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 (const auto intrinsic{
628                   context_.intrinsics().IsSpecificIntrinsicFunction(
629                       ultimate.name().ToString())};
630               !intrinsic || intrinsic->isRestrictedSpecific) { // C1030
631             context_.Say(
632                 "Intrinsic procedure '%s' is not an unrestricted specific "
633                 "intrinsic permitted for use as the initializer for procedure "
634                 "pointer '%s'"_err_en_US,
635                 ultimate.name(), symbol.name());
636           }
637         } else if (!ultimate.attrs().test(Attr::EXTERNAL) &&
638             ultimate.owner().kind() != Scope::Kind::Module) {
639           context_.Say("Procedure pointer '%s' initializer '%s' is neither "
640                        "an external nor a module procedure"_err_en_US,
641               symbol.name(), ultimate.name());
642         } else if (ultimate.attrs().test(Attr::ELEMENTAL)) {
643           context_.Say("Procedure pointer '%s' cannot be initialized with the "
644                        "elemental procedure '%s"_err_en_US,
645               symbol.name(), ultimate.name());
646         } else {
647           // TODO: Check the "shalls" in the 15.4.3.6 paragraphs 7-10.
648         }
649       }
650     }
651   }
652 }
653 
654 // The six different kinds of array-specs:
655 //   array-spec     -> explicit-shape-list | deferred-shape-list
656 //                     | assumed-shape-list | implied-shape-list
657 //                     | assumed-size | assumed-rank
658 //   explicit-shape -> [ lb : ] ub
659 //   deferred-shape -> :
660 //   assumed-shape  -> [ lb ] :
661 //   implied-shape  -> [ lb : ] *
662 //   assumed-size   -> [ explicit-shape-list , ] [ lb : ] *
663 //   assumed-rank   -> ..
664 // Note:
665 // - deferred-shape is also an assumed-shape
666 // - A single "*" or "lb:*" might be assumed-size or implied-shape-list
667 void CheckHelper::CheckArraySpec(
668     const Symbol &symbol, const ArraySpec &arraySpec) {
669   if (arraySpec.Rank() == 0) {
670     return;
671   }
672   bool isExplicit{arraySpec.IsExplicitShape()};
673   bool isDeferred{arraySpec.IsDeferredShape()};
674   bool isImplied{arraySpec.IsImpliedShape()};
675   bool isAssumedShape{arraySpec.IsAssumedShape()};
676   bool isAssumedSize{arraySpec.IsAssumedSize()};
677   bool isAssumedRank{arraySpec.IsAssumedRank()};
678   std::optional<parser::MessageFixedText> msg;
679   if (symbol.test(Symbol::Flag::CrayPointee) && !isExplicit && !isAssumedSize) {
680     msg = "Cray pointee '%s' must have must have explicit shape or"
681           " assumed size"_err_en_US;
682   } else if (IsAllocatableOrPointer(symbol) && !isDeferred && !isAssumedRank) {
683     if (symbol.owner().IsDerivedType()) { // C745
684       if (IsAllocatable(symbol)) {
685         msg = "Allocatable array component '%s' must have"
686               " deferred shape"_err_en_US;
687       } else {
688         msg = "Array pointer component '%s' must have deferred shape"_err_en_US;
689       }
690     } else {
691       if (IsAllocatable(symbol)) { // C832
692         msg = "Allocatable array '%s' must have deferred shape or"
693               " assumed rank"_err_en_US;
694       } else {
695         msg = "Array pointer '%s' must have deferred shape or"
696               " assumed rank"_err_en_US;
697       }
698     }
699   } else if (IsDummy(symbol)) {
700     if (isImplied && !isAssumedSize) { // C836
701       msg = "Dummy array argument '%s' may not have implied shape"_err_en_US;
702     }
703   } else if (isAssumedShape && !isDeferred) {
704     msg = "Assumed-shape array '%s' must be a dummy argument"_err_en_US;
705   } else if (isAssumedSize && !isImplied) { // C833
706     msg = "Assumed-size array '%s' must be a dummy argument"_err_en_US;
707   } else if (isAssumedRank) { // C837
708     msg = "Assumed-rank array '%s' must be a dummy argument"_err_en_US;
709   } else if (isImplied) {
710     if (!IsNamedConstant(symbol)) { // C835, C836
711       msg = "Implied-shape array '%s' must be a named constant or a "
712             "dummy argument"_err_en_US;
713     }
714   } else if (IsNamedConstant(symbol)) {
715     if (!isExplicit && !isImplied) {
716       msg = "Named constant '%s' array must have constant or"
717             " implied shape"_err_en_US;
718     }
719   } else if (!IsAllocatableOrPointer(symbol) && !isExplicit) {
720     if (symbol.owner().IsDerivedType()) { // C749
721       msg = "Component array '%s' without ALLOCATABLE or POINTER attribute must"
722             " have explicit shape"_err_en_US;
723     } else { // C816
724       msg = "Array '%s' without ALLOCATABLE or POINTER attribute must have"
725             " explicit shape"_err_en_US;
726     }
727   }
728   if (msg) {
729     context_.Say(std::move(*msg), symbol.name());
730   }
731 }
732 
733 void CheckHelper::CheckProcEntity(
734     const Symbol &symbol, const ProcEntityDetails &details) {
735   if (details.isDummy()) {
736     if (!symbol.attrs().test(Attr::POINTER) && // C843
737         (symbol.attrs().test(Attr::INTENT_IN) ||
738             symbol.attrs().test(Attr::INTENT_OUT) ||
739             symbol.attrs().test(Attr::INTENT_INOUT))) {
740       messages_.Say("A dummy procedure without the POINTER attribute"
741                     " may not have an INTENT attribute"_err_en_US);
742     }
743     if (InElemental()) { // C15100
744       messages_.Say(
745           "An ELEMENTAL subprogram may not have a dummy procedure"_err_en_US);
746     }
747     const Symbol *interface { details.interface().symbol() };
748     if (!symbol.attrs().test(Attr::INTRINSIC) &&
749         (symbol.attrs().test(Attr::ELEMENTAL) ||
750             (interface && !interface->attrs().test(Attr::INTRINSIC) &&
751                 interface->attrs().test(Attr::ELEMENTAL)))) {
752       // There's no explicit constraint or "shall" that we can find in the
753       // standard for this check, but it seems to be implied in multiple
754       // sites, and ELEMENTAL non-intrinsic actual arguments *are*
755       // explicitly forbidden.  But we allow "PROCEDURE(SIN)::dummy"
756       // because it is explicitly legal to *pass* the specific intrinsic
757       // function SIN as an actual argument.
758       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
759     }
760   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
761       symbol.attrs().test(Attr::INTENT_OUT) ||
762       symbol.attrs().test(Attr::INTENT_INOUT)) {
763     messages_.Say("INTENT attributes may apply only to a dummy "
764                   "argument"_err_en_US); // C843
765   } else if (IsOptional(symbol)) {
766     messages_.Say("OPTIONAL attribute may apply only to a dummy "
767                   "argument"_err_en_US); // C849
768   } else if (symbol.owner().IsDerivedType()) {
769     if (!symbol.attrs().test(Attr::POINTER)) { // C756
770       const auto &name{symbol.name()};
771       messages_.Say(name,
772           "Procedure component '%s' must have POINTER attribute"_err_en_US,
773           name);
774     }
775     CheckPassArg(symbol, details.interface().symbol(), details);
776   }
777   if (symbol.attrs().test(Attr::POINTER)) {
778     CheckPointerInitialization(symbol);
779     if (const Symbol * interface{details.interface().symbol()}) {
780       if (interface->attrs().test(Attr::INTRINSIC)) {
781         if (const auto intrinsic{
782                 context_.intrinsics().IsSpecificIntrinsicFunction(
783                     interface->name().ToString())};
784             !intrinsic || intrinsic->isRestrictedSpecific) { // C1515
785           messages_.Say(
786               "Intrinsic procedure '%s' is not an unrestricted specific "
787               "intrinsic permitted for use as the definition of the interface "
788               "to procedure pointer '%s'"_err_en_US,
789               interface->name(), symbol.name());
790         }
791       } else if (interface->attrs().test(Attr::ELEMENTAL)) {
792         messages_.Say("Procedure pointer '%s' may not be ELEMENTAL"_err_en_US,
793             symbol.name()); // C1517
794       }
795     }
796   } else if (symbol.attrs().test(Attr::SAVE)) {
797     messages_.Say(
798         "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US,
799         symbol.name());
800   }
801 }
802 
803 // When a module subprogram has the MODULE prefix the following must match
804 // with the corresponding separate module procedure interface body:
805 // - C1549: characteristics and dummy argument names
806 // - C1550: binding label
807 // - C1551: NON_RECURSIVE prefix
808 class SubprogramMatchHelper {
809 public:
810   explicit SubprogramMatchHelper(CheckHelper &checkHelper)
811       : checkHelper{checkHelper} {}
812 
813   void Check(const Symbol &, const Symbol &);
814 
815 private:
816   SemanticsContext &context() { return checkHelper.context(); }
817   void CheckDummyArg(const Symbol &, const Symbol &, const DummyArgument &,
818       const DummyArgument &);
819   void CheckDummyDataObject(const Symbol &, const Symbol &,
820       const DummyDataObject &, const DummyDataObject &);
821   void CheckDummyProcedure(const Symbol &, const Symbol &,
822       const DummyProcedure &, const DummyProcedure &);
823   bool CheckSameIntent(
824       const Symbol &, const Symbol &, common::Intent, common::Intent);
825   template <typename... A>
826   void Say(
827       const Symbol &, const Symbol &, parser::MessageFixedText &&, A &&...);
828   template <typename ATTRS>
829   bool CheckSameAttrs(const Symbol &, const Symbol &, ATTRS, ATTRS);
830   bool ShapesAreCompatible(const DummyDataObject &, const DummyDataObject &);
831   evaluate::Shape FoldShape(const evaluate::Shape &);
832   std::string AsFortran(DummyDataObject::Attr attr) {
833     return parser::ToUpperCaseLetters(DummyDataObject::EnumToString(attr));
834   }
835   std::string AsFortran(DummyProcedure::Attr attr) {
836     return parser::ToUpperCaseLetters(DummyProcedure::EnumToString(attr));
837   }
838 
839   CheckHelper &checkHelper;
840 };
841 
842 // 15.6.2.6 para 3 - can the result of an ENTRY differ from its function?
