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   ~SubprogramVisitor();
750   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
751   bool Pre(const parser::SubroutineStmt &);
752   void Post(const parser::SubroutineStmt &);
753   bool Pre(const parser::FunctionStmt &);
754   void Post(const parser::FunctionStmt &);
755   bool Pre(const parser::EntryStmt &);
756   void Post(const parser::EntryStmt &);
757   bool Pre(const parser::InterfaceBody::Subroutine &);
758   void Post(const parser::InterfaceBody::Subroutine &);
759   bool Pre(const parser::InterfaceBody::Function &);
760   void Post(const parser::InterfaceBody::Function &);
761   bool Pre(const parser::Suffix &);
762   bool Pre(const parser::PrefixSpec &);
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   void FinishFunctionResult();
772   // Set when we see a stmt function that is really an array element assignment
773   bool badStmtFuncFound_{false};
774 
775 private:
776   // Info about the current function: parse tree of the type in the PrefixSpec;
777   // name and symbol of the function result from the Suffix; source location.
778   struct FuncInfo {
779     const parser::DeclarationTypeSpec *parsedType{nullptr};
780     const parser::Name *resultName{nullptr};
781     Symbol *resultSymbol{nullptr};
782     std::optional<SourceName> source;
783     bool inFunctionStmt{false}; // true between Pre/Post of FunctionStmt
784   };
785   std::vector<FuncInfo> funcInfoStack_;
786 
787   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
788   // so that it can be replaced by a later definition.
789   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
790   void CheckExtantProc(const parser::Name &, Symbol::Flag);
791   // Create a subprogram symbol in the current scope and push a new scope.
792   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag);
793   Symbol *GetSpecificFromGeneric(const parser::Name &);
794   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
795 };
796 
797 class DeclarationVisitor : public ArraySpecVisitor,
798                            public virtual ScopeHandler {
799 public:
800   using ArraySpecVisitor::Post;
801   using ScopeHandler::Post;
802   using ScopeHandler::Pre;
803 
804   bool Pre(const parser::Initialization &);
805   void Post(const parser::EntityDecl &);
806   void Post(const parser::ObjectDecl &);
807   void Post(const parser::PointerDecl &);
808   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
809   void Post(const parser::BindStmt &) { EndAttrs(); }
810   bool Pre(const parser::BindEntity &);
811   bool Pre(const parser::OldParameterStmt &);
812   bool Pre(const parser::NamedConstantDef &);
813   bool Pre(const parser::NamedConstant &);
814   void Post(const parser::EnumDef &);
815   bool Pre(const parser::Enumerator &);
816   bool Pre(const parser::AccessSpec &);
817   bool Pre(const parser::AsynchronousStmt &);
818   bool Pre(const parser::ContiguousStmt &);
819   bool Pre(const parser::ExternalStmt &);
820   bool Pre(const parser::IntentStmt &);
821   bool Pre(const parser::IntrinsicStmt &);
822   bool Pre(const parser::OptionalStmt &);
823   bool Pre(const parser::ProtectedStmt &);
824   bool Pre(const parser::ValueStmt &);
825   bool Pre(const parser::VolatileStmt &);
826   bool Pre(const parser::AllocatableStmt &) {
827     objectDeclAttr_ = Attr::ALLOCATABLE;
828     return true;
829   }
830   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
831   bool Pre(const parser::TargetStmt &) {
832     objectDeclAttr_ = Attr::TARGET;
833     return true;
834   }
835   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
836   void Post(const parser::DimensionStmt::Declaration &);
837   void Post(const parser::CodimensionDecl &);
838   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
839   void Post(const parser::TypeDeclarationStmt &);
840   void Post(const parser::IntegerTypeSpec &);
841   void Post(const parser::IntrinsicTypeSpec::Real &);
842   void Post(const parser::IntrinsicTypeSpec::Complex &);
843   void Post(const parser::IntrinsicTypeSpec::Logical &);
844   void Post(const parser::IntrinsicTypeSpec::Character &);
845   void Post(const parser::CharSelector::LengthAndKind &);
846   void Post(const parser::CharLength &);
847   void Post(const parser::LengthSelector &);
848   bool Pre(const parser::KindParam &);
849   bool Pre(const parser::DeclarationTypeSpec::Type &);
850   void Post(const parser::DeclarationTypeSpec::Type &);
851   bool Pre(const parser::DeclarationTypeSpec::Class &);
852   void Post(const parser::DeclarationTypeSpec::Class &);
853   void Post(const parser::DeclarationTypeSpec::Record &);
854   void Post(const parser::DerivedTypeSpec &);
855   bool Pre(const parser::DerivedTypeDef &);
856   bool Pre(const parser::DerivedTypeStmt &);
857   void Post(const parser::DerivedTypeStmt &);
858   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
859   void Post(const parser::TypeParamDefStmt &);
860   bool Pre(const parser::TypeAttrSpec::Extends &);
861   bool Pre(const parser::PrivateStmt &);
862   bool Pre(const parser::SequenceStmt &);
863   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
864   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
865   void Post(const parser::ComponentDecl &);
866   void Post(const parser::FillDecl &);
867   bool Pre(const parser::ProcedureDeclarationStmt &);
868   void Post(const parser::ProcedureDeclarationStmt &);
869   bool Pre(const parser::DataComponentDefStmt &); // returns false
870   bool Pre(const parser::ProcComponentDefStmt &);
871   void Post(const parser::ProcComponentDefStmt &);
872   bool Pre(const parser::ProcPointerInit &);
873   void Post(const parser::ProcInterface &);
874   void Post(const parser::ProcDecl &);
875   bool Pre(const parser::TypeBoundProcedurePart &);
876   void Post(const parser::TypeBoundProcedurePart &);
877   void Post(const parser::ContainsStmt &);
878   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
879   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
880   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
881   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
882   void Post(const parser::FinalProcedureStmt &);
883   bool Pre(const parser::TypeBoundGenericStmt &);
884   bool Pre(const parser::StructureDef &); // returns false
885   bool Pre(const parser::Union::UnionStmt &);
886   bool Pre(const parser::StructureField &);
887   void Post(const parser::StructureField &);
888   bool Pre(const parser::AllocateStmt &);
889   void Post(const parser::AllocateStmt &);
890   bool Pre(const parser::StructureConstructor &);
891   bool Pre(const parser::NamelistStmt::Group &);
892   bool Pre(const parser::IoControlSpec &);
893   bool Pre(const parser::CommonStmt::Block &);
894   bool Pre(const parser::CommonBlockObject &);
895   void Post(const parser::CommonBlockObject &);
896   bool Pre(const parser::EquivalenceStmt &);
897   bool Pre(const parser::SaveStmt &);
898   bool Pre(const parser::BasedPointerStmt &);
899 
900   void PointerInitialization(
901       const parser::Name &, const parser::InitialDataTarget &);
902   void PointerInitialization(
903       const parser::Name &, const parser::ProcPointerInit &);
904   void NonPointerInitialization(
905       const parser::Name &, const parser::ConstantExpr &);
906   void CheckExplicitInterface(const parser::Name &);
907   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
908 
909   const parser::Name *ResolveDesignator(const parser::Designator &);
910 
911 protected:
912   bool BeginDecl();
913   void EndDecl();
914   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
915   // Make sure that there's an entity in an enclosing scope called Name
916   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
917   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
918   // it comes from the entity in the containing scope, or implicit rules.
919   // Return pointer to the new symbol, or nullptr on error.
920   Symbol *DeclareLocalEntity(const parser::Name &);
921   // Declare a statement entity (i.e., an implied DO loop index for
922   // a DATA statement or an array constructor).  If there isn't an explict
923   // type specified, implicit rules apply. Return pointer to the new symbol,
924   // or nullptr on error.
925   Symbol *DeclareStatementEntity(const parser::DoVariable &,
926       const std::optional<parser::IntegerTypeSpec> &);
927   Symbol &MakeCommonBlockSymbol(const parser::Name &);
928   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
929   bool CheckUseError(const parser::Name &);
930   void CheckAccessibility(const SourceName &, bool, Symbol &);
931   void CheckCommonBlocks();
932   void CheckSaveStmts();
933   void CheckEquivalenceSets();
934   bool CheckNotInBlock(const char *);
935   bool NameIsKnownOrIntrinsic(const parser::Name &);
936 
937   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
938   // or nullptr in case of error.
939   const parser::Name *ResolveStructureComponent(
940       const parser::StructureComponent &);
941   const parser::Name *ResolveDataRef(const parser::DataRef &);
942   const parser::Name *ResolveName(const parser::Name &);
943   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
944   Symbol *NoteInterfaceName(const parser::Name &);
945   bool IsUplevelReference(const Symbol &);
946 
947   std::optional<SourceName> BeginCheckOnIndexUseInOwnBounds(
948       const parser::DoVariable &name) {
949     std::optional<SourceName> result{checkIndexUseInOwnBounds_};
950     checkIndexUseInOwnBounds_ = name.thing.thing.source;
951     return result;
952   }
953   void EndCheckOnIndexUseInOwnBounds(const std::optional<SourceName> &restore) {
954     checkIndexUseInOwnBounds_ = restore;
955   }
956 
957 private:
958   // The attribute corresponding to the statement containing an ObjectDecl
959   std::optional<Attr> objectDeclAttr_;
960   // Info about current character type while walking DeclTypeSpec.
961   // Also captures any "*length" specifier on an individual declaration.
962   struct {
963     std::optional<ParamValue> length;
964     std::optional<KindExpr> kind;
965   } charInfo_;
966   // Info about current derived type or STRUCTURE while walking
967   // DerivedTypeDef / StructureDef
968   struct {
969     const parser::Name *extends{nullptr}; // EXTENDS(name)
970     bool privateComps{false}; // components are private by default
971     bool privateBindings{false}; // bindings are private by default
972     bool sawContains{false}; // currently processing bindings
973     bool sequence{false}; // is a sequence type
974     const Symbol *type{nullptr}; // derived type being defined
975     bool isStructure{false}; // is a DEC STRUCTURE
976   } derivedTypeInfo_;
977   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
978   // the interface name, if any.
979   const parser::Name *interfaceName_{nullptr};
980   // Map type-bound generic to binding names of its specific bindings
981   std::multimap<Symbol *, const parser::Name *> genericBindings_;
982   // Info about current ENUM
983   struct EnumeratorState {
984     // Enum value must hold inside a C_INT (7.6.2).
985     std::optional<int> value{0};
986   } enumerationState_;
987   // Set for OldParameterStmt processing
988   bool inOldStyleParameterStmt_{false};
989   // Set when walking DATA & array constructor implied DO loop bounds
990   // to warn about use of the implied DO intex therein.
991   std::optional<SourceName> checkIndexUseInOwnBounds_;
992 
993   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
994   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
995   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
996   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
997   void SetType(const parser::Name &, const DeclTypeSpec &);
998   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
999   std::optional<DerivedTypeSpec> ResolveExtendsType(
1000       const parser::Name &, const parser::Name *);
1001   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
1002   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1003   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
1004   ParamValue GetParamValue(
1005       const parser::TypeParamValue &, common::TypeParamAttr attr);
1006   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
1007   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
1008   Attrs HandleSaveName(const SourceName &, Attrs);
1009   void AddSaveName(std::set<SourceName> &, const SourceName &);
1010   void SetSaveAttr(Symbol &);
1011   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1012   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1013   void Initialization(const parser::Name &, const parser::Initialization &,
1014       bool inComponentDecl);
1015   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
1016   bool CheckForHostAssociatedImplicit(const parser::Name &);
1017 
1018   // Declare an object or procedure entity.
1019   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1020   template <typename T>
1021   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1022     Symbol &symbol{MakeSymbol(name, attrs)};
1023     if (context().HasError(symbol) || symbol.has<T>()) {
1024       return symbol; // OK or error already reported
1025     } else if (symbol.has<UnknownDetails>()) {
1026       symbol.set_details(T{});
1027       return symbol;
1028     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1029       symbol.set_details(T{std::move(*details)});
1030       return symbol;
1031     } else if (std::is_same_v<EntityDetails, T> &&
1032         (symbol.has<ObjectEntityDetails>() ||
1033             symbol.has<ProcEntityDetails>())) {
1034       return symbol; // OK
1035     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1036       Say(name.source,
1037           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1038           name.source, GetUsedModule(*details).name());
1039     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1040       if (details->kind() == SubprogramKind::Module) {
1041         Say2(name,
1042             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1043             symbol, "Module procedure definition"_en_US);
1044       } else if (details->kind() == SubprogramKind::Internal) {
1045         Say2(name,
1046             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1047             symbol, "Internal procedure definition"_en_US);
1048       } else {
1049         DIE("unexpected kind");
1050       }
1051     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1052         symbol.has<ProcEntityDetails>()) {
1053       SayWithDecl(
1054           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1055     } else if (std::is_same_v<ProcEntityDetails, T> &&
1056         symbol.has<ObjectEntityDetails>()) {
1057       if (InCommonBlock(symbol)) {
1058         SayWithDecl(name, symbol,
1059             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1060       } else {
1061         SayWithDecl(
1062             name, symbol, "'%s' is already declared as an object"_err_en_US);
1063       }
1064     } else if (!CheckPossibleBadForwardRef(symbol)) {
1065       SayAlreadyDeclared(name, symbol);
1066     }
1067     context().SetError(symbol);
1068     return symbol;
1069   }
1070   bool HasCycle(const Symbol &, const ProcInterface &);
1071 };
1072 
1073 // Resolve construct entities and statement entities.
1074 // Check that construct names don't conflict with other names.
1075 class ConstructVisitor : public virtual DeclarationVisitor {
1076 public:
1077   bool Pre(const parser::ConcurrentHeader &);
1078   bool Pre(const parser::LocalitySpec::Local &);
1079   bool Pre(const parser::LocalitySpec::LocalInit &);
1080   bool Pre(const parser::LocalitySpec::Shared &);
1081   bool Pre(const parser::AcSpec &);
1082   bool Pre(const parser::AcImpliedDo &);
1083   bool Pre(const parser::DataImpliedDo &);
1084   bool Pre(const parser::DataIDoObject &);
1085   bool Pre(const parser::DataStmtObject &);
1086   bool Pre(const parser::DataStmtValue &);
1087   bool Pre(const parser::DoConstruct &);
1088   void Post(const parser::DoConstruct &);
1089   bool Pre(const parser::ForallConstruct &);
1090   void Post(const parser::ForallConstruct &);
1091   bool Pre(const parser::ForallStmt &);
1092   void Post(const parser::ForallStmt &);
1093   bool Pre(const parser::BlockStmt &);
1094   bool Pre(const parser::EndBlockStmt &);
1095   void Post(const parser::Selector &);
1096   void Post(const parser::AssociateStmt &);
1097   void Post(const parser::EndAssociateStmt &);
1098   bool Pre(const parser::Association &);
1099   void Post(const parser::SelectTypeStmt &);
1100   void Post(const parser::SelectRankStmt &);
1101   bool Pre(const parser::SelectTypeConstruct &);
1102   void Post(const parser::SelectTypeConstruct &);
1103   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1104   void Post(const parser::SelectTypeConstruct::TypeCase &);
1105   // Creates Block scopes with neither symbol name nor symbol details.
1106   bool Pre(const parser::SelectRankConstruct::RankCase &);
1107   void Post(const parser::SelectRankConstruct::RankCase &);
1108   void Post(const parser::TypeGuardStmt::Guard &);
1109   void Post(const parser::SelectRankCaseStmt::Rank &);
1110   bool Pre(const parser::ChangeTeamStmt &);
1111   void Post(const parser::EndChangeTeamStmt &);
1112   void Post(const parser::CoarrayAssociation &);
1113 
1114   // Definitions of construct names
1115   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1116   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1117   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1118   bool Pre(const parser::LabelDoStmt &) {
1119     return false; // error recovery
1120   }
1121   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1122   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1123   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1124   bool Pre(const parser::SelectRankConstruct &);
1125   void Post(const parser::SelectRankConstruct &);
1126   bool Pre(const parser::SelectRankStmt &x) {
1127     return CheckDef(std::get<0>(x.t));
1128   }
1129   bool Pre(const parser::SelectTypeStmt &x) {
1130     return CheckDef(std::get<0>(x.t));
1131   }
1132 
1133   // References to construct names
1134   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1135   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1136   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1137   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1138   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1139   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1140   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1141   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1142   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1143   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1144   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1145   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1146   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1147   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1148   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1149 
1150 private:
1151   // R1105 selector -> expr | variable
1152   // expr is set in either case unless there were errors
1153   struct Selector {
1154     Selector() {}
1155     Selector(const SourceName &source, MaybeExpr &&expr)
1156         : source{source}, expr{std::move(expr)} {}
1157     operator bool() const { return expr.has_value(); }
1158     parser::CharBlock source;
1159     MaybeExpr expr;
1160   };
1161   // association -> [associate-name =>] selector
1162   struct Association {
1163     const parser::Name *name{nullptr};
1164     Selector selector;
1165   };
1166   std::vector<Association> associationStack_;
1167   Association *currentAssociation_{nullptr};
1168 
1169   template <typename T> bool CheckDef(const T &t) {
1170     return CheckDef(std::get<std::optional<parser::Name>>(t));
1171   }
1172   template <typename T> void CheckRef(const T &t) {
1173     CheckRef(std::get<std::optional<parser::Name>>(t));
1174   }
1175   bool CheckDef(const std::optional<parser::Name> &);
1176   void CheckRef(const std::optional<parser::Name> &);
1177   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1178   const DeclTypeSpec &ToDeclTypeSpec(
1179       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1180   Symbol *MakeAssocEntity();
1181   void SetTypeFromAssociation(Symbol &);
1182   void SetAttrsFromAssociation(Symbol &);
1183   Selector ResolveSelector(const parser::Selector &);
1184   void ResolveIndexName(const parser::ConcurrentControl &control);
1185   void SetCurrentAssociation(std::size_t n);
1186   Association &GetCurrentAssociation();
1187   void PushAssociation();
1188   void PopAssociation(std::size_t count = 1);
1189 };
1190 
1191 // Create scopes for OpenACC constructs
1192 class AccVisitor : public virtual DeclarationVisitor {
1193 public:
1194   void AddAccSourceRange(const parser::CharBlock &);
1195 
1196   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1197 
1198   bool Pre(const parser::OpenACCBlockConstruct &);
1199   void Post(const parser::OpenACCBlockConstruct &);
1200   bool Pre(const parser::AccBeginBlockDirective &x) {
1201     AddAccSourceRange(x.source);
1202     return true;
1203   }
1204   void Post(const parser::AccBeginBlockDirective &) {
1205     messageHandler().set_currStmtSource(std::nullopt);
1206   }
1207   bool Pre(const parser::AccEndBlockDirective &x) {
1208     AddAccSourceRange(x.source);
1209     return true;
1210   }
1211   void Post(const parser::AccEndBlockDirective &) {
1212     messageHandler().set_currStmtSource(std::nullopt);
1213   }
1214   bool Pre(const parser::AccBeginLoopDirective &x) {
1215     AddAccSourceRange(x.source);
1216     return true;
1217   }
1218   void Post(const parser::AccBeginLoopDirective &x) {
1219     messageHandler().set_currStmtSource(std::nullopt);
1220   }
1221 };
1222 
1223 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1224   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1225   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1226   switch (beginDir.v) {
1227   case llvm::acc::Directive::ACCD_data:
1228   case llvm::acc::Directive::ACCD_host_data:
1229   case llvm::acc::Directive::ACCD_kernels:
1230   case llvm::acc::Directive::ACCD_parallel:
1231   case llvm::acc::Directive::ACCD_serial:
1232     return true;
1233   default:
1234     return false;
1235   }
1236 }
1237 
1238 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1239   messageHandler().set_currStmtSource(source);
1240   currScope().AddSourceRange(source);
1241 }
1242 
1243 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1244   if (NeedsScope(x)) {
1245     PushScope(Scope::Kind::Block, nullptr);
1246   }
1247   return true;
1248 }
1249 
1250 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1251   if (NeedsScope(x)) {
1252     PopScope();
1253   }
1254 }
1255 
1256 // Create scopes for OpenMP constructs
1257 class OmpVisitor : public virtual DeclarationVisitor {
1258 public:
1259   void AddOmpSourceRange(const parser::CharBlock &);
1260 
1261   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1262 
1263   bool Pre(const parser::OpenMPBlockConstruct &);
1264   void Post(const parser::OpenMPBlockConstruct &);
1265   bool Pre(const parser::OmpBeginBlockDirective &x) {
1266     AddOmpSourceRange(x.source);
1267     return true;
1268   }
1269   void Post(const parser::OmpBeginBlockDirective &) {
1270     messageHandler().set_currStmtSource(std::nullopt);
1271   }
1272   bool Pre(const parser::OmpEndBlockDirective &x) {
1273     AddOmpSourceRange(x.source);
1274     return true;
1275   }
1276   void Post(const parser::OmpEndBlockDirective &) {
1277     messageHandler().set_currStmtSource(std::nullopt);
1278   }
1279 
1280   bool Pre(const parser::OpenMPLoopConstruct &) {
1281     PushScope(Scope::Kind::Block, nullptr);
1282     return true;
1283   }
1284   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1285   bool Pre(const parser::OmpBeginLoopDirective &x) {
1286     AddOmpSourceRange(x.source);
1287     return true;
1288   }
1289   void Post(const parser::OmpBeginLoopDirective &) {
1290     messageHandler().set_currStmtSource(std::nullopt);
1291   }
1292   bool Pre(const parser::OmpEndLoopDirective &x) {
1293     AddOmpSourceRange(x.source);
1294     return true;
1295   }
1296   void Post(const parser::OmpEndLoopDirective &) {
1297     messageHandler().set_currStmtSource(std::nullopt);
1298   }
1299 
1300   bool Pre(const parser::OpenMPSectionsConstruct &) {
1301     PushScope(Scope::Kind::Block, nullptr);
1302     return true;
1303   }
1304   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1305   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1306     AddOmpSourceRange(x.source);
1307     return true;
1308   }
1309   void Post(const parser::OmpBeginSectionsDirective &) {
1310     messageHandler().set_currStmtSource(std::nullopt);
1311   }
1312   bool Pre(const parser::OmpEndSectionsDirective &x) {
1313     AddOmpSourceRange(x.source);
1314     return true;
1315   }
1316   void Post(const parser::OmpEndSectionsDirective &) {
1317     messageHandler().set_currStmtSource(std::nullopt);
1318   }
1319 };
1320 
1321 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1322   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1323   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1324   switch (beginDir.v) {
1325   case llvm::omp::Directive::OMPD_target_data:
1326   case llvm::omp::Directive::OMPD_master:
1327   case llvm::omp::Directive::OMPD_ordered:
1328   case llvm::omp::Directive::OMPD_taskgroup:
1329     return false;
1330   default:
1331     return true;
1332   }
1333 }
1334 
1335 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1336   messageHandler().set_currStmtSource(source);
1337   currScope().AddSourceRange(source);
1338 }
1339 
1340 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1341   if (NeedsScope(x)) {
1342     PushScope(Scope::Kind::Block, nullptr);
1343   }
1344   return true;
1345 }
1346 
1347 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1348   if (NeedsScope(x)) {
1349     PopScope();
1350   }
1351 }
1352 
1353 // Walk the parse tree and resolve names to symbols.
1354 class ResolveNamesVisitor : public virtual ScopeHandler,
1355                             public ModuleVisitor,
1356                             public SubprogramVisitor,
1357                             public ConstructVisitor,
1358                             public OmpVisitor,
1359                             public AccVisitor {
1360 public:
1361   using AccVisitor::Post;
1362   using AccVisitor::Pre;
1363   using ArraySpecVisitor::Post;
1364   using ConstructVisitor::Post;
1365   using ConstructVisitor::Pre;
1366   using DeclarationVisitor::Post;
1367   using DeclarationVisitor::Pre;
1368   using ImplicitRulesVisitor::Post;
1369   using ImplicitRulesVisitor::Pre;
1370   using InterfaceVisitor::Post;
1371   using InterfaceVisitor::Pre;
1372   using ModuleVisitor::Post;
1373   using ModuleVisitor::Pre;
1374   using OmpVisitor::Post;
1375   using OmpVisitor::Pre;
1376   using ScopeHandler::Post;
1377   using ScopeHandler::Pre;
1378   using SubprogramVisitor::Post;
1379   using SubprogramVisitor::Pre;
1380 
1381   ResolveNamesVisitor(
1382       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1383       : BaseVisitor{context, *this, rules}, topScope_{top} {
1384     PushScope(top);
1385   }
1386 
1387   Scope &topScope() const { return topScope_; }
1388 
1389   // Default action for a parse tree node is to visit children.
