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/Common/visit.h"
21 #include "flang/Evaluate/characteristics.h"
22 #include "flang/Evaluate/check-expression.h"
23 #include "flang/Evaluate/common.h"
24 #include "flang/Evaluate/fold-designator.h"
25 #include "flang/Evaluate/fold.h"
26 #include "flang/Evaluate/intrinsics.h"
27 #include "flang/Evaluate/tools.h"
28 #include "flang/Evaluate/type.h"
29 #include "flang/Parser/parse-tree-visitor.h"
30 #include "flang/Parser/parse-tree.h"
31 #include "flang/Parser/tools.h"
32 #include "flang/Semantics/attr.h"
33 #include "flang/Semantics/expression.h"
34 #include "flang/Semantics/scope.h"
35 #include "flang/Semantics/semantics.h"
36 #include "flang/Semantics/symbol.h"
37 #include "flang/Semantics/tools.h"
38 #include "flang/Semantics/type.h"
39 #include "llvm/Support/raw_ostream.h"
40 #include <list>
41 #include <map>
42 #include <set>
43 #include <stack>
44 
45 namespace Fortran::semantics {
46 
47 using namespace parser::literals;
48 
49 template <typename T> using Indirection = common::Indirection<T>;
50 using Message = parser::Message;
51 using Messages = parser::Messages;
52 using MessageFixedText = parser::MessageFixedText;
53 using MessageFormattedText = parser::MessageFormattedText;
54 
55 class ResolveNamesVisitor;
56 class ScopeHandler;
57 
58 // ImplicitRules maps initial character of identifier to the DeclTypeSpec
59 // representing the implicit type; std::nullopt if none.
60 // It also records the presence of IMPLICIT NONE statements.
61 // When inheritFromParent is set, defaults come from the parent rules.
62 class ImplicitRules {
63 public:
64   ImplicitRules(SemanticsContext &context, ImplicitRules *parent)
65       : parent_{parent}, context_{context} {
66     inheritFromParent_ = parent != nullptr;
67   }
68   bool isImplicitNoneType() const;
69   bool isImplicitNoneExternal() const;
70   void set_isImplicitNoneType(bool x) { isImplicitNoneType_ = x; }
71   void set_isImplicitNoneExternal(bool x) { isImplicitNoneExternal_ = x; }
72   void set_inheritFromParent(bool x) { inheritFromParent_ = x; }
73   // Get the implicit type for this name. May be null.
74   const DeclTypeSpec *GetType(
75       SourceName, bool respectImplicitNone = true) const;
76   // Record the implicit type for the range of characters [fromLetter,
77   // toLetter].
78   void SetTypeMapping(const DeclTypeSpec &type, parser::Location fromLetter,
79       parser::Location toLetter);
80 
81 private:
82   static char Incr(char ch);
83 
84   ImplicitRules *parent_;
85   SemanticsContext &context_;
86   bool inheritFromParent_{false}; // look in parent if not specified here
87   bool isImplicitNoneType_{
88       context_.IsEnabled(common::LanguageFeature::ImplicitNoneTypeAlways)};
89   bool isImplicitNoneExternal_{false};
90   // map_ contains the mapping between letters and types that were defined
91   // by the IMPLICIT statements of the related scope. It does not contain
92   // the default Fortran mappings nor the mapping defined in parents.
93   std::map<char, common::Reference<const DeclTypeSpec>> map_;
94 
95   friend llvm::raw_ostream &operator<<(
96       llvm::raw_ostream &, const ImplicitRules &);
97   friend void ShowImplicitRule(
98       llvm::raw_ostream &, const ImplicitRules &, char);
99 };
100 
101 // scope -> implicit rules for that scope
102 using ImplicitRulesMap = std::map<const Scope *, ImplicitRules>;
103 
104 // Track statement source locations and save messages.
105 class MessageHandler {
106 public:
107   MessageHandler() { DIE("MessageHandler: default-constructed"); }
108   explicit MessageHandler(SemanticsContext &c) : context_{&c} {}
109   Messages &messages() { return context_->messages(); };
110   const std::optional<SourceName> &currStmtSource() {
111     return context_->location();
112   }
113   void set_currStmtSource(const std::optional<SourceName> &source) {
114     context_->set_location(source);
115   }
116 
117   // Emit a message associated with the current statement source.
118   Message &Say(MessageFixedText &&);
119   Message &Say(MessageFormattedText &&);
120   // Emit a message about a SourceName
121   Message &Say(const SourceName &, MessageFixedText &&);
122   // Emit a formatted message associated with a source location.
123   template <typename... A>
124   Message &Say(const SourceName &source, MessageFixedText &&msg, A &&...args) {
125     return context_->Say(source, std::move(msg), std::forward<A>(args)...);
126   }
127 
128 private:
129   SemanticsContext *context_;
130 };
131 
132 // Inheritance graph for the parse tree visitation classes that follow:
133 //   BaseVisitor
134 //   + AttrsVisitor
135 //   | + DeclTypeSpecVisitor
136 //   |   + ImplicitRulesVisitor
137 //   |     + ScopeHandler -----------+--+
138 //   |       + ModuleVisitor ========|==+
139 //   |       + InterfaceVisitor      |  |
140 //   |       +-+ SubprogramVisitor ==|==+
141 //   + ArraySpecVisitor              |  |
142 //     + DeclarationVisitor <--------+  |
143 //       + ConstructVisitor             |
144 //         + ResolveNamesVisitor <------+
145 
146 class BaseVisitor {
147 public:
148   BaseVisitor() { DIE("BaseVisitor: default-constructed"); }
149   BaseVisitor(
150       SemanticsContext &c, ResolveNamesVisitor &v, ImplicitRulesMap &rules)
151       : implicitRulesMap_{&rules}, this_{&v}, context_{&c}, messageHandler_{c} {
152   }
153   template <typename T> void Walk(const T &);
154 
155   MessageHandler &messageHandler() { return messageHandler_; }
156   const std::optional<SourceName> &currStmtSource() {
157     return context_->location();
158   }
159   SemanticsContext &context() const { return *context_; }
160   evaluate::FoldingContext &GetFoldingContext() const {
161     return context_->foldingContext();
162   }
163   bool IsIntrinsic(
164       const SourceName &name, std::optional<Symbol::Flag> flag) const {
165     if (!flag) {
166       return context_->intrinsics().IsIntrinsic(name.ToString());
167     } else if (flag == Symbol::Flag::Function) {
168       return context_->intrinsics().IsIntrinsicFunction(name.ToString());
169     } else if (flag == Symbol::Flag::Subroutine) {
170       return context_->intrinsics().IsIntrinsicSubroutine(name.ToString());
171     } else {
172       DIE("expected Subroutine or Function flag");
173     }
174   }
175 
176   // Make a placeholder symbol for a Name that otherwise wouldn't have one.
177   // It is not in any scope and always has MiscDetails.
178   void MakePlaceholder(const parser::Name &, MiscDetails::Kind);
179 
180   template <typename T> common::IfNoLvalue<T, T> FoldExpr(T &&expr) {
181     return evaluate::Fold(GetFoldingContext(), std::move(expr));
182   }
183 
184   template <typename T> MaybeExpr EvaluateExpr(const T &expr) {
185     return FoldExpr(AnalyzeExpr(*context_, expr));
186   }
187 
188   template <typename T>
189   MaybeExpr EvaluateNonPointerInitializer(
190       const Symbol &symbol, const T &expr, parser::CharBlock source) {
191     if (!context().HasError(symbol)) {
192       if (auto maybeExpr{AnalyzeExpr(*context_, expr)}) {
193         auto restorer{GetFoldingContext().messages().SetLocation(source)};
194         return evaluate::NonPointerInitializationExpr(
195             symbol, std::move(*maybeExpr), GetFoldingContext());
196       }
197     }
198     return std::nullopt;
199   }
200 
201   template <typename T> MaybeIntExpr EvaluateIntExpr(const T &expr) {
202     return semantics::EvaluateIntExpr(*context_, expr);
203   }
204 
205   template <typename T>
206   MaybeSubscriptIntExpr EvaluateSubscriptIntExpr(const T &expr) {
207     if (MaybeIntExpr maybeIntExpr{EvaluateIntExpr(expr)}) {
208       return FoldExpr(evaluate::ConvertToType<evaluate::SubscriptInteger>(
209           std::move(*maybeIntExpr)));
210     } else {
211       return std::nullopt;
212     }
213   }
214 
215   template <typename... A> Message &Say(A &&...args) {
216     return messageHandler_.Say(std::forward<A>(args)...);
217   }
218   template <typename... A>
219   Message &Say(
220       const parser::Name &name, MessageFixedText &&text, const A &...args) {
221     return messageHandler_.Say(name.source, std::move(text), args...);
222   }
223 
224 protected:
225   ImplicitRulesMap *implicitRulesMap_{nullptr};
226 
227 private:
228   ResolveNamesVisitor *this_;
229   SemanticsContext *context_;
230   MessageHandler messageHandler_;
231 };
232 
233 // Provide Post methods to collect attributes into a member variable.
234 class AttrsVisitor : public virtual BaseVisitor {
235 public:
236   bool BeginAttrs(); // always returns true
237   Attrs GetAttrs();
238   Attrs EndAttrs();
239   bool SetPassNameOn(Symbol &);
240   void SetBindNameOn(Symbol &);
241   void Post(const parser::LanguageBindingSpec &);
242   bool Pre(const parser::IntentSpec &);
243   bool Pre(const parser::Pass &);
244 
245   bool CheckAndSet(Attr);
246 
247 // Simple case: encountering CLASSNAME causes ATTRNAME to be set.
248 #define HANDLE_ATTR_CLASS(CLASSNAME, ATTRNAME) \
249   bool Pre(const parser::CLASSNAME &) { \
250     CheckAndSet(Attr::ATTRNAME); \
251     return false; \
252   }
253   HANDLE_ATTR_CLASS(PrefixSpec::Elemental, ELEMENTAL)
254   HANDLE_ATTR_CLASS(PrefixSpec::Impure, IMPURE)
255   HANDLE_ATTR_CLASS(PrefixSpec::Module, MODULE)
256   HANDLE_ATTR_CLASS(PrefixSpec::Non_Recursive, NON_RECURSIVE)
257   HANDLE_ATTR_CLASS(PrefixSpec::Pure, PURE)
258   HANDLE_ATTR_CLASS(PrefixSpec::Recursive, RECURSIVE)
259   HANDLE_ATTR_CLASS(TypeAttrSpec::BindC, BIND_C)
260   HANDLE_ATTR_CLASS(BindAttr::Deferred, DEFERRED)
261   HANDLE_ATTR_CLASS(BindAttr::Non_Overridable, NON_OVERRIDABLE)
262   HANDLE_ATTR_CLASS(Abstract, ABSTRACT)
263   HANDLE_ATTR_CLASS(Allocatable, ALLOCATABLE)
264   HANDLE_ATTR_CLASS(Asynchronous, ASYNCHRONOUS)
265   HANDLE_ATTR_CLASS(Contiguous, CONTIGUOUS)
266   HANDLE_ATTR_CLASS(External, EXTERNAL)
267   HANDLE_ATTR_CLASS(Intrinsic, INTRINSIC)
268   HANDLE_ATTR_CLASS(NoPass, NOPASS)
269   HANDLE_ATTR_CLASS(Optional, OPTIONAL)
270   HANDLE_ATTR_CLASS(Parameter, PARAMETER)
271   HANDLE_ATTR_CLASS(Pointer, POINTER)
272   HANDLE_ATTR_CLASS(Protected, PROTECTED)
273   HANDLE_ATTR_CLASS(Save, SAVE)
274   HANDLE_ATTR_CLASS(Target, TARGET)
275   HANDLE_ATTR_CLASS(Value, VALUE)
276   HANDLE_ATTR_CLASS(Volatile, VOLATILE)
277 #undef HANDLE_ATTR_CLASS
278 
279 protected:
280   std::optional<Attrs> attrs_;
281 
282   Attr AccessSpecToAttr(const parser::AccessSpec &x) {
283     switch (x.v) {
284     case parser::AccessSpec::Kind::Public:
285       return Attr::PUBLIC;
286     case parser::AccessSpec::Kind::Private:
287       return Attr::PRIVATE;
288     }
289     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
290   }
291   Attr IntentSpecToAttr(const parser::IntentSpec &x) {
292     switch (x.v) {
293     case parser::IntentSpec::Intent::In:
294       return Attr::INTENT_IN;
295     case parser::IntentSpec::Intent::Out:
296       return Attr::INTENT_OUT;
297     case parser::IntentSpec::Intent::InOut:
298       return Attr::INTENT_INOUT;
299     }
300     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
301   }
302 
303 private:
304   bool IsDuplicateAttr(Attr);
305   bool HaveAttrConflict(Attr, Attr, Attr);
306   bool IsConflictingAttr(Attr);
307 
308   MaybeExpr bindName_; // from BIND(C, NAME="...")
309   std::optional<SourceName> passName_; // from PASS(...)
310 };
311 
312 // Find and create types from declaration-type-spec nodes.
313 class DeclTypeSpecVisitor : public AttrsVisitor {
314 public:
315   using AttrsVisitor::Post;
316   using AttrsVisitor::Pre;
317   void Post(const parser::IntrinsicTypeSpec::DoublePrecision &);
318   void Post(const parser::IntrinsicTypeSpec::DoubleComplex &);
319   void Post(const parser::DeclarationTypeSpec::ClassStar &);
320   void Post(const parser::DeclarationTypeSpec::TypeStar &);
321   bool Pre(const parser::TypeGuardStmt &);
322   void Post(const parser::TypeGuardStmt &);
323   void Post(const parser::TypeSpec &);
324 
325   // Walk the parse tree of a type spec and return the DeclTypeSpec for it.
326   template <typename T>
327   const DeclTypeSpec *ProcessTypeSpec(const T &x, bool allowForward = false) {
328     auto restorer{common::ScopedSet(state_, State{})};
329     set_allowForwardReferenceToDerivedType(allowForward);
330     BeginDeclTypeSpec();
331     Walk(x);
332     const auto *type{GetDeclTypeSpec()};
333     EndDeclTypeSpec();
334     return type;
335   }
336 
337 protected:
338   struct State {
339     bool expectDeclTypeSpec{false}; // should see decl-type-spec only when true
340     const DeclTypeSpec *declTypeSpec{nullptr};
341     struct {
342       DerivedTypeSpec *type{nullptr};
343       DeclTypeSpec::Category category{DeclTypeSpec::TypeDerived};
344     } derived;
345     bool allowForwardReferenceToDerivedType{false};
346   };
347 
348   bool allowForwardReferenceToDerivedType() const {
349     return state_.allowForwardReferenceToDerivedType;
350   }
351   void set_allowForwardReferenceToDerivedType(bool yes) {
352     state_.allowForwardReferenceToDerivedType = yes;
353   }
354 
355   const DeclTypeSpec *GetDeclTypeSpec();
356   void BeginDeclTypeSpec();
357   void EndDeclTypeSpec();
358   void SetDeclTypeSpec(const DeclTypeSpec &);
359   void SetDeclTypeSpecCategory(DeclTypeSpec::Category);
360   DeclTypeSpec::Category GetDeclTypeSpecCategory() const {
361     return state_.derived.category;
362   }
363   KindExpr GetKindParamExpr(
364       TypeCategory, const std::optional<parser::KindSelector> &);
365   void CheckForAbstractType(const Symbol &typeSymbol);
366 
367 private:
368   State state_;
369 
370   void MakeNumericType(TypeCategory, int kind);
371 };
372 
373 // Visit ImplicitStmt and related parse tree nodes and updates implicit rules.
374 class ImplicitRulesVisitor : public DeclTypeSpecVisitor {
375 public:
376   using DeclTypeSpecVisitor::Post;
377   using DeclTypeSpecVisitor::Pre;
378   using ImplicitNoneNameSpec = parser::ImplicitStmt::ImplicitNoneNameSpec;
379 
380   void Post(const parser::ParameterStmt &);
381   bool Pre(const parser::ImplicitStmt &);
382   bool Pre(const parser::LetterSpec &);
383   bool Pre(const parser::ImplicitSpec &);
384   void Post(const parser::ImplicitSpec &);
385 
386   const DeclTypeSpec *GetType(
387       SourceName name, bool respectImplicitNoneType = true) {
388     return implicitRules_->GetType(name, respectImplicitNoneType);
389   }
390   bool isImplicitNoneType() const {
391     return implicitRules_->isImplicitNoneType();
392   }
393   bool isImplicitNoneType(const Scope &scope) const {
394     return implicitRulesMap_->at(&scope).isImplicitNoneType();
395   }
396   bool isImplicitNoneExternal() const {
397     return implicitRules_->isImplicitNoneExternal();
398   }
399   void set_inheritFromParent(bool x) {
400     implicitRules_->set_inheritFromParent(x);
401   }
402 
403 protected:
404   void BeginScope(const Scope &);
405   void SetScope(const Scope &);
406 
407 private:
408   // implicit rules in effect for current scope
409   ImplicitRules *implicitRules_{nullptr};
410   std::optional<SourceName> prevImplicit_;
411   std::optional<SourceName> prevImplicitNone_;
412   std::optional<SourceName> prevImplicitNoneType_;
413   std::optional<SourceName> prevParameterStmt_;
414 
415   bool HandleImplicitNone(const std::list<ImplicitNoneNameSpec> &nameSpecs);
416 };
417 
418 // Track array specifications. They can occur in AttrSpec, EntityDecl,
419 // ObjectDecl, DimensionStmt, CommonBlockObject, or BasedPointerStmt.
420 // 1. INTEGER, DIMENSION(10) :: x
421 // 2. INTEGER :: x(10)
422 // 3. ALLOCATABLE :: x(:)
423 // 4. DIMENSION :: x(10)
424 // 5. COMMON x(10)
425 // 6. BasedPointerStmt
426 class ArraySpecVisitor : public virtual BaseVisitor {
427 public:
428   void Post(const parser::ArraySpec &);
429   void Post(const parser::ComponentArraySpec &);
430   void Post(const parser::CoarraySpec &);
431   void Post(const parser::AttrSpec &) { PostAttrSpec(); }
432   void Post(const parser::ComponentAttrSpec &) { PostAttrSpec(); }
433 
434 protected:
435   const ArraySpec &arraySpec();
436   void set_arraySpec(const ArraySpec arraySpec) { arraySpec_ = arraySpec; }
437   const ArraySpec &coarraySpec();
438   void BeginArraySpec();
439   void EndArraySpec();
440   void ClearArraySpec() { arraySpec_.clear(); }
441   void ClearCoarraySpec() { coarraySpec_.clear(); }
442 
443 private:
444   // arraySpec_/coarraySpec_ are populated from any ArraySpec/CoarraySpec
445   ArraySpec arraySpec_;
446   ArraySpec coarraySpec_;
447   // When an ArraySpec is under an AttrSpec or ComponentAttrSpec, it is moved
448   // into attrArraySpec_
449   ArraySpec attrArraySpec_;
450   ArraySpec attrCoarraySpec_;
451 
452   void PostAttrSpec();
453 };
454 
455 // Manages a stack of function result information.  We defer the processing
456 // of a type specification that appears in the prefix of a FUNCTION statement
457 // until the function result variable appears in the specification part
458 // or the end of the specification part.  This allows for forward references
459 // in the type specification to resolve to local names.
460 class FuncResultStack {
461 public:
462   explicit FuncResultStack(ScopeHandler &scopeHandler)
463       : scopeHandler_{scopeHandler} {}
464   ~FuncResultStack();
465 
466   struct FuncInfo {
467     // Parse tree of the type specification in the FUNCTION prefix
468     const parser::DeclarationTypeSpec *parsedType{nullptr};
469     // Name of the function RESULT in the FUNCTION suffix, if any
470     const parser::Name *resultName{nullptr};
471     // Result symbol
472     Symbol *resultSymbol{nullptr};
473     std::optional<SourceName> source;
474     bool inFunctionStmt{false}; // true between Pre/Post of FunctionStmt
475   };
476 
477   // Completes the definition of the top function's result.
478   void CompleteFunctionResultType();
479   // Completes the definition of a symbol if it is the top function's result.
480   void CompleteTypeIfFunctionResult(Symbol &);
481 
482   FuncInfo *Top() { return stack_.empty() ? nullptr : &stack_.back(); }
483   FuncInfo &Push() { return stack_.emplace_back(); }
484   void Pop() { stack_.pop_back(); }
485 
486 private:
487   ScopeHandler &scopeHandler_;
488   std::vector<FuncInfo> stack_;
489 };
490 
491 // Manage a stack of Scopes
492 class ScopeHandler : public ImplicitRulesVisitor {
493 public:
494   using ImplicitRulesVisitor::Post;
495   using ImplicitRulesVisitor::Pre;
496 
497   Scope &currScope() { return DEREF(currScope_); }
498   // The enclosing host procedure if current scope is in an internal procedure
499   Scope *GetHostProcedure();
500   // The innermost enclosing program unit scope, ignoring BLOCK and other
501   // construct scopes.
502   Scope &InclusiveScope();
503   // The enclosing scope, skipping derived types.
504   Scope &NonDerivedTypeScope();
505 
506   // Create a new scope and push it on the scope stack.
507   void PushScope(Scope::Kind kind, Symbol *symbol);
508   void PushScope(Scope &scope);
509   void PopScope();
510   void SetScope(Scope &);
511 
512   template <typename T> bool Pre(const parser::Statement<T> &x) {
513     messageHandler().set_currStmtSource(x.source);
514     currScope_->AddSourceRange(x.source);
515     return true;
516   }
517   template <typename T> void Post(const parser::Statement<T> &) {
518     messageHandler().set_currStmtSource(std::nullopt);
519   }
520 
521   // Special messages: already declared; referencing symbol's declaration;
522   // about a type; two names & locations
523   void SayAlreadyDeclared(const parser::Name &, Symbol &);
524   void SayAlreadyDeclared(const SourceName &, Symbol &);
525   void SayAlreadyDeclared(const SourceName &, const SourceName &);
526   void SayWithReason(
527       const parser::Name &, Symbol &, MessageFixedText &&, Message &&);
528   void SayWithDecl(const parser::Name &, Symbol &, MessageFixedText &&);
529   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
530   void SayDerivedType(const SourceName &, MessageFixedText &&, const Scope &);
531   void Say2(const SourceName &, MessageFixedText &&, const SourceName &,
532       MessageFixedText &&);
533   void Say2(
534       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
535   void Say2(
536       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
537 
538   // Search for symbol by name in current, parent derived type, and
539   // containing scopes
540   Symbol *FindSymbol(const parser::Name &);
541   Symbol *FindSymbol(const Scope &, const parser::Name &);
542   // Search for name only in scope, not in enclosing scopes.
543   Symbol *FindInScope(const Scope &, const parser::Name &);
544   Symbol *FindInScope(const Scope &, const SourceName &);
545   template <typename T> Symbol *FindInScope(const T &name) {
546     return FindInScope(currScope(), name);
547   }
548   // Search for name in a derived type scope and its parents.
549   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
550   Symbol *FindInTypeOrParents(const parser::Name &);
551   void EraseSymbol(const parser::Name &);
552   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
553   // Make a new symbol with the name and attrs of an existing one
554   Symbol &CopySymbol(const SourceName &, const Symbol &);
555 
556   // Make symbols in the current or named scope
557   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
558   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
559   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
560   Symbol &MakeHostAssocSymbol(const parser::Name &, const Symbol &);
561 
562   template <typename D>
563   common::IfNoLvalue<Symbol &, D> MakeSymbol(
564       const parser::Name &name, D &&details) {
565     return MakeSymbol(name, Attrs{}, std::move(details));
566   }
567 
568   template <typename D>
569   common::IfNoLvalue<Symbol &, D> MakeSymbol(
570       const parser::Name &name, const Attrs &attrs, D &&details) {
571     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
572   }
573 
574   template <typename D>
575   common::IfNoLvalue<Symbol &, D> MakeSymbol(
576       const SourceName &name, const Attrs &attrs, D &&details) {
577     // Note: don't use FindSymbol here. If this is a derived type scope,
578     // we want to detect whether the name is already declared as a component.
579     auto *symbol{FindInScope(name)};
580     if (!symbol) {
581       symbol = &MakeSymbol(name, attrs);
582       symbol->set_details(std::move(details));
583       return *symbol;
584     }
585     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
586       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
587         if (!d->specific()) {
588           // derived type with same name as a generic
589           auto *derivedType{d->derivedType()};
590           if (!derivedType) {
591             derivedType =
592                 &currScope().MakeSymbol(name, attrs, std::move(details));
593             d->set_derivedType(*derivedType);
594           } else {
595             SayAlreadyDeclared(name, *derivedType);
596           }
597           return *derivedType;
598         }
599       }
600     }
601     if (symbol->CanReplaceDetails(details)) {
602       // update the existing symbol
603       symbol->attrs() |= attrs;
604       if constexpr (std::is_same_v<SubprogramDetails, D>) {
605         // Dummy argument defined by explicit interface
606         details.set_isDummy(IsDummy(*symbol));
607       }
608       symbol->set_details(std::move(details));
609       return *symbol;
610     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
611       symbol->attrs() |= attrs;
612       return *symbol;
613     } else {
614       if (!CheckPossibleBadForwardRef(*symbol)) {
615         SayAlreadyDeclared(name, *symbol);
616       }
617       // replace the old symbol with a new one with correct details
618       EraseSymbol(*symbol);
619       auto &result{MakeSymbol(name, attrs, std::move(details))};
620       context().SetError(result);
621       return result;
622     }
623   }
624 
625   void MakeExternal(Symbol &);
626 
627 protected:
628   FuncResultStack &funcResultStack() { return funcResultStack_; }
629 
630   // Apply the implicit type rules to this symbol.
631   void ApplyImplicitRules(Symbol &, bool allowForwardReference = false);
632   bool ImplicitlyTypeForwardRef(Symbol &);
633   void AcquireIntrinsicProcedureFlags(Symbol &);
634   const DeclTypeSpec *GetImplicitType(
635       Symbol &, bool respectImplicitNoneType = true);
636   bool ConvertToObjectEntity(Symbol &);
637   bool ConvertToProcEntity(Symbol &);
638 
639   const DeclTypeSpec &MakeNumericType(
640       TypeCategory, const std::optional<parser::KindSelector> &);
641   const DeclTypeSpec &MakeLogicalType(
642       const std::optional<parser::KindSelector> &);
643   void NotePossibleBadForwardRef(const parser::Name &);
644   std::optional<SourceName> HadForwardRef(const Symbol &) const;
645   bool CheckPossibleBadForwardRef(const Symbol &);
646 
647   bool inExecutionPart_{false};
648   bool inSpecificationPart_{false};
649   bool inEquivalenceStmt_{false};
650 
651   // Some information is collected from a specification part for deferred
652   // processing in DeclarationPartVisitor functions (e.g., CheckSaveStmts())
653   // that are called by ResolveNamesVisitor::FinishSpecificationPart().  Since
654   // specification parts can nest (e.g., INTERFACE bodies), the collected
655   // information that is not contained in the scope needs to be packaged
656   // and restorable.
657   struct SpecificationPartState {
658     std::set<SourceName> forwardRefs;
659     // Collect equivalence sets and process at end of specification part
660     std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets;
661     // Names of all common block objects in the scope
662     std::set<SourceName> commonBlockObjects;
663     // Info about about SAVE statements and attributes in current scope
664     struct {
665       std::optional<SourceName> saveAll; // "SAVE" without entity list
666       std::set<SourceName> entities; // names of entities with save attr
667       std::set<SourceName> commons; // names of common blocks with save attr
668     } saveInfo;
669   } specPartState_;
670 
671   // Some declaration processing can and should be deferred to
672   // ResolveExecutionParts() to avoid prematurely creating implicitly-typed
673   // local symbols that should be host associations.
674   struct DeferredDeclarationState {
675     // The content of each namelist group
676     std::list<const parser::NamelistStmt::Group *> namelistGroups;
677   };
678   DeferredDeclarationState *GetDeferredDeclarationState(bool add = false) {
679     if (!add && deferred_.find(&currScope()) == deferred_.end()) {
680       return nullptr;
681     } else {
682       return &deferred_.emplace(&currScope(), DeferredDeclarationState{})
683                   .first->second;
684     }
685   }
686 
687 private:
688   Scope *currScope_{nullptr};
689   FuncResultStack funcResultStack_{*this};
690   std::map<Scope *, DeferredDeclarationState> deferred_;
691 };
692 
693 class ModuleVisitor : public virtual ScopeHandler {
694 public:
695   bool Pre(const parser::AccessStmt &);
696   bool Pre(const parser::Only &);
697   bool Pre(const parser::Rename::Names &);
698   bool Pre(const parser::Rename::Operators &);
699   bool Pre(const parser::UseStmt &);
700   void Post(const parser::UseStmt &);
701 
702   void BeginModule(const parser::Name &, bool isSubmodule);
703   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
704   void ApplyDefaultAccess();
705   Symbol &AddGenericUse(GenericDetails &, const SourceName &, const Symbol &);
706   void AddAndCheckExplicitIntrinsicUse(SourceName, bool isIntrinsic);
707   void ClearUseRenames() { useRenames_.clear(); }
708   void ClearUseOnly() { useOnly_.clear(); }
709   void ClearExplicitIntrinsicUses() {
710     explicitIntrinsicUses_.clear();
711     explicitNonIntrinsicUses_.clear();
712   }
713 
714 private:
715   // The default access spec for this module.
716   Attr defaultAccess_{Attr::PUBLIC};
717   // The location of the last AccessStmt without access-ids, if any.