843 bool CheckHelper::IsResultOkToDiffer(const FunctionResult &result) {
844   if (result.attrs.test(FunctionResult::Attr::Allocatable) ||
845       result.attrs.test(FunctionResult::Attr::Pointer)) {
846     return false;
847   }
848   const auto *typeAndShape{result.GetTypeAndShape()};
849   if (!typeAndShape || typeAndShape->Rank() != 0) {
850     return false;
851   }
852   auto category{typeAndShape->type().category()};
853   if (category == TypeCategory::Character ||
854       category == TypeCategory::Derived) {
855     return false;
856   }
857   int kind{typeAndShape->type().kind()};
858   return kind == context_.GetDefaultKind(category) ||
859       (category == TypeCategory::Real &&
860           kind == context_.doublePrecisionKind());
861 }
862 
863 void CheckHelper::CheckSubprogram(
864     const Symbol &symbol, const SubprogramDetails &details) {
865   if (const Symbol * iface{FindSeparateModuleSubprogramInterface(&symbol)}) {
866     SubprogramMatchHelper{*this}.Check(symbol, *iface);
867   }
868   if (const Scope * entryScope{details.entryScope()}) {
869     // ENTRY 15.6.2.6, esp. C1571
870     std::optional<parser::MessageFixedText> error;
871     const Symbol *subprogram{entryScope->symbol()};
872     const SubprogramDetails *subprogramDetails{nullptr};
873     if (subprogram) {
874       subprogramDetails = subprogram->detailsIf<SubprogramDetails>();
875     }
876     if (entryScope->kind() != Scope::Kind::Subprogram) {
877       error = "ENTRY may appear only in a subroutine or function"_err_en_US;
878     } else if (!(entryScope->parent().IsGlobal() ||
879                    entryScope->parent().IsModule() ||
880                    entryScope->parent().IsSubmodule())) {
881       error = "ENTRY may not appear in an internal subprogram"_err_en_US;
882     } else if (FindSeparateModuleSubprogramInterface(subprogram)) {
883       error = "ENTRY may not appear in a separate module procedure"_err_en_US;
884     } else if (subprogramDetails && details.isFunction() &&
885         subprogramDetails->isFunction() &&
886         !context_.HasError(details.result()) &&
887         !context_.HasError(subprogramDetails->result())) {
888       auto result{FunctionResult::Characterize(
889           details.result(), context_.foldingContext())};
890       auto subpResult{FunctionResult::Characterize(
891           subprogramDetails->result(), context_.foldingContext())};
892       if (result && subpResult && *result != *subpResult &&
893           (!IsResultOkToDiffer(*result) || !IsResultOkToDiffer(*subpResult))) {
894         error =
895             "Result of ENTRY is not compatible with result of containing function"_err_en_US;
896       }
897     }
898     if (error) {
899       if (auto *msg{messages_.Say(symbol.name(), *error)}) {
900         if (subprogram) {
901           msg->Attach(subprogram->name(), "Containing subprogram"_en_US);
902         }
903       }
904     }
905   }
906   if (symbol.attrs().test(Attr::ELEMENTAL)) {
907     // See comment on the similar check in CheckProcEntity()
908     if (details.isDummy()) {
909       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
910     } else {
911       for (const Symbol *dummy : details.dummyArgs()) {
912         if (!dummy) { // C15100
913           messages_.Say(
914               "An ELEMENTAL subroutine may not have an alternate return dummy argument"_err_en_US);
915         }
916       }
917     }
918   }
919 }
920 
921 void CheckHelper::CheckDerivedType(
922     const Symbol &derivedType, const DerivedTypeDetails &details) {
923   if (details.isForwardReferenced() && !context_.HasError(derivedType)) {
924     messages_.Say("The derived type '%s' has not been defined"_err_en_US,
925         derivedType.name());
926   }
927   const Scope *scope{derivedType.scope()};
928   if (!scope) {
929     CHECK(details.isForwardReferenced());
930     return;
931   }
932   CHECK(scope->symbol() == &derivedType);
933   CHECK(scope->IsDerivedType());
934   if (derivedType.attrs().test(Attr::ABSTRACT) && // C734
935       (derivedType.attrs().test(Attr::BIND_C) || details.sequence())) {
936     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
937   }
938   if (const DeclTypeSpec * parent{FindParentTypeSpec(derivedType)}) {
939     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
940     if (!IsExtensibleType(parentDerived)) { // C705
941       messages_.Say("The parent type is not extensible"_err_en_US);
942     }
943     if (!derivedType.attrs().test(Attr::ABSTRACT) && parentDerived &&
944         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
945       ScopeComponentIterator components{*parentDerived};
946       for (const Symbol &component : components) {
947         if (component.attrs().test(Attr::DEFERRED)) {
948           if (scope->FindComponent(component.name()) == &component) {
949             SayWithDeclaration(component,
950                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
951                 parentDerived->typeSymbol().name(), component.name());
952           }
953         }
954       }
955     }
956     DerivedTypeSpec derived{derivedType.name(), derivedType};
957     derived.set_scope(*scope);
958     if (FindCoarrayUltimateComponent(derived) && // C736
959         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
960       messages_.Say(
961           "Type '%s' has a coarray ultimate component so the type at the base "
962           "of its type extension chain ('%s') must be a type that has a "
963           "coarray ultimate component"_err_en_US,
964           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
965     }
966     if (FindEventOrLockPotentialComponent(derived) && // C737
967         !(FindEventOrLockPotentialComponent(*parentDerived) ||
968             IsEventTypeOrLockType(parentDerived))) {
969       messages_.Say(
970           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
971           "at the base of its type extension chain ('%s') must either have an "
972           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
973           "LOCK_TYPE"_err_en_US,
974           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
975     }
976   }
977   if (HasIntrinsicTypeName(derivedType)) { // C729
978     messages_.Say("A derived type name cannot be the name of an intrinsic"
979                   " type"_err_en_US);
980   }
981   std::map<SourceName, SymbolRef> previous;
982   for (const auto &pair : details.finals()) {
983     SourceName source{pair.first};
984     const Symbol &ref{*pair.second};
985     if (CheckFinal(ref, source, derivedType) &&
986         std::all_of(previous.begin(), previous.end(),
987             [&](std::pair<SourceName, SymbolRef> prev) {
988               return CheckDistinguishableFinals(
989                   ref, source, *prev.second, prev.first, derivedType);
990             })) {
991       previous.emplace(source, ref);
992     }
993   }
994 }
995 
996 // C786
997 bool CheckHelper::CheckFinal(
998     const Symbol &subroutine, SourceName finalName, const Symbol &derivedType) {
999   if (!IsModuleProcedure(subroutine)) {
1000     SayWithDeclaration(subroutine, finalName,
1001         "FINAL subroutine '%s' of derived type '%s' must be a module procedure"_err_en_US,
1002         subroutine.name(), derivedType.name());
1003     return false;
1004   }
1005   const Procedure *proc{Characterize(subroutine)};
1006   if (!proc) {
1007     return false; // error recovery
1008   }
1009   if (!proc->IsSubroutine()) {
1010     SayWithDeclaration(subroutine, finalName,
1011         "FINAL subroutine '%s' of derived type '%s' must be a subroutine"_err_en_US,
1012         subroutine.name(), derivedType.name());
1013     return false;
1014   }
1015   if (proc->dummyArguments.size() != 1) {
1016     SayWithDeclaration(subroutine, finalName,
1017         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument"_err_en_US,
1018         subroutine.name(), derivedType.name());
1019     return false;
1020   }
1021   const auto &arg{proc->dummyArguments[0]};
1022   const Symbol *errSym{&subroutine};
1023   if (const auto *details{subroutine.detailsIf<SubprogramDetails>()}) {
1024     if (!details->dummyArgs().empty()) {
1025       if (const Symbol * argSym{details->dummyArgs()[0]}) {
1026         errSym = argSym;
1027       }
1028     }
1029   }
1030   const auto *ddo{std::get_if<DummyDataObject>(&arg.u)};
1031   if (!ddo) {
1032     SayWithDeclaration(subroutine, finalName,
1033         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument that is a data object"_err_en_US,
1034         subroutine.name(), derivedType.name());
1035     return false;
1036   }
1037   bool ok{true};
1038   if (arg.IsOptional()) {
1039     SayWithDeclaration(*errSym, finalName,
1040         "FINAL subroutine '%s' of derived type '%s' must not have an OPTIONAL dummy argument"_err_en_US,
1041         subroutine.name(), derivedType.name());
1042     ok = false;
1043   }
1044   if (ddo->attrs.test(DummyDataObject::Attr::Allocatable)) {
1045     SayWithDeclaration(*errSym, finalName,