1390   template <typename T> bool Pre(const T &) { return true; }
1391   template <typename T> void Post(const T &) {}
1392 
1393   bool Pre(const parser::SpecificationPart &);
1394   void Post(const parser::Program &);
1395   bool Pre(const parser::ImplicitStmt &);
1396   void Post(const parser::PointerObject &);
1397   void Post(const parser::AllocateObject &);
1398   bool Pre(const parser::PointerAssignmentStmt &);
1399   void Post(const parser::Designator &);
1400   template <typename A, typename B>
1401   void Post(const parser::LoopBounds<A, B> &x) {
1402     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1403   }
1404   void Post(const parser::ProcComponentRef &);
1405   bool Pre(const parser::FunctionReference &);
1406   bool Pre(const parser::CallStmt &);
1407   bool Pre(const parser::ImportStmt &);
1408   void Post(const parser::TypeGuardStmt &);
1409   bool Pre(const parser::StmtFunctionStmt &);
1410   bool Pre(const parser::DefinedOpName &);
1411   bool Pre(const parser::ProgramUnit &);
1412   void Post(const parser::AssignStmt &);
1413   void Post(const parser::AssignedGotoStmt &);
1414 
1415   // These nodes should never be reached: they are handled in ProgramUnit
1416   bool Pre(const parser::MainProgram &) {
1417     llvm_unreachable("This node is handled in ProgramUnit");
1418   }
1419   bool Pre(const parser::FunctionSubprogram &) {
1420     llvm_unreachable("This node is handled in ProgramUnit");
1421   }
1422   bool Pre(const parser::SubroutineSubprogram &) {
1423     llvm_unreachable("This node is handled in ProgramUnit");
1424   }
1425   bool Pre(const parser::SeparateModuleSubprogram &) {
1426     llvm_unreachable("This node is handled in ProgramUnit");
1427   }
1428   bool Pre(const parser::Module &) {
1429     llvm_unreachable("This node is handled in ProgramUnit");
1430   }
1431   bool Pre(const parser::Submodule &) {
1432     llvm_unreachable("This node is handled in ProgramUnit");
1433   }
1434   bool Pre(const parser::BlockData &) {
1435     llvm_unreachable("This node is handled in ProgramUnit");
1436   }
1437 
1438   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1439 
1440   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1441 
1442 private:
1443   // Kind of procedure we are expecting to see in a ProcedureDesignator
1444   std::optional<Symbol::Flag> expectedProcFlag_;
1445   std::optional<SourceName> prevImportStmt_;
1446   Scope &topScope_;
1447 
1448   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1449   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1450   void CreateGeneric(const parser::GenericSpec &);
1451   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1452   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1453   void CheckImports();
1454   void CheckImport(const SourceName &, const SourceName &);
1455   void HandleCall(Symbol::Flag, const parser::Call &);
1456   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1457   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1458   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1459   void ResolveSpecificationParts(ProgramTree &);
1460   void AddSubpNames(ProgramTree &);
1461   bool BeginScopeForNode(const ProgramTree &);
1462   void EndScopeForNode(const ProgramTree &);
1463   void FinishSpecificationParts(const ProgramTree &);
1464   void FinishDerivedTypeInstantiation(Scope &);
1465   void ResolveExecutionParts(const ProgramTree &);
1466 };
1467 
1468 // ImplicitRules implementation
1469 
1470 bool ImplicitRules::isImplicitNoneType() const {
1471   if (isImplicitNoneType_) {
1472     return true;
1473   } else if (map_.empty() && inheritFromParent_) {
1474     return parent_->isImplicitNoneType();
1475   } else {
1476     return false; // default if not specified
1477   }
1478 }
1479 
1480 bool ImplicitRules::isImplicitNoneExternal() const {
1481   if (isImplicitNoneExternal_) {
1482     return true;
1483   } else if (inheritFromParent_) {
1484     return parent_->isImplicitNoneExternal();
1485   } else {
1486     return false; // default if not specified
1487   }
1488 }
1489 
1490 const DeclTypeSpec *ImplicitRules::GetType(
1491     SourceName name, bool respectImplicitNoneType) const {
1492   char ch{name.begin()[0]};
1493   if (isImplicitNoneType_ && respectImplicitNoneType) {
1494     return nullptr;
1495   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1496     return &*it->second;
1497   } else if (inheritFromParent_) {
1498     return parent_->GetType(name, respectImplicitNoneType);
1499   } else if (ch >= 'i' && ch <= 'n') {
1500     return &context_.MakeNumericType(TypeCategory::Integer);
1501   } else if (ch >= 'a' && ch <= 'z') {
1502     return &context_.MakeNumericType(TypeCategory::Real);
1503   } else {
1504     return nullptr;
1505   }
1506 }
1507 
1508 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1509     parser::Location fromLetter, parser::Location toLetter) {
1510   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1511     auto res{map_.emplace(ch, type)};
1512     if (!res.second) {
1513       context_.Say(parser::CharBlock{fromLetter},
1514           "More than one implicit type specified for '%c'"_err_en_US, ch);
1515     }
1516     if (ch == *toLetter) {
1517       break;
1518     }
1519   }
1520 }
1521 
1522 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1523 // Return '\0' for the char after 'z'.
1524 char ImplicitRules::Incr(char ch) {
1525   switch (ch) {
1526   case 'i':
1527     return 'j';
1528   case 'r':
1529     return 's';
1530   case 'z':
1531     return '\0';
1532   default:
1533     return ch + 1;
1534   }
1535 }
1536 
1537 llvm::raw_ostream &operator<<(
1538     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1539   o << "ImplicitRules:\n";
1540   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1541     ShowImplicitRule(o, implicitRules, ch);
1542   }
1543   ShowImplicitRule(o, implicitRules, '_');
1544   ShowImplicitRule(o, implicitRules, '$');
1545   ShowImplicitRule(o, implicitRules, '@');
1546   return o;
1547 }
1548 void ShowImplicitRule(
1549     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1550   auto it{implicitRules.map_.find(ch)};
1551   if (it != implicitRules.map_.end()) {
1552     o << "  " << ch << ": " << *it->second << '\n';
1553   }
1554 }
1555 
1556 template <typename T> void BaseVisitor::Walk(const T &x) {
1557   parser::Walk(x, *this_);
1558 }
1559 
1560 void BaseVisitor::MakePlaceholder(
1561     const parser::Name &name, MiscDetails::Kind kind) {
1562   if (!name.symbol) {
1563     name.symbol = &context_->globalScope().MakeSymbol(
1564         name.source, Attrs{}, MiscDetails{kind});
1565   }
1566 }
1567 
1568 // AttrsVisitor implementation
1569 
1570 bool AttrsVisitor::BeginAttrs() {
1571   CHECK(!attrs_);
1572   attrs_ = std::make_optional<Attrs>();
1573   return true;
1574 }
1575 Attrs AttrsVisitor::GetAttrs() {
1576   CHECK(attrs_);
1577   return *attrs_;
1578 }
1579 Attrs AttrsVisitor::EndAttrs() {
1580   Attrs result{GetAttrs()};
1581   attrs_.reset();
1582   passName_ = std::nullopt;
1583   bindName_.reset();
1584   return result;
1585 }
1586 
1587 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1588   if (!passName_) {
1589     return false;
1590   }
1591   std::visit(common::visitors{
1592                  [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1593                  [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1594                  [](auto &) { common::die("unexpected pass name"); },
1595              },
1596       symbol.details());
1597   return true;
1598 }
1599 
1600 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1601   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1602     return;
1603   }
1604   std::optional<std::string> label{
1605       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1606   // 18.9.2(2): discard leading and trailing blanks, ignore if all blank
1607   if (label) {
1608     auto first{label->find_first_not_of(" ")};
1609     if (first == std::string::npos) {
1610       // Empty NAME= means no binding at all (18.10.2p2)
1611       Say(currStmtSource().value(), "Blank binding label ignored"_en_US);
1612       return;
1613     }
1614     auto last{label->find_last_not_of(" ")};
1615     label = label->substr(first, last - first + 1);
1616   } else {
1617     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1618   }
1619   symbol.SetBindName(std::move(*label));
1620 }
1621 
1622 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1623   CHECK(attrs_);
1624   if (CheckAndSet(Attr::BIND_C)) {
1625     if (x.v) {
1626       bindName_ = EvaluateExpr(*x.v);
1627     }
1628   }
1629 }
1630 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1631   CHECK(attrs_);
1632   CheckAndSet(IntentSpecToAttr(x));
1633   return false;
1634 }
1635 bool AttrsVisitor::Pre(const parser::Pass &x) {
1636   if (CheckAndSet(Attr::PASS)) {
1637     if (x.v) {
1638       passName_ = x.v->source;
1639       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1640     }
1641   }
1642   return false;
1643 }
1644 
1645 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1646 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1647   if (attrs_->test(attrName)) {
1648     Say(currStmtSource().value(),
1649         "Attribute '%s' cannot be used more than once"_en_US,
1650         AttrToString(attrName));
1651     return true;
1652   }
1653   return false;
1654 }
1655 
1656 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1657 // name attributes that cannot be used on the same declaration
1658 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1659   if ((attrName == attr1 && attrs_->test(attr2)) ||
1660       (attrName == attr2 && attrs_->test(attr1))) {
1661     Say(currStmtSource().value(),
1662         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1663         AttrToString(attr1), AttrToString(attr2));
1664     return true;
1665   }
1666   return false;
1667 }
1668 // C759, C1543
1669 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1670   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1671       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1672       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1673       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1674       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1675       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1676       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1677 }
1678 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1679   CHECK(attrs_);
1680   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1681     return false;
1682   }
1683   attrs_->set(attrName);
1684   return true;
1685 }
1686 
1687 // DeclTypeSpecVisitor implementation
1688 
1689 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1690   return state_.declTypeSpec;
1691 }
1692 
1693 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1694   CHECK(!state_.expectDeclTypeSpec);
1695   CHECK(!state_.declTypeSpec);
1696   state_.expectDeclTypeSpec = true;
1697 }
1698 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1699   CHECK(state_.expectDeclTypeSpec);
1700   state_ = {};
1701 }
1702 
1703 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1704     DeclTypeSpec::Category category) {
1705   CHECK(state_.expectDeclTypeSpec);
1706   state_.derived.category = category;
1707 }
1708 
1709 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1710   BeginDeclTypeSpec();
1711   return true;
1712 }
1713 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1714   EndDeclTypeSpec();
1715 }
1716 
1717 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1718   // Record the resolved DeclTypeSpec in the parse tree for use by
1719   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1720   // The grammar ensures that it's an intrinsic or derived type spec,
1721   // not TYPE(*) or CLASS(*) or CLASS(T).
1722   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1723     switch (spec->category()) {
1724     case DeclTypeSpec::Numeric:
1725     case DeclTypeSpec::Logical:
1726     case DeclTypeSpec::Character:
1727       typeSpec.declTypeSpec = spec;
1728       break;
1729     case DeclTypeSpec::TypeDerived:
1730       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1731         CheckForAbstractType(derived->typeSymbol()); // C703
1732         typeSpec.declTypeSpec = spec;
1733       }
1734       break;
1735     default:
1736       CRASH_NO_CASE;
1737     }
1738   }
1739 }
1740 
1741 void DeclTypeSpecVisitor::Post(
1742     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1743   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1744 }
1745 void DeclTypeSpecVisitor::Post(
1746     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1747   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1748 }
1749 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1750   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1751 }
1752 
1753 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1754   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1755     Say("ABSTRACT derived type may not be used here"_err_en_US);
1756   }
1757 }
1758 
1759 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1760   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1761 }
1762 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1763   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1764 }
1765 
1766 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1767 // and save it in state_.declTypeSpec.
1768 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1769   CHECK(state_.expectDeclTypeSpec);
1770   CHECK(!state_.declTypeSpec);
1771   state_.declTypeSpec = &declTypeSpec;
1772 }
1773 
1774 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1775     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1776   return AnalyzeKindSelector(context(), category, kind);
1777 }
1778 
1779 // MessageHandler implementation
1780 
1781 Message &MessageHandler::Say(MessageFixedText &&msg) {
1782   return context_->Say(currStmtSource().value(), std::move(msg));
1783 }
1784 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1785   return context_->Say(currStmtSource().value(), std::move(msg));
1786 }
1787 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1788   return Say(name, std::move(msg), name);
1789 }
1790 
1791 // ImplicitRulesVisitor implementation
1792 
1793 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1794   prevParameterStmt_ = currStmtSource();
1795 }
1796 
1797 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1798   bool result{
1799       std::visit(common::visitors{
1800                      [&](const std::list<ImplicitNoneNameSpec> &y) {
1801                        return HandleImplicitNone(y);
1802                      },
1803                      [&](const std::list<parser::ImplicitSpec> &) {
1804                        if (prevImplicitNoneType_) {
1805                          Say("IMPLICIT statement after IMPLICIT NONE or "
1806                              "IMPLICIT NONE(TYPE) statement"_err_en_US);
1807                          return false;
1808                        }
1809                        implicitRules_->set_isImplicitNoneType(false);
1810                        return true;
1811                      },
1812                  },
1813           x.u)};
1814   prevImplicit_ = currStmtSource();
1815   return result;
1816 }
1817 
1818 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1819   auto loLoc{std::get<parser::Location>(x.t)};
1820   auto hiLoc{loLoc};
1821   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1822     hiLoc = *hiLocOpt;
1823     if (*hiLoc < *loLoc) {
1824       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1825           std::string(hiLoc, 1), std::string(loLoc, 1));
1826       return false;
1827     }
1828   }
1829   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1830   return false;
1831 }
1832 
1833 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1834   BeginDeclTypeSpec();
1835   set_allowForwardReferenceToDerivedType(true);
1836   return true;
1837 }
1838 
1839 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1840   EndDeclTypeSpec();
1841 }
1842 
1843 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1844   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1845   prevImplicit_ = std::nullopt;
1846   prevImplicitNone_ = std::nullopt;
1847   prevImplicitNoneType_ = std::nullopt;
1848   prevParameterStmt_ = std::nullopt;
1849 }
1850 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1851   // find or create implicit rules for this scope
1852   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1853   SetScope(scope);
1854 }
1855 
1856 // TODO: for all of these errors, reference previous statement too
1857 bool ImplicitRulesVisitor::HandleImplicitNone(
1858     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1859   if (prevImplicitNone_) {
1860     Say("More than one IMPLICIT NONE statement"_err_en_US);
1861     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1862     return false;
1863   }
1864   if (prevParameterStmt_) {
1865     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1866     return false;
1867   }
1868   prevImplicitNone_ = currStmtSource();
1869   bool implicitNoneTypeNever{
1870       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1871   if (nameSpecs.empty()) {
1872     if (!implicitNoneTypeNever) {
1873       prevImplicitNoneType_ = currStmtSource();
1874       implicitRules_->set_isImplicitNoneType(true);
1875       if (prevImplicit_) {
1876         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1877         return false;
1878       }
1879     }
1880   } else {
1881     int sawType{0};
1882     int sawExternal{0};
1883     for (const auto noneSpec : nameSpecs) {
1884       switch (noneSpec) {
1885       case ImplicitNoneNameSpec::External:
1886         implicitRules_->set_isImplicitNoneExternal(true);
1887         ++sawExternal;
1888         break;
1889       case ImplicitNoneNameSpec::Type:
1890         if (!implicitNoneTypeNever) {
1891           prevImplicitNoneType_ = currStmtSource();
1892           implicitRules_->set_isImplicitNoneType(true);
1893           if (prevImplicit_) {
1894             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1895             return false;
1896           }
1897           ++sawType;
1898         }
1899         break;
1900       }
1901     }
1902     if (sawType > 1) {
1903       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1904       return false;
1905     }
1906     if (sawExternal > 1) {
1907       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1908       return false;
1909     }
1910   }
1911   return true;
1912 }
1913 
1914 // ArraySpecVisitor implementation
1915 
1916 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1917   CHECK(arraySpec_.empty());
1918   arraySpec_ = AnalyzeArraySpec(context(), x);
1919 }
1920 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1921   CHECK(arraySpec_.empty());
1922   arraySpec_ = AnalyzeArraySpec(context(), x);
1923 }
1924 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1925   CHECK(coarraySpec_.empty());
1926   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1927 }
1928 
1929 const ArraySpec &ArraySpecVisitor::arraySpec() {
1930   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
1931 }
1932 const ArraySpec &ArraySpecVisitor::coarraySpec() {
1933   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
1934 }
1935 void ArraySpecVisitor::BeginArraySpec() {
1936   CHECK(arraySpec_.empty());
1937   CHECK(coarraySpec_.empty());
1938   CHECK(attrArraySpec_.empty());
1939   CHECK(attrCoarraySpec_.empty());
1940 }
1941 void ArraySpecVisitor::EndArraySpec() {
1942   CHECK(arraySpec_.empty());
1943   CHECK(coarraySpec_.empty());
1944   attrArraySpec_.clear();
1945   attrCoarraySpec_.clear();
1946 }
1947 void ArraySpecVisitor::PostAttrSpec() {
1948   // Save dimension/codimension from attrs so we can process array/coarray-spec
1949   // on the entity-decl
1950   if (!arraySpec_.empty()) {
1951     if (attrArraySpec_.empty()) {
1952       attrArraySpec_ = arraySpec_;
1953       arraySpec_.clear();
1954     } else {
1955       Say(currStmtSource().value(),
1956           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
1957     }
1958   }
1959   if (!coarraySpec_.empty()) {
1960     if (attrCoarraySpec_.empty()) {
1961       attrCoarraySpec_ = coarraySpec_;
1962       coarraySpec_.clear();
1963     } else {
1964       Say(currStmtSource().value(),
1965           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
1966     }
1967   }
1968 }
1969 
1970 // ScopeHandler implementation
1971 
1972 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
1973   SayAlreadyDeclared(name.source, prev);
1974 }
1975 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
1976   if (context().HasError(prev)) {
1977     // don't report another error about prev
1978   } else {
1979     if (const auto *details{prev.detailsIf<UseDetails>()}) {
1980       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
1981           .Attach(details->location(),
1982               "It is use-associated with '%s' in module '%s'"_err_en_US,
1983               details->symbol().name(), GetUsedModule(*details).name());
1984     } else {
1985       SayAlreadyDeclared(name, prev.name());
1986     }
1987     context().SetError(prev);
1988   }
1989 }
1990 void ScopeHandler::SayAlreadyDeclared(
1991     const SourceName &name1, const SourceName &name2) {
1992   if (name1.begin() < name2.begin()) {
1993     SayAlreadyDeclared(name2, name1);
1994   } else {
1995     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
1996         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
1997   }
1998 }
1999 
2000 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
2001     MessageFixedText &&msg1, MessageFixedText &&msg2) {
2002   Say2(name, std::move(msg1), symbol, std::move(msg2));
2003   context().SetError(symbol, msg1.isFatal());
2004 }
2005 
2006 void ScopeHandler::SayWithDecl(
2007     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
2008   SayWithReason(name, symbol, std::move(msg),
2009       symbol.test(Symbol::Flag::Implicit) ? "Implicit declaration of '%s'"_en_US
2010                                           : "Declaration of '%s'"_en_US);
2011 }
2012 
2013 void ScopeHandler::SayLocalMustBeVariable(
2014     const parser::Name &name, Symbol &symbol) {
2015   SayWithDecl(name, symbol,
2016       "The name '%s' must be a variable to appear"
2017       " in a locality-spec"_err_en_US);
2018 }
2019 
2020 void ScopeHandler::SayDerivedType(
2021     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2022   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2023   Say(name, std::move(msg), name, typeSymbol.name())
2024       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2025           typeSymbol.name());
2026 }
2027 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2028     const SourceName &name2, MessageFixedText &&msg2) {
2029   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2030 }
2031 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2032     Symbol &symbol, MessageFixedText &&msg2) {
2033   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2034   context().SetError(symbol, msg1.isFatal());
2035 }
2036 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2037     Symbol &symbol, MessageFixedText &&msg2) {
2038   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2039   context().SetError(symbol, msg1.isFatal());
2040 }
2041 
2042 // This is essentially GetProgramUnitContaining(), but it can return
2043 // a mutable Scope &, it ignores statement functions, and it fails
2044 // gracefully for error recovery (returning the original Scope).
2045 template <typename T> static T &GetInclusiveScope(T &scope) {
2046   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2047     switch (s->kind()) {
2048     case Scope::Kind::Module:
2049     case Scope::Kind::MainProgram:
2050     case Scope::Kind::Subprogram:
2051     case Scope::Kind::BlockData:
2052       if (!s->IsStmtFunction()) {
2053         return *s;
2054       }
2055       break;
2056     default:;
2057     }
2058   }
2059   return scope;
2060 }
2061 
2062 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2063 
2064 Scope *ScopeHandler::GetHostProcedure() {
2065   Scope &parent{InclusiveScope().parent()};
2066   switch (parent.kind()) {
2067   case Scope::Kind::Subprogram:
2068     return &parent;
2069   case Scope::Kind::MainProgram:
2070     return &parent;
2071   default:
2072     return nullptr;
2073   }
2074 }
2075 
2076 Scope &ScopeHandler::NonDerivedTypeScope() {
2077   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2078 }
2079 
2080 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2081   PushScope(currScope().MakeScope(kind, symbol));
2082 }
2083 void ScopeHandler::PushScope(Scope &scope) {
2084   currScope_ = &scope;
2085   auto kind{currScope_->kind()};
2086   if (kind != Scope::Kind::Block) {
2087     BeginScope(scope);
2088   }
2089   // The name of a module or submodule cannot be "used" in its scope,
2090   // as we read 19.3.1(2), so we allow the name to be used as a local
2091   // identifier in the module or submodule too.  Same with programs
2092   // (14.1(3)) and BLOCK DATA.
2093   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2094       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2095     if (auto *symbol{scope.symbol()}) {
2096       // Create a dummy symbol so we can't create another one with the same
2097       // name. It might already be there if we previously pushed the scope.
2098       if (!FindInScope(scope, symbol->name())) {
2099         auto &newSymbol{MakeSymbol(symbol->name())};
2100         if (kind == Scope::Kind::Subprogram) {
2101           // Allow for recursive references.  If this symbol is a function
2102           // without an explicit RESULT(), this new symbol will be discarded
2103           // and replaced with an object of the same name.
2104           newSymbol.set_details(HostAssocDetails{*symbol});
2105         } else {
2106           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2107         }
2108       }
2109     }
2110   }
2111 }
2112 void ScopeHandler::PopScope() {
2113   // Entities that are not yet classified as objects or procedures are now
2114   // assumed to be objects.
2115   // TODO: Statement functions
2116   for (auto &pair : currScope()) {
2117     ConvertToObjectEntity(*pair.second);
2118   }
2119   SetScope(currScope_->parent());
2120 }
2121 void ScopeHandler::SetScope(Scope &scope) {
2122   currScope_ = &scope;
2123   ImplicitRulesVisitor::SetScope(InclusiveScope());
2124 }
2125 
2126 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2127   return FindSymbol(currScope(), name);
2128 }
2129 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2130   if (scope.IsDerivedType()) {
2131     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2132       if (!symbol->has<ProcBindingDetails>() &&
2133           !symbol->test(Symbol::Flag::ParentComp)) {
2134         return Resolve(name, symbol);
2135       }
2136     }
2137     return FindSymbol(scope.parent(), name);
2138   } else {
2139     // In EQUIVALENCE statements only resolve names in the local scope, see
2140     // 19.5.1.4, paragraph 2, item (10)
2141     return Resolve(name,
2142         inEquivalenceStmt_ ? FindInScope(scope, name)
2143                            : scope.FindSymbol(name.source));
2144   }
2145 }
2146 
2147 Symbol &ScopeHandler::MakeSymbol(
2148     Scope &scope, const SourceName &name, Attrs attrs) {
2149   if (Symbol * symbol{FindInScope(scope, name)}) {
2150     symbol->attrs() |= attrs;
2151     return *symbol;
2152   } else {
2153     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2154     CHECK(pair.second); // name was not found, so must be able to add
2155     return *pair.first->second;
2156   }
2157 }
2158 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2159   return MakeSymbol(currScope(), name, attrs);
2160 }
2161 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2162   return Resolve(name, MakeSymbol(name.source, attrs));
2163 }
2164 Symbol &ScopeHandler::MakeHostAssocSymbol(
2165     const parser::Name &name, const Symbol &hostSymbol) {
2166   Symbol &symbol{*NonDerivedTypeScope()
2167                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2168                       .first->second};
2169   name.symbol = &symbol;
2170   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2171   symbol.flags() = hostSymbol.flags();
2172   return symbol;
2173 }
2174 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2175   CHECK(!FindInScope(name));
2176   return MakeSymbol(currScope(), name, symbol.attrs());
2177 }
2178 
2179 // Look for name only in scope, not in enclosing scopes.
2180 Symbol *ScopeHandler::FindInScope(
2181     const Scope &scope, const parser::Name &name) {
2182   return Resolve(name, FindInScope(scope, name.source));
2183 }
2184 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2185   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2186   for (const std::string &n : GetAllNames(context(), name)) {
2187     auto it{scope.find(SourceName{n})};
2188     if (it != scope.end()) {
2189       return &*it->second;
2190     }
2191   }
2192   return nullptr;
2193 }
2194 
2195 // Find a component or type parameter by name in a derived type or its parents.
2196 Symbol *ScopeHandler::FindInTypeOrParents(
2197     const Scope &scope, const parser::Name &name) {
2198   return Resolve(name, scope.FindComponent(name.source));
2199 }
2200 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2201   return FindInTypeOrParents(currScope(), name);
2202 }
2203 
2204 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2205   currScope().erase(name.source);
2206   name.symbol = nullptr;
2207 }
2208 
2209 static bool NeedsType(const Symbol &symbol) {
2210   return !symbol.GetType() &&
2211       std::visit(common::visitors{
2212                      [](const EntityDetails &) { return true; },
2213                      [](const ObjectEntityDetails &) { return true; },
2214                      [](const AssocEntityDetails &) { return true; },
2215                      [&](const ProcEntityDetails &p) {
2216                        return symbol.test(Symbol::Flag::Function) &&
2217                            !symbol.attrs().test(Attr::INTRINSIC) &&
2218                            !p.interface().type() && !p.interface().symbol();
2219                      },
2220                      [](const auto &) { return false; },
2221                  },
2222           symbol.details());
2223 }
2224 
2225 void ScopeHandler::ApplyImplicitRules(
2226     Symbol &symbol, bool allowForwardReference) {
2227   if (context().HasError(symbol) || !NeedsType(symbol)) {
2228     return;
2229   }
2230   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2231     symbol.set(Symbol::Flag::Implicit);
2232     symbol.SetType(*type);
2233     return;
2234   }
2235   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2236     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2237     if (symbol.test(Symbol::Flag::Function)) {
2238       functionOrSubroutineFlag = Symbol::Flag::Function;
2239     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2240       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2241     }
2242     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2243       // type will be determined in expression semantics
2244       AcquireIntrinsicProcedureFlags(symbol);
2245       return;
2246     }
2247   }
2248   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2249     return;
2250   }
2251   if (!context().HasError(symbol)) {
2252     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2253     context().SetError(symbol);
2254   }
2255 }
2256 
2257 // Extension: Allow forward references to scalar integer dummy arguments
2258 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2259 // what would otherwise have been their implicit type is default INTEGER.
2260 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2261   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2262       symbol.Rank() != 0 ||
2263       !context().languageFeatures().IsEnabled(
2264           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2265     return false;
2266   }
2267   const DeclTypeSpec *type{
2268       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2269   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2270     return false;
2271   }
2272   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2273   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2274     return false;
2275   }
2276   if (!ConvertToObjectEntity(symbol)) {
2277     return false;
2278   }
2279   // TODO: check no INTENT(OUT)?
2280   if (context().languageFeatures().ShouldWarn(
2281           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2282     Say(symbol.name(),
2283         "Dummy argument '%s' was used without being explicitly typed"_en_US,
2284         symbol.name());
2285   }
2286   symbol.set(Symbol::Flag::Implicit);
2287   symbol.SetType(*type);
2288   return true;
2289 }
2290 
2291 // Ensure that the symbol for an intrinsic procedure is marked with
2292 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2293 // appropriate.