718   std::optional<SourceName> prevAccessStmt_;
719   // The scope of the module during a UseStmt
720   Scope *useModuleScope_{nullptr};
721   // Names that have appeared in a rename clause of a USE statement
722   std::set<std::pair<SourceName, Scope *>> useRenames_;
723   // Names that have appeared in an ONLY clause of a USE statement
724   std::set<std::pair<SourceName, Scope *>> useOnly_;
725   // Module names that have appeared in USE statements with explicit
726   // INTRINSIC or NON_INTRINSIC keywords
727   std::set<SourceName> explicitIntrinsicUses_;
728   std::set<SourceName> explicitNonIntrinsicUses_;
729 
730   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
731   // A rename in a USE statement: local => use
732   struct SymbolRename {
733     Symbol *local{nullptr};
734     Symbol *use{nullptr};
735   };
736   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
737   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
738   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
739   void DoAddUse(
740       SourceName, SourceName, Symbol &localSymbol, const Symbol &useSymbol);
741   void AddUse(const GenericSpecInfo &);
742   // If appropriate, erase a previously USE-associated symbol
743   void EraseRenamedSymbol(const Symbol &);
744   // Record a name appearing in a USE rename clause
745   void AddUseRename(const SourceName &name) {
746     useRenames_.emplace(std::make_pair(name, useModuleScope_));
747   }
748   bool IsUseRenamed(const SourceName &name) const {
749     return useRenames_.find({name, useModuleScope_}) != useRenames_.end();
750   }
751   // Record a name appearing in a USE ONLY clause
752   void AddUseOnly(const SourceName &name) {
753     useOnly_.emplace(std::make_pair(name, useModuleScope_));
754   }
755   bool IsUseOnly(const SourceName &name) const {
756     return useOnly_.find({name, useModuleScope_}) != useOnly_.end();
757   }
758   Scope *FindModule(const parser::Name &, std::optional<bool> isIntrinsic,
759       Scope *ancestor = nullptr);
760 };
761 
762 class InterfaceVisitor : public virtual ScopeHandler {
763 public:
764   bool Pre(const parser::InterfaceStmt &);
765   void Post(const parser::InterfaceStmt &);
766   void Post(const parser::EndInterfaceStmt &);
767   bool Pre(const parser::GenericSpec &);
768   bool Pre(const parser::ProcedureStmt &);
769   bool Pre(const parser::GenericStmt &);
770   void Post(const parser::GenericStmt &);
771 
772   bool inInterfaceBlock() const;
773   bool isGeneric() const;
774   bool isAbstract() const;
775 
776 protected:
777   Symbol &GetGenericSymbol() {
778     return DEREF(genericInfo_.top().symbol);
779   }
780   // Add to generic the symbol for the subprogram with the same name
781   void CheckGenericProcedures(Symbol &);
782 
783 private:
784   // A new GenericInfo is pushed for each interface block and generic stmt
785   struct GenericInfo {
786     GenericInfo(bool isInterface, bool isAbstract = false)
787         : isInterface{isInterface}, isAbstract{isAbstract} {}
788     bool isInterface; // in interface block
789     bool isAbstract; // in abstract interface block
790     Symbol *symbol{nullptr}; // the generic symbol being defined
791   };
792   std::stack<GenericInfo> genericInfo_;
793   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
794   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
795 
796   using ProcedureKind = parser::ProcedureStmt::Kind;
797   // mapping of generic to its specific proc names and kinds
798   std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>
799       specificProcs_;
800 
801   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
802   void ResolveSpecificsInGeneric(Symbol &generic);
803 };
804 
805 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
806 public:
807   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
808   bool Pre(const parser::SubroutineStmt &);
809   void Post(const parser::SubroutineStmt &);
810   bool Pre(const parser::FunctionStmt &);
811   void Post(const parser::FunctionStmt &);
812   bool Pre(const parser::EntryStmt &);
813   void Post(const parser::EntryStmt &);
814   bool Pre(const parser::InterfaceBody::Subroutine &);
815   void Post(const parser::InterfaceBody::Subroutine &);
816   bool Pre(const parser::InterfaceBody::Function &);
817   void Post(const parser::InterfaceBody::Function &);
818   bool Pre(const parser::Suffix &);
819   bool Pre(const parser::PrefixSpec &);
820 
821   bool BeginSubprogram(const parser::Name &, Symbol::Flag,
822       bool hasModulePrefix = false,
823       const parser::LanguageBindingSpec * = nullptr);
824   bool BeginMpSubprogram(const parser::Name &);
825   void PushBlockDataScope(const parser::Name &);
826   void EndSubprogram();
827 
828 protected:
829   // Set when we see a stmt function that is really an array element assignment
830   bool badStmtFuncFound_{false};
831 
832 private:
833   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
834   // so that it can be replaced by a later definition.
835   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
836   void CheckExtantProc(const parser::Name &, Symbol::Flag);
837   // Create a subprogram symbol in the current scope and push a new scope.
838   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag,
839       const parser::LanguageBindingSpec * = nullptr);
840   Symbol *GetSpecificFromGeneric(const parser::Name &);
841   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
842 };
843 
844 class DeclarationVisitor : public ArraySpecVisitor,
845                            public virtual ScopeHandler {
846 public:
847   using ArraySpecVisitor::Post;
848   using ScopeHandler::Post;
849   using ScopeHandler::Pre;
850 
851   bool Pre(const parser::Initialization &);
852   void Post(const parser::EntityDecl &);
853   void Post(const parser::ObjectDecl &);
854   void Post(const parser::PointerDecl &);
855   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
856   void Post(const parser::BindStmt &) { EndAttrs(); }
857   bool Pre(const parser::BindEntity &);
858   bool Pre(const parser::OldParameterStmt &);
859   bool Pre(const parser::NamedConstantDef &);
860   bool Pre(const parser::NamedConstant &);
861   void Post(const parser::EnumDef &);
862   bool Pre(const parser::Enumerator &);
863   bool Pre(const parser::AccessSpec &);
864   bool Pre(const parser::AsynchronousStmt &);
865   bool Pre(const parser::ContiguousStmt &);
866   bool Pre(const parser::ExternalStmt &);
867   bool Pre(const parser::IntentStmt &);
868   bool Pre(const parser::IntrinsicStmt &);
869   bool Pre(const parser::OptionalStmt &);
870   bool Pre(const parser::ProtectedStmt &);
871   bool Pre(const parser::ValueStmt &);
872   bool Pre(const parser::VolatileStmt &);
873   bool Pre(const parser::AllocatableStmt &) {
874     objectDeclAttr_ = Attr::ALLOCATABLE;
875     return true;
876   }
877   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
878   bool Pre(const parser::TargetStmt &) {
879     objectDeclAttr_ = Attr::TARGET;
880     return true;
881   }
882   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
883   void Post(const parser::DimensionStmt::Declaration &);
884   void Post(const parser::CodimensionDecl &);
885   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
886   void Post(const parser::TypeDeclarationStmt &);
887   void Post(const parser::IntegerTypeSpec &);
888   void Post(const parser::IntrinsicTypeSpec::Real &);
889   void Post(const parser::IntrinsicTypeSpec::Complex &);
890   void Post(const parser::IntrinsicTypeSpec::Logical &);
891   void Post(const parser::IntrinsicTypeSpec::Character &);
892   void Post(const parser::CharSelector::LengthAndKind &);
893   void Post(const parser::CharLength &);
894   void Post(const parser::LengthSelector &);
895   bool Pre(const parser::KindParam &);
896   bool Pre(const parser::DeclarationTypeSpec::Type &);
897   void Post(const parser::DeclarationTypeSpec::Type &);
898   bool Pre(const parser::DeclarationTypeSpec::Class &);
899   void Post(const parser::DeclarationTypeSpec::Class &);
900   void Post(const parser::DeclarationTypeSpec::Record &);
901   void Post(const parser::DerivedTypeSpec &);
902   bool Pre(const parser::DerivedTypeDef &);
903   bool Pre(const parser::DerivedTypeStmt &);
904   void Post(const parser::DerivedTypeStmt &);
905   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
906   void Post(const parser::TypeParamDefStmt &);
907   bool Pre(const parser::TypeAttrSpec::Extends &);
908   bool Pre(const parser::PrivateStmt &);
909   bool Pre(const parser::SequenceStmt &);
910   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
911   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
912   void Post(const parser::ComponentDecl &);
913   void Post(const parser::FillDecl &);
914   bool Pre(const parser::ProcedureDeclarationStmt &);
915   void Post(const parser::ProcedureDeclarationStmt &);
916   bool Pre(const parser::DataComponentDefStmt &); // returns false
917   bool Pre(const parser::ProcComponentDefStmt &);
918   void Post(const parser::ProcComponentDefStmt &);
919   bool Pre(const parser::ProcPointerInit &);
920   void Post(const parser::ProcInterface &);
921   void Post(const parser::ProcDecl &);
922   bool Pre(const parser::TypeBoundProcedurePart &);
923   void Post(const parser::TypeBoundProcedurePart &);
924   void Post(const parser::ContainsStmt &);
925   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
926   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
927   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
928   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
929   void Post(const parser::FinalProcedureStmt &);
930   bool Pre(const parser::TypeBoundGenericStmt &);
931   bool Pre(const parser::StructureDef &); // returns false
932   bool Pre(const parser::Union::UnionStmt &);
933   bool Pre(const parser::StructureField &);
934   void Post(const parser::StructureField &);
935   bool Pre(const parser::AllocateStmt &);
936   void Post(const parser::AllocateStmt &);
937   bool Pre(const parser::StructureConstructor &);
938   bool Pre(const parser::NamelistStmt::Group &);
939   bool Pre(const parser::IoControlSpec &);
940   bool Pre(const parser::CommonStmt::Block &);
941   bool Pre(const parser::CommonBlockObject &);
942   void Post(const parser::CommonBlockObject &);
943   bool Pre(const parser::EquivalenceStmt &);
944   bool Pre(const parser::SaveStmt &);
945   bool Pre(const parser::BasedPointerStmt &);
946 
947   void PointerInitialization(
948       const parser::Name &, const parser::InitialDataTarget &);
949   void PointerInitialization(
950       const parser::Name &, const parser::ProcPointerInit &);
951   void NonPointerInitialization(
952       const parser::Name &, const parser::ConstantExpr &);
953   void CheckExplicitInterface(const parser::Name &);
954   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
955 
956   const parser::Name *ResolveDesignator(const parser::Designator &);
957 
958 protected:
959   bool BeginDecl();
960   void EndDecl();
961   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
962   // Make sure that there's an entity in an enclosing scope called Name
963   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
964   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
965   // it comes from the entity in the containing scope, or implicit rules.
966   // Return pointer to the new symbol, or nullptr on error.
967   Symbol *DeclareLocalEntity(const parser::Name &);
968   // Declare a statement entity (i.e., an implied DO loop index for
969   // a DATA statement or an array constructor).  If there isn't an explict
970   // type specified, implicit rules apply. Return pointer to the new symbol,
971   // or nullptr on error.
972   Symbol *DeclareStatementEntity(const parser::DoVariable &,
973       const std::optional<parser::IntegerTypeSpec> &);
974   Symbol &MakeCommonBlockSymbol(const parser::Name &);
975   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
976   bool CheckUseError(const parser::Name &);
977   void CheckAccessibility(const SourceName &, bool, Symbol &);
978   void CheckCommonBlocks();
979   void CheckSaveStmts();
980   void CheckEquivalenceSets();
981   bool CheckNotInBlock(const char *);
982   bool NameIsKnownOrIntrinsic(const parser::Name &);
983   void FinishNamelists();
984 
985   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
986   // or nullptr in case of error.
987   const parser::Name *ResolveStructureComponent(
988       const parser::StructureComponent &);
989   const parser::Name *ResolveDataRef(const parser::DataRef &);
990   const parser::Name *ResolveName(const parser::Name &);
991   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
992   Symbol *NoteInterfaceName(const parser::Name &);
993   bool IsUplevelReference(const Symbol &);
994 
995   std::optional<SourceName> BeginCheckOnIndexUseInOwnBounds(
996       const parser::DoVariable &name) {
997     std::optional<SourceName> result{checkIndexUseInOwnBounds_};
998     checkIndexUseInOwnBounds_ = name.thing.thing.source;
999     return result;
1000   }
1001   void EndCheckOnIndexUseInOwnBounds(const std::optional<SourceName> &restore) {
1002     checkIndexUseInOwnBounds_ = restore;
1003   }
1004 
1005 private:
1006   // The attribute corresponding to the statement containing an ObjectDecl
1007   std::optional<Attr> objectDeclAttr_;
1008   // Info about current character type while walking DeclTypeSpec.
1009   // Also captures any "*length" specifier on an individual declaration.
1010   struct {
1011     std::optional<ParamValue> length;
1012     std::optional<KindExpr> kind;
1013   } charInfo_;
1014   // Info about current derived type or STRUCTURE while walking
1015   // DerivedTypeDef / StructureDef
1016   struct {
1017     const parser::Name *extends{nullptr}; // EXTENDS(name)
1018     bool privateComps{false}; // components are private by default
1019     bool privateBindings{false}; // bindings are private by default
1020     bool sawContains{false}; // currently processing bindings
1021     bool sequence{false}; // is a sequence type
1022     const Symbol *type{nullptr}; // derived type being defined
1023     bool isStructure{false}; // is a DEC STRUCTURE
1024   } derivedTypeInfo_;
1025   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
1026   // the interface name, if any.
1027   const parser::Name *interfaceName_{nullptr};
1028   // Map type-bound generic to binding names of its specific bindings
1029   std::multimap<Symbol *, const parser::Name *> genericBindings_;
1030   // Info about current ENUM
1031   struct EnumeratorState {
1032     // Enum value must hold inside a C_INT (7.6.2).
1033     std::optional<int> value{0};
1034   } enumerationState_;
1035   // Set for OldParameterStmt processing
1036   bool inOldStyleParameterStmt_{false};
1037   // Set when walking DATA & array constructor implied DO loop bounds
1038   // to warn about use of the implied DO intex therein.
1039   std::optional<SourceName> checkIndexUseInOwnBounds_;
1040 
1041   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
1042   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
1043   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
1044   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
1045   void SetType(const parser::Name &, const DeclTypeSpec &);
1046   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
1047   std::optional<DerivedTypeSpec> ResolveExtendsType(
1048       const parser::Name &, const parser::Name *);
1049   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
1050   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1051   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
1052   ParamValue GetParamValue(
1053       const parser::TypeParamValue &, common::TypeParamAttr attr);
1054   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
1055   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
1056   Attrs HandleSaveName(const SourceName &, Attrs);
1057   void AddSaveName(std::set<SourceName> &, const SourceName &);
1058   void SetSaveAttr(Symbol &);
1059   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1060   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1061   void Initialization(const parser::Name &, const parser::Initialization &,
1062       bool inComponentDecl);
1063   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
1064   bool CheckForHostAssociatedImplicit(const parser::Name &);
1065 
1066   // Declare an object or procedure entity.
1067   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1068   template <typename T>
1069   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1070     Symbol &symbol{MakeSymbol(name, attrs)};
1071     if (context().HasError(symbol) || symbol.has<T>()) {
1072       return symbol; // OK or error already reported
1073     } else if (symbol.has<UnknownDetails>()) {
1074       symbol.set_details(T{});
1075       return symbol;
1076     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1077       symbol.set_details(T{std::move(*details)});
1078       return symbol;
1079     } else if (std::is_same_v<EntityDetails, T> &&
1080         (symbol.has<ObjectEntityDetails>() ||
1081             symbol.has<ProcEntityDetails>())) {
1082       return symbol; // OK
1083     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1084       Say(name.source,
1085           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1086           name.source, GetUsedModule(*details).name());
1087     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1088       if (details->kind() == SubprogramKind::Module) {
1089         Say2(name,
1090             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1091             symbol, "Module procedure definition"_en_US);
1092       } else if (details->kind() == SubprogramKind::Internal) {
1093         Say2(name,
1094             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1095             symbol, "Internal procedure definition"_en_US);
1096       } else {
1097         DIE("unexpected kind");
1098       }
1099     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1100         symbol.has<ProcEntityDetails>()) {
1101       SayWithDecl(
1102           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1103     } else if (std::is_same_v<ProcEntityDetails, T> &&
1104         symbol.has<ObjectEntityDetails>()) {
1105       if (InCommonBlock(symbol)) {
1106         SayWithDecl(name, symbol,
1107             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1108       } else {
1109         SayWithDecl(
1110             name, symbol, "'%s' is already declared as an object"_err_en_US);
1111       }
1112     } else if (!CheckPossibleBadForwardRef(symbol)) {
1113       SayAlreadyDeclared(name, symbol);
1114     }
1115     context().SetError(symbol);
1116     return symbol;
1117   }
1118   bool HasCycle(const Symbol &, const ProcInterface &);
1119 };
1120 
1121 // Resolve construct entities and statement entities.
1122 // Check that construct names don't conflict with other names.
1123 class ConstructVisitor : public virtual DeclarationVisitor {
1124 public:
1125   bool Pre(const parser::ConcurrentHeader &);
1126   bool Pre(const parser::LocalitySpec::Local &);
1127   bool Pre(const parser::LocalitySpec::LocalInit &);
1128   bool Pre(const parser::LocalitySpec::Shared &);
1129   bool Pre(const parser::AcSpec &);
1130   bool Pre(const parser::AcImpliedDo &);
1131   bool Pre(const parser::DataImpliedDo &);
1132   bool Pre(const parser::DataIDoObject &);
1133   bool Pre(const parser::DataStmtObject &);
1134   bool Pre(const parser::DataStmtValue &);
1135   bool Pre(const parser::DoConstruct &);
1136   void Post(const parser::DoConstruct &);
1137   bool Pre(const parser::ForallConstruct &);
1138   void Post(const parser::ForallConstruct &);
1139   bool Pre(const parser::ForallStmt &);
1140   void Post(const parser::ForallStmt &);
1141   bool Pre(const parser::BlockStmt &);
1142   bool Pre(const parser::EndBlockStmt &);
1143   void Post(const parser::Selector &);
1144   void Post(const parser::AssociateStmt &);
1145   void Post(const parser::EndAssociateStmt &);
1146   bool Pre(const parser::Association &);
1147   void Post(const parser::SelectTypeStmt &);
1148   void Post(const parser::SelectRankStmt &);
1149   bool Pre(const parser::SelectTypeConstruct &);
1150   void Post(const parser::SelectTypeConstruct &);
1151   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1152   void Post(const parser::SelectTypeConstruct::TypeCase &);
1153   // Creates Block scopes with neither symbol name nor symbol details.
1154   bool Pre(const parser::SelectRankConstruct::RankCase &);
1155   void Post(const parser::SelectRankConstruct::RankCase &);
1156   void Post(const parser::TypeGuardStmt::Guard &);
1157   void Post(const parser::SelectRankCaseStmt::Rank &);
1158   bool Pre(const parser::ChangeTeamStmt &);
1159   void Post(const parser::EndChangeTeamStmt &);
1160   void Post(const parser::CoarrayAssociation &);
1161 
1162   // Definitions of construct names
1163   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1164   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1165   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1166   bool Pre(const parser::LabelDoStmt &) {
1167     return false; // error recovery
1168   }
1169   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1170   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1171   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1172   bool Pre(const parser::SelectRankConstruct &);
1173   void Post(const parser::SelectRankConstruct &);
1174   bool Pre(const parser::SelectRankStmt &x) {
1175     return CheckDef(std::get<0>(x.t));
1176   }
1177   bool Pre(const parser::SelectTypeStmt &x) {
1178     return CheckDef(std::get<0>(x.t));
1179   }
1180 
1181   // References to construct names
1182   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1183   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1184   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1185   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1186   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1187   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1188   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1189   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1190   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1191   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1192   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1193   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1194   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1195   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1196   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1197 
1198 private:
1199   // R1105 selector -> expr | variable
1200   // expr is set in either case unless there were errors
1201   struct Selector {
1202     Selector() {}
1203     Selector(const SourceName &source, MaybeExpr &&expr)
1204         : source{source}, expr{std::move(expr)} {}
1205     operator bool() const { return expr.has_value(); }
1206     parser::CharBlock source;
1207     MaybeExpr expr;
1208   };
1209   // association -> [associate-name =>] selector
1210   struct Association {
1211     const parser::Name *name{nullptr};
1212     Selector selector;
1213   };
1214   std::vector<Association> associationStack_;
1215   Association *currentAssociation_{nullptr};
1216 
1217   template <typename T> bool CheckDef(const T &t) {
1218     return CheckDef(std::get<std::optional<parser::Name>>(t));
1219   }
1220   template <typename T> void CheckRef(const T &t) {
1221     CheckRef(std::get<std::optional<parser::Name>>(t));
1222   }
1223   bool CheckDef(const std::optional<parser::Name> &);
1224   void CheckRef(const std::optional<parser::Name> &);
1225   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1226   const DeclTypeSpec &ToDeclTypeSpec(
1227       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1228   Symbol *MakeAssocEntity();
1229   void SetTypeFromAssociation(Symbol &);
1230   void SetAttrsFromAssociation(Symbol &);
1231   Selector ResolveSelector(const parser::Selector &);
1232   void ResolveIndexName(const parser::ConcurrentControl &control);
1233   void SetCurrentAssociation(std::size_t n);
1234   Association &GetCurrentAssociation();
1235   void PushAssociation();
1236   void PopAssociation(std::size_t count = 1);
1237 };
1238 
1239 // Create scopes for OpenACC constructs
1240 class AccVisitor : public virtual DeclarationVisitor {
1241 public:
1242   void AddAccSourceRange(const parser::CharBlock &);
1243 
1244   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1245 
1246   bool Pre(const parser::OpenACCBlockConstruct &);
1247   void Post(const parser::OpenACCBlockConstruct &);
1248   bool Pre(const parser::AccBeginBlockDirective &x) {
1249     AddAccSourceRange(x.source);
1250     return true;
1251   }
1252   void Post(const parser::AccBeginBlockDirective &) {
1253     messageHandler().set_currStmtSource(std::nullopt);
1254   }
1255   bool Pre(const parser::AccEndBlockDirective &x) {
1256     AddAccSourceRange(x.source);
1257     return true;
1258   }
1259   void Post(const parser::AccEndBlockDirective &) {
1260     messageHandler().set_currStmtSource(std::nullopt);
1261   }
1262   bool Pre(const parser::AccBeginLoopDirective &x) {
1263     AddAccSourceRange(x.source);
1264     return true;
1265   }
1266   void Post(const parser::AccBeginLoopDirective &x) {
1267     messageHandler().set_currStmtSource(std::nullopt);
1268   }
1269 };
1270 
1271 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1272   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1273   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1274   switch (beginDir.v) {
1275   case llvm::acc::Directive::ACCD_data:
1276   case llvm::acc::Directive::ACCD_host_data:
1277   case llvm::acc::Directive::ACCD_kernels:
1278   case llvm::acc::Directive::ACCD_parallel:
1279   case llvm::acc::Directive::ACCD_serial:
1280     return true;
1281   default:
1282     return false;
1283   }
1284 }
1285 
1286 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1287   messageHandler().set_currStmtSource(source);
1288   currScope().AddSourceRange(source);
1289 }
1290 
1291 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1292   if (NeedsScope(x)) {
1293     PushScope(Scope::Kind::Block, nullptr);
1294   }
1295   return true;
1296 }
1297 
1298 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1299   if (NeedsScope(x)) {
1300     PopScope();
1301   }
1302 }
1303 
1304 // Create scopes for OpenMP constructs
1305 class OmpVisitor : public virtual DeclarationVisitor {
1306 public:
1307   void AddOmpSourceRange(const parser::CharBlock &);
1308 
1309   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1310 
1311   bool Pre(const parser::OpenMPBlockConstruct &);
1312   void Post(const parser::OpenMPBlockConstruct &);
1313   bool Pre(const parser::OmpBeginBlockDirective &x) {
1314     AddOmpSourceRange(x.source);
1315     return true;
1316   }
1317   void Post(const parser::OmpBeginBlockDirective &) {
1318     messageHandler().set_currStmtSource(std::nullopt);
1319   }
1320   bool Pre(const parser::OmpEndBlockDirective &x) {
1321     AddOmpSourceRange(x.source);
1322     return true;
1323   }
1324   void Post(const parser::OmpEndBlockDirective &) {
1325     messageHandler().set_currStmtSource(std::nullopt);
1326   }
1327 
1328   bool Pre(const parser::OpenMPLoopConstruct &) {
1329     PushScope(Scope::Kind::Block, nullptr);
1330     return true;
1331   }
1332   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1333   bool Pre(const parser::OmpBeginLoopDirective &x) {
1334     AddOmpSourceRange(x.source);
1335     return true;
1336   }
1337   void Post(const parser::OmpBeginLoopDirective &) {
1338     messageHandler().set_currStmtSource(std::nullopt);
1339   }
1340   bool Pre(const parser::OmpEndLoopDirective &x) {
1341     AddOmpSourceRange(x.source);
1342     return true;
1343   }
1344   void Post(const parser::OmpEndLoopDirective &) {
1345     messageHandler().set_currStmtSource(std::nullopt);
1346   }
1347 
1348   bool Pre(const parser::OpenMPSectionsConstruct &) {
1349     PushScope(Scope::Kind::Block, nullptr);
1350     return true;
1351   }
1352   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1353   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1354     AddOmpSourceRange(x.source);
1355     return true;
1356   }
1357   void Post(const parser::OmpBeginSectionsDirective &) {
1358     messageHandler().set_currStmtSource(std::nullopt);
1359   }
1360   bool Pre(const parser::OmpEndSectionsDirective &x) {
1361     AddOmpSourceRange(x.source);
1362     return true;
1363   }
1364   void Post(const parser::OmpEndSectionsDirective &) {
1365     messageHandler().set_currStmtSource(std::nullopt);
1366   }
1367 };
1368 
1369 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1370   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1371   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1372   switch (beginDir.v) {
1373   case llvm::omp::Directive::OMPD_target_data:
1374   case llvm::omp::Directive::OMPD_master:
1375   case llvm::omp::Directive::OMPD_ordered:
1376   case llvm::omp::Directive::OMPD_taskgroup:
1377     return false;
1378   default:
1379     return true;
1380   }
1381 }
1382 
1383 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1384   messageHandler().set_currStmtSource(source);
1385   currScope().AddSourceRange(source);
1386 }
1387 
1388 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1389   if (NeedsScope(x)) {
1390     PushScope(Scope::Kind::Block, nullptr);
1391   }
1392   return true;
1393 }
1394 
1395 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1396   if (NeedsScope(x)) {
1397     PopScope();
1398   }
1399 }
1400 
1401 // Walk the parse tree and resolve names to symbols.
1402 class ResolveNamesVisitor : public virtual ScopeHandler,
1403                             public ModuleVisitor,
1404                             public SubprogramVisitor,
1405                             public ConstructVisitor,
1406                             public OmpVisitor,
1407                             public AccVisitor {
1408 public:
1409   using AccVisitor::Post;
1410   using AccVisitor::Pre;
1411   using ArraySpecVisitor::Post;
1412   using ConstructVisitor::Post;
1413   using ConstructVisitor::Pre;
1414   using DeclarationVisitor::Post;
1415   using DeclarationVisitor::Pre;
1416   using ImplicitRulesVisitor::Post;
1417   using ImplicitRulesVisitor::Pre;
1418   using InterfaceVisitor::Post;
1419   using InterfaceVisitor::Pre;
1420   using ModuleVisitor::Post;
1421   using ModuleVisitor::Pre;
1422   using OmpVisitor::Post;
1423   using OmpVisitor::Pre;
1424   using ScopeHandler::Post;
1425   using ScopeHandler::Pre;
1426   using SubprogramVisitor::Post;
1427   using SubprogramVisitor::Pre;
1428 
1429   ResolveNamesVisitor(
1430       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1431       : BaseVisitor{context, *this, rules}, topScope_{top} {
1432     PushScope(top);
1433   }
1434 
1435   Scope &topScope() const { return topScope_; }
1436 
1437   // Default action for a parse tree node is to visit children.
1438   template <typename T> bool Pre(const T &) { return true; }
1439   template <typename T> void Post(const T &) {}
1440 
1441   bool Pre(const parser::SpecificationPart &);
1442   void Post(const parser::Program &);
1443   bool Pre(const parser::ImplicitStmt &);
1444   void Post(const parser::PointerObject &);
1445   void Post(const parser::AllocateObject &);
1446   bool Pre(const parser::PointerAssignmentStmt &);
1447   void Post(const parser::Designator &);
1448   template <typename A, typename B>
1449   void Post(const parser::LoopBounds<A, B> &x) {
1450     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1451   }
1452   void Post(const parser::ProcComponentRef &);
1453   bool Pre(const parser::FunctionReference &);
1454   bool Pre(const parser::CallStmt &);
1455   bool Pre(const parser::ImportStmt &);
1456   void Post(const parser::TypeGuardStmt &);
1457   bool Pre(const parser::StmtFunctionStmt &);
1458   bool Pre(const parser::DefinedOpName &);
1459   bool Pre(const parser::ProgramUnit &);
1460   void Post(const parser::AssignStmt &);
1461   void Post(const parser::AssignedGotoStmt &);
1462 
1463   // These nodes should never be reached: they are handled in ProgramUnit
1464   bool Pre(const parser::MainProgram &) {
1465     llvm_unreachable("This node is handled in ProgramUnit");
1466   }
1467   bool Pre(const parser::FunctionSubprogram &) {
1468     llvm_unreachable("This node is handled in ProgramUnit");
1469   }
1470   bool Pre(const parser::SubroutineSubprogram &) {
1471     llvm_unreachable("This node is handled in ProgramUnit");
1472   }
1473   bool Pre(const parser::SeparateModuleSubprogram &) {
1474     llvm_unreachable("This node is handled in ProgramUnit");
1475   }
1476   bool Pre(const parser::Module &) {
1477     llvm_unreachable("This node is handled in ProgramUnit");
1478   }
1479   bool Pre(const parser::Submodule &) {
1480     llvm_unreachable("This node is handled in ProgramUnit");
1481   }
1482   bool Pre(const parser::BlockData &) {
1483     llvm_unreachable("This node is handled in ProgramUnit");
1484   }
1485 
1486   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1487 
1488   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1489 
1490 private:
1491   // Kind of procedure we are expecting to see in a ProcedureDesignator
1492   std::optional<Symbol::Flag> expectedProcFlag_;
1493   std::optional<SourceName> prevImportStmt_;
1494   Scope &topScope_;
1495 
1496   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1497   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1498   void CreateGeneric(const parser::GenericSpec &);
1499   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1500   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1501   void CheckImports();
1502   void CheckImport(const SourceName &, const SourceName &);
1503   void HandleCall(Symbol::Flag, const parser::Call &);
1504   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1505   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1506   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1507   void ResolveSpecificationParts(ProgramTree &);
1508   void AddSubpNames(ProgramTree &);
1509   bool BeginScopeForNode(const ProgramTree &);
1510   void EndScopeForNode(const ProgramTree &);
1511   void FinishSpecificationParts(const ProgramTree &);
1512   void FinishDerivedTypeInstantiation(Scope &);
1513   void ResolveExecutionParts(const ProgramTree &);
1514 };
1515 
1516 // ImplicitRules implementation
1517 
1518 bool ImplicitRules::isImplicitNoneType() const {
1519   if (isImplicitNoneType_) {
1520     return true;
1521   } else if (map_.empty() && inheritFromParent_) {
1522     return parent_->isImplicitNoneType();
1523   } else {
1524     return false; // default if not specified
1525   }
1526 }
1527 
1528 bool ImplicitRules::isImplicitNoneExternal() const {
1529   if (isImplicitNoneExternal_) {
1530     return true;
1531   } else if (inheritFromParent_) {
1532     return parent_->isImplicitNoneExternal();
1533   } else {
1534     return false; // default if not specified
1535   }
1536 }
1537 
1538 const DeclTypeSpec *ImplicitRules::GetType(
1539     SourceName name, bool respectImplicitNoneType) const {
1540   char ch{name.begin()[0]};
1541   if (isImplicitNoneType_ && respectImplicitNoneType) {
1542     return nullptr;
1543   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1544     return &*it->second;
1545   } else if (inheritFromParent_) {
1546     return parent_->GetType(name, respectImplicitNoneType);
1547   } else if (ch >= 'i' && ch <= 'n') {
1548     return &context_.MakeNumericType(TypeCategory::Integer);
1549   } else if (ch >= 'a' && ch <= 'z') {
1550     return &context_.MakeNumericType(TypeCategory::Real);
1551   } else {
1552     return nullptr;
1553   }
1554 }
1555 
1556 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1557     parser::Location fromLetter, parser::Location toLetter) {
1558   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1559     auto res{map_.emplace(ch, type)};
1560     if (!res.second) {
1561       context_.Say(parser::CharBlock{fromLetter},
1562           "More than one implicit type specified for '%c'"_err_en_US, ch);
1563     }
1564     if (ch == *toLetter) {
1565       break;
1566     }
1567   }
1568 }
1569 
1570 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1571 // Return '\0' for the char after 'z'.
