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     explicit FuncInfo(const Scope &s) : scope{s} {}
468     const Scope &scope;
469     // Parse tree of the type specification in the FUNCTION prefix
470     const parser::DeclarationTypeSpec *parsedType{nullptr};
471     // Name of the function RESULT in the FUNCTION suffix, if any
472     const parser::Name *resultName{nullptr};
473     // Result symbol
474     Symbol *resultSymbol{nullptr};
475     std::optional<SourceName> source;
476     bool inFunctionStmt{false}; // true between Pre/Post of FunctionStmt
477   };
478 
479   // Completes the definition of the top function's result.
480   void CompleteFunctionResultType();
481   // Completes the definition of a symbol if it is the top function's result.
482   void CompleteTypeIfFunctionResult(Symbol &);
483 
484   FuncInfo *Top() { return stack_.empty() ? nullptr : &stack_.back(); }
485   FuncInfo &Push(const Scope &scope) { return stack_.emplace_back(scope); }
486   void Pop();
487 
488 private:
489   ScopeHandler &scopeHandler_;
490   std::vector<FuncInfo> stack_;
491 };
492 
493 // Manage a stack of Scopes
494 class ScopeHandler : public ImplicitRulesVisitor {
495 public:
496   using ImplicitRulesVisitor::Post;
497   using ImplicitRulesVisitor::Pre;
498 
499   Scope &currScope() { return DEREF(currScope_); }
500   // The enclosing host procedure if current scope is in an internal procedure
501   Scope *GetHostProcedure();
502   // The innermost enclosing program unit scope, ignoring BLOCK and other
503   // construct scopes.
504   Scope &InclusiveScope();
505   // The enclosing scope, skipping derived types.
506   Scope &NonDerivedTypeScope();
507 
508   // Create a new scope and push it on the scope stack.
509   void PushScope(Scope::Kind kind, Symbol *symbol);
510   void PushScope(Scope &scope);
511   void PopScope();
512   void SetScope(Scope &);
513 
514   template <typename T> bool Pre(const parser::Statement<T> &x) {
515     messageHandler().set_currStmtSource(x.source);
516     currScope_->AddSourceRange(x.source);
517     return true;
518   }
519   template <typename T> void Post(const parser::Statement<T> &) {
520     messageHandler().set_currStmtSource(std::nullopt);
521   }
522 
523   // Special messages: already declared; referencing symbol's declaration;
524   // about a type; two names & locations
525   void SayAlreadyDeclared(const parser::Name &, Symbol &);
526   void SayAlreadyDeclared(const SourceName &, Symbol &);
527   void SayAlreadyDeclared(const SourceName &, const SourceName &);
528   void SayWithReason(
529       const parser::Name &, Symbol &, MessageFixedText &&, Message &&);
530   void SayWithDecl(const parser::Name &, Symbol &, MessageFixedText &&);
531   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
532   void SayDerivedType(const SourceName &, MessageFixedText &&, const Scope &);
533   void Say2(const SourceName &, MessageFixedText &&, const SourceName &,
534       MessageFixedText &&);
535   void Say2(
536       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
537   void Say2(
538       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
539 
540   // Search for symbol by name in current, parent derived type, and
541   // containing scopes
542   Symbol *FindSymbol(const parser::Name &);
543   Symbol *FindSymbol(const Scope &, const parser::Name &);
544   // Search for name only in scope, not in enclosing scopes.
545   Symbol *FindInScope(const Scope &, const parser::Name &);
546   Symbol *FindInScope(const Scope &, const SourceName &);
547   template <typename T> Symbol *FindInScope(const T &name) {
548     return FindInScope(currScope(), name);
549   }
550   // Search for name in a derived type scope and its parents.
551   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
552   Symbol *FindInTypeOrParents(const parser::Name &);
553   void EraseSymbol(const parser::Name &);
554   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
555   // Make a new symbol with the name and attrs of an existing one
556   Symbol &CopySymbol(const SourceName &, const Symbol &);
557 
558   // Make symbols in the current or named scope
559   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
560   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
561   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
562   Symbol &MakeHostAssocSymbol(const parser::Name &, const Symbol &);
563 
564   template <typename D>
565   common::IfNoLvalue<Symbol &, D> MakeSymbol(
566       const parser::Name &name, D &&details) {
567     return MakeSymbol(name, Attrs{}, std::move(details));
568   }
569 
570   template <typename D>
571   common::IfNoLvalue<Symbol &, D> MakeSymbol(
572       const parser::Name &name, const Attrs &attrs, D &&details) {
573     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
574   }
575 
576   template <typename D>
577   common::IfNoLvalue<Symbol &, D> MakeSymbol(
578       const SourceName &name, const Attrs &attrs, D &&details) {
579     // Note: don't use FindSymbol here. If this is a derived type scope,
580     // we want to detect whether the name is already declared as a component.
581     auto *symbol{FindInScope(name)};
582     if (!symbol) {
583       symbol = &MakeSymbol(name, attrs);
584       symbol->set_details(std::move(details));
585       return *symbol;
586     }
587     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
588       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
589         if (!d->specific()) {
590           // derived type with same name as a generic
591           auto *derivedType{d->derivedType()};
592           if (!derivedType) {
593             derivedType =
594                 &currScope().MakeSymbol(name, attrs, std::move(details));
595             d->set_derivedType(*derivedType);
596           } else if (derivedType->CanReplaceDetails(details)) {
597             // was forward-referenced
598             derivedType->attrs() |= attrs;
599             derivedType->set_details(std::move(details));
600           } else {
601             SayAlreadyDeclared(name, *derivedType);
602           }
603           return *derivedType;
604         }
605       }
606     }
607     if (symbol->CanReplaceDetails(details)) {
608       // update the existing symbol
609       symbol->attrs() |= attrs;
610       if constexpr (std::is_same_v<SubprogramDetails, D>) {
611         // Dummy argument defined by explicit interface
612         details.set_isDummy(IsDummy(*symbol));
613       }
614       symbol->set_details(std::move(details));
615       return *symbol;
616     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
617       symbol->attrs() |= attrs;
618       return *symbol;
619     } else {
620       if (!CheckPossibleBadForwardRef(*symbol)) {
621         if (name.empty() && symbol->name().empty()) {
622           // report the error elsewhere
623           return *symbol;
624         }
625         SayAlreadyDeclared(name, *symbol);
626       }
627       // replace the old symbol with a new one with correct details
628       EraseSymbol(*symbol);
629       auto &result{MakeSymbol(name, attrs, std::move(details))};
630       context().SetError(result);
631       return result;
632     }
633   }
634 
635   void MakeExternal(Symbol &);
636 
637 protected:
638   FuncResultStack &funcResultStack() { return funcResultStack_; }
639 
640   // Apply the implicit type rules to this symbol.
641   void ApplyImplicitRules(Symbol &, bool allowForwardReference = false);
642   bool ImplicitlyTypeForwardRef(Symbol &);
643   void AcquireIntrinsicProcedureFlags(Symbol &);
644   const DeclTypeSpec *GetImplicitType(
645       Symbol &, bool respectImplicitNoneType = true);
646   bool ConvertToObjectEntity(Symbol &);
647   bool ConvertToProcEntity(Symbol &);
648 
649   const DeclTypeSpec &MakeNumericType(
650       TypeCategory, const std::optional<parser::KindSelector> &);
651   const DeclTypeSpec &MakeLogicalType(
652       const std::optional<parser::KindSelector> &);
653   void NotePossibleBadForwardRef(const parser::Name &);
654   std::optional<SourceName> HadForwardRef(const Symbol &) const;
655   bool CheckPossibleBadForwardRef(const Symbol &);
656 
657   bool inSpecificationPart_{false};
658   bool inEquivalenceStmt_{false};
659 
660   // Some information is collected from a specification part for deferred
661   // processing in DeclarationPartVisitor functions (e.g., CheckSaveStmts())
662   // that are called by ResolveNamesVisitor::FinishSpecificationPart().  Since
663   // specification parts can nest (e.g., INTERFACE bodies), the collected
664   // information that is not contained in the scope needs to be packaged
665   // and restorable.
666   struct SpecificationPartState {
667     std::set<SourceName> forwardRefs;
668     // Collect equivalence sets and process at end of specification part
669     std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets;
670     // Names of all common block objects in the scope
671     std::set<SourceName> commonBlockObjects;
672     // Info about about SAVE statements and attributes in current scope
673     struct {
674       std::optional<SourceName> saveAll; // "SAVE" without entity list
675       std::set<SourceName> entities; // names of entities with save attr
676       std::set<SourceName> commons; // names of common blocks with save attr
677     } saveInfo;
678   } specPartState_;
679 
680   // Some declaration processing can and should be deferred to
681   // ResolveExecutionParts() to avoid prematurely creating implicitly-typed
682   // local symbols that should be host associations.
683   struct DeferredDeclarationState {
684     // The content of each namelist group
685     std::list<const parser::NamelistStmt::Group *> namelistGroups;
686   };
687   DeferredDeclarationState *GetDeferredDeclarationState(bool add = false) {
688     if (!add && deferred_.find(&currScope()) == deferred_.end()) {
689       return nullptr;
690     } else {
691       return &deferred_.emplace(&currScope(), DeferredDeclarationState{})
692                   .first->second;
693     }
694   }
695 
696 private:
697   Scope *currScope_{nullptr};
698   FuncResultStack funcResultStack_{*this};
699   std::map<Scope *, DeferredDeclarationState> deferred_;
700 };
701 
702 class ModuleVisitor : public virtual ScopeHandler {
703 public:
704   bool Pre(const parser::AccessStmt &);
705   bool Pre(const parser::Only &);
706   bool Pre(const parser::Rename::Names &);
707   bool Pre(const parser::Rename::Operators &);
708   bool Pre(const parser::UseStmt &);
709   void Post(const parser::UseStmt &);
710 
711   void BeginModule(const parser::Name &, bool isSubmodule);
712   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
713   void ApplyDefaultAccess();
714   Symbol &AddGenericUse(GenericDetails &, const SourceName &, const Symbol &);
715   void AddAndCheckExplicitIntrinsicUse(SourceName, bool isIntrinsic);
716   void ClearUseRenames() { useRenames_.clear(); }
717   void ClearUseOnly() { useOnly_.clear(); }
718   void ClearExplicitIntrinsicUses() {
719     explicitIntrinsicUses_.clear();
720     explicitNonIntrinsicUses_.clear();
721   }
722 
723 private:
724   // The default access spec for this module.
725   Attr defaultAccess_{Attr::PUBLIC};
726   // The location of the last AccessStmt without access-ids, if any.
727   std::optional<SourceName> prevAccessStmt_;
728   // The scope of the module during a UseStmt
729   Scope *useModuleScope_{nullptr};
730   // Names that have appeared in a rename clause of a USE statement
731   std::set<std::pair<SourceName, Scope *>> useRenames_;
732   // Names that have appeared in an ONLY clause of a USE statement
733   std::set<std::pair<SourceName, Scope *>> useOnly_;
734   // Module names that have appeared in USE statements with explicit
735   // INTRINSIC or NON_INTRINSIC keywords
736   std::set<SourceName> explicitIntrinsicUses_;
737   std::set<SourceName> explicitNonIntrinsicUses_;
738 
739   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
740   // A rename in a USE statement: local => use
741   struct SymbolRename {
742     Symbol *local{nullptr};
743     Symbol *use{nullptr};
744   };
745   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
746   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
747   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
748   void DoAddUse(
749       SourceName, SourceName, Symbol &localSymbol, const Symbol &useSymbol);
750   void AddUse(const GenericSpecInfo &);
751   // If appropriate, erase a previously USE-associated symbol
752   void EraseRenamedSymbol(const Symbol &);
753   // Record a name appearing in a USE rename clause
754   void AddUseRename(const SourceName &name) {
755     useRenames_.emplace(std::make_pair(name, useModuleScope_));
756   }
757   bool IsUseRenamed(const SourceName &name) const {
758     return useRenames_.find({name, useModuleScope_}) != useRenames_.end();
759   }
760   // Record a name appearing in a USE ONLY clause
761   void AddUseOnly(const SourceName &name) {
762     useOnly_.emplace(std::make_pair(name, useModuleScope_));
763   }
764   bool IsUseOnly(const SourceName &name) const {
765     return useOnly_.find({name, useModuleScope_}) != useOnly_.end();
766   }
767   Scope *FindModule(const parser::Name &, std::optional<bool> isIntrinsic,
768       Scope *ancestor = nullptr);
769 };
770 
771 class InterfaceVisitor : public virtual ScopeHandler {
772 public:
773   bool Pre(const parser::InterfaceStmt &);
774   void Post(const parser::InterfaceStmt &);
775   void Post(const parser::EndInterfaceStmt &);
776   bool Pre(const parser::GenericSpec &);
777   bool Pre(const parser::ProcedureStmt &);
778   bool Pre(const parser::GenericStmt &);
779   void Post(const parser::GenericStmt &);
780 
781   bool inInterfaceBlock() const;
782   bool isGeneric() const;
783   bool isAbstract() const;
784 
785 protected:
786   Symbol &GetGenericSymbol() { return DEREF(genericInfo_.top().symbol); }
787   // Add to generic the symbol for the subprogram with the same name
788   void CheckGenericProcedures(Symbol &);
789 
790 private:
791   // A new GenericInfo is pushed for each interface block and generic stmt
792   struct GenericInfo {
793     GenericInfo(bool isInterface, bool isAbstract = false)
794         : isInterface{isInterface}, isAbstract{isAbstract} {}
795     bool isInterface; // in interface block
796     bool isAbstract; // in abstract interface block
797     Symbol *symbol{nullptr}; // the generic symbol being defined
798   };
799   std::stack<GenericInfo> genericInfo_;
800   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
801   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
802 
803   using ProcedureKind = parser::ProcedureStmt::Kind;
804   // mapping of generic to its specific proc names and kinds
805   std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>
806       specificProcs_;
807 
808   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
809   void ResolveSpecificsInGeneric(Symbol &generic);
810 };
811 
812 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
813 public:
814   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
815   bool Pre(const parser::SubroutineStmt &);
816   bool Pre(const parser::FunctionStmt &);
817   void Post(const parser::FunctionStmt &);
818   bool Pre(const parser::EntryStmt &);
819   void Post(const parser::EntryStmt &);
820   bool Pre(const parser::InterfaceBody::Subroutine &);
821   void Post(const parser::InterfaceBody::Subroutine &);
822   bool Pre(const parser::InterfaceBody::Function &);
823   void Post(const parser::InterfaceBody::Function &);
824   bool Pre(const parser::Suffix &);
825   bool Pre(const parser::PrefixSpec &);
826 
827   bool BeginSubprogram(const parser::Name &, Symbol::Flag,
828       bool hasModulePrefix = false,
829       const parser::LanguageBindingSpec * = nullptr,
830       const ProgramTree::EntryStmtList * = nullptr);
831   bool BeginMpSubprogram(const parser::Name &);
832   void PushBlockDataScope(const parser::Name &);
833   void EndSubprogram(std::optional<parser::CharBlock> stmtSource = std::nullopt,
834       const std::optional<parser::LanguageBindingSpec> * = nullptr);
835 
836 protected:
837   // Set when we see a stmt function that is really an array element assignment
838   bool badStmtFuncFound_{false};
839 
840 private:
841   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
842   // so that it can be replaced by a later definition.
