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 if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2427     return hostDetails->symbol().has<ObjectEntityDetails>();
2428   } else {
2429     return false;
2430   }
2431   return true;
2432 }
2433 // Convert symbol to be a ProcEntity or return false if it can't be.
2434 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2435   if (symbol.has<ProcEntityDetails>()) {
2436     // nothing to do
2437   } else if (symbol.has<UnknownDetails>()) {
2438     symbol.set_details(ProcEntityDetails{});
2439   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2440     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2441     symbol.set_details(ProcEntityDetails{std::move(*details)});
2442     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2443       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2444       symbol.set(Symbol::Flag::Function);
2445     }
2446   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2447     return useDetails->symbol().has<ProcEntityDetails>();
2448   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2449     return hostDetails->symbol().has<ProcEntityDetails>();
2450   } else {
2451     return false;
2452   }
2453   return true;
2454 }
2455 
2456 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2457     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2458   KindExpr value{GetKindParamExpr(category, kind)};
2459   if (auto known{evaluate::ToInt64(value)}) {
2460     return context().MakeNumericType(category, static_cast<int>(*known));
2461   } else {
2462     return currScope_->MakeNumericType(category, std::move(value));
2463   }
2464 }
2465 
2466 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2467     const std::optional<parser::KindSelector> &kind) {
2468   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2469   if (auto known{evaluate::ToInt64(value)}) {
2470     return context().MakeLogicalType(static_cast<int>(*known));
2471   } else {
2472     return currScope_->MakeLogicalType(std::move(value));
2473   }
2474 }
2475 
2476 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2477   if (inSpecificationPart_ && name.symbol) {
2478     auto kind{currScope().kind()};
2479     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2480         kind == Scope::Kind::Block) {
2481       bool isHostAssociated{&name.symbol->owner() == &currScope()
2482               ? name.symbol->has<HostAssocDetails>()
2483               : name.symbol->owner().Contains(currScope())};
2484       if (isHostAssociated) {
2485         specPartState_.forwardRefs.insert(name.source);
2486       }
2487     }
2488   }
2489 }
2490 
2491 std::optional<SourceName> ScopeHandler::HadForwardRef(
2492     const Symbol &symbol) const {
2493   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2494   if (iter != specPartState_.forwardRefs.end()) {
2495     return *iter;
2496   }
2497   return std::nullopt;
2498 }
2499 
2500 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2501   if (!context().HasError(symbol)) {
2502     if (auto fwdRef{HadForwardRef(symbol)}) {
2503       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2504       if (outer && symbol.has<UseDetails>() &&
2505           &symbol.GetUltimate() == &outer->GetUltimate()) {
2506         // e.g. IMPORT of host's USE association
2507         return false;
2508       }
2509       Say(*fwdRef,
2510           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2511           *fwdRef)
2512           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2513       context().SetError(symbol);
2514       return true;
2515     }
2516     if (IsDummy(symbol) && isImplicitNoneType() &&
2517         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2518       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2519       // ApplyImplicitRules() due to use in a specification expression,
2520       // and no explicit type declaration appeared later.
2521       Say(symbol.name(),
2522           "No explicit type declared for dummy argument '%s'"_err_en_US);
2523       context().SetError(symbol);
2524       return true;
2525     }
2526   }
2527   return false;
2528 }
2529 
2530 void ScopeHandler::MakeExternal(Symbol &symbol) {
2531   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2532     symbol.attrs().set(Attr::EXTERNAL);
2533     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2534       Say(symbol.name(),
2535           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2536           symbol.name());
2537     }
2538   }
2539 }
2540 
2541 // ModuleVisitor implementation
2542 
2543 bool ModuleVisitor::Pre(const parser::Only &x) {
2544   common::visit(common::visitors{
2545                     [&](const Indirection<parser::GenericSpec> &generic) {
2546                       GenericSpecInfo genericSpecInfo{generic.value()};
2547                       AddUseOnly(genericSpecInfo.symbolName());
2548                       AddUse(genericSpecInfo);
2549                     },
2550                     [&](const parser::Name &name) {
2551                       AddUseOnly(name.source);
2552                       Resolve(name, AddUse(name.source, name.source).use);
2553                     },
2554                     [&](const parser::Rename &rename) { Walk(rename); },
2555                 },
2556       x.u);
2557   return false;
2558 }
2559 
2560 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2561   const auto &localName{std::get<0>(x.t)};
2562   const auto &useName{std::get<1>(x.t)};
2563   AddUseRename(useName.source);
2564   SymbolRename rename{AddUse(localName.source, useName.source)};
2565   if (rename.use) {
2566     EraseRenamedSymbol(*rename.use);
2567   }
2568   Resolve(useName, rename.use);
2569   Resolve(localName, rename.local);
2570   return false;
2571 }
2572 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2573   const parser::DefinedOpName &local{std::get<0>(x.t)};
2574   const parser::DefinedOpName &use{std::get<1>(x.t)};
2575   GenericSpecInfo localInfo{local};
2576   GenericSpecInfo useInfo{use};
2577   if (IsIntrinsicOperator(context(), local.v.source)) {
2578     Say(local.v,
2579         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2580   } else if (IsLogicalConstant(context(), local.v.source)) {
2581     Say(local.v,
2582         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2583   } else {
2584     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2585     if (rename.use) {
2586       EraseRenamedSymbol(*rename.use);
2587     }
2588     useInfo.Resolve(rename.use);
2589     localInfo.Resolve(rename.local);
2590   }
2591   return false;
2592 }
2593 
2594 // Set useModuleScope_ to the Scope of the module being used.
2595 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2596   std::optional<bool> isIntrinsic;
2597   if (x.nature) {
2598     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2599     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2600   } else if (currScope().IsModule() && currScope().symbol() &&
2601       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2602     // Intrinsic modules USE only other intrinsic modules
2603     isIntrinsic = true;
2604   }
2605   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2606   if (!useModuleScope_) {
2607     return false;
2608   }
2609   // use the name from this source file
2610   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2611   return true;
2612 }
2613 
2614 void ModuleVisitor::Post(const parser::UseStmt &x) {
2615   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2616     // Not a use-only: collect the names that were used in renames,
2617     // then add a use for each public name that was not renamed.
2618     std::set<SourceName> useNames;
2619     for (const auto &rename : *list) {
2620       common::visit(common::visitors{
2621                         [&](const parser::Rename::Names &names) {
2622                           useNames.insert(std::get<1>(names.t).source);
2623                         },
2624                         [&](const parser::Rename::Operators &ops) {
2625                           useNames.insert(std::get<1>(ops.t).v.source);
2626                         },
2627                     },
2628           rename.u);
2629     }
2630     for (const auto &[name, symbol] : *useModuleScope_) {
2631       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2632           (!symbol->attrs().test(Attr::INTRINSIC) ||
2633               symbol->has<UseDetails>()) &&
2634           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2635         SourceName location{x.moduleName.source};
2636         if (auto *localSymbol{FindInScope(name)}) {
2637           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2638         } else {
2639           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2640         }
2641       }
2642     }
2643   }
2644   useModuleScope_ = nullptr;
2645 }
2646 
2647 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2648     const SourceName &localName, const SourceName &useName) {
2649   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2650 }
2651 
2652 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2653     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2654   if (!useModuleScope_) {
2655     return {}; // error occurred finding module
2656   }
2657   if (!useSymbol) {
2658     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2659         useModuleScope_->GetName().value());
2660     return {};
2661   }
2662   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2663       !FindModuleFileContaining(currScope())) {
2664     // Privacy is not enforced in module files so that generic interfaces
2665     // can be resolved to private specific procedures in specification
2666     // expressions.
2667     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2668         useModuleScope_->GetName().value());
2669     return {};
2670   }
2671   auto &localSymbol{MakeSymbol(localName)};
2672   DoAddUse(useName, localName, localSymbol, *useSymbol);
2673   return {&localSymbol, useSymbol};
2674 }
2675 
2676 // symbol must be either a Use or a Generic formed by merging two uses.
2677 // Convert it to a UseError with this additional location.
2678 static void ConvertToUseError(
2679     Symbol &symbol, const SourceName &location, const Scope &module) {
2680   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2681   if (!useDetails) {
2682     auto &genericDetails{symbol.get<GenericDetails>()};
2683     useDetails = &genericDetails.uses().at(0)->get<UseDetails>();
2684   }
2685   symbol.set_details(
2686       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2687 }
2688 
2689 // If a symbol has previously been USE-associated and did not appear in a USE
2690 // ONLY clause, erase it from the current scope.  This is needed when a name
2691 // appears in a USE rename clause.
2692 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2693   const SourceName &name{useSymbol.name()};
2694   if (const Symbol * symbol{FindInScope(name)}) {
2695     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2696       const Symbol &moduleSymbol{useDetails->symbol()};
2697       if (moduleSymbol.name() == name &&
2698           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2699           !IsUseOnly(name)) {
2700         EraseSymbol(*symbol);
2701       }
2702     }
2703   }
2704 }
2705 
2706 void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
2707     Symbol &localSymbol, const Symbol &useSymbol) {
2708   if (localName != useSymbol.name()) {
2709     EraseRenamedSymbol(useSymbol);
2710   }
2711   if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2712     details->add_occurrence(location, *useModuleScope_);
2713     return;
2714   }
2715 
2716   if (localSymbol.has<UnknownDetails>()) {
2717     localSymbol.set_details(UseDetails{localName, useSymbol});
2718     localSymbol.attrs() =
2719         useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2720     localSymbol.flags() = useSymbol.flags();
2721     return;
2722   }
2723 
2724   Symbol &localUltimate{localSymbol.GetUltimate()};
2725   const Symbol &useUltimate{useSymbol.GetUltimate()};
2726   if (&localUltimate == &useUltimate) {
2727     // use-associating the same symbol again -- ok
2728     return;
2729   }
2730 
2731   auto checkAmbiguousDerivedType{[this, location, localName](
2732                                      const Symbol *t1, const Symbol *t2) {
2733     if (!t1 || !t2) {
2734       return true;
2735     } else {
2736       t1 = &t1->GetUltimate();
2737       t2 = &t2->GetUltimate();
2738       if (&t1 != &t2) {
2739         Say(location,
2740             "Generic interface '%s' has ambiguous derived types from modules '%s' and '%s'"_err_en_US,
2741             localName, t1->owner().GetName().value(),
2742             t2->owner().GetName().value());
2743         return false;
2744       }
2745     }
2746   }};
2747 
2748   auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
2749   const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
2750   auto combine{false};
2751   if (localGeneric) {
2752     if (useGeneric) {
2753       if (!checkAmbiguousDerivedType(
2754               localGeneric->derivedType(), useGeneric->derivedType())) {
2755         return;
2756       }
2757       combine = true;
2758     } else if (useUltimate.has<DerivedTypeDetails>()) {
2759       if (checkAmbiguousDerivedType(
2760               &useUltimate, localGeneric->derivedType())) {
2761         combine = true;
2762       } else {
2763         return;
2764       }
2765     } else if (&useUltimate == &BypassGeneric(localUltimate)) {
2766       return; // nothing to do; used subprogram is local's specific
2767     }
2768   } else if (useGeneric) {
2769     if (localUltimate.has<DerivedTypeDetails>()) {
2770       if (checkAmbiguousDerivedType(
2771               &localUltimate, useGeneric->derivedType())) {
2772         combine = true;
2773       } else {
2774         return;
2775       }
2776     } else if (&localUltimate == &BypassGeneric(useUltimate).GetUltimate()) {
2777       // Local is the specific of the used generic; replace it.
2778       EraseSymbol(localSymbol);
2779       Symbol &newSymbol{MakeSymbol(localName,
2780           useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2781           UseDetails{localName, useUltimate})};
2782       newSymbol.flags() = useSymbol.flags();
2783       return;
2784     }
2785   }
2786   if (!combine) {
2787     if (localSymbol.has<UseDetails>() || localSymbol.has<GenericDetails>()) {
2788       ConvertToUseError(localSymbol, location, *useModuleScope_);
2789     } else {
2790       Say(location,
2791           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2792           localName)
2793           .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2794               localName);
2795     }
2796     return;
2797   }
2798 
2799   // Two items are being use-associated from different modules
2800   // to the same local name.  At least one of them must be a generic,
2801   // and the other one can be a generic or a derived type.
2802   // (It could also have been the specific of the generic, but those
2803   // cases are handled above without needing to make a local copy of the
2804   // generic.)
2805 
2806   if (localGeneric) {
2807     if (localSymbol.has<UseDetails>()) {
2808       // Create a local copy of a previously use-associated generic so that
2809       // it can be locally extended without corrupting the original.
2810       GenericDetails generic;
2811       generic.CopyFrom(*localGeneric);
2812       EraseSymbol(localSymbol);
2813       Symbol &newSymbol{MakeSymbol(
2814           localSymbol.name(), localSymbol.attrs(), std::move(generic))};
2815       newSymbol.flags() = localSymbol.flags();
2816       localGeneric = &newSymbol.get<GenericDetails>();
2817       localGeneric->AddUse(localSymbol);
2818     }
2819     if (useGeneric) {
2820       // Combine two use-associated generics
2821       localSymbol.attrs() =
2822           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2823       localSymbol.flags() = useSymbol.flags();
2824       AddGenericUse(*localGeneric, localName, useUltimate);
2825       localGeneric->CopyFrom(*useGeneric);
2826     } else {
2827       CHECK(useUltimate.has<DerivedTypeDetails>());
2828       localGeneric->set_derivedType(
2829           AddGenericUse(*localGeneric, localName, useUltimate));
2830     }
2831   } else {
2832     CHECK(useGeneric && localUltimate.has<DerivedTypeDetails>());
2833     CHECK(localSymbol.has<UseDetails>());
2834     // Create a local copy of the use-associated generic, then extend it
2835     // with the local derived type.
2836     GenericDetails generic;
2837     generic.CopyFrom(*useGeneric);
2838     EraseSymbol(localSymbol);
2839     Symbol &newSymbol{MakeSymbol(localName,
2840         useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2841         std::move(generic))};
2842     newSymbol.flags() = useUltimate.flags();
2843     auto &newUseGeneric{newSymbol.get<GenericDetails>()};
2844     AddGenericUse(newUseGeneric, localName, useUltimate);
2845     newUseGeneric.AddUse(localSymbol);
2846     newUseGeneric.set_derivedType(localSymbol);
2847   }
2848 }
2849 
2850 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2851   if (useModuleScope_) {
2852     const auto &name{info.symbolName()};
2853     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2854     info.Resolve(rename.use);
2855   }
2856 }
2857 
2858 // Create a UseDetails symbol for this USE and add it to generic
2859 Symbol &ModuleVisitor::AddGenericUse(
2860     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2861   Symbol &newSymbol{
2862       currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol})};
2863   generic.AddUse(newSymbol);
2864   return newSymbol;
2865 }
2866 
2867 // Enforce C1406
2868 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2869     SourceName name, bool isIntrinsic) {
2870   if (isIntrinsic) {
2871     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2872         iter != explicitNonIntrinsicUses_.end()) {
2873       Say(name,
2874           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2875           name)
2876           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2877     }
2878     explicitIntrinsicUses_.insert(name);
2879   } else {
2880     if (auto iter{explicitIntrinsicUses_.find(name)};
2881         iter != explicitIntrinsicUses_.end()) {
2882       Say(name,
2883           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2884           name)
2885           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2886     }
2887     explicitNonIntrinsicUses_.insert(name);
2888   }
2889 }
2890 
2891 bool ModuleVisitor::BeginSubmodule(
2892     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2893   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2894   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2895   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2896   if (!ancestor) {
2897     return false;
2898   }
2899   Scope *parentScope{parentName
2900           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2901           : ancestor};
2902   if (!parentScope) {
2903     return false;
2904   }
2905   PushScope(*parentScope); // submodule is hosted in parent
2906   BeginModule(name, true);
2907   if (!ancestor->AddSubmodule(name.source, currScope())) {
2908     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2909         ancestorName.source, name.source);
2910   }
2911   return true;
2912 }
2913 
2914 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2915   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2916   auto &details{symbol.get<ModuleDetails>()};
2917   PushScope(Scope::Kind::Module, &symbol);
2918   details.set_scope(&currScope());
2919   defaultAccess_ = Attr::PUBLIC;
2920   prevAccessStmt_ = std::nullopt;
2921 }
2922 
2923 // Find a module or submodule by name and return its scope.
2924 // If ancestor is present, look for a submodule of that ancestor module.
2925 // May have to read a .mod file to find it.
2926 // If an error occurs, report it and return nullptr.
2927 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2928     std::optional<bool> isIntrinsic, Scope *ancestor) {
2929   ModFileReader reader{context()};
2930   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2931   if (!scope) {
2932     return nullptr;
2933   }
2934   if (scope->kind() != Scope::Kind::Module) {
2935     Say(name, "'%s' is not a module"_err_en_US);
2936     return nullptr;
2937   }
2938   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2939     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2940   }
2941   Resolve(name, scope->symbol());
2942   return scope;
2943 }
2944 
2945 void ModuleVisitor::ApplyDefaultAccess() {
2946   for (auto &pair : currScope()) {
2947     Symbol &symbol = *pair.second;
2948     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2949       symbol.attrs().set(defaultAccess_);
2950     }
2951   }
2952 }
2953 
2954 // InterfaceVistor implementation
2955 
2956 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2957   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2958   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2959   return BeginAttrs();
2960 }
2961 
2962 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2963 
2964 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2965   genericInfo_.pop();
2966 }
2967 
2968 // Create a symbol in genericSymbol_ for this GenericSpec.
2969 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2970   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
2971     SetGenericSymbol(*symbol);
2972   }
2973   return false;
2974 }
2975 
2976 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2977   if (!isGeneric()) {
2978     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2979     return false;
2980   }
2981   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2982   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2983   AddSpecificProcs(names, kind);
2984   return false;
2985 }
2986 
2987 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2988   genericInfo_.emplace(/*isInterface*/ false);
2989   return true;
2990 }
2991 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2992   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2993     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2994   }
2995   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2996   AddSpecificProcs(names, ProcedureKind::Procedure);
2997   genericInfo_.pop();
2998 }
2999 
3000 bool InterfaceVisitor::inInterfaceBlock() const {
3001   return !genericInfo_.empty() && GetGenericInfo().isInterface;
3002 }
3003 bool InterfaceVisitor::isGeneric() const {
3004   return !genericInfo_.empty() && GetGenericInfo().symbol;
3005 }
3006 bool InterfaceVisitor::isAbstract() const {
3007   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
3008 }
3009 
3010 void InterfaceVisitor::AddSpecificProcs(
3011     const std::list<parser::Name> &names, ProcedureKind kind) {
3012   for (const auto &name : names) {
3013     specificProcs_.emplace(
3014         GetGenericInfo().symbol, std::make_pair(&name, kind));
3015   }
3016 }
3017 
3018 // By now we should have seen all specific procedures referenced by name in
3019 // this generic interface. Resolve those names to symbols.
3020 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
3021   auto &details{generic.get<GenericDetails>()};
3022   UnorderedSymbolSet symbolsSeen;
3023   for (const Symbol &symbol : details.specificProcs()) {
3024     symbolsSeen.insert(symbol.GetUltimate());
3025   }
3026   auto range{specificProcs_.equal_range(&generic)};
3027   for (auto it{range.first}; it != range.second; ++it) {
3028     const parser::Name *name{it->second.first};
3029     auto kind{it->second.second};
3030     const auto *symbol{FindSymbol(*name)};
3031     if (!symbol) {
3032       Say(*name, "Procedure '%s' not found"_err_en_US);
3033       continue;
3034     }
3035     const Symbol &specific{BypassGeneric(*symbol)};
3036     const Symbol &ultimate{specific.GetUltimate()};
3037     if (!ultimate.has<SubprogramDetails>() &&
3038         !ultimate.has<SubprogramNameDetails>()) {
3039       Say(*name, "'%s' is not a subprogram"_err_en_US);
3040       continue;
3041     }
3042     if (kind == ProcedureKind::ModuleProcedure) {
3043       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
3044         if (nd->kind() != SubprogramKind::Module) {
3045           Say(*name, "'%s' is not a module procedure"_err_en_US);
3046         }
3047       } else {
3048         // USE-associated procedure
3049         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
3050         CHECK(sd);
3051         if (ultimate.owner().kind() != Scope::Kind::Module ||
3052             sd->isInterface()) {
3053           Say(*name, "'%s' is not a module procedure"_err_en_US);
3054         }
3055       }
3056     }
3057     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
3058       // When a specific procedure is a USE association, that association
3059       // is saved in the generic's specifics, not its ultimate symbol,
3060       // so that module file output of interfaces can distinguish them.