1572 char ImplicitRules::Incr(char ch) {
1573   switch (ch) {
1574   case 'i':
1575     return 'j';
1576   case 'r':
1577     return 's';
1578   case 'z':
1579     return '\0';
1580   default:
1581     return ch + 1;
1582   }
1583 }
1584 
1585 llvm::raw_ostream &operator<<(
1586     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1587   o << "ImplicitRules:\n";
1588   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1589     ShowImplicitRule(o, implicitRules, ch);
1590   }
1591   ShowImplicitRule(o, implicitRules, '_');
1592   ShowImplicitRule(o, implicitRules, '$');
1593   ShowImplicitRule(o, implicitRules, '@');
1594   return o;
1595 }
1596 void ShowImplicitRule(
1597     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1598   auto it{implicitRules.map_.find(ch)};
1599   if (it != implicitRules.map_.end()) {
1600     o << "  " << ch << ": " << *it->second << '\n';
1601   }
1602 }
1603 
1604 template <typename T> void BaseVisitor::Walk(const T &x) {
1605   parser::Walk(x, *this_);
1606 }
1607 
1608 void BaseVisitor::MakePlaceholder(
1609     const parser::Name &name, MiscDetails::Kind kind) {
1610   if (!name.symbol) {
1611     name.symbol = &context_->globalScope().MakeSymbol(
1612         name.source, Attrs{}, MiscDetails{kind});
1613   }
1614 }
1615 
1616 // AttrsVisitor implementation
1617 
1618 bool AttrsVisitor::BeginAttrs() {
1619   CHECK(!attrs_);
1620   attrs_ = std::make_optional<Attrs>();
1621   return true;
1622 }
1623 Attrs AttrsVisitor::GetAttrs() {
1624   CHECK(attrs_);
1625   return *attrs_;
1626 }
1627 Attrs AttrsVisitor::EndAttrs() {
1628   Attrs result{GetAttrs()};
1629   attrs_.reset();
1630   passName_ = std::nullopt;
1631   bindName_.reset();
1632   return result;
1633 }
1634 
1635 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1636   if (!passName_) {
1637     return false;
1638   }
1639   common::visit(common::visitors{
1640                     [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1641                     [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1642                     [](auto &) { common::die("unexpected pass name"); },
1643                 },
1644       symbol.details());
1645   return true;
1646 }
1647 
1648 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1649   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1650     return;
1651   }
1652   std::optional<std::string> label{
1653       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1654   // 18.9.2(2): discard leading and trailing blanks, ignore if all blank
1655   if (label) {
1656     auto first{label->find_first_not_of(" ")};
1657     if (first == std::string::npos) {
1658       // Empty NAME= means no binding at all (18.10.2p2)
1659       Say(currStmtSource().value(), "Blank binding label ignored"_warn_en_US);
1660       return;
1661     }
1662     auto last{label->find_last_not_of(" ")};
1663     label = label->substr(first, last - first + 1);
1664   } else {
1665     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1666   }
1667   symbol.SetBindName(std::move(*label));
1668 }
1669 
1670 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1671   CHECK(attrs_);
1672   if (CheckAndSet(Attr::BIND_C)) {
1673     if (x.v) {
1674       bindName_ = EvaluateExpr(*x.v);
1675     }
1676   }
1677 }
1678 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1679   CHECK(attrs_);
1680   CheckAndSet(IntentSpecToAttr(x));
1681   return false;
1682 }
1683 bool AttrsVisitor::Pre(const parser::Pass &x) {
1684   if (CheckAndSet(Attr::PASS)) {
1685     if (x.v) {
1686       passName_ = x.v->source;
1687       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1688     }
1689   }
1690   return false;
1691 }
1692 
1693 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1694 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1695   if (attrs_->test(attrName)) {
1696     Say(currStmtSource().value(),
1697         "Attribute '%s' cannot be used more than once"_warn_en_US,
1698         AttrToString(attrName));
1699     return true;
1700   }
1701   return false;
1702 }
1703 
1704 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1705 // name attributes that cannot be used on the same declaration
1706 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1707   if ((attrName == attr1 && attrs_->test(attr2)) ||
1708       (attrName == attr2 && attrs_->test(attr1))) {
1709     Say(currStmtSource().value(),
1710         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1711         AttrToString(attr1), AttrToString(attr2));
1712     return true;
1713   }
1714   return false;
1715 }
1716 // C759, C1543
1717 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1718   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1719       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1720       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1721       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1722       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1723       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1724       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1725 }
1726 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1727   CHECK(attrs_);
1728   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1729     return false;
1730   }
1731   attrs_->set(attrName);
1732   return true;
1733 }
1734 
1735 // DeclTypeSpecVisitor implementation
1736 
1737 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1738   return state_.declTypeSpec;
1739 }
1740 
1741 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1742   CHECK(!state_.expectDeclTypeSpec);
1743   CHECK(!state_.declTypeSpec);
1744   state_.expectDeclTypeSpec = true;
1745 }
1746 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1747   CHECK(state_.expectDeclTypeSpec);
1748   state_ = {};
1749 }
1750 
1751 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1752     DeclTypeSpec::Category category) {
1753   CHECK(state_.expectDeclTypeSpec);
1754   state_.derived.category = category;
1755 }
1756 
1757 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1758   BeginDeclTypeSpec();
1759   return true;
1760 }
1761 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1762   EndDeclTypeSpec();
1763 }
1764 
1765 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1766   // Record the resolved DeclTypeSpec in the parse tree for use by
1767   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1768   // The grammar ensures that it's an intrinsic or derived type spec,
1769   // not TYPE(*) or CLASS(*) or CLASS(T).
1770   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1771     switch (spec->category()) {
1772     case DeclTypeSpec::Numeric:
1773     case DeclTypeSpec::Logical:
1774     case DeclTypeSpec::Character:
1775       typeSpec.declTypeSpec = spec;
1776       break;
1777     case DeclTypeSpec::TypeDerived:
1778       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1779         CheckForAbstractType(derived->typeSymbol()); // C703
1780         typeSpec.declTypeSpec = spec;
1781       }
1782       break;
1783     default:
1784       CRASH_NO_CASE;
1785     }
1786   }
1787 }
1788 
1789 void DeclTypeSpecVisitor::Post(
1790     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1791   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1792 }
1793 void DeclTypeSpecVisitor::Post(
1794     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1795   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1796 }
1797 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1798   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1799 }
1800 
1801 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1802   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1803     Say("ABSTRACT derived type may not be used here"_err_en_US);
1804   }
1805 }
1806 
1807 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1808   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1809 }
1810 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1811   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1812 }
1813 
1814 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1815 // and save it in state_.declTypeSpec.
1816 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1817   CHECK(state_.expectDeclTypeSpec);
1818   CHECK(!state_.declTypeSpec);
1819   state_.declTypeSpec = &declTypeSpec;
1820 }
1821 
1822 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1823     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1824   return AnalyzeKindSelector(context(), category, kind);
1825 }
1826 
1827 // MessageHandler implementation
1828 
1829 Message &MessageHandler::Say(MessageFixedText &&msg) {
1830   return context_->Say(currStmtSource().value(), std::move(msg));
1831 }
1832 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1833   return context_->Say(currStmtSource().value(), std::move(msg));
1834 }
1835 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1836   return Say(name, std::move(msg), name);
1837 }
1838 
1839 // ImplicitRulesVisitor implementation
1840 
1841 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1842   prevParameterStmt_ = currStmtSource();
1843 }
1844 
1845 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1846   bool result{
1847       common::visit(common::visitors{
1848                         [&](const std::list<ImplicitNoneNameSpec> &y) {
1849                           return HandleImplicitNone(y);
1850                         },
1851                         [&](const std::list<parser::ImplicitSpec> &) {
1852                           if (prevImplicitNoneType_) {
1853                             Say("IMPLICIT statement after IMPLICIT NONE or "
1854                                 "IMPLICIT NONE(TYPE) statement"_err_en_US);
1855                             return false;
1856                           }
1857                           implicitRules_->set_isImplicitNoneType(false);
1858                           return true;
1859                         },
1860                     },
1861           x.u)};
1862   prevImplicit_ = currStmtSource();
1863   return result;
1864 }
1865 
1866 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1867   auto loLoc{std::get<parser::Location>(x.t)};
1868   auto hiLoc{loLoc};
1869   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1870     hiLoc = *hiLocOpt;
1871     if (*hiLoc < *loLoc) {
1872       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1873           std::string(hiLoc, 1), std::string(loLoc, 1));
1874       return false;
1875     }
1876   }
1877   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1878   return false;
1879 }
1880 
1881 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1882   BeginDeclTypeSpec();
1883   set_allowForwardReferenceToDerivedType(true);
1884   return true;
1885 }
1886 
1887 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1888   EndDeclTypeSpec();
1889 }
1890 
1891 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1892   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1893   prevImplicit_ = std::nullopt;
1894   prevImplicitNone_ = std::nullopt;
1895   prevImplicitNoneType_ = std::nullopt;
1896   prevParameterStmt_ = std::nullopt;
1897 }
1898 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1899   // find or create implicit rules for this scope
1900   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1901   SetScope(scope);
1902 }
1903 
1904 // TODO: for all of these errors, reference previous statement too
1905 bool ImplicitRulesVisitor::HandleImplicitNone(
1906     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1907   if (prevImplicitNone_) {
1908     Say("More than one IMPLICIT NONE statement"_err_en_US);
1909     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1910     return false;
1911   }
1912   if (prevParameterStmt_) {
1913     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1914     return false;
1915   }
1916   prevImplicitNone_ = currStmtSource();
1917   bool implicitNoneTypeNever{
1918       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1919   if (nameSpecs.empty()) {
1920     if (!implicitNoneTypeNever) {
1921       prevImplicitNoneType_ = currStmtSource();
1922       implicitRules_->set_isImplicitNoneType(true);
1923       if (prevImplicit_) {
1924         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1925         return false;
1926       }
1927     }
1928   } else {
1929     int sawType{0};
1930     int sawExternal{0};
1931     for (const auto noneSpec : nameSpecs) {
1932       switch (noneSpec) {
1933       case ImplicitNoneNameSpec::External:
1934         implicitRules_->set_isImplicitNoneExternal(true);
1935         ++sawExternal;
1936         break;
1937       case ImplicitNoneNameSpec::Type:
1938         if (!implicitNoneTypeNever) {
1939           prevImplicitNoneType_ = currStmtSource();
1940           implicitRules_->set_isImplicitNoneType(true);
1941           if (prevImplicit_) {
1942             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1943             return false;
1944           }
1945           ++sawType;
1946         }
1947         break;
1948       }
1949     }
1950     if (sawType > 1) {
1951       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1952       return false;
1953     }
1954     if (sawExternal > 1) {
1955       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1956       return false;
1957     }
1958   }
1959   return true;
1960 }
1961 
1962 // ArraySpecVisitor implementation
1963 
1964 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1965   CHECK(arraySpec_.empty());
1966   arraySpec_ = AnalyzeArraySpec(context(), x);
1967 }
1968 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1969   CHECK(arraySpec_.empty());
1970   arraySpec_ = AnalyzeArraySpec(context(), x);
1971 }
1972 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1973   CHECK(coarraySpec_.empty());
1974   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1975 }
1976 
1977 const ArraySpec &ArraySpecVisitor::arraySpec() {
1978   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
1979 }
1980 const ArraySpec &ArraySpecVisitor::coarraySpec() {
1981   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
1982 }
1983 void ArraySpecVisitor::BeginArraySpec() {
1984   CHECK(arraySpec_.empty());
1985   CHECK(coarraySpec_.empty());
1986   CHECK(attrArraySpec_.empty());
1987   CHECK(attrCoarraySpec_.empty());
1988 }
1989 void ArraySpecVisitor::EndArraySpec() {
1990   CHECK(arraySpec_.empty());
1991   CHECK(coarraySpec_.empty());
1992   attrArraySpec_.clear();
1993   attrCoarraySpec_.clear();
1994 }
1995 void ArraySpecVisitor::PostAttrSpec() {
1996   // Save dimension/codimension from attrs so we can process array/coarray-spec
1997   // on the entity-decl
1998   if (!arraySpec_.empty()) {
1999     if (attrArraySpec_.empty()) {
2000       attrArraySpec_ = arraySpec_;
2001       arraySpec_.clear();
2002     } else {
2003       Say(currStmtSource().value(),
2004           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
2005     }
2006   }
2007   if (!coarraySpec_.empty()) {
2008     if (attrCoarraySpec_.empty()) {
2009       attrCoarraySpec_ = coarraySpec_;
2010       coarraySpec_.clear();
2011     } else {
2012       Say(currStmtSource().value(),
2013           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
2014     }
2015   }
2016 }
2017 
2018 // FuncResultStack implementation
2019 
2020 FuncResultStack::~FuncResultStack() { CHECK(stack_.empty()); }
2021 
2022 void FuncResultStack::CompleteFunctionResultType() {
2023   // If the function has a type in the prefix, process it now.
2024   if (IsFunction(scopeHandler_.currScope())) {
2025     FuncInfo &info{DEREF(Top())};
2026     if (info.parsedType) {
2027       scopeHandler_.messageHandler().set_currStmtSource(info.source);
2028       if (const auto *type{
2029               scopeHandler_.ProcessTypeSpec(*info.parsedType, true)}) {
2030         if (!scopeHandler_.context().HasError(info.resultSymbol)) {
2031           info.resultSymbol->SetType(*type);
2032         }
2033       }
2034       info.parsedType = nullptr;
2035     }
2036   }
2037 }
2038 
2039 // Called from ConvertTo{Object/Proc}Entity to cope with any appearance
2040 // of the function result in a specification expression.
2041 void FuncResultStack::CompleteTypeIfFunctionResult(Symbol &symbol) {
2042   if (FuncInfo * info{Top()}) {
2043     if (info->resultSymbol == &symbol) {
2044       CompleteFunctionResultType();
2045     }
2046   }
2047 }
2048 
2049 // ScopeHandler implementation
2050 
2051 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
2052   SayAlreadyDeclared(name.source, prev);
2053 }
2054 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
2055   if (context().HasError(prev)) {
2056     // don't report another error about prev
2057   } else {
2058     if (const auto *details{prev.detailsIf<UseDetails>()}) {
2059       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
2060           .Attach(details->location(),
2061               "It is use-associated with '%s' in module '%s'"_en_US,
2062               details->symbol().name(), GetUsedModule(*details).name());
2063     } else {
2064       SayAlreadyDeclared(name, prev.name());
2065     }
2066     context().SetError(prev);
2067   }
2068 }
2069 void ScopeHandler::SayAlreadyDeclared(
2070     const SourceName &name1, const SourceName &name2) {
2071   if (name1.begin() < name2.begin()) {
2072     SayAlreadyDeclared(name2, name1);
2073   } else {
2074     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
2075         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
2076   }
2077 }
2078 
2079 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
2080     MessageFixedText &&msg1, Message &&msg2) {
2081   Say(name, std::move(msg1), symbol.name()).Attach(std::move(msg2));
2082   context().SetError(symbol, msg1.isFatal());
2083 }
2084 
2085 void ScopeHandler::SayWithDecl(
2086     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
2087   Say(name, std::move(msg), symbol.name())
2088       .Attach(Message{name.source,
2089           symbol.test(Symbol::Flag::Implicit)
2090               ? "Implicit declaration of '%s'"_en_US
2091               : "Declaration of '%s'"_en_US,
2092           name.source});
2093   context().SetError(symbol, msg.isFatal());
2094 }
2095 
2096 void ScopeHandler::SayLocalMustBeVariable(
2097     const parser::Name &name, Symbol &symbol) {
2098   SayWithDecl(name, symbol,
2099       "The name '%s' must be a variable to appear"
2100       " in a locality-spec"_err_en_US);
2101 }
2102 
2103 void ScopeHandler::SayDerivedType(
2104     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2105   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2106   Say(name, std::move(msg), name, typeSymbol.name())
2107       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2108           typeSymbol.name());
2109 }
2110 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2111     const SourceName &name2, MessageFixedText &&msg2) {
2112   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2113 }
2114 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2115     Symbol &symbol, MessageFixedText &&msg2) {
2116   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2117   context().SetError(symbol, msg1.isFatal());
2118 }
2119 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2120     Symbol &symbol, MessageFixedText &&msg2) {
2121   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2122   context().SetError(symbol, msg1.isFatal());
2123 }
2124 
2125 // This is essentially GetProgramUnitContaining(), but it can return
2126 // a mutable Scope &, it ignores statement functions, and it fails
2127 // gracefully for error recovery (returning the original Scope).
2128 template <typename T> static T &GetInclusiveScope(T &scope) {
2129   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2130     switch (s->kind()) {
2131     case Scope::Kind::Module:
2132     case Scope::Kind::MainProgram:
2133     case Scope::Kind::Subprogram:
2134     case Scope::Kind::BlockData:
2135       if (!s->IsStmtFunction()) {
2136         return *s;
2137       }
2138       break;
2139     default:;
2140     }
2141   }
2142   return scope;
2143 }
2144 
2145 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2146 
2147 Scope *ScopeHandler::GetHostProcedure() {
2148   Scope &parent{InclusiveScope().parent()};
2149   switch (parent.kind()) {
2150   case Scope::Kind::Subprogram:
2151     return &parent;
2152   case Scope::Kind::MainProgram:
2153     return &parent;
2154   default:
2155     return nullptr;
2156   }
2157 }
2158 
2159 Scope &ScopeHandler::NonDerivedTypeScope() {
2160   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2161 }
2162 
2163 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2164   PushScope(currScope().MakeScope(kind, symbol));
2165 }
2166 void ScopeHandler::PushScope(Scope &scope) {
2167   currScope_ = &scope;
2168   auto kind{currScope_->kind()};
2169   if (kind != Scope::Kind::Block) {
2170     BeginScope(scope);
2171   }
2172   // The name of a module or submodule cannot be "used" in its scope,
2173   // as we read 19.3.1(2), so we allow the name to be used as a local
2174   // identifier in the module or submodule too.  Same with programs
2175   // (14.1(3)) and BLOCK DATA.
2176   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2177       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2178     if (auto *symbol{scope.symbol()}) {
2179       // Create a dummy symbol so we can't create another one with the same
2180       // name. It might already be there if we previously pushed the scope.
2181       SourceName name{symbol->name()};
2182       if (!FindInScope(scope, name)) {
2183         auto &newSymbol{MakeSymbol(name)};
2184         if (kind == Scope::Kind::Subprogram) {
2185           // Allow for recursive references.  If this symbol is a function
2186           // without an explicit RESULT(), this new symbol will be discarded
2187           // and replaced with an object of the same name.
2188           newSymbol.set_details(HostAssocDetails{*symbol});
2189         } else {
2190           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2191         }
2192       }
2193     }
2194   }
2195 }
2196 void ScopeHandler::PopScope() {
2197   // Entities that are not yet classified as objects or procedures are now
2198   // assumed to be objects.
2199   // TODO: Statement functions
2200   for (auto &pair : currScope()) {
2201     ConvertToObjectEntity(*pair.second);
2202   }
2203   // If popping back into a global scope, pop back to the main global scope.
2204   SetScope(currScope_->parent().IsGlobal() ? context().globalScope()
2205                                            : currScope_->parent());
2206 }
2207 void ScopeHandler::SetScope(Scope &scope) {
2208   currScope_ = &scope;
2209   ImplicitRulesVisitor::SetScope(InclusiveScope());
2210 }
2211 
2212 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2213   return FindSymbol(currScope(), name);
2214 }
2215 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2216   if (scope.IsDerivedType()) {
2217     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2218       if (!symbol->has<ProcBindingDetails>() &&
2219           !symbol->test(Symbol::Flag::ParentComp)) {
2220         return Resolve(name, symbol);
2221       }
2222     }
2223     return FindSymbol(scope.parent(), name);
2224   } else {
2225     // In EQUIVALENCE statements only resolve names in the local scope, see
2226     // 19.5.1.4, paragraph 2, item (10)
2227     return Resolve(name,
2228         inEquivalenceStmt_ ? FindInScope(scope, name)
2229                            : scope.FindSymbol(name.source));
2230   }
2231 }
2232 
2233 Symbol &ScopeHandler::MakeSymbol(
2234     Scope &scope, const SourceName &name, Attrs attrs) {
2235   if (Symbol * symbol{FindInScope(scope, name)}) {
2236     symbol->attrs() |= attrs;
2237     return *symbol;
2238   } else {
2239     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2240     CHECK(pair.second); // name was not found, so must be able to add
2241     return *pair.first->second;
2242   }
2243 }
2244 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2245   return MakeSymbol(currScope(), name, attrs);
2246 }
2247 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2248   return Resolve(name, MakeSymbol(name.source, attrs));
2249 }
2250 Symbol &ScopeHandler::MakeHostAssocSymbol(
2251     const parser::Name &name, const Symbol &hostSymbol) {
2252   Symbol &symbol{*NonDerivedTypeScope()
2253                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2254                       .first->second};
2255   name.symbol = &symbol;
2256   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2257   symbol.flags() = hostSymbol.flags();
2258   return symbol;
2259 }
2260 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2261   CHECK(!FindInScope(name));
2262   return MakeSymbol(currScope(), name, symbol.attrs());
2263 }
2264 
2265 // Look for name only in scope, not in enclosing scopes.
2266 Symbol *ScopeHandler::FindInScope(
2267     const Scope &scope, const parser::Name &name) {
2268   return Resolve(name, FindInScope(scope, name.source));
2269 }
2270 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2271   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2272   for (const std::string &n : GetAllNames(context(), name)) {
2273     auto it{scope.find(SourceName{n})};
2274     if (it != scope.end()) {
2275       return &*it->second;
2276     }
2277   }
2278   return nullptr;
2279 }
2280 
2281 // Find a component or type parameter by name in a derived type or its parents.
2282 Symbol *ScopeHandler::FindInTypeOrParents(
2283     const Scope &scope, const parser::Name &name) {
2284   return Resolve(name, scope.FindComponent(name.source));
2285 }
2286 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2287   return FindInTypeOrParents(currScope(), name);
2288 }
2289 
2290 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2291   currScope().erase(name.source);
2292   name.symbol = nullptr;
2293 }
2294 
2295 static bool NeedsType(const Symbol &symbol) {
2296   return !symbol.GetType() &&
2297       common::visit(common::visitors{
2298                         [](const EntityDetails &) { return true; },
2299                         [](const ObjectEntityDetails &) { return true; },
2300                         [](const AssocEntityDetails &) { return true; },
2301                         [&](const ProcEntityDetails &p) {
2302                           return symbol.test(Symbol::Flag::Function) &&
2303                               !symbol.attrs().test(Attr::INTRINSIC) &&
2304                               !p.interface().type() && !p.interface().symbol();
2305                         },
2306                         [](const auto &) { return false; },
2307                     },
2308           symbol.details());
2309 }
2310 
2311 void ScopeHandler::ApplyImplicitRules(
2312     Symbol &symbol, bool allowForwardReference) {
2313   funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2314   if (context().HasError(symbol) || !NeedsType(symbol)) {
2315     return;
2316   }
2317   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2318     symbol.set(Symbol::Flag::Implicit);
2319     symbol.SetType(*type);
2320     return;
2321   }
2322   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2323     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2324     if (symbol.test(Symbol::Flag::Function)) {
2325       functionOrSubroutineFlag = Symbol::Flag::Function;
2326     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2327       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2328     }
2329     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2330       // type will be determined in expression semantics
2331       AcquireIntrinsicProcedureFlags(symbol);
2332       return;
2333     }
2334   }
2335   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2336     return;
2337   }
2338   if (!context().HasError(symbol)) {
2339     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2340     context().SetError(symbol);
2341   }
2342 }
2343 
2344 // Extension: Allow forward references to scalar integer dummy arguments
2345 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2346 // what would otherwise have been their implicit type is default INTEGER.
2347 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2348   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2349       symbol.Rank() != 0 ||
2350       !context().languageFeatures().IsEnabled(
2351           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2352     return false;
2353   }
2354   const DeclTypeSpec *type{
2355       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2356   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2357     return false;
2358   }
2359   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2360   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2361     return false;
2362   }
2363   if (!ConvertToObjectEntity(symbol)) {
2364     return false;
2365   }
2366   // TODO: check no INTENT(OUT)?
2367   if (context().languageFeatures().ShouldWarn(
2368           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2369     Say(symbol.name(),
2370         "Dummy argument '%s' was used without being explicitly typed"_warn_en_US,
2371         symbol.name());
2372   }
2373   symbol.set(Symbol::Flag::Implicit);
2374   symbol.SetType(*type);
2375   return true;
2376 }
2377 
2378 // Ensure that the symbol for an intrinsic procedure is marked with
2379 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2380 // appropriate.
2381 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2382   symbol.attrs().set(Attr::INTRINSIC);
2383   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2384   case evaluate::IntrinsicClass::elementalFunction:
2385   case evaluate::IntrinsicClass::elementalSubroutine:
2386     symbol.attrs().set(Attr::ELEMENTAL);
2387     symbol.attrs().set(Attr::PURE);
2388     break;
2389   case evaluate::IntrinsicClass::impureSubroutine:
2390     break;
2391   default:
2392     symbol.attrs().set(Attr::PURE);
2393   }
2394 }
2395 
2396 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2397     Symbol &symbol, bool respectImplicitNoneType) {
2398   const Scope *scope{&symbol.owner()};
2399   if (scope->IsGlobal()) {
2400     scope = &currScope();
2401   }
2402   scope = &GetInclusiveScope(*scope);
2403   const auto *type{implicitRulesMap_->at(scope).GetType(
2404       symbol.name(), respectImplicitNoneType)};
2405   if (type) {
2406     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2407       // Resolve any forward-referenced derived type; a quick no-op else.
2408       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2409       instantiatable.Instantiate(currScope());
2410     }
2411   }
2412   return type;
2413 }
2414 
2415 // Convert symbol to be a ObjectEntity or return false if it can't be.
2416 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2417   if (symbol.has<ObjectEntityDetails>()) {
2418     // nothing to do
2419   } else if (symbol.has<UnknownDetails>()) {
2420     symbol.set_details(ObjectEntityDetails{});
2421   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2422     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2423     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2424   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2425     return useDetails->symbol().has<ObjectEntityDetails>();
2426   } else {
2427     return false;
2428   }
2429   return true;
2430 }
2431 // Convert symbol to be a ProcEntity or return false if it can't be.
2432 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2433   if (symbol.has<ProcEntityDetails>()) {
2434     // nothing to do
2435   } else if (symbol.has<UnknownDetails>()) {
2436     symbol.set_details(ProcEntityDetails{});
2437   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2438     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2439     symbol.set_details(ProcEntityDetails{std::move(*details)});
2440     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2441       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2442       symbol.set(Symbol::Flag::Function);
2443     }
2444   } else {
2445     return false;
2446   }
2447   return true;
2448 }
2449 
2450 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2451     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2452   KindExpr value{GetKindParamExpr(category, kind)};
2453   if (auto known{evaluate::ToInt64(value)}) {
2454     return context().MakeNumericType(category, static_cast<int>(*known));
2455   } else {
2456     return currScope_->MakeNumericType(category, std::move(value));
2457   }
2458 }
2459 
2460 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2461     const std::optional<parser::KindSelector> &kind) {
2462   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2463   if (auto known{evaluate::ToInt64(value)}) {
2464     return context().MakeLogicalType(static_cast<int>(*known));
2465   } else {
2466     return currScope_->MakeLogicalType(std::move(value));
2467   }
2468 }
2469 
2470 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2471   if (inSpecificationPart_ && name.symbol) {
2472     auto kind{currScope().kind()};
2473     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2474         kind == Scope::Kind::Block) {
2475       bool isHostAssociated{&name.symbol->owner() == &currScope()
2476               ? name.symbol->has<HostAssocDetails>()
2477               : name.symbol->owner().Contains(currScope())};
2478       if (isHostAssociated) {
2479         specPartState_.forwardRefs.insert(name.source);
2480       }
2481     }
2482   }
2483 }
2484 
2485 std::optional<SourceName> ScopeHandler::HadForwardRef(
2486     const Symbol &symbol) const {
2487   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2488   if (iter != specPartState_.forwardRefs.end()) {
2489     return *iter;
2490   }
2491   return std::nullopt;
2492 }
2493 
2494 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2495   if (!context().HasError(symbol)) {
2496     if (auto fwdRef{HadForwardRef(symbol)}) {
2497       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2498       if (outer && symbol.has<UseDetails>() &&
2499           &symbol.GetUltimate() == &outer->GetUltimate()) {
2500         // e.g. IMPORT of host's USE association
2501         return false;
2502       }
2503       Say(*fwdRef,
2504           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2505           *fwdRef)
2506           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2507       context().SetError(symbol);
2508       return true;
2509     }
2510     if (IsDummy(symbol) && isImplicitNoneType() &&
2511         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2512       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2513       // ApplyImplicitRules() due to use in a specification expression,
2514       // and no explicit type declaration appeared later.
2515       Say(symbol.name(),
2516           "No explicit type declared for dummy argument '%s'"_err_en_US);
2517       context().SetError(symbol);
2518       return true;
2519     }
2520   }
2521   return false;
2522 }
2523 
2524 void ScopeHandler::MakeExternal(Symbol &symbol) {
2525   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2526     symbol.attrs().set(Attr::EXTERNAL);
2527     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2528       Say(symbol.name(),
2529           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2530           symbol.name());
2531     }
2532   }
2533 }
2534 
2535 // ModuleVisitor implementation
2536 
2537 bool ModuleVisitor::Pre(const parser::Only &x) {
2538   common::visit(common::visitors{
2539                     [&](const Indirection<parser::GenericSpec> &generic) {
2540                       GenericSpecInfo genericSpecInfo{generic.value()};
2541                       AddUseOnly(genericSpecInfo.symbolName());
2542                       AddUse(genericSpecInfo);
2543                     },
2544                     [&](const parser::Name &name) {
2545                       AddUseOnly(name.source);
2546                       Resolve(name, AddUse(name.source, name.source).use);
2547                     },
2548                     [&](const parser::Rename &rename) { Walk(rename); },
2549                 },
2550       x.u);
2551   return false;
2552 }
2553 
2554 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2555   const auto &localName{std::get<0>(x.t)};
2556   const auto &useName{std::get<1>(x.t)};
2557   AddUseRename(useName.source);
2558   SymbolRename rename{AddUse(localName.source, useName.source)};
2559   if (rename.use) {
2560     EraseRenamedSymbol(*rename.use);
2561   }
2562   Resolve(useName, rename.use);
2563   Resolve(localName, rename.local);
2564   return false;
2565 }
2566 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2567   const parser::DefinedOpName &local{std::get<0>(x.t)};
2568   const parser::DefinedOpName &use{std::get<1>(x.t)};
2569   GenericSpecInfo localInfo{local};
2570   GenericSpecInfo useInfo{use};
2571   if (IsIntrinsicOperator(context(), local.v.source)) {
2572     Say(local.v,
2573         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2574   } else if (IsLogicalConstant(context(), local.v.source)) {
2575     Say(local.v,
2576         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2577   } else {
2578     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2579     if (rename.use) {
2580       EraseRenamedSymbol(*rename.use);
2581     }
2582     useInfo.Resolve(rename.use);
2583     localInfo.Resolve(rename.local);
2584   }
2585   return false;
2586 }
2587 
2588 // Set useModuleScope_ to the Scope of the module being used.
2589 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2590   std::optional<bool> isIntrinsic;
2591   if (x.nature) {
2592     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2593     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2594   } else if (currScope().IsModule() && currScope().symbol() &&
2595       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2596     // Intrinsic modules USE only other intrinsic modules
2597     isIntrinsic = true;
2598   }
2599   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2600   if (!useModuleScope_) {
2601     return false;
2602   }
2603   // use the name from this source file
2604   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2605   return true;
2606 }
2607 
2608 void ModuleVisitor::Post(const parser::UseStmt &x) {
2609   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2610     // Not a use-only: collect the names that were used in renames,
2611     // then add a use for each public name that was not renamed.
2612     std::set<SourceName> useNames;
2613     for (const auto &rename : *list) {
2614       common::visit(common::visitors{
2615                         [&](const parser::Rename::Names &names) {
2616                           useNames.insert(std::get<1>(names.t).source);
2617                         },
2618                         [&](const parser::Rename::Operators &ops) {
2619                           useNames.insert(std::get<1>(ops.t).v.source);
2620                         },
2621                     },
2622           rename.u);
2623     }
2624     for (const auto &[name, symbol] : *useModuleScope_) {
2625       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2626           (!symbol->attrs().test(Attr::INTRINSIC) ||
2627               symbol->has<UseDetails>()) &&
2628           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2629         SourceName location{x.moduleName.source};
2630         if (auto *localSymbol{FindInScope(name)}) {
2631           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2632         } else {
2633           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2634         }
2635       }
2636     }
2637   }
2638   useModuleScope_ = nullptr;
2639 }
2640 
2641 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2642     const SourceName &localName, const SourceName &useName) {
2643   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2644 }
2645 
2646 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2647     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2648   if (!useModuleScope_) {
2649     return {}; // error occurred finding module
2650   }
2651   if (!useSymbol) {
2652     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2653         useModuleScope_->GetName().value());
2654     return {};
2655   }
2656   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2657       !FindModuleFileContaining(currScope())) {
2658     // Privacy is not enforced in module files so that generic interfaces
2659     // can be resolved to private specific procedures in specification
2660     // expressions.
