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 InFunction() const {
94     return innermostSymbol_ && IsFunction(*innermostSymbol_);
95   }
96   template <typename... A>
97   void SayWithDeclaration(const Symbol &symbol, A &&...x) {
98     if (parser::Message * msg{messages_.Say(std::forward<A>(x)...)}) {
99       if (messages_.at().begin() != symbol.name().begin()) {
100         evaluate::AttachDeclaration(*msg, symbol);
101       }
102     }
103   }
104   bool IsResultOkToDiffer(const FunctionResult &);
105   void CheckBindCName(const Symbol &);
106 
107   SemanticsContext &context_;
108   evaluate::FoldingContext &foldingContext_{context_.foldingContext()};
109   parser::ContextualMessages &messages_{foldingContext_.messages()};
110   const Scope *scope_{nullptr};
111   bool scopeIsUninstantiatedPDT_{false};
112   // This symbol is the one attached to the innermost enclosing scope
113   // that has a symbol.
114   const Symbol *innermostSymbol_{nullptr};
115   // Cache of calls to Procedure::Characterize(Symbol)
116   std::map<SymbolRef, std::optional<Procedure>, SymbolAddressCompare>
117       characterizeCache_;
118   // Collection of symbols with BIND(C) names
119   std::map<std::string, SymbolRef> bindC_;
120 };
121 
122 class DistinguishabilityHelper {
123 public:
124   DistinguishabilityHelper(SemanticsContext &context) : context_{context} {}
125   void Add(const Symbol &, GenericKind, const Symbol &, const Procedure &);
126   void Check(const Scope &);
127 
128 private:
129   void SayNotDistinguishable(const Scope &, const SourceName &, GenericKind,
130       const Symbol &, const Symbol &);
131   void AttachDeclaration(parser::Message &, const Scope &, const Symbol &);
132 
133   SemanticsContext &context_;
134   struct ProcedureInfo {
135     GenericKind kind;
136     const Symbol &symbol;
137     const Procedure &procedure;
138   };
139   std::map<SourceName, std::vector<ProcedureInfo>> nameToInfo_;
140 };
141 
142 void CheckHelper::Check(const ParamValue &value, bool canBeAssumed) {
143   if (value.isAssumed()) {
144     if (!canBeAssumed) { // C795, C721, C726
145       messages_.Say(
146           "An assumed (*) type parameter may be used only for a (non-statement"
147           " function) dummy argument, associate name, named constant, or"
148           " external function result"_err_en_US);
149     }
150   } else {
151     CheckSpecExpr(value.GetExplicit());
152   }
153 }
154 
155 void CheckHelper::Check(const ArraySpec &shape) {
156   for (const auto &spec : shape) {
157     Check(spec);
158   }
159 }
160 
161 void CheckHelper::Check(
162     const DeclTypeSpec &type, bool canHaveAssumedTypeParameters) {
163   if (type.category() == DeclTypeSpec::Character) {
164     Check(type.characterTypeSpec().length(), canHaveAssumedTypeParameters);
165   } else if (const DerivedTypeSpec * derived{type.AsDerived()}) {
166     for (auto &parm : derived->parameters()) {
167       Check(parm.second, canHaveAssumedTypeParameters);
168     }
169   }
170 }
171 
172 void CheckHelper::Check(const Symbol &symbol) {
173   if (context_.HasError(symbol)) {
174     return;
175   }
176   auto restorer{messages_.SetLocation(symbol.name())};
177   context_.set_location(symbol.name());
178   const DeclTypeSpec *type{symbol.GetType()};
179   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
180   bool isDone{false};
181   std::visit(
182       common::visitors{
183           [&](const UseDetails &x) { isDone = true; },
184           [&](const HostAssocDetails &x) {
185             CheckHostAssoc(symbol, x);
186             isDone = true;
187           },
188           [&](const ProcBindingDetails &x) {
189             CheckProcBinding(symbol, x);
190             isDone = true;
191           },
192           [&](const ObjectEntityDetails &x) { CheckObjectEntity(symbol, x); },
193           [&](const ProcEntityDetails &x) { CheckProcEntity(symbol, x); },
194           [&](const SubprogramDetails &x) { CheckSubprogram(symbol, x); },
195           [&](const DerivedTypeDetails &x) { CheckDerivedType(symbol, x); },
196           [&](const GenericDetails &x) { CheckGeneric(symbol, x); },
197           [](const auto &) {},
198       },
199       symbol.details());
200   if (symbol.attrs().test(Attr::VOLATILE)) {
201     CheckVolatile(symbol, derived);
202   }
203   CheckBindCName(symbol);
204   if (isDone) {
205     return; // following checks do not apply
206   }
207   if (IsPointer(symbol)) {
208     CheckPointer(symbol);
209   }
210   if (InPure()) {
211     if (IsSaved(symbol)) {
212       messages_.Say(
213           "A pure subprogram may not have a variable with the SAVE attribute"_err_en_US);
214     }
215     if (symbol.attrs().test(Attr::VOLATILE)) {
216       messages_.Say(
217           "A pure subprogram may not have a variable with the VOLATILE attribute"_err_en_US);
218     }
219     if (IsProcedure(symbol) && !IsPureProcedure(symbol) && IsDummy(symbol)) {
220       messages_.Say(
221           "A dummy procedure of a pure subprogram must be pure"_err_en_US);
222     }
223     if (!IsDummy(symbol) && !IsFunctionResult(symbol)) {
224       if (IsPolymorphicAllocatable(symbol)) {
225         SayWithDeclaration(symbol,
226             "Deallocation of polymorphic object '%s' is not permitted in a pure subprogram"_err_en_US,
227             symbol.name());
228       } else if (derived) {
229         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
230           SayWithDeclaration(*bad,
231               "Deallocation of polymorphic object '%s%s' is not permitted in a pure subprogram"_err_en_US,
232               symbol.name(), bad.BuildResultDesignatorName());
233         }
234       }
235     }
236   }
237   if (type) { // Section 7.2, paragraph 7
238     bool canHaveAssumedParameter{IsNamedConstant(symbol) ||
239         (IsAssumedLengthCharacter(symbol) && // C722
240             IsExternal(symbol)) ||
241         symbol.test(Symbol::Flag::ParentComp)};
242     if (!IsStmtFunctionDummy(symbol)) { // C726
243       if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
244         canHaveAssumedParameter |= object->isDummy() ||
245             (object->isFuncResult() &&
246                 type->category() == DeclTypeSpec::Character) ||
247             IsStmtFunctionResult(symbol); // Avoids multiple messages
248       } else {
249         canHaveAssumedParameter |= symbol.has<AssocEntityDetails>();
250       }
251     }
252     Check(*type, canHaveAssumedParameter);
253     if (InPure() && InFunction() && IsFunctionResult(symbol)) {
254       if (derived && HasImpureFinal(*derived)) { // C1584
255         messages_.Say(
256             "Result of pure function may not have an impure FINAL subroutine"_err_en_US);
257       }
258       if (type->IsPolymorphic() && IsAllocatable(symbol)) { // C1585
259         messages_.Say(
260             "Result of pure function may not be both polymorphic and ALLOCATABLE"_err_en_US);
261       }
262       if (derived) {
263         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
264           SayWithDeclaration(*bad,
265               "Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%s'"_err_en_US,
266               bad.BuildResultDesignatorName());
267         }
268       }
269     }
270   }
271   if (IsAssumedLengthCharacter(symbol) && IsExternal(symbol)) { // C723
272     if (symbol.attrs().test(Attr::RECURSIVE)) {
273       messages_.Say(
274           "An assumed-length CHARACTER(*) function cannot be RECURSIVE"_err_en_US);
275     }
276     if (symbol.Rank() > 0) {
277       messages_.Say(
278           "An assumed-length CHARACTER(*) function cannot return an array"_err_en_US);
279     }
280     if (symbol.attrs().test(Attr::PURE)) {
281       messages_.Say(
282           "An assumed-length CHARACTER(*) function cannot be PURE"_err_en_US);
283     }
284     if (symbol.attrs().test(Attr::ELEMENTAL)) {
285       messages_.Say(
286           "An assumed-length CHARACTER(*) function cannot be ELEMENTAL"_err_en_US);
287     }
288     if (const Symbol * result{FindFunctionResult(symbol)}) {
289       if (IsPointer(*result)) {
290         messages_.Say(
291             "An assumed-length CHARACTER(*) function cannot return a POINTER"_err_en_US);
292       }
293     }
294   }
295   if (symbol.attrs().test(Attr::VALUE)) {
296     CheckValue(symbol, derived);
297   }
298   if (symbol.attrs().test(Attr::CONTIGUOUS) && IsPointer(symbol) &&
299       symbol.Rank() == 0) { // C830
300     messages_.Say("CONTIGUOUS POINTER must be an array"_err_en_US);
301   }
302   if (IsDummy(symbol)) {
303     if (IsNamedConstant(symbol)) {
304       messages_.Say(
305           "A dummy argument may not also be a named constant"_err_en_US);
306     }
307     if (IsSaved(symbol)) {
308       messages_.Say(
309           "A dummy argument may not have the SAVE attribute"_err_en_US);
310     }
311   } else if (IsFunctionResult(symbol)) {
312     if (IsSaved(symbol)) {
313       messages_.Say(
314           "A function result may not have the SAVE attribute"_err_en_US);
315     }
316   }
317   if (symbol.owner().IsDerivedType() &&
318       (symbol.attrs().test(Attr::CONTIGUOUS) &&
319           !(IsPointer(symbol) && symbol.Rank() > 0))) { // C752
320     messages_.Say(
321         "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
322   }
323   if (symbol.owner().IsModule() && IsAutomatic(symbol)) {
324     messages_.Say(
325         "Automatic data object '%s' may not appear in the specification part"
326         " of a module"_err_en_US,
327         symbol.name());
328   }
329 }
330 
331 void CheckHelper::CheckValue(
332     const Symbol &symbol, const DerivedTypeSpec *derived) { // C863 - C865
333   if (!IsDummy(symbol)) {
334     messages_.Say(
335         "VALUE attribute may apply only to a dummy argument"_err_en_US);
