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 
38   SemanticsContext &context() { return context_; }
39   void Check() { Check(context_.globalScope()); }
40   void Check(const ParamValue &, bool canBeAssumed);
41   void Check(const Bound &bound) { CheckSpecExpr(bound.GetExplicit()); }
42   void Check(const ShapeSpec &spec) {
43     Check(spec.lbound());
44     Check(spec.ubound());
45   }
46   void Check(const ArraySpec &);
47   void Check(const DeclTypeSpec &, bool canHaveAssumedTypeParameters);
48   void Check(const Symbol &);
49   void Check(const Scope &);
50   const Procedure *Characterize(const Symbol &);
51 
52 private:
53   template <typename A> void CheckSpecExpr(const A &x) {
54     evaluate::CheckSpecificationExpr(x, DEREF(scope_), foldingContext_);
55   }
56   void CheckValue(const Symbol &, const DerivedTypeSpec *);
57   void CheckVolatile(const Symbol &, const DerivedTypeSpec *);
58   void CheckPointer(const Symbol &);
59   void CheckPassArg(
60       const Symbol &proc, const Symbol *interface, const WithPassArg &);
61   void CheckProcBinding(const Symbol &, const ProcBindingDetails &);
62   void CheckObjectEntity(const Symbol &, const ObjectEntityDetails &);
63   void CheckPointerInitialization(const Symbol &);
64   void CheckArraySpec(const Symbol &, const ArraySpec &);
65   void CheckProcEntity(const Symbol &, const ProcEntityDetails &);
66   void CheckSubprogram(const Symbol &, const SubprogramDetails &);
67   void CheckAssumedTypeEntity(const Symbol &, const ObjectEntityDetails &);
68   void CheckDerivedType(const Symbol &, const DerivedTypeDetails &);
69   bool CheckFinal(
70       const Symbol &subroutine, SourceName, const Symbol &derivedType);
71   bool CheckDistinguishableFinals(const Symbol &f1, SourceName f1name,
72       const Symbol &f2, SourceName f2name, const Symbol &derivedType);
73   void CheckGeneric(const Symbol &, const GenericDetails &);
74   void CheckHostAssoc(const Symbol &, const HostAssocDetails &);
75   bool CheckDefinedOperator(
76       SourceName, GenericKind, const Symbol &, const Procedure &);
77   std::optional<parser::MessageFixedText> CheckNumberOfArgs(
78       const GenericKind &, std::size_t);
79   bool CheckDefinedOperatorArg(
80       const SourceName &, const Symbol &, const Procedure &, std::size_t);
81   bool CheckDefinedAssignment(const Symbol &, const Procedure &);
82   bool CheckDefinedAssignmentArg(const Symbol &, const DummyArgument &, int);
83   void CheckSpecificsAreDistinguishable(const Symbol &, const GenericDetails &);
84   void CheckEquivalenceSet(const EquivalenceSet &);
85   void CheckBlockData(const Scope &);
86   void CheckGenericOps(const Scope &);
87   bool CheckConflicting(const Symbol &, Attr, Attr);
88   void WarnMissingFinal(const Symbol &);
89   bool InPure() const {
90     return innermostSymbol_ && IsPureProcedure(*innermostSymbol_);
91   }
92   bool InElemental() const {
93     return innermostSymbol_ && innermostSymbol_->attrs().test(Attr::ELEMENTAL);
94   }
95   bool InFunction() const {
96     return innermostSymbol_ && IsFunction(*innermostSymbol_);
97   }
98   template <typename... A>
99   void SayWithDeclaration(const Symbol &symbol, A &&...x) {
100     if (parser::Message * msg{messages_.Say(std::forward<A>(x)...)}) {
101       if (messages_.at().begin() != symbol.name().begin()) {
102         evaluate::AttachDeclaration(*msg, symbol);
103       }
104     }
105   }
106   bool IsResultOkToDiffer(const FunctionResult &);
107   void CheckBindCName(const Symbol &);
108   // Check functions for defined I/O procedures
109   void CheckDefinedIoProc(
110       const Symbol &, const GenericDetails &, GenericKind::DefinedIo);
111   bool CheckDioDummyIsData(const Symbol &, const Symbol *, std::size_t);
112   void CheckDioDummyIsDerived(
113       const Symbol &, const Symbol &, GenericKind::DefinedIo ioKind);
114   void CheckDioDummyIsDefaultInteger(const Symbol &, const Symbol &);
115   void CheckDioDummyIsScalar(const Symbol &, const Symbol &);
116   void CheckDioDummyAttrs(const Symbol &, const Symbol &, Attr);
117   void CheckDioDtvArg(const Symbol &, const Symbol *, GenericKind::DefinedIo);
118   void CheckGenericVsIntrinsic(const Symbol &, const GenericDetails &);
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 (symbol.name().size() > common::maxNameLen) {
202     messages_.Say(symbol.name(),
203         "%s has length %d, which is greater than the maximum name length "
204         "%d"_port_en_US,
205         symbol.name(), symbol.name().size(), common::maxNameLen);
206   }
207   if (context_.HasError(symbol)) {
208     return;
209   }
210   auto restorer{messages_.SetLocation(symbol.name())};
211   context_.set_location(symbol.name());
212   const DeclTypeSpec *type{symbol.GetType()};
213   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
214   bool isDone{false};
215   common::visit(
216       common::visitors{
217           [&](const UseDetails &x) { isDone = true; },
218           [&](const HostAssocDetails &x) {
219             CheckHostAssoc(symbol, x);
220             isDone = true;
221           },
222           [&](const ProcBindingDetails &x) {
223             CheckProcBinding(symbol, x);
224             isDone = true;
225           },
226           [&](const ObjectEntityDetails &x) { CheckObjectEntity(symbol, x); },
227           [&](const ProcEntityDetails &x) { CheckProcEntity(symbol, x); },
228           [&](const SubprogramDetails &x) { CheckSubprogram(symbol, x); },
229           [&](const DerivedTypeDetails &x) { CheckDerivedType(symbol, x); },
230           [&](const GenericDetails &x) { CheckGeneric(symbol, x); },
231           [](const auto &) {},
232       },
233       symbol.details());
234   if (symbol.attrs().test(Attr::VOLATILE)) {
235     CheckVolatile(symbol, derived);
236   }
237   CheckBindCName(symbol);
238   if (isDone) {
239     return; // following checks do not apply
240   }
241   if (IsPointer(symbol)) {
242     CheckPointer(symbol);
243   }
244   if (InPure()) {
245     if (IsSaved(symbol)) {
246       if (IsInitialized(symbol)) {
247         messages_.Say(
248             "A pure subprogram may not initialize a variable"_err_en_US);
249       } else {
250         messages_.Say(
251             "A pure subprogram may not have a variable with the SAVE attribute"_err_en_US);
252       }
253     }
254     if (symbol.attrs().test(Attr::VOLATILE)) {
255       messages_.Say(
256           "A pure subprogram may not have a variable with the VOLATILE attribute"_err_en_US);
257     }
258     if (IsProcedure(symbol) && !IsPureProcedure(symbol) && IsDummy(symbol)) {
259       messages_.Say(
260           "A dummy procedure of a pure subprogram must be pure"_err_en_US);
261     }
262     if (!IsDummy(symbol) && !IsFunctionResult(symbol)) {
263       if (IsPolymorphicAllocatable(symbol)) {
264         SayWithDeclaration(symbol,
265             "Deallocation of polymorphic object '%s' is not permitted in a pure subprogram"_err_en_US,
266             symbol.name());
267       } else if (derived) {
268         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
269           SayWithDeclaration(*bad,
270               "Deallocation of polymorphic object '%s%s' is not permitted in a pure subprogram"_err_en_US,
271               symbol.name(), bad.BuildResultDesignatorName());
272         }
273       }
274     }
275   }
276   if (type) { // Section 7.2, paragraph 7
277     bool canHaveAssumedParameter{IsNamedConstant(symbol) ||
278         (IsAssumedLengthCharacter(symbol) && // C722
279             IsExternal(symbol)) ||
280         symbol.test(Symbol::Flag::ParentComp)};
281     if (!IsStmtFunctionDummy(symbol)) { // C726
282       if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
283         canHaveAssumedParameter |= object->isDummy() ||
284             (object->isFuncResult() &&
285                 type->category() == DeclTypeSpec::Character) ||
286             IsStmtFunctionResult(symbol); // Avoids multiple messages
287       } else {
288         canHaveAssumedParameter |= symbol.has<AssocEntityDetails>();
289       }
290     }
291     Check(*type, canHaveAssumedParameter);
292     if (InPure() && InFunction() && IsFunctionResult(symbol)) {
293       if (derived && HasImpureFinal(*derived)) { // C1584
294         messages_.Say(
295             "Result of pure function may not have an impure FINAL subroutine"_err_en_US);
296       }
297       if (type->IsPolymorphic() && IsAllocatable(symbol)) { // C1585
298         messages_.Say(
299             "Result of pure function may not be both polymorphic and ALLOCATABLE"_err_en_US);
300       }
301       if (derived) {
302         if (auto bad{FindPolymorphicAllocatableUltimateComponent(*derived)}) {
303           SayWithDeclaration(*bad,
304               "Result of pure function may not have polymorphic ALLOCATABLE ultimate component '%s'"_err_en_US,
305               bad.BuildResultDesignatorName());
306         }
307       }
308     }
309   }
310   if (IsAssumedLengthCharacter(symbol) && IsExternal(symbol)) { // C723
311     if (symbol.attrs().test(Attr::RECURSIVE)) {
312       messages_.Say(
313           "An assumed-length CHARACTER(*) function cannot be RECURSIVE"_err_en_US);
314     }
315     if (symbol.Rank() > 0) {
316       messages_.Say(
317           "An assumed-length CHARACTER(*) function cannot return an array"_err_en_US);
318     }
319     if (symbol.attrs().test(Attr::PURE)) {
320       messages_.Say(
321           "An assumed-length CHARACTER(*) function cannot be PURE"_err_en_US);
322     }
323     if (symbol.attrs().test(Attr::ELEMENTAL)) {
324       messages_.Say(
325           "An assumed-length CHARACTER(*) function cannot be ELEMENTAL"_err_en_US);
326     }
327     if (const Symbol * result{FindFunctionResult(symbol)}) {
328       if (IsPointer(*result)) {
329         messages_.Say(
330             "An assumed-length CHARACTER(*) function cannot return a POINTER"_err_en_US);
331       }
332     }
333   }
334   if (symbol.attrs().test(Attr::VALUE)) {
335     CheckValue(symbol, derived);
336   }
337   if (symbol.attrs().test(Attr::CONTIGUOUS) && IsPointer(symbol) &&
338       symbol.Rank() == 0) { // C830
339     messages_.Say("CONTIGUOUS POINTER must be an array"_err_en_US);
340   }
341   if (IsDummy(symbol)) {
342     if (IsNamedConstant(symbol)) {
343       messages_.Say(
344           "A dummy argument may not also be a named constant"_err_en_US);
345     }
346     if (!symbol.test(Symbol::Flag::InDataStmt) /*caught elsewhere*/ &&
347         IsSaved(symbol)) {
348       messages_.Say(
349           "A dummy argument may not have the SAVE attribute"_err_en_US);
350     }
351   } else if (IsFunctionResult(symbol)) {
352     if (!symbol.test(Symbol::Flag::InDataStmt) /*caught elsewhere*/ &&
353         IsSaved(symbol)) {
354       messages_.Say(
355           "A function result may not have the SAVE attribute"_err_en_US);
356     }
357   }
358   if (symbol.owner().IsDerivedType() &&
359       (symbol.attrs().test(Attr::CONTIGUOUS) &&
360           !(IsPointer(symbol) && symbol.Rank() > 0))) { // C752
361     messages_.Say(
362         "A CONTIGUOUS component must be an array with the POINTER attribute"_err_en_US);
363   }
364   if (symbol.owner().IsModule() && IsAutomatic(symbol)) {
365     messages_.Say(
366         "Automatic data object '%s' may not appear in the specification part"
367         " of a module"_err_en_US,
368         symbol.name());
369   }
370 }
371 
372 void CheckHelper::CheckValue(
373     const Symbol &symbol, const DerivedTypeSpec *derived) { // C863 - C865
374   if (!IsDummy(symbol)) {
375     messages_.Say(
376         "VALUE attribute may apply only to a dummy argument"_err_en_US);
377   }
378   if (IsProcedure(symbol)) {
379     messages_.Say(
380         "VALUE attribute may apply only to a dummy data object"_err_en_US);
381   }
382   if (IsAssumedSizeArray(symbol)) {
383     messages_.Say(
384         "VALUE attribute may not apply to an assumed-size array"_err_en_US);
385   }
386   if (evaluate::IsCoarray(symbol)) {
387     messages_.Say("VALUE attribute may not apply to a coarray"_err_en_US);
388   }
389   if (IsAllocatable(symbol)) {
390     messages_.Say("VALUE attribute may not apply to an ALLOCATABLE"_err_en_US);
391   } else if (IsPointer(symbol)) {
392     messages_.Say("VALUE attribute may not apply to a POINTER"_err_en_US);
393   }
394   if (IsIntentInOut(symbol)) {
395     messages_.Say(
396         "VALUE attribute may not apply to an INTENT(IN OUT) argument"_err_en_US);
397   } else if (IsIntentOut(symbol)) {
398     messages_.Say(
399         "VALUE attribute may not apply to an INTENT(OUT) argument"_err_en_US);
400   }
401   if (symbol.attrs().test(Attr::VOLATILE)) {
402     messages_.Say("VALUE attribute may not apply to a VOLATILE"_err_en_US);
403   }
404   if (innermostSymbol_ && IsBindCProcedure(*innermostSymbol_) &&
405       IsOptional(symbol)) {
