1 //===-- lib/Semantics/resolve-names.cpp -----------------------------------===//
2 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3 // See https://llvm.org/LICENSE.txt for license information.
4 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5 //
6 //===----------------------------------------------------------------------===//
7 
8 #include "resolve-names.h"
9 #include "assignment.h"
10 #include "mod-file.h"
11 #include "pointer-assignment.h"
12 #include "program-tree.h"
13 #include "resolve-directives.h"
14 #include "resolve-names-utils.h"
15 #include "rewrite-parse-tree.h"
16 #include "flang/Common/Fortran.h"
17 #include "flang/Common/default-kinds.h"
18 #include "flang/Common/indirection.h"
19 #include "flang/Common/restorer.h"
20 #include "flang/Evaluate/characteristics.h"
21 #include "flang/Evaluate/check-expression.h"
22 #include "flang/Evaluate/common.h"
23 #include "flang/Evaluate/fold-designator.h"
24 #include "flang/Evaluate/fold.h"
25 #include "flang/Evaluate/intrinsics.h"
26 #include "flang/Evaluate/tools.h"
27 #include "flang/Evaluate/type.h"
28 #include "flang/Parser/parse-tree-visitor.h"
29 #include "flang/Parser/parse-tree.h"
30 #include "flang/Parser/tools.h"
31 #include "flang/Semantics/attr.h"
32 #include "flang/Semantics/expression.h"
33 #include "flang/Semantics/scope.h"
34 #include "flang/Semantics/semantics.h"
35 #include "flang/Semantics/symbol.h"
36 #include "flang/Semantics/tools.h"
37 #include "flang/Semantics/type.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include <list>
40 #include <map>
41 #include <set>
42 #include <stack>
43 
44 namespace Fortran::semantics {
45 
46 using namespace parser::literals;
47 
48 template <typename T> using Indirection = common::Indirection<T>;
49 using Message = parser::Message;
50 using Messages = parser::Messages;
51 using MessageFixedText = parser::MessageFixedText;
52 using MessageFormattedText = parser::MessageFormattedText;
53 
54 class ResolveNamesVisitor;
55 
56 // ImplicitRules maps initial character of identifier to the DeclTypeSpec
57 // representing the implicit type; std::nullopt if none.
58 // It also records the presence of IMPLICIT NONE statements.
59 // When inheritFromParent is set, defaults come from the parent rules.
60 class ImplicitRules {
61 public:
62   ImplicitRules(SemanticsContext &context, ImplicitRules *parent)
63       : parent_{parent}, context_{context} {
64     inheritFromParent_ = parent != nullptr;
65   }
66   bool isImplicitNoneType() const;
67   bool isImplicitNoneExternal() const;
68   void set_isImplicitNoneType(bool x) { isImplicitNoneType_ = x; }
69   void set_isImplicitNoneExternal(bool x) { isImplicitNoneExternal_ = x; }
70   void set_inheritFromParent(bool x) { inheritFromParent_ = x; }
71   // Get the implicit type for this name. May be null.
72   const DeclTypeSpec *GetType(
73       SourceName, bool respectImplicitNone = true) const;
74   // Record the implicit type for the range of characters [fromLetter,
75   // toLetter].
76   void SetTypeMapping(const DeclTypeSpec &type, parser::Location fromLetter,
77       parser::Location toLetter);
78 
79 private:
80   static char Incr(char ch);
81 
82   ImplicitRules *parent_;
83   SemanticsContext &context_;
84   bool inheritFromParent_{false}; // look in parent if not specified here
85   bool isImplicitNoneType_{
86       context_.IsEnabled(common::LanguageFeature::ImplicitNoneTypeAlways)};
87   bool isImplicitNoneExternal_{false};
88   // map_ contains the mapping between letters and types that were defined
89   // by the IMPLICIT statements of the related scope. It does not contain
90   // the default Fortran mappings nor the mapping defined in parents.
91   std::map<char, common::Reference<const DeclTypeSpec>> map_;
92 
93   friend llvm::raw_ostream &operator<<(
94       llvm::raw_ostream &, const ImplicitRules &);
95   friend void ShowImplicitRule(
96       llvm::raw_ostream &, const ImplicitRules &, char);
97 };
98 
99 // scope -> implicit rules for that scope
100 using ImplicitRulesMap = std::map<const Scope *, ImplicitRules>;
101 
102 // Track statement source locations and save messages.
103 class MessageHandler {
104 public:
105   MessageHandler() { DIE("MessageHandler: default-constructed"); }
106   explicit MessageHandler(SemanticsContext &c) : context_{&c} {}
107   Messages &messages() { return context_->messages(); };
108   const std::optional<SourceName> &currStmtSource() {
109     return context_->location();
110   }
111   void set_currStmtSource(const std::optional<SourceName> &source) {
112     context_->set_location(source);
113   }
114 
115   // Emit a message associated with the current statement source.
116   Message &Say(MessageFixedText &&);
117   Message &Say(MessageFormattedText &&);
118   // Emit a message about a SourceName
119   Message &Say(const SourceName &, MessageFixedText &&);
120   // Emit a formatted message associated with a source location.
121   template <typename... A>
122   Message &Say(const SourceName &source, MessageFixedText &&msg, A &&...args) {
123     return context_->Say(source, std::move(msg), std::forward<A>(args)...);
124   }
125 
126 private:
127   SemanticsContext *context_;
128 };
129 
130 // Inheritance graph for the parse tree visitation classes that follow:
131 //   BaseVisitor
132 //   + AttrsVisitor
133 //   | + DeclTypeSpecVisitor
134 //   |   + ImplicitRulesVisitor
135 //   |     + ScopeHandler -----------+--+
136 //   |       + ModuleVisitor ========|==+
137 //   |       + InterfaceVisitor      |  |
138 //   |       +-+ SubprogramVisitor ==|==+
139 //   + ArraySpecVisitor              |  |
140 //     + DeclarationVisitor <--------+  |
141 //       + ConstructVisitor             |
142 //         + ResolveNamesVisitor <------+
143 
144 class BaseVisitor {
145 public:
146   BaseVisitor() { DIE("BaseVisitor: default-constructed"); }
147   BaseVisitor(
148       SemanticsContext &c, ResolveNamesVisitor &v, ImplicitRulesMap &rules)
149       : implicitRulesMap_{&rules}, this_{&v}, context_{&c}, messageHandler_{c} {
150   }
151   template <typename T> void Walk(const T &);
152 
153   MessageHandler &messageHandler() { return messageHandler_; }
154   const std::optional<SourceName> &currStmtSource() {
155     return context_->location();
156   }
157   SemanticsContext &context() const { return *context_; }
158   evaluate::FoldingContext &GetFoldingContext() const {
159     return context_->foldingContext();
160   }
161   bool IsIntrinsic(
162       const SourceName &name, std::optional<Symbol::Flag> flag) const {
163     if (!flag) {
164       return context_->intrinsics().IsIntrinsic(name.ToString());
165     } else if (flag == Symbol::Flag::Function) {
166       return context_->intrinsics().IsIntrinsicFunction(name.ToString());
167     } else if (flag == Symbol::Flag::Subroutine) {
168       return context_->intrinsics().IsIntrinsicSubroutine(name.ToString());
169     } else {
170       DIE("expected Subroutine or Function flag");
171     }
172   }
173 
174   // Make a placeholder symbol for a Name that otherwise wouldn't have one.
175   // It is not in any scope and always has MiscDetails.
176   void MakePlaceholder(const parser::Name &, MiscDetails::Kind);
177 
178   template <typename T> common::IfNoLvalue<T, T> FoldExpr(T &&expr) {
179     return evaluate::Fold(GetFoldingContext(), std::move(expr));
180   }
181 
182   template <typename T> MaybeExpr EvaluateExpr(const T &expr) {
183     return FoldExpr(AnalyzeExpr(*context_, expr));
184   }
185 
186   template <typename T>
187   MaybeExpr EvaluateNonPointerInitializer(
188       const Symbol &symbol, const T &expr, parser::CharBlock source) {
189     if (!context().HasError(symbol)) {
190       if (auto maybeExpr{AnalyzeExpr(*context_, expr)}) {
191         auto restorer{GetFoldingContext().messages().SetLocation(source)};
192         return evaluate::NonPointerInitializationExpr(
193             symbol, std::move(*maybeExpr), GetFoldingContext());
194       }
195     }
196     return std::nullopt;
197   }
198 
199   template <typename T> MaybeIntExpr EvaluateIntExpr(const T &expr) {
200     return semantics::EvaluateIntExpr(*context_, expr);
201   }
202 
203   template <typename T>
204   MaybeSubscriptIntExpr EvaluateSubscriptIntExpr(const T &expr) {
205     if (MaybeIntExpr maybeIntExpr{EvaluateIntExpr(expr)}) {
206       return FoldExpr(evaluate::ConvertToType<evaluate::SubscriptInteger>(
207           std::move(*maybeIntExpr)));
208     } else {
209       return std::nullopt;
210     }
211   }
212 
213   template <typename... A> Message &Say(A &&...args) {
214     return messageHandler_.Say(std::forward<A>(args)...);
215   }
216   template <typename... A>
217   Message &Say(
218       const parser::Name &name, MessageFixedText &&text, const A &...args) {
219     return messageHandler_.Say(name.source, std::move(text), args...);
220   }
221 
222 protected:
223   ImplicitRulesMap *implicitRulesMap_{nullptr};
224 
225 private:
226   ResolveNamesVisitor *this_;
227   SemanticsContext *context_;
228   MessageHandler messageHandler_;
229 };
230 
231 // Provide Post methods to collect attributes into a member variable.
232 class AttrsVisitor : public virtual BaseVisitor {
233 public:
234   bool BeginAttrs(); // always returns true
235   Attrs GetAttrs();
236   Attrs EndAttrs();
237   bool SetPassNameOn(Symbol &);
238   void SetBindNameOn(Symbol &);
239   void Post(const parser::LanguageBindingSpec &);
240   bool Pre(const parser::IntentSpec &);
241   bool Pre(const parser::Pass &);
242 
243   bool CheckAndSet(Attr);
244 
245 // Simple case: encountering CLASSNAME causes ATTRNAME to be set.
246 #define HANDLE_ATTR_CLASS(CLASSNAME, ATTRNAME) \
247   bool Pre(const parser::CLASSNAME &) { \
248     CheckAndSet(Attr::ATTRNAME); \
249     return false; \
250   }
251   HANDLE_ATTR_CLASS(PrefixSpec::Elemental, ELEMENTAL)
252   HANDLE_ATTR_CLASS(PrefixSpec::Impure, IMPURE)
253   HANDLE_ATTR_CLASS(PrefixSpec::Module, MODULE)
254   HANDLE_ATTR_CLASS(PrefixSpec::Non_Recursive, NON_RECURSIVE)
255   HANDLE_ATTR_CLASS(PrefixSpec::Pure, PURE)
256   HANDLE_ATTR_CLASS(PrefixSpec::Recursive, RECURSIVE)
257   HANDLE_ATTR_CLASS(TypeAttrSpec::BindC, BIND_C)
258   HANDLE_ATTR_CLASS(BindAttr::Deferred, DEFERRED)
259   HANDLE_ATTR_CLASS(BindAttr::Non_Overridable, NON_OVERRIDABLE)
260   HANDLE_ATTR_CLASS(Abstract, ABSTRACT)
261   HANDLE_ATTR_CLASS(Allocatable, ALLOCATABLE)
262   HANDLE_ATTR_CLASS(Asynchronous, ASYNCHRONOUS)
263   HANDLE_ATTR_CLASS(Contiguous, CONTIGUOUS)
264   HANDLE_ATTR_CLASS(External, EXTERNAL)
265   HANDLE_ATTR_CLASS(Intrinsic, INTRINSIC)
266   HANDLE_ATTR_CLASS(NoPass, NOPASS)
267   HANDLE_ATTR_CLASS(Optional, OPTIONAL)
268   HANDLE_ATTR_CLASS(Parameter, PARAMETER)
269   HANDLE_ATTR_CLASS(Pointer, POINTER)
270   HANDLE_ATTR_CLASS(Protected, PROTECTED)
271   HANDLE_ATTR_CLASS(Save, SAVE)
272   HANDLE_ATTR_CLASS(Target, TARGET)
273   HANDLE_ATTR_CLASS(Value, VALUE)
274   HANDLE_ATTR_CLASS(Volatile, VOLATILE)
275 #undef HANDLE_ATTR_CLASS
276 
277 protected:
278   std::optional<Attrs> attrs_;
279 
280   Attr AccessSpecToAttr(const parser::AccessSpec &x) {
281     switch (x.v) {
282     case parser::AccessSpec::Kind::Public:
283       return Attr::PUBLIC;
284     case parser::AccessSpec::Kind::Private:
285       return Attr::PRIVATE;
286     }
287     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
288   }
289   Attr IntentSpecToAttr(const parser::IntentSpec &x) {
290     switch (x.v) {
291     case parser::IntentSpec::Intent::In:
292       return Attr::INTENT_IN;
293     case parser::IntentSpec::Intent::Out:
294       return Attr::INTENT_OUT;
295     case parser::IntentSpec::Intent::InOut:
296       return Attr::INTENT_INOUT;
297     }
298     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
299   }
300 
301 private:
302   bool IsDuplicateAttr(Attr);
303   bool HaveAttrConflict(Attr, Attr, Attr);
304   bool IsConflictingAttr(Attr);
305 
306   MaybeExpr bindName_; // from BIND(C, NAME="...")
307   std::optional<SourceName> passName_; // from PASS(...)
308 };
309 
310 // Find and create types from declaration-type-spec nodes.
311 class DeclTypeSpecVisitor : public AttrsVisitor {
312 public:
313   using AttrsVisitor::Post;
314   using AttrsVisitor::Pre;
315   void Post(const parser::IntrinsicTypeSpec::DoublePrecision &);
316   void Post(const parser::IntrinsicTypeSpec::DoubleComplex &);
317   void Post(const parser::DeclarationTypeSpec::ClassStar &);
318   void Post(const parser::DeclarationTypeSpec::TypeStar &);
319   bool Pre(const parser::TypeGuardStmt &);
320   void Post(const parser::TypeGuardStmt &);
321   void Post(const parser::TypeSpec &);
322 
323 protected:
324   struct State {
325     bool expectDeclTypeSpec{false}; // should see decl-type-spec only when true
326     const DeclTypeSpec *declTypeSpec{nullptr};
327     struct {
328       DerivedTypeSpec *type{nullptr};
329       DeclTypeSpec::Category category{DeclTypeSpec::TypeDerived};
330     } derived;
331     bool allowForwardReferenceToDerivedType{false};
332   };
333 
334   bool allowForwardReferenceToDerivedType() const {
335     return state_.allowForwardReferenceToDerivedType;
336   }
337   void set_allowForwardReferenceToDerivedType(bool yes) {
338     state_.allowForwardReferenceToDerivedType = yes;
339   }
340 
341   // Walk the parse tree of a type spec and return the DeclTypeSpec for it.
342   template <typename T>
343   const DeclTypeSpec *ProcessTypeSpec(const T &x, bool allowForward = false) {
344     auto restorer{common::ScopedSet(state_, State{})};
345     set_allowForwardReferenceToDerivedType(allowForward);
346     BeginDeclTypeSpec();
347     Walk(x);
348     const auto *type{GetDeclTypeSpec()};
349     EndDeclTypeSpec();
350     return type;
351   }
352 
353   const DeclTypeSpec *GetDeclTypeSpec();
354   void BeginDeclTypeSpec();
355   void EndDeclTypeSpec();
356   void SetDeclTypeSpec(const DeclTypeSpec &);
357   void SetDeclTypeSpecCategory(DeclTypeSpec::Category);
358   DeclTypeSpec::Category GetDeclTypeSpecCategory() const {
359     return state_.derived.category;
360   }
361   KindExpr GetKindParamExpr(
362       TypeCategory, const std::optional<parser::KindSelector> &);
363   void CheckForAbstractType(const Symbol &typeSymbol);
364 
365 private:
366   State state_;
367 
368   void MakeNumericType(TypeCategory, int kind);
369 };
370 
371 // Visit ImplicitStmt and related parse tree nodes and updates implicit rules.
372 class ImplicitRulesVisitor : public DeclTypeSpecVisitor {
373 public:
374   using DeclTypeSpecVisitor::Post;
375   using DeclTypeSpecVisitor::Pre;
376   using ImplicitNoneNameSpec = parser::ImplicitStmt::ImplicitNoneNameSpec;
377 
378   void Post(const parser::ParameterStmt &);
379   bool Pre(const parser::ImplicitStmt &);
380   bool Pre(const parser::LetterSpec &);
381   bool Pre(const parser::ImplicitSpec &);
382   void Post(const parser::ImplicitSpec &);
383 
384   const DeclTypeSpec *GetType(
385       SourceName name, bool respectImplicitNoneType = true) {
386     return implicitRules_->GetType(name, respectImplicitNoneType);
387   }
388   bool isImplicitNoneType() const {
389     return implicitRules_->isImplicitNoneType();
390   }
391   bool isImplicitNoneType(const Scope &scope) const {
392     return implicitRulesMap_->at(&scope).isImplicitNoneType();
393   }
394   bool isImplicitNoneExternal() const {
395     return implicitRules_->isImplicitNoneExternal();
396   }
397   void set_inheritFromParent(bool x) {
398     implicitRules_->set_inheritFromParent(x);
399   }
400 
401 protected:
402   void BeginScope(const Scope &);
403   void SetScope(const Scope &);
404 
405 private:
406   // implicit rules in effect for current scope
407   ImplicitRules *implicitRules_{nullptr};
408   std::optional<SourceName> prevImplicit_;
409   std::optional<SourceName> prevImplicitNone_;
410   std::optional<SourceName> prevImplicitNoneType_;
411   std::optional<SourceName> prevParameterStmt_;
412 
413   bool HandleImplicitNone(const std::list<ImplicitNoneNameSpec> &nameSpecs);
414 };
415 
416 // Track array specifications. They can occur in AttrSpec, EntityDecl,
417 // ObjectDecl, DimensionStmt, CommonBlockObject, or BasedPointerStmt.
418 // 1. INTEGER, DIMENSION(10) :: x
419 // 2. INTEGER :: x(10)
420 // 3. ALLOCATABLE :: x(:)
421 // 4. DIMENSION :: x(10)
422 // 5. COMMON x(10)
423 // 6. BasedPointerStmt
424 class ArraySpecVisitor : public virtual BaseVisitor {
425 public:
426   void Post(const parser::ArraySpec &);
427   void Post(const parser::ComponentArraySpec &);
428   void Post(const parser::CoarraySpec &);
429   void Post(const parser::AttrSpec &) { PostAttrSpec(); }
430   void Post(const parser::ComponentAttrSpec &) { PostAttrSpec(); }
431 
432 protected:
433   const ArraySpec &arraySpec();
434   void set_arraySpec(const ArraySpec arraySpec) { arraySpec_ = arraySpec; }
435   const ArraySpec &coarraySpec();
436   void BeginArraySpec();
437   void EndArraySpec();
438   void ClearArraySpec() { arraySpec_.clear(); }
439   void ClearCoarraySpec() { coarraySpec_.clear(); }
440 
441 private:
442   // arraySpec_/coarraySpec_ are populated from any ArraySpec/CoarraySpec
443   ArraySpec arraySpec_;
444   ArraySpec coarraySpec_;
445   // When an ArraySpec is under an AttrSpec or ComponentAttrSpec, it is moved
446   // into attrArraySpec_
447   ArraySpec attrArraySpec_;
448   ArraySpec attrCoarraySpec_;
449 
450   void PostAttrSpec();
451 };
452 
453 // Manage a stack of Scopes
454 class ScopeHandler : public ImplicitRulesVisitor {
455 public:
456   using ImplicitRulesVisitor::Post;
457   using ImplicitRulesVisitor::Pre;
458 
459   Scope &currScope() { return DEREF(currScope_); }
460   // The enclosing host procedure if current scope is in an internal procedure
461   Scope *GetHostProcedure();
462   // The innermost enclosing program unit scope, ignoring BLOCK and other
463   // construct scopes.
464   Scope &InclusiveScope();
465   // The enclosing scope, skipping derived types.
466   Scope &NonDerivedTypeScope();
467 
468   // Create a new scope and push it on the scope stack.
469   void PushScope(Scope::Kind kind, Symbol *symbol);
470   void PushScope(Scope &scope);
471   void PopScope();
472   void SetScope(Scope &);
473 
474   template <typename T> bool Pre(const parser::Statement<T> &x) {
475     messageHandler().set_currStmtSource(x.source);
476     currScope_->AddSourceRange(x.source);
477     return true;
478   }
479   template <typename T> void Post(const parser::Statement<T> &) {
480     messageHandler().set_currStmtSource(std::nullopt);
481   }
482 
483   // Special messages: already declared; referencing symbol's declaration;
484   // about a type; two names & locations
485   void SayAlreadyDeclared(const parser::Name &, Symbol &);
486   void SayAlreadyDeclared(const SourceName &, Symbol &);
487   void SayAlreadyDeclared(const SourceName &, const SourceName &);
488   void SayWithReason(
489       const parser::Name &, Symbol &, MessageFixedText &&, MessageFixedText &&);
490   void SayWithDecl(const parser::Name &, Symbol &, MessageFixedText &&);
491   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
492   void SayDerivedType(const SourceName &, MessageFixedText &&, const Scope &);
493   void Say2(const SourceName &, MessageFixedText &&, const SourceName &,
494       MessageFixedText &&);
495   void Say2(
496       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
497   void Say2(
498       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
499 
500   // Search for symbol by name in current, parent derived type, and
501   // containing scopes
502   Symbol *FindSymbol(const parser::Name &);
503   Symbol *FindSymbol(const Scope &, const parser::Name &);
504   // Search for name only in scope, not in enclosing scopes.
505   Symbol *FindInScope(const Scope &, const parser::Name &);
506   Symbol *FindInScope(const Scope &, const SourceName &);
507   template <typename T> Symbol *FindInScope(const T &name) {
508     return FindInScope(currScope(), name);
509   }
510   // Search for name in a derived type scope and its parents.
511   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
512   Symbol *FindInTypeOrParents(const parser::Name &);
513   void EraseSymbol(const parser::Name &);
514   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
515   // Make a new symbol with the name and attrs of an existing one
516   Symbol &CopySymbol(const SourceName &, const Symbol &);
517 
518   // Make symbols in the current or named scope
519   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
520   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
521   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
522   Symbol &MakeHostAssocSymbol(const parser::Name &, const Symbol &);
523 
524   template <typename D>
525   common::IfNoLvalue<Symbol &, D> MakeSymbol(
526       const parser::Name &name, D &&details) {
527     return MakeSymbol(name, Attrs{}, std::move(details));
528   }
529 
530   template <typename D>
531   common::IfNoLvalue<Symbol &, D> MakeSymbol(
532       const parser::Name &name, const Attrs &attrs, D &&details) {
533     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
534   }
535 
536   template <typename D>
537   common::IfNoLvalue<Symbol &, D> MakeSymbol(
538       const SourceName &name, const Attrs &attrs, D &&details) {
539     // Note: don't use FindSymbol here. If this is a derived type scope,
540     // we want to detect whether the name is already declared as a component.
541     auto *symbol{FindInScope(name)};
542     if (!symbol) {
543       symbol = &MakeSymbol(name, attrs);
544       symbol->set_details(std::move(details));
545       return *symbol;
546     }
547     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
548       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
549         if (!d->specific()) {
550           // derived type with same name as a generic
551           auto *derivedType{d->derivedType()};
552           if (!derivedType) {
553             derivedType =
554                 &currScope().MakeSymbol(name, attrs, std::move(details));
555             d->set_derivedType(*derivedType);
556           } else {
557             SayAlreadyDeclared(name, *derivedType);
558           }
559           return *derivedType;
560         }
561       }
562     }
563     if (symbol->CanReplaceDetails(details)) {
564       // update the existing symbol
565       symbol->attrs() |= attrs;
566       if constexpr (std::is_same_v<SubprogramDetails, D>) {
567         // Dummy argument defined by explicit interface
568         details.set_isDummy(IsDummy(*symbol));
569       }
570       symbol->set_details(std::move(details));
571       return *symbol;
572     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
573       symbol->attrs() |= attrs;
574       return *symbol;
575     } else {
576       if (!CheckPossibleBadForwardRef(*symbol)) {
577         SayAlreadyDeclared(name, *symbol);
578       }
579       // replace the old symbol with a new one with correct details
580       EraseSymbol(*symbol);
581       auto &result{MakeSymbol(name, attrs, std::move(details))};
582       context().SetError(result);
583       return result;
584     }
585   }
586 
587   void MakeExternal(Symbol &);
588 
589 protected:
590   // Apply the implicit type rules to this symbol.
591   void ApplyImplicitRules(Symbol &, bool allowForwardReference = false);
592   bool ImplicitlyTypeForwardRef(Symbol &);
593   void AcquireIntrinsicProcedureFlags(Symbol &);
594   const DeclTypeSpec *GetImplicitType(
595       Symbol &, bool respectImplicitNoneType = true);
596   bool ConvertToObjectEntity(Symbol &);
597   bool ConvertToProcEntity(Symbol &);
598 
599   const DeclTypeSpec &MakeNumericType(
600       TypeCategory, const std::optional<parser::KindSelector> &);
601   const DeclTypeSpec &MakeLogicalType(
602       const std::optional<parser::KindSelector> &);
603   void NotePossibleBadForwardRef(const parser::Name &);
604   std::optional<SourceName> HadForwardRef(const Symbol &) const;
605   bool CheckPossibleBadForwardRef(const Symbol &);
606 
607   bool inExecutionPart_{false};
608   bool inSpecificationPart_{false};
609   bool inEquivalenceStmt_{false};
610 
611   // Some information is collected from a specification part for deferred
612   // processing in DeclarationPartVisitor functions (e.g., CheckSaveStmts())
613   // that are called by ResolveNamesVisitor::FinishSpecificationPart().  Since
614   // specification parts can nest (e.g., INTERFACE bodies), the collected
615   // information that is not contained in the scope needs to be packaged
616   // and restorable.
617   struct SpecificationPartState {
618     std::set<SourceName> forwardRefs;
619     // Collect equivalence sets and process at end of specification part
620     std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets;
621     // Names of all common block objects in the scope
622     std::set<SourceName> commonBlockObjects;
623     // Info about about SAVE statements and attributes in current scope
624     struct {
625       std::optional<SourceName> saveAll; // "SAVE" without entity list
626       std::set<SourceName> entities; // names of entities with save attr
627       std::set<SourceName> commons; // names of common blocks with save attr
628     } saveInfo;
629   } specPartState_;
630 
631 private:
632   Scope *currScope_{nullptr};
633 };
634 
635 class ModuleVisitor : public virtual ScopeHandler {
636 public:
637   bool Pre(const parser::AccessStmt &);
638   bool Pre(const parser::Only &);
639   bool Pre(const parser::Rename::Names &);
640   bool Pre(const parser::Rename::Operators &);
641   bool Pre(const parser::UseStmt &);
642   void Post(const parser::UseStmt &);
643 
644   void BeginModule(const parser::Name &, bool isSubmodule);
645   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
646   void ApplyDefaultAccess();
647   void AddGenericUse(GenericDetails &, const SourceName &, const Symbol &);
648   void AddAndCheckExplicitIntrinsicUse(SourceName, bool isIntrinsic);
649   void ClearUseRenames() { useRenames_.clear(); }
650   void ClearUseOnly() { useOnly_.clear(); }
651   void ClearExplicitIntrinsicUses() {
652     explicitIntrinsicUses_.clear();
653     explicitNonIntrinsicUses_.clear();
654   }
655 
656 private:
657   // The default access spec for this module.
658   Attr defaultAccess_{Attr::PUBLIC};
659   // The location of the last AccessStmt without access-ids, if any.