336   }
337   if (IsProcedure(symbol)) {
338     messages_.Say(
339         "VALUE attribute may apply only to a dummy data object"_err_en_US);
340   }
341   if (IsAssumedSizeArray(symbol)) {
342     messages_.Say(
343         "VALUE attribute may not apply to an assumed-size array"_err_en_US);
344   }
345   if (IsCoarray(symbol)) {
346     messages_.Say("VALUE attribute may not apply to a coarray"_err_en_US);
347   }
348   if (IsAllocatable(symbol)) {
349     messages_.Say("VALUE attribute may not apply to an ALLOCATABLE"_err_en_US);
350   } else if (IsPointer(symbol)) {
351     messages_.Say("VALUE attribute may not apply to a POINTER"_err_en_US);
352   }
353   if (IsIntentInOut(symbol)) {
354     messages_.Say(
355         "VALUE attribute may not apply to an INTENT(IN OUT) argument"_err_en_US);
356   } else if (IsIntentOut(symbol)) {
357     messages_.Say(
358         "VALUE attribute may not apply to an INTENT(OUT) argument"_err_en_US);
359   }
360   if (symbol.attrs().test(Attr::VOLATILE)) {
361     messages_.Say("VALUE attribute may not apply to a VOLATILE"_err_en_US);
362   }
363   if (innermostSymbol_ && IsBindCProcedure(*innermostSymbol_) &&
364       IsOptional(symbol)) {
365     messages_.Say(
366         "VALUE attribute may not apply to an OPTIONAL in a BIND(C) procedure"_err_en_US);
367   }
368   if (derived) {
369     if (FindCoarrayUltimateComponent(*derived)) {
370       messages_.Say(
371           "VALUE attribute may not apply to a type with a coarray ultimate component"_err_en_US);
372     }
373   }
374 }
375 
376 void CheckHelper::CheckAssumedTypeEntity( // C709
377     const Symbol &symbol, const ObjectEntityDetails &details) {
378   if (const DeclTypeSpec * type{symbol.GetType()};
379       type && type->category() == DeclTypeSpec::TypeStar) {
380     if (!IsDummy(symbol)) {
381       messages_.Say(
382           "Assumed-type entity '%s' must be a dummy argument"_err_en_US,
383           symbol.name());
384     } else {
385       if (symbol.attrs().test(Attr::ALLOCATABLE)) {
386         messages_.Say("Assumed-type argument '%s' cannot have the ALLOCATABLE"
387                       " attribute"_err_en_US,
388             symbol.name());
389       }
390       if (symbol.attrs().test(Attr::POINTER)) {
391         messages_.Say("Assumed-type argument '%s' cannot have the POINTER"
392                       " attribute"_err_en_US,
393             symbol.name());
394       }
395       if (symbol.attrs().test(Attr::VALUE)) {
396         messages_.Say("Assumed-type argument '%s' cannot have the VALUE"
397                       " attribute"_err_en_US,
398             symbol.name());
399       }
400       if (symbol.attrs().test(Attr::INTENT_OUT)) {
401         messages_.Say(
402             "Assumed-type argument '%s' cannot be INTENT(OUT)"_err_en_US,
403             symbol.name());
404       }
405       if (IsCoarray(symbol)) {
406         messages_.Say(
407             "Assumed-type argument '%s' cannot be a coarray"_err_en_US,
408             symbol.name());
409       }
410       if (details.IsArray() && details.shape().IsExplicitShape()) {
411         messages_.Say(
412             "Assumed-type array argument 'arg8' must be assumed shape,"
413             " assumed size, or assumed rank"_err_en_US,
414             symbol.name());
415       }
416     }
417   }
418 }
419 
420 void CheckHelper::CheckObjectEntity(
421     const Symbol &symbol, const ObjectEntityDetails &details) {
422   CheckArraySpec(symbol, details.shape());
423   Check(details.shape());
424   Check(details.coshape());
425   CheckAssumedTypeEntity(symbol, details);
426   WarnMissingFinal(symbol);
427   if (!details.coshape().empty()) {
428     bool isDeferredShape{details.coshape().IsDeferredShape()};
429     if (IsAllocatable(symbol)) {
430       if (!isDeferredShape) { // C827
431         messages_.Say("'%s' is an ALLOCATABLE coarray and must have a deferred"
432                       " coshape"_err_en_US,
433             symbol.name());
434       }
435     } else if (symbol.owner().IsDerivedType()) { // C746
436       std::string deferredMsg{
437           isDeferredShape ? "" : " and have a deferred coshape"};
438       messages_.Say("Component '%s' is a coarray and must have the ALLOCATABLE"
439                     " attribute%s"_err_en_US,
440           symbol.name(), deferredMsg);
441     } else {
442       if (!details.coshape().IsAssumedSize()) { // C828
443         messages_.Say(
444             "Component '%s' is a non-ALLOCATABLE coarray and must have"
445             " an explicit coshape"_err_en_US,
446             symbol.name());
447       }
448     }
449   }
450   if (details.isDummy()) {
451     if (symbol.attrs().test(Attr::INTENT_OUT)) {
452       if (FindUltimateComponent(symbol, [](const Symbol &x) {
453             return IsCoarray(x) && IsAllocatable(x);
454           })) { // C846
455         messages_.Say(
456             "An INTENT(OUT) dummy argument may not be, or contain, an ALLOCATABLE coarray"_err_en_US);
457       }
458       if (IsOrContainsEventOrLockComponent(symbol)) { // C847
459         messages_.Say(
460             "An INTENT(OUT) dummy argument may not be, or contain, EVENT_TYPE or LOCK_TYPE"_err_en_US);
461       }
462     }
463     if (InPure() && !IsStmtFunction(DEREF(innermostSymbol_)) &&
464         !IsPointer(symbol) && !IsIntentIn(symbol) &&
465         !symbol.attrs().test(Attr::VALUE)) {
466       if (InFunction()) { // C1583
467         messages_.Say(
468             "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
469       } else if (IsIntentOut(symbol)) {
470         if (const DeclTypeSpec * type{details.type()}) {
471           if (type && type->IsPolymorphic()) { // C1588
472             messages_.Say(
473                 "An INTENT(OUT) dummy argument of a pure subroutine may not be polymorphic"_err_en_US);
474           } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
475             if (FindUltimateComponent(*derived, [](const Symbol &x) {
476                   const DeclTypeSpec *type{x.GetType()};
477                   return type && type->IsPolymorphic();
478                 })) { // C1588
479               messages_.Say(
480                   "An INTENT(OUT) dummy argument of a pure subroutine may not have a polymorphic ultimate component"_err_en_US);
481             }
482             if (HasImpureFinal(*derived)) { // C1587
483               messages_.Say(
484                   "An INTENT(OUT) dummy argument of a pure subroutine may not have an impure FINAL subroutine"_err_en_US);
485             }
486           }
487         }
488       } else if (!IsIntentInOut(symbol)) { // C1586
489         messages_.Say(
490             "non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute"_err_en_US);
491       }
492     }
493   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
494       symbol.attrs().test(Attr::INTENT_OUT) ||
495       symbol.attrs().test(Attr::INTENT_INOUT)) {
496     messages_.Say("INTENT attributes may apply only to a dummy "
497                   "argument"_err_en_US); // C843
498   } else if (IsOptional(symbol)) {
499     messages_.Say("OPTIONAL attribute may apply only to a dummy "
500                   "argument"_err_en_US); // C849
501   }
502   if (IsStaticallyInitialized(symbol, true /* ignore DATA inits */)) { // C808
503     CheckPointerInitialization(symbol);
504     if (IsAutomatic(symbol)) {
505       messages_.Say(
506           "An automatic variable or component must not be initialized"_err_en_US);
507     } else if (IsDummy(symbol)) {
508       messages_.Say("A dummy argument must not be initialized"_err_en_US);
509     } else if (IsFunctionResult(symbol)) {
510       messages_.Say("A function result must not be initialized"_err_en_US);
511     } else if (IsInBlankCommon(symbol)) {
512       messages_.Say(
513           "A variable in blank COMMON should not be initialized"_en_US);
514     }
515   }
516   if (symbol.owner().kind() == Scope::Kind::BlockData) {
517     if (IsAllocatable(symbol)) {
518       messages_.Say(
519           "An ALLOCATABLE variable may not appear in a BLOCK DATA subprogram"_err_en_US);
520     } else if (IsInitialized(symbol) && !FindCommonBlockContaining(symbol)) {
521       messages_.Say(
522           "An initialized variable in BLOCK DATA must be in a COMMON block"_err_en_US);
523     }
524   }
525   if (const DeclTypeSpec * type{details.type()}) { // C708
526     if (type->IsPolymorphic() &&
527         !(type->IsAssumedType() || IsAllocatableOrPointer(symbol) ||
528             IsDummy(symbol))) {
529       messages_.Say("CLASS entity '%s' must be a dummy argument or have "
530                     "ALLOCATABLE or POINTER attribute"_err_en_US,
531           symbol.name());
532     }
533   }
534 }
535 
536 void CheckHelper::CheckPointerInitialization(const Symbol &symbol) {
537   if (IsPointer(symbol) && !context_.HasError(symbol) &&
538       !scopeIsUninstantiatedPDT_) {
539     if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
540       if (object->init()) { // C764, C765; C808
541         if (auto dyType{evaluate::DynamicType::From(symbol)}) {
542           if (auto designator{evaluate::TypedWrapper<evaluate::Designator>(
543                   *dyType, evaluate::DataRef{symbol})}) {
544             auto restorer{messages_.SetLocation(symbol.name())};
545             context_.set_location(symbol.name());
546             CheckInitialTarget(foldingContext_, *designator, *object->init());
547           }
548         }
549       }
550     } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
551       if (proc->init() && *proc->init()) {
552         // C1519 - must be nonelemental external or module procedure,
553         // or an unrestricted specific intrinsic function.
