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       if (IsInitialized(symbol)) {
241         messages_.Say(
242             "A pure subprogram may not initialize a variable"_err_en_US);
243       } else {
244         messages_.Say(
245             "A pure subprogram may not have a variable with the SAVE attribute"_err_en_US);
246       }
247     }
248     if (symbol.attrs().test(Attr::VOLATILE)) {
249       messages_.Say(
250           "A pure subprogram may not have a variable with the VOLATILE attribute"_err_en_US);
251     }
252     if (IsProcedure(symbol) && !IsPureProcedure(symbol) && IsDummy(symbol)) {
253       messages_.Say(
254           "A dummy procedure of a pure subprogram must be pure"_err_en_US);
255     }
256     if (!IsDummy(symbol) && !IsFunctionResult(symbol)) {
257       if (IsPolymorphicAllocatable(symbol)) {
258         SayWithDeclaration(symbol,
259             "Deallocation of polymorphic object '%s' is not permitted in a pure subprogram"_err_en_US,
260             symbol.name());
261       } else if (derived) {
262         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
263           SayWithDeclaration(*bad,
264               "Deallocation of polymorphic object '%s%s' is not permitted in a pure subprogram"_err_en_US,
265               symbol.name(), bad.BuildResultDesignatorName());
266         }
267       }
268     }
269   }
270   if (type) { // Section 7.2, paragraph 7
271     bool canHaveAssumedParameter{IsNamedConstant(symbol) ||
272         (IsAssumedLengthCharacter(symbol) && // C722
273             IsExternal(symbol)) ||
274         symbol.test(Symbol::Flag::ParentComp)};
275     if (!IsStmtFunctionDummy(symbol)) { // C726
276       if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
277         canHaveAssumedParameter |= object->isDummy() ||
278             (object->isFuncResult() &&
279                 type->category() == DeclTypeSpec::Character) ||
280             IsStmtFunctionResult(symbol); // Avoids multiple messages
281       } else {
282         canHaveAssumedParameter |= symbol.has<AssocEntityDetails>();
283       }
284     }
285     Check(*type, canHaveAssumedParameter);
286     if (InPure() && InFunction() && IsFunctionResult(symbol)) {
287       if (derived && HasImpureFinal(*derived)) { // C1584
288         messages_.Say(
289             "Result of pure function may not have an impure FINAL subroutine"_err_en_US);
290       }
291       if (type->IsPolymorphic() && IsAllocatable(symbol)) { // C1585
292         messages_.Say(
293             "Result of pure function may not be both polymorphic and ALLOCATABLE"_err_en_US);
294       }
295       if (derived) {
296         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
297           SayWithDeclaration(*bad,
298               "Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%s'"_err_en_US,
299               bad.BuildResultDesignatorName());
300         }
301       }
302     }
303   }
304   if (IsAssumedLengthCharacter(symbol) && IsExternal(symbol)) { // C723
305     if (symbol.attrs().test(Attr::RECURSIVE)) {
306       messages_.Say(
307           "An assumed-length CHARACTER(*) function cannot be RECURSIVE"_err_en_US);
308     }
309     if (symbol.Rank() > 0) {
310       messages_.Say(
311           "An assumed-length CHARACTER(*) function cannot return an array"_err_en_US);
312     }
313     if (symbol.attrs().test(Attr::PURE)) {
314       messages_.Say(
315           "An assumed-length CHARACTER(*) function cannot be PURE"_err_en_US);
316     }
317     if (symbol.attrs().test(Attr::ELEMENTAL)) {
318       messages_.Say(
319           "An assumed-length CHARACTER(*) function cannot be ELEMENTAL"_err_en_US);
320     }
321     if (const Symbol * result{FindFunctionResult(symbol)}) {
322       if (IsPointer(*result)) {
323         messages_.Say(
324             "An assumed-length CHARACTER(*) function cannot return a POINTER"_err_en_US);
325       }
326     }
327   }
328   if (symbol.attrs().test(Attr::VALUE)) {
329     CheckValue(symbol, derived);
330   }
331   if (symbol.attrs().test(Attr::CONTIGUOUS) && IsPointer(symbol) &&
332       symbol.Rank() == 0) { // C830
333     messages_.Say("CONTIGUOUS POINTER must be an array"_err_en_US);
334   }
335   if (IsDummy(symbol)) {
336     if (IsNamedConstant(symbol)) {
337       messages_.Say(
338           "A dummy argument may not also be a named constant"_err_en_US);
339     }
340     if (!symbol.test(Symbol::Flag::InDataStmt) /*caught elsewhere*/ &&
341         IsSaved(symbol)) {
342       messages_.Say(
343           "A dummy argument may not have the SAVE attribute"_err_en_US);
344     }
345   } else if (IsFunctionResult(symbol)) {
346     if (!symbol.test(Symbol::Flag::InDataStmt) /*caught elsewhere*/ &&
347         IsSaved(symbol)) {
348       messages_.Say(
349           "A function result may not have the SAVE attribute"_err_en_US);
350     }
351   }
352   if (symbol.owner().IsDerivedType() &&
353       (symbol.attrs().test(Attr::CONTIGUOUS) &&
354           !(IsPointer(symbol) && symbol.Rank() > 0))) { // C752
355     messages_.Say(
356         "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
357   }
358   if (symbol.owner().IsModule() && IsAutomatic(symbol)) {
359     messages_.Say(
360         "Automatic data object '%s' may not appear in the specification part"
361         " of a module"_err_en_US,
362         symbol.name());
363   }
364 }
365 
366 void CheckHelper::CheckValue(
367     const Symbol &symbol, const DerivedTypeSpec *derived) { // C863 - C865
368   if (!IsDummy(symbol)) {
369     messages_.Say(
370         "VALUE attribute may apply only to a dummy argument"_err_en_US);
371   }
372   if (IsProcedure(symbol)) {
373     messages_.Say(
374         "VALUE attribute may apply only to a dummy data object"_err_en_US);
375   }
376   if (IsAssumedSizeArray(symbol)) {
377     messages_.Say(
378         "VALUE attribute may not apply to an assumed-size array"_err_en_US);
379   }
380   if (evaluate::IsCoarray(symbol)) {
381     messages_.Say("VALUE attribute may not apply to a coarray"_err_en_US);
382   }
383   if (IsAllocatable(symbol)) {
384     messages_.Say("VALUE attribute may not apply to an ALLOCATABLE"_err_en_US);
385   } else if (IsPointer(symbol)) {
386     messages_.Say("VALUE attribute may not apply to a POINTER"_err_en_US);
387   }
388   if (IsIntentInOut(symbol)) {
389     messages_.Say(
390         "VALUE attribute may not apply to an INTENT(IN OUT) argument"_err_en_US);
391   } else if (IsIntentOut(symbol)) {
392     messages_.Say(
393         "VALUE attribute may not apply to an INTENT(OUT) argument"_err_en_US);
394   }
395   if (symbol.attrs().test(Attr::VOLATILE)) {
396     messages_.Say("VALUE attribute may not apply to a VOLATILE"_err_en_US);
397   }
398   if (innermostSymbol_ && IsBindCProcedure(*innermostSymbol_) &&
399       IsOptional(symbol)) {
400     messages_.Say(
401         "VALUE attribute may not apply to an OPTIONAL in a BIND(C) procedure"_err_en_US);
402   }
403   if (derived) {
404     if (FindCoarrayUltimateComponent(*derived)) {
405       messages_.Say(
406           "VALUE attribute may not apply to a type with a coarray ultimate component"_err_en_US);
407     }
408   }
409 }
410 
411 void CheckHelper::CheckAssumedTypeEntity( // C709
412     const Symbol &symbol, const ObjectEntityDetails &details) {
413   if (const DeclTypeSpec * type{symbol.GetType()};
414       type && type->category() == DeclTypeSpec::TypeStar) {
415     if (!IsDummy(symbol)) {
416       messages_.Say(
417           "Assumed-type entity '%s' must be a dummy argument"_err_en_US,
418           symbol.name());
419     } else {
420       if (symbol.attrs().test(Attr::ALLOCATABLE)) {
421         messages_.Say("Assumed-type argument '%s' cannot have the ALLOCATABLE"
422                       " attribute"_err_en_US,
423             symbol.name());
424       }
425       if (symbol.attrs().test(Attr::POINTER)) {
426         messages_.Say("Assumed-type argument '%s' cannot have the POINTER"
427                       " attribute"_err_en_US,
428             symbol.name());
429       }
430       if (symbol.attrs().test(Attr::VALUE)) {
431         messages_.Say("Assumed-type argument '%s' cannot have the VALUE"
432                       " attribute"_err_en_US,
433             symbol.name());
434       }
435       if (symbol.attrs().test(Attr::INTENT_OUT)) {
436         messages_.Say(
437             "Assumed-type argument '%s' cannot be INTENT(OUT)"_err_en_US,
438             symbol.name());
439       }
440       if (evaluate::IsCoarray(symbol)) {
441         messages_.Say(
442             "Assumed-type argument '%s' cannot be a coarray"_err_en_US,
443             symbol.name());
444       }
445       if (details.IsArray() && details.shape().IsExplicitShape()) {
446         messages_.Say(
447             "Assumed-type array argument 'arg8' must be assumed shape,"
448             " assumed size, or assumed rank"_err_en_US,
449             symbol.name());
450       }
451     }
452   }
453 }
454 
455 void CheckHelper::CheckObjectEntity(
456     const Symbol &symbol, const ObjectEntityDetails &details) {
457   CheckArraySpec(symbol, details.shape());
458   Check(details.shape());
459   Check(details.coshape());
460   CheckAssumedTypeEntity(symbol, details);
461   WarnMissingFinal(symbol);
462   if (!details.coshape().empty()) {
463     bool isDeferredCoshape{details.coshape().CanBeDeferredShape()};
464     if (IsAllocatable(symbol)) {
465       if (!isDeferredCoshape) { // C827
466         messages_.Say("'%s' is an ALLOCATABLE coarray and must have a deferred"
467                       " coshape"_err_en_US,
468             symbol.name());
469       }
470     } else if (symbol.owner().IsDerivedType()) { // C746
471       std::string deferredMsg{
472           isDeferredCoshape ? "" : " and have a deferred coshape"};
473       messages_.Say("Component '%s' is a coarray and must have the ALLOCATABLE"
474                     " attribute%s"_err_en_US,
475           symbol.name(), deferredMsg);
476     } else {
477       if (!details.coshape().CanBeAssumedSize()) { // C828
478         messages_.Say(
479             "'%s' is a non-ALLOCATABLE coarray and must have an explicit coshape"_err_en_US,
480             symbol.name());
481       }
482     }
483     if (const DeclTypeSpec * type{details.type()}) {
484       if (IsBadCoarrayType(type->AsDerived())) { // C747 & C824
485         messages_.Say(
486             "Coarray '%s' may not have type TEAM_TYPE, C_PTR, or C_FUNPTR"_err_en_US,
487             symbol.name());
488       }
489     }
490   }
491   if (details.isDummy()) {
492     if (symbol.attrs().test(Attr::INTENT_OUT)) {
493       if (FindUltimateComponent(symbol, [](const Symbol &x) {
494             return evaluate::IsCoarray(x) && IsAllocatable(x);
495           })) { // C846
496         messages_.Say(
497             "An INTENT(OUT) dummy argument may not be, or contain, an ALLOCATABLE coarray"_err_en_US);
498       }
499       if (IsOrContainsEventOrLockComponent(symbol)) { // C847
500         messages_.Say(
501             "An INTENT(OUT) dummy argument may not be, or contain, EVENT_TYPE or LOCK_TYPE"_err_en_US);
502       }
503     }
504     if (InPure() && !IsStmtFunction(DEREF(innermostSymbol_)) &&
505         !IsPointer(symbol) && !IsIntentIn(symbol) &&
506         !symbol.attrs().test(Attr::VALUE)) {
507       if (InFunction()) { // C1583
508         messages_.Say(
509             "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
510       } else if (IsIntentOut(symbol)) {
511         if (const DeclTypeSpec * type{details.type()}) {
512           if (type && type->IsPolymorphic()) { // C1588
513             messages_.Say(
514                 "An INTENT(OUT) dummy argument of a pure subroutine may not be polymorphic"_err_en_US);
