en_US;
1542   } else if (passArg.Rank() > 0) {
1543     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1544           " must be scalar"_err_en_US;
1545   }
1546   if (msg) {
1547     messages_.Say(name, std::move(*msg), passName.value(), name);
1548     return;
1549   }
1550   const DeclTypeSpec *type{passArg.GetType()};
1551   if (!type) {
1552     return; // an error already occurred
1553   }
1554   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1555   const DerivedTypeSpec *derived{type->AsDerived()};
1556   if (!derived || derived->typeSymbol() != typeSymbol) {
1557     messages_.Say(name,
1558         "Passed-object dummy argument '%s' of procedure '%s'"
1559         " must be of type '%s' but is '%s'"_err_en_US,
1560         passName.value(), name, typeSymbol.name(), type->AsFortran());
1561     return;
1562   }
1563   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1564     messages_.Say(name,
1565         type->IsPolymorphic()
1566             ? "Passed-object dummy argument '%s' of procedure '%s'"
1567               " may not be polymorphic because '%s' is not extensible"_err_en_US
1568             : "Passed-object dummy argument '%s' of procedure '%s'"
1569               " must be polymorphic because '%s' is extensible"_err_en_US,
1570         passName.value(), name, typeSymbol.name());
1571     return;
1572   }
1573   for (const auto &[paramName, paramValue] : derived->parameters()) {
1574     if (paramValue.isLen() && !paramValue.isAssumed()) {
1575       messages_.Say(name,
1576           "Passed-object dummy argument '%s' of procedure '%s'"
1577           " has non-assumed length parameter '%s'"_err_en_US,
1578           passName.value(), name, paramName);
1579     }
1580   }
1581 }
1582 
1583 void CheckHelper::CheckProcBinding(
1584     const Symbol &symbol, const ProcBindingDetails &binding) {
1585   const Scope &dtScope{symbol.owner()};
1586   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1587   if (symbol.attrs().test(Attr::DEFERRED)) {
1588     if (const Symbol * dtSymbol{dtScope.symbol()}) {
1589       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1590         SayWithDeclaration(*dtSymbol,
1591             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1592             dtSymbol->name());
1593       }
1594     }
1595     if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1596       messages_.Say(
1597           "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1598           symbol.name());
1599     }
1600   }
1601   if (binding.symbol().attrs().test(Attr::INTRINSIC) &&
1602       !context_.intrinsics().IsSpecificIntrinsicFunction(
1603           binding.symbol().name().ToString())) {
1604     messages_.Say(
1605         "Intrinsic procedure '%s' is not a specific intrinsic permitted for use in the definition of binding '%s'"_err_en_US,
1606         binding.symbol().name(), symbol.name());
1607   }
1608   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1609     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1610       SayWithDeclaration(*overridden,
1611           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1612           symbol.name());
1613     }
1614     if (const auto *overriddenBinding{
1615             overridden->detailsIf<ProcBindingDetails>()}) {
1616       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1617         SayWithDeclaration(*overridden,
1618             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1619         return;
1620       }
1621       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1622           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1623         SayWithDeclaration(*overridden,
1624             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1625         return;
1626       }
1627       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1628       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1629         SayWithDeclaration(*overridden,
1630             isNopass
1631                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1632                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1633       } else {
1634         const auto *bindingChars{Characterize(binding.symbol())};
1635         const auto *overriddenChars{Characterize(overriddenBinding->symbol())};
1636         if (bindingChars && overriddenChars) {
1637           if (isNopass) {
1638             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1639               SayWithDeclaration(*overridden,
1640                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1641             }
1642           } else if (!context_.HasError(binding.symbol())) {
1643             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1644             int overriddenPassIndex{
1645                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1646             if (passIndex != overriddenPassIndex) {