660   std::optional<SourceName> prevAccessStmt_;
661   // The scope of the module during a UseStmt
662   Scope *useModuleScope_{nullptr};
663   // Names that have appeared in a rename clause of a USE statement
664   std::set<std::pair<SourceName, Scope *>> useRenames_;
665   // Names that have appeared in an ONLY clause of a USE statement
666   std::set<std::pair<SourceName, Scope *>> useOnly_;
667   // Module names that have appeared in USE statements with explicit
668   // INTRINSIC or NON_INTRINSIC keywords
669   std::set<SourceName> explicitIntrinsicUses_;
670   std::set<SourceName> explicitNonIntrinsicUses_;
671 
672   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
673   // A rename in a USE statement: local => use
674   struct SymbolRename {
675     Symbol *local{nullptr};
676     Symbol *use{nullptr};
677   };
678   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
679   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
680   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
681   void DoAddUse(const SourceName &, const SourceName &, Symbol &localSymbol,
682       const Symbol &useSymbol);
683   void AddUse(const GenericSpecInfo &);
684   // If appropriate, erase a previously USE-associated symbol
685   void EraseRenamedSymbol(const Symbol &);
686   // Record a name appearing in a USE rename clause
687   void AddUseRename(const SourceName &name) {
688     useRenames_.emplace(std::make_pair(name, useModuleScope_));
689   }
690   bool IsUseRenamed(const SourceName &name) const {
691     return useRenames_.find({name, useModuleScope_}) != useRenames_.end();
692   }
693   // Record a name appearing in a USE ONLY clause
694   void AddUseOnly(const SourceName &name) {
695     useOnly_.emplace(std::make_pair(name, useModuleScope_));
696   }
697   bool IsUseOnly(const SourceName &name) const {
698     return useOnly_.find({name, useModuleScope_}) != useOnly_.end();
699   }
700   Scope *FindModule(const parser::Name &, std::optional<bool> isIntrinsic,
701       Scope *ancestor = nullptr);
702 };
703 
704 class InterfaceVisitor : public virtual ScopeHandler {
705 public:
706   bool Pre(const parser::InterfaceStmt &);
707   void Post(const parser::InterfaceStmt &);
708   void Post(const parser::EndInterfaceStmt &);
709   bool Pre(const parser::GenericSpec &);
710   bool Pre(const parser::ProcedureStmt &);
711   bool Pre(const parser::GenericStmt &);
712   void Post(const parser::GenericStmt &);
713 
714   bool inInterfaceBlock() const;
715   bool isGeneric() const;
716   bool isAbstract() const;
717 
718 protected:
719   Symbol &GetGenericSymbol() {
720     return DEREF(genericInfo_.top().symbol);
721   }
722   // Add to generic the symbol for the subprogram with the same name
723   void CheckGenericProcedures(Symbol &);
724 
725 private:
726   // A new GenericInfo is pushed for each interface block and generic stmt
727   struct GenericInfo {
728     GenericInfo(bool isInterface, bool isAbstract = false)
729         : isInterface{isInterface}, isAbstract{isAbstract} {}
730     bool isInterface; // in interface block
731     bool isAbstract; // in abstract interface block
732     Symbol *symbol{nullptr}; // the generic symbol being defined
733   };
734   std::stack<GenericInfo> genericInfo_;
735   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
736   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
737 
738   using ProcedureKind = parser::ProcedureStmt::Kind;
739   // mapping of generic to its specific proc names and kinds
740   std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>
741       specificProcs_;
742 
743   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
744   void ResolveSpecificsInGeneric(Symbol &generic);
745 };
746 
747 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
748 public:
749   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
750   bool Pre(const parser::SubroutineStmt &);
751   void Post(const parser::SubroutineStmt &);
752   bool Pre(const parser::FunctionStmt &);
753   void Post(const parser::FunctionStmt &);
754   bool Pre(const parser::EntryStmt &);
755   void Post(const parser::EntryStmt &);
756   bool Pre(const parser::InterfaceBody::Subroutine &);
757   void Post(const parser::InterfaceBody::Subroutine &);
758   bool Pre(const parser::InterfaceBody::Function &);
759   void Post(const parser::InterfaceBody::Function &);
760   bool Pre(const parser::Suffix &);
761   bool Pre(const parser::PrefixSpec &);
762   void Post(const parser::ImplicitPart &);
763 
764   bool BeginSubprogram(
765       const parser::Name &, Symbol::Flag, bool hasModulePrefix = false);
766   bool BeginMpSubprogram(const parser::Name &);
767   void PushBlockDataScope(const parser::Name &);
768   void EndSubprogram();
769 
770 protected:
771   // Set when we see a stmt function that is really an array element assignment
772   bool badStmtFuncFound_{false};
773 
774 private:
775   // Info about the current function: parse tree of the type in the PrefixSpec;
776   // name and symbol of the function result from the Suffix; source location.
777   struct {
778     const parser::DeclarationTypeSpec *parsedType{nullptr};
779     const parser::Name *resultName{nullptr};
780     Symbol *resultSymbol{nullptr};
781     std::optional<SourceName> source;
782   } funcInfo_;
783 
784   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
785   // so that it can be replaced by a later definition.
786   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
787   void CheckExtantProc(const parser::Name &, Symbol::Flag);
788   // Create a subprogram symbol in the current scope and push a new scope.
789   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag);
790   Symbol *GetSpecificFromGeneric(const parser::Name &);
791   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
792 };
793 
794 class DeclarationVisitor : public ArraySpecVisitor,
795                            public virtual ScopeHandler {
796 public:
797   using ArraySpecVisitor::Post;
798   using ScopeHandler::Post;
799   using ScopeHandler::Pre;
800 
801   bool Pre(const parser::Initialization &);
802   void Post(const parser::EntityDecl &);
803   void Post(const parser::ObjectDecl &);
804   void Post(const parser::PointerDecl &);
805   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
806   void Post(const parser::BindStmt &) { EndAttrs(); }
807   bool Pre(const parser::BindEntity &);
808   bool Pre(const parser::OldParameterStmt &);
809   bool Pre(const parser::NamedConstantDef &);
810   bool Pre(const parser::NamedConstant &);
811   void Post(const parser::EnumDef &);
812   bool Pre(const parser::Enumerator &);
813   bool Pre(const parser::AccessSpec &);
814   bool Pre(const parser::AsynchronousStmt &);
815   bool Pre(const parser::ContiguousStmt &);
816   bool Pre(const parser::ExternalStmt &);
817   bool Pre(const parser::IntentStmt &);
818   bool Pre(const parser::IntrinsicStmt &);
819   bool Pre(const parser::OptionalStmt &);
820   bool Pre(const parser::ProtectedStmt &);
821   bool Pre(const parser::ValueStmt &);
822   bool Pre(const parser::VolatileStmt &);
823   bool Pre(const parser::AllocatableStmt &) {
824     objectDeclAttr_ = Attr::ALLOCATABLE;
825     return true;
826   }
827   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
828   bool Pre(const parser::TargetStmt &) {
829     objectDeclAttr_ = Attr::TARGET;
830     return true;
831   }
832   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
833   void Post(const parser::DimensionStmt::Declaration &);
834   void Post(const parser::CodimensionDecl &);
835   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
836   void Post(const parser::TypeDeclarationStmt &);
837   void Post(const parser::IntegerTypeSpec &);
838   void Post(const parser::IntrinsicTypeSpec::Real &);
839   void Post(const parser::IntrinsicTypeSpec::Complex &);
840   void Post(const parser::IntrinsicTypeSpec::Logical &);
841   void Post(const parser::IntrinsicTypeSpec::Character &);
842   void Post(const parser::CharSelector::LengthAndKind &);
843   void Post(const parser::CharLength &);
844   void Post(const parser::LengthSelector &);
845   bool Pre(const parser::KindParam &);
846   bool Pre(const parser::DeclarationTypeSpec::Type &);
847   void Post(const parser::DeclarationTypeSpec::Type &);
848   bool Pre(const parser::DeclarationTypeSpec::Class &);
849   void Post(const parser::DeclarationTypeSpec::Class &);
850   void Post(const parser::DeclarationTypeSpec::Record &);
851   void Post(const parser::DerivedTypeSpec &);
852   bool Pre(const parser::DerivedTypeDef &);
853   bool Pre(const parser::DerivedTypeStmt &);
854   void Post(const parser::DerivedTypeStmt &);
855   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
856   void Post(const parser::TypeParamDefStmt &);
857   bool Pre(const parser::TypeAttrSpec::Extends &);
858   bool Pre(const parser::PrivateStmt &);
859   bool Pre(const parser::SequenceStmt &);
860   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
861   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
862   void Post(const parser::ComponentDecl &);
863   void Post(const parser::FillDecl &);
864   bool Pre(const parser::ProcedureDeclarationStmt &);
865   void Post(const parser::ProcedureDeclarationStmt &);
866   bool Pre(const parser::DataComponentDefStmt &); // returns false
867   bool Pre(const parser::ProcComponentDefStmt &);
868   void Post(const parser::ProcComponentDefStmt &);
869   bool Pre(const parser::ProcPointerInit &);
870   void Post(const parser::ProcInterface &);
871   void Post(const parser::ProcDecl &);
872   bool Pre(const parser::TypeBoundProcedurePart &);
873   void Post(const parser::TypeBoundProcedurePart &);
874   void Post(const parser::ContainsStmt &);
875   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
876   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
877   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
878   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
879   void Post(const parser::FinalProcedureStmt &);
880   bool Pre(const parser::TypeBoundGenericStmt &);
881   bool Pre(const parser::StructureDef &); // returns false
882   bool Pre(const parser::Union::UnionStmt &);
883   bool Pre(const parser::StructureField &);
884   void Post(const parser::StructureField &);
885   bool Pre(const parser::AllocateStmt &);
886   void Post(const parser::AllocateStmt &);
887   bool Pre(const parser::StructureConstructor &);
888   bool Pre(const parser::NamelistStmt::Group &);
889   bool Pre(const parser::IoControlSpec &);
890   bool Pre(const parser::CommonStmt::Block &);
891   bool Pre(const parser::CommonBlockObject &);
892   void Post(const parser::CommonBlockObject &);
893   bool Pre(const parser::EquivalenceStmt &);
894   bool Pre(const parser::SaveStmt &);
895   bool Pre(const parser::BasedPointerStmt &);
896 
897   void PointerInitialization(
898       const parser::Name &, const parser::InitialDataTarget &);
899   void PointerInitialization(
900       const parser::Name &, const parser::ProcPointerInit &);
901   void NonPointerInitialization(
902       const parser::Name &, const parser::ConstantExpr &);
903   void CheckExplicitInterface(const parser::Name &);
904   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
905 
906   const parser::Name *ResolveDesignator(const parser::Designator &);
907 
908 protected:
909   bool BeginDecl();
910   void EndDecl();
911   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
912   // Make sure that there's an entity in an enclosing scope called Name
913   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
914   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
915   // it comes from the entity in the containing scope, or implicit rules.
916   // Return pointer to the new symbol, or nullptr on error.
917   Symbol *DeclareLocalEntity(const parser::Name &);
918   // Declare a statement entity (i.e., an implied DO loop index for
919   // a DATA statement or an array constructor).  If there isn't an explict
920   // type specified, implicit rules apply. Return pointer to the new symbol,
921   // or nullptr on error.
922   Symbol *DeclareStatementEntity(const parser::DoVariable &,
923       const std::optional<parser::IntegerTypeSpec> &);
924   Symbol &MakeCommonBlockSymbol(const parser::Name &);
925   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
926   bool CheckUseError(const parser::Name &);
927   void CheckAccessibility(const SourceName &, bool, Symbol &);
928   void CheckCommonBlocks();
929   void CheckSaveStmts();
930   void CheckEquivalenceSets();
931   bool CheckNotInBlock(const char *);
932   bool NameIsKnownOrIntrinsic(const parser::Name &);
933 
934   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
935   // or nullptr in case of error.
936   const parser::Name *ResolveStructureComponent(
937       const parser::StructureComponent &);
938   const parser::Name *ResolveDataRef(const parser::DataRef &);
939   const parser::Name *ResolveName(const parser::Name &);
940   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
941   Symbol *NoteInterfaceName(const parser::Name &);
942   bool IsUplevelReference(const Symbol &);
943 
944   std::optional<SourceName> BeginCheckOnIndexUseInOwnBounds(
945       const parser::DoVariable &name) {
946     std::optional<SourceName> result{checkIndexUseInOwnBounds_};
947     checkIndexUseInOwnBounds_ = name.thing.thing.source;
948     return result;
949   }
950   void EndCheckOnIndexUseInOwnBounds(const std::optional<SourceName> &restore) {
951     checkIndexUseInOwnBounds_ = restore;
952   }
953 
954 private:
955   // The attribute corresponding to the statement containing an ObjectDecl
956   std::optional<Attr> objectDeclAttr_;
957   // Info about current character type while walking DeclTypeSpec.
958   // Also captures any "*length" specifier on an individual declaration.
959   struct {
960     std::optional<ParamValue> length;
961     std::optional<KindExpr> kind;
962   } charInfo_;
963   // Info about current derived type or STRUCTURE while walking
964   // DerivedTypeDef / StructureDef
965   struct {
966     const parser::Name *extends{nullptr}; // EXTENDS(name)
967     bool privateComps{false}; // components are private by default
968     bool privateBindings{false}; // bindings are private by default
969     bool sawContains{false}; // currently processing bindings
970     bool sequence{false}; // is a sequence type
971     const Symbol *type{nullptr}; // derived type being defined
972     bool isStructure{false}; // is a DEC STRUCTURE
973   } derivedTypeInfo_;
974   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
975   // the interface name, if any.
976   const parser::Name *interfaceName_{nullptr};
977   // Map type-bound generic to binding names of its specific bindings
978   std::multimap<Symbol *, const parser::Name *> genericBindings_;
979   // Info about current ENUM
980   struct EnumeratorState {
981     // Enum value must hold inside a C_INT (7.6.2).
982     std::optional<int> value{0};
983   } enumerationState_;
984   // Set for OldParameterStmt processing
985   bool inOldStyleParameterStmt_{false};
986   // Set when walking DATA & array constructor implied DO loop bounds
987   // to warn about use of the implied DO intex therein.
988   std::optional<SourceName> checkIndexUseInOwnBounds_;
989 
990   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
991   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
992   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
993   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
994   void SetType(const parser::Name &, const DeclTypeSpec &);
995   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
996   std::optional<DerivedTypeSpec> ResolveExtendsType(
997       const parser::Name &, const parser::Name *);
998   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
999   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1000   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
1001   ParamValue GetParamValue(
1002       const parser::TypeParamValue &, common::TypeParamAttr attr);
1003   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
1004   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
1005   Attrs HandleSaveName(const SourceName &, Attrs);
1006   void AddSaveName(std::set<SourceName> &, const SourceName &);
1007   void SetSaveAttr(Symbol &);
1008   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1009   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1010   void Initialization(const parser::Name &, const parser::Initialization &,
1011       bool inComponentDecl);
1012   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
1013   bool CheckForHostAssociatedImplicit(const parser::Name &);
1014 
1015   // Declare an object or procedure entity.
1016   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1017   template <typename T>
1018   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1019     Symbol &symbol{MakeSymbol(name, attrs)};
1020     if (context().HasError(symbol) || symbol.has<T>()) {
1021       return symbol; // OK or error already reported
1022     } else if (symbol.has<UnknownDetails>()) {
1023       symbol.set_details(T{});
1024       return symbol;
1025     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1026       symbol.set_details(T{std::move(*details)});
1027       return symbol;
1028     } else if (std::is_same_v<EntityDetails, T> &&
1029         (symbol.has<ObjectEntityDetails>() ||
1030             symbol.has<ProcEntityDetails>())) {
1031       return symbol; // OK
1032     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1033       Say(name.source,
1034           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1035           name.source, GetUsedModule(*details).name());
1036     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1037       if (details->kind() == SubprogramKind::Module) {
1038         Say2(name,
1039             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1040             symbol, "Module procedure definition"_en_US);
1041       } else if (details->kind() == SubprogramKind::Internal) {
1042         Say2(name,
1043             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1044             symbol, "Internal procedure definition"_en_US);
1045       } else {
1046         DIE("unexpected kind");
1047       }
1048     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1049         symbol.has<ProcEntityDetails>()) {
1050       SayWithDecl(
1051           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1052     } else if (std::is_same_v<ProcEntityDetails, T> &&
1053         symbol.has<ObjectEntityDetails>()) {
1054       if (InCommonBlock(symbol)) {
1055         SayWithDecl(name, symbol,
1056             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1057       } else {
1058         SayWithDecl(
1059             name, symbol, "'%s' is already declared as an object"_err_en_US);
1060       }
1061     } else if (!CheckPossibleBadForwardRef(symbol)) {
1062       SayAlreadyDeclared(name, symbol);
1063     }
1064     context().SetError(symbol);
1065     return symbol;
1066   }
1067   bool HasCycle(const Symbol &, const ProcInterface &);
1068 };
1069 
1070 // Resolve construct entities and statement entities.
1071 // Check that construct names don't conflict with other names.
1072 class ConstructVisitor : public virtual DeclarationVisitor {
1073 public:
1074   bool Pre(const parser::ConcurrentHeader &);
1075   bool Pre(const parser::LocalitySpec::Local &);
1076   bool Pre(const parser::LocalitySpec::LocalInit &);
1077   bool Pre(const parser::LocalitySpec::Shared &);
1078   bool Pre(const parser::AcSpec &);
1079   bool Pre(const parser::AcImpliedDo &);
1080   bool Pre(const parser::DataImpliedDo &);
1081   bool Pre(const parser::DataIDoObject &);
1082   bool Pre(const parser::DataStmtObject &);
1083   bool Pre(const parser::DataStmtValue &);
1084   bool Pre(const parser::DoConstruct &);
1085   void Post(const parser::DoConstruct &);
1086   bool Pre(const parser::ForallConstruct &);
1087   void Post(const parser::ForallConstruct &);
1088   bool Pre(const parser::ForallStmt &);
1089   void Post(const parser::ForallStmt &);
1090   bool Pre(const parser::BlockStmt &);
1091   bool Pre(const parser::EndBlockStmt &);
1092   void Post(const parser::Selector &);
1093   void Post(const parser::AssociateStmt &);
1094   void Post(const parser::EndAssociateStmt &);
1095   bool Pre(const parser::Association &);
1096   void Post(const parser::SelectTypeStmt &);
1097   void Post(const parser::SelectRankStmt &);
1098   bool Pre(const parser::SelectTypeConstruct &);
1099   void Post(const parser::SelectTypeConstruct &);
1100   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1101   void Post(const parser::SelectTypeConstruct::TypeCase &);
1102   // Creates Block scopes with neither symbol name nor symbol details.
1103   bool Pre(const parser::SelectRankConstruct::RankCase &);
1104   void Post(const parser::SelectRankConstruct::RankCase &);
1105   void Post(const parser::TypeGuardStmt::Guard &);
1106   void Post(const parser::SelectRankCaseStmt::Rank &);
1107   bool Pre(const parser::ChangeTeamStmt &);
1108   void Post(const parser::EndChangeTeamStmt &);
1109   void Post(const parser::CoarrayAssociation &);
1110 
1111   // Definitions of construct names
1112   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1113   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1114   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1115   bool Pre(const parser::LabelDoStmt &) {
1116     return false; // error recovery
1117   }
1118   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1119   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1120   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1121   bool Pre(const parser::SelectRankConstruct &);
1122   void Post(const parser::SelectRankConstruct &);
1123   bool Pre(const parser::SelectRankStmt &x) {
1124     return CheckDef(std::get<0>(x.t));
1125   }
1126   bool Pre(const parser::SelectTypeStmt &x) {
1127     return CheckDef(std::get<0>(x.t));
1128   }
1129 
1130   // References to construct names
1131   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1132   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1133   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1134   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1135   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1136   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1137   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1138   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1139   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1140   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1141   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1142   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1143   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1144   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1145   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1146 
1147 private:
1148   // R1105 selector -> expr | variable
1149   // expr is set in either case unless there were errors
1150   struct Selector {
1151     Selector() {}
1152     Selector(const SourceName &source, MaybeExpr &&expr)
1153         : source{source}, expr{std::move(expr)} {}
1154     operator bool() const { return expr.has_value(); }
1155     parser::CharBlock source;
1156     MaybeExpr expr;
1157   };
1158   // association -> [associate-name =>] selector
1159   struct Association {
1160     const parser::Name *name{nullptr};
1161     Selector selector;
1162   };
1163   std::vector<Association> associationStack_;
1164   Association *currentAssociation_{nullptr};
1165 
1166   template <typename T> bool CheckDef(const T &t) {
1167     return CheckDef(std::get<std::optional<parser::Name>>(t));
1168   }
1169   template <typename T> void CheckRef(const T &t) {
1170     CheckRef(std::get<std::optional<parser::Name>>(t));
1171   }
1172   bool CheckDef(const std::optional<parser::Name> &);
1173   void CheckRef(const std::optional<parser::Name> &);
1174   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1175   const DeclTypeSpec &ToDeclTypeSpec(
1176       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1177   Symbol *MakeAssocEntity();
1178   void SetTypeFromAssociation(Symbol &);
1179   void SetAttrsFromAssociation(Symbol &);
1180   Selector ResolveSelector(const parser::Selector &);
1181   void ResolveIndexName(const parser::ConcurrentControl &control);
1182   void SetCurrentAssociation(std::size_t n);
1183   Association &GetCurrentAssociation();
1184   void PushAssociation();
1185   void PopAssociation(std::size_t count = 1);
1186 };
1187 
1188 // Create scopes for OpenACC constructs
1189 class AccVisitor : public virtual DeclarationVisitor {
1190 public:
1191   void AddAccSourceRange(const parser::CharBlock &);
1192 
1193   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1194 
1195   bool Pre(const parser::OpenACCBlockConstruct &);
1196   void Post(const parser::OpenACCBlockConstruct &);
1197   bool Pre(const parser::AccBeginBlockDirective &x) {
1198     AddAccSourceRange(x.source);
1199     return true;
1200   }
1201   void Post(const parser::AccBeginBlockDirective &) {
1202     messageHandler().set_currStmtSource(std::nullopt);
1203   }
1204   bool Pre(const parser::AccEndBlockDirective &x) {
1205     AddAccSourceRange(x.source);
1206     return true;
1207   }
1208   void Post(const parser::AccEndBlockDirective &) {
1209     messageHandler().set_currStmtSource(std::nullopt);
1210   }
1211   bool Pre(const parser::AccBeginLoopDirective &x) {
1212     AddAccSourceRange(x.source);
1213     return true;
1214   }
1215   void Post(const parser::AccBeginLoopDirective &x) {
1216     messageHandler().set_currStmtSource(std::nullopt);
1217   }
1218 };
1219 
1220 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1221   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1222   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1223   switch (beginDir.v) {
1224   case llvm::acc::Directive::ACCD_data:
1225   case llvm::acc::Directive::ACCD_host_data:
1226   case llvm::acc::Directive::ACCD_kernels:
1227   case llvm::acc::Directive::ACCD_parallel:
1228   case llvm::acc::Directive::ACCD_serial:
1229     return true;
1230   default:
1231     return false;
1232   }
1233 }
1234 
1235 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1236   messageHandler().set_currStmtSource(source);
1237   currScope().AddSourceRange(source);
1238 }
1239 
1240 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1241   if (NeedsScope(x)) {
1242     PushScope(Scope::Kind::Block, nullptr);
1243   }
1244   return true;
1245 }
1246 
1247 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1248   if (NeedsScope(x)) {
1249     PopScope();
1250   }
1251 }
1252 
1253 // Create scopes for OpenMP constructs
1254 class OmpVisitor : public virtual DeclarationVisitor {
1255 public:
1256   void AddOmpSourceRange(const parser::CharBlock &);
1257 
1258   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1259 
1260   bool Pre(const parser::OpenMPBlockConstruct &);
1261   void Post(const parser::OpenMPBlockConstruct &);
1262   bool Pre(const parser::OmpBeginBlockDirective &x) {
1263     AddOmpSourceRange(x.source);
1264     return true;
1265   }
1266   void Post(const parser::OmpBeginBlockDirective &) {
1267     messageHandler().set_currStmtSource(std::nullopt);
1268   }
1269   bool Pre(const parser::OmpEndBlockDirective &x) {
1270     AddOmpSourceRange(x.source);
1271     return true;
1272   }
1273   void Post(const parser::OmpEndBlockDirective &) {
1274     messageHandler().set_currStmtSource(std::nullopt);
1275   }
1276 
1277   bool Pre(const parser::OpenMPLoopConstruct &) {
1278     PushScope(Scope::Kind::Block, nullptr);
1279     return true;
1280   }
1281   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1282   bool Pre(const parser::OmpBeginLoopDirective &x) {
1283     AddOmpSourceRange(x.source);
1284     return true;
1285   }
1286   void Post(const parser::OmpBeginLoopDirective &) {
1287     messageHandler().set_currStmtSource(std::nullopt);
1288   }
1289   bool Pre(const parser::OmpEndLoopDirective &x) {
1290     AddOmpSourceRange(x.source);
1291     return true;
1292   }
1293   void Post(const parser::OmpEndLoopDirective &) {
1294     messageHandler().set_currStmtSource(std::nullopt);
1295   }
1296 
1297   bool Pre(const parser::OpenMPSectionsConstruct &) {
1298     PushScope(Scope::Kind::Block, nullptr);
1299     return true;
1300   }
1301   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1302   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1303     AddOmpSourceRange(x.source);
1304     return true;
1305   }
1306   void Post(const parser::OmpBeginSectionsDirective &) {
1307     messageHandler().set_currStmtSource(std::nullopt);
1308   }
1309   bool Pre(const parser::OmpEndSectionsDirective &x) {
1310     AddOmpSourceRange(x.source);
1311     return true;
1312   }
1313   void Post(const parser::OmpEndSectionsDirective &) {
1314     messageHandler().set_currStmtSource(std::nullopt);
1315   }
1316 };
1317 
1318 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1319   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1320   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1321   switch (beginDir.v) {
1322   case llvm::omp::Directive::OMPD_target_data:
1323   case llvm::omp::Directive::OMPD_master:
1324   case llvm::omp::Directive::OMPD_ordered:
1325   case llvm::omp::Directive::OMPD_taskgroup:
1326     return false;
1327   default:
1328     return true;
1329   }
1330 }
1331 
1332 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1333   messageHandler().set_currStmtSource(source);
1334   currScope().AddSourceRange(source);
1335 }
1336 
1337 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1338   if (NeedsScope(x)) {
1339     PushScope(Scope::Kind::Block, nullptr);
1340   }
1341   return true;
1342 }
1343 
1344 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1345   if (NeedsScope(x)) {
1346     PopScope();
1347   }
1348 }
1349 
1350 // Walk the parse tree and resolve names to symbols.
1351 class ResolveNamesVisitor : public virtual ScopeHandler,
1352                             public ModuleVisitor,
1353                             public SubprogramVisitor,
1354                             public ConstructVisitor,
1355                             public OmpVisitor,
1356                             public AccVisitor {
1357 public:
1358   using AccVisitor::Post;
1359   using AccVisitor::Pre;
1360   using ArraySpecVisitor::Post;
1361   using ConstructVisitor::Post;
1362   using ConstructVisitor::Pre;
1363   using DeclarationVisitor::Post;
1364   using DeclarationVisitor::Pre;
1365   using ImplicitRulesVisitor::Post;
1366   using ImplicitRulesVisitor::Pre;
1367   using InterfaceVisitor::Post;
1368   using InterfaceVisitor::Pre;
1369   using ModuleVisitor::Post;
1370   using ModuleVisitor::Pre;
1371   using OmpVisitor::Post;
1372   using OmpVisitor::Pre;
1373   using ScopeHandler::Post;
1374   using ScopeHandler::Pre;
1375   using SubprogramVisitor::Post;
1376   using SubprogramVisitor::Pre;
1377 
1378   ResolveNamesVisitor(
1379       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1380       : BaseVisitor{context, *this, rules}, topScope_{top} {
1381     PushScope(top);
1382   }
1383 
1384   Scope &topScope() const { return topScope_; }
1385 
1386   // Default action for a parse tree node is to visit children.
1387   template <typename T> bool Pre(const T &) { return true; }
1388   template <typename T> void Post(const T &) {}
1389 
1390   bool Pre(const parser::SpecificationPart &);
1391   void Post(const parser::Program &);
1392   bool Pre(const parser::ImplicitStmt &);
1393   void Post(const parser::PointerObject &);
1394   void Post(const parser::AllocateObject &);
1395   bool Pre(const parser::PointerAssignmentStmt &);
1396   void Post(const parser::Designator &);
1397   template <typename A, typename B>
1398   void Post(const parser::LoopBounds<A, B> &x) {
1399     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1400   }
1401   void Post(const parser::ProcComponentRef &);
1402   bool Pre(const parser::FunctionReference &);
1403   bool Pre(const parser::CallStmt &);
1404   bool Pre(const parser::ImportStmt &);
1405   void Post(const parser::TypeGuardStmt &);
1406   bool Pre(const parser::StmtFunctionStmt &);
1407   bool Pre(const parser::DefinedOpName &);
1408   bool Pre(const parser::ProgramUnit &);
1409   void Post(const parser::AssignStmt &);
1410   void Post(const parser::AssignedGotoStmt &);
1411 
1412   // These nodes should never be reached: they are handled in ProgramUnit
1413   bool Pre(const parser::MainProgram &) {
1414     llvm_unreachable("This node is handled in ProgramUnit");
1415   }
1416   bool Pre(const parser::FunctionSubprogram &) {
1417     llvm_unreachable("This node is handled in ProgramUnit");
1418   }
1419   bool Pre(const parser::SubroutineSubprogram &) {
1420     llvm_unreachable("This node is handled in ProgramUnit");
1421   }
1422   bool Pre(const parser::SeparateModuleSubprogram &) {
1423     llvm_unreachable("This node is handled in ProgramUnit");
1424   }
1425   bool Pre(const parser::Module &) {
1426     llvm_unreachable("This node is handled in ProgramUnit");
1427   }
1428   bool Pre(const parser::Submodule &) {
1429     llvm_unreachable("This node is handled in ProgramUnit");
1430   }
1431   bool Pre(const parser::BlockData &) {
1432     llvm_unreachable("This node is handled in ProgramUnit");
1433   }
1434 
1435   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1436 
1437   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1438 
1439 private:
1440   // Kind of procedure we are expecting to see in a ProcedureDesignator
1441   std::optional<Symbol::Flag> expectedProcFlag_;
1442   std::optional<SourceName> prevImportStmt_;
1443   Scope &topScope_;
1444 
1445   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1446   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1447   void CreateGeneric(const parser::GenericSpec &);
1448   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1449   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1450   void CheckImports();
1451   void CheckImport(const SourceName &, const SourceName &);
1452   void HandleCall(Symbol::Flag, const parser::Call &);
1453   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1454   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1455   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1456   void ResolveSpecificationParts(ProgramTree &);
1457   void AddSubpNames(ProgramTree &);
1458   bool BeginScopeForNode(const ProgramTree &);
1459   void FinishSpecificationParts(const ProgramTree &);
1460   void FinishDerivedTypeInstantiation(Scope &);
1461   void ResolveExecutionParts(const ProgramTree &);
1462 };
1463 
1464 // ImplicitRules implementation
1465 
1466 bool ImplicitRules::isImplicitNoneType() const {
1467   if (isImplicitNoneType_) {
1468     return true;
1469   } else if (map_.empty() && inheritFromParent_) {
1470     return parent_->isImplicitNoneType();
1471   } else {
1472     return false; // default if not specified
1473   }
1474 }
1475 
1476 bool ImplicitRules::isImplicitNoneExternal() const {
1477   if (isImplicitNoneExternal_) {
1478     return true;
1479   } else if (inheritFromParent_) {
1480     return parent_->isImplicitNoneExternal();
1481   } else {
1482     return false; // default if not specified
1483   }
1484 }
1485 
1486 const DeclTypeSpec *ImplicitRules::GetType(
1487     SourceName name, bool respectImplicitNoneType) const {
1488   char ch{name.begin()[0]};
1489   if (isImplicitNoneType_ && respectImplicitNoneType) {
1490     return nullptr;
1491   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1492     return &*it->second;
1493   } else if (inheritFromParent_) {
1494     return parent_->GetType(name, respectImplicitNoneType);
1495   } else if (ch >= 'i' && ch <= 'n') {
1496     return &context_.MakeNumericType(TypeCategory::Integer);
1497   } else if (ch >= 'a' && ch <= 'z') {
1498     return &context_.MakeNumericType(TypeCategory::Real);
1499   } else {
1500     return nullptr;
1501   }
1502 }
1503 
1504 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1505     parser::Location fromLetter, parser::Location toLetter) {
1506   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1507     auto res{map_.emplace(ch, type)};
1508     if (!res.second) {
1509       context_.Say(parser::CharBlock{fromLetter},
1510           "More than one implicit type specified for '%c'"_err_en_US, ch);
1511     }
1512     if (ch == *toLetter) {
1513       break;
1514     }
1515   }
1516 }
1517 
1518 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1519 // Return '\0' for the char after 'z'.