406     messages_.Say(
407         "VALUE attribute may not apply to an OPTIONAL in a BIND(C) procedure"_err_en_US);
408   }
409   if (derived) {
410     if (FindCoarrayUltimateComponent(*derived)) {
411       messages_.Say(
412           "VALUE attribute may not apply to a type with a coarray ultimate component"_err_en_US);
413     }
414   }
415 }
416 
417 void CheckHelper::CheckAssumedTypeEntity( // C709
418     const Symbol &symbol, const ObjectEntityDetails &details) {
419   if (const DeclTypeSpec * type{symbol.GetType()};
420       type && type->category() == DeclTypeSpec::TypeStar) {
421     if (!IsDummy(symbol)) {
422       messages_.Say(
423           "Assumed-type entity '%s' must be a dummy argument"_err_en_US,
424           symbol.name());
425     } else {
426       if (symbol.attrs().test(Attr::ALLOCATABLE)) {
427         messages_.Say("Assumed-type argument '%s' cannot have the ALLOCATABLE"
428                       " attribute"_err_en_US,
429             symbol.name());
430       }
431       if (symbol.attrs().test(Attr::POINTER)) {
432         messages_.Say("Assumed-type argument '%s' cannot have the POINTER"
433                       " attribute"_err_en_US,
434             symbol.name());
435       }
436       if (symbol.attrs().test(Attr::VALUE)) {
437         messages_.Say("Assumed-type argument '%s' cannot have the VALUE"
438                       " attribute"_err_en_US,
439             symbol.name());
440       }
441       if (symbol.attrs().test(Attr::INTENT_OUT)) {
442         messages_.Say(
443             "Assumed-type argument '%s' cannot be INTENT(OUT)"_err_en_US,
444             symbol.name());
445       }
446       if (evaluate::IsCoarray(symbol)) {
447         messages_.Say(
448             "Assumed-type argument '%s' cannot be a coarray"_err_en_US,
449             symbol.name());
450       }
451       if (details.IsArray() && details.shape().IsExplicitShape()) {
452         messages_.Say(
453             "Assumed-type array argument 'arg8' must be assumed shape,"
454             " assumed size, or assumed rank"_err_en_US,
455             symbol.name());
456       }
457     }
458   }
459 }
460 
461 void CheckHelper::CheckObjectEntity(
462     const Symbol &symbol, const ObjectEntityDetails &details) {
463   CheckArraySpec(symbol, details.shape());
464   Check(details.shape());
465   Check(details.coshape());
466   if (details.shape().Rank() > common::maxRank) {
467     messages_.Say(
468         "'%s' has rank %d, which is greater than the maximum supported rank %d"_err_en_US,
469         symbol.name(), details.shape().Rank(), common::maxRank);
470   } else if (details.shape().Rank() + details.coshape().Rank() >
471       common::maxRank) {
472     messages_.Say(
473         "'%s' has rank %d and corank %d, whose sum is greater than the maximum supported rank %d"_err_en_US,
474         symbol.name(), details.shape().Rank(), details.coshape().Rank(),
475         common::maxRank);
476   }
477   CheckAssumedTypeEntity(symbol, details);
478   WarnMissingFinal(symbol);
479   if (!details.coshape().empty()) {
480     bool isDeferredCoshape{details.coshape().CanBeDeferredShape()};
481     if (IsAllocatable(symbol)) {
482       if (!isDeferredCoshape) { // C827
483         messages_.Say("'%s' is an ALLOCATABLE coarray and must have a deferred"
484                       " coshape"_err_en_US,
485             symbol.name());
486       }
487     } else if (symbol.owner().IsDerivedType()) { // C746
488       std::string deferredMsg{
489           isDeferredCoshape ? "" : " and have a deferred coshape"};
490       messages_.Say("Component '%s' is a coarray and must have the ALLOCATABLE"
491                     " attribute%s"_err_en_US,
492           symbol.name(), deferredMsg);
493     } else {
494       if (!details.coshape().CanBeAssumedSize()) { // C828
495         messages_.Say(
496             "'%s' is a non-ALLOCATABLE coarray and must have an explicit coshape"_err_en_US,
497             symbol.name());
498       }
499     }
500     if (const DeclTypeSpec * type{details.type()}) {
501       if (IsBadCoarrayType(type->AsDerived())) { // C747 & C824
502         messages_.Say(
503             "Coarray '%s' may not have type TEAM_TYPE, C_PTR, or C_FUNPTR"_err_en_US,
504             symbol.name());
505       }
506     }
507   }
508   if (details.isDummy()) {
509     if (symbol.attrs().test(Attr::INTENT_OUT)) {
510       if (FindUltimateComponent(symbol, [](const Symbol &x) {
511             return evaluate::IsCoarray(x) && IsAllocatable(x);
512           })) { // C846
513         messages_.Say(
514             "An INTENT(OUT) dummy argument may not be, or contain, an ALLOCATABLE coarray"_err_en_US);
515       }
516       if (IsOrContainsEventOrLockComponent(symbol)) { // C847
517         messages_.Say(
518             "An INTENT(OUT) dummy argument may not be, or contain, EVENT_TYPE or LOCK_TYPE"_err_en_US);
519       }
520     }
521     if (InPure() && !IsStmtFunction(DEREF(innermostSymbol_)) &&
522         !IsPointer(symbol) && !IsIntentIn(symbol) &&
523         !symbol.attrs().test(Attr::VALUE)) {
524       if (InFunction()) { // C1583
525         messages_.Say(
526             "non-POINTER dummy argument of pure function must be INTENT(IN) or VALUE"_err_en_US);
527       } else if (IsIntentOut(symbol)) {
528         if (const DeclTypeSpec * type{details.type()}) {
529           if (type && type->IsPolymorphic()) { // C1588
530             messages_.Say(
531                 "An INTENT(OUT) dummy argument of a pure subroutine may not be polymorphic"_err_en_US);
532           } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
533             if (FindUltimateComponent(*derived, [](const Symbol &x) {
534                   const DeclTypeSpec *type{x.GetType()};
535                   return type && type->IsPolymorphic();
536                 })) { // C1588
537               messages_.Say(
538                   "An INTENT(OUT) dummy argument of a pure subroutine may not have a polymorphic ultimate component"_err_en_US);
539             }
540             if (HasImpureFinal(*derived)) { // C1587
541               messages_.Say(
542                   "An INTENT(OUT) dummy argument of a pure subroutine may not have an impure FINAL subroutine"_err_en_US);
543             }
544           }
545         }
546       } else if (!IsIntentInOut(symbol)) { // C1586
547         messages_.Say(
548             "non-POINTER dummy argument of pure subroutine must have INTENT() or VALUE attribute"_err_en_US);
549       }
550     }
551   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
552       symbol.attrs().test(Attr::INTENT_OUT) ||
553       symbol.attrs().test(Attr::INTENT_INOUT)) {
554     messages_.Say("INTENT attributes may apply only to a dummy "
555                   "argument"_err_en_US); // C843
556   } else if (IsOptional(symbol)) {
557     messages_.Say("OPTIONAL attribute may apply only to a dummy "
558                   "argument"_err_en_US); // C849
559   }
560   if (InElemental()) {
561     if (details.isDummy()) { // C15100
562       if (details.shape().Rank() > 0) {
563         messages_.Say(
564             "A dummy argument of an ELEMENTAL procedure must be scalar"_err_en_US);
565       }
566       if (IsAllocatable(symbol)) {
567         messages_.Say(
568             "A dummy argument of an ELEMENTAL procedure may not be ALLOCATABLE"_err_en_US);
569       }
570       if (evaluate::IsCoarray(symbol)) {
571         messages_.Say(
572             "A dummy argument of an ELEMENTAL procedure may not be a coarray"_err_en_US);
573       }
574       if (IsPointer(symbol)) {
575         messages_.Say(
576             "A dummy argument of an ELEMENTAL procedure may not be a POINTER"_err_en_US);
577       }
578       if (!symbol.attrs().HasAny(Attrs{Attr::VALUE, Attr::INTENT_IN,
579               Attr::INTENT_INOUT, Attr::INTENT_OUT})) { // C15102
580         messages_.Say(
581             "A dummy argument of an ELEMENTAL procedure must have an INTENT() or VALUE attribute"_err_en_US);
582       }
583     } else if (IsFunctionResult(symbol)) { // C15101
584       if (details.shape().Rank() > 0) {
585         messages_.Say(
586             "The result of an ELEMENTAL function must be scalar"_err_en_US);
587       }
588       if (IsAllocatable(symbol)) {
589         messages_.Say(
590             "The result of an ELEMENTAL function may not be ALLOCATABLE"_err_en_US);
591       }
592       if (IsPointer(symbol)) {
593         messages_.Say(
594             "The result of an ELEMENTAL function may not be a POINTER"_err_en_US);
595       }
596     }
597   }
598   if (HasDeclarationInitializer(symbol)) { // C808; ignore DATA initialization
599     CheckPointerInitialization(symbol);
600     if (IsAutomatic(symbol)) {
601       messages_.Say(
602           "An automatic variable or component must not be initialized"_err_en_US);
603     } else if (IsDummy(symbol)) {
604       messages_.Say("A dummy argument must not be initialized"_err_en_US);
605     } else if (IsFunctionResult(symbol)) {
606       messages_.Say("A function result must not be initialized"_err_en_US);
607     } else if (IsInBlankCommon(symbol)) {
608       messages_.Say(
609           "A variable in blank COMMON should not be initialized"_port_en_US);
610     }
611   }
612   if (symbol.owner().kind() == Scope::Kind::BlockData) {
613     if (IsAllocatable(symbol)) {
614       messages_.Say(
615           "An ALLOCATABLE variable may not appear in a BLOCK DATA subprogram"_err_en_US);
616     } else if (IsInitialized(symbol) && !FindCommonBlockContaining(symbol)) {
617       messages_.Say(
618           "An initialized variable in BLOCK DATA must be in a COMMON block"_err_en_US);
619     }
620   }
621   if (const DeclTypeSpec * type{details.type()}) { // C708
622     if (type->IsPolymorphic() &&
623         !(type->IsAssumedType() || IsAllocatableOrPointer(symbol) ||
624             IsDummy(symbol))) {
625       messages_.Say("CLASS entity '%s' must be a dummy argument or have "
626                     "ALLOCATABLE or POINTER attribute"_err_en_US,
627           symbol.name());
628     }
629   }
630 }
631 
632 void CheckHelper::CheckPointerInitialization(const Symbol &symbol) {
633   if (IsPointer(symbol) && !context_.HasError(symbol) &&
634       !scopeIsUninstantiatedPDT_) {
635     if (const auto *object{symbol.detailsIf<ObjectEntityDetails>()}) {
636       if (object->init()) { // C764, C765; C808
637         if (auto designator{evaluate::AsGenericExpr(symbol)}) {
638           auto restorer{messages_.SetLocation(symbol.name())};
639           context_.set_location(symbol.name());
640           CheckInitialTarget(foldingContext_, *designator, *object->init());
641         }
642       }
643     } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}) {
644       if (proc->init() && *proc->init()) {
645         // C1519 - must be nonelemental external or module procedure,
646         // or an unrestricted specific intrinsic function.
647         const Symbol &ultimate{(*proc->init())->GetUltimate()};
648         if (ultimate.attrs().test(Attr::INTRINSIC)) {
649           if (const auto intrinsic{
650                   context_.intrinsics().IsSpecificIntrinsicFunction(
651                       ultimate.name().ToString())};
652               !intrinsic || intrinsic->isRestrictedSpecific) { // C1030
653             context_.Say(
654                 "Intrinsic procedure '%s' is not an unrestricted specific "
655                 "intrinsic permitted for use as the initializer for procedure "
656                 "pointer '%s'"_err_en_US,
657                 ultimate.name(), symbol.name());
658           }
659         } else if (!ultimate.attrs().test(Attr::EXTERNAL) &&
660             ultimate.owner().kind() != Scope::Kind::Module) {
661           context_.Say("Procedure pointer '%s' initializer '%s' is neither "
662                        "an external nor a module procedure"_err_en_US,
663               symbol.name(), ultimate.name());
664         } else if (ultimate.attrs().test(Attr::ELEMENTAL)) {
665           context_.Say("Procedure pointer '%s' cannot be initialized with the "
666                        "elemental procedure '%s"_err_en_US,
667               symbol.name(), ultimate.name());
668         } else {
669           // TODO: Check the "shalls" in the 15.4.3.6 paragraphs 7-10.
670         }
671       }
672     }
673   }
674 }
675 
676 // The six different kinds of array-specs:
677 //   array-spec     -> explicit-shape-list | deferred-shape-list
678 //                     | assumed-shape-list | implied-shape-list
679 //                     | assumed-size | assumed-rank
680 //   explicit-shape -> [ lb : ] ub
681 //   deferred-shape -> :
682 //   assumed-shape  -> [ lb ] :
683 //   implied-shape  -> [ lb : ] *
684 //   assumed-size   -> [ explicit-shape-list , ] [ lb : ] *
685 //   assumed-rank   -> ..