1647               SayWithDeclaration(*overridden,
1648                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1649             } else if (!bindingChars->CanOverride(
1650                            *overriddenChars, passIndex)) {
1651               SayWithDeclaration(*overridden,
1652                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1653             }
1654           }
1655         }
1656       }
1657       if (symbol.attrs().test(Attr::PRIVATE) &&
1658           overridden->attrs().test(Attr::PUBLIC)) {
1659         SayWithDeclaration(*overridden,
1660             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1661       }
1662     } else {
1663       SayWithDeclaration(*overridden,
1664           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1665     }
1666   }
1667   CheckPassArg(symbol, &binding.symbol(), binding);
1668 }
1669 
1670 void CheckHelper::Check(const Scope &scope) {
1671   scope_ = &scope;
1672   common::Restorer<const Symbol *> restorer{innermostSymbol_, innermostSymbol_};
1673   if (const Symbol * symbol{scope.symbol()}) {
1674     innermostSymbol_ = symbol;
1675   }
1676   if (scope.IsParameterizedDerivedTypeInstantiation()) {
1677     auto restorer{common::ScopedSet(scopeIsUninstantiatedPDT_, false)};
1678     auto restorer2{context_.foldingContext().messages().SetContext(
1679         scope.instantiationContext().get())};
1680     for (const auto &pair : scope) {
1681       CheckPointerInitialization(*pair.second);
1682     }
1683   } else {
1684     auto restorer{common::ScopedSet(
1685         scopeIsUninstantiatedPDT_, scope.IsParameterizedDerivedType())};
1686     for (const auto &set : scope.equivalenceSets()) {
1687       CheckEquivalenceSet(set);
1688     }
1689     for (const auto &pair : scope) {
1690       Check(*pair.second);
1691     }
1692     for (const Scope &child : scope.children()) {
1693       Check(child);
1694     }
1695     if (scope.kind() == Scope::Kind::BlockData) {
1696       CheckBlockData(scope);
1697     }
1698     CheckGenericOps(scope);
1699   }
1700 }
1701 
1702 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1703   auto iter{
1704       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1705         return FindCommonBlockContaining(object.symbol) != nullptr;
1706       })};
1707   if (iter != set.end()) {
1708     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1709     for (auto &object : set) {
1710       if (&object != &*iter) {
1711         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1712           if (details->commonBlock()) {
1713             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1714               if (auto *msg{messages_.Say(object.symbol.name(),
1715                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1716                 msg->Attach(iter->symbol.name(),
1717                        "Other object in EQUIVALENCE set"_en_US)
1718                     .Attach(details->commonBlock()->name(),
1719                         "COMMON block containing '%s'"_en_US,
1720                         object.symbol.name())
1721                     .Attach(commonBlock.name(),
1722                         "COMMON block containing '%s'"_en_US,
1723                         iter->symbol.name());
1724               }
1725             }
1726           } else {
1727             // Mark all symbols in the equivalence set with the same COMMON
1728             // block to prevent spurious error messages about initialization
1729             // in BLOCK DATA outside COMMON
1730             details->set_commonBlock(commonBlock);
1731           }
1732         }
1733       }
1734     }
1735   }
1736   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1737 }
1738 
1739 void CheckHelper::CheckBlockData(const Scope &scope) {
1740   // BLOCK DATA subprograms should contain only named common blocks.
1741   // C1415 presents a list of statements that shouldn't appear in
1742   // BLOCK DATA, but so long as the subprogram contains no executable
1743   // code and allocates no storage outside named COMMON, we're happy
1744   // (e.g., an ENUM is strictly not allowed).
1745   for (const auto &pair : scope) {
1746     const Symbol &symbol{*pair.second};
1747     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1748             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1749             symbol.has<SubprogramDetails>() ||
1750             symbol.has<ObjectEntityDetails>() ||
1751             (symbol.has<ProcEntityDetails>() &&
1752                 !symbol.attrs().test(Attr::POINTER)))) {
1753       messages_.Say(symbol.name(),
1754           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1755           symbol.name());
1756     }
1757   }
1758 }
1759 
1760 // Check distinguishability of generic assignment and operators.
1761 // For these, generics and generic bindings must be considered together.