2661     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2662         useModuleScope_->GetName().value());
2663     return {};
2664   }
2665   auto &localSymbol{MakeSymbol(localName)};
2666   DoAddUse(useName, localName, localSymbol, *useSymbol);
2667   return {&localSymbol, useSymbol};
2668 }
2669 
2670 // symbol must be either a Use or a Generic formed by merging two uses.
2671 // Convert it to a UseError with this additional location.
2672 static void ConvertToUseError(
2673     Symbol &symbol, const SourceName &location, const Scope &module) {
2674   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2675   if (!useDetails) {
2676     auto &genericDetails{symbol.get<GenericDetails>()};
2677     useDetails = &genericDetails.uses().at(0)->get<UseDetails>();
2678   }
2679   symbol.set_details(
2680       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2681 }
2682 
2683 // If a symbol has previously been USE-associated and did not appear in a USE
2684 // ONLY clause, erase it from the current scope.  This is needed when a name
2685 // appears in a USE rename clause.
2686 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2687   const SourceName &name{useSymbol.name()};
2688   if (const Symbol * symbol{FindInScope(name)}) {
2689     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2690       const Symbol &moduleSymbol{useDetails->symbol()};
2691       if (moduleSymbol.name() == name &&
2692           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2693           !IsUseOnly(name)) {
2694         EraseSymbol(*symbol);
2695       }
2696     }
2697   }
2698 }
2699 
2700 void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
2701     Symbol &localSymbol, const Symbol &useSymbol) {
2702   if (localName != useSymbol.name()) {
2703     EraseRenamedSymbol(useSymbol);
2704   }
2705   if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2706     details->add_occurrence(location, *useModuleScope_);
2707     return;
2708   }
2709 
2710   if (localSymbol.has<UnknownDetails>()) {
2711     localSymbol.set_details(UseDetails{localName, useSymbol});
2712     localSymbol.attrs() =
2713         useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2714     localSymbol.flags() = useSymbol.flags();
2715     return;
2716   }
2717 
2718   Symbol &localUltimate{localSymbol.GetUltimate()};
2719   const Symbol &useUltimate{useSymbol.GetUltimate()};
2720   if (&localUltimate == &useUltimate) {
2721     // use-associating the same symbol again -- ok
2722     return;
2723   }
2724 
2725   auto checkAmbiguousDerivedType{[this, location, localName](
2726                                      const Symbol *t1, const Symbol *t2) {
2727     if (!t1 || !t2) {
2728       return true;
2729     } else {
2730       t1 = &t1->GetUltimate();
2731       t2 = &t2->GetUltimate();
2732       if (&t1 != &t2) {
2733         Say(location,
2734             "Generic interface '%s' has ambiguous derived types from modules '%s' and '%s'"_err_en_US,
2735             localName, t1->owner().GetName().value(),
2736             t2->owner().GetName().value());
2737         return false;
2738       }
2739     }
2740   }};
2741 
2742   auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
2743   const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
2744   auto combine{false};
2745   if (localGeneric) {
2746     if (useGeneric) {
2747       if (!checkAmbiguousDerivedType(
2748               localGeneric->derivedType(), useGeneric->derivedType())) {
2749         return;
2750       }
2751       combine = true;
2752     } else if (useUltimate.has<DerivedTypeDetails>()) {
2753       if (checkAmbiguousDerivedType(
2754               &useUltimate, localGeneric->derivedType())) {
2755         combine = true;
2756       } else {
2757         return;
2758       }
2759     } else if (&useUltimate == &BypassGeneric(localUltimate)) {
2760       return; // nothing to do; used subprogram is local's specific
2761     }
2762   } else if (useGeneric) {
2763     if (localUltimate.has<DerivedTypeDetails>()) {
2764       if (checkAmbiguousDerivedType(
2765               &localUltimate, useGeneric->derivedType())) {
2766         combine = true;
2767       } else {
2768         return;
2769       }
2770     } else if (&localUltimate == &BypassGeneric(useUltimate).GetUltimate()) {
2771       // Local is the specific of the used generic; replace it.
2772       EraseSymbol(localSymbol);
2773       Symbol &newSymbol{MakeSymbol(localName,
2774           useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2775           UseDetails{localName, useUltimate})};
2776       newSymbol.flags() = useSymbol.flags();
2777       return;
2778     }
2779   }
2780   if (!combine) {
2781     if (localSymbol.has<UseDetails>() || localSymbol.has<GenericDetails>()) {
2782       ConvertToUseError(localSymbol, location, *useModuleScope_);
2783     } else {
2784       Say(location,
2785           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2786           localName)
2787           .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2788               localName);
2789     }
2790     return;
2791   }
2792 
2793   // Two items are being use-associated from different modules
2794   // to the same local name.  At least one of them must be a generic,
2795   // and the other one can be a generic or a derived type.
2796   // (It could also have been the specific of the generic, but those
2797   // cases are handled above without needing to make a local copy of the
2798   // generic.)
2799 
2800   if (localGeneric) {
2801     if (localSymbol.has<UseDetails>()) {
2802       // Create a local copy of a previously use-associated generic so that
2803       // it can be locally extended without corrupting the original.
2804       GenericDetails generic;
2805       generic.CopyFrom(*localGeneric);
2806       EraseSymbol(localSymbol);
2807       Symbol &newSymbol{MakeSymbol(
2808           localSymbol.name(), localSymbol.attrs(), std::move(generic))};
2809       newSymbol.flags() = localSymbol.flags();
2810       localGeneric = &newSymbol.get<GenericDetails>();
2811       localGeneric->AddUse(localSymbol);
2812     }
2813     if (useGeneric) {
2814       // Combine two use-associated generics
2815       localSymbol.attrs() =
2816           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2817       localSymbol.flags() = useSymbol.flags();
2818       AddGenericUse(*localGeneric, localName, useUltimate);
2819       localGeneric->CopyFrom(*useGeneric);
2820     } else {
2821       CHECK(useUltimate.has<DerivedTypeDetails>());
2822       localGeneric->set_derivedType(
2823           AddGenericUse(*localGeneric, localName, useUltimate));
2824     }
2825   } else {
2826     CHECK(useGeneric && localUltimate.has<DerivedTypeDetails>());
2827     CHECK(localSymbol.has<UseDetails>());
2828     // Create a local copy of the use-associated generic, then extend it
2829     // with the local derived type.
2830     GenericDetails generic;
2831     generic.CopyFrom(*useGeneric);
2832     EraseSymbol(localSymbol);
2833     Symbol &newSymbol{MakeSymbol(localName,
2834         useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2835         std::move(generic))};
2836     newSymbol.flags() = useUltimate.flags();
2837     auto &newUseGeneric{newSymbol.get<GenericDetails>()};
2838     AddGenericUse(newUseGeneric, localName, useUltimate);
2839     newUseGeneric.AddUse(localSymbol);
2840     newUseGeneric.set_derivedType(localSymbol);
2841   }
2842 }
2843 
2844 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2845   if (useModuleScope_) {
2846     const auto &name{info.symbolName()};
2847     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2848     info.Resolve(rename.use);
2849   }
2850 }
2851 
2852 // Create a UseDetails symbol for this USE and add it to generic
2853 Symbol &ModuleVisitor::AddGenericUse(
2854     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2855   Symbol &newSymbol{
2856       currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol})};
2857   generic.AddUse(newSymbol);
2858   return newSymbol;
2859 }
2860 
2861 // Enforce C1406
2862 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2863     SourceName name, bool isIntrinsic) {
2864   if (isIntrinsic) {
2865     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2866         iter != explicitNonIntrinsicUses_.end()) {
2867       Say(name,
2868           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2869           name)
2870           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2871     }
2872     explicitIntrinsicUses_.insert(name);
2873   } else {
2874     if (auto iter{explicitIntrinsicUses_.find(name)};
2875         iter != explicitIntrinsicUses_.end()) {
2876       Say(name,
2877           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2878           name)
2879           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2880     }
2881     explicitNonIntrinsicUses_.insert(name);
2882   }
2883 }
2884 
2885 bool ModuleVisitor::BeginSubmodule(
2886     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2887   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2888   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2889   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2890   if (!ancestor) {
2891     return false;
2892   }
2893   Scope *parentScope{parentName
2894           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2895           : ancestor};
2896   if (!parentScope) {
2897     return false;
2898   }
2899   PushScope(*parentScope); // submodule is hosted in parent
2900   BeginModule(name, true);
2901   if (!ancestor->AddSubmodule(name.source, currScope())) {
2902     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2903         ancestorName.source, name.source);
2904   }
2905   return true;
2906 }
2907 
2908 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2909   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2910   auto &details{symbol.get<ModuleDetails>()};
2911   PushScope(Scope::Kind::Module, &symbol);
2912   details.set_scope(&currScope());
2913   defaultAccess_ = Attr::PUBLIC;
2914   prevAccessStmt_ = std::nullopt;
2915 }
2916 
2917 // Find a module or submodule by name and return its scope.
2918 // If ancestor is present, look for a submodule of that ancestor module.
2919 // May have to read a .mod file to find it.
2920 // If an error occurs, report it and return nullptr.
2921 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2922     std::optional<bool> isIntrinsic, Scope *ancestor) {
2923   ModFileReader reader{context()};
2924   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2925   if (!scope) {
2926     return nullptr;
2927   }
2928   if (scope->kind() != Scope::Kind::Module) {
2929     Say(name, "'%s' is not a module"_err_en_US);
2930     return nullptr;
2931   }
2932   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2933     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2934   }
2935   Resolve(name, scope->symbol());
2936   return scope;
2937 }
2938 
2939 void ModuleVisitor::ApplyDefaultAccess() {
2940   for (auto &pair : currScope()) {
2941     Symbol &symbol = *pair.second;
2942     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2943       symbol.attrs().set(defaultAccess_);
2944     }
2945   }
2946 }
2947 
2948 // InterfaceVistor implementation
2949 
2950 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2951   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2952   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2953   return BeginAttrs();
2954 }
2955 
2956 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2957 
2958 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2959   genericInfo_.pop();
2960 }
2961 
2962 // Create a symbol in genericSymbol_ for this GenericSpec.
2963 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2964   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
2965     SetGenericSymbol(*symbol);
2966   }
2967   return false;
2968 }
2969 
2970 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2971   if (!isGeneric()) {
2972     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2973     return false;
2974   }
2975   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2976   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2977   AddSpecificProcs(names, kind);
2978   return false;
2979 }
2980 
2981 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2982   genericInfo_.emplace(/*isInterface*/ false);
2983   return true;
2984 }
2985 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2986   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2987     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2988   }
2989   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2990   AddSpecificProcs(names, ProcedureKind::Procedure);
2991   genericInfo_.pop();
2992 }
2993 
2994 bool InterfaceVisitor::inInterfaceBlock() const {
2995   return !genericInfo_.empty() && GetGenericInfo().isInterface;
2996 }
2997 bool InterfaceVisitor::isGeneric() const {
2998   return !genericInfo_.empty() && GetGenericInfo().symbol;
2999 }
3000 bool InterfaceVisitor::isAbstract() const {
3001   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
3002 }
3003 
3004 void InterfaceVisitor::AddSpecificProcs(
3005     const std::list<parser::Name> &names, ProcedureKind kind) {
3006   for (const auto &name : names) {
3007     specificProcs_.emplace(
3008         GetGenericInfo().symbol, std::make_pair(&name, kind));
3009   }
3010 }
3011 
3012 // By now we should have seen all specific procedures referenced by name in
3013 // this generic interface. Resolve those names to symbols.
3014 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
3015   auto &details{generic.get<GenericDetails>()};
3016   UnorderedSymbolSet symbolsSeen;
3017   for (const Symbol &symbol : details.specificProcs()) {
3018     symbolsSeen.insert(symbol.GetUltimate());
3019   }
3020   auto range{specificProcs_.equal_range(&generic)};
3021   for (auto it{range.first}; it != range.second; ++it) {
3022     const parser::Name *name{it->second.first};
3023     auto kind{it->second.second};
3024     const auto *symbol{FindSymbol(*name)};
3025     if (!symbol) {
3026       Say(*name, "Procedure '%s' not found"_err_en_US);
3027       continue;
3028     }
3029     const Symbol &specific{BypassGeneric(*symbol)};
3030     const Symbol &ultimate{specific.GetUltimate()};
3031     if (!ultimate.has<SubprogramDetails>() &&
3032         !ultimate.has<SubprogramNameDetails>()) {
3033       Say(*name, "'%s' is not a subprogram"_err_en_US);
3034       continue;
3035     }
3036     if (kind == ProcedureKind::ModuleProcedure) {
3037       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
3038         if (nd->kind() != SubprogramKind::Module) {
3039           Say(*name, "'%s' is not a module procedure"_err_en_US);
3040         }
3041       } else {
3042         // USE-associated procedure
3043         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
3044         CHECK(sd);
3045         if (ultimate.owner().kind() != Scope::Kind::Module ||
3046             sd->isInterface()) {
3047           Say(*name, "'%s' is not a module procedure"_err_en_US);
3048         }
3049       }
3050     }
3051     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
3052       // When a specific procedure is a USE association, that association
3053       // is saved in the generic's specifics, not its ultimate symbol,
3054       // so that module file output of interfaces can distinguish them.
3055       details.AddSpecificProc(specific, name->source);
3056     } else if (&specific == &ultimate) {
3057       Say(name->source,
3058           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
3059           name->source, MakeOpName(generic.name()));
3060     } else {
3061       Say(name->source,
3062           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
3063           ultimate.name(), ultimate.owner().GetName().value(),
3064           MakeOpName(generic.name()));
3065     }
3066   }
3067   specificProcs_.erase(range.first, range.second);
3068 }
3069 
3070 // Check that the specific procedures are all functions or all subroutines.
3071 // If there is a derived type with the same name they must be functions.
3072 // Set the corresponding flag on generic.
3073 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
3074   ResolveSpecificsInGeneric(generic);
3075   auto &details{generic.get<GenericDetails>()};
3076   if (auto *proc{details.CheckSpecific()}) {
3077     auto msg{
3078         "'%s' may not be the name of both a generic interface and a"
3079         " procedure unless it is a specific procedure of the generic"_err_en_US};
3080     if (proc->name().begin() > generic.name().begin()) {
3081       Say(proc->name(), std::move(msg));
3082     } else {
3083       Say(generic.name(), std::move(msg));
3084     }
3085   }
3086   auto &specifics{details.specificProcs()};
3087   if (specifics.empty()) {
3088     if (details.derivedType()) {
3089       generic.set(Symbol::Flag::Function);
3090     }
3091     return;
3092   }
3093   const Symbol &firstSpecific{specifics.front()};
3094   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
3095   for (const Symbol &specific : specifics) {
3096     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
3097       auto &msg{Say(generic.name(),
3098           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
3099       if (isFunction) {
3100         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
3101         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
3102       } else {
3103         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
3104         msg.Attach(specific.name(), "Function declaration"_en_US);
3105       }
3106     }
3107   }
3108   if (!isFunction && details.derivedType()) {
3109     SayDerivedType(generic.name(),
3110         "Generic interface '%s' may only contain functions due to derived type"
3111         " with same name"_err_en_US,
3112         *details.derivedType()->scope());
3113   }
3114   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
3115 }
3116 
3117 // SubprogramVisitor implementation
3118 
3119 // Return false if it is actually an assignment statement.
3120 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
3121   const auto &name{std::get<parser::Name>(x.t)};
3122   const DeclTypeSpec *resultType{nullptr};
3123   // Look up name: provides return type or tells us if it's an array
3124   if (auto *symbol{FindSymbol(name)}) {
3125     auto *details{symbol->detailsIf<EntityDetails>()};
3126     if (!details) {
3127       badStmtFuncFound_ = true;
3128       return false;
3129     }
3130     // TODO: check that attrs are compatible with stmt func
3131     resultType = details->type();
3132     symbol->details() = UnknownDetails{}; // will be replaced below
3133   }
3134   if (badStmtFuncFound_) {
3135     Say(name, "'%s' has not been declared as an array"_err_en_US);
3136     return true;
3137   }
3138   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
3139   symbol.set(Symbol::Flag::StmtFunction);
3140   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
3141   auto &details{symbol.get<SubprogramDetails>()};
3142   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
3143     ObjectEntityDetails dummyDetails{true};
3144     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
3145       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
3146         if (d->type()) {
3147           dummyDetails.set_type(*d->type());
3148         }
3149       }
3150     }
3151     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
3152     ApplyImplicitRules(dummy);
3153     details.add_dummyArg(dummy);
3154   }
3155   ObjectEntityDetails resultDetails;
3156   if (resultType) {
3157     resultDetails.set_type(*resultType);
3158   }
3159   resultDetails.set_funcResult(true);
3160   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
3161   ApplyImplicitRules(result);
3162   details.set_result(result);
3163   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
3164   Walk(parsedExpr);
3165   // The analysis of the expression that constitutes the body of the
3166   // statement function is deferred to FinishSpecificationPart() so that
3167   // all declarations and implicit typing are complete.
3168   PopScope();
3169   return true;
3170 }
3171 
3172 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3173   if (suffix.resultName) {
3174     if (IsFunction(currScope())) {
3175       if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3176         if (info->inFunctionStmt) {
3177           info->resultName = &suffix.resultName.value();
3178         } else {
3179           // will check the result name in Post(EntryStmt)
3180         }
3181       }
3182     } else {
3183       Message &msg{Say(*suffix.resultName,
3184           "RESULT(%s) may appear only in a function"_err_en_US)};
3185       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3186         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3187       }
3188     }
3189   }
3190   return true;
3191 }
3192 
3193 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3194   // Save this to process after UseStmt and ImplicitPart
3195   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3196     FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3197     if (info.parsedType) { // C1543
3198       Say(currStmtSource().value(),
3199           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3200       return false;
3201     } else {
3202       info.parsedType = parsedType;
3203       info.source = currStmtSource();
3204       return false;
3205     }
3206   } else {
3207     return true;
3208   }
3209 }
3210 
3211 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3212   const auto &name{std::get<parser::Name>(
3213       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3214   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3215 }
3216 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
3217   EndSubprogram();
3218 }
3219 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3220   const auto &name{std::get<parser::Name>(
3221       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3222   return BeginSubprogram(name, Symbol::Flag::Function);
3223 }
3224 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
3225   EndSubprogram();
3226 }
3227 
3228 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
3229   return BeginAttrs();
3230 }
3231 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3232   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3233   CHECK(!info.inFunctionStmt);
3234   info.inFunctionStmt = true;
3235   return BeginAttrs();
3236 }
3237 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3238 
3239 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
3240   const auto &name{std::get<parser::Name>(stmt.t)};
3241   auto &details{PostSubprogramStmt(name)};
3242   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3243     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3244       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3245       details.add_dummyArg(dummy);
3246     } else {
3247       details.add_alternateReturn();
3248     }
3249   }
3250 }
3251 
3252 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3253   const auto &name{std::get<parser::Name>(stmt.t)};
3254   auto &details{PostSubprogramStmt(name)};
3255   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3256     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3257     details.add_dummyArg(dummy);
3258   }
3259   const parser::Name *funcResultName;
3260   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3261   CHECK(info.inFunctionStmt);
3262   info.inFunctionStmt = false;
3263   if (info.resultName && info.resultName->source != name.source) {
3264     // Note that RESULT is ignored if it has the same name as the function.
3265     funcResultName = info.resultName;
3266   } else {
3267     EraseSymbol(name); // was added by PushSubprogramScope
3268     funcResultName = &name;
3269   }
3270   // add function result to function scope
3271   if (details.isFunction()) {
3272     CHECK(context().HasError(currScope().symbol()));
3273   } else {
3274     // add function result to function scope
3275     EntityDetails funcResultDetails;
3276     funcResultDetails.set_funcResult(true);
3277     Symbol &result{MakeSymbol(*funcResultName, std::move(funcResultDetails))};
3278     info.resultSymbol = &result;
3279     details.set_result(result);
3280   }
3281   // C1560.
3282   if (info.resultName && info.resultName->source == name.source) {
3283     Say(info.resultName->source,
3284         "The function name should not appear in RESULT, references to '%s' "
3285         "inside the function will be considered as references to the "
3286         "result only"_warn_en_US,
3287         name.source);
3288     // RESULT name was ignored above, the only side effect from doing so will be
3289     // the inability to make recursive calls. The related parser::Name is still
3290     // resolved to the created function result symbol because every parser::Name
3291     // should be resolved to avoid internal errors.
3292     Resolve(*info.resultName, info.resultSymbol);
3293   }
3294   name.symbol = currScope().symbol(); // must not be function result symbol
3295   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3296   // has a RESULT() suffix.
3297   info.resultName = nullptr;
3298 }
3299 
3300 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3301     const parser::Name &name) {
3302   Symbol &symbol{*currScope().symbol()};
3303   auto &subp{symbol.get<SubprogramDetails>()};
3304   SetBindNameOn(symbol);
3305   CHECK(name.source == symbol.name() ||
3306       (subp.bindName() && symbol.owner().IsGlobal() &&
3307           context().IsTempName(symbol.name().ToString())));
3308   symbol.attrs() |= EndAttrs();
3309   if (symbol.attrs().test(Attr::MODULE)) {
3310     symbol.attrs().set(Attr::EXTERNAL, false);
3311   }
3312   return symbol.get<SubprogramDetails>();
3313 }
3314 
3315 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3316   auto attrs{EndAttrs()}; // needs to be called even if early return
3317   Scope &inclusiveScope{InclusiveScope()};
3318   const Symbol *subprogram{inclusiveScope.symbol()};
3319   if (!subprogram) {
3320     CHECK(context().AnyFatalError());
3321     return;
3322   }
3323   const auto &name{std::get<parser::Name>(stmt.t)};
3324   const parser::Name *resultName{nullptr};
3325   if (const auto &maybeSuffix{
3326           std::get<std::optional<parser::Suffix>>(stmt.t)}) {
3327     resultName = common::GetPtrFromOptional(maybeSuffix->resultName);
3328   }
3329   bool inFunction{IsFunction(currScope())};
3330   if (resultName) { // RESULT(result) is present
3331     if (!inFunction) {
3332       // error was already emitted for the suffix
3333     } else if (resultName->source == subprogram->name()) { // C1574
3334       Say2(resultName->source,
3335           "RESULT(%s) may not have the same name as the function"_err_en_US,
3336           subprogram->name(), "Containing function"_en_US);
3337     } else if (const Symbol *
3338         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
3339       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
3340         if (details->entryScope() == &inclusiveScope) {
3341           Say2(resultName->source,
3342               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3343               symbol->name(), "Conflicting ENTRY"_en_US);
3344         }
3345       }
3346     }
3347     if (Symbol * symbol{FindSymbol(name)}) { // C1570
3348       // When RESULT() appears, ENTRY name can't have been already declared
3349       if (inclusiveScope.Contains(symbol->owner())) {
3350         Say2(name,
3351             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
3352             *symbol, "Previous declaration of '%s'"_en_US);
3353       }
3354     }
3355     if (resultName->source == name.source) {
3356       // ignore RESULT() hereafter when it's the same name as the ENTRY
3357       resultName = nullptr;
3358     }
3359   }
3360   SubprogramDetails entryDetails;
3361   entryDetails.set_entryScope(inclusiveScope);
3362   if (inFunction) {
3363     // Create the entity to hold the function result, if necessary.
3364     Symbol *resultSymbol{nullptr};
3365     auto &effectiveResultName{*(resultName ? resultName : &name)};
3366     resultSymbol = FindInScope(currScope(), effectiveResultName);
3367     if (resultSymbol) { // C1574
3368       common::visit(
3369           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
3370               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
3371               [](ProcEntityDetails &x) { x.set_funcResult(true); },
3372               [&](const auto &) {
3373                 Say2(effectiveResultName.source,
3374                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
3375                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
3376                 context().SetError(*resultSymbol);
3377               }},
3378           resultSymbol->details());
3379     } else if (inExecutionPart_) {
3380       ObjectEntityDetails entity;
3381       entity.set_funcResult(true);
3382       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3383       ApplyImplicitRules(*resultSymbol);
3384     } else {
3385       EntityDetails entity;
3386       entity.set_funcResult(true);
3387       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3388     }
3389     if (!resultName) {
3390       name.symbol = nullptr; // symbol will be used for entry point below
3391     }
3392     entryDetails.set_result(*resultSymbol);
3393   }
3394 
3395   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3396     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3397       Symbol *dummy{FindSymbol(*dummyName)};
3398       if (dummy) {
3399         common::visit(
3400             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3401                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3402                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3403                 [](SubprogramDetails &x) { x.set_isDummy(); },
3404                 [&](const auto &) {
3405                   Say2(dummyName->source,
3406                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3407                       dummy->name(), "Previous declaration of '%s'"_en_US);
3408                 }},
3409             dummy->details());
3410       } else {
3411         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3412         if (inExecutionPart_) {
3413           ApplyImplicitRules(*dummy);
3414         }
3415       }
3416       entryDetails.add_dummyArg(*dummy);
3417     } else {
3418       if (inFunction) { // C1573
3419         Say(name,
3420             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3421         break;
3422       }
3423       entryDetails.add_alternateReturn();
3424     }
3425   }
3426 
3427   Symbol::Flag subpFlag{
3428       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
3429   Scope &outer{inclusiveScope.parent()}; // global or module scope
3430   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3431     attrs.set(Attr::PUBLIC);
3432   }
3433   if (Symbol * extant{FindSymbol(outer, name)}) {
3434     if (!HandlePreviousCalls(name, *extant, subpFlag)) {
3435       if (outer.IsGlobal()) {
3436         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
3437             *extant, "Previous definition of '%s'"_en_US);
3438       } else {
3439         SayAlreadyDeclared(name, *extant);
3440       }
3441       return;
3442     }
3443   }
3444 
3445   Symbol *entrySymbol{&MakeSymbol(outer, name.source, attrs)};
3446   if (auto *generic{entrySymbol->detailsIf<GenericDetails>()}) {
3447     CHECK(generic->specific());
3448     entrySymbol = generic->specific();
3449   }
3450   entrySymbol->set_details(std::move(entryDetails));
3451   SetBindNameOn(*entrySymbol);
3452   entrySymbol->set(subpFlag);
3453   Resolve(name, *entrySymbol);
3454 }
3455 
3456 // A subprogram declared with MODULE PROCEDURE
3457 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3458   auto *symbol{FindSymbol(name)};
3459   if (symbol && symbol->has<SubprogramNameDetails>()) {
3460     symbol = FindSymbol(currScope().parent(), name);
3461   }
3462   if (!IsSeparateModuleProcedureInterface(symbol)) {
3463     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3464     return false;
3465   }
3466   if (symbol->owner() == currScope() && symbol->scope()) {
3467     // This is a MODULE PROCEDURE whose interface appears in its host.
3468     // Convert the module procedure's interface into a subprogram.
3469     SetScope(DEREF(symbol->scope()));
3470     symbol->get<SubprogramDetails>().set_isInterface(false);
3471     if (IsFunction(*symbol)) {
3472       funcResultStack().Push(); // just to be popped later
3473     }
3474   } else {
3475     // Copy the interface into a new subprogram scope.
3476     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3477     PushScope(Scope::Kind::Subprogram, &newSymbol);
3478     const auto &details{symbol->get<SubprogramDetails>()};
3479     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3480     newDetails.set_moduleInterface(*symbol);
3481     for (const Symbol *dummyArg : details.dummyArgs()) {
3482       if (!dummyArg) {
3483         newDetails.add_alternateReturn();
3484       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3485         newDetails.add_dummyArg(*copy);
3486       }
3487     }
3488     if (details.isFunction()) {
3489       currScope().erase(symbol->name());
3490       newDetails.set_result(*currScope().CopySymbol(details.result()));
3491       funcResultStack().Push(); // just to be popped later
3492     }
3493   }
3494   return true;
3495 }
3496 
3497 // A subprogram or interface declared with SUBROUTINE or FUNCTION
3498 bool SubprogramVisitor::BeginSubprogram(const parser::Name &name,
3499     Symbol::Flag subpFlag, bool hasModulePrefix,
3500     const parser::LanguageBindingSpec *bindingSpec) {
3501   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3502     Say(name,
3503         "'%s' is a MODULE procedure which must be declared within a "
3504         "MODULE or SUBMODULE"_err_en_US);
3505     return false;
3506   }
3507   Symbol *moduleInterface{nullptr};
3508   if (hasModulePrefix && !inInterfaceBlock()) {
3509     moduleInterface = FindSymbol(currScope(), name);
3510     if (IsSeparateModuleProcedureInterface(moduleInterface)) {
3511       // Subprogram is MODULE FUNCTION or MODULE SUBROUTINE with an interface
3512       // previously defined in the same scope.
3513       currScope().erase(moduleInterface->name());
3514     } else {
3515       moduleInterface = nullptr;
3516     }
3517     if (!moduleInterface) {
3518       moduleInterface = FindSymbol(currScope().parent(), name);
3519       if (!IsSeparateModuleProcedureInterface(moduleInterface)) {
3520         Say(name,
3521             "'%s' was not declared a separate module procedure"_err_en_US);
3522         return false;
3523       }
3524     }
3525   }
3526   Symbol &newSymbol{PushSubprogramScope(name, subpFlag, bindingSpec)};
3527   if (moduleInterface) {
3528     newSymbol.get<SubprogramDetails>().set_moduleInterface(*moduleInterface);
3529     if (moduleInterface->attrs().test(Attr::PRIVATE)) {
3530       newSymbol.attrs().set(Attr::PRIVATE);
3531     } else if (moduleInterface->attrs().test(Attr::PUBLIC)) {
3532       newSymbol.attrs().set(Attr::PUBLIC);
3533     }
3534   }
3535   if (IsFunction(currScope())) {
3536     funcResultStack().Push();
3537   }
3538   return true;
3539 }
3540 
3541 void SubprogramVisitor::EndSubprogram() {
3542   if (IsFunction(currScope())) {
3543     funcResultStack().Pop();
3544   }
3545   PopScope();
3546 }
3547 
3548 bool SubprogramVisitor::HandlePreviousCalls(
3549     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3550   // If the extant symbol is a generic, check its homonymous specific
3551   // procedure instead if it has one.
3552   if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
3553     return generic->specific() &&
3554         HandlePreviousCalls(name, *generic->specific(), subpFlag);
3555   } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3556              !proc->isDummy() &&
3557              !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3558     // There's a symbol created for previous calls to this subprogram or
3559     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3560     // obligation to rewrite symbol pointers in the parse tree.
3561     if (!symbol.test(subpFlag)) {
3562       Say2(name,
3563           subpFlag == Symbol::Flag::Function
3564               ? "'%s' was previously called as a subroutine"_err_en_US
3565               : "'%s' was previously called as a function"_err_en_US,
3566           symbol, "Previous call of '%s'"_en_US);
3567     }
3568     EntityDetails entity;
3569     if (proc->type()) {
3570       entity.set_type(*proc->type());
3571     }
3572     symbol.details() = std::move(entity);
3573     return true;
3574   } else {
3575     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3576   }
3577 }
3578 
3579 void SubprogramVisitor::CheckExtantProc(
3580     const parser::Name &name, Symbol::Flag subpFlag) {
3581   if (auto *prev{FindSymbol(name)}) {
3582     if (IsDummy(*prev)) {
3583     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3584       // Procedures in an INTERFACE block do not resolve to symbols
3585       // in scopes between the global scope and the current scope.