3061       details.AddSpecificProc(specific, name->source);
3062     } else if (&specific == &ultimate) {
3063       Say(name->source,
3064           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
3065           name->source, MakeOpName(generic.name()));
3066     } else {
3067       Say(name->source,
3068           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
3069           ultimate.name(), ultimate.owner().GetName().value(),
3070           MakeOpName(generic.name()));
3071     }
3072   }
3073   specificProcs_.erase(range.first, range.second);
3074 }
3075 
3076 // Check that the specific procedures are all functions or all subroutines.
3077 // If there is a derived type with the same name they must be functions.
3078 // Set the corresponding flag on generic.
3079 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
3080   ResolveSpecificsInGeneric(generic);
3081   auto &details{generic.get<GenericDetails>()};
3082   if (auto *proc{details.CheckSpecific()}) {
3083     auto msg{
3084         "'%s' may not be the name of both a generic interface and a"
3085         " procedure unless it is a specific procedure of the generic"_err_en_US};
3086     if (proc->name().begin() > generic.name().begin()) {
3087       Say(proc->name(), std::move(msg));
3088     } else {
3089       Say(generic.name(), std::move(msg));
3090     }
3091   }
3092   auto &specifics{details.specificProcs()};
3093   if (specifics.empty()) {
3094     if (details.derivedType()) {
3095       generic.set(Symbol::Flag::Function);
3096     }
3097     return;
3098   }
3099   const Symbol &firstSpecific{specifics.front()};
3100   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
3101   for (const Symbol &specific : specifics) {
3102     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
3103       auto &msg{Say(generic.name(),
3104           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
3105       if (isFunction) {
3106         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
3107         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
3108       } else {
3109         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
3110         msg.Attach(specific.name(), "Function declaration"_en_US);
3111       }
3112     }
3113   }
3114   if (!isFunction && details.derivedType()) {
3115     SayDerivedType(generic.name(),
3116         "Generic interface '%s' may only contain functions due to derived type"
3117         " with same name"_err_en_US,
3118         *details.derivedType()->scope());
3119   }
3120   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
3121 }
3122 
3123 // SubprogramVisitor implementation
3124 
3125 // Return false if it is actually an assignment statement.
3126 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
3127   const auto &name{std::get<parser::Name>(x.t)};
3128   const DeclTypeSpec *resultType{nullptr};
3129   // Look up name: provides return type or tells us if it's an array
3130   if (auto *symbol{FindSymbol(name)}) {
3131     auto *details{symbol->detailsIf<EntityDetails>()};
3132     if (!details) {
3133       badStmtFuncFound_ = true;
3134       return false;
3135     }
3136     // TODO: check that attrs are compatible with stmt func
3137     resultType = details->type();
3138     symbol->details() = UnknownDetails{}; // will be replaced below
3139   }
3140   if (badStmtFuncFound_) {
3141     Say(name, "'%s' has not been declared as an array"_err_en_US);
3142     return true;
3143   }
3144   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
3145   symbol.set(Symbol::Flag::StmtFunction);
3146   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
3147   auto &details{symbol.get<SubprogramDetails>()};
3148   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
3149     ObjectEntityDetails dummyDetails{true};
3150     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
3151       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
3152         if (d->type()) {
3153           dummyDetails.set_type(*d->type());
3154         }
3155       }
3156     }
3157     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
3158     ApplyImplicitRules(dummy);
3159     details.add_dummyArg(dummy);
3160   }
3161   ObjectEntityDetails resultDetails;
3162   if (resultType) {
3163     resultDetails.set_type(*resultType);
3164   }
3165   resultDetails.set_funcResult(true);
3166   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
3167   ApplyImplicitRules(result);
3168   details.set_result(result);
3169   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
3170   Walk(parsedExpr);
3171   // The analysis of the expression that constitutes the body of the
3172   // statement function is deferred to FinishSpecificationPart() so that
3173   // all declarations and implicit typing are complete.
3174   PopScope();
3175   return true;
3176 }
3177 
3178 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3179   if (suffix.resultName) {
3180     if (IsFunction(currScope())) {
3181       if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3182         if (info->inFunctionStmt) {
3183           info->resultName = &suffix.resultName.value();
3184         } else {
3185           // will check the result name in Post(EntryStmt)
3186         }
3187       }
3188     } else {
3189       Message &msg{Say(*suffix.resultName,
3190           "RESULT(%s) may appear only in a function"_err_en_US)};
3191       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3192         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3193       }
3194     }
3195   }
3196   return true;
3197 }
3198 
3199 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3200   // Save this to process after UseStmt and ImplicitPart
3201   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3202     FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3203     if (info.parsedType) { // C1543
3204       Say(currStmtSource().value(),
3205           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3206       return false;
3207     } else {
3208       info.parsedType = parsedType;
3209       info.source = currStmtSource();
3210       return false;
3211     }
3212   } else {
3213     return true;
3214   }
3215 }
3216 
3217 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3218   const auto &name{std::get<parser::Name>(
3219       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3220   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3221 }
3222 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
3223   EndSubprogram();
3224 }
3225 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3226   const auto &name{std::get<parser::Name>(
3227       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3228   return BeginSubprogram(name, Symbol::Flag::Function);
3229 }
3230 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
3231   EndSubprogram();
3232 }
3233 
3234 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
3235   return BeginAttrs();
3236 }
3237 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3238   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3239   CHECK(!info.inFunctionStmt);
3240   info.inFunctionStmt = true;
3241   return BeginAttrs();
3242 }
3243 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3244 
3245 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
3246   const auto &name{std::get<parser::Name>(stmt.t)};
3247   auto &details{PostSubprogramStmt(name)};
3248   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3249     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3250       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3251       details.add_dummyArg(dummy);
3252     } else {
3253       details.add_alternateReturn();
3254     }
3255   }
3256 }
3257 
3258 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3259   const auto &name{std::get<parser::Name>(stmt.t)};
3260   auto &details{PostSubprogramStmt(name)};
3261   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3262     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3263     details.add_dummyArg(dummy);
3264   }
3265   const parser::Name *funcResultName;
3266   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3267   CHECK(info.inFunctionStmt);
3268   info.inFunctionStmt = false;
3269   if (info.resultName && info.resultName->source != name.source) {
3270     // Note that RESULT is ignored if it has the same name as the function.
3271     funcResultName = info.resultName;
3272   } else {
3273     EraseSymbol(name); // was added by PushSubprogramScope
3274     funcResultName = &name;
3275   }
3276   // add function result to function scope
3277   if (details.isFunction()) {
3278     CHECK(context().HasError(currScope().symbol()));
3279   } else {
3280     // add function result to function scope
3281     EntityDetails funcResultDetails;
3282     funcResultDetails.set_funcResult(true);
3283     Symbol &result{MakeSymbol(*funcResultName, std::move(funcResultDetails))};
3284     info.resultSymbol = &result;
3285     details.set_result(result);
3286   }
3287   // C1560.
3288   if (info.resultName && info.resultName->source == name.source) {
3289     Say(info.resultName->source,
3290         "The function name should not appear in RESULT, references to '%s' "
3291         "inside the function will be considered as references to the "
3292         "result only"_warn_en_US,
3293         name.source);
3294     // RESULT name was ignored above, the only side effect from doing so will be
3295     // the inability to make recursive calls. The related parser::Name is still
3296     // resolved to the created function result symbol because every parser::Name
3297     // should be resolved to avoid internal errors.
3298     Resolve(*info.resultName, info.resultSymbol);
3299   }
3300   name.symbol = currScope().symbol(); // must not be function result symbol
3301   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3302   // has a RESULT() suffix.
3303   info.resultName = nullptr;
3304 }
3305 
3306 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3307     const parser::Name &name) {
3308   Symbol &symbol{*currScope().symbol()};
3309   auto &subp{symbol.get<SubprogramDetails>()};
3310   SetBindNameOn(symbol);
3311   CHECK(name.source == symbol.name() ||
3312       (subp.bindName() && symbol.owner().IsGlobal() &&
3313           context().IsTempName(symbol.name().ToString())));
3314   symbol.attrs() |= EndAttrs();
3315   if (symbol.attrs().test(Attr::MODULE)) {
3316     symbol.attrs().set(Attr::EXTERNAL, false);
3317   }
3318   return symbol.get<SubprogramDetails>();
3319 }
3320 
3321 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3322   auto attrs{EndAttrs()}; // needs to be called even if early return
3323   Scope &inclusiveScope{InclusiveScope()};
3324   const Symbol *subprogram{inclusiveScope.symbol()};
3325   if (!subprogram) {
3326     CHECK(context().AnyFatalError());
3327     return;
3328   }
3329   const auto &name{std::get<parser::Name>(stmt.t)};
3330   const parser::Name *resultName{nullptr};
3331   if (const auto &maybeSuffix{
3332           std::get<std::optional<parser::Suffix>>(stmt.t)}) {
3333     resultName = common::GetPtrFromOptional(maybeSuffix->resultName);
3334   }
3335   bool inFunction{IsFunction(currScope())};
3336   if (resultName) { // RESULT(result) is present
3337     if (!inFunction) {
3338       // error was already emitted for the suffix
3339     } else if (resultName->source == subprogram->name()) { // C1574
3340       Say2(resultName->source,
3341           "RESULT(%s) may not have the same name as the function"_err_en_US,
3342           subprogram->name(), "Containing function"_en_US);
3343     } else if (const Symbol *
3344         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
3345       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
3346         if (details->entryScope() == &inclusiveScope) {
3347           Say2(resultName->source,
3348               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3349               symbol->name(), "Conflicting ENTRY"_en_US);
3350         }
3351       }
3352     }
3353     if (Symbol * symbol{FindSymbol(name)}) { // C1570
3354       // When RESULT() appears, ENTRY name can't have been already declared
3355       if (inclusiveScope.Contains(symbol->owner())) {
3356         Say2(name,
3357             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
3358             *symbol, "Previous declaration of '%s'"_en_US);
3359       }
3360     }
3361     if (resultName->source == name.source) {
3362       // ignore RESULT() hereafter when it's the same name as the ENTRY
3363       resultName = nullptr;
3364     }
3365   }
3366   SubprogramDetails entryDetails;
3367   entryDetails.set_entryScope(inclusiveScope);
3368   if (inFunction) {
3369     // Create the entity to hold the function result, if necessary.
3370     Symbol *resultSymbol{nullptr};
3371     auto &effectiveResultName{*(resultName ? resultName : &name)};
3372     resultSymbol = FindInScope(currScope(), effectiveResultName);
3373     if (resultSymbol) { // C1574
3374       common::visit(
3375           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
3376               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
3377               [](ProcEntityDetails &x) { x.set_funcResult(true); },
3378               [&](const auto &) {
3379                 Say2(effectiveResultName.source,
3380                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
3381                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
3382                 context().SetError(*resultSymbol);
3383               }},
3384           resultSymbol->details());
3385     } else if (inExecutionPart_) {
3386       ObjectEntityDetails entity;
3387       entity.set_funcResult(true);
3388       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3389       ApplyImplicitRules(*resultSymbol);
3390     } else {
3391       EntityDetails entity;
3392       entity.set_funcResult(true);
3393       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3394     }
3395     if (!resultName) {
3396       name.symbol = nullptr; // symbol will be used for entry point below
3397     }
3398     entryDetails.set_result(*resultSymbol);
3399   }
3400 
3401   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3402     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3403       Symbol *dummy{FindSymbol(*dummyName)};
3404       if (dummy) {
3405         common::visit(
3406             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3407                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3408                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3409                 [](SubprogramDetails &x) { x.set_isDummy(); },
3410                 [&](const auto &) {
3411                   Say2(dummyName->source,
3412                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3413                       dummy->name(), "Previous declaration of '%s'"_en_US);
3414                 }},
3415             dummy->details());
3416       } else {
3417         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3418         if (inExecutionPart_) {
3419           ApplyImplicitRules(*dummy);
3420         }
3421       }
3422       entryDetails.add_dummyArg(*dummy);
3423     } else {
3424       if (inFunction) { // C1573
3425         Say(name,
3426             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3427         break;
3428       }
3429       entryDetails.add_alternateReturn();
3430     }
3431   }
3432 
3433   Symbol::Flag subpFlag{
3434       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
3435   Scope &outer{inclusiveScope.parent()}; // global or module scope
3436   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3437     attrs.set(Attr::PUBLIC);
3438   }
3439   if (Symbol * extant{FindSymbol(outer, name)}) {
3440     if (!HandlePreviousCalls(name, *extant, subpFlag)) {
3441       if (outer.IsGlobal()) {
3442         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
3443             *extant, "Previous definition of '%s'"_en_US);
3444       } else {
3445         SayAlreadyDeclared(name, *extant);
3446       }
3447       return;
3448     }
3449   }
3450 
3451   Symbol *entrySymbol{&MakeSymbol(outer, name.source, attrs)};
3452   if (auto *generic{entrySymbol->detailsIf<GenericDetails>()}) {
3453     CHECK(generic->specific());
3454     entrySymbol = generic->specific();
3455   }
3456   entrySymbol->set_details(std::move(entryDetails));
3457   SetBindNameOn(*entrySymbol);
3458   entrySymbol->set(subpFlag);
3459   Resolve(name, *entrySymbol);
3460 }
3461 
3462 // A subprogram declared with MODULE PROCEDURE
3463 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3464   auto *symbol{FindSymbol(name)};
3465   if (symbol && symbol->has<SubprogramNameDetails>()) {
3466     symbol = FindSymbol(currScope().parent(), name);
3467   }
3468   if (!IsSeparateModuleProcedureInterface(symbol)) {
3469     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3470     return false;
3471   }
3472   if (symbol->owner() == currScope() && symbol->scope()) {
3473     // This is a MODULE PROCEDURE whose interface appears in its host.
3474     // Convert the module procedure's interface into a subprogram.
3475     SetScope(DEREF(symbol->scope()));
3476     symbol->get<SubprogramDetails>().set_isInterface(false);
3477     if (IsFunction(*symbol)) {
3478       funcResultStack().Push(); // just to be popped later
3479     }
3480   } else {
3481     // Copy the interface into a new subprogram scope.
3482     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3483     PushScope(Scope::Kind::Subprogram, &newSymbol);
3484     const auto &details{symbol->get<SubprogramDetails>()};
3485     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3486     newDetails.set_moduleInterface(*symbol);
3487     for (const Symbol *dummyArg : details.dummyArgs()) {
3488       if (!dummyArg) {
3489         newDetails.add_alternateReturn();
3490       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3491         newDetails.add_dummyArg(*copy);
3492       }
3493     }
3494     if (details.isFunction()) {
3495       currScope().erase(symbol->name());
3496       newDetails.set_result(*currScope().CopySymbol(details.result()));
3497       funcResultStack().Push(); // just to be popped later
3498     }
3499   }
3500   return true;
3501 }
3502 
3503 // A subprogram or interface declared with SUBROUTINE or FUNCTION
3504 bool SubprogramVisitor::BeginSubprogram(const parser::Name &name,
3505     Symbol::Flag subpFlag, bool hasModulePrefix,
3506     const parser::LanguageBindingSpec *bindingSpec) {
3507   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3508     Say(name,
3509         "'%s' is a MODULE procedure which must be declared within a "
3510         "MODULE or SUBMODULE"_err_en_US);
3511     return false;
3512   }
3513   Symbol *moduleInterface{nullptr};
3514   if (hasModulePrefix && !inInterfaceBlock()) {
3515     moduleInterface = FindSymbol(currScope(), name);
3516     if (IsSeparateModuleProcedureInterface(moduleInterface)) {
3517       // Subprogram is MODULE FUNCTION or MODULE SUBROUTINE with an interface
3518       // previously defined in the same scope.
3519       currScope().erase(moduleInterface->name());
3520     } else {
3521       moduleInterface = nullptr;
3522     }
3523     if (!moduleInterface) {
3524       moduleInterface = FindSymbol(currScope().parent(), name);
3525       if (!IsSeparateModuleProcedureInterface(moduleInterface)) {
3526         Say(name,
3527             "'%s' was not declared a separate module procedure"_err_en_US);
3528         return false;
3529       }
3530     }
3531   }
3532   Symbol &newSymbol{PushSubprogramScope(name, subpFlag, bindingSpec)};
3533   if (moduleInterface) {
3534     newSymbol.get<SubprogramDetails>().set_moduleInterface(*moduleInterface);
3535     if (moduleInterface->attrs().test(Attr::PRIVATE)) {
3536       newSymbol.attrs().set(Attr::PRIVATE);
3537     } else if (moduleInterface->attrs().test(Attr::PUBLIC)) {
3538       newSymbol.attrs().set(Attr::PUBLIC);
3539     }
3540   }
3541   if (IsFunction(currScope())) {
3542     funcResultStack().Push();
3543   }
3544   return true;
3545 }
3546 
3547 void SubprogramVisitor::EndSubprogram() {
3548   if (IsFunction(currScope())) {
3549     funcResultStack().Pop();
3550   }
3551   PopScope();
3552 }
3553 
3554 bool SubprogramVisitor::HandlePreviousCalls(
3555     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3556   // If the extant symbol is a generic, check its homonymous specific
3557   // procedure instead if it has one.
3558   if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
3559     return generic->specific() &&
3560         HandlePreviousCalls(name, *generic->specific(), subpFlag);
3561   } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3562              !proc->isDummy() &&
3563              !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3564     // There's a symbol created for previous calls to this subprogram or
3565     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3566     // obligation to rewrite symbol pointers in the parse tree.
3567     if (!symbol.test(subpFlag)) {
3568       Say2(name,
3569           subpFlag == Symbol::Flag::Function
3570               ? "'%s' was previously called as a subroutine"_err_en_US
3571               : "'%s' was previously called as a function"_err_en_US,
3572           symbol, "Previous call of '%s'"_en_US);
3573     }
3574     EntityDetails entity;
3575     if (proc->type()) {
3576       entity.set_type(*proc->type());
3577     }
3578     symbol.details() = std::move(entity);
3579     return true;
3580   } else {
3581     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3582   }
3583 }
3584 
3585 void SubprogramVisitor::CheckExtantProc(
3586     const parser::Name &name, Symbol::Flag subpFlag) {
3587   if (auto *prev{FindSymbol(name)}) {
3588     if (IsDummy(*prev)) {
3589     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3590       // Procedures in an INTERFACE block do not resolve to symbols
3591       // in scopes between the global scope and the current scope.
3592     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3593       SayAlreadyDeclared(name, *prev);
3594     }
3595   }
3596 }
3597 
3598 Symbol &SubprogramVisitor::PushSubprogramScope(const parser::Name &name,
3599     Symbol::Flag subpFlag, const parser::LanguageBindingSpec *bindingSpec) {
3600   Symbol *symbol{GetSpecificFromGeneric(name)};
3601   if (!symbol) {
3602     if (bindingSpec && currScope().IsGlobal() && bindingSpec->v) {
3603       // Create this new top-level subprogram with a binding label
3604       // in a new global scope, so that its symbol's name won't clash
3605       // with another symbol that has a distinct binding label.
3606       PushScope(Scope::Kind::Global,
3607           &MakeSymbol(context().GetTempName(currScope()), Attrs{},
3608               MiscDetails{MiscDetails::Kind::ScopeName}));
3609     }
3610     CheckExtantProc(name, subpFlag);
3611     symbol = &MakeSymbol(name, SubprogramDetails{});
3612   }
3613   symbol->ReplaceName(name.source);
3614   symbol->set(subpFlag);
3615   PushScope(Scope::Kind::Subprogram, symbol);
3616   auto &details{symbol->get<SubprogramDetails>()};
3617   if (inInterfaceBlock()) {
3618     details.set_isInterface();
3619     if (isAbstract()) {
3620       symbol->attrs().set(Attr::ABSTRACT);
3621     } else {
3622       MakeExternal(*symbol);
3623     }
3624     if (isGeneric()) {
3625       Symbol &genericSymbol{GetGenericSymbol()};
3626       if (genericSymbol.has<GenericDetails>()) {
3627         genericSymbol.get<GenericDetails>().AddSpecificProc(
3628             *symbol, name.source);
3629       } else {
3630         CHECK(context().HasError(genericSymbol));
3631       }
3632     }
3633     set_inheritFromParent(false);
3634   }
3635   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3636   return *symbol;
3637 }
3638 
3639 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3640   if (auto *prev{FindSymbol(name)}) {
3641     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3642       if (prev->test(Symbol::Flag::Subroutine) ||
3643           prev->test(Symbol::Flag::Function)) {
3644         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3645             "Previous call of '%s'"_en_US);
3646       }
3647       EraseSymbol(name);
3648     }
3649   }
3650   if (name.source.empty()) {
3651     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3652     PushScope(Scope::Kind::BlockData, nullptr);
3653   } else {
3654     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3655   }
3656 }
3657 
3658 // If name is a generic, return specific subprogram with the same name.