1762 void CheckHelper::CheckGenericOps(const Scope &scope) {
1763   DistinguishabilityHelper helper{context_};
1764   auto addSpecifics{[&](const Symbol &generic) {
1765     const auto *details{generic.GetUltimate().detailsIf<GenericDetails>()};
1766     if (!details) {
1767       return;
1768     }
1769     GenericKind kind{details->kind()};
1770     if (!kind.IsAssignment() && !kind.IsOperator()) {
1771       return;
1772     }
1773     const SymbolVector &specifics{details->specificProcs()};
1774     const std::vector<SourceName> &bindingNames{details->bindingNames()};
1775     for (std::size_t i{0}; i < specifics.size(); ++i) {
1776       const Symbol &specific{*specifics[i]};
1777       if (const Procedure * proc{Characterize(specific)}) {
1778         auto restorer{messages_.SetLocation(bindingNames[i])};
1779         if (kind.IsAssignment()) {
1780           if (!CheckDefinedAssignment(specific, *proc)) {
1781             continue;
1782           }
1783         } else {
1784           if (!CheckDefinedOperator(generic.name(), kind, specific, *proc)) {
1785             continue;
1786           }
1787         }
1788         helper.Add(generic, kind, specific, *proc);
1789       }
1790     }
1791   }};
1792   for (const auto &pair : scope) {
1793     const Symbol &symbol{*pair.second};
1794     addSpecifics(symbol);
1795     const Symbol &ultimate{symbol.GetUltimate()};
1796     if (ultimate.has<DerivedTypeDetails>()) {
1797       if (const Scope * typeScope{ultimate.scope()}) {
1798         for (const auto &pair2 : *typeScope) {
1799           addSpecifics(*pair2.second);
1800         }
1801       }
1802     }
1803   }
1804   helper.Check(scope);
1805 }
1806 
1807 static const std::string *DefinesBindCName(const Symbol &symbol) {
1808   const auto *subp{symbol.detailsIf<SubprogramDetails>()};
1809   if ((subp && !subp->isInterface()) || symbol.has<ObjectEntityDetails>()) {
1810     // Symbol defines data or entry point
1811     return symbol.GetBindName();
1812   } else {
1813     return nullptr;
1814   }
1815 }
1816 
1817 // Check that BIND(C) names are distinct
1818 void CheckHelper::CheckBindCName(const Symbol &symbol) {
1819   if (const std::string * name{DefinesBindCName(symbol)}) {
1820     auto pair{bindC_.emplace(*name, symbol)};
1821     if (!pair.second) {
1822       const Symbol &other{*pair.first->second};
1823       if (DefinesBindCName(other) && !context_.HasError(other)) {
1824         if (auto *msg{messages_.Say(
1825                 "Two symbols have the same BIND(C) name '%s'"_err_en_US,
1826                 *name)}) {
1827           msg->Attach(other.name(), "Conflicting symbol"_en_US);
1828         }
1829         context_.SetError(symbol);
1830         context_.SetError(other);
1831       }
1832     }
1833   }
1834 }
1835 
1836 bool CheckHelper::CheckDioDummyIsData(
1837     const Symbol &subp, const Symbol *arg, std::size_t position) {
1838   if (arg && arg->detailsIf<ObjectEntityDetails>()) {
1839     return true;
1840   } else {
1841     if (arg) {
1842       messages_.Say(arg->name(),
1843           "Dummy argument '%s' must be a data object"_err_en_US, arg->name());
1844     } else {
1845       messages_.Say(subp.name(),
1846           "Dummy argument %d of '%s' must be a data object"_err_en_US, position,
1847           subp.name());
1848     }
1849     return false;
1850   }
1851 }
1852 
1853 void CheckHelper::CheckAlreadySeenDefinedIo(const DerivedTypeSpec *derivedType,
1854     GenericKind::DefinedIo ioKind, const Symbol &proc) {
1855   for (TypeWithDefinedIo definedIoType : seenDefinedIoTypes_) {
1856     if (*derivedType == *definedIoType.type && ioKind == definedIoType.ioKind &&
1857         proc != definedIoType.proc) {
1858       SayWithDeclaration(proc, definedIoType.proc.name(),
1859           "Derived type '%s' already has defined input/output procedure"
1860           " '%s'"_err_en_US,
1861           derivedType->name(),
1862           parser::ToUpperCaseLetters(GenericKind::EnumToString(ioKind)));
1863       return;
1864     }
1865   }
1866   seenDefinedIoTypes_.emplace_back(
1867       TypeWithDefinedIo{derivedType, ioKind, proc});
1868 }
1869 