843   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
844   void CheckExtantProc(const parser::Name &, Symbol::Flag);
845   // Create a subprogram symbol in the current scope and push a new scope.
846   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag,
847       const parser::LanguageBindingSpec * = nullptr);
848   Symbol *GetSpecificFromGeneric(const parser::Name &);
849   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
850   void CreateEntry(const parser::EntryStmt &stmt, Symbol &subprogram);
851   void PostEntryStmt(const parser::EntryStmt &stmt);
852 };
853 
854 class DeclarationVisitor : public ArraySpecVisitor,
855                            public virtual ScopeHandler {
856 public:
857   using ArraySpecVisitor::Post;
858   using ScopeHandler::Post;
859   using ScopeHandler::Pre;
860 
861   bool Pre(const parser::Initialization &);
862   void Post(const parser::EntityDecl &);
863   void Post(const parser::ObjectDecl &);
864   void Post(const parser::PointerDecl &);
865   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
866   void Post(const parser::BindStmt &) { EndAttrs(); }
867   bool Pre(const parser::BindEntity &);
868   bool Pre(const parser::OldParameterStmt &);
869   bool Pre(const parser::NamedConstantDef &);
870   bool Pre(const parser::NamedConstant &);
871   void Post(const parser::EnumDef &);
872   bool Pre(const parser::Enumerator &);
873   bool Pre(const parser::AccessSpec &);
874   bool Pre(const parser::AsynchronousStmt &);
875   bool Pre(const parser::ContiguousStmt &);
876   bool Pre(const parser::ExternalStmt &);
877   bool Pre(const parser::IntentStmt &);
878   bool Pre(const parser::IntrinsicStmt &);
879   bool Pre(const parser::OptionalStmt &);
880   bool Pre(const parser::ProtectedStmt &);
881   bool Pre(const parser::ValueStmt &);
882   bool Pre(const parser::VolatileStmt &);
883   bool Pre(const parser::AllocatableStmt &) {
884     objectDeclAttr_ = Attr::ALLOCATABLE;
885     return true;
886   }
887   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
888   bool Pre(const parser::TargetStmt &) {
889     objectDeclAttr_ = Attr::TARGET;
890     return true;
891   }
892   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
893   void Post(const parser::DimensionStmt::Declaration &);
894   void Post(const parser::CodimensionDecl &);
895   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
896   void Post(const parser::TypeDeclarationStmt &);
897   void Post(const parser::IntegerTypeSpec &);
898   void Post(const parser::IntrinsicTypeSpec::Real &);
899   void Post(const parser::IntrinsicTypeSpec::Complex &);
900   void Post(const parser::IntrinsicTypeSpec::Logical &);
901   void Post(const parser::IntrinsicTypeSpec::Character &);
902   void Post(const parser::CharSelector::LengthAndKind &);
903   void Post(const parser::CharLength &);
904   void Post(const parser::LengthSelector &);
905   bool Pre(const parser::KindParam &);
906   bool Pre(const parser::DeclarationTypeSpec::Type &);
907   void Post(const parser::DeclarationTypeSpec::Type &);
908   bool Pre(const parser::DeclarationTypeSpec::Class &);
909   void Post(const parser::DeclarationTypeSpec::Class &);
910   void Post(const parser::DeclarationTypeSpec::Record &);
911   void Post(const parser::DerivedTypeSpec &);
912   bool Pre(const parser::DerivedTypeDef &);
913   bool Pre(const parser::DerivedTypeStmt &);
914   void Post(const parser::DerivedTypeStmt &);
915   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
916   void Post(const parser::TypeParamDefStmt &);
917   bool Pre(const parser::TypeAttrSpec::Extends &);
918   bool Pre(const parser::PrivateStmt &);
919   bool Pre(const parser::SequenceStmt &);
920   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
921   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
922   void Post(const parser::ComponentDecl &);
923   void Post(const parser::FillDecl &);
924   bool Pre(const parser::ProcedureDeclarationStmt &);
925   void Post(const parser::ProcedureDeclarationStmt &);
926   bool Pre(const parser::DataComponentDefStmt &); // returns false
927   bool Pre(const parser::ProcComponentDefStmt &);
928   void Post(const parser::ProcComponentDefStmt &);
929   bool Pre(const parser::ProcPointerInit &);
930   void Post(const parser::ProcInterface &);
931   void Post(const parser::ProcDecl &);
932   bool Pre(const parser::TypeBoundProcedurePart &);
933   void Post(const parser::TypeBoundProcedurePart &);
934   void Post(const parser::ContainsStmt &);
935   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
936   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
937   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
938   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
939   void Post(const parser::FinalProcedureStmt &);
940   bool Pre(const parser::TypeBoundGenericStmt &);
941   bool Pre(const parser::StructureDef &); // returns false
942   bool Pre(const parser::Union::UnionStmt &);
943   bool Pre(const parser::StructureField &);
944   void Post(const parser::StructureField &);
945   bool Pre(const parser::AllocateStmt &);
946   void Post(const parser::AllocateStmt &);
947   bool Pre(const parser::StructureConstructor &);
948   bool Pre(const parser::NamelistStmt::Group &);
949   bool Pre(const parser::IoControlSpec &);
950   bool Pre(const parser::CommonStmt::Block &);
951   bool Pre(const parser::CommonBlockObject &);
952   void Post(const parser::CommonBlockObject &);
953   bool Pre(const parser::EquivalenceStmt &);
954   bool Pre(const parser::SaveStmt &);
955   bool Pre(const parser::BasedPointerStmt &);
956 
957   void PointerInitialization(
958       const parser::Name &, const parser::InitialDataTarget &);
959   void PointerInitialization(
960       const parser::Name &, const parser::ProcPointerInit &);
961   void NonPointerInitialization(
962       const parser::Name &, const parser::ConstantExpr &);
963   void CheckExplicitInterface(const parser::Name &);
964   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
965 
966   const parser::Name *ResolveDesignator(const parser::Designator &);
967 
968 protected:
969   bool BeginDecl();
970   void EndDecl();
971   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
972   // Make sure that there's an entity in an enclosing scope called Name
973   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
974   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
975   // it comes from the entity in the containing scope, or implicit rules.
976   // Return pointer to the new symbol, or nullptr on error.
977   Symbol *DeclareLocalEntity(const parser::Name &);
978   // Declare a statement entity (i.e., an implied DO loop index for
979   // a DATA statement or an array constructor).  If there isn't an explict
980   // type specified, implicit rules apply. Return pointer to the new symbol,
981   // or nullptr on error.
982   Symbol *DeclareStatementEntity(const parser::DoVariable &,
983       const std::optional<parser::IntegerTypeSpec> &);
984   Symbol &MakeCommonBlockSymbol(const parser::Name &);
985   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
986   bool CheckUseError(const parser::Name &);
987   void CheckAccessibility(const SourceName &, bool, Symbol &);
988   void CheckCommonBlocks();
989   void CheckSaveStmts();
990   void CheckEquivalenceSets();
991   bool CheckNotInBlock(const char *);
992   bool NameIsKnownOrIntrinsic(const parser::Name &);
993   void FinishNamelists();
994 
995   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
996   // or nullptr in case of error.
997   const parser::Name *ResolveStructureComponent(
998       const parser::StructureComponent &);
999   const parser::Name *ResolveDataRef(const parser::DataRef &);
1000   const parser::Name *ResolveName(const parser::Name &);
1001   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
1002   Symbol *NoteInterfaceName(const parser::Name &);
1003   bool IsUplevelReference(const Symbol &);
1004 
1005   std::optional<SourceName> BeginCheckOnIndexUseInOwnBounds(
1006       const parser::DoVariable &name) {
1007     std::optional<SourceName> result{checkIndexUseInOwnBounds_};
1008     checkIndexUseInOwnBounds_ = name.thing.thing.source;
1009     return result;
1010   }
1011   void EndCheckOnIndexUseInOwnBounds(const std::optional<SourceName> &restore) {
1012     checkIndexUseInOwnBounds_ = restore;
1013   }
1014 
1015 private:
1016   // The attribute corresponding to the statement containing an ObjectDecl
1017   std::optional<Attr> objectDeclAttr_;
1018   // Info about current character type while walking DeclTypeSpec.
1019   // Also captures any "*length" specifier on an individual declaration.
1020   struct {
1021     std::optional<ParamValue> length;
1022     std::optional<KindExpr> kind;
1023   } charInfo_;
1024   // Info about current derived type or STRUCTURE while walking
1025   // DerivedTypeDef / StructureDef
1026   struct {
1027     const parser::Name *extends{nullptr}; // EXTENDS(name)
1028     bool privateComps{false}; // components are private by default
1029     bool privateBindings{false}; // bindings are private by default
1030     bool sawContains{false}; // currently processing bindings
1031     bool sequence{false}; // is a sequence type
1032     const Symbol *type{nullptr}; // derived type being defined
1033     bool isStructure{false}; // is a DEC STRUCTURE
1034   } derivedTypeInfo_;
1035   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
1036   // the interface name, if any.
1037   const parser::Name *interfaceName_{nullptr};
1038   // Map type-bound generic to binding names of its specific bindings
1039   std::multimap<Symbol *, const parser::Name *> genericBindings_;
1040   // Info about current ENUM
1041   struct EnumeratorState {
1042     // Enum value must hold inside a C_INT (7.6.2).
1043     std::optional<int> value{0};
1044   } enumerationState_;
1045   // Set for OldParameterStmt processing
1046   bool inOldStyleParameterStmt_{false};
1047   // Set when walking DATA & array constructor implied DO loop bounds
1048   // to warn about use of the implied DO intex therein.
1049   std::optional<SourceName> checkIndexUseInOwnBounds_;
1050 
1051   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
1052   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
1053   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
1054   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
1055   void SetType(const parser::Name &, const DeclTypeSpec &);
1056   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
1057   std::optional<DerivedTypeSpec> ResolveExtendsType(
1058       const parser::Name &, const parser::Name *);
1059   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
1060   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1061   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
1062   ParamValue GetParamValue(
1063       const parser::TypeParamValue &, common::TypeParamAttr attr);
1064   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
1065   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
1066   Attrs HandleSaveName(const SourceName &, Attrs);
1067   void AddSaveName(std::set<SourceName> &, const SourceName &);
1068   void SetSaveAttr(Symbol &);
1069   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1070   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1071   void Initialization(const parser::Name &, const parser::Initialization &,
1072       bool inComponentDecl);
1073   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
1074   bool CheckForHostAssociatedImplicit(const parser::Name &);
1075 
1076   // Declare an object or procedure entity.
1077   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1078   template <typename T>
1079   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1080     Symbol &symbol{MakeSymbol(name, attrs)};
1081     if (context().HasError(symbol) || symbol.has<T>()) {
1082       return symbol; // OK or error already reported
1083     } else if (symbol.has<UnknownDetails>()) {
1084       symbol.set_details(T{});
1085       return symbol;
1086     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1087       symbol.set_details(T{std::move(*details)});
1088       return symbol;
1089     } else if (std::is_same_v<EntityDetails, T> &&
1090         (symbol.has<ObjectEntityDetails>() ||
1091             symbol.has<ProcEntityDetails>())) {
1092       return symbol; // OK
1093     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1094       Say(name.source,
1095           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1096           name.source, GetUsedModule(*details).name());
1097     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1098       if (details->kind() == SubprogramKind::Module) {
1099         Say2(name,
1100             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1101             symbol, "Module procedure definition"_en_US);
1102       } else if (details->kind() == SubprogramKind::Internal) {
1103         Say2(name,
1104             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1105             symbol, "Internal procedure definition"_en_US);
1106       } else {
1107         DIE("unexpected kind");
1108       }
1109     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1110         symbol.has<ProcEntityDetails>()) {
1111       SayWithDecl(
1112           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1113     } else if (std::is_same_v<ProcEntityDetails, T> &&
1114         symbol.has<ObjectEntityDetails>()) {
1115       if (InCommonBlock(symbol)) {
1116         SayWithDecl(name, symbol,
1117             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1118       } else {
1119         SayWithDecl(
1120             name, symbol, "'%s' is already declared as an object"_err_en_US);
1121       }
1122     } else if (!CheckPossibleBadForwardRef(symbol)) {
1123       SayAlreadyDeclared(name, symbol);
1124     }
1125     context().SetError(symbol);
1126     return symbol;
1127   }
1128   bool HasCycle(const Symbol &, const ProcInterface &);
1129 };
1130 
1131 // Resolve construct entities and statement entities.
1132 // Check that construct names don't conflict with other names.
1133 class ConstructVisitor : public virtual DeclarationVisitor {
1134 public:
1135   bool Pre(const parser::ConcurrentHeader &);
1136   bool Pre(const parser::LocalitySpec::Local &);
1137   bool Pre(const parser::LocalitySpec::LocalInit &);
1138   bool Pre(const parser::LocalitySpec::Shared &);
1139   bool Pre(const parser::AcSpec &);
1140   bool Pre(const parser::AcImpliedDo &);
1141   bool Pre(const parser::DataImpliedDo &);
1142   bool Pre(const parser::DataIDoObject &);
1143   bool Pre(const parser::DataStmtObject &);
1144   bool Pre(const parser::DataStmtValue &);
1145   bool Pre(const parser::DoConstruct &);
1146   void Post(const parser::DoConstruct &);
1147   bool Pre(const parser::ForallConstruct &);
1148   void Post(const parser::ForallConstruct &);
1149   bool Pre(const parser::ForallStmt &);
1150   void Post(const parser::ForallStmt &);
1151   bool Pre(const parser::BlockStmt &);
1152   bool Pre(const parser::EndBlockStmt &);
1153   void Post(const parser::Selector &);
1154   void Post(const parser::AssociateStmt &);
1155   void Post(const parser::EndAssociateStmt &);
1156   bool Pre(const parser::Association &);
1157   void Post(const parser::SelectTypeStmt &);
1158   void Post(const parser::SelectRankStmt &);
1159   bool Pre(const parser::SelectTypeConstruct &);
1160   void Post(const parser::SelectTypeConstruct &);
1161   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1162   void Post(const parser::SelectTypeConstruct::TypeCase &);
1163   // Creates Block scopes with neither symbol name nor symbol details.