1520 char ImplicitRules::Incr(char ch) {
1521   switch (ch) {
1522   case 'i':
1523     return 'j';
1524   case 'r':
1525     return 's';
1526   case 'z':
1527     return '\0';
1528   default:
1529     return ch + 1;
1530   }
1531 }
1532 
1533 llvm::raw_ostream &operator<<(
1534     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1535   o << "ImplicitRules:\n";
1536   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1537     ShowImplicitRule(o, implicitRules, ch);
1538   }
1539   ShowImplicitRule(o, implicitRules, '_');
1540   ShowImplicitRule(o, implicitRules, '$');
1541   ShowImplicitRule(o, implicitRules, '@');
1542   return o;
1543 }
1544 void ShowImplicitRule(
1545     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1546   auto it{implicitRules.map_.find(ch)};
1547   if (it != implicitRules.map_.end()) {
1548     o << "  " << ch << ": " << *it->second << '\n';
1549   }
1550 }
1551 
1552 template <typename T> void BaseVisitor::Walk(const T &x) {
1553   parser::Walk(x, *this_);
1554 }
1555 
1556 void BaseVisitor::MakePlaceholder(
1557     const parser::Name &name, MiscDetails::Kind kind) {
1558   if (!name.symbol) {
1559     name.symbol = &context_->globalScope().MakeSymbol(
1560         name.source, Attrs{}, MiscDetails{kind});
1561   }
1562 }
1563 
1564 // AttrsVisitor implementation
1565 
1566 bool AttrsVisitor::BeginAttrs() {
1567   CHECK(!attrs_);
1568   attrs_ = std::make_optional<Attrs>();
1569   return true;
1570 }
1571 Attrs AttrsVisitor::GetAttrs() {
1572   CHECK(attrs_);
1573   return *attrs_;
1574 }
1575 Attrs AttrsVisitor::EndAttrs() {
1576   Attrs result{GetAttrs()};
1577   attrs_.reset();
1578   passName_ = std::nullopt;
1579   bindName_.reset();
1580   return result;
1581 }
1582 
1583 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1584   if (!passName_) {
1585     return false;
1586   }
1587   std::visit(common::visitors{
1588                  [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1589                  [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1590                  [](auto &) { common::die("unexpected pass name"); },
1591              },
1592       symbol.details());
1593   return true;
1594 }
1595 
1596 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1597   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1598     return;
1599   }
1600   std::optional<std::string> label{
1601       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1602   // 18.9.2(2): discard leading and trailing blanks, ignore if all blank
1603   if (label) {
1604     auto first{label->find_first_not_of(" ")};
1605     if (first == std::string::npos) {
1606       // Empty NAME= means no binding at all (18.10.2p2)
1607       Say(currStmtSource().value(), "Blank binding label ignored"_en_US);
1608       return;
1609     }
1610     auto last{label->find_last_not_of(" ")};
1611     label = label->substr(first, last - first + 1);
1612   } else {
1613     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1614   }
1615   symbol.SetBindName(std::move(*label));
1616 }
1617 
1618 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1619   CHECK(attrs_);
1620   if (CheckAndSet(Attr::BIND_C)) {
1621     if (x.v) {
1622       bindName_ = EvaluateExpr(*x.v);
1623     }
1624   }
1625 }
1626 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1627   CHECK(attrs_);
1628   CheckAndSet(IntentSpecToAttr(x));
1629   return false;
1630 }
1631 bool AttrsVisitor::Pre(const parser::Pass &x) {
1632   if (CheckAndSet(Attr::PASS)) {
1633     if (x.v) {
1634       passName_ = x.v->source;
1635       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1636     }
1637   }
1638   return false;
1639 }
1640 
1641 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1642 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1643   if (attrs_->test(attrName)) {
1644     Say(currStmtSource().value(),
1645         "Attribute '%s' cannot be used more than once"_en_US,
1646         AttrToString(attrName));
1647     return true;
1648   }
1649   return false;
1650 }
1651 
1652 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1653 // name attributes that cannot be used on the same declaration
1654 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1655   if ((attrName == attr1 && attrs_->test(attr2)) ||
1656       (attrName == attr2 && attrs_->test(attr1))) {
1657     Say(currStmtSource().value(),
1658         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1659         AttrToString(attr1), AttrToString(attr2));
1660     return true;
1661   }
1662   return false;
1663 }
1664 // C759, C1543
1665 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1666   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1667       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1668       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1669       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1670       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1671       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1672       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1673 }
1674 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1675   CHECK(attrs_);
1676   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1677     return false;
1678   }
1679   attrs_->set(attrName);
1680   return true;
1681 }
1682 
1683 // DeclTypeSpecVisitor implementation
1684 
1685 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1686   return state_.declTypeSpec;
1687 }
1688 
1689 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1690   CHECK(!state_.expectDeclTypeSpec);
1691   CHECK(!state_.declTypeSpec);
1692   state_.expectDeclTypeSpec = true;
1693 }
1694 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1695   CHECK(state_.expectDeclTypeSpec);
1696   state_ = {};
1697 }
1698 
1699 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1700     DeclTypeSpec::Category category) {
1701   CHECK(state_.expectDeclTypeSpec);
1702   state_.derived.category = category;
1703 }
1704 
1705 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1706   BeginDeclTypeSpec();
1707   return true;
1708 }
1709 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1710   EndDeclTypeSpec();
1711 }
1712 
1713 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1714   // Record the resolved DeclTypeSpec in the parse tree for use by
1715   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1716   // The grammar ensures that it's an intrinsic or derived type spec,
1717   // not TYPE(*) or CLASS(*) or CLASS(T).
1718   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1719     switch (spec->category()) {
1720     case DeclTypeSpec::Numeric:
1721     case DeclTypeSpec::Logical:
1722     case DeclTypeSpec::Character:
1723       typeSpec.declTypeSpec = spec;
1724       break;
1725     case DeclTypeSpec::TypeDerived:
1726       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1727         CheckForAbstractType(derived->typeSymbol()); // C703
1728         typeSpec.declTypeSpec = spec;
1729       }
1730       break;
1731     default:
1732       CRASH_NO_CASE;
1733     }
1734   }
1735 }
1736 
1737 void DeclTypeSpecVisitor::Post(
1738     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1739   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1740 }
1741 void DeclTypeSpecVisitor::Post(
1742     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1743   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1744 }
1745 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1746   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1747 }
1748 
1749 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1750   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1751     Say("ABSTRACT derived type may not be used here"_err_en_US);
1752   }
1753 }
1754 
1755 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1756   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1757 }
1758 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1759   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1760 }
1761 
1762 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1763 // and save it in state_.declTypeSpec.
1764 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1765   CHECK(state_.expectDeclTypeSpec);
1766   CHECK(!state_.declTypeSpec);
1767   state_.declTypeSpec = &declTypeSpec;
1768 }
1769 
1770 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1771     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1772   return AnalyzeKindSelector(context(), category, kind);
1773 }
1774 
1775 // MessageHandler implementation
1776 
1777 Message &MessageHandler::Say(MessageFixedText &&msg) {
1778   return context_->Say(currStmtSource().value(), std::move(msg));
1779 }
1780 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1781   return context_->Say(currStmtSource().value(), std::move(msg));
1782 }
1783 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1784   return Say(name, std::move(msg), name);
1785 }
1786 
1787 // ImplicitRulesVisitor implementation
1788 
1789 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1790   prevParameterStmt_ = currStmtSource();
1791 }
1792 
1793 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1794   bool result{
1795       std::visit(common::visitors{
1796                      [&](const std::list<ImplicitNoneNameSpec> &y) {
1797                        return HandleImplicitNone(y);
1798                      },
1799                      [&](const std::list<parser::ImplicitSpec> &) {
1800                        if (prevImplicitNoneType_) {
1801                          Say("IMPLICIT statement after IMPLICIT NONE or "
1802                              "IMPLICIT NONE(TYPE) statement"_err_en_US);
1803                          return false;
1804                        }
1805                        implicitRules_->set_isImplicitNoneType(false);
1806                        return true;
1807                      },
1808                  },
1809           x.u)};
1810   prevImplicit_ = currStmtSource();
1811   return result;
1812 }
1813 
1814 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1815   auto loLoc{std::get<parser::Location>(x.t)};
1816   auto hiLoc{loLoc};
1817   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1818     hiLoc = *hiLocOpt;
1819     if (*hiLoc < *loLoc) {
1820       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1821           std::string(hiLoc, 1), std::string(loLoc, 1));
1822       return false;
1823     }
1824   }
1825   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1826   return false;
1827 }
1828 
1829 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1830   BeginDeclTypeSpec();
1831   set_allowForwardReferenceToDerivedType(true);
1832   return true;
1833 }
1834 
1835 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1836   EndDeclTypeSpec();
1837 }
1838 
1839 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1840   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1841   prevImplicit_ = std::nullopt;
1842   prevImplicitNone_ = std::nullopt;
1843   prevImplicitNoneType_ = std::nullopt;
1844   prevParameterStmt_ = std::nullopt;
1845 }
1846 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1847   // find or create implicit rules for this scope
1848   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1849   SetScope(scope);
1850 }
1851 
1852 // TODO: for all of these errors, reference previous statement too
1853 bool ImplicitRulesVisitor::HandleImplicitNone(
1854     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1855   if (prevImplicitNone_) {
1856     Say("More than one IMPLICIT NONE statement"_err_en_US);
1857     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1858     return false;
1859   }
1860   if (prevParameterStmt_) {
1861     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1862     return false;
1863   }
1864   prevImplicitNone_ = currStmtSource();
1865   bool implicitNoneTypeNever{
1866       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1867   if (nameSpecs.empty()) {
1868     if (!implicitNoneTypeNever) {
1869       prevImplicitNoneType_ = currStmtSource();
1870       implicitRules_->set_isImplicitNoneType(true);
1871       if (prevImplicit_) {
1872         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1873         return false;
1874       }
1875     }
1876   } else {
1877     int sawType{0};
1878     int sawExternal{0};
1879     for (const auto noneSpec : nameSpecs) {
1880       switch (noneSpec) {
1881       case ImplicitNoneNameSpec::External:
1882         implicitRules_->set_isImplicitNoneExternal(true);
1883         ++sawExternal;
1884         break;
1885       case ImplicitNoneNameSpec::Type:
1886         if (!implicitNoneTypeNever) {
1887           prevImplicitNoneType_ = currStmtSource();
1888           implicitRules_->set_isImplicitNoneType(true);
1889           if (prevImplicit_) {
1890             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1891             return false;
1892           }
1893           ++sawType;
1894         }
1895         break;
1896       }
1897     }
1898     if (sawType > 1) {
1899       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1900       return false;
1901     }
1902     if (sawExternal > 1) {
1903       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1904       return false;
1905     }
1906   }
1907   return true;
1908 }
1909 
1910 // ArraySpecVisitor implementation
1911 
1912 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1913   CHECK(arraySpec_.empty());
1914   arraySpec_ = AnalyzeArraySpec(context(), x);
1915 }
1916 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1917   CHECK(arraySpec_.empty());
1918   arraySpec_ = AnalyzeArraySpec(context(), x);
1919 }
1920 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1921   CHECK(coarraySpec_.empty());
1922   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1923 }
1924 
1925 const ArraySpec &ArraySpecVisitor::arraySpec() {
1926   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
1927 }
1928 const ArraySpec &ArraySpecVisitor::coarraySpec() {
1929   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
1930 }
1931 void ArraySpecVisitor::BeginArraySpec() {
1932   CHECK(arraySpec_.empty());
1933   CHECK(coarraySpec_.empty());
1934   CHECK(attrArraySpec_.empty());
1935   CHECK(attrCoarraySpec_.empty());
1936 }
1937 void ArraySpecVisitor::EndArraySpec() {
1938   CHECK(arraySpec_.empty());
1939   CHECK(coarraySpec_.empty());
1940   attrArraySpec_.clear();
1941   attrCoarraySpec_.clear();
1942 }
1943 void ArraySpecVisitor::PostAttrSpec() {
1944   // Save dimension/codimension from attrs so we can process array/coarray-spec
1945   // on the entity-decl
1946   if (!arraySpec_.empty()) {
1947     if (attrArraySpec_.empty()) {
1948       attrArraySpec_ = arraySpec_;
1949       arraySpec_.clear();
1950     } else {
1951       Say(currStmtSource().value(),
1952           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
1953     }
1954   }
1955   if (!coarraySpec_.empty()) {
1956     if (attrCoarraySpec_.empty()) {
1957       attrCoarraySpec_ = coarraySpec_;
1958       coarraySpec_.clear();
1959     } else {
1960       Say(currStmtSource().value(),
1961           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
1962     }
1963   }
1964 }
1965 
1966 // ScopeHandler implementation
1967 
1968 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
1969   SayAlreadyDeclared(name.source, prev);
1970 }
1971 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
1972   if (context().HasError(prev)) {
1973     // don't report another error about prev
1974   } else {
1975     if (const auto *details{prev.detailsIf<UseDetails>()}) {
1976       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
1977           .Attach(details->location(),
1978               "It is use-associated with '%s' in module '%s'"_err_en_US,
1979               details->symbol().name(), GetUsedModule(*details).name());
1980     } else {
1981       SayAlreadyDeclared(name, prev.name());
1982     }
1983     context().SetError(prev);
1984   }
1985 }
1986 void ScopeHandler::SayAlreadyDeclared(
1987     const SourceName &name1, const SourceName &name2) {
1988   if (name1.begin() < name2.begin()) {
1989     SayAlreadyDeclared(name2, name1);
1990   } else {
1991     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
1992         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
1993   }
1994 }
1995 
1996 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
1997     MessageFixedText &&msg1, MessageFixedText &&msg2) {
1998   Say2(name, std::move(msg1), symbol, std::move(msg2));
1999   context().SetError(symbol, msg1.isFatal());
2000 }
2001 
2002 void ScopeHandler::SayWithDecl(
2003     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
2004   SayWithReason(name, symbol, std::move(msg),
2005       symbol.test(Symbol::Flag::Implicit) ? "Implicit declaration of '%s'"_en_US
2006                                           : "Declaration of '%s'"_en_US);
2007 }
2008 
2009 void ScopeHandler::SayLocalMustBeVariable(
2010     const parser::Name &name, Symbol &symbol) {
2011   SayWithDecl(name, symbol,
2012       "The name '%s' must be a variable to appear"
2013       " in a locality-spec"_err_en_US);
2014 }
2015 
2016 void ScopeHandler::SayDerivedType(
2017     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2018   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2019   Say(name, std::move(msg), name, typeSymbol.name())
2020       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2021           typeSymbol.name());
2022 }
2023 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2024     const SourceName &name2, MessageFixedText &&msg2) {
2025   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2026 }
2027 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2028     Symbol &symbol, MessageFixedText &&msg2) {
2029   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2030   context().SetError(symbol, msg1.isFatal());
2031 }
2032 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2033     Symbol &symbol, MessageFixedText &&msg2) {
2034   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2035   context().SetError(symbol, msg1.isFatal());
2036 }
2037 
2038 // This is essentially GetProgramUnitContaining(), but it can return
2039 // a mutable Scope &, it ignores statement functions, and it fails
2040 // gracefully for error recovery (returning the original Scope).
2041 template <typename T> static T &GetInclusiveScope(T &scope) {
2042   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2043     switch (s->kind()) {
2044     case Scope::Kind::Module:
2045     case Scope::Kind::MainProgram:
2046     case Scope::Kind::Subprogram:
2047     case Scope::Kind::BlockData:
2048       if (!s->IsStmtFunction()) {
2049         return *s;
2050       }
2051       break;
2052     default:;
2053     }
2054   }
2055   return scope;
2056 }
2057 
2058 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2059 
2060 Scope *ScopeHandler::GetHostProcedure() {
2061   Scope &parent{InclusiveScope().parent()};
2062   switch (parent.kind()) {
2063   case Scope::Kind::Subprogram:
2064     return &parent;
2065   case Scope::Kind::MainProgram:
2066     return &parent;
2067   default:
2068     return nullptr;
2069   }
2070 }
2071 
2072 Scope &ScopeHandler::NonDerivedTypeScope() {
2073   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2074 }
2075 
2076 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2077   PushScope(currScope().MakeScope(kind, symbol));
2078 }
2079 void ScopeHandler::PushScope(Scope &scope) {
2080   currScope_ = &scope;
2081   auto kind{currScope_->kind()};
2082   if (kind != Scope::Kind::Block) {
2083     BeginScope(scope);
2084   }
2085   // The name of a module or submodule cannot be "used" in its scope,
2086   // as we read 19.3.1(2), so we allow the name to be used as a local
2087   // identifier in the module or submodule too.  Same with programs
2088   // (14.1(3)) and BLOCK DATA.
2089   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2090       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2091     if (auto *symbol{scope.symbol()}) {
2092       // Create a dummy symbol so we can't create another one with the same
2093       // name. It might already be there if we previously pushed the scope.
2094       if (!FindInScope(scope, symbol->name())) {
2095         auto &newSymbol{MakeSymbol(symbol->name())};
2096         if (kind == Scope::Kind::Subprogram) {
2097           // Allow for recursive references.  If this symbol is a function
2098           // without an explicit RESULT(), this new symbol will be discarded
2099           // and replaced with an object of the same name.
2100           newSymbol.set_details(HostAssocDetails{*symbol});
2101         } else {
2102           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2103         }
2104       }
2105     }
2106   }
2107 }
2108 void ScopeHandler::PopScope() {
2109   // Entities that are not yet classified as objects or procedures are now
2110   // assumed to be objects.
2111   // TODO: Statement functions
2112   for (auto &pair : currScope()) {
2113     ConvertToObjectEntity(*pair.second);
2114   }
2115   SetScope(currScope_->parent());
2116 }
2117 void ScopeHandler::SetScope(Scope &scope) {
2118   currScope_ = &scope;
2119   ImplicitRulesVisitor::SetScope(InclusiveScope());
2120 }
2121 
2122 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2123   return FindSymbol(currScope(), name);
2124 }
2125 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2126   if (scope.IsDerivedType()) {
2127     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2128       if (!symbol->has<ProcBindingDetails>() &&
2129           !symbol->test(Symbol::Flag::ParentComp)) {
2130         return Resolve(name, symbol);
2131       }
2132     }
2133     return FindSymbol(scope.parent(), name);
2134   } else {
2135     // In EQUIVALENCE statements only resolve names in the local scope, see
2136     // 19.5.1.4, paragraph 2, item (10)
2137     return Resolve(name,
2138         inEquivalenceStmt_ ? FindInScope(scope, name)
2139                            : scope.FindSymbol(name.source));
2140   }
2141 }
2142 
2143 Symbol &ScopeHandler::MakeSymbol(
2144     Scope &scope, const SourceName &name, Attrs attrs) {
2145   if (Symbol * symbol{FindInScope(scope, name)}) {
2146     symbol->attrs() |= attrs;
2147     return *symbol;
2148   } else {
2149     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2150     CHECK(pair.second); // name was not found, so must be able to add
2151     return *pair.first->second;
2152   }
2153 }
2154 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2155   return MakeSymbol(currScope(), name, attrs);
2156 }
2157 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2158   return Resolve(name, MakeSymbol(name.source, attrs));
2159 }
2160 Symbol &ScopeHandler::MakeHostAssocSymbol(
2161     const parser::Name &name, const Symbol &hostSymbol) {
2162   Symbol &symbol{*NonDerivedTypeScope()
2163                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2164                       .first->second};
2165   name.symbol = &symbol;
2166   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2167   symbol.flags() = hostSymbol.flags();
2168   return symbol;
2169 }
2170 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2171   CHECK(!FindInScope(name));
2172   return MakeSymbol(currScope(), name, symbol.attrs());
2173 }
2174 
2175 // Look for name only in scope, not in enclosing scopes.
2176 Symbol *ScopeHandler::FindInScope(
2177     const Scope &scope, const parser::Name &name) {
2178   return Resolve(name, FindInScope(scope, name.source));
2179 }
2180 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2181   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2182   for (const std::string &n : GetAllNames(context(), name)) {
2183     auto it{scope.find(SourceName{n})};
2184     if (it != scope.end()) {
2185       return &*it->second;
2186     }
2187   }
2188   return nullptr;
2189 }
2190 
2191 // Find a component or type parameter by name in a derived type or its parents.
2192 Symbol *ScopeHandler::FindInTypeOrParents(
2193     const Scope &scope, const parser::Name &name) {
2194   return Resolve(name, scope.FindComponent(name.source));
2195 }
2196 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2197   return FindInTypeOrParents(currScope(), name);
2198 }
2199 
2200 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2201   currScope().erase(name.source);
2202   name.symbol = nullptr;
2203 }
2204 
2205 static bool NeedsType(const Symbol &symbol) {
2206   return !symbol.GetType() &&
2207       std::visit(common::visitors{
2208                      [](const EntityDetails &) { return true; },
2209                      [](const ObjectEntityDetails &) { return true; },
2210                      [](const AssocEntityDetails &) { return true; },
2211                      [&](const ProcEntityDetails &p) {
2212                        return symbol.test(Symbol::Flag::Function) &&
2213                            !symbol.attrs().test(Attr::INTRINSIC) &&
2214                            !p.interface().type() && !p.interface().symbol();
2215                      },
2216                      [](const auto &) { return false; },
2217                  },
2218           symbol.details());
2219 }
2220 
2221 void ScopeHandler::ApplyImplicitRules(
2222     Symbol &symbol, bool allowForwardReference) {
2223   if (context().HasError(symbol) || !NeedsType(symbol)) {
2224     return;
2225   }
2226   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2227     symbol.set(Symbol::Flag::Implicit);
2228     symbol.SetType(*type);
2229     return;
2230   }
2231   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2232     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2233     if (symbol.test(Symbol::Flag::Function)) {
2234       functionOrSubroutineFlag = Symbol::Flag::Function;
2235     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2236       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2237     }
2238     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2239       // type will be determined in expression semantics
2240       AcquireIntrinsicProcedureFlags(symbol);
2241       return;
2242     }
2243   }
2244   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2245     return;
2246   }
2247   if (!context().HasError(symbol)) {
2248     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2249     context().SetError(symbol);
2250   }
2251 }
2252 
2253 // Extension: Allow forward references to scalar integer dummy arguments
2254 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2255 // what would otherwise have been their implicit type is default INTEGER.
2256 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2257   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2258       symbol.Rank() != 0 ||
2259       !context().languageFeatures().IsEnabled(
2260           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2261     return false;
2262   }
2263   const DeclTypeSpec *type{
2264       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2265   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2266     return false;
2267   }
2268   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2269   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2270     return false;
2271   }
2272   if (!ConvertToObjectEntity(symbol)) {
2273     return false;
2274   }
2275   // TODO: check no INTENT(OUT)?
2276   if (context().languageFeatures().ShouldWarn(
2277           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2278     Say(symbol.name(),
2279         "Dummy argument '%s' was used without being explicitly typed"_en_US,
2280         symbol.name());
2281   }
2282   symbol.set(Symbol::Flag::Implicit);
2283   symbol.SetType(*type);
2284   return true;
2285 }
2286 
2287 // Ensure that the symbol for an intrinsic procedure is marked with
2288 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2289 // appropriate.
2290 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2291   symbol.attrs().set(Attr::INTRINSIC);
2292   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2293   case evaluate::IntrinsicClass::elementalFunction:
2294   case evaluate::IntrinsicClass::elementalSubroutine:
2295     symbol.attrs().set(Attr::ELEMENTAL);
2296     symbol.attrs().set(Attr::PURE);
2297     break;
2298   case evaluate::IntrinsicClass::impureSubroutine:
2299     break;
2300   default:
2301     symbol.attrs().set(Attr::PURE);
2302   }
2303 }
2304 
2305 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2306     Symbol &symbol, bool respectImplicitNoneType) {
2307   const Scope *scope{&symbol.owner()};
2308   if (scope->IsGlobal()) {
2309     scope = &currScope();
2310   }
2311   scope = &GetInclusiveScope(*scope);
2312   const auto *type{implicitRulesMap_->at(scope).GetType(
2313       symbol.name(), respectImplicitNoneType)};
2314   if (type) {
2315     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2316       // Resolve any forward-referenced derived type; a quick no-op else.
2317       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2318       instantiatable.Instantiate(currScope());
2319     }
2320   }
2321   return type;
2322 }
2323 
2324 // Convert symbol to be a ObjectEntity or return false if it can't be.
2325 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2326   if (symbol.has<ObjectEntityDetails>()) {
2327     // nothing to do
2328   } else if (symbol.has<UnknownDetails>()) {
2329     symbol.set_details(ObjectEntityDetails{});
2330   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2331     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2332   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2333     return useDetails->symbol().has<ObjectEntityDetails>();
2334   } else {
2335     return false;
2336   }
2337   return true;
2338 }
2339 // Convert symbol to be a ProcEntity or return false if it can't be.
2340 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2341   if (symbol.has<ProcEntityDetails>()) {
2342     // nothing to do
2343   } else if (symbol.has<UnknownDetails>()) {
2344     symbol.set_details(ProcEntityDetails{});
2345   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2346     symbol.set_details(ProcEntityDetails{std::move(*details)});
2347     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2348       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2349       symbol.set(Symbol::Flag::Function);
2350     }
2351   } else {
2352     return false;
2353   }
2354   return true;
2355 }
2356 
2357 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2358     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2359   KindExpr value{GetKindParamExpr(category, kind)};
2360   if (auto known{evaluate::ToInt64(value)}) {
2361     return context().MakeNumericType(category, static_cast<int>(*known));
2362   } else {
2363     return currScope_->MakeNumericType(category, std::move(value));
2364   }
2365 }
2366 
2367 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2368     const std::optional<parser::KindSelector> &kind) {
2369   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2370   if (auto known{evaluate::ToInt64(value)}) {
2371     return context().MakeLogicalType(static_cast<int>(*known));
2372   } else {
2373     return currScope_->MakeLogicalType(std::move(value));
2374   }
2375 }
2376 
2377 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2378   if (inSpecificationPart_ && name.symbol) {
2379     auto kind{currScope().kind()};
2380     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2381         kind == Scope::Kind::Block) {
2382       bool isHostAssociated{&name.symbol->owner() == &currScope()
2383               ? name.symbol->has<HostAssocDetails>()
2384               : name.symbol->owner().Contains(currScope())};
2385       if (isHostAssociated) {
2386         specPartState_.forwardRefs.insert(name.source);
2387       }
2388     }
2389   }
2390 }
2391 
2392 std::optional<SourceName> ScopeHandler::HadForwardRef(
2393     const Symbol &symbol) const {
2394   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2395   if (iter != specPartState_.forwardRefs.end()) {
2396     return *iter;
2397   }
2398   return std::nullopt;
2399 }
2400 
2401 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2402   if (!context().HasError(symbol)) {
2403     if (auto fwdRef{HadForwardRef(symbol)}) {
2404       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2405       if (outer && symbol.has<UseDetails>() &&
2406           &symbol.GetUltimate() == &outer->GetUltimate()) {
2407         // e.g. IMPORT of host's USE association
2408         return false;
2409       }
2410       Say(*fwdRef,
2411           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2412           *fwdRef)
2413           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2414       context().SetError(symbol);
2415       return true;
2416     }
2417     if (IsDummy(symbol) && isImplicitNoneType() &&
2418         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2419       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2420       // ApplyImplicitRules() due to use in a specification expression,
2421       // and no explicit type declaration appeared later.
2422       Say(symbol.name(),
2423           "No explicit type declared for dummy argument '%s'"_err_en_US);
2424       context().SetError(symbol);
2425       return true;
2426     }
2427   }
2428   return false;
2429 }
2430 
2431 void ScopeHandler::MakeExternal(Symbol &symbol) {
2432   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2433     symbol.attrs().set(Attr::EXTERNAL);
2434     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2435       Say(symbol.name(),
2436           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2437           symbol.name());
2438     }
2439   }
2440 }
2441 
2442 // ModuleVisitor implementation
2443 
2444 bool ModuleVisitor::Pre(const parser::Only &x) {
2445   std::visit(common::visitors{
2446                  [&](const Indirection<parser::GenericSpec> &generic) {
2447                    GenericSpecInfo genericSpecInfo{generic.value()};
2448                    AddUseOnly(genericSpecInfo.symbolName());
2449                    AddUse(genericSpecInfo);
2450                  },
2451                  [&](const parser::Name &name) {
2452                    AddUseOnly(name.source);
2453                    Resolve(name, AddUse(name.source, name.source).use);
2454                  },
2455                  [&](const parser::Rename &rename) { Walk(rename); },
2456              },
2457       x.u);
2458   return false;
2459 }
2460 
2461 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2462   const auto &localName{std::get<0>(x.t)};
2463   const auto &useName{std::get<1>(x.t)};
2464   AddUseRename(useName.source);
2465   SymbolRename rename{AddUse(localName.source, useName.source)};
2466   if (rename.use) {
2467     EraseRenamedSymbol(*rename.use);
2468   }
2469   Resolve(useName, rename.use);
2470   Resolve(localName, rename.local);
2471   return false;
2472 }
2473 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2474   const parser::DefinedOpName &local{std::get<0>(x.t)};
2475   const parser::DefinedOpName &use{std::get<1>(x.t)};
2476   GenericSpecInfo localInfo{local};
2477   GenericSpecInfo useInfo{use};
2478   if (IsIntrinsicOperator(context(), local.v.source)) {
2479     Say(local.v,
2480         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2481   } else if (IsLogicalConstant(context(), local.v.source)) {
2482     Say(local.v,
2483         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2484   } else {
2485     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2486     if (rename.use) {
2487       EraseRenamedSymbol(*rename.use);
2488     }
2489     useInfo.Resolve(rename.use);
2490     localInfo.Resolve(rename.local);
2491   }
2492   return false;
2493 }
2494 
2495 // Set useModuleScope_ to the Scope of the module being used.