2294 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2295   symbol.attrs().set(Attr::INTRINSIC);
2296   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2297   case evaluate::IntrinsicClass::elementalFunction:
2298   case evaluate::IntrinsicClass::elementalSubroutine:
2299     symbol.attrs().set(Attr::ELEMENTAL);
2300     symbol.attrs().set(Attr::PURE);
2301     break;
2302   case evaluate::IntrinsicClass::impureSubroutine:
2303     break;
2304   default:
2305     symbol.attrs().set(Attr::PURE);
2306   }
2307 }
2308 
2309 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2310     Symbol &symbol, bool respectImplicitNoneType) {
2311   const Scope *scope{&symbol.owner()};
2312   if (scope->IsGlobal()) {
2313     scope = &currScope();
2314   }
2315   scope = &GetInclusiveScope(*scope);
2316   const auto *type{implicitRulesMap_->at(scope).GetType(
2317       symbol.name(), respectImplicitNoneType)};
2318   if (type) {
2319     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2320       // Resolve any forward-referenced derived type; a quick no-op else.
2321       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2322       instantiatable.Instantiate(currScope());
2323     }
2324   }
2325   return type;
2326 }
2327 
2328 // Convert symbol to be a ObjectEntity or return false if it can't be.
2329 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2330   if (symbol.has<ObjectEntityDetails>()) {
2331     // nothing to do
2332   } else if (symbol.has<UnknownDetails>()) {
2333     symbol.set_details(ObjectEntityDetails{});
2334   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2335     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2336   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2337     return useDetails->symbol().has<ObjectEntityDetails>();
2338   } else {
2339     return false;
2340   }
2341   return true;
2342 }
2343 // Convert symbol to be a ProcEntity or return false if it can't be.
2344 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2345   if (symbol.has<ProcEntityDetails>()) {
2346     // nothing to do
2347   } else if (symbol.has<UnknownDetails>()) {
2348     symbol.set_details(ProcEntityDetails{});
2349   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2350     symbol.set_details(ProcEntityDetails{std::move(*details)});
2351     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2352       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2353       symbol.set(Symbol::Flag::Function);
2354     }
2355   } else {
2356     return false;
2357   }
2358   return true;
2359 }
2360 
2361 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2362     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2363   KindExpr value{GetKindParamExpr(category, kind)};
2364   if (auto known{evaluate::ToInt64(value)}) {
2365     return context().MakeNumericType(category, static_cast<int>(*known));
2366   } else {
2367     return currScope_->MakeNumericType(category, std::move(value));
2368   }
2369 }
2370 
2371 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2372     const std::optional<parser::KindSelector> &kind) {
2373   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2374   if (auto known{evaluate::ToInt64(value)}) {
2375     return context().MakeLogicalType(static_cast<int>(*known));
2376   } else {
2377     return currScope_->MakeLogicalType(std::move(value));
2378   }
2379 }
2380 
2381 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2382   if (inSpecificationPart_ && name.symbol) {
2383     auto kind{currScope().kind()};
2384     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2385         kind == Scope::Kind::Block) {
2386       bool isHostAssociated{&name.symbol->owner() == &currScope()
2387               ? name.symbol->has<HostAssocDetails>()
2388               : name.symbol->owner().Contains(currScope())};
2389       if (isHostAssociated) {
2390         specPartState_.forwardRefs.insert(name.source);
2391       }
2392     }
2393   }
2394 }
2395 
2396 std::optional<SourceName> ScopeHandler::HadForwardRef(
2397     const Symbol &symbol) const {
2398   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2399   if (iter != specPartState_.forwardRefs.end()) {
2400     return *iter;
2401   }
2402   return std::nullopt;
2403 }
2404 
2405 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2406   if (!context().HasError(symbol)) {
2407     if (auto fwdRef{HadForwardRef(symbol)}) {
2408       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2409       if (outer && symbol.has<UseDetails>() &&
2410           &symbol.GetUltimate() == &outer->GetUltimate()) {
2411         // e.g. IMPORT of host's USE association
2412         return false;
2413       }
2414       Say(*fwdRef,
2415           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2416           *fwdRef)
2417           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2418       context().SetError(symbol);
2419       return true;
2420     }
2421     if (IsDummy(symbol) && isImplicitNoneType() &&
2422         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2423       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2424       // ApplyImplicitRules() due to use in a specification expression,
2425       // and no explicit type declaration appeared later.
2426       Say(symbol.name(),
2427           "No explicit type declared for dummy argument '%s'"_err_en_US);
2428       context().SetError(symbol);
2429       return true;
2430     }
2431   }
2432   return false;
2433 }
2434 
2435 void ScopeHandler::MakeExternal(Symbol &symbol) {
2436   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2437     symbol.attrs().set(Attr::EXTERNAL);
2438     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2439       Say(symbol.name(),
2440           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2441           symbol.name());
2442     }
2443   }
2444 }
2445 
2446 // ModuleVisitor implementation
2447 
2448 bool ModuleVisitor::Pre(const parser::Only &x) {
2449   std::visit(common::visitors{
2450                  [&](const Indirection<parser::GenericSpec> &generic) {
2451                    GenericSpecInfo genericSpecInfo{generic.value()};
2452                    AddUseOnly(genericSpecInfo.symbolName());
2453                    AddUse(genericSpecInfo);
2454                  },
2455                  [&](const parser::Name &name) {
2456                    AddUseOnly(name.source);
2457                    Resolve(name, AddUse(name.source, name.source).use);
2458                  },
2459                  [&](const parser::Rename &rename) { Walk(rename); },
2460              },
2461       x.u);
2462   return false;
2463 }
2464 
2465 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2466   const auto &localName{std::get<0>(x.t)};
2467   const auto &useName{std::get<1>(x.t)};
2468   AddUseRename(useName.source);
2469   SymbolRename rename{AddUse(localName.source, useName.source)};
2470   if (rename.use) {
2471     EraseRenamedSymbol(*rename.use);
2472   }
2473   Resolve(useName, rename.use);
2474   Resolve(localName, rename.local);
2475   return false;
2476 }
2477 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2478   const parser::DefinedOpName &local{std::get<0>(x.t)};
2479   const parser::DefinedOpName &use{std::get<1>(x.t)};
2480   GenericSpecInfo localInfo{local};
2481   GenericSpecInfo useInfo{use};
2482   if (IsIntrinsicOperator(context(), local.v.source)) {
2483     Say(local.v,
2484         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2485   } else if (IsLogicalConstant(context(), local.v.source)) {
2486     Say(local.v,
2487         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2488   } else {
2489     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2490     if (rename.use) {
2491       EraseRenamedSymbol(*rename.use);
2492     }
2493     useInfo.Resolve(rename.use);
2494     localInfo.Resolve(rename.local);
2495   }
2496   return false;
2497 }
2498 
2499 // Set useModuleScope_ to the Scope of the module being used.
2500 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2501   std::optional<bool> isIntrinsic;
2502   if (x.nature) {
2503     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2504     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2505   } else if (currScope().IsModule() && currScope().symbol() &&
2506       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2507     // Intrinsic modules USE only other intrinsic modules
2508     isIntrinsic = true;
2509   }
2510   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2511   if (!useModuleScope_) {
2512     return false;
2513   }
2514   // use the name from this source file
2515   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2516   return true;
2517 }
2518 
2519 void ModuleVisitor::Post(const parser::UseStmt &x) {
2520   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2521     // Not a use-only: collect the names that were used in renames,
2522     // then add a use for each public name that was not renamed.
2523     std::set<SourceName> useNames;
2524     for (const auto &rename : *list) {
2525       std::visit(common::visitors{
2526                      [&](const parser::Rename::Names &names) {
2527                        useNames.insert(std::get<1>(names.t).source);
2528                      },
2529                      [&](const parser::Rename::Operators &ops) {
2530                        useNames.insert(std::get<1>(ops.t).v.source);
2531                      },
2532                  },
2533           rename.u);
2534     }
2535     for (const auto &[name, symbol] : *useModuleScope_) {
2536       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2537           (!symbol->attrs().test(Attr::INTRINSIC) ||
2538               symbol->has<UseDetails>()) &&
2539           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2540         SourceName location{x.moduleName.source};
2541         if (auto *localSymbol{FindInScope(name)}) {
2542           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2543         } else {
2544           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2545         }
2546       }
2547     }
2548   }
2549   useModuleScope_ = nullptr;
2550 }
2551 
2552 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2553     const SourceName &localName, const SourceName &useName) {
2554   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2555 }
2556 
2557 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2558     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2559   if (!useModuleScope_) {
2560     return {}; // error occurred finding module
2561   }
2562   if (!useSymbol) {
2563     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2564         useModuleScope_->GetName().value());
2565     return {};
2566   }
2567   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2568       !FindModuleFileContaining(currScope())) {
2569     // Privacy is not enforced in module files so that generic interfaces
2570     // can be resolved to private specific procedures in specification
2571     // expressions.
2572     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2573         useModuleScope_->GetName().value());
2574     return {};
2575   }
2576   auto &localSymbol{MakeSymbol(localName)};
2577   DoAddUse(useName, localName, localSymbol, *useSymbol);
2578   return {&localSymbol, useSymbol};
2579 }
2580 
2581 // symbol must be either a Use or a Generic formed by merging two uses.
2582 // Convert it to a UseError with this additional location.
2583 static void ConvertToUseError(
2584     Symbol &symbol, const SourceName &location, const Scope &module) {
2585   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2586   if (!useDetails) {
2587     auto &genericDetails{symbol.get<GenericDetails>()};
2588     useDetails = &genericDetails.uses().at(0)->get<UseDetails>();
2589   }
2590   symbol.set_details(
2591       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2592 }
2593 
2594 // If a symbol has previously been USE-associated and did not appear in a USE
2595 // ONLY clause, erase it from the current scope.  This is needed when a name
2596 // appears in a USE rename clause.
2597 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2598   const SourceName &name{useSymbol.name()};
2599   if (const Symbol * symbol{FindInScope(name)}) {
2600     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2601       const Symbol &moduleSymbol{useDetails->symbol()};
2602       if (moduleSymbol.name() == name &&
2603           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2604           !IsUseOnly(name)) {
2605         EraseSymbol(*symbol);
2606       }
2607     }
2608   }
2609 }
2610 
2611 void ModuleVisitor::DoAddUse(const SourceName &location,
2612     const SourceName &localName, Symbol &localSymbol, const Symbol &useSymbol) {
2613   if (localName != useSymbol.name()) {
2614     EraseRenamedSymbol(useSymbol);
2615   }
2616   localSymbol.attrs() = useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2617   localSymbol.flags() = useSymbol.flags();
2618   const Symbol &useUltimate{useSymbol.GetUltimate()};
2619   if (auto *useDetails{localSymbol.detailsIf<UseDetails>()}) {
2620     const Symbol &localUltimate{localSymbol.GetUltimate()};
2621     if (localUltimate.owner() == useUltimate.owner()) {
2622       // use-associating the same symbol again -- ok
2623     } else if (localUltimate.has<GenericDetails>() &&
2624         useUltimate.has<GenericDetails>()) {
2625       // use-associating generics with the same names: merge them into a
2626       // new generic in this scope
2627       auto generic1{localUltimate.get<GenericDetails>()};
2628       AddGenericUse(generic1, localName, useUltimate);
2629       generic1.AddUse(localSymbol);
2630       // useSymbol has specific g and so does generic1
2631       auto &generic2{useUltimate.get<GenericDetails>()};
2632       if (generic1.derivedType() && generic2.derivedType() &&
2633           generic1.derivedType() != generic2.derivedType()) {
2634         Say(location,
2635             "Generic interface '%s' has ambiguous derived types"
2636             " from modules '%s' and '%s'"_err_en_US,
2637             localSymbol.name(), GetUsedModule(*useDetails).name(),
2638             useUltimate.owner().GetName().value());
2639         context().SetError(localSymbol);
2640       } else {
2641         generic1.CopyFrom(generic2);
2642       }
2643       EraseSymbol(localSymbol);
2644       MakeSymbol(localSymbol.name(), localSymbol.attrs(), std::move(generic1));
2645     } else {
2646       ConvertToUseError(localSymbol, location, *useModuleScope_);
2647     }
2648   } else if (auto *genericDetails{localSymbol.detailsIf<GenericDetails>()}) {
2649     if (const auto *useDetails{useUltimate.detailsIf<GenericDetails>()}) {
2650       AddGenericUse(*genericDetails, localName, useUltimate);
2651       if (genericDetails->derivedType() && useDetails->derivedType() &&
2652           genericDetails->derivedType() != useDetails->derivedType()) {
2653         Say(location,
2654             "Generic interface '%s' has ambiguous derived types"
2655             " from modules '%s' and '%s'"_err_en_US,
2656             localSymbol.name(),
2657             genericDetails->derivedType()->owner().GetName().value(),
2658             useDetails->derivedType()->owner().GetName().value());
2659       } else {
2660         genericDetails->CopyFrom(*useDetails);
2661       }
2662     } else {
2663       ConvertToUseError(localSymbol, location, *useModuleScope_);
2664     }
2665   } else if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2666     details->add_occurrence(location, *useModuleScope_);
2667   } else if (!localSymbol.has<UnknownDetails>()) {
2668     Say(location,
2669         "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2670         localName)
2671         .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2672             localName);
2673   } else {
2674     localSymbol.set_details(UseDetails{localName, useSymbol});
2675   }
2676 }
2677 
2678 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2679   if (useModuleScope_) {
2680     const auto &name{info.symbolName()};
2681     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2682     info.Resolve(rename.use);
2683   }
2684 }
2685 
2686 // Create a UseDetails symbol for this USE and add it to generic
2687 void ModuleVisitor::AddGenericUse(
2688     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2689   generic.AddUse(currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol}));
2690 }
2691 
2692 // Enforce C1406
2693 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2694     SourceName name, bool isIntrinsic) {
2695   if (isIntrinsic) {
2696     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2697         iter != explicitNonIntrinsicUses_.end()) {
2698       Say(name,
2699           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2700           name)
2701           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2702     }
2703     explicitIntrinsicUses_.insert(name);
2704   } else {
2705     if (auto iter{explicitIntrinsicUses_.find(name)};
2706         iter != explicitIntrinsicUses_.end()) {
2707       Say(name,
2708           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2709           name)
2710           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2711     }
2712     explicitNonIntrinsicUses_.insert(name);
2713   }
2714 }
2715 
2716 bool ModuleVisitor::BeginSubmodule(
2717     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2718   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2719   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2720   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2721   if (!ancestor) {
2722     return false;
2723   }
2724   Scope *parentScope{parentName
2725           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2726           : ancestor};
2727   if (!parentScope) {
2728     return false;
2729   }
2730   PushScope(*parentScope); // submodule is hosted in parent
2731   BeginModule(name, true);
2732   if (!ancestor->AddSubmodule(name.source, currScope())) {
2733     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2734         ancestorName.source, name.source);
2735   }
2736   return true;
2737 }
2738 
2739 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2740   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2741   auto &details{symbol.get<ModuleDetails>()};
2742   PushScope(Scope::Kind::Module, &symbol);
2743   details.set_scope(&currScope());
2744   defaultAccess_ = Attr::PUBLIC;
2745   prevAccessStmt_ = std::nullopt;
2746 }
2747 
2748 // Find a module or submodule by name and return its scope.
2749 // If ancestor is present, look for a submodule of that ancestor module.
2750 // May have to read a .mod file to find it.
2751 // If an error occurs, report it and return nullptr.
2752 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2753     std::optional<bool> isIntrinsic, Scope *ancestor) {
2754   ModFileReader reader{context()};
2755   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2756   if (!scope) {
2757     return nullptr;
2758   }
2759   if (scope->kind() != Scope::Kind::Module) {
2760     Say(name, "'%s' is not a module"_err_en_US);
2761     return nullptr;
2762   }
2763   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2764     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2765   }
2766   Resolve(name, scope->symbol());
2767   return scope;
2768 }
2769 
2770 void ModuleVisitor::ApplyDefaultAccess() {
2771   for (auto &pair : currScope()) {
2772     Symbol &symbol = *pair.second;
2773     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2774       symbol.attrs().set(defaultAccess_);
2775     }
2776   }
2777 }
2778 
2779 // InterfaceVistor implementation
2780 
2781 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2782   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2783   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2784   return BeginAttrs();
2785 }
2786 
2787 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2788 
2789 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2790   genericInfo_.pop();
2791 }
2792 
2793 // Create a symbol in genericSymbol_ for this GenericSpec.
2794 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2795   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
2796     SetGenericSymbol(*symbol);
2797   }
2798   return false;
2799 }
2800 
2801 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2802   if (!isGeneric()) {
2803     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2804     return false;
2805   }
2806   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2807   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2808   AddSpecificProcs(names, kind);
2809   return false;
2810 }
2811 
2812 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2813   genericInfo_.emplace(/*isInterface*/ false);
2814   return true;
2815 }
2816 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2817   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2818     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2819   }
2820   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2821   AddSpecificProcs(names, ProcedureKind::Procedure);
2822   genericInfo_.pop();
2823 }
2824 
2825 bool InterfaceVisitor::inInterfaceBlock() const {
2826   return !genericInfo_.empty() && GetGenericInfo().isInterface;
2827 }
2828 bool InterfaceVisitor::isGeneric() const {
2829   return !genericInfo_.empty() && GetGenericInfo().symbol;
2830 }
2831 bool InterfaceVisitor::isAbstract() const {
2832   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
2833 }
2834 
2835 void InterfaceVisitor::AddSpecificProcs(
2836     const std::list<parser::Name> &names, ProcedureKind kind) {
2837   for (const auto &name : names) {
2838     specificProcs_.emplace(
2839         GetGenericInfo().symbol, std::make_pair(&name, kind));
2840   }
2841 }
2842 
2843 // By now we should have seen all specific procedures referenced by name in
2844 // this generic interface. Resolve those names to symbols.
2845 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
2846   auto &details{generic.get<GenericDetails>()};
2847   UnorderedSymbolSet symbolsSeen;
2848   for (const Symbol &symbol : details.specificProcs()) {
2849     symbolsSeen.insert(symbol.GetUltimate());
2850   }
2851   auto range{specificProcs_.equal_range(&generic)};
2852   for (auto it{range.first}; it != range.second; ++it) {
2853     const parser::Name *name{it->second.first};
2854     auto kind{it->second.second};
2855     const auto *symbol{FindSymbol(*name)};
2856     if (!symbol) {
2857       Say(*name, "Procedure '%s' not found"_err_en_US);
2858       continue;
2859     }
2860     const Symbol &specific{BypassGeneric(*symbol)};
2861     const Symbol &ultimate{specific.GetUltimate()};
2862     if (!ultimate.has<SubprogramDetails>() &&
2863         !ultimate.has<SubprogramNameDetails>()) {
2864       Say(*name, "'%s' is not a subprogram"_err_en_US);
2865       continue;
2866     }
2867     if (kind == ProcedureKind::ModuleProcedure) {
2868       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
2869         if (nd->kind() != SubprogramKind::Module) {
2870           Say(*name, "'%s' is not a module procedure"_err_en_US);
2871         }
2872       } else {
2873         // USE-associated procedure
2874         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
2875         CHECK(sd);
2876         if (ultimate.owner().kind() != Scope::Kind::Module ||
2877             sd->isInterface()) {
2878           Say(*name, "'%s' is not a module procedure"_err_en_US);
2879         }
2880       }
2881     }
2882     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
2883       // When a specific procedure is a USE association, that association
2884       // is saved in the generic's specifics, not its ultimate symbol,
2885       // so that module file output of interfaces can distinguish them.
2886       details.AddSpecificProc(specific, name->source);
2887     } else if (&specific == &ultimate) {
2888       Say(name->source,
2889           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
2890           name->source, MakeOpName(generic.name()));
2891     } else {
2892       Say(name->source,
2893           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
2894           ultimate.name(), ultimate.owner().GetName().value(),
2895           MakeOpName(generic.name()));
2896     }
2897   }
2898   specificProcs_.erase(range.first, range.second);
2899 }
2900 
2901 // Check that the specific procedures are all functions or all subroutines.
2902 // If there is a derived type with the same name they must be functions.
2903 // Set the corresponding flag on generic.
2904 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
2905   ResolveSpecificsInGeneric(generic);
2906   auto &details{generic.get<GenericDetails>()};
2907   if (auto *proc{details.CheckSpecific()}) {
2908     auto msg{
2909         "'%s' may not be the name of both a generic interface and a"
2910         " procedure unless it is a specific procedure of the generic"_err_en_US};
2911     if (proc->name().begin() > generic.name().begin()) {
2912       Say(proc->name(), std::move(msg));
2913     } else {
2914       Say(generic.name(), std::move(msg));
2915     }
2916   }
2917   auto &specifics{details.specificProcs()};
2918   if (specifics.empty()) {
2919     if (details.derivedType()) {
2920       generic.set(Symbol::Flag::Function);
2921     }
2922     return;
2923   }
2924   const Symbol &firstSpecific{specifics.front()};
2925   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
2926   for (const Symbol &specific : specifics) {
2927     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
2928       auto &msg{Say(generic.name(),
2929           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
2930       if (isFunction) {
2931         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
2932         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
2933       } else {
2934         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
2935         msg.Attach(specific.name(), "Function declaration"_en_US);
2936       }
2937     }
2938   }
2939   if (!isFunction && details.derivedType()) {
2940     SayDerivedType(generic.name(),
2941         "Generic interface '%s' may only contain functions due to derived type"
2942         " with same name"_err_en_US,
2943         *details.derivedType()->scope());
2944   }
2945   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
2946 }
2947 
2948 // SubprogramVisitor implementation
2949 
2950 SubprogramVisitor::~SubprogramVisitor() { CHECK(funcInfoStack_.empty()); }
2951 
2952 // Return false if it is actually an assignment statement.
2953 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
2954   const auto &name{std::get<parser::Name>(x.t)};
2955   const DeclTypeSpec *resultType{nullptr};
2956   // Look up name: provides return type or tells us if it's an array
2957   if (auto *symbol{FindSymbol(name)}) {
2958     auto *details{symbol->detailsIf<EntityDetails>()};
2959     if (!details) {
2960       badStmtFuncFound_ = true;
2961       return false;
2962     }
2963     // TODO: check that attrs are compatible with stmt func
2964     resultType = details->type();
2965     symbol->details() = UnknownDetails{}; // will be replaced below
2966   }
2967   if (badStmtFuncFound_) {
2968     Say(name, "'%s' has not been declared as an array"_err_en_US);
2969     return true;
2970   }
2971   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
2972   symbol.set(Symbol::Flag::StmtFunction);
2973   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
2974   auto &details{symbol.get<SubprogramDetails>()};
2975   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
2976     ObjectEntityDetails dummyDetails{true};
2977     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
2978       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
2979         if (d->type()) {
2980           dummyDetails.set_type(*d->type());
2981         }
2982       }
2983     }
2984     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
2985     ApplyImplicitRules(dummy);
2986     details.add_dummyArg(dummy);
2987   }
2988   ObjectEntityDetails resultDetails;
2989   if (resultType) {
2990     resultDetails.set_type(*resultType);
2991   }
2992   resultDetails.set_funcResult(true);
2993   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
2994   ApplyImplicitRules(result);
2995   details.set_result(result);
2996   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
2997   Walk(parsedExpr);
2998   // The analysis of the expression that constitutes the body of the
2999   // statement function is deferred to FinishSpecificationPart() so that
3000   // all declarations and implicit typing are complete.
3001   PopScope();
3002   return true;
3003 }
3004 
3005 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3006   if (suffix.resultName) {
3007     if (IsFunction(currScope())) {
3008       if (!funcInfoStack_.empty()) {
3009         FuncInfo &info{funcInfoStack_.back()};
3010         if (info.inFunctionStmt) {
3011           info.resultName = &suffix.resultName.value();
3012         } else {
3013           // will check the result name in Post(EntryStmt)
3014         }
3015       }
3016     } else {
3017       Message &msg{Say(*suffix.resultName,
3018           "RESULT(%s) may appear only in a function"_err_en_US)};
3019       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3020         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3021       }
3022     }
3023   }
3024   return true;
3025 }
3026 
3027 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3028   // Save this to process after UseStmt and ImplicitPart
3029   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3030     CHECK(!funcInfoStack_.empty());
3031     FuncInfo &info{funcInfoStack_.back()};
3032     if (info.parsedType) { // C1543
3033       Say(currStmtSource().value(),
3034           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3035       return false;
3036     } else {
3037       info.parsedType = parsedType;
3038       info.source = currStmtSource();
3039       return false;
3040     }
3041   } else {
3042     return true;
3043   }
3044 }
3045 
3046 void SubprogramVisitor::FinishFunctionResult() {
3047   // If the function has a type in the prefix, process it now.
3048   if (IsFunction(currScope())) {
3049     CHECK(!funcInfoStack_.empty());
3050     FuncInfo &info{funcInfoStack_.back()};
3051     if (info.parsedType) {
3052       messageHandler().set_currStmtSource(info.source);
3053       if (const auto *type{ProcessTypeSpec(*info.parsedType, true)}) {
3054         if (!context().HasError(info.resultSymbol)) {
3055           info.resultSymbol->SetType(*type);
3056         }
3057       }
3058       info.parsedType = nullptr;
3059     }
3060   }
3061 }
3062 
3063 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3064   const auto &name{std::get<parser::Name>(
3065       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3066   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3067 }
3068 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
3069   EndSubprogram();
3070 }
3071 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3072   const auto &name{std::get<parser::Name>(
3073       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3074   return BeginSubprogram(name, Symbol::Flag::Function);
3075 }
3076 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
3077   EndSubprogram();
3078 }
3079 
3080 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
3081   return BeginAttrs();
3082 }
3083 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3084   CHECK(!funcInfoStack_.empty());
3085   FuncInfo &info{funcInfoStack_.back()};
3086   CHECK(!info.inFunctionStmt);
3087   info.inFunctionStmt = true;
3088   return BeginAttrs();
3089 }
3090 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3091 
3092 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
3093   const auto &name{std::get<parser::Name>(stmt.t)};
3094   auto &details{PostSubprogramStmt(name)};
3095   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3096     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3097       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3098       details.add_dummyArg(dummy);
3099     } else {
3100       details.add_alternateReturn();
3101     }
3102   }
3103 }
3104 
3105 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3106   const auto &name{std::get<parser::Name>(stmt.t)};
3107   auto &details{PostSubprogramStmt(name)};
3108   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3109     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3110     details.add_dummyArg(dummy);
3111   }
3112   const parser::Name *funcResultName;
3113   CHECK(!funcInfoStack_.empty());
3114   FuncInfo &info{funcInfoStack_.back()};
3115   CHECK(info.inFunctionStmt);
3116   info.inFunctionStmt = false;
3117   if (info.resultName && info.resultName->source != name.source) {
3118     // Note that RESULT is ignored if it has the same name as the function.