1164   bool Pre(const parser::SelectRankConstruct::RankCase &);
1165   void Post(const parser::SelectRankConstruct::RankCase &);
1166   void Post(const parser::TypeGuardStmt::Guard &);
1167   void Post(const parser::SelectRankCaseStmt::Rank &);
1168   bool Pre(const parser::ChangeTeamStmt &);
1169   void Post(const parser::EndChangeTeamStmt &);
1170   void Post(const parser::CoarrayAssociation &);
1171 
1172   // Definitions of construct names
1173   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1174   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1175   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1176   bool Pre(const parser::LabelDoStmt &) {
1177     return false; // error recovery
1178   }
1179   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1180   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1181   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1182   bool Pre(const parser::SelectRankConstruct &);
1183   void Post(const parser::SelectRankConstruct &);
1184   bool Pre(const parser::SelectRankStmt &x) {
1185     return CheckDef(std::get<0>(x.t));
1186   }
1187   bool Pre(const parser::SelectTypeStmt &x) {
1188     return CheckDef(std::get<0>(x.t));
1189   }
1190 
1191   // References to construct names
1192   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1193   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1194   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1195   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1196   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1197   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1198   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1199   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1200   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1201   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1202   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1203   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1204   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1205   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1206   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1207 
1208 private:
1209   // R1105 selector -> expr | variable
1210   // expr is set in either case unless there were errors
1211   struct Selector {
1212     Selector() {}
1213     Selector(const SourceName &source, MaybeExpr &&expr)
1214         : source{source}, expr{std::move(expr)} {}
1215     operator bool() const { return expr.has_value(); }
1216     parser::CharBlock source;
1217     MaybeExpr expr;
1218   };
1219   // association -> [associate-name =>] selector
1220   struct Association {
1221     const parser::Name *name{nullptr};
1222     Selector selector;
1223   };
1224   std::vector<Association> associationStack_;
1225   Association *currentAssociation_{nullptr};
1226 
1227   template <typename T> bool CheckDef(const T &t) {
1228     return CheckDef(std::get<std::optional<parser::Name>>(t));
1229   }
1230   template <typename T> void CheckRef(const T &t) {
1231     CheckRef(std::get<std::optional<parser::Name>>(t));
1232   }
1233   bool CheckDef(const std::optional<parser::Name> &);
1234   void CheckRef(const std::optional<parser::Name> &);
1235   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1236   const DeclTypeSpec &ToDeclTypeSpec(
1237       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1238   Symbol *MakeAssocEntity();
1239   void SetTypeFromAssociation(Symbol &);
1240   void SetAttrsFromAssociation(Symbol &);
1241   Selector ResolveSelector(const parser::Selector &);
1242   void ResolveIndexName(const parser::ConcurrentControl &control);
1243   void SetCurrentAssociation(std::size_t n);
1244   Association &GetCurrentAssociation();
1245   void PushAssociation();
1246   void PopAssociation(std::size_t count = 1);
1247 };
1248 
1249 // Create scopes for OpenACC constructs
1250 class AccVisitor : public virtual DeclarationVisitor {
1251 public:
1252   void AddAccSourceRange(const parser::CharBlock &);
1253 
1254   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1255 
1256   bool Pre(const parser::OpenACCBlockConstruct &);
1257   void Post(const parser::OpenACCBlockConstruct &);
1258   bool Pre(const parser::AccBeginBlockDirective &x) {
1259     AddAccSourceRange(x.source);
1260     return true;
1261   }
1262   void Post(const parser::AccBeginBlockDirective &) {
1263     messageHandler().set_currStmtSource(std::nullopt);
1264   }
1265   bool Pre(const parser::AccEndBlockDirective &x) {
1266     AddAccSourceRange(x.source);
1267     return true;
1268   }
1269   void Post(const parser::AccEndBlockDirective &) {
1270     messageHandler().set_currStmtSource(std::nullopt);
1271   }
1272   bool Pre(const parser::AccBeginLoopDirective &x) {
1273     AddAccSourceRange(x.source);
1274     return true;
1275   }
1276   void Post(const parser::AccBeginLoopDirective &x) {
1277     messageHandler().set_currStmtSource(std::nullopt);
1278   }
1279 };
1280 
1281 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1282   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1283   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1284   switch (beginDir.v) {
1285   case llvm::acc::Directive::ACCD_data:
1286   case llvm::acc::Directive::ACCD_host_data:
1287   case llvm::acc::Directive::ACCD_kernels:
1288   case llvm::acc::Directive::ACCD_parallel:
1289   case llvm::acc::Directive::ACCD_serial:
1290     return true;
1291   default:
1292     return false;
1293   }
1294 }
1295 
1296 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1297   messageHandler().set_currStmtSource(source);
1298   currScope().AddSourceRange(source);
1299 }
1300 
1301 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1302   if (NeedsScope(x)) {
1303     PushScope(Scope::Kind::Block, nullptr);
1304   }
1305   return true;
1306 }
1307 
1308 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1309   if (NeedsScope(x)) {
1310     PopScope();
1311   }
1312 }
1313 
1314 // Create scopes for OpenMP constructs
1315 class OmpVisitor : public virtual DeclarationVisitor {
1316 public:
1317   void AddOmpSourceRange(const parser::CharBlock &);
1318 
1319   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1320 
1321   bool Pre(const parser::OpenMPBlockConstruct &);
1322   void Post(const parser::OpenMPBlockConstruct &);
1323   bool Pre(const parser::OmpBeginBlockDirective &x) {
1324     AddOmpSourceRange(x.source);
1325     return true;
1326   }
1327   void Post(const parser::OmpBeginBlockDirective &) {
1328     messageHandler().set_currStmtSource(std::nullopt);
1329   }
1330   bool Pre(const parser::OmpEndBlockDirective &x) {
1331     AddOmpSourceRange(x.source);
1332     return true;
1333   }
1334   void Post(const parser::OmpEndBlockDirective &) {
1335     messageHandler().set_currStmtSource(std::nullopt);
1336   }
1337 
1338   bool Pre(const parser::OpenMPLoopConstruct &) {
1339     PushScope(Scope::Kind::Block, nullptr);
1340     return true;
1341   }
1342   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1343   bool Pre(const parser::OmpBeginLoopDirective &x) {
1344     AddOmpSourceRange(x.source);
1345     return true;
1346   }
1347   void Post(const parser::OmpBeginLoopDirective &) {
1348     messageHandler().set_currStmtSource(std::nullopt);
1349   }
1350   bool Pre(const parser::OmpEndLoopDirective &x) {
1351     AddOmpSourceRange(x.source);
1352     return true;
1353   }
1354   void Post(const parser::OmpEndLoopDirective &) {
1355     messageHandler().set_currStmtSource(std::nullopt);
1356   }
1357 
1358   bool Pre(const parser::OpenMPSectionsConstruct &) {
1359     PushScope(Scope::Kind::Block, nullptr);
1360     return true;
1361   }
1362   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1363   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1364     AddOmpSourceRange(x.source);
1365     return true;
1366   }
1367   void Post(const parser::OmpBeginSectionsDirective &) {
1368     messageHandler().set_currStmtSource(std::nullopt);
1369   }
1370   bool Pre(const parser::OmpEndSectionsDirective &x) {
1371     AddOmpSourceRange(x.source);
1372     return true;
1373   }
1374   void Post(const parser::OmpEndSectionsDirective &) {
1375     messageHandler().set_currStmtSource(std::nullopt);
1376   }
1377 };
1378 
1379 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1380   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1381   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1382   switch (beginDir.v) {
1383   case llvm::omp::Directive::OMPD_target_data:
1384   case llvm::omp::Directive::OMPD_master:
1385   case llvm::omp::Directive::OMPD_ordered:
1386   case llvm::omp::Directive::OMPD_taskgroup:
1387     return false;
1388   default:
1389     return true;
1390   }
1391 }
1392 
1393 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1394   messageHandler().set_currStmtSource(source);
1395   currScope().AddSourceRange(source);
1396 }
1397 
1398 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1399   if (NeedsScope(x)) {
1400     PushScope(Scope::Kind::Block, nullptr);
1401   }
1402   return true;
1403 }
1404 
1405 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1406   if (NeedsScope(x)) {
1407     PopScope();
1408   }
1409 }
1410 
1411 // Walk the parse tree and resolve names to symbols.
1412 class ResolveNamesVisitor : public virtual ScopeHandler,
1413                             public ModuleVisitor,
1414                             public SubprogramVisitor,
1415                             public ConstructVisitor,
1416                             public OmpVisitor,
1417                             public AccVisitor {
1418 public:
1419   using AccVisitor::Post;
1420   using AccVisitor::Pre;
1421   using ArraySpecVisitor::Post;
1422   using ConstructVisitor::Post;
1423   using ConstructVisitor::Pre;
1424   using DeclarationVisitor::Post;
1425   using DeclarationVisitor::Pre;
1426   using ImplicitRulesVisitor::Post;
1427   using ImplicitRulesVisitor::Pre;
1428   using InterfaceVisitor::Post;
1429   using InterfaceVisitor::Pre;
1430   using ModuleVisitor::Post;
1431   using ModuleVisitor::Pre;
1432   using OmpVisitor::Post;
1433   using OmpVisitor::Pre;
1434   using ScopeHandler::Post;
1435   using ScopeHandler::Pre;
1436   using SubprogramVisitor::Post;
1437   using SubprogramVisitor::Pre;
1438 
1439   ResolveNamesVisitor(
1440       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1441       : BaseVisitor{context, *this, rules}, topScope_{top} {
1442     PushScope(top);
1443   }
1444 
1445   Scope &topScope() const { return topScope_; }
1446 
1447   // Default action for a parse tree node is to visit children.
1448   template <typename T> bool Pre(const T &) { return true; }
1449   template <typename T> void Post(const T &) {}
1450 
1451   bool Pre(const parser::SpecificationPart &);
1452   void Post(const parser::Program &);
1453   bool Pre(const parser::ImplicitStmt &);
1454   void Post(const parser::PointerObject &);
1455   void Post(const parser::AllocateObject &);
1456   bool Pre(const parser::PointerAssignmentStmt &);
1457   void Post(const parser::Designator &);
1458   template <typename A, typename B>
1459   void Post(const parser::LoopBounds<A, B> &x) {
1460     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1461   }
1462   void Post(const parser::ProcComponentRef &);
1463   bool Pre(const parser::FunctionReference &);
1464   bool Pre(const parser::CallStmt &);
1465   bool Pre(const parser::ImportStmt &);
1466   void Post(const parser::TypeGuardStmt &);
1467   bool Pre(const parser::StmtFunctionStmt &);
1468   bool Pre(const parser::DefinedOpName &);
1469   bool Pre(const parser::ProgramUnit &);
1470   void Post(const parser::AssignStmt &);
1471   void Post(const parser::AssignedGotoStmt &);
1472 
1473   // These nodes should never be reached: they are handled in ProgramUnit
1474   bool Pre(const parser::MainProgram &) {
1475     llvm_unreachable("This node is handled in ProgramUnit");
1476   }
1477   bool Pre(const parser::FunctionSubprogram &) {
1478     llvm_unreachable("This node is handled in ProgramUnit");
1479   }
1480   bool Pre(const parser::SubroutineSubprogram &) {
1481     llvm_unreachable("This node is handled in ProgramUnit");
1482   }
1483   bool Pre(const parser::SeparateModuleSubprogram &) {
1484     llvm_unreachable("This node is handled in ProgramUnit");
1485   }
1486   bool Pre(const parser::Module &) {
1487     llvm_unreachable("This node is handled in ProgramUnit");
1488   }
1489   bool Pre(const parser::Submodule &) {
1490     llvm_unreachable("This node is handled in ProgramUnit");
1491   }
1492   bool Pre(const parser::BlockData &) {
1493     llvm_unreachable("This node is handled in ProgramUnit");
1494   }
1495 
1496   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1497 
1498   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1499 
1500 private:
1501   // Kind of procedure we are expecting to see in a ProcedureDesignator
1502   std::optional<Symbol::Flag> expectedProcFlag_;
1503   std::optional<SourceName> prevImportStmt_;
1504   Scope &topScope_;
1505 
1506   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1507   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1508   void CreateGeneric(const parser::GenericSpec &);
1509   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1510   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1511   void CheckImports();
1512   void CheckImport(const SourceName &, const SourceName &);
1513   void HandleCall(Symbol::Flag, const parser::Call &);
1514   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1515   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1516   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1517   void ResolveSpecificationParts(ProgramTree &);
1518   void AddSubpNames(ProgramTree &);
1519   bool BeginScopeForNode(const ProgramTree &);
1520   void EndScopeForNode(const ProgramTree &);
1521   void FinishSpecificationParts(const ProgramTree &);
1522   void FinishDerivedTypeInstantiation(Scope &);
1523   void ResolveExecutionParts(const ProgramTree &);
1524 };
1525 
1526 // ImplicitRules implementation
1527 
1528 bool ImplicitRules::isImplicitNoneType() const {
1529   if (isImplicitNoneType_) {
1530     return true;
1531   } else if (map_.empty() && inheritFromParent_) {
1532     return parent_->isImplicitNoneType();
1533   } else {
1534     return false; // default if not specified
1535   }
1536 }
1537 
1538 bool ImplicitRules::isImplicitNoneExternal() const {
1539   if (isImplicitNoneExternal_) {
1540     return true;
1541   } else if (inheritFromParent_) {
1542     return parent_->isImplicitNoneExternal();
1543   } else {
1544     return false; // default if not specified
1545   }
1546 }
1547 
1548 const DeclTypeSpec *ImplicitRules::GetType(
1549     SourceName name, bool respectImplicitNoneType) const {
1550   char ch{name.begin()[0]};
1551   if (isImplicitNoneType_ && respectImplicitNoneType) {
1552     return nullptr;
1553   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1554     return &*it->second;
1555   } else if (inheritFromParent_) {
1556     return parent_->GetType(name, respectImplicitNoneType);
1557   } else if (ch >= 'i' && ch <= 'n') {
1558     return &context_.MakeNumericType(TypeCategory::Integer);
1559   } else if (ch >= 'a' && ch <= 'z') {
1560     return &context_.MakeNumericType(TypeCategory::Real);
1561   } else {
1562     return nullptr;
1563   }
1564 }
1565 
1566 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1567     parser::Location fromLetter, parser::Location toLetter) {
1568   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1569     auto res{map_.emplace(ch, type)};
1570     if (!res.second) {
1571       context_.Say(parser::CharBlock{fromLetter},
1572           "More than one implicit type specified for '%c'"_err_en_US, ch);
1573     }
1574     if (ch == *toLetter) {
1575       break;
1576     }
1577   }
1578 }
1579 
1580 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1581 // Return '\0' for the char after 'z'.