515           } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
516             if (FindUltimateComponent(*derived, [](const Symbol &x) {
517                   const DeclTypeSpec *type{x.GetType()};
518                   return type && type->IsPolymorphic();
519                 })) { // C1588
520               messages_.Say(
521                   "An INTENT(OUT) dummy argument of a pure subroutine may not have a polymorphic ultimate component"_err_en_US);
522             }
523             if (HasImpureFinal(*derived)) { // C1587
524               messages_.Say(
525                   "An INTENT(OUT) dummy argument of a pure subroutine may not have an impure FINAL subroutine"_err_en_US);
526             }
527           }
528         }
529       } else if (!IsIntentInOut(symbol)) { // C1586
530         messages_.Say(
531             "non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute"_err_en_US);
532       }
533     }
534   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
535       symbol.attrs().test(Attr::INTENT_OUT) ||
536       symbol.attrs().test(Attr::INTENT_INOUT)) {
537     messages_.Say("INTENT attributes may apply only to a dummy "
538                   "argument"_err_en_US); // C843
539   } else if (IsOptional(symbol)) {
540     messages_.Say("OPTIONAL attribute may apply only to a dummy "
541                   "argument"_err_en_US); // C849
542   }
543   if (InElemental()) {
544     if (details.isDummy()) { // C15100
545       if (details.shape().Rank() > 0) {
546         messages_.Say(
547             "A dummy argument of an ELEMENTAL procedure must be scalar"_err_en_US);
548       }
549       if (IsAllocatable(symbol)) {
550         messages_.Say(
551             "A dummy argument of an ELEMENTAL procedure may not be ALLOCATABLE"_err_en_US);
552       }
553       if (evaluate::IsCoarray(symbol)) {
554         messages_.Say(
555             "A dummy argument of an ELEMENTAL procedure may not be a coarray"_err_en_US);
556       }
557       if (IsPointer(symbol)) {
558         messages_.Say(
559             "A dummy argument of an ELEMENTAL procedure may not be a POINTER"_err_en_US);
560       }
561       if (!symbol.attrs().HasAny(Attrs{Attr::VALUE, Attr::INTENT_IN,
562               Attr::INTENT_INOUT, Attr::INTENT_OUT})) { // C15102
563         messages_.Say(
564             "A dummy argument of an ELEMENTAL procedure must have an INTENT() or VALUE attribute"_err_en_US);
565       }
566     } else if (IsFunctionResult(symbol)) { // C15101
567       if (details.shape().Rank() > 0) {
568         messages_.Say(
569             "The result of an ELEMENTAL function must be scalar"_err_en_US);
570       }
571       if (IsAllocatable(symbol)) {
572         messages_.Say(
573             "The result of an ELEMENTAL function may not be ALLOCATABLE"_err_en_US);
574       }
575       if (IsPointer(symbol)) {
576         messages_.Say(
577             "The result of an ELEMENTAL function may not be a POINTER"_err_en_US);
578       }
579     }
580   }
581   if (HasDeclarationInitializer(symbol)) { // C808; ignore DATA initialization
582     CheckPointerInitialization(symbol);
583     if (IsAutomatic(symbol)) {
584       messages_.Say(
585           "An automatic variable or component must not be initialized"_err_en_US);
586     } else if (IsDummy(symbol)) {
587       messages_.Say("A dummy argument must not be initialized"_err_en_US);
588     } else if (IsFunctionResult(symbol)) {
589       messages_.Say("A function result must not be initialized"_err_en_US);
590     } else if (IsInBlankCommon(symbol)) {
591       messages_.Say(
592           "A variable in blank COMMON should not be initialized"_en_US);
593     }
594   }
595   if (symbol.owner().kind() == Scope::Kind::BlockData) {
596     if (IsAllocatable(symbol)) {
597       messages_.Say(
598           "An ALLOCATABLE variable may not appear in a BLOCK DATA subprogram"_err_en_US);
599     } else if (IsInitialized(symbol) && !FindCommonBlockContaining(symbol)) {
600       messages_.Say(
601           "An initialized variable in BLOCK DATA must be in a COMMON block"_err_en_US);
602     }
603   }
604   if (const DeclTypeSpec * type{details.type()}) { // C708
605     if (type->IsPolymorphic() &&
606         !(type->IsAssumedType() || IsAllocatableOrPointer(symbol) ||
607             IsDummy(symbol))) {
608       messages_.Say("CLASS entity '%s' must be a dummy argument or have "
609                     "ALLOCATABLE or POINTER attribute"_err_en_US,
610           symbol.name());
611     }
612   }
613 }
614 
615 void CheckHelper::CheckPointerInitialization(const Symbol &symbol) {
616   if (IsPointer(symbol) && !context_.HasError(symbol) &&
617       !scopeIsUninstantiatedPDT_) {
618     if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
619       if (object->init()) { // C764, C765; C808
620         if (auto designator{evaluate::AsGenericExpr(symbol)}) {
621           auto restorer{messages_.SetLocation(symbol.name())};
622           context_.set_location(symbol.name());
623           CheckInitialTarget(foldingContext_, *designator, *object->init());
624         }
625       }
626     } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
627       if (proc->init() && *proc->init()) {
628         // C1519 - must be nonelemental external or module procedure,
629         // or an unrestricted specific intrinsic function.
630         const Symbol &ultimate{(*proc->init())->GetUltimate()};
631         if (ultimate.attrs().test(Attr::INTRINSIC)) {
632           if (const auto intrinsic{
633                   context_.intrinsics().IsSpecificIntrinsicFunction(
634                       ultimate.name().ToString())};
635               !intrinsic || intrinsic->isRestrictedSpecific) { // C1030
636             context_.Say(
637                 "Intrinsic procedure '%s' is not an unrestricted specific "
638                 "intrinsic permitted for use as the initializer for procedure "
639                 "pointer '%s'"_err_en_US,
640                 ultimate.name(), symbol.name());
641           }
642         } else if (!ultimate.attrs().test(Attr::EXTERNAL) &&
643             ultimate.owner().kind() != Scope::Kind::Module) {
644           context_.Say("Procedure pointer '%s' initializer '%s' is neither "
645                        "an external nor a module procedure"_err_en_US,
646               symbol.name(), ultimate.name());
647         } else if (ultimate.attrs().test(Attr::ELEMENTAL)) {
648           context_.Say("Procedure pointer '%s' cannot be initialized with the "
649                        "elemental procedure '%s"_err_en_US,
650               symbol.name(), ultimate.name());
651         } else {
652           // TODO: Check the "shalls" in the 15.4.3.6 paragraphs 7-10.
653         }
654       }
655     }
656   }
657 }
658 
659 // The six different kinds of array-specs:
660 //   array-spec     -> explicit-shape-list | deferred-shape-list
661 //                     | assumed-shape-list | implied-shape-list
662 //                     | assumed-size | assumed-rank
663 //   explicit-shape -> [ lb : ] ub
664 //   deferred-shape -> :
665 //   assumed-shape  -> [ lb ] :
666 //   implied-shape  -> [ lb : ] *
667 //   assumed-size   -> [ explicit-shape-list , ] [ lb : ] *
668 //   assumed-rank   -> ..
669 // Note:
670 // - deferred-shape is also an assumed-shape
671 // - A single "*" or "lb:*" might be assumed-size or implied-shape-list
672 void CheckHelper::CheckArraySpec(
673     const Symbol &symbol, const ArraySpec &arraySpec) {
674   if (arraySpec.Rank() == 0) {
675     return;
676   }
677   bool isExplicit{arraySpec.IsExplicitShape()};
678   bool canBeDeferred{arraySpec.CanBeDeferredShape()};
679   bool canBeImplied{arraySpec.CanBeImpliedShape()};
680   bool canBeAssumedShape{arraySpec.CanBeAssumedShape()};
681   bool canBeAssumedSize{arraySpec.CanBeAssumedSize()};
682   bool isAssumedRank{arraySpec.IsAssumedRank()};
683   std::optional<parser::MessageFixedText> msg;
684   if (symbol.test(Symbol::Flag::CrayPointee) && !isExplicit &&
685       !canBeAssumedSize) {
686     msg = "Cray pointee '%s' must have must have explicit shape or"
687           " assumed size"_err_en_US;
688   } else if (IsAllocatableOrPointer(symbol) && !canBeDeferred &&
689       !isAssumedRank) {
690     if (symbol.owner().IsDerivedType()) { // C745
691       if (IsAllocatable(symbol)) {
692         msg = "Allocatable array component '%s' must have"
693               " deferred shape"_err_en_US;
694       } else {
695         msg = "Array pointer component '%s' must have deferred shape"_err_en_US;
696       }
697     } else {
698       if (IsAllocatable(symbol)) { // C832
699         msg = "Allocatable array '%s' must have deferred shape or"
700               " assumed rank"_err_en_US;
701       } else {
702         msg = "Array pointer '%s' must have deferred shape or"
703               " assumed rank"_err_en_US;
704       }
705     }
706   } else if (IsDummy(symbol)) {
707     if (canBeImplied && !canBeAssumedSize) { // C836
708       msg = "Dummy array argument '%s' may not have implied shape"_err_en_US;
709     }
710   } else if (canBeAssumedShape && !canBeDeferred) {
711     msg = "Assumed-shape array '%s' must be a dummy argument"_err_en_US;
712   } else if (canBeAssumedSize && !canBeImplied) { // C833
713     msg = "Assumed-size array '%s' must be a dummy argument"_err_en_US;
714   } else if (isAssumedRank) { // C837
715     msg = "Assumed-rank array '%s' must be a dummy argument"_err_en_US;
716   } else if (canBeImplied) {
717     if (!IsNamedConstant(symbol)) { // C835, C836
718       msg = "Implied-shape array '%s' must be a named constant or a "
719             "dummy argument"_err_en_US;
720     }
721   } else if (IsNamedConstant(symbol)) {
722     if (!isExplicit && !canBeImplied) {
723       msg = "Named constant '%s' array must have constant or"
724             " implied shape"_err_en_US;
725     }
726   } else if (!IsAllocatableOrPointer(symbol) && !isExplicit) {
727     if (symbol.owner().IsDerivedType()) { // C749
728       msg = "Component array '%s' without ALLOCATABLE or POINTER attribute must"
729             " have explicit shape"_err_en_US;
730     } else { // C816
731       msg = "Array '%s' without ALLOCATABLE or POINTER attribute must have"
732             " explicit shape"_err_en_US;
733     }
734   }
735   if (msg) {
736     context_.Say(std::move(*msg), symbol.name());
737   }
738 }
739 
740 void CheckHelper::CheckProcEntity(
741     const Symbol &symbol, const ProcEntityDetails &details) {
742   if (details.isDummy()) {
743     if (!symbol.attrs().test(Attr::POINTER) && // C843
744         (symbol.attrs().test(Attr::INTENT_IN) ||
745             symbol.attrs().test(Attr::INTENT_OUT) ||
746             symbol.attrs().test(Attr::INTENT_INOUT))) {
747       messages_.Say("A dummy procedure without the POINTER attribute"
748                     " may not have an INTENT attribute"_err_en_US);
749     }
750     if (InElemental()) { // C15100
751       messages_.Say(
752           "An ELEMENTAL subprogram may not have a dummy procedure"_err_en_US);
753     }
754     const Symbol *interface { details.interface().symbol() };
755     if (!symbol.attrs().test(Attr::INTRINSIC) &&
756         (symbol.attrs().test(Attr::ELEMENTAL) ||
757             (interface && !interface->attrs().test(Attr::INTRINSIC) &&
758                 interface->attrs().test(Attr::ELEMENTAL)))) {
759       // There's no explicit constraint or "shall" that we can find in the
760       // standard for this check, but it seems to be implied in multiple
761       // sites, and ELEMENTAL non-intrinsic actual arguments *are*
762       // explicitly forbidden.  But we allow "PROCEDURE(SIN)::dummy"
763       // because it is explicitly legal to *pass* the specific intrinsic
764       // function SIN as an actual argument.