3119     funcResultName = info.resultName;
3120   } else {
3121     EraseSymbol(name); // was added by PushSubprogramScope
3122     funcResultName = &name;
3123   }
3124   // add function result to function scope
3125   if (details.isFunction()) {
3126     CHECK(context().HasError(currScope().symbol()));
3127   } else {
3128     // add function result to function scope
3129     EntityDetails funcResultDetails;
3130     funcResultDetails.set_funcResult(true);
3131     funcInfoStack_.back().resultSymbol =
3132         &MakeSymbol(*funcResultName, std::move(funcResultDetails));
3133     details.set_result(*funcInfoStack_.back().resultSymbol);
3134   }
3135   // C1560.
3136   if (info.resultName && info.resultName->source == name.source) {
3137     Say(info.resultName->source,
3138         "The function name should not appear in RESULT, references to '%s' "
3139         "inside the function will be considered as references to the "
3140         "result only"_en_US,
3141         name.source);
3142     // RESULT name was ignored above, the only side effect from doing so will be
3143     // the inability to make recursive calls. The related parser::Name is still
3144     // resolved to the created function result symbol because every parser::Name
3145     // should be resolved to avoid internal errors.
3146     Resolve(*info.resultName, info.resultSymbol);
3147   }
3148   name.symbol = currScope().symbol(); // must not be function result symbol
3149   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3150   // has a RESULT() suffix.
3151   info.resultName = nullptr;
3152   // If there was a type on the function statement, and it is an intrinsic
3153   // type, process that type now so that inquiries in specification expressions
3154   // will work.  Derived types are deferred to the end of the specification part
3155   // so that they can resolve to a locally declared type.
3156   if (info.parsedType &&
3157       std::holds_alternative<parser::IntrinsicTypeSpec>(info.parsedType->u)) {
3158     FinishFunctionResult();
3159   }
3160 }
3161 
3162 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3163     const parser::Name &name) {
3164   Symbol &symbol{*currScope().symbol()};
3165   CHECK(name.source == symbol.name());
3166   SetBindNameOn(symbol);
3167   symbol.attrs() |= EndAttrs();
3168   if (symbol.attrs().test(Attr::MODULE)) {
3169     symbol.attrs().set(Attr::EXTERNAL, false);
3170   }
3171   return symbol.get<SubprogramDetails>();
3172 }
3173 
3174 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3175   auto attrs{EndAttrs()}; // needs to be called even if early return
3176   Scope &inclusiveScope{InclusiveScope()};
3177   const Symbol *subprogram{inclusiveScope.symbol()};
3178   if (!subprogram) {
3179     CHECK(context().AnyFatalError());
3180     return;
3181   }
3182   const auto &name{std::get<parser::Name>(stmt.t)};
3183   const parser::Name *resultName{nullptr};
3184   if (const auto &maybeSuffix{
3185           std::get<std::optional<parser::Suffix>>(stmt.t)}) {
3186     resultName = common::GetPtrFromOptional(maybeSuffix->resultName);
3187   }
3188   bool inFunction{IsFunction(currScope())};
3189   if (resultName) { // RESULT(result) is present
3190     if (!inFunction) {
3191       // error was already emitted for the suffix
3192     } else if (resultName->source == subprogram->name()) { // C1574
3193       Say2(resultName->source,
3194           "RESULT(%s) may not have the same name as the function"_err_en_US,
3195           subprogram->name(), "Containing function"_en_US);
3196     } else if (const Symbol *
3197         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
3198       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
3199         if (details->entryScope() == &inclusiveScope) {
3200           Say2(resultName->source,
3201               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3202               symbol->name(), "Conflicting ENTRY"_en_US);
3203         }
3204       }
3205     }
3206     if (Symbol * symbol{FindSymbol(name)}) { // C1570
3207       // When RESULT() appears, ENTRY name can't have been already declared
3208       if (inclusiveScope.Contains(symbol->owner())) {
3209         Say2(name,
3210             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
3211             *symbol, "Previous declaration of '%s'"_en_US);
3212       }
3213     }
3214     if (resultName->source == name.source) {
3215       // ignore RESULT() hereafter when it's the same name as the ENTRY
3216       resultName = nullptr;
3217     }
3218   }
3219   SubprogramDetails entryDetails;
3220   entryDetails.set_entryScope(inclusiveScope);
3221   if (inFunction) {
3222     // Create the entity to hold the function result, if necessary.
3223     Symbol *resultSymbol{nullptr};
3224     auto &effectiveResultName{*(resultName ? resultName : &name)};
3225     resultSymbol = FindInScope(currScope(), effectiveResultName);
3226     if (resultSymbol) { // C1574
3227       std::visit(
3228           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
3229               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
3230               [](ProcEntityDetails &x) { x.set_funcResult(true); },
3231               [&](const auto &) {
3232                 Say2(effectiveResultName.source,
3233                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
3234                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
3235                 context().SetError(*resultSymbol);
3236               }},
3237           resultSymbol->details());
3238     } else if (inExecutionPart_) {
3239       ObjectEntityDetails entity;
3240       entity.set_funcResult(true);
3241       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3242       ApplyImplicitRules(*resultSymbol);
3243     } else {
3244       EntityDetails entity;
3245       entity.set_funcResult(true);
3246       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3247     }
3248     if (!resultName) {
3249       name.symbol = nullptr; // symbol will be used for entry point below
3250     }
3251     entryDetails.set_result(*resultSymbol);
3252   }
3253 
3254   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3255     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3256       Symbol *dummy{FindSymbol(*dummyName)};
3257       if (dummy) {
3258         std::visit(
3259             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3260                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3261                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3262                 [](SubprogramDetails &x) { x.set_isDummy(); },
3263                 [&](const auto &) {
3264                   Say2(dummyName->source,
3265                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3266                       dummy->name(), "Previous declaration of '%s'"_en_US);
3267                 }},
3268             dummy->details());
3269       } else {
3270         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3271         if (inExecutionPart_) {
3272           ApplyImplicitRules(*dummy);
3273         }
3274       }
3275       entryDetails.add_dummyArg(*dummy);
3276     } else {
3277       if (inFunction) { // C1573
3278         Say(name,
3279             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3280         break;
3281       }
3282       entryDetails.add_alternateReturn();
3283     }
3284   }
3285 
3286   Symbol::Flag subpFlag{
3287       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
3288   Scope &outer{inclusiveScope.parent()}; // global or module scope
3289   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3290     attrs.set(Attr::PUBLIC);
3291   }
3292   if (Symbol * extant{FindSymbol(outer, name)}) {
3293     if (!HandlePreviousCalls(name, *extant, subpFlag)) {
3294       if (outer.IsGlobal()) {
3295         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
3296             *extant, "Previous definition of '%s'"_en_US);
3297       } else {
3298         SayAlreadyDeclared(name, *extant);
3299       }
3300       return;
3301     }
3302   }
3303   Symbol &entrySymbol{MakeSymbol(outer, name.source, attrs)};
3304   entrySymbol.set_details(std::move(entryDetails));
3305   SetBindNameOn(entrySymbol);
3306   entrySymbol.set(subpFlag);
3307   Resolve(name, entrySymbol);
3308 }
3309 
3310 // A subprogram declared with MODULE PROCEDURE
3311 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3312   auto *symbol{FindSymbol(name)};
3313   if (symbol && symbol->has<SubprogramNameDetails>()) {
3314     symbol = FindSymbol(currScope().parent(), name);
3315   }
3316   if (!IsSeparateModuleProcedureInterface(symbol)) {
3317     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3318     return false;
3319   }
3320   if (symbol->owner() == currScope()) {
3321     PushScope(Scope::Kind::Subprogram, symbol);
3322   } else {
3323     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3324     PushScope(Scope::Kind::Subprogram, &newSymbol);
3325     const auto &details{symbol->get<SubprogramDetails>()};
3326     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3327     for (const Symbol *dummyArg : details.dummyArgs()) {
3328       if (!dummyArg) {
3329         newDetails.add_alternateReturn();
3330       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3331         newDetails.add_dummyArg(*copy);
3332       }
3333     }
3334     if (details.isFunction()) {
3335       currScope().erase(symbol->name());
3336       newDetails.set_result(*currScope().CopySymbol(details.result()));
3337       funcInfoStack_.emplace_back(); // just to be popped later
3338     }
3339   }
3340   return true;
3341 }
3342 
3343 // A subprogram or interface declared with SUBROUTINE or FUNCTION
3344 bool SubprogramVisitor::BeginSubprogram(
3345     const parser::Name &name, Symbol::Flag subpFlag, bool hasModulePrefix) {
3346   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3347     Say(name,
3348         "'%s' is a MODULE procedure which must be declared within a "
3349         "MODULE or SUBMODULE"_err_en_US);
3350     return false;
3351   }
3352 
3353   if (hasModulePrefix && !inInterfaceBlock() &&
3354       !IsSeparateModuleProcedureInterface(
3355           FindSymbol(currScope().parent(), name))) {
3356     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3357     return false;
3358   }
3359   PushSubprogramScope(name, subpFlag);
3360   if (IsFunction(currScope())) {
3361     funcInfoStack_.emplace_back();
3362   }
3363   return true;
3364 }
3365 
3366 void SubprogramVisitor::EndSubprogram() {
3367   if (IsFunction(currScope())) {
3368     funcInfoStack_.pop_back();
3369   }
3370   PopScope();
3371 }
3372 
3373 bool SubprogramVisitor::HandlePreviousCalls(
3374     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3375   if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3376       !proc->isDummy() &&
3377       !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3378     // There's a symbol created for previous calls to this subprogram or
3379     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3380     // obligation to rewrite symbol pointers in the parse tree.
3381     if (!symbol.test(subpFlag)) {
3382       Say2(name,
3383           subpFlag == Symbol::Flag::Function
3384               ? "'%s' was previously called as a subroutine"_err_en_US
3385               : "'%s' was previously called as a function"_err_en_US,
3386           symbol, "Previous call of '%s'"_en_US);
3387     }
3388     EntityDetails entity;
3389     if (proc->type()) {
3390       entity.set_type(*proc->type());
3391     }
3392     symbol.details() = std::move(entity);
3393     return true;
3394   } else {
3395     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3396   }
3397 }
3398 
3399 void SubprogramVisitor::CheckExtantProc(
3400     const parser::Name &name, Symbol::Flag subpFlag) {
3401   if (auto *prev{FindSymbol(name)}) {
3402     if (IsDummy(*prev)) {
3403     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3404       // Procedures in an INTERFACE block do not resolve to symbols
3405       // in scopes between the global scope and the current scope.
3406     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3407       SayAlreadyDeclared(name, *prev);
3408     }
3409   }
3410 }
3411 
3412 Symbol &SubprogramVisitor::PushSubprogramScope(
3413     const parser::Name &name, Symbol::Flag subpFlag) {
3414   auto *symbol{GetSpecificFromGeneric(name)};
3415   if (!symbol) {
3416     CheckExtantProc(name, subpFlag);
3417     symbol = &MakeSymbol(name, SubprogramDetails{});
3418   }
3419   symbol->set(subpFlag);
3420   symbol->ReplaceName(name.source);
3421   PushScope(Scope::Kind::Subprogram, symbol);
3422   auto &details{symbol->get<SubprogramDetails>()};
3423   if (inInterfaceBlock()) {
3424     details.set_isInterface();
3425     if (isAbstract()) {
3426       symbol->attrs().set(Attr::ABSTRACT);
3427     } else {
3428       MakeExternal(*symbol);
3429     }
3430     if (isGeneric()) {
3431       Symbol &genericSymbol{GetGenericSymbol()};
3432       if (genericSymbol.has<GenericDetails>()) {
3433         genericSymbol.get<GenericDetails>().AddSpecificProc(
3434             *symbol, name.source);
3435       } else {
3436         CHECK(context().HasError(genericSymbol));
3437       }
3438     }
3439     set_inheritFromParent(false);
3440   }
3441   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3442   return *symbol;
3443 }
3444 
3445 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3446   if (auto *prev{FindSymbol(name)}) {
3447     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3448       if (prev->test(Symbol::Flag::Subroutine) ||
3449           prev->test(Symbol::Flag::Function)) {
3450         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3451             "Previous call of '%s'"_en_US);
3452       }
3453       EraseSymbol(name);
3454     }
3455   }
3456   if (name.source.empty()) {
3457     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3458     PushScope(Scope::Kind::BlockData, nullptr);
3459   } else {
3460     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3461   }
3462 }
3463 
3464 // If name is a generic, return specific subprogram with the same name.
3465 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3466   if (auto *symbol{FindSymbol(name)}) {
3467     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3468       // found generic, want subprogram
3469       auto *specific{details->specific()};
3470       if (!specific) {
3471         specific =
3472             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3473         if (details->derivedType()) {
3474           // A specific procedure with the same name as a derived type
3475           SayAlreadyDeclared(name, *details->derivedType());
3476         } else {
3477           details->set_specific(Resolve(name, *specific));
3478         }
3479       } else if (isGeneric()) {
3480         SayAlreadyDeclared(name, *specific);
3481       }
3482       if (!specific->has<SubprogramDetails>()) {
3483         specific->set_details(SubprogramDetails{});
3484       }
3485       return specific;
3486     }
3487   }
3488   return nullptr;
3489 }
3490 
3491 // DeclarationVisitor implementation
3492 
3493 bool DeclarationVisitor::BeginDecl() {
3494   BeginDeclTypeSpec();
3495   BeginArraySpec();
3496   return BeginAttrs();
3497 }
3498 void DeclarationVisitor::EndDecl() {
3499   EndDeclTypeSpec();
3500   EndArraySpec();
3501   EndAttrs();
3502 }
3503 
3504 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3505   const auto *details{
3506       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3507   if (!details) {
3508     return false;
3509   }
3510   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3511   for (const auto &[location, module] : details->occurrences()) {
3512     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3513         name.source, module->GetName().value());
3514   }
3515   context().SetError(*name.symbol);
3516   return true;
3517 }
3518 
3519 // Report error if accessibility of symbol doesn't match isPrivate.
3520 void DeclarationVisitor::CheckAccessibility(
3521     const SourceName &name, bool isPrivate, Symbol &symbol) {
3522   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3523     Say2(name,
3524         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3525         symbol, "Previous declaration of '%s'"_en_US);
3526   }
3527 }
3528 
3529 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3530   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3531     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3532       if (typeSpec->category() == DeclTypeSpec::Character) {
3533         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3534           Say("The type parameter LEN cannot be deferred without"
3535               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3536         }
3537       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3538         for (const auto &pair : derivedSpec->parameters()) {
3539           if (pair.second.isDeferred()) {
3540             Say(currStmtSource().value(),
3541                 "The value of type parameter '%s' cannot be deferred"
3542                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3543                 pair.first);
3544           }
3545         }
3546       }
3547     }
3548   }
3549   EndDecl();
3550 }
3551 
3552 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3553   DeclareObjectEntity(std::get<parser::Name>(x.t));
3554 }
3555 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3556   DeclareObjectEntity(std::get<parser::Name>(x.t));
3557 }
3558 
3559 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3560   // Defer inspection of initializers to Initialization() so that the
3561   // symbol being initialized will be available within the initialization
3562   // expression.
3563   return false;
3564 }
3565 
3566 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3567   const auto &name{std::get<parser::ObjectName>(x.t)};
3568   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3569   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3570   symbol.ReplaceName(name.source);
3571   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3572     if (ConvertToObjectEntity(symbol)) {
3573       Initialization(name, *init, false);
3574     }
3575   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3576     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3577   }
3578 }
3579 
3580 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3581   const auto &name{std::get<parser::Name>(x.t)};
3582   if (const auto &deferredShapeSpecs{
3583           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3584     CHECK(arraySpec().empty());
3585     BeginArraySpec();
3586     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3587     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3588     symbol.ReplaceName(name.source);
3589     EndArraySpec();
3590   } else {
3591     Symbol &symbol{DeclareUnknownEntity(name, Attrs{Attr::POINTER})};
3592     symbol.ReplaceName(name.source);
3593   }
3594 }
3595 
3596 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3597   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3598   auto &name{std::get<parser::Name>(x.t)};
3599   Symbol *symbol;
3600   if (kind == parser::BindEntity::Kind::Object) {
3601     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3602   } else {
3603     symbol = &MakeCommonBlockSymbol(name);
3604     symbol->attrs().set(Attr::BIND_C);
3605   }
3606   SetBindNameOn(*symbol);
3607   return false;
3608 }
3609 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3610   inOldStyleParameterStmt_ = true;
3611   Walk(x.v);
3612   inOldStyleParameterStmt_ = false;
3613   return false;
3614 }
3615 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3616   auto &name{std::get<parser::NamedConstant>(x.t).v};
3617   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3618   if (!ConvertToObjectEntity(symbol) ||
3619       symbol.test(Symbol::Flag::CrayPointer) ||
3620       symbol.test(Symbol::Flag::CrayPointee)) {
3621     SayWithDecl(
3622         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3623     return false;
3624   }
3625   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3626   auto &details{symbol.get<ObjectEntityDetails>()};
3627   if (inOldStyleParameterStmt_) {
3628     // non-standard extension PARAMETER statement (no parentheses)
3629     Walk(expr);
3630     auto folded{EvaluateExpr(expr)};
3631     if (details.type()) {
3632       SayWithDecl(name, symbol,
3633           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3634     } else if (folded) {
3635       auto at{expr.thing.value().source};
3636       if (evaluate::IsActuallyConstant(*folded)) {
3637         if (const auto *type{currScope().GetType(*folded)}) {
3638           if (type->IsPolymorphic()) {
3639             Say(at, "The expression must not be polymorphic"_err_en_US);
3640           } else if (auto shape{ToArraySpec(
3641                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3642             // The type of the named constant is assumed from the expression.
3643             details.set_type(*type);
3644             details.set_init(std::move(*folded));
3645             details.set_shape(std::move(*shape));
3646           } else {
3647             Say(at, "The expression must have constant shape"_err_en_US);
3648           }
3649         } else {
3650           Say(at, "The expression must have a known type"_err_en_US);
3651         }
3652       } else {
3653         Say(at, "The expression must be a constant of known type"_err_en_US);
3654       }
3655     }
3656   } else {
3657     // standard-conforming PARAMETER statement (with parentheses)
3658     ApplyImplicitRules(symbol);
3659     Walk(expr);
3660     if (auto converted{EvaluateNonPointerInitializer(
3661             symbol, expr, expr.thing.value().source)}) {
3662       details.set_init(std::move(*converted));
3663     }
3664   }
3665   return false;
3666 }
3667 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3668   const parser::Name &name{x.v};
3669   if (!FindSymbol(name)) {
3670     Say(name, "Named constant '%s' not found"_err_en_US);
3671   } else {
3672     CheckUseError(name);
3673   }
3674   return false;
3675 }
3676 
3677 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3678   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3679   Symbol *symbol{FindSymbol(name)};
3680   if (symbol && !symbol->has<UnknownDetails>()) {
3681     // Contrary to named constants appearing in a PARAMETER statement,
3682     // enumerator names should not have their type, dimension or any other
3683     // attributes defined before they are declared in the enumerator statement,
3684     // with the exception of accessibility.
3685     // This is not explicitly forbidden by the standard, but they are scalars
3686     // which type is left for the compiler to chose, so do not let users try to
3687     // tamper with that.
3688     SayAlreadyDeclared(name, *symbol);
3689     symbol = nullptr;
3690   } else {
3691     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3692     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3693     symbol->SetType(context().MakeNumericType(
3694         TypeCategory::Integer, evaluate::CInteger::kind));
3695   }
3696 
3697   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3698           enumerator.t)}) {
3699     Walk(*init); // Resolve names in expression before evaluation.
3700     if (auto value{EvaluateInt64(context(), *init)}) {
3701       // Cast all init expressions to C_INT so that they can then be
3702       // safely incremented (see 7.6 Note 2).
3703       enumerationState_.value = static_cast<int>(*value);
3704     } else {
3705       Say(name,
3706           "Enumerator value could not be computed "
3707           "from the given expression"_err_en_US);
3708       // Prevent resolution of next enumerators value
3709       enumerationState_.value = std::nullopt;
3710     }
3711   }
3712 
3713   if (symbol) {
3714     if (enumerationState_.value) {
3715       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3716           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3717     } else {
3718       context().SetError(*symbol);
3719     }
3720   }
3721 
3722   if (enumerationState_.value) {
3723     (*enumerationState_.value)++;
3724   }
3725   return false;
3726 }
3727 
3728 void DeclarationVisitor::Post(const parser::EnumDef &) {
3729   enumerationState_ = EnumeratorState{};
3730 }
3731 
3732 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3733   Attr attr{AccessSpecToAttr(x)};
3734   if (!NonDerivedTypeScope().IsModule()) { // C817
3735     Say(currStmtSource().value(),
3736         "%s attribute may only appear in the specification part of a module"_err_en_US,
3737         EnumToString(attr));
3738   }
3739   CheckAndSet(attr);
3740   return false;
3741 }
3742 
3743 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3744   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3745 }
3746 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3747   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3748 }
3749 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3750   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3751   for (const auto &name : x.v) {
3752     auto *symbol{FindSymbol(name)};
3753     if (!ConvertToProcEntity(*symbol)) {
3754       SayWithDecl(
3755           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3756     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
3757       Say(symbol->name(),
3758           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
3759           symbol->name());
3760     }
3761   }
3762   return false;
3763 }
3764 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3765   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3766   auto &names{std::get<std::list<parser::Name>>(x.t)};
3767   return CheckNotInBlock("INTENT") && // C1107
3768       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3769 }
3770 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3771   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3772   for (const auto &name : x.v) {
3773     auto &symbol{DEREF(FindSymbol(name))};
3774     if (!ConvertToProcEntity(symbol)) {
3775       SayWithDecl(
3776           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3777     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
3778       Say(symbol.name(),
3779           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3780           symbol.name());
3781     } else if (symbol.GetType()) {
3782       // These warnings are worded so that they should make sense in either
3783       // order.
3784       Say(symbol.name(),
3785           "Explicit type declaration ignored for intrinsic function '%s'"_en_US,
3786           symbol.name())
3787           .Attach(name.source,
3788               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
3789               name.source);
3790     }
3791   }
3792   return false;
3793 }
3794 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3795   return CheckNotInBlock("OPTIONAL") && // C1107
3796       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3797 }
3798 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3799   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3800 }
3801 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3802   return CheckNotInBlock("VALUE") && // C1107
3803       HandleAttributeStmt(Attr::VALUE, x.v);
3804 }
3805 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
3806   return HandleAttributeStmt(Attr::VOLATILE, x.v);
3807 }
3808 // Handle a statement that sets an attribute on a list of names.
3809 bool DeclarationVisitor::HandleAttributeStmt(
3810     Attr attr, const std::list<parser::Name> &names) {
3811   for (const auto &name : names) {
3812     HandleAttributeStmt(attr, name);
3813   }
3814   return false;
3815 }
3816 Symbol &DeclarationVisitor::HandleAttributeStmt(
3817     Attr attr, const parser::Name &name) {
3818   if (attr == Attr::INTRINSIC && !IsIntrinsic(name.source, std::nullopt)) {
3819     Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
3820   }
3821   auto *symbol{FindInScope(name)};
3822   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
3823     // these can be set on a symbol that is host-assoc or use-assoc
3824     if (!symbol &&
3825         (currScope().kind() == Scope::Kind::Subprogram ||
3826             currScope().kind() == Scope::Kind::Block)) {
3827       if (auto *hostSymbol{FindSymbol(name)}) {
3828         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
3829       }
3830     }
3831   } else if (symbol && symbol->has<UseDetails>()) {
3832     Say(currStmtSource().value(),
3833         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
3834         EnumToString(attr), name.source);
3835     return *symbol;
3836   }
3837   if (!symbol) {
3838     symbol = &MakeSymbol(name, EntityDetails{});
3839   }
3840   symbol->attrs().set(attr);
3841   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
3842   return *symbol;
3843 }
3844 // C1107
3845 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
3846   if (currScope().kind() == Scope::Kind::Block) {
3847     Say(MessageFormattedText{
3848         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
3849     return false;
3850   } else {
3851     return true;
3852   }
3853 }
3854 
3855 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
3856   CHECK(objectDeclAttr_);
3857   const auto &name{std::get<parser::ObjectName>(x.t)};
3858   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
3859 }
3860 
3861 // Declare an entity not yet known to be an object or proc.