554         const Symbol &ultimate{(*proc->init())->GetUltimate()};
555         if (ultimate.attrs().test(Attr::INTRINSIC)) {
556         } else if (!ultimate.attrs().test(Attr::EXTERNAL) &&
557             ultimate.owner().kind() != Scope::Kind::Module) {
558           context_.Say("Procedure pointer '%s' initializer '%s' is neither "
559                        "an external nor a module procedure"_err_en_US,
560               symbol.name(), ultimate.name());
561         } else if (ultimate.attrs().test(Attr::ELEMENTAL)) {
562           context_.Say("Procedure pointer '%s' cannot be initialized with the "
563                        "elemental procedure '%s"_err_en_US,
564               symbol.name(), ultimate.name());
565         } else {
566           // TODO: Check the "shalls" in the 15.4.3.6 paragraphs 7-10.
567         }
568       }
569     }
570   }
571 }
572 
573 // The six different kinds of array-specs:
574 //   array-spec     -> explicit-shape-list | deferred-shape-list
575 //                     | assumed-shape-list | implied-shape-list
576 //                     | assumed-size | assumed-rank
577 //   explicit-shape -> [ lb : ] ub
578 //   deferred-shape -> :
579 //   assumed-shape  -> [ lb ] :
580 //   implied-shape  -> [ lb : ] *
581 //   assumed-size   -> [ explicit-shape-list , ] [ lb : ] *
582 //   assumed-rank   -> ..
583 // Note:
584 // - deferred-shape is also an assumed-shape
585 // - A single "*" or "lb:*" might be assumed-size or implied-shape-list
586 void CheckHelper::CheckArraySpec(
587     const Symbol &symbol, const ArraySpec &arraySpec) {
588   if (arraySpec.Rank() == 0) {
589     return;
590   }
591   bool isExplicit{arraySpec.IsExplicitShape()};
592   bool isDeferred{arraySpec.IsDeferredShape()};
593   bool isImplied{arraySpec.IsImpliedShape()};
594   bool isAssumedShape{arraySpec.IsAssumedShape()};
595   bool isAssumedSize{arraySpec.IsAssumedSize()};
596   bool isAssumedRank{arraySpec.IsAssumedRank()};
597   std::optional<parser::MessageFixedText> msg;
598   if (symbol.test(Symbol::Flag::CrayPointee) && !isExplicit && !isAssumedSize) {
599     msg = "Cray pointee '%s' must have must have explicit shape or"
600           " assumed size"_err_en_US;
601   } else if (IsAllocatableOrPointer(symbol) && !isDeferred && !isAssumedRank) {
602     if (symbol.owner().IsDerivedType()) { // C745
603       if (IsAllocatable(symbol)) {
604         msg = "Allocatable array component '%s' must have"
605               " deferred shape"_err_en_US;
606       } else {
607         msg = "Array pointer component '%s' must have deferred shape"_err_en_US;
608       }
609     } else {
610       if (IsAllocatable(symbol)) { // C832
611         msg = "Allocatable array '%s' must have deferred shape or"
612               " assumed rank"_err_en_US;
613       } else {
614         msg = "Array pointer '%s' must have deferred shape or"
615               " assumed rank"_err_en_US;
616       }
617     }
618   } else if (IsDummy(symbol)) {
619     if (isImplied && !isAssumedSize) { // C836
620       msg = "Dummy array argument '%s' may not have implied shape"_err_en_US;
621     }
622   } else if (isAssumedShape && !isDeferred) {
623     msg = "Assumed-shape array '%s' must be a dummy argument"_err_en_US;
624   } else if (isAssumedSize && !isImplied) { // C833
625     msg = "Assumed-size array '%s' must be a dummy argument"_err_en_US;
626   } else if (isAssumedRank) { // C837
627     msg = "Assumed-rank array '%s' must be a dummy argument"_err_en_US;
628   } else if (isImplied) {
629     if (!IsNamedConstant(symbol)) { // C835, C836
630       msg = "Implied-shape array '%s' must be a named constant or a "
631             "dummy argument"_err_en_US;
632     }
633   } else if (IsNamedConstant(symbol)) {
634     if (!isExplicit && !isImplied) {
635       msg = "Named constant '%s' array must have constant or"
636             " implied shape"_err_en_US;
637     }
638   } else if (!IsAllocatableOrPointer(symbol) && !isExplicit) {
639     if (symbol.owner().IsDerivedType()) { // C749
640       msg = "Component array '%s' without ALLOCATABLE or POINTER attribute must"
641             " have explicit shape"_err_en_US;
642     } else { // C816
643       msg = "Array '%s' without ALLOCATABLE or POINTER attribute must have"
644             " explicit shape"_err_en_US;
645     }
646   }
647   if (msg) {
648     context_.Say(std::move(*msg), symbol.name());
649   }
650 }
651 
652 void CheckHelper::CheckProcEntity(
653     const Symbol &symbol, const ProcEntityDetails &details) {
654   if (details.isDummy()) {
655     if (!symbol.attrs().test(Attr::POINTER) && // C843
656         (symbol.attrs().test(Attr::INTENT_IN) ||
657             symbol.attrs().test(Attr::INTENT_OUT) ||
658             symbol.attrs().test(Attr::INTENT_INOUT))) {
659       messages_.Say("A dummy procedure without the POINTER attribute"
660                     " may not have an INTENT attribute"_err_en_US);
661     }
662 
663     const Symbol *interface{details.interface().symbol()};
664     if (!symbol.attrs().test(Attr::INTRINSIC) &&
665         (symbol.attrs().test(Attr::ELEMENTAL) ||
666             (interface && !interface->attrs().test(Attr::INTRINSIC) &&
667                 interface->attrs().test(Attr::ELEMENTAL)))) {
668       // There's no explicit constraint or "shall" that we can find in the
669       // standard for this check, but it seems to be implied in multiple
670       // sites, and ELEMENTAL non-intrinsic actual arguments *are*
671       // explicitly forbidden.  But we allow "PROCEDURE(SIN)::dummy"
672       // because it is explicitly legal to *pass* the specific intrinsic
673       // function SIN as an actual argument.
674       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
675     }
676   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
677       symbol.attrs().test(Attr::INTENT_OUT) ||
678       symbol.attrs().test(Attr::INTENT_INOUT)) {
679     messages_.Say("INTENT attributes may apply only to a dummy "
680                   "argument"_err_en_US); // C843
681   } else if (IsOptional(symbol)) {
682     messages_.Say("OPTIONAL attribute may apply only to a dummy "
683                   "argument"_err_en_US); // C849
684   } else if (symbol.owner().IsDerivedType()) {
685     if (!symbol.attrs().test(Attr::POINTER)) { // C756
686       const auto &name{symbol.name()};
687       messages_.Say(name,
688           "Procedure component '%s' must have POINTER attribute"_err_en_US,
689           name);
690     }
691     CheckPassArg(symbol, details.interface().symbol(), details);
692   }
693   if (symbol.attrs().test(Attr::POINTER)) {
694     CheckPointerInitialization(symbol);
695     if (const Symbol * interface{details.interface().symbol()}) {
696       if (interface->attrs().test(Attr::ELEMENTAL) &&
697           !interface->attrs().test(Attr::INTRINSIC)) {
698         messages_.Say("Procedure pointer '%s' may not be ELEMENTAL"_err_en_US,
699             symbol.name()); // C1517
700       }
701     }
702   } else if (symbol.attrs().test(Attr::SAVE)) {
703     messages_.Say(
704         "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US,
705         symbol.name());
706   }
707 }
708 
709 // When a module subprogram has the MODULE prefix the following must match
710 // with the corresponding separate module procedure interface body:
711 // - C1549: characteristics and dummy argument names
712 // - C1550: binding label
713 // - C1551: NON_RECURSIVE prefix
714 class SubprogramMatchHelper {
715 public:
716   explicit SubprogramMatchHelper(CheckHelper &checkHelper)
717       : checkHelper{checkHelper} {}
718 
719   void Check(const Symbol &, const Symbol &);
720 
721 private:
722   SemanticsContext &context() { return checkHelper.context(); }
723   void CheckDummyArg(const Symbol &, const Symbol &, const DummyArgument &,
724       const DummyArgument &);
725   void CheckDummyDataObject(const Symbol &, const Symbol &,
726       const DummyDataObject &, const DummyDataObject &);
727   void CheckDummyProcedure(const Symbol &, const Symbol &,
728       const DummyProcedure &, const DummyProcedure &);
729   bool CheckSameIntent(
730       const Symbol &, const Symbol &, common::Intent, common::Intent);
731   template <typename... A>
732   void Say(
733       const Symbol &, const Symbol &, parser::MessageFixedText &&, A &&...);
734   template <typename ATTRS>
735   bool CheckSameAttrs(const Symbol &, const Symbol &, ATTRS, ATTRS);
736   bool ShapesAreCompatible(const DummyDataObject &, const DummyDataObject &);
737   evaluate::Shape FoldShape(const evaluate::Shape &);
738   std::string AsFortran(DummyDataObject::Attr attr) {
739     return parser::ToUpperCaseLetters(DummyDataObject::EnumToString(attr));
740   }
741   std::string AsFortran(DummyProcedure::Attr attr) {
742     return parser::ToUpperCaseLetters(DummyProcedure::EnumToString(attr));
743   }
744 
745   CheckHelper &checkHelper;
746 };
747 
748 // 15.6.2.6 para 3 - can the result of an ENTRY differ from its function?