765       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
766     }
767   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
768       symbol.attrs().test(Attr::INTENT_OUT) ||
769       symbol.attrs().test(Attr::INTENT_INOUT)) {
770     messages_.Say("INTENT attributes may apply only to a dummy "
771                   "argument"_err_en_US); // C843
772   } else if (IsOptional(symbol)) {
773     messages_.Say("OPTIONAL attribute may apply only to a dummy "
774                   "argument"_err_en_US); // C849
775   } else if (symbol.owner().IsDerivedType()) {
776     if (!symbol.attrs().test(Attr::POINTER)) { // C756
777       const auto &name{symbol.name()};
778       messages_.Say(name,
779           "Procedure component '%s' must have POINTER attribute"_err_en_US,
780           name);
781     }
782     CheckPassArg(symbol, details.interface().symbol(), details);
783   }
784   if (symbol.attrs().test(Attr::POINTER)) {
785     CheckPointerInitialization(symbol);
786     if (const Symbol * interface{details.interface().symbol()}) {
787       if (interface->attrs().test(Attr::INTRINSIC)) {
788         if (const auto intrinsic{
789                 context_.intrinsics().IsSpecificIntrinsicFunction(
790                     interface->name().ToString())};
791             !intrinsic || intrinsic->isRestrictedSpecific) { // C1515
792           messages_.Say(
793               "Intrinsic procedure '%s' is not an unrestricted specific "
794               "intrinsic permitted for use as the definition of the interface "
795               "to procedure pointer '%s'"_err_en_US,
796               interface->name(), symbol.name());
797         }
798       } else if (interface->attrs().test(Attr::ELEMENTAL)) {
799         messages_.Say("Procedure pointer '%s' may not be ELEMENTAL"_err_en_US,
800             symbol.name()); // C1517
801       }
802     }
803   } else if (symbol.attrs().test(Attr::SAVE)) {
804     messages_.Say(
805         "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US,
806         symbol.name());
807   }
808 }
809 
810 // When a module subprogram has the MODULE prefix the following must match
811 // with the corresponding separate module procedure interface body:
812 // - C1549: characteristics and dummy argument names
813 // - C1550: binding label
814 // - C1551: NON_RECURSIVE prefix
815 class SubprogramMatchHelper {
816 public:
817   explicit SubprogramMatchHelper(CheckHelper &checkHelper)
818       : checkHelper{checkHelper} {}
819 
820   void Check(const Symbol &, const Symbol &);
821 
822 private:
823   SemanticsContext &context() { return checkHelper.context(); }
824   void CheckDummyArg(const Symbol &, const Symbol &, const DummyArgument &,
825       const DummyArgument &);
826   void CheckDummyDataObject(const Symbol &, const Symbol &,
827       const DummyDataObject &, const DummyDataObject &);
828   void CheckDummyProcedure(const Symbol &, const Symbol &,
829       const DummyProcedure &, const DummyProcedure &);
830   bool CheckSameIntent(
831       const Symbol &, const Symbol &, common::Intent, common::Intent);
832   template <typename... A>
833   void Say(
834       const Symbol &, const Symbol &, parser::MessageFixedText &&, A &&...);
835   template <typename ATTRS>
836   bool CheckSameAttrs(const Symbol &, const Symbol &, ATTRS, ATTRS);
837   bool ShapesAreCompatible(const DummyDataObject &, const DummyDataObject &);
838   evaluate::Shape FoldShape(const evaluate::Shape &);
839   std::string AsFortran(DummyDataObject::Attr attr) {
840     return parser::ToUpperCaseLetters(DummyDataObject::EnumToString(attr));
841   }
842   std::string AsFortran(DummyProcedure::Attr attr) {
843     return parser::ToUpperCaseLetters(DummyProcedure::EnumToString(attr));
844   }
845 
846   CheckHelper &checkHelper;
847 };
848 
849 // 15.6.2.6 para 3 - can the result of an ENTRY differ from its function?
850 bool CheckHelper::IsResultOkToDiffer(const FunctionResult &result) {
851   if (result.attrs.test(FunctionResult::Attr::Allocatable) ||
852       result.attrs.test(FunctionResult::Attr::Pointer)) {
853     return false;
854   }
855   const auto *typeAndShape{result.GetTypeAndShape()};
856   if (!typeAndShape || typeAndShape->Rank() != 0) {
857     return false;
858   }
859   auto category{typeAndShape->type().category()};
860   if (category == TypeCategory::Character ||
861       category == TypeCategory::Derived) {
862     return false;
863   }
864   int kind{typeAndShape->type().kind()};
865   return kind == context_.GetDefaultKind(category) ||
866       (category == TypeCategory::Real &&
867           kind == context_.doublePrecisionKind());
868 }
869 
870 void CheckHelper::CheckSubprogram(
871     const Symbol &symbol, const SubprogramDetails &details) {
872   if (const Symbol * iface{FindSeparateModuleSubprogramInterface(&symbol)}) {
873     SubprogramMatchHelper{*this}.Check(symbol, *iface);
874   }
875   if (const Scope * entryScope{details.entryScope()}) {
876     // ENTRY 15.6.2.6, esp. C1571
877     std::optional<parser::MessageFixedText> error;
878     const Symbol *subprogram{entryScope->symbol()};
879     const SubprogramDetails *subprogramDetails{nullptr};
880     if (subprogram) {
881       subprogramDetails = subprogram->detailsIf<SubprogramDetails>();
882     }
883     if (entryScope->kind() != Scope::Kind::Subprogram) {
884       error = "ENTRY may appear only in a subroutine or function"_err_en_US;
885     } else if (!(entryScope->parent().IsGlobal() ||
886                    entryScope->parent().IsModule() ||
887                    entryScope->parent().IsSubmodule())) {
888       error = "ENTRY may not appear in an internal subprogram"_err_en_US;
889     } else if (FindSeparateModuleSubprogramInterface(subprogram)) {
890       error = "ENTRY may not appear in a separate module procedure"_err_en_US;
891     } else if (subprogramDetails && details.isFunction() &&
892         subprogramDetails->isFunction() &&
893         !context_.HasError(details.result()) &&
894         !context_.HasError(subprogramDetails->result())) {
895       auto result{FunctionResult::Characterize(
896           details.result(), context_.foldingContext())};
897       auto subpResult{FunctionResult::Characterize(
898           subprogramDetails->result(), context_.foldingContext())};
899       if (result && subpResult && *result != *subpResult &&
900           (!IsResultOkToDiffer(*result) || !IsResultOkToDiffer(*subpResult))) {
901         error =
902             "Result of ENTRY is not compatible with result of containing function"_err_en_US;
903       }
904     }
905     if (error) {
906       if (auto *msg{messages_.Say(symbol.name(), *error)}) {
907         if (subprogram) {
908           msg->Attach(subprogram->name(), "Containing subprogram"_en_US);
909         }
910       }
911     }
912   }
913   if (symbol.attrs().test(Attr::ELEMENTAL)) {
914     // See comment on the similar check in CheckProcEntity()
915     if (details.isDummy()) {
916       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
917     } else {
918       for (const Symbol *dummy : details.dummyArgs()) {
919         if (!dummy) { // C15100
920           messages_.Say(
921               "An ELEMENTAL subroutine may not have an alternate return dummy argument"_err_en_US);
922         }
923       }
924     }
925   }
926 }
927 
928 void CheckHelper::CheckDerivedType(
929     const Symbol &derivedType, const DerivedTypeDetails &details) {
930   if (details.isForwardReferenced() && !context_.HasError(derivedType)) {
931     messages_.Say("The derived type '%s' has not been defined"_err_en_US,
932         derivedType.name());
933   }
934   const Scope *scope{derivedType.scope()};
935   if (!scope) {
936     CHECK(details.isForwardReferenced());
937     return;
938   }
939   CHECK(scope->symbol() == &derivedType);
940   CHECK(scope->IsDerivedType());
941   if (derivedType.attrs().test(Attr::ABSTRACT) && // C734
942       (derivedType.attrs().test(Attr::BIND_C) || details.sequence())) {
943     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
944   }
945   if (const DeclTypeSpec * parent{FindParentTypeSpec(derivedType)}) {
946     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
947     if (!IsExtensibleType(parentDerived)) { // C705
948       messages_.Say("The parent type is not extensible"_err_en_US);
949     }
950     if (!derivedType.attrs().test(Attr::ABSTRACT) && parentDerived &&
951         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
952       ScopeComponentIterator components{*parentDerived};
953       for (const Symbol &component : components) {
954         if (component.attrs().test(Attr::DEFERRED)) {
955           if (scope->FindComponent(component.name()) == &component) {
956             SayWithDeclaration(component,
957                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
958                 parentDerived->typeSymbol().name(), component.name());
959           }
960         }
961       }
962     }
963     DerivedTypeSpec derived{derivedType.name(), derivedType};
964     derived.set_scope(*scope);
965     if (FindCoarrayUltimateComponent(derived) && // C736
966         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
967       messages_.Say(
968           "Type '%s' has a coarray ultimate component so the type at the base "
969           "of its type extension chain ('%s') must be a type that has a "
970           "coarray ultimate component"_err_en_US,
971           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
972     }
973     if (FindEventOrLockPotentialComponent(derived) && // C737
974         !(FindEventOrLockPotentialComponent(*parentDerived) ||
975             IsEventTypeOrLockType(parentDerived))) {
976       messages_.Say(
977           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
978           "at the base of its type extension chain ('%s') must either have an "
979           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
980           "LOCK_TYPE"_err_en_US,
981           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
982     }
983   }
984   if (HasIntrinsicTypeName(derivedType)) { // C729
985     messages_.Say("A derived type name cannot be the name of an intrinsic"
986                   " type"_err_en_US);
987   }
988   std::map<SourceName, SymbolRef> previous;
989   for (const auto &pair : details.finals()) {
990     SourceName source{pair.first};
991     const Symbol &ref{*pair.second};
992     if (CheckFinal(ref, source, derivedType) &&
993         std::all_of(previous.begin(), previous.end(),
994             [&](std::pair<SourceName, SymbolRef> prev) {
995               return CheckDistinguishableFinals(
996                   ref, source, *prev.second, prev.first, derivedType);
997             })) {
998       previous.emplace(source, ref);
999     }
1000   }
1001 }
1002 
1003 // C786
1004 bool CheckHelper::CheckFinal(
1005     const Symbol &subroutine, SourceName finalName, const Symbol &derivedType) {
1006   if (!IsModuleProcedure(subroutine)) {
1007     SayWithDeclaration(subroutine, finalName,