3862 Symbol &DeclarationVisitor::DeclareUnknownEntity(
3863     const parser::Name &name, Attrs attrs) {
3864   if (!arraySpec().empty() || !coarraySpec().empty()) {
3865     return DeclareObjectEntity(name, attrs);
3866   } else {
3867     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
3868     if (auto *type{GetDeclTypeSpec()}) {
3869       SetType(name, *type);
3870     }
3871     charInfo_.length.reset();
3872     SetBindNameOn(symbol);
3873     if (symbol.attrs().test(Attr::EXTERNAL)) {
3874       ConvertToProcEntity(symbol);
3875     }
3876     return symbol;
3877   }
3878 }
3879 
3880 bool DeclarationVisitor::HasCycle(
3881     const Symbol &procSymbol, const ProcInterface &interface) {
3882   SourceOrderedSymbolSet procsInCycle;
3883   procsInCycle.insert(procSymbol);
3884   const ProcInterface *thisInterface{&interface};
3885   bool haveInterface{true};
3886   while (haveInterface) {
3887     haveInterface = false;
3888     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
3889       if (procsInCycle.count(*interfaceSymbol) > 0) {
3890         for (const auto &procInCycle : procsInCycle) {
3891           Say(procInCycle->name(),
3892               "The interface for procedure '%s' is recursively "
3893               "defined"_err_en_US,
3894               procInCycle->name());
3895           context().SetError(*procInCycle);
3896         }
3897         return true;
3898       } else if (const auto *procDetails{
3899                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
3900         haveInterface = true;
3901         thisInterface = &procDetails->interface();
3902         procsInCycle.insert(*interfaceSymbol);
3903       }
3904     }
3905   }
3906   return false;
3907 }
3908 
3909 Symbol &DeclarationVisitor::DeclareProcEntity(
3910     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
3911   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
3912   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
3913     if (details->IsInterfaceSet()) {
3914       SayWithDecl(name, symbol,
3915           "The interface for procedure '%s' has already been "
3916           "declared"_err_en_US);
3917       context().SetError(symbol);
3918     } else if (HasCycle(symbol, interface)) {
3919       return symbol;
3920     } else if (interface.type()) {
3921       symbol.set(Symbol::Flag::Function);
3922     } else if (interface.symbol()) {
3923       if (interface.symbol()->test(Symbol::Flag::Function)) {
3924         symbol.set(Symbol::Flag::Function);
3925       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
3926         symbol.set(Symbol::Flag::Subroutine);
3927       }
3928     }
3929     details->set_interface(interface);
3930     SetBindNameOn(symbol);
3931     SetPassNameOn(symbol);
3932   }
3933   return symbol;
3934 }
3935 
3936 Symbol &DeclarationVisitor::DeclareObjectEntity(
3937     const parser::Name &name, Attrs attrs) {
3938   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
3939   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
3940     if (auto *type{GetDeclTypeSpec()}) {
3941       SetType(name, *type);
3942     }
3943     if (!arraySpec().empty()) {
3944       if (details->IsArray()) {
3945         if (!context().HasError(symbol)) {
3946           Say(name,
3947               "The dimensions of '%s' have already been declared"_err_en_US);
3948           context().SetError(symbol);
3949         }
3950       } else {
3951         details->set_shape(arraySpec());
3952       }
3953     }
3954     if (!coarraySpec().empty()) {
3955       if (details->IsCoarray()) {
3956         if (!context().HasError(symbol)) {
3957           Say(name,
3958               "The codimensions of '%s' have already been declared"_err_en_US);
3959           context().SetError(symbol);
3960         }
3961       } else {
3962         details->set_coshape(coarraySpec());
3963       }
3964     }
3965     SetBindNameOn(symbol);
3966   }
3967   ClearArraySpec();
3968   ClearCoarraySpec();
3969   charInfo_.length.reset();
3970   return symbol;
3971 }
3972 
3973 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
3974   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
3975 }
3976 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
3977   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
3978 }
3979 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
3980   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
3981 }
3982 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
3983   SetDeclTypeSpec(MakeLogicalType(x.kind));
3984 }
3985 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
3986   if (!charInfo_.length) {
3987     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
3988   }
3989   if (!charInfo_.kind) {
3990     charInfo_.kind =
3991         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
3992   }
3993   SetDeclTypeSpec(currScope().MakeCharacterType(
3994       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
3995   charInfo_ = {};
3996 }
3997 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
3998   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
3999   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
4000   if (intKind &&
4001       !evaluate::IsValidKindOfIntrinsicType(
4002           TypeCategory::Character, *intKind)) { // C715, C719
4003     Say(currStmtSource().value(),
4004         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
4005     charInfo_.kind = std::nullopt; // prevent further errors
4006   }
4007   if (x.length) {
4008     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
4009   }
4010 }
4011 void DeclarationVisitor::Post(const parser::CharLength &x) {
4012   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
4013     charInfo_.length = ParamValue{
4014         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
4015   } else {
4016     charInfo_.length = GetParamValue(
4017         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
4018   }
4019 }
4020 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
4021   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
4022     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
4023   }
4024 }
4025 
4026 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
4027   if (const auto *kind{std::get_if<
4028           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
4029           &x.u)}) {
4030     const parser::Name &name{kind->thing.thing.thing};
4031     if (!FindSymbol(name)) {
4032       Say(name, "Parameter '%s' not found"_err_en_US);
4033     }
4034   }
4035   return false;
4036 }
4037 
4038 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
4039   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
4040   return true;
4041 }
4042 
4043 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
4044   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
4045   if (const Symbol * derivedSymbol{derivedName.symbol}) {
4046     CheckForAbstractType(*derivedSymbol); // C706
4047   }
4048 }
4049 
4050 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4051   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4052   return true;
4053 }
4054 
4055 void DeclarationVisitor::Post(
4056     const parser::DeclarationTypeSpec::Class &parsedClass) {
4057   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4058   if (auto spec{ResolveDerivedType(typeName)};
4059       spec && !IsExtensibleType(&*spec)) { // C705
4060     SayWithDecl(typeName, *typeName.symbol,
4061         "Non-extensible derived type '%s' may not be used with CLASS"
4062         " keyword"_err_en_US);
4063   }
4064 }
4065 
4066 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4067   const auto &typeName{std::get<parser::Name>(x.t)};
4068   auto spec{ResolveDerivedType(typeName)};
4069   if (!spec) {
4070     return;
4071   }
4072   bool seenAnyName{false};
4073   for (const auto &typeParamSpec :
4074       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4075     const auto &optKeyword{
4076         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4077     std::optional<SourceName> name;
4078     if (optKeyword) {
4079       seenAnyName = true;
4080       name = optKeyword->v.source;
4081     } else if (seenAnyName) {
4082       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4083       continue;
4084     }
4085     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4086     // The expressions in a derived type specifier whose values define
4087     // non-defaulted type parameters are evaluated (folded) in the enclosing
4088     // scope.  The KIND/LEN distinction is resolved later in
4089     // DerivedTypeSpec::CookParameters().
4090     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4091     if (!param.isExplicit() || param.GetExplicit()) {
4092       spec->AddRawParamValue(optKeyword, std::move(param));
4093     }
4094   }
4095 
4096   // The DerivedTypeSpec *spec is used initially as a search key.
4097   // If it turns out to have the same name and actual parameter
4098   // value expressions as another DerivedTypeSpec in the current
4099   // scope does, then we'll use that extant spec; otherwise, when this
4100   // spec is distinct from all derived types previously instantiated
4101   // in the current scope, this spec will be moved into that collection.
4102   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4103   auto category{GetDeclTypeSpecCategory()};
4104   if (dtDetails.isForwardReferenced()) {
4105     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4106     SetDeclTypeSpec(type);
4107     return;
4108   }
4109   // Normalize parameters to produce a better search key.
4110   spec->CookParameters(GetFoldingContext());
4111   if (!spec->MightBeParameterized()) {
4112     spec->EvaluateParameters(context());
4113   }
4114   if (const DeclTypeSpec *
4115       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4116     // This derived type and parameter expressions (if any) are already present
4117     // in this scope.
4118     SetDeclTypeSpec(*extant);
4119   } else {
4120     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4121     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4122     if (derived.MightBeParameterized() &&
4123         currScope().IsParameterizedDerivedType()) {
4124       // Defer instantiation; use the derived type's definition's scope.
4125       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4126     } else if (&currScope() == spec->typeSymbol().scope()) {
4127       // Direct recursive use of a type in the definition of one of its
4128       // components: defer instantiation
4129     } else {
4130       auto restorer{
4131           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4132       derived.Instantiate(currScope());
4133     }
4134     SetDeclTypeSpec(type);
4135   }
4136   // Capture the DerivedTypeSpec in the parse tree for use in building
4137   // structure constructor expressions.
4138   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4139 }
4140 
4141 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4142   const auto &typeName{rec.v};
4143   if (auto spec{ResolveDerivedType(typeName)}) {
4144     spec->CookParameters(GetFoldingContext());
4145     spec->EvaluateParameters(context());
4146     if (const DeclTypeSpec *
4147         extant{currScope().FindInstantiatedDerivedType(
4148             *spec, DeclTypeSpec::TypeDerived)}) {
4149       SetDeclTypeSpec(*extant);
4150     } else {
4151       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4152           typeName.source);
4153     }
4154   }
4155 }
4156 
4157 // The descendents of DerivedTypeDef in the parse tree are visited directly
4158 // in this Pre() routine so that recursive use of the derived type can be
4159 // supported in the components.
4160 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4161   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4162   Walk(stmt);
4163   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4164   auto &scope{currScope()};
4165   CHECK(scope.symbol());
4166   CHECK(scope.symbol()->scope() == &scope);
4167   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4168   details.set_isForwardReferenced(false);
4169   std::set<SourceName> paramNames;
4170   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4171     details.add_paramName(paramName.source);
4172     auto *symbol{FindInScope(scope, paramName)};
4173     if (!symbol) {
4174       Say(paramName,
4175           "No definition found for type parameter '%s'"_err_en_US); // C742
4176       // No symbol for a type param.  Create one and mark it as containing an
4177       // error to improve subsequent semantic processing
4178       BeginAttrs();
4179       Symbol *typeParam{MakeTypeSymbol(
4180           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4181       context().SetError(*typeParam);
4182       EndAttrs();
4183     } else if (!symbol->has<TypeParamDetails>()) {
4184       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4185           *symbol, "Definition of '%s'"_en_US); // C741
4186     }
4187     if (!paramNames.insert(paramName.source).second) {
4188       Say(paramName,
4189           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4190     }
4191   }
4192   for (const auto &[name, symbol] : currScope()) {
4193     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4194       SayDerivedType(name,
4195           "'%s' is not a type parameter of this derived type"_err_en_US,
4196           currScope()); // C741
4197     }
4198   }
4199   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4200   const auto &componentDefs{
4201       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4202   Walk(componentDefs);
4203   if (derivedTypeInfo_.sequence) {
4204     details.set_sequence(true);
4205     if (componentDefs.empty()) { // C740
4206       Say(stmt.source,
4207           "A sequence type must have at least one component"_err_en_US);
4208     }
4209     if (!details.paramNames().empty()) { // C740
4210       Say(stmt.source,
4211           "A sequence type may not have type parameters"_err_en_US);
4212     }
4213     if (derivedTypeInfo_.extends) { // C735
4214       Say(stmt.source,
4215           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4216     }
4217   }
4218   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4219   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4220   derivedTypeInfo_ = {};
4221   PopScope();
4222   return false;
4223 }
4224 
4225 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4226   return BeginAttrs();
4227 }
4228 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4229   auto &name{std::get<parser::Name>(x.t)};
4230   // Resolve the EXTENDS() clause before creating the derived
4231   // type's symbol to foil attempts to recursively extend a type.
4232   auto *extendsName{derivedTypeInfo_.extends};
4233   std::optional<DerivedTypeSpec> extendsType{
4234       ResolveExtendsType(name, extendsName)};
4235   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4236   symbol.ReplaceName(name.source);
4237   derivedTypeInfo_.type = &symbol;
4238   PushScope(Scope::Kind::DerivedType, &symbol);
4239   if (extendsType) {
4240     // Declare the "parent component"; private if the type is.
4241     // Any symbol stored in the EXTENDS() clause is temporarily
4242     // hidden so that a new symbol can be created for the parent
4243     // component without producing spurious errors about already
4244     // existing.
4245     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4246     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4247     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4248       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4249       comp.attrs().set(
4250           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4251       comp.set(Symbol::Flag::ParentComp);
4252       DeclTypeSpec &type{currScope().MakeDerivedType(
4253           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4254       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4255       comp.SetType(type);
4256       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4257       details.add_component(comp);
4258     }
4259   }
4260   EndAttrs();
4261 }
4262 
4263 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4264   auto *type{GetDeclTypeSpec()};
4265   auto attr{std::get<common::TypeParamAttr>(x.t)};
4266   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4267     auto &name{std::get<parser::Name>(decl.t)};
4268     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4269       SetType(name, *type);
4270       if (auto &init{
4271               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4272         if (auto maybeExpr{EvaluateNonPointerInitializer(
4273                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4274           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4275             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4276           }
4277         }
4278       }
4279     }
4280   }
4281   EndDecl();
4282 }
4283 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4284   if (derivedTypeInfo_.extends) {
4285     Say(currStmtSource().value(),
4286         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4287   } else {
4288     derivedTypeInfo_.extends = &x.v;
4289   }
4290   return false;
4291 }
4292 
4293 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4294   if (!currScope().parent().IsModule()) {
4295     Say("PRIVATE is only allowed in a derived type that is"
4296         " in a module"_err_en_US); // C766
4297   } else if (derivedTypeInfo_.sawContains) {
4298     derivedTypeInfo_.privateBindings = true;
4299   } else if (!derivedTypeInfo_.privateComps) {
4300     derivedTypeInfo_.privateComps = true;
4301   } else {
4302     Say("PRIVATE may not appear more than once in"
4303         " derived type components"_en_US); // C738
4304   }
4305   return false;
4306 }
4307 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4308   if (derivedTypeInfo_.sequence) {
4309     Say("SEQUENCE may not appear more than once in"
4310         " derived type components"_en_US); // C738
4311   }
4312   derivedTypeInfo_.sequence = true;
4313   return false;
4314 }
4315 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4316   const auto &name{std::get<parser::Name>(x.t)};
4317   auto attrs{GetAttrs()};
4318   if (derivedTypeInfo_.privateComps &&
4319       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4320     attrs.set(Attr::PRIVATE);
4321   }
4322   if (const auto *declType{GetDeclTypeSpec()}) {
4323     if (const auto *derived{declType->AsDerived()}) {
4324       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4325         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4326           Say("Recursive use of the derived type requires "
4327               "POINTER or ALLOCATABLE"_err_en_US);
4328         }
4329       }
4330       // TODO: This would be more appropriate in CheckDerivedType()
4331       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4332         std::string ultimateName{it.BuildResultDesignatorName()};
4333         // Strip off the leading "%"
4334         if (ultimateName.length() > 1) {
4335           ultimateName.erase(0, 1);
4336           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4337             evaluate::AttachDeclaration(
4338                 Say(name.source,
4339                     "A component with a POINTER or ALLOCATABLE attribute may "
4340                     "not "
4341                     "be of a type with a coarray ultimate component (named "
4342                     "'%s')"_err_en_US,
4343                     ultimateName),
4344                 derived->typeSymbol());
4345           }
4346           if (!arraySpec().empty() || !coarraySpec().empty()) {
4347             evaluate::AttachDeclaration(
4348                 Say(name.source,
4349                     "An array or coarray component may not be of a type with a "
4350                     "coarray ultimate component (named '%s')"_err_en_US,
4351                     ultimateName),
4352                 derived->typeSymbol());
4353           }
4354         }
4355       }
4356     }
4357   }
4358   if (OkToAddComponent(name)) {
4359     auto &symbol{DeclareObjectEntity(name, attrs)};
4360     if (symbol.has<ObjectEntityDetails>()) {
4361       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4362         Initialization(name, *init, true);
4363       }
4364     }
4365     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4366   }
4367   ClearArraySpec();
4368   ClearCoarraySpec();
4369 }
4370 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4371   // Replace "%FILL" with a distinct generated name
4372   const auto &name{std::get<parser::Name>(x.t)};
4373   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4374   if (OkToAddComponent(name)) {
4375     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4376     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4377   }
4378   ClearArraySpec();
4379 }
4380 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4381   CHECK(!interfaceName_);
4382   return BeginDecl();
4383 }
4384 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4385   interfaceName_ = nullptr;
4386   EndDecl();
4387 }
4388 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4389   // Overrides parse tree traversal so as to handle attributes first,
4390   // so POINTER & ALLOCATABLE enable forward references to derived types.
4391   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4392   set_allowForwardReferenceToDerivedType(
4393       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4394   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4395   set_allowForwardReferenceToDerivedType(false);
4396   if (derivedTypeInfo_.sequence) { // C740
4397     if (const auto *declType{GetDeclTypeSpec()}) {
4398       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4399         if (GetAttrs().test(Attr::POINTER) &&
4400             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4401           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4402             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_en_US);
4403           }
4404         } else {
4405           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4406         }
4407       }
4408     }
4409   }
4410   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4411   return false;
4412 }
4413 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4414   CHECK(!interfaceName_);
4415   return true;
4416 }
4417 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4418   interfaceName_ = nullptr;
4419 }
4420 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4421   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4422     return !NameIsKnownOrIntrinsic(*name);
4423   }
4424   return true;
4425 }
4426 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4427   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4428     interfaceName_ = name;
4429     NoteInterfaceName(*name);
4430   }
4431 }
4432 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4433   const auto &name{std::get<parser::Name>(x.t)};
4434   ProcInterface interface;
4435   if (interfaceName_) {
4436     interface.set_symbol(*interfaceName_->symbol);
4437   } else if (auto *type{GetDeclTypeSpec()}) {
4438     interface.set_type(*type);
4439   }
4440   auto attrs{HandleSaveName(name.source, GetAttrs())};
4441   DerivedTypeDetails *dtDetails{nullptr};
4442   if (Symbol * symbol{currScope().symbol()}) {
4443     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4444   }
4445   if (!dtDetails) {
4446     attrs.set(Attr::EXTERNAL);
4447   }
4448   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4449   symbol.ReplaceName(name.source);
4450   if (dtDetails) {
4451     dtDetails->add_component(symbol);
4452   }
4453 }
4454 
4455 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4456   derivedTypeInfo_.sawContains = true;
4457   return true;
4458 }
4459 
4460 // Resolve binding names from type-bound generics, saved in genericBindings_.
4461 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4462   // track specifics seen for the current generic to detect duplicates:
4463   const Symbol *currGeneric{nullptr};
4464   std::set<SourceName> specifics;
4465   for (const auto &[generic, bindingName] : genericBindings_) {
4466     if (generic != currGeneric) {
4467       currGeneric = generic;
4468       specifics.clear();
4469     }
4470     auto [it, inserted]{specifics.insert(bindingName->source)};
4471     if (!inserted) {
4472       Say(*bindingName, // C773
4473           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4474           bindingName->source, generic->name())
4475           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4476       continue;
4477     }
4478     auto *symbol{FindInTypeOrParents(*bindingName)};
4479     if (!symbol) {
4480       Say(*bindingName, // C772
4481           "Binding name '%s' not found in this derived type"_err_en_US);
4482     } else if (!symbol->has<ProcBindingDetails>()) {
4483       SayWithDecl(*bindingName, *symbol, // C772
4484           "'%s' is not the name of a specific binding of this type"_err_en_US);
4485     } else {
4486       generic->get<GenericDetails>().AddSpecificProc(
4487           *symbol, bindingName->source);
4488     }
4489   }
4490   genericBindings_.clear();
4491 }
4492 
4493 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4494   if (derivedTypeInfo_.sequence) {
4495     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4496   }
4497 }
4498 
4499 void DeclarationVisitor::Post(
4500     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4501   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4502     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4503   }
4504   for (auto &declaration : x.declarations) {
4505     auto &bindingName{std::get<parser::Name>(declaration.t)};
4506     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4507     const parser::Name &procedureName{optName ? *optName : bindingName};
4508     Symbol *procedure{FindSymbol(procedureName)};
4509     if (!procedure) {
4510       procedure = NoteInterfaceName(procedureName);
4511     }
4512     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4513       SetPassNameOn(*s);
4514       if (GetAttrs().test(Attr::DEFERRED)) {
4515         context().SetError(*s);
4516       }
4517     }
4518   }
4519 }
4520 
4521 void DeclarationVisitor::CheckBindings(
4522     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4523   CHECK(currScope().IsDerivedType());
4524   for (auto &declaration : tbps.declarations) {
4525     auto &bindingName{std::get<parser::Name>(declaration.t)};
4526     if (Symbol * binding{FindInScope(bindingName)}) {
4527       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4528         const Symbol *procedure{FindSubprogram(details->symbol())};
4529         if (!CanBeTypeBoundProc(procedure)) {
4530           if (details->symbol().name() != binding->name()) {
4531             Say(binding->name(),
4532                 "The binding of '%s' ('%s') must be either an accessible "
4533                 "module procedure or an external procedure with "
4534                 "an explicit interface"_err_en_US,
4535                 binding->name(), details->symbol().name());
4536           } else {
4537             Say(binding->name(),
4538                 "'%s' must be either an accessible module procedure "
4539                 "or an external procedure with an explicit interface"_err_en_US,
4540                 binding->name());
4541           }
4542           context().SetError(*binding);
4543         }
4544       }
4545     }
4546   }
4547 }
4548 
4549 void DeclarationVisitor::Post(
4550     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4551   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4552     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4553   }
4554   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4555     for (auto &bindingName : x.bindingNames) {
4556       if (auto *s{
4557               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4558         SetPassNameOn(*s);
4559         if (!GetAttrs().test(Attr::DEFERRED)) {
4560           context().SetError(*s);
4561         }
4562       }
4563     }
4564   }
4565 }
4566 
4567 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4568   if (currScope().IsDerivedType() && currScope().symbol()) {
4569     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4570       for (const auto &subrName : x.v) {
4571         if (const auto *name{ResolveName(subrName)}) {
4572           auto pair{
4573               details->finals().emplace(name->source, DEREF(name->symbol))};
4574           if (!pair.second) { // C787
4575             Say(name->source,
4576                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4577                 name->source)
4578                 .Attach(pair.first->first,
4579                     "earlier appearance of this FINAL subroutine"_en_US);
4580           }
4581         }
4582       }
4583     }
4584   }
4585 }
4586 
4587 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4588   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4589   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4590   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4591   auto info{GenericSpecInfo{genericSpec.value()}};
4592   SourceName symbolName{info.symbolName()};
4593   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4594                             : derivedTypeInfo_.privateBindings};
4595   auto *genericSymbol{FindInScope(symbolName)};
4596   if (genericSymbol) {
4597     if (!genericSymbol->has<GenericDetails>()) {
4598       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4599     }
4600   } else {
4601     // look in parent types:
4602     Symbol *inheritedSymbol{nullptr};
4603     for (const auto &name : GetAllNames(context(), symbolName)) {
4604       inheritedSymbol = currScope().FindComponent(SourceName{name});
4605       if (inheritedSymbol) {
4606         break;
4607       }
4608     }
4609     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4610       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4611     }
4612   }
4613   if (genericSymbol) {
4614     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4615   } else {
4616     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4617     if (!genericSymbol) {
4618       return false;
4619     }
4620     if (isPrivate) {
4621       genericSymbol->attrs().set(Attr::PRIVATE);
4622     }
4623   }
4624   for (const parser::Name &bindingName : bindingNames) {
4625     genericBindings_.emplace(genericSymbol, &bindingName);
4626   }
4627   info.Resolve(genericSymbol);
4628   return false;
4629 }
4630 
4631 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4632 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4633   const auto &structureStatement{
4634       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4635   auto saveDerivedTypeInfo{derivedTypeInfo_};
4636   derivedTypeInfo_ = {};
4637   derivedTypeInfo_.isStructure = true;
4638   derivedTypeInfo_.sequence = true;
4639   Scope *previousStructure{nullptr};
4640   if (saveDerivedTypeInfo.isStructure) {
4641     previousStructure = &currScope();
4642     PopScope();
4643   }
4644   const parser::StructureStmt &structStmt{structureStatement.statement};
4645   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4646   if (!name) {
4647     // Construct a distinct generated name for an anonymous structure
4648     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4649     mutableName.emplace(
4650         parser::Name{context().GetTempName(currScope()), nullptr});
4651   }
4652   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4653   symbol.ReplaceName(name->source);
4654   symbol.get<DerivedTypeDetails>().set_sequence(true);
4655   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4656   derivedTypeInfo_.type = &symbol;
4657   PushScope(Scope::Kind::DerivedType, &symbol);
4658   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4659   Walk(fields);
4660   PopScope();
4661   // Complete the definition
4662   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4663   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4664   derivedTypeSpec.CookParameters(GetFoldingContext());
4665   derivedTypeSpec.EvaluateParameters(context());
4666   DeclTypeSpec &type{currScope().MakeDerivedType(
4667       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4668   type.derivedTypeSpec().Instantiate(currScope());
4669   // Restore previous structure definition context, if any
4670   derivedTypeInfo_ = saveDerivedTypeInfo;
4671   if (previousStructure) {
4672     PushScope(*previousStructure);
4673   }
4674   // Handle any entity declarations on the STRUCTURE statement
4675   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4676   if (!decls.empty()) {
4677     BeginDecl();
4678     SetDeclTypeSpec(type);
4679     Walk(decls);
4680     EndDecl();
4681   }
4682   return false;
4683 }
4684 
4685 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
4686   Say("UNION is not yet supported"_err_en_US); // TODO
4687   return true;
4688 }
4689 
4690 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
4691   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4692           x.u)) {
4693     BeginDecl();
4694   }
4695   return true;
4696 }
4697 
4698 void DeclarationVisitor::Post(const parser::StructureField &x) {
4699   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4700           x.u)) {
4701     EndDecl();
4702   }
4703 }
4704 
4705 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4706   BeginDeclTypeSpec();
4707   return true;
4708 }
4709 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4710   EndDeclTypeSpec();
4711 }
4712 
4713 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4714   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4715   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4716   if (!type) {
4717     return false;
4718   }
4719   const DerivedTypeSpec *spec{type->AsDerived()};
4720   const Scope *typeScope{spec ? spec->scope() : nullptr};
4721   if (!typeScope) {
4722     return false;
4723   }
4724 
4725   // N.B C7102 is implicitly enforced by having inaccessible types not
4726   // being found in resolution.
4727   // More constraints are enforced in expression.cpp so that they
4728   // can apply to structure constructors that have been converted
4729   // from misparsed function references.
4730   for (const auto &component :
4731       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4732     // Visit the component spec expression, but not the keyword, since
4733     // we need to resolve its symbol in the scope of the derived type.