749 bool CheckHelper::IsResultOkToDiffer(const FunctionResult &result) {
750   if (result.attrs.test(FunctionResult::Attr::Allocatable) ||
751       result.attrs.test(FunctionResult::Attr::Pointer)) {
752     return false;
753   }
754   const auto *typeAndShape{result.GetTypeAndShape()};
755   if (!typeAndShape || typeAndShape->Rank() != 0) {
756     return false;
757   }
758   auto category{typeAndShape->type().category()};
759   if (category == TypeCategory::Character ||
760       category == TypeCategory::Derived) {
761     return false;
762   }
763   int kind{typeAndShape->type().kind()};
764   return kind == context_.GetDefaultKind(category) ||
765       (category == TypeCategory::Real &&
766           kind == context_.doublePrecisionKind());
767 }
768 
769 void CheckHelper::CheckSubprogram(
770     const Symbol &symbol, const SubprogramDetails &details) {
771   if (const Symbol * iface{FindSeparateModuleSubprogramInterface(&symbol)}) {
772     SubprogramMatchHelper{*this}.Check(symbol, *iface);
773   }
774   if (const Scope * entryScope{details.entryScope()}) {
775     // ENTRY 15.6.2.6, esp. C1571
776     std::optional<parser::MessageFixedText> error;
777     const Symbol *subprogram{entryScope->symbol()};
778     const SubprogramDetails *subprogramDetails{nullptr};
779     if (subprogram) {
780       subprogramDetails = subprogram->detailsIf<SubprogramDetails>();
781     }
782     if (entryScope->kind() != Scope::Kind::Subprogram) {
783       error = "ENTRY may appear only in a subroutine or function"_err_en_US;
784     } else if (!(entryScope->parent().IsGlobal() ||
785                    entryScope->parent().IsModule() ||
786                    entryScope->parent().IsSubmodule())) {
787       error = "ENTRY may not appear in an internal subprogram"_err_en_US;
788     } else if (FindSeparateModuleSubprogramInterface(subprogram)) {
789       error = "ENTRY may not appear in a separate module procedure"_err_en_US;
790     } else if (subprogramDetails && details.isFunction() &&
791         subprogramDetails->isFunction()) {
792       auto result{FunctionResult::Characterize(
793           details.result(), context_.foldingContext())};
794       auto subpResult{FunctionResult::Characterize(
795           subprogramDetails->result(), context_.foldingContext())};
796       if (result && subpResult && *result != *subpResult &&
797           (!IsResultOkToDiffer(*result) || !IsResultOkToDiffer(*subpResult))) {
798         error =
799             "Result of ENTRY is not compatible with result of containing function"_err_en_US;
800       }
801     }
802     if (error) {
803       if (auto *msg{messages_.Say(symbol.name(), *error)}) {
804         if (subprogram) {
805           msg->Attach(subprogram->name(), "Containing subprogram"_en_US);
806         }
807       }
808     }
809   }
810 }
811 
812 void CheckHelper::CheckDerivedType(
813     const Symbol &derivedType, const DerivedTypeDetails &details) {
814   const Scope *scope{derivedType.scope()};
815   if (!scope) {
816     CHECK(details.isForwardReferenced());
817     return;
818   }
819   CHECK(scope->symbol() == &derivedType);
820   CHECK(scope->IsDerivedType());
821   if (derivedType.attrs().test(Attr::ABSTRACT) && // C734
822       (derivedType.attrs().test(Attr::BIND_C) || details.sequence())) {
823     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
824   }
825   if (const DeclTypeSpec * parent{FindParentTypeSpec(derivedType)}) {
826     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
827     if (!IsExtensibleType(parentDerived)) { // C705
828       messages_.Say("The parent type is not extensible"_err_en_US);
829     }
830     if (!derivedType.attrs().test(Attr::ABSTRACT) && parentDerived &&
831         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
832       ScopeComponentIterator components{*parentDerived};
833       for (const Symbol &component : components) {
834         if (component.attrs().test(Attr::DEFERRED)) {
835           if (scope->FindComponent(component.name()) == &component) {
836             SayWithDeclaration(component,
837                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
838                 parentDerived->typeSymbol().name(), component.name());
839           }
840         }
841       }
842     }
843     DerivedTypeSpec derived{derivedType.name(), derivedType};
844     derived.set_scope(*scope);
845     if (FindCoarrayUltimateComponent(derived) && // C736
846         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
847       messages_.Say(
848           "Type '%s' has a coarray ultimate component so the type at the base "
849           "of its type extension chain ('%s') must be a type that has a "
850           "coarray ultimate component"_err_en_US,
851           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
852     }
853     if (FindEventOrLockPotentialComponent(derived) && // C737
854         !(FindEventOrLockPotentialComponent(*parentDerived) ||
855             IsEventTypeOrLockType(parentDerived))) {
856       messages_.Say(
857           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
858           "at the base of its type extension chain ('%s') must either have an "
859           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
860           "LOCK_TYPE"_err_en_US,
861           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
862     }
863   }
864   if (HasIntrinsicTypeName(derivedType)) { // C729
865     messages_.Say("A derived type name cannot be the name of an intrinsic"
866                   " type"_err_en_US);
867   }
868   std::map<SourceName, SymbolRef> previous;
869   for (const auto &pair : details.finals()) {
870     SourceName source{pair.first};
871     const Symbol &ref{*pair.second};
872     if (CheckFinal(ref, source, derivedType) &&
873         std::all_of(previous.begin(), previous.end(),
874             [&](std::pair<SourceName, SymbolRef> prev) {
875               return CheckDistinguishableFinals(
876                   ref, source, *prev.second, prev.first, derivedType);
877             })) {
878       previous.emplace(source, ref);
879     }
880   }
881 }
882 
883 // C786
884 bool CheckHelper::CheckFinal(
885     const Symbol &subroutine, SourceName finalName, const Symbol &derivedType) {
886   if (!IsModuleProcedure(subroutine)) {
887     SayWithDeclaration(subroutine, finalName,
888         "FINAL subroutine '%s' of derived type '%s' must be a module procedure"_err_en_US,
889         subroutine.name(), derivedType.name());
890     return false;
891   }
892   const Procedure *proc{Characterize(subroutine)};
893   if (!proc) {
894     return false; // error recovery
895   }
896   if (!proc->IsSubroutine()) {
897     SayWithDeclaration(subroutine, finalName,
898         "FINAL subroutine '%s' of derived type '%s' must be a subroutine"_err_en_US,
899         subroutine.name(), derivedType.name());
900     return false;
901   }
902   if (proc->dummyArguments.size() != 1) {
903     SayWithDeclaration(subroutine, finalName,
904         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument"_err_en_US,
905         subroutine.name(), derivedType.name());
906     return false;
907   }
908   const auto &arg{proc->dummyArguments[0]};
909   const Symbol *errSym{&subroutine};
910   if (const auto *details{subroutine.detailsIf<SubprogramDetails>()}) {
911     if (!details->dummyArgs().empty()) {
912       if (const Symbol * argSym{details->dummyArgs()[0]}) {
913         errSym = argSym;
914       }
915     }
916   }
917   const auto *ddo{std::get_if<DummyDataObject>(&arg.u)};
918   if (!ddo) {
919     SayWithDeclaration(subroutine, finalName,
920         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument that is a data object"_err_en_US,
921         subroutine.name(), derivedType.name());
922     return false;
923   }
924   bool ok{true};
925   if (arg.IsOptional()) {
926     SayWithDeclaration(*errSym, finalName,
927         "FINAL subroutine '%s' of derived type '%s' must not have an OPTIONAL dummy argument"_err_en_US,
928         subroutine.name(), derivedType.name());
929     ok = false;
930   }
931   if (ddo->attrs.test(DummyDataObject::Attr::Allocatable)) {
932     SayWithDeclaration(*errSym, finalName,
933         "FINAL subroutine '%s' of derived type '%s' must not have an ALLOCATABLE dummy argument"_err_en_US,
934         subroutine.name(), derivedType.name());
935     ok = false;
936   }
937   if (ddo->attrs.test(DummyDataObject::Attr::Pointer)) {
938     SayWithDeclaration(*errSym, finalName,
939         "FINAL subroutine '%s' of derived type '%s' must not have a POINTER dummy argument"_err_en_US,
940         subroutine.name(), derivedType.name());
941     ok = false;
942   }
943   if (ddo->intent == common::Intent::Out) {
944     SayWithDeclaration(*errSym, finalName,
945         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with INTENT(OUT)"_err_en_US,
946         subroutine.name(), derivedType.name());
947     ok = false;
948   }
949   if (ddo->attrs.test(DummyDataObject::Attr::Value)) {
950     SayWithDeclaration(*errSym, finalName,
951         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with the VALUE attribute"_err_en_US,
952         subroutine.name(), derivedType.name());
953     ok = false;
954   }
955   if (ddo->type.corank() > 0) {
956     SayWithDeclaration(*errSym, finalName,
957         "FINAL subroutine '%s' of derived type '%s' must not have a coarray dummy argument"_err_en_US,
958         subroutine.name(), derivedType.name());
959     ok = false;
960   }
961   if (ddo->type.type().IsPolymorphic()) {
962     SayWithDeclaration(*errSym, finalName,
963         "FINAL subroutine '%s' of derived type '%s' must not have a polymorphic dummy argument"_err_en_US,
964         subroutine.name(), derivedType.name());
965     ok = false;
966   } else if (ddo->type.type().category() != TypeCategory::Derived ||
967       &ddo->type.type().GetDerivedTypeSpec().typeSymbol() != &derivedType) {
968     SayWithDeclaration(*errSym, finalName,
969         "FINAL subroutine '%s' of derived type '%s' must have a TYPE(%s) dummy argument"_err_en_US,
970         subroutine.name(), derivedType.name(), derivedType.name());
971     ok = false;
972   } else { // check that all LEN type parameters are assumed
973     for (auto ref : OrderParameterDeclarations(derivedType)) {
974       if (IsLenTypeParameter(*ref)) {
975         const auto *value{
976             ddo->type.type().GetDerivedTypeSpec().FindParameter(ref->name())};
977         if (!value || !value->isAssumed()) {
978           SayWithDeclaration(*errSym, finalName,
979               "FINAL subroutine '%s' of derived type '%s' must have a dummy argument with an assumed LEN type parameter '%s=*'"_err_en_US,