1046         "FINAL subroutine '%s' of derived type '%s' must not have an ALLOCATABLE dummy argument"_err_en_US,
1047         subroutine.name(), derivedType.name());
1048     ok = false;
1049   }
1050   if (ddo->attrs.test(DummyDataObject::Attr::Pointer)) {
1051     SayWithDeclaration(*errSym, finalName,
1052         "FINAL subroutine '%s' of derived type '%s' must not have a POINTER dummy argument"_err_en_US,
1053         subroutine.name(), derivedType.name());
1054     ok = false;
1055   }
1056   if (ddo->intent == common::Intent::Out) {
1057     SayWithDeclaration(*errSym, finalName,
1058         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with INTENT(OUT)"_err_en_US,
1059         subroutine.name(), derivedType.name());
1060     ok = false;
1061   }
1062   if (ddo->attrs.test(DummyDataObject::Attr::Value)) {
1063     SayWithDeclaration(*errSym, finalName,
1064         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with the VALUE attribute"_err_en_US,
1065         subroutine.name(), derivedType.name());
1066     ok = false;
1067   }
1068   if (ddo->type.corank() > 0) {
1069     SayWithDeclaration(*errSym, finalName,
1070         "FINAL subroutine '%s' of derived type '%s' must not have a coarray dummy argument"_err_en_US,
1071         subroutine.name(), derivedType.name());
1072     ok = false;
1073   }
1074   if (ddo->type.type().IsPolymorphic()) {
1075     SayWithDeclaration(*errSym, finalName,
1076         "FINAL subroutine '%s' of derived type '%s' must not have a polymorphic dummy argument"_err_en_US,
1077         subroutine.name(), derivedType.name());
1078     ok = false;
1079   } else if (ddo->type.type().category() != TypeCategory::Derived ||
1080       &ddo->type.type().GetDerivedTypeSpec().typeSymbol() != &derivedType) {
1081     SayWithDeclaration(*errSym, finalName,
1082         "FINAL subroutine '%s' of derived type '%s' must have a TYPE(%s) dummy argument"_err_en_US,
1083         subroutine.name(), derivedType.name(), derivedType.name());
1084     ok = false;
1085   } else { // check that all LEN type parameters are assumed
1086     for (auto ref : OrderParameterDeclarations(derivedType)) {
1087       if (IsLenTypeParameter(*ref)) {
1088         const auto *value{
1089             ddo->type.type().GetDerivedTypeSpec().FindParameter(ref->name())};
1090         if (!value || !value->isAssumed()) {
1091           SayWithDeclaration(*errSym, finalName,
1092               "FINAL subroutine '%s' of derived type '%s' must have a dummy argument with an assumed LEN type parameter '%s=*'"_err_en_US,
1093               subroutine.name(), derivedType.name(), ref->name());
1094           ok = false;
1095         }
1096       }
1097     }
1098   }
1099   return ok;
1100 }
1101 
1102 bool CheckHelper::CheckDistinguishableFinals(const Symbol &f1,
1103     SourceName f1Name, const Symbol &f2, SourceName f2Name,
1104     const Symbol &derivedType) {
1105   const Procedure *p1{Characterize(f1)};
1106   const Procedure *p2{Characterize(f2)};
1107   if (p1 && p2) {
1108     if (characteristics::Distinguishable(
1109             context_.languageFeatures(), *p1, *p2)) {
1110       return true;
1111     }
1112     if (auto *msg{messages_.Say(f1Name,
1113             "FINAL subroutines '%s' and '%s' of derived type '%s' cannot be distinguished by rank or KIND type parameter value"_err_en_US,
1114             f1Name, f2Name, derivedType.name())}) {
1115       msg->Attach(f2Name, "FINAL declaration of '%s'"_en_US, f2.name())
1116           .Attach(f1.name(), "Definition of '%s'"_en_US, f1Name)
1117           .Attach(f2.name(), "Definition of '%s'"_en_US, f2Name);
1118     }
1119   }
1120   return false;
1121 }
1122 
1123 void CheckHelper::CheckHostAssoc(
1124     const Symbol &symbol, const HostAssocDetails &details) {
1125   const Symbol &hostSymbol{details.symbol()};
1126   if (hostSymbol.test(Symbol::Flag::ImplicitOrError)) {
1127     if (details.implicitOrSpecExprError) {
1128       messages_.Say("Implicitly typed local entity '%s' not allowed in"
1129                     " specification expression"_err_en_US,
1130           symbol.name());
1131     } else if (details.implicitOrExplicitTypeError) {
1132       messages_.Say(
1133           "No explicit type declared for '%s'"_err_en_US, symbol.name());
1134     }
1135   }
1136 }
1137 
1138 void CheckHelper::CheckGeneric(
1139     const Symbol &symbol, const GenericDetails &details) {
1140   CheckSpecificsAreDistinguishable(symbol, details);
1141   std::visit(common::visitors{
1142                  [&](const GenericKind::DefinedIo &io) {
1143                    CheckDefinedIoProc(symbol, details, io);
1144                  },
1145                  [](const auto &) {},
1146              },
1147       details.kind().u);
1148 }
1149 
1150 // Check that the specifics of this generic are distinguishable from each other
1151 void CheckHelper::CheckSpecificsAreDistinguishable(
1152     const Symbol &generic, const GenericDetails &details) {
1153   GenericKind kind{details.kind()};
1154   const SymbolVector &specifics{details.specificProcs()};
1155   std::size_t count{specifics.size()};
1156   if (count < 2 || !kind.IsName()) {
1157     return;
1158   }
1159   DistinguishabilityHelper helper{context_};
1160   for (const Symbol &specific : specifics) {
1161     if (const Procedure * procedure{Characterize(specific)}) {
1162       helper.Add(generic, kind, specific, *procedure);
1163     }
1164   }
1165   helper.Check(generic.owner());
1166 }
1167 
1168 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
1169   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1170   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1171   return Tristate::No ==
1172       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
1173 }
1174 
1175 static bool ConflictsWithIntrinsicOperator(
1176     const GenericKind &kind, const Procedure &proc) {
1177   if (!kind.IsIntrinsicOperator()) {
1178     return false;
1179   }
1180   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1181   auto type0{arg0.type()};
1182   if (proc.dummyArguments.size() == 1) { // unary
1183     return std::visit(
1184         common::visitors{
1185             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
1186             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
1187             [](const auto &) -> bool { DIE("bad generic kind"); },
1188         },
1189         kind.u);
1190   } else { // binary
1191     int rank0{arg0.Rank()};
1192     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1193     auto type1{arg1.type()};
1194     int rank1{arg1.Rank()};
1195     return std::visit(
1196         common::visitors{
1197             [&](common::NumericOperator) {
1198               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
1199             },
1200             [&](common::LogicalOperator) {
1201               return IsIntrinsicLogical(type0, rank0, type1, rank1);
1202             },
1203             [&](common::RelationalOperator opr) {
1204               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
1205             },
1206             [&](GenericKind::OtherKind x) {
1207               CHECK(x == GenericKind::OtherKind::Concat);
1208               return IsIntrinsicConcat(type0, rank0, type1, rank1);
1209             },
1210             [](const auto &) -> bool { DIE("bad generic kind"); },
1211         },
1212         kind.u);
1213   }
1214 }
1215 
1216 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
1217 bool CheckHelper::CheckDefinedOperator(SourceName opName, GenericKind kind,
1218     const Symbol &specific, const Procedure &proc) {
1219   if (context_.HasError(specific)) {
1220     return false;
1221   }
1222   std::optional<parser::MessageFixedText> msg;
1223   auto checkDefinedOperatorArgs{
1224       [&](SourceName opName, const Symbol &specific, const Procedure &proc) {
1225         bool arg0Defined{CheckDefinedOperatorArg(opName, specific, proc, 0)};
1226         bool arg1Defined{CheckDefinedOperatorArg(opName, specific, proc, 1)};
1227         return arg0Defined && arg1Defined;
1228       }};
1229   if (specific.attrs().test(Attr::NOPASS)) { // C774
1230     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
1231   } else if (!proc.functionResult.has_value()) {
1232     msg = "%s procedure '%s' must be a function"_err_en_US;
1233   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
1234     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
1235           " result"_err_en_US;
1236   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
1237     msg = std::move(m);
1238   } else if (!checkDefinedOperatorArgs(opName, specific, proc)) {
1239     return false; // error was reported
1240   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
1241     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
1242   } else {
1243     return true; // OK
1244   }
1245   SayWithDeclaration(
1246       specific, std::move(*msg), MakeOpName(opName), specific.name());
1247   context_.SetError(specific);
1248   return false;
1249 }
1250 
1251 // If the number of arguments is wrong for this intrinsic operator, return
1252 // false and return the error message in msg.