686 // Note:
687 // - deferred-shape is also an assumed-shape
688 // - A single "*" or "lb:*" might be assumed-size or implied-shape-list
689 void CheckHelper::CheckArraySpec(
690     const Symbol &symbol, const ArraySpec &arraySpec) {
691   if (arraySpec.Rank() == 0) {
692     return;
693   }
694   bool isExplicit{arraySpec.IsExplicitShape()};
695   bool canBeDeferred{arraySpec.CanBeDeferredShape()};
696   bool canBeImplied{arraySpec.CanBeImpliedShape()};
697   bool canBeAssumedShape{arraySpec.CanBeAssumedShape()};
698   bool canBeAssumedSize{arraySpec.CanBeAssumedSize()};
699   bool isAssumedRank{arraySpec.IsAssumedRank()};
700   std::optional<parser::MessageFixedText> msg;
701   if (symbol.test(Symbol::Flag::CrayPointee) && !isExplicit &&
702       !canBeAssumedSize) {
703     msg = "Cray pointee '%s' must have must have explicit shape or"
704           " assumed size"_err_en_US;
705   } else if (IsAllocatableOrPointer(symbol) && !canBeDeferred &&
706       !isAssumedRank) {
707     if (symbol.owner().IsDerivedType()) { // C745
708       if (IsAllocatable(symbol)) {
709         msg = "Allocatable array component '%s' must have"
710               " deferred shape"_err_en_US;
711       } else {
712         msg = "Array pointer component '%s' must have deferred shape"_err_en_US;
713       }
714     } else {
715       if (IsAllocatable(symbol)) { // C832
716         msg = "Allocatable array '%s' must have deferred shape or"
717               " assumed rank"_err_en_US;
718       } else {
719         msg = "Array pointer '%s' must have deferred shape or"
720               " assumed rank"_err_en_US;
721       }
722     }
723   } else if (IsDummy(symbol)) {
724     if (canBeImplied && !canBeAssumedSize) { // C836
725       msg = "Dummy array argument '%s' may not have implied shape"_err_en_US;
726     }
727   } else if (canBeAssumedShape && !canBeDeferred) {
728     msg = "Assumed-shape array '%s' must be a dummy argument"_err_en_US;
729   } else if (canBeAssumedSize && !canBeImplied) { // C833
730     msg = "Assumed-size array '%s' must be a dummy argument"_err_en_US;
731   } else if (isAssumedRank) { // C837
732     msg = "Assumed-rank array '%s' must be a dummy argument"_err_en_US;
733   } else if (canBeImplied) {
734     if (!IsNamedConstant(symbol)) { // C835, C836
735       msg = "Implied-shape array '%s' must be a named constant or a "
736             "dummy argument"_err_en_US;
737     }
738   } else if (IsNamedConstant(symbol)) {
739     if (!isExplicit && !canBeImplied) {
740       msg = "Named constant '%s' array must have constant or"
741             " implied shape"_err_en_US;
742     }
743   } else if (!IsAllocatableOrPointer(symbol) && !isExplicit) {
744     if (symbol.owner().IsDerivedType()) { // C749
745       msg = "Component array '%s' without ALLOCATABLE or POINTER attribute must"
746             " have explicit shape"_err_en_US;
747     } else { // C816
748       msg = "Array '%s' without ALLOCATABLE or POINTER attribute must have"
749             " explicit shape"_err_en_US;
750     }
751   }
752   if (msg) {
753     context_.Say(std::move(*msg), symbol.name());
754   }
755 }
756 
757 void CheckHelper::CheckProcEntity(
758     const Symbol &symbol, const ProcEntityDetails &details) {
759   if (details.isDummy()) {
760     if (!symbol.attrs().test(Attr::POINTER) && // C843
761         (symbol.attrs().test(Attr::INTENT_IN) ||
762             symbol.attrs().test(Attr::INTENT_OUT) ||
763             symbol.attrs().test(Attr::INTENT_INOUT))) {
764       messages_.Say("A dummy procedure without the POINTER attribute"
765                     " may not have an INTENT attribute"_err_en_US);
766     }
767     if (InElemental()) { // C15100
768       messages_.Say(
769           "An ELEMENTAL subprogram may not have a dummy procedure"_err_en_US);
770     }
771     const Symbol *interface { details.interface().symbol() };
772     if (!symbol.attrs().test(Attr::INTRINSIC) &&
773         (symbol.attrs().test(Attr::ELEMENTAL) ||
774             (interface && !interface->attrs().test(Attr::INTRINSIC) &&
775                 interface->attrs().test(Attr::ELEMENTAL)))) {
776       // There's no explicit constraint or "shall" that we can find in the
777       // standard for this check, but it seems to be implied in multiple
778       // sites, and ELEMENTAL non-intrinsic actual arguments *are*
779       // explicitly forbidden.  But we allow "PROCEDURE(SIN)::dummy"
780       // because it is explicitly legal to *pass* the specific intrinsic
781       // function SIN as an actual argument.
782       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
783     }
784   } else if (symbol.attrs().test(Attr::INTENT_IN) ||
785       symbol.attrs().test(Attr::INTENT_OUT) ||
786       symbol.attrs().test(Attr::INTENT_INOUT)) {
787     messages_.Say("INTENT attributes may apply only to a dummy "
788                   "argument"_err_en_US); // C843
789   } else if (IsOptional(symbol)) {
790     messages_.Say("OPTIONAL attribute may apply only to a dummy "
791                   "argument"_err_en_US); // C849
792   } else if (symbol.owner().IsDerivedType()) {
793     if (!symbol.attrs().test(Attr::POINTER)) { // C756
794       const auto &name{symbol.name()};
795       messages_.Say(name,
796           "Procedure component '%s' must have POINTER attribute"_err_en_US,
797           name);
798     }
799     CheckPassArg(symbol, details.interface().symbol(), details);
800   }
801   if (symbol.attrs().test(Attr::POINTER)) {
802     CheckPointerInitialization(symbol);
803     if (const Symbol * interface{details.interface().symbol()}) {
804       if (interface->attrs().test(Attr::INTRINSIC)) {
805         if (const auto intrinsic{
806                 context_.intrinsics().IsSpecificIntrinsicFunction(
807                     interface->name().ToString())};
808             !intrinsic || intrinsic->isRestrictedSpecific) { // C1515
809           messages_.Say(
810               "Intrinsic procedure '%s' is not an unrestricted specific "
811               "intrinsic permitted for use as the definition of the interface "
812               "to procedure pointer '%s'"_err_en_US,
813               interface->name(), symbol.name());
814         }
815       } else if (interface->attrs().test(Attr::ELEMENTAL)) {
816         messages_.Say("Procedure pointer '%s' may not be ELEMENTAL"_err_en_US,
817             symbol.name()); // C1517
818       }
819     }
820   } else if (symbol.attrs().test(Attr::SAVE)) {
821     messages_.Say(
822         "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US,
823         symbol.name());
824   }
825 }
826 
827 // When a module subprogram has the MODULE prefix the following must match
828 // with the corresponding separate module procedure interface body:
829 // - C1549: characteristics and dummy argument names
830 // - C1550: binding label
831 // - C1551: NON_RECURSIVE prefix
832 class SubprogramMatchHelper {
833 public:
834   explicit SubprogramMatchHelper(CheckHelper &checkHelper)
835       : checkHelper{checkHelper} {}
836 
837   void Check(const Symbol &, const Symbol &);
838 
839 private:
840   SemanticsContext &context() { return checkHelper.context(); }
841   void CheckDummyArg(const Symbol &, const Symbol &, const DummyArgument &,
842       const DummyArgument &);
843   void CheckDummyDataObject(const Symbol &, const Symbol &,
844       const DummyDataObject &, const DummyDataObject &);
845   void CheckDummyProcedure(const Symbol &, const Symbol &,
846       const DummyProcedure &, const DummyProcedure &);
847   bool CheckSameIntent(
848       const Symbol &, const Symbol &, common::Intent, common::Intent);
849   template <typename... A>
850   void Say(
851       const Symbol &, const Symbol &, parser::MessageFixedText &&, A &&...);
852   template <typename ATTRS>
853   bool CheckSameAttrs(const Symbol &, const Symbol &, ATTRS, ATTRS);
854   bool ShapesAreCompatible(const DummyDataObject &, const DummyDataObject &);
855   evaluate::Shape FoldShape(const evaluate::Shape &);
856   std::string AsFortran(DummyDataObject::Attr attr) {
857     return parser::ToUpperCaseLetters(DummyDataObject::EnumToString(attr));
858   }
859   std::string AsFortran(DummyProcedure::Attr attr) {
860     return parser::ToUpperCaseLetters(DummyProcedure::EnumToString(attr));
861   }
862 
863   CheckHelper &checkHelper;
864 };
865 
866 // 15.6.2.6 para 3 - can the result of an ENTRY differ from its function?
867 bool CheckHelper::IsResultOkToDiffer(const FunctionResult &result) {
868   if (result.attrs.test(FunctionResult::Attr::Allocatable) ||
869       result.attrs.test(FunctionResult::Attr::Pointer)) {
870     return false;
871   }
872   const auto *typeAndShape{result.GetTypeAndShape()};
873   if (!typeAndShape || typeAndShape->Rank() != 0) {
874     return false;
875   }
876   auto category{typeAndShape->type().category()};
877   if (category == TypeCategory::Character ||
878       category == TypeCategory::Derived) {
879     return false;
880   }
881   int kind{typeAndShape->type().kind()};
882   return kind == context_.GetDefaultKind(category) ||
883       (category == TypeCategory::Real &&
884           kind == context_.doublePrecisionKind());
885 }
886 
887 void CheckHelper::CheckSubprogram(
888     const Symbol &symbol, const SubprogramDetails &details) {
889   if (const Symbol * iface{FindSeparateModuleSubprogramInterface(&symbol)}) {
890     SubprogramMatchHelper{*this}.Check(symbol, *iface);
891   }
892   if (const Scope * entryScope{details.entryScope()}) {
893     // ENTRY 15.6.2.6, esp. C1571
894     std::optional<parser::MessageFixedText> error;
895     const Symbol *subprogram{entryScope->symbol()};
896     const SubprogramDetails *subprogramDetails{nullptr};
897     if (subprogram) {
898       subprogramDetails = subprogram->detailsIf<SubprogramDetails>();
899     }
900     if (entryScope->kind() != Scope::Kind::Subprogram) {
901       error = "ENTRY may appear only in a subroutine or function"_err_en_US;
902     } else if (!(entryScope->parent().IsGlobal() ||
903                    entryScope->parent().IsModule() ||
904                    entryScope->parent().IsSubmodule())) {
905       error = "ENTRY may not appear in an internal subprogram"_err_en_US;
906     } else if (FindSeparateModuleSubprogramInterface(subprogram)) {
907       error = "ENTRY may not appear in a separate module procedure"_err_en_US;
908     } else if (subprogramDetails && details.isFunction() &&
909         subprogramDetails->isFunction() &&
910         !context_.HasError(details.result()) &&
911         !context_.HasError(subprogramDetails->result())) {
912       auto result{FunctionResult::Characterize(
913           details.result(), context_.foldingContext())};
914       auto subpResult{FunctionResult::Characterize(
915           subprogramDetails->result(), context_.foldingContext())};
916       if (result && subpResult && *result != *subpResult &&
917           (!IsResultOkToDiffer(*result) || !IsResultOkToDiffer(*subpResult))) {
918         error =
919             "Result of ENTRY is not compatible with result of containing function"_err_en_US;
920       }
921     }
922     if (error) {
923       if (auto *msg{messages_.Say(symbol.name(), *error)}) {
924         if (subprogram) {
925           msg->Attach(subprogram->name(), "Containing subprogram"_en_US);
926         }
927       }
928     }
929   }
930   if (symbol.attrs().test(Attr::ELEMENTAL)) {
931     // See comment on the similar check in CheckProcEntity()
932     if (details.isDummy()) {
933       messages_.Say("A dummy procedure may not be ELEMENTAL"_err_en_US);
934     } else {
935       for (const Symbol *dummy : details.dummyArgs()) {
936         if (!dummy) { // C15100
937           messages_.Say(
938               "An ELEMENTAL subroutine may not have an alternate return dummy argument"_err_en_US);
939         }
940       }
941     }
942   }
943 }
944 
945 void CheckHelper::CheckDerivedType(
946     const Symbol &derivedType, const DerivedTypeDetails &details) {
947   if (details.isForwardReferenced() && !context_.HasError(derivedType)) {
948     messages_.Say("The derived type '%s' has not been defined"_err_en_US,
949         derivedType.name());
950   }
951   const Scope *scope{derivedType.scope()};
952   if (!scope) {
953     CHECK(details.isForwardReferenced());
954     return;
955   }
956   CHECK(scope->symbol() == &derivedType);
957   CHECK(scope->IsDerivedType());
958   if (derivedType.attrs().test(Attr::ABSTRACT) && // C734
959       (derivedType.attrs().test(Attr::BIND_C) || details.sequence())) {
960     messages_.Say("An ABSTRACT derived type must be extensible"_err_en_US);
961   }
962   if (const DeclTypeSpec * parent{FindParentTypeSpec(derivedType)}) {
963     const DerivedTypeSpec *parentDerived{parent->AsDerived()};
964     if (!IsExtensibleType(parentDerived)) { // C705
965       messages_.Say("The parent type is not extensible"_err_en_US);
966     }
967     if (!derivedType.attrs().test(Attr::ABSTRACT) && parentDerived &&
968         parentDerived->typeSymbol().attrs().test(Attr::ABSTRACT)) {
969       ScopeComponentIterator components{*parentDerived};
970       for (const Symbol &component : components) {
971         if (component.attrs().test(Attr::DEFERRED)) {
972           if (scope->FindComponent(component.name()) == &component) {
973             SayWithDeclaration(component,
974                 "Non-ABSTRACT extension of ABSTRACT derived type '%s' lacks a binding for DEFERRED procedure '%s'"_err_en_US,
975                 parentDerived->typeSymbol().name(), component.name());
976           }
977         }
978       }
979     }
980     DerivedTypeSpec derived{derivedType.name(), derivedType};