980               subroutine.name(), derivedType.name(), ref->name());
981           ok = false;
982         }
983       }
984     }
985   }
986   return ok;
987 }
988 
989 bool CheckHelper::CheckDistinguishableFinals(const Symbol &f1,
990     SourceName f1Name, const Symbol &f2, SourceName f2Name,
991     const Symbol &derivedType) {
992   const Procedure *p1{Characterize(f1)};
993   const Procedure *p2{Characterize(f2)};
994   if (p1 && p2) {
995     if (characteristics::Distinguishable(*p1, *p2)) {
996       return true;
997     }
998     if (auto *msg{messages_.Say(f1Name,
999             "FINAL subroutines '%s' and '%s' of derived type '%s' cannot be distinguished by rank or KIND type parameter value"_err_en_US,
1000             f1Name, f2Name, derivedType.name())}) {
1001       msg->Attach(f2Name, "FINAL declaration of '%s'"_en_US, f2.name())
1002           .Attach(f1.name(), "Definition of '%s'"_en_US, f1Name)
1003           .Attach(f2.name(), "Definition of '%s'"_en_US, f2Name);
1004     }
1005   }
1006   return false;
1007 }
1008 
1009 void CheckHelper::CheckHostAssoc(
1010     const Symbol &symbol, const HostAssocDetails &details) {
1011   const Symbol &hostSymbol{details.symbol()};
1012   if (hostSymbol.test(Symbol::Flag::ImplicitOrError)) {
1013     if (details.implicitOrSpecExprError) {
1014       messages_.Say("Implicitly typed local entity '%s' not allowed in"
1015                     " specification expression"_err_en_US,
1016           symbol.name());
1017     } else if (details.implicitOrExplicitTypeError) {
1018       messages_.Say(
1019           "No explicit type declared for '%s'"_err_en_US, symbol.name());
1020     }
1021   }
1022 }
1023 
1024 void CheckHelper::CheckGeneric(
1025     const Symbol &symbol, const GenericDetails &details) {
1026   CheckSpecificsAreDistinguishable(symbol, details);
1027 }
1028 
1029 // Check that the specifics of this generic are distinguishable from each other
1030 void CheckHelper::CheckSpecificsAreDistinguishable(
1031     const Symbol &generic, const GenericDetails &details) {
1032   GenericKind kind{details.kind()};
1033   const SymbolVector &specifics{details.specificProcs()};
1034   std::size_t count{specifics.size()};
1035   if (count < 2 || !kind.IsName()) {
1036     return;
1037   }
1038   DistinguishabilityHelper helper{context_};
1039   for (const Symbol &specific : specifics) {
1040     if (const Procedure * procedure{Characterize(specific)}) {
1041       helper.Add(generic, kind, specific, *procedure);
1042     }
1043   }
1044   helper.Check(generic.owner());
1045 }
1046 
1047 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
1048   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1049   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1050   return Tristate::No ==
1051       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
1052 }
1053 
1054 static bool ConflictsWithIntrinsicOperator(
1055     const GenericKind &kind, const Procedure &proc) {
1056   if (!kind.IsIntrinsicOperator()) {
1057     return false;
1058   }
1059   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1060   auto type0{arg0.type()};
1061   if (proc.dummyArguments.size() == 1) { // unary
1062     return std::visit(
1063         common::visitors{
1064             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
1065             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
1066             [](const auto &) -> bool { DIE("bad generic kind"); },
1067         },
1068         kind.u);
1069   } else { // binary
1070     int rank0{arg0.Rank()};
1071     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1072     auto type1{arg1.type()};
1073     int rank1{arg1.Rank()};
1074     return std::visit(
1075         common::visitors{
1076             [&](common::NumericOperator) {
1077               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
1078             },
1079             [&](common::LogicalOperator) {
1080               return IsIntrinsicLogical(type0, rank0, type1, rank1);
1081             },
1082             [&](common::RelationalOperator opr) {
1083               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
1084             },
1085             [&](GenericKind::OtherKind x) {
1086               CHECK(x == GenericKind::OtherKind::Concat);
1087               return IsIntrinsicConcat(type0, rank0, type1, rank1);
1088             },
1089             [](const auto &) -> bool { DIE("bad generic kind"); },
1090         },
1091         kind.u);
1092   }
1093 }
1094 
1095 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
1096 bool CheckHelper::CheckDefinedOperator(SourceName opName, GenericKind kind,
1097     const Symbol &specific, const Procedure &proc) {
1098   if (context_.HasError(specific)) {
1099     return false;
1100   }
1101   std::optional<parser::MessageFixedText> msg;
1102   if (specific.attrs().test(Attr::NOPASS)) { // C774
1103     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
1104   } else if (!proc.functionResult.has_value()) {
1105     msg = "%s procedure '%s' must be a function"_err_en_US;
1106   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
1107     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
1108           " result"_err_en_US;
1109   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
1110     msg = std::move(m);
1111   } else if (!CheckDefinedOperatorArg(opName, specific, proc, 0) |
1112       !CheckDefinedOperatorArg(opName, specific, proc, 1)) {
1113     return false; // error was reported
1114   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
1115     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
1116   } else {
1117     return true; // OK
1118   }
1119   SayWithDeclaration(
1120       specific, std::move(*msg), MakeOpName(opName), specific.name());
1121   context_.SetError(specific);
1122   return false;
1123 }
1124 
1125 // If the number of arguments is wrong for this intrinsic operator, return
1126 // false and return the error message in msg.
1127 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
1128     const GenericKind &kind, std::size_t nargs) {
1129   if (!kind.IsIntrinsicOperator()) {
1130     return std::nullopt;
1131   }
1132   std::size_t min{2}, max{2}; // allowed number of args; default is binary
1133   std::visit(common::visitors{
1134                  [&](const common::NumericOperator &x) {
1135                    if (x == common::NumericOperator::Add ||
1136                        x == common::NumericOperator::Subtract) {
1137                      min = 1; // + and - are unary or binary
1138                    }
1139                  },
1140                  [&](const common::LogicalOperator &x) {
1141                    if (x == common::LogicalOperator::Not) {
1142                      min = 1; // .NOT. is unary
1143                      max = 1;
1144                    }
1145                  },
1146                  [](const common::RelationalOperator &) {
1147                    // all are binary
1148                  },
1149                  [](const GenericKind::OtherKind &x) {
1150                    CHECK(x == GenericKind::OtherKind::Concat);
1151                  },
1152                  [](const auto &) { DIE("expected intrinsic operator"); },
1153              },
1154       kind.u);
1155   if (nargs >= min && nargs <= max) {
1156     return std::nullopt;
1157   } else if (max == 1) {
1158     return "%s function '%s' must have one dummy argument"_err_en_US;
1159   } else if (min == 2) {
1160     return "%s function '%s' must have two dummy arguments"_err_en_US;
1161   } else {
1162     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
1163   }
1164 }
1165 
1166 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
1167     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
1168   if (pos >= proc.dummyArguments.size()) {
1169     return true;
1170   }
1171   auto &arg{proc.dummyArguments.at(pos)};
1172   std::optional<parser::MessageFixedText> msg;
1173   if (arg.IsOptional()) {
1174     msg = "In %s function '%s', dummy argument '%s' may not be"
1175           " OPTIONAL"_err_en_US;
1176   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
1177              dataObject == nullptr) {
1178     msg = "In %s function '%s', dummy argument '%s' must be a"
1179           " data object"_err_en_US;
1180   } else if (dataObject->intent != common::Intent::In &&
1181       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1182     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
1183           " or VALUE attribute"_err_en_US;
1184   }
1185   if (msg) {
1186     SayWithDeclaration(symbol, std::move(*msg),
1187         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
1188     return false;
1189   }
1190   return true;
1191 }
1192 
1193 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
1194 bool CheckHelper::CheckDefinedAssignment(
1195     const Symbol &specific, const Procedure &proc) {
1196   if (context_.HasError(specific)) {
1197     return false;
1198   }
1199   std::optional<parser::MessageFixedText> msg;
1200   if (specific.attrs().test(Attr::NOPASS)) { // C774
1201     msg = "Defined assignment procedure '%s' may not have"
1202           " NOPASS attribute"_err_en_US;
1203   } else if (!proc.IsSubroutine()) {
1204     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
1205   } else if (proc.dummyArguments.size() != 2) {
1206     msg = "Defined assignment subroutine '%s' must have"
1207           " two dummy arguments"_err_en_US;
1208   } else if (!CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0) |
1209       !CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)) {
1210     return false; // error was reported
1211   } else if (ConflictsWithIntrinsicAssignment(proc)) {
1212     msg = "Defined assignment subroutine '%s' conflicts with"
1213           " intrinsic assignment"_err_en_US;
1214   } else {
1215     return true; // OK
1216   }
1217   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
1218   context_.SetError(specific);
1219   return false;
1220 }
1221 
1222 bool CheckHelper::CheckDefinedAssignmentArg(
1223     const Symbol &symbol, const DummyArgument &arg, int pos) {
1224   std::optional<parser::MessageFixedText> msg;
1225   if (arg.IsOptional()) {
1226     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1227           " may not be OPTIONAL"_err_en_US;
1228   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
1229     if (pos == 0) {
1230       if (dataObject->intent != common::Intent::Out &&
1231           dataObject->intent != common::Intent::InOut) {
1232         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
1233               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
1234       }
1235     } else if (pos == 1) {