3586     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3587       SayAlreadyDeclared(name, *prev);
3588     }
3589   }
3590 }
3591 
3592 Symbol &SubprogramVisitor::PushSubprogramScope(const parser::Name &name,
3593     Symbol::Flag subpFlag, const parser::LanguageBindingSpec *bindingSpec) {
3594   Symbol *symbol{GetSpecificFromGeneric(name)};
3595   if (!symbol) {
3596     if (bindingSpec && currScope().IsGlobal() && bindingSpec->v) {
3597       // Create this new top-level subprogram with a binding label
3598       // in a new global scope, so that its symbol's name won't clash
3599       // with another symbol that has a distinct binding label.
3600       PushScope(Scope::Kind::Global,
3601           &MakeSymbol(context().GetTempName(currScope()), Attrs{},
3602               MiscDetails{MiscDetails::Kind::ScopeName}));
3603     }
3604     CheckExtantProc(name, subpFlag);
3605     symbol = &MakeSymbol(name, SubprogramDetails{});
3606   }
3607   symbol->ReplaceName(name.source);
3608   symbol->set(subpFlag);
3609   PushScope(Scope::Kind::Subprogram, symbol);
3610   auto &details{symbol->get<SubprogramDetails>()};
3611   if (inInterfaceBlock()) {
3612     details.set_isInterface();
3613     if (isAbstract()) {
3614       symbol->attrs().set(Attr::ABSTRACT);
3615     } else {
3616       MakeExternal(*symbol);
3617     }
3618     if (isGeneric()) {
3619       Symbol &genericSymbol{GetGenericSymbol()};
3620       if (genericSymbol.has<GenericDetails>()) {
3621         genericSymbol.get<GenericDetails>().AddSpecificProc(
3622             *symbol, name.source);
3623       } else {
3624         CHECK(context().HasError(genericSymbol));
3625       }
3626     }
3627     set_inheritFromParent(false);
3628   }
3629   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3630   return *symbol;
3631 }
3632 
3633 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3634   if (auto *prev{FindSymbol(name)}) {
3635     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3636       if (prev->test(Symbol::Flag::Subroutine) ||
3637           prev->test(Symbol::Flag::Function)) {
3638         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3639             "Previous call of '%s'"_en_US);
3640       }
3641       EraseSymbol(name);
3642     }
3643   }
3644   if (name.source.empty()) {
3645     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3646     PushScope(Scope::Kind::BlockData, nullptr);
3647   } else {
3648     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3649   }
3650 }
3651 
3652 // If name is a generic, return specific subprogram with the same name.
3653 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3654   if (auto *symbol{FindSymbol(name)}) {
3655     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3656       // found generic, want subprogram
3657       auto *specific{details->specific()};
3658       if (!specific) {
3659         specific =
3660             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3661         if (details->derivedType()) {
3662           // A specific procedure with the same name as a derived type
3663           SayAlreadyDeclared(name, *details->derivedType());
3664         } else {
3665           details->set_specific(Resolve(name, *specific));
3666         }
3667       } else if (isGeneric()) {
3668         SayAlreadyDeclared(name, *specific);
3669       }
3670       if (!specific->has<SubprogramDetails>()) {
3671         specific->set_details(SubprogramDetails{});
3672       }
3673       return specific;
3674     }
3675   }
3676   return nullptr;
3677 }
3678 
3679 // DeclarationVisitor implementation
3680 
3681 bool DeclarationVisitor::BeginDecl() {
3682   BeginDeclTypeSpec();
3683   BeginArraySpec();
3684   return BeginAttrs();
3685 }
3686 void DeclarationVisitor::EndDecl() {
3687   EndDeclTypeSpec();
3688   EndArraySpec();
3689   EndAttrs();
3690 }
3691 
3692 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3693   const auto *details{
3694       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3695   if (!details) {
3696     return false;
3697   }
3698   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3699   for (const auto &[location, module] : details->occurrences()) {
3700     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3701         name.source, module->GetName().value());
3702   }
3703   context().SetError(*name.symbol);
3704   return true;
3705 }
3706 
3707 // Report error if accessibility of symbol doesn't match isPrivate.
3708 void DeclarationVisitor::CheckAccessibility(
3709     const SourceName &name, bool isPrivate, Symbol &symbol) {
3710   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3711     Say2(name,
3712         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3713         symbol, "Previous declaration of '%s'"_en_US);
3714   }
3715 }
3716 
3717 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3718   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3719     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3720       if (typeSpec->category() == DeclTypeSpec::Character) {
3721         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3722           Say("The type parameter LEN cannot be deferred without"
3723               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3724         }
3725       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3726         for (const auto &pair : derivedSpec->parameters()) {
3727           if (pair.second.isDeferred()) {
3728             Say(currStmtSource().value(),
3729                 "The value of type parameter '%s' cannot be deferred"
3730                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3731                 pair.first);
3732           }
3733         }
3734       }
3735     }
3736   }
3737   EndDecl();
3738 }
3739 
3740 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3741   DeclareObjectEntity(std::get<parser::Name>(x.t));
3742 }
3743 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3744   DeclareObjectEntity(std::get<parser::Name>(x.t));
3745 }
3746 
3747 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3748   // Defer inspection of initializers to Initialization() so that the
3749   // symbol being initialized will be available within the initialization
3750   // expression.
3751   return false;
3752 }
3753 
3754 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3755   const auto &name{std::get<parser::ObjectName>(x.t)};
3756   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3757   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3758   symbol.ReplaceName(name.source);
3759   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3760     if (ConvertToObjectEntity(symbol)) {
3761       Initialization(name, *init, false);
3762     }
3763   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3764     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3765   }
3766 }
3767 
3768 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3769   const auto &name{std::get<parser::Name>(x.t)};
3770   if (const auto &deferredShapeSpecs{
3771           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3772     CHECK(arraySpec().empty());
3773     BeginArraySpec();
3774     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3775     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3776     symbol.ReplaceName(name.source);
3777     EndArraySpec();
3778   } else {
3779     HandleAttributeStmt(Attr::POINTER, std::get<parser::Name>(x.t));
3780   }
3781 }
3782 
3783 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3784   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3785   auto &name{std::get<parser::Name>(x.t)};
3786   Symbol *symbol;
3787   if (kind == parser::BindEntity::Kind::Object) {
3788     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3789   } else {
3790     symbol = &MakeCommonBlockSymbol(name);
3791     symbol->attrs().set(Attr::BIND_C);
3792   }
3793   SetBindNameOn(*symbol);
3794   return false;
3795 }
3796 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3797   inOldStyleParameterStmt_ = true;
3798   Walk(x.v);
3799   inOldStyleParameterStmt_ = false;
3800   return false;
3801 }
3802 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3803   auto &name{std::get<parser::NamedConstant>(x.t).v};
3804   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3805   if (!ConvertToObjectEntity(symbol) ||
3806       symbol.test(Symbol::Flag::CrayPointer) ||
3807       symbol.test(Symbol::Flag::CrayPointee)) {
3808     SayWithDecl(
3809         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3810     return false;
3811   }
3812   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3813   auto &details{symbol.get<ObjectEntityDetails>()};
3814   if (inOldStyleParameterStmt_) {
3815     // non-standard extension PARAMETER statement (no parentheses)
3816     Walk(expr);
3817     auto folded{EvaluateExpr(expr)};
3818     if (details.type()) {
3819       SayWithDecl(name, symbol,
3820           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3821     } else if (folded) {
3822       auto at{expr.thing.value().source};
3823       if (evaluate::IsActuallyConstant(*folded)) {
3824         if (const auto *type{currScope().GetType(*folded)}) {
3825           if (type->IsPolymorphic()) {
3826             Say(at, "The expression must not be polymorphic"_err_en_US);
3827           } else if (auto shape{ToArraySpec(
3828                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3829             // The type of the named constant is assumed from the expression.
3830             details.set_type(*type);
3831             details.set_init(std::move(*folded));
3832             details.set_shape(std::move(*shape));
3833           } else {
3834             Say(at, "The expression must have constant shape"_err_en_US);
3835           }
3836         } else {
3837           Say(at, "The expression must have a known type"_err_en_US);
3838         }
3839       } else {
3840         Say(at, "The expression must be a constant of known type"_err_en_US);
3841       }
3842     }
3843   } else {
3844     // standard-conforming PARAMETER statement (with parentheses)
3845     ApplyImplicitRules(symbol);
3846     Walk(expr);
3847     if (auto converted{EvaluateNonPointerInitializer(
3848             symbol, expr, expr.thing.value().source)}) {
3849       details.set_init(std::move(*converted));
3850     }
3851   }
3852   return false;
3853 }
3854 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3855   const parser::Name &name{x.v};
3856   if (!FindSymbol(name)) {
3857     Say(name, "Named constant '%s' not found"_err_en_US);
3858   } else {
3859     CheckUseError(name);
3860   }
3861   return false;
3862 }
3863 
3864 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3865   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3866   Symbol *symbol{FindSymbol(name)};
3867   if (symbol && !symbol->has<UnknownDetails>()) {
3868     // Contrary to named constants appearing in a PARAMETER statement,
3869     // enumerator names should not have their type, dimension or any other
3870     // attributes defined before they are declared in the enumerator statement,
3871     // with the exception of accessibility.
3872     // This is not explicitly forbidden by the standard, but they are scalars
3873     // which type is left for the compiler to chose, so do not let users try to
3874     // tamper with that.
3875     SayAlreadyDeclared(name, *symbol);
3876     symbol = nullptr;
3877   } else {
3878     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3879     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3880     symbol->SetType(context().MakeNumericType(
3881         TypeCategory::Integer, evaluate::CInteger::kind));
3882   }
3883 
3884   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3885           enumerator.t)}) {
3886     Walk(*init); // Resolve names in expression before evaluation.
3887     if (auto value{EvaluateInt64(context(), *init)}) {
3888       // Cast all init expressions to C_INT so that they can then be
3889       // safely incremented (see 7.6 Note 2).
3890       enumerationState_.value = static_cast<int>(*value);
3891     } else {
3892       Say(name,
3893           "Enumerator value could not be computed "
3894           "from the given expression"_err_en_US);
3895       // Prevent resolution of next enumerators value
3896       enumerationState_.value = std::nullopt;
3897     }
3898   }
3899 
3900   if (symbol) {
3901     if (enumerationState_.value) {
3902       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3903           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3904     } else {
3905       context().SetError(*symbol);
3906     }
3907   }
3908 
3909   if (enumerationState_.value) {
3910     (*enumerationState_.value)++;
3911   }
3912   return false;
3913 }
3914 
3915 void DeclarationVisitor::Post(const parser::EnumDef &) {
3916   enumerationState_ = EnumeratorState{};
3917 }
3918 
3919 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3920   Attr attr{AccessSpecToAttr(x)};
3921   if (!NonDerivedTypeScope().IsModule()) { // C817
3922     Say(currStmtSource().value(),
3923         "%s attribute may only appear in the specification part of a module"_err_en_US,
3924         EnumToString(attr));
3925   }
3926   CheckAndSet(attr);
3927   return false;
3928 }
3929 
3930 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3931   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3932 }
3933 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3934   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3935 }
3936 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3937   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3938   for (const auto &name : x.v) {
3939     auto *symbol{FindSymbol(name)};
3940     if (!ConvertToProcEntity(DEREF(symbol))) {
3941       SayWithDecl(
3942           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3943     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
3944       Say(symbol->name(),
3945           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
3946           symbol->name());
3947     }
3948   }
3949   return false;
3950 }
3951 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3952   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3953   auto &names{std::get<std::list<parser::Name>>(x.t)};
3954   return CheckNotInBlock("INTENT") && // C1107
3955       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3956 }
3957 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3958   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3959   for (const auto &name : x.v) {
3960     auto &symbol{DEREF(FindSymbol(name))};
3961     if (symbol.has<GenericDetails>()) {
3962       // Generic interface is extending intrinsic; ok
3963     } else if (!symbol.has<HostAssocDetails>() &&
3964         !ConvertToProcEntity(symbol)) {
3965       SayWithDecl(
3966           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3967     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
3968       Say(symbol.name(),
3969           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3970           symbol.name());
3971     } else if (symbol.GetType()) {
3972       // These warnings are worded so that they should make sense in either
3973       // order.
3974       Say(symbol.name(),
3975           "Explicit type declaration ignored for intrinsic function '%s'"_warn_en_US,
3976           symbol.name())
3977           .Attach(name.source,
3978               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
3979               name.source);
3980     }
3981   }
3982   return false;
3983 }
3984 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3985   return CheckNotInBlock("OPTIONAL") && // C1107
3986       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3987 }
3988 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3989   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3990 }
3991 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3992   return CheckNotInBlock("VALUE") && // C1107
3993       HandleAttributeStmt(Attr::VALUE, x.v);
3994 }
3995 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
3996   return HandleAttributeStmt(Attr::VOLATILE, x.v);
3997 }
3998 // Handle a statement that sets an attribute on a list of names.
3999 bool DeclarationVisitor::HandleAttributeStmt(
4000     Attr attr, const std::list<parser::Name> &names) {
4001   for (const auto &name : names) {
4002     HandleAttributeStmt(attr, name);
4003   }
4004   return false;
4005 }
4006 Symbol &DeclarationVisitor::HandleAttributeStmt(
4007     Attr attr, const parser::Name &name) {
4008   if (attr == Attr::INTRINSIC) {
4009     if (!IsIntrinsic(name.source, std::nullopt)) {
4010       Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
4011     } else if (currScope().kind() == Scope::Kind::Subprogram ||
4012         currScope().kind() == Scope::Kind::Block) {
4013       if (auto *symbol{FindSymbol(name)}) {
4014         if (symbol->GetUltimate().has<GenericDetails>() &&
4015             symbol->owner() != currScope()) {
4016           // Declaring a name INTRINSIC when there is a generic
4017           // interface of the same name in the host scope.
4018           // Host-associate the generic and mark it INTRINSIC
4019           // rather than completely overriding the generic.
4020           symbol = &MakeHostAssocSymbol(name, *symbol);
4021           symbol->attrs().set(Attr::INTRINSIC);
4022           return *symbol;
4023         }
4024       }
4025     }
4026   }
4027   auto *symbol{FindInScope(name)};
4028   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
4029     // these can be set on a symbol that is host-assoc or use-assoc
4030     if (!symbol &&
4031         (currScope().kind() == Scope::Kind::Subprogram ||
4032             currScope().kind() == Scope::Kind::Block)) {
4033       if (auto *hostSymbol{FindSymbol(name)}) {
4034         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
4035       }
4036     }
4037   } else if (symbol && symbol->has<UseDetails>()) {
4038     Say(currStmtSource().value(),
4039         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
4040         EnumToString(attr), name.source);
4041     return *symbol;
4042   }
4043   if (!symbol) {
4044     symbol = &MakeSymbol(name, EntityDetails{});
4045   }
4046   symbol->attrs().set(attr);
4047   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
4048   return *symbol;
4049 }
4050 // C1107
4051 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
4052   if (currScope().kind() == Scope::Kind::Block) {
4053     Say(MessageFormattedText{
4054         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
4055     return false;
4056   } else {
4057     return true;
4058   }
4059 }
4060 
4061 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
4062   CHECK(objectDeclAttr_);
4063   const auto &name{std::get<parser::ObjectName>(x.t)};
4064   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
4065 }
4066 
4067 // Declare an entity not yet known to be an object or proc.
4068 Symbol &DeclarationVisitor::DeclareUnknownEntity(
4069     const parser::Name &name, Attrs attrs) {
4070   if (!arraySpec().empty() || !coarraySpec().empty()) {
4071     return DeclareObjectEntity(name, attrs);
4072   } else {
4073     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
4074     if (auto *type{GetDeclTypeSpec()}) {
4075       SetType(name, *type);
4076     }
4077     charInfo_.length.reset();
4078     SetBindNameOn(symbol);
4079     if (symbol.attrs().test(Attr::EXTERNAL)) {
4080       ConvertToProcEntity(symbol);
4081     }
4082     return symbol;
4083   }
4084 }
4085 
4086 bool DeclarationVisitor::HasCycle(
4087     const Symbol &procSymbol, const ProcInterface &interface) {
4088   SourceOrderedSymbolSet procsInCycle;
4089   procsInCycle.insert(procSymbol);
4090   const ProcInterface *thisInterface{&interface};
4091   bool haveInterface{true};
4092   while (haveInterface) {
4093     haveInterface = false;
4094     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
4095       if (procsInCycle.count(*interfaceSymbol) > 0) {
4096         for (const auto &procInCycle : procsInCycle) {
4097           Say(procInCycle->name(),
4098               "The interface for procedure '%s' is recursively "
4099               "defined"_err_en_US,
4100               procInCycle->name());
4101           context().SetError(*procInCycle);
4102         }
4103         return true;
4104       } else if (const auto *procDetails{
4105                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
4106         haveInterface = true;
4107         thisInterface = &procDetails->interface();
4108         procsInCycle.insert(*interfaceSymbol);
4109       }
4110     }
4111   }
4112   return false;
4113 }
4114 
4115 Symbol &DeclarationVisitor::DeclareProcEntity(
4116     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
4117   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
4118   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
4119     if (details->IsInterfaceSet()) {
4120       SayWithDecl(name, symbol,
4121           "The interface for procedure '%s' has already been "
4122           "declared"_err_en_US);
4123       context().SetError(symbol);
4124     } else if (HasCycle(symbol, interface)) {
4125       return symbol;
4126     } else if (interface.type()) {
4127       symbol.set(Symbol::Flag::Function);
4128     } else if (interface.symbol()) {
4129       if (interface.symbol()->test(Symbol::Flag::Function)) {
4130         symbol.set(Symbol::Flag::Function);
4131       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
4132         symbol.set(Symbol::Flag::Subroutine);
4133       }
4134     }
4135     details->set_interface(interface);
4136     SetBindNameOn(symbol);
4137     SetPassNameOn(symbol);
4138   }
4139   return symbol;
4140 }
4141 
4142 Symbol &DeclarationVisitor::DeclareObjectEntity(
4143     const parser::Name &name, Attrs attrs) {
4144   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
4145   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
4146     if (auto *type{GetDeclTypeSpec()}) {
4147       SetType(name, *type);
4148     }
4149     if (!arraySpec().empty()) {
4150       if (details->IsArray()) {
4151         if (!context().HasError(symbol)) {
4152           Say(name,
4153               "The dimensions of '%s' have already been declared"_err_en_US);
4154           context().SetError(symbol);
4155         }
4156       } else {
4157         details->set_shape(arraySpec());
4158       }
4159     }
4160     if (!coarraySpec().empty()) {
4161       if (details->IsCoarray()) {
4162         if (!context().HasError(symbol)) {
4163           Say(name,
4164               "The codimensions of '%s' have already been declared"_err_en_US);
4165           context().SetError(symbol);
4166         }
4167       } else {
4168         details->set_coshape(coarraySpec());
4169       }
4170     }
4171     SetBindNameOn(symbol);
4172   }
4173   ClearArraySpec();
4174   ClearCoarraySpec();
4175   charInfo_.length.reset();
4176   return symbol;
4177 }
4178 
4179 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
4180   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
4181 }
4182 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
4183   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
4184 }
4185 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
4186   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
4187 }
4188 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
4189   SetDeclTypeSpec(MakeLogicalType(x.kind));
4190 }
4191 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
4192   if (!charInfo_.length) {
4193     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
4194   }
4195   if (!charInfo_.kind) {
4196     charInfo_.kind =
4197         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
4198   }
4199   SetDeclTypeSpec(currScope().MakeCharacterType(
4200       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
4201   charInfo_ = {};
4202 }
4203 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
4204   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
4205   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
4206   if (intKind &&
4207       !evaluate::IsValidKindOfIntrinsicType(
4208           TypeCategory::Character, *intKind)) { // C715, C719
4209     Say(currStmtSource().value(),
4210         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
4211     charInfo_.kind = std::nullopt; // prevent further errors
4212   }
4213   if (x.length) {
4214     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
4215   }
4216 }
4217 void DeclarationVisitor::Post(const parser::CharLength &x) {
4218   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
4219     charInfo_.length = ParamValue{
4220         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
4221   } else {
4222     charInfo_.length = GetParamValue(
4223         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
4224   }
4225 }
4226 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
4227   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
4228     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
4229   }
4230 }
4231 
4232 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
4233   if (const auto *kind{std::get_if<
4234           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
4235           &x.u)}) {
4236     const parser::Name &name{kind->thing.thing.thing};
4237     if (!FindSymbol(name)) {
4238       Say(name, "Parameter '%s' not found"_err_en_US);
4239     }
4240   }
4241   return false;
4242 }
4243 
4244 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
4245   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
4246   return true;
4247 }
4248 
4249 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
4250   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
4251   if (const Symbol * derivedSymbol{derivedName.symbol}) {
4252     CheckForAbstractType(*derivedSymbol); // C706
4253   }
4254 }
4255 
4256 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4257   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4258   return true;
4259 }
4260 
4261 void DeclarationVisitor::Post(
4262     const parser::DeclarationTypeSpec::Class &parsedClass) {
4263   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4264   if (auto spec{ResolveDerivedType(typeName)};
4265       spec && !IsExtensibleType(&*spec)) { // C705
4266     SayWithDecl(typeName, *typeName.symbol,
4267         "Non-extensible derived type '%s' may not be used with CLASS"
4268         " keyword"_err_en_US);
4269   }
4270 }
4271 
4272 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4273   const auto &typeName{std::get<parser::Name>(x.t)};
4274   auto spec{ResolveDerivedType(typeName)};
4275   if (!spec) {
4276     return;
4277   }
4278   bool seenAnyName{false};
4279   for (const auto &typeParamSpec :
4280       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4281     const auto &optKeyword{
4282         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4283     std::optional<SourceName> name;
4284     if (optKeyword) {
4285       seenAnyName = true;
4286       name = optKeyword->v.source;
4287     } else if (seenAnyName) {
4288       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4289       continue;
4290     }
4291     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4292     // The expressions in a derived type specifier whose values define
4293     // non-defaulted type parameters are evaluated (folded) in the enclosing
4294     // scope.  The KIND/LEN distinction is resolved later in
4295     // DerivedTypeSpec::CookParameters().
4296     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4297     if (!param.isExplicit() || param.GetExplicit()) {
4298       spec->AddRawParamValue(optKeyword, std::move(param));
4299     }
4300   }
4301 
4302   // The DerivedTypeSpec *spec is used initially as a search key.
4303   // If it turns out to have the same name and actual parameter
4304   // value expressions as another DerivedTypeSpec in the current
4305   // scope does, then we'll use that extant spec; otherwise, when this
4306   // spec is distinct from all derived types previously instantiated
4307   // in the current scope, this spec will be moved into that collection.
4308   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4309   auto category{GetDeclTypeSpecCategory()};
4310   if (dtDetails.isForwardReferenced()) {
4311     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4312     SetDeclTypeSpec(type);
4313     return;
4314   }
4315   // Normalize parameters to produce a better search key.
4316   spec->CookParameters(GetFoldingContext());
4317   if (!spec->MightBeParameterized()) {
4318     spec->EvaluateParameters(context());
4319   }
4320   if (const DeclTypeSpec *
4321       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4322     // This derived type and parameter expressions (if any) are already present
4323     // in this scope.
4324     SetDeclTypeSpec(*extant);
4325   } else {
4326     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4327     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4328     if (derived.MightBeParameterized() &&
4329         currScope().IsParameterizedDerivedType()) {
4330       // Defer instantiation; use the derived type's definition's scope.
4331       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4332     } else if (&currScope() == spec->typeSymbol().scope()) {
4333       // Direct recursive use of a type in the definition of one of its
4334       // components: defer instantiation
4335     } else {
4336       auto restorer{
4337           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4338       derived.Instantiate(currScope());
4339     }
4340     SetDeclTypeSpec(type);
4341   }
4342   // Capture the DerivedTypeSpec in the parse tree for use in building
4343   // structure constructor expressions.
4344   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4345 }
4346 
4347 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4348   const auto &typeName{rec.v};
4349   if (auto spec{ResolveDerivedType(typeName)}) {
4350     spec->CookParameters(GetFoldingContext());
4351     spec->EvaluateParameters(context());
4352     if (const DeclTypeSpec *
4353         extant{currScope().FindInstantiatedDerivedType(
4354             *spec, DeclTypeSpec::TypeDerived)}) {
4355       SetDeclTypeSpec(*extant);
4356     } else {
4357       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4358           typeName.source);
4359     }
4360   }
4361 }
4362 
4363 // The descendents of DerivedTypeDef in the parse tree are visited directly
4364 // in this Pre() routine so that recursive use of the derived type can be
4365 // supported in the components.
4366 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4367   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4368   Walk(stmt);
4369   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4370   auto &scope{currScope()};
4371   CHECK(scope.symbol());
4372   CHECK(scope.symbol()->scope() == &scope);
4373   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4374   details.set_isForwardReferenced(false);
4375   std::set<SourceName> paramNames;
4376   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4377     details.add_paramName(paramName.source);
4378     auto *symbol{FindInScope(scope, paramName)};
4379     if (!symbol) {
4380       Say(paramName,
4381           "No definition found for type parameter '%s'"_err_en_US); // C742
4382       // No symbol for a type param.  Create one and mark it as containing an
4383       // error to improve subsequent semantic processing
4384       BeginAttrs();
4385       Symbol *typeParam{MakeTypeSymbol(
4386           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4387       context().SetError(*typeParam);
4388       EndAttrs();
4389     } else if (!symbol->has<TypeParamDetails>()) {
4390       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4391           *symbol, "Definition of '%s'"_en_US); // C741
4392     }
4393     if (!paramNames.insert(paramName.source).second) {
4394       Say(paramName,
4395           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4396     }
4397   }
4398   for (const auto &[name, symbol] : currScope()) {
4399     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4400       SayDerivedType(name,
4401           "'%s' is not a type parameter of this derived type"_err_en_US,
4402           currScope()); // C741
4403     }
4404   }
4405   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4406   const auto &componentDefs{
4407       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4408   Walk(componentDefs);
4409   if (derivedTypeInfo_.sequence) {
4410     details.set_sequence(true);
4411     if (componentDefs.empty()) { // C740
4412       Say(stmt.source,
4413           "A sequence type must have at least one component"_err_en_US);
4414     }
4415     if (!details.paramNames().empty()) { // C740
4416       Say(stmt.source,
4417           "A sequence type may not have type parameters"_err_en_US);
4418     }
4419     if (derivedTypeInfo_.extends) { // C735
4420       Say(stmt.source,
4421           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4422     }
4423   }
4424   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4425   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4426   derivedTypeInfo_ = {};
4427   PopScope();
4428   return false;
4429 }
4430 
4431 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4432   return BeginAttrs();
4433 }
4434 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4435   auto &name{std::get<parser::Name>(x.t)};
4436   // Resolve the EXTENDS() clause before creating the derived
4437   // type's symbol to foil attempts to recursively extend a type.
4438   auto *extendsName{derivedTypeInfo_.extends};
4439   std::optional<DerivedTypeSpec> extendsType{
4440       ResolveExtendsType(name, extendsName)};
4441   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4442   symbol.ReplaceName(name.source);
4443   derivedTypeInfo_.type = &symbol;
4444   PushScope(Scope::Kind::DerivedType, &symbol);
4445   if (extendsType) {
4446     // Declare the "parent component"; private if the type is.
4447     // Any symbol stored in the EXTENDS() clause is temporarily
4448     // hidden so that a new symbol can be created for the parent
4449     // component without producing spurious errors about already
4450     // existing.
4451     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4452     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4453     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4454       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4455       comp.attrs().set(
4456           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4457       comp.set(Symbol::Flag::ParentComp);
4458       DeclTypeSpec &type{currScope().MakeDerivedType(
4459           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4460       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4461       comp.SetType(type);
4462       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4463       details.add_component(comp);
4464     }
4465   }
4466   EndAttrs();
4467 }
4468 
4469 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4470   auto *type{GetDeclTypeSpec()};
4471   auto attr{std::get<common::TypeParamAttr>(x.t)};
4472   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4473     auto &name{std::get<parser::Name>(decl.t)};
4474     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4475       SetType(name, *type);
4476       if (auto &init{
4477               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4478         if (auto maybeExpr{EvaluateNonPointerInitializer(
4479                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4480           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4481             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4482           }
4483         }
4484       }
4485     }
4486   }
4487   EndDecl();
4488 }
4489 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4490   if (derivedTypeInfo_.extends) {
4491     Say(currStmtSource().value(),
4492         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4493   } else {
4494     derivedTypeInfo_.extends = &x.v;
4495   }
4496   return false;
4497 }
4498 
4499 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4500   if (!currScope().parent().IsModule()) {
4501     Say("PRIVATE is only allowed in a derived type that is"
4502         " in a module"_err_en_US); // C766
4503   } else if (derivedTypeInfo_.sawContains) {
4504     derivedTypeInfo_.privateBindings = true;
4505   } else if (!derivedTypeInfo_.privateComps) {
4506     derivedTypeInfo_.privateComps = true;
4507   } else {
4508     Say("PRIVATE may not appear more than once in"
4509         " derived type components"_warn_en_US); // C738
4510   }
4511   return false;
4512 }
4513 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4514   if (derivedTypeInfo_.sequence) {
4515     Say("SEQUENCE may not appear more than once in"
4516         " derived type components"_warn_en_US); // C738
4517   }
4518   derivedTypeInfo_.sequence = true;
4519   return false;
4520 }
4521 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4522   const auto &name{std::get<parser::Name>(x.t)};
4523   auto attrs{GetAttrs()};
4524   if (derivedTypeInfo_.privateComps &&
4525       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4526     attrs.set(Attr::PRIVATE);
4527   }
4528   if (const auto *declType{GetDeclTypeSpec()}) {
4529     if (const auto *derived{declType->AsDerived()}) {
4530       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4531         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4532           Say("Recursive use of the derived type requires "
4533               "POINTER or ALLOCATABLE"_err_en_US);
4534         }
4535       }
4536       // TODO: This would be more appropriate in CheckDerivedType()
4537       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4538         std::string ultimateName{it.BuildResultDesignatorName()};
4539         // Strip off the leading "%"
4540         if (ultimateName.length() > 1) {
4541           ultimateName.erase(0, 1);
4542           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4543             evaluate::AttachDeclaration(
4544                 Say(name.source,
4545                     "A component with a POINTER or ALLOCATABLE attribute may "
4546                     "not "
4547                     "be of a type with a coarray ultimate component (named "
4548                     "'%s')"_err_en_US,
4549                     ultimateName),
4550                 derived->typeSymbol());
4551           }
4552           if (!arraySpec().empty() || !coarraySpec().empty()) {
4553             evaluate::AttachDeclaration(
4554                 Say(name.source,
4555                     "An array or coarray component may not be of a type with a "
4556                     "coarray ultimate component (named '%s')"_err_en_US,
4557                     ultimateName),
4558                 derived->typeSymbol());
4559           }
4560         }
4561       }
4562     }
4563   }
4564   if (OkToAddComponent(name)) {
4565     auto &symbol{DeclareObjectEntity(name, attrs)};
4566     if (symbol.has<ObjectEntityDetails>()) {
4567       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4568         Initialization(name, *init, true);
4569       }
4570     }
4571     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4572   }
4573   ClearArraySpec();
4574   ClearCoarraySpec();
4575 }
4576 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4577   // Replace "%FILL" with a distinct generated name
4578   const auto &name{std::get<parser::Name>(x.t)};
4579   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4580   if (OkToAddComponent(name)) {
4581     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4582     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4583   }
4584   ClearArraySpec();
4585 }
4586 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4587   CHECK(!interfaceName_);
4588   return BeginDecl();
4589 }
4590 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4591   interfaceName_ = nullptr;
4592   EndDecl();
4593 }
4594 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4595   // Overrides parse tree traversal so as to handle attributes first,
4596   // so POINTER & ALLOCATABLE enable forward references to derived types.