3659 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3660   if (auto *symbol{FindSymbol(name)}) {
3661     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3662       // found generic, want subprogram
3663       auto *specific{details->specific()};
3664       if (!specific) {
3665         specific =
3666             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3667         if (details->derivedType()) {
3668           // A specific procedure with the same name as a derived type
3669           SayAlreadyDeclared(name, *details->derivedType());
3670         } else {
3671           details->set_specific(Resolve(name, *specific));
3672         }
3673       } else if (isGeneric()) {
3674         SayAlreadyDeclared(name, *specific);
3675       }
3676       if (!specific->has<SubprogramDetails>()) {
3677         specific->set_details(SubprogramDetails{});
3678       }
3679       return specific;
3680     }
3681   }
3682   return nullptr;
3683 }
3684 
3685 // DeclarationVisitor implementation
3686 
3687 bool DeclarationVisitor::BeginDecl() {
3688   BeginDeclTypeSpec();
3689   BeginArraySpec();
3690   return BeginAttrs();
3691 }
3692 void DeclarationVisitor::EndDecl() {
3693   EndDeclTypeSpec();
3694   EndArraySpec();
3695   EndAttrs();
3696 }
3697 
3698 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3699   const auto *details{
3700       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3701   if (!details) {
3702     return false;
3703   }
3704   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3705   for (const auto &[location, module] : details->occurrences()) {
3706     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3707         name.source, module->GetName().value());
3708   }
3709   context().SetError(*name.symbol);
3710   return true;
3711 }
3712 
3713 // Report error if accessibility of symbol doesn't match isPrivate.
3714 void DeclarationVisitor::CheckAccessibility(
3715     const SourceName &name, bool isPrivate, Symbol &symbol) {
3716   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3717     Say2(name,
3718         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3719         symbol, "Previous declaration of '%s'"_en_US);
3720   }
3721 }
3722 
3723 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3724   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3725     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3726       if (typeSpec->category() == DeclTypeSpec::Character) {
3727         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3728           Say("The type parameter LEN cannot be deferred without"
3729               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3730         }
3731       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3732         for (const auto &pair : derivedSpec->parameters()) {
3733           if (pair.second.isDeferred()) {
3734             Say(currStmtSource().value(),
3735                 "The value of type parameter '%s' cannot be deferred"
3736                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3737                 pair.first);
3738           }
3739         }
3740       }
3741     }
3742   }
3743   EndDecl();
3744 }
3745 
3746 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3747   DeclareObjectEntity(std::get<parser::Name>(x.t));
3748 }
3749 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3750   DeclareObjectEntity(std::get<parser::Name>(x.t));
3751 }
3752 
3753 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3754   // Defer inspection of initializers to Initialization() so that the
3755   // symbol being initialized will be available within the initialization
3756   // expression.
3757   return false;
3758 }
3759 
3760 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3761   const auto &name{std::get<parser::ObjectName>(x.t)};
3762   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3763   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3764   symbol.ReplaceName(name.source);
3765   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3766     if (ConvertToObjectEntity(symbol)) {
3767       Initialization(name, *init, false);
3768     }
3769   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3770     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3771   }
3772 }
3773 
3774 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3775   const auto &name{std::get<parser::Name>(x.t)};
3776   if (const auto &deferredShapeSpecs{
3777           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3778     CHECK(arraySpec().empty());
3779     BeginArraySpec();
3780     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3781     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3782     symbol.ReplaceName(name.source);
3783     EndArraySpec();
3784   } else {
3785     HandleAttributeStmt(Attr::POINTER, std::get<parser::Name>(x.t));
3786   }
3787 }
3788 
3789 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3790   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3791   auto &name{std::get<parser::Name>(x.t)};
3792   Symbol *symbol;
3793   if (kind == parser::BindEntity::Kind::Object) {
3794     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3795   } else {
3796     symbol = &MakeCommonBlockSymbol(name);
3797     symbol->attrs().set(Attr::BIND_C);
3798   }
3799   SetBindNameOn(*symbol);
3800   return false;
3801 }
3802 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3803   inOldStyleParameterStmt_ = true;
3804   Walk(x.v);
3805   inOldStyleParameterStmt_ = false;
3806   return false;
3807 }
3808 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3809   auto &name{std::get<parser::NamedConstant>(x.t).v};
3810   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3811   if (!ConvertToObjectEntity(symbol) ||
3812       symbol.test(Symbol::Flag::CrayPointer) ||
3813       symbol.test(Symbol::Flag::CrayPointee)) {
3814     SayWithDecl(
3815         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3816     return false;
3817   }
3818   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3819   auto &details{symbol.get<ObjectEntityDetails>()};
3820   if (inOldStyleParameterStmt_) {
3821     // non-standard extension PARAMETER statement (no parentheses)
3822     Walk(expr);
3823     auto folded{EvaluateExpr(expr)};
3824     if (details.type()) {
3825       SayWithDecl(name, symbol,
3826           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3827     } else if (folded) {
3828       auto at{expr.thing.value().source};
3829       if (evaluate::IsActuallyConstant(*folded)) {
3830         if (const auto *type{currScope().GetType(*folded)}) {
3831           if (type->IsPolymorphic()) {
3832             Say(at, "The expression must not be polymorphic"_err_en_US);
3833           } else if (auto shape{ToArraySpec(
3834                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3835             // The type of the named constant is assumed from the expression.
3836             details.set_type(*type);
3837             details.set_init(std::move(*folded));
3838             details.set_shape(std::move(*shape));
3839           } else {
3840             Say(at, "The expression must have constant shape"_err_en_US);
3841           }
3842         } else {
3843           Say(at, "The expression must have a known type"_err_en_US);
3844         }
3845       } else {
3846         Say(at, "The expression must be a constant of known type"_err_en_US);
3847       }
3848     }
3849   } else {
3850     // standard-conforming PARAMETER statement (with parentheses)
3851     ApplyImplicitRules(symbol);
3852     Walk(expr);
3853     if (auto converted{EvaluateNonPointerInitializer(
3854             symbol, expr, expr.thing.value().source)}) {
3855       details.set_init(std::move(*converted));
3856     }
3857   }
3858   return false;
3859 }
3860 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3861   const parser::Name &name{x.v};
3862   if (!FindSymbol(name)) {
3863     Say(name, "Named constant '%s' not found"_err_en_US);
3864   } else {
3865     CheckUseError(name);
3866   }
3867   return false;
3868 }
3869 
3870 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3871   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3872   Symbol *symbol{FindSymbol(name)};
3873   if (symbol && !symbol->has<UnknownDetails>()) {
3874     // Contrary to named constants appearing in a PARAMETER statement,
3875     // enumerator names should not have their type, dimension or any other
3876     // attributes defined before they are declared in the enumerator statement,
3877     // with the exception of accessibility.
3878     // This is not explicitly forbidden by the standard, but they are scalars
3879     // which type is left for the compiler to chose, so do not let users try to
3880     // tamper with that.
3881     SayAlreadyDeclared(name, *symbol);
3882     symbol = nullptr;
3883   } else {
3884     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3885     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3886     symbol->SetType(context().MakeNumericType(
3887         TypeCategory::Integer, evaluate::CInteger::kind));
3888   }
3889 
3890   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3891           enumerator.t)}) {
3892     Walk(*init); // Resolve names in expression before evaluation.
3893     if (auto value{EvaluateInt64(context(), *init)}) {
3894       // Cast all init expressions to C_INT so that they can then be
3895       // safely incremented (see 7.6 Note 2).
3896       enumerationState_.value = static_cast<int>(*value);
3897     } else {
3898       Say(name,
3899           "Enumerator value could not be computed "
3900           "from the given expression"_err_en_US);
3901       // Prevent resolution of next enumerators value
3902       enumerationState_.value = std::nullopt;
3903     }
3904   }
3905 
3906   if (symbol) {
3907     if (enumerationState_.value) {
3908       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3909           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3910     } else {
3911       context().SetError(*symbol);
3912     }
3913   }
3914 
3915   if (enumerationState_.value) {
3916     (*enumerationState_.value)++;
3917   }
3918   return false;
3919 }
3920 
3921 void DeclarationVisitor::Post(const parser::EnumDef &) {
3922   enumerationState_ = EnumeratorState{};
3923 }
3924 
3925 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3926   Attr attr{AccessSpecToAttr(x)};
3927   if (!NonDerivedTypeScope().IsModule()) { // C817
3928     Say(currStmtSource().value(),
3929         "%s attribute may only appear in the specification part of a module"_err_en_US,
3930         EnumToString(attr));
3931   }
3932   CheckAndSet(attr);
3933   return false;
3934 }
3935 
3936 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3937   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3938 }
3939 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3940   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3941 }
3942 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3943   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3944   for (const auto &name : x.v) {
3945     auto *symbol{FindSymbol(name)};
3946     if (!ConvertToProcEntity(DEREF(symbol))) {
3947       SayWithDecl(
3948           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3949     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
3950       Say(symbol->name(),
3951           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
3952           symbol->name());
3953     }
3954   }
3955   return false;
3956 }
3957 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3958   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3959   auto &names{std::get<std::list<parser::Name>>(x.t)};
3960   return CheckNotInBlock("INTENT") && // C1107
3961       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3962 }
3963 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3964   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3965   for (const auto &name : x.v) {
3966     auto &symbol{DEREF(FindSymbol(name))};
3967     if (symbol.has<GenericDetails>()) {
3968       // Generic interface is extending intrinsic; ok
3969     } else if (!symbol.has<HostAssocDetails>() &&
3970         !ConvertToProcEntity(symbol)) {
3971       SayWithDecl(
3972           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3973     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
3974       Say(symbol.name(),
3975           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3976           symbol.name());
3977     } else if (symbol.GetType()) {
3978       // These warnings are worded so that they should make sense in either
3979       // order.
3980       Say(symbol.name(),
3981           "Explicit type declaration ignored for intrinsic function '%s'"_warn_en_US,
3982           symbol.name())
3983           .Attach(name.source,
3984               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
3985               name.source);
3986     }
3987   }
3988   return false;
3989 }
3990 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3991   return CheckNotInBlock("OPTIONAL") && // C1107
3992       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3993 }
3994 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3995   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3996 }
3997 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3998   return CheckNotInBlock("VALUE") && // C1107
3999       HandleAttributeStmt(Attr::VALUE, x.v);
4000 }
4001 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
4002   return HandleAttributeStmt(Attr::VOLATILE, x.v);
4003 }
4004 // Handle a statement that sets an attribute on a list of names.
4005 bool DeclarationVisitor::HandleAttributeStmt(
4006     Attr attr, const std::list<parser::Name> &names) {
4007   for (const auto &name : names) {
4008     HandleAttributeStmt(attr, name);
4009   }
4010   return false;
4011 }
4012 Symbol &DeclarationVisitor::HandleAttributeStmt(
4013     Attr attr, const parser::Name &name) {
4014   if (attr == Attr::INTRINSIC) {
4015     if (!IsIntrinsic(name.source, std::nullopt)) {
4016       Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
4017     } else if (currScope().kind() == Scope::Kind::Subprogram ||
4018         currScope().kind() == Scope::Kind::Block) {
4019       if (auto *symbol{FindSymbol(name)}) {
4020         if (symbol->GetUltimate().has<GenericDetails>() &&
4021             symbol->owner() != currScope()) {
4022           // Declaring a name INTRINSIC when there is a generic
4023           // interface of the same name in the host scope.
4024           // Host-associate the generic and mark it INTRINSIC
4025           // rather than completely overriding the generic.
4026           symbol = &MakeHostAssocSymbol(name, *symbol);
4027           symbol->attrs().set(Attr::INTRINSIC);
4028           return *symbol;
4029         }
4030       }
4031     }
4032   }
4033   auto *symbol{FindInScope(name)};
4034   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
4035     // these can be set on a symbol that is host-assoc or use-assoc
4036     if (!symbol &&
4037         (currScope().kind() == Scope::Kind::Subprogram ||
4038             currScope().kind() == Scope::Kind::Block)) {
4039       if (auto *hostSymbol{FindSymbol(name)}) {
4040         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
4041       }
4042     }
4043   } else if (symbol && symbol->has<UseDetails>()) {
4044     Say(currStmtSource().value(),
4045         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
4046         EnumToString(attr), name.source);
4047     return *symbol;
4048   }
4049   if (!symbol) {
4050     symbol = &MakeSymbol(name, EntityDetails{});
4051   }
4052   symbol->attrs().set(attr);
4053   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
4054   return *symbol;
4055 }
4056 // C1107
4057 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
4058   if (currScope().kind() == Scope::Kind::Block) {
4059     Say(MessageFormattedText{
4060         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
4061     return false;
4062   } else {
4063     return true;
4064   }
4065 }
4066 
4067 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
4068   CHECK(objectDeclAttr_);
4069   const auto &name{std::get<parser::ObjectName>(x.t)};
4070   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
4071 }
4072 
4073 // Declare an entity not yet known to be an object or proc.
4074 Symbol &DeclarationVisitor::DeclareUnknownEntity(
4075     const parser::Name &name, Attrs attrs) {
4076   if (!arraySpec().empty() || !coarraySpec().empty()) {
4077     return DeclareObjectEntity(name, attrs);
4078   } else {
4079     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
4080     if (auto *type{GetDeclTypeSpec()}) {
4081       SetType(name, *type);
4082     }
4083     charInfo_.length.reset();
4084     SetBindNameOn(symbol);
4085     if (symbol.attrs().test(Attr::EXTERNAL)) {
4086       ConvertToProcEntity(symbol);
4087     }
4088     return symbol;
4089   }
4090 }
4091 
4092 bool DeclarationVisitor::HasCycle(
4093     const Symbol &procSymbol, const ProcInterface &interface) {
4094   SourceOrderedSymbolSet procsInCycle;
4095   procsInCycle.insert(procSymbol);
4096   const ProcInterface *thisInterface{&interface};
4097   bool haveInterface{true};
4098   while (haveInterface) {
4099     haveInterface = false;
4100     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
4101       if (procsInCycle.count(*interfaceSymbol) > 0) {
4102         for (const auto &procInCycle : procsInCycle) {
4103           Say(procInCycle->name(),
4104               "The interface for procedure '%s' is recursively "
4105               "defined"_err_en_US,
4106               procInCycle->name());
4107           context().SetError(*procInCycle);
4108         }
4109         return true;
4110       } else if (const auto *procDetails{
4111                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
4112         haveInterface = true;
4113         thisInterface = &procDetails->interface();
4114         procsInCycle.insert(*interfaceSymbol);
4115       }
4116     }
4117   }
4118   return false;
4119 }
4120 
4121 Symbol &DeclarationVisitor::DeclareProcEntity(
4122     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
4123   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
4124   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
4125     if (details->IsInterfaceSet()) {
4126       SayWithDecl(name, symbol,
4127           "The interface for procedure '%s' has already been "
4128           "declared"_err_en_US);
4129       context().SetError(symbol);
4130     } else if (HasCycle(symbol, interface)) {
4131       return symbol;
4132     } else if (interface.type()) {
4133       symbol.set(Symbol::Flag::Function);
4134     } else if (interface.symbol()) {
4135       if (interface.symbol()->test(Symbol::Flag::Function)) {
4136         symbol.set(Symbol::Flag::Function);
4137       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
4138         symbol.set(Symbol::Flag::Subroutine);
4139       }
4140     }
4141     details->set_interface(interface);
4142     SetBindNameOn(symbol);
4143     SetPassNameOn(symbol);
4144   }
4145   return symbol;
4146 }
4147 
4148 Symbol &DeclarationVisitor::DeclareObjectEntity(
4149     const parser::Name &name, Attrs attrs) {
4150   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
4151   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
4152     if (auto *type{GetDeclTypeSpec()}) {
4153       SetType(name, *type);
4154     }
4155     if (!arraySpec().empty()) {
4156       if (details->IsArray()) {
4157         if (!context().HasError(symbol)) {
4158           Say(name,
4159               "The dimensions of '%s' have already been declared"_err_en_US);
4160           context().SetError(symbol);
4161         }
4162       } else {
4163         details->set_shape(arraySpec());
4164       }
4165     }
4166     if (!coarraySpec().empty()) {
4167       if (details->IsCoarray()) {
4168         if (!context().HasError(symbol)) {
4169           Say(name,
4170               "The codimensions of '%s' have already been declared"_err_en_US);
4171           context().SetError(symbol);
4172         }
4173       } else {
4174         details->set_coshape(coarraySpec());
4175       }
4176     }
4177     SetBindNameOn(symbol);
4178   }
4179   ClearArraySpec();
4180   ClearCoarraySpec();
4181   charInfo_.length.reset();
4182   return symbol;
4183 }
4184 
4185 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
4186   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
4187 }
4188 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
4189   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
4190 }
4191 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
4192   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
4193 }
4194 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
4195   SetDeclTypeSpec(MakeLogicalType(x.kind));
4196 }
4197 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
4198   if (!charInfo_.length) {
4199     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
4200   }
4201   if (!charInfo_.kind) {
4202     charInfo_.kind =
4203         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
4204   }
4205   SetDeclTypeSpec(currScope().MakeCharacterType(
4206       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
4207   charInfo_ = {};
4208 }
4209 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
4210   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
4211   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
4212   if (intKind &&
4213       !evaluate::IsValidKindOfIntrinsicType(
4214           TypeCategory::Character, *intKind)) { // C715, C719
4215     Say(currStmtSource().value(),
4216         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
4217     charInfo_.kind = std::nullopt; // prevent further errors
4218   }
4219   if (x.length) {
4220     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
4221   }
4222 }
4223 void DeclarationVisitor::Post(const parser::CharLength &x) {
4224   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
4225     charInfo_.length = ParamValue{
4226         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
4227   } else {
4228     charInfo_.length = GetParamValue(
4229         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
4230   }
4231 }
4232 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
4233   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
4234     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
4235   }
4236 }
4237 
4238 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
4239   if (const auto *kind{std::get_if<
4240           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
4241           &x.u)}) {
4242     const parser::Name &name{kind->thing.thing.thing};
4243     if (!FindSymbol(name)) {
4244       Say(name, "Parameter '%s' not found"_err_en_US);
4245     }
4246   }
4247   return false;
4248 }
4249 
4250 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
4251   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
4252   return true;
4253 }
4254 
4255 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
4256   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
4257   if (const Symbol * derivedSymbol{derivedName.symbol}) {
4258     CheckForAbstractType(*derivedSymbol); // C706
4259   }
4260 }
4261 
4262 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4263   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4264   return true;
4265 }
4266 
4267 void DeclarationVisitor::Post(
4268     const parser::DeclarationTypeSpec::Class &parsedClass) {
4269   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4270   if (auto spec{ResolveDerivedType(typeName)};
4271       spec && !IsExtensibleType(&*spec)) { // C705
4272     SayWithDecl(typeName, *typeName.symbol,
4273         "Non-extensible derived type '%s' may not be used with CLASS"
4274         " keyword"_err_en_US);
4275   }
4276 }
4277 
4278 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4279   const auto &typeName{std::get<parser::Name>(x.t)};
4280   auto spec{ResolveDerivedType(typeName)};
4281   if (!spec) {
4282     return;
4283   }
4284   bool seenAnyName{false};
4285   for (const auto &typeParamSpec :
4286       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4287     const auto &optKeyword{
4288         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4289     std::optional<SourceName> name;
4290     if (optKeyword) {
4291       seenAnyName = true;
4292       name = optKeyword->v.source;
4293     } else if (seenAnyName) {
4294       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4295       continue;
4296     }
4297     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4298     // The expressions in a derived type specifier whose values define
4299     // non-defaulted type parameters are evaluated (folded) in the enclosing
4300     // scope.  The KIND/LEN distinction is resolved later in
4301     // DerivedTypeSpec::CookParameters().
4302     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4303     if (!param.isExplicit() || param.GetExplicit()) {
4304       spec->AddRawParamValue(optKeyword, std::move(param));
4305     }
4306   }
4307 
4308   // The DerivedTypeSpec *spec is used initially as a search key.
4309   // If it turns out to have the same name and actual parameter
4310   // value expressions as another DerivedTypeSpec in the current
4311   // scope does, then we'll use that extant spec; otherwise, when this
4312   // spec is distinct from all derived types previously instantiated
4313   // in the current scope, this spec will be moved into that collection.
4314   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4315   auto category{GetDeclTypeSpecCategory()};
4316   if (dtDetails.isForwardReferenced()) {
4317     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4318     SetDeclTypeSpec(type);
4319     return;
4320   }
4321   // Normalize parameters to produce a better search key.
4322   spec->CookParameters(GetFoldingContext());
4323   if (!spec->MightBeParameterized()) {
4324     spec->EvaluateParameters(context());
4325   }
4326   if (const DeclTypeSpec *
4327       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4328     // This derived type and parameter expressions (if any) are already present
4329     // in this scope.
4330     SetDeclTypeSpec(*extant);
4331   } else {
4332     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4333     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4334     if (derived.MightBeParameterized() &&
4335         currScope().IsParameterizedDerivedType()) {
4336       // Defer instantiation; use the derived type's definition's scope.