2496 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2497   std::optional<bool> isIntrinsic;
2498   if (x.nature) {
2499     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2500     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2501   } else if (currScope().IsModule() && currScope().symbol() &&
2502       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2503     // Intrinsic modules USE only other intrinsic modules
2504     isIntrinsic = true;
2505   }
2506   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2507   if (!useModuleScope_) {
2508     return false;
2509   }
2510   // use the name from this source file
2511   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2512   return true;
2513 }
2514 
2515 void ModuleVisitor::Post(const parser::UseStmt &x) {
2516   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2517     // Not a use-only: collect the names that were used in renames,
2518     // then add a use for each public name that was not renamed.
2519     std::set<SourceName> useNames;
2520     for (const auto &rename : *list) {
2521       std::visit(common::visitors{
2522                      [&](const parser::Rename::Names &names) {
2523                        useNames.insert(std::get<1>(names.t).source);
2524                      },
2525                      [&](const parser::Rename::Operators &ops) {
2526                        useNames.insert(std::get<1>(ops.t).v.source);
2527                      },
2528                  },
2529           rename.u);
2530     }
2531     for (const auto &[name, symbol] : *useModuleScope_) {
2532       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2533           (!symbol->attrs().test(Attr::INTRINSIC) ||
2534               symbol->has<UseDetails>()) &&
2535           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2536         SourceName location{x.moduleName.source};
2537         if (auto *localSymbol{FindInScope(name)}) {
2538           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2539         } else {
2540           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2541         }
2542       }
2543     }
2544   }
2545   useModuleScope_ = nullptr;
2546 }
2547 
2548 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2549     const SourceName &localName, const SourceName &useName) {
2550   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2551 }
2552 
2553 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2554     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2555   if (!useModuleScope_) {
2556     return {}; // error occurred finding module
2557   }
2558   if (!useSymbol) {
2559     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2560         useModuleScope_->GetName().value());
2561     return {};
2562   }
2563   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2564       !FindModuleFileContaining(currScope())) {
2565     // Privacy is not enforced in module files so that generic interfaces
2566     // can be resolved to private specific procedures in specification
2567     // expressions.
2568     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2569         useModuleScope_->GetName().value());
2570     return {};
2571   }
2572   auto &localSymbol{MakeSymbol(localName)};
2573   DoAddUse(useName, localName, localSymbol, *useSymbol);
2574   return {&localSymbol, useSymbol};
2575 }
2576 
2577 // symbol must be either a Use or a Generic formed by merging two uses.
2578 // Convert it to a UseError with this additional location.
2579 static void ConvertToUseError(
2580     Symbol &symbol, const SourceName &location, const Scope &module) {
2581   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2582   if (!useDetails) {
2583     auto &genericDetails{symbol.get<GenericDetails>()};
2584     useDetails = &genericDetails.uses().at(0)->get<UseDetails>();
2585   }
2586   symbol.set_details(
2587       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2588 }
2589 
2590 // If a symbol has previously been USE-associated and did not appear in a USE
2591 // ONLY clause, erase it from the current scope.  This is needed when a name
2592 // appears in a USE rename clause.
2593 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2594   const SourceName &name{useSymbol.name()};
2595   if (const Symbol * symbol{FindInScope(name)}) {
2596     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2597       const Symbol &moduleSymbol{useDetails->symbol()};
2598       if (moduleSymbol.name() == name &&
2599           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2600           !IsUseOnly(name)) {
2601         EraseSymbol(*symbol);
2602       }
2603     }
2604   }
2605 }
2606 
2607 void ModuleVisitor::DoAddUse(const SourceName &location,
2608     const SourceName &localName, Symbol &localSymbol, const Symbol &useSymbol) {
2609   if (localName != useSymbol.name()) {
2610     EraseRenamedSymbol(useSymbol);
2611   }
2612   localSymbol.attrs() = useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2613   localSymbol.flags() = useSymbol.flags();
2614   const Symbol &useUltimate{useSymbol.GetUltimate()};
2615   if (auto *useDetails{localSymbol.detailsIf<UseDetails>()}) {
2616     const Symbol &localUltimate{localSymbol.GetUltimate()};
2617     if (localUltimate.owner() == useUltimate.owner()) {
2618       // use-associating the same symbol again -- ok
2619     } else if (localUltimate.has<GenericDetails>() &&
2620         useUltimate.has<GenericDetails>()) {
2621       // use-associating generics with the same names: merge them into a
2622       // new generic in this scope
2623       auto generic1{localUltimate.get<GenericDetails>()};
2624       AddGenericUse(generic1, localName, useUltimate);
2625       generic1.AddUse(localSymbol);
2626       // useSymbol has specific g and so does generic1
2627       auto &generic2{useUltimate.get<GenericDetails>()};
2628       if (generic1.derivedType() && generic2.derivedType() &&
2629           generic1.derivedType() != generic2.derivedType()) {
2630         Say(location,
2631             "Generic interface '%s' has ambiguous derived types"
2632             " from modules '%s' and '%s'"_err_en_US,
2633             localSymbol.name(), GetUsedModule(*useDetails).name(),
2634             useUltimate.owner().GetName().value());
2635         context().SetError(localSymbol);
2636       } else {
2637         generic1.CopyFrom(generic2);
2638       }
2639       EraseSymbol(localSymbol);
2640       MakeSymbol(localSymbol.name(), localSymbol.attrs(), std::move(generic1));
2641     } else {
2642       ConvertToUseError(localSymbol, location, *useModuleScope_);
2643     }
2644   } else if (auto *genericDetails{localSymbol.detailsIf<GenericDetails>()}) {
2645     if (const auto *useDetails{useUltimate.detailsIf<GenericDetails>()}) {
2646       AddGenericUse(*genericDetails, localName, useUltimate);
2647       if (genericDetails->derivedType() && useDetails->derivedType() &&
2648           genericDetails->derivedType() != useDetails->derivedType()) {
2649         Say(location,
2650             "Generic interface '%s' has ambiguous derived types"
2651             " from modules '%s' and '%s'"_err_en_US,
2652             localSymbol.name(),
2653             genericDetails->derivedType()->owner().GetName().value(),
2654             useDetails->derivedType()->owner().GetName().value());
2655       } else {
2656         genericDetails->CopyFrom(*useDetails);
2657       }
2658     } else {
2659       ConvertToUseError(localSymbol, location, *useModuleScope_);
2660     }
2661   } else if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2662     details->add_occurrence(location, *useModuleScope_);
2663   } else if (!localSymbol.has<UnknownDetails>()) {
2664     Say(location,
2665         "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2666         localName)
2667         .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2668             localName);
2669   } else {
2670     localSymbol.set_details(UseDetails{localName, useSymbol});
2671   }
2672 }
2673 
2674 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2675   if (useModuleScope_) {
2676     const auto &name{info.symbolName()};
2677     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2678     info.Resolve(rename.use);
2679   }
2680 }
2681 
2682 // Create a UseDetails symbol for this USE and add it to generic
2683 void ModuleVisitor::AddGenericUse(
2684     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2685   generic.AddUse(currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol}));
2686 }
2687 
2688 // Enforce C1406
2689 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2690     SourceName name, bool isIntrinsic) {
2691   if (isIntrinsic) {
2692     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2693         iter != explicitNonIntrinsicUses_.end()) {
2694       Say(name,
2695           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2696           name)
2697           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2698     }
2699     explicitIntrinsicUses_.insert(name);
2700   } else {
2701     if (auto iter{explicitIntrinsicUses_.find(name)};
2702         iter != explicitIntrinsicUses_.end()) {
2703       Say(name,
2704           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2705           name)
2706           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2707     }
2708     explicitNonIntrinsicUses_.insert(name);
2709   }
2710 }
2711 
2712 bool ModuleVisitor::BeginSubmodule(
2713     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2714   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2715   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2716   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2717   if (!ancestor) {
2718     return false;
2719   }
2720   Scope *parentScope{parentName
2721           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2722           : ancestor};
2723   if (!parentScope) {
2724     return false;
2725   }
2726   PushScope(*parentScope); // submodule is hosted in parent
2727   BeginModule(name, true);
2728   if (!ancestor->AddSubmodule(name.source, currScope())) {
2729     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2730         ancestorName.source, name.source);
2731   }
2732   return true;
2733 }
2734 
2735 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2736   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2737   auto &details{symbol.get<ModuleDetails>()};
2738   PushScope(Scope::Kind::Module, &symbol);
2739   details.set_scope(&currScope());
2740   defaultAccess_ = Attr::PUBLIC;
2741   prevAccessStmt_ = std::nullopt;
2742 }
2743 
2744 // Find a module or submodule by name and return its scope.
2745 // If ancestor is present, look for a submodule of that ancestor module.
2746 // May have to read a .mod file to find it.
2747 // If an error occurs, report it and return nullptr.
2748 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2749     std::optional<bool> isIntrinsic, Scope *ancestor) {
2750   ModFileReader reader{context()};
2751   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2752   if (!scope) {
2753     return nullptr;
2754   }
2755   if (scope->kind() != Scope::Kind::Module) {
2756     Say(name, "'%s' is not a module"_err_en_US);
2757     return nullptr;
2758   }
2759   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2760     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2761   }
2762   Resolve(name, scope->symbol());
2763   return scope;
2764 }
2765 
2766 void ModuleVisitor::ApplyDefaultAccess() {
2767   for (auto &pair : currScope()) {
2768     Symbol &symbol = *pair.second;
2769     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2770       symbol.attrs().set(defaultAccess_);
2771     }
2772   }
2773 }
2774 
2775 // InterfaceVistor implementation
2776 
2777 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2778   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2779   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2780   return BeginAttrs();
2781 }
2782 
2783 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2784 
2785 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2786   genericInfo_.pop();
2787 }
2788 
2789 // Create a symbol in genericSymbol_ for this GenericSpec.
2790 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2791   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
2792     SetGenericSymbol(*symbol);
2793   }
2794   return false;
2795 }
2796 
2797 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2798   if (!isGeneric()) {
2799     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2800     return false;
2801   }
2802   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2803   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2804   AddSpecificProcs(names, kind);
2805   return false;
2806 }
2807 
2808 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2809   genericInfo_.emplace(/*isInterface*/ false);
2810   return true;
2811 }
2812 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2813   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2814     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2815   }
2816   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2817   AddSpecificProcs(names, ProcedureKind::Procedure);
2818   genericInfo_.pop();
2819 }
2820 
2821 bool InterfaceVisitor::inInterfaceBlock() const {
2822   return !genericInfo_.empty() && GetGenericInfo().isInterface;
2823 }
2824 bool InterfaceVisitor::isGeneric() const {
2825   return !genericInfo_.empty() && GetGenericInfo().symbol;
2826 }
2827 bool InterfaceVisitor::isAbstract() const {
2828   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
2829 }
2830 
2831 void InterfaceVisitor::AddSpecificProcs(
2832     const std::list<parser::Name> &names, ProcedureKind kind) {
2833   for (const auto &name : names) {
2834     specificProcs_.emplace(
2835         GetGenericInfo().symbol, std::make_pair(&name, kind));
2836   }
2837 }
2838 
2839 // By now we should have seen all specific procedures referenced by name in
2840 // this generic interface. Resolve those names to symbols.
2841 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
2842   auto &details{generic.get<GenericDetails>()};
2843   UnorderedSymbolSet symbolsSeen;
2844   for (const Symbol &symbol : details.specificProcs()) {
2845     symbolsSeen.insert(symbol.GetUltimate());
2846   }
2847   auto range{specificProcs_.equal_range(&generic)};
2848   for (auto it{range.first}; it != range.second; ++it) {
2849     const parser::Name *name{it->second.first};
2850     auto kind{it->second.second};
2851     const auto *symbol{FindSymbol(*name)};
2852     if (!symbol) {
2853       Say(*name, "Procedure '%s' not found"_err_en_US);
2854       continue;
2855     }
2856     const Symbol &specific{BypassGeneric(*symbol)};
2857     const Symbol &ultimate{specific.GetUltimate()};
2858     if (!ultimate.has<SubprogramDetails>() &&
2859         !ultimate.has<SubprogramNameDetails>()) {
2860       Say(*name, "'%s' is not a subprogram"_err_en_US);
2861       continue;
2862     }
2863     if (kind == ProcedureKind::ModuleProcedure) {
2864       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
2865         if (nd->kind() != SubprogramKind::Module) {
2866           Say(*name, "'%s' is not a module procedure"_err_en_US);
2867         }
2868       } else {
2869         // USE-associated procedure
2870         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
2871         CHECK(sd);
2872         if (ultimate.owner().kind() != Scope::Kind::Module ||
2873             sd->isInterface()) {
2874           Say(*name, "'%s' is not a module procedure"_err_en_US);
2875         }
2876       }
2877     }
2878     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
2879       // When a specific procedure is a USE association, that association
2880       // is saved in the generic's specifics, not its ultimate symbol,
2881       // so that module file output of interfaces can distinguish them.
2882       details.AddSpecificProc(specific, name->source);
2883     } else if (&specific == &ultimate) {
2884       Say(name->source,
2885           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
2886           name->source, MakeOpName(generic.name()));
2887     } else {
2888       Say(name->source,
2889           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
2890           ultimate.name(), ultimate.owner().GetName().value(),
2891           MakeOpName(generic.name()));
2892     }
2893   }
2894   specificProcs_.erase(range.first, range.second);
2895 }
2896 
2897 // Check that the specific procedures are all functions or all subroutines.
2898 // If there is a derived type with the same name they must be functions.
2899 // Set the corresponding flag on generic.
2900 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
2901   ResolveSpecificsInGeneric(generic);
2902   auto &details{generic.get<GenericDetails>()};
2903   if (auto *proc{details.CheckSpecific()}) {
2904     auto msg{
2905         "'%s' may not be the name of both a generic interface and a"
2906         " procedure unless it is a specific procedure of the generic"_err_en_US};
2907     if (proc->name().begin() > generic.name().begin()) {
2908       Say(proc->name(), std::move(msg));
2909     } else {
2910       Say(generic.name(), std::move(msg));
2911     }
2912   }
2913   auto &specifics{details.specificProcs()};
2914   if (specifics.empty()) {
2915     if (details.derivedType()) {
2916       generic.set(Symbol::Flag::Function);
2917     }
2918     return;
2919   }
2920   const Symbol &firstSpecific{specifics.front()};
2921   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
2922   for (const Symbol &specific : specifics) {
2923     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
2924       auto &msg{Say(generic.name(),
2925           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
2926       if (isFunction) {
2927         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
2928         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
2929       } else {
2930         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
2931         msg.Attach(specific.name(), "Function declaration"_en_US);
2932       }
2933     }
2934   }
2935   if (!isFunction && details.derivedType()) {
2936     SayDerivedType(generic.name(),
2937         "Generic interface '%s' may only contain functions due to derived type"
2938         " with same name"_err_en_US,
2939         *details.derivedType()->scope());
2940   }
2941   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
2942 }
2943 
2944 // SubprogramVisitor implementation
2945 
2946 // Return false if it is actually an assignment statement.
2947 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
2948   const auto &name{std::get<parser::Name>(x.t)};
2949   const DeclTypeSpec *resultType{nullptr};
2950   // Look up name: provides return type or tells us if it's an array
2951   if (auto *symbol{FindSymbol(name)}) {
2952     auto *details{symbol->detailsIf<EntityDetails>()};
2953     if (!details) {
2954       badStmtFuncFound_ = true;
2955       return false;
2956     }
2957     // TODO: check that attrs are compatible with stmt func
2958     resultType = details->type();
2959     symbol->details() = UnknownDetails{}; // will be replaced below
2960   }
2961   if (badStmtFuncFound_) {
2962     Say(name, "'%s' has not been declared as an array"_err_en_US);
2963     return true;
2964   }
2965   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
2966   symbol.set(Symbol::Flag::StmtFunction);
2967   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
2968   auto &details{symbol.get<SubprogramDetails>()};
2969   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
2970     ObjectEntityDetails dummyDetails{true};
2971     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
2972       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
2973         if (d->type()) {
2974           dummyDetails.set_type(*d->type());
2975         }
2976       }
2977     }
2978     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
2979     ApplyImplicitRules(dummy);
2980     details.add_dummyArg(dummy);
2981   }
2982   ObjectEntityDetails resultDetails;
2983   if (resultType) {
2984     resultDetails.set_type(*resultType);
2985   }
2986   resultDetails.set_funcResult(true);
2987   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
2988   ApplyImplicitRules(result);
2989   details.set_result(result);
2990   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
2991   Walk(parsedExpr);
2992   // The analysis of the expression that constitutes the body of the
2993   // statement function is deferred to FinishSpecificationPart() so that
2994   // all declarations and implicit typing are complete.
2995   PopScope();
2996   return true;
2997 }
2998 
2999 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3000   if (suffix.resultName) {
3001     funcInfo_.resultName = &suffix.resultName.value();
3002   }
3003   return true;
3004 }
3005 
3006 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3007   // Save this to process after UseStmt and ImplicitPart
3008   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3009     if (funcInfo_.parsedType) { // C1543
3010       Say(currStmtSource().value(),
3011           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3012       return false;
3013     } else {
3014       funcInfo_.parsedType = parsedType;
3015       funcInfo_.source = currStmtSource();
3016       return false;
3017     }
3018   } else {
3019     return true;
3020   }
3021 }
3022 
3023 void SubprogramVisitor::Post(const parser::ImplicitPart &) {
3024   // If the function has a type in the prefix, process it now
3025   if (funcInfo_.parsedType) {
3026     messageHandler().set_currStmtSource(funcInfo_.source);
3027     if (const auto *type{ProcessTypeSpec(*funcInfo_.parsedType, true)}) {
3028       if (!context().HasError(funcInfo_.resultSymbol)) {
3029         funcInfo_.resultSymbol->SetType(*type);
3030       }
3031     }
3032   }
3033   funcInfo_ = {};
3034 }
3035 
3036 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3037   const auto &name{std::get<parser::Name>(
3038       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3039   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3040 }
3041 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
3042   EndSubprogram();
3043 }
3044 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3045   const auto &name{std::get<parser::Name>(
3046       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3047   return BeginSubprogram(name, Symbol::Flag::Function);
3048 }
3049 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
3050   EndSubprogram();
3051 }
3052 
3053 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
3054   return BeginAttrs();
3055 }
3056 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3057   return BeginAttrs();
3058 }
3059 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3060 
3061 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
3062   const auto &name{std::get<parser::Name>(stmt.t)};
3063   auto &details{PostSubprogramStmt(name)};
3064   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3065     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3066       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3067       details.add_dummyArg(dummy);
3068     } else {
3069       details.add_alternateReturn();
3070     }
3071   }
3072 }
3073 
3074 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3075   const auto &name{std::get<parser::Name>(stmt.t)};
3076   auto &details{PostSubprogramStmt(name)};
3077   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3078     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3079     details.add_dummyArg(dummy);
3080   }
3081   const parser::Name *funcResultName;
3082   if (funcInfo_.resultName && funcInfo_.resultName->source != name.source) {
3083     // Note that RESULT is ignored if it has the same name as the function.
3084     funcResultName = funcInfo_.resultName;
3085   } else {
3086     EraseSymbol(name); // was added by PushSubprogramScope
3087     funcResultName = &name;
3088   }
3089   // add function result to function scope
3090   if (details.isFunction()) {
3091     CHECK(context().HasError(currScope().symbol()));
3092   } else {
3093     // add function result to function scope
3094     EntityDetails funcResultDetails;
3095     funcResultDetails.set_funcResult(true);
3096     funcInfo_.resultSymbol =
3097         &MakeSymbol(*funcResultName, std::move(funcResultDetails));
3098     details.set_result(*funcInfo_.resultSymbol);
3099   }
3100 
3101   // C1560.
3102   if (funcInfo_.resultName && funcInfo_.resultName->source == name.source) {
3103     Say(funcInfo_.resultName->source,
3104         "The function name should not appear in RESULT, references to '%s' "
3105         "inside"
3106         " the function will be considered as references to the result only"_en_US,
3107         name.source);
3108     // RESULT name was ignored above, the only side effect from doing so will be
3109     // the inability to make recursive calls. The related parser::Name is still
3110     // resolved to the created function result symbol because every parser::Name
3111     // should be resolved to avoid internal errors.
3112     Resolve(*funcInfo_.resultName, funcInfo_.resultSymbol);
3113   }
3114   name.symbol = currScope().symbol(); // must not be function result symbol
3115   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3116   // has a RESULT() suffix.
3117   funcInfo_.resultName = nullptr;
3118 }
3119 
3120 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3121     const parser::Name &name) {
3122   Symbol &symbol{*currScope().symbol()};
3123   CHECK(name.source == symbol.name());
3124   SetBindNameOn(symbol);
3125   symbol.attrs() |= EndAttrs();
3126   if (symbol.attrs().test(Attr::MODULE)) {
3127     symbol.attrs().set(Attr::EXTERNAL, false);
3128   }
3129   return symbol.get<SubprogramDetails>();
3130 }
3131 
3132 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3133   auto attrs{EndAttrs()}; // needs to be called even if early return
3134   Scope &inclusiveScope{InclusiveScope()};
3135   const Symbol *subprogram{inclusiveScope.symbol()};
3136   if (!subprogram) {
3137     CHECK(context().AnyFatalError());
3138     return;
3139   }
3140   const auto &name{std::get<parser::Name>(stmt.t)};
3141   const auto *parentDetails{subprogram->detailsIf<SubprogramDetails>()};
3142   bool inFunction{parentDetails && parentDetails->isFunction()};
3143   const parser::Name *resultName{funcInfo_.resultName};
3144   if (resultName) { // RESULT(result) is present
3145     funcInfo_.resultName = nullptr;
3146     if (!inFunction) {
3147       Say2(resultName->source,
3148           "RESULT(%s) may appear only in a function"_err_en_US,
3149           subprogram->name(), "Containing subprogram"_en_US);
3150     } else if (resultName->source == subprogram->name()) { // C1574
3151       Say2(resultName->source,
3152           "RESULT(%s) may not have the same name as the function"_err_en_US,
3153           subprogram->name(), "Containing function"_en_US);
3154     } else if (const Symbol *
3155         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
3156       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
3157         if (details->entryScope() == &inclusiveScope) {
3158           Say2(resultName->source,
3159               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3160               symbol->name(), "Conflicting ENTRY"_en_US);
3161         }
3162       }
3163     }
3164     if (Symbol * symbol{FindSymbol(name)}) { // C1570
3165       // When RESULT() appears, ENTRY name can't have been already declared
3166       if (inclusiveScope.Contains(symbol->owner())) {
3167         Say2(name,
3168             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
3169             *symbol, "Previous declaration of '%s'"_en_US);
3170       }
3171     }
3172     if (resultName->source == name.source) {
3173       // ignore RESULT() hereafter when it's the same name as the ENTRY
3174       resultName = nullptr;
3175     }
3176   }
3177   SubprogramDetails entryDetails;
3178   entryDetails.set_entryScope(inclusiveScope);
3179   if (inFunction) {
3180     // Create the entity to hold the function result, if necessary.
3181     Symbol *resultSymbol{nullptr};
3182     auto &effectiveResultName{*(resultName ? resultName : &name)};
3183     resultSymbol = FindInScope(currScope(), effectiveResultName);
3184     if (resultSymbol) { // C1574
3185       std::visit(
3186           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
3187               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
3188               [](ProcEntityDetails &x) { x.set_funcResult(true); },
3189               [&](const auto &) {
3190                 Say2(effectiveResultName.source,
3191                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
3192                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
3193                 context().SetError(*resultSymbol);
3194               }},
3195           resultSymbol->details());
3196     } else if (inExecutionPart_) {
3197       ObjectEntityDetails entity;
3198       entity.set_funcResult(true);
3199       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3200       ApplyImplicitRules(*resultSymbol);
3201     } else {
3202       EntityDetails entity;
3203       entity.set_funcResult(true);
3204       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3205     }
3206     if (!resultName) {
3207       name.symbol = nullptr; // symbol will be used for entry point below
3208     }
3209     entryDetails.set_result(*resultSymbol);
3210   }
3211 
3212   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3213     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3214       Symbol *dummy{FindSymbol(*dummyName)};
3215       if (dummy) {
3216         std::visit(
3217             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3218                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3219                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3220                 [](SubprogramDetails &x) { x.set_isDummy(); },
3221                 [&](const auto &) {
3222                   Say2(dummyName->source,
3223                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3224                       dummy->name(), "Previous declaration of '%s'"_en_US);
3225                 }},
3226             dummy->details());
3227       } else {
3228         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3229         if (inExecutionPart_) {
3230           ApplyImplicitRules(*dummy);
3231         }
3232       }
3233       entryDetails.add_dummyArg(*dummy);
3234     } else {
3235       if (inFunction) { // C1573
3236         Say(name,
3237             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3238         break;
3239       }
3240       entryDetails.add_alternateReturn();
3241     }
3242   }
3243 
3244   Symbol::Flag subpFlag{
3245       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
3246   Scope &outer{inclusiveScope.parent()}; // global or module scope
3247   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3248     attrs.set(Attr::PUBLIC);
3249   }
3250   if (Symbol * extant{FindSymbol(outer, name)}) {
3251     if (!HandlePreviousCalls(name, *extant, subpFlag)) {
3252       if (outer.IsGlobal()) {
3253         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
3254             *extant, "Previous definition of '%s'"_en_US);
3255       } else {
3256         SayAlreadyDeclared(name, *extant);
3257       }
3258       return;
3259     }
3260   }
3261   Symbol &entrySymbol{MakeSymbol(outer, name.source, attrs)};
3262   entrySymbol.set_details(std::move(entryDetails));
3263   SetBindNameOn(entrySymbol);
3264   entrySymbol.set(subpFlag);
3265   Resolve(name, entrySymbol);
3266 }
3267 
3268 // A subprogram declared with MODULE PROCEDURE
3269 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3270   auto *symbol{FindSymbol(name)};
3271   if (symbol && symbol->has<SubprogramNameDetails>()) {
3272     symbol = FindSymbol(currScope().parent(), name);
3273   }
3274   if (!IsSeparateModuleProcedureInterface(symbol)) {
3275     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3276     return false;
3277   }
3278   if (symbol->owner() == currScope()) {
3279     PushScope(Scope::Kind::Subprogram, symbol);
3280   } else {
3281     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3282     PushScope(Scope::Kind::Subprogram, &newSymbol);
3283     const auto &details{symbol->get<SubprogramDetails>()};
3284     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3285     for (const Symbol *dummyArg : details.dummyArgs()) {
3286       if (!dummyArg) {
3287         newDetails.add_alternateReturn();
3288       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3289         newDetails.add_dummyArg(*copy);
3290       }
3291     }
3292     if (details.isFunction()) {
3293       currScope().erase(symbol->name());
3294       newDetails.set_result(*currScope().CopySymbol(details.result()));
3295     }
3296   }
3297   return true;
3298 }
3299 
3300 // A subprogram declared with SUBROUTINE or FUNCTION
3301 bool SubprogramVisitor::BeginSubprogram(
3302     const parser::Name &name, Symbol::Flag subpFlag, bool hasModulePrefix) {
3303   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3304     Say(name,
3305         "'%s' is a MODULE procedure which must be declared within a "
3306         "MODULE or SUBMODULE"_err_en_US);
3307     return false;
3308   }
3309 
3310   if (hasModulePrefix && !inInterfaceBlock() &&
3311       !IsSeparateModuleProcedureInterface(
3312           FindSymbol(currScope().parent(), name))) {
3313     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3314     return false;
3315   }
3316   PushSubprogramScope(name, subpFlag);
3317   return true;
3318 }
3319 
3320 void SubprogramVisitor::EndSubprogram() { PopScope(); }
3321 
3322 bool SubprogramVisitor::HandlePreviousCalls(
3323     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3324   if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3325       !proc->isDummy() &&
3326       !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3327     // There's a symbol created for previous calls to this subprogram or
3328     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3329     // obligation to rewrite symbol pointers in the parse tree.
3330     if (!symbol.test(subpFlag)) {
3331       Say2(name,
3332           subpFlag == Symbol::Flag::Function
3333               ? "'%s' was previously called as a subroutine"_err_en_US
3334               : "'%s' was previously called as a function"_err_en_US,
3335           symbol, "Previous call of '%s'"_en_US);
3336     }
3337     EntityDetails entity;
3338     if (proc->type()) {
3339       entity.set_type(*proc->type());
3340     }
3341     symbol.details() = std::move(entity);
3342     return true;
3343   } else {
3344     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3345   }
3346 }
3347 
3348 void SubprogramVisitor::CheckExtantProc(
3349     const parser::Name &name, Symbol::Flag subpFlag) {
3350   if (auto *prev{FindSymbol(name)}) {
3351     if (IsDummy(*prev)) {
3352     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3353       // Procedures in an INTERFACE block do not resolve to symbols
3354       // in scopes between the global scope and the current scope.