1253 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
1254     const GenericKind &kind, std::size_t nargs) {
1255   if (!kind.IsIntrinsicOperator()) {
1256     return std::nullopt;
1257   }
1258   std::size_t min{2}, max{2}; // allowed number of args; default is binary
1259   std::visit(common::visitors{
1260                  [&](const common::NumericOperator &x) {
1261                    if (x == common::NumericOperator::Add ||
1262                        x == common::NumericOperator::Subtract) {
1263                      min = 1; // + and - are unary or binary
1264                    }
1265                  },
1266                  [&](const common::LogicalOperator &x) {
1267                    if (x == common::LogicalOperator::Not) {
1268                      min = 1; // .NOT. is unary
1269                      max = 1;
1270                    }
1271                  },
1272                  [](const common::RelationalOperator &) {
1273                    // all are binary
1274                  },
1275                  [](const GenericKind::OtherKind &x) {
1276                    CHECK(x == GenericKind::OtherKind::Concat);
1277                  },
1278                  [](const auto &) { DIE("expected intrinsic operator"); },
1279              },
1280       kind.u);
1281   if (nargs >= min && nargs <= max) {
1282     return std::nullopt;
1283   } else if (max == 1) {
1284     return "%s function '%s' must have one dummy argument"_err_en_US;
1285   } else if (min == 2) {
1286     return "%s function '%s' must have two dummy arguments"_err_en_US;
1287   } else {
1288     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
1289   }
1290 }
1291 
1292 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
1293     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
1294   if (pos >= proc.dummyArguments.size()) {
1295     return true;
1296   }
1297   auto &arg{proc.dummyArguments.at(pos)};
1298   std::optional<parser::MessageFixedText> msg;
1299   if (arg.IsOptional()) {
1300     msg = "In %s function '%s', dummy argument '%s' may not be"
1301           " OPTIONAL"_err_en_US;
1302   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
1303              dataObject == nullptr) {
1304     msg = "In %s function '%s', dummy argument '%s' must be a"
1305           " data object"_err_en_US;
1306   } else if (dataObject->intent != common::Intent::In &&
1307       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1308     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
1309           " or VALUE attribute"_err_en_US;
1310   }
1311   if (msg) {
1312     SayWithDeclaration(symbol, std::move(*msg),
1313         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
1314     return false;
1315   }
1316   return true;
1317 }
1318 
1319 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
1320 bool CheckHelper::CheckDefinedAssignment(
1321     const Symbol &specific, const Procedure &proc) {
1322   if (context_.HasError(specific)) {
1323     return false;
1324   }
1325   std::optional<parser::MessageFixedText> msg;
1326   if (specific.attrs().test(Attr::NOPASS)) { // C774
1327     msg = "Defined assignment procedure '%s' may not have"
1328           " NOPASS attribute"_err_en_US;
1329   } else if (!proc.IsSubroutine()) {
1330     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
1331   } else if (proc.dummyArguments.size() != 2) {
1332     msg = "Defined assignment subroutine '%s' must have"
1333           " two dummy arguments"_err_en_US;
1334   } else {
1335     // Check both arguments even if the first has an error.
1336     bool ok0{CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0)};
1337     bool ok1{CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)};
1338     if (!(ok0 && ok1)) {
1339       return false; // error was reported
1340     } else if (ConflictsWithIntrinsicAssignment(proc)) {
1341       msg = "Defined assignment subroutine '%s' conflicts with"
1342             " intrinsic assignment"_err_en_US;
1343     } else {
1344       return true; // OK
1345     }
1346   }
1347   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
1348   context_.SetError(specific);
1349   return false;
1350 }
1351 
1352 bool CheckHelper::CheckDefinedAssignmentArg(
1353     const Symbol &symbol, const DummyArgument &arg, int pos) {
1354   std::optional<parser::MessageFixedText> msg;
1355   if (arg.IsOptional()) {
1356     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1357           " may not be OPTIONAL"_err_en_US;
1358   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
1359     if (pos == 0) {
1360       if (dataObject->intent != common::Intent::Out &&
1361           dataObject->intent != common::Intent::InOut) {
1362         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
1363               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
1364       }
1365     } else if (pos == 1) {
1366       if (dataObject->intent != common::Intent::In &&
1367           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1368         msg =
1369             "In defined assignment subroutine '%s', second dummy"
1370             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1371       }
1372     } else {
1373       DIE("pos must be 0 or 1");
1374     }
1375   } else {
1376     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1377           " must be a data object"_err_en_US;
1378   }
1379   if (msg) {
1380     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1381     context_.SetError(symbol);
1382     return false;
1383   }
1384   return true;
1385 }
1386 
1387 // Report a conflicting attribute error if symbol has both of these attributes
1388 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1389   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1390     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1391         symbol.name(), AttrToString(a1), AttrToString(a2));
1392     return true;
1393   } else {
1394     return false;
1395   }
1396 }
1397 
1398 void CheckHelper::WarnMissingFinal(const Symbol &symbol) {
1399   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
1400   if (!object || IsPointer(symbol)) {
1401     return;
1402   }
1403   const DeclTypeSpec *type{object->type()};
1404   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
1405   const Symbol *derivedSym{derived ? &derived->typeSymbol() : nullptr};
1406   int rank{object->shape().Rank()};
1407   const Symbol *initialDerivedSym{derivedSym};
1408   while (const auto *derivedDetails{
1409       derivedSym ? derivedSym->detailsIf<DerivedTypeDetails>() : nullptr}) {
1410     if (!derivedDetails->finals().empty() &&
1411         !derivedDetails->GetFinalForRank(rank)) {
1412       if (auto *msg{derivedSym == initialDerivedSym
1413                   ? messages_.Say(symbol.name(),
1414                         "'%s' of derived type '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1415                         symbol.name(), derivedSym->name(), rank)
1416                   : messages_.Say(symbol.name(),
1417                         "'%s' of derived type '%s' extended from '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1418                         symbol.name(), initialDerivedSym->name(),
1419                         derivedSym->name(), rank)}) {
1420         msg->Attach(derivedSym->name(),
1421             "Declaration of derived type '%s'"_en_US, derivedSym->name());
1422       }
1423       return;
1424     }
1425     derived = derivedSym->GetParentTypeSpec();
1426     derivedSym = derived ? &derived->typeSymbol() : nullptr;
1427   }
1428 }
1429 
1430 const Procedure *CheckHelper::Characterize(const Symbol &symbol) {
1431   auto it{characterizeCache_.find(symbol)};
1432   if (it == characterizeCache_.end()) {
1433     auto pair{characterizeCache_.emplace(SymbolRef{symbol},
1434         Procedure::Characterize(symbol, context_.foldingContext()))};
1435     it = pair.first;
1436   }
1437   return common::GetPtrFromOptional(it->second);
1438 }
1439 
1440 void CheckHelper::CheckVolatile(const Symbol &symbol,
1441     const DerivedTypeSpec *derived) { // C866 - C868
1442   if (IsIntentIn(symbol)) {
1443     messages_.Say(
1444         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1445   }
1446   if (IsProcedure(symbol)) {
1447     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1448   }
1449   if (symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()) {
1450     const Symbol &ultimate{symbol.GetUltimate()};
1451     if (IsCoarray(ultimate)) {
1452       messages_.Say(
1453           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1454     }
1455     if (derived) {
1456       if (FindCoarrayUltimateComponent(*derived)) {
1457         messages_.Say(
1458             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1459       }
1460     }
1461   }
1462 }
1463 
1464 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1465   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1466   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1467   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1468   // Prohibit constant pointers.  The standard does not explicitly prohibit
1469   // them, but the PARAMETER attribute requires a entity-decl to have an
1470   // initialization that is a constant-expr, and the only form of
1471   // initialization that allows a constant-expr is the one that's not a "=>"
1472   // pointer initialization.  See C811, C807, and section 8.5.13.