4337       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4338     } else if (&currScope() == spec->typeSymbol().scope()) {
4339       // Direct recursive use of a type in the definition of one of its
4340       // components: defer instantiation
4341     } else {
4342       auto restorer{
4343           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4344       derived.Instantiate(currScope());
4345     }
4346     SetDeclTypeSpec(type);
4347   }
4348   // Capture the DerivedTypeSpec in the parse tree for use in building
4349   // structure constructor expressions.
4350   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4351 }
4352 
4353 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4354   const auto &typeName{rec.v};
4355   if (auto spec{ResolveDerivedType(typeName)}) {
4356     spec->CookParameters(GetFoldingContext());
4357     spec->EvaluateParameters(context());
4358     if (const DeclTypeSpec *
4359         extant{currScope().FindInstantiatedDerivedType(
4360             *spec, DeclTypeSpec::TypeDerived)}) {
4361       SetDeclTypeSpec(*extant);
4362     } else {
4363       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4364           typeName.source);
4365     }
4366   }
4367 }
4368 
4369 // The descendents of DerivedTypeDef in the parse tree are visited directly
4370 // in this Pre() routine so that recursive use of the derived type can be
4371 // supported in the components.
4372 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4373   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4374   Walk(stmt);
4375   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4376   auto &scope{currScope()};
4377   CHECK(scope.symbol());
4378   CHECK(scope.symbol()->scope() == &scope);
4379   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4380   details.set_isForwardReferenced(false);
4381   std::set<SourceName> paramNames;
4382   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4383     details.add_paramName(paramName.source);
4384     auto *symbol{FindInScope(scope, paramName)};
4385     if (!symbol) {
4386       Say(paramName,
4387           "No definition found for type parameter '%s'"_err_en_US); // C742
4388       // No symbol for a type param.  Create one and mark it as containing an
4389       // error to improve subsequent semantic processing
4390       BeginAttrs();
4391       Symbol *typeParam{MakeTypeSymbol(
4392           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4393       context().SetError(*typeParam);
4394       EndAttrs();
4395     } else if (!symbol->has<TypeParamDetails>()) {
4396       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4397           *symbol, "Definition of '%s'"_en_US); // C741
4398     }
4399     if (!paramNames.insert(paramName.source).second) {
4400       Say(paramName,
4401           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4402     }
4403   }
4404   for (const auto &[name, symbol] : currScope()) {
4405     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4406       SayDerivedType(name,
4407           "'%s' is not a type parameter of this derived type"_err_en_US,
4408           currScope()); // C741
4409     }
4410   }
4411   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4412   const auto &componentDefs{
4413       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4414   Walk(componentDefs);
4415   if (derivedTypeInfo_.sequence) {
4416     details.set_sequence(true);
4417     if (componentDefs.empty()) { // C740
4418       Say(stmt.source,
4419           "A sequence type must have at least one component"_err_en_US);
4420     }
4421     if (!details.paramNames().empty()) { // C740
4422       Say(stmt.source,
4423           "A sequence type may not have type parameters"_err_en_US);
4424     }
4425     if (derivedTypeInfo_.extends) { // C735
4426       Say(stmt.source,
4427           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4428     }
4429   }
4430   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4431   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4432   derivedTypeInfo_ = {};
4433   PopScope();
4434   return false;
4435 }
4436 
4437 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4438   return BeginAttrs();
4439 }
4440 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4441   auto &name{std::get<parser::Name>(x.t)};
4442   // Resolve the EXTENDS() clause before creating the derived
4443   // type's symbol to foil attempts to recursively extend a type.
4444   auto *extendsName{derivedTypeInfo_.extends};
4445   std::optional<DerivedTypeSpec> extendsType{
4446       ResolveExtendsType(name, extendsName)};
4447   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4448   symbol.ReplaceName(name.source);
4449   derivedTypeInfo_.type = &symbol;
4450   PushScope(Scope::Kind::DerivedType, &symbol);
4451   if (extendsType) {
4452     // Declare the "parent component"; private if the type is.
4453     // Any symbol stored in the EXTENDS() clause is temporarily
4454     // hidden so that a new symbol can be created for the parent
4455     // component without producing spurious errors about already
4456     // existing.
4457     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4458     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4459     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4460       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4461       comp.attrs().set(
4462           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4463       comp.set(Symbol::Flag::ParentComp);
4464       DeclTypeSpec &type{currScope().MakeDerivedType(
4465           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4466       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4467       comp.SetType(type);
4468       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4469       details.add_component(comp);
4470     }
4471   }
4472   EndAttrs();
4473 }
4474 
4475 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4476   auto *type{GetDeclTypeSpec()};
4477   auto attr{std::get<common::TypeParamAttr>(x.t)};
4478   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4479     auto &name{std::get<parser::Name>(decl.t)};
4480     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4481       SetType(name, *type);
4482       if (auto &init{
4483               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4484         if (auto maybeExpr{EvaluateNonPointerInitializer(
4485                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4486           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4487             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4488           }
4489         }
4490       }
4491     }
4492   }
4493   EndDecl();
4494 }
4495 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4496   if (derivedTypeInfo_.extends) {
4497     Say(currStmtSource().value(),
4498         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4499   } else {
4500     derivedTypeInfo_.extends = &x.v;
4501   }
4502   return false;
4503 }
4504 
4505 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4506   if (!currScope().parent().IsModule()) {
4507     Say("PRIVATE is only allowed in a derived type that is"
4508         " in a module"_err_en_US); // C766
4509   } else if (derivedTypeInfo_.sawContains) {
4510     derivedTypeInfo_.privateBindings = true;
4511   } else if (!derivedTypeInfo_.privateComps) {
4512     derivedTypeInfo_.privateComps = true;
4513   } else {
4514     Say("PRIVATE may not appear more than once in"
4515         " derived type components"_warn_en_US); // C738
4516   }
4517   return false;
4518 }
4519 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4520   if (derivedTypeInfo_.sequence) {
4521     Say("SEQUENCE may not appear more than once in"
4522         " derived type components"_warn_en_US); // C738
4523   }
4524   derivedTypeInfo_.sequence = true;
4525   return false;
4526 }
4527 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4528   const auto &name{std::get<parser::Name>(x.t)};
4529   auto attrs{GetAttrs()};
4530   if (derivedTypeInfo_.privateComps &&
4531       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4532     attrs.set(Attr::PRIVATE);
4533   }
4534   if (const auto *declType{GetDeclTypeSpec()}) {
4535     if (const auto *derived{declType->AsDerived()}) {
4536       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4537         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4538           Say("Recursive use of the derived type requires "
4539               "POINTER or ALLOCATABLE"_err_en_US);
4540         }
4541       }
4542       // TODO: This would be more appropriate in CheckDerivedType()
4543       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4544         std::string ultimateName{it.BuildResultDesignatorName()};
4545         // Strip off the leading "%"
4546         if (ultimateName.length() > 1) {
4547           ultimateName.erase(0, 1);
4548           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4549             evaluate::AttachDeclaration(
4550                 Say(name.source,
4551                     "A component with a POINTER or ALLOCATABLE attribute may "
4552                     "not "
4553                     "be of a type with a coarray ultimate component (named "
4554                     "'%s')"_err_en_US,
4555                     ultimateName),
4556                 derived->typeSymbol());
4557           }
4558           if (!arraySpec().empty() || !coarraySpec().empty()) {
4559             evaluate::AttachDeclaration(
4560                 Say(name.source,
4561                     "An array or coarray component may not be of a type with a "
4562                     "coarray ultimate component (named '%s')"_err_en_US,
4563                     ultimateName),
4564                 derived->typeSymbol());
4565           }
4566         }
4567       }
4568     }
4569   }
4570   if (OkToAddComponent(name)) {
4571     auto &symbol{DeclareObjectEntity(name, attrs)};
4572     if (symbol.has<ObjectEntityDetails>()) {
4573       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4574         Initialization(name, *init, true);
4575       }
4576     }
4577     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4578   }
4579   ClearArraySpec();
4580   ClearCoarraySpec();
4581 }
4582 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4583   // Replace "%FILL" with a distinct generated name
4584   const auto &name{std::get<parser::Name>(x.t)};
4585   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4586   if (OkToAddComponent(name)) {
4587     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4588     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4589   }
4590   ClearArraySpec();
4591 }
4592 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4593   CHECK(!interfaceName_);
4594   return BeginDecl();
4595 }
4596 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4597   interfaceName_ = nullptr;
4598   EndDecl();
4599 }
4600 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4601   // Overrides parse tree traversal so as to handle attributes first,
4602   // so POINTER & ALLOCATABLE enable forward references to derived types.
4603   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4604   set_allowForwardReferenceToDerivedType(
4605       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4606   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4607   set_allowForwardReferenceToDerivedType(false);
4608   if (derivedTypeInfo_.sequence) { // C740
4609     if (const auto *declType{GetDeclTypeSpec()}) {
4610       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4611         if (GetAttrs().test(Attr::POINTER) &&
4612             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4613           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4614             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_port_en_US);
4615           }
4616         } else {
4617           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4618         }
4619       }
4620     }
4621   }
4622   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4623   return false;
4624 }
4625 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4626   CHECK(!interfaceName_);
4627   return true;
4628 }
4629 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4630   interfaceName_ = nullptr;
4631 }
4632 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4633   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4634     return !NameIsKnownOrIntrinsic(*name);
4635   }
4636   return true;
4637 }
4638 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4639   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4640     interfaceName_ = name;
4641     NoteInterfaceName(*name);
4642   }
4643 }
4644 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4645   const auto &name{std::get<parser::Name>(x.t)};
4646   ProcInterface interface;
4647   if (interfaceName_) {
4648     interface.set_symbol(*interfaceName_->symbol);
4649   } else if (auto *type{GetDeclTypeSpec()}) {
4650     interface.set_type(*type);
4651   }
4652   auto attrs{HandleSaveName(name.source, GetAttrs())};
4653   DerivedTypeDetails *dtDetails{nullptr};
4654   if (Symbol * symbol{currScope().symbol()}) {
4655     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4656   }
4657   if (!dtDetails) {
4658     attrs.set(Attr::EXTERNAL);
4659   }
4660   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4661   symbol.ReplaceName(name.source);
4662   if (dtDetails) {
4663     dtDetails->add_component(symbol);
4664   }
4665 }
4666 
4667 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4668   derivedTypeInfo_.sawContains = true;
4669   return true;
4670 }
4671 
4672 // Resolve binding names from type-bound generics, saved in genericBindings_.
4673 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4674   // track specifics seen for the current generic to detect duplicates:
4675   const Symbol *currGeneric{nullptr};
4676   std::set<SourceName> specifics;
4677   for (const auto &[generic, bindingName] : genericBindings_) {
4678     if (generic != currGeneric) {
4679       currGeneric = generic;
4680       specifics.clear();
4681     }
4682     auto [it, inserted]{specifics.insert(bindingName->source)};
4683     if (!inserted) {
4684       Say(*bindingName, // C773
4685           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4686           bindingName->source, generic->name())
4687           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4688       continue;
4689     }
4690     auto *symbol{FindInTypeOrParents(*bindingName)};
4691     if (!symbol) {
4692       Say(*bindingName, // C772
4693           "Binding name '%s' not found in this derived type"_err_en_US);
4694     } else if (!symbol->has<ProcBindingDetails>()) {
4695       SayWithDecl(*bindingName, *symbol, // C772
4696           "'%s' is not the name of a specific binding of this type"_err_en_US);
4697     } else {
4698       generic->get<GenericDetails>().AddSpecificProc(
4699           *symbol, bindingName->source);
4700     }
4701   }
4702   genericBindings_.clear();
4703 }
4704 
4705 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4706   if (derivedTypeInfo_.sequence) {
4707     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4708   }
4709 }
4710 
4711 void DeclarationVisitor::Post(
4712     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4713   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4714     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4715   }
4716   for (auto &declaration : x.declarations) {
4717     auto &bindingName{std::get<parser::Name>(declaration.t)};
4718     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4719     const parser::Name &procedureName{optName ? *optName : bindingName};
4720     Symbol *procedure{FindSymbol(procedureName)};
4721     if (!procedure) {
4722       procedure = NoteInterfaceName(procedureName);
4723     }
4724     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4725       SetPassNameOn(*s);
4726       if (GetAttrs().test(Attr::DEFERRED)) {
4727         context().SetError(*s);
4728       }
4729     }
4730   }
4731 }
4732 
4733 void DeclarationVisitor::CheckBindings(
4734     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4735   CHECK(currScope().IsDerivedType());
4736   for (auto &declaration : tbps.declarations) {
4737     auto &bindingName{std::get<parser::Name>(declaration.t)};
4738     if (Symbol * binding{FindInScope(bindingName)}) {
4739       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4740         const Symbol *procedure{FindSubprogram(details->symbol())};
4741         if (!CanBeTypeBoundProc(procedure)) {
4742           if (details->symbol().name() != binding->name()) {
4743             Say(binding->name(),
4744                 "The binding of '%s' ('%s') must be either an accessible "
4745                 "module procedure or an external procedure with "
4746                 "an explicit interface"_err_en_US,
4747                 binding->name(), details->symbol().name());
4748           } else {
4749             Say(binding->name(),
4750                 "'%s' must be either an accessible module procedure "
4751                 "or an external procedure with an explicit interface"_err_en_US,
4752                 binding->name());
4753           }
4754           context().SetError(*binding);
4755         }
4756       }
4757     }
4758   }
4759 }
4760 
4761 void DeclarationVisitor::Post(
4762     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4763   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4764     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4765   }
4766   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4767     for (auto &bindingName : x.bindingNames) {
4768       if (auto *s{
4769               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4770         SetPassNameOn(*s);
4771         if (!GetAttrs().test(Attr::DEFERRED)) {
4772           context().SetError(*s);
4773         }
4774       }
4775     }
4776   }
4777 }
4778 
4779 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4780   if (currScope().IsDerivedType() && currScope().symbol()) {
4781     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4782       for (const auto &subrName : x.v) {
4783         if (const auto *name{ResolveName(subrName)}) {
4784           auto pair{
4785               details->finals().emplace(name->source, DEREF(name->symbol))};
4786           if (!pair.second) { // C787
4787             Say(name->source,
4788                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4789                 name->source)
4790                 .Attach(pair.first->first,
4791                     "earlier appearance of this FINAL subroutine"_en_US);
4792           }
4793         }
4794       }
4795     }
4796   }
4797 }
4798 
4799 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4800   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4801   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4802   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4803   auto info{GenericSpecInfo{genericSpec.value()}};
4804   SourceName symbolName{info.symbolName()};
4805   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4806                             : derivedTypeInfo_.privateBindings};
4807   auto *genericSymbol{FindInScope(symbolName)};
4808   if (genericSymbol) {
4809     if (!genericSymbol->has<GenericDetails>()) {
4810       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4811     }
4812   } else {
4813     // look in parent types:
4814     Symbol *inheritedSymbol{nullptr};
4815     for (const auto &name : GetAllNames(context(), symbolName)) {
4816       inheritedSymbol = currScope().FindComponent(SourceName{name});
4817       if (inheritedSymbol) {
4818         break;
4819       }
4820     }
4821     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4822       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4823     }
4824   }
4825   if (genericSymbol) {
4826     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4827   } else {
4828     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4829     if (!genericSymbol) {
4830       return false;
4831     }
4832     if (isPrivate) {
4833       genericSymbol->attrs().set(Attr::PRIVATE);
4834     }
4835   }
4836   for (const parser::Name &bindingName : bindingNames) {
4837     genericBindings_.emplace(genericSymbol, &bindingName);
4838   }
4839   info.Resolve(genericSymbol);
4840   return false;
4841 }
4842 
4843 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4844 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4845   const auto &structureStatement{
4846       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4847   auto saveDerivedTypeInfo{derivedTypeInfo_};
4848   derivedTypeInfo_ = {};
4849   derivedTypeInfo_.isStructure = true;
4850   derivedTypeInfo_.sequence = true;
4851   Scope *previousStructure{nullptr};
4852   if (saveDerivedTypeInfo.isStructure) {
4853     previousStructure = &currScope();
4854     PopScope();
4855   }
4856   const parser::StructureStmt &structStmt{structureStatement.statement};
4857   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4858   if (!name) {
4859     // Construct a distinct generated name for an anonymous structure
4860     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4861     mutableName.emplace(
4862         parser::Name{context().GetTempName(currScope()), nullptr});
4863   }
4864   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4865   symbol.ReplaceName(name->source);
4866   symbol.get<DerivedTypeDetails>().set_sequence(true);
4867   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4868   derivedTypeInfo_.type = &symbol;
4869   PushScope(Scope::Kind::DerivedType, &symbol);
4870   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4871   Walk(fields);
4872   PopScope();
4873   // Complete the definition
4874   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4875   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4876   derivedTypeSpec.CookParameters(GetFoldingContext());
4877   derivedTypeSpec.EvaluateParameters(context());
4878   DeclTypeSpec &type{currScope().MakeDerivedType(
4879       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4880   type.derivedTypeSpec().Instantiate(currScope());
4881   // Restore previous structure definition context, if any
4882   derivedTypeInfo_ = saveDerivedTypeInfo;
4883   if (previousStructure) {
4884     PushScope(*previousStructure);
4885   }
4886   // Handle any entity declarations on the STRUCTURE statement
4887   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4888   if (!decls.empty()) {
4889     BeginDecl();
4890     SetDeclTypeSpec(type);
4891     Walk(decls);
4892     EndDecl();
4893   }
4894   return false;
4895 }
4896 
4897 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
4898   Say("not yet implemented: support for UNION"_err_en_US); // TODO
4899   return true;
4900 }
4901 
4902 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
4903   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4904           x.u)) {
4905     BeginDecl();
4906   }
4907   return true;
4908 }
4909 
4910 void DeclarationVisitor::Post(const parser::StructureField &x) {
4911   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4912           x.u)) {
4913     EndDecl();
4914   }
4915 }
4916 
4917 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4918   BeginDeclTypeSpec();
4919   return true;
4920 }
4921 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4922   EndDeclTypeSpec();
4923 }
4924 
4925 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4926   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4927   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4928   if (!type) {
4929     return false;
4930   }
4931   const DerivedTypeSpec *spec{type->AsDerived()};
4932   const Scope *typeScope{spec ? spec->scope() : nullptr};
4933   if (!typeScope) {
4934     return false;
4935   }
4936 
4937   // N.B C7102 is implicitly enforced by having inaccessible types not
4938   // being found in resolution.
4939   // More constraints are enforced in expression.cpp so that they
4940   // can apply to structure constructors that have been converted
4941   // from misparsed function references.
4942   for (const auto &component :
4943       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4944     // Visit the component spec expression, but not the keyword, since
4945     // we need to resolve its symbol in the scope of the derived type.
4946     Walk(std::get<parser::ComponentDataSource>(component.t));
4947     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4948       FindInTypeOrParents(*typeScope, kw->v);
4949     }
4950   }
4951   return false;
4952 }
4953 
4954 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4955   for (const parser::BasedPointer &bp : x.v) {
4956     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4957     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4958     auto *pointer{FindSymbol(pointerName)};
4959     if (!pointer) {
4960       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4961     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4962       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4963     } else if (pointer->Rank() > 0) {
4964       SayWithDecl(pointerName, *pointer,
4965           "Cray pointer '%s' must be a scalar"_err_en_US);
4966     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4967       Say(pointerName,
4968           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4969     }
4970     pointer->set(Symbol::Flag::CrayPointer);
4971     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4972         context().defaultKinds().subscriptIntegerKind())};
4973     const auto *type{pointer->GetType()};
4974     if (!type) {
4975       pointer->SetType(pointerType);
4976     } else if (*type != pointerType) {
4977       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4978           pointerName.source, pointerType.AsFortran());
4979     }
4980     if (ResolveName(pointeeName)) {
4981       Symbol &pointee{*pointeeName.symbol};
4982       if (pointee.has<UseDetails>()) {
4983         Say(pointeeName,
4984             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4985         continue;
4986       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4987         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4988         continue;
4989       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4990         Say(pointeeName,
4991             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4992       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4993         Say(pointeeName,
4994             "'%s' was already declared as a Cray pointee"_err_en_US);
4995       } else {
4996         pointee.set(Symbol::Flag::CrayPointee);
4997       }
4998       if (const auto *pointeeType{pointee.GetType()}) {
4999         if (const auto *derived{pointeeType->AsDerived()}) {
5000           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
5001             Say(pointeeName,
5002                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
5003           }
5004         }
5005       }
5006       // process the pointee array-spec, if present
5007       BeginArraySpec();
5008       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
5009       const auto &spec{arraySpec()};
5010       if (!spec.empty()) {
5011         auto &details{pointee.get<ObjectEntityDetails>()};
5012         if (details.shape().empty()) {
5013           details.set_shape(spec);
5014         } else {
5015           SayWithDecl(pointeeName, pointee,
5016               "Array spec was already declared for '%s'"_err_en_US);
5017         }
5018       }
5019       ClearArraySpec();
5020       currScope().add_crayPointer(pointeeName.source, *pointer);
5021     }
5022   }
5023   return false;
5024 }
5025 
5026 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
5027   if (!CheckNotInBlock("NAMELIST")) { // C1107
5028     return false;
5029   }
5030   const auto &groupName{std::get<parser::Name>(x.t)};
5031   auto *groupSymbol{FindInScope(groupName)};
5032   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
5033     groupSymbol = &MakeSymbol(groupName, NamelistDetails{});
5034     groupSymbol->ReplaceName(groupName.source);
5035   }
5036   // Name resolution of group items is deferred to FinishNamelists()
5037   // so that host association is handled correctly.