981     derived.set_scope(*scope);
982     if (FindCoarrayUltimateComponent(derived) && // C736
983         !(parentDerived && FindCoarrayUltimateComponent(*parentDerived))) {
984       messages_.Say(
985           "Type '%s' has a coarray ultimate component so the type at the base "
986           "of its type extension chain ('%s') must be a type that has a "
987           "coarray ultimate component"_err_en_US,
988           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
989     }
990     if (FindEventOrLockPotentialComponent(derived) && // C737
991         !(FindEventOrLockPotentialComponent(*parentDerived) ||
992             IsEventTypeOrLockType(parentDerived))) {
993       messages_.Say(
994           "Type '%s' has an EVENT_TYPE or LOCK_TYPE component, so the type "
995           "at the base of its type extension chain ('%s') must either have an "
996           "EVENT_TYPE or LOCK_TYPE component, or be EVENT_TYPE or "
997           "LOCK_TYPE"_err_en_US,
998           derivedType.name(), scope->GetDerivedTypeBase().GetSymbol()->name());
999     }
1000   }
1001   if (HasIntrinsicTypeName(derivedType)) { // C729
1002     messages_.Say("A derived type name cannot be the name of an intrinsic"
1003                   " type"_err_en_US);
1004   }
1005   std::map<SourceName, SymbolRef> previous;
1006   for (const auto &pair : details.finals()) {
1007     SourceName source{pair.first};
1008     const Symbol &ref{*pair.second};
1009     if (CheckFinal(ref, source, derivedType) &&
1010         std::all_of(previous.begin(), previous.end(),
1011             [&](std::pair<SourceName, SymbolRef> prev) {
1012               return CheckDistinguishableFinals(
1013                   ref, source, *prev.second, prev.first, derivedType);
1014             })) {
1015       previous.emplace(source, ref);
1016     }
1017   }
1018 }
1019 
1020 // C786
1021 bool CheckHelper::CheckFinal(
1022     const Symbol &subroutine, SourceName finalName, const Symbol &derivedType) {
1023   if (!IsModuleProcedure(subroutine)) {
1024     SayWithDeclaration(subroutine, finalName,
1025         "FINAL subroutine '%s' of derived type '%s' must be a module procedure"_err_en_US,
1026         subroutine.name(), derivedType.name());
1027     return false;
1028   }
1029   const Procedure *proc{Characterize(subroutine)};
1030   if (!proc) {
1031     return false; // error recovery
1032   }
1033   if (!proc->IsSubroutine()) {
1034     SayWithDeclaration(subroutine, finalName,
1035         "FINAL subroutine '%s' of derived type '%s' must be a subroutine"_err_en_US,
1036         subroutine.name(), derivedType.name());
1037     return false;
1038   }
1039   if (proc->dummyArguments.size() != 1) {
1040     SayWithDeclaration(subroutine, finalName,
1041         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument"_err_en_US,
1042         subroutine.name(), derivedType.name());
1043     return false;
1044   }
1045   const auto &arg{proc->dummyArguments[0]};
1046   const Symbol *errSym{&subroutine};
1047   if (const auto *details{subroutine.detailsIf<SubprogramDetails>()}) {
1048     if (!details->dummyArgs().empty()) {
1049       if (const Symbol * argSym{details->dummyArgs()[0]}) {
1050         errSym = argSym;
1051       }
1052     }
1053   }
1054   const auto *ddo{std::get_if<DummyDataObject>(&arg.u)};
1055   if (!ddo) {
1056     SayWithDeclaration(subroutine, finalName,
1057         "FINAL subroutine '%s' of derived type '%s' must have a single dummy argument that is a data object"_err_en_US,
1058         subroutine.name(), derivedType.name());
1059     return false;
1060   }
1061   bool ok{true};
1062   if (arg.IsOptional()) {
1063     SayWithDeclaration(*errSym, finalName,
1064         "FINAL subroutine '%s' of derived type '%s' must not have an OPTIONAL dummy argument"_err_en_US,
1065         subroutine.name(), derivedType.name());
1066     ok = false;
1067   }
1068   if (ddo->attrs.test(DummyDataObject::Attr::Allocatable)) {
1069     SayWithDeclaration(*errSym, finalName,
1070         "FINAL subroutine '%s' of derived type '%s' must not have an ALLOCATABLE dummy argument"_err_en_US,
1071         subroutine.name(), derivedType.name());
1072     ok = false;
1073   }
1074   if (ddo->attrs.test(DummyDataObject::Attr::Pointer)) {
1075     SayWithDeclaration(*errSym, finalName,
1076         "FINAL subroutine '%s' of derived type '%s' must not have a POINTER dummy argument"_err_en_US,
1077         subroutine.name(), derivedType.name());
1078     ok = false;
1079   }
1080   if (ddo->intent == common::Intent::Out) {
1081     SayWithDeclaration(*errSym, finalName,
1082         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with INTENT(OUT)"_err_en_US,
1083         subroutine.name(), derivedType.name());
1084     ok = false;
1085   }
1086   if (ddo->attrs.test(DummyDataObject::Attr::Value)) {
1087     SayWithDeclaration(*errSym, finalName,
1088         "FINAL subroutine '%s' of derived type '%s' must not have a dummy argument with the VALUE attribute"_err_en_US,
1089         subroutine.name(), derivedType.name());
1090     ok = false;
1091   }
1092   if (ddo->type.corank() > 0) {
1093     SayWithDeclaration(*errSym, finalName,
1094         "FINAL subroutine '%s' of derived type '%s' must not have a coarray dummy argument"_err_en_US,
1095         subroutine.name(), derivedType.name());
1096     ok = false;
1097   }
1098   if (ddo->type.type().IsPolymorphic()) {
1099     SayWithDeclaration(*errSym, finalName,
1100         "FINAL subroutine '%s' of derived type '%s' must not have a polymorphic dummy argument"_err_en_US,
1101         subroutine.name(), derivedType.name());
1102     ok = false;
1103   } else if (ddo->type.type().category() != TypeCategory::Derived ||
1104       &ddo->type.type().GetDerivedTypeSpec().typeSymbol() != &derivedType) {
1105     SayWithDeclaration(*errSym, finalName,
1106         "FINAL subroutine '%s' of derived type '%s' must have a TYPE(%s) dummy argument"_err_en_US,
1107         subroutine.name(), derivedType.name(), derivedType.name());
1108     ok = false;
1109   } else { // check that all LEN type parameters are assumed
1110     for (auto ref : OrderParameterDeclarations(derivedType)) {
1111       if (IsLenTypeParameter(*ref)) {
1112         const auto *value{
1113             ddo->type.type().GetDerivedTypeSpec().FindParameter(ref->name())};
1114         if (!value || !value->isAssumed()) {
1115           SayWithDeclaration(*errSym, finalName,
1116               "FINAL subroutine '%s' of derived type '%s' must have a dummy argument with an assumed LEN type parameter '%s=*'"_err_en_US,
1117               subroutine.name(), derivedType.name(), ref->name());
1118           ok = false;
1119         }
1120       }
1121     }
1122   }
1123   return ok;
1124 }
1125 
1126 bool CheckHelper::CheckDistinguishableFinals(const Symbol &f1,
1127     SourceName f1Name, const Symbol &f2, SourceName f2Name,
1128     const Symbol &derivedType) {
1129   const Procedure *p1{Characterize(f1)};
1130   const Procedure *p2{Characterize(f2)};
1131   if (p1 && p2) {
1132     if (characteristics::Distinguishable(
1133             context_.languageFeatures(), *p1, *p2)) {
1134       return true;
1135     }
1136     if (auto *msg{messages_.Say(f1Name,
1137             "FINAL subroutines '%s' and '%s' of derived type '%s' cannot be distinguished by rank or KIND type parameter value"_err_en_US,
1138             f1Name, f2Name, derivedType.name())}) {
1139       msg->Attach(f2Name, "FINAL declaration of '%s'"_en_US, f2.name())
1140           .Attach(f1.name(), "Definition of '%s'"_en_US, f1Name)
1141           .Attach(f2.name(), "Definition of '%s'"_en_US, f2Name);
1142     }
1143   }
1144   return false;
1145 }
1146 
1147 void CheckHelper::CheckHostAssoc(
1148     const Symbol &symbol, const HostAssocDetails &details) {
1149   const Symbol &hostSymbol{details.symbol()};
1150   if (hostSymbol.test(Symbol::Flag::ImplicitOrError)) {
1151     if (details.implicitOrSpecExprError) {
1152       messages_.Say("Implicitly typed local entity '%s' not allowed in"
1153                     " specification expression"_err_en_US,
1154           symbol.name());
1155     } else if (details.implicitOrExplicitTypeError) {
1156       messages_.Say(
1157           "No explicit type declared for '%s'"_err_en_US, symbol.name());
1158     }
1159   }
1160 }
1161 
1162 void CheckHelper::CheckGeneric(
1163     const Symbol &symbol, const GenericDetails &details) {
1164   CheckSpecificsAreDistinguishable(symbol, details);
1165   common::visit(common::visitors{
1166                     [&](const GenericKind::DefinedIo &io) {
1167                       CheckDefinedIoProc(symbol, details, io);
1168                     },
1169                     [&](const GenericKind::OtherKind &other) {
1170                       if (other == GenericKind::OtherKind::Name) {
1171                         CheckGenericVsIntrinsic(symbol, details);
1172                       }
1173                     },
1174                     [](const auto &) {},
1175                 },
1176       details.kind().u);
1177 }
1178 
1179 // Check that the specifics of this generic are distinguishable from each other
1180 void CheckHelper::CheckSpecificsAreDistinguishable(
1181     const Symbol &generic, const GenericDetails &details) {
1182   GenericKind kind{details.kind()};
1183   const SymbolVector &specifics{details.specificProcs()};
1184   std::size_t count{specifics.size()};
1185   if (count < 2 || !kind.IsName()) {
1186     return;
1187   }
1188   DistinguishabilityHelper helper{context_};
1189   for (const Symbol &specific : specifics) {
1190     if (const Procedure * procedure{Characterize(specific)}) {
1191       helper.Add(generic, kind, specific, *procedure);
1192     }
1193   }
1194   helper.Check(generic.owner());
1195 }
1196 
1197 static bool ConflictsWithIntrinsicAssignment(const Procedure &proc) {
1198   auto lhs{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1199   auto rhs{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1200   return Tristate::No ==
1201       IsDefinedAssignment(lhs.type(), lhs.Rank(), rhs.type(), rhs.Rank());
1202 }
1203 
1204 static bool ConflictsWithIntrinsicOperator(
1205     const GenericKind &kind, const Procedure &proc) {
1206   if (!kind.IsIntrinsicOperator()) {
1207     return false;
1208   }
1209   auto arg0{std::get<DummyDataObject>(proc.dummyArguments[0].u).type};
1210   auto type0{arg0.type()};
1211   if (proc.dummyArguments.size() == 1) { // unary
1212     return common::visit(
1213         common::visitors{
1214             [&](common::NumericOperator) { return IsIntrinsicNumeric(type0); },
1215             [&](common::LogicalOperator) { return IsIntrinsicLogical(type0); },
1216             [](const auto &) -> bool { DIE("bad generic kind"); },
1217         },
1218         kind.u);
1219   } else { // binary
1220     int rank0{arg0.Rank()};
1221     auto arg1{std::get<DummyDataObject>(proc.dummyArguments[1].u).type};
1222     auto type1{arg1.type()};
1223     int rank1{arg1.Rank()};
1224     return common::visit(
1225         common::visitors{
1226             [&](common::NumericOperator) {
1227               return IsIntrinsicNumeric(type0, rank0, type1, rank1);
1228             },
1229             [&](common::LogicalOperator) {
1230               return IsIntrinsicLogical(type0, rank0, type1, rank1);
1231             },
1232             [&](common::RelationalOperator opr) {
1233               return IsIntrinsicRelational(opr, type0, rank0, type1, rank1);
1234             },
1235             [&](GenericKind::OtherKind x) {
1236               CHECK(x == GenericKind::OtherKind::Concat);
1237               return IsIntrinsicConcat(type0, rank0, type1, rank1);
1238             },
1239             [](const auto &) -> bool { DIE("bad generic kind"); },
1240         },
1241         kind.u);
1242   }
1243 }
1244 
1245 // Check if this procedure can be used for defined operators (see 15.4.3.4.2).
1246 bool CheckHelper::CheckDefinedOperator(SourceName opName, GenericKind kind,
1247     const Symbol &specific, const Procedure &proc) {
1248   if (context_.HasError(specific)) {
1249     return false;
1250   }
1251   std::optional<parser::MessageFixedText> msg;
1252   auto checkDefinedOperatorArgs{
1253       [&](SourceName opName, const Symbol &specific, const Procedure &proc) {
1254         bool arg0Defined{CheckDefinedOperatorArg(opName, specific, proc, 0)};
1255         bool arg1Defined{CheckDefinedOperatorArg(opName, specific, proc, 1)};
1256         return arg0Defined && arg1Defined;
1257       }};
1258   if (specific.attrs().test(Attr::NOPASS)) { // C774
1259     msg = "%s procedure '%s' may not have NOPASS attribute"_err_en_US;
1260   } else if (!proc.functionResult.has_value()) {
1261     msg = "%s procedure '%s' must be a function"_err_en_US;
1262   } else if (proc.functionResult->IsAssumedLengthCharacter()) {
1263     msg = "%s function '%s' may not have assumed-length CHARACTER(*)"
1264           " result"_err_en_US;
1265   } else if (auto m{CheckNumberOfArgs(kind, proc.dummyArguments.size())}) {
1266     msg = std::move(m);
1267   } else if (!checkDefinedOperatorArgs(opName, specific, proc)) {
1268     return false; // error was reported
1269   } else if (ConflictsWithIntrinsicOperator(kind, proc)) {
1270     msg = "%s function '%s' conflicts with intrinsic operator"_err_en_US;
1271   } else {
1272     return true; // OK
1273   }
1274   SayWithDeclaration(
1275       specific, std::move(*msg), MakeOpName(opName), specific.name());
1276   context_.SetError(specific);
1277   return false;
1278 }
1279 
1280 // If the number of arguments is wrong for this intrinsic operator, return
1281 // false and return the error message in msg.