1473   CheckConflicting(symbol, Attr::POINTER, Attr::PARAMETER);
1474   if (symbol.Corank() > 0) {
1475     messages_.Say(
1476         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1477         symbol.name());
1478   }
1479 }
1480 
1481 // C760 constraints on the passed-object dummy argument
1482 // C757 constraints on procedure pointer components
1483 void CheckHelper::CheckPassArg(
1484     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1485   if (proc.attrs().test(Attr::NOPASS)) {
1486     return;
1487   }
1488   const auto &name{proc.name()};
1489   if (!interface) {
1490     messages_.Say(name,
1491         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1492         name);
1493     return;
1494   }
1495   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1496   if (!subprogram) {
1497     messages_.Say(name,
1498         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1499         interface->name());
1500     return;
1501   }
1502   std::optional<SourceName> passName{details.passName()};
1503   const auto &dummyArgs{subprogram->dummyArgs()};
1504   if (!passName) {
1505     if (dummyArgs.empty()) {
1506       messages_.Say(name,
1507           proc.has<ProcEntityDetails>()
1508               ? "Procedure component '%s' with no dummy arguments"
1509                 " must have NOPASS attribute"_err_en_US
1510               : "Procedure binding '%s' with no dummy arguments"
1511                 " must have NOPASS attribute"_err_en_US,
1512           name);
1513       context_.SetError(*interface);
1514       return;
1515     }
1516     Symbol *argSym{dummyArgs[0]};
1517     if (!argSym) {
1518       messages_.Say(interface->name(),
1519           "Cannot use an alternate return as the passed-object dummy "
1520           "argument"_err_en_US);
1521       return;
1522     }
1523     passName = dummyArgs[0]->name();
1524   }
1525   std::optional<int> passArgIndex{};
1526   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1527     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1528       passArgIndex = i;
1529       break;
1530     }
1531   }
1532   if (!passArgIndex) { // C758
1533     messages_.Say(*passName,
1534         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1535         *passName, interface->name());
1536     return;
1537   }
1538   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1539   std::optional<parser::MessageFixedText> msg;
1540   if (!passArg.has<ObjectEntityDetails>()) {
1541     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1542           " must be a data object"_err_en_US;
1543   } else if (passArg.attrs().test(Attr::POINTER)) {
1544     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1545           " may not have the POINTER attribute"_err_en_US;
1546   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1547     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1548           " may not have the ALLOCATABLE attribute"_err_en_US;
1549   } else if (passArg.attrs().test(Attr::VALUE)) {
1550     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1551           " may not have the VALUE attribute"_err_en_US;
1552   } else if (passArg.Rank() > 0) {
1553     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1554           " must be scalar"_err_en_US;
1555   }
1556   if (msg) {
1557     messages_.Say(name, std::move(*msg), passName.value(), name);
1558     return;
1559   }
1560   const DeclTypeSpec *type{passArg.GetType()};
1561   if (!type) {
1562     return; // an error already occurred
1563   }
1564   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1565   const DerivedTypeSpec *derived{type->AsDerived()};
1566   if (!derived || derived->typeSymbol() != typeSymbol) {
1567     messages_.Say(name,
1568         "Passed-object dummy argument '%s' of procedure '%s'"
1569         " must be of type '%s' but is '%s'"_err_en_US,
1570         passName.value(), name, typeSymbol.name(), type->AsFortran());
1571     return;
1572   }
1573   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1574     messages_.Say(name,
1575         type->IsPolymorphic()
1576             ? "Passed-object dummy argument '%s' of procedure '%s'"
1577               " may not be polymorphic because '%s' is not extensible"_err_en_US
1578             : "Passed-object dummy argument '%s' of procedure '%s'"
1579               " must be polymorphic because '%s' is extensible"_err_en_US,
1580         passName.value(), name, typeSymbol.name());
1581     return;
1582   }
1583   for (const auto &[paramName, paramValue] : derived->parameters()) {
1584     if (paramValue.isLen() && !paramValue.isAssumed()) {
1585       messages_.Say(name,
1586           "Passed-object dummy argument '%s' of procedure '%s'"
1587           " has non-assumed length parameter '%s'"_err_en_US,
1588           passName.value(), name, paramName);
1589     }
1590   }
1591 }
1592 
1593 void CheckHelper::CheckProcBinding(
1594     const Symbol &symbol, const ProcBindingDetails &binding) {
1595   const Scope &dtScope{symbol.owner()};
1596   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1597   if (symbol.attrs().test(Attr::DEFERRED)) {
1598     if (const Symbol * dtSymbol{dtScope.symbol()}) {
1599       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1600         SayWithDeclaration(*dtSymbol,
1601             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1602             dtSymbol->name());
1603       }
1604     }
1605     if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1606       messages_.Say(
1607           "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1608           symbol.name());
1609     }
1610   }
1611   if (binding.symbol().attrs().test(Attr::INTRINSIC) &&
1612       !context_.intrinsics().IsSpecificIntrinsicFunction(
1613           binding.symbol().name().ToString())) {
1614     messages_.Say(
1615         "Intrinsic procedure '%s' is not a specific intrinsic permitted for use in the definition of binding '%s'"_err_en_US,
1616         binding.symbol().name(), symbol.name());
1617   }
1618   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1619     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1620       SayWithDeclaration(*overridden,
1621           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1622           symbol.name());
1623     }
1624     if (const auto *overriddenBinding{
1625             overridden->detailsIf<ProcBindingDetails>()}) {
1626       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1627         SayWithDeclaration(*overridden,
1628             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1629         return;
1630       }
1631       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1632           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1633         SayWithDeclaration(*overridden,
1634             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1635         return;
1636       }
1637       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1638       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1639         SayWithDeclaration(*overridden,
1640             isNopass
1641                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1642                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1643       } else {
1644         const auto *bindingChars{Characterize(binding.symbol())};
1645         const auto *overriddenChars{Characterize(overriddenBinding->symbol())};
1646         if (bindingChars && overriddenChars) {
1647           if (isNopass) {
1648             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1649               SayWithDeclaration(*overridden,
1650                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1651             }
1652           } else if (!context_.HasError(binding.symbol())) {
1653             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1654             int overriddenPassIndex{
1655                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1656             if (passIndex != overriddenPassIndex) {
1657               SayWithDeclaration(*overridden,
1658                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1659             } else if (!bindingChars->CanOverride(
1660                            *overriddenChars, passIndex)) {
1661               SayWithDeclaration(*overridden,
1662                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1663             }
1664           }
1665         }
1666       }
1667       if (symbol.attrs().test(Attr::PRIVATE) &&
1668           overridden->attrs().test(Attr::PUBLIC)) {
1669         SayWithDeclaration(*overridden,
1670             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1671       }
1672     } else {
1673       SayWithDeclaration(*overridden,
1674           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1675     }
1676   }
1677   CheckPassArg(symbol, &binding.symbol(), binding);
1678 }
1679 
1680 void CheckHelper::Check(const Scope &scope) {
1681   scope_ = &scope;
1682   common::Restorer<const Symbol *> restorer{innermostSymbol_, innermostSymbol_};
1683   if (const Symbol * symbol{scope.symbol()}) {
1684     innermostSymbol_ = symbol;
1685   }
1686   if (scope.IsParameterizedDerivedTypeInstantiation()) {
1687     auto restorer{common::ScopedSet(scopeIsUninstantiatedPDT_, false)};
1688     auto restorer2{context_.foldingContext().messages().SetContext(
1689         scope.instantiationContext().get())};
1690     for (const auto &pair : scope) {
1691       CheckPointerInitialization(*pair.second);
1692     }
1693   } else {
1694     auto restorer{common::ScopedSet(
1695         scopeIsUninstantiatedPDT_, scope.IsParameterizedDerivedType())};
1696     for (const auto &set : scope.equivalenceSets()) {
1697       CheckEquivalenceSet(set);
1698     }
1699     for (const auto &pair : scope) {
1700       Check(*pair.second);
1701     }
1702     for (const Scope &child : scope.children()) {
1703       Check(child);
1704     }
1705     if (scope.kind() == Scope::Kind::BlockData) {
1706       CheckBlockData(scope);
1707     }
1708     CheckGenericOps(scope);
1709   }
1710 }
1711 
1712 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1713   auto iter{
1714       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1715         return FindCommonBlockContaining(object.symbol) != nullptr;
1716       })};
1717   if (iter != set.end()) {
1718     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1719     for (auto &object : set) {
1720       if (&object != &*iter) {
1721         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1722           if (details->commonBlock()) {
1723             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1724               if (auto *msg{messages_.Say(object.symbol.name(),
1725                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1726                 msg->Attach(iter->symbol.name(),
1727                        "Other object in EQUIVALENCE set"_en_US)
1728                     .Attach(details->commonBlock()->name(),
1729                         "COMMON block containing '%s'"_en_US,
1730                         object.symbol.name())
1731                     .Attach(commonBlock.name(),
1732                         "COMMON block containing '%s'"_en_US,
1733                         iter->symbol.name());
1734               }
1735             }
1736           } else {
1737             // Mark all symbols in the equivalence set with the same COMMON
1738             // block to prevent spurious error messages about initialization
1739             // in BLOCK DATA outside COMMON
1740             details->set_commonBlock(commonBlock);
1741           }
1742         }
1743       }
1744     }
1745   }
1746   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1747 }
1748 
1749 void CheckHelper::CheckBlockData(const Scope &scope) {
1750   // BLOCK DATA subprograms should contain only named common blocks.