1236       if (dataObject->intent != common::Intent::In &&
1237           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1238         msg =
1239             "In defined assignment subroutine '%s', second dummy"
1240             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1241       }
1242     } else {
1243       DIE("pos must be 0 or 1");
1244     }
1245   } else {
1246     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1247           " must be a data object"_err_en_US;
1248   }
1249   if (msg) {
1250     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1251     context_.SetError(symbol);
1252     return false;
1253   }
1254   return true;
1255 }
1256 
1257 // Report a conflicting attribute error if symbol has both of these attributes
1258 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1259   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1260     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1261         symbol.name(), EnumToString(a1), EnumToString(a2));
1262     return true;
1263   } else {
1264     return false;
1265   }
1266 }
1267 
1268 void CheckHelper::WarnMissingFinal(const Symbol &symbol) {
1269   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
1270   if (!object || IsPointer(symbol)) {
1271     return;
1272   }
1273   const DeclTypeSpec *type{object->type()};
1274   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
1275   const Symbol *derivedSym{derived ? &derived->typeSymbol() : nullptr};
1276   int rank{object->shape().Rank()};
1277   const Symbol *initialDerivedSym{derivedSym};
1278   while (const auto *derivedDetails{
1279       derivedSym ? derivedSym->detailsIf<DerivedTypeDetails>() : nullptr}) {
1280     if (!derivedDetails->finals().empty() &&
1281         !derivedDetails->GetFinalForRank(rank)) {
1282       if (auto *msg{derivedSym == initialDerivedSym
1283                   ? messages_.Say(symbol.name(),
1284                         "'%s' of derived type '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1285                         symbol.name(), derivedSym->name(), rank)
1286                   : messages_.Say(symbol.name(),
1287                         "'%s' of derived type '%s' extended from '%s' does not have a FINAL subroutine for its rank (%d)"_en_US,
1288                         symbol.name(), initialDerivedSym->name(),
1289                         derivedSym->name(), rank)}) {
1290         msg->Attach(derivedSym->name(),
1291             "Declaration of derived type '%s'"_en_US, derivedSym->name());
1292       }
1293       return;
1294     }
1295     derived = derivedSym->GetParentTypeSpec();
1296     derivedSym = derived ? &derived->typeSymbol() : nullptr;
1297   }
1298 }
1299 
1300 const Procedure *CheckHelper::Characterize(const Symbol &symbol) {
1301   auto it{characterizeCache_.find(symbol)};
1302   if (it == characterizeCache_.end()) {
1303     auto pair{characterizeCache_.emplace(SymbolRef{symbol},
1304         Procedure::Characterize(symbol, context_.foldingContext()))};
1305     it = pair.first;
1306   }
1307   return common::GetPtrFromOptional(it->second);
1308 }
1309 
1310 void CheckHelper::CheckVolatile(const Symbol &symbol,
1311     const DerivedTypeSpec *derived) { // C866 - C868
1312   if (IsIntentIn(symbol)) {
1313     messages_.Say(
1314         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1315   }
1316   if (IsProcedure(symbol)) {
1317     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1318   }
1319   if (symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()) {
1320     const Symbol &ultimate{symbol.GetUltimate()};
1321     if (IsCoarray(ultimate)) {
1322       messages_.Say(
1323           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1324     }
1325     if (derived) {
1326       if (FindCoarrayUltimateComponent(*derived)) {
1327         messages_.Say(
1328             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1329       }
1330     }
1331   }
1332 }
1333 
1334 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1335   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1336   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1337   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1338   // Prohibit constant pointers.  The standard does not explicitly prohibit
1339   // them, but the PARAMETER attribute requires a entity-decl to have an
1340   // initialization that is a constant-expr, and the only form of
1341   // initialization that allows a constant-expr is the one that's not a "=>"
1342   // pointer initialization.  See C811, C807, and section 8.5.13.
1343   CheckConflicting(symbol, Attr::POINTER, Attr::PARAMETER);
1344   if (symbol.Corank() > 0) {
1345     messages_.Say(
1346         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1347         symbol.name());
1348   }
1349 }
1350 
1351 // C760 constraints on the passed-object dummy argument
1352 // C757 constraints on procedure pointer components
1353 void CheckHelper::CheckPassArg(
1354     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1355   if (proc.attrs().test(Attr::NOPASS)) {
1356     return;
1357   }
1358   const auto &name{proc.name()};
1359   if (!interface) {
1360     messages_.Say(name,
1361         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1362         name);
1363     return;
1364   }
1365   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1366   if (!subprogram) {
1367     messages_.Say(name,
1368         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1369         interface->name());
1370     return;
1371   }
1372   std::optional<SourceName> passName{details.passName()};
1373   const auto &dummyArgs{subprogram->dummyArgs()};
1374   if (!passName) {
1375     if (dummyArgs.empty()) {
1376       messages_.Say(name,
1377           proc.has<ProcEntityDetails>()
1378               ? "Procedure component '%s' with no dummy arguments"
1379                 " must have NOPASS attribute"_err_en_US
1380               : "Procedure binding '%s' with no dummy arguments"
1381                 " must have NOPASS attribute"_err_en_US,
1382           name);
1383       context_.SetError(*interface);
1384       return;
1385     }
1386     Symbol *argSym{dummyArgs[0]};
1387     if (!argSym) {
1388       messages_.Say(interface->name(),
1389           "Cannot use an alternate return as the passed-object dummy "
1390           "argument"_err_en_US);
1391       return;
1392     }
1393     passName = dummyArgs[0]->name();
1394   }
1395   std::optional<int> passArgIndex{};
1396   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1397     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1398       passArgIndex = i;
1399       break;
1400     }
1401   }
1402   if (!passArgIndex) { // C758
1403     messages_.Say(*passName,
1404         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1405         *passName, interface->name());
1406     return;
1407   }
1408   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1409   std::optional<parser::MessageFixedText> msg;
1410   if (!passArg.has<ObjectEntityDetails>()) {
1411     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1412           " must be a data object"_err_en_US;
1413   } else if (passArg.attrs().test(Attr::POINTER)) {
1414     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1415           " may not have the POINTER attribute"_err_en_US;
1416   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1417     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1418           " may not have the ALLOCATABLE attribute"_err_en_US;
1419   } else if (passArg.attrs().test(Attr::VALUE)) {
1420     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1421           " may not have the VALUE attribute"_err_en_US;
1422   } else if (passArg.Rank() > 0) {
1423     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1424           " must be scalar"_err_en_US;
1425   }
1426   if (msg) {
1427     messages_.Say(name, std::move(*msg), passName.value(), name);
1428     return;
1429   }
1430   const DeclTypeSpec *type{passArg.GetType()};
1431   if (!type) {
1432     return; // an error already occurred
1433   }
1434   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1435   const DerivedTypeSpec *derived{type->AsDerived()};
1436   if (!derived || derived->typeSymbol() != typeSymbol) {
1437     messages_.Say(name,
1438         "Passed-object dummy argument '%s' of procedure '%s'"
1439         " must be of type '%s' but is '%s'"_err_en_US,
1440         passName.value(), name, typeSymbol.name(), type->AsFortran());
1441     return;
1442   }
1443   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1444     messages_.Say(name,
1445         type->IsPolymorphic()
1446             ? "Passed-object dummy argument '%s' of procedure '%s'"
1447               " may not be polymorphic because '%s' is not extensible"_err_en_US
1448             : "Passed-object dummy argument '%s' of procedure '%s'"
1449               " must be polymorphic because '%s' is extensible"_err_en_US,
1450         passName.value(), name, typeSymbol.name());
1451     return;
1452   }
1453   for (const auto &[paramName, paramValue] : derived->parameters()) {
1454     if (paramValue.isLen() && !paramValue.isAssumed()) {
1455       messages_.Say(name,
1456           "Passed-object dummy argument '%s' of procedure '%s'"
1457           " has non-assumed length parameter '%s'"_err_en_US,
1458           passName.value(), name, paramName);
1459     }
1460   }
1461 }
1462 
1463 void CheckHelper::CheckProcBinding(
1464     const Symbol &symbol, const ProcBindingDetails &binding) {
1465   const Scope &dtScope{symbol.owner()};
1466   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1467   if (const Symbol * dtSymbol{dtScope.symbol()}) {
1468     if (symbol.attrs().test(Attr::DEFERRED)) {
1469       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1470         SayWithDeclaration(*dtSymbol,
1471             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1472             dtSymbol->name());
1473       }
1474       if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1475         messages_.Say(
1476             "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1477             symbol.name());
1478       }
1479     }
1480   }
1481   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1482     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1483       SayWithDeclaration(*overridden,
1484           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1485           symbol.name());
1486     }
1487     if (const auto *overriddenBinding{
1488             overridden->detailsIf<ProcBindingDetails>()}) {
1489       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1490         SayWithDeclaration(*overridden,