4734     Walk(std::get<parser::ComponentDataSource>(component.t));
4735     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4736       FindInTypeOrParents(*typeScope, kw->v);
4737     }
4738   }
4739   return false;
4740 }
4741 
4742 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4743   for (const parser::BasedPointer &bp : x.v) {
4744     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4745     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4746     auto *pointer{FindSymbol(pointerName)};
4747     if (!pointer) {
4748       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4749     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4750       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4751     } else if (pointer->Rank() > 0) {
4752       SayWithDecl(pointerName, *pointer,
4753           "Cray pointer '%s' must be a scalar"_err_en_US);
4754     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4755       Say(pointerName,
4756           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4757     }
4758     pointer->set(Symbol::Flag::CrayPointer);
4759     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4760         context().defaultKinds().subscriptIntegerKind())};
4761     const auto *type{pointer->GetType()};
4762     if (!type) {
4763       pointer->SetType(pointerType);
4764     } else if (*type != pointerType) {
4765       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4766           pointerName.source, pointerType.AsFortran());
4767     }
4768     if (ResolveName(pointeeName)) {
4769       Symbol &pointee{*pointeeName.symbol};
4770       if (pointee.has<UseDetails>()) {
4771         Say(pointeeName,
4772             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4773         continue;
4774       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4775         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4776         continue;
4777       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4778         Say(pointeeName,
4779             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4780       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4781         Say(pointeeName,
4782             "'%s' was already declared as a Cray pointee"_err_en_US);
4783       } else {
4784         pointee.set(Symbol::Flag::CrayPointee);
4785       }
4786       if (const auto *pointeeType{pointee.GetType()}) {
4787         if (const auto *derived{pointeeType->AsDerived()}) {
4788           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
4789             Say(pointeeName,
4790                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
4791           }
4792         }
4793       }
4794       // process the pointee array-spec, if present
4795       BeginArraySpec();
4796       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
4797       const auto &spec{arraySpec()};
4798       if (!spec.empty()) {
4799         auto &details{pointee.get<ObjectEntityDetails>()};
4800         if (details.shape().empty()) {
4801           details.set_shape(spec);
4802         } else {
4803           SayWithDecl(pointeeName, pointee,
4804               "Array spec was already declared for '%s'"_err_en_US);
4805         }
4806       }
4807       ClearArraySpec();
4808       currScope().add_crayPointer(pointeeName.source, *pointer);
4809     }
4810   }
4811   return false;
4812 }
4813 
4814 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
4815   if (!CheckNotInBlock("NAMELIST")) { // C1107
4816     return false;
4817   }
4818 
4819   NamelistDetails details;
4820   for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
4821     auto *symbol{FindSymbol(name)};
4822     if (!symbol) {
4823       symbol = &MakeSymbol(name, ObjectEntityDetails{});
4824       ApplyImplicitRules(*symbol);
4825     } else if (!ConvertToObjectEntity(*symbol)) {
4826       SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
4827     }
4828     symbol->GetUltimate().set(Symbol::Flag::InNamelist);
4829     details.add_object(*symbol);
4830   }
4831 
4832   const auto &groupName{std::get<parser::Name>(x.t)};
4833   auto *groupSymbol{FindInScope(groupName)};
4834   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
4835     groupSymbol = &MakeSymbol(groupName, std::move(details));
4836     groupSymbol->ReplaceName(groupName.source);
4837   }
4838   groupSymbol->get<NamelistDetails>().add_objects(details.objects());
4839   return false;
4840 }
4841 
4842 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
4843   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
4844     auto *symbol{FindSymbol(*name)};
4845     if (!symbol) {
4846       Say(*name, "Namelist group '%s' not found"_err_en_US);
4847     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
4848       SayWithDecl(
4849           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
4850     }
4851   }
4852   return true;
4853 }
4854 
4855 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
4856   CheckNotInBlock("COMMON"); // C1107
4857   return true;
4858 }
4859 
4860 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
4861   BeginArraySpec();
4862   return true;
4863 }
4864 
4865 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
4866   const auto &name{std::get<parser::Name>(x.t)};
4867   DeclareObjectEntity(name);
4868   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
4869   if (!pair.second) {
4870     const SourceName &prev{*pair.first};
4871     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
4872         "Previous occurrence of '%s' in a COMMON block"_en_US);
4873   }
4874 }
4875 
4876 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
4877   // save equivalence sets to be processed after specification part
4878   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
4879     for (const std::list<parser::EquivalenceObject> &set : x.v) {
4880       specPartState_.equivalenceSets.push_back(&set);
4881     }
4882   }
4883   return false; // don't implicitly declare names yet
4884 }
4885 
4886 void DeclarationVisitor::CheckEquivalenceSets() {
4887   EquivalenceSets equivSets{context()};
4888   inEquivalenceStmt_ = true;
4889   for (const auto *set : specPartState_.equivalenceSets) {
4890     const auto &source{set->front().v.value().source};
4891     if (set->size() <= 1) { // R871
4892       Say(source, "Equivalence set must have more than one object"_err_en_US);
4893     }
4894     for (const parser::EquivalenceObject &object : *set) {
4895       const auto &designator{object.v.value()};
4896       // The designator was not resolved when it was encountered so do it now.
4897       // AnalyzeExpr causes array sections to be changed to substrings as needed
4898       Walk(designator);
4899       if (AnalyzeExpr(context(), designator)) {
4900         equivSets.AddToSet(designator);
4901       }
4902     }
4903     equivSets.FinishSet(source);
4904   }
4905   inEquivalenceStmt_ = false;
4906   for (auto &set : equivSets.sets()) {
4907     if (!set.empty()) {
4908       currScope().add_equivalenceSet(std::move(set));
4909     }
4910   }
4911   specPartState_.equivalenceSets.clear();
4912 }
4913 
4914 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
4915   if (x.v.empty()) {
4916     specPartState_.saveInfo.saveAll = currStmtSource();
4917     currScope().set_hasSAVE();
4918   } else {
4919     for (const parser::SavedEntity &y : x.v) {
4920       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
4921       const auto &name{std::get<parser::Name>(y.t)};
4922       if (kind == parser::SavedEntity::Kind::Common) {
4923         MakeCommonBlockSymbol(name);
4924         AddSaveName(specPartState_.saveInfo.commons, name.source);
4925       } else {
4926         HandleAttributeStmt(Attr::SAVE, name);
4927       }
4928     }
4929   }
4930   return false;
4931 }
4932 
4933 void DeclarationVisitor::CheckSaveStmts() {
4934   for (const SourceName &name : specPartState_.saveInfo.entities) {
4935     auto *symbol{FindInScope(name)};
4936     if (!symbol) {
4937       // error was reported
4938     } else if (specPartState_.saveInfo.saveAll) {
4939       // C889 - note that pgi, ifort, xlf do not enforce this constraint
4940       Say2(name,
4941           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
4942           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
4943     } else if (auto msg{CheckSaveAttr(*symbol)}) {
4944       Say(name, std::move(*msg));
4945       context().SetError(*symbol);
4946     } else {
4947       SetSaveAttr(*symbol);
4948     }
4949   }
4950   for (const SourceName &name : specPartState_.saveInfo.commons) {
4951     if (auto *symbol{currScope().FindCommonBlock(name)}) {
4952       auto &objects{symbol->get<CommonBlockDetails>().objects()};
4953       if (objects.empty()) {
4954         if (currScope().kind() != Scope::Kind::Block) {
4955           Say(name,
4956               "'%s' appears as a COMMON block in a SAVE statement but not in"
4957               " a COMMON statement"_err_en_US);
4958         } else { // C1108
4959           Say(name,
4960               "SAVE statement in BLOCK construct may not contain a"
4961               " common block name '%s'"_err_en_US);
4962         }
4963       } else {
4964         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
4965           SetSaveAttr(*object);
4966         }
4967       }
4968     }
4969   }
4970   if (specPartState_.saveInfo.saveAll) {
4971     // Apply SAVE attribute to applicable symbols
4972     for (auto pair : currScope()) {
4973       auto &symbol{*pair.second};
4974       if (!CheckSaveAttr(symbol)) {
4975         SetSaveAttr(symbol);
4976       }
4977     }
4978   }
4979   specPartState_.saveInfo = {};
4980 }
4981 
4982 // If SAVE attribute can't be set on symbol, return error message.
4983 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
4984     const Symbol &symbol) {
4985   if (IsDummy(symbol)) {
4986     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
4987   } else if (symbol.IsFuncResult()) {
4988     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
4989   } else if (symbol.has<ProcEntityDetails>() &&
4990       !symbol.attrs().test(Attr::POINTER)) {
4991     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
4992   } else if (IsAutomatic(symbol)) {
4993     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
4994   } else {
4995     return std::nullopt;
4996   }
4997 }
4998 
4999 // Record SAVEd names in specPartState_.saveInfo.entities.
5000 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
5001   if (attrs.test(Attr::SAVE)) {
5002     AddSaveName(specPartState_.saveInfo.entities, name);
5003   }
5004   return attrs;
5005 }
5006 
5007 // Record a name in a set of those to be saved.
5008 void DeclarationVisitor::AddSaveName(
5009     std::set<SourceName> &set, const SourceName &name) {
5010   auto pair{set.insert(name)};
5011   if (!pair.second) {
5012     Say2(name, "SAVE attribute was already specified on '%s'"_en_US,
5013         *pair.first, "Previous specification of SAVE attribute"_en_US);
5014   }
5015 }
5016 
5017 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
5018 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
5019   if (!IsSaved(symbol)) {
5020     symbol.attrs().set(Attr::SAVE);
5021   }
5022 }
5023 
5024 // Check types of common block objects, now that they are known.
5025 void DeclarationVisitor::CheckCommonBlocks() {
5026   // check for empty common blocks
5027   for (const auto &pair : currScope().commonBlocks()) {
5028     const auto &symbol{*pair.second};
5029     if (symbol.get<CommonBlockDetails>().objects().empty() &&
5030         symbol.attrs().test(Attr::BIND_C)) {
5031       Say(symbol.name(),
5032           "'%s' appears as a COMMON block in a BIND statement but not in"
5033           " a COMMON statement"_err_en_US);
5034     }
5035   }
5036   // check objects in common blocks
5037   for (const auto &name : specPartState_.commonBlockObjects) {
5038     const auto *symbol{currScope().FindSymbol(name)};
5039     if (!symbol) {
5040       continue;
5041     }
5042     const auto &attrs{symbol->attrs()};
5043     if (attrs.test(Attr::ALLOCATABLE)) {
5044       Say(name,
5045           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
5046     } else if (attrs.test(Attr::BIND_C)) {
5047       Say(name,
5048           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
5049     } else if (IsDummy(*symbol)) {
5050       Say(name,
5051           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5052     } else if (symbol->IsFuncResult()) {
5053       Say(name,
5054           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5055     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5056       if (type->category() == DeclTypeSpec::ClassStar) {
5057         Say(name,
5058             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5059       } else if (const auto *derived{type->AsDerived()}) {
5060         auto &typeSymbol{derived->typeSymbol()};
5061         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5062             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5063           Say(name,
5064               "Derived type '%s' in COMMON block must have the BIND or"
5065               " SEQUENCE attribute"_err_en_US);
5066         }
5067         CheckCommonBlockDerivedType(name, typeSymbol);
5068       }
5069     }
5070   }
5071   specPartState_.commonBlockObjects = {};
5072 }
5073 
5074 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5075   return Resolve(name, currScope().MakeCommonBlock(name.source));
5076 }
5077 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5078     const std::optional<parser::Name> &name) {
5079   if (name) {
5080     return MakeCommonBlockSymbol(*name);
5081   } else {
5082     return MakeCommonBlockSymbol(parser::Name{});
5083   }
5084 }
5085 
5086 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5087   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5088 }
5089 
5090 // Check if this derived type can be in a COMMON block.
5091 void DeclarationVisitor::CheckCommonBlockDerivedType(
5092     const SourceName &name, const Symbol &typeSymbol) {
5093   if (const auto *scope{typeSymbol.scope()}) {
5094     for (const auto &pair : *scope) {
5095       const Symbol &component{*pair.second};
5096       if (component.attrs().test(Attr::ALLOCATABLE)) {
5097         Say2(name,
5098             "Derived type variable '%s' may not appear in a COMMON block"
5099             " due to ALLOCATABLE component"_err_en_US,
5100             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5101         return;
5102       }
5103       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5104       if (component.test(Symbol::Flag::InDataStmt) ||
5105           (details && details->init())) {
5106         Say2(name,
5107             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5108             component.name(), "Component with default initialization"_en_US);
5109         return;
5110       }
5111       if (details) {
5112         if (const auto *type{details->type()}) {
5113           if (const auto *derived{type->AsDerived()}) {
5114             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5115           }
5116         }
5117       }
5118     }
5119   }
5120 }
5121 
5122 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5123     const parser::Name &name) {
5124   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5125           name.source.ToString())}) {
5126     // Unrestricted specific intrinsic function names (e.g., "cos")
5127     // are acceptable as procedure interfaces.
5128     Symbol &symbol{
5129         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5130     symbol.set_details(ProcEntityDetails{});
5131     symbol.set(Symbol::Flag::Function);
5132     if (interface->IsElemental()) {
5133       symbol.attrs().set(Attr::ELEMENTAL);
5134     }
5135     if (interface->IsPure()) {
5136       symbol.attrs().set(Attr::PURE);
5137     }
5138     Resolve(name, symbol);
5139     return true;
5140   } else {
5141     return false;
5142   }
5143 }
5144 
5145 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5146 bool DeclarationVisitor::PassesSharedLocalityChecks(
5147     const parser::Name &name, Symbol &symbol) {
5148   if (!IsVariableName(symbol)) {
5149     SayLocalMustBeVariable(name, symbol); // C1124
5150     return false;
5151   }
5152   if (symbol.owner() == currScope()) { // C1125 and C1126
5153     SayAlreadyDeclared(name, symbol);
5154     return false;
5155   }
5156   return true;
5157 }
5158 
5159 // Checks for locality-specs LOCAL and LOCAL_INIT
5160 bool DeclarationVisitor::PassesLocalityChecks(
5161     const parser::Name &name, Symbol &symbol) {
5162   if (IsAllocatable(symbol)) { // C1128
5163     SayWithDecl(name, symbol,
5164         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5165     return false;
5166   }
5167   if (IsOptional(symbol)) { // C1128
5168     SayWithDecl(name, symbol,
5169         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5170     return false;
5171   }
5172   if (IsIntentIn(symbol)) { // C1128
5173     SayWithDecl(name, symbol,
5174         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5175     return false;
5176   }
5177   if (IsFinalizable(symbol)) { // C1128
5178     SayWithDecl(name, symbol,
5179         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5180     return false;
5181   }
5182   if (evaluate::IsCoarray(symbol)) { // C1128
5183     SayWithDecl(
5184         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5185     return false;
5186   }
5187   if (const DeclTypeSpec * type{symbol.GetType()}) {
5188     if (type->IsPolymorphic() && IsDummy(symbol) &&
5189         !IsPointer(symbol)) { // C1128
5190       SayWithDecl(name, symbol,
5191           "Nonpointer polymorphic argument '%s' not allowed in a "
5192           "locality-spec"_err_en_US);
5193       return false;
5194     }
5195   }
5196   if (IsAssumedSizeArray(symbol)) { // C1128
5197     SayWithDecl(name, symbol,
5198         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5199     return false;
5200   }
5201   if (std::optional<MessageFixedText> msg{
5202           WhyNotModifiable(symbol, currScope())}) {
5203     SayWithReason(name, symbol,
5204         "'%s' may not appear in a locality-spec because it is not "
5205         "definable"_err_en_US,
5206         std::move(*msg));
5207     return false;
5208   }
5209   return PassesSharedLocalityChecks(name, symbol);
5210 }
5211 
5212 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5213     const parser::Name &name) {
5214   Symbol *prev{FindSymbol(name)};
5215   if (!prev) {
5216     // Declare the name as an object in the enclosing scope so that
5217     // the name can't be repurposed there later as something else.
5218     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5219     ConvertToObjectEntity(*prev);
5220     ApplyImplicitRules(*prev);
5221   }
5222   return *prev;
5223 }
5224 
5225 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5226   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5227   if (!PassesLocalityChecks(name, prev)) {
5228     return nullptr;
5229   }
5230   return &MakeHostAssocSymbol(name, prev);
5231 }
5232 
5233 Symbol *DeclarationVisitor::DeclareStatementEntity(
5234     const parser::DoVariable &doVar,
5235     const std::optional<parser::IntegerTypeSpec> &type) {
5236   const parser::Name &name{doVar.thing.thing};
5237   const DeclTypeSpec *declTypeSpec{nullptr};
5238   if (auto *prev{FindSymbol(name)}) {
5239     if (prev->owner() == currScope()) {
5240       SayAlreadyDeclared(name, *prev);
5241       return nullptr;
5242     }
5243     name.symbol = nullptr;
5244     declTypeSpec = prev->GetType();
5245   }
5246   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5247   if (!symbol.has<ObjectEntityDetails>()) {
5248     return nullptr; // error was reported in DeclareEntity
5249   }
5250   if (type) {
5251     declTypeSpec = ProcessTypeSpec(*type);
5252   }
5253   if (declTypeSpec) {
5254     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5255     // declaration of this implied DO loop control variable.
5256     auto restorer{
5257         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5258     SetType(name, *declTypeSpec);
5259   } else {
5260     ApplyImplicitRules(symbol);
5261   }
5262   Symbol *result{Resolve(name, &symbol)};
5263   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5264   return result;
5265 }
5266 
5267 // Set the type of an entity or report an error.
5268 void DeclarationVisitor::SetType(
5269     const parser::Name &name, const DeclTypeSpec &type) {
5270   CHECK(name.symbol);
5271   auto &symbol{*name.symbol};
5272   if (charInfo_.length) { // Declaration has "*length" (R723)
5273     auto length{std::move(*charInfo_.length)};
5274     charInfo_.length.reset();
5275     if (type.category() == DeclTypeSpec::Character) {
5276       auto kind{type.characterTypeSpec().kind()};
5277       // Recurse with correct type.
5278       SetType(name,
5279           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5280       return;
5281     } else { // C753
5282       Say(name,
5283           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5284     }
5285   }
5286   auto *prevType{symbol.GetType()};
5287   if (!prevType) {
5288     symbol.SetType(type);
5289   } else if (symbol.has<UseDetails>()) {
5290     // error recovery case, redeclaration of use-associated name
5291   } else if (HadForwardRef(symbol)) {
5292     // error recovery after use of host-associated name
5293   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5294     SayWithDecl(
5295         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5296     context().SetError(symbol);
5297   } else if (type != *prevType) {
5298     SayWithDecl(name, symbol,
5299         "The type of '%s' has already been implicitly declared"_err_en_US);
5300     context().SetError(symbol);
5301   } else {
5302     symbol.set(Symbol::Flag::Implicit, false);
5303   }
5304 }
5305 
5306 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5307     const parser::Name &name) {
5308   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5309   if (!symbol || symbol->has<UnknownDetails>()) {
5310     if (allowForwardReferenceToDerivedType()) {
5311       if (!symbol) {
5312         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5313         Resolve(name, *symbol);
5314       };
5315       DerivedTypeDetails details;
5316       details.set_isForwardReferenced(true);
5317       symbol->set_details(std::move(details));
5318     } else { // C732
5319       Say(name, "Derived type '%s' not found"_err_en_US);
5320       return std::nullopt;
5321     }
5322   }
5323   if (CheckUseError(name)) {
5324     return std::nullopt;
5325   }
5326   symbol = &symbol->GetUltimate();
5327   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
5328     if (details->derivedType()) {
5329       symbol = details->derivedType();
5330     }
5331   }
5332   if (symbol->has<DerivedTypeDetails>()) {
5333     return DerivedTypeSpec{name.source, *symbol};
5334   } else {
5335     Say(name, "'%s' is not a derived type"_err_en_US);
5336     return std::nullopt;
5337   }
5338 }
5339 
5340 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5341     const parser::Name &typeName, const parser::Name *extendsName) {
5342   if (!extendsName) {
5343     return std::nullopt;
5344   } else if (typeName.source == extendsName->source) {
5345     Say(extendsName->source,
5346         "Derived type '%s' cannot extend itself"_err_en_US);
5347     return std::nullopt;
5348   } else {
5349     return ResolveDerivedType(*extendsName);
5350   }
5351 }
5352 
5353 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5354   // The symbol is checked later by CheckExplicitInterface() and
5355   // CheckBindings().  It can be a forward reference.
5356   if (!NameIsKnownOrIntrinsic(name)) {
5357     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5358     Resolve(name, symbol);
5359   }
5360   return name.symbol;
5361 }
5362 
5363 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5364   if (const Symbol * symbol{name.symbol}) {
5365     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5366       Say(name,
5367           "'%s' must be an abstract interface or a procedure with "
5368           "an explicit interface"_err_en_US,
5369           symbol->name());
5370     }
5371   }
5372 }
5373 
5374 // Create a symbol for a type parameter, component, or procedure binding in
5375 // the current derived type scope. Return false on error.
5376 Symbol *DeclarationVisitor::MakeTypeSymbol(
5377     const parser::Name &name, Details &&details) {
5378   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5379 }
5380 Symbol *DeclarationVisitor::MakeTypeSymbol(
5381     const SourceName &name, Details &&details) {
5382   Scope &derivedType{currScope()};
5383   CHECK(derivedType.IsDerivedType());
5384   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5385     Say2(name,
5386         "Type parameter, component, or procedure binding '%s'"
5387         " already defined in this type"_err_en_US,
5388         *symbol, "Previous definition of '%s'"_en_US);
5389     return nullptr;
5390   } else {
5391     auto attrs{GetAttrs()};
5392     // Apply binding-private-stmt if present and this is a procedure binding
5393     if (derivedTypeInfo_.privateBindings &&
5394         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5395         std::holds_alternative<ProcBindingDetails>(details)) {
5396       attrs.set(Attr::PRIVATE);
5397     }
5398     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5399     if (result.has<TypeParamDetails>()) {
5400       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5401     }
5402     return &result;
5403   }
5404 }
5405 
5406 // Return true if it is ok to declare this component in the current scope.
5407 // Otherwise, emit an error and return false.
5408 bool DeclarationVisitor::OkToAddComponent(
5409     const parser::Name &name, const Symbol *extends) {
5410   for (const Scope *scope{&currScope()}; scope;) {
5411     CHECK(scope->IsDerivedType());
5412     if (auto *prev{FindInScope(*scope, name)}) {
5413       if (!context().HasError(*prev)) {
5414         auto msg{""_en_US};
5415         if (extends) {
5416           msg = "Type cannot be extended as it has a component named"
5417                 " '%s'"_err_en_US;
5418         } else if (prev->test(Symbol::Flag::ParentComp)) {
5419           msg = "'%s' is a parent type of this type and so cannot be"
5420                 " a component"_err_en_US;
5421         } else if (scope != &currScope()) {
5422           msg = "Component '%s' is already declared in a parent of this"
5423                 " derived type"_err_en_US;
5424         } else {
5425           msg = "Component '%s' is already declared in this"
5426                 " derived type"_err_en_US;
5427         }
5428         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5429       }
5430       return false;
5431     }
5432     if (scope == &currScope() && extends) {
5433       // The parent component has not yet been added to the scope.
5434       scope = extends->scope();
5435     } else {
5436       scope = scope->GetDerivedTypeParent();
5437     }
5438   }
5439   return true;
5440 }
5441 
5442 ParamValue DeclarationVisitor::GetParamValue(
5443     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5444   return std::visit(
5445       common::visitors{
5446           [=](const parser::ScalarIntExpr &x) { // C704
5447             return ParamValue{EvaluateIntExpr(x), attr};
5448           },
5449           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5450           [=](const parser::TypeParamValue::Deferred &) {
5451             return ParamValue::Deferred(attr);
5452           },
5453       },
5454       x.u);
5455 }
5456 
5457 // ConstructVisitor implementation
5458 
5459 void ConstructVisitor::ResolveIndexName(
5460     const parser::ConcurrentControl &control) {
5461   const parser::Name &name{std::get<parser::Name>(control.t)};
5462   auto *prev{FindSymbol(name)};
5463   if (prev) {
5464     if (prev->owner().kind() == Scope::Kind::Forall ||
5465         prev->owner() == currScope()) {
5466       SayAlreadyDeclared(name, *prev);
5467       return;
5468     }
5469     name.symbol = nullptr;
5470   }
5471   auto &symbol{DeclareObjectEntity(name)};
5472   if (symbol.GetType()) {
5473     // type came from explicit type-spec
5474   } else if (!prev) {
5475     ApplyImplicitRules(symbol);
5476   } else {
5477     const Symbol &prevRoot{ResolveAssociations(*prev)};
5478     // prev could be host- use- or construct-associated with another symbol
5479     if (!prevRoot.has<ObjectEntityDetails>() &&
5480         !prevRoot.has<EntityDetails>()) {
5481       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5482           *prev, "Previous declaration of '%s'"_en_US);
5483       context().SetError(symbol);
5484       return;
5485     } else {
5486       if (const auto *type{prevRoot.GetType()}) {
5487         symbol.SetType(*type);
5488       }
5489       if (prevRoot.IsObjectArray()) {
5490         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5491         return;
5492       }
5493     }
5494   }
5495   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5496 }
5497 
5498 // We need to make sure that all of the index-names get declared before the
5499 // expressions in the loop control are evaluated so that references to the
5500 // index-names in the expressions are correctly detected.
5501 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5502   BeginDeclTypeSpec();
5503   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5504   const auto &controls{
5505       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5506   for (const auto &control : controls) {
5507     ResolveIndexName(control);
5508   }
5509   Walk(controls);
5510   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5511   EndDeclTypeSpec();
5512   return false;
5513 }
5514 
5515 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5516   for (auto &name : x.v) {
5517     if (auto *symbol{DeclareLocalEntity(name)}) {
5518       symbol->set(Symbol::Flag::LocalityLocal);
5519     }
5520   }
5521   return false;
5522 }
5523 
5524 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5525   for (auto &name : x.v) {
5526     if (auto *symbol{DeclareLocalEntity(name)}) {
5527       symbol->set(Symbol::Flag::LocalityLocalInit);
5528     }
5529   }
5530   return false;
5531 }
5532 
5533 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5534   for (const auto &name : x.v) {
5535     if (!FindSymbol(name)) {
5536       Say(name, "Variable '%s' with SHARED locality implicitly declared"_en_US);
5537     }
5538     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5539     if (PassesSharedLocalityChecks(name, prev)) {
5540       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5541     }
5542   }
5543   return false;
5544 }
5545 
5546 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5547   ProcessTypeSpec(x.type);
5548   Walk(x.values);
5549   return false;
5550 }
5551 
5552 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5553 // enclosing ac-implied-do
5554 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5555   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5556   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5557   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5558   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5559   // F'2018 has the scope of the implied DO variable covering the entire
5560   // implied DO production (19.4(5)), which seems wrong in cases where the name
5561   // of the implied DO variable appears in one of the bound expressions. Thus
5562   // this extension, which shrinks the scope of the variable to exclude the
5563   // expressions in the bounds.
5564   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5565   Walk(bounds.lower);
5566   Walk(bounds.upper);
5567   Walk(bounds.step);
5568   EndCheckOnIndexUseInOwnBounds(restore);
5569   PushScope(Scope::Kind::ImpliedDos, nullptr);
5570   DeclareStatementEntity(bounds.name, type);
5571   Walk(values);
5572   PopScope();
5573   return false;
5574 }
5575 
5576 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5577   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5578   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5579   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5580   // See comment in Pre(AcImpliedDo) above.
5581   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5582   Walk(bounds.lower);
5583   Walk(bounds.upper);
5584   Walk(bounds.step);
5585   EndCheckOnIndexUseInOwnBounds(restore);
5586   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5587   if (pushScope) {
5588     PushScope(Scope::Kind::ImpliedDos, nullptr);
5589   }
5590   DeclareStatementEntity(bounds.name, type);
5591   Walk(objects);
5592   if (pushScope) {
5593     PopScope();
5594   }
5595   return false;
5596 }
5597 
5598 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5599 // statement so that the predicate IsInitialized() will be true
5600 // during semantic analysis before the symbol's initializer is constructed.