1008         "FINAL subroutine '%s' of derived type '%s' must be a module procedure"_err_en_US,
1009         subroutine.name(), derivedType.name());
1010     return false;
1011   }
1012   const Procedure *proc{Characterize(subroutine)};
1013   if (!proc) {
1014     return false; // error recovery
1015   }
1016   if (!proc->IsSubroutine()) {
1017     SayWithDeclaration(subroutine, finalName,
1018         "FINAL subroutine '%s' of derived type '%s' must be a subroutine"_err_en_US,
1019         subroutine.name(), derivedType.name());
1020     return false;
1021   }
1022   if (proc->dummyArguments.size() != 1) {
1023     SayWithDeclaration(subroutine, finalName,
1024         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument"_err_en_US,
1025         subroutine.name(), derivedType.name());
1026     return false;
1027   }
1028   const auto &arg{proc->dummyArguments[0]};
1029   const Symbol *errSym{&subroutine};
1030   if (const auto *details{subroutine.detailsIf<SubprogramDetails>()}) {
1031     if (!details->dummyArgs().empty()) {
1032       if (const Symbol * argSym{details->dummyArgs()[0]}) {
1033         errSym = argSym;
1034       }
1035     }
1036   }
1037   const auto *ddo{std::get_if<DummyDataObject>(&arg.u)};
1038   if (!ddo) {
1039     SayWithDeclaration(subroutine, finalName,
1040         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument that is a data object"_err_en_US,
1041         subroutine.name(), derivedType.name());
1042     return false;
1043   }
1044   bool ok{true};
1045   if (arg.IsOptional()) {
1046     SayWithDeclaration(*errSym, finalName,
1047         "FINAL subroutine '%s' of derived type '%s' must not have an OPTIONAL dummy argument"_err_en_US,
1048         subroutine.name(), derivedType.name());
1049     ok = false;
1050   }
1051   if (ddo->attrs.test(DummyDataObject::Attr::Allocatable)) {
1052     SayWithDeclaration(*errSym, finalName,
1053         "FINAL subroutine '%s' of derived type '%s' must not have an ALLOCATABLE dummy argument"_err_en_US,
1054         subroutine.name(), derivedType.name());
1055     ok = false;
1056   }
1057   if (ddo->attrs.test(DummyDataObject::Attr::Pointer)) {
1058     SayWithDeclaration(*errSym, finalName,
1059         "FINAL subroutine '%s' of derived type '%s' must not have a POINTER dummy argument"_err_en_US,
1060         subroutine.name(), derivedType.name());
1061     ok = false;
1062   }
1063   if (ddo->intent == common::Intent::Out) {
1064     SayWithDeclaration(*errSym, finalName,
1065         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with INTENT(OUT)"_err_en_US,
1066         subroutine.name(), derivedType.name());
1067     ok = false;
1068   }
1069   if (ddo->attrs.test(DummyDataObject::Attr::Value)) {
1070     SayWithDeclaration(*errSym, finalName,
1071         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with the VALUE attribute"_err_en_US,
1072         subroutine.name(), derivedType.name());
1073     ok = false;
1074   }
1075   if (ddo->type.corank() > 0) {
1076     SayWithDeclaration(*errSym, finalName,
1077         "FINAL subroutine '%s' of derived type '%s' must not have a coarray dummy argument"_err_en_US,
1078         subroutine.name(), derivedType.name());
1079     ok = false;
1080   }
1081   if (ddo->type.type().IsPolymorphic()) {
1082     SayWithDeclaration(*errSym, finalName,
1083         "FINAL subroutine '%s' of derived type '%s' must not have a polymorphic dummy argument"_err_en_US,
1084         subroutine.name(), derivedType.name());
1085     ok = false;
1086   } else if (ddo->type.type().category() != TypeCategory::Derived ||
1087       &ddo->type.type().GetDerivedTypeSpec().typeSymbol() != &derivedType) {
1088     SayWithDeclaration(*errSym, finalName,
1089         "FINAL subroutine '%s' of derived type '%s' must have a TYPE(%s) dummy argument"_err_en_US,
1090         subroutine.name(), derivedType.name(), derivedType.name());
1091     ok = false;
1092   } else { // check that all LEN type parameters are assumed
1093     for (auto ref : OrderParameterDeclarations(derivedType)) {
1094       if (IsLenTypeParameter(*ref)) {
1095         const auto *value{
1096             ddo->type.type().GetDerivedTypeSpec().FindParameter(ref->name())};
1097         if (!value || !value->isAssumed()) {
1098           SayWithDeclaration(*errSym, finalName,
1099               "FINAL subroutine '%s' of derived type '%s' must have a dummy argument with an assumed LEN type parameter '%s=*'"_err_en_US,
1100               subroutine.name(), derivedType.name(), ref->name());
1101           ok = false;
1102         }
1103       }
1104     }
1105   }
1106   return ok;
1107 }
1108 
1109 bool CheckHelper::CheckDistinguishableFinals(const Symbol &f1,
1110     SourceName f1Name, const Symbol &f2, SourceName f2Name,
1111     const Symbol &derivedType) {
1112   const Procedure *p1{Characterize(f1)};
1113   const Procedure *p2{Characterize(f2)};
1114   if (p1 && p2) {
1115     if (characteristics::Distinguishable(
1116             context_.languageFeatures(), *p1, *p2)) {
1117       return true;
1118     }
1119     if (auto *msg{messages_.Say(f1Name,
1120             "FINAL subroutines '%s' and '%s' of derived type '%s' cannot be distinguished by rank or KIND type parameter value"_err_en_US,
1121             f1Name, f2Name, derivedType.name())}) {
1122       msg->Attach(f2Name, "FINAL declaration of '%s'"_en_US, f2.name())
1123           .Attach(f1.name(), "Definition of '%s'"_en_US, f1Name)
1124           .Attach(f2.name(), "Definition of '%s'"_en_US, f2Name);
1125     }
1126   }
1127   return false;
1128 }
1129 
1130 void CheckHelper::CheckHostAssoc(
1131     const Symbol &symbol, const HostAssocDetails &details) {
1132   const Symbol &hostSymbol{details.symbol()};
1133   if (hostSymbol.test(Symbol::Flag::ImplicitOrError)) {
1134     if (details.implicitOrSpecExprError) {
1135       messages_.Say("Implicitly typed local entity '%s' not allowed in"
1136                     " specification expression"_err_en_US,
1137           symbol.name());
1138     } else if (details.implicitOrExplicitTypeError) {
1139       messages_.Say(
1140           "No explicit type declared for '%s'"_err_en_US, symbol.name());
1141     }
1142   }
1143 }
1144 
1145 void CheckHelper::CheckGeneric(
1146     const Symbol &symbol, const GenericDetails &details) {
1147   CheckSpecificsAreDistinguishable(symbol, details);
1148   std::visit(common::visitors{
1149                  [&](const GenericKind::DefinedIo &io) {
1150                    CheckDefinedIoProc(symbol, details, io);
1151                  },
1152                  [](const auto &) {},
1153              },
1154       details.kind().u);
1155 }
1156 
1157 // Check that the specifics of this generic are distinguishable from each other
1158 void CheckHelper::CheckSpecificsAreDistinguishable(
1159     const Symbol &generic, const GenericDetails &details) {
1160   GenericKind kind{details.kind()};
1161   const SymbolVector &specifics{details.specificProcs()};
1162   std::size_t count{specifics.size()};
1163   if (count < 2 || !kind.IsName()) {
1164     return;
1165   }
1166   DistinguishabilityHelper helper{context_};
1167   for (const Symbol &specific : specifics) {
1168     if (const Procedure * procedure{Characterize(specific)}) {
1169       helper.Add(generic, kind, specific, *procedure);
1170     }
1171   }
1172   helper.Check(generic.owner());
1173 }
1174 
1175 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
1176   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1177   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1178   return Tristate::No ==
1179       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
1180 }
1181 
1182 static bool ConflictsWithIntrinsicOperator(
1183     const GenericKind &kind, const Procedure &proc) {
1184   if (!kind.IsIntrinsicOperator()) {
1185     return false;
1186   }
1187   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1188   auto type0{arg0.type()};
1189   if (proc.dummyArguments.size() == 1) { // unary
1190     return std::visit(
1191         common::visitors{
1192             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
1193             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
1194             [](const auto &) -> bool { DIE("bad generic kind"); },
1195         },
1196         kind.u);
1197   } else { // binary
1198     int rank0{arg0.Rank()};
1199     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1200     auto type1{arg1.type()};
1201     int rank1{arg1.Rank()};
1202     return std::visit(
1203         common::visitors{
1204             [&](common::NumericOperator) {
1205               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
1206             },
1207             [&](common::LogicalOperator) {
1208               return IsIntrinsicLogical(type0, rank0, type1, rank1);
1209             },
1210             [&](common::RelationalOperator opr) {
1211               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
1212             },
1213             [&](GenericKind::OtherKind x) {
1214               CHECK(x == GenericKind::OtherKind::Concat);
1215               return IsIntrinsicConcat(type0, rank0, type1, rank1);
1216             },
1217             [](const auto &) -> bool { DIE("bad generic kind"); },
1218         },
1219         kind.u);
1220   }
1221 }
1222 
1223 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
1224 bool CheckHelper::CheckDefinedOperator(SourceName opName, GenericKind kind,
1225     const Symbol &specific, const Procedure &proc) {
1226   if (context_.HasError(specific)) {
1227     return false;
1228   }
1229   std::optional<parser::MessageFixedText> msg;
1230   auto checkDefinedOperatorArgs{
1231       [&](SourceName opName, const Symbol &specific, const Procedure &proc) {
1232         bool arg0Defined{CheckDefinedOperatorArg(opName, specific, proc, 0)};
1233         bool arg1Defined{CheckDefinedOperatorArg(opName, specific, proc, 1)};
1234         return arg0Defined && arg1Defined;
1235       }};
1236   if (specific.attrs().test(Attr::NOPASS)) { // C774
1237     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
1238   } else if (!proc.functionResult.has_value()) {
1239     msg = "%s procedure '%s' must be a function"_err_en_US;
1240   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
1241     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
1242           " result"_err_en_US;
1243   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
1244     msg = std::move(m);
1245   } else if (!checkDefinedOperatorArgs(opName, specific, proc)) {
1246     return false; // error was reported
1247   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
1248     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
1249   } else {
1250     return true; // OK
1251   }
1252   SayWithDeclaration(
1253       specific, std::move(*msg), MakeOpName(opName), specific.name());
1254   context_.SetError(specific);
1255   return false;
1256 }
1257 
1258 // If the number of arguments is wrong for this intrinsic operator, return
1259 // false and return the error message in msg.