1582 char ImplicitRules::Incr(char ch) {
1583   switch (ch) {
1584   case 'i':
1585     return 'j';
1586   case 'r':
1587     return 's';
1588   case 'z':
1589     return '\0';
1590   default:
1591     return ch + 1;
1592   }
1593 }
1594 
1595 llvm::raw_ostream &operator<<(
1596     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1597   o << "ImplicitRules:\n";
1598   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1599     ShowImplicitRule(o, implicitRules, ch);
1600   }
1601   ShowImplicitRule(o, implicitRules, '_');
1602   ShowImplicitRule(o, implicitRules, '$');
1603   ShowImplicitRule(o, implicitRules, '@');
1604   return o;
1605 }
1606 void ShowImplicitRule(
1607     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1608   auto it{implicitRules.map_.find(ch)};
1609   if (it != implicitRules.map_.end()) {
1610     o << "  " << ch << ": " << *it->second << '\n';
1611   }
1612 }
1613 
1614 template <typename T> void BaseVisitor::Walk(const T &x) {
1615   parser::Walk(x, *this_);
1616 }
1617 
1618 void BaseVisitor::MakePlaceholder(
1619     const parser::Name &name, MiscDetails::Kind kind) {
1620   if (!name.symbol) {
1621     name.symbol = &context_->globalScope().MakeSymbol(
1622         name.source, Attrs{}, MiscDetails{kind});
1623   }
1624 }
1625 
1626 // AttrsVisitor implementation
1627 
1628 bool AttrsVisitor::BeginAttrs() {
1629   CHECK(!attrs_);
1630   attrs_ = std::make_optional<Attrs>();
1631   return true;
1632 }
1633 Attrs AttrsVisitor::GetAttrs() {
1634   CHECK(attrs_);
1635   return *attrs_;
1636 }
1637 Attrs AttrsVisitor::EndAttrs() {
1638   Attrs result{GetAttrs()};
1639   attrs_.reset();
1640   passName_ = std::nullopt;
1641   bindName_.reset();
1642   return result;
1643 }
1644 
1645 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1646   if (!passName_) {
1647     return false;
1648   }
1649   common::visit(common::visitors{
1650                     [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1651                     [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1652                     [](auto &) { common::die("unexpected pass name"); },
1653                 },
1654       symbol.details());
1655   return true;
1656 }
1657 
1658 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1659   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1660     return;
1661   }
1662   std::optional<std::string> label{
1663       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1664   // 18.9.2(2): discard leading and trailing blanks, ignore if all blank
1665   if (label) {
1666     auto first{label->find_first_not_of(" ")};
1667     if (first == std::string::npos) {
1668       // Empty NAME= means no binding at all (18.10.2p2)
1669       Say(currStmtSource().value(), "Blank binding label ignored"_warn_en_US);
1670       return;
1671     }
1672     auto last{label->find_last_not_of(" ")};
1673     label = label->substr(first, last - first + 1);
1674   } else {
1675     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1676   }
1677   // Check if a symbol has two Bind names.
1678   std::string oldBindName;
1679   if (symbol.GetBindName()) {
1680     oldBindName = *symbol.GetBindName();
1681   }
1682   symbol.SetBindName(std::move(*label));
1683   if (!oldBindName.empty()) {
1684     if (const std::string * newBindName{symbol.GetBindName()}) {
1685       if (oldBindName.compare(*newBindName) != 0) {
1686         Say(symbol.name(), "The entity '%s' has multiple BIND names"_err_en_US);
1687       }
1688     }
1689   }
1690 }
1691 
1692 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1693   CHECK(attrs_);
1694   if (CheckAndSet(Attr::BIND_C)) {
1695     if (x.v) {
1696       bindName_ = EvaluateExpr(*x.v);
1697     }
1698   }
1699 }
1700 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1701   CHECK(attrs_);
1702   CheckAndSet(IntentSpecToAttr(x));
1703   return false;
1704 }
1705 bool AttrsVisitor::Pre(const parser::Pass &x) {
1706   if (CheckAndSet(Attr::PASS)) {
1707     if (x.v) {
1708       passName_ = x.v->source;
1709       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1710     }
1711   }
1712   return false;
1713 }
1714 
1715 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1716 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1717   if (attrs_->test(attrName)) {
1718     Say(currStmtSource().value(),
1719         "Attribute '%s' cannot be used more than once"_warn_en_US,
1720         AttrToString(attrName));
1721     return true;
1722   }
1723   return false;
1724 }
1725 
1726 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1727 // name attributes that cannot be used on the same declaration
1728 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1729   if ((attrName == attr1 && attrs_->test(attr2)) ||
1730       (attrName == attr2 && attrs_->test(attr1))) {
1731     Say(currStmtSource().value(),
1732         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1733         AttrToString(attr1), AttrToString(attr2));
1734     return true;
1735   }
1736   return false;
1737 }
1738 // C759, C1543
1739 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1740   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1741       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1742       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1743       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1744       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1745       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1746       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1747 }
1748 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1749   CHECK(attrs_);
1750   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1751     return false;
1752   }
1753   attrs_->set(attrName);
1754   return true;
1755 }
1756 
1757 // DeclTypeSpecVisitor implementation
1758 
1759 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1760   return state_.declTypeSpec;
1761 }
1762 
1763 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1764   CHECK(!state_.expectDeclTypeSpec);
1765   CHECK(!state_.declTypeSpec);
1766   state_.expectDeclTypeSpec = true;
1767 }
1768 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1769   CHECK(state_.expectDeclTypeSpec);
1770   state_ = {};
1771 }
1772 
1773 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1774     DeclTypeSpec::Category category) {
1775   CHECK(state_.expectDeclTypeSpec);
1776   state_.derived.category = category;
1777 }
1778 
1779 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1780   BeginDeclTypeSpec();
1781   return true;
1782 }
1783 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1784   EndDeclTypeSpec();
1785 }
1786 
1787 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1788   // Record the resolved DeclTypeSpec in the parse tree for use by
1789   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1790   // The grammar ensures that it's an intrinsic or derived type spec,
1791   // not TYPE(*) or CLASS(*) or CLASS(T).
1792   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1793     switch (spec->category()) {
1794     case DeclTypeSpec::Numeric:
1795     case DeclTypeSpec::Logical:
1796     case DeclTypeSpec::Character:
1797       typeSpec.declTypeSpec = spec;
1798       break;
1799     case DeclTypeSpec::TypeDerived:
1800       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1801         CheckForAbstractType(derived->typeSymbol()); // C703
1802         typeSpec.declTypeSpec = spec;
1803       }
1804       break;
1805     default:
1806       CRASH_NO_CASE;
1807     }
1808   }
1809 }
1810 
1811 void DeclTypeSpecVisitor::Post(
1812     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1813   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1814 }
1815 void DeclTypeSpecVisitor::Post(
1816     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1817   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1818 }
1819 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1820   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1821 }
1822 
1823 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1824   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1825     Say("ABSTRACT derived type may not be used here"_err_en_US);
1826   }
1827 }
1828 
1829 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1830   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1831 }
1832 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1833   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1834 }
1835 
1836 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1837 // and save it in state_.declTypeSpec.
1838 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1839   CHECK(state_.expectDeclTypeSpec);
1840   CHECK(!state_.declTypeSpec);
1841   state_.declTypeSpec = &declTypeSpec;
1842 }
1843 
1844 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1845     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1846   return AnalyzeKindSelector(context(), category, kind);
1847 }
1848 
1849 // MessageHandler implementation
1850 
1851 Message &MessageHandler::Say(MessageFixedText &&msg) {
1852   return context_->Say(currStmtSource().value(), std::move(msg));
1853 }
1854 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1855   return context_->Say(currStmtSource().value(), std::move(msg));
1856 }
1857 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1858   return Say(name, std::move(msg), name);
1859 }
1860 
1861 // ImplicitRulesVisitor implementation
1862 
1863 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1864   prevParameterStmt_ = currStmtSource();
1865 }
1866 
1867 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1868   bool result{
1869       common::visit(common::visitors{
1870                         [&](const std::list<ImplicitNoneNameSpec> &y) {
1871                           return HandleImplicitNone(y);
1872                         },
1873                         [&](const std::list<parser::ImplicitSpec> &) {
1874                           if (prevImplicitNoneType_) {
1875                             Say("IMPLICIT statement after IMPLICIT NONE or "
1876                                 "IMPLICIT NONE(TYPE) statement"_err_en_US);
1877                             return false;
1878                           }
1879                           implicitRules_->set_isImplicitNoneType(false);
1880                           return true;
1881                         },
1882                     },
1883           x.u)};
1884   prevImplicit_ = currStmtSource();
1885   return result;
1886 }
1887 
1888 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1889   auto loLoc{std::get<parser::Location>(x.t)};
1890   auto hiLoc{loLoc};
1891   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1892     hiLoc = *hiLocOpt;
1893     if (*hiLoc < *loLoc) {
1894       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1895           std::string(hiLoc, 1), std::string(loLoc, 1));
1896       return false;
1897     }
1898   }
1899   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1900   return false;
1901 }
1902 
1903 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1904   BeginDeclTypeSpec();
1905   set_allowForwardReferenceToDerivedType(true);
1906   return true;
1907 }
1908 
1909 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1910   EndDeclTypeSpec();
1911 }
1912 
1913 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1914   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1915   prevImplicit_ = std::nullopt;
1916   prevImplicitNone_ = std::nullopt;
1917   prevImplicitNoneType_ = std::nullopt;
1918   prevParameterStmt_ = std::nullopt;
1919 }
1920 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1921   // find or create implicit rules for this scope
1922   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1923   SetScope(scope);
1924 }
1925 
1926 // TODO: for all of these errors, reference previous statement too
1927 bool ImplicitRulesVisitor::HandleImplicitNone(
1928     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1929   if (prevImplicitNone_) {
1930     Say("More than one IMPLICIT NONE statement"_err_en_US);
1931     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1932     return false;
1933   }
1934   if (prevParameterStmt_) {
1935     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1936     return false;
1937   }
1938   prevImplicitNone_ = currStmtSource();
1939   bool implicitNoneTypeNever{
1940       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1941   if (nameSpecs.empty()) {
1942     if (!implicitNoneTypeNever) {
1943       prevImplicitNoneType_ = currStmtSource();
1944       implicitRules_->set_isImplicitNoneType(true);
1945       if (prevImplicit_) {
1946         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1947         return false;
1948       }
1949     }
1950   } else {
1951     int sawType{0};
1952     int sawExternal{0};
1953     for (const auto noneSpec : nameSpecs) {
1954       switch (noneSpec) {
1955       case ImplicitNoneNameSpec::External:
1956         implicitRules_->set_isImplicitNoneExternal(true);
1957         ++sawExternal;
1958         break;
1959       case ImplicitNoneNameSpec::Type:
1960         if (!implicitNoneTypeNever) {
1961           prevImplicitNoneType_ = currStmtSource();
1962           implicitRules_->set_isImplicitNoneType(true);
1963           if (prevImplicit_) {
1964             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1965             return false;
1966           }
1967           ++sawType;
1968         }
1969         break;
1970       }
1971     }
1972     if (sawType > 1) {
1973       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1974       return false;
1975     }
1976     if (sawExternal > 1) {
1977       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1978       return false;
1979     }
1980   }
1981   return true;
1982 }
1983 
1984 // ArraySpecVisitor implementation
1985 
1986 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1987   CHECK(arraySpec_.empty());
1988   arraySpec_ = AnalyzeArraySpec(context(), x);
1989 }
1990 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1991   CHECK(arraySpec_.empty());
1992   arraySpec_ = AnalyzeArraySpec(context(), x);
1993 }
1994 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1995   CHECK(coarraySpec_.empty());
1996   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1997 }
1998 
1999 const ArraySpec &ArraySpecVisitor::arraySpec() {
2000   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
2001 }
2002 const ArraySpec &ArraySpecVisitor::coarraySpec() {
2003   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
2004 }
2005 void ArraySpecVisitor::BeginArraySpec() {
2006   CHECK(arraySpec_.empty());
2007   CHECK(coarraySpec_.empty());
2008   CHECK(attrArraySpec_.empty());
2009   CHECK(attrCoarraySpec_.empty());
2010 }
2011 void ArraySpecVisitor::EndArraySpec() {
2012   CHECK(arraySpec_.empty());
2013   CHECK(coarraySpec_.empty());
2014   attrArraySpec_.clear();
2015   attrCoarraySpec_.clear();
2016 }
2017 void ArraySpecVisitor::PostAttrSpec() {
2018   // Save dimension/codimension from attrs so we can process array/coarray-spec
2019   // on the entity-decl
2020   if (!arraySpec_.empty()) {
2021     if (attrArraySpec_.empty()) {
2022       attrArraySpec_ = arraySpec_;
2023       arraySpec_.clear();
2024     } else {
2025       Say(currStmtSource().value(),
2026           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
2027     }
2028   }
2029   if (!coarraySpec_.empty()) {
2030     if (attrCoarraySpec_.empty()) {
2031       attrCoarraySpec_ = coarraySpec_;
2032       coarraySpec_.clear();
2033     } else {
2034       Say(currStmtSource().value(),
2035           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
2036     }
2037   }
2038 }
2039 
2040 // FuncResultStack implementation
2041 
2042 FuncResultStack::~FuncResultStack() { CHECK(stack_.empty()); }
2043 
2044 void FuncResultStack::CompleteFunctionResultType() {
2045   // If the function has a type in the prefix, process it now.
2046   FuncInfo *info{Top()};
2047   if (info && &info->scope == &scopeHandler_.currScope()) {
2048     if (info->parsedType) {
2049       scopeHandler_.messageHandler().set_currStmtSource(info->source);
2050       if (const auto *type{
2051               scopeHandler_.ProcessTypeSpec(*info->parsedType, true)}) {
2052         if (!scopeHandler_.context().HasError(info->resultSymbol)) {
2053           info->resultSymbol->SetType(*type);
2054         }
2055       }
2056       info->parsedType = nullptr;
2057     }
2058   }
2059 }
2060 
2061 // Called from ConvertTo{Object/Proc}Entity to cope with any appearance
2062 // of the function result in a specification expression.