4597   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4598   set_allowForwardReferenceToDerivedType(
4599       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4600   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4601   set_allowForwardReferenceToDerivedType(false);
4602   if (derivedTypeInfo_.sequence) { // C740
4603     if (const auto *declType{GetDeclTypeSpec()}) {
4604       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4605         if (GetAttrs().test(Attr::POINTER) &&
4606             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4607           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4608             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_port_en_US);
4609           }
4610         } else {
4611           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4612         }
4613       }
4614     }
4615   }
4616   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4617   return false;
4618 }
4619 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4620   CHECK(!interfaceName_);
4621   return true;
4622 }
4623 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4624   interfaceName_ = nullptr;
4625 }
4626 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4627   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4628     return !NameIsKnownOrIntrinsic(*name);
4629   }
4630   return true;
4631 }
4632 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4633   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4634     interfaceName_ = name;
4635     NoteInterfaceName(*name);
4636   }
4637 }
4638 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4639   const auto &name{std::get<parser::Name>(x.t)};
4640   ProcInterface interface;
4641   if (interfaceName_) {
4642     interface.set_symbol(*interfaceName_->symbol);
4643   } else if (auto *type{GetDeclTypeSpec()}) {
4644     interface.set_type(*type);
4645   }
4646   auto attrs{HandleSaveName(name.source, GetAttrs())};
4647   DerivedTypeDetails *dtDetails{nullptr};
4648   if (Symbol * symbol{currScope().symbol()}) {
4649     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4650   }
4651   if (!dtDetails) {
4652     attrs.set(Attr::EXTERNAL);
4653   }
4654   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4655   symbol.ReplaceName(name.source);
4656   if (dtDetails) {
4657     dtDetails->add_component(symbol);
4658   }
4659 }
4660 
4661 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4662   derivedTypeInfo_.sawContains = true;
4663   return true;
4664 }
4665 
4666 // Resolve binding names from type-bound generics, saved in genericBindings_.
4667 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4668   // track specifics seen for the current generic to detect duplicates:
4669   const Symbol *currGeneric{nullptr};
4670   std::set<SourceName> specifics;
4671   for (const auto &[generic, bindingName] : genericBindings_) {
4672     if (generic != currGeneric) {
4673       currGeneric = generic;
4674       specifics.clear();
4675     }
4676     auto [it, inserted]{specifics.insert(bindingName->source)};
4677     if (!inserted) {
4678       Say(*bindingName, // C773
4679           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4680           bindingName->source, generic->name())
4681           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4682       continue;
4683     }
4684     auto *symbol{FindInTypeOrParents(*bindingName)};
4685     if (!symbol) {
4686       Say(*bindingName, // C772
4687           "Binding name '%s' not found in this derived type"_err_en_US);
4688     } else if (!symbol->has<ProcBindingDetails>()) {
4689       SayWithDecl(*bindingName, *symbol, // C772
4690           "'%s' is not the name of a specific binding of this type"_err_en_US);
4691     } else {
4692       generic->get<GenericDetails>().AddSpecificProc(
4693           *symbol, bindingName->source);
4694     }
4695   }
4696   genericBindings_.clear();
4697 }
4698 
4699 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4700   if (derivedTypeInfo_.sequence) {
4701     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4702   }
4703 }
4704 
4705 void DeclarationVisitor::Post(
4706     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4707   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4708     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4709   }
4710   for (auto &declaration : x.declarations) {
4711     auto &bindingName{std::get<parser::Name>(declaration.t)};
4712     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4713     const parser::Name &procedureName{optName ? *optName : bindingName};
4714     Symbol *procedure{FindSymbol(procedureName)};
4715     if (!procedure) {
4716       procedure = NoteInterfaceName(procedureName);
4717     }
4718     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4719       SetPassNameOn(*s);
4720       if (GetAttrs().test(Attr::DEFERRED)) {
4721         context().SetError(*s);
4722       }
4723     }
4724   }
4725 }
4726 
4727 void DeclarationVisitor::CheckBindings(
4728     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4729   CHECK(currScope().IsDerivedType());
4730   for (auto &declaration : tbps.declarations) {
4731     auto &bindingName{std::get<parser::Name>(declaration.t)};
4732     if (Symbol * binding{FindInScope(bindingName)}) {
4733       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4734         const Symbol *procedure{FindSubprogram(details->symbol())};
4735         if (!CanBeTypeBoundProc(procedure)) {
4736           if (details->symbol().name() != binding->name()) {
4737             Say(binding->name(),
4738                 "The binding of '%s' ('%s') must be either an accessible "
4739                 "module procedure or an external procedure with "
4740                 "an explicit interface"_err_en_US,
4741                 binding->name(), details->symbol().name());
4742           } else {
4743             Say(binding->name(),
4744                 "'%s' must be either an accessible module procedure "
4745                 "or an external procedure with an explicit interface"_err_en_US,
4746                 binding->name());
4747           }
4748           context().SetError(*binding);
4749         }
4750       }
4751     }
4752   }
4753 }
4754 
4755 void DeclarationVisitor::Post(
4756     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4757   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4758     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4759   }
4760   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4761     for (auto &bindingName : x.bindingNames) {
4762       if (auto *s{
4763               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4764         SetPassNameOn(*s);
4765         if (!GetAttrs().test(Attr::DEFERRED)) {
4766           context().SetError(*s);
4767         }
4768       }
4769     }
4770   }
4771 }
4772 
4773 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4774   if (currScope().IsDerivedType() && currScope().symbol()) {
4775     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4776       for (const auto &subrName : x.v) {
4777         if (const auto *name{ResolveName(subrName)}) {
4778           auto pair{
4779               details->finals().emplace(name->source, DEREF(name->symbol))};
4780           if (!pair.second) { // C787
4781             Say(name->source,
4782                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4783                 name->source)
4784                 .Attach(pair.first->first,
4785                     "earlier appearance of this FINAL subroutine"_en_US);
4786           }
4787         }
4788       }
4789     }
4790   }
4791 }
4792 
4793 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4794   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4795   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4796   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4797   auto info{GenericSpecInfo{genericSpec.value()}};
4798   SourceName symbolName{info.symbolName()};
4799   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4800                             : derivedTypeInfo_.privateBindings};
4801   auto *genericSymbol{FindInScope(symbolName)};
4802   if (genericSymbol) {
4803     if (!genericSymbol->has<GenericDetails>()) {
4804       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4805     }
4806   } else {
4807     // look in parent types:
4808     Symbol *inheritedSymbol{nullptr};
4809     for (const auto &name : GetAllNames(context(), symbolName)) {
4810       inheritedSymbol = currScope().FindComponent(SourceName{name});
4811       if (inheritedSymbol) {
4812         break;
4813       }
4814     }
4815     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4816       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4817     }
4818   }
4819   if (genericSymbol) {
4820     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4821   } else {
4822     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4823     if (!genericSymbol) {
4824       return false;
4825     }
4826     if (isPrivate) {
4827       genericSymbol->attrs().set(Attr::PRIVATE);
4828     }
4829   }
4830   for (const parser::Name &bindingName : bindingNames) {
4831     genericBindings_.emplace(genericSymbol, &bindingName);
4832   }
4833   info.Resolve(genericSymbol);
4834   return false;
4835 }
4836 
4837 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4838 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4839   const auto &structureStatement{
4840       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4841   auto saveDerivedTypeInfo{derivedTypeInfo_};
4842   derivedTypeInfo_ = {};
4843   derivedTypeInfo_.isStructure = true;
4844   derivedTypeInfo_.sequence = true;
4845   Scope *previousStructure{nullptr};
4846   if (saveDerivedTypeInfo.isStructure) {
4847     previousStructure = &currScope();
4848     PopScope();
4849   }
4850   const parser::StructureStmt &structStmt{structureStatement.statement};
4851   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4852   if (!name) {
4853     // Construct a distinct generated name for an anonymous structure
4854     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4855     mutableName.emplace(
4856         parser::Name{context().GetTempName(currScope()), nullptr});
4857   }
4858   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4859   symbol.ReplaceName(name->source);
4860   symbol.get<DerivedTypeDetails>().set_sequence(true);
4861   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4862   derivedTypeInfo_.type = &symbol;
4863   PushScope(Scope::Kind::DerivedType, &symbol);
4864   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4865   Walk(fields);
4866   PopScope();
4867   // Complete the definition
4868   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4869   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4870   derivedTypeSpec.CookParameters(GetFoldingContext());
4871   derivedTypeSpec.EvaluateParameters(context());
4872   DeclTypeSpec &type{currScope().MakeDerivedType(
4873       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4874   type.derivedTypeSpec().Instantiate(currScope());
4875   // Restore previous structure definition context, if any
4876   derivedTypeInfo_ = saveDerivedTypeInfo;
4877   if (previousStructure) {
4878     PushScope(*previousStructure);
4879   }
4880   // Handle any entity declarations on the STRUCTURE statement
4881   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4882   if (!decls.empty()) {
4883     BeginDecl();
4884     SetDeclTypeSpec(type);
4885     Walk(decls);
4886     EndDecl();
4887   }
4888   return false;
4889 }
4890 
4891 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
4892   Say("not yet implemented: support for UNION"_err_en_US); // TODO
4893   return true;
4894 }
4895 
4896 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
4897   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4898           x.u)) {
4899     BeginDecl();
4900   }
4901   return true;
4902 }
4903 
4904 void DeclarationVisitor::Post(const parser::StructureField &x) {
4905   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4906           x.u)) {
4907     EndDecl();
4908   }
4909 }
4910 
4911 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4912   BeginDeclTypeSpec();
4913   return true;
4914 }
4915 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4916   EndDeclTypeSpec();
4917 }
4918 
4919 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4920   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4921   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4922   if (!type) {
4923     return false;
4924   }
4925   const DerivedTypeSpec *spec{type->AsDerived()};
4926   const Scope *typeScope{spec ? spec->scope() : nullptr};
4927   if (!typeScope) {
4928     return false;
4929   }
4930 
4931   // N.B C7102 is implicitly enforced by having inaccessible types not
4932   // being found in resolution.
4933   // More constraints are enforced in expression.cpp so that they
4934   // can apply to structure constructors that have been converted
4935   // from misparsed function references.
4936   for (const auto &component :
4937       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4938     // Visit the component spec expression, but not the keyword, since
4939     // we need to resolve its symbol in the scope of the derived type.
4940     Walk(std::get<parser::ComponentDataSource>(component.t));
4941     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4942       FindInTypeOrParents(*typeScope, kw->v);
4943     }
4944   }
4945   return false;
4946 }
4947 
4948 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4949   for (const parser::BasedPointer &bp : x.v) {
4950     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4951     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4952     auto *pointer{FindSymbol(pointerName)};
4953     if (!pointer) {
4954       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4955     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4956       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4957     } else if (pointer->Rank() > 0) {
4958       SayWithDecl(pointerName, *pointer,
4959           "Cray pointer '%s' must be a scalar"_err_en_US);
4960     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4961       Say(pointerName,
4962           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4963     }
4964     pointer->set(Symbol::Flag::CrayPointer);
4965     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4966         context().defaultKinds().subscriptIntegerKind())};
4967     const auto *type{pointer->GetType()};
4968     if (!type) {
4969       pointer->SetType(pointerType);
4970     } else if (*type != pointerType) {
4971       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4972           pointerName.source, pointerType.AsFortran());
4973     }
4974     if (ResolveName(pointeeName)) {
4975       Symbol &pointee{*pointeeName.symbol};
4976       if (pointee.has<UseDetails>()) {
4977         Say(pointeeName,
4978             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4979         continue;
4980       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4981         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4982         continue;
4983       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4984         Say(pointeeName,
4985             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4986       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4987         Say(pointeeName,
4988             "'%s' was already declared as a Cray pointee"_err_en_US);
4989       } else {
4990         pointee.set(Symbol::Flag::CrayPointee);
4991       }
4992       if (const auto *pointeeType{pointee.GetType()}) {
4993         if (const auto *derived{pointeeType->AsDerived()}) {
4994           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
4995             Say(pointeeName,
4996                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
4997           }
4998         }
4999       }
5000       // process the pointee array-spec, if present
5001       BeginArraySpec();
5002       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
5003       const auto &spec{arraySpec()};
5004       if (!spec.empty()) {
5005         auto &details{pointee.get<ObjectEntityDetails>()};
5006         if (details.shape().empty()) {
5007           details.set_shape(spec);
5008         } else {
5009           SayWithDecl(pointeeName, pointee,
5010               "Array spec was already declared for '%s'"_err_en_US);
5011         }
5012       }
5013       ClearArraySpec();
5014       currScope().add_crayPointer(pointeeName.source, *pointer);
5015     }
5016   }
5017   return false;
5018 }
5019 
5020 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
5021   if (!CheckNotInBlock("NAMELIST")) { // C1107
5022     return false;
5023   }
5024   const auto &groupName{std::get<parser::Name>(x.t)};
5025   auto *groupSymbol{FindInScope(groupName)};
5026   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
5027     groupSymbol = &MakeSymbol(groupName, NamelistDetails{});
5028     groupSymbol->ReplaceName(groupName.source);
5029   }
5030   // Name resolution of group items is deferred to FinishNamelists()
5031   // so that host association is handled correctly.
5032   GetDeferredDeclarationState(true)->namelistGroups.emplace_back(&x);
5033   return false;
5034 }
5035 
5036 void DeclarationVisitor::FinishNamelists() {
5037   if (auto *deferred{GetDeferredDeclarationState()}) {
5038     for (const parser::NamelistStmt::Group *group : deferred->namelistGroups) {
5039       if (auto *groupSymbol{FindInScope(std::get<parser::Name>(group->t))}) {
5040         if (auto *details{groupSymbol->detailsIf<NamelistDetails>()}) {
5041           for (const auto &name : std::get<std::list<parser::Name>>(group->t)) {
5042             auto *symbol{FindSymbol(name)};
5043             if (!symbol) {
5044               symbol = &MakeSymbol(name, ObjectEntityDetails{});
5045               ApplyImplicitRules(*symbol);
5046             } else if (!ConvertToObjectEntity(*symbol)) {
5047               SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
5048             }
5049             symbol->GetUltimate().set(Symbol::Flag::InNamelist);
5050             details->add_object(*symbol);
5051           }
5052         }
5053       }
5054     }
5055     deferred->namelistGroups.clear();
5056   }
5057 }
5058 
5059 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
5060   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
5061     auto *symbol{FindSymbol(*name)};
5062     if (!symbol) {
5063       Say(*name, "Namelist group '%s' not found"_err_en_US);
5064     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
5065       SayWithDecl(
5066           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
5067     }
5068   }
5069   return true;
5070 }
5071 
5072 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
5073   CheckNotInBlock("COMMON"); // C1107
5074   return true;
5075 }
5076 
5077 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
5078   BeginArraySpec();
5079   return true;
5080 }
5081 
5082 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
5083   const auto &name{std::get<parser::Name>(x.t)};
5084   DeclareObjectEntity(name);
5085   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
5086   if (!pair.second) {
5087     const SourceName &prev{*pair.first};
5088     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
5089         "Previous occurrence of '%s' in a COMMON block"_en_US);
5090   }
5091 }
5092 
5093 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
5094   // save equivalence sets to be processed after specification part
5095   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
5096     for (const std::list<parser::EquivalenceObject> &set : x.v) {
5097       specPartState_.equivalenceSets.push_back(&set);
5098     }
5099   }
5100   return false; // don't implicitly declare names yet
5101 }
5102 
5103 void DeclarationVisitor::CheckEquivalenceSets() {
5104   EquivalenceSets equivSets{context()};
5105   inEquivalenceStmt_ = true;
5106   for (const auto *set : specPartState_.equivalenceSets) {
5107     const auto &source{set->front().v.value().source};
5108     if (set->size() <= 1) { // R871
5109       Say(source, "Equivalence set must have more than one object"_err_en_US);
5110     }
5111     for (const parser::EquivalenceObject &object : *set) {
5112       const auto &designator{object.v.value()};
5113       // The designator was not resolved when it was encountered so do it now.
5114       // AnalyzeExpr causes array sections to be changed to substrings as needed
5115       Walk(designator);
5116       if (AnalyzeExpr(context(), designator)) {
5117         equivSets.AddToSet(designator);
5118       }
5119     }
5120     equivSets.FinishSet(source);
5121   }
5122   inEquivalenceStmt_ = false;
5123   for (auto &set : equivSets.sets()) {
5124     if (!set.empty()) {
5125       currScope().add_equivalenceSet(std::move(set));
5126     }
5127   }
5128   specPartState_.equivalenceSets.clear();
5129 }
5130 
5131 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
5132   if (x.v.empty()) {
5133     specPartState_.saveInfo.saveAll = currStmtSource();
5134     currScope().set_hasSAVE();
5135   } else {
5136     for (const parser::SavedEntity &y : x.v) {
5137       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
5138       const auto &name{std::get<parser::Name>(y.t)};
5139       if (kind == parser::SavedEntity::Kind::Common) {
5140         MakeCommonBlockSymbol(name);
5141         AddSaveName(specPartState_.saveInfo.commons, name.source);
5142       } else {
5143         HandleAttributeStmt(Attr::SAVE, name);
5144       }
5145     }
5146   }
5147   return false;
5148 }
5149 
5150 void DeclarationVisitor::CheckSaveStmts() {
5151   for (const SourceName &name : specPartState_.saveInfo.entities) {
5152     auto *symbol{FindInScope(name)};
5153     if (!symbol) {
5154       // error was reported
5155     } else if (specPartState_.saveInfo.saveAll) {
5156       // C889 - note that pgi, ifort, xlf do not enforce this constraint
5157       Say2(name,
5158           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
5159           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
5160     } else if (auto msg{CheckSaveAttr(*symbol)}) {
5161       Say(name, std::move(*msg));
5162       context().SetError(*symbol);
5163     } else {
5164       SetSaveAttr(*symbol);
5165     }
5166   }
5167   for (const SourceName &name : specPartState_.saveInfo.commons) {
5168     if (auto *symbol{currScope().FindCommonBlock(name)}) {
5169       auto &objects{symbol->get<CommonBlockDetails>().objects()};
5170       if (objects.empty()) {
5171         if (currScope().kind() != Scope::Kind::Block) {
5172           Say(name,
5173               "'%s' appears as a COMMON block in a SAVE statement but not in"
5174               " a COMMON statement"_err_en_US);
5175         } else { // C1108
5176           Say(name,
5177               "SAVE statement in BLOCK construct may not contain a"
5178               " common block name '%s'"_err_en_US);
5179         }
5180       } else {
5181         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
5182           SetSaveAttr(*object);
5183         }
5184       }
5185     }
5186   }
5187   if (specPartState_.saveInfo.saveAll) {
5188     // Apply SAVE attribute to applicable symbols
5189     for (auto pair : currScope()) {
5190       auto &symbol{*pair.second};
5191       if (!CheckSaveAttr(symbol)) {
5192         SetSaveAttr(symbol);
5193       }
5194     }
5195   }
5196   specPartState_.saveInfo = {};
5197 }
5198 
5199 // If SAVE attribute can't be set on symbol, return error message.
5200 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
5201     const Symbol &symbol) {
5202   if (IsDummy(symbol)) {
5203     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
5204   } else if (symbol.IsFuncResult()) {
5205     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
5206   } else if (symbol.has<ProcEntityDetails>() &&
5207       !symbol.attrs().test(Attr::POINTER)) {
5208     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
5209   } else if (IsAutomatic(symbol)) {
5210     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
5211   } else {
5212     return std::nullopt;
5213   }
5214 }
5215 
5216 // Record SAVEd names in specPartState_.saveInfo.entities.
5217 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
5218   if (attrs.test(Attr::SAVE)) {
5219     AddSaveName(specPartState_.saveInfo.entities, name);
5220   }
5221   return attrs;
5222 }
5223 
5224 // Record a name in a set of those to be saved.
5225 void DeclarationVisitor::AddSaveName(
5226     std::set<SourceName> &set, const SourceName &name) {
5227   auto pair{set.insert(name)};
5228   if (!pair.second) {
5229     Say2(name, "SAVE attribute was already specified on '%s'"_warn_en_US,
5230         *pair.first, "Previous specification of SAVE attribute"_en_US);
5231   }
5232 }
5233 
5234 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
5235 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
5236   if (!IsSaved(symbol)) {
5237     symbol.attrs().set(Attr::SAVE);
5238   }
5239 }
5240 
5241 // Check types of common block objects, now that they are known.
5242 void DeclarationVisitor::CheckCommonBlocks() {
5243   // check for empty common blocks
5244   for (const auto &pair : currScope().commonBlocks()) {
5245     const auto &symbol{*pair.second};
5246     if (symbol.get<CommonBlockDetails>().objects().empty() &&
5247         symbol.attrs().test(Attr::BIND_C)) {
5248       Say(symbol.name(),
5249           "'%s' appears as a COMMON block in a BIND statement but not in"
5250           " a COMMON statement"_err_en_US);
5251     }
5252   }
5253   // check objects in common blocks
5254   for (const auto &name : specPartState_.commonBlockObjects) {
5255     const auto *symbol{currScope().FindSymbol(name)};
5256     if (!symbol) {
5257       continue;
5258     }
5259     const auto &attrs{symbol->attrs()};
5260     if (attrs.test(Attr::ALLOCATABLE)) {
5261       Say(name,
5262           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
5263     } else if (attrs.test(Attr::BIND_C)) {
5264       Say(name,
5265           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
5266     } else if (IsDummy(*symbol)) {
5267       Say(name,
5268           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5269     } else if (symbol->IsFuncResult()) {
5270       Say(name,
5271           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5272     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5273       if (type->category() == DeclTypeSpec::ClassStar) {
5274         Say(name,
5275             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5276       } else if (const auto *derived{type->AsDerived()}) {
5277         auto &typeSymbol{derived->typeSymbol()};
5278         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5279             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5280           Say(name,
5281               "Derived type '%s' in COMMON block must have the BIND or"
5282               " SEQUENCE attribute"_err_en_US);
5283         }
5284         CheckCommonBlockDerivedType(name, typeSymbol);
5285       }
5286     }
5287   }
5288   specPartState_.commonBlockObjects = {};
5289 }
5290 
5291 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5292   return Resolve(name, currScope().MakeCommonBlock(name.source));
5293 }
5294 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5295     const std::optional<parser::Name> &name) {
5296   if (name) {
5297     return MakeCommonBlockSymbol(*name);
5298   } else {
5299     return MakeCommonBlockSymbol(parser::Name{});
5300   }
5301 }
5302 
5303 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5304   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5305 }
5306 
5307 // Check if this derived type can be in a COMMON block.
5308 void DeclarationVisitor::CheckCommonBlockDerivedType(
5309     const SourceName &name, const Symbol &typeSymbol) {
5310   if (const auto *scope{typeSymbol.scope()}) {
5311     for (const auto &pair : *scope) {
5312       const Symbol &component{*pair.second};
5313       if (component.attrs().test(Attr::ALLOCATABLE)) {
5314         Say2(name,
5315             "Derived type variable '%s' may not appear in a COMMON block"
5316             " due to ALLOCATABLE component"_err_en_US,
5317             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5318         return;
5319       }
5320       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5321       if (component.test(Symbol::Flag::InDataStmt) ||
5322           (details && details->init())) {
5323         Say2(name,
5324             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5325             component.name(), "Component with default initialization"_en_US);
5326         return;
5327       }
5328       if (details) {
5329         if (const auto *type{details->type()}) {
5330           if (const auto *derived{type->AsDerived()}) {
5331             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5332           }
5333         }
5334       }
5335     }
5336   }
5337 }
5338 
5339 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5340     const parser::Name &name) {
5341   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5342           name.source.ToString())}) {
5343     // Unrestricted specific intrinsic function names (e.g., "cos")
5344     // are acceptable as procedure interfaces.  The presence of the
5345     // INTRINSIC flag will cause this symbol to have a complete interface
5346     // recreated for it later on demand, but capturing its result type here
5347     // will make GetType() return a correct result without having to
5348     // probe the intrinsics table again.
5349     Symbol &symbol{
5350         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5351     CHECK(interface->functionResult.has_value());
5352     evaluate::DynamicType dyType{
5353         DEREF(interface->functionResult->GetTypeAndShape()).type()};
5354     CHECK(common::IsNumericTypeCategory(dyType.category()));
5355     const DeclTypeSpec &typeSpec{
5356         MakeNumericType(dyType.category(), dyType.kind())};
5357     ProcEntityDetails details;
5358     ProcInterface procInterface;
5359     procInterface.set_type(typeSpec);
5360     details.set_interface(procInterface);
5361     symbol.set_details(std::move(details));
5362     symbol.set(Symbol::Flag::Function);
5363     if (interface->IsElemental()) {
5364       symbol.attrs().set(Attr::ELEMENTAL);
5365     }
5366     if (interface->IsPure()) {
5367       symbol.attrs().set(Attr::PURE);
5368     }
5369     Resolve(name, symbol);
5370     return true;
5371   } else {
5372     return false;
5373   }
5374 }
5375 
5376 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5377 bool DeclarationVisitor::PassesSharedLocalityChecks(
5378     const parser::Name &name, Symbol &symbol) {
5379   if (!IsVariableName(symbol)) {
5380     SayLocalMustBeVariable(name, symbol); // C1124
5381     return false;
5382   }
5383   if (symbol.owner() == currScope()) { // C1125 and C1126
5384     SayAlreadyDeclared(name, symbol);
5385     return false;
5386   }
5387   return true;
5388 }
5389 
5390 // Checks for locality-specs LOCAL and LOCAL_INIT
5391 bool DeclarationVisitor::PassesLocalityChecks(
5392     const parser::Name &name, Symbol &symbol) {
5393   if (IsAllocatable(symbol)) { // C1128
5394     SayWithDecl(name, symbol,
5395         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5396     return false;
5397   }
5398   if (IsOptional(symbol)) { // C1128
5399     SayWithDecl(name, symbol,
5400         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5401     return false;
5402   }
5403   if (IsIntentIn(symbol)) { // C1128
5404     SayWithDecl(name, symbol,
5405         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5406     return false;
5407   }
5408   if (IsFinalizable(symbol)) { // C1128
5409     SayWithDecl(name, symbol,
5410         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5411     return false;
5412   }
5413   if (evaluate::IsCoarray(symbol)) { // C1128
5414     SayWithDecl(
5415         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5416     return false;
5417   }
5418   if (const DeclTypeSpec * type{symbol.GetType()}) {
5419     if (type->IsPolymorphic() && IsDummy(symbol) &&
5420         !IsPointer(symbol)) { // C1128
5421       SayWithDecl(name, symbol,
5422           "Nonpointer polymorphic argument '%s' not allowed in a "
5423           "locality-spec"_err_en_US);
5424       return false;
5425     }
5426   }
5427   if (IsAssumedSizeArray(symbol)) { // C1128
5428     SayWithDecl(name, symbol,
5429         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5430     return false;
5431   }
5432   if (std::optional<Message> msg{WhyNotModifiable(symbol, currScope())}) {
5433     SayWithReason(name, symbol,
5434         "'%s' may not appear in a locality-spec because it is not "
5435         "definable"_err_en_US,
5436         std::move(*msg));
5437     return false;
5438   }
5439   return PassesSharedLocalityChecks(name, symbol);
5440 }
5441 
5442 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5443     const parser::Name &name) {
5444   Symbol *prev{FindSymbol(name)};
5445   if (!prev) {
5446     // Declare the name as an object in the enclosing scope so that
5447     // the name can't be repurposed there later as something else.
5448     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5449     ConvertToObjectEntity(*prev);
5450     ApplyImplicitRules(*prev);
5451   }
5452   return *prev;
5453 }
5454 
5455 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5456   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5457   if (!PassesLocalityChecks(name, prev)) {
5458     return nullptr;
5459   }
5460   return &MakeHostAssocSymbol(name, prev);
5461 }
5462 
5463 Symbol *DeclarationVisitor::DeclareStatementEntity(
5464     const parser::DoVariable &doVar,
5465     const std::optional<parser::IntegerTypeSpec> &type) {
5466   const parser::Name &name{doVar.thing.thing};
5467   const DeclTypeSpec *declTypeSpec{nullptr};
5468   if (auto *prev{FindSymbol(name)}) {
5469     if (prev->owner() == currScope()) {
5470       SayAlreadyDeclared(name, *prev);
5471       return nullptr;
5472     }
5473     name.symbol = nullptr;
5474     declTypeSpec = prev->GetType();
5475   }
5476   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5477   if (!symbol.has<ObjectEntityDetails>()) {
5478     return nullptr; // error was reported in DeclareEntity
5479   }
5480   if (type) {
5481     declTypeSpec = ProcessTypeSpec(*type);
5482   }
5483   if (declTypeSpec) {
5484     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5485     // declaration of this implied DO loop control variable.
5486     auto restorer{
5487         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5488     SetType(name, *declTypeSpec);
5489   } else {
5490     ApplyImplicitRules(symbol);
5491   }
5492   Symbol *result{Resolve(name, &symbol)};
5493   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5494   return result;
5495 }
5496 
5497 // Set the type of an entity or report an error.
5498 void DeclarationVisitor::SetType(
5499     const parser::Name &name, const DeclTypeSpec &type) {
5500   CHECK(name.symbol);
5501   auto &symbol{*name.symbol};
5502   if (charInfo_.length) { // Declaration has "*length" (R723)
5503     auto length{std::move(*charInfo_.length)};
5504     charInfo_.length.reset();
5505     if (type.category() == DeclTypeSpec::Character) {
5506       auto kind{type.characterTypeSpec().kind()};
5507       // Recurse with correct type.
5508       SetType(name,
5509           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5510       return;
5511     } else { // C753
5512       Say(name,
5513           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5514     }
5515   }
5516   auto *prevType{symbol.GetType()};
5517   if (!prevType) {
5518     symbol.SetType(type);
5519   } else if (symbol.has<UseDetails>()) {
5520     // error recovery case, redeclaration of use-associated name
5521   } else if (HadForwardRef(symbol)) {
5522     // error recovery after use of host-associated name
5523   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5524     SayWithDecl(
5525         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5526     context().SetError(symbol);
5527   } else if (type != *prevType) {
5528     SayWithDecl(name, symbol,
5529         "The type of '%s' has already been implicitly declared"_err_en_US);
5530     context().SetError(symbol);
5531   } else {
5532     symbol.set(Symbol::Flag::Implicit, false);
5533   }
5534 }
5535 
5536 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5537     const parser::Name &name) {
5538   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5539   if (!symbol || symbol->has<UnknownDetails>()) {
5540     if (allowForwardReferenceToDerivedType()) {
5541       if (!symbol) {
5542         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5543         Resolve(name, *symbol);
5544       };
5545       DerivedTypeDetails details;
5546       details.set_isForwardReferenced(true);
5547       symbol->set_details(std::move(details));
5548     } else { // C732
5549       Say(name, "Derived type '%s' not found"_err_en_US);
5550       return std::nullopt;
5551     }
5552   }
5553   if (CheckUseError(name)) {
5554     return std::nullopt;
5555   }
5556   symbol = &symbol->GetUltimate();
5557   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
5558     if (details->derivedType()) {
5559       symbol = &details->derivedType()->GetUltimate();
5560     }
5561   }
5562   if (symbol->has<DerivedTypeDetails>()) {
5563     return DerivedTypeSpec{name.source, *symbol};
5564   } else {
5565     Say(name, "'%s' is not a derived type"_err_en_US);
5566     return std::nullopt;
5567   }
5568 }
5569 
5570 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5571     const parser::Name &typeName, const parser::Name *extendsName) {
5572   if (!extendsName) {
5573     return std::nullopt;
5574   } else if (typeName.source == extendsName->source) {
5575     Say(extendsName->source,
5576         "Derived type '%s' cannot extend itself"_err_en_US);
5577     return std::nullopt;
5578   } else {
5579     return ResolveDerivedType(*extendsName);
5580   }
5581 }
5582 
5583 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5584   // The symbol is checked later by CheckExplicitInterface() and
5585   // CheckBindings().  It can be a forward reference.