1260 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
1261     const GenericKind &kind, std::size_t nargs) {
1262   if (!kind.IsIntrinsicOperator()) {
1263     return std::nullopt;
1264   }
1265   std::size_t min{2}, max{2}; // allowed number of args; default is binary
1266   std::visit(common::visitors{
1267                  [&](const common::NumericOperator &x) {
1268                    if (x == common::NumericOperator::Add ||
1269                        x == common::NumericOperator::Subtract) {
1270                      min = 1; // + and - are unary or binary
1271                    }
1272                  },
1273                  [&](const common::LogicalOperator &x) {
1274                    if (x == common::LogicalOperator::Not) {
1275                      min = 1; // .NOT. is unary
1276                      max = 1;
1277                    }
1278                  },
1279                  [](const common::RelationalOperator &) {
1280                    // all are binary
1281                  },
1282                  [](const GenericKind::OtherKind &x) {
1283                    CHECK(x == GenericKind::OtherKind::Concat);
1284                  },
1285                  [](const auto &) { DIE("expected intrinsic operator"); },
1286              },
1287       kind.u);
1288   if (nargs >= min && nargs <= max) {
1289     return std::nullopt;
1290   } else if (max == 1) {
1291     return "%s function '%s' must have one dummy argument"_err_en_US;
1292   } else if (min == 2) {
1293     return "%s function '%s' must have two dummy arguments"_err_en_US;
1294   } else {
1295     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
1296   }
1297 }
1298 
1299 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
1300     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
1301   if (pos >= proc.dummyArguments.size()) {
1302     return true;
1303   }
1304   auto &arg{proc.dummyArguments.at(pos)};
1305   std::optional<parser::MessageFixedText> msg;
1306   if (arg.IsOptional()) {
1307     msg = "In %s function '%s', dummy argument '%s' may not be"
1308           " OPTIONAL"_err_en_US;
1309   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
1310              dataObject == nullptr) {
1311     msg = "In %s function '%s', dummy argument '%s' must be a"
1312           " data object"_err_en_US;
1313   } else if (dataObject->intent != common::Intent::In &&
1314       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1315     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
1316           " or VALUE attribute"_err_en_US;
1317   }
1318   if (msg) {
1319     SayWithDeclaration(symbol, std::move(*msg),
1320         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
1321     return false;
1322   }
1323   return true;
1324 }
1325 
1326 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
1327 bool CheckHelper::CheckDefinedAssignment(
1328     const Symbol &specific, const Procedure &proc) {
1329   if (context_.HasError(specific)) {
1330     return false;
1331   }
1332   std::optional<parser::MessageFixedText> msg;
1333   if (specific.attrs().test(Attr::NOPASS)) { // C774
1334     msg = "Defined assignment procedure '%s' may not have"
1335           " NOPASS attribute"_err_en_US;
1336   } else if (!proc.IsSubroutine()) {
1337     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
1338   } else if (proc.dummyArguments.size() != 2) {
1339     msg = "Defined assignment subroutine '%s' must have"
1340           " two dummy arguments"_err_en_US;
1341   } else {
1342     // Check both arguments even if the first has an error.
1343     bool ok0{CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0)};
1344     bool ok1{CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)};
1345     if (!(ok0 && ok1)) {
1346       return false; // error was reported
1347     } else if (ConflictsWithIntrinsicAssignment(proc)) {
1348       msg = "Defined assignment subroutine '%s' conflicts with"
1349             " intrinsic assignment"_err_en_US;
1350     } else {
1351       return true; // OK
1352     }
1353   }
1354   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
1355   context_.SetError(specific);
1356   return false;
1357 }
1358 
1359 bool CheckHelper::CheckDefinedAssignmentArg(
1360     const Symbol &symbol, const DummyArgument &arg, int pos) {
1361   std::optional<parser::MessageFixedText> msg;
1362   if (arg.IsOptional()) {
1363     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1364           " may not be OPTIONAL"_err_en_US;
1365   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
1366     if (pos == 0) {
1367       if (dataObject->intent != common::Intent::Out &&
1368           dataObject->intent != common::Intent::InOut) {
1369         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
1370               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
1371       }
1372     } else if (pos == 1) {
1373       if (dataObject->intent != common::Intent::In &&
1374           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1375         msg =
1376             "In defined assignment subroutine '%s', second dummy"
1377             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1378       }
1379     } else {
1380       DIE("pos must be 0 or 1");
1381     }
1382   } else {
1383     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1384           " must be a data object"_err_en_US;
1385   }
1386   if (msg) {
1387     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1388     context_.SetError(symbol);
1389     return false;
1390   }
1391   return true;
1392 }
1393 
1394 // Report a conflicting attribute error if symbol has both of these attributes
1395 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1396   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1397     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1398         symbol.name(), AttrToString(a1), AttrToString(a2));
1399     return true;
1400   } else {
1401     return false;
1402   }
1403 }
1404 
1405 void CheckHelper::WarnMissingFinal(const Symbol &symbol) {
1406   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
1407   if (!object || IsPointer(symbol)) {
1408     return;
1409   }
1410   const DeclTypeSpec *type{object->type()};
1411   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
1412   const Symbol *derivedSym{derived ? &derived->typeSymbol() : nullptr};
1413   int rank{object->shape().Rank()};
1414   const Symbol *initialDerivedSym{derivedSym};
1415   while (const auto *derivedDetails{
1416       derivedSym ? derivedSym->detailsIf<DerivedTypeDetails>() : nullptr}) {
1417     if (!derivedDetails->finals().empty() &&
1418         !derivedDetails->GetFinalForRank(rank)) {
1419       if (auto *msg{derivedSym == initialDerivedSym
1420                   ? messages_.Say(symbol.name(),
1421                         "'%s' of derived type '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1422                         symbol.name(), derivedSym->name(), rank)
1423                   : messages_.Say(symbol.name(),
1424                         "'%s' of derived type '%s' extended from '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1425                         symbol.name(), initialDerivedSym->name(),
1426                         derivedSym->name(), rank)}) {
1427         msg->Attach(derivedSym->name(),
1428             "Declaration of derived type '%s'"_en_US, derivedSym->name());
1429       }
1430       return;
1431     }
1432     derived = derivedSym->GetParentTypeSpec();
1433     derivedSym = derived ? &derived->typeSymbol() : nullptr;
1434   }
1435 }
1436 
1437 const Procedure *CheckHelper::Characterize(const Symbol &symbol) {
1438   auto it{characterizeCache_.find(symbol)};
1439   if (it == characterizeCache_.end()) {
1440     auto pair{characterizeCache_.emplace(SymbolRef{symbol},
1441         Procedure::Characterize(symbol, context_.foldingContext()))};
1442     it = pair.first;
1443   }
1444   return common::GetPtrFromOptional(it->second);
1445 }
1446 
1447 void CheckHelper::CheckVolatile(const Symbol &symbol,
1448     const DerivedTypeSpec *derived) { // C866 - C868
1449   if (IsIntentIn(symbol)) {
1450     messages_.Say(
1451         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1452   }
1453   if (IsProcedure(symbol)) {
1454     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1455   }
1456   if (symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()) {
1457     const Symbol &ultimate{symbol.GetUltimate()};
1458     if (evaluate::IsCoarray(ultimate)) {
1459       messages_.Say(
1460           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1461     }
1462     if (derived) {
1463       if (FindCoarrayUltimateComponent(*derived)) {
1464         messages_.Say(
1465             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1466       }
1467     }
1468   }
1469 }
1470 
1471 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1472   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1473   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1474   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1475   // Prohibit constant pointers.  The standard does not explicitly prohibit
1476   // them, but the PARAMETER attribute requires a entity-decl to have an
1477   // initialization that is a constant-expr, and the only form of
1478   // initialization that allows a constant-expr is the one that's not a "=>"
1479   // pointer initialization.  See C811, C807, and section 8.5.13.