5038   GetDeferredDeclarationState(true)->namelistGroups.emplace_back(&x);
5039   return false;
5040 }
5041 
5042 void DeclarationVisitor::FinishNamelists() {
5043   if (auto *deferred{GetDeferredDeclarationState()}) {
5044     for (const parser::NamelistStmt::Group *group : deferred->namelistGroups) {
5045       if (auto *groupSymbol{FindInScope(std::get<parser::Name>(group->t))}) {
5046         if (auto *details{groupSymbol->detailsIf<NamelistDetails>()}) {
5047           for (const auto &name : std::get<std::list<parser::Name>>(group->t)) {
5048             auto *symbol{FindSymbol(name)};
5049             if (!symbol) {
5050               symbol = &MakeSymbol(name, ObjectEntityDetails{});
5051               ApplyImplicitRules(*symbol);
5052             } else if (!ConvertToObjectEntity(*symbol)) {
5053               SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
5054             }
5055             symbol->GetUltimate().set(Symbol::Flag::InNamelist);
5056             details->add_object(*symbol);
5057           }
5058         }
5059       }
5060     }
5061     deferred->namelistGroups.clear();
5062   }
5063 }
5064 
5065 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
5066   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
5067     auto *symbol{FindSymbol(*name)};
5068     if (!symbol) {
5069       Say(*name, "Namelist group '%s' not found"_err_en_US);
5070     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
5071       SayWithDecl(
5072           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
5073     }
5074   }
5075   return true;
5076 }
5077 
5078 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
5079   CheckNotInBlock("COMMON"); // C1107
5080   return true;
5081 }
5082 
5083 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
5084   BeginArraySpec();
5085   return true;
5086 }
5087 
5088 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
5089   const auto &name{std::get<parser::Name>(x.t)};
5090   DeclareObjectEntity(name);
5091   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
5092   if (!pair.second) {
5093     const SourceName &prev{*pair.first};
5094     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
5095         "Previous occurrence of '%s' in a COMMON block"_en_US);
5096   }
5097 }
5098 
5099 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
5100   // save equivalence sets to be processed after specification part
5101   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
5102     for (const std::list<parser::EquivalenceObject> &set : x.v) {
5103       specPartState_.equivalenceSets.push_back(&set);
5104     }
5105   }
5106   return false; // don't implicitly declare names yet
5107 }
5108 
5109 void DeclarationVisitor::CheckEquivalenceSets() {
5110   EquivalenceSets equivSets{context()};
5111   inEquivalenceStmt_ = true;
5112   for (const auto *set : specPartState_.equivalenceSets) {
5113     const auto &source{set->front().v.value().source};
5114     if (set->size() <= 1) { // R871
5115       Say(source, "Equivalence set must have more than one object"_err_en_US);
5116     }
5117     for (const parser::EquivalenceObject &object : *set) {
5118       const auto &designator{object.v.value()};
5119       // The designator was not resolved when it was encountered so do it now.
5120       // AnalyzeExpr causes array sections to be changed to substrings as needed
5121       Walk(designator);
5122       if (AnalyzeExpr(context(), designator)) {
5123         equivSets.AddToSet(designator);
5124       }
5125     }
5126     equivSets.FinishSet(source);
5127   }
5128   inEquivalenceStmt_ = false;
5129   for (auto &set : equivSets.sets()) {
5130     if (!set.empty()) {
5131       currScope().add_equivalenceSet(std::move(set));
5132     }
5133   }
5134   specPartState_.equivalenceSets.clear();
5135 }
5136 
5137 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
5138   if (x.v.empty()) {
5139     specPartState_.saveInfo.saveAll = currStmtSource();
5140     currScope().set_hasSAVE();
5141   } else {
5142     for (const parser::SavedEntity &y : x.v) {
5143       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
5144       const auto &name{std::get<parser::Name>(y.t)};
5145       if (kind == parser::SavedEntity::Kind::Common) {
5146         MakeCommonBlockSymbol(name);
5147         AddSaveName(specPartState_.saveInfo.commons, name.source);
5148       } else {
5149         HandleAttributeStmt(Attr::SAVE, name);
5150       }
5151     }
5152   }
5153   return false;
5154 }
5155 
5156 void DeclarationVisitor::CheckSaveStmts() {
5157   for (const SourceName &name : specPartState_.saveInfo.entities) {
5158     auto *symbol{FindInScope(name)};
5159     if (!symbol) {
5160       // error was reported
5161     } else if (specPartState_.saveInfo.saveAll) {
5162       // C889 - note that pgi, ifort, xlf do not enforce this constraint
5163       Say2(name,
5164           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
5165           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
5166     } else if (auto msg{CheckSaveAttr(*symbol)}) {
5167       Say(name, std::move(*msg));
5168       context().SetError(*symbol);
5169     } else {
5170       SetSaveAttr(*symbol);
5171     }
5172   }
5173   for (const SourceName &name : specPartState_.saveInfo.commons) {
5174     if (auto *symbol{currScope().FindCommonBlock(name)}) {
5175       auto &objects{symbol->get<CommonBlockDetails>().objects()};
5176       if (objects.empty()) {
5177         if (currScope().kind() != Scope::Kind::Block) {
5178           Say(name,
5179               "'%s' appears as a COMMON block in a SAVE statement but not in"
5180               " a COMMON statement"_err_en_US);
5181         } else { // C1108
5182           Say(name,
5183               "SAVE statement in BLOCK construct may not contain a"
5184               " common block name '%s'"_err_en_US);
5185         }
5186       } else {
5187         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
5188           SetSaveAttr(*object);
5189         }
5190       }
5191     }
5192   }
5193   if (specPartState_.saveInfo.saveAll) {
5194     // Apply SAVE attribute to applicable symbols
5195     for (auto pair : currScope()) {
5196       auto &symbol{*pair.second};
5197       if (!CheckSaveAttr(symbol)) {
5198         SetSaveAttr(symbol);
5199       }
5200     }
5201   }
5202   specPartState_.saveInfo = {};
5203 }
5204 
5205 // If SAVE attribute can't be set on symbol, return error message.
5206 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
5207     const Symbol &symbol) {
5208   if (IsDummy(symbol)) {
5209     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
5210   } else if (symbol.IsFuncResult()) {
5211     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
5212   } else if (symbol.has<ProcEntityDetails>() &&
5213       !symbol.attrs().test(Attr::POINTER)) {
5214     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
5215   } else if (IsAutomatic(symbol)) {
5216     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
5217   } else {
5218     return std::nullopt;
5219   }
5220 }
5221 
5222 // Record SAVEd names in specPartState_.saveInfo.entities.
5223 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
5224   if (attrs.test(Attr::SAVE)) {
5225     AddSaveName(specPartState_.saveInfo.entities, name);
5226   }
5227   return attrs;
5228 }
5229 
5230 // Record a name in a set of those to be saved.
5231 void DeclarationVisitor::AddSaveName(
5232     std::set<SourceName> &set, const SourceName &name) {
5233   auto pair{set.insert(name)};
5234   if (!pair.second) {
5235     Say2(name, "SAVE attribute was already specified on '%s'"_warn_en_US,
5236         *pair.first, "Previous specification of SAVE attribute"_en_US);
5237   }
5238 }
5239 
5240 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
5241 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
5242   if (!IsSaved(symbol)) {
5243     symbol.attrs().set(Attr::SAVE);
5244   }
5245 }
5246 
5247 // Check types of common block objects, now that they are known.
5248 void DeclarationVisitor::CheckCommonBlocks() {
5249   // check for empty common blocks
5250   for (const auto &pair : currScope().commonBlocks()) {
5251     const auto &symbol{*pair.second};
5252     if (symbol.get<CommonBlockDetails>().objects().empty() &&
5253         symbol.attrs().test(Attr::BIND_C)) {
5254       Say(symbol.name(),
5255           "'%s' appears as a COMMON block in a BIND statement but not in"
5256           " a COMMON statement"_err_en_US);
5257     }
5258   }
5259   // check objects in common blocks
5260   for (const auto &name : specPartState_.commonBlockObjects) {
5261     const auto *symbol{currScope().FindSymbol(name)};
5262     if (!symbol) {
5263       continue;
5264     }
5265     const auto &attrs{symbol->attrs()};
5266     if (attrs.test(Attr::ALLOCATABLE)) {
5267       Say(name,
5268           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
5269     } else if (attrs.test(Attr::BIND_C)) {
5270       Say(name,
5271           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
5272     } else if (IsDummy(*symbol)) {
5273       Say(name,
5274           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5275     } else if (symbol->IsFuncResult()) {
5276       Say(name,
5277           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5278     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5279       if (type->category() == DeclTypeSpec::ClassStar) {
5280         Say(name,
5281             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5282       } else if (const auto *derived{type->AsDerived()}) {
5283         auto &typeSymbol{derived->typeSymbol()};
5284         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5285             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5286           Say(name,
5287               "Derived type '%s' in COMMON block must have the BIND or"
5288               " SEQUENCE attribute"_err_en_US);
5289         }
5290         CheckCommonBlockDerivedType(name, typeSymbol);
5291       }
5292     }
5293   }
5294   specPartState_.commonBlockObjects = {};
5295 }
5296 
5297 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5298   return Resolve(name, currScope().MakeCommonBlock(name.source));
5299 }
5300 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5301     const std::optional<parser::Name> &name) {
5302   if (name) {
5303     return MakeCommonBlockSymbol(*name);
5304   } else {
5305     return MakeCommonBlockSymbol(parser::Name{});
5306   }
5307 }
5308 
5309 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5310   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5311 }
5312 
5313 // Check if this derived type can be in a COMMON block.
5314 void DeclarationVisitor::CheckCommonBlockDerivedType(
5315     const SourceName &name, const Symbol &typeSymbol) {
5316   if (const auto *scope{typeSymbol.scope()}) {
5317     for (const auto &pair : *scope) {
5318       const Symbol &component{*pair.second};
5319       if (component.attrs().test(Attr::ALLOCATABLE)) {
5320         Say2(name,
5321             "Derived type variable '%s' may not appear in a COMMON block"
5322             " due to ALLOCATABLE component"_err_en_US,
5323             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5324         return;
5325       }
5326       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5327       if (component.test(Symbol::Flag::InDataStmt) ||
5328           (details && details->init())) {
5329         Say2(name,
5330             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5331             component.name(), "Component with default initialization"_en_US);
5332         return;
5333       }
5334       if (details) {
5335         if (const auto *type{details->type()}) {
5336           if (const auto *derived{type->AsDerived()}) {
5337             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5338           }
5339         }
5340       }
5341     }
5342   }
5343 }
5344 
5345 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5346     const parser::Name &name) {
5347   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5348           name.source.ToString())}) {
5349     // Unrestricted specific intrinsic function names (e.g., "cos")
5350     // are acceptable as procedure interfaces.  The presence of the
5351     // INTRINSIC flag will cause this symbol to have a complete interface
5352     // recreated for it later on demand, but capturing its result type here
5353     // will make GetType() return a correct result without having to
5354     // probe the intrinsics table again.
5355     Symbol &symbol{
5356         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5357     CHECK(interface->functionResult.has_value());
5358     evaluate::DynamicType dyType{
5359         DEREF(interface->functionResult->GetTypeAndShape()).type()};
5360     CHECK(common::IsNumericTypeCategory(dyType.category()));
5361     const DeclTypeSpec &typeSpec{
5362         MakeNumericType(dyType.category(), dyType.kind())};
5363     ProcEntityDetails details;
5364     ProcInterface procInterface;
5365     procInterface.set_type(typeSpec);
5366     details.set_interface(procInterface);
5367     symbol.set_details(std::move(details));
5368     symbol.set(Symbol::Flag::Function);
5369     if (interface->IsElemental()) {
5370       symbol.attrs().set(Attr::ELEMENTAL);
5371     }
5372     if (interface->IsPure()) {
5373       symbol.attrs().set(Attr::PURE);
5374     }
5375     Resolve(name, symbol);
5376     return true;
5377   } else {
5378     return false;
5379   }
5380 }
5381 
5382 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5383 bool DeclarationVisitor::PassesSharedLocalityChecks(
5384     const parser::Name &name, Symbol &symbol) {
5385   if (!IsVariableName(symbol)) {
5386     SayLocalMustBeVariable(name, symbol); // C1124
5387     return false;
5388   }
5389   if (symbol.owner() == currScope()) { // C1125 and C1126
5390     SayAlreadyDeclared(name, symbol);
5391     return false;
5392   }
5393   return true;
5394 }
5395 
5396 // Checks for locality-specs LOCAL and LOCAL_INIT
5397 bool DeclarationVisitor::PassesLocalityChecks(
5398     const parser::Name &name, Symbol &symbol) {
5399   if (IsAllocatable(symbol)) { // C1128
5400     SayWithDecl(name, symbol,
5401         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5402     return false;
5403   }
5404   if (IsOptional(symbol)) { // C1128
5405     SayWithDecl(name, symbol,
5406         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5407     return false;
5408   }
5409   if (IsIntentIn(symbol)) { // C1128
5410     SayWithDecl(name, symbol,
5411         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5412     return false;
5413   }
5414   if (IsFinalizable(symbol)) { // C1128
5415     SayWithDecl(name, symbol,
5416         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5417     return false;
5418   }
5419   if (evaluate::IsCoarray(symbol)) { // C1128
5420     SayWithDecl(
5421         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5422     return false;
5423   }
5424   if (const DeclTypeSpec * type{symbol.GetType()}) {
5425     if (type->IsPolymorphic() && IsDummy(symbol) &&
5426         !IsPointer(symbol)) { // C1128
5427       SayWithDecl(name, symbol,
5428           "Nonpointer polymorphic argument '%s' not allowed in a "
5429           "locality-spec"_err_en_US);
5430       return false;
5431     }
5432   }
5433   if (IsAssumedSizeArray(symbol)) { // C1128
5434     SayWithDecl(name, symbol,
5435         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5436     return false;
5437   }
5438   if (std::optional<Message> msg{WhyNotModifiable(symbol, currScope())}) {
5439     SayWithReason(name, symbol,
5440         "'%s' may not appear in a locality-spec because it is not "
5441         "definable"_err_en_US,
5442         std::move(*msg));
5443     return false;
5444   }
5445   return PassesSharedLocalityChecks(name, symbol);
5446 }
5447 
5448 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5449     const parser::Name &name) {
5450   Symbol *prev{FindSymbol(name)};
5451   if (!prev) {
5452     // Declare the name as an object in the enclosing scope so that
5453     // the name can't be repurposed there later as something else.
5454     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5455     ConvertToObjectEntity(*prev);
5456     ApplyImplicitRules(*prev);
5457   }
5458   return *prev;
5459 }
5460 
5461 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5462   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5463   if (!PassesLocalityChecks(name, prev)) {
5464     return nullptr;
5465   }
5466   return &MakeHostAssocSymbol(name, prev);
5467 }
5468 
5469 Symbol *DeclarationVisitor::DeclareStatementEntity(
5470     const parser::DoVariable &doVar,
5471     const std::optional<parser::IntegerTypeSpec> &type) {
5472   const parser::Name &name{doVar.thing.thing};
5473   const DeclTypeSpec *declTypeSpec{nullptr};
5474   if (auto *prev{FindSymbol(name)}) {
5475     if (prev->owner() == currScope()) {
5476       SayAlreadyDeclared(name, *prev);
5477       return nullptr;
5478     }
5479     name.symbol = nullptr;
5480     declTypeSpec = prev->GetType();
5481   }
5482   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5483   if (!symbol.has<ObjectEntityDetails>()) {
5484     return nullptr; // error was reported in DeclareEntity
5485   }
5486   if (type) {
5487     declTypeSpec = ProcessTypeSpec(*type);
5488   }
5489   if (declTypeSpec) {
5490     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5491     // declaration of this implied DO loop control variable.
5492     auto restorer{
5493         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5494     SetType(name, *declTypeSpec);
5495   } else {
5496     ApplyImplicitRules(symbol);
5497   }
5498   Symbol *result{Resolve(name, &symbol)};
5499   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5500   return result;
5501 }
5502 
5503 // Set the type of an entity or report an error.
5504 void DeclarationVisitor::SetType(
5505     const parser::Name &name, const DeclTypeSpec &type) {
5506   CHECK(name.symbol);
5507   auto &symbol{*name.symbol};
5508   if (charInfo_.length) { // Declaration has "*length" (R723)
5509     auto length{std::move(*charInfo_.length)};
5510     charInfo_.length.reset();
5511     if (type.category() == DeclTypeSpec::Character) {
5512       auto kind{type.characterTypeSpec().kind()};
5513       // Recurse with correct type.
5514       SetType(name,
5515           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5516       return;
5517     } else { // C753
5518       Say(name,
5519           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5520     }
5521   }
5522   auto *prevType{symbol.GetType()};
5523   if (!prevType) {
5524     symbol.SetType(type);
5525   } else if (symbol.has<UseDetails>()) {
5526     // error recovery case, redeclaration of use-associated name
5527   } else if (HadForwardRef(symbol)) {
5528     // error recovery after use of host-associated name
5529   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5530     SayWithDecl(
5531         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5532     context().SetError(symbol);
5533   } else if (type != *prevType) {
5534     SayWithDecl(name, symbol,
5535         "The type of '%s' has already been implicitly declared"_err_en_US);
5536     context().SetError(symbol);
5537   } else {
5538     symbol.set(Symbol::Flag::Implicit, false);
5539   }
5540 }
5541 
5542 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5543     const parser::Name &name) {
5544   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5545   if (!symbol || symbol->has<UnknownDetails>()) {
5546     if (allowForwardReferenceToDerivedType()) {
5547       if (!symbol) {
5548         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5549         Resolve(name, *symbol);
5550       };
5551       DerivedTypeDetails details;
5552       details.set_isForwardReferenced(true);
5553       symbol->set_details(std::move(details));
5554     } else { // C732
5555       Say(name, "Derived type '%s' not found"_err_en_US);
5556       return std::nullopt;
5557     }
5558   }
5559   if (CheckUseError(name)) {
5560     return std::nullopt;
5561   }
5562   symbol = &symbol->GetUltimate();
5563   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
5564     if (details->derivedType()) {
5565       symbol = &details->derivedType()->GetUltimate();
5566     }
5567   }
5568   if (symbol->has<DerivedTypeDetails>()) {
5569     return DerivedTypeSpec{name.source, *symbol};
5570   } else {
5571     Say(name, "'%s' is not a derived type"_err_en_US);
5572     return std::nullopt;
5573   }
5574 }
5575 
5576 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5577     const parser::Name &typeName, const parser::Name *extendsName) {
5578   if (!extendsName) {
5579     return std::nullopt;
5580   } else if (typeName.source == extendsName->source) {
5581     Say(extendsName->source,
5582         "Derived type '%s' cannot extend itself"_err_en_US);
5583     return std::nullopt;
5584   } else {
5585     return ResolveDerivedType(*extendsName);
5586   }
5587 }
5588 
5589 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5590   // The symbol is checked later by CheckExplicitInterface() and
5591   // CheckBindings().  It can be a forward reference.
5592   if (!NameIsKnownOrIntrinsic(name)) {
5593     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5594     Resolve(name, symbol);
5595   }
5596   return name.symbol;
5597 }
5598 
5599 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5600   if (const Symbol * symbol{name.symbol}) {
5601     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5602       Say(name,
5603           "'%s' must be an abstract interface or a procedure with "
5604           "an explicit interface"_err_en_US,
5605           symbol->name());
5606     }
5607   }
5608 }
5609 
5610 // Create a symbol for a type parameter, component, or procedure binding in
5611 // the current derived type scope. Return false on error.