1870 void CheckHelper::CheckDioDummyIsDerived(
1871     const Symbol &subp, const Symbol &arg, GenericKind::DefinedIo ioKind) {
1872   if (const DeclTypeSpec * type{arg.GetType()}) {
1873     if (const DerivedTypeSpec * derivedType{type->AsDerived()}) {
1874       CheckAlreadySeenDefinedIo(derivedType, ioKind, subp);
1875       bool isPolymorphic{type->IsPolymorphic()};
1876       if (isPolymorphic != IsExtensibleType(derivedType)) {
1877         messages_.Say(arg.name(),
1878             "Dummy argument '%s' of a defined input/output procedure must be %s when the derived type is %s"_err_en_US,
1879             arg.name(), isPolymorphic ? "TYPE()" : "CLASS()",
1880             isPolymorphic ? "not extensible" : "extensible");
1881       }
1882     } else {
1883       messages_.Say(arg.name(),
1884           "Dummy argument '%s' of a defined input/output procedure must have a"
1885           " derived type"_err_en_US,
1886           arg.name());
1887     }
1888   }
1889 }
1890 
1891 void CheckHelper::CheckDioDummyIsDefaultInteger(
1892     const Symbol &subp, const Symbol &arg) {
1893   if (const DeclTypeSpec * type{arg.GetType()};
1894       type && type->IsNumeric(TypeCategory::Integer)) {
1895     if (const auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
1896         kind && *kind == context_.GetDefaultKind(TypeCategory::Integer)) {
1897       return;
1898     }
1899   }
1900   messages_.Say(arg.name(),
1901       "Dummy argument '%s' of a defined input/output procedure"
1902       " must be an INTEGER of default KIND"_err_en_US,
1903       arg.name());
1904 }
1905 
1906 void CheckHelper::CheckDioDummyIsScalar(const Symbol &subp, const Symbol &arg) {
1907   if (arg.Rank() > 0 || arg.Corank() > 0) {
1908     messages_.Say(arg.name(),
1909         "Dummy argument '%s' of a defined input/output procedure"
1910         " must be a scalar"_err_en_US,
1911         arg.name());
1912   }
1913 }
1914 
1915 void CheckHelper::CheckDioDtvArg(
1916     const Symbol &subp, const Symbol *arg, GenericKind::DefinedIo ioKind) {
1917   // Dtv argument looks like: dtv-type-spec, INTENT(INOUT) :: dtv
1918   if (CheckDioDummyIsData(subp, arg, 0)) {
1919     CheckDioDummyIsDerived(subp, *arg, ioKind);
1920     CheckDioDummyAttrs(subp, *arg,
1921         ioKind == GenericKind::DefinedIo::ReadFormatted ||
1922                 ioKind == GenericKind::DefinedIo::ReadUnformatted
1923             ? Attr::INTENT_INOUT
1924             : Attr::INTENT_IN);
1925   }
1926 }
1927 
1928 void CheckHelper::CheckDefaultIntegerArg(
1929     const Symbol &subp, const Symbol *arg, Attr intent) {
1930   // Argument looks like: INTEGER, INTENT(intent) :: arg
1931   if (CheckDioDummyIsData(subp, arg, 1)) {
1932     CheckDioDummyIsDefaultInteger(subp, *arg);
1933     CheckDioDummyIsScalar(subp, *arg);
1934     CheckDioDummyAttrs(subp, *arg, intent);
1935   }
1936 }
1937 
1938 void CheckHelper::CheckDioAssumedLenCharacterArg(const Symbol &subp,
1939     const Symbol *arg, std::size_t argPosition, Attr intent) {
1940   // Argument looks like: CHARACTER (LEN=*), INTENT(intent) :: (iotype OR iomsg)
1941   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1942     CheckDioDummyAttrs(subp, *arg, intent);
1943     if (!IsAssumedLengthCharacter(*arg)) {
1944       messages_.Say(arg->name(),
1945           "Dummy argument '%s' of a defined input/output procedure"
1946           " must be assumed-length CHARACTER"_err_en_US,
1947           arg->name());
1948     }
1949   }
1950 }
1951 
1952 void CheckHelper::CheckDioVlistArg(
1953     const Symbol &subp, const Symbol *arg, std::size_t argPosition) {
1954   // Vlist argument looks like: INTEGER, INTENT(IN) :: v_list(:)
1955   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1956     CheckDioDummyIsDefaultInteger(subp, *arg);
1957     CheckDioDummyAttrs(subp, *arg, Attr::INTENT_IN);
1958     if (const auto *objectDetails{arg->detailsIf<ObjectEntityDetails>()}) {
1959       if (objectDetails->shape().IsDeferredShape()) {
1960         return;
1961       }
1962     }
1963     messages_.Say(arg->name(),
1964         "Dummy argument '%s' of a defined input/output procedure must be"