1282 std::optional<parser::MessageFixedText> CheckHelper::CheckNumberOfArgs(
1283     const GenericKind &kind, std::size_t nargs) {
1284   if (!kind.IsIntrinsicOperator()) {
1285     return std::nullopt;
1286   }
1287   std::size_t min{2}, max{2}; // allowed number of args; default is binary
1288   common::visit(common::visitors{
1289                     [&](const common::NumericOperator &x) {
1290                       if (x == common::NumericOperator::Add ||
1291                           x == common::NumericOperator::Subtract) {
1292                         min = 1; // + and - are unary or binary
1293                       }
1294                     },
1295                     [&](const common::LogicalOperator &x) {
1296                       if (x == common::LogicalOperator::Not) {
1297                         min = 1; // .NOT. is unary
1298                         max = 1;
1299                       }
1300                     },
1301                     [](const common::RelationalOperator &) {
1302                       // all are binary
1303                     },
1304                     [](const GenericKind::OtherKind &x) {
1305                       CHECK(x == GenericKind::OtherKind::Concat);
1306                     },
1307                     [](const auto &) { DIE("expected intrinsic operator"); },
1308                 },
1309       kind.u);
1310   if (nargs >= min && nargs <= max) {
1311     return std::nullopt;
1312   } else if (max == 1) {
1313     return "%s function '%s' must have one dummy argument"_err_en_US;
1314   } else if (min == 2) {
1315     return "%s function '%s' must have two dummy arguments"_err_en_US;
1316   } else {
1317     return "%s function '%s' must have one or two dummy arguments"_err_en_US;
1318   }
1319 }
1320 
1321 bool CheckHelper::CheckDefinedOperatorArg(const SourceName &opName,
1322     const Symbol &symbol, const Procedure &proc, std::size_t pos) {
1323   if (pos >= proc.dummyArguments.size()) {
1324     return true;
1325   }
1326   auto &arg{proc.dummyArguments.at(pos)};
1327   std::optional<parser::MessageFixedText> msg;
1328   if (arg.IsOptional()) {
1329     msg = "In %s function '%s', dummy argument '%s' may not be"
1330           " OPTIONAL"_err_en_US;
1331   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)};
1332              dataObject == nullptr) {
1333     msg = "In %s function '%s', dummy argument '%s' must be a"
1334           " data object"_err_en_US;
1335   } else if (dataObject->intent != common::Intent::In &&
1336       !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1337     msg = "In %s function '%s', dummy argument '%s' must have INTENT(IN)"
1338           " or VALUE attribute"_err_en_US;
1339   }
1340   if (msg) {
1341     SayWithDeclaration(symbol, std::move(*msg),
1342         parser::ToUpperCaseLetters(opName.ToString()), symbol.name(), arg.name);
1343     return false;
1344   }
1345   return true;
1346 }
1347 
1348 // Check if this procedure can be used for defined assignment (see 15.4.3.4.3).
1349 bool CheckHelper::CheckDefinedAssignment(
1350     const Symbol &specific, const Procedure &proc) {
1351   if (context_.HasError(specific)) {
1352     return false;
1353   }
1354   std::optional<parser::MessageFixedText> msg;
1355   if (specific.attrs().test(Attr::NOPASS)) { // C774
1356     msg = "Defined assignment procedure '%s' may not have"
1357           " NOPASS attribute"_err_en_US;
1358   } else if (!proc.IsSubroutine()) {
1359     msg = "Defined assignment procedure '%s' must be a subroutine"_err_en_US;
1360   } else if (proc.dummyArguments.size() != 2) {
1361     msg = "Defined assignment subroutine '%s' must have"
1362           " two dummy arguments"_err_en_US;
1363   } else {
1364     // Check both arguments even if the first has an error.
1365     bool ok0{CheckDefinedAssignmentArg(specific, proc.dummyArguments[0], 0)};
1366     bool ok1{CheckDefinedAssignmentArg(specific, proc.dummyArguments[1], 1)};
1367     if (!(ok0 && ok1)) {
1368       return false; // error was reported
1369     } else if (ConflictsWithIntrinsicAssignment(proc)) {
1370       msg = "Defined assignment subroutine '%s' conflicts with"
1371             " intrinsic assignment"_err_en_US;
1372     } else {
1373       return true; // OK
1374     }
1375   }
1376   SayWithDeclaration(specific, std::move(msg.value()), specific.name());
1377   context_.SetError(specific);
1378   return false;
1379 }
1380 
1381 bool CheckHelper::CheckDefinedAssignmentArg(
1382     const Symbol &symbol, const DummyArgument &arg, int pos) {
1383   std::optional<parser::MessageFixedText> msg;
1384   if (arg.IsOptional()) {
1385     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1386           " may not be OPTIONAL"_err_en_US;
1387   } else if (const auto *dataObject{std::get_if<DummyDataObject>(&arg.u)}) {
1388     if (pos == 0) {
1389       if (dataObject->intent != common::Intent::Out &&
1390           dataObject->intent != common::Intent::InOut) {
1391         msg = "In defined assignment subroutine '%s', first dummy argument '%s'"
1392               " must have INTENT(OUT) or INTENT(INOUT)"_err_en_US;
1393       }
1394     } else if (pos == 1) {
1395       if (dataObject->intent != common::Intent::In &&
1396           !dataObject->attrs.test(DummyDataObject::Attr::Value)) {
1397         msg =
1398             "In defined assignment subroutine '%s', second dummy"
1399             " argument '%s' must have INTENT(IN) or VALUE attribute"_err_en_US;
1400       }
1401     } else {
1402       DIE("pos must be 0 or 1");
1403     }
1404   } else {
1405     msg = "In defined assignment subroutine '%s', dummy argument '%s'"
1406           " must be a data object"_err_en_US;
1407   }
1408   if (msg) {
1409     SayWithDeclaration(symbol, std::move(*msg), symbol.name(), arg.name);
1410     context_.SetError(symbol);
1411     return false;
1412   }
1413   return true;
1414 }
1415 
1416 // Report a conflicting attribute error if symbol has both of these attributes
1417 bool CheckHelper::CheckConflicting(const Symbol &symbol, Attr a1, Attr a2) {
1418   if (symbol.attrs().test(a1) && symbol.attrs().test(a2)) {
1419     messages_.Say("'%s' may not have both the %s and %s attributes"_err_en_US,
1420         symbol.name(), AttrToString(a1), AttrToString(a2));
1421     return true;
1422   } else {
1423     return false;
1424   }
1425 }
1426 
1427 void CheckHelper::WarnMissingFinal(const Symbol &symbol) {
1428   const auto *object{symbol.detailsIf<ObjectEntityDetails>()};
1429   if (!object || IsPointer(symbol)) {
1430     return;
1431   }
1432   const DeclTypeSpec *type{object->type()};
1433   const DerivedTypeSpec *derived{type ? type->AsDerived() : nullptr};
1434   const Symbol *derivedSym{derived ? &derived->typeSymbol() : nullptr};
1435   int rank{object->shape().Rank()};
1436   const Symbol *initialDerivedSym{derivedSym};
1437   while (const auto *derivedDetails{
1438       derivedSym ? derivedSym->detailsIf<DerivedTypeDetails>() : nullptr}) {
1439     if (!derivedDetails->finals().empty() &&
1440         !derivedDetails->GetFinalForRank(rank)) {
1441       if (auto *msg{derivedSym == initialDerivedSym
1442                   ? messages_.Say(symbol.name(),
1443                         "'%s' of derived type '%s' does not have a FINAL subroutine for its rank (%d)"_warn_en_US,
1444                         symbol.name(), derivedSym->name(), rank)
1445                   : messages_.Say(symbol.name(),
1446                         "'%s' of derived type '%s' extended from '%s' does not have a FINAL subroutine for its rank (%d)"_warn_en_US,
1447                         symbol.name(), initialDerivedSym->name(),
1448                         derivedSym->name(), rank)}) {
1449         msg->Attach(derivedSym->name(),
1450             "Declaration of derived type '%s'"_en_US, derivedSym->name());
1451       }
1452       return;
1453     }
1454     derived = derivedSym->GetParentTypeSpec();
1455     derivedSym = derived ? &derived->typeSymbol() : nullptr;
1456   }
1457 }
1458 
1459 const Procedure *CheckHelper::Characterize(const Symbol &symbol) {
1460   auto it{characterizeCache_.find(symbol)};
1461   if (it == characterizeCache_.end()) {
1462     auto pair{characterizeCache_.emplace(SymbolRef{symbol},
1463         Procedure::Characterize(symbol, context_.foldingContext()))};
1464     it = pair.first;
1465   }
1466   return common::GetPtrFromOptional(it->second);
1467 }
1468 
1469 void CheckHelper::CheckVolatile(const Symbol &symbol,
1470     const DerivedTypeSpec *derived) { // C866 - C868
1471   if (IsIntentIn(symbol)) {
1472     messages_.Say(
1473         "VOLATILE attribute may not apply to an INTENT(IN) argument"_err_en_US);
1474   }
1475   if (IsProcedure(symbol)) {
1476     messages_.Say("VOLATILE attribute may apply only to a variable"_err_en_US);
1477   }
1478   if (symbol.has<UseDetails>() || symbol.has<HostAssocDetails>()) {
1479     const Symbol &ultimate{symbol.GetUltimate()};
1480     if (evaluate::IsCoarray(ultimate)) {
1481       messages_.Say(
1482           "VOLATILE attribute may not apply to a coarray accessed by USE or host association"_err_en_US);
1483     }
1484     if (derived) {
1485       if (FindCoarrayUltimateComponent(*derived)) {
1486         messages_.Say(
1487             "VOLATILE attribute may not apply to a type with a coarray ultimate component accessed by USE or host association"_err_en_US);
1488       }
1489     }
1490   }
1491 }
1492 
1493 void CheckHelper::CheckPointer(const Symbol &symbol) { // C852
1494   CheckConflicting(symbol, Attr::POINTER, Attr::TARGET);
1495   CheckConflicting(symbol, Attr::POINTER, Attr::ALLOCATABLE); // C751
1496   CheckConflicting(symbol, Attr::POINTER, Attr::INTRINSIC);
1497   // Prohibit constant pointers.  The standard does not explicitly prohibit
1498   // them, but the PARAMETER attribute requires a entity-decl to have an
1499   // initialization that is a constant-expr, and the only form of
1500   // initialization that allows a constant-expr is the one that's not a "=>"
1501   // pointer initialization.  See C811, C807, and section 8.5.13.