1751   // C1415 presents a list of statements that shouldn't appear in
1752   // BLOCK DATA, but so long as the subprogram contains no executable
1753   // code and allocates no storage outside named COMMON, we're happy
1754   // (e.g., an ENUM is strictly not allowed).
1755   for (const auto &pair : scope) {
1756     const Symbol &symbol{*pair.second};
1757     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1758             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1759             symbol.has<SubprogramDetails>() ||
1760             symbol.has<ObjectEntityDetails>() ||
1761             (symbol.has<ProcEntityDetails>() &&
1762                 !symbol.attrs().test(Attr::POINTER)))) {
1763       messages_.Say(symbol.name(),
1764           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1765           symbol.name());
1766     }
1767   }
1768 }
1769 
1770 // Check distinguishability of generic assignment and operators.
1771 // For these, generics and generic bindings must be considered together.
1772 void CheckHelper::CheckGenericOps(const Scope &scope) {
1773   DistinguishabilityHelper helper{context_};
1774   auto addSpecifics{[&](const Symbol &generic) {
1775     const auto *details{generic.GetUltimate().detailsIf<GenericDetails>()};
1776     if (!details) {
1777       return;
1778     }
1779     GenericKind kind{details->kind()};
1780     if (!kind.IsAssignment() && !kind.IsOperator()) {
1781       return;
1782     }
1783     const SymbolVector &specifics{details->specificProcs()};
1784     const std::vector<SourceName> &bindingNames{details->bindingNames()};
1785     for (std::size_t i{0}; i < specifics.size(); ++i) {
1786       const Symbol &specific{*specifics[i]};
1787       if (const Procedure * proc{Characterize(specific)}) {
1788         auto restorer{messages_.SetLocation(bindingNames[i])};
1789         if (kind.IsAssignment()) {
1790           if (!CheckDefinedAssignment(specific, *proc)) {
1791             continue;
1792           }
1793         } else {
1794           if (!CheckDefinedOperator(generic.name(), kind, specific, *proc)) {
1795             continue;
1796           }
1797         }
1798         helper.Add(generic, kind, specific, *proc);
1799       }
1800     }
1801   }};
1802   for (const auto &pair : scope) {
1803     const Symbol &symbol{*pair.second};
1804     addSpecifics(symbol);
1805     const Symbol &ultimate{symbol.GetUltimate()};
1806     if (ultimate.has<DerivedTypeDetails>()) {
1807       if (const Scope * typeScope{ultimate.scope()}) {
1808         for (const auto &pair2 : *typeScope) {
1809           addSpecifics(*pair2.second);
1810         }
1811       }
1812     }
1813   }
1814   helper.Check(scope);
1815 }
1816 
1817 static const std::string *DefinesBindCName(const Symbol &symbol) {
1818   const auto *subp{symbol.detailsIf<SubprogramDetails>()};
1819   if ((subp && !subp->isInterface()) || symbol.has<ObjectEntityDetails>()) {
1820     // Symbol defines data or entry point
1821     return symbol.GetBindName();
1822   } else {
1823     return nullptr;
1824   }
1825 }
1826 
1827 // Check that BIND(C) names are distinct
1828 void CheckHelper::CheckBindCName(const Symbol &symbol) {
1829   if (const std::string * name{DefinesBindCName(symbol)}) {
1830     auto pair{bindC_.emplace(*name, symbol)};
1831     if (!pair.second) {
1832       const Symbol &other{*pair.first->second};
1833       if (DefinesBindCName(other) && !context_.HasError(other)) {
1834         if (auto *msg{messages_.Say(
1835                 "Two symbols have the same BIND(C) name '%s'"_err_en_US,
1836                 *name)}) {
1837           msg->Attach(other.name(), "Conflicting symbol"_en_US);
1838         }
1839         context_.SetError(symbol);
1840         context_.SetError(other);
1841       }
1842     }
1843   }
1844 }
1845 
1846 bool CheckHelper::CheckDioDummyIsData(
1847     const Symbol &subp, const Symbol *arg, std::size_t position) {
1848   if (arg && arg->detailsIf<ObjectEntityDetails>()) {
1849     return true;
1850   } else {
1851     if (arg) {
1852       messages_.Say(arg->name(),
1853           "Dummy argument '%s' must be a data object"_err_en_US, arg->name());
1854     } else {
1855       messages_.Say(subp.name(),
1856           "Dummy argument %d of '%s' must be a data object"_err_en_US, position,
1857           subp.name());
1858     }
1859     return false;
1860   }
1861 }
1862 
1863 void CheckHelper::CheckAlreadySeenDefinedIo(const DerivedTypeSpec *derivedType,
1864     GenericKind::DefinedIo ioKind, const Symbol &proc) {
1865   for (TypeWithDefinedIo definedIoType : seenDefinedIoTypes_) {
1866     if (*derivedType == *definedIoType.type && ioKind == definedIoType.ioKind &&
1867         proc != definedIoType.proc) {
1868       SayWithDeclaration(proc, definedIoType.proc.name(),
1869           "Derived type '%s' already has defined input/output procedure"
1870           " '%s'"_err_en_US,
1871           derivedType->name(),
1872           parser::ToUpperCaseLetters(GenericKind::EnumToString(ioKind)));
1873       return;
1874     }
1875   }
1876   seenDefinedIoTypes_.emplace_back(
1877       TypeWithDefinedIo{derivedType, ioKind, proc});
1878 }
1879 
1880 void CheckHelper::CheckDioDummyIsDerived(
1881     const Symbol &subp, const Symbol &arg, GenericKind::DefinedIo ioKind) {
1882   if (const DeclTypeSpec * type{arg.GetType()}) {
1883     if (const DerivedTypeSpec * derivedType{type->AsDerived()}) {
1884       CheckAlreadySeenDefinedIo(derivedType, ioKind, subp);
1885       bool isPolymorphic{type->IsPolymorphic()};
1886       if (isPolymorphic != IsExtensibleType(derivedType)) {
1887         messages_.Say(arg.name(),
1888             "Dummy argument '%s' of a defined input/output procedure must be %s when the derived type is %s"_err_en_US,
1889             arg.name(), isPolymorphic ? "TYPE()" : "CLASS()",
1890             isPolymorphic ? "not extensible" : "extensible");
1891       }
1892     } else {
1893       messages_.Say(arg.name(),
1894           "Dummy argument '%s' of a defined input/output procedure must have a"
1895           " derived type"_err_en_US,
1896           arg.name());
1897     }
1898   }
1899 }
1900 
1901 void CheckHelper::CheckDioDummyIsDefaultInteger(
1902     const Symbol &subp, const Symbol &arg) {
1903   if (const DeclTypeSpec * type{arg.GetType()};
1904       type && type->IsNumeric(TypeCategory::Integer)) {
1905     if (const auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
1906         kind && *kind == context_.GetDefaultKind(TypeCategory::Integer)) {
1907       return;
1908     }
1909   }
1910   messages_.Say(arg.name(),
1911       "Dummy argument '%s' of a defined input/output procedure"
1912       " must be an INTEGER of default KIND"_err_en_US,
1913       arg.name());
1914 }
1915 
1916 void CheckHelper::CheckDioDummyIsScalar(const Symbol &subp, const Symbol &arg) {
1917   if (arg.Rank() > 0 || arg.Corank() > 0) {
1918     messages_.Say(arg.name(),
1919         "Dummy argument '%s' of a defined input/output procedure"
1920         " must be a scalar"_err_en_US,
1921         arg.name());
1922   }
1923 }
1924 
1925 void CheckHelper::CheckDioDtvArg(
1926     const Symbol &subp, const Symbol *arg, GenericKind::DefinedIo ioKind) {
1927   // Dtv argument looks like: dtv-type-spec, INTENT(INOUT) :: dtv
1928   if (CheckDioDummyIsData(subp, arg, 0)) {
1929     CheckDioDummyIsDerived(subp, *arg, ioKind);
1930     CheckDioDummyAttrs(subp, *arg,
1931         ioKind == GenericKind::DefinedIo::ReadFormatted ||
1932                 ioKind == GenericKind::DefinedIo::ReadUnformatted
1933             ? Attr::INTENT_INOUT
1934             : Attr::INTENT_IN);
1935   }
1936 }
1937 
1938 void CheckHelper::CheckDefaultIntegerArg(
1939     const Symbol &subp, const Symbol *arg, Attr intent) {
1940   // Argument looks like: INTEGER, INTENT(intent) :: arg
1941   if (CheckDioDummyIsData(subp, arg, 1)) {
1942     CheckDioDummyIsDefaultInteger(subp, *arg);
1943     CheckDioDummyIsScalar(subp, *arg);
1944     CheckDioDummyAttrs(subp, *arg, intent);
1945   }
1946 }
1947 
1948 void CheckHelper::CheckDioAssumedLenCharacterArg(const Symbol &subp,
1949     const Symbol *arg, std::size_t argPosition, Attr intent) {
1950   // Argument looks like: CHARACTER (LEN=*), INTENT(intent) :: (iotype OR iomsg)
1951   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1952     CheckDioDummyAttrs(subp, *arg, intent);
1953     if (!IsAssumedLengthCharacter(*arg)) {
1954       messages_.Say(arg->name(),
1955           "Dummy argument '%s' of a defined input/output procedure"
1956           " must be assumed-length CHARACTER"_err_en_US,
1957           arg->name());