1965         " deferred shape"_err_en_US,
1966         arg->name());
1967   }
1968 }
1969 
1970 void CheckHelper::CheckDioArgCount(
1971     const Symbol &subp, GenericKind::DefinedIo ioKind, std::size_t argCount) {
1972   const std::size_t requiredArgCount{
1973       (std::size_t)(ioKind == GenericKind::DefinedIo::ReadFormatted ||
1974                   ioKind == GenericKind::DefinedIo::WriteFormatted
1975               ? 6
1976               : 4)};
1977   if (argCount != requiredArgCount) {
1978     SayWithDeclaration(subp,
1979         "Defined input/output procedure '%s' must have"
1980         " %d dummy arguments rather than %d"_err_en_US,
1981         subp.name(), requiredArgCount, argCount);
1982     context_.SetError(subp);
1983   }
1984 }
1985 
1986 void CheckHelper::CheckDioDummyAttrs(
1987     const Symbol &subp, const Symbol &arg, Attr goodIntent) {
1988   // Defined I/O procedures can't have attributes other than INTENT
1989   Attrs attrs{arg.attrs()};
1990   if (!attrs.test(goodIntent)) {
1991     messages_.Say(arg.name(),
1992         "Dummy argument '%s' of a defined input/output procedure"
1993         " must have intent '%s'"_err_en_US,
1994         arg.name(), AttrToString(goodIntent));
1995   }
1996   attrs = attrs - Attr::INTENT_IN - Attr::INTENT_OUT - Attr::INTENT_INOUT;
1997   if (!attrs.empty()) {
1998     messages_.Say(arg.name(),
1999         "Dummy argument '%s' of a defined input/output procedure may not have"
2000         " any attributes"_err_en_US,
2001         arg.name());
2002   }
2003 }
2004 
2005 // Enforce semantics for defined input/output procedures (12.6.4.8.2) and C777
2006 void CheckHelper::CheckDefinedIoProc(const Symbol &symbol,
2007     const GenericDetails &details, GenericKind::DefinedIo ioKind) {
2008   for (auto ref : details.specificProcs()) {
2009     const auto *binding{ref->detailsIf<ProcBindingDetails>()};
2010     const Symbol &specific{*(binding ? &binding->symbol() : &*ref)};
2011     if (ref->attrs().test(Attr::NOPASS)) { // C774
2012       messages_.Say("Defined input/output procedure '%s' may not have NOPASS "
2013                     "attribute"_err_en_US,
2014           ref->name());
2015       context_.SetError(*ref);
2016     }
2017     if (const auto *subpDetails{specific.detailsIf<SubprogramDetails>()}) {
2018       const std::vector<Symbol *> &dummyArgs{subpDetails->dummyArgs()};
2019       CheckDioArgCount(specific, ioKind, dummyArgs.size());
2020       int argCount{0};
2021       for (auto *arg : dummyArgs) {
2022         switch (argCount++) {
2023         case 0:
2024           // dtv-type-spec, INTENT(INOUT) :: dtv
2025           CheckDioDtvArg(specific, arg, ioKind);
2026           break;
2027         case 1:
2028           // INTEGER, INTENT(IN) :: unit
2029           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_IN);
2030           break;
2031         case 2:
2032           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2033               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2034             // CHARACTER (LEN=*), INTENT(IN) :: iotype
2035             CheckDioAssumedLenCharacterArg(
2036                 specific, arg, argCount, Attr::INTENT_IN);
2037           } else {
2038             // INTEGER, INTENT(OUT) :: iostat
2039             CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2040           }
2041           break;
2042         case 3:
2043           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2044               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2045             // INTEGER, INTENT(IN) :: v_list(:)
2046             CheckDioVlistArg(specific, arg, argCount);
2047           } else {
2048             // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2049             CheckDioAssumedLenCharacterArg(
2050                 specific, arg, argCount, Attr::INTENT_INOUT);
2051           }
2052           break;
2053         case 4:
2054           // INTEGER, INTENT(OUT) :: iostat
2055           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2056           break;
2057         case 5:
2058           // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2059           CheckDioAssumedLenCharacterArg(