1491             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1492         return;
1493       }
1494       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1495           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1496         SayWithDeclaration(*overridden,
1497             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1498         return;
1499       }
1500       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1501       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1502         SayWithDeclaration(*overridden,
1503             isNopass
1504                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1505                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1506       } else {
1507         const auto *bindingChars{Characterize(binding.symbol())};
1508         const auto *overriddenChars{Characterize(overriddenBinding->symbol())};
1509         if (bindingChars && overriddenChars) {
1510           if (isNopass) {
1511             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1512               SayWithDeclaration(*overridden,
1513                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1514             }
1515           } else if (!context_.HasError(binding.symbol())) {
1516             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1517             int overriddenPassIndex{
1518                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1519             if (passIndex != overriddenPassIndex) {
1520               SayWithDeclaration(*overridden,
1521                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1522             } else if (!bindingChars->CanOverride(
1523                            *overriddenChars, passIndex)) {
1524               SayWithDeclaration(*overridden,
1525                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1526             }
1527           }
1528         }
1529       }
1530       if (symbol.attrs().test(Attr::PRIVATE) &&
1531           overridden->attrs().test(Attr::PUBLIC)) {
1532         SayWithDeclaration(*overridden,
1533             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1534       }
1535     } else {
1536       SayWithDeclaration(*overridden,
1537           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1538     }
1539   }
1540   CheckPassArg(symbol, &binding.symbol(), binding);
1541 }
1542 
1543 void CheckHelper::Check(const Scope &scope) {
1544   scope_ = &scope;
1545   common::Restorer<const Symbol *> restorer{innermostSymbol_, innermostSymbol_};
1546   if (const Symbol * symbol{scope.symbol()}) {
1547     innermostSymbol_ = symbol;
1548   }
1549   if (scope.IsParameterizedDerivedTypeInstantiation()) {
1550     auto restorer{common::ScopedSet(scopeIsUninstantiatedPDT_, false)};
1551     auto restorer2{context_.foldingContext().messages().SetContext(
1552         scope.instantiationContext().get())};
1553     for (const auto &pair : scope) {
1554       CheckPointerInitialization(*pair.second);
1555     }
1556   } else {
1557     auto restorer{common::ScopedSet(
1558         scopeIsUninstantiatedPDT_, scope.IsParameterizedDerivedType())};
1559     for (const auto &set : scope.equivalenceSets()) {
1560       CheckEquivalenceSet(set);
1561     }
1562     for (const auto &pair : scope) {
1563       Check(*pair.second);
1564     }
1565     for (const Scope &child : scope.children()) {
1566       Check(child);
1567     }
1568     if (scope.kind() == Scope::Kind::BlockData) {
1569       CheckBlockData(scope);
1570     }
1571     CheckGenericOps(scope);
1572   }
1573 }
1574 
1575 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1576   auto iter{
1577       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1578         return FindCommonBlockContaining(object.symbol) != nullptr;
1579       })};
1580   if (iter != set.end()) {
1581     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1582     for (auto &object : set) {
1583       if (&object != &*iter) {
1584         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1585           if (details->commonBlock()) {
1586             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1587               if (auto *msg{messages_.Say(object.symbol.name(),
1588                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1589                 msg->Attach(iter->symbol.name(),
1590                        "Other object in EQUIVALENCE set"_en_US)
1591                     .Attach(details->commonBlock()->name(),
1592                         "COMMON block containing '%s'"_en_US,
1593                         object.symbol.name())
1594                     .Attach(commonBlock.name(),
1595                         "COMMON block containing '%s'"_en_US,
1596                         iter->symbol.name());
1597               }
1598             }
1599           } else {
1600             // Mark all symbols in the equivalence set with the same COMMON
1601             // block to prevent spurious error messages about initialization
1602             // in BLOCK DATA outside COMMON
1603             details->set_commonBlock(commonBlock);
1604           }
1605         }
1606       }
1607     }
1608   }
1609   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1610 }
1611 
1612 void CheckHelper::CheckBlockData(const Scope &scope) {
1613   // BLOCK DATA subprograms should contain only named common blocks.
1614   // C1415 presents a list of statements that shouldn't appear in
1615   // BLOCK DATA, but so long as the subprogram contains no executable
1616   // code and allocates no storage outside named COMMON, we're happy
1617   // (e.g., an ENUM is strictly not allowed).
1618   for (const auto &pair : scope) {
1619     const Symbol &symbol{*pair.second};
1620     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1621             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1622             symbol.has<SubprogramDetails>() ||
1623             symbol.has<ObjectEntityDetails>() ||
1624             (symbol.has<ProcEntityDetails>() &&
1625                 !symbol.attrs().test(Attr::POINTER)))) {
1626       messages_.Say(symbol.name(),
1627           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1628           symbol.name());
1629     }
1630   }
1631 }
1632 
1633 // Check distinguishability of generic assignment and operators.
1634 // For these, generics and generic bindings must be considered together.
1635 void CheckHelper::CheckGenericOps(const Scope &scope) {
1636   DistinguishabilityHelper helper{context_};
1637   auto addSpecifics{[&](const Symbol &generic) {
1638     const auto *details{generic.GetUltimate().detailsIf<GenericDetails>()};
1639     if (!details) {
1640       return;
1641     }
1642     GenericKind kind{details->kind()};
1643     if (!kind.IsAssignment() && !kind.IsOperator()) {
1644       return;
1645     }
1646     const SymbolVector &specifics{details->specificProcs()};
1647     const std::vector<SourceName> &bindingNames{details->bindingNames()};
1648     for (std::size_t i{0}; i < specifics.size(); ++i) {
1649       const Symbol &specific{*specifics[i]};
1650       if (const Procedure * proc{Characterize(specific)}) {
1651         auto restorer{messages_.SetLocation(bindingNames[i])};
1652         if (kind.IsAssignment()) {
1653           if (!CheckDefinedAssignment(specific, *proc)) {
1654             continue;
1655           }
1656         } else {
1657           if (!CheckDefinedOperator(generic.name(), kind, specific, *proc)) {
1658             continue;
1659           }
1660         }
1661         helper.Add(generic, kind, specific, *proc);
1662       }
1663     }
1664   }};
1665   for (const auto &pair : scope) {
1666     const Symbol &symbol{*pair.second};
1667     addSpecifics(symbol);
1668     const Symbol &ultimate{symbol.GetUltimate()};
1669     if (ultimate.has<DerivedTypeDetails>()) {
1670       if (const Scope * typeScope{ultimate.scope()}) {
1671         for (const auto &pair2 : *typeScope) {
1672           addSpecifics(*pair2.second);
1673         }
1674       }
1675     }
1676   }
1677   helper.Check(scope);
1678 }
1679 
1680 static const std::string *DefinesBindCName(const Symbol &symbol) {
1681   const auto *subp{symbol.detailsIf<SubprogramDetails>()};
1682   if ((subp && !subp->isInterface()) || symbol.has<ObjectEntityDetails>()) {
1683     // Symbol defines data or entry point
1684     return symbol.GetBindName();
1685   } else {
1686     return nullptr;
1687   }
1688 }
1689 
1690 // Check that BIND(C) names are distinct
1691 void CheckHelper::CheckBindCName(const Symbol &symbol) {
1692   if (const std::string * name{DefinesBindCName(symbol)}) {
1693     auto pair{bindC_.emplace(*name, symbol)};
1694     if (!pair.second) {
1695       const Symbol &other{*pair.first->second};
1696       if (DefinesBindCName(other) && !context_.HasError(other)) {
1697         if (auto *msg{messages_.Say(
1698                 "Two symbols have the same BIND(C) name '%s'"_err_en_US,
1699                 *name)}) {
1700           msg->Attach(other.name(), "Conflicting symbol"_en_US);
1701         }
1702         context_.SetError(symbol);
1703         context_.SetError(other);
1704       }
1705     }
1706   }
1707 }
1708 
1709 void SubprogramMatchHelper::Check(
1710     const Symbol &symbol1, const Symbol &symbol2) {
1711   const auto details1{symbol1.get<SubprogramDetails>()};
1712   const auto details2{symbol2.get<SubprogramDetails>()};
1713   if (details1.isFunction() != details2.isFunction()) {
1714     Say(symbol1, symbol2,
1715         details1.isFunction()
1716             ? "Module function '%s' was declared as a subroutine in the"
1717               " corresponding interface body"_err_en_US
1718             : "Module subroutine '%s' was declared as a function in the"
1719               " corresponding interface body"_err_en_US);
1720     return;
1721   }
1722   const auto &args1{details1.dummyArgs()};
1723   const auto &args2{details2.dummyArgs()};
1724   int nargs1{static_cast<int>(args1.size())};
1725   int nargs2{static_cast<int>(args2.size())};
1726   if (nargs1 != nargs2) {
1727     Say(symbol1, symbol2,
1728         "Module subprogram '%s' has %d args but the corresponding interface"
1729         " body has %d"_err_en_US,
1730         nargs1, nargs2);
1731     return;
1732   }
1733   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
1734   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
1735     Say(symbol1, symbol2,
1736         nonRecursive1
1737             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
1738               " the corresponding interface body does not"_err_en_US
1739             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
1740               "the corresponding interface body does"_err_en_US);
1741   }