3355     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3356       SayAlreadyDeclared(name, *prev);
3357     }
3358   }
3359 }
3360 
3361 Symbol &SubprogramVisitor::PushSubprogramScope(
3362     const parser::Name &name, Symbol::Flag subpFlag) {
3363   auto *symbol{GetSpecificFromGeneric(name)};
3364   if (!symbol) {
3365     CheckExtantProc(name, subpFlag);
3366     symbol = &MakeSymbol(name, SubprogramDetails{});
3367   }
3368   symbol->set(subpFlag);
3369   symbol->ReplaceName(name.source);
3370   PushScope(Scope::Kind::Subprogram, symbol);
3371   auto &details{symbol->get<SubprogramDetails>()};
3372   if (inInterfaceBlock()) {
3373     details.set_isInterface();
3374     if (isAbstract()) {
3375       symbol->attrs().set(Attr::ABSTRACT);
3376     } else {
3377       MakeExternal(*symbol);
3378     }
3379     if (isGeneric()) {
3380       Symbol &genericSymbol{GetGenericSymbol()};
3381       if (genericSymbol.has<GenericDetails>()) {
3382         genericSymbol.get<GenericDetails>().AddSpecificProc(
3383             *symbol, name.source);
3384       } else {
3385         CHECK(context().HasError(genericSymbol));
3386       }
3387     }
3388     set_inheritFromParent(false);
3389   }
3390   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3391   return *symbol;
3392 }
3393 
3394 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3395   if (auto *prev{FindSymbol(name)}) {
3396     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3397       if (prev->test(Symbol::Flag::Subroutine) ||
3398           prev->test(Symbol::Flag::Function)) {
3399         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3400             "Previous call of '%s'"_en_US);
3401       }
3402       EraseSymbol(name);
3403     }
3404   }
3405   if (name.source.empty()) {
3406     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3407     PushScope(Scope::Kind::BlockData, nullptr);
3408   } else {
3409     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3410   }
3411 }
3412 
3413 // If name is a generic, return specific subprogram with the same name.
3414 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3415   if (auto *symbol{FindSymbol(name)}) {
3416     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3417       // found generic, want subprogram
3418       auto *specific{details->specific()};
3419       if (!specific) {
3420         specific =
3421             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3422         if (details->derivedType()) {
3423           // A specific procedure with the same name as a derived type
3424           SayAlreadyDeclared(name, *details->derivedType());
3425         } else {
3426           details->set_specific(Resolve(name, *specific));
3427         }
3428       } else if (isGeneric()) {
3429         SayAlreadyDeclared(name, *specific);
3430       }
3431       if (!specific->has<SubprogramDetails>()) {
3432         specific->set_details(SubprogramDetails{});
3433       }
3434       return specific;
3435     }
3436   }
3437   return nullptr;
3438 }
3439 
3440 // DeclarationVisitor implementation
3441 
3442 bool DeclarationVisitor::BeginDecl() {
3443   BeginDeclTypeSpec();
3444   BeginArraySpec();
3445   return BeginAttrs();
3446 }
3447 void DeclarationVisitor::EndDecl() {
3448   EndDeclTypeSpec();
3449   EndArraySpec();
3450   EndAttrs();
3451 }
3452 
3453 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3454   const auto *details{
3455       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3456   if (!details) {
3457     return false;
3458   }
3459   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3460   for (const auto &[location, module] : details->occurrences()) {
3461     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3462         name.source, module->GetName().value());
3463   }
3464   context().SetError(*name.symbol);
3465   return true;
3466 }
3467 
3468 // Report error if accessibility of symbol doesn't match isPrivate.
3469 void DeclarationVisitor::CheckAccessibility(
3470     const SourceName &name, bool isPrivate, Symbol &symbol) {
3471   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3472     Say2(name,
3473         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3474         symbol, "Previous declaration of '%s'"_en_US);
3475   }
3476 }
3477 
3478 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3479   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3480     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3481       if (typeSpec->category() == DeclTypeSpec::Character) {
3482         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3483           Say("The type parameter LEN cannot be deferred without"
3484               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3485         }
3486       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3487         for (const auto &pair : derivedSpec->parameters()) {
3488           if (pair.second.isDeferred()) {
3489             Say(currStmtSource().value(),
3490                 "The value of type parameter '%s' cannot be deferred"
3491                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3492                 pair.first);
3493           }
3494         }
3495       }
3496     }
3497   }
3498   EndDecl();
3499 }
3500 
3501 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3502   DeclareObjectEntity(std::get<parser::Name>(x.t));
3503 }
3504 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3505   DeclareObjectEntity(std::get<parser::Name>(x.t));
3506 }
3507 
3508 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3509   // Defer inspection of initializers to Initialization() so that the
3510   // symbol being initialized will be available within the initialization
3511   // expression.
3512   return false;
3513 }
3514 
3515 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3516   const auto &name{std::get<parser::ObjectName>(x.t)};
3517   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3518   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3519   symbol.ReplaceName(name.source);
3520   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3521     if (ConvertToObjectEntity(symbol)) {
3522       Initialization(name, *init, false);
3523     }
3524   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3525     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3526   }
3527 }
3528 
3529 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3530   const auto &name{std::get<parser::Name>(x.t)};
3531   if (const auto &deferredShapeSpecs{
3532           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3533     CHECK(arraySpec().empty());
3534     BeginArraySpec();
3535     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3536     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3537     symbol.ReplaceName(name.source);
3538     EndArraySpec();
3539   } else {
3540     Symbol &symbol{DeclareUnknownEntity(name, Attrs{Attr::POINTER})};
3541     symbol.ReplaceName(name.source);
3542   }
3543 }
3544 
3545 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3546   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3547   auto &name{std::get<parser::Name>(x.t)};
3548   Symbol *symbol;
3549   if (kind == parser::BindEntity::Kind::Object) {
3550     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3551   } else {
3552     symbol = &MakeCommonBlockSymbol(name);
3553     symbol->attrs().set(Attr::BIND_C);
3554   }
3555   SetBindNameOn(*symbol);
3556   return false;
3557 }
3558 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3559   inOldStyleParameterStmt_ = true;
3560   Walk(x.v);
3561   inOldStyleParameterStmt_ = false;
3562   return false;
3563 }
3564 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3565   auto &name{std::get<parser::NamedConstant>(x.t).v};
3566   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3567   if (!ConvertToObjectEntity(symbol) ||
3568       symbol.test(Symbol::Flag::CrayPointer) ||
3569       symbol.test(Symbol::Flag::CrayPointee)) {
3570     SayWithDecl(
3571         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3572     return false;
3573   }
3574   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3575   auto &details{symbol.get<ObjectEntityDetails>()};
3576   if (inOldStyleParameterStmt_) {
3577     // non-standard extension PARAMETER statement (no parentheses)
3578     Walk(expr);
3579     auto folded{EvaluateExpr(expr)};
3580     if (details.type()) {
3581       SayWithDecl(name, symbol,
3582           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3583     } else if (folded) {
3584       auto at{expr.thing.value().source};
3585       if (evaluate::IsActuallyConstant(*folded)) {
3586         if (const auto *type{currScope().GetType(*folded)}) {
3587           if (type->IsPolymorphic()) {
3588             Say(at, "The expression must not be polymorphic"_err_en_US);
3589           } else if (auto shape{ToArraySpec(
3590                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3591             // The type of the named constant is assumed from the expression.
3592             details.set_type(*type);
3593             details.set_init(std::move(*folded));
3594             details.set_shape(std::move(*shape));
3595           } else {
3596             Say(at, "The expression must have constant shape"_err_en_US);
3597           }
3598         } else {
3599           Say(at, "The expression must have a known type"_err_en_US);
3600         }
3601       } else {
3602         Say(at, "The expression must be a constant of known type"_err_en_US);
3603       }
3604     }
3605   } else {
3606     // standard-conforming PARAMETER statement (with parentheses)
3607     ApplyImplicitRules(symbol);
3608     Walk(expr);
3609     if (auto converted{EvaluateNonPointerInitializer(
3610             symbol, expr, expr.thing.value().source)}) {
3611       details.set_init(std::move(*converted));
3612     }
3613   }
3614   return false;
3615 }
3616 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3617   const parser::Name &name{x.v};
3618   if (!FindSymbol(name)) {
3619     Say(name, "Named constant '%s' not found"_err_en_US);
3620   } else {
3621     CheckUseError(name);
3622   }
3623   return false;
3624 }
3625 
3626 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3627   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3628   Symbol *symbol{FindSymbol(name)};
3629   if (symbol && !symbol->has<UnknownDetails>()) {
3630     // Contrary to named constants appearing in a PARAMETER statement,
3631     // enumerator names should not have their type, dimension or any other
3632     // attributes defined before they are declared in the enumerator statement,
3633     // with the exception of accessibility.
3634     // This is not explicitly forbidden by the standard, but they are scalars
3635     // which type is left for the compiler to chose, so do not let users try to
3636     // tamper with that.
3637     SayAlreadyDeclared(name, *symbol);
3638     symbol = nullptr;
3639   } else {
3640     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3641     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3642     symbol->SetType(context().MakeNumericType(
3643         TypeCategory::Integer, evaluate::CInteger::kind));
3644   }
3645 
3646   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3647           enumerator.t)}) {
3648     Walk(*init); // Resolve names in expression before evaluation.
3649     if (auto value{EvaluateInt64(context(), *init)}) {
3650       // Cast all init expressions to C_INT so that they can then be
3651       // safely incremented (see 7.6 Note 2).
3652       enumerationState_.value = static_cast<int>(*value);
3653     } else {
3654       Say(name,
3655           "Enumerator value could not be computed "
3656           "from the given expression"_err_en_US);
3657       // Prevent resolution of next enumerators value
3658       enumerationState_.value = std::nullopt;
3659     }
3660   }
3661 
3662   if (symbol) {
3663     if (enumerationState_.value) {
3664       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3665           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3666     } else {
3667       context().SetError(*symbol);
3668     }
3669   }
3670 
3671   if (enumerationState_.value) {
3672     (*enumerationState_.value)++;
3673   }
3674   return false;
3675 }
3676 
3677 void DeclarationVisitor::Post(const parser::EnumDef &) {
3678   enumerationState_ = EnumeratorState{};
3679 }
3680 
3681 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3682   Attr attr{AccessSpecToAttr(x)};
3683   if (!NonDerivedTypeScope().IsModule()) { // C817
3684     Say(currStmtSource().value(),
3685         "%s attribute may only appear in the specification part of a module"_err_en_US,
3686         EnumToString(attr));
3687   }
3688   CheckAndSet(attr);
3689   return false;
3690 }
3691 
3692 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3693   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3694 }
3695 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3696   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3697 }
3698 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3699   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3700   for (const auto &name : x.v) {
3701     auto *symbol{FindSymbol(name)};
3702     if (!ConvertToProcEntity(*symbol)) {
3703       SayWithDecl(
3704           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3705     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
3706       Say(symbol->name(),
3707           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
3708           symbol->name());
3709     }
3710   }
3711   return false;
3712 }
3713 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3714   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3715   auto &names{std::get<std::list<parser::Name>>(x.t)};
3716   return CheckNotInBlock("INTENT") && // C1107
3717       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3718 }
3719 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3720   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3721   for (const auto &name : x.v) {
3722     auto &symbol{DEREF(FindSymbol(name))};
3723     if (!ConvertToProcEntity(symbol)) {
3724       SayWithDecl(
3725           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3726     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
3727       Say(symbol.name(),
3728           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3729           symbol.name());
3730     } else if (symbol.GetType()) {
3731       // These warnings are worded so that they should make sense in either
3732       // order.
3733       Say(symbol.name(),
3734           "Explicit type declaration ignored for intrinsic function '%s'"_en_US,
3735           symbol.name())
3736           .Attach(name.source,
3737               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
3738               name.source);
3739     }
3740   }
3741   return false;
3742 }
3743 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3744   return CheckNotInBlock("OPTIONAL") && // C1107
3745       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3746 }
3747 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3748   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3749 }
3750 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3751   return CheckNotInBlock("VALUE") && // C1107
3752       HandleAttributeStmt(Attr::VALUE, x.v);
3753 }
3754 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
3755   return HandleAttributeStmt(Attr::VOLATILE, x.v);
3756 }
3757 // Handle a statement that sets an attribute on a list of names.
3758 bool DeclarationVisitor::HandleAttributeStmt(
3759     Attr attr, const std::list<parser::Name> &names) {
3760   for (const auto &name : names) {
3761     HandleAttributeStmt(attr, name);
3762   }
3763   return false;
3764 }
3765 Symbol &DeclarationVisitor::HandleAttributeStmt(
3766     Attr attr, const parser::Name &name) {
3767   if (attr == Attr::INTRINSIC && !IsIntrinsic(name.source, std::nullopt)) {
3768     Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
3769   }
3770   auto *symbol{FindInScope(name)};
3771   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
3772     // these can be set on a symbol that is host-assoc or use-assoc
3773     if (!symbol &&
3774         (currScope().kind() == Scope::Kind::Subprogram ||
3775             currScope().kind() == Scope::Kind::Block)) {
3776       if (auto *hostSymbol{FindSymbol(name)}) {
3777         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
3778       }
3779     }
3780   } else if (symbol && symbol->has<UseDetails>()) {
3781     Say(currStmtSource().value(),
3782         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
3783         EnumToString(attr), name.source);
3784     return *symbol;
3785   }
3786   if (!symbol) {
3787     symbol = &MakeSymbol(name, EntityDetails{});
3788   }
3789   symbol->attrs().set(attr);
3790   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
3791   return *symbol;
3792 }
3793 // C1107
3794 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
3795   if (currScope().kind() == Scope::Kind::Block) {
3796     Say(MessageFormattedText{
3797         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
3798     return false;
3799   } else {
3800     return true;
3801   }
3802 }
3803 
3804 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
3805   CHECK(objectDeclAttr_);
3806   const auto &name{std::get<parser::ObjectName>(x.t)};
3807   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
3808 }
3809 
3810 // Declare an entity not yet known to be an object or proc.
3811 Symbol &DeclarationVisitor::DeclareUnknownEntity(
3812     const parser::Name &name, Attrs attrs) {
3813   if (!arraySpec().empty() || !coarraySpec().empty()) {
3814     return DeclareObjectEntity(name, attrs);
3815   } else {
3816     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
3817     if (auto *type{GetDeclTypeSpec()}) {
3818       SetType(name, *type);
3819     }
3820     charInfo_.length.reset();
3821     SetBindNameOn(symbol);
3822     if (symbol.attrs().test(Attr::EXTERNAL)) {
3823       ConvertToProcEntity(symbol);
3824     }
3825     return symbol;
3826   }
3827 }
3828 
3829 bool DeclarationVisitor::HasCycle(
3830     const Symbol &procSymbol, const ProcInterface &interface) {
3831   SourceOrderedSymbolSet procsInCycle;
3832   procsInCycle.insert(procSymbol);
3833   const ProcInterface *thisInterface{&interface};
3834   bool haveInterface{true};
3835   while (haveInterface) {
3836     haveInterface = false;
3837     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
3838       if (procsInCycle.count(*interfaceSymbol) > 0) {
3839         for (const auto &procInCycle : procsInCycle) {
3840           Say(procInCycle->name(),
3841               "The interface for procedure '%s' is recursively "
3842               "defined"_err_en_US,
3843               procInCycle->name());
3844           context().SetError(*procInCycle);
3845         }
3846         return true;
3847       } else if (const auto *procDetails{
3848                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
3849         haveInterface = true;
3850         thisInterface = &procDetails->interface();
3851         procsInCycle.insert(*interfaceSymbol);
3852       }
3853     }
3854   }
3855   return false;
3856 }
3857 
3858 Symbol &DeclarationVisitor::DeclareProcEntity(
3859     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
3860   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
3861   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
3862     if (details->IsInterfaceSet()) {
3863       SayWithDecl(name, symbol,
3864           "The interface for procedure '%s' has already been "
3865           "declared"_err_en_US);
3866       context().SetError(symbol);
3867     } else if (HasCycle(symbol, interface)) {
3868       return symbol;
3869     } else if (interface.type()) {
3870       symbol.set(Symbol::Flag::Function);
3871     } else if (interface.symbol()) {
3872       if (interface.symbol()->test(Symbol::Flag::Function)) {
3873         symbol.set(Symbol::Flag::Function);
3874       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
3875         symbol.set(Symbol::Flag::Subroutine);
3876       }
3877     }
3878     details->set_interface(interface);
3879     SetBindNameOn(symbol);
3880     SetPassNameOn(symbol);
3881   }
3882   return symbol;
3883 }
3884 
3885 Symbol &DeclarationVisitor::DeclareObjectEntity(
3886     const parser::Name &name, Attrs attrs) {
3887   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
3888   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
3889     if (auto *type{GetDeclTypeSpec()}) {
3890       SetType(name, *type);
3891     }
3892     if (!arraySpec().empty()) {
3893       if (details->IsArray()) {
3894         if (!context().HasError(symbol)) {
3895           Say(name,
3896               "The dimensions of '%s' have already been declared"_err_en_US);
3897           context().SetError(symbol);
3898         }
3899       } else {
3900         details->set_shape(arraySpec());
3901       }
3902     }
3903     if (!coarraySpec().empty()) {
3904       if (details->IsCoarray()) {
3905         if (!context().HasError(symbol)) {
3906           Say(name,
3907               "The codimensions of '%s' have already been declared"_err_en_US);
3908           context().SetError(symbol);
3909         }
3910       } else {
3911         details->set_coshape(coarraySpec());
3912       }
3913     }
3914     SetBindNameOn(symbol);
3915   }
3916   ClearArraySpec();
3917   ClearCoarraySpec();
3918   charInfo_.length.reset();
3919   return symbol;
3920 }
3921 
3922 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
3923   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
3924 }
3925 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
3926   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
3927 }
3928 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
3929   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
3930 }
3931 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
3932   SetDeclTypeSpec(MakeLogicalType(x.kind));
3933 }
3934 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
3935   if (!charInfo_.length) {
3936     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
3937   }
3938   if (!charInfo_.kind) {
3939     charInfo_.kind =
3940         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
3941   }
3942   SetDeclTypeSpec(currScope().MakeCharacterType(
3943       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
3944   charInfo_ = {};
3945 }
3946 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
3947   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
3948   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
3949   if (intKind &&
3950       !evaluate::IsValidKindOfIntrinsicType(
3951           TypeCategory::Character, *intKind)) { // C715, C719
3952     Say(currStmtSource().value(),
3953         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
3954     charInfo_.kind = std::nullopt; // prevent further errors
3955   }
3956   if (x.length) {
3957     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
3958   }
3959 }
3960 void DeclarationVisitor::Post(const parser::CharLength &x) {
3961   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
3962     charInfo_.length = ParamValue{
3963         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
3964   } else {
3965     charInfo_.length = GetParamValue(
3966         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
3967   }
3968 }
3969 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
3970   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
3971     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
3972   }
3973 }
3974 
3975 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
3976   if (const auto *kind{std::get_if<
3977           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
3978           &x.u)}) {
3979     const parser::Name &name{kind->thing.thing.thing};
3980     if (!FindSymbol(name)) {
3981       Say(name, "Parameter '%s' not found"_err_en_US);
3982     }
3983   }
3984   return false;
3985 }
3986 
3987 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
3988   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
3989   return true;
3990 }
3991 
3992 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
3993   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
3994   if (const Symbol * derivedSymbol{derivedName.symbol}) {
3995     CheckForAbstractType(*derivedSymbol); // C706
3996   }
3997 }
3998 
3999 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4000   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4001   return true;
4002 }
4003 
4004 void DeclarationVisitor::Post(
4005     const parser::DeclarationTypeSpec::Class &parsedClass) {
4006   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4007   if (auto spec{ResolveDerivedType(typeName)};
4008       spec && !IsExtensibleType(&*spec)) { // C705
4009     SayWithDecl(typeName, *typeName.symbol,
4010         "Non-extensible derived type '%s' may not be used with CLASS"
4011         " keyword"_err_en_US);
4012   }
4013 }
4014 
4015 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4016   const auto &typeName{std::get<parser::Name>(x.t)};
4017   auto spec{ResolveDerivedType(typeName)};
4018   if (!spec) {
4019     return;
4020   }
4021   bool seenAnyName{false};
4022   for (const auto &typeParamSpec :
4023       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4024     const auto &optKeyword{
4025         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4026     std::optional<SourceName> name;
4027     if (optKeyword) {
4028       seenAnyName = true;
4029       name = optKeyword->v.source;
4030     } else if (seenAnyName) {
4031       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4032       continue;
4033     }
4034     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4035     // The expressions in a derived type specifier whose values define
4036     // non-defaulted type parameters are evaluated (folded) in the enclosing
4037     // scope.  The KIND/LEN distinction is resolved later in
4038     // DerivedTypeSpec::CookParameters().
4039     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4040     if (!param.isExplicit() || param.GetExplicit()) {
4041       spec->AddRawParamValue(optKeyword, std::move(param));
4042     }
4043   }
4044 
4045   // The DerivedTypeSpec *spec is used initially as a search key.
4046   // If it turns out to have the same name and actual parameter
4047   // value expressions as another DerivedTypeSpec in the current
4048   // scope does, then we'll use that extant spec; otherwise, when this
4049   // spec is distinct from all derived types previously instantiated
4050   // in the current scope, this spec will be moved into that collection.
4051   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4052   auto category{GetDeclTypeSpecCategory()};
4053   if (dtDetails.isForwardReferenced()) {
4054     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4055     SetDeclTypeSpec(type);
4056     return;
4057   }
4058   // Normalize parameters to produce a better search key.
4059   spec->CookParameters(GetFoldingContext());
4060   if (!spec->MightBeParameterized()) {
4061     spec->EvaluateParameters(context());
4062   }
4063   if (const DeclTypeSpec *
4064       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4065     // This derived type and parameter expressions (if any) are already present
4066     // in this scope.
4067     SetDeclTypeSpec(*extant);
4068   } else {
4069     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4070     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4071     if (derived.MightBeParameterized() &&
4072         currScope().IsParameterizedDerivedType()) {
4073       // Defer instantiation; use the derived type's definition's scope.
4074       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4075     } else if (&currScope() == spec->typeSymbol().scope()) {
4076       // Direct recursive use of a type in the definition of one of its
4077       // components: defer instantiation
4078     } else {
4079       auto restorer{
4080           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4081       derived.Instantiate(currScope());
4082     }
4083     SetDeclTypeSpec(type);
4084   }
4085   // Capture the DerivedTypeSpec in the parse tree for use in building
4086   // structure constructor expressions.
4087   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4088 }
4089 
4090 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4091   const auto &typeName{rec.v};
4092   if (auto spec{ResolveDerivedType(typeName)}) {
4093     spec->CookParameters(GetFoldingContext());
4094     spec->EvaluateParameters(context());
4095     if (const DeclTypeSpec *
4096         extant{currScope().FindInstantiatedDerivedType(
4097             *spec, DeclTypeSpec::TypeDerived)}) {
4098       SetDeclTypeSpec(*extant);
4099     } else {
4100       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4101           typeName.source);
4102     }
4103   }
4104 }
4105 
4106 // The descendents of DerivedTypeDef in the parse tree are visited directly
4107 // in this Pre() routine so that recursive use of the derived type can be
4108 // supported in the components.
4109 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4110   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4111   Walk(stmt);
4112   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4113   auto &scope{currScope()};
4114   CHECK(scope.symbol());
4115   CHECK(scope.symbol()->scope() == &scope);
4116   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4117   details.set_isForwardReferenced(false);
4118   std::set<SourceName> paramNames;
4119   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4120     details.add_paramName(paramName.source);
4121     auto *symbol{FindInScope(scope, paramName)};
4122     if (!symbol) {
4123       Say(paramName,
4124           "No definition found for type parameter '%s'"_err_en_US); // C742
4125       // No symbol for a type param.  Create one and mark it as containing an
4126       // error to improve subsequent semantic processing
4127       BeginAttrs();
4128       Symbol *typeParam{MakeTypeSymbol(
4129           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4130       context().SetError(*typeParam);
4131       EndAttrs();
4132     } else if (!symbol->has<TypeParamDetails>()) {
4133       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4134           *symbol, "Definition of '%s'"_en_US); // C741
4135     }
4136     if (!paramNames.insert(paramName.source).second) {
4137       Say(paramName,
4138           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4139     }
4140   }
4141   for (const auto &[name, symbol] : currScope()) {
4142     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4143       SayDerivedType(name,
4144           "'%s' is not a type parameter of this derived type"_err_en_US,
4145           currScope()); // C741
4146     }
4147   }
4148   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4149   const auto &componentDefs{
4150       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4151   Walk(componentDefs);
4152   if (derivedTypeInfo_.sequence) {
4153     details.set_sequence(true);
4154     if (componentDefs.empty()) { // C740
4155       Say(stmt.source,
4156           "A sequence type must have at least one component"_err_en_US);
4157     }
4158     if (!details.paramNames().empty()) { // C740
4159       Say(stmt.source,
4160           "A sequence type may not have type parameters"_err_en_US);
4161     }
4162     if (derivedTypeInfo_.extends) { // C735
4163       Say(stmt.source,
4164           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4165     }
4166   }
4167   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4168   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4169   derivedTypeInfo_ = {};
4170   PopScope();
4171   return false;
4172 }
4173 
4174 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4175   return BeginAttrs();
4176 }
4177 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4178   auto &name{std::get<parser::Name>(x.t)};
4179   // Resolve the EXTENDS() clause before creating the derived
4180   // type's symbol to foil attempts to recursively extend a type.
4181   auto *extendsName{derivedTypeInfo_.extends};
4182   std::optional<DerivedTypeSpec> extendsType{
4183       ResolveExtendsType(name, extendsName)};
4184   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4185   symbol.ReplaceName(name.source);
4186   derivedTypeInfo_.type = &symbol;
4187   PushScope(Scope::Kind::DerivedType, &symbol);
4188   if (extendsType) {
4189     // Declare the "parent component"; private if the type is.
4190     // Any symbol stored in the EXTENDS() clause is temporarily
4191     // hidden so that a new symbol can be created for the parent
4192     // component without producing spurious errors about already
4193     // existing.
4194     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4195     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4196     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4197       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4198       comp.attrs().set(
4199           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4200       comp.set(Symbol::Flag::ParentComp);
4201       DeclTypeSpec &type{currScope().MakeDerivedType(
4202           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4203       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4204       comp.SetType(type);
4205       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4206       details.add_component(comp);
4207     }
4208   }
4209   EndAttrs();
4210 }
4211 
4212 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4213   auto *type{GetDeclTypeSpec()};
4214   auto attr{std::get<common::TypeParamAttr>(x.t)};
4215   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4216     auto &name{std::get<parser::Name>(decl.t)};
4217     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4218       SetType(name, *type);
4219       if (auto &init{
4220               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4221         if (auto maybeExpr{EvaluateNonPointerInitializer(
4222                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4223           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4224             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4225           }
4226         }
4227       }
4228     }
4229   }
4230   EndDecl();
4231 }
4232 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4233   if (derivedTypeInfo_.extends) {
4234     Say(currStmtSource().value(),
4235         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4236   } else {
4237     derivedTypeInfo_.extends = &x.v;
4238   }
4239   return false;
4240 }
4241 
4242 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4243   if (!currScope().parent().IsModule()) {
4244     Say("PRIVATE is only allowed in a derived type that is"
4245         " in a module"_err_en_US); // C766
4246   } else if (derivedTypeInfo_.sawContains) {
4247     derivedTypeInfo_.privateBindings = true;
4248   } else if (!derivedTypeInfo_.privateComps) {
4249     derivedTypeInfo_.privateComps = true;
4250   } else {
4251     Say("PRIVATE may not appear more than once in"
4252         " derived type components"_en_US); // C738
4253   }
4254   return false;
4255 }
4256 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4257   if (derivedTypeInfo_.sequence) {
4258     Say("SEQUENCE may not appear more than once in"
4259         " derived type components"_en_US); // C738
4260   }
4261   derivedTypeInfo_.sequence = true;
4262   return false;
4263 }
4264 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4265   const auto &name{std::get<parser::Name>(x.t)};
4266   auto attrs{GetAttrs()};
4267   if (derivedTypeInfo_.privateComps &&
4268       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4269     attrs.set(Attr::PRIVATE);
4270   }
4271   if (const auto *declType{GetDeclTypeSpec()}) {
4272     if (const auto *derived{declType->AsDerived()}) {
4273       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4274         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4275           Say("Recursive use of the derived type requires "
4276               "POINTER or ALLOCATABLE"_err_en_US);
4277         }
4278       }
4279       // TODO: This would be more appropriate in CheckDerivedType()
4280       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4281         std::string ultimateName{it.BuildResultDesignatorName()};
4282         // Strip off the leading "%"
4283         if (ultimateName.length() > 1) {
4284           ultimateName.erase(0, 1);
4285           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4286             evaluate::AttachDeclaration(
4287                 Say(name.source,
4288                     "A component with a POINTER or ALLOCATABLE attribute may "
4289                     "not "
4290                     "be of a type with a coarray ultimate component (named "
4291                     "'%s')"_err_en_US,
4292                     ultimateName),
4293                 derived->typeSymbol());
4294           }
4295           if (!arraySpec().empty() || !coarraySpec().empty()) {
4296             evaluate::AttachDeclaration(
4297                 Say(name.source,
4298                     "An array or coarray component may not be of a type with a "
4299                     "coarray ultimate component (named '%s')"_err_en_US,
4300                     ultimateName),
4301                 derived->typeSymbol());
4302           }
4303         }
4304       }
4305     }
4306   }
4307   if (OkToAddComponent(name)) {
4308     auto &symbol{DeclareObjectEntity(name, attrs)};
4309     if (symbol.has<ObjectEntityDetails>()) {
4310       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4311         Initialization(name, *init, true);
4312       }
4313     }
4314     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4315   }
4316   ClearArraySpec();
4317   ClearCoarraySpec();
4318 }
4319 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4320   // Replace "%FILL" with a distinct generated name
4321   const auto &name{std::get<parser::Name>(x.t)};
4322   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4323   if (OkToAddComponent(name)) {
4324     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4325     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4326   }
4327   ClearArraySpec();
4328 }
4329 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4330   CHECK(!interfaceName_);
4331   return BeginDecl();
4332 }
4333 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4334   interfaceName_ = nullptr;
4335   EndDecl();
4336 }
4337 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4338   // Overrides parse tree traversal so as to handle attributes first,
4339   // so POINTER & ALLOCATABLE enable forward references to derived types.