1502   CheckConflicting(symbol, Attr::POINTER, Attr::PARAMETER);
1503   if (symbol.Corank() > 0) {
1504     messages_.Say(
1505         "'%s' may not have the POINTER attribute because it is a coarray"_err_en_US,
1506         symbol.name());
1507   }
1508 }
1509 
1510 // C760 constraints on the passed-object dummy argument
1511 // C757 constraints on procedure pointer components
1512 void CheckHelper::CheckPassArg(
1513     const Symbol &proc, const Symbol *interface, const WithPassArg &details) {
1514   if (proc.attrs().test(Attr::NOPASS)) {
1515     return;
1516   }
1517   const auto &name{proc.name()};
1518   if (!interface) {
1519     messages_.Say(name,
1520         "Procedure component '%s' must have NOPASS attribute or explicit interface"_err_en_US,
1521         name);
1522     return;
1523   }
1524   const auto *subprogram{interface->detailsIf<SubprogramDetails>()};
1525   if (!subprogram) {
1526     messages_.Say(name,
1527         "Procedure component '%s' has invalid interface '%s'"_err_en_US, name,
1528         interface->name());
1529     return;
1530   }
1531   std::optional<SourceName> passName{details.passName()};
1532   const auto &dummyArgs{subprogram->dummyArgs()};
1533   if (!passName) {
1534     if (dummyArgs.empty()) {
1535       messages_.Say(name,
1536           proc.has<ProcEntityDetails>()
1537               ? "Procedure component '%s' with no dummy arguments"
1538                 " must have NOPASS attribute"_err_en_US
1539               : "Procedure binding '%s' with no dummy arguments"
1540                 " must have NOPASS attribute"_err_en_US,
1541           name);
1542       context_.SetError(*interface);
1543       return;
1544     }
1545     Symbol *argSym{dummyArgs[0]};
1546     if (!argSym) {
1547       messages_.Say(interface->name(),
1548           "Cannot use an alternate return as the passed-object dummy "
1549           "argument"_err_en_US);
1550       return;
1551     }
1552     passName = dummyArgs[0]->name();
1553   }
1554   std::optional<int> passArgIndex{};
1555   for (std::size_t i{0}; i < dummyArgs.size(); ++i) {
1556     if (dummyArgs[i] && dummyArgs[i]->name() == *passName) {
1557       passArgIndex = i;
1558       break;
1559     }
1560   }
1561   if (!passArgIndex) { // C758
1562     messages_.Say(*passName,
1563         "'%s' is not a dummy argument of procedure interface '%s'"_err_en_US,
1564         *passName, interface->name());
1565     return;
1566   }
1567   const Symbol &passArg{*dummyArgs[*passArgIndex]};
1568   std::optional<parser::MessageFixedText> msg;
1569   if (!passArg.has<ObjectEntityDetails>()) {
1570     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1571           " must be a data object"_err_en_US;
1572   } else if (passArg.attrs().test(Attr::POINTER)) {
1573     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1574           " may not have the POINTER attribute"_err_en_US;
1575   } else if (passArg.attrs().test(Attr::ALLOCATABLE)) {
1576     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1577           " may not have the ALLOCATABLE attribute"_err_en_US;
1578   } else if (passArg.attrs().test(Attr::VALUE)) {
1579     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1580           " may not have the VALUE attribute"_err_en_US;
1581   } else if (passArg.Rank() > 0) {
1582     msg = "Passed-object dummy argument '%s' of procedure '%s'"
1583           " must be scalar"_err_en_US;
1584   }
1585   if (msg) {
1586     messages_.Say(name, std::move(*msg), passName.value(), name);
1587     return;
1588   }
1589   const DeclTypeSpec *type{passArg.GetType()};
1590   if (!type) {
1591     return; // an error already occurred
1592   }
1593   const Symbol &typeSymbol{*proc.owner().GetSymbol()};
1594   const DerivedTypeSpec *derived{type->AsDerived()};
1595   if (!derived || derived->typeSymbol() != typeSymbol) {
1596     messages_.Say(name,
1597         "Passed-object dummy argument '%s' of procedure '%s'"
1598         " must be of type '%s' but is '%s'"_err_en_US,
1599         passName.value(), name, typeSymbol.name(), type->AsFortran());
1600     return;
1601   }
1602   if (IsExtensibleType(derived) != type->IsPolymorphic()) {
1603     messages_.Say(name,
1604         type->IsPolymorphic()
1605             ? "Passed-object dummy argument '%s' of procedure '%s'"
1606               " may not be polymorphic because '%s' is not extensible"_err_en_US
1607             : "Passed-object dummy argument '%s' of procedure '%s'"
1608               " must be polymorphic because '%s' is extensible"_err_en_US,
1609         passName.value(), name, typeSymbol.name());
1610     return;
1611   }
1612   for (const auto &[paramName, paramValue] : derived->parameters()) {
1613     if (paramValue.isLen() && !paramValue.isAssumed()) {
1614       messages_.Say(name,
1615           "Passed-object dummy argument '%s' of procedure '%s'"
1616           " has non-assumed length parameter '%s'"_err_en_US,
1617           passName.value(), name, paramName);
1618     }
1619   }
1620 }
1621 
1622 void CheckHelper::CheckProcBinding(
1623     const Symbol &symbol, const ProcBindingDetails &binding) {
1624   const Scope &dtScope{symbol.owner()};
1625   CHECK(dtScope.kind() == Scope::Kind::DerivedType);
1626   if (symbol.attrs().test(Attr::DEFERRED)) {
1627     if (const Symbol * dtSymbol{dtScope.symbol()}) {
1628       if (!dtSymbol->attrs().test(Attr::ABSTRACT)) { // C733
1629         SayWithDeclaration(*dtSymbol,
1630             "Procedure bound to non-ABSTRACT derived type '%s' may not be DEFERRED"_err_en_US,
1631             dtSymbol->name());
1632       }
1633     }
1634     if (symbol.attrs().test(Attr::NON_OVERRIDABLE)) {
1635       messages_.Say(
1636           "Type-bound procedure '%s' may not be both DEFERRED and NON_OVERRIDABLE"_err_en_US,
1637           symbol.name());
1638     }
1639   }
1640   if (binding.symbol().attrs().test(Attr::INTRINSIC) &&
1641       !context_.intrinsics().IsSpecificIntrinsicFunction(
1642           binding.symbol().name().ToString())) {
1643     messages_.Say(
1644         "Intrinsic procedure '%s' is not a specific intrinsic permitted for use in the definition of binding '%s'"_err_en_US,
1645         binding.symbol().name(), symbol.name());
1646   }
1647   if (const Symbol * overridden{FindOverriddenBinding(symbol)}) {
1648     if (overridden->attrs().test(Attr::NON_OVERRIDABLE)) {
1649       SayWithDeclaration(*overridden,
1650           "Override of NON_OVERRIDABLE '%s' is not permitted"_err_en_US,
1651           symbol.name());
1652     }
1653     if (const auto *overriddenBinding{
1654             overridden->detailsIf<ProcBindingDetails>()}) {
1655       if (!IsPureProcedure(symbol) && IsPureProcedure(*overridden)) {
1656         SayWithDeclaration(*overridden,
1657             "An overridden pure type-bound procedure binding must also be pure"_err_en_US);
1658         return;
1659       }
1660       if (!binding.symbol().attrs().test(Attr::ELEMENTAL) &&
1661           overriddenBinding->symbol().attrs().test(Attr::ELEMENTAL)) {
1662         SayWithDeclaration(*overridden,
1663             "A type-bound procedure and its override must both, or neither, be ELEMENTAL"_err_en_US);
1664         return;
1665       }
1666       bool isNopass{symbol.attrs().test(Attr::NOPASS)};
1667       if (isNopass != overridden->attrs().test(Attr::NOPASS)) {
1668         SayWithDeclaration(*overridden,
1669             isNopass
1670                 ? "A NOPASS type-bound procedure may not override a passed-argument procedure"_err_en_US
1671                 : "A passed-argument type-bound procedure may not override a NOPASS procedure"_err_en_US);
1672       } else {
1673         const auto *bindingChars{Characterize(binding.symbol())};
1674         const auto *overriddenChars{Characterize(overriddenBinding->symbol())};
1675         if (bindingChars && overriddenChars) {
1676           if (isNopass) {
1677             if (!bindingChars->CanOverride(*overriddenChars, std::nullopt)) {
1678               SayWithDeclaration(*overridden,
1679                   "A type-bound procedure and its override must have compatible interfaces"_err_en_US);
1680             }
1681           } else if (!context_.HasError(binding.symbol())) {
1682             int passIndex{bindingChars->FindPassIndex(binding.passName())};
1683             int overriddenPassIndex{
1684                 overriddenChars->FindPassIndex(overriddenBinding->passName())};
1685             if (passIndex != overriddenPassIndex) {
1686               SayWithDeclaration(*overridden,
1687                   "A type-bound procedure and its override must use the same PASS argument"_err_en_US);
1688             } else if (!bindingChars->CanOverride(
1689                            *overriddenChars, passIndex)) {
1690               SayWithDeclaration(*overridden,
1691                   "A type-bound procedure and its override must have compatible interfaces apart from their passed argument"_err_en_US);
1692             }
1693           }
1694         }
1695       }
1696       if (symbol.attrs().test(Attr::PRIVATE) &&
1697           overridden->attrs().test(Attr::PUBLIC)) {
1698         SayWithDeclaration(*overridden,
1699             "A PRIVATE procedure may not override a PUBLIC procedure"_err_en_US);
1700       }
1701     } else {
1702       SayWithDeclaration(*overridden,
1703           "A type-bound procedure binding may not have the same name as a parent component"_err_en_US);
1704     }
1705   }
1706   CheckPassArg(symbol, &binding.symbol(), binding);
1707 }
1708 
1709 void CheckHelper::Check(const Scope &scope) {
1710   scope_ = &scope;
1711   common::Restorer<const Symbol *> restorer{innermostSymbol_, innermostSymbol_};
1712   if (const Symbol * symbol{scope.symbol()}) {
1713     innermostSymbol_ = symbol;
1714   }
1715   if (scope.IsParameterizedDerivedTypeInstantiation()) {
1716     auto restorer{common::ScopedSet(scopeIsUninstantiatedPDT_, false)};
1717     auto restorer2{context_.foldingContext().messages().SetContext(
1718         scope.instantiationContext().get())};
1719     for (const auto &pair : scope) {
1720       CheckPointerInitialization(*pair.second);
1721     }
1722   } else {
1723     auto restorer{common::ScopedSet(
1724         scopeIsUninstantiatedPDT_, scope.IsParameterizedDerivedType())};
1725     for (const auto &set : scope.equivalenceSets()) {
1726       CheckEquivalenceSet(set);
1727     }
1728     for (const auto &pair : scope) {
1729       Check(*pair.second);
1730     }
1731     int mainProgCnt{0};
1732     for (const Scope &child : scope.children()) {
1733       Check(child);
1734       // A program shall consist of exactly one main program (5.2.2).
1735       if (child.kind() == Scope::Kind::MainProgram) {
1736         ++mainProgCnt;
1737         if (mainProgCnt > 1) {
1738           messages_.Say(child.sourceRange(),
1739               "A source file cannot contain more than one main program"_err_en_US);
1740         }
1741       }
1742     }
1743     if (scope.kind() == Scope::Kind::BlockData) {
1744       CheckBlockData(scope);
1745     }
1746     CheckGenericOps(scope);
1747   }
1748 }
1749 
1750 void CheckHelper::CheckEquivalenceSet(const EquivalenceSet &set) {
1751   auto iter{
1752       std::find_if(set.begin(), set.end(), [](const EquivalenceObject &object) {
1753         return FindCommonBlockContaining(object.symbol) != nullptr;
1754       })};
1755   if (iter != set.end()) {
1756     const Symbol &commonBlock{DEREF(FindCommonBlockContaining(iter->symbol))};
1757     for (auto &object : set) {
1758       if (&object != &*iter) {
1759         if (auto *details{object.symbol.detailsIf<ObjectEntityDetails>()}) {
1760           if (details->commonBlock()) {
1761             if (details->commonBlock() != &commonBlock) { // 8.10.3 paragraph 1
1762               if (auto *msg{messages_.Say(object.symbol.name(),
1763                       "Two objects in the same EQUIVALENCE set may not be members of distinct COMMON blocks"_err_en_US)}) {
1764                 msg->Attach(iter->symbol.name(),
1765                        "Other object in EQUIVALENCE set"_en_US)
1766                     .Attach(details->commonBlock()->name(),
1767                         "COMMON block containing '%s'"_en_US,
1768                         object.symbol.name())
1769                     .Attach(commonBlock.name(),
1770                         "COMMON block containing '%s'"_en_US,
1771                         iter->symbol.name());
1772               }
1773             }
1774           } else {
1775             // Mark all symbols in the equivalence set with the same COMMON
1776             // block to prevent spurious error messages about initialization
1777             // in BLOCK DATA outside COMMON
1778             details->set_commonBlock(commonBlock);
1779           }
1780         }
1781       }
1782     }
1783   }
1784   // TODO: Move C8106 (&al.) checks here from resolve-names-utils.cpp
1785 }
1786 
1787 void CheckHelper::CheckBlockData(const Scope &scope) {
1788   // BLOCK DATA subprograms should contain only named common blocks.
1789   // C1415 presents a list of statements that shouldn't appear in
1790   // BLOCK DATA, but so long as the subprogram contains no executable
1791   // code and allocates no storage outside named COMMON, we're happy
1792   // (e.g., an ENUM is strictly not allowed).
1793   for (const auto &pair : scope) {
1794     const Symbol &symbol{*pair.second};
1795     if (!(symbol.has<CommonBlockDetails>() || symbol.has<UseDetails>() ||
1796             symbol.has<UseErrorDetails>() || symbol.has<DerivedTypeDetails>() ||
1797             symbol.has<SubprogramDetails>() ||
1798             symbol.has<ObjectEntityDetails>() ||
1799             (symbol.has<ProcEntityDetails>() &&
1800                 !symbol.attrs().test(Attr::POINTER)))) {
1801       messages_.Say(symbol.name(),
1802           "'%s' may not appear in a BLOCK DATA subprogram"_err_en_US,
1803           symbol.name());
1804     }
1805   }
1806 }
1807 
1808 // Check distinguishability of generic assignment and operators.
1809 // For these, generics and generic bindings must be considered together.