1958     }
1959   }
1960 }
1961 
1962 void CheckHelper::CheckDioVlistArg(
1963     const Symbol &subp, const Symbol *arg, std::size_t argPosition) {
1964   // Vlist argument looks like: INTEGER, INTENT(IN) :: v_list(:)
1965   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1966     CheckDioDummyIsDefaultInteger(subp, *arg);
1967     CheckDioDummyAttrs(subp, *arg, Attr::INTENT_IN);
1968     if (const auto *objectDetails{arg->detailsIf<ObjectEntityDetails>()}) {
1969       if (objectDetails->shape().IsDeferredShape()) {
1970         return;
1971       }
1972     }
1973     messages_.Say(arg->name(),
1974         "Dummy argument '%s' of a defined input/output procedure must be"
1975         " deferred shape"_err_en_US,
1976         arg->name());
1977   }
1978 }
1979 
1980 void CheckHelper::CheckDioArgCount(
1981     const Symbol &subp, GenericKind::DefinedIo ioKind, std::size_t argCount) {
1982   const std::size_t requiredArgCount{
1983       (std::size_t)(ioKind == GenericKind::DefinedIo::ReadFormatted ||
1984                   ioKind == GenericKind::DefinedIo::WriteFormatted
1985               ? 6
1986               : 4)};
1987   if (argCount != requiredArgCount) {
1988     SayWithDeclaration(subp,
1989         "Defined input/output procedure '%s' must have"
1990         " %d dummy arguments rather than %d"_err_en_US,
1991         subp.name(), requiredArgCount, argCount);
1992     context_.SetError(subp);
1993   }
1994 }
1995 
1996 void CheckHelper::CheckDioDummyAttrs(
1997     const Symbol &subp, const Symbol &arg, Attr goodIntent) {
1998   // Defined I/O procedures can't have attributes other than INTENT
1999   Attrs attrs{arg.attrs()};
2000   if (!attrs.test(goodIntent)) {
2001     messages_.Say(arg.name(),
2002         "Dummy argument '%s' of a defined input/output procedure"
2003         " must have intent '%s'"_err_en_US,
2004         arg.name(), AttrToString(goodIntent));
2005   }
2006   attrs = attrs - Attr::INTENT_IN - Attr::INTENT_OUT - Attr::INTENT_INOUT;
2007   if (!attrs.empty()) {
2008     messages_.Say(arg.name(),
2009         "Dummy argument '%s' of a defined input/output procedure may not have"
2010         " any attributes"_err_en_US,
2011         arg.name());
2012   }
2013 }
2014 
2015 // Enforce semantics for defined input/output procedures (12.6.4.8.2) and C777
2016 void CheckHelper::CheckDefinedIoProc(const Symbol &symbol,
2017     const GenericDetails &details, GenericKind::DefinedIo ioKind) {
2018   for (auto ref : details.specificProcs()) {
2019     const auto *binding{ref->detailsIf<ProcBindingDetails>()};
2020     const Symbol &specific{*(binding ? &binding->symbol() : &*ref)};
2021     if (ref->attrs().test(Attr::NOPASS)) { // C774
2022       messages_.Say("Defined input/output procedure '%s' may not have NOPASS "
2023                     "attribute"_err_en_US,
2024           ref->name());
2025       context_.SetError(*ref);
2026     }
2027     if (const auto *subpDetails{specific.detailsIf<SubprogramDetails>()}) {
2028       const std::vector<Symbol *> &dummyArgs{subpDetails->dummyArgs()};
2029       CheckDioArgCount(specific, ioKind, dummyArgs.size());
2030       int argCount{0};
2031       for (auto *arg : dummyArgs) {
2032         switch (argCount++) {
2033         case 0:
2034           // dtv-type-spec, INTENT(INOUT) :: dtv
2035           CheckDioDtvArg(specific, arg, ioKind);
2036           break;
2037         case 1:
2038           // INTEGER, INTENT(IN) :: unit
2039           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_IN);
2040           break;
2041         case 2:
2042           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2043               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2044             // CHARACTER (LEN=*), INTENT(IN) :: iotype
2045             CheckDioAssumedLenCharacterArg(
2046                 specific, arg, argCount, Attr::INTENT_IN);
2047           } else {
2048             // INTEGER, INTENT(OUT) :: iostat
2049             CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2050           }
2051           break;
2052         case 3:
2053           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2054               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2055             // INTEGER, INTENT(IN) :: v_list(:)
2056             CheckDioVlistArg(specific, arg, argCount);
2057           } else {
2058             // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2059             CheckDioAssumedLenCharacterArg(
2060                 specific, arg, argCount, Attr::INTENT_INOUT);
2061           }
2062           break;
2063         case 4:
2064           // INTEGER, INTENT(OUT) :: iostat
2065           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2066           break;
2067         case 5:
2068           // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2069           CheckDioAssumedLenCharacterArg(
2070               specific, arg, argCount, Attr::INTENT_INOUT);
2071           break;
2072         default:;
2073         }
2074       }
2075     }
2076   }
2077 }
2078 
2079 void SubprogramMatchHelper::Check(
2080     const Symbol &symbol1, const Symbol &symbol2) {
2081   const auto details1{symbol1.get<SubprogramDetails>()};
2082   const auto details2{symbol2.get<SubprogramDetails>()};
2083   if (details1.isFunction() != details2.isFunction()) {
2084     Say(symbol1, symbol2,
2085         details1.isFunction()
2086             ? "Module function '%s' was declared as a subroutine in the"
2087               " corresponding interface body"_err_en_US
2088             : "Module subroutine '%s' was declared as a function in the"
2089               " corresponding interface body"_err_en_US);
2090     return;
2091   }
2092   const auto &args1{details1.dummyArgs()};
2093   const auto &args2{details2.dummyArgs()};
2094   int nargs1{static_cast<int>(args1.size())};
2095   int nargs2{static_cast<int>(args2.size())};
2096   if (nargs1 != nargs2) {
2097     Say(symbol1, symbol2,
2098         "Module subprogram '%s' has %d args but the corresponding interface"
2099         " body has %d"_err_en_US,
2100         nargs1, nargs2);
2101     return;
2102   }
2103   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
2104   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
2105     Say(symbol1, symbol2,
2106         nonRecursive1
2107             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
2108               " the corresponding interface body does not"_err_en_US
2109             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
2110               "the corresponding interface body does"_err_en_US);
2111   }
2112   const std::string *bindName1{details1.bindName()};
2113   const std::string *bindName2{details2.bindName()};
2114   if (!bindName1 && !bindName2) {
2115     // OK - neither has a binding label
2116   } else if (!bindName1) {
2117     Say(symbol1, symbol2,
2118         "Module subprogram '%s' does not have a binding label but the"
2119         " corresponding interface body does"_err_en_US);
2120   } else if (!bindName2) {
2121     Say(symbol1, symbol2,
2122         "Module subprogram '%s' has a binding label but the"
2123         " corresponding interface body does not"_err_en_US);
2124   } else if (*bindName1 != *bindName2) {
2125     Say(symbol1, symbol2,
2126         "Module subprogram '%s' has binding label '%s' but the corresponding"
2127         " interface body has '%s'"_err_en_US,
2128         *details1.bindName(), *details2.bindName());
2129   }
2130   const Procedure *proc1{checkHelper.Characterize(symbol1)};
2131   const Procedure *proc2{checkHelper.Characterize(symbol2)};
2132   if (!proc1 || !proc2) {
2133     return;
2134   }
2135   if (proc1->functionResult && proc2->functionResult &&
2136       *proc1->functionResult != *proc2->functionResult) {
2137     Say(symbol1, symbol2,
2138         "Return type of function '%s' does not match return type of"
2139         " the corresponding interface body"_err_en_US);
2140   }
2141   for (int i{0}; i < nargs1; ++i) {
2142     const Symbol *arg1{args1[i]};
2143     const Symbol *arg2{args2[i]};
2144     if (arg1 && !arg2) {
2145       Say(symbol1, symbol2,
2146           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
2147           " but the corresponding argument in the interface body is"_err_en_US,
2148           i + 1);
2149     } else if (!arg1 && arg2) {
2150       Say(symbol1, symbol2,
2151           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
2152           " the corresponding argument in the interface body is not"_err_en_US,
2153           i + 1);
2154     } else if (arg1 && arg2) {