5586   if (!NameIsKnownOrIntrinsic(name)) {
5587     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5588     Resolve(name, symbol);
5589   }
5590   return name.symbol;
5591 }
5592 
5593 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5594   if (const Symbol * symbol{name.symbol}) {
5595     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5596       Say(name,
5597           "'%s' must be an abstract interface or a procedure with "
5598           "an explicit interface"_err_en_US,
5599           symbol->name());
5600     }
5601   }
5602 }
5603 
5604 // Create a symbol for a type parameter, component, or procedure binding in
5605 // the current derived type scope. Return false on error.
5606 Symbol *DeclarationVisitor::MakeTypeSymbol(
5607     const parser::Name &name, Details &&details) {
5608   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5609 }
5610 Symbol *DeclarationVisitor::MakeTypeSymbol(
5611     const SourceName &name, Details &&details) {
5612   Scope &derivedType{currScope()};
5613   CHECK(derivedType.IsDerivedType());
5614   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5615     Say2(name,
5616         "Type parameter, component, or procedure binding '%s'"
5617         " already defined in this type"_err_en_US,
5618         *symbol, "Previous definition of '%s'"_en_US);
5619     return nullptr;
5620   } else {
5621     auto attrs{GetAttrs()};
5622     // Apply binding-private-stmt if present and this is a procedure binding
5623     if (derivedTypeInfo_.privateBindings &&
5624         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5625         std::holds_alternative<ProcBindingDetails>(details)) {
5626       attrs.set(Attr::PRIVATE);
5627     }
5628     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5629     if (result.has<TypeParamDetails>()) {
5630       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5631     }
5632     return &result;
5633   }
5634 }
5635 
5636 // Return true if it is ok to declare this component in the current scope.
5637 // Otherwise, emit an error and return false.
5638 bool DeclarationVisitor::OkToAddComponent(
5639     const parser::Name &name, const Symbol *extends) {
5640   for (const Scope *scope{&currScope()}; scope;) {
5641     CHECK(scope->IsDerivedType());
5642     if (auto *prev{FindInScope(*scope, name)}) {
5643       if (!context().HasError(*prev)) {
5644         parser::MessageFixedText msg;
5645         if (extends) {
5646           msg = "Type cannot be extended as it has a component named"
5647                 " '%s'"_err_en_US;
5648         } else if (prev->test(Symbol::Flag::ParentComp)) {
5649           msg = "'%s' is a parent type of this type and so cannot be"
5650                 " a component"_err_en_US;
5651         } else if (scope != &currScope()) {
5652           msg = "Component '%s' is already declared in a parent of this"
5653                 " derived type"_err_en_US;
5654         } else {
5655           msg = "Component '%s' is already declared in this"
5656                 " derived type"_err_en_US;
5657         }
5658         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5659       }
5660       return false;
5661     }
5662     if (scope == &currScope() && extends) {
5663       // The parent component has not yet been added to the scope.
5664       scope = extends->scope();
5665     } else {
5666       scope = scope->GetDerivedTypeParent();
5667     }
5668   }
5669   return true;
5670 }
5671 
5672 ParamValue DeclarationVisitor::GetParamValue(
5673     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5674   return common::visit(
5675       common::visitors{
5676           [=](const parser::ScalarIntExpr &x) { // C704
5677             return ParamValue{EvaluateIntExpr(x), attr};
5678           },
5679           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5680           [=](const parser::TypeParamValue::Deferred &) {
5681             return ParamValue::Deferred(attr);
5682           },
5683       },
5684       x.u);
5685 }
5686 
5687 // ConstructVisitor implementation
5688 
5689 void ConstructVisitor::ResolveIndexName(
5690     const parser::ConcurrentControl &control) {
5691   const parser::Name &name{std::get<parser::Name>(control.t)};
5692   auto *prev{FindSymbol(name)};
5693   if (prev) {
5694     if (prev->owner().kind() == Scope::Kind::Forall ||
5695         prev->owner() == currScope()) {
5696       SayAlreadyDeclared(name, *prev);
5697       return;
5698     }
5699     name.symbol = nullptr;
5700   }
5701   auto &symbol{DeclareObjectEntity(name)};
5702   if (symbol.GetType()) {
5703     // type came from explicit type-spec
5704   } else if (!prev) {
5705     ApplyImplicitRules(symbol);
5706   } else {
5707     const Symbol &prevRoot{ResolveAssociations(*prev)};
5708     // prev could be host- use- or construct-associated with another symbol
5709     if (!prevRoot.has<ObjectEntityDetails>() &&
5710         !prevRoot.has<EntityDetails>()) {
5711       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5712           *prev, "Previous declaration of '%s'"_en_US);
5713       context().SetError(symbol);
5714       return;
5715     } else {
5716       if (const auto *type{prevRoot.GetType()}) {
5717         symbol.SetType(*type);
5718       }
5719       if (prevRoot.IsObjectArray()) {
5720         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5721         return;
5722       }
5723     }
5724   }
5725   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5726 }
5727 
5728 // We need to make sure that all of the index-names get declared before the
5729 // expressions in the loop control are evaluated so that references to the
5730 // index-names in the expressions are correctly detected.
5731 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5732   BeginDeclTypeSpec();
5733   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5734   const auto &controls{
5735       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5736   for (const auto &control : controls) {
5737     ResolveIndexName(control);
5738   }
5739   Walk(controls);
5740   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5741   EndDeclTypeSpec();
5742   return false;
5743 }
5744 
5745 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5746   for (auto &name : x.v) {
5747     if (auto *symbol{DeclareLocalEntity(name)}) {
5748       symbol->set(Symbol::Flag::LocalityLocal);
5749     }
5750   }
5751   return false;
5752 }
5753 
5754 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5755   for (auto &name : x.v) {
5756     if (auto *symbol{DeclareLocalEntity(name)}) {
5757       symbol->set(Symbol::Flag::LocalityLocalInit);
5758     }
5759   }
5760   return false;
5761 }
5762 
5763 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5764   for (const auto &name : x.v) {
5765     if (!FindSymbol(name)) {
5766       Say(name,
5767           "Variable '%s' with SHARED locality implicitly declared"_warn_en_US);
5768     }
5769     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5770     if (PassesSharedLocalityChecks(name, prev)) {
5771       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5772     }
5773   }
5774   return false;
5775 }
5776 
5777 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5778   ProcessTypeSpec(x.type);
5779   Walk(x.values);
5780   return false;
5781 }
5782 
5783 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5784 // enclosing ac-implied-do
5785 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5786   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5787   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5788   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5789   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5790   // F'2018 has the scope of the implied DO variable covering the entire
5791   // implied DO production (19.4(5)), which seems wrong in cases where the name
5792   // of the implied DO variable appears in one of the bound expressions. Thus
5793   // this extension, which shrinks the scope of the variable to exclude the
5794   // expressions in the bounds.
5795   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5796   Walk(bounds.lower);
5797   Walk(bounds.upper);
5798   Walk(bounds.step);
5799   EndCheckOnIndexUseInOwnBounds(restore);
5800   PushScope(Scope::Kind::ImpliedDos, nullptr);
5801   DeclareStatementEntity(bounds.name, type);
5802   Walk(values);
5803   PopScope();
5804   return false;
5805 }
5806 
5807 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5808   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5809   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5810   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5811   // See comment in Pre(AcImpliedDo) above.
5812   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5813   Walk(bounds.lower);
5814   Walk(bounds.upper);
5815   Walk(bounds.step);
5816   EndCheckOnIndexUseInOwnBounds(restore);
5817   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5818   if (pushScope) {
5819     PushScope(Scope::Kind::ImpliedDos, nullptr);
5820   }
5821   DeclareStatementEntity(bounds.name, type);
5822   Walk(objects);
5823   if (pushScope) {
5824     PopScope();
5825   }
5826   return false;
5827 }
5828 
5829 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5830 // statement so that the predicate IsInitialized() will be true
5831 // during semantic analysis before the symbol's initializer is constructed.
5832 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5833   common::visit(
5834       common::visitors{
5835           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5836             Walk(y.thing.value());
5837             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5838             if (first.symbol) {
5839               first.symbol->set(Symbol::Flag::InDataStmt);
5840             }
5841           },
5842           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5843       },
5844       x.u);
5845   return false;
5846 }
5847 
5848 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5849   common::visit(common::visitors{
5850                     [&](const Indirection<parser::Variable> &y) {
5851                       Walk(y.value());
5852                       const parser::Name &first{
5853                           parser::GetFirstName(y.value())};
5854                       if (first.symbol) {
5855                         first.symbol->set(Symbol::Flag::InDataStmt);
5856                       }
5857                     },
5858                     [&](const parser::DataImpliedDo &y) {
5859                       PushScope(Scope::Kind::ImpliedDos, nullptr);
5860                       Walk(y);
5861                       PopScope();
5862                     },
5863                 },
5864       x.u);
5865   return false;
5866 }
5867 
5868 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5869   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5870   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5871   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5872     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5873       if (const Symbol * symbol{FindSymbol(*name)}) {
5874         const Symbol &ultimate{symbol->GetUltimate()};
5875         if (ultimate.has<DerivedTypeDetails>()) {
5876           mutableData.u = elem->ConvertToStructureConstructor(
5877               DerivedTypeSpec{name->source, ultimate});
5878         }
5879       }
5880     }
5881   }
5882   return true;
5883 }
5884 
5885 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5886   if (x.IsDoConcurrent()) {
5887     PushScope(Scope::Kind::Block, nullptr);
5888   }
5889   return true;
5890 }
5891 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5892   if (x.IsDoConcurrent()) {
5893     PopScope();
5894   }
5895 }
5896 
5897 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5898   PushScope(Scope::Kind::Forall, nullptr);
5899   return true;
5900 }
5901 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5902 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5903   PushScope(Scope::Kind::Forall, nullptr);
5904   return true;
5905 }
5906 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5907 
5908 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5909   CheckDef(x.v);
5910   PushScope(Scope::Kind::Block, nullptr);
5911   return false;
5912 }
5913 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5914   PopScope();
5915   CheckRef(x.v);
5916   return false;
5917 }
5918 
5919 void ConstructVisitor::Post(const parser::Selector &x) {
5920   GetCurrentAssociation().selector = ResolveSelector(x);
5921 }
5922 
5923 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
5924   CheckDef(x.t);
5925   PushScope(Scope::Kind::Block, nullptr);
5926   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
5927   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
5928     SetCurrentAssociation(nthLastAssoc);
5929     if (auto *symbol{MakeAssocEntity()}) {
5930       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
5931         Say("Selector must not be a coindexed object"_err_en_US);
5932       }
5933       SetTypeFromAssociation(*symbol);
5934       SetAttrsFromAssociation(*symbol);
5935     }
5936   }
5937   PopAssociation(assocCount);
5938 }
5939 
5940 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5941   PopScope();
5942   CheckRef(x.v);
5943 }
5944 
5945 bool ConstructVisitor::Pre(const parser::Association &x) {
5946   PushAssociation();
5947   const auto &name{std::get<parser::Name>(x.t)};
5948   GetCurrentAssociation().name = &name;
5949   return true;
5950 }
5951 
5952 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5953   CheckDef(x.t);
5954   PushScope(Scope::Kind::Block, nullptr);
5955   PushAssociation();
5956   return true;
5957 }
5958 
5959 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5960   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5961   const auto &name{std::get<parser::Name>(decl.t)};
5962   if (auto *symbol{FindInScope(name)}) {
5963     const auto &selector{std::get<parser::Selector>(x.t)};
5964     if (auto sel{ResolveSelector(selector)}) {
5965       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5966       if (!whole || whole->Corank() == 0) {
5967         Say(sel.source, // C1116
5968             "Selector in coarray association must name a coarray"_err_en_US);
5969       } else if (auto dynType{sel.expr->GetType()}) {
5970         if (!symbol->GetType()) {
5971           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5972         }
5973       }
5974     }
5975   }
5976 }
5977 
5978 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5979   PopAssociation();
5980   PopScope();
5981   CheckRef(x.t);
5982 }
5983 
5984 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5985   PushAssociation();
5986   return true;
5987 }
5988 
5989 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5990   PopAssociation();
5991 }
5992 
5993 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
5994   auto &association{GetCurrentAssociation()};
5995   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5996     // This isn't a name in the current scope, it is in each TypeGuardStmt
5997     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
5998     association.name = &*name;
5999     auto exprType{association.selector.expr->GetType()};
6000     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
6001       Say("Selector must not be a coindexed object"_err_en_US);
6002     }
6003     if (exprType && !exprType->IsPolymorphic()) { // C1159
6004       Say(association.selector.source,
6005           "Selector '%s' in SELECT TYPE statement must be "
6006           "polymorphic"_err_en_US);
6007     }
6008   } else {
6009     if (const Symbol *
6010         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6011       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
6012       if (!IsVariableName(*whole)) {
6013         Say(association.selector.source, // C901
6014             "Selector is not a variable"_err_en_US);
6015         association = {};
6016       }
6017       if (const DeclTypeSpec * type{whole->GetType()}) {
6018         if (!type->IsPolymorphic()) { // C1159
6019           Say(association.selector.source,
6020               "Selector '%s' in SELECT TYPE statement must be "
6021               "polymorphic"_err_en_US);
6022         }
6023       }
6024     } else {
6025       Say(association.selector.source, // C1157
6026           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
6027       association = {};
6028     }
6029   }
6030 }
6031 
6032 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
6033   auto &association{GetCurrentAssociation()};
6034   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6035     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
6036     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
6037     association.name = &*name;
6038   }
6039 }
6040 
6041 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
6042   PushScope(Scope::Kind::Block, nullptr);
6043   return true;
6044 }
6045 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
6046   PopScope();
6047 }
6048 
6049 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
6050   PushScope(Scope::Kind::Block, nullptr);
6051   return true;
6052 }
6053 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
6054   PopScope();
6055 }
6056 
6057 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
6058   if (auto *symbol{MakeAssocEntity()}) {
6059     if (std::holds_alternative<parser::Default>(x.u)) {
6060       SetTypeFromAssociation(*symbol);
6061     } else if (const auto *type{GetDeclTypeSpec()}) {
6062       symbol->SetType(*type);
6063     }
6064     SetAttrsFromAssociation(*symbol);
6065   }
6066 }
6067 
6068 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
6069   if (auto *symbol{MakeAssocEntity()}) {
6070     SetTypeFromAssociation(*symbol);
6071     SetAttrsFromAssociation(*symbol);
6072     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
6073       if (auto val{EvaluateInt64(context(), *init)}) {
6074         auto &details{symbol->get<AssocEntityDetails>()};
6075         details.set_rank(*val);
6076       }
6077     }
6078   }
6079 }
6080 
6081 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
6082   PushAssociation();
6083   return true;
6084 }
6085 
6086 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
6087   PopAssociation();
6088 }
6089 
6090 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
6091   if (x) {
6092     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
6093   }
6094   return true;
6095 }
6096 
6097 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
6098   if (x) {
6099     // Just add an occurrence of this name; checking is done in ValidateLabels
6100     FindSymbol(*x);
6101   }
6102 }
6103 
6104 // Make a symbol for the associating entity of the current association.
6105 Symbol *ConstructVisitor::MakeAssocEntity() {
6106   Symbol *symbol{nullptr};
6107   auto &association{GetCurrentAssociation()};
6108   if (association.name) {
6109     symbol = &MakeSymbol(*association.name, UnknownDetails{});
6110     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
6111       Say(*association.name, // C1102
6112           "The associate name '%s' is already used in this associate statement"_err_en_US);
6113       return nullptr;
6114     }
6115   } else if (const Symbol *
6116       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6117     symbol = &MakeSymbol(whole->name());
6118   } else {
6119     return nullptr;
6120   }
6121   if (auto &expr{association.selector.expr}) {
6122     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
6123   } else {
6124     symbol->set_details(AssocEntityDetails{});
6125   }
6126   return symbol;
6127 }
6128 
6129 // Set the type of symbol based on the current association selector.
6130 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
6131   auto &details{symbol.get<AssocEntityDetails>()};
6132   const MaybeExpr *pexpr{&details.expr()};
6133   if (!*pexpr) {
6134     pexpr = &GetCurrentAssociation().selector.expr;
6135   }
6136   if (*pexpr) {
6137     const SomeExpr &expr{**pexpr};
6138     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
6139       if (const auto *charExpr{
6140               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
6141                   expr)}) {
6142         symbol.SetType(ToDeclTypeSpec(std::move(*type),
6143             FoldExpr(common::visit(
6144                 [](const auto &kindChar) { return kindChar.LEN(); },
6145                 charExpr->u))));
6146       } else {
6147         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
6148       }
6149     } else {
6150       // BOZ literals, procedure designators, &c. are not acceptable
6151       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
6152     }
6153   }
6154 }
6155 
6156 // If current selector is a variable, set some of its attributes on symbol.
6157 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
6158   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
6159   symbol.attrs() |= attrs &
6160       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
6161   if (attrs.test(Attr::POINTER)) {
6162     symbol.attrs().set(Attr::TARGET);
6163   }
6164 }
6165 
6166 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
6167     const parser::Selector &x) {
6168   return common::visit(common::visitors{
6169                            [&](const parser::Expr &expr) {
6170                              return Selector{expr.source, EvaluateExpr(x)};
6171                            },
6172                            [&](const parser::Variable &var) {
6173                              return Selector{var.GetSource(), EvaluateExpr(x)};
6174                            },
6175                        },
6176       x.u);
6177 }
6178 
6179 // Set the current association to the nth to the last association on the
6180 // association stack.  The top of the stack is at n = 1.  This allows access
6181 // to the interior of a list of associations at the top of the stack.
6182 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
6183   CHECK(n > 0 && n <= associationStack_.size());
6184   currentAssociation_ = &associationStack_[associationStack_.size() - n];
6185 }
6186 
6187 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
6188   CHECK(currentAssociation_);
6189   return *currentAssociation_;
6190 }
6191 
6192 void ConstructVisitor::PushAssociation() {
6193   associationStack_.emplace_back(Association{});
6194   currentAssociation_ = &associationStack_.back();
6195 }
6196 
6197 void ConstructVisitor::PopAssociation(std::size_t count) {
6198   CHECK(count > 0 && count <= associationStack_.size());
6199   associationStack_.resize(associationStack_.size() - count);
6200   currentAssociation_ =
6201       associationStack_.empty() ? nullptr : &associationStack_.back();
6202 }
6203 
6204 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6205     evaluate::DynamicType &&type) {
6206   switch (type.category()) {
6207     SWITCH_COVERS_ALL_CASES
6208   case common::TypeCategory::Integer:
6209   case common::TypeCategory::Real:
6210   case common::TypeCategory::Complex:
6211     return context().MakeNumericType(type.category(), type.kind());
6212   case common::TypeCategory::Logical:
6213     return context().MakeLogicalType(type.kind());
6214   case common::TypeCategory::Derived:
6215     if (type.IsAssumedType()) {
6216       return currScope().MakeTypeStarType();
6217     } else if (type.IsUnlimitedPolymorphic()) {
6218       return currScope().MakeClassStarType();
6219     } else {
6220       return currScope().MakeDerivedType(
6221           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
6222                                : DeclTypeSpec::TypeDerived,
6223           common::Clone(type.GetDerivedTypeSpec())
6224 
6225       );
6226     }
6227   case common::TypeCategory::Character:
6228     CRASH_NO_CASE;
6229   }
6230 }
6231 
6232 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6233     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
6234   CHECK(type.category() == common::TypeCategory::Character);
6235   if (length) {
6236     return currScope().MakeCharacterType(
6237         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
6238         KindExpr{type.kind()});
6239   } else {
6240     return currScope().MakeCharacterType(
6241         ParamValue::Deferred(common::TypeParamAttr::Len),
6242         KindExpr{type.kind()});
6243   }
6244 }
6245 
6246 // ResolveNamesVisitor implementation
6247 
6248 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
6249   HandleCall(Symbol::Flag::Function, x.v);
6250   return false;
6251 }
6252 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
6253   HandleCall(Symbol::Flag::Subroutine, x.v);
6254   return false;
6255 }
6256 
6257 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
6258   auto &scope{currScope()};
6259   // Check C896 and C899: where IMPORT statements are allowed
6260   switch (scope.kind()) {
6261   case Scope::Kind::Module:
6262     if (scope.IsModule()) {
6263       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
6264       return false;
6265     } else if (x.kind == common::ImportKind::None) {
6266       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
6267       return false;
6268     }
6269     break;
6270   case Scope::Kind::MainProgram:
6271     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
6272     return false;
6273   case Scope::Kind::Subprogram:
6274     if (scope.parent().IsGlobal()) {
6275       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
6276       return false;
6277     }
6278     break;
6279   case Scope::Kind::BlockData: // C1415 (in part)
6280     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
6281     return false;
6282   default:;
6283   }
6284   if (auto error{scope.SetImportKind(x.kind)}) {
6285     Say(std::move(*error));
6286   }
6287   for (auto &name : x.names) {
6288     if (FindSymbol(scope.parent(), name)) {
6289       scope.add_importName(name.source);
6290     } else {
6291       Say(name, "'%s' not found in host scope"_err_en_US);
6292     }
6293   }
6294   prevImportStmt_ = currStmtSource();
6295   return false;
6296 }
6297 
6298 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6299     const parser::StructureComponent &x) {
6300   return FindComponent(ResolveDataRef(x.base), x.component);
6301 }
6302 
6303 const parser::Name *DeclarationVisitor::ResolveDesignator(
6304     const parser::Designator &x) {
6305   return common::visit(
6306       common::visitors{
6307           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6308           [&](const parser::Substring &x) {
6309             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6310           },
6311       },
6312       x.u);
6313 }
6314 
6315 const parser::Name *DeclarationVisitor::ResolveDataRef(
6316     const parser::DataRef &x) {
6317   return common::visit(
6318       common::visitors{
6319           [=](const parser::Name &y) { return ResolveName(y); },
6320           [=](const Indirection<parser::StructureComponent> &y) {
6321             return ResolveStructureComponent(y.value());
6322           },
6323           [&](const Indirection<parser::ArrayElement> &y) {
6324             Walk(y.value().subscripts);
6325             const parser::Name *name{ResolveDataRef(y.value().base)};
6326             if (name && name->symbol) {
6327               if (!IsProcedure(*name->symbol)) {
6328                 ConvertToObjectEntity(*name->symbol);
6329               } else if (!context().HasError(*name->symbol)) {
6330                 SayWithDecl(*name, *name->symbol,
6331                     "Cannot reference function '%s' as data"_err_en_US);
6332               }
6333             }
6334             return name;
6335           },
6336           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6337             Walk(y.value().imageSelector);
6338             return ResolveDataRef(y.value().base);
6339           },
6340       },
6341       x.u);
6342 }
6343 
6344 // If implicit types are allowed, ensure name is in the symbol table.
6345 // Otherwise, report an error if it hasn't been declared.
6346 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6347   FindSymbol(name);
6348   if (CheckForHostAssociatedImplicit(name)) {
6349     NotePossibleBadForwardRef(name);
6350     return &name;
6351   }
6352   if (Symbol * symbol{name.symbol}) {
6353     if (CheckUseError(name)) {
6354       return nullptr; // reported an error
6355     }
6356     NotePossibleBadForwardRef(name);
6357     symbol->set(Symbol::Flag::ImplicitOrError, false);
6358     if (IsUplevelReference(*symbol)) {
6359       MakeHostAssocSymbol(name, *symbol);
6360     } else if (IsDummy(*symbol) ||
6361         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6362       ConvertToObjectEntity(*symbol);
6363       ApplyImplicitRules(*symbol);
6364     }
6365     if (checkIndexUseInOwnBounds_ &&
6366         *checkIndexUseInOwnBounds_ == name.source) {
6367       Say(name,
6368           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_port_en_US,
6369           name.source);
6370     }
6371     return &name;
6372   }
6373   if (isImplicitNoneType()) {
6374     Say(name, "No explicit type declared for '%s'"_err_en_US);
6375     return nullptr;
6376   }
6377   // Create the symbol then ensure it is accessible
6378   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6379     Say(name,
6380         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6381         name.source);
6382   }
6383   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6384   auto *symbol{FindSymbol(name)};
6385   if (!symbol) {
6386     Say(name,
6387         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6388     return nullptr;
6389   }
6390   ConvertToObjectEntity(*symbol);
6391   ApplyImplicitRules(*symbol);
6392   NotePossibleBadForwardRef(name);
6393   return &name;
6394 }
6395 
6396 // A specification expression may refer to a symbol in the host procedure that
6397 // is implicitly typed. Because specification parts are processed before
6398 // execution parts, this may be the first time we see the symbol. It can't be a
6399 // local in the current scope (because it's in a specification expression) so
6400 // either it is implicitly declared in the host procedure or it is an error.
6401 // We create a symbol in the host assuming it is the former; if that proves to
6402 // be wrong we report an error later in CheckDeclarations().
6403 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6404     const parser::Name &name) {
6405   if (inExecutionPart_) {
6406     return false;
6407   }
6408   if (name.symbol) {
6409     ApplyImplicitRules(*name.symbol, true);
6410   }
6411   Symbol *hostSymbol;
6412   Scope *host{GetHostProcedure()};
6413   if (!host || isImplicitNoneType(*host)) {
6414     return false;
6415   }
6416   if (!name.symbol) {
6417     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6418     ConvertToObjectEntity(*hostSymbol);
6419     ApplyImplicitRules(*hostSymbol);
6420     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6421   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6422     hostSymbol = name.symbol;
6423   } else {
6424     return false;
6425   }
6426   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6427   if (isImplicitNoneType()) {
6428     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6429   } else {
6430     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6431   }
6432   return true;
6433 }
6434 
6435 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6436   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6437   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6438     return false;
6439   } else {
6440     Scope::Kind kind{symbolUnit.kind()};
6441     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6442   }
6443 }
6444 
6445 // base is a part-ref of a derived type; find the named component in its type.
6446 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6447 // COMPLEX component references (%re, %im).
6448 const parser::Name *DeclarationVisitor::FindComponent(
6449     const parser::Name *base, const parser::Name &component) {
6450   if (!base || !base->symbol) {
6451     return nullptr;
6452   }
6453   if (auto *misc{base->symbol->detailsIf<MiscDetails>()}) {
6454     if (component.source == "kind") {
6455       if (misc->kind() == MiscDetails::Kind::ComplexPartRe ||
6456           misc->kind() == MiscDetails::Kind::ComplexPartIm ||
6457           misc->kind() == MiscDetails::Kind::KindParamInquiry ||
6458           misc->kind() == MiscDetails::Kind::LenParamInquiry) {
6459         // x%{re,im,kind,len}%kind
6460         MakePlaceholder(component, MiscDetails::Kind::KindParamInquiry);
6461         return &component;
6462       }
6463     }
6464   }
6465   auto &symbol{base->symbol->GetUltimate()};
6466   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6467     SayWithDecl(*base, symbol,
6468         "'%s' is an invalid base for a component reference"_err_en_US);
6469     return nullptr;
6470   }
6471   auto *type{symbol.GetType()};
6472   if (!type) {
6473     return nullptr; // should have already reported error
6474   }
6475   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6476     auto category{intrinsic->category()};
6477     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6478     if (component.source == "kind") {
6479       miscKind = MiscDetails::Kind::KindParamInquiry;
6480     } else if (category == TypeCategory::Character) {
6481       if (component.source == "len") {
6482         miscKind = MiscDetails::Kind::LenParamInquiry;
6483       }
6484     } else if (category == TypeCategory::Complex) {
6485       if (component.source == "re") {
6486         miscKind = MiscDetails::Kind::ComplexPartRe;
6487       } else if (component.source == "im") {
6488         miscKind = MiscDetails::Kind::ComplexPartIm;
6489       }
6490     }
6491     if (miscKind != MiscDetails::Kind::None) {
6492       MakePlaceholder(component, miscKind);
6493       return &component;
6494     }
6495   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6496     if (const Scope * scope{derived->scope()}) {
6497       if (Resolve(component, scope->FindComponent(component.source))) {
6498         if (auto msg{
6499                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6500           context().Say(component.source, *msg);
6501         }
6502         return &component;
6503       } else {
6504         SayDerivedType(component.source,
6505             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6506       }
6507     }
6508     return nullptr;
6509   }
6510   if (symbol.test(Symbol::Flag::Implicit)) {
6511     Say(*base,
6512         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6513   } else {
6514     SayWithDecl(
6515         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6516   }
6517   return nullptr;
6518 }
6519 
6520 void DeclarationVisitor::Initialization(const parser::Name &name,
6521     const parser::Initialization &init, bool inComponentDecl) {
6522   // Traversal of the initializer was deferred to here so that the
6523   // symbol being declared can be available for use in the expression, e.g.:
6524   //   real, parameter :: x = tiny(x)
6525   if (!name.symbol) {
6526     return;
6527   }
6528   Symbol &ultimate{name.symbol->GetUltimate()};
6529   if (IsAllocatable(ultimate)) {
6530     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6531     return;
6532   }
6533   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6534     // TODO: check C762 - all bounds and type parameters of component
6535     // are colons or constant expressions if component is initialized
6536     common::visit(
6537         common::visitors{
6538             [&](const parser::ConstantExpr &expr) {
6539               NonPointerInitialization(name, expr);
6540             },
6541             [&](const parser::NullInit &null) {
6542               Walk(null);
6543               if (auto nullInit{EvaluateExpr(null)}) {
6544                 if (!evaluate::IsNullPointer(*nullInit)) {
6545                   Say(name,
6546                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6547                 } else if (IsPointer(ultimate)) {
6548                   object->set_init(std::move(*nullInit));
6549                 } else {
6550                   Say(name,
6551                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6552                 }
6553               }
6554             },
6555             [&](const parser::InitialDataTarget &) {
6556               // Defer analysis to the end of the specification part
6557               // so that forward references and attribute checks like SAVE
6558               // work better.
6559               ultimate.set(Symbol::Flag::InDataStmt);
6560             },
6561             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
6562               // Handled later in data-to-inits conversion
6563               ultimate.set(Symbol::Flag::InDataStmt);
6564             },
6565         },
6566         init.u);
6567   }
6568 }
6569 
6570 void DeclarationVisitor::PointerInitialization(
6571     const parser::Name &name, const parser::InitialDataTarget &target) {
6572   if (name.symbol) {
6573     Symbol &ultimate{name.symbol->GetUltimate()};
6574     if (!context().HasError(ultimate)) {
6575       if (IsPointer(ultimate)) {
6576         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6577           CHECK(!details->init());
6578           Walk(target);
6579           if (MaybeExpr expr{EvaluateExpr(target)}) {
6580             // Validation is done in declaration checking.
6581             details->set_init(std::move(*expr));
6582           }
6583         }
6584       } else {
6585         Say(name,
6586             "'%s' is not a pointer but is initialized like one"_err_en_US);
6587         context().SetError(ultimate);
6588       }
6589     }
6590   }
6591 }
6592 void DeclarationVisitor::PointerInitialization(
6593     const parser::Name &name, const parser::ProcPointerInit &target) {
6594   if (name.symbol) {
6595     Symbol &ultimate{name.symbol->GetUltimate()};
6596     if (!context().HasError(ultimate)) {
6597       if (IsProcedurePointer(ultimate)) {
6598         auto &details{ultimate.get<ProcEntityDetails>()};
6599         CHECK(!details.init());
6600         Walk(target);
6601         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6602           if (targetName->symbol) {
6603             // Validation is done in declaration checking.