2060               specific, arg, argCount, Attr::INTENT_INOUT);
2061           break;
2062         default:;
2063         }
2064       }
2065     }
2066   }
2067 }
2068 
2069 void SubprogramMatchHelper::Check(
2070     const Symbol &symbol1, const Symbol &symbol2) {
2071   const auto details1{symbol1.get<SubprogramDetails>()};
2072   const auto details2{symbol2.get<SubprogramDetails>()};
2073   if (details1.isFunction() != details2.isFunction()) {
2074     Say(symbol1, symbol2,
2075         details1.isFunction()
2076             ? "Module function '%s' was declared as a subroutine in the"
2077               " corresponding interface body"_err_en_US
2078             : "Module subroutine '%s' was declared as a function in the"
2079               " corresponding interface body"_err_en_US);
2080     return;
2081   }
2082   const auto &args1{details1.dummyArgs()};
2083   const auto &args2{details2.dummyArgs()};
2084   int nargs1{static_cast<int>(args1.size())};
2085   int nargs2{static_cast<int>(args2.size())};
2086   if (nargs1 != nargs2) {
2087     Say(symbol1, symbol2,
2088         "Module subprogram '%s' has %d args but the corresponding interface"
2089         " body has %d"_err_en_US,
2090         nargs1, nargs2);
2091     return;
2092   }
2093   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
2094   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
2095     Say(symbol1, symbol2,
2096         nonRecursive1
2097             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
2098               " the corresponding interface body does not"_err_en_US
2099             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
2100               "the corresponding interface body does"_err_en_US);
2101   }
2102   const std::string *bindName1{details1.bindName()};
2103   const std::string *bindName2{details2.bindName()};
2104   if (!bindName1 && !bindName2) {
2105     // OK - neither has a binding label
2106   } else if (!bindName1) {
2107     Say(symbol1, symbol2,
2108         "Module subprogram '%s' does not have a binding label but the"
2109         " corresponding interface body does"_err_en_US);
2110   } else if (!bindName2) {
2111     Say(symbol1, symbol2,
2112         "Module subprogram '%s' has a binding label but the"
2113         " corresponding interface body does not"_err_en_US);
2114   } else if (*bindName1 != *bindName2) {
2115     Say(symbol1, symbol2,
2116         "Module subprogram '%s' has binding label '%s' but the corresponding"
2117         " interface body has '%s'"_err_en_US,
2118         *details1.bindName(), *details2.bindName());
2119   }
2120   const Procedure *proc1{checkHelper.Characterize(symbol1)};
2121   const Procedure *proc2{checkHelper.Characterize(symbol2)};
2122   if (!proc1 || !proc2) {
2123     return;
2124   }
2125   if (proc1->functionResult && proc2->functionResult &&
2126       *proc1->functionResult != *proc2->functionResult) {
2127     Say(symbol1, symbol2,
2128         "Return type of function '%s' does not match return type of"
2129         " the corresponding interface body"_err_en_US);
2130   }
2131   for (int i{0}; i < nargs1; ++i) {
2132     const Symbol *arg1{args1[i]};
2133     const Symbol *arg2{args2[i]};
2134     if (arg1 && !arg2) {
2135       Say(symbol1, symbol2,
2136           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
2137           " but the corresponding argument in the interface body is"_err_en_US,
2138           i + 1);
2139     } else if (!arg1 && arg2) {
2140       Say(symbol1, symbol2,
2141           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
2142           " the corresponding argument in the interface body is not"_err_en_US,
2143           i + 1);
2144     } else if (arg1 && arg2) {
2145       SourceName name1{arg1->name()};
2146       SourceName name2{arg2->name()};
2147       if (name1 != name2) {
2148         Say(*arg1, *arg2,
2149             "Dummy argument name '%s' does not match corresponding name '%s'"
2150             " in interface body"_err_en_US,
2151             name2);
2152       } else {
2153         CheckDummyArg(
2154             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