2063 void FuncResultStack::CompleteTypeIfFunctionResult(Symbol &symbol) {
2064   if (FuncInfo * info{Top()}) {
2065     if (info->resultSymbol == &symbol) {
2066       CompleteFunctionResultType();
2067     }
2068   }
2069 }
2070 
2071 void FuncResultStack::Pop() {
2072   if (!stack_.empty() && &stack_.back().scope == &scopeHandler_.currScope()) {
2073     stack_.pop_back();
2074   }
2075 }
2076 
2077 // ScopeHandler implementation
2078 
2079 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
2080   SayAlreadyDeclared(name.source, prev);
2081 }
2082 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
2083   if (context().HasError(prev)) {
2084     // don't report another error about prev
2085   } else {
2086     if (const auto *details{prev.detailsIf<UseDetails>()}) {
2087       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
2088           .Attach(details->location(),
2089               "It is use-associated with '%s' in module '%s'"_en_US,
2090               details->symbol().name(), GetUsedModule(*details).name());
2091     } else {
2092       SayAlreadyDeclared(name, prev.name());
2093     }
2094     context().SetError(prev);
2095   }
2096 }
2097 void ScopeHandler::SayAlreadyDeclared(
2098     const SourceName &name1, const SourceName &name2) {
2099   if (name1.begin() < name2.begin()) {
2100     SayAlreadyDeclared(name2, name1);
2101   } else {
2102     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
2103         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
2104   }
2105 }
2106 
2107 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
2108     MessageFixedText &&msg1, Message &&msg2) {
2109   Say(name, std::move(msg1), symbol.name()).Attach(std::move(msg2));
2110   context().SetError(symbol, msg1.isFatal());
2111 }
2112 
2113 void ScopeHandler::SayWithDecl(
2114     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
2115   Say(name, std::move(msg), symbol.name())
2116       .Attach(Message{name.source,
2117           symbol.test(Symbol::Flag::Implicit)
2118               ? "Implicit declaration of '%s'"_en_US
2119               : "Declaration of '%s'"_en_US,
2120           name.source});
2121   context().SetError(symbol, msg.isFatal());
2122 }
2123 
2124 void ScopeHandler::SayLocalMustBeVariable(
2125     const parser::Name &name, Symbol &symbol) {
2126   SayWithDecl(name, symbol,
2127       "The name '%s' must be a variable to appear"
2128       " in a locality-spec"_err_en_US);
2129 }
2130 
2131 void ScopeHandler::SayDerivedType(
2132     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2133   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2134   Say(name, std::move(msg), name, typeSymbol.name())
2135       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2136           typeSymbol.name());
2137 }
2138 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2139     const SourceName &name2, MessageFixedText &&msg2) {
2140   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2141 }
2142 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2143     Symbol &symbol, MessageFixedText &&msg2) {
2144   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2145   context().SetError(symbol, msg1.isFatal());
2146 }
2147 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2148     Symbol &symbol, MessageFixedText &&msg2) {
2149   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2150   context().SetError(symbol, msg1.isFatal());
2151 }
2152 
2153 // This is essentially GetProgramUnitContaining(), but it can return
2154 // a mutable Scope &, it ignores statement functions, and it fails
2155 // gracefully for error recovery (returning the original Scope).
2156 template <typename T> static T &GetInclusiveScope(T &scope) {
2157   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2158     switch (s->kind()) {
2159     case Scope::Kind::Module:
2160     case Scope::Kind::MainProgram:
2161     case Scope::Kind::Subprogram:
2162     case Scope::Kind::BlockData:
2163       if (!s->IsStmtFunction()) {
2164         return *s;
2165       }
2166       break;
2167     default:;
2168     }
2169   }
2170   return scope;
2171 }
2172 
2173 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2174 
2175 Scope *ScopeHandler::GetHostProcedure() {
2176   Scope &parent{InclusiveScope().parent()};
2177   switch (parent.kind()) {
2178   case Scope::Kind::Subprogram:
2179     return &parent;
2180   case Scope::Kind::MainProgram:
2181     return &parent;
2182   default:
2183     return nullptr;
2184   }
2185 }
2186 
2187 Scope &ScopeHandler::NonDerivedTypeScope() {
2188   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2189 }
2190 
2191 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2192   PushScope(currScope().MakeScope(kind, symbol));
2193 }
2194 void ScopeHandler::PushScope(Scope &scope) {
2195   currScope_ = &scope;
2196   auto kind{currScope_->kind()};
2197   if (kind != Scope::Kind::Block) {
2198     BeginScope(scope);
2199   }
2200   // The name of a module or submodule cannot be "used" in its scope,
2201   // as we read 19.3.1(2), so we allow the name to be used as a local
2202   // identifier in the module or submodule too.  Same with programs
2203   // (14.1(3)) and BLOCK DATA.
2204   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2205       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2206     if (auto *symbol{scope.symbol()}) {
2207       // Create a dummy symbol so we can't create another one with the same
2208       // name. It might already be there if we previously pushed the scope.
2209       SourceName name{symbol->name()};
2210       if (!FindInScope(scope, name)) {
2211         auto &newSymbol{MakeSymbol(name)};
2212         if (kind == Scope::Kind::Subprogram) {
2213           // Allow for recursive references.  If this symbol is a function
2214           // without an explicit RESULT(), this new symbol will be discarded
2215           // and replaced with an object of the same name.
2216           newSymbol.set_details(HostAssocDetails{*symbol});
2217         } else {
2218           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2219         }
2220       }
2221     }
2222   }
2223 }
2224 void ScopeHandler::PopScope() {
2225   // Entities that are not yet classified as objects or procedures are now
2226   // assumed to be objects.
2227   // TODO: Statement functions
2228   for (auto &pair : currScope()) {
2229     ConvertToObjectEntity(*pair.second);
2230   }
2231   funcResultStack_.Pop();
2232   // If popping back into a global scope, pop back to the main global scope.
2233   SetScope(currScope_->parent().IsGlobal() ? context().globalScope()
2234                                            : currScope_->parent());
2235 }
2236 void ScopeHandler::SetScope(Scope &scope) {
2237   currScope_ = &scope;
2238   ImplicitRulesVisitor::SetScope(InclusiveScope());
2239 }
2240 
2241 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2242   return FindSymbol(currScope(), name);
2243 }
2244 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2245   if (scope.IsDerivedType()) {
2246     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2247       if (!symbol->has<ProcBindingDetails>() &&
2248           !symbol->test(Symbol::Flag::ParentComp)) {
2249         return Resolve(name, symbol);
2250       }
2251     }
2252     return FindSymbol(scope.parent(), name);
2253   } else {
2254     // In EQUIVALENCE statements only resolve names in the local scope, see
2255     // 19.5.1.4, paragraph 2, item (10)
2256     return Resolve(name,
2257         inEquivalenceStmt_ ? FindInScope(scope, name)
2258                            : scope.FindSymbol(name.source));
2259   }
2260 }
2261 
2262 Symbol &ScopeHandler::MakeSymbol(
2263     Scope &scope, const SourceName &name, Attrs attrs) {
2264   if (Symbol * symbol{FindInScope(scope, name)}) {
2265     symbol->attrs() |= attrs;
2266     return *symbol;
2267   } else {
2268     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2269     CHECK(pair.second); // name was not found, so must be able to add
2270     return *pair.first->second;
2271   }
2272 }
2273 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2274   return MakeSymbol(currScope(), name, attrs);
2275 }
2276 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2277   return Resolve(name, MakeSymbol(name.source, attrs));
2278 }
2279 Symbol &ScopeHandler::MakeHostAssocSymbol(
2280     const parser::Name &name, const Symbol &hostSymbol) {
2281   Symbol &symbol{*NonDerivedTypeScope()
2282                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2283                       .first->second};
2284   name.symbol = &symbol;
2285   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2286   symbol.flags() = hostSymbol.flags();
2287   return symbol;
2288 }
2289 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2290   CHECK(!FindInScope(name));
2291   return MakeSymbol(currScope(), name, symbol.attrs());
2292 }
2293 
2294 // Look for name only in scope, not in enclosing scopes.
2295 Symbol *ScopeHandler::FindInScope(
2296     const Scope &scope, const parser::Name &name) {
2297   return Resolve(name, FindInScope(scope, name.source));
2298 }
2299 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2300   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2301   for (const std::string &n : GetAllNames(context(), name)) {
2302     auto it{scope.find(SourceName{n})};
2303     if (it != scope.end()) {
2304       return &*it->second;
2305     }
2306   }
2307   return nullptr;
2308 }
2309 
2310 // Find a component or type parameter by name in a derived type or its parents.
2311 Symbol *ScopeHandler::FindInTypeOrParents(
2312     const Scope &scope, const parser::Name &name) {
2313   return Resolve(name, scope.FindComponent(name.source));
2314 }
2315 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2316   return FindInTypeOrParents(currScope(), name);
2317 }
2318 
2319 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2320   currScope().erase(name.source);
2321   name.symbol = nullptr;
2322 }
2323 
2324 static bool NeedsType(const Symbol &symbol) {
2325   return !symbol.GetType() &&
2326       common::visit(common::visitors{
2327                         [](const EntityDetails &) { return true; },
2328                         [](const ObjectEntityDetails &) { return true; },
2329                         [](const AssocEntityDetails &) { return true; },
2330                         [&](const ProcEntityDetails &p) {
2331                           return symbol.test(Symbol::Flag::Function) &&
2332                               !symbol.attrs().test(Attr::INTRINSIC) &&
2333                               !p.interface().type() && !p.interface().symbol();
2334                         },
2335                         [](const auto &) { return false; },
2336                     },
2337           symbol.details());
2338 }
2339 
2340 void ScopeHandler::ApplyImplicitRules(
2341     Symbol &symbol, bool allowForwardReference) {
2342   funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2343   if (context().HasError(symbol) || !NeedsType(symbol)) {
2344     return;
2345   }
2346   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2347     symbol.set(Symbol::Flag::Implicit);
2348     symbol.SetType(*type);
2349     return;
2350   }
2351   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2352     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2353     if (symbol.test(Symbol::Flag::Function)) {
2354       functionOrSubroutineFlag = Symbol::Flag::Function;
2355     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2356       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2357     }
2358     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2359       // type will be determined in expression semantics
2360       AcquireIntrinsicProcedureFlags(symbol);
2361       return;
2362     }
2363   }
2364   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2365     return;
2366   }
2367   if (!context().HasError(symbol)) {
2368     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2369     context().SetError(symbol);
2370   }
2371 }
2372 
2373 // Extension: Allow forward references to scalar integer dummy arguments
2374 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2375 // what would otherwise have been their implicit type is default INTEGER.
2376 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2377   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2378       symbol.Rank() != 0 ||
2379       !context().languageFeatures().IsEnabled(
2380           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2381     return false;
2382   }
2383   const DeclTypeSpec *type{
2384       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2385   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2386     return false;
2387   }
2388   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2389   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2390     return false;
2391   }
2392   if (!ConvertToObjectEntity(symbol)) {
2393     return false;
2394   }
2395   // TODO: check no INTENT(OUT)?
2396   if (context().languageFeatures().ShouldWarn(
2397           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2398     Say(symbol.name(),
2399         "Dummy argument '%s' was used without being explicitly typed"_warn_en_US,
2400         symbol.name());
2401   }
2402   symbol.set(Symbol::Flag::Implicit);
2403   symbol.SetType(*type);
2404   return true;
2405 }
2406 
2407 // Ensure that the symbol for an intrinsic procedure is marked with
2408 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2409 // appropriate.
2410 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2411   symbol.attrs().set(Attr::INTRINSIC);
2412   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2413   case evaluate::IntrinsicClass::elementalFunction:
2414   case evaluate::IntrinsicClass::elementalSubroutine:
2415     symbol.attrs().set(Attr::ELEMENTAL);
2416     symbol.attrs().set(Attr::PURE);
2417     break;
2418   case evaluate::IntrinsicClass::impureSubroutine:
2419     break;
2420   default:
2421     symbol.attrs().set(Attr::PURE);
2422   }
2423 }
2424 
2425 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2426     Symbol &symbol, bool respectImplicitNoneType) {
2427   const Scope *scope{&symbol.owner()};
2428   if (scope->IsGlobal()) {
2429     scope = &currScope();
2430   }
2431   scope = &GetInclusiveScope(*scope);
2432   const auto *type{implicitRulesMap_->at(scope).GetType(
2433       symbol.name(), respectImplicitNoneType)};
2434   if (type) {
2435     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2436       // Resolve any forward-referenced derived type; a quick no-op else.
2437       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2438       instantiatable.Instantiate(currScope());
2439     }
2440   }
2441   return type;
2442 }
2443 
2444 // Convert symbol to be a ObjectEntity or return false if it can't be.
2445 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2446   if (symbol.has<ObjectEntityDetails>()) {
2447     // nothing to do
2448   } else if (symbol.has<UnknownDetails>()) {
2449     symbol.set_details(ObjectEntityDetails{});
2450   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2451     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2452     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2453   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2454     return useDetails->symbol().has<ObjectEntityDetails>();
2455   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2456     return hostDetails->symbol().has<ObjectEntityDetails>();
2457   } else {
2458     return false;
2459   }
2460   return true;
2461 }
2462 // Convert symbol to be a ProcEntity or return false if it can't be.
2463 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2464   if (symbol.has<ProcEntityDetails>()) {
2465     // nothing to do
2466   } else if (symbol.has<UnknownDetails>()) {
2467     symbol.set_details(ProcEntityDetails{});
2468   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2469     if (IsFunctionResult(symbol) &&
2470         !(IsPointer(symbol) && symbol.attrs().test(Attr::EXTERNAL))) {
2471       // Don't turn function result into a procedure pointer unless both
2472       // POUNTER and EXTERNAL
2473       return false;
2474     }
2475     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2476     symbol.set_details(ProcEntityDetails{std::move(*details)});
2477     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2478       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2479       symbol.set(Symbol::Flag::Function);
2480     }
2481   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2482     return useDetails->symbol().has<ProcEntityDetails>();
2483   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2484     return hostDetails->symbol().has<ProcEntityDetails>();
2485   } else {
2486     return false;
2487   }
2488   return true;
2489 }
2490 
2491 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2492     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2493   KindExpr value{GetKindParamExpr(category, kind)};
2494   if (auto known{evaluate::ToInt64(value)}) {
2495     return context().MakeNumericType(category, static_cast<int>(*known));
2496   } else {
2497     return currScope_->MakeNumericType(category, std::move(value));
2498   }
2499 }
2500 
2501 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2502     const std::optional<parser::KindSelector> &kind) {
2503   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2504   if (auto known{evaluate::ToInt64(value)}) {
2505     return context().MakeLogicalType(static_cast<int>(*known));
2506   } else {
2507     return currScope_->MakeLogicalType(std::move(value));
2508   }
2509 }
2510 
2511 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2512   if (inSpecificationPart_ && name.symbol) {
2513     auto kind{currScope().kind()};
2514     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2515         kind == Scope::Kind::Block) {
2516       bool isHostAssociated{&name.symbol->owner() == &currScope()
2517               ? name.symbol->has<HostAssocDetails>()
2518               : name.symbol->owner().Contains(currScope())};
2519       if (isHostAssociated) {
2520         specPartState_.forwardRefs.insert(name.source);
2521       }
2522     }
2523   }
2524 }
2525 
2526 std::optional<SourceName> ScopeHandler::HadForwardRef(
2527     const Symbol &symbol) const {
2528   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2529   if (iter != specPartState_.forwardRefs.end()) {
2530     return *iter;
2531   }
2532   return std::nullopt;
2533 }
2534 
2535 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2536   if (!context().HasError(symbol)) {
2537     if (auto fwdRef{HadForwardRef(symbol)}) {
2538       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2539       if (outer && symbol.has<UseDetails>() &&
2540           &symbol.GetUltimate() == &outer->GetUltimate()) {
2541         // e.g. IMPORT of host's USE association
2542         return false;
2543       }
2544       Say(*fwdRef,
2545           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2546           *fwdRef)
2547           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2548       context().SetError(symbol);
2549       return true;
2550     }
2551     if (IsDummy(symbol) && isImplicitNoneType() &&
2552         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2553       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2554       // ApplyImplicitRules() due to use in a specification expression,
2555       // and no explicit type declaration appeared later.