6604             details.set_init(*targetName->symbol);
6605           }
6606         } else {
6607           details.set_init(nullptr); // explicit NULL()
6608         }
6609       } else {
6610         Say(name,
6611             "'%s' is not a procedure pointer but is initialized "
6612             "like one"_err_en_US);
6613         context().SetError(ultimate);
6614       }
6615     }
6616   }
6617 }
6618 
6619 void DeclarationVisitor::NonPointerInitialization(
6620     const parser::Name &name, const parser::ConstantExpr &expr) {
6621   if (name.symbol) {
6622     Symbol &ultimate{name.symbol->GetUltimate()};
6623     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6624       if (IsPointer(ultimate)) {
6625         Say(name,
6626             "'%s' is a pointer but is not initialized like one"_err_en_US);
6627       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6628         CHECK(!details->init());
6629         Walk(expr);
6630         if (ultimate.owner().IsParameterizedDerivedType()) {
6631           // Save the expression for per-instantiation analysis.
6632           details->set_unanalyzedPDTComponentInit(&expr.thing.value());
6633         } else {
6634           if (MaybeExpr folded{EvaluateNonPointerInitializer(
6635                   ultimate, expr, expr.thing.value().source)}) {
6636             details->set_init(std::move(*folded));
6637           }
6638         }
6639       }
6640     }
6641   }
6642 }
6643 
6644 void ResolveNamesVisitor::HandleCall(
6645     Symbol::Flag procFlag, const parser::Call &call) {
6646   common::visit(
6647       common::visitors{
6648           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6649           [&](const parser::ProcComponentRef &x) { Walk(x); },
6650       },
6651       std::get<parser::ProcedureDesignator>(call.t).u);
6652   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6653 }
6654 
6655 void ResolveNamesVisitor::HandleProcedureName(
6656     Symbol::Flag flag, const parser::Name &name) {
6657   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6658   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6659   if (!symbol) {
6660     if (IsIntrinsic(name.source, flag)) {
6661       symbol =
6662           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6663     } else {
6664       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6665     }
6666     Resolve(name, *symbol);
6667     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6668       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6669         MakeExternal(*symbol);
6670       }
6671     }
6672     ConvertToProcEntity(*symbol);
6673     SetProcFlag(name, *symbol, flag);
6674   } else if (CheckUseError(name)) {
6675     // error was reported
6676   } else {
6677     auto &nonUltimateSymbol = *symbol;
6678     symbol = &Resolve(name, symbol)->GetUltimate();
6679     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6680     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6681         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6682       AcquireIntrinsicProcedureFlags(*symbol);
6683     }
6684     if (!SetProcFlag(name, *symbol, flag)) {
6685       return; // reported error
6686     }
6687     if (!symbol->has<GenericDetails>()) {
6688       CheckImplicitNoneExternal(name.source, *symbol);
6689     }
6690     if (symbol->has<SubprogramDetails>() &&
6691         symbol->attrs().test(Attr::ABSTRACT)) {
6692       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6693     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6694         symbol->has<AssocEntityDetails>()) {
6695       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6696       // here as procedure-designators because this means the related
6697       // FunctionReference are mis-parsed structure constructors or array
6698       // references that will be fixed later when analyzing expressions.
6699     } else if (symbol->has<ObjectEntityDetails>()) {
6700       // Symbols with ObjectEntityDetails are also accepted because this can be
6701       // a mis-parsed array references that will be fixed later. Ensure that if
6702       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6703       // is created for the current scope.
6704       // Operate on non ultimate symbol so that HostAssocDetails are also
6705       // created for symbols used associated in the host procedure.
6706       if (IsUplevelReference(nonUltimateSymbol)) {
6707         MakeHostAssocSymbol(name, nonUltimateSymbol);
6708       }
6709     } else if (symbol->test(Symbol::Flag::Implicit)) {
6710       Say(name,
6711           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6712     } else {
6713       SayWithDecl(name, *symbol,
6714           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6715     }
6716   }
6717 }
6718 
6719 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6720     const SourceName &name, const Symbol &symbol) {
6721   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6722       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6723     Say(name,
6724         "'%s' is an external procedure without the EXTERNAL"
6725         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6726     return false;
6727   }
6728   return true;
6729 }
6730 
6731 // Variant of HandleProcedureName() for use while skimming the executable
6732 // part of a subprogram to catch calls to dummy procedures that are part
6733 // of the subprogram's interface, and to mark as procedures any symbols
6734 // that might otherwise have been miscategorized as objects.
6735 void ResolveNamesVisitor::NoteExecutablePartCall(
6736     Symbol::Flag flag, const parser::Call &call) {
6737   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6738   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6739     // Subtlety: The symbol pointers in the parse tree are not set, because
6740     // they might end up resolving elsewhere (e.g., construct entities in
6741     // SELECT TYPE).
6742     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6743       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6744               ? Symbol::Flag::Function
6745               : Symbol::Flag::Subroutine};
6746       if (!symbol->test(other)) {
6747         ConvertToProcEntity(*symbol);
6748         if (symbol->has<ProcEntityDetails>()) {
6749           symbol->set(flag);
6750           if (IsDummy(*symbol)) {
6751             symbol->attrs().set(Attr::EXTERNAL);
6752           }
6753           ApplyImplicitRules(*symbol);
6754         }
6755       }
6756     }
6757   }
6758 }
6759 
6760 static bool IsLocallyImplicitGlobalSymbol(
6761     const Symbol &symbol, const parser::Name &localName) {
6762   return symbol.owner().IsGlobal() &&
6763       (!symbol.scope() ||
6764           !symbol.scope()->sourceRange().Contains(localName.source));
6765 }
6766 
6767 static bool TypesMismatchIfNonNull(
6768     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
6769   return type1 && type2 && *type1 != *type2;
6770 }
6771 
6772 // Check and set the Function or Subroutine flag on symbol; false on error.
6773 bool ResolveNamesVisitor::SetProcFlag(
6774     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6775   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6776     SayWithDecl(
6777         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6778     return false;
6779   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6780       flag == Symbol::Flag::Function) {
6781     SayWithDecl(
6782         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6783     return false;
6784   } else if (flag == Symbol::Flag::Function &&
6785       IsLocallyImplicitGlobalSymbol(symbol, name) &&
6786       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
6787     SayWithDecl(name, symbol,
6788         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
6789     return false;
6790   } else if (symbol.has<ProcEntityDetails>()) {
6791     symbol.set(flag); // in case it hasn't been set yet
6792     if (flag == Symbol::Flag::Function) {
6793       ApplyImplicitRules(symbol);
6794     }
6795     if (symbol.attrs().test(Attr::INTRINSIC)) {
6796       AcquireIntrinsicProcedureFlags(symbol);
6797     }
6798   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6799     SayWithDecl(
6800         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6801   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6802     AcquireIntrinsicProcedureFlags(symbol);
6803   }
6804   return true;
6805 }
6806 
6807 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6808   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6809   if (!currScope().IsModule()) { // C869
6810     Say(currStmtSource().value(),
6811         "%s statement may only appear in the specification part of a module"_err_en_US,
6812         EnumToString(accessAttr));
6813     return false;
6814   }
6815   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6816   if (accessIds.empty()) {
6817     if (prevAccessStmt_) { // C869
6818       Say("The default accessibility of this module has already been declared"_err_en_US)
6819           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6820     }
6821     prevAccessStmt_ = currStmtSource();
6822     defaultAccess_ = accessAttr;
6823   } else {
6824     for (const auto &accessId : accessIds) {
6825       common::visit(
6826           common::visitors{
6827               [=](const parser::Name &y) {
6828                 Resolve(y, SetAccess(y.source, accessAttr));
6829               },
6830               [=](const Indirection<parser::GenericSpec> &y) {
6831                 auto info{GenericSpecInfo{y.value()}};
6832                 const auto &symbolName{info.symbolName()};
6833                 if (auto *symbol{FindInScope(symbolName)}) {
6834                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6835                 } else if (info.kind().IsName()) {
6836                   info.Resolve(&SetAccess(symbolName, accessAttr));
6837                 } else {
6838                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6839                 }
6840               },
6841           },
6842           accessId.u);
6843     }
6844   }
6845   return false;
6846 }
6847 
6848 // Set the access specification for this symbol.
6849 Symbol &ModuleVisitor::SetAccess(
6850     const SourceName &name, Attr attr, Symbol *symbol) {
6851   if (!symbol) {
6852     symbol = &MakeSymbol(name);
6853   }
6854   Attrs &attrs{symbol->attrs()};
6855   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6856     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6857     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6858     Say(name,
6859         WithSeverity(
6860             "The accessibility of '%s' has already been specified as %s"_warn_en_US,
6861             attr != prev ? parser::Severity::Error : parser::Severity::Warning),
6862         MakeOpName(name), EnumToString(prev));
6863   } else {
6864     attrs.set(attr);
6865   }
6866   return *symbol;
6867 }
6868 
6869 static bool NeedsExplicitType(const Symbol &symbol) {
6870   if (symbol.has<UnknownDetails>()) {
6871     return true;
6872   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6873     return !details->type();
6874   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6875     return !details->type();
6876   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6877     return !details->interface().symbol() && !details->interface().type();
6878   } else {
6879     return false;
6880   }
6881 }
6882 
6883 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6884   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
6885       implicitPart, decls] = x.t;
6886   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
6887   auto stateRestorer{
6888       common::ScopedSet(specPartState_, SpecificationPartState{})};
6889   Walk(accDecls);
6890   Walk(ompDecls);
6891   Walk(compilerDirectives);
6892   Walk(useStmts);
6893   ClearUseRenames();
6894   ClearUseOnly();
6895   ClearExplicitIntrinsicUses();
6896   Walk(importStmts);
6897   Walk(implicitPart);
6898   for (const auto &decl : decls) {
6899     if (const auto *spec{
6900             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6901       PreSpecificationConstruct(*spec);
6902     }
6903   }
6904   Walk(decls);
6905   FinishSpecificationPart(decls);
6906   return false;
6907 }
6908 
6909 // Initial processing on specification constructs, before visiting them.
6910 void ResolveNamesVisitor::PreSpecificationConstruct(
6911     const parser::SpecificationConstruct &spec) {
6912   common::visit(
6913       common::visitors{
6914           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6915             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6916           },
6917           [&](const Indirection<parser::InterfaceBlock> &y) {
6918             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6919                 y.value().t)};
6920             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
6921               CreateGeneric(*spec);
6922             }
6923           },
6924           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
6925             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
6926               CreateCommonBlockSymbols(*commonStmt);
6927             }
6928           },
6929           [&](const auto &) {},
6930       },
6931       spec.u);
6932 }
6933 
6934 void ResolveNamesVisitor::CreateCommonBlockSymbols(
6935     const parser::CommonStmt &commonStmt) {
6936   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
6937     const auto &[name, objects] = block.t;
6938     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
6939     for (const auto &object : objects) {
6940       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
6941       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
6942         details->set_commonBlock(commonBlock);
6943         commonBlock.get<CommonBlockDetails>().add_object(obj);
6944       }
6945     }
6946   }
6947 }
6948 
6949 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6950   auto info{GenericSpecInfo{x}};
6951   SourceName symbolName{info.symbolName()};
6952   if (IsLogicalConstant(context(), symbolName)) {
6953     Say(symbolName,
6954         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6955     return;
6956   }
6957   GenericDetails genericDetails;
6958   Symbol *existing{nullptr};
6959   // Check all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
6960   for (const std::string &n : GetAllNames(context(), symbolName)) {
6961     existing = currScope().FindSymbol(n);
6962     if (existing) {
6963       break;
6964     }
6965   }
6966   if (existing) {
6967     Symbol &ultimate{existing->GetUltimate()};
6968     if (const auto *existingGeneric{ultimate.detailsIf<GenericDetails>()}) {
6969       if (&ultimate.owner() != &currScope()) {
6970         // Create a local copy of a host or use associated generic so that
6971         // it can be locally extended without corrupting the original.
6972         genericDetails.CopyFrom(*existingGeneric);
6973         if (const auto *use{existing->detailsIf<UseDetails>()}) {
6974           AddGenericUse(genericDetails, existing->name(), use->symbol());
6975           EraseSymbol(*existing);
6976         }
6977         existing = &MakeSymbol(symbolName, Attrs{}, std::move(genericDetails));
6978       }
6979       info.Resolve(existing);
6980       return;
6981     }
6982     if (&existing->owner() == &currScope()) {
6983       if (ultimate.has<SubprogramDetails>() ||
6984           ultimate.has<SubprogramNameDetails>()) {
6985         genericDetails.set_specific(ultimate);
6986       } else if (ultimate.has<DerivedTypeDetails>()) {
6987         genericDetails.set_derivedType(ultimate);
6988       } else {
6989         SayAlreadyDeclared(symbolName, *existing);
6990         return;
6991       }
6992       EraseSymbol(*existing);
6993     }
6994   }
6995   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
6996 }
6997 
6998 void ResolveNamesVisitor::FinishSpecificationPart(
6999     const std::list<parser::DeclarationConstruct> &decls) {
7000   badStmtFuncFound_ = false;
7001   funcResultStack().CompleteFunctionResultType();
7002   CheckImports();
7003   bool inModule{currScope().kind() == Scope::Kind::Module};
7004   for (auto &pair : currScope()) {
7005     auto &symbol{*pair.second};
7006     if (NeedsExplicitType(symbol)) {
7007       ApplyImplicitRules(symbol);
7008     }
7009     if (IsDummy(symbol) && isImplicitNoneType() &&
7010         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
7011       Say(symbol.name(),
7012           "No explicit type declared for dummy argument '%s'"_err_en_US);
7013       context().SetError(symbol);
7014     }
7015     if (symbol.has<GenericDetails>()) {
7016       CheckGenericProcedures(symbol);
7017     }
7018     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
7019         !symbol.test(Symbol::Flag::Function) &&
7020         !symbol.test(Symbol::Flag::Subroutine)) {
7021       // in a module, external proc without return type is subroutine
7022       symbol.set(
7023           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
7024     }
7025     if (!symbol.has<HostAssocDetails>()) {
7026       CheckPossibleBadForwardRef(symbol);
7027     }
7028   }
7029   currScope().InstantiateDerivedTypes();
7030   for (const auto &decl : decls) {
7031     if (const auto *statement{std::get_if<
7032             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
7033             &decl.u)}) {
7034       AnalyzeStmtFunctionStmt(statement->statement.value());
7035     }
7036   }
7037   // TODO: what about instantiations in BLOCK?
7038   CheckSaveStmts();
7039   CheckCommonBlocks();
7040   if (!inInterfaceBlock()) {
7041     // TODO: warn for the case where the EQUIVALENCE statement is in a
7042     // procedure declaration in an interface block
7043     CheckEquivalenceSets();
7044   }
7045 }
7046 
7047 // Analyze the bodies of statement functions now that the symbols in this
7048 // specification part have been fully declared and implicitly typed.
7049 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
7050     const parser::StmtFunctionStmt &stmtFunc) {
7051   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
7052   if (!symbol || !symbol->has<SubprogramDetails>()) {
7053     return;
7054   }
7055   auto &details{symbol->get<SubprogramDetails>()};
7056   auto expr{AnalyzeExpr(
7057       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
7058   if (!expr) {
7059     context().SetError(*symbol);
7060     return;
7061   }
7062   if (auto type{evaluate::DynamicType::From(*symbol)}) {
7063     auto converted{ConvertToType(*type, std::move(*expr))};
7064     if (!converted) {
7065       context().SetError(*symbol);
7066       return;
7067     }
7068     details.set_stmtFunction(std::move(*converted));
7069   } else {
7070     details.set_stmtFunction(std::move(*expr));
7071   }
7072 }
7073 
7074 void ResolveNamesVisitor::CheckImports() {
7075   auto &scope{currScope()};
7076   switch (scope.GetImportKind()) {
7077   case common::ImportKind::None:
7078     break;
7079   case common::ImportKind::All:
7080     // C8102: all entities in host must not be hidden
7081     for (const auto &pair : scope.parent()) {
7082       auto &name{pair.first};
7083       std::optional<SourceName> scopeName{scope.GetName()};
7084       if (!scopeName || name != *scopeName) {
7085         CheckImport(prevImportStmt_.value(), name);
7086       }
7087     }
7088     break;
7089   case common::ImportKind::Default:
7090   case common::ImportKind::Only:
7091     // C8102: entities named in IMPORT must not be hidden
7092     for (auto &name : scope.importNames()) {
7093       CheckImport(name, name);
7094     }
7095     break;
7096   }
7097 }
7098 
7099 void ResolveNamesVisitor::CheckImport(
7100     const SourceName &location, const SourceName &name) {
7101   if (auto *symbol{FindInScope(name)}) {
7102     const Symbol &ultimate{symbol->GetUltimate()};
7103     if (&ultimate.owner() == &currScope()) {
7104       Say(location, "'%s' from host is not accessible"_err_en_US, name)
7105           .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
7106               symbol->name());
7107     }
7108   }
7109 }
7110 
7111 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
7112   return CheckNotInBlock("IMPLICIT") && // C1107
7113       ImplicitRulesVisitor::Pre(x);
7114 }
7115 
7116 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
7117   common::visit(common::visitors{
7118                     [&](const parser::Name &x) { ResolveName(x); },
7119                     [&](const parser::StructureComponent &x) {
7120                       ResolveStructureComponent(x);
7121                     },
7122                 },
7123       x.u);
7124 }
7125 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
7126   common::visit(common::visitors{
7127                     [&](const parser::Name &x) { ResolveName(x); },
7128                     [&](const parser::StructureComponent &x) {
7129                       ResolveStructureComponent(x);
7130                     },
7131                 },
7132       x.u);
7133 }
7134 
7135 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
7136   const auto &dataRef{std::get<parser::DataRef>(x.t)};
7137   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
7138   const auto &expr{std::get<parser::Expr>(x.t)};
7139   ResolveDataRef(dataRef);
7140   Walk(bounds);
7141   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
7142   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
7143     if (NameIsKnownOrIntrinsic(*name)) {
7144       // If the name is known because it is an object entity from a host
7145       // procedure, create a host associated symbol.
7146       if (Symbol * symbol{name->symbol}; symbol &&
7147           symbol->GetUltimate().has<ObjectEntityDetails>() &&
7148           IsUplevelReference(*symbol)) {
7149         MakeHostAssocSymbol(*name, *symbol);
7150       }
7151       return false;
7152     }
7153   }
7154   Walk(expr);
7155   return false;
7156 }
7157 void ResolveNamesVisitor::Post(const parser::Designator &x) {
7158   ResolveDesignator(x);
7159 }
7160 
7161 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
7162   ResolveStructureComponent(x.v.thing);
7163 }
7164 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
7165   DeclTypeSpecVisitor::Post(x);
7166   ConstructVisitor::Post(x);
7167 }
7168 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
7169   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
7170   if (HandleStmtFunction(x)) {
7171     return false;
7172   } else {
7173     // This is an array element assignment: resolve names of indices
7174     const auto &names{std::get<std::list<parser::Name>>(x.t)};
7175     for (auto &name : names) {
7176       ResolveName(name);
7177     }
7178     return true;
7179   }
7180 }
7181 
7182 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
7183   const parser::Name &name{x.v};
7184   if (FindSymbol(name)) {
7185     // OK
7186   } else if (IsLogicalConstant(context(), name.source)) {
7187     Say(name,
7188         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7189   } else {
7190     // Resolved later in expression semantics
7191     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
7192   }
7193   return false;
7194 }
7195 
7196 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
7197   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7198     ConvertToObjectEntity(DEREF(name->symbol));
7199   }
7200 }
7201 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
7202   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7203     ConvertToObjectEntity(DEREF(name->symbol));
7204   }
7205 }
7206 
7207 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
7208   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
7209           x.u)) {
7210     // TODO: global directives
7211     return true;
7212   }
7213   auto root{ProgramTree::Build(x)};
7214   SetScope(topScope_);
7215   ResolveSpecificationParts(root);
7216   FinishSpecificationParts(root);
7217   inExecutionPart_ = true;
7218   ResolveExecutionParts(root);
7219   inExecutionPart_ = false;
7220   ResolveAccParts(context(), x);
7221   ResolveOmpParts(context(), x);
7222   return false;
7223 }
7224 
7225 // References to procedures need to record that their symbols are known
7226 // to be procedures, so that they don't get converted to objects by default.
7227 class ExecutionPartSkimmer {
7228 public:
7229   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
7230       : resolver_{resolver} {}
7231 
7232   void Walk(const parser::ExecutionPart *exec) {
7233     if (exec) {
7234       parser::Walk(*exec, *this);
7235     }
7236   }
7237 
7238   template <typename A> bool Pre(const A &) { return true; }
7239   template <typename A> void Post(const A &) {}
7240   void Post(const parser::FunctionReference &fr) {
7241     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
7242   }
7243   void Post(const parser::CallStmt &cs) {
7244     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
7245   }
7246 
7247 private:
7248   ResolveNamesVisitor &resolver_;
7249 };
7250 
7251 // Build the scope tree and resolve names in the specification parts of this
7252 // node and its children
7253 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
7254   if (node.isSpecificationPartResolved()) {
7255     return; // been here already
7256   }
7257   node.set_isSpecificationPartResolved();
7258   if (!BeginScopeForNode(node)) {
7259     return; // an error prevented scope from being created
7260   }
7261   Scope &scope{currScope()};
7262   node.set_scope(scope);
7263   AddSubpNames(node);
7264   common::visit(
7265       [&](const auto *x) {
7266         if (x) {
7267           Walk(*x);
7268         }
7269       },
7270       node.stmt());
7271   Walk(node.spec());
7272   // If this is a function, convert result to an object. This is to prevent the
7273   // result from being converted later to a function symbol if it is called
7274   // inside the function.
7275   // If the result is function pointer, then ConvertToObjectEntity will not
7276   // convert the result to an object, and calling the symbol inside the function
7277   // will result in calls to the result pointer.
7278   // A function cannot be called recursively if RESULT was not used to define a
7279   // distinct result name (15.6.2.2 point 4.).
7280   if (Symbol * symbol{scope.symbol()}) {
7281     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
7282       if (details->isFunction()) {
7283         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
7284       }
7285     }
7286   }
7287   if (node.IsModule()) {
7288     ApplyDefaultAccess();
7289   }
7290   for (auto &child : node.children()) {
7291     ResolveSpecificationParts(child);
7292   }
7293   ExecutionPartSkimmer{*this}.Walk(node.exec());
7294   EndScopeForNode(node);
7295   // Ensure that every object entity has a type.
7296   for (auto &pair : *node.scope()) {
7297     ApplyImplicitRules(*pair.second);
7298   }
7299 }
7300 
7301 // Add SubprogramNameDetails symbols for module and internal subprograms and
7302 // their ENTRY statements.
7303 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
7304   auto kind{
7305       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
7306   for (auto &child : node.children()) {
7307     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
7308     auto childKind{child.GetKind()};
7309     if (childKind == ProgramTree::Kind::Function) {
7310       symbol.set(Symbol::Flag::Function);
7311     } else if (childKind == ProgramTree::Kind::Subroutine) {
7312       symbol.set(Symbol::Flag::Subroutine);
7313     }
7314     for (const auto &entryStmt : child.entryStmts()) {
7315       SubprogramNameDetails details{kind, child};
7316       details.set_isEntryStmt();
7317       auto &symbol{
7318           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
7319       symbol.set(child.GetSubpFlag());
7320     }
7321   }
7322   for (const auto &generic : node.genericSpecs()) {
7323     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
7324       if (currScope().find(name->source) != currScope().end()) {
7325         // If this scope has both a generic interface and a contained
7326         // subprogram with the same name, create the generic's symbol
7327         // now so that any other generics of the same name that are pulled
7328         // into scope later via USE association will properly merge instead
7329         // of raising a bogus error due a conflict with the subprogram.
7330         CreateGeneric(*generic);
7331       }
7332     }
7333   }
7334 }
7335 
7336 // Push a new scope for this node or return false on error.
7337 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
7338   switch (node.GetKind()) {
7339     SWITCH_COVERS_ALL_CASES
7340   case ProgramTree::Kind::Program:
7341     PushScope(Scope::Kind::MainProgram,
7342         &MakeSymbol(node.name(), MainProgramDetails{}));
7343     return true;
7344   case ProgramTree::Kind::Function:
7345   case ProgramTree::Kind::Subroutine:
7346     return BeginSubprogram(node.name(), node.GetSubpFlag(),
7347         node.HasModulePrefix(), node.bindingSpec());
7348   case ProgramTree::Kind::MpSubprogram:
7349     return BeginMpSubprogram(node.name());
7350   case ProgramTree::Kind::Module:
7351     BeginModule(node.name(), false);
7352     return true;
7353   case ProgramTree::Kind::Submodule:
7354     return BeginSubmodule(node.name(), node.GetParentId());
7355   case ProgramTree::Kind::BlockData:
7356     PushBlockDataScope(node.name());
7357     return true;
7358   }
7359 }
7360 
7361 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
7362   EndSubprogram();
7363 }
7364 
7365 // Some analyses and checks, such as the processing of initializers of
7366 // pointers, are deferred until all of the pertinent specification parts
7367 // have been visited.  This deferred processing enables the use of forward
7368 // references in these circumstances.
7369 class DeferredCheckVisitor {
7370 public:
7371   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7372       : resolver_{resolver} {}
7373 
7374   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7375 
7376   template <typename A> bool Pre(const A &) { return true; }
7377   template <typename A> void Post(const A &) {}
7378 
7379   void Post(const parser::DerivedTypeStmt &x) {
7380     const auto &name{std::get<parser::Name>(x.t)};
7381     if (Symbol * symbol{name.symbol}) {
7382       if (Scope * scope{symbol->scope()}) {
7383         if (scope->IsDerivedType()) {
7384           resolver_.PushScope(*scope);
7385           pushedScope_ = true;
7386         }
7387       }
7388     }
7389   }
7390   void Post(const parser::EndTypeStmt &) {
7391     if (pushedScope_) {
7392       resolver_.PopScope();
7393       pushedScope_ = false;
7394     }
7395   }
7396 
7397   void Post(const parser::ProcInterface &pi) {
7398     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7399       resolver_.CheckExplicitInterface(*name);
7400     }
7401   }
7402   bool Pre(const parser::EntityDecl &decl) {
7403     Init(std::get<parser::Name>(decl.t),
7404         std::get<std::optional<parser::Initialization>>(decl.t));
7405     return false;
7406   }
7407   bool Pre(const parser::ComponentDecl &decl) {
7408     Init(std::get<parser::Name>(decl.t),
7409         std::get<std::optional<parser::Initialization>>(decl.t));
7410     return false;
7411   }
7412   bool Pre(const parser::ProcDecl &decl) {
7413     if (const auto &init{
7414             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7415       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7416     }
7417     return false;
7418   }
7419   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7420     resolver_.CheckExplicitInterface(tbps.interfaceName);
7421   }
7422   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7423     if (pushedScope_) {
7424       resolver_.CheckBindings(tbps);
7425     }
7426   }
7427 
7428 private:
7429   void Init(const parser::Name &name,
7430       const std::optional<parser::Initialization> &init) {
7431     if (init) {
7432       if (const auto *target{
7433               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7434         resolver_.PointerInitialization(name, *target);
7435       }
7436     }
7437   }
7438 
7439   ResolveNamesVisitor &resolver_;
7440   bool pushedScope_{false};
7441 };
7442 
7443 // Perform checks and completions that need to happen after all of
7444 // the specification parts but before any of the execution parts.
7445 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7446   if (!node.scope()) {
7447     return; // error occurred creating scope
7448   }
7449   SetScope(*node.scope());
7450   // The initializers of pointers, the default initializers of pointer
7451   // components, and non-deferred type-bound procedure bindings have not
7452   // yet been traversed.
7453   // We do that now, when any (formerly) forward references that appear
7454   // in those initializers will resolve to the right symbols without
7455   // incurring spurious errors with IMPLICIT NONE.
7456   DeferredCheckVisitor{*this}.Walk(node.spec());
7457   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7458   for (Scope &childScope : currScope().children()) {
7459     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7460       FinishDerivedTypeInstantiation(childScope);
7461     }
7462   }
7463   for (const auto &child : node.children()) {
7464     FinishSpecificationParts(child);
7465   }
7466 }
7467 
7468 // Duplicate and fold component object pointer default initializer designators
7469 // using the actual type parameter values of each particular instantiation.
7470 // Validation is done later in declaration checking.
7471 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7472   CHECK(scope.IsDerivedType() && !scope.symbol());
7473   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7474     spec->Instantiate(currScope());
7475     const Symbol &origTypeSymbol{spec->typeSymbol()};
7476     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7477       CHECK(origTypeScope->IsDerivedType() &&
7478           origTypeScope->symbol() == &origTypeSymbol);
7479       auto &foldingContext{GetFoldingContext()};
7480       auto restorer{foldingContext.WithPDTInstance(*spec)};
7481       for (auto &pair : scope) {
7482         Symbol &comp{*pair.second};
7483         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7484         if (IsPointer(comp)) {
7485           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7486             auto origDetails{origComp.get<ObjectEntityDetails>()};
7487             if (const MaybeExpr & init{origDetails.init()}) {
7488               SomeExpr newInit{*init};
7489               MaybeExpr folded{
7490                   evaluate::Fold(foldingContext, std::move(newInit))};
7491               details->set_init(std::move(folded));
7492             }
7493           }
7494         }
7495       }
7496     }
7497   }
7498 }
7499 
7500 // Resolve names in the execution part of this node and its children
7501 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7502   if (!node.scope()) {
7503     return; // error occurred creating scope
7504   }
7505   SetScope(*node.scope());
7506   if (const auto *exec{node.exec()}) {
7507     Walk(*exec);
7508   }
7509   FinishNamelists();
7510   PopScope(); // converts unclassified entities into objects
7511   for (const auto &child : node.children()) {
7512     ResolveExecutionParts(child);
7513   }
7514 }
7515 
7516 void ResolveNamesVisitor::Post(const parser::Program &) {
7517   // ensure that all temps were deallocated
7518   CHECK(!attrs_);
7519   CHECK(!GetDeclTypeSpec());
7520 }
7521 
7522 // A singleton instance of the scope -> IMPLICIT rules mapping is
7523 // shared by all instances of ResolveNamesVisitor and accessed by this
7524 // pointer when the visitors (other than the top-level original) are
7525 // constructed.
7526 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7527 
7528 bool ResolveNames(
7529     SemanticsContext &context, const parser::Program &program, Scope &top) {
7530   ImplicitRulesMap implicitRulesMap;
7531   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7532   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7533   return !context.AnyFatalError();
7534 }
7535 
7536 // Processes a module (but not internal) function when it is referenced
7537 // in a specification expression in a sibling procedure.
7538 void ResolveSpecificationParts(
7539     SemanticsContext &context, const Symbol &subprogram) {
7540   auto originalLocation{context.location()};
7541   ImplicitRulesMap implicitRulesMap;
7542   bool localImplicitRulesMap{false};
7543   if (!sharedImplicitRulesMap) {
7544     sharedImplicitRulesMap = &implicitRulesMap;
7545     localImplicitRulesMap = true;
7546   }
7547   ResolveNamesVisitor visitor{
7548       context, *sharedImplicitRulesMap, context.globalScope()};
7549   const auto &details{subprogram.get<SubprogramNameDetails>()};
7550   ProgramTree &node{details.node()};
7551   const Scope &moduleScope{subprogram.owner()};
7552   if (localImplicitRulesMap) {
7553     visitor.BeginScope(const_cast<Scope &>(moduleScope));
7554   } else {
7555     visitor.SetScope(const_cast<Scope &>(moduleScope));
7556   }
7557   visitor.ResolveSpecificationParts(node);
7558   context.set_location(std::move(originalLocation));
7559   if (localImplicitRulesMap) {
7560     sharedImplicitRulesMap = nullptr;
7561   }
7562 }
7563 
7564 } // namespace Fortran::semantics
7565