5612 Symbol *DeclarationVisitor::MakeTypeSymbol(
5613     const parser::Name &name, Details &&details) {
5614   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5615 }
5616 Symbol *DeclarationVisitor::MakeTypeSymbol(
5617     const SourceName &name, Details &&details) {
5618   Scope &derivedType{currScope()};
5619   CHECK(derivedType.IsDerivedType());
5620   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5621     Say2(name,
5622         "Type parameter, component, or procedure binding '%s'"
5623         " already defined in this type"_err_en_US,
5624         *symbol, "Previous definition of '%s'"_en_US);
5625     return nullptr;
5626   } else {
5627     auto attrs{GetAttrs()};
5628     // Apply binding-private-stmt if present and this is a procedure binding
5629     if (derivedTypeInfo_.privateBindings &&
5630         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5631         std::holds_alternative<ProcBindingDetails>(details)) {
5632       attrs.set(Attr::PRIVATE);
5633     }
5634     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5635     if (result.has<TypeParamDetails>()) {
5636       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5637     }
5638     return &result;
5639   }
5640 }
5641 
5642 // Return true if it is ok to declare this component in the current scope.
5643 // Otherwise, emit an error and return false.
5644 bool DeclarationVisitor::OkToAddComponent(
5645     const parser::Name &name, const Symbol *extends) {
5646   for (const Scope *scope{&currScope()}; scope;) {
5647     CHECK(scope->IsDerivedType());
5648     if (auto *prev{FindInScope(*scope, name)}) {
5649       if (!context().HasError(*prev)) {
5650         parser::MessageFixedText msg;
5651         if (extends) {
5652           msg = "Type cannot be extended as it has a component named"
5653                 " '%s'"_err_en_US;
5654         } else if (prev->test(Symbol::Flag::ParentComp)) {
5655           msg = "'%s' is a parent type of this type and so cannot be"
5656                 " a component"_err_en_US;
5657         } else if (scope != &currScope()) {
5658           msg = "Component '%s' is already declared in a parent of this"
5659                 " derived type"_err_en_US;
5660         } else {
5661           msg = "Component '%s' is already declared in this"
5662                 " derived type"_err_en_US;
5663         }
5664         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5665       }
5666       return false;
5667     }
5668     if (scope == &currScope() && extends) {
5669       // The parent component has not yet been added to the scope.
5670       scope = extends->scope();
5671     } else {
5672       scope = scope->GetDerivedTypeParent();
5673     }
5674   }
5675   return true;
5676 }
5677 
5678 ParamValue DeclarationVisitor::GetParamValue(
5679     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5680   return common::visit(
5681       common::visitors{
5682           [=](const parser::ScalarIntExpr &x) { // C704
5683             return ParamValue{EvaluateIntExpr(x), attr};
5684           },
5685           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5686           [=](const parser::TypeParamValue::Deferred &) {
5687             return ParamValue::Deferred(attr);
5688           },
5689       },
5690       x.u);
5691 }
5692 
5693 // ConstructVisitor implementation
5694 
5695 void ConstructVisitor::ResolveIndexName(
5696     const parser::ConcurrentControl &control) {
5697   const parser::Name &name{std::get<parser::Name>(control.t)};
5698   auto *prev{FindSymbol(name)};
5699   if (prev) {
5700     if (prev->owner().kind() == Scope::Kind::Forall ||
5701         prev->owner() == currScope()) {
5702       SayAlreadyDeclared(name, *prev);
5703       return;
5704     }
5705     name.symbol = nullptr;
5706   }
5707   auto &symbol{DeclareObjectEntity(name)};
5708   if (symbol.GetType()) {
5709     // type came from explicit type-spec
5710   } else if (!prev) {
5711     ApplyImplicitRules(symbol);
5712   } else {
5713     const Symbol &prevRoot{ResolveAssociations(*prev)};
5714     // prev could be host- use- or construct-associated with another symbol
5715     if (!prevRoot.has<ObjectEntityDetails>() &&
5716         !prevRoot.has<EntityDetails>()) {
5717       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5718           *prev, "Previous declaration of '%s'"_en_US);
5719       context().SetError(symbol);
5720       return;
5721     } else {
5722       if (const auto *type{prevRoot.GetType()}) {
5723         symbol.SetType(*type);
5724       }
5725       if (prevRoot.IsObjectArray()) {
5726         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5727         return;
5728       }
5729     }
5730   }
5731   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5732 }
5733 
5734 // We need to make sure that all of the index-names get declared before the
5735 // expressions in the loop control are evaluated so that references to the
5736 // index-names in the expressions are correctly detected.
5737 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5738   BeginDeclTypeSpec();
5739   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5740   const auto &controls{
5741       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5742   for (const auto &control : controls) {
5743     ResolveIndexName(control);
5744   }
5745   Walk(controls);
5746   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5747   EndDeclTypeSpec();
5748   return false;
5749 }
5750 
5751 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5752   for (auto &name : x.v) {
5753     if (auto *symbol{DeclareLocalEntity(name)}) {
5754       symbol->set(Symbol::Flag::LocalityLocal);
5755     }
5756   }
5757   return false;
5758 }
5759 
5760 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5761   for (auto &name : x.v) {
5762     if (auto *symbol{DeclareLocalEntity(name)}) {
5763       symbol->set(Symbol::Flag::LocalityLocalInit);
5764     }
5765   }
5766   return false;
5767 }
5768 
5769 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5770   for (const auto &name : x.v) {
5771     if (!FindSymbol(name)) {
5772       Say(name,
5773           "Variable '%s' with SHARED locality implicitly declared"_warn_en_US);
5774     }
5775     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5776     if (PassesSharedLocalityChecks(name, prev)) {
5777       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5778     }
5779   }
5780   return false;
5781 }
5782 
5783 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5784   ProcessTypeSpec(x.type);
5785   Walk(x.values);
5786   return false;
5787 }
5788 
5789 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5790 // enclosing ac-implied-do
5791 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5792   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5793   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5794   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5795   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5796   // F'2018 has the scope of the implied DO variable covering the entire
5797   // implied DO production (19.4(5)), which seems wrong in cases where the name
5798   // of the implied DO variable appears in one of the bound expressions. Thus
5799   // this extension, which shrinks the scope of the variable to exclude the
5800   // expressions in the bounds.
5801   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5802   Walk(bounds.lower);
5803   Walk(bounds.upper);
5804   Walk(bounds.step);
5805   EndCheckOnIndexUseInOwnBounds(restore);
5806   PushScope(Scope::Kind::ImpliedDos, nullptr);
5807   DeclareStatementEntity(bounds.name, type);
5808   Walk(values);
5809   PopScope();
5810   return false;
5811 }
5812 
5813 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5814   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5815   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5816   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5817   // See comment in Pre(AcImpliedDo) above.
5818   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5819   Walk(bounds.lower);
5820   Walk(bounds.upper);
5821   Walk(bounds.step);
5822   EndCheckOnIndexUseInOwnBounds(restore);
5823   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5824   if (pushScope) {
5825     PushScope(Scope::Kind::ImpliedDos, nullptr);
5826   }
5827   DeclareStatementEntity(bounds.name, type);
5828   Walk(objects);
5829   if (pushScope) {
5830     PopScope();
5831   }
5832   return false;
5833 }
5834 
5835 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5836 // statement so that the predicate IsInitialized() will be true
5837 // during semantic analysis before the symbol's initializer is constructed.
5838 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5839   common::visit(
5840       common::visitors{
5841           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5842             Walk(y.thing.value());
5843             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5844             if (first.symbol) {
5845               first.symbol->set(Symbol::Flag::InDataStmt);
5846             }
5847           },
5848           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5849       },
5850       x.u);
5851   return false;
5852 }
5853 
5854 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5855   common::visit(common::visitors{
5856                     [&](const Indirection<parser::Variable> &y) {
5857                       Walk(y.value());
5858                       const parser::Name &first{
5859                           parser::GetFirstName(y.value())};
5860                       if (first.symbol) {
5861                         first.symbol->set(Symbol::Flag::InDataStmt);
5862                       }
5863                     },
5864                     [&](const parser::DataImpliedDo &y) {
5865                       PushScope(Scope::Kind::ImpliedDos, nullptr);
5866                       Walk(y);
5867                       PopScope();
5868                     },
5869                 },
5870       x.u);
5871   return false;
5872 }
5873 
5874 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5875   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5876   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5877   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5878     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5879       if (const Symbol * symbol{FindSymbol(*name)}) {
5880         const Symbol &ultimate{symbol->GetUltimate()};
5881         if (ultimate.has<DerivedTypeDetails>()) {
5882           mutableData.u = elem->ConvertToStructureConstructor(
5883               DerivedTypeSpec{name->source, ultimate});
5884         }
5885       }
5886     }
5887   }
5888   return true;
5889 }
5890 
5891 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5892   if (x.IsDoConcurrent()) {
5893     PushScope(Scope::Kind::Block, nullptr);
5894   }
5895   return true;
5896 }
5897 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5898   if (x.IsDoConcurrent()) {
5899     PopScope();
5900   }
5901 }
5902 
5903 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5904   PushScope(Scope::Kind::Forall, nullptr);
5905   return true;
5906 }
5907 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5908 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5909   PushScope(Scope::Kind::Forall, nullptr);
5910   return true;
5911 }
5912 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5913 
5914 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5915   CheckDef(x.v);
5916   PushScope(Scope::Kind::Block, nullptr);
5917   return false;
5918 }
5919 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5920   PopScope();
5921   CheckRef(x.v);
5922   return false;
5923 }
5924 
5925 void ConstructVisitor::Post(const parser::Selector &x) {
5926   GetCurrentAssociation().selector = ResolveSelector(x);
5927 }
5928 
5929 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
5930   CheckDef(x.t);
5931   PushScope(Scope::Kind::Block, nullptr);
5932   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
5933   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
5934     SetCurrentAssociation(nthLastAssoc);
5935     if (auto *symbol{MakeAssocEntity()}) {
5936       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
5937         Say("Selector must not be a coindexed object"_err_en_US);
5938       }
5939       SetTypeFromAssociation(*symbol);
5940       SetAttrsFromAssociation(*symbol);
5941     }
5942   }
5943   PopAssociation(assocCount);
5944 }
5945 
5946 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5947   PopScope();
5948   CheckRef(x.v);
5949 }
5950 
5951 bool ConstructVisitor::Pre(const parser::Association &x) {
5952   PushAssociation();
5953   const auto &name{std::get<parser::Name>(x.t)};
5954   GetCurrentAssociation().name = &name;
5955   return true;
5956 }
5957 
5958 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5959   CheckDef(x.t);
5960   PushScope(Scope::Kind::Block, nullptr);
5961   PushAssociation();
5962   return true;
5963 }
5964 
5965 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5966   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5967   const auto &name{std::get<parser::Name>(decl.t)};
5968   if (auto *symbol{FindInScope(name)}) {
5969     const auto &selector{std::get<parser::Selector>(x.t)};
5970     if (auto sel{ResolveSelector(selector)}) {
5971       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5972       if (!whole || whole->Corank() == 0) {
5973         Say(sel.source, // C1116
5974             "Selector in coarray association must name a coarray"_err_en_US);
5975       } else if (auto dynType{sel.expr->GetType()}) {
5976         if (!symbol->GetType()) {
5977           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5978         }
5979       }
5980     }
5981   }
5982 }
5983 
5984 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5985   PopAssociation();
5986   PopScope();
5987   CheckRef(x.t);
5988 }
5989 
5990 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5991   PushAssociation();
5992   return true;
5993 }
5994 
5995 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5996   PopAssociation();
5997 }
5998 
5999 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
6000   auto &association{GetCurrentAssociation()};
6001   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6002     // This isn't a name in the current scope, it is in each TypeGuardStmt
6003     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
6004     association.name = &*name;
6005     auto exprType{association.selector.expr->GetType()};
6006     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
6007       Say("Selector must not be a coindexed object"_err_en_US);
6008     }
6009     if (exprType && !exprType->IsPolymorphic()) { // C1159
6010       Say(association.selector.source,
6011           "Selector '%s' in SELECT TYPE statement must be "
6012           "polymorphic"_err_en_US);
6013     }
6014   } else {
6015     if (const Symbol *
6016         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6017       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
6018       if (!IsVariableName(*whole)) {
6019         Say(association.selector.source, // C901
6020             "Selector is not a variable"_err_en_US);
6021         association = {};
6022       }
6023       if (const DeclTypeSpec * type{whole->GetType()}) {
6024         if (!type->IsPolymorphic()) { // C1159
6025           Say(association.selector.source,
6026               "Selector '%s' in SELECT TYPE statement must be "
6027               "polymorphic"_err_en_US);
6028         }
6029       }
6030     } else {
6031       Say(association.selector.source, // C1157
6032           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
6033       association = {};
6034     }
6035   }
6036 }
6037 
6038 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
6039   auto &association{GetCurrentAssociation()};
6040   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6041     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
6042     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
6043     association.name = &*name;
6044   }
6045 }
6046 
6047 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
6048   PushScope(Scope::Kind::Block, nullptr);
6049   return true;
6050 }
6051 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
6052   PopScope();
6053 }
6054 
6055 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
6056   PushScope(Scope::Kind::Block, nullptr);
6057   return true;
6058 }
6059 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
6060   PopScope();
6061 }
6062 
6063 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
6064   if (auto *symbol{MakeAssocEntity()}) {
6065     if (std::holds_alternative<parser::Default>(x.u)) {
6066       SetTypeFromAssociation(*symbol);
6067     } else if (const auto *type{GetDeclTypeSpec()}) {
6068       symbol->SetType(*type);
6069     }
6070     SetAttrsFromAssociation(*symbol);
6071   }
6072 }
6073 
6074 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
6075   if (auto *symbol{MakeAssocEntity()}) {
6076     SetTypeFromAssociation(*symbol);
6077     SetAttrsFromAssociation(*symbol);
6078     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
6079       if (auto val{EvaluateInt64(context(), *init)}) {
6080         auto &details{symbol->get<AssocEntityDetails>()};
6081         details.set_rank(*val);
6082       }
6083     }
6084   }
6085 }
6086 
6087 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
6088   PushAssociation();
6089   return true;
6090 }
6091 
6092 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
6093   PopAssociation();
6094 }
6095 
6096 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
6097   if (x) {
6098     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
6099   }
6100   return true;
6101 }
6102 
6103 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
6104   if (x) {
6105     // Just add an occurrence of this name; checking is done in ValidateLabels
6106     FindSymbol(*x);
6107   }
6108 }
6109 
6110 // Make a symbol for the associating entity of the current association.
6111 Symbol *ConstructVisitor::MakeAssocEntity() {
6112   Symbol *symbol{nullptr};
6113   auto &association{GetCurrentAssociation()};
6114   if (association.name) {
6115     symbol = &MakeSymbol(*association.name, UnknownDetails{});
6116     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
6117       Say(*association.name, // C1102
6118           "The associate name '%s' is already used in this associate statement"_err_en_US);
6119       return nullptr;
6120     }
6121   } else if (const Symbol *
6122       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6123     symbol = &MakeSymbol(whole->name());
6124   } else {
6125     return nullptr;
6126   }
6127   if (auto &expr{association.selector.expr}) {
6128     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
6129   } else {
6130     symbol->set_details(AssocEntityDetails{});
6131   }
6132   return symbol;
6133 }
6134 
6135 // Set the type of symbol based on the current association selector.
6136 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
6137   auto &details{symbol.get<AssocEntityDetails>()};
6138   const MaybeExpr *pexpr{&details.expr()};
6139   if (!*pexpr) {
6140     pexpr = &GetCurrentAssociation().selector.expr;
6141   }
6142   if (*pexpr) {
6143     const SomeExpr &expr{**pexpr};
6144     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
6145       if (const auto *charExpr{
6146               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
6147                   expr)}) {
6148         symbol.SetType(ToDeclTypeSpec(std::move(*type),
6149             FoldExpr(common::visit(
6150                 [](const auto &kindChar) { return kindChar.LEN(); },
6151                 charExpr->u))));
6152       } else {
6153         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
6154       }
6155     } else {
6156       // BOZ literals, procedure designators, &c. are not acceptable
6157       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
6158     }
6159   }
6160 }
6161 
6162 // If current selector is a variable, set some of its attributes on symbol.
6163 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
6164   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
6165   symbol.attrs() |= attrs &
6166       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
6167   if (attrs.test(Attr::POINTER)) {
6168     symbol.attrs().set(Attr::TARGET);
6169   }
6170 }
6171 
6172 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
6173     const parser::Selector &x) {
6174   return common::visit(common::visitors{
6175                            [&](const parser::Expr &expr) {
6176                              return Selector{expr.source, EvaluateExpr(x)};
6177                            },
6178                            [&](const parser::Variable &var) {
6179                              return Selector{var.GetSource(), EvaluateExpr(x)};
6180                            },
6181                        },
6182       x.u);
6183 }
6184 
6185 // Set the current association to the nth to the last association on the
6186 // association stack.  The top of the stack is at n = 1.  This allows access
6187 // to the interior of a list of associations at the top of the stack.
6188 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
6189   CHECK(n > 0 && n <= associationStack_.size());
6190   currentAssociation_ = &associationStack_[associationStack_.size() - n];
6191 }
6192 
6193 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
6194   CHECK(currentAssociation_);
6195   return *currentAssociation_;
6196 }
6197 
6198 void ConstructVisitor::PushAssociation() {
6199   associationStack_.emplace_back(Association{});
6200   currentAssociation_ = &associationStack_.back();
6201 }
6202 
6203 void ConstructVisitor::PopAssociation(std::size_t count) {
6204   CHECK(count > 0 && count <= associationStack_.size());
6205   associationStack_.resize(associationStack_.size() - count);
6206   currentAssociation_ =
6207       associationStack_.empty() ? nullptr : &associationStack_.back();
6208 }
6209 
6210 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6211     evaluate::DynamicType &&type) {
6212   switch (type.category()) {
6213     SWITCH_COVERS_ALL_CASES
6214   case common::TypeCategory::Integer:
6215   case common::TypeCategory::Real:
6216   case common::TypeCategory::Complex:
6217     return context().MakeNumericType(type.category(), type.kind());
6218   case common::TypeCategory::Logical:
6219     return context().MakeLogicalType(type.kind());
6220   case common::TypeCategory::Derived:
6221     if (type.IsAssumedType()) {
6222       return currScope().MakeTypeStarType();
6223     } else if (type.IsUnlimitedPolymorphic()) {
6224       return currScope().MakeClassStarType();
6225     } else {
6226       return currScope().MakeDerivedType(
6227           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
6228                                : DeclTypeSpec::TypeDerived,
6229           common::Clone(type.GetDerivedTypeSpec())
6230 
6231       );
6232     }
6233   case common::TypeCategory::Character:
6234     CRASH_NO_CASE;
6235   }
6236 }
6237 
6238 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6239     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
6240   CHECK(type.category() == common::TypeCategory::Character);
6241   if (length) {
6242     return currScope().MakeCharacterType(
6243         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
6244         KindExpr{type.kind()});
6245   } else {
6246     return currScope().MakeCharacterType(
6247         ParamValue::Deferred(common::TypeParamAttr::Len),
6248         KindExpr{type.kind()});
6249   }
6250 }
6251 
6252 // ResolveNamesVisitor implementation
6253 
6254 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
6255   HandleCall(Symbol::Flag::Function, x.v);
6256   return false;
6257 }
6258 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
6259   HandleCall(Symbol::Flag::Subroutine, x.v);
6260   return false;
6261 }
6262 
6263 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
6264   auto &scope{currScope()};
6265   // Check C896 and C899: where IMPORT statements are allowed
6266   switch (scope.kind()) {
6267   case Scope::Kind::Module:
6268     if (scope.IsModule()) {
6269       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
6270       return false;
6271     } else if (x.kind == common::ImportKind::None) {
6272       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
6273       return false;
6274     }
6275     break;
6276   case Scope::Kind::MainProgram:
6277     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
6278     return false;
6279   case Scope::Kind::Subprogram:
6280     if (scope.parent().IsGlobal()) {
6281       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
6282       return false;
6283     }
6284     break;
6285   case Scope::Kind::BlockData: // C1415 (in part)
6286     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
6287     return false;
6288   default:;
6289   }
6290   if (auto error{scope.SetImportKind(x.kind)}) {
6291     Say(std::move(*error));
6292   }
6293   for (auto &name : x.names) {
6294     if (FindSymbol(scope.parent(), name)) {
6295       scope.add_importName(name.source);
6296     } else {
6297       Say(name, "'%s' not found in host scope"_err_en_US);
6298     }
6299   }
6300   prevImportStmt_ = currStmtSource();
6301   return false;
6302 }
6303 
6304 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6305     const parser::StructureComponent &x) {
6306   return FindComponent(ResolveDataRef(x.base), x.component);
6307 }
6308 
6309 const parser::Name *DeclarationVisitor::ResolveDesignator(
6310     const parser::Designator &x) {
6311   return common::visit(
6312       common::visitors{
6313           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6314           [&](const parser::Substring &x) {
6315             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6316           },
6317       },
6318       x.u);
6319 }
6320 
6321 const parser::Name *DeclarationVisitor::ResolveDataRef(
6322     const parser::DataRef &x) {
6323   return common::visit(
6324       common::visitors{
6325           [=](const parser::Name &y) { return ResolveName(y); },
6326           [=](const Indirection<parser::StructureComponent> &y) {
6327             return ResolveStructureComponent(y.value());
6328           },
6329           [&](const Indirection<parser::ArrayElement> &y) {
6330             Walk(y.value().subscripts);
6331             const parser::Name *name{ResolveDataRef(y.value().base)};
6332             if (name && name->symbol) {
6333               if (!IsProcedure(*name->symbol)) {
6334                 ConvertToObjectEntity(*name->symbol);
6335               } else if (!context().HasError(*name->symbol)) {
6336                 SayWithDecl(*name, *name->symbol,
6337                     "Cannot reference function '%s' as data"_err_en_US);
6338               }
6339             }
6340             return name;
6341           },
6342           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6343             Walk(y.value().imageSelector);
6344             return ResolveDataRef(y.value().base);
6345           },
6346       },
6347       x.u);
6348 }
6349 
6350 // If implicit types are allowed, ensure name is in the symbol table.