5601 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5602   std::visit(
5603       common::visitors{
5604           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5605             Walk(y.thing.value());
5606             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5607             if (first.symbol) {
5608               first.symbol->set(Symbol::Flag::InDataStmt);
5609             }
5610           },
5611           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5612       },
5613       x.u);
5614   return false;
5615 }
5616 
5617 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5618   std::visit(common::visitors{
5619                  [&](const Indirection<parser::Variable> &y) {
5620                    Walk(y.value());
5621                    const parser::Name &first{parser::GetFirstName(y.value())};
5622                    if (first.symbol) {
5623                      first.symbol->set(Symbol::Flag::InDataStmt);
5624                    }
5625                  },
5626                  [&](const parser::DataImpliedDo &y) {
5627                    PushScope(Scope::Kind::ImpliedDos, nullptr);
5628                    Walk(y);
5629                    PopScope();
5630                  },
5631              },
5632       x.u);
5633   return false;
5634 }
5635 
5636 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5637   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5638   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5639   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5640     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5641       if (const Symbol * symbol{FindSymbol(*name)}) {
5642         const Symbol &ultimate{symbol->GetUltimate()};
5643         if (ultimate.has<DerivedTypeDetails>()) {
5644           mutableData.u = elem->ConvertToStructureConstructor(
5645               DerivedTypeSpec{name->source, ultimate});
5646         }
5647       }
5648     }
5649   }
5650   return true;
5651 }
5652 
5653 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5654   if (x.IsDoConcurrent()) {
5655     PushScope(Scope::Kind::Block, nullptr);
5656   }
5657   return true;
5658 }
5659 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5660   if (x.IsDoConcurrent()) {
5661     PopScope();
5662   }
5663 }
5664 
5665 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5666   PushScope(Scope::Kind::Forall, nullptr);
5667   return true;
5668 }
5669 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5670 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5671   PushScope(Scope::Kind::Forall, nullptr);
5672   return true;
5673 }
5674 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5675 
5676 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5677   CheckDef(x.v);
5678   PushScope(Scope::Kind::Block, nullptr);
5679   return false;
5680 }
5681 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5682   PopScope();
5683   CheckRef(x.v);
5684   return false;
5685 }
5686 
5687 void ConstructVisitor::Post(const parser::Selector &x) {
5688   GetCurrentAssociation().selector = ResolveSelector(x);
5689 }
5690 
5691 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
5692   CheckDef(x.t);
5693   PushScope(Scope::Kind::Block, nullptr);
5694   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
5695   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
5696     SetCurrentAssociation(nthLastAssoc);
5697     if (auto *symbol{MakeAssocEntity()}) {
5698       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
5699         Say("Selector must not be a coindexed object"_err_en_US);
5700       }
5701       SetTypeFromAssociation(*symbol);
5702       SetAttrsFromAssociation(*symbol);
5703     }
5704   }
5705   PopAssociation(assocCount);
5706 }
5707 
5708 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5709   PopScope();
5710   CheckRef(x.v);
5711 }
5712 
5713 bool ConstructVisitor::Pre(const parser::Association &x) {
5714   PushAssociation();
5715   const auto &name{std::get<parser::Name>(x.t)};
5716   GetCurrentAssociation().name = &name;
5717   return true;
5718 }
5719 
5720 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5721   CheckDef(x.t);
5722   PushScope(Scope::Kind::Block, nullptr);
5723   PushAssociation();
5724   return true;
5725 }
5726 
5727 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5728   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5729   const auto &name{std::get<parser::Name>(decl.t)};
5730   if (auto *symbol{FindInScope(name)}) {
5731     const auto &selector{std::get<parser::Selector>(x.t)};
5732     if (auto sel{ResolveSelector(selector)}) {
5733       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5734       if (!whole || whole->Corank() == 0) {
5735         Say(sel.source, // C1116
5736             "Selector in coarray association must name a coarray"_err_en_US);
5737       } else if (auto dynType{sel.expr->GetType()}) {
5738         if (!symbol->GetType()) {
5739           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5740         }
5741       }
5742     }
5743   }
5744 }
5745 
5746 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5747   PopAssociation();
5748   PopScope();
5749   CheckRef(x.t);
5750 }
5751 
5752 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5753   PushAssociation();
5754   return true;
5755 }
5756 
5757 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5758   PopAssociation();
5759 }
5760 
5761 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
5762   auto &association{GetCurrentAssociation()};
5763   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5764     // This isn't a name in the current scope, it is in each TypeGuardStmt
5765     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
5766     association.name = &*name;
5767     auto exprType{association.selector.expr->GetType()};
5768     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
5769       Say("Selector must not be a coindexed object"_err_en_US);
5770     }
5771     if (exprType && !exprType->IsPolymorphic()) { // C1159
5772       Say(association.selector.source,
5773           "Selector '%s' in SELECT TYPE statement must be "
5774           "polymorphic"_err_en_US);
5775     }
5776   } else {
5777     if (const Symbol *
5778         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5779       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
5780       if (!IsVariableName(*whole)) {
5781         Say(association.selector.source, // C901
5782             "Selector is not a variable"_err_en_US);
5783         association = {};
5784       }
5785       if (const DeclTypeSpec * type{whole->GetType()}) {
5786         if (!type->IsPolymorphic()) { // C1159
5787           Say(association.selector.source,
5788               "Selector '%s' in SELECT TYPE statement must be "
5789               "polymorphic"_err_en_US);
5790         }
5791       }
5792     } else {
5793       Say(association.selector.source, // C1157
5794           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
5795       association = {};
5796     }
5797   }
5798 }
5799 
5800 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
5801   auto &association{GetCurrentAssociation()};
5802   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5803     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
5804     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
5805     association.name = &*name;
5806   }
5807 }
5808 
5809 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
5810   PushScope(Scope::Kind::Block, nullptr);
5811   return true;
5812 }
5813 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
5814   PopScope();
5815 }
5816 
5817 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
5818   PushScope(Scope::Kind::Block, nullptr);
5819   return true;
5820 }
5821 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
5822   PopScope();
5823 }
5824 
5825 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
5826   if (auto *symbol{MakeAssocEntity()}) {
5827     if (std::holds_alternative<parser::Default>(x.u)) {
5828       SetTypeFromAssociation(*symbol);
5829     } else if (const auto *type{GetDeclTypeSpec()}) {
5830       symbol->SetType(*type);
5831     }
5832     SetAttrsFromAssociation(*symbol);
5833   }
5834 }
5835 
5836 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
5837   if (auto *symbol{MakeAssocEntity()}) {
5838     SetTypeFromAssociation(*symbol);
5839     SetAttrsFromAssociation(*symbol);
5840     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
5841       if (auto val{EvaluateInt64(context(), *init)}) {
5842         auto &details{symbol->get<AssocEntityDetails>()};
5843         details.set_rank(*val);
5844       }
5845     }
5846   }
5847 }
5848 
5849 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
5850   PushAssociation();
5851   return true;
5852 }
5853 
5854 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
5855   PopAssociation();
5856 }
5857 
5858 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
5859   if (x) {
5860     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
5861   }
5862   return true;
5863 }
5864 
5865 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
5866   if (x) {
5867     // Just add an occurrence of this name; checking is done in ValidateLabels
5868     FindSymbol(*x);
5869   }
5870 }
5871 
5872 // Make a symbol for the associating entity of the current association.
5873 Symbol *ConstructVisitor::MakeAssocEntity() {
5874   Symbol *symbol{nullptr};
5875   auto &association{GetCurrentAssociation()};
5876   if (association.name) {
5877     symbol = &MakeSymbol(*association.name, UnknownDetails{});
5878     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
5879       Say(*association.name, // C1102
5880           "The associate name '%s' is already used in this associate statement"_err_en_US);
5881       return nullptr;
5882     }
5883   } else if (const Symbol *
5884       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5885     symbol = &MakeSymbol(whole->name());
5886   } else {
5887     return nullptr;
5888   }
5889   if (auto &expr{association.selector.expr}) {
5890     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
5891   } else {
5892     symbol->set_details(AssocEntityDetails{});
5893   }
5894   return symbol;
5895 }
5896 
5897 // Set the type of symbol based on the current association selector.
5898 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
5899   auto &details{symbol.get<AssocEntityDetails>()};
5900   const MaybeExpr *pexpr{&details.expr()};
5901   if (!*pexpr) {
5902     pexpr = &GetCurrentAssociation().selector.expr;
5903   }
5904   if (*pexpr) {
5905     const SomeExpr &expr{**pexpr};
5906     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
5907       if (const auto *charExpr{
5908               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
5909                   expr)}) {
5910         symbol.SetType(ToDeclTypeSpec(std::move(*type),
5911             FoldExpr(
5912                 std::visit([](const auto &kindChar) { return kindChar.LEN(); },
5913                     charExpr->u))));
5914       } else {
5915         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
5916       }
5917     } else {
5918       // BOZ literals, procedure designators, &c. are not acceptable
5919       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
5920     }
5921   }
5922 }
5923 
5924 // If current selector is a variable, set some of its attributes on symbol.
5925 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
5926   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
5927   symbol.attrs() |= attrs &
5928       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
5929   if (attrs.test(Attr::POINTER)) {
5930     symbol.attrs().set(Attr::TARGET);
5931   }
5932 }
5933 
5934 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
5935     const parser::Selector &x) {
5936   return std::visit(common::visitors{
5937                         [&](const parser::Expr &expr) {
5938                           return Selector{expr.source, EvaluateExpr(x)};
5939                         },
5940                         [&](const parser::Variable &var) {
5941                           return Selector{var.GetSource(), EvaluateExpr(x)};
5942                         },
5943                     },
5944       x.u);
5945 }
5946 
5947 // Set the current association to the nth to the last association on the
5948 // association stack.  The top of the stack is at n = 1.  This allows access
5949 // to the interior of a list of associations at the top of the stack.
5950 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
5951   CHECK(n > 0 && n <= associationStack_.size());
5952   currentAssociation_ = &associationStack_[associationStack_.size() - n];
5953 }
5954 
5955 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
5956   CHECK(currentAssociation_);
5957   return *currentAssociation_;
5958 }
5959 
5960 void ConstructVisitor::PushAssociation() {
5961   associationStack_.emplace_back(Association{});
5962   currentAssociation_ = &associationStack_.back();
5963 }
5964 
5965 void ConstructVisitor::PopAssociation(std::size_t count) {
5966   CHECK(count > 0 && count <= associationStack_.size());
5967   associationStack_.resize(associationStack_.size() - count);
5968   currentAssociation_ =
5969       associationStack_.empty() ? nullptr : &associationStack_.back();
5970 }
5971 
5972 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5973     evaluate::DynamicType &&type) {
5974   switch (type.category()) {
5975     SWITCH_COVERS_ALL_CASES
5976   case common::TypeCategory::Integer:
5977   case common::TypeCategory::Real:
5978   case common::TypeCategory::Complex:
5979     return context().MakeNumericType(type.category(), type.kind());
5980   case common::TypeCategory::Logical:
5981     return context().MakeLogicalType(type.kind());
5982   case common::TypeCategory::Derived:
5983     if (type.IsAssumedType()) {
5984       return currScope().MakeTypeStarType();
5985     } else if (type.IsUnlimitedPolymorphic()) {
5986       return currScope().MakeClassStarType();
5987     } else {
5988       return currScope().MakeDerivedType(
5989           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
5990                                : DeclTypeSpec::TypeDerived,
5991           common::Clone(type.GetDerivedTypeSpec())
5992 
5993       );
5994     }
5995   case common::TypeCategory::Character:
5996     CRASH_NO_CASE;
5997   }
5998 }
5999 
6000 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6001     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
6002   CHECK(type.category() == common::TypeCategory::Character);
6003   if (length) {
6004     return currScope().MakeCharacterType(
6005         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
6006         KindExpr{type.kind()});
6007   } else {
6008     return currScope().MakeCharacterType(
6009         ParamValue::Deferred(common::TypeParamAttr::Len),
6010         KindExpr{type.kind()});
6011   }
6012 }
6013 
6014 // ResolveNamesVisitor implementation
6015 
6016 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
6017   HandleCall(Symbol::Flag::Function, x.v);
6018   return false;
6019 }
6020 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
6021   HandleCall(Symbol::Flag::Subroutine, x.v);
6022   return false;
6023 }
6024 
6025 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
6026   auto &scope{currScope()};
6027   // Check C896 and C899: where IMPORT statements are allowed
6028   switch (scope.kind()) {
6029   case Scope::Kind::Module:
6030     if (scope.IsModule()) {
6031       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
6032       return false;
6033     } else if (x.kind == common::ImportKind::None) {
6034       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
6035       return false;
6036     }
6037     break;
6038   case Scope::Kind::MainProgram:
6039     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
6040     return false;
6041   case Scope::Kind::Subprogram:
6042     if (scope.parent().IsGlobal()) {
6043       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
6044       return false;
6045     }
6046     break;
6047   case Scope::Kind::BlockData: // C1415 (in part)
6048     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
6049     return false;
6050   default:;
6051   }
6052   if (auto error{scope.SetImportKind(x.kind)}) {
6053     Say(std::move(*error));
6054   }
6055   for (auto &name : x.names) {
6056     if (FindSymbol(scope.parent(), name)) {
6057       scope.add_importName(name.source);
6058     } else {
6059       Say(name, "'%s' not found in host scope"_err_en_US);
6060     }
6061   }
6062   prevImportStmt_ = currStmtSource();
6063   return false;
6064 }
6065 
6066 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6067     const parser::StructureComponent &x) {
6068   return FindComponent(ResolveDataRef(x.base), x.component);
6069 }
6070 
6071 const parser::Name *DeclarationVisitor::ResolveDesignator(
6072     const parser::Designator &x) {
6073   return std::visit(
6074       common::visitors{
6075           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6076           [&](const parser::Substring &x) {
6077             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6078           },
6079       },
6080       x.u);
6081 }
6082 
6083 const parser::Name *DeclarationVisitor::ResolveDataRef(
6084     const parser::DataRef &x) {
6085   return std::visit(
6086       common::visitors{
6087           [=](const parser::Name &y) { return ResolveName(y); },
6088           [=](const Indirection<parser::StructureComponent> &y) {
6089             return ResolveStructureComponent(y.value());
6090           },
6091           [&](const Indirection<parser::ArrayElement> &y) {
6092             Walk(y.value().subscripts);
6093             const parser::Name *name{ResolveDataRef(y.value().base)};
6094             if (name && name->symbol) {
6095               if (!IsProcedure(*name->symbol)) {
6096                 ConvertToObjectEntity(*name->symbol);
6097               } else if (!context().HasError(*name->symbol)) {
6098                 SayWithDecl(*name, *name->symbol,
6099                     "Cannot reference function '%s' as data"_err_en_US);
6100               }
6101             }
6102             return name;
6103           },
6104           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6105             Walk(y.value().imageSelector);
6106             return ResolveDataRef(y.value().base);
6107           },
6108       },
6109       x.u);
6110 }
6111 
6112 // If implicit types are allowed, ensure name is in the symbol table.
6113 // Otherwise, report an error if it hasn't been declared.
6114 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6115   FindSymbol(name);
6116   if (CheckForHostAssociatedImplicit(name)) {
6117     NotePossibleBadForwardRef(name);
6118     return &name;
6119   }
6120   if (Symbol * symbol{name.symbol}) {
6121     if (CheckUseError(name)) {
6122       return nullptr; // reported an error
6123     }
6124     NotePossibleBadForwardRef(name);
6125     symbol->set(Symbol::Flag::ImplicitOrError, false);
6126     if (IsUplevelReference(*symbol)) {
6127       MakeHostAssocSymbol(name, *symbol);
6128     } else if (IsDummy(*symbol) ||
6129         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6130       ConvertToObjectEntity(*symbol);
6131       ApplyImplicitRules(*symbol);
6132     }
6133     if (checkIndexUseInOwnBounds_ &&
6134         *checkIndexUseInOwnBounds_ == name.source) {
6135       Say(name,
6136           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_en_US,
6137           name.source);
6138     }
6139     return &name;
6140   }
6141   if (isImplicitNoneType()) {
6142     Say(name, "No explicit type declared for '%s'"_err_en_US);
6143     return nullptr;
6144   }
6145   // Create the symbol then ensure it is accessible
6146   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6147     Say(name,
6148         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6149         name.source);
6150   }
6151   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6152   auto *symbol{FindSymbol(name)};
6153   if (!symbol) {
6154     Say(name,
6155         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6156     return nullptr;
6157   }
6158   ConvertToObjectEntity(*symbol);
6159   ApplyImplicitRules(*symbol);
6160   NotePossibleBadForwardRef(name);
6161   return &name;
6162 }
6163 
6164 // A specification expression may refer to a symbol in the host procedure that
6165 // is implicitly typed. Because specification parts are processed before
6166 // execution parts, this may be the first time we see the symbol. It can't be a
6167 // local in the current scope (because it's in a specification expression) so
6168 // either it is implicitly declared in the host procedure or it is an error.
6169 // We create a symbol in the host assuming it is the former; if that proves to
6170 // be wrong we report an error later in CheckDeclarations().
6171 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6172     const parser::Name &name) {
6173   if (inExecutionPart_) {
6174     return false;
6175   }
6176   if (name.symbol) {
6177     ApplyImplicitRules(*name.symbol, true);
6178   }
6179   Symbol *hostSymbol;
6180   Scope *host{GetHostProcedure()};
6181   if (!host || isImplicitNoneType(*host)) {
6182     return false;
6183   }
6184   if (!name.symbol) {
6185     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6186     ConvertToObjectEntity(*hostSymbol);
6187     ApplyImplicitRules(*hostSymbol);
6188     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6189   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6190     hostSymbol = name.symbol;
6191   } else {
6192     return false;
6193   }
6194   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6195   if (isImplicitNoneType()) {
6196     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6197   } else {
6198     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6199   }
6200   return true;
6201 }
6202 
6203 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6204   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6205   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6206     return false;
6207   } else {
6208     Scope::Kind kind{symbolUnit.kind()};
6209     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6210   }
6211 }
6212 
6213 // base is a part-ref of a derived type; find the named component in its type.
6214 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6215 // COMPLEX component references (%re, %im).
6216 const parser::Name *DeclarationVisitor::FindComponent(
6217     const parser::Name *base, const parser::Name &component) {
6218   if (!base || !base->symbol) {
6219     return nullptr;
6220   }
6221   auto &symbol{base->symbol->GetUltimate()};
6222   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6223     SayWithDecl(*base, symbol,
6224         "'%s' is an invalid base for a component reference"_err_en_US);
6225     return nullptr;
6226   }
6227   auto *type{symbol.GetType()};
6228   if (!type) {
6229     return nullptr; // should have already reported error
6230   }
6231   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6232     auto name{component.ToString()};
6233     auto category{intrinsic->category()};
6234     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6235     if (name == "kind") {
6236       miscKind = MiscDetails::Kind::KindParamInquiry;
6237     } else if (category == TypeCategory::Character) {
6238       if (name == "len") {
6239         miscKind = MiscDetails::Kind::LenParamInquiry;
6240       }
6241     } else if (category == TypeCategory::Complex) {
6242       if (name == "re") {
6243         miscKind = MiscDetails::Kind::ComplexPartRe;
6244       } else if (name == "im") {
6245         miscKind = MiscDetails::Kind::ComplexPartIm;
6246       }
6247     }
6248     if (miscKind != MiscDetails::Kind::None) {
6249       MakePlaceholder(component, miscKind);
6250       return nullptr;
6251     }
6252   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6253     if (const Scope * scope{derived->scope()}) {
6254       if (Resolve(component, scope->FindComponent(component.source))) {
6255         if (auto msg{
6256                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6257           context().Say(component.source, *msg);
6258         }
6259         return &component;
6260       } else {
6261         SayDerivedType(component.source,
6262             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6263       }
6264     }
6265     return nullptr;
6266   }
6267   if (symbol.test(Symbol::Flag::Implicit)) {
6268     Say(*base,
6269         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6270   } else {
6271     SayWithDecl(
6272         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6273   }
6274   return nullptr;
6275 }
6276 
6277 void DeclarationVisitor::Initialization(const parser::Name &name,
6278     const parser::Initialization &init, bool inComponentDecl) {
6279   // Traversal of the initializer was deferred to here so that the
6280   // symbol being declared can be available for use in the expression, e.g.:
6281   //   real, parameter :: x = tiny(x)
6282   if (!name.symbol) {
6283     return;
6284   }
6285   Symbol &ultimate{name.symbol->GetUltimate()};
6286   if (IsAllocatable(ultimate)) {
6287     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6288     return;
6289   }
6290   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6291     // TODO: check C762 - all bounds and type parameters of component
6292     // are colons or constant expressions if component is initialized
6293     std::visit(
6294         common::visitors{
6295             [&](const parser::ConstantExpr &expr) {
6296               NonPointerInitialization(name, expr);
6297             },
6298             [&](const parser::NullInit &null) {
6299               Walk(null);
6300               if (auto nullInit{EvaluateExpr(null)}) {
6301                 if (!evaluate::IsNullPointer(*nullInit)) {
6302                   Say(name,
6303                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6304                 } else if (IsPointer(ultimate)) {
6305                   object->set_init(std::move(*nullInit));
6306                 } else {
6307                   Say(name,
6308                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6309                 }
6310               }
6311             },
6312             [&](const parser::InitialDataTarget &) {
6313               // Defer analysis to the end of the specification part
6314               // so that forward references and attribute checks like SAVE
6315               // work better.
6316               ultimate.set(Symbol::Flag::InDataStmt);
6317             },
6318             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
6319               // Handled later in data-to-inits conversion
6320               ultimate.set(Symbol::Flag::InDataStmt);
6321             },
6322         },
6323         init.u);
6324   }
6325 }
6326 
6327 void DeclarationVisitor::PointerInitialization(
6328     const parser::Name &name, const parser::InitialDataTarget &target) {
6329   if (name.symbol) {
6330     Symbol &ultimate{name.symbol->GetUltimate()};
6331     if (!context().HasError(ultimate)) {
6332       if (IsPointer(ultimate)) {
6333         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6334           CHECK(!details->init());
6335           Walk(target);
6336           if (MaybeExpr expr{EvaluateExpr(target)}) {
6337             // Validation is done in declaration checking.
6338             details->set_init(std::move(*expr));
6339           }
6340         }
6341       } else {
6342         Say(name,
6343             "'%s' is not a pointer but is initialized like one"_err_en_US);
6344         context().SetError(ultimate);
6345       }
6346     }
6347   }
6348 }
6349 void DeclarationVisitor::PointerInitialization(
6350     const parser::Name &name, const parser::ProcPointerInit &target) {
6351   if (name.symbol) {
6352     Symbol &ultimate{name.symbol->GetUltimate()};
6353     if (!context().HasError(ultimate)) {
6354       if (IsProcedurePointer(ultimate)) {
6355         auto &details{ultimate.get<ProcEntityDetails>()};
6356         CHECK(!details.init());
6357         Walk(target);
6358         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6359           if (targetName->symbol) {
6360             // Validation is done in declaration checking.
6361             details.set_init(*targetName->symbol);
6362           }
6363         } else {
6364           details.set_init(nullptr); // explicit NULL()
6365         }
6366       } else {
6367         Say(name,
6368             "'%s' is not a procedure pointer but is initialized "
6369             "like one"_err_en_US);
6370         context().SetError(ultimate);
6371       }
6372     }
6373   }
6374 }
6375 
6376 void DeclarationVisitor::NonPointerInitialization(
6377     const parser::Name &name, const parser::ConstantExpr &expr) {
6378   if (name.symbol) {
6379     Symbol &ultimate{name.symbol->GetUltimate()};
6380     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6381       if (IsPointer(ultimate)) {
6382         Say(name,
6383             "'%s' is a pointer but is not initialized like one"_err_en_US);
6384       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6385         CHECK(!details->init());
6386         Walk(expr);
6387         if (ultimate.owner().IsParameterizedDerivedType()) {
6388           // Can't convert to type of component, which might not yet
6389           // be known; that's done later during PDT instantiation.
6390           if (MaybeExpr value{EvaluateExpr(expr)}) {
6391             details->set_init(std::move(*value));
6392           }
6393         } else if (MaybeExpr folded{EvaluateNonPointerInitializer(
6394                        ultimate, expr, expr.thing.value().source)}) {
6395           details->set_init(std::move(*folded));
6396         }
6397       }
6398     }
6399   }
6400 }
6401 
6402 void ResolveNamesVisitor::HandleCall(
6403     Symbol::Flag procFlag, const parser::Call &call) {
6404   std::visit(
6405       common::visitors{
6406           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6407           [&](const parser::ProcComponentRef &x) { Walk(x); },
6408       },
6409       std::get<parser::ProcedureDesignator>(call.t).u);
6410   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6411 }
6412 
6413 void ResolveNamesVisitor::HandleProcedureName(
6414     Symbol::Flag flag, const parser::Name &name) {
6415   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6416   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6417   if (!symbol) {
6418     if (IsIntrinsic(name.source, flag)) {
6419       symbol =
6420           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6421     } else {
6422       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6423     }
6424     Resolve(name, *symbol);
6425     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6426       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6427         MakeExternal(*symbol);
6428       }
6429     }
6430     ConvertToProcEntity(*symbol);
6431     SetProcFlag(name, *symbol, flag);
6432   } else if (CheckUseError(name)) {
6433     // error was reported
6434   } else {
6435     auto &nonUltimateSymbol = *symbol;
6436     symbol = &Resolve(name, symbol)->GetUltimate();
6437     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6438     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6439         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6440       AcquireIntrinsicProcedureFlags(*symbol);
6441     }
6442     if (!SetProcFlag(name, *symbol, flag)) {
6443       return; // reported error
6444     }
6445     CheckImplicitNoneExternal(name.source, *symbol);
6446     if (symbol->has<SubprogramDetails>() &&
6447         symbol->attrs().test(Attr::ABSTRACT)) {
6448       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6449     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6450         symbol->has<AssocEntityDetails>()) {
6451       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6452       // here as procedure-designators because this means the related
6453       // FunctionReference are mis-parsed structure constructors or array
6454       // references that will be fixed later when analyzing expressions.
6455     } else if (symbol->has<ObjectEntityDetails>()) {
6456       // Symbols with ObjectEntityDetails are also accepted because this can be
6457       // a mis-parsed array references that will be fixed later. Ensure that if
6458       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6459       // is created for the current scope.
6460       // Operate on non ultimate symbol so that HostAssocDetails are also
6461       // created for symbols used associated in the host procedure.
6462       if (IsUplevelReference(nonUltimateSymbol)) {
6463         MakeHostAssocSymbol(name, nonUltimateSymbol);
6464       }
6465     } else if (symbol->test(Symbol::Flag::Implicit)) {
6466       Say(name,
6467           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6468     } else {
6469       SayWithDecl(name, *symbol,
6470           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6471     }
6472   }
6473 }
6474 
6475 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6476     const SourceName &name, const Symbol &symbol) {
6477   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6478       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6479     Say(name,
6480         "'%s' is an external procedure without the EXTERNAL"
6481         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6482     return false;
6483   }
6484   return true;
6485 }
6486 
6487 // Variant of HandleProcedureName() for use while skimming the executable
6488 // part of a subprogram to catch calls to dummy procedures that are part
6489 // of the subprogram's interface, and to mark as procedures any symbols
6490 // that might otherwise have been miscategorized as objects.