2556       Say(symbol.name(),
2557           "No explicit type declared for dummy argument '%s'"_err_en_US);
2558       context().SetError(symbol);
2559       return true;
2560     }
2561   }
2562   return false;
2563 }
2564 
2565 void ScopeHandler::MakeExternal(Symbol &symbol) {
2566   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2567     symbol.attrs().set(Attr::EXTERNAL);
2568     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2569       Say(symbol.name(),
2570           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2571           symbol.name());
2572     }
2573   }
2574 }
2575 
2576 // ModuleVisitor implementation
2577 
2578 bool ModuleVisitor::Pre(const parser::Only &x) {
2579   common::visit(common::visitors{
2580                     [&](const Indirection<parser::GenericSpec> &generic) {
2581                       GenericSpecInfo genericSpecInfo{generic.value()};
2582                       AddUseOnly(genericSpecInfo.symbolName());
2583                       AddUse(genericSpecInfo);
2584                     },
2585                     [&](const parser::Name &name) {
2586                       AddUseOnly(name.source);
2587                       Resolve(name, AddUse(name.source, name.source).use);
2588                     },
2589                     [&](const parser::Rename &rename) { Walk(rename); },
2590                 },
2591       x.u);
2592   return false;
2593 }
2594 
2595 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2596   const auto &localName{std::get<0>(x.t)};
2597   const auto &useName{std::get<1>(x.t)};
2598   AddUseRename(useName.source);
2599   SymbolRename rename{AddUse(localName.source, useName.source)};
2600   if (rename.use) {
2601     EraseRenamedSymbol(*rename.use);
2602   }
2603   Resolve(useName, rename.use);
2604   Resolve(localName, rename.local);
2605   return false;
2606 }
2607 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2608   const parser::DefinedOpName &local{std::get<0>(x.t)};
2609   const parser::DefinedOpName &use{std::get<1>(x.t)};
2610   GenericSpecInfo localInfo{local};
2611   GenericSpecInfo useInfo{use};
2612   if (IsIntrinsicOperator(context(), local.v.source)) {
2613     Say(local.v,
2614         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2615   } else if (IsLogicalConstant(context(), local.v.source)) {
2616     Say(local.v,
2617         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2618   } else {
2619     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2620     if (rename.use) {
2621       EraseRenamedSymbol(*rename.use);
2622     }
2623     useInfo.Resolve(rename.use);
2624     localInfo.Resolve(rename.local);
2625   }
2626   return false;
2627 }
2628 
2629 // Set useModuleScope_ to the Scope of the module being used.
2630 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2631   std::optional<bool> isIntrinsic;
2632   if (x.nature) {
2633     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2634     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2635   } else if (currScope().IsModule() && currScope().symbol() &&
2636       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2637     // Intrinsic modules USE only other intrinsic modules
2638     isIntrinsic = true;
2639   }
2640   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2641   if (!useModuleScope_) {
2642     return false;
2643   }
2644   // use the name from this source file
2645   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2646   return true;
2647 }
2648 
2649 void ModuleVisitor::Post(const parser::UseStmt &x) {
2650   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2651     // Not a use-only: collect the names that were used in renames,
2652     // then add a use for each public name that was not renamed.
2653     std::set<SourceName> useNames;
2654     for (const auto &rename : *list) {
2655       common::visit(common::visitors{
2656                         [&](const parser::Rename::Names &names) {
2657                           useNames.insert(std::get<1>(names.t).source);
2658                         },
2659                         [&](const parser::Rename::Operators &ops) {
2660                           useNames.insert(std::get<1>(ops.t).v.source);
2661                         },
2662                     },
2663           rename.u);
2664     }
2665     for (const auto &[name, symbol] : *useModuleScope_) {
2666       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2667           (!symbol->attrs().test(Attr::INTRINSIC) ||
2668               symbol->has<UseDetails>()) &&
2669           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2670         SourceName location{x.moduleName.source};
2671         if (auto *localSymbol{FindInScope(name)}) {
2672           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2673         } else {
2674           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2675         }
2676       }
2677     }
2678   }
2679   useModuleScope_ = nullptr;
2680 }
2681 
2682 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2683     const SourceName &localName, const SourceName &useName) {
2684   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2685 }
2686 
2687 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2688     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2689   if (!useModuleScope_) {
2690     return {}; // error occurred finding module
2691   }
2692   if (!useSymbol) {
2693     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2694         useModuleScope_->GetName().value());
2695     return {};
2696   }
2697   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2698       !FindModuleFileContaining(currScope())) {
2699     // Privacy is not enforced in module files so that generic interfaces
2700     // can be resolved to private specific procedures in specification
2701     // expressions.
2702     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2703         useModuleScope_->GetName().value());
2704     return {};
2705   }
2706   auto &localSymbol{MakeSymbol(localName)};
2707   DoAddUse(useName, localName, localSymbol, *useSymbol);
2708   return {&localSymbol, useSymbol};
2709 }
2710 
2711 // symbol must be either a Use or a Generic formed by merging two uses.
2712 // Convert it to a UseError with this additional location.
2713 static bool ConvertToUseError(
2714     Symbol &symbol, const SourceName &location, const Scope &module) {
2715   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2716   if (!useDetails) {
2717     if (auto *genericDetails{symbol.detailsIf<GenericDetails>()}) {
2718       if (!genericDetails->uses().empty()) {
2719         useDetails = &genericDetails->uses().at(0)->get<UseDetails>();
2720       }
2721     }
2722   }
2723   if (useDetails) {
2724     symbol.set_details(
2725         UseErrorDetails{*useDetails}.add_occurrence(location, module));
2726     return true;
2727   } else {
2728     return false;
2729   }
2730 }
2731 
2732 // If a symbol has previously been USE-associated and did not appear in a USE
2733 // ONLY clause, erase it from the current scope.  This is needed when a name
2734 // appears in a USE rename clause.
2735 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2736   const SourceName &name{useSymbol.name()};
2737   if (const Symbol * symbol{FindInScope(name)}) {
2738     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2739       const Symbol &moduleSymbol{useDetails->symbol()};
2740       if (moduleSymbol.name() == name &&
2741           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2742           !IsUseOnly(name)) {
2743         EraseSymbol(*symbol);
2744       }
2745     }
2746   }
2747 }
2748 
2749 void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
2750     Symbol &localSymbol, const Symbol &useSymbol) {
2751   if (localName != useSymbol.name()) {
2752     EraseRenamedSymbol(useSymbol);
2753   }
2754   if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2755     details->add_occurrence(location, *useModuleScope_);
2756     return;
2757   }
2758 
2759   if (localSymbol.has<UnknownDetails>()) {
2760     localSymbol.set_details(UseDetails{localName, useSymbol});
2761     localSymbol.attrs() =
2762         useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2763     localSymbol.flags() = useSymbol.flags();
2764     return;
2765   }
2766 
2767   Symbol &localUltimate{localSymbol.GetUltimate()};
2768   const Symbol &useUltimate{useSymbol.GetUltimate()};
2769   if (&localUltimate == &useUltimate) {
2770     // use-associating the same symbol again -- ok
2771     return;
2772   }
2773 
2774   auto checkAmbiguousDerivedType{[this, location, localName](
2775                                      const Symbol *t1, const Symbol *t2) {
2776     if (!t1 || !t2) {
2777       return true;
2778     } else {
2779       t1 = &t1->GetUltimate();
2780       t2 = &t2->GetUltimate();
2781       if (&t1 != &t2) {
2782         Say(location,
2783             "Generic interface '%s' has ambiguous derived types from modules '%s' and '%s'"_err_en_US,
2784             localName, t1->owner().GetName().value(),
2785             t2->owner().GetName().value());
2786         return false;
2787       }
2788     }
2789   }};
2790 
2791   auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
2792   const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
2793   auto combine{false};
2794   if (localGeneric) {
2795     if (useGeneric) {
2796       if (!checkAmbiguousDerivedType(
2797               localGeneric->derivedType(), useGeneric->derivedType())) {
2798         return;
2799       }
2800       combine = true;
2801     } else if (useUltimate.has<DerivedTypeDetails>()) {
2802       if (checkAmbiguousDerivedType(
2803               &useUltimate, localGeneric->derivedType())) {
2804         combine = true;
2805       } else {
2806         return;
2807       }
2808     } else if (&useUltimate == &BypassGeneric(localUltimate)) {
2809       return; // nothing to do; used subprogram is local's specific
2810     }
2811   } else if (useGeneric) {
2812     if (localUltimate.has<DerivedTypeDetails>()) {
2813       if (checkAmbiguousDerivedType(
2814               &localUltimate, useGeneric->derivedType())) {
2815         combine = true;
2816       } else {
2817         return;
2818       }
2819     } else if (&localUltimate == &BypassGeneric(useUltimate).GetUltimate()) {
2820       // Local is the specific of the used generic; replace it.
2821       EraseSymbol(localSymbol);
2822       Symbol &newSymbol{MakeSymbol(localName,
2823           useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2824           UseDetails{localName, useUltimate})};
2825       newSymbol.flags() = useSymbol.flags();
2826       return;
2827     }
2828   }
2829   if (!combine) {
2830     if (!ConvertToUseError(localSymbol, location, *useModuleScope_)) {
2831       Say(location,
2832           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2833           localName)
2834           .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2835               localName);
2836     }
2837     return;
2838   }
2839 
2840   // Two items are being use-associated from different modules
2841   // to the same local name.  At least one of them must be a generic,
2842   // and the other one can be a generic or a derived type.
2843   // (It could also have been the specific of the generic, but those
2844   // cases are handled above without needing to make a local copy of the
2845   // generic.)
2846 
2847   if (localGeneric) {
2848     if (localSymbol.has<UseDetails>()) {
2849       // Create a local copy of a previously use-associated generic so that
2850       // it can be locally extended without corrupting the original.
2851       GenericDetails generic;
2852       generic.CopyFrom(*localGeneric);
2853       EraseSymbol(localSymbol);
2854       Symbol &newSymbol{MakeSymbol(
2855           localSymbol.name(), localSymbol.attrs(), std::move(generic))};
2856       newSymbol.flags() = localSymbol.flags();
2857       localGeneric = &newSymbol.get<GenericDetails>();
2858       localGeneric->AddUse(localSymbol);
2859     }
2860     if (useGeneric) {
2861       // Combine two use-associated generics
2862       localSymbol.attrs() =
2863           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2864       localSymbol.flags() = useSymbol.flags();
2865       AddGenericUse(*localGeneric, localName, useUltimate);
2866       localGeneric->CopyFrom(*useGeneric);
2867     } else {
2868       CHECK(useUltimate.has<DerivedTypeDetails>());
2869       localGeneric->set_derivedType(
2870           AddGenericUse(*localGeneric, localName, useUltimate));
2871     }
2872   } else {
2873     CHECK(useGeneric && localUltimate.has<DerivedTypeDetails>());
2874     CHECK(localSymbol.has<UseDetails>());
2875     // Create a local copy of the use-associated generic, then extend it
2876     // with the local derived type.
2877     GenericDetails generic;
2878     generic.CopyFrom(*useGeneric);
2879     EraseSymbol(localSymbol);
2880     Symbol &newSymbol{MakeSymbol(localName,
2881         useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2882         std::move(generic))};
2883     newSymbol.flags() = useUltimate.flags();
2884     auto &newUseGeneric{newSymbol.get<GenericDetails>()};
2885     AddGenericUse(newUseGeneric, localName, useUltimate);
2886     newUseGeneric.AddUse(localSymbol);
2887     newUseGeneric.set_derivedType(localSymbol);
2888   }
2889 }
2890 
2891 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2892   if (useModuleScope_) {
2893     const auto &name{info.symbolName()};
2894     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2895     info.Resolve(rename.use);
2896   }
2897 }
2898 
2899 // Create a UseDetails symbol for this USE and add it to generic
2900 Symbol &ModuleVisitor::AddGenericUse(
2901     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2902   Symbol &newSymbol{
2903       currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol})};
2904   generic.AddUse(newSymbol);
2905   return newSymbol;
2906 }
2907 
2908 // Enforce C1406
2909 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2910     SourceName name, bool isIntrinsic) {
2911   if (isIntrinsic) {
2912     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2913         iter != explicitNonIntrinsicUses_.end()) {
2914       Say(name,
2915           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2916           name)
2917           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2918     }
2919     explicitIntrinsicUses_.insert(name);
2920   } else {
2921     if (auto iter{explicitIntrinsicUses_.find(name)};
2922         iter != explicitIntrinsicUses_.end()) {
2923       Say(name,
2924           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2925           name)
2926           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2927     }
2928     explicitNonIntrinsicUses_.insert(name);
2929   }
2930 }
2931 
2932 bool ModuleVisitor::BeginSubmodule(
2933     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2934   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2935   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2936   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2937   if (!ancestor) {
2938     return false;
2939   }
2940   Scope *parentScope{parentName
2941           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2942           : ancestor};
2943   if (!parentScope) {
2944     return false;
2945   }
2946   PushScope(*parentScope); // submodule is hosted in parent
2947   BeginModule(name, true);
2948   if (!ancestor->AddSubmodule(name.source, currScope())) {
2949     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2950         ancestorName.source, name.source);
2951   }
2952   return true;
2953 }
2954 
2955 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2956   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2957   auto &details{symbol.get<ModuleDetails>()};
2958   PushScope(Scope::Kind::Module, &symbol);
2959   details.set_scope(&currScope());
2960   defaultAccess_ = Attr::PUBLIC;
2961   prevAccessStmt_ = std::nullopt;
2962 }
2963 
2964 // Find a module or submodule by name and return its scope.
2965 // If ancestor is present, look for a submodule of that ancestor module.
2966 // May have to read a .mod file to find it.
2967 // If an error occurs, report it and return nullptr.
2968 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2969     std::optional<bool> isIntrinsic, Scope *ancestor) {
2970   ModFileReader reader{context()};
2971   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2972   if (!scope) {
2973     return nullptr;
2974   }
2975   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2976     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2977   }
2978   Resolve(name, scope->symbol());
2979   return scope;
2980 }
2981 
2982 void ModuleVisitor::ApplyDefaultAccess() {
2983   for (auto &pair : currScope()) {
2984     Symbol &symbol = *pair.second;
2985     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2986       symbol.attrs().set(defaultAccess_);
2987     }
2988   }
2989 }
2990 
2991 // InterfaceVistor implementation
2992 
2993 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2994   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2995   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2996   return BeginAttrs();
2997 }
2998 
2999 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
3000 
3001 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
3002   genericInfo_.pop();
3003 }
3004 
3005 // Create a symbol in genericSymbol_ for this GenericSpec.