6351 // Otherwise, report an error if it hasn't been declared.
6352 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6353   FindSymbol(name);
6354   if (CheckForHostAssociatedImplicit(name)) {
6355     NotePossibleBadForwardRef(name);
6356     return &name;
6357   }
6358   if (Symbol * symbol{name.symbol}) {
6359     if (CheckUseError(name)) {
6360       return nullptr; // reported an error
6361     }
6362     NotePossibleBadForwardRef(name);
6363     symbol->set(Symbol::Flag::ImplicitOrError, false);
6364     if (IsUplevelReference(*symbol)) {
6365       MakeHostAssocSymbol(name, *symbol);
6366     } else if (IsDummy(*symbol) ||
6367         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6368       ConvertToObjectEntity(*symbol);
6369       ApplyImplicitRules(*symbol);
6370     }
6371     if (checkIndexUseInOwnBounds_ &&
6372         *checkIndexUseInOwnBounds_ == name.source) {
6373       Say(name,
6374           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_port_en_US,
6375           name.source);
6376     }
6377     return &name;
6378   }
6379   if (isImplicitNoneType()) {
6380     Say(name, "No explicit type declared for '%s'"_err_en_US);
6381     return nullptr;
6382   }
6383   // Create the symbol then ensure it is accessible
6384   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6385     Say(name,
6386         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6387         name.source);
6388   }
6389   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6390   auto *symbol{FindSymbol(name)};
6391   if (!symbol) {
6392     Say(name,
6393         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6394     return nullptr;
6395   }
6396   ConvertToObjectEntity(*symbol);
6397   ApplyImplicitRules(*symbol);
6398   NotePossibleBadForwardRef(name);
6399   return &name;
6400 }
6401 
6402 // A specification expression may refer to a symbol in the host procedure that
6403 // is implicitly typed. Because specification parts are processed before
6404 // execution parts, this may be the first time we see the symbol. It can't be a
6405 // local in the current scope (because it's in a specification expression) so
6406 // either it is implicitly declared in the host procedure or it is an error.
6407 // We create a symbol in the host assuming it is the former; if that proves to
6408 // be wrong we report an error later in CheckDeclarations().
6409 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6410     const parser::Name &name) {
6411   if (inExecutionPart_) {
6412     return false;
6413   }
6414   if (name.symbol) {
6415     ApplyImplicitRules(*name.symbol, true);
6416   }
6417   Symbol *hostSymbol;
6418   Scope *host{GetHostProcedure()};
6419   if (!host || isImplicitNoneType(*host)) {
6420     return false;
6421   }
6422   if (!name.symbol) {
6423     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6424     ConvertToObjectEntity(*hostSymbol);
6425     ApplyImplicitRules(*hostSymbol);
6426     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6427   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6428     hostSymbol = name.symbol;
6429   } else {
6430     return false;
6431   }
6432   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6433   if (isImplicitNoneType()) {
6434     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6435   } else {
6436     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6437   }
6438   return true;
6439 }
6440 
6441 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6442   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6443   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6444     return false;
6445   } else {
6446     Scope::Kind kind{symbolUnit.kind()};
6447     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6448   }
6449 }
6450 
6451 // base is a part-ref of a derived type; find the named component in its type.
6452 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6453 // COMPLEX component references (%re, %im).
6454 const parser::Name *DeclarationVisitor::FindComponent(
6455     const parser::Name *base, const parser::Name &component) {
6456   if (!base || !base->symbol) {
6457     return nullptr;
6458   }
6459   if (auto *misc{base->symbol->detailsIf<MiscDetails>()}) {
6460     if (component.source == "kind") {
6461       if (misc->kind() == MiscDetails::Kind::ComplexPartRe ||
6462           misc->kind() == MiscDetails::Kind::ComplexPartIm ||
6463           misc->kind() == MiscDetails::Kind::KindParamInquiry ||
6464           misc->kind() == MiscDetails::Kind::LenParamInquiry) {
6465         // x%{re,im,kind,len}%kind
6466         MakePlaceholder(component, MiscDetails::Kind::KindParamInquiry);
6467         return &component;
6468       }
6469     }
6470   }
6471   auto &symbol{base->symbol->GetUltimate()};
6472   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6473     SayWithDecl(*base, symbol,
6474         "'%s' is an invalid base for a component reference"_err_en_US);
6475     return nullptr;
6476   }
6477   auto *type{symbol.GetType()};
6478   if (!type) {
6479     return nullptr; // should have already reported error
6480   }
6481   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6482     auto category{intrinsic->category()};
6483     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6484     if (component.source == "kind") {
6485       miscKind = MiscDetails::Kind::KindParamInquiry;
6486     } else if (category == TypeCategory::Character) {
6487       if (component.source == "len") {
6488         miscKind = MiscDetails::Kind::LenParamInquiry;
6489       }
6490     } else if (category == TypeCategory::Complex) {
6491       if (component.source == "re") {
6492         miscKind = MiscDetails::Kind::ComplexPartRe;
6493       } else if (component.source == "im") {
6494         miscKind = MiscDetails::Kind::ComplexPartIm;
6495       }
6496     }
6497     if (miscKind != MiscDetails::Kind::None) {
6498       MakePlaceholder(component, miscKind);
6499       return &component;
6500     }
6501   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6502     if (const Scope * scope{derived->scope()}) {
6503       if (Resolve(component, scope->FindComponent(component.source))) {
6504         if (auto msg{
6505                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6506           context().Say(component.source, *msg);
6507         }
6508         return &component;
6509       } else {
6510         SayDerivedType(component.source,
6511             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6512       }
6513     }
6514     return nullptr;
6515   }
6516   if (symbol.test(Symbol::Flag::Implicit)) {
6517     Say(*base,
6518         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6519   } else {
6520     SayWithDecl(
6521         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6522   }
6523   return nullptr;
6524 }
6525 
6526 void DeclarationVisitor::Initialization(const parser::Name &name,
6527     const parser::Initialization &init, bool inComponentDecl) {
6528   // Traversal of the initializer was deferred to here so that the
6529   // symbol being declared can be available for use in the expression, e.g.:
6530   //   real, parameter :: x = tiny(x)
6531   if (!name.symbol) {
6532     return;
6533   }
6534   Symbol &ultimate{name.symbol->GetUltimate()};
6535   if (IsAllocatable(ultimate)) {
6536     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6537     return;
6538   }
6539   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6540     // TODO: check C762 - all bounds and type parameters of component
6541     // are colons or constant expressions if component is initialized
6542     common::visit(
6543         common::visitors{
6544             [&](const parser::ConstantExpr &expr) {
6545               NonPointerInitialization(name, expr);
6546             },
6547             [&](const parser::NullInit &null) {
6548               Walk(null);
6549               if (auto nullInit{EvaluateExpr(null)}) {
6550                 if (!evaluate::IsNullPointer(*nullInit)) {
6551                   Say(name,
6552                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6553                 } else if (IsPointer(ultimate)) {
6554                   object->set_init(std::move(*nullInit));
6555                 } else {
6556                   Say(name,
6557                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6558                 }
6559               }
6560             },
6561             [&](const parser::InitialDataTarget &) {
6562               // Defer analysis to the end of the specification part
6563               // so that forward references and attribute checks like SAVE
6564               // work better.
6565               ultimate.set(Symbol::Flag::InDataStmt);
6566             },
6567             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
6568               // Handled later in data-to-inits conversion
6569               ultimate.set(Symbol::Flag::InDataStmt);
6570             },
6571         },
6572         init.u);
6573   }
6574 }
6575 
6576 void DeclarationVisitor::PointerInitialization(
6577     const parser::Name &name, const parser::InitialDataTarget &target) {
6578   if (name.symbol) {
6579     Symbol &ultimate{name.symbol->GetUltimate()};
6580     if (!context().HasError(ultimate)) {
6581       if (IsPointer(ultimate)) {
6582         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6583           CHECK(!details->init());
6584           Walk(target);
6585           if (MaybeExpr expr{EvaluateExpr(target)}) {
6586             // Validation is done in declaration checking.
6587             details->set_init(std::move(*expr));
6588           }
6589         }
6590       } else {
6591         Say(name,
6592             "'%s' is not a pointer but is initialized like one"_err_en_US);
6593         context().SetError(ultimate);
6594       }
6595     }
6596   }
6597 }
6598 void DeclarationVisitor::PointerInitialization(
6599     const parser::Name &name, const parser::ProcPointerInit &target) {
6600   if (name.symbol) {
6601     Symbol &ultimate{name.symbol->GetUltimate()};
6602     if (!context().HasError(ultimate)) {
6603       if (IsProcedurePointer(ultimate)) {
6604         auto &details{ultimate.get<ProcEntityDetails>()};
6605         CHECK(!details.init());
6606         Walk(target);
6607         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6608           if (targetName->symbol) {
6609             // Validation is done in declaration checking.
6610             details.set_init(*targetName->symbol);
6611           }
6612         } else {
6613           details.set_init(nullptr); // explicit NULL()
6614         }
6615       } else {
6616         Say(name,
6617             "'%s' is not a procedure pointer but is initialized "
6618             "like one"_err_en_US);
6619         context().SetError(ultimate);
6620       }
6621     }
6622   }
6623 }
6624 
6625 void DeclarationVisitor::NonPointerInitialization(
6626     const parser::Name &name, const parser::ConstantExpr &expr) {
6627   if (name.symbol) {
6628     Symbol &ultimate{name.symbol->GetUltimate()};
6629     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6630       if (IsPointer(ultimate)) {
6631         Say(name,
6632             "'%s' is a pointer but is not initialized like one"_err_en_US);
6633       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6634         CHECK(!details->init());
6635         Walk(expr);
6636         if (ultimate.owner().IsParameterizedDerivedType()) {
6637           // Save the expression for per-instantiation analysis.
6638           details->set_unanalyzedPDTComponentInit(&expr.thing.value());
6639         } else {
6640           if (MaybeExpr folded{EvaluateNonPointerInitializer(
6641                   ultimate, expr, expr.thing.value().source)}) {
6642             details->set_init(std::move(*folded));
6643           }
6644         }
6645       }
6646     }
6647   }
6648 }
6649 
6650 void ResolveNamesVisitor::HandleCall(
6651     Symbol::Flag procFlag, const parser::Call &call) {
6652   common::visit(
6653       common::visitors{
6654           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6655           [&](const parser::ProcComponentRef &x) { Walk(x); },
6656       },
6657       std::get<parser::ProcedureDesignator>(call.t).u);
6658   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6659 }
6660 
6661 void ResolveNamesVisitor::HandleProcedureName(
6662     Symbol::Flag flag, const parser::Name &name) {
6663   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6664   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6665   if (!symbol) {
6666     if (IsIntrinsic(name.source, flag)) {
6667       symbol =
6668           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6669     } else {
6670       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6671     }
6672     Resolve(name, *symbol);
6673     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6674       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6675         MakeExternal(*symbol);
6676       }
6677     }
6678     ConvertToProcEntity(*symbol);
6679     SetProcFlag(name, *symbol, flag);
6680   } else if (CheckUseError(name)) {
6681     // error was reported
6682   } else {
6683     auto &nonUltimateSymbol = *symbol;
6684     symbol = &Resolve(name, symbol)->GetUltimate();
6685     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6686     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6687         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6688       AcquireIntrinsicProcedureFlags(*symbol);
6689     }
6690     if (!SetProcFlag(name, *symbol, flag)) {
6691       return; // reported error
6692     }
6693     if (!symbol->has<GenericDetails>()) {
6694       CheckImplicitNoneExternal(name.source, *symbol);
6695     }
6696     if (symbol->has<SubprogramDetails>() &&
6697         symbol->attrs().test(Attr::ABSTRACT)) {
6698       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6699     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6700         symbol->has<AssocEntityDetails>()) {
6701       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6702       // here as procedure-designators because this means the related
6703       // FunctionReference are mis-parsed structure constructors or array
6704       // references that will be fixed later when analyzing expressions.
6705     } else if (symbol->has<ObjectEntityDetails>()) {
6706       // Symbols with ObjectEntityDetails are also accepted because this can be
6707       // a mis-parsed array references that will be fixed later. Ensure that if
6708       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6709       // is created for the current scope.
6710       // Operate on non ultimate symbol so that HostAssocDetails are also
6711       // created for symbols used associated in the host procedure.
6712       if (IsUplevelReference(nonUltimateSymbol)) {
6713         MakeHostAssocSymbol(name, nonUltimateSymbol);
6714       }
6715     } else if (symbol->test(Symbol::Flag::Implicit)) {
6716       Say(name,
6717           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6718     } else {
6719       SayWithDecl(name, *symbol,
6720           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6721     }
6722   }
6723 }
6724 
6725 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6726     const SourceName &name, const Symbol &symbol) {
6727   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6728       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6729     Say(name,
6730         "'%s' is an external procedure without the EXTERNAL"
6731         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6732     return false;
6733   }
6734   return true;
6735 }
6736 
6737 // Variant of HandleProcedureName() for use while skimming the executable
6738 // part of a subprogram to catch calls to dummy procedures that are part
6739 // of the subprogram's interface, and to mark as procedures any symbols
6740 // that might otherwise have been miscategorized as objects.
6741 void ResolveNamesVisitor::NoteExecutablePartCall(
6742     Symbol::Flag flag, const parser::Call &call) {
6743   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6744   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6745     // Subtlety: The symbol pointers in the parse tree are not set, because
6746     // they might end up resolving elsewhere (e.g., construct entities in
6747     // SELECT TYPE).
6748     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6749       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6750               ? Symbol::Flag::Function
6751               : Symbol::Flag::Subroutine};
6752       if (!symbol->test(other)) {
6753         ConvertToProcEntity(*symbol);
6754         if (symbol->has<ProcEntityDetails>()) {
6755           symbol->set(flag);
6756           if (IsDummy(*symbol)) {
6757             symbol->attrs().set(Attr::EXTERNAL);
6758           }
6759           ApplyImplicitRules(*symbol);
6760         }
6761       }
6762     }
6763   }
6764 }
6765 
6766 static bool IsLocallyImplicitGlobalSymbol(
6767     const Symbol &symbol, const parser::Name &localName) {
6768   return symbol.owner().IsGlobal() &&
6769       (!symbol.scope() ||
6770           !symbol.scope()->sourceRange().Contains(localName.source));
6771 }
6772 
6773 static bool TypesMismatchIfNonNull(
6774     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
6775   return type1 && type2 && *type1 != *type2;
6776 }
6777 
6778 // Check and set the Function or Subroutine flag on symbol; false on error.
6779 bool ResolveNamesVisitor::SetProcFlag(
6780     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6781   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6782     SayWithDecl(
6783         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6784     return false;
6785   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6786       flag == Symbol::Flag::Function) {
6787     SayWithDecl(
6788         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6789     return false;
6790   } else if (flag == Symbol::Flag::Function &&
6791       IsLocallyImplicitGlobalSymbol(symbol, name) &&
6792       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
6793     SayWithDecl(name, symbol,
6794         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
6795     return false;
6796   } else if (symbol.has<ProcEntityDetails>()) {
6797     symbol.set(flag); // in case it hasn't been set yet
6798     if (flag == Symbol::Flag::Function) {
6799       ApplyImplicitRules(symbol);
6800     }
6801     if (symbol.attrs().test(Attr::INTRINSIC)) {
6802       AcquireIntrinsicProcedureFlags(symbol);
6803     }
6804   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6805     SayWithDecl(
6806         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6807   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6808     AcquireIntrinsicProcedureFlags(symbol);
6809   }
6810   return true;
6811 }
6812 
6813 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6814   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6815   if (!currScope().IsModule()) { // C869
6816     Say(currStmtSource().value(),
6817         "%s statement may only appear in the specification part of a module"_err_en_US,
6818         EnumToString(accessAttr));
6819     return false;
6820   }
6821   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6822   if (accessIds.empty()) {
6823     if (prevAccessStmt_) { // C869
6824       Say("The default accessibility of this module has already been declared"_err_en_US)
6825           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6826     }
6827     prevAccessStmt_ = currStmtSource();
6828     defaultAccess_ = accessAttr;
6829   } else {
6830     for (const auto &accessId : accessIds) {
6831       common::visit(
6832           common::visitors{
6833               [=](const parser::Name &y) {
6834                 Resolve(y, SetAccess(y.source, accessAttr));
6835               },
6836               [=](const Indirection<parser::GenericSpec> &y) {
6837                 auto info{GenericSpecInfo{y.value()}};
6838                 const auto &symbolName{info.symbolName()};
6839                 if (auto *symbol{FindInScope(symbolName)}) {
6840                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6841                 } else if (info.kind().IsName()) {
6842                   info.Resolve(&SetAccess(symbolName, accessAttr));
6843                 } else {
6844                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6845                 }
6846               },
6847           },
6848           accessId.u);
6849     }
6850   }
6851   return false;
6852 }
6853 
6854 // Set the access specification for this symbol.
6855 Symbol &ModuleVisitor::SetAccess(
6856     const SourceName &name, Attr attr, Symbol *symbol) {
6857   if (!symbol) {
6858     symbol = &MakeSymbol(name);
6859   }
6860   Attrs &attrs{symbol->attrs()};
6861   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6862     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6863     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6864     Say(name,
6865         WithSeverity(
6866             "The accessibility of '%s' has already been specified as %s"_warn_en_US,
6867             attr != prev ? parser::Severity::Error : parser::Severity::Warning),
6868         MakeOpName(name), EnumToString(prev));
6869   } else {
6870     attrs.set(attr);
6871   }
6872   return *symbol;
6873 }
6874 
6875 static bool NeedsExplicitType(const Symbol &symbol) {
6876   if (symbol.has<UnknownDetails>()) {
6877     return true;
6878   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6879     return !details->type();
6880   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6881     return !details->type();
6882   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6883     return !details->interface().symbol() && !details->interface().type();
6884   } else {
6885     return false;
6886   }
6887 }
6888 
6889 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6890   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
6891       implicitPart, decls] = x.t;
6892   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
6893   auto stateRestorer{
6894       common::ScopedSet(specPartState_, SpecificationPartState{})};
6895   Walk(accDecls);
6896   Walk(ompDecls);
6897   Walk(compilerDirectives);
6898   Walk(useStmts);
6899   ClearUseRenames();
6900   ClearUseOnly();
6901   ClearExplicitIntrinsicUses();
6902   Walk(importStmts);
6903   Walk(implicitPart);
6904   for (const auto &decl : decls) {
6905     if (const auto *spec{
6906             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6907       PreSpecificationConstruct(*spec);
6908     }
6909   }
6910   Walk(decls);
6911   FinishSpecificationPart(decls);
6912   return false;
6913 }
6914 
6915 // Initial processing on specification constructs, before visiting them.
6916 void ResolveNamesVisitor::PreSpecificationConstruct(
6917     const parser::SpecificationConstruct &spec) {
6918   common::visit(
6919       common::visitors{
6920           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6921             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6922           },
6923           [&](const Indirection<parser::InterfaceBlock> &y) {
6924             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6925                 y.value().t)};
6926             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
6927               CreateGeneric(*spec);
6928             }
6929           },
6930           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
6931             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
6932               CreateCommonBlockSymbols(*commonStmt);
6933             }
6934           },
6935           [&](const auto &) {},
6936       },
6937       spec.u);
6938 }
6939 
6940 void ResolveNamesVisitor::CreateCommonBlockSymbols(
6941     const parser::CommonStmt &commonStmt) {
6942   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
6943     const auto &[name, objects] = block.t;
6944     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
6945     for (const auto &object : objects) {
6946       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
6947       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
6948         details->set_commonBlock(commonBlock);
6949         commonBlock.get<CommonBlockDetails>().add_object(obj);
6950       }
6951     }
6952   }
6953 }
6954 
6955 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6956   auto info{GenericSpecInfo{x}};
6957   SourceName symbolName{info.symbolName()};
6958   if (IsLogicalConstant(context(), symbolName)) {
6959     Say(symbolName,
6960         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6961     return;
6962   }
6963   GenericDetails genericDetails;
6964   Symbol *existing{nullptr};
6965   // Check all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
6966   for (const std::string &n : GetAllNames(context(), symbolName)) {
6967     existing = currScope().FindSymbol(n);
6968     if (existing) {
6969       break;
6970     }
6971   }
6972   if (existing) {
6973     Symbol &ultimate{existing->GetUltimate()};
6974     if (const auto *existingGeneric{ultimate.detailsIf<GenericDetails>()}) {
6975       if (&ultimate.owner() != &currScope()) {
6976         // Create a local copy of a host or use associated generic so that
6977         // it can be locally extended without corrupting the original.