2155       }
2156     }
2157   }
2158 }
2159 
2160 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
2161     const Symbol &symbol2, const DummyArgument &arg1,
2162     const DummyArgument &arg2) {
2163   std::visit(common::visitors{
2164                  [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
2165                    CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
2166                  },
2167                  [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
2168                    CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
2169                  },
2170                  [&](const DummyDataObject &, const auto &) {
2171                    Say(symbol1, symbol2,
2172                        "Dummy argument '%s' is a data object; the corresponding"
2173                        " argument in the interface body is not"_err_en_US);
2174                  },
2175                  [&](const DummyProcedure &, const auto &) {
2176                    Say(symbol1, symbol2,
2177                        "Dummy argument '%s' is a procedure; the corresponding"
2178                        " argument in the interface body is not"_err_en_US);
2179                  },
2180                  [&](const auto &, const auto &) {
2181                    llvm_unreachable("Dummy arguments are not data objects or"
2182                                     "procedures");
2183                  },
2184              },
2185       arg1.u, arg2.u);
2186 }
2187 
2188 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
2189     const Symbol &symbol2, const DummyDataObject &obj1,
2190     const DummyDataObject &obj2) {
2191   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
2192   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
2193   } else if (obj1.type.type() != obj2.type.type()) {
2194     Say(symbol1, symbol2,
2195         "Dummy argument '%s' has type %s; the corresponding argument in the"
2196         " interface body has type %s"_err_en_US,
2197         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
2198   } else if (!ShapesAreCompatible(obj1, obj2)) {
2199     Say(symbol1, symbol2,
2200         "The shape of dummy argument '%s' does not match the shape of the"
2201         " corresponding argument in the interface body"_err_en_US);
2202   }
2203   // TODO: coshape
2204 }
2205 
2206 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
2207     const Symbol &symbol2, const DummyProcedure &proc1,
2208     const DummyProcedure &proc2) {
2209   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
2210   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
2211   } else if (proc1 != proc2) {
2212     Say(symbol1, symbol2,
2213         "Dummy procedure '%s' does not match the corresponding argument in"
2214         " the interface body"_err_en_US);
2215   }
2216 }
2217 
2218 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
2219     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
2220   if (intent1 == intent2) {
2221     return true;
2222   } else {
2223     Say(symbol1, symbol2,
2224         "The intent of dummy argument '%s' does not match the intent"
2225         " of the corresponding argument in the interface body"_err_en_US);
2226     return false;
2227   }
2228 }
2229 
2230 // Report an error referring to first symbol with declaration of second symbol
2231 template <typename... A>
2232 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
2233     parser::MessageFixedText &&text, A &&...args) {
2234   auto &message{context().Say(symbol1.name(), std::move(text), symbol1.name(),
2235       std::forward<A>(args)...)};
2236   evaluate::AttachDeclaration(message, symbol2);
2237 }
2238 
2239 template <typename ATTRS>
2240 bool SubprogramMatchHelper::CheckSameAttrs(
2241     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
2242   if (attrs1 == attrs2) {
2243     return true;
2244   }
2245   attrs1.IterateOverMembers([&](auto attr) {
2246     if (!attrs2.test(attr)) {
2247       Say(symbol1, symbol2,
2248           "Dummy argument '%s' has the %s attribute; the corresponding"
2249           " argument in the interface body does not"_err_en_US,