3006 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
3007   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
3008     SetGenericSymbol(*symbol);
3009   }
3010   return false;
3011 }
3012 
3013 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
3014   if (!isGeneric()) {
3015     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
3016     return false;
3017   }
3018   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
3019   const auto &names{std::get<std::list<parser::Name>>(x.t)};
3020   AddSpecificProcs(names, kind);
3021   return false;
3022 }
3023 
3024 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
3025   genericInfo_.emplace(/*isInterface*/ false);
3026   return true;
3027 }
3028 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
3029   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
3030     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
3031   }
3032   const auto &names{std::get<std::list<parser::Name>>(x.t)};
3033   AddSpecificProcs(names, ProcedureKind::Procedure);
3034   genericInfo_.pop();
3035 }
3036 
3037 bool InterfaceVisitor::inInterfaceBlock() const {
3038   return !genericInfo_.empty() && GetGenericInfo().isInterface;
3039 }
3040 bool InterfaceVisitor::isGeneric() const {
3041   return !genericInfo_.empty() && GetGenericInfo().symbol;
3042 }
3043 bool InterfaceVisitor::isAbstract() const {
3044   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
3045 }
3046 
3047 void InterfaceVisitor::AddSpecificProcs(
3048     const std::list<parser::Name> &names, ProcedureKind kind) {
3049   for (const auto &name : names) {
3050     specificProcs_.emplace(
3051         GetGenericInfo().symbol, std::make_pair(&name, kind));
3052   }
3053 }
3054 
3055 // By now we should have seen all specific procedures referenced by name in
3056 // this generic interface. Resolve those names to symbols.
3057 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
3058   auto &details{generic.get<GenericDetails>()};
3059   UnorderedSymbolSet symbolsSeen;
3060   for (const Symbol &symbol : details.specificProcs()) {
3061     symbolsSeen.insert(symbol.GetUltimate());
3062   }
3063   auto range{specificProcs_.equal_range(&generic)};
3064   for (auto it{range.first}; it != range.second; ++it) {
3065     const parser::Name *name{it->second.first};
3066     auto kind{it->second.second};
3067     const auto *symbol{FindSymbol(*name)};
3068     if (!symbol) {
3069       Say(*name, "Procedure '%s' not found"_err_en_US);
3070       continue;
3071     }
3072     const Symbol &specific{BypassGeneric(*symbol)};
3073     const Symbol &ultimate{specific.GetUltimate()};
3074     if (!ultimate.has<SubprogramDetails>() &&
3075         !ultimate.has<SubprogramNameDetails>()) {
3076       Say(*name, "'%s' is not a subprogram"_err_en_US);
3077       continue;
3078     }
3079     if (kind == ProcedureKind::ModuleProcedure) {
3080       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
3081         if (nd->kind() != SubprogramKind::Module) {
3082           Say(*name, "'%s' is not a module procedure"_err_en_US);
3083         }
3084       } else {
3085         // USE-associated procedure
3086         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
3087         CHECK(sd);
3088         if (ultimate.owner().kind() != Scope::Kind::Module ||
3089             sd->isInterface()) {
3090           Say(*name, "'%s' is not a module procedure"_err_en_US);
3091         }
3092       }
3093     }
3094     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
3095       // When a specific procedure is a USE association, that association
3096       // is saved in the generic's specifics, not its ultimate symbol,
3097       // so that module file output of interfaces can distinguish them.
3098       details.AddSpecificProc(specific, name->source);
3099     } else if (&specific == &ultimate) {
3100       Say(name->source,
3101           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
3102           name->source, MakeOpName(generic.name()));
3103     } else {
3104       Say(name->source,
3105           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
3106           ultimate.name(), ultimate.owner().GetName().value(),
3107           MakeOpName(generic.name()));
3108     }
3109   }
3110   specificProcs_.erase(range.first, range.second);
3111 }
3112 
3113 // Check that the specific procedures are all functions or all subroutines.
3114 // If there is a derived type with the same name they must be functions.
3115 // Set the corresponding flag on generic.
3116 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
3117   ResolveSpecificsInGeneric(generic);
3118   auto &details{generic.get<GenericDetails>()};
3119   if (auto *proc{details.CheckSpecific()}) {
3120     auto msg{
3121         "'%s' may not be the name of both a generic interface and a"
3122         " procedure unless it is a specific procedure of the generic"_err_en_US};
3123     if (proc->name().begin() > generic.name().begin()) {
3124       Say(proc->name(), std::move(msg));
3125     } else {
3126       Say(generic.name(), std::move(msg));
3127     }
3128   }
3129   auto &specifics{details.specificProcs()};
3130   if (specifics.empty()) {
3131     if (details.derivedType()) {
3132       generic.set(Symbol::Flag::Function);
3133     }
3134     return;
3135   }
3136   const Symbol &firstSpecific{specifics.front()};
3137   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
3138   for (const Symbol &specific : specifics) {
3139     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
3140       auto &msg{Say(generic.name(),
3141           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
3142       if (isFunction) {
3143         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
3144         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
3145       } else {
3146         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
3147         msg.Attach(specific.name(), "Function declaration"_en_US);
3148       }
3149     }
3150   }
3151   if (!isFunction && details.derivedType()) {
3152     SayDerivedType(generic.name(),
3153         "Generic interface '%s' may only contain functions due to derived type"
3154         " with same name"_err_en_US,
3155         *details.derivedType()->scope());
3156   }
3157   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
3158 }
3159 
3160 // SubprogramVisitor implementation
3161 
3162 // Return false if it is actually an assignment statement.
3163 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
3164   const auto &name{std::get<parser::Name>(x.t)};
3165   const DeclTypeSpec *resultType{nullptr};
3166   // Look up name: provides return type or tells us if it's an array
3167   if (auto *symbol{FindSymbol(name)}) {
3168     auto *details{symbol->detailsIf<EntityDetails>()};
3169     if (!details) {
3170       badStmtFuncFound_ = true;
3171       return false;
3172     }
3173     // TODO: check that attrs are compatible with stmt func
3174     resultType = details->type();
3175     symbol->details() = UnknownDetails{}; // will be replaced below
3176   }
3177   if (badStmtFuncFound_) {
3178     Say(name, "'%s' has not been declared as an array"_err_en_US);
3179     return true;
3180   }
3181   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
3182   symbol.set(Symbol::Flag::StmtFunction);
3183   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
3184   auto &details{symbol.get<SubprogramDetails>()};
3185   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
3186     ObjectEntityDetails dummyDetails{true};
3187     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
3188       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
3189         if (d->type()) {
3190           dummyDetails.set_type(*d->type());
3191         }
3192       }
3193     }
3194     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
3195     ApplyImplicitRules(dummy);
3196     details.add_dummyArg(dummy);
3197   }
3198   ObjectEntityDetails resultDetails;
3199   if (resultType) {
3200     resultDetails.set_type(*resultType);
3201   }
3202   resultDetails.set_funcResult(true);
3203   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
3204   ApplyImplicitRules(result);
3205   details.set_result(result);
3206   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
3207   Walk(parsedExpr);
3208   // The analysis of the expression that constitutes the body of the
3209   // statement function is deferred to FinishSpecificationPart() so that
3210   // all declarations and implicit typing are complete.
3211   PopScope();
3212   return true;
3213 }
3214 
3215 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3216   if (suffix.resultName) {
3217     if (IsFunction(currScope())) {
3218       if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3219         if (info->inFunctionStmt) {
3220           info->resultName = &suffix.resultName.value();
3221         } else {
3222           // will check the result name in Post(EntryStmt)
3223         }
3224       }
3225     } else {
3226       Message &msg{Say(*suffix.resultName,
3227           "RESULT(%s) may appear only in a function"_err_en_US)};
3228       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3229         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3230       }
3231     }
3232   }
3233   // LanguageBindingSpec deferred to Post(EntryStmt) or, for FunctionStmt,
3234   // all the way to EndSubprogram().
3235   return false;
3236 }
3237 
3238 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3239   // Save this to process after UseStmt and ImplicitPart
3240   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3241     FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3242     if (info.parsedType) { // C1543
3243       Say(currStmtSource().value(),
3244           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3245       return false;
3246     } else {
3247       info.parsedType = parsedType;
3248       info.source = currStmtSource();
3249       return false;
3250     }
3251   } else {
3252     return true;
3253   }
3254 }
3255 
3256 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3257   const auto &name{std::get<parser::Name>(
3258       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3259   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3260 }
3261 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &x) {
3262   const auto &stmt{std::get<parser::Statement<parser::SubroutineStmt>>(x.t)};
3263   EndSubprogram(stmt.source,
3264       &std::get<std::optional<parser::LanguageBindingSpec>>(stmt.statement.t));
3265 }
3266 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3267   const auto &name{std::get<parser::Name>(
3268       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3269   return BeginSubprogram(name, Symbol::Flag::Function);
3270 }
3271 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &x) {
3272   const auto &stmt{std::get<parser::Statement<parser::FunctionStmt>>(x.t)};
3273   const auto &maybeSuffix{
3274       std::get<std::optional<parser::Suffix>>(stmt.statement.t)};
3275   EndSubprogram(stmt.source, maybeSuffix ? &maybeSuffix->binding : nullptr);
3276 }
3277 
3278 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &stmt) {
3279   BeginAttrs();
3280   Walk(std::get<std::list<parser::PrefixSpec>>(stmt.t));
3281   Walk(std::get<parser::Name>(stmt.t));
3282   Walk(std::get<std::list<parser::DummyArg>>(stmt.t));
3283   // Don't traverse the LanguageBindingSpec now; it's deferred to EndSubprogram.
3284   const auto &name{std::get<parser::Name>(stmt.t)};
3285   auto &details{PostSubprogramStmt(name)};
3286   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3287     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3288       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3289       details.add_dummyArg(dummy);
3290     } else {
3291       details.add_alternateReturn();
3292     }
3293   }
3294   return false;
3295 }
3296 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3297   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3298   CHECK(!info.inFunctionStmt);
3299   info.inFunctionStmt = true;
3300   return BeginAttrs();
3301 }
3302 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3303 
3304 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3305   const auto &name{std::get<parser::Name>(stmt.t)};
3306   auto &details{PostSubprogramStmt(name)};
3307   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3308     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3309     details.add_dummyArg(dummy);
3310   }
3311   const parser::Name *funcResultName;
3312   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3313   CHECK(info.inFunctionStmt);
3314   info.inFunctionStmt = false;
3315   bool distinctResultName{
3316       info.resultName && info.resultName->source != name.source};
3317   if (distinctResultName) {
3318     // Note that RESULT is ignored if it has the same name as the function.
3319     // The symbol created by PushScope() is retained as a place-holder
3320     // for error detection.
3321     funcResultName = info.resultName;
3322   } else {
3323     EraseSymbol(name); // was added by PushScope()
3324     funcResultName = &name;
3325   }
3326   if (details.isFunction()) {
3327     CHECK(context().HasError(currScope().symbol()));
3328   } else {
3329     // RESULT(x) can be the same explicitly-named RESULT(x) as an ENTRY
3330     // statement.
3331     Symbol *result{nullptr};
3332     if (distinctResultName) {
3333       if (auto iter{currScope().find(funcResultName->source)};
3334           iter != currScope().end()) {
3335         Symbol &entryResult{*iter->second};
3336         if (IsFunctionResult(entryResult)) {
3337           result = &entryResult;
3338         }
3339       }
3340     }
3341     if (result) {
3342       Resolve(*funcResultName, *result);
3343     } else {
3344       // add function result to function scope
3345       EntityDetails funcResultDetails;
3346       funcResultDetails.set_funcResult(true);
3347       result = &MakeSymbol(*funcResultName, std::move(funcResultDetails));
3348     }
3349     info.resultSymbol = result;
3350     details.set_result(*result);
3351   }
3352   // C1560.
3353   if (info.resultName && !distinctResultName) {
3354     Say(info.resultName->source,
3355         "The function name should not appear in RESULT, references to '%s' "
3356         "inside the function will be considered as references to the "
3357         "result only"_warn_en_US,
3358         name.source);
3359     // RESULT name was ignored above, the only side effect from doing so will be
3360     // the inability to make recursive calls. The related parser::Name is still
3361     // resolved to the created function result symbol because every parser::Name
3362     // should be resolved to avoid internal errors.
3363     Resolve(*info.resultName, info.resultSymbol);
3364   }
3365   name.symbol = currScope().symbol(); // must not be function result symbol
3366   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3367   // has a RESULT() suffix.
3368   info.resultName = nullptr;
3369 }
3370 
3371 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3372     const parser::Name &name) {
3373   Symbol &symbol{*currScope().symbol()};
3374   symbol.attrs() |= EndAttrs();
3375   if (symbol.attrs().test(Attr::MODULE)) {
3376     symbol.attrs().set(Attr::EXTERNAL, false);
3377   }
3378   return symbol.get<SubprogramDetails>();
3379 }
3380 
3381 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3382   if (const auto &suffix{std::get<std::optional<parser::Suffix>>(stmt.t)}) {
3383     Walk(suffix->binding);
3384   }
3385   PostEntryStmt(stmt);
3386   EndAttrs();
3387 }
3388 
3389 void SubprogramVisitor::CreateEntry(
3390     const parser::EntryStmt &stmt, Symbol &subprogram) {
3391   const auto &entryName{std::get<parser::Name>(stmt.t)};
3392   Scope &outer{currScope().parent()};
3393   Symbol::Flag subpFlag{subprogram.test(Symbol::Flag::Function)
3394           ? Symbol::Flag::Function
3395           : Symbol::Flag::Subroutine};
3396   Attrs attrs;
3397   if (Symbol * extant{FindSymbol(outer, entryName)}) {
3398     if (!HandlePreviousCalls(entryName, *extant, subpFlag)) {
3399       if (outer.IsTopLevel()) {
3400         Say2(entryName,
3401             "'%s' is already defined as a global identifier"_err_en_US, *extant,
3402             "Previous definition of '%s'"_en_US);
3403       } else {
3404         SayAlreadyDeclared(entryName, *extant);
3405       }
3406       return;
3407     }
3408     attrs = extant->attrs();
3409   }
3410   const auto &suffix{std::get<std::optional<parser::Suffix>>(stmt.t)};
3411   bool badResultName{false};
3412   std::optional<SourceName> distinctResultName;
3413   if (suffix && suffix->resultName &&
3414       suffix->resultName->source != entryName.source) {
3415     distinctResultName = suffix->resultName->source;
3416     const parser::Name &resultName{*suffix->resultName};
3417     if (resultName.source == subprogram.name()) { // C1574
3418       Say2(resultName.source,
3419           "RESULT(%s) may not have the same name as the function"_err_en_US,
3420           subprogram, "Containing function"_en_US);
3421       badResultName = true;
3422     } else if (const Symbol * extant{FindSymbol(outer, resultName)}) { // C1574
3423       if (const auto *details{extant->detailsIf<SubprogramDetails>()}) {
3424         if (details->entryScope() == &currScope()) {
3425           Say2(resultName.source,
3426               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3427               extant->name(), "Conflicting ENTRY"_en_US);
3428           badResultName = true;
3429         }
3430       }
3431     }
3432   }
3433   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3434     attrs.set(Attr::PUBLIC);
3435   }
3436   Symbol *entrySymbol{FindInScope(outer, entryName.source)};
3437   if (entrySymbol) {
3438     if (auto *generic{entrySymbol->detailsIf<GenericDetails>()}) {
3439       if (auto *specific{generic->specific()}) {
3440         // Forward reference to ENTRY from a generic interface
3441         entrySymbol = specific;
3442         entrySymbol->attrs() |= attrs;
3443       }
3444     }
3445   } else {
3446     entrySymbol = &MakeSymbol(outer, entryName.source, attrs);
3447   }
3448   SubprogramDetails entryDetails;
3449   entryDetails.set_entryScope(currScope());
3450   entrySymbol->set(subpFlag);
3451   if (subpFlag == Symbol::Flag::Function) {
3452     Symbol *result{nullptr};
3453     EntityDetails resultDetails;
3454     resultDetails.set_funcResult(true);
3455     if (distinctResultName) {
3456       if (!badResultName) {
3457         // RESULT(x) can be the same explicitly-named RESULT(x) as
3458         // the enclosing function or another ENTRY.