1480   CheckConflicting(symbol, Attr::POINTER, Attr::PARAMETER);
1481   if (symbol.Corank() > 0) {
1482     messages_.Say(
1483         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1484         symbol.name());
1485   }
1486 }
1487 
1488 // C760 constraints on the passed-object dummy argument
1489 // C757 constraints on procedure pointer components
1490 void CheckHelper::CheckPassArg(
1491     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1492   if (proc.attrs().test(Attr::NOPASS)) {
1493     return;
1494   }
1495   const auto &name{proc.name()};
1496   if (!interface) {
1497     messages_.Say(name,
1498         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1499         name);
1500     return;
1501   }
1502   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1503   if (!subprogram) {
1504     messages_.Say(name,
1505         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1506         interface->name());
1507     return;
1508   }
1509   std::optional<SourceName> passName{details.passName()};
1510   const auto &dummyArgs{subprogram->dummyArgs()};
1511   if (!passName) {
1512     if (dummyArgs.empty()) {
1513       messages_.Say(name,
1514           proc.has<ProcEntityDetails>()
1515               ? "Procedure component '%s' with no dummy arguments"
1516                 " must have NOPASS attribute"_err_en_US
1517               : "Procedure binding '%s' with no dummy arguments"
1518                 " must have NOPASS attribute"_err_en_US,
1519           name);
1520       context_.SetError(*interface);
1521       return;
1522     }
1523     Symbol *argSym{dummyArgs[0]};
1524     if (!argSym) {
1525       messages_.Say(interface->name(),
1526           "Cannot use an alternate return as the passed-object dummy "
1527           "argument"_err_en_US);
1528       return;
1529     }
1530     passName = dummyArgs[0]->name();
1531   }
1532   std::optional<int> passArgIndex{};
1533   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1534     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1535       passArgIndex = i;
1536       break;
1537     }
1538   }
1539   if (!passArgIndex) { // C758
1540     messages_.Say(*passName,
1541         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1542         *passName, interface->name());
1543     return;
1544   }
1545   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1546   std::optional<parser::MessageFixedText> msg;
1547   if (!passArg.has<ObjectEntityDetails>()) {
1548     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1549           " must be a data object"_err_en_US;
1550   } else if (passArg.attrs().test(Attr::POINTER)) {
1551     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1552           " may not have the POINTER attribute"_err_en_US;
1553   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1554     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1555           " may not have the ALLOCATABLE attribute"_err_en_US;
1556   } else if (passArg.attrs().test(Attr::VALUE)) {
1557     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1558           " may not have the VALUE attribute"_err_en_US;
1559   } else if (passArg.Rank() > 0) {
1560     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1561           " must be scalar"_err_en_US;
1562   }
1563   if (msg) {
1564     messages_.Say(name, std::move(*msg), passName.value(), name);
1565     return;
1566   }
1567   const DeclTypeSpec *type{passArg.GetType()};
1568   if (!type) {
1569     return; // an error already occurred
1570   }
1571   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1572   const DerivedTypeSpec *derived{type->AsDerived()};
1573   if (!derived || derived->typeSymbol() != typeSymbol) {
1574     messages_.Say(name,
1575         "Passed-object dummy argument '%s' of procedure '%s'"
1576         " must be of type '%s' but is '%s'"_err_en_US,
1577         passName.value(), name, typeSymbol.name(), type->AsFortran());
1578     return;
1579   }
1580   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1581     messages_.Say(name,
1582         type->IsPolymorphic()
1583             ? "Passed-object dummy argument '%s' of procedure '%s'"
1584               " may not be polymorphic because '%s' is not extensible"_err_en_US
1585             : "Passed-object dummy argument '%s' of procedure '%s'"
1586               " must be polymorphic because '%s' is extensible"_err_en_US,
1587         passName.value(), name, typeSymbol.name());
1588     return;
1589   }
1590   for (const auto &[paramName, paramValue] : derived->parameters()) {
1591     if (paramValue.isLen() && !paramValue.isAssumed()) {
1592       messages_.Say(name,
1593           "Passed-object dummy argument '%s' of procedure '%s'"
1594           " has non-assumed length parameter '%s'"_err_en_US,
1595           passName.value(), name, paramName);
1596     }
1597   }
1598 }
1599 
1600 void CheckHelper::CheckProcBinding(
1601     const Symbol &symbol, const ProcBindingDetails &binding) {
1602   const Scope &dtScope{symbol.owner()};
1603   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1604   if (symbol.attrs().test(Attr::DEFERRED)) {
1605     if (const Symbol * dtSymbol{dtScope.symbol()}) {
1606       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1607         SayWithDeclaration(*dtSymbol,
1608             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1609             dtSymbol->name());
1610       }
1611     }
1612     if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1613       messages_.Say(
1614           "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1615           symbol.name());
1616     }
1617   }
1618   if (binding.symbol().attrs().test(Attr::INTRINSIC) &&
1619       !context_.intrinsics().IsSpecificIntrinsicFunction(
1620           binding.symbol().name().ToString())) {
1621     messages_.Say(
1622         "Intrinsic procedure '%s' is not a specific intrinsic permitted for use in the definition of binding '%s'"_err_en_US,
1623         binding.symbol().name(), symbol.name());
1624   }
1625   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1626     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1627       SayWithDeclaration(*overridden,
1628           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1629           symbol.name());
1630     }
1631     if (const auto *overriddenBinding{
1632             overridden->detailsIf<ProcBindingDetails>()}) {
1633       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1634         SayWithDeclaration(*overridden,
1635             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1636         return;
1637       }
1638       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1639           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1640         SayWithDeclaration(*overridden,
1641             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1642         return;
1643       }
1644       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1645       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1646         SayWithDeclaration(*overridden,
1647             isNopass
1648                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1649                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1650       } else {
1651         const auto *bindingChars{Characterize(binding.symbol())};
1652         const auto *overriddenChars{Characterize(overriddenBinding->symbol())};
1653         if (bindingChars && overriddenChars) {
1654           if (isNopass) {
1655             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1656               SayWithDeclaration(*overridden,
1657                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1658             }
1659           } else if (!context_.HasError(binding.symbol())) {
1660             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1661             int overriddenPassIndex{
1662                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1663             if (passIndex != overriddenPassIndex) {
1664               SayWithDeclaration(*overridden,
1665                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1666             } else if (!bindingChars->CanOverride(
1667                            *overriddenChars, passIndex)) {
1668               SayWithDeclaration(*overridden,
1669                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1670             }
1671           }
1672         }
1673       }
1674       if (symbol.attrs().test(Attr::PRIVATE) &&
1675           overridden->attrs().test(Attr::PUBLIC)) {
1676         SayWithDeclaration(*overridden,
1677             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1678       }
1679     } else {
1680       SayWithDeclaration(*overridden,
1681           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1682     }
1683   }
1684   CheckPassArg(symbol, &binding.symbol(), binding);
1685 }
1686 
1687 void CheckHelper::Check(const Scope &scope) {
1688   scope_ = &scope;
1689   common::Restorer<const Symbol *> restorer{innermostSymbol_, innermostSymbol_};
1690   if (const Symbol * symbol{scope.symbol()}) {
1691     innermostSymbol_ = symbol;
1692   }
1693   if (scope.IsParameterizedDerivedTypeInstantiation()) {
1694     auto restorer{common::ScopedSet(scopeIsUninstantiatedPDT_, false)};
1695     auto restorer2{context_.foldingContext().messages().SetContext(
1696         scope.instantiationContext().get())};
1697     for (const auto &pair : scope) {
1698       CheckPointerInitialization(*pair.second);
1699     }
1700   } else {
1701     auto restorer{common::ScopedSet(
1702         scopeIsUninstantiatedPDT_, scope.IsParameterizedDerivedType())};
1703     for (const auto &set : scope.equivalenceSets()) {
1704       CheckEquivalenceSet(set);
1705     }
1706     for (const auto &pair : scope) {
1707       Check(*pair.second);
1708     }
1709     for (const Scope &child : scope.children()) {
1710       Check(child);
1711     }
1712     if (scope.kind() == Scope::Kind::BlockData) {
1713       CheckBlockData(scope);
1714     }
1715     CheckGenericOps(scope);
1716   }
1717 }
1718 
1719 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1720   auto iter{
1721       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1722         return FindCommonBlockContaining(object.symbol) != nullptr;
1723       })};
1724   if (iter != set.end()) {
1725     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1726     for (auto &object : set) {
1727       if (&object != &*iter) {
1728         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1729           if (details->commonBlock()) {
1730             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1731               if (auto *msg{messages_.Say(object.symbol.name(),
1732                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1733                 msg->Attach(iter->symbol.name(),
1734                        "Other object in EQUIVALENCE set"_en_US)
1735                     .Attach(details->commonBlock()->name(),
1736                         "COMMON block containing '%s'"_en_US,
1737                         object.symbol.name())
1738                     .Attach(commonBlock.name(),
1739                         "COMMON block containing '%s'"_en_US,
1740                         iter->symbol.name());
1741               }
1742             }
1743           } else {
1744             // Mark all symbols in the equivalence set with the same COMMON
1745             // block to prevent spurious error messages about initialization
1746             // in BLOCK DATA outside COMMON
1747             details->set_commonBlock(commonBlock);
1748           }
1749         }
1750       }
1751     }
1752   }
1753   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1754 }
1755 
1756 void CheckHelper::CheckBlockData(const Scope &scope) {
1757   // BLOCK DATA subprograms should contain only named common blocks.
1758   // C1415 presents a list of statements that shouldn't appear in
1759   // BLOCK DATA, but so long as the subprogram contains no executable
1760   // code and allocates no storage outside named COMMON, we're happy
1761   // (e.g., an ENUM is strictly not allowed).
1762   for (const auto &pair : scope) {
1763     const Symbol &symbol{*pair.second};
1764     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1765             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1766             symbol.has<SubprogramDetails>() ||
1767             symbol.has<ObjectEntityDetails>() ||
1768             (symbol.has<ProcEntityDetails>() &&
1769                 !symbol.attrs().test(Attr::POINTER)))) {
1770       messages_.Say(symbol.name(),
1771           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1772           symbol.name());
1773     }
1774   }
1775 }
1776 
1777 // Check distinguishability of generic assignment and operators.
1778 // For these, generics and generic bindings must be considered together.