1810 void CheckHelper::CheckGenericOps(const Scope &scope) {
1811   DistinguishabilityHelper helper{context_};
1812   auto addSpecifics{[&](const Symbol &generic) {
1813     const auto *details{generic.GetUltimate().detailsIf<GenericDetails>()};
1814     if (!details) {
1815       if (generic.test(Symbol::Flag::Function)) {
1816         Characterize(generic);
1817       }
1818       return;
1819     }
1820     GenericKind kind{details->kind()};
1821     if (!kind.IsAssignment() && !kind.IsOperator()) {
1822       return;
1823     }
1824     const SymbolVector &specifics{details->specificProcs()};
1825     const std::vector<SourceName> &bindingNames{details->bindingNames()};
1826     for (std::size_t i{0}; i < specifics.size(); ++i) {
1827       const Symbol &specific{*specifics[i]};
1828       if (const Procedure * proc{Characterize(specific)}) {
1829         auto restorer{messages_.SetLocation(bindingNames[i])};
1830         if (kind.IsAssignment()) {
1831           if (!CheckDefinedAssignment(specific, *proc)) {
1832             continue;
1833           }
1834         } else {
1835           if (!CheckDefinedOperator(generic.name(), kind, specific, *proc)) {
1836             continue;
1837           }
1838         }
1839         helper.Add(generic, kind, specific, *proc);
1840       }
1841     }
1842   }};
1843   for (const auto &pair : scope) {
1844     const Symbol &symbol{*pair.second};
1845     addSpecifics(symbol);
1846     const Symbol &ultimate{symbol.GetUltimate()};
1847     if (ultimate.has<DerivedTypeDetails>()) {
1848       if (const Scope * typeScope{ultimate.scope()}) {
1849         for (const auto &pair2 : *typeScope) {
1850           addSpecifics(*pair2.second);
1851         }
1852       }
1853     }
1854   }
1855   helper.Check(scope);
1856 }
1857 
1858 static const std::string *DefinesBindCName(const Symbol &symbol) {
1859   const auto *subp{symbol.detailsIf<SubprogramDetails>()};
1860   if ((subp && !subp->isInterface()) || symbol.has<ObjectEntityDetails>()) {
1861     // Symbol defines data or entry point
1862     return symbol.GetBindName();
1863   } else {
1864     return nullptr;
1865   }
1866 }
1867 
1868 // Check that BIND(C) names are distinct
1869 void CheckHelper::CheckBindCName(const Symbol &symbol) {
1870   if (const std::string * name{DefinesBindCName(symbol)}) {
1871     auto pair{bindC_.emplace(*name, symbol)};
1872     if (!pair.second) {
1873       const Symbol &other{*pair.first->second};
1874       if (DefinesBindCName(other) && !context_.HasError(other)) {
1875         if (auto *msg{messages_.Say(
1876                 "Two symbols have the same BIND(C) name '%s'"_err_en_US,
1877                 *name)}) {
1878           msg->Attach(other.name(), "Conflicting symbol"_en_US);
1879         }
1880         context_.SetError(symbol);
1881         context_.SetError(other);
1882       }
1883     }
1884   }
1885 }
1886 
1887 bool CheckHelper::CheckDioDummyIsData(
1888     const Symbol &subp, const Symbol *arg, std::size_t position) {
1889   if (arg && arg->detailsIf<ObjectEntityDetails>()) {
1890     return true;
1891   } else {
1892     if (arg) {
1893       messages_.Say(arg->name(),
1894           "Dummy argument '%s' must be a data object"_err_en_US, arg->name());
1895     } else {
1896       messages_.Say(subp.name(),
1897           "Dummy argument %d of '%s' must be a data object"_err_en_US, position,
1898           subp.name());
1899     }
1900     return false;
1901   }
1902 }
1903 
1904 void CheckHelper::CheckAlreadySeenDefinedIo(const DerivedTypeSpec *derivedType,
1905     GenericKind::DefinedIo ioKind, const Symbol &proc) {
1906   for (TypeWithDefinedIo definedIoType : seenDefinedIoTypes_) {
1907     if (*derivedType == *definedIoType.type && ioKind == definedIoType.ioKind &&
1908         proc != definedIoType.proc) {
1909       SayWithDeclaration(proc, definedIoType.proc.name(),
1910           "Derived type '%s' already has defined input/output procedure"
1911           " '%s'"_err_en_US,
1912           derivedType->name(),
1913           parser::ToUpperCaseLetters(GenericKind::EnumToString(ioKind)));
1914       return;
1915     }
1916   }
1917   seenDefinedIoTypes_.emplace_back(
1918       TypeWithDefinedIo{derivedType, ioKind, proc});
1919 }
1920 
1921 void CheckHelper::CheckDioDummyIsDerived(
1922     const Symbol &subp, const Symbol &arg, GenericKind::DefinedIo ioKind) {
1923   if (const DeclTypeSpec * type{arg.GetType()}) {
1924     if (const DerivedTypeSpec * derivedType{type->AsDerived()}) {
1925       CheckAlreadySeenDefinedIo(derivedType, ioKind, subp);
1926       bool isPolymorphic{type->IsPolymorphic()};
1927       if (isPolymorphic != IsExtensibleType(derivedType)) {
1928         messages_.Say(arg.name(),
1929             "Dummy argument '%s' of a defined input/output procedure must be %s when the derived type is %s"_err_en_US,
1930             arg.name(), isPolymorphic ? "TYPE()" : "CLASS()",
1931             isPolymorphic ? "not extensible" : "extensible");
1932       }
1933     } else {
1934       messages_.Say(arg.name(),
1935           "Dummy argument '%s' of a defined input/output procedure must have a"
1936           " derived type"_err_en_US,
1937           arg.name());
1938     }
1939   }
1940 }
1941 
1942 void CheckHelper::CheckDioDummyIsDefaultInteger(
1943     const Symbol &subp, const Symbol &arg) {
1944   if (const DeclTypeSpec * type{arg.GetType()};
1945       type && type->IsNumeric(TypeCategory::Integer)) {
1946     if (const auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
1947         kind && *kind == context_.GetDefaultKind(TypeCategory::Integer)) {
1948       return;
1949     }
1950   }
1951   messages_.Say(arg.name(),
1952       "Dummy argument '%s' of a defined input/output procedure"
1953       " must be an INTEGER of default KIND"_err_en_US,
1954       arg.name());
1955 }
1956 
1957 void CheckHelper::CheckDioDummyIsScalar(const Symbol &subp, const Symbol &arg) {
1958   if (arg.Rank() > 0 || arg.Corank() > 0) {
1959     messages_.Say(arg.name(),
1960         "Dummy argument '%s' of a defined input/output procedure"
1961         " must be a scalar"_err_en_US,
1962         arg.name());
1963   }
1964 }
1965 
1966 void CheckHelper::CheckDioDtvArg(
1967     const Symbol &subp, const Symbol *arg, GenericKind::DefinedIo ioKind) {
1968   // Dtv argument looks like: dtv-type-spec, INTENT(INOUT) :: dtv
1969   if (CheckDioDummyIsData(subp, arg, 0)) {
1970     CheckDioDummyIsDerived(subp, *arg, ioKind);
1971     CheckDioDummyAttrs(subp, *arg,
1972         ioKind == GenericKind::DefinedIo::ReadFormatted ||
1973                 ioKind == GenericKind::DefinedIo::ReadUnformatted
1974             ? Attr::INTENT_INOUT
1975             : Attr::INTENT_IN);
1976   }
1977 }
1978 
1979 // If an explicit INTRINSIC name is a function, so must all the specifics be,
1980 // and similarly for subroutines
1981 void CheckHelper::CheckGenericVsIntrinsic(
1982     const Symbol &symbol, const GenericDetails &generic) {
1983   if (symbol.attrs().test(Attr::INTRINSIC)) {
1984     const evaluate::IntrinsicProcTable &table{
1985         context_.foldingContext().intrinsics()};
1986     bool isSubroutine{table.IsIntrinsicSubroutine(symbol.name().ToString())};
1987     if (isSubroutine || table.IsIntrinsicFunction(symbol.name().ToString())) {
1988       for (const SymbolRef &ref : generic.specificProcs()) {
1989         const Symbol &ultimate{ref->GetUltimate()};
1990         bool specificFunc{ultimate.test(Symbol::Flag::Function)};
1991         bool specificSubr{ultimate.test(Symbol::Flag::Subroutine)};
1992         if (!specificFunc && !specificSubr) {
1993           if (const auto *proc{ultimate.detailsIf<SubprogramDetails>()}) {
1994             if (proc->isFunction()) {
1995               specificFunc = true;
1996             } else {
1997               specificSubr = true;
1998             }
1999           }
2000         }
2001         if ((specificFunc || specificSubr) &&
2002             isSubroutine != specificSubr) { // C848
2003           messages_.Say(symbol.name(),
2004               "Generic interface '%s' with explicit intrinsic %s of the same name may not have specific procedure '%s' that is a %s"_err_en_US,
2005               symbol.name(), isSubroutine ? "subroutine" : "function",
2006               ref->name(), isSubroutine ? "function" : "subroutine");
2007         }
2008       }
2009     }
2010   }
2011 }
2012 
2013 void CheckHelper::CheckDefaultIntegerArg(
2014     const Symbol &subp, const Symbol *arg, Attr intent) {
2015   // Argument looks like: INTEGER, INTENT(intent) :: arg
2016   if (CheckDioDummyIsData(subp, arg, 1)) {
2017     CheckDioDummyIsDefaultInteger(subp, *arg);
2018     CheckDioDummyIsScalar(subp, *arg);
2019     CheckDioDummyAttrs(subp, *arg, intent);
2020   }
2021 }
2022 
2023 void CheckHelper::CheckDioAssumedLenCharacterArg(const Symbol &subp,
2024     const Symbol *arg, std::size_t argPosition, Attr intent) {
2025   // Argument looks like: CHARACTER (LEN=*), INTENT(intent) :: (iotype OR iomsg)
2026   if (CheckDioDummyIsData(subp, arg, argPosition)) {
2027     CheckDioDummyAttrs(subp, *arg, intent);
2028     if (!IsAssumedLengthCharacter(*arg)) {
2029       messages_.Say(arg->name(),
2030           "Dummy argument '%s' of a defined input/output procedure"
2031           " must be assumed-length CHARACTER"_err_en_US,
2032           arg->name());
2033     }
2034   }
2035 }
2036 
2037 void CheckHelper::CheckDioVlistArg(
2038     const Symbol &subp, const Symbol *arg, std::size_t argPosition) {
2039   // Vlist argument looks like: INTEGER, INTENT(IN) :: v_list(:)
2040   if (CheckDioDummyIsData(subp, arg, argPosition)) {
2041     CheckDioDummyIsDefaultInteger(subp, *arg);
2042     CheckDioDummyAttrs(subp, *arg, Attr::INTENT_IN);
2043     const auto *objectDetails{arg->detailsIf<ObjectEntityDetails>()};
2044     if (!objectDetails || !objectDetails->shape().CanBeDeferredShape()) {
2045       messages_.Say(arg->name(),
2046           "Dummy argument '%s' of a defined input/output procedure must be"
2047           " deferred shape"_err_en_US,
2048           arg->name());
2049     }
2050   }
2051 }
2052 
2053 void CheckHelper::CheckDioArgCount(
2054     const Symbol &subp, GenericKind::DefinedIo ioKind, std::size_t argCount) {
2055   const std::size_t requiredArgCount{
2056       (std::size_t)(ioKind == GenericKind::DefinedIo::ReadFormatted ||
2057                   ioKind == GenericKind::DefinedIo::WriteFormatted
2058               ? 6
2059               : 4)};
2060   if (argCount != requiredArgCount) {
2061     SayWithDeclaration(subp,
2062         "Defined input/output procedure '%s' must have"
2063         " %d dummy arguments rather than %d"_err_en_US,
2064         subp.name(), requiredArgCount, argCount);
2065     context_.SetError(subp);
2066   }
2067 }
2068 
2069 void CheckHelper::CheckDioDummyAttrs(
2070     const Symbol &subp, const Symbol &arg, Attr goodIntent) {
2071   // Defined I/O procedures can't have attributes other than INTENT
2072   Attrs attrs{arg.attrs()};
2073   if (!attrs.test(goodIntent)) {
2074     messages_.Say(arg.name(),
2075         "Dummy argument '%s' of a defined input/output procedure"
2076         " must have intent '%s'"_err_en_US,
2077         arg.name(), AttrToString(goodIntent));
2078   }
2079   attrs = attrs - Attr::INTENT_IN - Attr::INTENT_OUT - Attr::INTENT_INOUT;
2080   if (!attrs.empty()) {
2081     messages_.Say(arg.name(),
2082         "Dummy argument '%s' of a defined input/output procedure may not have"
2083         " any attributes"_err_en_US,
2084         arg.name());
2085   }
2086 }
2087 
2088 // Enforce semantics for defined input/output procedures (12.6.4.8.2) and C777
2089 void CheckHelper::CheckDefinedIoProc(const Symbol &symbol,
2090     const GenericDetails &details, GenericKind::DefinedIo ioKind) {
2091   for (auto ref : details.specificProcs()) {
2092     const auto *binding{ref->detailsIf<ProcBindingDetails>()};
2093     const Symbol &specific{*(binding ? &binding->symbol() : &*ref)};
2094     if (ref->attrs().test(Attr::NOPASS)) { // C774
2095       messages_.Say("Defined input/output procedure '%s' may not have NOPASS "
2096                     "attribute"_err_en_US,
2097           ref->name());
2098       context_.SetError(*ref);
2099     }
2100     if (const auto *subpDetails{specific.detailsIf<SubprogramDetails>()}) {
2101       const std::vector<Symbol *> &dummyArgs{subpDetails->dummyArgs()};
2102       CheckDioArgCount(specific, ioKind, dummyArgs.size());
2103       int argCount{0};
2104       for (auto *arg : dummyArgs) {
2105         switch (argCount++) {
2106         case 0:
2107           // dtv-type-spec, INTENT(INOUT) :: dtv
2108           CheckDioDtvArg(specific, arg, ioKind);
2109           break;
2110         case 1:
2111           // INTEGER, INTENT(IN) :: unit
2112           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_IN);
2113           break;
2114         case 2:
2115           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2116               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2117             // CHARACTER (LEN=*), INTENT(IN) :: iotype
2118             CheckDioAssumedLenCharacterArg(
2119                 specific, arg, argCount, Attr::INTENT_IN);
2120           } else {
2121             // INTEGER, INTENT(OUT) :: iostat
2122             CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2123           }
2124           break;
2125         case 3:
2126           if (ioKind == GenericKind::DefinedIo::ReadFormatted ||
2127               ioKind == GenericKind::DefinedIo::WriteFormatted) {
2128             // INTEGER, INTENT(IN) :: v_list(:)
2129             CheckDioVlistArg(specific, arg, argCount);
2130           } else {
2131             // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2132             CheckDioAssumedLenCharacterArg(