4340   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4341   set_allowForwardReferenceToDerivedType(
4342       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4343   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4344   set_allowForwardReferenceToDerivedType(false);
4345   if (derivedTypeInfo_.sequence) { // C740
4346     if (const auto *declType{GetDeclTypeSpec()}) {
4347       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4348         if (GetAttrs().test(Attr::POINTER) &&
4349             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4350           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4351             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_en_US);
4352           }
4353         } else {
4354           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4355         }
4356       }
4357     }
4358   }
4359   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4360   return false;
4361 }
4362 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4363   CHECK(!interfaceName_);
4364   return true;
4365 }
4366 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4367   interfaceName_ = nullptr;
4368 }
4369 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4370   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4371     return !NameIsKnownOrIntrinsic(*name);
4372   }
4373   return true;
4374 }
4375 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4376   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4377     interfaceName_ = name;
4378     NoteInterfaceName(*name);
4379   }
4380 }
4381 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4382   const auto &name{std::get<parser::Name>(x.t)};
4383   ProcInterface interface;
4384   if (interfaceName_) {
4385     interface.set_symbol(*interfaceName_->symbol);
4386   } else if (auto *type{GetDeclTypeSpec()}) {
4387     interface.set_type(*type);
4388   }
4389   auto attrs{HandleSaveName(name.source, GetAttrs())};
4390   DerivedTypeDetails *dtDetails{nullptr};
4391   if (Symbol * symbol{currScope().symbol()}) {
4392     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4393   }
4394   if (!dtDetails) {
4395     attrs.set(Attr::EXTERNAL);
4396   }
4397   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4398   symbol.ReplaceName(name.source);
4399   if (dtDetails) {
4400     dtDetails->add_component(symbol);
4401   }
4402 }
4403 
4404 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4405   derivedTypeInfo_.sawContains = true;
4406   return true;
4407 }
4408 
4409 // Resolve binding names from type-bound generics, saved in genericBindings_.
4410 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4411   // track specifics seen for the current generic to detect duplicates:
4412   const Symbol *currGeneric{nullptr};
4413   std::set<SourceName> specifics;
4414   for (const auto &[generic, bindingName] : genericBindings_) {
4415     if (generic != currGeneric) {
4416       currGeneric = generic;
4417       specifics.clear();
4418     }
4419     auto [it, inserted]{specifics.insert(bindingName->source)};
4420     if (!inserted) {
4421       Say(*bindingName, // C773
4422           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4423           bindingName->source, generic->name())
4424           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4425       continue;
4426     }
4427     auto *symbol{FindInTypeOrParents(*bindingName)};
4428     if (!symbol) {
4429       Say(*bindingName, // C772
4430           "Binding name '%s' not found in this derived type"_err_en_US);
4431     } else if (!symbol->has<ProcBindingDetails>()) {
4432       SayWithDecl(*bindingName, *symbol, // C772
4433           "'%s' is not the name of a specific binding of this type"_err_en_US);
4434     } else {
4435       generic->get<GenericDetails>().AddSpecificProc(
4436           *symbol, bindingName->source);
4437     }
4438   }
4439   genericBindings_.clear();
4440 }
4441 
4442 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4443   if (derivedTypeInfo_.sequence) {
4444     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4445   }
4446 }
4447 
4448 void DeclarationVisitor::Post(
4449     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4450   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4451     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4452   }
4453   for (auto &declaration : x.declarations) {
4454     auto &bindingName{std::get<parser::Name>(declaration.t)};
4455     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4456     const parser::Name &procedureName{optName ? *optName : bindingName};
4457     Symbol *procedure{FindSymbol(procedureName)};
4458     if (!procedure) {
4459       procedure = NoteInterfaceName(procedureName);
4460     }
4461     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4462       SetPassNameOn(*s);
4463       if (GetAttrs().test(Attr::DEFERRED)) {
4464         context().SetError(*s);
4465       }
4466     }
4467   }
4468 }
4469 
4470 void DeclarationVisitor::CheckBindings(
4471     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4472   CHECK(currScope().IsDerivedType());
4473   for (auto &declaration : tbps.declarations) {
4474     auto &bindingName{std::get<parser::Name>(declaration.t)};
4475     if (Symbol * binding{FindInScope(bindingName)}) {
4476       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4477         const Symbol *procedure{FindSubprogram(details->symbol())};
4478         if (!CanBeTypeBoundProc(procedure)) {
4479           if (details->symbol().name() != binding->name()) {
4480             Say(binding->name(),
4481                 "The binding of '%s' ('%s') must be either an accessible "
4482                 "module procedure or an external procedure with "
4483                 "an explicit interface"_err_en_US,
4484                 binding->name(), details->symbol().name());
4485           } else {
4486             Say(binding->name(),
4487                 "'%s' must be either an accessible module procedure "
4488                 "or an external procedure with an explicit interface"_err_en_US,
4489                 binding->name());
4490           }
4491           context().SetError(*binding);
4492         }
4493       }
4494     }
4495   }
4496 }
4497 
4498 void DeclarationVisitor::Post(
4499     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4500   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4501     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4502   }
4503   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4504     for (auto &bindingName : x.bindingNames) {
4505       if (auto *s{
4506               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4507         SetPassNameOn(*s);
4508         if (!GetAttrs().test(Attr::DEFERRED)) {
4509           context().SetError(*s);
4510         }
4511       }
4512     }
4513   }
4514 }
4515 
4516 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4517   if (currScope().IsDerivedType() && currScope().symbol()) {
4518     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4519       for (const auto &subrName : x.v) {
4520         if (const auto *name{ResolveName(subrName)}) {
4521           auto pair{
4522               details->finals().emplace(name->source, DEREF(name->symbol))};
4523           if (!pair.second) { // C787
4524             Say(name->source,
4525                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4526                 name->source)
4527                 .Attach(pair.first->first,
4528                     "earlier appearance of this FINAL subroutine"_en_US);
4529           }
4530         }
4531       }
4532     }
4533   }
4534 }
4535 
4536 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4537   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4538   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4539   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4540   auto info{GenericSpecInfo{genericSpec.value()}};
4541   SourceName symbolName{info.symbolName()};
4542   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4543                             : derivedTypeInfo_.privateBindings};
4544   auto *genericSymbol{FindInScope(symbolName)};
4545   if (genericSymbol) {
4546     if (!genericSymbol->has<GenericDetails>()) {
4547       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4548     }
4549   } else {
4550     // look in parent types:
4551     Symbol *inheritedSymbol{nullptr};
4552     for (const auto &name : GetAllNames(context(), symbolName)) {
4553       inheritedSymbol = currScope().FindComponent(SourceName{name});
4554       if (inheritedSymbol) {
4555         break;
4556       }
4557     }
4558     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4559       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4560     }
4561   }
4562   if (genericSymbol) {
4563     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4564   } else {
4565     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4566     if (!genericSymbol) {
4567       return false;
4568     }
4569     if (isPrivate) {
4570       genericSymbol->attrs().set(Attr::PRIVATE);
4571     }
4572   }
4573   for (const parser::Name &bindingName : bindingNames) {
4574     genericBindings_.emplace(genericSymbol, &bindingName);
4575   }
4576   info.Resolve(genericSymbol);
4577   return false;
4578 }
4579 
4580 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4581 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4582   const auto &structureStatement{
4583       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4584   auto saveDerivedTypeInfo{derivedTypeInfo_};
4585   derivedTypeInfo_ = {};
4586   derivedTypeInfo_.isStructure = true;
4587   derivedTypeInfo_.sequence = true;
4588   Scope *previousStructure{nullptr};
4589   if (saveDerivedTypeInfo.isStructure) {
4590     previousStructure = &currScope();
4591     PopScope();
4592   }
4593   const parser::StructureStmt &structStmt{structureStatement.statement};
4594   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4595   if (!name) {
4596     // Construct a distinct generated name for an anonymous structure
4597     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4598     mutableName.emplace(
4599         parser::Name{context().GetTempName(currScope()), nullptr});
4600   }
4601   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4602   symbol.ReplaceName(name->source);
4603   symbol.get<DerivedTypeDetails>().set_sequence(true);
4604   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4605   derivedTypeInfo_.type = &symbol;
4606   PushScope(Scope::Kind::DerivedType, &symbol);
4607   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4608   Walk(fields);
4609   PopScope();
4610   // Complete the definition
4611   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4612   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4613   derivedTypeSpec.CookParameters(GetFoldingContext());
4614   derivedTypeSpec.EvaluateParameters(context());
4615   DeclTypeSpec &type{currScope().MakeDerivedType(
4616       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4617   type.derivedTypeSpec().Instantiate(currScope());
4618   // Restore previous structure definition context, if any
4619   derivedTypeInfo_ = saveDerivedTypeInfo;
4620   if (previousStructure) {
4621     PushScope(*previousStructure);
4622   }
4623   // Handle any entity declarations on the STRUCTURE statement
4624   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4625   if (!decls.empty()) {
4626     BeginDecl();
4627     SetDeclTypeSpec(type);
4628     Walk(decls);
4629     EndDecl();
4630   }
4631   return false;
4632 }
4633 
4634 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
4635   Say("UNION is not yet supported"_err_en_US); // TODO
4636   return true;
4637 }
4638 
4639 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
4640   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4641           x.u)) {
4642     BeginDecl();
4643   }
4644   return true;
4645 }
4646 
4647 void DeclarationVisitor::Post(const parser::StructureField &x) {
4648   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4649           x.u)) {
4650     EndDecl();
4651   }
4652 }
4653 
4654 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4655   BeginDeclTypeSpec();
4656   return true;
4657 }
4658 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4659   EndDeclTypeSpec();
4660 }
4661 
4662 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4663   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4664   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4665   if (!type) {
4666     return false;
4667   }
4668   const DerivedTypeSpec *spec{type->AsDerived()};
4669   const Scope *typeScope{spec ? spec->scope() : nullptr};
4670   if (!typeScope) {
4671     return false;
4672   }
4673 
4674   // N.B C7102 is implicitly enforced by having inaccessible types not
4675   // being found in resolution.
4676   // More constraints are enforced in expression.cpp so that they
4677   // can apply to structure constructors that have been converted
4678   // from misparsed function references.
4679   for (const auto &component :
4680       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4681     // Visit the component spec expression, but not the keyword, since
4682     // we need to resolve its symbol in the scope of the derived type.
4683     Walk(std::get<parser::ComponentDataSource>(component.t));
4684     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4685       FindInTypeOrParents(*typeScope, kw->v);
4686     }
4687   }
4688   return false;
4689 }
4690 
4691 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4692   for (const parser::BasedPointer &bp : x.v) {
4693     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4694     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4695     auto *pointer{FindSymbol(pointerName)};
4696     if (!pointer) {
4697       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4698     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4699       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4700     } else if (pointer->Rank() > 0) {
4701       SayWithDecl(pointerName, *pointer,
4702           "Cray pointer '%s' must be a scalar"_err_en_US);
4703     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4704       Say(pointerName,
4705           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4706     }
4707     pointer->set(Symbol::Flag::CrayPointer);
4708     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4709         context().defaultKinds().subscriptIntegerKind())};
4710     const auto *type{pointer->GetType()};
4711     if (!type) {
4712       pointer->SetType(pointerType);
4713     } else if (*type != pointerType) {
4714       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4715           pointerName.source, pointerType.AsFortran());
4716     }
4717     if (ResolveName(pointeeName)) {
4718       Symbol &pointee{*pointeeName.symbol};
4719       if (pointee.has<UseDetails>()) {
4720         Say(pointeeName,
4721             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4722         continue;
4723       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4724         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4725         continue;
4726       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4727         Say(pointeeName,
4728             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4729       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4730         Say(pointeeName,
4731             "'%s' was already declared as a Cray pointee"_err_en_US);
4732       } else {
4733         pointee.set(Symbol::Flag::CrayPointee);
4734       }
4735       if (const auto *pointeeType{pointee.GetType()}) {
4736         if (const auto *derived{pointeeType->AsDerived()}) {
4737           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
4738             Say(pointeeName,
4739                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
4740           }
4741         }
4742       }
4743       // process the pointee array-spec, if present
4744       BeginArraySpec();
4745       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
4746       const auto &spec{arraySpec()};
4747       if (!spec.empty()) {
4748         auto &details{pointee.get<ObjectEntityDetails>()};
4749         if (details.shape().empty()) {
4750           details.set_shape(spec);
4751         } else {
4752           SayWithDecl(pointeeName, pointee,
4753               "Array spec was already declared for '%s'"_err_en_US);
4754         }
4755       }
4756       ClearArraySpec();
4757       currScope().add_crayPointer(pointeeName.source, *pointer);
4758     }
4759   }
4760   return false;
4761 }
4762 
4763 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
4764   if (!CheckNotInBlock("NAMELIST")) { // C1107
4765     return false;
4766   }
4767 
4768   NamelistDetails details;
4769   for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
4770     auto *symbol{FindSymbol(name)};
4771     if (!symbol) {
4772       symbol = &MakeSymbol(name, ObjectEntityDetails{});
4773       ApplyImplicitRules(*symbol);
4774     } else if (!ConvertToObjectEntity(*symbol)) {
4775       SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
4776     }
4777     symbol->GetUltimate().set(Symbol::Flag::InNamelist);
4778     details.add_object(*symbol);
4779   }
4780 
4781   const auto &groupName{std::get<parser::Name>(x.t)};
4782   auto *groupSymbol{FindInScope(groupName)};
4783   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
4784     groupSymbol = &MakeSymbol(groupName, std::move(details));
4785     groupSymbol->ReplaceName(groupName.source);
4786   }
4787   groupSymbol->get<NamelistDetails>().add_objects(details.objects());
4788   return false;
4789 }
4790 
4791 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
4792   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
4793     auto *symbol{FindSymbol(*name)};
4794     if (!symbol) {
4795       Say(*name, "Namelist group '%s' not found"_err_en_US);
4796     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
4797       SayWithDecl(
4798           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
4799     }
4800   }
4801   return true;
4802 }
4803 
4804 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
4805   CheckNotInBlock("COMMON"); // C1107
4806   return true;
4807 }
4808 
4809 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
4810   BeginArraySpec();
4811   return true;
4812 }
4813 
4814 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
4815   const auto &name{std::get<parser::Name>(x.t)};
4816   DeclareObjectEntity(name);
4817   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
4818   if (!pair.second) {
4819     const SourceName &prev{*pair.first};
4820     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
4821         "Previous occurrence of '%s' in a COMMON block"_en_US);
4822   }
4823 }
4824 
4825 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
4826   // save equivalence sets to be processed after specification part
4827   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
4828     for (const std::list<parser::EquivalenceObject> &set : x.v) {
4829       specPartState_.equivalenceSets.push_back(&set);
4830     }
4831   }
4832   return false; // don't implicitly declare names yet
4833 }
4834 
4835 void DeclarationVisitor::CheckEquivalenceSets() {
4836   EquivalenceSets equivSets{context()};
4837   inEquivalenceStmt_ = true;
4838   for (const auto *set : specPartState_.equivalenceSets) {
4839     const auto &source{set->front().v.value().source};
4840     if (set->size() <= 1) { // R871
4841       Say(source, "Equivalence set must have more than one object"_err_en_US);
4842     }
4843     for (const parser::EquivalenceObject &object : *set) {
4844       const auto &designator{object.v.value()};
4845       // The designator was not resolved when it was encountered so do it now.
4846       // AnalyzeExpr causes array sections to be changed to substrings as needed
4847       Walk(designator);
4848       if (AnalyzeExpr(context(), designator)) {
4849         equivSets.AddToSet(designator);
4850       }
4851     }
4852     equivSets.FinishSet(source);
4853   }
4854   inEquivalenceStmt_ = false;
4855   for (auto &set : equivSets.sets()) {
4856     if (!set.empty()) {
4857       currScope().add_equivalenceSet(std::move(set));
4858     }
4859   }
4860   specPartState_.equivalenceSets.clear();
4861 }
4862 
4863 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
4864   if (x.v.empty()) {
4865     specPartState_.saveInfo.saveAll = currStmtSource();
4866     currScope().set_hasSAVE();
4867   } else {
4868     for (const parser::SavedEntity &y : x.v) {
4869       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
4870       const auto &name{std::get<parser::Name>(y.t)};
4871       if (kind == parser::SavedEntity::Kind::Common) {
4872         MakeCommonBlockSymbol(name);
4873         AddSaveName(specPartState_.saveInfo.commons, name.source);
4874       } else {
4875         HandleAttributeStmt(Attr::SAVE, name);
4876       }
4877     }
4878   }
4879   return false;
4880 }
4881 
4882 void DeclarationVisitor::CheckSaveStmts() {
4883   for (const SourceName &name : specPartState_.saveInfo.entities) {
4884     auto *symbol{FindInScope(name)};
4885     if (!symbol) {
4886       // error was reported
4887     } else if (specPartState_.saveInfo.saveAll) {
4888       // C889 - note that pgi, ifort, xlf do not enforce this constraint
4889       Say2(name,
4890           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
4891           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
4892     } else if (auto msg{CheckSaveAttr(*symbol)}) {
4893       Say(name, std::move(*msg));
4894       context().SetError(*symbol);
4895     } else {
4896       SetSaveAttr(*symbol);
4897     }
4898   }
4899   for (const SourceName &name : specPartState_.saveInfo.commons) {
4900     if (auto *symbol{currScope().FindCommonBlock(name)}) {
4901       auto &objects{symbol->get<CommonBlockDetails>().objects()};
4902       if (objects.empty()) {
4903         if (currScope().kind() != Scope::Kind::Block) {
4904           Say(name,
4905               "'%s' appears as a COMMON block in a SAVE statement but not in"
4906               " a COMMON statement"_err_en_US);
4907         } else { // C1108
4908           Say(name,
4909               "SAVE statement in BLOCK construct may not contain a"
4910               " common block name '%s'"_err_en_US);
4911         }
4912       } else {
4913         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
4914           SetSaveAttr(*object);
4915         }
4916       }
4917     }
4918   }
4919   if (specPartState_.saveInfo.saveAll) {
4920     // Apply SAVE attribute to applicable symbols
4921     for (auto pair : currScope()) {
4922       auto &symbol{*pair.second};
4923       if (!CheckSaveAttr(symbol)) {
4924         SetSaveAttr(symbol);
4925       }
4926     }
4927   }
4928   specPartState_.saveInfo = {};
4929 }
4930 
4931 // If SAVE attribute can't be set on symbol, return error message.
4932 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
4933     const Symbol &symbol) {
4934   if (IsDummy(symbol)) {
4935     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
4936   } else if (symbol.IsFuncResult()) {
4937     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
4938   } else if (symbol.has<ProcEntityDetails>() &&
4939       !symbol.attrs().test(Attr::POINTER)) {
4940     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
4941   } else if (IsAutomatic(symbol)) {
4942     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
4943   } else {
4944     return std::nullopt;
4945   }
4946 }
4947 
4948 // Record SAVEd names in specPartState_.saveInfo.entities.
4949 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
4950   if (attrs.test(Attr::SAVE)) {
4951     AddSaveName(specPartState_.saveInfo.entities, name);
4952   }
4953   return attrs;
4954 }
4955 
4956 // Record a name in a set of those to be saved.
4957 void DeclarationVisitor::AddSaveName(
4958     std::set<SourceName> &set, const SourceName &name) {
4959   auto pair{set.insert(name)};
4960   if (!pair.second) {
4961     Say2(name, "SAVE attribute was already specified on '%s'"_en_US,
4962         *pair.first, "Previous specification of SAVE attribute"_en_US);
4963   }
4964 }
4965 
4966 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
4967 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
4968   if (!IsSaved(symbol)) {
4969     symbol.attrs().set(Attr::SAVE);
4970   }
4971 }
4972 
4973 // Check types of common block objects, now that they are known.
4974 void DeclarationVisitor::CheckCommonBlocks() {
4975   // check for empty common blocks
4976   for (const auto &pair : currScope().commonBlocks()) {
4977     const auto &symbol{*pair.second};
4978     if (symbol.get<CommonBlockDetails>().objects().empty() &&
4979         symbol.attrs().test(Attr::BIND_C)) {
4980       Say(symbol.name(),
4981           "'%s' appears as a COMMON block in a BIND statement but not in"
4982           " a COMMON statement"_err_en_US);
4983     }
4984   }
4985   // check objects in common blocks
4986   for (const auto &name : specPartState_.commonBlockObjects) {
4987     const auto *symbol{currScope().FindSymbol(name)};
4988     if (!symbol) {
4989       continue;
4990     }
4991     const auto &attrs{symbol->attrs()};
4992     if (attrs.test(Attr::ALLOCATABLE)) {
4993       Say(name,
4994           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
4995     } else if (attrs.test(Attr::BIND_C)) {
4996       Say(name,
4997           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
4998     } else if (IsDummy(*symbol)) {
4999       Say(name,
5000           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5001     } else if (symbol->IsFuncResult()) {
5002       Say(name,
5003           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5004     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5005       if (type->category() == DeclTypeSpec::ClassStar) {
5006         Say(name,
5007             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5008       } else if (const auto *derived{type->AsDerived()}) {
5009         auto &typeSymbol{derived->typeSymbol()};
5010         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5011             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5012           Say(name,
5013               "Derived type '%s' in COMMON block must have the BIND or"
5014               " SEQUENCE attribute"_err_en_US);
5015         }
5016         CheckCommonBlockDerivedType(name, typeSymbol);
5017       }
5018     }
5019   }
5020   specPartState_.commonBlockObjects = {};
5021 }
5022 
5023 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5024   return Resolve(name, currScope().MakeCommonBlock(name.source));
5025 }
5026 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5027     const std::optional<parser::Name> &name) {
5028   if (name) {
5029     return MakeCommonBlockSymbol(*name);
5030   } else {
5031     return MakeCommonBlockSymbol(parser::Name{});
5032   }
5033 }
5034 
5035 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5036   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5037 }
5038 
5039 // Check if this derived type can be in a COMMON block.
5040 void DeclarationVisitor::CheckCommonBlockDerivedType(
5041     const SourceName &name, const Symbol &typeSymbol) {
5042   if (const auto *scope{typeSymbol.scope()}) {
5043     for (const auto &pair : *scope) {
5044       const Symbol &component{*pair.second};
5045       if (component.attrs().test(Attr::ALLOCATABLE)) {
5046         Say2(name,
5047             "Derived type variable '%s' may not appear in a COMMON block"
5048             " due to ALLOCATABLE component"_err_en_US,
5049             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5050         return;
5051       }
5052       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5053       if (component.test(Symbol::Flag::InDataStmt) ||
5054           (details && details->init())) {
5055         Say2(name,
5056             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5057             component.name(), "Component with default initialization"_en_US);
5058         return;
5059       }
5060       if (details) {
5061         if (const auto *type{details->type()}) {
5062           if (const auto *derived{type->AsDerived()}) {
5063             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5064           }
5065         }
5066       }
5067     }
5068   }
5069 }
5070 
5071 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5072     const parser::Name &name) {
5073   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5074           name.source.ToString())}) {
5075     // Unrestricted specific intrinsic function names (e.g., "cos")
5076     // are acceptable as procedure interfaces.
5077     Symbol &symbol{
5078         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5079     symbol.set_details(ProcEntityDetails{});
5080     symbol.set(Symbol::Flag::Function);
5081     if (interface->IsElemental()) {
5082       symbol.attrs().set(Attr::ELEMENTAL);
5083     }
5084     if (interface->IsPure()) {
5085       symbol.attrs().set(Attr::PURE);
5086     }
5087     Resolve(name, symbol);
5088     return true;
5089   } else {
5090     return false;
5091   }
5092 }
5093 
5094 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5095 bool DeclarationVisitor::PassesSharedLocalityChecks(
5096     const parser::Name &name, Symbol &symbol) {
5097   if (!IsVariableName(symbol)) {
5098     SayLocalMustBeVariable(name, symbol); // C1124
5099     return false;
5100   }
5101   if (symbol.owner() == currScope()) { // C1125 and C1126
5102     SayAlreadyDeclared(name, symbol);
5103     return false;
5104   }
5105   return true;
5106 }
5107 
5108 // Checks for locality-specs LOCAL and LOCAL_INIT
5109 bool DeclarationVisitor::PassesLocalityChecks(
5110     const parser::Name &name, Symbol &symbol) {
5111   if (IsAllocatable(symbol)) { // C1128
5112     SayWithDecl(name, symbol,
5113         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5114     return false;
5115   }
5116   if (IsOptional(symbol)) { // C1128
5117     SayWithDecl(name, symbol,
5118         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5119     return false;
5120   }
5121   if (IsIntentIn(symbol)) { // C1128
5122     SayWithDecl(name, symbol,
5123         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5124     return false;
5125   }
5126   if (IsFinalizable(symbol)) { // C1128
5127     SayWithDecl(name, symbol,
5128         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5129     return false;
5130   }
5131   if (evaluate::IsCoarray(symbol)) { // C1128
5132     SayWithDecl(
5133         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5134     return false;
5135   }
5136   if (const DeclTypeSpec * type{symbol.GetType()}) {
5137     if (type->IsPolymorphic() && IsDummy(symbol) &&
5138         !IsPointer(symbol)) { // C1128
5139       SayWithDecl(name, symbol,
5140           "Nonpointer polymorphic argument '%s' not allowed in a "
5141           "locality-spec"_err_en_US);
5142       return false;
5143     }
5144   }
5145   if (IsAssumedSizeArray(symbol)) { // C1128
5146     SayWithDecl(name, symbol,
5147         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5148     return false;
5149   }
5150   if (std::optional<MessageFixedText> msg{
5151           WhyNotModifiable(symbol, currScope())}) {
5152     SayWithReason(name, symbol,
5153         "'%s' may not appear in a locality-spec because it is not "
5154         "definable"_err_en_US,
5155         std::move(*msg));
5156     return false;
5157   }
5158   return PassesSharedLocalityChecks(name, symbol);
5159 }
5160 
5161 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5162     const parser::Name &name) {
5163   Symbol *prev{FindSymbol(name)};
5164   if (!prev) {
5165     // Declare the name as an object in the enclosing scope so that
5166     // the name can't be repurposed there later as something else.
5167     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5168     ConvertToObjectEntity(*prev);
5169     ApplyImplicitRules(*prev);
5170   }
5171   return *prev;
5172 }
5173 
5174 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5175   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5176   if (!PassesLocalityChecks(name, prev)) {
5177     return nullptr;
5178   }
5179   return &MakeHostAssocSymbol(name, prev);
5180 }
5181 
5182 Symbol *DeclarationVisitor::DeclareStatementEntity(
5183     const parser::DoVariable &doVar,
5184     const std::optional<parser::IntegerTypeSpec> &type) {
5185   const parser::Name &name{doVar.thing.thing};
5186   const DeclTypeSpec *declTypeSpec{nullptr};
5187   if (auto *prev{FindSymbol(name)}) {
5188     if (prev->owner() == currScope()) {
5189       SayAlreadyDeclared(name, *prev);
5190       return nullptr;
5191     }
5192     name.symbol = nullptr;
5193     declTypeSpec = prev->GetType();
5194   }
5195   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5196   if (!symbol.has<ObjectEntityDetails>()) {
5197     return nullptr; // error was reported in DeclareEntity
5198   }
5199   if (type) {
5200     declTypeSpec = ProcessTypeSpec(*type);
5201   }
5202   if (declTypeSpec) {
5203     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5204     // declaration of this implied DO loop control variable.
5205     auto restorer{
5206         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5207     SetType(name, *declTypeSpec);
5208   } else {
5209     ApplyImplicitRules(symbol);
5210   }
5211   Symbol *result{Resolve(name, &symbol)};
5212   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5213   return result;
5214 }
5215 
5216 // Set the type of an entity or report an error.
5217 void DeclarationVisitor::SetType(
5218     const parser::Name &name, const DeclTypeSpec &type) {
5219   CHECK(name.symbol);
5220   auto &symbol{*name.symbol};
5221   if (charInfo_.length) { // Declaration has "*length" (R723)
5222     auto length{std::move(*charInfo_.length)};
5223     charInfo_.length.reset();
5224     if (type.category() == DeclTypeSpec::Character) {
5225       auto kind{type.characterTypeSpec().kind()};
5226       // Recurse with correct type.
5227       SetType(name,
5228           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5229       return;
5230     } else { // C753
5231       Say(name,
5232           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5233     }
5234   }
5235   auto *prevType{symbol.GetType()};
5236   if (!prevType) {
5237     symbol.SetType(type);
5238   } else if (symbol.has<UseDetails>()) {
5239     // error recovery case, redeclaration of use-associated name
5240   } else if (HadForwardRef(symbol)) {
5241     // error recovery after use of host-associated name
5242   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5243     SayWithDecl(
5244         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5245     context().SetError(symbol);
5246   } else if (type != *prevType) {
5247     SayWithDecl(name, symbol,
5248         "The type of '%s' has already been implicitly declared"_err_en_US);
5249     context().SetError(symbol);
5250   } else {
5251     symbol.set(Symbol::Flag::Implicit, false);
5252   }
5253 }
5254 
5255 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5256     const parser::Name &name) {
5257   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5258   if (!symbol || symbol->has<UnknownDetails>()) {
5259     if (allowForwardReferenceToDerivedType()) {
5260       if (!symbol) {
5261         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5262         Resolve(name, *symbol);
5263       };
5264       DerivedTypeDetails details;
5265       details.set_isForwardReferenced(true);
5266       symbol->set_details(std::move(details));
5267     } else { // C732
5268       Say(name, "Derived type '%s' not found"_err_en_US);
5269       return std::nullopt;
5270     }
5271   }
5272   if (CheckUseError(name)) {
5273     return std::nullopt;
5274   }
5275   symbol = &symbol->GetUltimate();
5276   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
5277     if (details->derivedType()) {
5278       symbol = details->derivedType();
5279     }
5280   }
5281   if (symbol->has<DerivedTypeDetails>()) {
5282     return DerivedTypeSpec{name.source, *symbol};
5283   } else {
5284     Say(name, "'%s' is not a derived type"_err_en_US);
5285     return std::nullopt;
5286   }
5287 }
5288 
5289 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5290     const parser::Name &typeName, const parser::Name *extendsName) {
5291   if (!extendsName) {
5292     return std::nullopt;
5293   } else if (typeName.source == extendsName->source) {
5294     Say(extendsName->source,
5295         "Derived type '%s' cannot extend itself"_err_en_US);
5296     return std::nullopt;
5297   } else {
5298     return ResolveDerivedType(*extendsName);
5299   }
5300 }
5301 
5302 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5303   // The symbol is checked later by CheckExplicitInterface() and
5304   // CheckBindings().  It can be a forward reference.