1779 void CheckHelper::CheckGenericOps(const Scope &scope) {
1780   DistinguishabilityHelper helper{context_};
1781   auto addSpecifics{[&](const Symbol &generic) {
1782     const auto *details{generic.GetUltimate().detailsIf<GenericDetails>()};
1783     if (!details) {
1784       return;
1785     }
1786     GenericKind kind{details->kind()};
1787     if (!kind.IsAssignment() && !kind.IsOperator()) {
1788       return;
1789     }
1790     const SymbolVector &specifics{details->specificProcs()};
1791     const std::vector<SourceName> &bindingNames{details->bindingNames()};
1792     for (std::size_t i{0}; i < specifics.size(); ++i) {
1793       const Symbol &specific{*specifics[i]};
1794       if (const Procedure * proc{Characterize(specific)}) {
1795         auto restorer{messages_.SetLocation(bindingNames[i])};
1796         if (kind.IsAssignment()) {
1797           if (!CheckDefinedAssignment(specific, *proc)) {
1798             continue;
1799           }
1800         } else {
1801           if (!CheckDefinedOperator(generic.name(), kind, specific, *proc)) {
1802             continue;
1803           }
1804         }
1805         helper.Add(generic, kind, specific, *proc);
1806       }
1807     }
1808   }};
1809   for (const auto &pair : scope) {
1810     const Symbol &symbol{*pair.second};
1811     addSpecifics(symbol);
1812     const Symbol &ultimate{symbol.GetUltimate()};
1813     if (ultimate.has<DerivedTypeDetails>()) {
1814       if (const Scope * typeScope{ultimate.scope()}) {
1815         for (const auto &pair2 : *typeScope) {
1816           addSpecifics(*pair2.second);
1817         }
1818       }
1819     }
1820   }
1821   helper.Check(scope);
1822 }
1823 
1824 static const std::string *DefinesBindCName(const Symbol &symbol) {
1825   const auto *subp{symbol.detailsIf<SubprogramDetails>()};
1826   if ((subp && !subp->isInterface()) || symbol.has<ObjectEntityDetails>()) {
1827     // Symbol defines data or entry point
1828     return symbol.GetBindName();
1829   } else {
1830     return nullptr;
1831   }
1832 }
1833 
1834 // Check that BIND(C) names are distinct
1835 void CheckHelper::CheckBindCName(const Symbol &symbol) {
1836   if (const std::string * name{DefinesBindCName(symbol)}) {
1837     auto pair{bindC_.emplace(*name, symbol)};
1838     if (!pair.second) {
1839       const Symbol &other{*pair.first->second};
1840       if (DefinesBindCName(other) && !context_.HasError(other)) {
1841         if (auto *msg{messages_.Say(
1842                 "Two symbols have the same BIND(C) name '%s'"_err_en_US,
1843                 *name)}) {
1844           msg->Attach(other.name(), "Conflicting symbol"_en_US);
1845         }
1846         context_.SetError(symbol);
1847         context_.SetError(other);
1848       }
1849     }
1850   }
1851 }
1852 
1853 bool CheckHelper::CheckDioDummyIsData(
1854     const Symbol &subp, const Symbol *arg, std::size_t position) {
1855   if (arg && arg->detailsIf<ObjectEntityDetails>()) {
1856     return true;
1857   } else {
1858     if (arg) {
1859       messages_.Say(arg->name(),
1860           "Dummy argument '%s' must be a data object"_err_en_US, arg->name());
1861     } else {
1862       messages_.Say(subp.name(),
1863           "Dummy argument %d of '%s' must be a data object"_err_en_US, position,
1864           subp.name());
1865     }
1866     return false;
1867   }
1868 }
1869 
1870 void CheckHelper::CheckAlreadySeenDefinedIo(const DerivedTypeSpec *derivedType,
1871     GenericKind::DefinedIo ioKind, const Symbol &proc) {
1872   for (TypeWithDefinedIo definedIoType : seenDefinedIoTypes_) {
1873     if (*derivedType == *definedIoType.type && ioKind == definedIoType.ioKind &&
1874         proc != definedIoType.proc) {
1875       SayWithDeclaration(proc, definedIoType.proc.name(),
1876           "Derived type '%s' already has defined input/output procedure"
1877           " '%s'"_err_en_US,
1878           derivedType->name(),
1879           parser::ToUpperCaseLetters(GenericKind::EnumToString(ioKind)));
1880       return;
1881     }
1882   }
1883   seenDefinedIoTypes_.emplace_back(
1884       TypeWithDefinedIo{derivedType, ioKind, proc});
1885 }
1886 
1887 void CheckHelper::CheckDioDummyIsDerived(
1888     const Symbol &subp, const Symbol &arg, GenericKind::DefinedIo ioKind) {
1889   if (const DeclTypeSpec * type{arg.GetType()}) {
1890     if (const DerivedTypeSpec * derivedType{type->AsDerived()}) {
1891       CheckAlreadySeenDefinedIo(derivedType, ioKind, subp);
1892       bool isPolymorphic{type->IsPolymorphic()};
1893       if (isPolymorphic != IsExtensibleType(derivedType)) {
1894         messages_.Say(arg.name(),
1895             "Dummy argument '%s' of a defined input/output procedure must be %s when the derived type is %s"_err_en_US,
1896             arg.name(), isPolymorphic ? "TYPE()" : "CLASS()",
1897             isPolymorphic ? "not extensible" : "extensible");
1898       }
1899     } else {
1900       messages_.Say(arg.name(),
1901           "Dummy argument '%s' of a defined input/output procedure must have a"
1902           " derived type"_err_en_US,
1903           arg.name());
1904     }
1905   }
1906 }
1907 
1908 void CheckHelper::CheckDioDummyIsDefaultInteger(
1909     const Symbol &subp, const Symbol &arg) {
1910   if (const DeclTypeSpec * type{arg.GetType()};
1911       type && type->IsNumeric(TypeCategory::Integer)) {
1912     if (const auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
1913         kind && *kind == context_.GetDefaultKind(TypeCategory::Integer)) {
1914       return;
1915     }
1916   }
1917   messages_.Say(arg.name(),
1918       "Dummy argument '%s' of a defined input/output procedure"
1919       " must be an INTEGER of default KIND"_err_en_US,
1920       arg.name());
1921 }
1922 
1923 void CheckHelper::CheckDioDummyIsScalar(const Symbol &subp, const Symbol &arg) {
1924   if (arg.Rank() > 0 || arg.Corank() > 0) {
1925     messages_.Say(arg.name(),
1926         "Dummy argument '%s' of a defined input/output procedure"
1927         " must be a scalar"_err_en_US,
1928         arg.name());
1929   }
1930 }
1931 
1932 void CheckHelper::CheckDioDtvArg(
1933     const Symbol &subp, const Symbol *arg, GenericKind::DefinedIo ioKind) {
1934   // Dtv argument looks like: dtv-type-spec, INTENT(INOUT) :: dtv
1935   if (CheckDioDummyIsData(subp, arg, 0)) {
1936     CheckDioDummyIsDerived(subp, *arg, ioKind);
1937     CheckDioDummyAttrs(subp, *arg,
1938         ioKind == GenericKind::DefinedIo::ReadFormatted ||
1939                 ioKind == GenericKind::DefinedIo::ReadUnformatted
1940             ? Attr::INTENT_INOUT
1941             : Attr::INTENT_IN);
1942   }
1943 }
1944 
1945 void CheckHelper::CheckDefaultIntegerArg(
1946     const Symbol &subp, const Symbol *arg, Attr intent) {
1947   // Argument looks like: INTEGER, INTENT(intent) :: arg
1948   if (CheckDioDummyIsData(subp, arg, 1)) {
1949     CheckDioDummyIsDefaultInteger(subp, *arg);
1950     CheckDioDummyIsScalar(subp, *arg);
1951     CheckDioDummyAttrs(subp, *arg, intent);
1952   }
1953 }
1954 
1955 void CheckHelper::CheckDioAssumedLenCharacterArg(const Symbol &subp,
1956     const Symbol *arg, std::size_t argPosition, Attr intent) {
1957   // Argument looks like: CHARACTER (LEN=*), INTENT(intent) :: (iotype OR iomsg)
1958   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1959     CheckDioDummyAttrs(subp, *arg, intent);
1960     if (!IsAssumedLengthCharacter(*arg)) {
1961       messages_.Say(arg->name(),
1962           "Dummy argument '%s' of a defined input/output procedure"
1963           " must be assumed-length CHARACTER"_err_en_US,
1964           arg->name());
1965     }
1966   }
1967 }
1968 
1969 void CheckHelper::CheckDioVlistArg(
1970     const Symbol &subp, const Symbol *arg, std::size_t argPosition) {
1971   // Vlist argument looks like: INTEGER, INTENT(IN) :: v_list(:)
1972   if (CheckDioDummyIsData(subp, arg, argPosition)) {
1973     CheckDioDummyIsDefaultInteger(subp, *arg);
1974     CheckDioDummyAttrs(subp, *arg, Attr::INTENT_IN);
1975     const auto *objectDetails{arg->detailsIf<ObjectEntityDetails>()};
1976     if (!objectDetails || !objectDetails->shape().CanBeDeferredShape()) {
1977       messages_.Say(arg->name(),
1978           "Dummy argument '%s' of a defined input/output procedure must be"
1979           " deferred shape"_err_en_US,
1980           arg->name());
1981     }
1982   }
1983 }
1984 
1985 void CheckHelper::CheckDioArgCount(
1986     const Symbol &subp, GenericKind::DefinedIo ioKind, std::size_t argCount) {
1987   const std::size_t requiredArgCount{
1988       (std::size_t)(ioKind == GenericKind::DefinedIo::ReadFormatted ||
1989                   ioKind == GenericKind::DefinedIo::WriteFormatted
1990               ? 6
1991               : 4)};
1992   if (argCount != requiredArgCount) {
1993     SayWithDeclaration(subp,
1994         "Defined input/output procedure '%s' must have"
1995         " %d dummy arguments rather than %d"_err_en_US,
1996         subp.name(), requiredArgCount, argCount);
1997     context_.SetError(subp);
1998   }
1999 }
2000 
2001 void CheckHelper::CheckDioDummyAttrs(
2002     const Symbol &subp, const Symbol &arg, Attr goodIntent) {
2003   // Defined I/O procedures can't have attributes other than INTENT
2004   Attrs attrs{arg.attrs()};
2005   if (!attrs.test(goodIntent)) {
2006     messages_.Say(arg.name(),
2007         "Dummy argument '%s' of a defined input/output procedure"
2008         " must have intent '%s'"_err_en_US,
2009         arg.name(), AttrToString(goodIntent));
2010   }
2011   attrs = attrs - Attr::INTENT_IN - Attr::INTENT_OUT - Attr::INTENT_INOUT;
2012   if (!attrs.empty()) {
2013     messages_.Say(arg.name(),
2014         "Dummy argument '%s' of a defined input/output procedure may not have"
2015         " any attributes"_err_en_US,
2016         arg.name());
2017   }
2018 }
2019 
2020 // Enforce semantics for defined input/output procedures (12.6.4.8.2) and C777
2021 void CheckHelper::CheckDefinedIoProc(const Symbol &symbol,
2022     const GenericDetails &details, GenericKind::DefinedIo ioKind) {
2023   for (auto ref : details.specificProcs()) {
2024     const auto *binding{ref->detailsIf<ProcBindingDetails>()};
2025     const Symbol &specific{*(binding ? &binding->symbol() : &*ref)};
2026     if (ref->attrs().test(Attr::NOPASS)) { // C774
2027       messages_.Say("Defined input/output procedure '%s' may not have NOPASS "
2028                     "attribute"_err_en_US,
2029           ref->name());
2030       context_.SetError(*ref);
2031     }
2032     if (const auto *subpDetails{specific.detailsIf<SubprogramDetails>()}) {
2033       const std::vector<Symbol *> &dummyArgs{subpDetails->dummyArgs()};
2034       CheckDioArgCount(specific, ioKind, dummyArgs.size());
2035       int argCount{0};
2036       for (auto *arg : dummyArgs) {
2037         switch (argCount++) {
2038         case 0:
2039           // dtv-type-spec, INTENT(INOUT) :: dtv
2040           CheckDioDtvArg(specific, arg, ioKind);
2041           break;
2042         case 1:
2043           // INTEGER, INTENT(IN) :: unit
2044           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_IN);
2045           break;
2046         case 2:
2047           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2048               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2049             // CHARACTER (LEN=*), INTENT(IN) :: iotype
2050             CheckDioAssumedLenCharacterArg(
2051                 specific, arg, argCount, Attr::INTENT_IN);
2052           } else {
2053             // INTEGER, INTENT(OUT) :: iostat
2054             CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2055           }
2056           break;
2057         case 3:
2058           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2059               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2060             // INTEGER, INTENT(IN) :: v_list(:)
2061             CheckDioVlistArg(specific, arg, argCount);
2062           } else {
2063             // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2064             CheckDioAssumedLenCharacterArg(
2065                 specific, arg, argCount, Attr::INTENT_INOUT);
2066           }
2067           break;
2068         case 4:
2069           // INTEGER, INTENT(OUT) :: iostat
2070           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2071           break;
2072         case 5:
2073           // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2074           CheckDioAssumedLenCharacterArg(
2075               specific, arg, argCount, Attr::INTENT_INOUT);
2076           break;
2077         default:;
2078         }
2079       }
2080     }
2081   }
2082 }
2083 
2084 void SubprogramMatchHelper::Check(
2085     const Symbol &symbol1, const Symbol &symbol2) {
2086   const auto details1{symbol1.get<SubprogramDetails>()};
2087   const auto details2{symbol2.get<SubprogramDetails>()};
2088   if (details1.isFunction() != details2.isFunction()) {
2089     Say(symbol1, symbol2,
2090         details1.isFunction()
2091             ? "Module function '%s' was declared as a subroutine in the"
2092               " corresponding interface body"_err_en_US
2093             : "Module subroutine '%s' was declared as a function in the"
2094               " corresponding interface body"_err_en_US);
2095     return;
2096   }
2097   const auto &args1{details1.dummyArgs()};
2098   const auto &args2{details2.dummyArgs()};
2099   int nargs1{static_cast<int>(args1.size())};
2100   int nargs2{static_cast<int>(args2.size())};
2101   if (nargs1 != nargs2) {
2102     Say(symbol1, symbol2,
2103         "Module subprogram '%s' has %d args but the corresponding interface"
2104         " body has %d"_err_en_US,
2105         nargs1, nargs2);
2106     return;
2107   }
2108   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
2109   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
2110     Say(symbol1, symbol2,
2111         nonRecursive1
2112             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
2113               " the corresponding interface body does not"_err_en_US
2114             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
2115               "the corresponding interface body does"_err_en_US);
2116   }
2117   const std::string *bindName1{details1.bindName()};
2118   const std::string *bindName2{details2.bindName()};
2119   if (!bindName1 && !bindName2) {
2120     // OK - neither has a binding label
2121   } else if (!bindName1) {
2122     Say(symbol1, symbol2,
2123         "Module subprogram '%s' does not have a binding label but the"
2124         " corresponding interface body does"_err_en_US);
2125   } else if (!bindName2) {
2126     Say(symbol1, symbol2,
2127         "Module subprogram '%s' has a binding label but the"
2128         " corresponding interface body does not"_err_en_US);
2129   } else if (*bindName1 != *bindName2) {
2130     Say(symbol1, symbol2,
2131         "Module subprogram '%s' has binding label '%s' but the corresponding"
2132         " interface body has '%s'"_err_en_US,
2133         *details1.bindName(), *details2.bindName());
2134   }
2135   const Procedure *proc1{checkHelper.Characterize(symbol1)};
2136   const Procedure *proc2{checkHelper.Characterize(symbol2)};
2137   if (!proc1 || !proc2) {
2138     return;
2139   }
2140   if (proc1->functionResult && proc2->functionResult &&
2141       *proc1->functionResult != *proc2->functionResult) {
2142     Say(symbol1, symbol2,
2143         "Return type of function '%s' does not match return type of"
2144         " the corresponding interface body"_err_en_US);
2145   }
2146   for (int i{0}; i < nargs1; ++i) {
2147     const Symbol *arg1{args1[i]};
2148     const Symbol *arg2{args2[i]};
2149     if (arg1 && !arg2) {
2150       Say(symbol1, symbol2,
2151           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
2152           " but the corresponding argument in the interface body is"_err_en_US,
2153           i + 1);
2154     } else if (!arg1 && arg2) {
2155       Say(symbol1, symbol2,
2156           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
2157           " the corresponding argument in the interface body is not"_err_en_US,
2158           i + 1);
2159     } else if (arg1 && arg2) {
2160       SourceName name1{arg1->name()};
2161       SourceName name2{arg2->name()};
2162       if (name1 != name2) {
2163         Say(*arg1, *arg2,
2164             "Dummy argument name '%s' does not match corresponding name '%s'"
2165             " in interface body"_err_en_US,
2166             name2);
2167       } else {
2168         CheckDummyArg(
2169             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
2170       }
2171     }
2172   }
2173 }
2174 
2175 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
2176     const Symbol &symbol2, const DummyArgument &arg1,
2177     const DummyArgument &arg2) {
2178   std::visit(common::visitors{
2179                  [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
2180                    CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
2181                  },
2182                  [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
2183                    CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
2184                  },
2185                  [&](const DummyDataObject &, const auto &) {
2186                    Say(symbol1, symbol2,
2187                        "Dummy argument '%s' is a data object; the corresponding"
2188                        " argument in the interface body is not"_err_en_US);
2189                  },
2190                  [&](const DummyProcedure &, const auto &) {
2191                    Say(symbol1, symbol2,
2192                        "Dummy argument '%s' is a procedure; the corresponding"
2193                        " argument in the interface body is not"_err_en_US);
2194                  },
2195                  [&](const auto &, const auto &) {
2196                    llvm_unreachable("Dummy arguments are not data objects or"
2197                                     "procedures");
2198                  },
2199              },
2200       arg1.u, arg2.u);
2201 }
2202 
2203 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
2204     const Symbol &symbol2, const DummyDataObject &obj1,
2205     const DummyDataObject &obj2) {
2206   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
2207   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
2208   } else if (obj1.type.type() != obj2.type.type()) {
2209     Say(symbol1, symbol2,
2210         "Dummy argument '%s' has type %s; the corresponding argument in the"
2211         " interface body has type %s"_err_en_US,
2212         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
2213   } else if (!ShapesAreCompatible(obj1, obj2)) {
2214     Say(symbol1, symbol2,
2215         "The shape of dummy argument '%s' does not match the shape of the"
2216         " corresponding argument in the interface body"_err_en_US);
2217   }
2218   // TODO: coshape
2219 }
2220 
2221 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
2222     const Symbol &symbol2, const DummyProcedure &proc1,
2223     const DummyProcedure &proc2) {
2224   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
2225   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
2226   } else if (proc1 != proc2) {
2227     Say(symbol1, symbol2,
2228         "Dummy procedure '%s' does not match the corresponding argument in"
2229         " the interface body"_err_en_US);
2230   }
2231 }
2232 
2233 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
2234     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
2235   if (intent1 == intent2) {
2236     return true;
2237   } else {
2238     Say(symbol1, symbol2,
2239         "The intent of dummy argument '%s' does not match the intent"
2240         " of the corresponding argument in the interface body"_err_en_US);
2241     return false;
2242   }
2243 }
2244 
2245 // Report an error referring to first symbol with declaration of second symbol
2246 template <typename... A>
2247 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
2248     parser::MessageFixedText &&text, A &&...args) {
2249   auto &message{context().Say(symbol1.name(), std::move(text), symbol1.name(),
2250       std::forward<A>(args)...)};
2251   evaluate::AttachDeclaration(message, symbol2);
2252 }
2253 
2254 template <typename ATTRS>
2255 bool SubprogramMatchHelper::CheckSameAttrs(
2256     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
2257   if (attrs1 == attrs2) {
2258     return true;
2259   }
2260   attrs1.IterateOverMembers([&](auto attr) {
2261     if (!attrs2.test(attr)) {
2262       Say(symbol1, symbol2,
2263           "Dummy argument '%s' has the %s attribute; the corresponding"
2264           " argument in the interface body does not"_err_en_US,
2265           AsFortran(attr));
2266     }
2267   });
2268   attrs2.IterateOverMembers([&](auto attr) {
2269     if (!attrs1.test(attr)) {
2270       Say(symbol1, symbol2,
2271           "Dummy argument '%s' does not have the %s attribute; the"
2272           " corresponding argument in the interface body does"_err_en_US,
2273           AsFortran(attr));
2274     }
2275   });
2276   return false;
2277 }
2278 
2279 bool SubprogramMatchHelper::ShapesAreCompatible(
2280     const DummyDataObject &obj1, const DummyDataObject &obj2) {
2281   return characteristics::ShapesAreCompatible(
2282       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
2283 }
2284 
2285 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
2286   evaluate::Shape result;
2287   for (const auto &extent : shape) {
2288     result.emplace_back(
2289         evaluate::Fold(context().foldingContext(), common::Clone(extent)));
2290   }
2291   return result;
2292 }
2293 
2294 void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
2295     const Symbol &specific, const Procedure &procedure) {
2296   if (!context_.HasError(specific)) {
2297     nameToInfo_[generic.name()].emplace_back(
2298         ProcedureInfo{kind, specific, procedure});
2299   }
2300 }
2301 
2302 void DistinguishabilityHelper::Check(const Scope &scope) {
2303   for (const auto &[name, info] : nameToInfo_) {
2304     auto count{info.size()};
2305     for (std::size_t i1{0}; i1 < count - 1; ++i1) {
2306       const auto &[kind, symbol, proc]{info[i1]};
2307       for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
2308         auto distinguishable{kind.IsName()
2309                 ? evaluate::characteristics::Distinguishable
2310                 : evaluate::characteristics::DistinguishableOpOrAssign};
2311         if (!distinguishable(
2312                 context_.languageFeatures(), proc, info[i2].procedure)) {
2313           SayNotDistinguishable(GetTopLevelUnitContaining(scope), name, kind,
2314               symbol, info[i2].symbol);
2315         }
2316       }
2317     }
2318   }
2319 }
2320 
2321 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
2322     const SourceName &name, GenericKind kind, const Symbol &proc1,
2323     const Symbol &proc2) {
2324   std::string name1{proc1.name().ToString()};
2325   std::string name2{proc2.name().ToString()};
2326   if (kind.IsOperator() || kind.IsAssignment()) {
2327     // proc1 and proc2 may come from different scopes so qualify their names
2328     if (proc1.owner().IsDerivedType()) {
2329       name1 = proc1.owner().GetName()->ToString() + '%' + name1;
2330     }
2331     if (proc2.owner().IsDerivedType()) {
2332       name2 = proc2.owner().GetName()->ToString() + '%' + name2;
2333     }
2334   }
2335   parser::Message *msg;
2336   if (scope.sourceRange().Contains(name)) {
2337     msg = &context_.Say(name,
2338         "Generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2339         MakeOpName(name), name1, name2);
2340   } else {
2341     msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
2342         "USE-associated generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2343         MakeOpName(name), name1, name2);
2344   }
2345   AttachDeclaration(*msg, scope, proc1);
2346   AttachDeclaration(*msg, scope, proc2);
2347 }
2348 
2349 // `evaluate::AttachDeclaration` doesn't handle the generic case where `proc`
2350 // comes from a different module but is not necessarily use-associated.
2351 void DistinguishabilityHelper::AttachDeclaration(
2352     parser::Message &msg, const Scope &scope, const Symbol &proc) {
2353   const Scope &unit{GetTopLevelUnitContaining(proc)};
2354   if (unit == scope) {
2355     evaluate::AttachDeclaration(msg, proc);
2356   } else {
2357     msg.Attach(unit.GetName().value(),
2358         "'%s' is USE-associated from module '%s'"_en_US, proc.name(),
2359         unit.GetName().value());
2360   }
2361 }
2362 
2363 void CheckDeclarations(SemanticsContext &context) {
2364   CheckHelper{context}.Check();
2365 }
2366 } // namespace Fortran::semantics
2367