6978         genericDetails.CopyFrom(*existingGeneric);
6979         if (const auto *use{existing->detailsIf<UseDetails>()}) {
6980           AddGenericUse(genericDetails, existing->name(), use->symbol());
6981           EraseSymbol(*existing);
6982         }
6983         existing = &MakeSymbol(symbolName, Attrs{}, std::move(genericDetails));
6984       }
6985       info.Resolve(existing);
6986       return;
6987     }
6988     if (&existing->owner() == &currScope()) {
6989       if (ultimate.has<SubprogramDetails>() ||
6990           ultimate.has<SubprogramNameDetails>()) {
6991         genericDetails.set_specific(ultimate);
6992       } else if (ultimate.has<DerivedTypeDetails>()) {
6993         genericDetails.set_derivedType(ultimate);
6994       } else {
6995         SayAlreadyDeclared(symbolName, *existing);
6996         return;
6997       }
6998       EraseSymbol(*existing);
6999     }
7000   }
7001   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
7002 }
7003 
7004 void ResolveNamesVisitor::FinishSpecificationPart(
7005     const std::list<parser::DeclarationConstruct> &decls) {
7006   badStmtFuncFound_ = false;
7007   funcResultStack().CompleteFunctionResultType();
7008   CheckImports();
7009   bool inModule{currScope().kind() == Scope::Kind::Module};
7010   for (auto &pair : currScope()) {
7011     auto &symbol{*pair.second};
7012     if (NeedsExplicitType(symbol)) {
7013       ApplyImplicitRules(symbol);
7014     }
7015     if (IsDummy(symbol) && isImplicitNoneType() &&
7016         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
7017       Say(symbol.name(),
7018           "No explicit type declared for dummy argument '%s'"_err_en_US);
7019       context().SetError(symbol);
7020     }
7021     if (symbol.has<GenericDetails>()) {
7022       CheckGenericProcedures(symbol);
7023     }
7024     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
7025         !symbol.test(Symbol::Flag::Function) &&
7026         !symbol.test(Symbol::Flag::Subroutine)) {
7027       // in a module, external proc without return type is subroutine
7028       symbol.set(
7029           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
7030     }
7031     if (!symbol.has<HostAssocDetails>()) {
7032       CheckPossibleBadForwardRef(symbol);
7033     }
7034   }
7035   currScope().InstantiateDerivedTypes();
7036   for (const auto &decl : decls) {
7037     if (const auto *statement{std::get_if<
7038             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
7039             &decl.u)}) {
7040       AnalyzeStmtFunctionStmt(statement->statement.value());
7041     }
7042   }
7043   // TODO: what about instantiations in BLOCK?
7044   CheckSaveStmts();
7045   CheckCommonBlocks();
7046   if (!inInterfaceBlock()) {
7047     // TODO: warn for the case where the EQUIVALENCE statement is in a
7048     // procedure declaration in an interface block
7049     CheckEquivalenceSets();
7050   }
7051 }
7052 
7053 // Analyze the bodies of statement functions now that the symbols in this
7054 // specification part have been fully declared and implicitly typed.
7055 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
7056     const parser::StmtFunctionStmt &stmtFunc) {
7057   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
7058   if (!symbol || !symbol->has<SubprogramDetails>()) {
7059     return;
7060   }
7061   auto &details{symbol->get<SubprogramDetails>()};
7062   auto expr{AnalyzeExpr(
7063       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
7064   if (!expr) {
7065     context().SetError(*symbol);
7066     return;
7067   }
7068   if (auto type{evaluate::DynamicType::From(*symbol)}) {
7069     auto converted{ConvertToType(*type, std::move(*expr))};
7070     if (!converted) {
7071       context().SetError(*symbol);
7072       return;
7073     }
7074     details.set_stmtFunction(std::move(*converted));
7075   } else {
7076     details.set_stmtFunction(std::move(*expr));
7077   }
7078 }
7079 
7080 void ResolveNamesVisitor::CheckImports() {
7081   auto &scope{currScope()};
7082   switch (scope.GetImportKind()) {
7083   case common::ImportKind::None:
7084     break;
7085   case common::ImportKind::All:
7086     // C8102: all entities in host must not be hidden
7087     for (const auto &pair : scope.parent()) {
7088       auto &name{pair.first};
7089       std::optional<SourceName> scopeName{scope.GetName()};
7090       if (!scopeName || name != *scopeName) {
7091         CheckImport(prevImportStmt_.value(), name);
7092       }
7093     }
7094     break;
7095   case common::ImportKind::Default:
7096   case common::ImportKind::Only:
7097     // C8102: entities named in IMPORT must not be hidden
7098     for (auto &name : scope.importNames()) {
7099       CheckImport(name, name);
7100     }
7101     break;
7102   }
7103 }
7104 
7105 void ResolveNamesVisitor::CheckImport(
7106     const SourceName &location, const SourceName &name) {
7107   if (auto *symbol{FindInScope(name)}) {
7108     const Symbol &ultimate{symbol->GetUltimate()};
7109     if (&ultimate.owner() == &currScope()) {
7110       Say(location, "'%s' from host is not accessible"_err_en_US, name)
7111           .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
7112               symbol->name());
7113     }
7114   }
7115 }
7116 
7117 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
7118   return CheckNotInBlock("IMPLICIT") && // C1107
7119       ImplicitRulesVisitor::Pre(x);
7120 }
7121 
7122 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
7123   common::visit(common::visitors{
7124                     [&](const parser::Name &x) { ResolveName(x); },
7125                     [&](const parser::StructureComponent &x) {
7126                       ResolveStructureComponent(x);
7127                     },
7128                 },
7129       x.u);
7130 }
7131 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
7132   common::visit(common::visitors{
7133                     [&](const parser::Name &x) { ResolveName(x); },
7134                     [&](const parser::StructureComponent &x) {
7135                       ResolveStructureComponent(x);
7136                     },
7137                 },
7138       x.u);
7139 }
7140 
7141 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
7142   const auto &dataRef{std::get<parser::DataRef>(x.t)};
7143   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
7144   const auto &expr{std::get<parser::Expr>(x.t)};
7145   ResolveDataRef(dataRef);
7146   Walk(bounds);
7147   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
7148   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
7149     if (NameIsKnownOrIntrinsic(*name)) {
7150       // If the name is known because it is an object entity from a host
7151       // procedure, create a host associated symbol.
7152       if (Symbol * symbol{name->symbol}; symbol &&
7153           symbol->GetUltimate().has<ObjectEntityDetails>() &&
7154           IsUplevelReference(*symbol)) {
7155         MakeHostAssocSymbol(*name, *symbol);
7156       }
7157       return false;
7158     }
7159   }
7160   Walk(expr);
7161   return false;
7162 }
7163 void ResolveNamesVisitor::Post(const parser::Designator &x) {
7164   ResolveDesignator(x);
7165 }
7166 
7167 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
7168   ResolveStructureComponent(x.v.thing);
7169 }
7170 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
7171   DeclTypeSpecVisitor::Post(x);
7172   ConstructVisitor::Post(x);
7173 }
7174 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
7175   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
7176   if (HandleStmtFunction(x)) {
7177     return false;
7178   } else {
7179     // This is an array element assignment: resolve names of indices
7180     const auto &names{std::get<std::list<parser::Name>>(x.t)};
7181     for (auto &name : names) {
7182       ResolveName(name);
7183     }
7184     return true;
7185   }
7186 }
7187 
7188 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
7189   const parser::Name &name{x.v};
7190   if (FindSymbol(name)) {
7191     // OK
7192   } else if (IsLogicalConstant(context(), name.source)) {
7193     Say(name,
7194         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7195   } else {
7196     // Resolved later in expression semantics
7197     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
7198   }
7199   return false;
7200 }
7201 
7202 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
7203   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7204     ConvertToObjectEntity(DEREF(name->symbol));
7205   }
7206 }
7207 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
7208   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7209     ConvertToObjectEntity(DEREF(name->symbol));
7210   }
7211 }
7212 
7213 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
7214   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
7215           x.u)) {
7216     // TODO: global directives
7217     return true;
7218   }
7219   auto root{ProgramTree::Build(x)};
7220   SetScope(topScope_);
7221   ResolveSpecificationParts(root);
7222   FinishSpecificationParts(root);
7223   inExecutionPart_ = true;
7224   ResolveExecutionParts(root);
7225   inExecutionPart_ = false;
7226   ResolveAccParts(context(), x);
7227   ResolveOmpParts(context(), x);
7228   return false;
7229 }
7230 
7231 // References to procedures need to record that their symbols are known
7232 // to be procedures, so that they don't get converted to objects by default.
7233 class ExecutionPartSkimmer {
7234 public:
7235   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
7236       : resolver_{resolver} {}
7237 
7238   void Walk(const parser::ExecutionPart *exec) {
7239     if (exec) {
7240       parser::Walk(*exec, *this);
7241     }
7242   }
7243 
7244   template <typename A> bool Pre(const A &) { return true; }
7245   template <typename A> void Post(const A &) {}
7246   void Post(const parser::FunctionReference &fr) {
7247     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
7248   }
7249   void Post(const parser::CallStmt &cs) {
7250     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
7251   }
7252 
7253 private:
7254   ResolveNamesVisitor &resolver_;
7255 };
7256 
7257 // Build the scope tree and resolve names in the specification parts of this
7258 // node and its children
7259 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
7260   if (node.isSpecificationPartResolved()) {
7261     return; // been here already
7262   }
7263   node.set_isSpecificationPartResolved();
7264   if (!BeginScopeForNode(node)) {
7265     return; // an error prevented scope from being created
7266   }
7267   Scope &scope{currScope()};
7268   node.set_scope(scope);
7269   AddSubpNames(node);
7270   common::visit(
7271       [&](const auto *x) {
7272         if (x) {
7273           Walk(*x);
7274         }
7275       },
7276       node.stmt());
7277   Walk(node.spec());
7278   // If this is a function, convert result to an object. This is to prevent the
7279   // result from being converted later to a function symbol if it is called
7280   // inside the function.
7281   // If the result is function pointer, then ConvertToObjectEntity will not
7282   // convert the result to an object, and calling the symbol inside the function
7283   // will result in calls to the result pointer.
7284   // A function cannot be called recursively if RESULT was not used to define a
7285   // distinct result name (15.6.2.2 point 4.).
7286   if (Symbol * symbol{scope.symbol()}) {
7287     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
7288       if (details->isFunction()) {
7289         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
7290       }
7291     }
7292   }
7293   if (node.IsModule()) {
7294     ApplyDefaultAccess();
7295   }
7296   for (auto &child : node.children()) {
7297     ResolveSpecificationParts(child);
7298   }
7299   ExecutionPartSkimmer{*this}.Walk(node.exec());
7300   EndScopeForNode(node);
7301   // Ensure that every object entity has a type.
7302   for (auto &pair : *node.scope()) {
7303     ApplyImplicitRules(*pair.second);
7304   }
7305 }
7306 
7307 // Add SubprogramNameDetails symbols for module and internal subprograms and
7308 // their ENTRY statements.
7309 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
7310   auto kind{
7311       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
7312   for (auto &child : node.children()) {
7313     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
7314     auto childKind{child.GetKind()};
7315     if (childKind == ProgramTree::Kind::Function) {
7316       symbol.set(Symbol::Flag::Function);
7317     } else if (childKind == ProgramTree::Kind::Subroutine) {
7318       symbol.set(Symbol::Flag::Subroutine);
7319     }
7320     for (const auto &entryStmt : child.entryStmts()) {
7321       SubprogramNameDetails details{kind, child};
7322       details.set_isEntryStmt();
7323       auto &symbol{
7324           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
7325       symbol.set(child.GetSubpFlag());
7326     }
7327   }
7328   for (const auto &generic : node.genericSpecs()) {
7329     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
7330       if (currScope().find(name->source) != currScope().end()) {
7331         // If this scope has both a generic interface and a contained
7332         // subprogram with the same name, create the generic's symbol
7333         // now so that any other generics of the same name that are pulled
7334         // into scope later via USE association will properly merge instead
7335         // of raising a bogus error due a conflict with the subprogram.
7336         CreateGeneric(*generic);
7337       }
7338     }
7339   }
7340 }
7341 
7342 // Push a new scope for this node or return false on error.
7343 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
7344   switch (node.GetKind()) {
7345     SWITCH_COVERS_ALL_CASES
7346   case ProgramTree::Kind::Program:
7347     PushScope(Scope::Kind::MainProgram,
7348         &MakeSymbol(node.name(), MainProgramDetails{}));
7349     return true;
7350   case ProgramTree::Kind::Function:
7351   case ProgramTree::Kind::Subroutine:
7352     return BeginSubprogram(node.name(), node.GetSubpFlag(),
7353         node.HasModulePrefix(), node.bindingSpec());
7354   case ProgramTree::Kind::MpSubprogram:
7355     return BeginMpSubprogram(node.name());
7356   case ProgramTree::Kind::Module:
7357     BeginModule(node.name(), false);
7358     return true;
7359   case ProgramTree::Kind::Submodule:
7360     return BeginSubmodule(node.name(), node.GetParentId());
7361   case ProgramTree::Kind::BlockData:
7362     PushBlockDataScope(node.name());
7363     return true;
7364   }
7365 }
7366 
7367 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
7368   EndSubprogram();
7369 }
7370 
7371 // Some analyses and checks, such as the processing of initializers of
7372 // pointers, are deferred until all of the pertinent specification parts
7373 // have been visited.  This deferred processing enables the use of forward
7374 // references in these circumstances.
7375 class DeferredCheckVisitor {
7376 public:
7377   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7378       : resolver_{resolver} {}
7379 
7380   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7381 
7382   template <typename A> bool Pre(const A &) { return true; }
7383   template <typename A> void Post(const A &) {}
7384 
7385   void Post(const parser::DerivedTypeStmt &x) {
7386     const auto &name{std::get<parser::Name>(x.t)};
7387     if (Symbol * symbol{name.symbol}) {
7388       if (Scope * scope{symbol->scope()}) {
7389         if (scope->IsDerivedType()) {
7390           resolver_.PushScope(*scope);
7391           pushedScope_ = true;
7392         }
7393       }
7394     }
7395   }
7396   void Post(const parser::EndTypeStmt &) {
7397     if (pushedScope_) {
7398       resolver_.PopScope();
7399       pushedScope_ = false;
7400     }
7401   }
7402 
7403   void Post(const parser::ProcInterface &pi) {
7404     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7405       resolver_.CheckExplicitInterface(*name);
7406     }
7407   }
7408   bool Pre(const parser::EntityDecl &decl) {
7409     Init(std::get<parser::Name>(decl.t),
7410         std::get<std::optional<parser::Initialization>>(decl.t));
7411     return false;
7412   }
7413   bool Pre(const parser::ComponentDecl &decl) {
7414     Init(std::get<parser::Name>(decl.t),
7415         std::get<std::optional<parser::Initialization>>(decl.t));
7416     return false;
7417   }
7418   bool Pre(const parser::ProcDecl &decl) {
7419     if (const auto &init{
7420             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7421       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7422     }
7423     return false;
7424   }
7425   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7426     resolver_.CheckExplicitInterface(tbps.interfaceName);
7427   }
7428   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7429     if (pushedScope_) {
7430       resolver_.CheckBindings(tbps);
7431     }
7432   }
7433 
7434 private:
7435   void Init(const parser::Name &name,
7436       const std::optional<parser::Initialization> &init) {
7437     if (init) {
7438       if (const auto *target{
7439               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7440         resolver_.PointerInitialization(name, *target);
7441       }
7442     }
7443   }
7444 
7445   ResolveNamesVisitor &resolver_;
7446   bool pushedScope_{false};
7447 };
7448 
7449 // Perform checks and completions that need to happen after all of
7450 // the specification parts but before any of the execution parts.
7451 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7452   if (!node.scope()) {
7453     return; // error occurred creating scope
7454   }
7455   SetScope(*node.scope());
7456   // The initializers of pointers, the default initializers of pointer
7457   // components, and non-deferred type-bound procedure bindings have not
7458   // yet been traversed.
7459   // We do that now, when any (formerly) forward references that appear
7460   // in those initializers will resolve to the right symbols without
7461   // incurring spurious errors with IMPLICIT NONE.
7462   DeferredCheckVisitor{*this}.Walk(node.spec());
7463   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7464   for (Scope &childScope : currScope().children()) {
7465     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7466       FinishDerivedTypeInstantiation(childScope);
7467     }
7468   }
7469   for (const auto &child : node.children()) {
7470     FinishSpecificationParts(child);
7471   }
7472 }
7473 
7474 // Duplicate and fold component object pointer default initializer designators
7475 // using the actual type parameter values of each particular instantiation.
7476 // Validation is done later in declaration checking.
7477 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7478   CHECK(scope.IsDerivedType() && !scope.symbol());
7479   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7480     spec->Instantiate(currScope());
7481     const Symbol &origTypeSymbol{spec->typeSymbol()};
7482     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7483       CHECK(origTypeScope->IsDerivedType() &&
7484           origTypeScope->symbol() == &origTypeSymbol);
7485       auto &foldingContext{GetFoldingContext()};
7486       auto restorer{foldingContext.WithPDTInstance(*spec)};
7487       for (auto &pair : scope) {
7488         Symbol &comp{*pair.second};
7489         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7490         if (IsPointer(comp)) {
7491           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7492             auto origDetails{origComp.get<ObjectEntityDetails>()};
7493             if (const MaybeExpr & init{origDetails.init()}) {
7494               SomeExpr newInit{*init};
7495               MaybeExpr folded{
7496                   evaluate::Fold(foldingContext, std::move(newInit))};
7497               details->set_init(std::move(folded));
7498             }
7499           }
7500         }
7501       }
7502     }
7503   }
7504 }
7505 
7506 // Resolve names in the execution part of this node and its children
7507 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7508   if (!node.scope()) {
7509     return; // error occurred creating scope
7510   }
7511   SetScope(*node.scope());
7512   if (const auto *exec{node.exec()}) {
7513     Walk(*exec);
7514   }
7515   FinishNamelists();
7516   PopScope(); // converts unclassified entities into objects
7517   for (const auto &child : node.children()) {
7518     ResolveExecutionParts(child);
7519   }
7520 }
7521 
7522 void ResolveNamesVisitor::Post(const parser::Program &) {
7523   // ensure that all temps were deallocated
7524   CHECK(!attrs_);
7525   CHECK(!GetDeclTypeSpec());
7526 }
7527 
7528 // A singleton instance of the scope -> IMPLICIT rules mapping is
7529 // shared by all instances of ResolveNamesVisitor and accessed by this
7530 // pointer when the visitors (other than the top-level original) are
7531 // constructed.
7532 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7533 
7534 bool ResolveNames(
7535     SemanticsContext &context, const parser::Program &program, Scope &top) {
7536   ImplicitRulesMap implicitRulesMap;
7537   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7538   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7539   return !context.AnyFatalError();
7540 }
7541 
7542 // Processes a module (but not internal) function when it is referenced
7543 // in a specification expression in a sibling procedure.
7544 void ResolveSpecificationParts(
7545     SemanticsContext &context, const Symbol &subprogram) {
7546   auto originalLocation{context.location()};
7547   ImplicitRulesMap implicitRulesMap;
7548   bool localImplicitRulesMap{false};
7549   if (!sharedImplicitRulesMap) {
7550     sharedImplicitRulesMap = &implicitRulesMap;
7551     localImplicitRulesMap = true;
7552   }
7553   ResolveNamesVisitor visitor{
7554       context, *sharedImplicitRulesMap, context.globalScope()};
7555   const auto &details{subprogram.get<SubprogramNameDetails>()};
7556   ProgramTree &node{details.node()};
7557   const Scope &moduleScope{subprogram.owner()};
7558   if (localImplicitRulesMap) {
7559     visitor.BeginScope(const_cast<Scope &>(moduleScope));
7560   } else {
7561     visitor.SetScope(const_cast<Scope &>(moduleScope));
7562   }
7563   visitor.ResolveSpecificationParts(node);
7564   context.set_location(std::move(originalLocation));
7565   if (localImplicitRulesMap) {
7566     sharedImplicitRulesMap = nullptr;
7567   }
7568 }
7569 
7570 } // namespace Fortran::semantics
7571