5305   if (!NameIsKnownOrIntrinsic(name)) {
5306     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5307     Resolve(name, symbol);
5308   }
5309   return name.symbol;
5310 }
5311 
5312 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5313   if (const Symbol * symbol{name.symbol}) {
5314     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5315       Say(name,
5316           "'%s' must be an abstract interface or a procedure with "
5317           "an explicit interface"_err_en_US,
5318           symbol->name());
5319     }
5320   }
5321 }
5322 
5323 // Create a symbol for a type parameter, component, or procedure binding in
5324 // the current derived type scope. Return false on error.
5325 Symbol *DeclarationVisitor::MakeTypeSymbol(
5326     const parser::Name &name, Details &&details) {
5327   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5328 }
5329 Symbol *DeclarationVisitor::MakeTypeSymbol(
5330     const SourceName &name, Details &&details) {
5331   Scope &derivedType{currScope()};
5332   CHECK(derivedType.IsDerivedType());
5333   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5334     Say2(name,
5335         "Type parameter, component, or procedure binding '%s'"
5336         " already defined in this type"_err_en_US,
5337         *symbol, "Previous definition of '%s'"_en_US);
5338     return nullptr;
5339   } else {
5340     auto attrs{GetAttrs()};
5341     // Apply binding-private-stmt if present and this is a procedure binding
5342     if (derivedTypeInfo_.privateBindings &&
5343         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5344         std::holds_alternative<ProcBindingDetails>(details)) {
5345       attrs.set(Attr::PRIVATE);
5346     }
5347     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5348     if (result.has<TypeParamDetails>()) {
5349       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5350     }
5351     return &result;
5352   }
5353 }
5354 
5355 // Return true if it is ok to declare this component in the current scope.
5356 // Otherwise, emit an error and return false.
5357 bool DeclarationVisitor::OkToAddComponent(
5358     const parser::Name &name, const Symbol *extends) {
5359   for (const Scope *scope{&currScope()}; scope;) {
5360     CHECK(scope->IsDerivedType());
5361     if (auto *prev{FindInScope(*scope, name)}) {
5362       if (!context().HasError(*prev)) {
5363         auto msg{""_en_US};
5364         if (extends) {
5365           msg = "Type cannot be extended as it has a component named"
5366                 " '%s'"_err_en_US;
5367         } else if (prev->test(Symbol::Flag::ParentComp)) {
5368           msg = "'%s' is a parent type of this type and so cannot be"
5369                 " a component"_err_en_US;
5370         } else if (scope != &currScope()) {
5371           msg = "Component '%s' is already declared in a parent of this"
5372                 " derived type"_err_en_US;
5373         } else {
5374           msg = "Component '%s' is already declared in this"
5375                 " derived type"_err_en_US;
5376         }
5377         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5378       }
5379       return false;
5380     }
5381     if (scope == &currScope() && extends) {
5382       // The parent component has not yet been added to the scope.
5383       scope = extends->scope();
5384     } else {
5385       scope = scope->GetDerivedTypeParent();
5386     }
5387   }
5388   return true;
5389 }
5390 
5391 ParamValue DeclarationVisitor::GetParamValue(
5392     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5393   return std::visit(
5394       common::visitors{
5395           [=](const parser::ScalarIntExpr &x) { // C704
5396             return ParamValue{EvaluateIntExpr(x), attr};
5397           },
5398           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5399           [=](const parser::TypeParamValue::Deferred &) {
5400             return ParamValue::Deferred(attr);
5401           },
5402       },
5403       x.u);
5404 }
5405 
5406 // ConstructVisitor implementation
5407 
5408 void ConstructVisitor::ResolveIndexName(
5409     const parser::ConcurrentControl &control) {
5410   const parser::Name &name{std::get<parser::Name>(control.t)};
5411   auto *prev{FindSymbol(name)};
5412   if (prev) {
5413     if (prev->owner().kind() == Scope::Kind::Forall ||
5414         prev->owner() == currScope()) {
5415       SayAlreadyDeclared(name, *prev);
5416       return;
5417     }
5418     name.symbol = nullptr;
5419   }
5420   auto &symbol{DeclareObjectEntity(name)};
5421   if (symbol.GetType()) {
5422     // type came from explicit type-spec
5423   } else if (!prev) {
5424     ApplyImplicitRules(symbol);
5425   } else {
5426     const Symbol &prevRoot{ResolveAssociations(*prev)};
5427     // prev could be host- use- or construct-associated with another symbol
5428     if (!prevRoot.has<ObjectEntityDetails>() &&
5429         !prevRoot.has<EntityDetails>()) {
5430       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5431           *prev, "Previous declaration of '%s'"_en_US);
5432       context().SetError(symbol);
5433       return;
5434     } else {
5435       if (const auto *type{prevRoot.GetType()}) {
5436         symbol.SetType(*type);
5437       }
5438       if (prevRoot.IsObjectArray()) {
5439         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5440         return;
5441       }
5442     }
5443   }
5444   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5445 }
5446 
5447 // We need to make sure that all of the index-names get declared before the
5448 // expressions in the loop control are evaluated so that references to the
5449 // index-names in the expressions are correctly detected.
5450 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5451   BeginDeclTypeSpec();
5452   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5453   const auto &controls{
5454       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5455   for (const auto &control : controls) {
5456     ResolveIndexName(control);
5457   }
5458   Walk(controls);
5459   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5460   EndDeclTypeSpec();
5461   return false;
5462 }
5463 
5464 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5465   for (auto &name : x.v) {
5466     if (auto *symbol{DeclareLocalEntity(name)}) {
5467       symbol->set(Symbol::Flag::LocalityLocal);
5468     }
5469   }
5470   return false;
5471 }
5472 
5473 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5474   for (auto &name : x.v) {
5475     if (auto *symbol{DeclareLocalEntity(name)}) {
5476       symbol->set(Symbol::Flag::LocalityLocalInit);
5477     }
5478   }
5479   return false;
5480 }
5481 
5482 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5483   for (const auto &name : x.v) {
5484     if (!FindSymbol(name)) {
5485       Say(name, "Variable '%s' with SHARED locality implicitly declared"_en_US);
5486     }
5487     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5488     if (PassesSharedLocalityChecks(name, prev)) {
5489       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5490     }
5491   }
5492   return false;
5493 }
5494 
5495 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5496   ProcessTypeSpec(x.type);
5497   Walk(x.values);
5498   return false;
5499 }
5500 
5501 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5502 // enclosing ac-implied-do
5503 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5504   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5505   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5506   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5507   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5508   // F'2018 has the scope of the implied DO variable covering the entire
5509   // implied DO production (19.4(5)), which seems wrong in cases where the name
5510   // of the implied DO variable appears in one of the bound expressions. Thus
5511   // this extension, which shrinks the scope of the variable to exclude the
5512   // expressions in the bounds.
5513   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5514   Walk(bounds.lower);
5515   Walk(bounds.upper);
5516   Walk(bounds.step);
5517   EndCheckOnIndexUseInOwnBounds(restore);
5518   PushScope(Scope::Kind::ImpliedDos, nullptr);
5519   DeclareStatementEntity(bounds.name, type);
5520   Walk(values);
5521   PopScope();
5522   return false;
5523 }
5524 
5525 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5526   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5527   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5528   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5529   // See comment in Pre(AcImpliedDo) above.
5530   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5531   Walk(bounds.lower);
5532   Walk(bounds.upper);
5533   Walk(bounds.step);
5534   EndCheckOnIndexUseInOwnBounds(restore);
5535   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5536   if (pushScope) {
5537     PushScope(Scope::Kind::ImpliedDos, nullptr);
5538   }
5539   DeclareStatementEntity(bounds.name, type);
5540   Walk(objects);
5541   if (pushScope) {
5542     PopScope();
5543   }
5544   return false;
5545 }
5546 
5547 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5548 // statement so that the predicate IsInitialized() will be true
5549 // during semantic analysis before the symbol's initializer is constructed.
5550 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5551   std::visit(
5552       common::visitors{
5553           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5554             Walk(y.thing.value());
5555             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5556             if (first.symbol) {
5557               first.symbol->set(Symbol::Flag::InDataStmt);
5558             }
5559           },
5560           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5561       },
5562       x.u);
5563   return false;
5564 }
5565 
5566 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5567   std::visit(common::visitors{
5568                  [&](const Indirection<parser::Variable> &y) {
5569                    Walk(y.value());
5570                    const parser::Name &first{parser::GetFirstName(y.value())};
5571                    if (first.symbol) {
5572                      first.symbol->set(Symbol::Flag::InDataStmt);
5573                    }
5574                  },
5575                  [&](const parser::DataImpliedDo &y) {
5576                    PushScope(Scope::Kind::ImpliedDos, nullptr);
5577                    Walk(y);
5578                    PopScope();
5579                  },
5580              },
5581       x.u);
5582   return false;
5583 }
5584 
5585 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5586   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5587   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5588   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5589     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5590       if (const Symbol * symbol{FindSymbol(*name)}) {
5591         const Symbol &ultimate{symbol->GetUltimate()};
5592         if (ultimate.has<DerivedTypeDetails>()) {
5593           mutableData.u = elem->ConvertToStructureConstructor(
5594               DerivedTypeSpec{name->source, ultimate});
5595         }
5596       }
5597     }
5598   }
5599   return true;
5600 }
5601 
5602 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5603   if (x.IsDoConcurrent()) {
5604     PushScope(Scope::Kind::Block, nullptr);
5605   }
5606   return true;
5607 }
5608 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5609   if (x.IsDoConcurrent()) {
5610     PopScope();
5611   }
5612 }
5613 
5614 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5615   PushScope(Scope::Kind::Forall, nullptr);
5616   return true;
5617 }
5618 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5619 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5620   PushScope(Scope::Kind::Forall, nullptr);
5621   return true;
5622 }
5623 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5624 
5625 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5626   CheckDef(x.v);
5627   PushScope(Scope::Kind::Block, nullptr);
5628   return false;
5629 }
5630 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5631   PopScope();
5632   CheckRef(x.v);
5633   return false;
5634 }
5635 
5636 void ConstructVisitor::Post(const parser::Selector &x) {
5637   GetCurrentAssociation().selector = ResolveSelector(x);
5638 }
5639 
5640 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
5641   CheckDef(x.t);
5642   PushScope(Scope::Kind::Block, nullptr);
5643   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
5644   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
5645     SetCurrentAssociation(nthLastAssoc);
5646     if (auto *symbol{MakeAssocEntity()}) {
5647       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
5648         Say("Selector must not be a coindexed object"_err_en_US);
5649       }
5650       SetTypeFromAssociation(*symbol);
5651       SetAttrsFromAssociation(*symbol);
5652     }
5653   }
5654   PopAssociation(assocCount);
5655 }
5656 
5657 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5658   PopScope();
5659   CheckRef(x.v);
5660 }
5661 
5662 bool ConstructVisitor::Pre(const parser::Association &x) {
5663   PushAssociation();
5664   const auto &name{std::get<parser::Name>(x.t)};
5665   GetCurrentAssociation().name = &name;
5666   return true;
5667 }
5668 
5669 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5670   CheckDef(x.t);
5671   PushScope(Scope::Kind::Block, nullptr);
5672   PushAssociation();
5673   return true;
5674 }
5675 
5676 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5677   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5678   const auto &name{std::get<parser::Name>(decl.t)};
5679   if (auto *symbol{FindInScope(name)}) {
5680     const auto &selector{std::get<parser::Selector>(x.t)};
5681     if (auto sel{ResolveSelector(selector)}) {
5682       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5683       if (!whole || whole->Corank() == 0) {
5684         Say(sel.source, // C1116
5685             "Selector in coarray association must name a coarray"_err_en_US);
5686       } else if (auto dynType{sel.expr->GetType()}) {
5687         if (!symbol->GetType()) {
5688           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5689         }
5690       }
5691     }
5692   }
5693 }
5694 
5695 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5696   PopAssociation();
5697   PopScope();
5698   CheckRef(x.t);
5699 }
5700 
5701 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5702   PushAssociation();
5703   return true;
5704 }
5705 
5706 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5707   PopAssociation();
5708 }
5709 
5710 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
5711   auto &association{GetCurrentAssociation()};
5712   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5713     // This isn't a name in the current scope, it is in each TypeGuardStmt
5714     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
5715     association.name = &*name;
5716     auto exprType{association.selector.expr->GetType()};
5717     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
5718       Say("Selector must not be a coindexed object"_err_en_US);
5719     }
5720     if (exprType && !exprType->IsPolymorphic()) { // C1159
5721       Say(association.selector.source,
5722           "Selector '%s' in SELECT TYPE statement must be "
5723           "polymorphic"_err_en_US);
5724     }
5725   } else {
5726     if (const Symbol *
5727         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5728       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
5729       if (!IsVariableName(*whole)) {
5730         Say(association.selector.source, // C901
5731             "Selector is not a variable"_err_en_US);
5732         association = {};
5733       }
5734       if (const DeclTypeSpec * type{whole->GetType()}) {
5735         if (!type->IsPolymorphic()) { // C1159
5736           Say(association.selector.source,
5737               "Selector '%s' in SELECT TYPE statement must be "
5738               "polymorphic"_err_en_US);
5739         }
5740       }
5741     } else {
5742       Say(association.selector.source, // C1157
5743           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
5744       association = {};
5745     }
5746   }
5747 }
5748 
5749 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
5750   auto &association{GetCurrentAssociation()};
5751   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5752     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
5753     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
5754     association.name = &*name;
5755   }
5756 }
5757 
5758 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
5759   PushScope(Scope::Kind::Block, nullptr);
5760   return true;
5761 }
5762 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
5763   PopScope();
5764 }
5765 
5766 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
5767   PushScope(Scope::Kind::Block, nullptr);
5768   return true;
5769 }
5770 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
5771   PopScope();
5772 }
5773 
5774 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
5775   if (auto *symbol{MakeAssocEntity()}) {
5776     if (std::holds_alternative<parser::Default>(x.u)) {
5777       SetTypeFromAssociation(*symbol);
5778     } else if (const auto *type{GetDeclTypeSpec()}) {
5779       symbol->SetType(*type);
5780     }
5781     SetAttrsFromAssociation(*symbol);
5782   }
5783 }
5784 
5785 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
5786   if (auto *symbol{MakeAssocEntity()}) {
5787     SetTypeFromAssociation(*symbol);
5788     SetAttrsFromAssociation(*symbol);
5789     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
5790       if (auto val{EvaluateInt64(context(), *init)}) {
5791         auto &details{symbol->get<AssocEntityDetails>()};
5792         details.set_rank(*val);
5793       }
5794     }
5795   }
5796 }
5797 
5798 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
5799   PushAssociation();
5800   return true;
5801 }
5802 
5803 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
5804   PopAssociation();
5805 }
5806 
5807 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
5808   if (x) {
5809     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
5810   }
5811   return true;
5812 }
5813 
5814 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
5815   if (x) {
5816     // Just add an occurrence of this name; checking is done in ValidateLabels
5817     FindSymbol(*x);
5818   }
5819 }
5820 
5821 // Make a symbol for the associating entity of the current association.
5822 Symbol *ConstructVisitor::MakeAssocEntity() {
5823   Symbol *symbol{nullptr};
5824   auto &association{GetCurrentAssociation()};
5825   if (association.name) {
5826     symbol = &MakeSymbol(*association.name, UnknownDetails{});
5827     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
5828       Say(*association.name, // C1102
5829           "The associate name '%s' is already used in this associate statement"_err_en_US);
5830       return nullptr;
5831     }
5832   } else if (const Symbol *
5833       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5834     symbol = &MakeSymbol(whole->name());
5835   } else {
5836     return nullptr;
5837   }
5838   if (auto &expr{association.selector.expr}) {
5839     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
5840   } else {
5841     symbol->set_details(AssocEntityDetails{});
5842   }
5843   return symbol;
5844 }
5845 
5846 // Set the type of symbol based on the current association selector.
5847 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
5848   auto &details{symbol.get<AssocEntityDetails>()};
5849   const MaybeExpr *pexpr{&details.expr()};
5850   if (!*pexpr) {
5851     pexpr = &GetCurrentAssociation().selector.expr;
5852   }
5853   if (*pexpr) {
5854     const SomeExpr &expr{**pexpr};
5855     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
5856       if (const auto *charExpr{
5857               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
5858                   expr)}) {
5859         symbol.SetType(ToDeclTypeSpec(std::move(*type),
5860             FoldExpr(
5861                 std::visit([](const auto &kindChar) { return kindChar.LEN(); },
5862                     charExpr->u))));
5863       } else {
5864         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
5865       }
5866     } else {
5867       // BOZ literals, procedure designators, &c. are not acceptable
5868       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
5869     }
5870   }
5871 }
5872 
5873 // If current selector is a variable, set some of its attributes on symbol.
5874 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
5875   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
5876   symbol.attrs() |= attrs &
5877       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
5878   if (attrs.test(Attr::POINTER)) {
5879     symbol.attrs().set(Attr::TARGET);
5880   }
5881 }
5882 
5883 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
5884     const parser::Selector &x) {
5885   return std::visit(common::visitors{
5886                         [&](const parser::Expr &expr) {
5887                           return Selector{expr.source, EvaluateExpr(x)};
5888                         },
5889                         [&](const parser::Variable &var) {
5890                           return Selector{var.GetSource(), EvaluateExpr(x)};
5891                         },
5892                     },
5893       x.u);
5894 }
5895 
5896 // Set the current association to the nth to the last association on the
5897 // association stack.  The top of the stack is at n = 1.  This allows access
5898 // to the interior of a list of associations at the top of the stack.
5899 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
5900   CHECK(n > 0 && n <= associationStack_.size());
5901   currentAssociation_ = &associationStack_[associationStack_.size() - n];
5902 }
5903 
5904 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
5905   CHECK(currentAssociation_);
5906   return *currentAssociation_;
5907 }
5908 
5909 void ConstructVisitor::PushAssociation() {
5910   associationStack_.emplace_back(Association{});
5911   currentAssociation_ = &associationStack_.back();
5912 }
5913 
5914 void ConstructVisitor::PopAssociation(std::size_t count) {
5915   CHECK(count > 0 && count <= associationStack_.size());
5916   associationStack_.resize(associationStack_.size() - count);
5917   currentAssociation_ =
5918       associationStack_.empty() ? nullptr : &associationStack_.back();
5919 }
5920 
5921 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5922     evaluate::DynamicType &&type) {
5923   switch (type.category()) {
5924     SWITCH_COVERS_ALL_CASES
5925   case common::TypeCategory::Integer:
5926   case common::TypeCategory::Real:
5927   case common::TypeCategory::Complex:
5928     return context().MakeNumericType(type.category(), type.kind());
5929   case common::TypeCategory::Logical:
5930     return context().MakeLogicalType(type.kind());
5931   case common::TypeCategory::Derived:
5932     if (type.IsAssumedType()) {
5933       return currScope().MakeTypeStarType();
5934     } else if (type.IsUnlimitedPolymorphic()) {
5935       return currScope().MakeClassStarType();
5936     } else {
5937       return currScope().MakeDerivedType(
5938           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
5939                                : DeclTypeSpec::TypeDerived,
5940           common::Clone(type.GetDerivedTypeSpec())
5941 
5942       );
5943     }
5944   case common::TypeCategory::Character:
5945     CRASH_NO_CASE;
5946   }
5947 }
5948 
5949 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5950     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
5951   CHECK(type.category() == common::TypeCategory::Character);
5952   if (length) {
5953     return currScope().MakeCharacterType(
5954         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
5955         KindExpr{type.kind()});
5956   } else {
5957     return currScope().MakeCharacterType(
5958         ParamValue::Deferred(common::TypeParamAttr::Len),
5959         KindExpr{type.kind()});
5960   }
5961 }
5962 
5963 // ResolveNamesVisitor implementation
5964 
5965 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
5966   HandleCall(Symbol::Flag::Function, x.v);
5967   return false;
5968 }
5969 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
5970   HandleCall(Symbol::Flag::Subroutine, x.v);
5971   return false;
5972 }
5973 
5974 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
5975   auto &scope{currScope()};
5976   // Check C896 and C899: where IMPORT statements are allowed
5977   switch (scope.kind()) {
5978   case Scope::Kind::Module:
5979     if (scope.IsModule()) {
5980       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
5981       return false;
5982     } else if (x.kind == common::ImportKind::None) {
5983       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
5984       return false;
5985     }
5986     break;
5987   case Scope::Kind::MainProgram:
5988     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
5989     return false;
5990   case Scope::Kind::Subprogram:
5991     if (scope.parent().IsGlobal()) {
5992       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
5993       return false;
5994     }
5995     break;
5996   case Scope::Kind::BlockData: // C1415 (in part)
5997     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
5998     return false;
5999   default:;
6000   }
6001   if (auto error{scope.SetImportKind(x.kind)}) {
6002     Say(std::move(*error));
6003   }
6004   for (auto &name : x.names) {
6005     if (FindSymbol(scope.parent(), name)) {
6006       scope.add_importName(name.source);
6007     } else {
6008       Say(name, "'%s' not found in host scope"_err_en_US);
6009     }
6010   }
6011   prevImportStmt_ = currStmtSource();
6012   return false;
6013 }
6014 
6015 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6016     const parser::StructureComponent &x) {
6017   return FindComponent(ResolveDataRef(x.base), x.component);
6018 }
6019 
6020 const parser::Name *DeclarationVisitor::ResolveDesignator(
6021     const parser::Designator &x) {
6022   return std::visit(
6023       common::visitors{
6024           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6025           [&](const parser::Substring &x) {
6026             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6027           },
6028       },
6029       x.u);
6030 }
6031 
6032 const parser::Name *DeclarationVisitor::ResolveDataRef(
6033     const parser::DataRef &x) {
6034   return std::visit(
6035       common::visitors{
6036           [=](const parser::Name &y) { return ResolveName(y); },
6037           [=](const Indirection<parser::StructureComponent> &y) {
6038             return ResolveStructureComponent(y.value());
6039           },
6040           [&](const Indirection<parser::ArrayElement> &y) {
6041             Walk(y.value().subscripts);
6042             const parser::Name *name{ResolveDataRef(y.value().base)};
6043             if (name && name->symbol) {
6044               if (!IsProcedure(*name->symbol)) {
6045                 ConvertToObjectEntity(*name->symbol);
6046               } else if (!context().HasError(*name->symbol)) {
6047                 SayWithDecl(*name, *name->symbol,
6048                     "Cannot reference function '%s' as data"_err_en_US);
6049               }
6050             }
6051             return name;
6052           },
6053           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6054             Walk(y.value().imageSelector);
6055             return ResolveDataRef(y.value().base);
6056           },
6057       },
6058       x.u);
6059 }
6060 
6061 // If implicit types are allowed, ensure name is in the symbol table.
6062 // Otherwise, report an error if it hasn't been declared.
6063 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6064   FindSymbol(name);
6065   if (CheckForHostAssociatedImplicit(name)) {
6066     NotePossibleBadForwardRef(name);
6067     return &name;
6068   }
6069   if (Symbol * symbol{name.symbol}) {
6070     if (CheckUseError(name)) {
6071       return nullptr; // reported an error
6072     }
6073     NotePossibleBadForwardRef(name);
6074     symbol->set(Symbol::Flag::ImplicitOrError, false);
6075     if (IsUplevelReference(*symbol)) {
6076       MakeHostAssocSymbol(name, *symbol);
6077     } else if (IsDummy(*symbol) ||
6078         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6079       ConvertToObjectEntity(*symbol);
6080       ApplyImplicitRules(*symbol);
6081     }
6082     if (checkIndexUseInOwnBounds_ &&
6083         *checkIndexUseInOwnBounds_ == name.source) {
6084       Say(name,
6085           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_en_US,
6086           name.source);
6087     }
6088     return &name;
6089   }
6090   if (isImplicitNoneType()) {
6091     Say(name, "No explicit type declared for '%s'"_err_en_US);
6092     return nullptr;
6093   }
6094   // Create the symbol then ensure it is accessible
6095   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6096     Say(name,
6097         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6098         name.source);
6099   }
6100   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6101   auto *symbol{FindSymbol(name)};
6102   if (!symbol) {
6103     Say(name,
6104         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6105     return nullptr;
6106   }
6107   ConvertToObjectEntity(*symbol);
6108   ApplyImplicitRules(*symbol);
6109   NotePossibleBadForwardRef(name);
6110   return &name;
6111 }
6112 
6113 // A specification expression may refer to a symbol in the host procedure that
6114 // is implicitly typed. Because specification parts are processed before
6115 // execution parts, this may be the first time we see the symbol. It can't be a
6116 // local in the current scope (because it's in a specification expression) so
6117 // either it is implicitly declared in the host procedure or it is an error.
6118 // We create a symbol in the host assuming it is the former; if that proves to
6119 // be wrong we report an error later in CheckDeclarations().
6120 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6121     const parser::Name &name) {
6122   if (inExecutionPart_) {
6123     return false;
6124   }
6125   if (name.symbol) {
6126     ApplyImplicitRules(*name.symbol, true);
6127   }
6128   Symbol *hostSymbol;
6129   Scope *host{GetHostProcedure()};
6130   if (!host || isImplicitNoneType(*host)) {
6131     return false;
6132   }
6133   if (!name.symbol) {
6134     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6135     ConvertToObjectEntity(*hostSymbol);
6136     ApplyImplicitRules(*hostSymbol);
6137     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6138   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6139     hostSymbol = name.symbol;
6140   } else {
6141     return false;
6142   }
6143   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6144   if (isImplicitNoneType()) {
6145     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6146   } else {
6147     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6148   }
6149   return true;
6150 }
6151 
6152 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6153   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6154   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6155     return false;
6156   } else {
6157     Scope::Kind kind{symbolUnit.kind()};
6158     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6159   }
6160 }
6161 
6162 // base is a part-ref of a derived type; find the named component in its type.
6163 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6164 // COMPLEX component references (%re, %im).
6165 const parser::Name *DeclarationVisitor::FindComponent(
6166     const parser::Name *base, const parser::Name &component) {
6167   if (!base || !base->symbol) {
6168     return nullptr;
6169   }
6170   auto &symbol{base->symbol->GetUltimate()};
6171   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6172     SayWithDecl(*base, symbol,
6173         "'%s' is an invalid base for a component reference"_err_en_US);
6174     return nullptr;
6175   }
6176   auto *type{symbol.GetType()};
6177   if (!type) {
6178     return nullptr; // should have already reported error
6179   }
6180   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6181     auto name{component.ToString()};
6182     auto category{intrinsic->category()};
6183     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6184     if (name == "kind") {
6185       miscKind = MiscDetails::Kind::KindParamInquiry;
6186     } else if (category == TypeCategory::Character) {
6187       if (name == "len") {
6188         miscKind = MiscDetails::Kind::LenParamInquiry;
6189       }
6190     } else if (category == TypeCategory::Complex) {
6191       if (name == "re") {
6192         miscKind = MiscDetails::Kind::ComplexPartRe;
6193       } else if (name == "im") {
6194         miscKind = MiscDetails::Kind::ComplexPartIm;
6195       }
6196     }
6197     if (miscKind != MiscDetails::Kind::None) {
6198       MakePlaceholder(component, miscKind);
6199       return nullptr;
6200     }
6201   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6202     if (const Scope * scope{derived->scope()}) {
6203       if (Resolve(component, scope->FindComponent(component.source))) {
6204         if (auto msg{
6205                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6206           context().Say(component.source, *msg);
6207         }
6208         return &component;
6209       } else {
6210         SayDerivedType(component.source,
6211             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6212       }
6213     }
6214     return nullptr;
6215   }
6216   if (symbol.test(Symbol::Flag::Implicit)) {
6217     Say(*base,
6218         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6219   } else {
6220     SayWithDecl(
6221         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6222   }
6223   return nullptr;
6224 }
6225 
6226 void DeclarationVisitor::Initialization(const parser::Name &name,
6227     const parser::Initialization &init, bool inComponentDecl) {
6228   // Traversal of the initializer was deferred to here so that the
6229   // symbol being declared can be available for use in the expression, e.g.:
6230   //   real, parameter :: x = tiny(x)
6231   if (!name.symbol) {
6232     return;
6233   }
6234   Symbol &ultimate{name.symbol->GetUltimate()};
6235   if (IsAllocatable(ultimate)) {
6236     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6237     return;
6238   }
6239   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6240     // TODO: check C762 - all bounds and type parameters of component
6241     // are colons or constant expressions if component is initialized
6242     std::visit(
6243         common::visitors{
6244             [&](const parser::ConstantExpr &expr) {
6245               NonPointerInitialization(name, expr);
6246             },
6247             [&](const parser::NullInit &null) {
6248               Walk(null);
6249               if (auto nullInit{EvaluateExpr(null)}) {
6250                 if (!evaluate::IsNullPointer(*nullInit)) {
6251                   Say(name,
6252                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6253                 } else if (IsPointer(ultimate)) {
6254                   object->set_init(std::move(*nullInit));
6255                 } else {
6256                   Say(name,
6257                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6258                 }
6259               }
6260             },
6261             [&](const parser::InitialDataTarget &) {
6262               // Defer analysis to the end of the specification part
6263               // so that forward references and attribute checks like SAVE
6264               // work better.
6265               ultimate.set(Symbol::Flag::InDataStmt);
6266             },
6267             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
6268               // Handled later in data-to-inits conversion
6269               ultimate.set(Symbol::Flag::InDataStmt);
6270             },
6271         },
6272         init.u);
6273   }
6274 }
6275 
6276 void DeclarationVisitor::PointerInitialization(
6277     const parser::Name &name, const parser::InitialDataTarget &target) {
6278   if (name.symbol) {
6279     Symbol &ultimate{name.symbol->GetUltimate()};
6280     if (!context().HasError(ultimate)) {
6281       if (IsPointer(ultimate)) {
6282         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6283           CHECK(!details->init());
6284           Walk(target);
6285           if (MaybeExpr expr{EvaluateExpr(target)}) {
6286             // Validation is done in declaration checking.