2133                 specific, arg, argCount, Attr::INTENT_INOUT);
2134           }
2135           break;
2136         case 4:
2137           // INTEGER, INTENT(OUT) :: iostat
2138           CheckDefaultIntegerArg(specific, arg, Attr::INTENT_OUT);
2139           break;
2140         case 5:
2141           // CHARACTER (LEN=*), INTENT(INOUT) :: iomsg
2142           CheckDioAssumedLenCharacterArg(
2143               specific, arg, argCount, Attr::INTENT_INOUT);
2144           break;
2145         default:;
2146         }
2147       }
2148     }
2149   }
2150 }
2151 
2152 void SubprogramMatchHelper::Check(
2153     const Symbol &symbol1, const Symbol &symbol2) {
2154   const auto details1{symbol1.get<SubprogramDetails>()};
2155   const auto details2{symbol2.get<SubprogramDetails>()};
2156   if (details1.isFunction() != details2.isFunction()) {
2157     Say(symbol1, symbol2,
2158         details1.isFunction()
2159             ? "Module function '%s' was declared as a subroutine in the"
2160               " corresponding interface body"_err_en_US
2161             : "Module subroutine '%s' was declared as a function in the"
2162               " corresponding interface body"_err_en_US);
2163     return;
2164   }
2165   const auto &args1{details1.dummyArgs()};
2166   const auto &args2{details2.dummyArgs()};
2167   int nargs1{static_cast<int>(args1.size())};
2168   int nargs2{static_cast<int>(args2.size())};
2169   if (nargs1 != nargs2) {
2170     Say(symbol1, symbol2,
2171         "Module subprogram '%s' has %d args but the corresponding interface"
2172         " body has %d"_err_en_US,
2173         nargs1, nargs2);
2174     return;
2175   }
2176   bool nonRecursive1{symbol1.attrs().test(Attr::NON_RECURSIVE)};
2177   if (nonRecursive1 != symbol2.attrs().test(Attr::NON_RECURSIVE)) { // C1551
2178     Say(symbol1, symbol2,
2179         nonRecursive1
2180             ? "Module subprogram '%s' has NON_RECURSIVE prefix but"
2181               " the corresponding interface body does not"_err_en_US
2182             : "Module subprogram '%s' does not have NON_RECURSIVE prefix but "
2183               "the corresponding interface body does"_err_en_US);
2184   }
2185   const std::string *bindName1{details1.bindName()};
2186   const std::string *bindName2{details2.bindName()};
2187   if (!bindName1 && !bindName2) {
2188     // OK - neither has a binding label
2189   } else if (!bindName1) {
2190     Say(symbol1, symbol2,
2191         "Module subprogram '%s' does not have a binding label but the"
2192         " corresponding interface body does"_err_en_US);
2193   } else if (!bindName2) {
2194     Say(symbol1, symbol2,
2195         "Module subprogram '%s' has a binding label but the"
2196         " corresponding interface body does not"_err_en_US);
2197   } else if (*bindName1 != *bindName2) {
2198     Say(symbol1, symbol2,
2199         "Module subprogram '%s' has binding label '%s' but the corresponding"
2200         " interface body has '%s'"_err_en_US,
2201         *details1.bindName(), *details2.bindName());
2202   }
2203   const Procedure *proc1{checkHelper.Characterize(symbol1)};
2204   const Procedure *proc2{checkHelper.Characterize(symbol2)};
2205   if (!proc1 || !proc2) {
2206     return;
2207   }
2208   if (proc1->attrs.test(Procedure::Attr::Pure) !=
2209       proc2->attrs.test(Procedure::Attr::Pure)) {
2210     Say(symbol1, symbol2,
2211         "Module subprogram '%s' and its corresponding interface body are not both PURE"_err_en_US);
2212   }
2213   if (proc1->attrs.test(Procedure::Attr::Elemental) !=
2214       proc2->attrs.test(Procedure::Attr::Elemental)) {
2215     Say(symbol1, symbol2,
2216         "Module subprogram '%s' and its corresponding interface body are not both ELEMENTAL"_err_en_US);
2217   }
2218   if (proc1->attrs.test(Procedure::Attr::BindC) !=
2219       proc2->attrs.test(Procedure::Attr::BindC)) {
2220     Say(symbol1, symbol2,
2221         "Module subprogram '%s' and its corresponding interface body are not both BIND(C)"_err_en_US);
2222   }
2223   if (proc1->functionResult && proc2->functionResult &&
2224       *proc1->functionResult != *proc2->functionResult) {
2225     Say(symbol1, symbol2,
2226         "Return type of function '%s' does not match return type of"
2227         " the corresponding interface body"_err_en_US);
2228   }
2229   for (int i{0}; i < nargs1; ++i) {
2230     const Symbol *arg1{args1[i]};
2231     const Symbol *arg2{args2[i]};
2232     if (arg1 && !arg2) {
2233       Say(symbol1, symbol2,
2234           "Dummy argument %2$d of '%1$s' is not an alternate return indicator"
2235           " but the corresponding argument in the interface body is"_err_en_US,
2236           i + 1);
2237     } else if (!arg1 && arg2) {
2238       Say(symbol1, symbol2,
2239           "Dummy argument %2$d of '%1$s' is an alternate return indicator but"
2240           " the corresponding argument in the interface body is not"_err_en_US,
2241           i + 1);
2242     } else if (arg1 && arg2) {
2243       SourceName name1{arg1->name()};
2244       SourceName name2{arg2->name()};
2245       if (name1 != name2) {
2246         Say(*arg1, *arg2,
2247             "Dummy argument name '%s' does not match corresponding name '%s'"
2248             " in interface body"_err_en_US,
2249             name2);
2250       } else {
2251         CheckDummyArg(
2252             *arg1, *arg2, proc1->dummyArguments[i], proc2->dummyArguments[i]);
2253       }
2254     }
2255   }
2256 }
2257 
2258 void SubprogramMatchHelper::CheckDummyArg(const Symbol &symbol1,
2259     const Symbol &symbol2, const DummyArgument &arg1,
2260     const DummyArgument &arg2) {
2261   common::visit(
2262       common::visitors{
2263           [&](const DummyDataObject &obj1, const DummyDataObject &obj2) {
2264             CheckDummyDataObject(symbol1, symbol2, obj1, obj2);
2265           },
2266           [&](const DummyProcedure &proc1, const DummyProcedure &proc2) {
2267             CheckDummyProcedure(symbol1, symbol2, proc1, proc2);
2268           },
2269           [&](const DummyDataObject &, const auto &) {
2270             Say(symbol1, symbol2,
2271                 "Dummy argument '%s' is a data object; the corresponding"
2272                 " argument in the interface body is not"_err_en_US);
2273           },
2274           [&](const DummyProcedure &, const auto &) {
2275             Say(symbol1, symbol2,
2276                 "Dummy argument '%s' is a procedure; the corresponding"
2277                 " argument in the interface body is not"_err_en_US);
2278           },
2279           [&](const auto &, const auto &) {
2280             llvm_unreachable("Dummy arguments are not data objects or"
2281                              "procedures");
2282           },
2283       },
2284       arg1.u, arg2.u);
2285 }
2286 
2287 void SubprogramMatchHelper::CheckDummyDataObject(const Symbol &symbol1,
2288     const Symbol &symbol2, const DummyDataObject &obj1,
2289     const DummyDataObject &obj2) {
2290   if (!CheckSameIntent(symbol1, symbol2, obj1.intent, obj2.intent)) {
2291   } else if (!CheckSameAttrs(symbol1, symbol2, obj1.attrs, obj2.attrs)) {
2292   } else if (obj1.type.type() != obj2.type.type()) {
2293     Say(symbol1, symbol2,
2294         "Dummy argument '%s' has type %s; the corresponding argument in the"
2295         " interface body has type %s"_err_en_US,
2296         obj1.type.type().AsFortran(), obj2.type.type().AsFortran());
2297   } else if (!ShapesAreCompatible(obj1, obj2)) {
2298     Say(symbol1, symbol2,
2299         "The shape of dummy argument '%s' does not match the shape of the"
2300         " corresponding argument in the interface body"_err_en_US);
2301   }
2302   // TODO: coshape
2303 }
2304 
2305 void SubprogramMatchHelper::CheckDummyProcedure(const Symbol &symbol1,
2306     const Symbol &symbol2, const DummyProcedure &proc1,
2307     const DummyProcedure &proc2) {
2308   if (!CheckSameIntent(symbol1, symbol2, proc1.intent, proc2.intent)) {
2309   } else if (!CheckSameAttrs(symbol1, symbol2, proc1.attrs, proc2.attrs)) {
2310   } else if (proc1 != proc2) {
2311     Say(symbol1, symbol2,
2312         "Dummy procedure '%s' does not match the corresponding argument in"
2313         " the interface body"_err_en_US);
2314   }
2315 }
2316 
2317 bool SubprogramMatchHelper::CheckSameIntent(const Symbol &symbol1,
2318     const Symbol &symbol2, common::Intent intent1, common::Intent intent2) {
2319   if (intent1 == intent2) {
2320     return true;
2321   } else {
2322     Say(symbol1, symbol2,
2323         "The intent of dummy argument '%s' does not match the intent"
2324         " of the corresponding argument in the interface body"_err_en_US);
2325     return false;
2326   }
2327 }
2328 
2329 // Report an error referring to first symbol with declaration of second symbol
2330 template <typename... A>
2331 void SubprogramMatchHelper::Say(const Symbol &symbol1, const Symbol &symbol2,
2332     parser::MessageFixedText &&text, A &&...args) {
2333   auto &message{context().Say(symbol1.name(), std::move(text), symbol1.name(),
2334       std::forward<A>(args)...)};
2335   evaluate::AttachDeclaration(message, symbol2);
2336 }
2337 
2338 template <typename ATTRS>
2339 bool SubprogramMatchHelper::CheckSameAttrs(
2340     const Symbol &symbol1, const Symbol &symbol2, ATTRS attrs1, ATTRS attrs2) {
2341   if (attrs1 == attrs2) {
2342     return true;
2343   }
2344   attrs1.IterateOverMembers([&](auto attr) {
2345     if (!attrs2.test(attr)) {
2346       Say(symbol1, symbol2,
2347           "Dummy argument '%s' has the %s attribute; the corresponding"
2348           " argument in the interface body does not"_err_en_US,
2349           AsFortran(attr));
2350     }
2351   });
2352   attrs2.IterateOverMembers([&](auto attr) {
2353     if (!attrs1.test(attr)) {
2354       Say(symbol1, symbol2,
2355           "Dummy argument '%s' does not have the %s attribute; the"
2356           " corresponding argument in the interface body does"_err_en_US,
2357           AsFortran(attr));
2358     }
2359   });
2360   return false;
2361 }
2362 
2363 bool SubprogramMatchHelper::ShapesAreCompatible(
2364     const DummyDataObject &obj1, const DummyDataObject &obj2) {
2365   return characteristics::ShapesAreCompatible(
2366       FoldShape(obj1.type.shape()), FoldShape(obj2.type.shape()));
2367 }
2368 
2369 evaluate::Shape SubprogramMatchHelper::FoldShape(const evaluate::Shape &shape) {
2370   evaluate::Shape result;
2371   for (const auto &extent : shape) {
2372     result.emplace_back(
2373         evaluate::Fold(context().foldingContext(), common::Clone(extent)));
2374   }
2375   return result;
2376 }
2377 
2378 void DistinguishabilityHelper::Add(const Symbol &generic, GenericKind kind,
2379     const Symbol &specific, const Procedure &procedure) {
2380   if (!context_.HasError(specific)) {
2381     nameToInfo_[generic.name()].emplace_back(
2382         ProcedureInfo{kind, specific, procedure});
2383   }
2384 }
2385 
2386 void DistinguishabilityHelper::Check(const Scope &scope) {
2387   for (const auto &[name, info] : nameToInfo_) {
2388     auto count{info.size()};
2389     for (std::size_t i1{0}; i1 < count - 1; ++i1) {
2390       const auto &[kind, symbol, proc]{info[i1]};
2391       for (std::size_t i2{i1 + 1}; i2 < count; ++i2) {
2392         auto distinguishable{kind.IsName()
2393                 ? evaluate::characteristics::Distinguishable
2394                 : evaluate::characteristics::DistinguishableOpOrAssign};
2395         if (!distinguishable(
2396                 context_.languageFeatures(), proc, info[i2].procedure)) {
2397           SayNotDistinguishable(GetTopLevelUnitContaining(scope), name, kind,
2398               symbol, info[i2].symbol);
2399         }
2400       }
2401     }
2402   }
2403 }
2404 
2405 void DistinguishabilityHelper::SayNotDistinguishable(const Scope &scope,
2406     const SourceName &name, GenericKind kind, const Symbol &proc1,
2407     const Symbol &proc2) {
2408   std::string name1{proc1.name().ToString()};
2409   std::string name2{proc2.name().ToString()};
2410   if (kind.IsOperator() || kind.IsAssignment()) {
2411     // proc1 and proc2 may come from different scopes so qualify their names
2412     if (proc1.owner().IsDerivedType()) {
2413       name1 = proc1.owner().GetName()->ToString() + '%' + name1;
2414     }
2415     if (proc2.owner().IsDerivedType()) {
2416       name2 = proc2.owner().GetName()->ToString() + '%' + name2;
2417     }
2418   }
2419   parser::Message *msg;
2420   if (scope.sourceRange().Contains(name)) {
2421     msg = &context_.Say(name,
2422         "Generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2423         MakeOpName(name), name1, name2);
2424   } else {
2425     msg = &context_.Say(*GetTopLevelUnitContaining(proc1).GetName(),
2426         "USE-associated generic '%s' may not have specific procedures '%s' and '%s' as their interfaces are not distinguishable"_err_en_US,
2427         MakeOpName(name), name1, name2);
2428   }
2429   AttachDeclaration(*msg, scope, proc1);
2430   AttachDeclaration(*msg, scope, proc2);
2431 }
2432 
2433 // `evaluate::AttachDeclaration` doesn't handle the generic case where `proc`
2434 // comes from a different module but is not necessarily use-associated.
2435 void DistinguishabilityHelper::AttachDeclaration(
2436     parser::Message &msg, const Scope &scope, const Symbol &proc) {
2437   const Scope &unit{GetTopLevelUnitContaining(proc)};
2438   if (unit == scope) {
2439     evaluate::AttachDeclaration(msg, proc);
2440   } else {
2441     msg.Attach(unit.GetName().value(),
2442         "'%s' is USE-associated from module '%s'"_en_US, proc.name(),
2443         unit.GetName().value());
2444   }
2445 }
2446 
2447 void CheckDeclarations(SemanticsContext &context) {
2448   CheckHelper{context}.Check();
2449 }
2450 } // namespace Fortran::semantics
2451