6491 void ResolveNamesVisitor::NoteExecutablePartCall(
6492     Symbol::Flag flag, const parser::Call &call) {
6493   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6494   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6495     // Subtlety: The symbol pointers in the parse tree are not set, because
6496     // they might end up resolving elsewhere (e.g., construct entities in
6497     // SELECT TYPE).
6498     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6499       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6500               ? Symbol::Flag::Function
6501               : Symbol::Flag::Subroutine};
6502       if (!symbol->test(other)) {
6503         ConvertToProcEntity(*symbol);
6504         if (symbol->has<ProcEntityDetails>()) {
6505           symbol->set(flag);
6506           if (IsDummy(*symbol)) {
6507             symbol->attrs().set(Attr::EXTERNAL);
6508           }
6509           ApplyImplicitRules(*symbol);
6510         }
6511       }
6512     }
6513   }
6514 }
6515 
6516 static bool IsLocallyImplicitGlobalSymbol(
6517     const Symbol &symbol, const parser::Name &localName) {
6518   return symbol.owner().IsGlobal() &&
6519       (!symbol.scope() ||
6520           !symbol.scope()->sourceRange().Contains(localName.source));
6521 }
6522 
6523 static bool TypesMismatchIfNonNull(
6524     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
6525   return type1 && type2 && *type1 != *type2;
6526 }
6527 
6528 // Check and set the Function or Subroutine flag on symbol; false on error.
6529 bool ResolveNamesVisitor::SetProcFlag(
6530     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6531   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6532     SayWithDecl(
6533         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6534     return false;
6535   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6536       flag == Symbol::Flag::Function) {
6537     SayWithDecl(
6538         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6539     return false;
6540   } else if (flag == Symbol::Flag::Function &&
6541       IsLocallyImplicitGlobalSymbol(symbol, name) &&
6542       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
6543     SayWithDecl(name, symbol,
6544         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
6545     return false;
6546   } else if (symbol.has<ProcEntityDetails>()) {
6547     symbol.set(flag); // in case it hasn't been set yet
6548     if (flag == Symbol::Flag::Function) {
6549       ApplyImplicitRules(symbol);
6550     }
6551     if (symbol.attrs().test(Attr::INTRINSIC)) {
6552       AcquireIntrinsicProcedureFlags(symbol);
6553     }
6554   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6555     SayWithDecl(
6556         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6557   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6558     AcquireIntrinsicProcedureFlags(symbol);
6559   }
6560   return true;
6561 }
6562 
6563 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6564   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6565   if (!currScope().IsModule()) { // C869
6566     Say(currStmtSource().value(),
6567         "%s statement may only appear in the specification part of a module"_err_en_US,
6568         EnumToString(accessAttr));
6569     return false;
6570   }
6571   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6572   if (accessIds.empty()) {
6573     if (prevAccessStmt_) { // C869
6574       Say("The default accessibility of this module has already been declared"_err_en_US)
6575           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6576     }
6577     prevAccessStmt_ = currStmtSource();
6578     defaultAccess_ = accessAttr;
6579   } else {
6580     for (const auto &accessId : accessIds) {
6581       std::visit(
6582           common::visitors{
6583               [=](const parser::Name &y) {
6584                 Resolve(y, SetAccess(y.source, accessAttr));
6585               },
6586               [=](const Indirection<parser::GenericSpec> &y) {
6587                 auto info{GenericSpecInfo{y.value()}};
6588                 const auto &symbolName{info.symbolName()};
6589                 if (auto *symbol{FindInScope(symbolName)}) {
6590                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6591                 } else if (info.kind().IsName()) {
6592                   info.Resolve(&SetAccess(symbolName, accessAttr));
6593                 } else {
6594                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6595                 }
6596               },
6597           },
6598           accessId.u);
6599     }
6600   }
6601   return false;
6602 }
6603 
6604 // Set the access specification for this symbol.
6605 Symbol &ModuleVisitor::SetAccess(
6606     const SourceName &name, Attr attr, Symbol *symbol) {
6607   if (!symbol) {
6608     symbol = &MakeSymbol(name);
6609   }
6610   Attrs &attrs{symbol->attrs()};
6611   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6612     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6613     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6614     Say(name,
6615         WithIsFatal(
6616             "The accessibility of '%s' has already been specified as %s"_en_US,
6617             attr != prev),
6618         MakeOpName(name), EnumToString(prev));
6619   } else {
6620     attrs.set(attr);
6621   }
6622   return *symbol;
6623 }
6624 
6625 static bool NeedsExplicitType(const Symbol &symbol) {
6626   if (symbol.has<UnknownDetails>()) {
6627     return true;
6628   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6629     return !details->type();
6630   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6631     return !details->type();
6632   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6633     return !details->interface().symbol() && !details->interface().type();
6634   } else {
6635     return false;
6636   }
6637 }
6638 
6639 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6640   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
6641       implicitPart, decls] = x.t;
6642   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
6643   auto stateRestorer{
6644       common::ScopedSet(specPartState_, SpecificationPartState{})};
6645   Walk(accDecls);
6646   Walk(ompDecls);
6647   Walk(compilerDirectives);
6648   Walk(useStmts);
6649   ClearUseRenames();
6650   ClearUseOnly();
6651   ClearExplicitIntrinsicUses();
6652   Walk(importStmts);
6653   Walk(implicitPart);
6654   for (const auto &decl : decls) {
6655     if (const auto *spec{
6656             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6657       PreSpecificationConstruct(*spec);
6658     }
6659   }
6660   Walk(decls);
6661   FinishSpecificationPart(decls);
6662   return false;
6663 }
6664 
6665 // Initial processing on specification constructs, before visiting them.
6666 void ResolveNamesVisitor::PreSpecificationConstruct(
6667     const parser::SpecificationConstruct &spec) {
6668   std::visit(
6669       common::visitors{
6670           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6671             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6672           },
6673           [&](const Indirection<parser::InterfaceBlock> &y) {
6674             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6675                 y.value().t)};
6676             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
6677               CreateGeneric(*spec);
6678             }
6679           },
6680           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
6681             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
6682               CreateCommonBlockSymbols(*commonStmt);
6683             }
6684           },
6685           [&](const auto &) {},
6686       },
6687       spec.u);
6688 }
6689 
6690 void ResolveNamesVisitor::CreateCommonBlockSymbols(
6691     const parser::CommonStmt &commonStmt) {
6692   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
6693     const auto &[name, objects] = block.t;
6694     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
6695     for (const auto &object : objects) {
6696       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
6697       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
6698         details->set_commonBlock(commonBlock);
6699         commonBlock.get<CommonBlockDetails>().add_object(obj);
6700       }
6701     }
6702   }
6703 }
6704 
6705 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6706   auto info{GenericSpecInfo{x}};
6707   const SourceName &symbolName{info.symbolName()};
6708   if (IsLogicalConstant(context(), symbolName)) {
6709     Say(symbolName,
6710         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6711     return;
6712   }
6713   GenericDetails genericDetails;
6714   if (Symbol * existing{FindInScope(symbolName)}) {
6715     if (existing->has<GenericDetails>()) {
6716       info.Resolve(existing);
6717       return; // already have generic, add to it
6718     }
6719     Symbol &ultimate{existing->GetUltimate()};
6720     if (auto *ultimateDetails{ultimate.detailsIf<GenericDetails>()}) {
6721       // convert a use-associated generic into a local generic
6722       genericDetails.CopyFrom(*ultimateDetails);
6723       AddGenericUse(genericDetails, existing->name(),
6724           existing->get<UseDetails>().symbol());
6725     } else if (ultimate.has<SubprogramDetails>() ||
6726         ultimate.has<SubprogramNameDetails>()) {
6727       genericDetails.set_specific(ultimate);
6728     } else if (ultimate.has<DerivedTypeDetails>()) {
6729       genericDetails.set_derivedType(ultimate);
6730     } else {
6731       SayAlreadyDeclared(symbolName, *existing);
6732     }
6733     EraseSymbol(*existing);
6734   }
6735   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
6736 }
6737 
6738 void ResolveNamesVisitor::FinishSpecificationPart(
6739     const std::list<parser::DeclarationConstruct> &decls) {
6740   badStmtFuncFound_ = false;
6741   FinishFunctionResult();
6742   CheckImports();
6743   bool inModule{currScope().kind() == Scope::Kind::Module};
6744   for (auto &pair : currScope()) {
6745     auto &symbol{*pair.second};
6746     if (NeedsExplicitType(symbol)) {
6747       ApplyImplicitRules(symbol);
6748     }
6749     if (IsDummy(symbol) && isImplicitNoneType() &&
6750         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
6751       Say(symbol.name(),
6752           "No explicit type declared for dummy argument '%s'"_err_en_US);
6753       context().SetError(symbol);
6754     }
6755     if (symbol.has<GenericDetails>()) {
6756       CheckGenericProcedures(symbol);
6757     }
6758     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
6759         !symbol.test(Symbol::Flag::Function) &&
6760         !symbol.test(Symbol::Flag::Subroutine)) {
6761       // in a module, external proc without return type is subroutine
6762       symbol.set(
6763           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
6764     }
6765     if (!symbol.has<HostAssocDetails>()) {
6766       CheckPossibleBadForwardRef(symbol);
6767     }
6768   }
6769   currScope().InstantiateDerivedTypes();
6770   for (const auto &decl : decls) {
6771     if (const auto *statement{std::get_if<
6772             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
6773             &decl.u)}) {
6774       AnalyzeStmtFunctionStmt(statement->statement.value());
6775     }
6776   }
6777   // TODO: what about instantiations in BLOCK?
6778   CheckSaveStmts();
6779   CheckCommonBlocks();
6780   if (!inInterfaceBlock()) {
6781     // TODO: warn for the case where the EQUIVALENCE statement is in a
6782     // procedure declaration in an interface block
6783     CheckEquivalenceSets();
6784   }
6785 }
6786 
6787 // Analyze the bodies of statement functions now that the symbols in this
6788 // specification part have been fully declared and implicitly typed.
6789 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
6790     const parser::StmtFunctionStmt &stmtFunc) {
6791   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
6792   if (!symbol || !symbol->has<SubprogramDetails>()) {
6793     return;
6794   }
6795   auto &details{symbol->get<SubprogramDetails>()};
6796   auto expr{AnalyzeExpr(
6797       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
6798   if (!expr) {
6799     context().SetError(*symbol);
6800     return;
6801   }
6802   if (auto type{evaluate::DynamicType::From(*symbol)}) {
6803     auto converted{ConvertToType(*type, std::move(*expr))};
6804     if (!converted) {
6805       context().SetError(*symbol);
6806       return;
6807     }
6808     details.set_stmtFunction(std::move(*converted));
6809   } else {
6810     details.set_stmtFunction(std::move(*expr));
6811   }
6812 }
6813 
6814 void ResolveNamesVisitor::CheckImports() {
6815   auto &scope{currScope()};
6816   switch (scope.GetImportKind()) {
6817   case common::ImportKind::None:
6818     break;
6819   case common::ImportKind::All:
6820     // C8102: all entities in host must not be hidden
6821     for (const auto &pair : scope.parent()) {
6822       auto &name{pair.first};
6823       std::optional<SourceName> scopeName{scope.GetName()};
6824       if (!scopeName || name != *scopeName) {
6825         CheckImport(prevImportStmt_.value(), name);
6826       }
6827     }
6828     break;
6829   case common::ImportKind::Default:
6830   case common::ImportKind::Only:
6831     // C8102: entities named in IMPORT must not be hidden
6832     for (auto &name : scope.importNames()) {
6833       CheckImport(name, name);
6834     }
6835     break;
6836   }
6837 }
6838 
6839 void ResolveNamesVisitor::CheckImport(
6840     const SourceName &location, const SourceName &name) {
6841   if (auto *symbol{FindInScope(name)}) {
6842     const Symbol &ultimate{symbol->GetUltimate()};
6843     if (&ultimate.owner() == &currScope()) {
6844       Say(location, "'%s' from host is not accessible"_err_en_US, name)
6845           .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
6846               symbol->name());
6847     }
6848   }
6849 }
6850 
6851 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
6852   return CheckNotInBlock("IMPLICIT") && // C1107
6853       ImplicitRulesVisitor::Pre(x);
6854 }
6855 
6856 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
6857   std::visit(common::visitors{
6858                  [&](const parser::Name &x) { ResolveName(x); },
6859                  [&](const parser::StructureComponent &x) {
6860                    ResolveStructureComponent(x);
6861                  },
6862              },
6863       x.u);
6864 }
6865 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
6866   std::visit(common::visitors{
6867                  [&](const parser::Name &x) { ResolveName(x); },
6868                  [&](const parser::StructureComponent &x) {
6869                    ResolveStructureComponent(x);
6870                  },
6871              },
6872       x.u);
6873 }
6874 
6875 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
6876   const auto &dataRef{std::get<parser::DataRef>(x.t)};
6877   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
6878   const auto &expr{std::get<parser::Expr>(x.t)};
6879   ResolveDataRef(dataRef);
6880   Walk(bounds);
6881   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
6882   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
6883     if (NameIsKnownOrIntrinsic(*name)) {
6884       // If the name is known because it is an object entity from a host
6885       // procedure, create a host associated symbol.
6886       if (Symbol * symbol{name->symbol}; symbol &&
6887           symbol->GetUltimate().has<ObjectEntityDetails>() &&
6888           IsUplevelReference(*symbol)) {
6889         MakeHostAssocSymbol(*name, *symbol);
6890       }
6891       return false;
6892     }
6893   }
6894   Walk(expr);
6895   return false;
6896 }
6897 void ResolveNamesVisitor::Post(const parser::Designator &x) {
6898   ResolveDesignator(x);
6899 }
6900 
6901 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
6902   ResolveStructureComponent(x.v.thing);
6903 }
6904 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
6905   DeclTypeSpecVisitor::Post(x);
6906   ConstructVisitor::Post(x);
6907 }
6908 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
6909   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
6910   if (HandleStmtFunction(x)) {
6911     return false;
6912   } else {
6913     // This is an array element assignment: resolve names of indices
6914     const auto &names{std::get<std::list<parser::Name>>(x.t)};
6915     for (auto &name : names) {
6916       ResolveName(name);
6917     }
6918     return true;
6919   }
6920 }
6921 
6922 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
6923   const parser::Name &name{x.v};
6924   if (FindSymbol(name)) {
6925     // OK
6926   } else if (IsLogicalConstant(context(), name.source)) {
6927     Say(name,
6928         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6929   } else {
6930     // Resolved later in expression semantics
6931     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
6932   }
6933   return false;
6934 }
6935 
6936 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
6937   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6938     ConvertToObjectEntity(DEREF(name->symbol));
6939   }
6940 }
6941 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
6942   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6943     ConvertToObjectEntity(DEREF(name->symbol));
6944   }
6945 }
6946 
6947 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
6948   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
6949           x.u)) {
6950     // TODO: global directives
6951     return true;
6952   }
6953   auto root{ProgramTree::Build(x)};
6954   SetScope(topScope_);
6955   ResolveSpecificationParts(root);
6956   FinishSpecificationParts(root);
6957   inExecutionPart_ = true;
6958   ResolveExecutionParts(root);
6959   inExecutionPart_ = false;
6960   ResolveAccParts(context(), x);
6961   ResolveOmpParts(context(), x);
6962   return false;
6963 }
6964 
6965 // References to procedures need to record that their symbols are known
6966 // to be procedures, so that they don't get converted to objects by default.
6967 class ExecutionPartSkimmer {
6968 public:
6969   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
6970       : resolver_{resolver} {}
6971 
6972   void Walk(const parser::ExecutionPart *exec) {
6973     if (exec) {
6974       parser::Walk(*exec, *this);
6975     }
6976   }
6977 
6978   template <typename A> bool Pre(const A &) { return true; }
6979   template <typename A> void Post(const A &) {}
6980   void Post(const parser::FunctionReference &fr) {
6981     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
6982   }
6983   void Post(const parser::CallStmt &cs) {
6984     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
6985   }
6986 
6987 private:
6988   ResolveNamesVisitor &resolver_;
6989 };
6990 
6991 // Build the scope tree and resolve names in the specification parts of this
6992 // node and its children
6993 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
6994   if (node.isSpecificationPartResolved()) {
6995     return; // been here already
6996   }
6997   node.set_isSpecificationPartResolved();
6998   if (!BeginScopeForNode(node)) {
6999     return; // an error prevented scope from being created
7000   }
7001   Scope &scope{currScope()};
7002   node.set_scope(scope);
7003   AddSubpNames(node);
7004   std::visit(
7005       [&](const auto *x) {
7006         if (x) {
7007           Walk(*x);
7008         }
7009       },
7010       node.stmt());
7011   Walk(node.spec());
7012   // If this is a function, convert result to an object. This is to prevent the
7013   // result from being converted later to a function symbol if it is called
7014   // inside the function.
7015   // If the result is function pointer, then ConvertToObjectEntity will not
7016   // convert the result to an object, and calling the symbol inside the function
7017   // will result in calls to the result pointer.
7018   // A function cannot be called recursively if RESULT was not used to define a
7019   // distinct result name (15.6.2.2 point 4.).
7020   if (Symbol * symbol{scope.symbol()}) {
7021     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
7022       if (details->isFunction()) {
7023         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
7024       }
7025     }
7026   }
7027   if (node.IsModule()) {
7028     ApplyDefaultAccess();
7029   }
7030   for (auto &child : node.children()) {
7031     ResolveSpecificationParts(child);
7032   }
7033   ExecutionPartSkimmer{*this}.Walk(node.exec());
7034   EndScopeForNode(node);
7035   // Ensure that every object entity has a type.
7036   for (auto &pair : *node.scope()) {
7037     ApplyImplicitRules(*pair.second);
7038   }
7039 }
7040 
7041 // Add SubprogramNameDetails symbols for module and internal subprograms and
7042 // their ENTRY statements.
7043 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
7044   auto kind{
7045       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
7046   for (auto &child : node.children()) {
7047     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
7048     symbol.set(child.GetSubpFlag());
7049     for (const auto &entryStmt : child.entryStmts()) {
7050       SubprogramNameDetails details{kind, child};
7051       details.set_isEntryStmt();
7052       auto &symbol{
7053           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
7054       symbol.set(child.GetSubpFlag());
7055     }
7056   }
7057   for (const auto &generic : node.genericSpecs()) {
7058     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
7059       if (currScope().find(name->source) != currScope().end()) {
7060         // If this scope has both a generic interface and a contained
7061         // subprogram with the same name, create the generic's symbol
7062         // now so that any other generics of the same name that are pulled
7063         // into scope later via USE association will properly merge instead
7064         // of raising a bogus error due a conflict with the subprogram.
7065         CreateGeneric(*generic);
7066       }
7067     }
7068   }
7069 }
7070 
7071 // Push a new scope for this node or return false on error.
7072 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
7073   switch (node.GetKind()) {
7074     SWITCH_COVERS_ALL_CASES
7075   case ProgramTree::Kind::Program:
7076     PushScope(Scope::Kind::MainProgram,
7077         &MakeSymbol(node.name(), MainProgramDetails{}));
7078     return true;
7079   case ProgramTree::Kind::Function:
7080   case ProgramTree::Kind::Subroutine:
7081     return BeginSubprogram(
7082         node.name(), node.GetSubpFlag(), node.HasModulePrefix());
7083   case ProgramTree::Kind::MpSubprogram:
7084     return BeginMpSubprogram(node.name());
7085   case ProgramTree::Kind::Module:
7086     BeginModule(node.name(), false);
7087     return true;
7088   case ProgramTree::Kind::Submodule:
7089     return BeginSubmodule(node.name(), node.GetParentId());
7090   case ProgramTree::Kind::BlockData:
7091     PushBlockDataScope(node.name());
7092     return true;
7093   }
7094 }
7095 
7096 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
7097   EndSubprogram();
7098 }
7099 
7100 // Some analyses and checks, such as the processing of initializers of
7101 // pointers, are deferred until all of the pertinent specification parts
7102 // have been visited.  This deferred processing enables the use of forward
7103 // references in these circumstances.
7104 class DeferredCheckVisitor {
7105 public:
7106   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7107       : resolver_{resolver} {}
7108 
7109   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7110 
7111   template <typename A> bool Pre(const A &) { return true; }
7112   template <typename A> void Post(const A &) {}
7113 
7114   void Post(const parser::DerivedTypeStmt &x) {
7115     const auto &name{std::get<parser::Name>(x.t)};
7116     if (Symbol * symbol{name.symbol}) {
7117       if (Scope * scope{symbol->scope()}) {
7118         if (scope->IsDerivedType()) {
7119           resolver_.PushScope(*scope);
7120           pushedScope_ = true;
7121         }
7122       }
7123     }
7124   }
7125   void Post(const parser::EndTypeStmt &) {
7126     if (pushedScope_) {
7127       resolver_.PopScope();
7128       pushedScope_ = false;
7129     }
7130   }
7131 
7132   void Post(const parser::ProcInterface &pi) {
7133     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7134       resolver_.CheckExplicitInterface(*name);
7135     }
7136   }
7137   bool Pre(const parser::EntityDecl &decl) {
7138     Init(std::get<parser::Name>(decl.t),
7139         std::get<std::optional<parser::Initialization>>(decl.t));
7140     return false;
7141   }
7142   bool Pre(const parser::ComponentDecl &decl) {
7143     Init(std::get<parser::Name>(decl.t),
7144         std::get<std::optional<parser::Initialization>>(decl.t));
7145     return false;
7146   }
7147   bool Pre(const parser::ProcDecl &decl) {
7148     if (const auto &init{
7149             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7150       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7151     }
7152     return false;
7153   }
7154   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7155     resolver_.CheckExplicitInterface(tbps.interfaceName);
7156   }
7157   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7158     if (pushedScope_) {
7159       resolver_.CheckBindings(tbps);
7160     }
7161   }
7162 
7163 private:
7164   void Init(const parser::Name &name,
7165       const std::optional<parser::Initialization> &init) {
7166     if (init) {
7167       if (const auto *target{
7168               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7169         resolver_.PointerInitialization(name, *target);
7170       }
7171     }
7172   }
7173 
7174   ResolveNamesVisitor &resolver_;
7175   bool pushedScope_{false};
7176 };
7177 
7178 // Perform checks and completions that need to happen after all of
7179 // the specification parts but before any of the execution parts.
7180 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7181   if (!node.scope()) {
7182     return; // error occurred creating scope
7183   }
7184   SetScope(*node.scope());
7185   // The initializers of pointers, the default initializers of pointer
7186   // components, and non-deferred type-bound procedure bindings have not
7187   // yet been traversed.
7188   // We do that now, when any (formerly) forward references that appear
7189   // in those initializers will resolve to the right symbols without
7190   // incurring spurious errors with IMPLICIT NONE.
7191   DeferredCheckVisitor{*this}.Walk(node.spec());
7192   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7193   for (Scope &childScope : currScope().children()) {
7194     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7195       FinishDerivedTypeInstantiation(childScope);
7196     }
7197   }
7198   for (const auto &child : node.children()) {
7199     FinishSpecificationParts(child);
7200   }
7201 }
7202 
7203 // Duplicate and fold component object pointer default initializer designators
7204 // using the actual type parameter values of each particular instantiation.
7205 // Validation is done later in declaration checking.
7206 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7207   CHECK(scope.IsDerivedType() && !scope.symbol());
7208   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7209     spec->Instantiate(currScope());
7210     const Symbol &origTypeSymbol{spec->typeSymbol()};
7211     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7212       CHECK(origTypeScope->IsDerivedType() &&
7213           origTypeScope->symbol() == &origTypeSymbol);
7214       auto &foldingContext{GetFoldingContext()};
7215       auto restorer{foldingContext.WithPDTInstance(*spec)};
7216       for (auto &pair : scope) {
7217         Symbol &comp{*pair.second};
7218         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7219         if (IsPointer(comp)) {
7220           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7221             auto origDetails{origComp.get<ObjectEntityDetails>()};
7222             if (const MaybeExpr & init{origDetails.init()}) {
7223               SomeExpr newInit{*init};
7224               MaybeExpr folded{
7225                   evaluate::Fold(foldingContext, std::move(newInit))};
7226               details->set_init(std::move(folded));
7227             }
7228           }
7229         }
7230       }
7231     }
7232   }
7233 }
7234 
7235 // Resolve names in the execution part of this node and its children
7236 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7237   if (!node.scope()) {
7238     return; // error occurred creating scope
7239   }
7240   SetScope(*node.scope());
7241   if (const auto *exec{node.exec()}) {
7242     Walk(*exec);
7243   }
7244   PopScope(); // converts unclassified entities into objects
7245   for (const auto &child : node.children()) {
7246     ResolveExecutionParts(child);
7247   }
7248 }
7249 
7250 void ResolveNamesVisitor::Post(const parser::Program &) {
7251   // ensure that all temps were deallocated
7252   CHECK(!attrs_);
7253   CHECK(!GetDeclTypeSpec());
7254 }
7255 
7256 // A singleton instance of the scope -> IMPLICIT rules mapping is
7257 // shared by all instances of ResolveNamesVisitor and accessed by this
7258 // pointer when the visitors (other than the top-level original) are
7259 // constructed.
7260 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7261 
7262 bool ResolveNames(
7263     SemanticsContext &context, const parser::Program &program, Scope &top) {
7264   ImplicitRulesMap implicitRulesMap;
7265   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7266   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7267   return !context.AnyFatalError();
7268 }
7269 
7270 // Processes a module (but not internal) function when it is referenced
7271 // in a specification expression in a sibling procedure.
7272 void ResolveSpecificationParts(
7273     SemanticsContext &context, const Symbol &subprogram) {
7274   auto originalLocation{context.location()};
7275   ResolveNamesVisitor visitor{
7276       context, DEREF(sharedImplicitRulesMap), context.globalScope()};
7277   const auto &details{subprogram.get<SubprogramNameDetails>()};
7278   ProgramTree &node{details.node()};
7279   const Scope &moduleScope{subprogram.owner()};
7280   visitor.SetScope(const_cast<Scope &>(moduleScope));
7281   visitor.ResolveSpecificationParts(node);
7282   context.set_location(std::move(originalLocation));
7283 }
7284 
7285 } // namespace Fortran::semantics
7286