2250           AsFortran(attr));
2251     }
2252   });
2253   attrs2.IterateOverMembers([&](auto attr) {
2254     if (!attrs1.test(attr)) {
2255       Say(symbol1, symbol2,
2256           "Dummy argument '%s' does not have the %s attribute; the"
2257           " corresponding argument in the interface body does"_err_en_US,
2258           AsFortran(attr));
2259     }
2260   });
2261   return false;
2262 }
2263 
2264 bool SubprogramMatchHelper::ShapesAreCompatible(
2265     const DummyDataObject &obj1, const DummyDataObject &obj2) {
2266   return characteristics::ShapesAreCompatible(
2267       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
2268 }
2269 
2270 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
2271   evaluate::Shape result;
2272   for (const auto &extent : shape) {
2273     result.emplace_back(
2274         evaluate::Fold(context().foldingContext(), common::Clone(extent)));
2275   }
2276   return result;
2277 }
2278 
2279 void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
2280     const Symbol &specific, const Procedure &procedure) {
2281   if (!context_.HasError(specific)) {
2282     nameToInfo_[generic.name()].emplace_back(
2283         ProcedureInfo{kind, specific, procedure});
2284   }
2285 }
2286 
2287 void DistinguishabilityHelper::Check(const Scope &scope) {
2288   for (const auto &[name, info] : nameToInfo_) {
2289     auto count{info.size()};
2290     for (std::size_t i1{0}; i1 < count - 1; ++i1) {
2291       const auto &[kind, symbol, proc]{info[i1]};
2292       for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
2293         auto distinguishable{kind.IsName()
2294                 ? evaluate::characteristics::Distinguishable
2295                 : evaluate::characteristics::DistinguishableOpOrAssign};
2296         if (!distinguishable(proc, info[i2].procedure)) {
2297           SayNotDistinguishable(GetTopLevelUnitContaining(scope), name, kind,
2298               symbol, info[i2].symbol);
2299         }
2300       }
2301     }
2302   }
2303 }
2304 
2305 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
2306     const SourceName &name, GenericKind kind, const Symbol &proc1,
2307     const Symbol &proc2) {
2308   std::string name1{proc1.name().ToString()};
2309   std::string name2{proc2.name().ToString()};
2310   if (kind.IsOperator() || kind.IsAssignment()) {
2311     // proc1 and proc2 may come from different scopes so qualify their names
2312     if (proc1.owner().IsDerivedType()) {
2313       name1 = proc1.owner().GetName()->ToString() + '%' + name1;
2314     }
2315     if (proc2.owner().IsDerivedType()) {
2316       name2 = proc2.owner().GetName()->ToString() + '%' + name2;
2317     }
2318   }
2319   parser::Message *msg;
2320   if (scope.sourceRange().Contains(name)) {
2321     msg = &context_.Say(name,
2322         "Generic '%s' may not have specific procedures '%s' and"
2323         " '%s' as their interfaces are not distinguishable"_err_en_US,
2324         MakeOpName(name), name1, name2);
2325   } else {
2326     msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
2327         "USE-associated generic '%s' may not have specific procedures '%s' "
2328         "and"
2329         " '%s' as their interfaces are not distinguishable"_err_en_US,
2330         MakeOpName(name), name1, name2);
2331   }
2332   AttachDeclaration(*msg, scope, proc1);
2333   AttachDeclaration(*msg, scope, proc2);
2334 }
2335 
2336 // `evaluate::AttachDeclaration` doesn't handle the generic case where `proc`
2337 // comes from a different module but is not necessarily use-associated.
2338 void DistinguishabilityHelper::AttachDeclaration(
2339     parser::Message &msg, const Scope &scope, const Symbol &proc) {
2340   const Scope &unit{GetTopLevelUnitContaining(proc)};
2341   if (unit == scope) {
2342     evaluate::AttachDeclaration(msg, proc);
2343   } else {
2344     msg.Attach(unit.GetName().value(),
2345         "'%s' is USE-associated from module '%s'"_en_US, proc.name(),
2346         unit.GetName().value());
2347   }
2348 }
2349 
2350 void CheckDeclarations(SemanticsContext &context) {
2351   CheckHelper{context}.Check();
2352 }
2353 } // namespace Fortran::semantics
2354