1742   const std::string *bindName1{details1.bindName()};
1743   const std::string *bindName2{details2.bindName()};
1744   if (!bindName1 && !bindName2) {
1745     // OK - neither has a binding label
1746   } else if (!bindName1) {
1747     Say(symbol1, symbol2,
1748         "Module subprogram '%s' does not have a binding label but the"
1749         " corresponding interface body does"_err_en_US);
1750   } else if (!bindName2) {
1751     Say(symbol1, symbol2,
1752         "Module subprogram '%s' has a binding label but the"
1753         " corresponding interface body does not"_err_en_US);
1754   } else if (*bindName1 != *bindName2) {
1755     Say(symbol1, symbol2,
1756         "Module subprogram '%s' has binding label '%s' but the corresponding"
1757         " interface body has '%s'"_err_en_US,
1758         *details1.bindName(), *details2.bindName());
1759   }
1760   const Procedure *proc1{checkHelper.Characterize(symbol1)};
1761   const Procedure *proc2{checkHelper.Characterize(symbol2)};
1762   if (!proc1 || !proc2) {
1763     return;
1764   }
1765   if (proc1->functionResult && proc2->functionResult &&
1766       *proc1->functionResult != *proc2->functionResult) {
1767     Say(symbol1, symbol2,
1768         "Return type of function '%s' does not match return type of"
1769         " the corresponding interface body"_err_en_US);
1770   }
1771   for (int i{0}; i < nargs1; ++i) {
1772     const Symbol *arg1{args1[i]};
1773     const Symbol *arg2{args2[i]};
1774     if (arg1 && !arg2) {
1775       Say(symbol1, symbol2,
1776           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
1777           " but the corresponding argument in the interface body is"_err_en_US,
1778           i + 1);
1779     } else if (!arg1 && arg2) {
1780       Say(symbol1, symbol2,
1781           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
1782           " the corresponding argument in the interface body is not"_err_en_US,
1783           i + 1);
1784     } else if (arg1 && arg2) {
1785       SourceName name1{arg1->name()};
1786       SourceName name2{arg2->name()};
1787       if (name1 != name2) {
1788         Say(*arg1, *arg2,
1789             "Dummy argument name '%s' does not match corresponding name '%s'"
1790             " in interface body"_err_en_US,
1791             name2);
1792       } else {
1793         CheckDummyArg(
1794             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
1795       }
1796     }
1797   }
1798 }
1799 
1800 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
1801     const Symbol &symbol2, const DummyArgument &arg1,
1802     const DummyArgument &arg2) {
1803   std::visit(common::visitors{
1804                  [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
1805                    CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
1806                  },
1807                  [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
1808                    CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
1809                  },
1810                  [&](const DummyDataObject &, const auto &) {
1811                    Say(symbol1, symbol2,
1812                        "Dummy argument '%s' is a data object; the corresponding"
1813                        " argument in the interface body is not"_err_en_US);
1814                  },
1815                  [&](const DummyProcedure &, const auto &) {
1816                    Say(symbol1, symbol2,
1817                        "Dummy argument '%s' is a procedure; the corresponding"
1818                        " argument in the interface body is not"_err_en_US);
1819                  },
1820                  [&](const auto &, const auto &) {
1821                    llvm_unreachable("Dummy arguments are not data objects or"
1822                                     "procedures");
1823                  },
1824              },
1825       arg1.u, arg2.u);
1826 }
1827 
1828 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
1829     const Symbol &symbol2, const DummyDataObject &obj1,
1830     const DummyDataObject &obj2) {
1831   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
1832   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
1833   } else if (obj1.type.type() != obj2.type.type()) {
1834     Say(symbol1, symbol2,
1835         "Dummy argument '%s' has type %s; the corresponding argument in the"
1836         " interface body has type %s"_err_en_US,
1837         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
1838   } else if (!ShapesAreCompatible(obj1, obj2)) {
1839     Say(symbol1, symbol2,
1840         "The shape of dummy argument '%s' does not match the shape of the"
1841         " corresponding argument in the interface body"_err_en_US);
1842   }
1843   // TODO: coshape
1844 }
1845 
1846 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
1847     const Symbol &symbol2, const DummyProcedure &proc1,
1848     const DummyProcedure &proc2) {
1849   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
1850   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
1851   } else if (proc1 != proc2) {
1852     Say(symbol1, symbol2,
1853         "Dummy procedure '%s' does not match the corresponding argument in"
1854         " the interface body"_err_en_US);
1855   }
1856 }
1857 
1858 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
1859     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
1860   if (intent1 == intent2) {
1861     return true;
1862   } else {
1863     Say(symbol1, symbol2,
1864         "The intent of dummy argument '%s' does not match the intent"
1865         " of the corresponding argument in the interface body"_err_en_US);
1866     return false;
1867   }
1868 }
1869 
1870 // Report an error referring to first symbol with declaration of second symbol
1871 template <typename... A>
1872 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
1873     parser::MessageFixedText &&text, A &&...args) {
1874   auto &message{context().Say(symbol1.name(), std::move(text), symbol1.name(),
1875       std::forward<A>(args)...)};
1876   evaluate::AttachDeclaration(message, symbol2);
1877 }
1878 
1879 template <typename ATTRS>
1880 bool SubprogramMatchHelper::CheckSameAttrs(
1881     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
1882   if (attrs1 == attrs2) {
1883     return true;
1884   }
1885   attrs1.IterateOverMembers([&](auto attr) {
1886     if (!attrs2.test(attr)) {
1887       Say(symbol1, symbol2,
1888           "Dummy argument '%s' has the %s attribute; the corresponding"
1889           " argument in the interface body does not"_err_en_US,
1890           AsFortran(attr));
1891     }
1892   });
1893   attrs2.IterateOverMembers([&](auto attr) {
1894     if (!attrs1.test(attr)) {
1895       Say(symbol1, symbol2,
1896           "Dummy argument '%s' does not have the %s attribute; the"
1897           " corresponding argument in the interface body does"_err_en_US,
1898           AsFortran(attr));
1899     }
1900   });
1901   return false;
1902 }
1903 
1904 bool SubprogramMatchHelper::ShapesAreCompatible(
1905     const DummyDataObject &obj1, const DummyDataObject &obj2) {
1906   return characteristics::ShapesAreCompatible(
1907       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
1908 }
1909 
1910 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
1911   evaluate::Shape result;
1912   for (const auto &extent : shape) {
1913     result.emplace_back(
1914         evaluate::Fold(context().foldingContext(), common::Clone(extent)));
1915   }
1916   return result;
1917 }
1918 
1919 void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
1920     const Symbol &specific, const Procedure &procedure) {
1921   if (!context_.HasError(specific)) {
1922     nameToInfo_[generic.name()].emplace_back(
1923         ProcedureInfo{kind, specific, procedure});
1924   }
1925 }
1926 
1927 void DistinguishabilityHelper::Check(const Scope &scope) {
1928   for (const auto &[name, info] : nameToInfo_) {
1929     auto count{info.size()};
1930     for (std::size_t i1{0}; i1 < count - 1; ++i1) {
1931       const auto &[kind1, symbol1, proc1] = info[i1];
1932       for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
1933         const auto &[kind2, symbol2, proc2] = info[i2];
1934         auto distinguishable{kind1.IsName()
1935                 ? evaluate::characteristics::Distinguishable
1936                 : evaluate::characteristics::DistinguishableOpOrAssign};
1937         if (!distinguishable(proc1, proc2)) {
1938           SayNotDistinguishable(
1939               GetTopLevelUnitContaining(scope), name, kind1, symbol1, symbol2);
1940         }
1941       }
1942     }
1943   }
1944 }
1945 
1946 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
1947     const SourceName &name, GenericKind kind, const Symbol &proc1,
1948     const Symbol &proc2) {
1949   std::string name1{proc1.name().ToString()};
1950   std::string name2{proc2.name().ToString()};
1951   if (kind.IsOperator() || kind.IsAssignment()) {
1952     // proc1 and proc2 may come from different scopes so qualify their names
1953     if (proc1.owner().IsDerivedType()) {
1954       name1 = proc1.owner().GetName()->ToString() + '%' + name1;
1955     }
1956     if (proc2.owner().IsDerivedType()) {
1957       name2 = proc2.owner().GetName()->ToString() + '%' + name2;
1958     }
1959   }
1960   parser::Message *msg;
1961   if (scope.sourceRange().Contains(name)) {
1962     msg = &context_.Say(name,
1963         "Generic '%s' may not have specific procedures '%s' and"
1964         " '%s' as their interfaces are not distinguishable"_err_en_US,
1965         MakeOpName(name), name1, name2);
1966   } else {
1967     msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
1968         "USE-associated generic '%s' may not have specific procedures '%s' and"
1969         " '%s' as their interfaces are not distinguishable"_err_en_US,
1970         MakeOpName(name), name1, name2);
1971   }
1972   AttachDeclaration(*msg, scope, proc1);
1973   AttachDeclaration(*msg, scope, proc2);
1974 }
1975 
1976 // `evaluate::AttachDeclaration` doesn't handle the generic case where `proc`
1977 // comes from a different module but is not necessarily use-associated.
1978 void DistinguishabilityHelper::AttachDeclaration(
1979     parser::Message &msg, const Scope &scope, const Symbol &proc) {
1980   const Scope &unit{GetTopLevelUnitContaining(proc)};
1981   if (unit == scope) {
1982     evaluate::AttachDeclaration(msg, proc);
1983   } else {
1984     msg.Attach(unit.GetName().value(),
1985         "'%s' is USE-associated from module '%s'"_en_US, proc.name(),
1986         unit.GetName().value());
1987   }
1988 }
1989 
1990 void CheckDeclarations(SemanticsContext &context) {
1991   CheckHelper{context}.Check();
1992 }
1993 } // namespace Fortran::semantics
1994