2155       SourceName name1{arg1->name()};
2156       SourceName name2{arg2->name()};
2157       if (name1 != name2) {
2158         Say(*arg1, *arg2,
2159             "Dummy argument name '%s' does not match corresponding name '%s'"
2160             " in interface body"_err_en_US,
2161             name2);
2162       } else {
2163         CheckDummyArg(
2164             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
2165       }
2166     }
2167   }
2168 }
2169 
2170 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
2171     const Symbol &symbol2, const DummyArgument &arg1,
2172     const DummyArgument &arg2) {
2173   std::visit(common::visitors{
2174                  [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
2175                    CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
2176                  },
2177                  [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
2178                    CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
2179                  },
2180                  [&](const DummyDataObject &, const auto &) {
2181                    Say(symbol1, symbol2,
2182                        "Dummy argument '%s' is a data object; the corresponding"
2183                        " argument in the interface body is not"_err_en_US);
2184                  },
2185                  [&](const DummyProcedure &, const auto &) {
2186                    Say(symbol1, symbol2,
2187                        "Dummy argument '%s' is a procedure; the corresponding"
2188                        " argument in the interface body is not"_err_en_US);
2189                  },
2190                  [&](const auto &, const auto &) {
2191                    llvm_unreachable("Dummy arguments are not data objects or"
2192                                     "procedures");
2193                  },
2194              },
2195       arg1.u, arg2.u);
2196 }
2197 
2198 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
2199     const Symbol &symbol2, const DummyDataObject &obj1,
2200     const DummyDataObject &obj2) {
2201   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
2202   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
2203   } else if (obj1.type.type() != obj2.type.type()) {
2204     Say(symbol1, symbol2,
2205         "Dummy argument '%s' has type %s; the corresponding argument in the"
2206         " interface body has type %s"_err_en_US,
2207         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
2208   } else if (!ShapesAreCompatible(obj1, obj2)) {
2209     Say(symbol1, symbol2,
2210         "The shape of dummy argument '%s' does not match the shape of the"
2211         " corresponding argument in the interface body"_err_en_US);
2212   }
2213   // TODO: coshape
2214 }
2215 
2216 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
2217     const Symbol &symbol2, const DummyProcedure &proc1,
2218     const DummyProcedure &proc2) {
2219   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
2220   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
2221   } else if (proc1 != proc2) {
2222     Say(symbol1, symbol2,
2223         "Dummy procedure '%s' does not match the corresponding argument in"
2224         " the interface body"_err_en_US);
2225   }
2226 }
2227 
2228 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
2229     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
2230   if (intent1 == intent2) {
2231     return true;
2232   } else {
2233     Say(symbol1, symbol2,
2234         "The intent of dummy argument '%s' does not match the intent"
2235         " of the corresponding argument in the interface body"_err_en_US);
2236     return false;
2237   }
2238 }
2239 
2240 // Report an error referring to first symbol with declaration of second symbol
2241 template <typename... A>
2242 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
2243     parser::MessageFixedText &&text, A &&...args) {
2244   auto &message{context().Say(symbol1.name(), std::move(text), symbol1.name(),
2245       std::forward<A>(args)...)};
2246   evaluate::AttachDeclaration(message, symbol2);
2247 }
2248 
2249 template <typename ATTRS>
2250 bool SubprogramMatchHelper::CheckSameAttrs(
2251     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
2252   if (attrs1 == attrs2) {
2253     return true;
2254   }
2255   attrs1.IterateOverMembers([&](auto attr) {
2256     if (!attrs2.test(attr)) {
2257       Say(symbol1, symbol2,
2258           "Dummy argument '%s' has the %s attribute; the corresponding"
2259           " argument in the interface body does not"_err_en_US,
2260           AsFortran(attr));
2261     }
2262   });
2263   attrs2.IterateOverMembers([&](auto attr) {
2264     if (!attrs1.test(attr)) {
2265       Say(symbol1, symbol2,
2266           "Dummy argument '%s' does not have the %s attribute; the"
2267           " corresponding argument in the interface body does"_err_en_US,
2268           AsFortran(attr));
2269     }
2270   });
2271   return false;
2272 }
2273 
2274 bool SubprogramMatchHelper::ShapesAreCompatible(
2275     const DummyDataObject &obj1, const DummyDataObject &obj2) {
2276   return characteristics::ShapesAreCompatible(
2277       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
2278 }
2279 
2280 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
2281   evaluate::Shape result;
2282   for (const auto &extent : shape) {
2283     result.emplace_back(
2284         evaluate::Fold(context().foldingContext(), common::Clone(extent)));
2285   }
2286   return result;
2287 }
2288 
2289 void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
2290     const Symbol &specific, const Procedure &procedure) {
2291   if (!context_.HasError(specific)) {
2292     nameToInfo_[generic.name()].emplace_back(
2293         ProcedureInfo{kind, specific, procedure});
2294   }
2295 }
2296 
2297 void DistinguishabilityHelper::Check(const Scope &scope) {
2298   for (const auto &[name, info] : nameToInfo_) {
2299     auto count{info.size()};
2300     for (std::size_t i1{0}; i1 < count - 1; ++i1) {
2301       const auto &[kind, symbol, proc]{info[i1]};
2302       for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
2303         auto distinguishable{kind.IsName()
2304                 ? evaluate::characteristics::Distinguishable
2305                 : evaluate::characteristics::DistinguishableOpOrAssign};
2306         if (!distinguishable(
2307                 context_.languageFeatures(), proc, info[i2].procedure)) {
2308           SayNotDistinguishable(GetTopLevelUnitContaining(scope), name, kind,
2309               symbol, info[i2].symbol);
2310         }
2311       }
2312     }
2313   }
2314 }
2315 
2316 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
2317     const SourceName &name, GenericKind kind, const Symbol &proc1,
2318     const Symbol &proc2) {
2319   std::string name1{proc1.name().ToString()};
2320   std::string name2{proc2.name().ToString()};
2321   if (kind.IsOperator() || kind.IsAssignment()) {
2322     // proc1 and proc2 may come from different scopes so qualify their names
2323     if (proc1.owner().IsDerivedType()) {
2324       name1 = proc1.owner().GetName()->ToString() + '%' + name1;
2325     }
2326     if (proc2.owner().IsDerivedType()) {
2327       name2 = proc2.owner().GetName()->ToString() + '%' + name2;
2328     }
2329   }
2330   parser::Message *msg;
2331   if (scope.sourceRange().Contains(name)) {
2332     msg = &context_.Say(name,
2333         "Generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2334         MakeOpName(name), name1, name2);
2335   } else {
2336     msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
2337         "USE-associated generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2338         MakeOpName(name), name1, name2);
2339   }
2340   AttachDeclaration(*msg, scope, proc1);
2341   AttachDeclaration(*msg, scope, proc2);
2342 }
2343 
2344 // `evaluate::AttachDeclaration` doesn't handle the generic case where `proc`
2345 // comes from a different module but is not necessarily use-associated.
2346 void DistinguishabilityHelper::AttachDeclaration(
2347     parser::Message &msg, const Scope &scope, const Symbol &proc) {
2348   const Scope &unit{GetTopLevelUnitContaining(proc)};
2349   if (unit == scope) {
2350     evaluate::AttachDeclaration(msg, proc);
2351   } else {
2352     msg.Attach(unit.GetName().value(),
2353         "'%s' is USE-associated from module '%s'"_en_US, proc.name(),
2354         unit.GetName().value());
2355   }
2356 }
2357 
2358 void CheckDeclarations(SemanticsContext &context) {
2359   CheckHelper{context}.Check();
2360 }
2361 } // namespace Fortran::semantics
2362