6287             details->set_init(std::move(*expr));
6288           }
6289         }
6290       } else {
6291         Say(name,
6292             "'%s' is not a pointer but is initialized like one"_err_en_US);
6293         context().SetError(ultimate);
6294       }
6295     }
6296   }
6297 }
6298 void DeclarationVisitor::PointerInitialization(
6299     const parser::Name &name, const parser::ProcPointerInit &target) {
6300   if (name.symbol) {
6301     Symbol &ultimate{name.symbol->GetUltimate()};
6302     if (!context().HasError(ultimate)) {
6303       if (IsProcedurePointer(ultimate)) {
6304         auto &details{ultimate.get<ProcEntityDetails>()};
6305         CHECK(!details.init());
6306         Walk(target);
6307         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6308           if (targetName->symbol) {
6309             // Validation is done in declaration checking.
6310             details.set_init(*targetName->symbol);
6311           }
6312         } else {
6313           details.set_init(nullptr); // explicit NULL()
6314         }
6315       } else {
6316         Say(name,
6317             "'%s' is not a procedure pointer but is initialized "
6318             "like one"_err_en_US);
6319         context().SetError(ultimate);
6320       }
6321     }
6322   }
6323 }
6324 
6325 void DeclarationVisitor::NonPointerInitialization(
6326     const parser::Name &name, const parser::ConstantExpr &expr) {
6327   if (name.symbol) {
6328     Symbol &ultimate{name.symbol->GetUltimate()};
6329     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6330       if (IsPointer(ultimate)) {
6331         Say(name,
6332             "'%s' is a pointer but is not initialized like one"_err_en_US);
6333       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6334         CHECK(!details->init());
6335         Walk(expr);
6336         if (ultimate.owner().IsParameterizedDerivedType()) {
6337           // Can't convert to type of component, which might not yet
6338           // be known; that's done later during PDT instantiation.
6339           if (MaybeExpr value{EvaluateExpr(expr)}) {
6340             details->set_init(std::move(*value));
6341           }
6342         } else if (MaybeExpr folded{EvaluateNonPointerInitializer(
6343                        ultimate, expr, expr.thing.value().source)}) {
6344           details->set_init(std::move(*folded));
6345         }
6346       }
6347     }
6348   }
6349 }
6350 
6351 void ResolveNamesVisitor::HandleCall(
6352     Symbol::Flag procFlag, const parser::Call &call) {
6353   std::visit(
6354       common::visitors{
6355           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6356           [&](const parser::ProcComponentRef &x) { Walk(x); },
6357       },
6358       std::get<parser::ProcedureDesignator>(call.t).u);
6359   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6360 }
6361 
6362 void ResolveNamesVisitor::HandleProcedureName(
6363     Symbol::Flag flag, const parser::Name &name) {
6364   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6365   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6366   if (!symbol) {
6367     if (IsIntrinsic(name.source, flag)) {
6368       symbol =
6369           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6370     } else {
6371       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6372     }
6373     Resolve(name, *symbol);
6374     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6375       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6376         MakeExternal(*symbol);
6377       }
6378     }
6379     ConvertToProcEntity(*symbol);
6380     SetProcFlag(name, *symbol, flag);
6381   } else if (CheckUseError(name)) {
6382     // error was reported
6383   } else {
6384     auto &nonUltimateSymbol = *symbol;
6385     symbol = &Resolve(name, symbol)->GetUltimate();
6386     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6387     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6388         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6389       AcquireIntrinsicProcedureFlags(*symbol);
6390     }
6391     if (!SetProcFlag(name, *symbol, flag)) {
6392       return; // reported error
6393     }
6394     CheckImplicitNoneExternal(name.source, *symbol);
6395     if (symbol->has<SubprogramDetails>() &&
6396         symbol->attrs().test(Attr::ABSTRACT)) {
6397       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6398     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6399         symbol->has<AssocEntityDetails>()) {
6400       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6401       // here as procedure-designators because this means the related
6402       // FunctionReference are mis-parsed structure constructors or array
6403       // references that will be fixed later when analyzing expressions.
6404     } else if (symbol->has<ObjectEntityDetails>()) {
6405       // Symbols with ObjectEntityDetails are also accepted because this can be
6406       // a mis-parsed array references that will be fixed later. Ensure that if
6407       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6408       // is created for the current scope.
6409       // Operate on non ultimate symbol so that HostAssocDetails are also
6410       // created for symbols used associated in the host procedure.
6411       if (IsUplevelReference(nonUltimateSymbol)) {
6412         MakeHostAssocSymbol(name, nonUltimateSymbol);
6413       }
6414     } else if (symbol->test(Symbol::Flag::Implicit)) {
6415       Say(name,
6416           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6417     } else {
6418       SayWithDecl(name, *symbol,
6419           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6420     }
6421   }
6422 }
6423 
6424 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6425     const SourceName &name, const Symbol &symbol) {
6426   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6427       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6428     Say(name,
6429         "'%s' is an external procedure without the EXTERNAL"
6430         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6431     return false;
6432   }
6433   return true;
6434 }
6435 
6436 // Variant of HandleProcedureName() for use while skimming the executable
6437 // part of a subprogram to catch calls to dummy procedures that are part
6438 // of the subprogram's interface, and to mark as procedures any symbols
6439 // that might otherwise have been miscategorized as objects.
6440 void ResolveNamesVisitor::NoteExecutablePartCall(
6441     Symbol::Flag flag, const parser::Call &call) {
6442   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6443   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6444     // Subtlety: The symbol pointers in the parse tree are not set, because
6445     // they might end up resolving elsewhere (e.g., construct entities in
6446     // SELECT TYPE).
6447     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6448       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6449               ? Symbol::Flag::Function
6450               : Symbol::Flag::Subroutine};
6451       if (!symbol->test(other)) {
6452         ConvertToProcEntity(*symbol);
6453         if (symbol->has<ProcEntityDetails>()) {
6454           symbol->set(flag);
6455           if (IsDummy(*symbol)) {
6456             symbol->attrs().set(Attr::EXTERNAL);
6457           }
6458           ApplyImplicitRules(*symbol);
6459         }
6460       }
6461     }
6462   }
6463 }
6464 
6465 // Check and set the Function or Subroutine flag on symbol; false on error.
6466 bool ResolveNamesVisitor::SetProcFlag(
6467     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6468   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6469     SayWithDecl(
6470         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6471     return false;
6472   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6473       flag == Symbol::Flag::Function) {
6474     SayWithDecl(
6475         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6476     return false;
6477   } else if (symbol.has<ProcEntityDetails>()) {
6478     symbol.set(flag); // in case it hasn't been set yet
6479     if (flag == Symbol::Flag::Function) {
6480       ApplyImplicitRules(symbol);
6481     }
6482     if (symbol.attrs().test(Attr::INTRINSIC)) {
6483       AcquireIntrinsicProcedureFlags(symbol);
6484     }
6485   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6486     SayWithDecl(
6487         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6488   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6489     AcquireIntrinsicProcedureFlags(symbol);
6490   }
6491   return true;
6492 }
6493 
6494 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6495   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6496   if (!currScope().IsModule()) { // C869
6497     Say(currStmtSource().value(),
6498         "%s statement may only appear in the specification part of a module"_err_en_US,
6499         EnumToString(accessAttr));
6500     return false;
6501   }
6502   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6503   if (accessIds.empty()) {
6504     if (prevAccessStmt_) { // C869
6505       Say("The default accessibility of this module has already been declared"_err_en_US)
6506           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6507     }
6508     prevAccessStmt_ = currStmtSource();
6509     defaultAccess_ = accessAttr;
6510   } else {
6511     for (const auto &accessId : accessIds) {
6512       std::visit(
6513           common::visitors{
6514               [=](const parser::Name &y) {
6515                 Resolve(y, SetAccess(y.source, accessAttr));
6516               },
6517               [=](const Indirection<parser::GenericSpec> &y) {
6518                 auto info{GenericSpecInfo{y.value()}};
6519                 const auto &symbolName{info.symbolName()};
6520                 if (auto *symbol{FindInScope(symbolName)}) {
6521                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6522                 } else if (info.kind().IsName()) {
6523                   info.Resolve(&SetAccess(symbolName, accessAttr));
6524                 } else {
6525                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6526                 }
6527               },
6528           },
6529           accessId.u);
6530     }
6531   }
6532   return false;
6533 }
6534 
6535 // Set the access specification for this symbol.
6536 Symbol &ModuleVisitor::SetAccess(
6537     const SourceName &name, Attr attr, Symbol *symbol) {
6538   if (!symbol) {
6539     symbol = &MakeSymbol(name);
6540   }
6541   Attrs &attrs{symbol->attrs()};
6542   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6543     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6544     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6545     Say(name,
6546         WithIsFatal(
6547             "The accessibility of '%s' has already been specified as %s"_en_US,
6548             attr != prev),
6549         MakeOpName(name), EnumToString(prev));
6550   } else {
6551     attrs.set(attr);
6552   }
6553   return *symbol;
6554 }
6555 
6556 static bool NeedsExplicitType(const Symbol &symbol) {
6557   if (symbol.has<UnknownDetails>()) {
6558     return true;
6559   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6560     return !details->type();
6561   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6562     return !details->type();
6563   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6564     return !details->interface().symbol() && !details->interface().type();
6565   } else {
6566     return false;
6567   }
6568 }
6569 
6570 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6571   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
6572       implicitPart, decls] = x.t;
6573   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
6574   auto stateRestorer{
6575       common::ScopedSet(specPartState_, SpecificationPartState{})};
6576   Walk(accDecls);
6577   Walk(ompDecls);
6578   Walk(compilerDirectives);
6579   Walk(useStmts);
6580   ClearUseRenames();
6581   ClearUseOnly();
6582   ClearExplicitIntrinsicUses();
6583   Walk(importStmts);
6584   Walk(implicitPart);
6585   for (const auto &decl : decls) {
6586     if (const auto *spec{
6587             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6588       PreSpecificationConstruct(*spec);
6589     }
6590   }
6591   Walk(decls);
6592   FinishSpecificationPart(decls);
6593   return false;
6594 }
6595 
6596 // Initial processing on specification constructs, before visiting them.
6597 void ResolveNamesVisitor::PreSpecificationConstruct(
6598     const parser::SpecificationConstruct &spec) {
6599   std::visit(
6600       common::visitors{
6601           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6602             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6603           },
6604           [&](const Indirection<parser::InterfaceBlock> &y) {
6605             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6606                 y.value().t)};
6607             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
6608               CreateGeneric(*spec);
6609             }
6610           },
6611           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
6612             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
6613               CreateCommonBlockSymbols(*commonStmt);
6614             }
6615           },
6616           [&](const auto &) {},
6617       },
6618       spec.u);
6619 }
6620 
6621 void ResolveNamesVisitor::CreateCommonBlockSymbols(
6622     const parser::CommonStmt &commonStmt) {
6623   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
6624     const auto &[name, objects] = block.t;
6625     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
6626     for (const auto &object : objects) {
6627       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
6628       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
6629         details->set_commonBlock(commonBlock);
6630         commonBlock.get<CommonBlockDetails>().add_object(obj);
6631       }
6632     }
6633   }
6634 }
6635 
6636 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6637   auto info{GenericSpecInfo{x}};
6638   const SourceName &symbolName{info.symbolName()};
6639   if (IsLogicalConstant(context(), symbolName)) {
6640     Say(symbolName,
6641         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6642     return;
6643   }
6644   GenericDetails genericDetails;
6645   if (Symbol * existing{FindInScope(symbolName)}) {
6646     if (existing->has<GenericDetails>()) {
6647       info.Resolve(existing);
6648       return; // already have generic, add to it
6649     }
6650     Symbol &ultimate{existing->GetUltimate()};
6651     if (auto *ultimateDetails{ultimate.detailsIf<GenericDetails>()}) {
6652       // convert a use-associated generic into a local generic
6653       genericDetails.CopyFrom(*ultimateDetails);
6654       AddGenericUse(genericDetails, existing->name(),
6655           existing->get<UseDetails>().symbol());
6656     } else if (ultimate.has<SubprogramDetails>() ||
6657         ultimate.has<SubprogramNameDetails>()) {
6658       genericDetails.set_specific(ultimate);
6659     } else if (ultimate.has<DerivedTypeDetails>()) {
6660       genericDetails.set_derivedType(ultimate);
6661     } else {
6662       SayAlreadyDeclared(symbolName, *existing);
6663     }
6664     EraseSymbol(*existing);
6665   }
6666   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
6667 }
6668 
6669 void ResolveNamesVisitor::FinishSpecificationPart(
6670     const std::list<parser::DeclarationConstruct> &decls) {
6671   badStmtFuncFound_ = false;
6672   CheckImports();
6673   bool inModule{currScope().kind() == Scope::Kind::Module};
6674   for (auto &pair : currScope()) {
6675     auto &symbol{*pair.second};
6676     if (NeedsExplicitType(symbol)) {
6677       ApplyImplicitRules(symbol);
6678     }
6679     if (IsDummy(symbol) && isImplicitNoneType() &&
6680         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
6681       Say(symbol.name(),
6682           "No explicit type declared for dummy argument '%s'"_err_en_US);
6683       context().SetError(symbol);
6684     }
6685     if (symbol.has<GenericDetails>()) {
6686       CheckGenericProcedures(symbol);
6687     }
6688     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
6689         !symbol.test(Symbol::Flag::Function) &&
6690         !symbol.test(Symbol::Flag::Subroutine)) {
6691       // in a module, external proc without return type is subroutine
6692       symbol.set(
6693           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
6694     }
6695     if (!symbol.has<HostAssocDetails>()) {
6696       CheckPossibleBadForwardRef(symbol);
6697     }
6698   }
6699   currScope().InstantiateDerivedTypes();
6700   for (const auto &decl : decls) {
6701     if (const auto *statement{std::get_if<
6702             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
6703             &decl.u)}) {
6704       AnalyzeStmtFunctionStmt(statement->statement.value());
6705     }
6706   }
6707   // TODO: what about instantiations in BLOCK?
6708   CheckSaveStmts();
6709   CheckCommonBlocks();
6710   if (!inInterfaceBlock()) {
6711     // TODO: warn for the case where the EQUIVALENCE statement is in a
6712     // procedure declaration in an interface block
6713     CheckEquivalenceSets();
6714   }
6715 }
6716 
6717 // Analyze the bodies of statement functions now that the symbols in this
6718 // specification part have been fully declared and implicitly typed.
6719 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
6720     const parser::StmtFunctionStmt &stmtFunc) {
6721   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
6722   if (!symbol || !symbol->has<SubprogramDetails>()) {
6723     return;
6724   }
6725   auto &details{symbol->get<SubprogramDetails>()};
6726   auto expr{AnalyzeExpr(
6727       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
6728   if (!expr) {
6729     context().SetError(*symbol);
6730     return;
6731   }
6732   if (auto type{evaluate::DynamicType::From(*symbol)}) {
6733     auto converted{ConvertToType(*type, std::move(*expr))};
6734     if (!converted) {
6735       context().SetError(*symbol);
6736       return;
6737     }
6738     details.set_stmtFunction(std::move(*converted));
6739   } else {
6740     details.set_stmtFunction(std::move(*expr));
6741   }
6742 }
6743 
6744 void ResolveNamesVisitor::CheckImports() {
6745   auto &scope{currScope()};
6746   switch (scope.GetImportKind()) {
6747   case common::ImportKind::None:
6748     break;
6749   case common::ImportKind::All:
6750     // C8102: all entities in host must not be hidden
6751     for (const auto &pair : scope.parent()) {
6752       auto &name{pair.first};
6753       std::optional<SourceName> scopeName{scope.GetName()};
6754       if (!scopeName || name != *scopeName) {
6755         CheckImport(prevImportStmt_.value(), name);
6756       }
6757     }
6758     break;
6759   case common::ImportKind::Default:
6760   case common::ImportKind::Only:
6761     // C8102: entities named in IMPORT must not be hidden
6762     for (auto &name : scope.importNames()) {
6763       CheckImport(name, name);
6764     }
6765     break;
6766   }
6767 }
6768 
6769 void ResolveNamesVisitor::CheckImport(
6770     const SourceName &location, const SourceName &name) {
6771   if (auto *symbol{FindInScope(name)}) {
6772     Say(location, "'%s' from host is not accessible"_err_en_US, name)
6773         .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
6774             symbol->name());
6775   }
6776 }
6777 
6778 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
6779   return CheckNotInBlock("IMPLICIT") && // C1107
6780       ImplicitRulesVisitor::Pre(x);
6781 }
6782 
6783 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
6784   std::visit(common::visitors{
6785                  [&](const parser::Name &x) { ResolveName(x); },
6786                  [&](const parser::StructureComponent &x) {
6787                    ResolveStructureComponent(x);
6788                  },
6789              },
6790       x.u);
6791 }
6792 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
6793   std::visit(common::visitors{
6794                  [&](const parser::Name &x) { ResolveName(x); },
6795                  [&](const parser::StructureComponent &x) {
6796                    ResolveStructureComponent(x);
6797                  },
6798              },
6799       x.u);
6800 }
6801 
6802 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
6803   const auto &dataRef{std::get<parser::DataRef>(x.t)};
6804   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
6805   const auto &expr{std::get<parser::Expr>(x.t)};
6806   ResolveDataRef(dataRef);
6807   Walk(bounds);
6808   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
6809   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
6810     if (NameIsKnownOrIntrinsic(*name)) {
6811       // If the name is known because it is an object entity from a host
6812       // procedure, create a host associated symbol.
6813       if (Symbol * symbol{name->symbol}; symbol &&
6814           symbol->GetUltimate().has<ObjectEntityDetails>() &&
6815           IsUplevelReference(*symbol)) {
6816         MakeHostAssocSymbol(*name, *symbol);
6817       }
6818       return false;
6819     }
6820   }
6821   Walk(expr);
6822   return false;
6823 }
6824 void ResolveNamesVisitor::Post(const parser::Designator &x) {
6825   ResolveDesignator(x);
6826 }
6827 
6828 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
6829   ResolveStructureComponent(x.v.thing);
6830 }
6831 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
6832   DeclTypeSpecVisitor::Post(x);
6833   ConstructVisitor::Post(x);
6834 }
6835 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
6836   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
6837   if (HandleStmtFunction(x)) {
6838     return false;
6839   } else {
6840     // This is an array element assignment: resolve names of indices
6841     const auto &names{std::get<std::list<parser::Name>>(x.t)};
6842     for (auto &name : names) {
6843       ResolveName(name);
6844     }
6845     return true;
6846   }
6847 }
6848 
6849 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
6850   const parser::Name &name{x.v};
6851   if (FindSymbol(name)) {
6852     // OK
6853   } else if (IsLogicalConstant(context(), name.source)) {
6854     Say(name,
6855         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6856   } else {
6857     // Resolved later in expression semantics
6858     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
6859   }
6860   return false;
6861 }
6862 
6863 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
6864   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6865     ConvertToObjectEntity(DEREF(name->symbol));
6866   }
6867 }
6868 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
6869   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6870     ConvertToObjectEntity(DEREF(name->symbol));
6871   }
6872 }
6873 
6874 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
6875   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
6876           x.u)) {
6877     // TODO: global directives
6878     return true;
6879   }
6880   auto root{ProgramTree::Build(x)};
6881   SetScope(topScope_);
6882   ResolveSpecificationParts(root);
6883   FinishSpecificationParts(root);
6884   inExecutionPart_ = true;
6885   ResolveExecutionParts(root);
6886   inExecutionPart_ = false;
6887   ResolveAccParts(context(), x);
6888   ResolveOmpParts(context(), x);
6889   return false;
6890 }
6891 
6892 // References to procedures need to record that their symbols are known
6893 // to be procedures, so that they don't get converted to objects by default.
6894 class ExecutionPartSkimmer {
6895 public:
6896   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
6897       : resolver_{resolver} {}
6898 
6899   void Walk(const parser::ExecutionPart *exec) {
6900     if (exec) {
6901       parser::Walk(*exec, *this);
6902     }
6903   }
6904 
6905   template <typename A> bool Pre(const A &) { return true; }
6906   template <typename A> void Post(const A &) {}
6907   void Post(const parser::FunctionReference &fr) {
6908     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
6909   }
6910   void Post(const parser::CallStmt &cs) {
6911     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
6912   }
6913 
6914 private:
6915   ResolveNamesVisitor &resolver_;
6916 };
6917 
6918 // Build the scope tree and resolve names in the specification parts of this
6919 // node and its children
6920 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
6921   if (node.isSpecificationPartResolved()) {
6922     return; // been here already
6923   }
6924   node.set_isSpecificationPartResolved();
6925   if (!BeginScopeForNode(node)) {
6926     return; // an error prevented scope from being created
6927   }
6928   Scope &scope{currScope()};
6929   node.set_scope(scope);
6930   AddSubpNames(node);
6931   std::visit(
6932       [&](const auto *x) {
6933         if (x) {
6934           Walk(*x);
6935         }
6936       },
6937       node.stmt());
6938   Walk(node.spec());
6939   // If this is a function, convert result to an object. This is to prevent the
6940   // result from being converted later to a function symbol if it is called
6941   // inside the function.
6942   // If the result is function pointer, then ConvertToObjectEntity will not
6943   // convert the result to an object, and calling the symbol inside the function
6944   // will result in calls to the result pointer.
6945   // A function cannot be called recursively if RESULT was not used to define a
6946   // distinct result name (15.6.2.2 point 4.).
6947   if (Symbol * symbol{scope.symbol()}) {
6948     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
6949       if (details->isFunction()) {
6950         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
6951       }
6952     }
6953   }
6954   if (node.IsModule()) {
6955     ApplyDefaultAccess();
6956   }
6957   for (auto &child : node.children()) {
6958     ResolveSpecificationParts(child);
6959   }
6960   ExecutionPartSkimmer{*this}.Walk(node.exec());
6961   PopScope();
6962   // Ensure that every object entity has a type.
6963   for (auto &pair : *node.scope()) {
6964     ApplyImplicitRules(*pair.second);
6965   }
6966 }
6967 
6968 // Add SubprogramNameDetails symbols for module and internal subprograms and
6969 // their ENTRY statements.
6970 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
6971   auto kind{
6972       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
6973   for (auto &child : node.children()) {
6974     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
6975     symbol.set(child.GetSubpFlag());
6976     for (const auto &entryStmt : child.entryStmts()) {
6977       SubprogramNameDetails details{kind, child};
6978       details.set_isEntryStmt();
6979       auto &symbol{
6980           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
6981       symbol.set(child.GetSubpFlag());
6982     }
6983   }
6984 }
6985 
6986 // Push a new scope for this node or return false on error.
6987 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
6988   switch (node.GetKind()) {
6989     SWITCH_COVERS_ALL_CASES
6990   case ProgramTree::Kind::Program:
6991     PushScope(Scope::Kind::MainProgram,
6992         &MakeSymbol(node.name(), MainProgramDetails{}));
6993     return true;
6994   case ProgramTree::Kind::Function:
6995   case ProgramTree::Kind::Subroutine:
6996     return BeginSubprogram(
6997         node.name(), node.GetSubpFlag(), node.HasModulePrefix());
6998   case ProgramTree::Kind::MpSubprogram:
6999     return BeginMpSubprogram(node.name());
7000   case ProgramTree::Kind::Module:
7001     BeginModule(node.name(), false);
7002     return true;
7003   case ProgramTree::Kind::Submodule:
7004     return BeginSubmodule(node.name(), node.GetParentId());
7005   case ProgramTree::Kind::BlockData:
7006     PushBlockDataScope(node.name());
7007     return true;
7008   }
7009 }
7010 
7011 // Some analyses and checks, such as the processing of initializers of
7012 // pointers, are deferred until all of the pertinent specification parts
7013 // have been visited.  This deferred processing enables the use of forward
7014 // references in these circumstances.
7015 class DeferredCheckVisitor {
7016 public:
7017   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7018       : resolver_{resolver} {}
7019 
7020   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7021 
7022   template <typename A> bool Pre(const A &) { return true; }
7023   template <typename A> void Post(const A &) {}
7024 
7025   void Post(const parser::DerivedTypeStmt &x) {
7026     const auto &name{std::get<parser::Name>(x.t)};
7027     if (Symbol * symbol{name.symbol}) {
7028       if (Scope * scope{symbol->scope()}) {
7029         if (scope->IsDerivedType()) {
7030           resolver_.PushScope(*scope);
7031           pushedScope_ = true;
7032         }
7033       }
7034     }
7035   }
7036   void Post(const parser::EndTypeStmt &) {
7037     if (pushedScope_) {
7038       resolver_.PopScope();
7039       pushedScope_ = false;
7040     }
7041   }
7042 
7043   void Post(const parser::ProcInterface &pi) {
7044     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7045       resolver_.CheckExplicitInterface(*name);
7046     }
7047   }
7048   bool Pre(const parser::EntityDecl &decl) {
7049     Init(std::get<parser::Name>(decl.t),
7050         std::get<std::optional<parser::Initialization>>(decl.t));
7051     return false;
7052   }
7053   bool Pre(const parser::ComponentDecl &decl) {
7054     Init(std::get<parser::Name>(decl.t),
7055         std::get<std::optional<parser::Initialization>>(decl.t));
7056     return false;
7057   }
7058   bool Pre(const parser::ProcDecl &decl) {
7059     if (const auto &init{
7060             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7061       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7062     }
7063     return false;
7064   }
7065   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7066     resolver_.CheckExplicitInterface(tbps.interfaceName);
7067   }
7068   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7069     if (pushedScope_) {
7070       resolver_.CheckBindings(tbps);
7071     }
7072   }
7073 
7074 private:
7075   void Init(const parser::Name &name,
7076       const std::optional<parser::Initialization> &init) {
7077     if (init) {
7078       if (const auto *target{
7079               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7080         resolver_.PointerInitialization(name, *target);
7081       }
7082     }
7083   }
7084 
7085   ResolveNamesVisitor &resolver_;
7086   bool pushedScope_{false};
7087 };
7088 
7089 // Perform checks and completions that need to happen after all of
7090 // the specification parts but before any of the execution parts.
7091 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7092   if (!node.scope()) {
7093     return; // error occurred creating scope
7094   }
7095   SetScope(*node.scope());
7096   // The initializers of pointers, the default initializers of pointer
7097   // components, and non-deferred type-bound procedure bindings have not
7098   // yet been traversed.
7099   // We do that now, when any (formerly) forward references that appear
7100   // in those initializers will resolve to the right symbols without
7101   // incurring spurious errors with IMPLICIT NONE.
7102   DeferredCheckVisitor{*this}.Walk(node.spec());
7103   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7104   for (Scope &childScope : currScope().children()) {
7105     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7106       FinishDerivedTypeInstantiation(childScope);
7107     }
7108   }
7109   for (const auto &child : node.children()) {
7110     FinishSpecificationParts(child);
7111   }
7112 }
7113 
7114 // Duplicate and fold component object pointer default initializer designators
7115 // using the actual type parameter values of each particular instantiation.
7116 // Validation is done later in declaration checking.
7117 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7118   CHECK(scope.IsDerivedType() && !scope.symbol());
7119   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7120     spec->Instantiate(currScope());
7121     const Symbol &origTypeSymbol{spec->typeSymbol()};
7122     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7123       CHECK(origTypeScope->IsDerivedType() &&
7124           origTypeScope->symbol() == &origTypeSymbol);
7125       auto &foldingContext{GetFoldingContext()};
7126       auto restorer{foldingContext.WithPDTInstance(*spec)};
7127       for (auto &pair : scope) {
7128         Symbol &comp{*pair.second};
7129         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7130         if (IsPointer(comp)) {
7131           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7132             auto origDetails{origComp.get<ObjectEntityDetails>()};
7133             if (const MaybeExpr & init{origDetails.init()}) {
7134               SomeExpr newInit{*init};
7135               MaybeExpr folded{
7136                   evaluate::Fold(foldingContext, std::move(newInit))};
7137               details->set_init(std::move(folded));
7138             }
7139           }
7140         }
7141       }
7142     }
7143   }
7144 }
7145 
7146 // Resolve names in the execution part of this node and its children
7147 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7148   if (!node.scope()) {
7149     return; // error occurred creating scope
7150   }
7151   SetScope(*node.scope());
7152   if (const auto *exec{node.exec()}) {
7153     Walk(*exec);
7154   }
7155   PopScope(); // converts unclassified entities into objects
7156   for (const auto &child : node.children()) {
7157     ResolveExecutionParts(child);
7158   }
7159 }
7160 
7161 void ResolveNamesVisitor::Post(const parser::Program &) {
7162   // ensure that all temps were deallocated
7163   CHECK(!attrs_);
7164   CHECK(!GetDeclTypeSpec());
7165 }
7166 
7167 // A singleton instance of the scope -> IMPLICIT rules mapping is
7168 // shared by all instances of ResolveNamesVisitor and accessed by this
7169 // pointer when the visitors (other than the top-level original) are
7170 // constructed.
7171 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7172 
7173 bool ResolveNames(
7174     SemanticsContext &context, const parser::Program &program, Scope &top) {
7175   ImplicitRulesMap implicitRulesMap;
7176   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7177   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7178   return !context.AnyFatalError();
7179 }
7180 
7181 // Processes a module (but not internal) function when it is referenced
7182 // in a specification expression in a sibling procedure.
7183 void ResolveSpecificationParts(
7184     SemanticsContext &context, const Symbol &subprogram) {
7185   auto originalLocation{context.location()};
7186   ResolveNamesVisitor visitor{
7187       context, DEREF(sharedImplicitRulesMap), context.globalScope()};
7188   const auto &details{subprogram.get<SubprogramNameDetails>()};
7189   ProgramTree &node{details.node()};
7190   const Scope &moduleScope{subprogram.owner()};
7191   visitor.SetScope(const_cast<Scope &>(moduleScope));
7192   visitor.ResolveSpecificationParts(node);
7193   context.set_location(std::move(originalLocation));
7194 }
7195 
7196 } // namespace Fortran::semantics
7197