3459         if (auto iter{currScope().find(suffix->resultName->source)};
3460             iter != currScope().end()) {
3461           result = &*iter->second;
3462         }
3463         if (!result) {
3464           result = &MakeSymbol(
3465               *distinctResultName, Attrs{}, std::move(resultDetails));
3466         }
3467         Resolve(*suffix->resultName, *result);
3468       }
3469     } else {
3470       result = &MakeSymbol(entryName.source, Attrs{}, std::move(resultDetails));
3471     }
3472     if (result) {
3473       entryDetails.set_result(*result);
3474     }
3475   }
3476   if (subpFlag == Symbol::Flag::Subroutine ||
3477       (distinctResultName && !badResultName)) {
3478     Symbol &assoc{MakeSymbol(entryName.source)};
3479     assoc.set_details(HostAssocDetails{*entrySymbol});
3480     assoc.set(Symbol::Flag::Subroutine);
3481   }
3482   Resolve(entryName, *entrySymbol);
3483   Details details{std::move(entryDetails)};
3484   entrySymbol->set_details(std::move(entryDetails));
3485 }
3486 
3487 void SubprogramVisitor::PostEntryStmt(const parser::EntryStmt &stmt) {
3488   // The entry symbol should have already been created and resolved
3489   // in CreateEntry(), called by BeginSubprogram(), with one exception (below).
3490   const auto &name{std::get<parser::Name>(stmt.t)};
3491   Scope &inclusiveScope{InclusiveScope()};
3492   if (!name.symbol) {
3493     if (inclusiveScope.kind() != Scope::Kind::Subprogram) {
3494       Say(name.source,
3495           "ENTRY '%s' may appear only in a subroutine or function"_err_en_US,
3496           name.source);
3497     } else if (FindSeparateModuleSubprogramInterface(inclusiveScope.symbol())) {
3498       Say(name.source,
3499           "ENTRY '%s' may not appear in a separate module procedure"_err_en_US,
3500           name.source);
3501     } else {
3502       // C1571 - entry is nested, so was not put into the program tree; error
3503       // is emitted from MiscChecker in semantics.cpp.
3504     }
3505     return;
3506   }
3507   Symbol &entrySymbol{*name.symbol};
3508   if (context().HasError(entrySymbol)) {
3509     return;
3510   }
3511   if (!entrySymbol.has<SubprogramDetails>()) {
3512     SayAlreadyDeclared(name, entrySymbol);
3513     return;
3514   }
3515   SubprogramDetails &entryDetails{entrySymbol.get<SubprogramDetails>()};
3516   CHECK(entryDetails.entryScope() == &inclusiveScope);
3517   entrySymbol.attrs() |= GetAttrs();
3518   SetBindNameOn(entrySymbol);
3519   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3520     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3521       Symbol *dummy{FindSymbol(*dummyName)};
3522       if (dummy) {
3523         common::visit(
3524             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3525                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3526                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3527                 [](SubprogramDetails &x) { x.set_isDummy(); },
3528                 [&](const auto &) {
3529                   Say2(dummyName->source,
3530                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3531                       dummy->name(), "Previous declaration of '%s'"_en_US);
3532                 }},
3533             dummy->details());
3534       } else {
3535         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3536         if (!inSpecificationPart_) {
3537           ApplyImplicitRules(*dummy);
3538         }
3539       }
3540       entryDetails.add_dummyArg(*dummy);
3541     } else {
3542       if (entrySymbol.test(Symbol::Flag::Function)) { // C1573
3543         Say(name,
3544             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3545         break;
3546       }
3547       entryDetails.add_alternateReturn();
3548     }
3549   }
3550 }
3551 
3552 // A subprogram declared with MODULE PROCEDURE
3553 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3554   auto *symbol{FindSymbol(name)};
3555   if (symbol && symbol->has<SubprogramNameDetails>()) {
3556     symbol = FindSymbol(currScope().parent(), name);
3557   }
3558   if (!IsSeparateModuleProcedureInterface(symbol)) {
3559     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3560     return false;
3561   }
3562   if (symbol->owner() == currScope() && symbol->scope()) {
3563     // This is a MODULE PROCEDURE whose interface appears in its host.
3564     // Convert the module procedure's interface into a subprogram.
3565     SetScope(DEREF(symbol->scope()));
3566     symbol->get<SubprogramDetails>().set_isInterface(false);
3567   } else {
3568     // Copy the interface into a new subprogram scope.
3569     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3570     PushScope(Scope::Kind::Subprogram, &newSymbol);
3571     const auto &details{symbol->get<SubprogramDetails>()};
3572     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3573     newDetails.set_moduleInterface(*symbol);
3574     for (const Symbol *dummyArg : details.dummyArgs()) {
3575       if (!dummyArg) {
3576         newDetails.add_alternateReturn();
3577       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3578         newDetails.add_dummyArg(*copy);
3579       }
3580     }
3581     if (details.isFunction()) {
3582       currScope().erase(symbol->name());
3583       newDetails.set_result(*currScope().CopySymbol(details.result()));
3584     }
3585   }
3586   return true;
3587 }
3588 
3589 // A subprogram or interface declared with SUBROUTINE or FUNCTION
3590 bool SubprogramVisitor::BeginSubprogram(const parser::Name &name,
3591     Symbol::Flag subpFlag, bool hasModulePrefix,
3592     const parser::LanguageBindingSpec *bindingSpec,
3593     const ProgramTree::EntryStmtList *entryStmts) {
3594   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3595     Say(name,
3596         "'%s' is a MODULE procedure which must be declared within a "
3597         "MODULE or SUBMODULE"_err_en_US);
3598     return false;
3599   }
3600   Symbol *moduleInterface{nullptr};
3601   if (hasModulePrefix && !inInterfaceBlock()) {
3602     moduleInterface = FindSymbol(currScope(), name);
3603     if (IsSeparateModuleProcedureInterface(moduleInterface)) {
3604       // Subprogram is MODULE FUNCTION or MODULE SUBROUTINE with an interface
3605       // previously defined in the same scope.
3606       currScope().erase(moduleInterface->name());
3607     } else {
3608       moduleInterface = nullptr;
3609     }
3610     if (!moduleInterface) {
3611       moduleInterface = FindSymbol(currScope().parent(), name);
3612       if (!IsSeparateModuleProcedureInterface(moduleInterface)) {
3613         Say(name,
3614             "'%s' was not declared a separate module procedure"_err_en_US);
3615         return false;
3616       }
3617     }
3618   }
3619   Symbol &newSymbol{PushSubprogramScope(name, subpFlag, bindingSpec)};
3620   if (moduleInterface) {
3621     newSymbol.get<SubprogramDetails>().set_moduleInterface(*moduleInterface);
3622     if (moduleInterface->attrs().test(Attr::PRIVATE)) {
3623       newSymbol.attrs().set(Attr::PRIVATE);
3624     } else if (moduleInterface->attrs().test(Attr::PUBLIC)) {
3625       newSymbol.attrs().set(Attr::PUBLIC);
3626     }
3627   }
3628   if (entryStmts) {
3629     for (const auto &ref : *entryStmts) {
3630       CreateEntry(*ref, newSymbol);
3631     }
3632   }
3633   return true;
3634 }
3635 
3636 void SubprogramVisitor::EndSubprogram(
3637     std::optional<parser::CharBlock> stmtSource,
3638     const std::optional<parser::LanguageBindingSpec> *binding) {
3639   if (binding && *binding && currScope().symbol()) {
3640     // Finally process the BIND(C,NAME=name) now that symbols in the name
3641     // expression will resolve local names.
3642     auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
3643     auto originalStmtSource{messageHandler().currStmtSource()};
3644     messageHandler().set_currStmtSource(stmtSource);
3645     BeginAttrs();
3646     Walk(**binding);
3647     SetBindNameOn(*currScope().symbol());
3648     currScope().symbol()->attrs() |= EndAttrs();
3649     messageHandler().set_currStmtSource(originalStmtSource);
3650   }
3651   PopScope();
3652 }
3653 
3654 bool SubprogramVisitor::HandlePreviousCalls(
3655     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3656   // If the extant symbol is a generic, check its homonymous specific
3657   // procedure instead if it has one.
3658   if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
3659     return generic->specific() &&
3660         HandlePreviousCalls(name, *generic->specific(), subpFlag);
3661   } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3662              !proc->isDummy() &&
3663              !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3664     // There's a symbol created for previous calls to this subprogram or
3665     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3666     // obligation to rewrite symbol pointers in the parse tree.
3667     if (!symbol.test(subpFlag)) {
3668       Say2(name,
3669           subpFlag == Symbol::Flag::Function
3670               ? "'%s' was previously called as a subroutine"_err_en_US
3671               : "'%s' was previously called as a function"_err_en_US,
3672           symbol, "Previous call of '%s'"_en_US);
3673     }
3674     EntityDetails entity;
3675     if (proc->type()) {
3676       entity.set_type(*proc->type());
3677     }
3678     symbol.details() = std::move(entity);
3679     return true;
3680   } else {
3681     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3682   }
3683 }
3684 
3685 void SubprogramVisitor::CheckExtantProc(
3686     const parser::Name &name, Symbol::Flag subpFlag) {
3687   if (auto *prev{FindSymbol(name)}) {
3688     if (IsDummy(*prev)) {
3689     } else if (auto *entity{prev->detailsIf<EntityDetails>()};
3690                IsPointer(*prev) && !entity->type()) {
3691       // POINTER attribute set before interface
3692     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3693       // Procedures in an INTERFACE block do not resolve to symbols
3694       // in scopes between the global scope and the current scope.
3695     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3696       SayAlreadyDeclared(name, *prev);
3697     }
3698   }
3699 }
3700 
3701 Symbol &SubprogramVisitor::PushSubprogramScope(const parser::Name &name,
3702     Symbol::Flag subpFlag, const parser::LanguageBindingSpec *bindingSpec) {
3703   Symbol *symbol{GetSpecificFromGeneric(name)};
3704   if (!symbol) {
3705     if (bindingSpec && currScope().IsGlobal() && bindingSpec->v) {
3706       // Create this new top-level subprogram with a binding label
3707       // in a new global scope, so that its symbol's name won't clash
3708       // with another symbol that has a distinct binding label.
3709       PushScope(Scope::Kind::Global,
3710           &MakeSymbol(context().GetTempName(currScope()), Attrs{},
3711               MiscDetails{MiscDetails::Kind::ScopeName}));
3712     }
3713     CheckExtantProc(name, subpFlag);
3714     symbol = &MakeSymbol(name, SubprogramDetails{});
3715   }
3716   symbol->ReplaceName(name.source);
3717   symbol->set(subpFlag);
3718   PushScope(Scope::Kind::Subprogram, symbol);
3719   if (subpFlag == Symbol::Flag::Function) {
3720     funcResultStack().Push(currScope());
3721   }
3722   if (inInterfaceBlock()) {
3723     auto &details{symbol->get<SubprogramDetails>()};
3724     details.set_isInterface();
3725     if (isAbstract()) {
3726       symbol->attrs().set(Attr::ABSTRACT);
3727     } else {
3728       MakeExternal(*symbol);
3729     }
3730     if (isGeneric()) {
3731       Symbol &genericSymbol{GetGenericSymbol()};
3732       if (genericSymbol.has<GenericDetails>()) {
3733         genericSymbol.get<GenericDetails>().AddSpecificProc(
3734             *symbol, name.source);
3735       } else {
3736         CHECK(context().HasError(genericSymbol));
3737       }
3738     }
3739     set_inheritFromParent(false);
3740   }
3741   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3742   return *symbol;
3743 }
3744 
3745 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3746   if (auto *prev{FindSymbol(name)}) {
3747     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3748       if (prev->test(Symbol::Flag::Subroutine) ||
3749           prev->test(Symbol::Flag::Function)) {
3750         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3751             "Previous call of '%s'"_en_US);
3752       }
3753       EraseSymbol(name);
3754     }
3755   }
3756   if (name.source.empty()) {
3757     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3758     PushScope(Scope::Kind::BlockData, nullptr);
3759   } else {
3760     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3761   }
3762 }
3763 
3764 // If name is a generic, return specific subprogram with the same name.
3765 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3766   // Search for the name but don't resolve it
3767   if (auto *symbol{currScope().FindSymbol(name.source)}) {
3768     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3769       // found generic, want subprogram
3770       auto *specific{details->specific()};
3771       if (!specific) {
3772         specific =
3773             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3774         if (details->derivedType()) {
3775           // A specific procedure with the same name as a derived type
3776           SayAlreadyDeclared(name, *details->derivedType());
3777         } else {
3778           details->set_specific(Resolve(name, *specific));
3779         }
3780       } else if (isGeneric()) {
3781         SayAlreadyDeclared(name, *specific);
3782       }
3783       if (!specific->has<SubprogramDetails>()) {
3784         specific->set_details(SubprogramDetails{});
3785       }
3786       return specific;
3787     }
3788   }
3789   return nullptr;
3790 }
3791 
3792 // DeclarationVisitor implementation
3793 
3794 bool DeclarationVisitor::BeginDecl() {
3795   BeginDeclTypeSpec();
3796   BeginArraySpec();
3797   return BeginAttrs();
3798 }
3799 void DeclarationVisitor::EndDecl() {
3800   EndDeclTypeSpec();
3801   EndArraySpec();
3802   EndAttrs();
3803 }
3804 
3805 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3806   const auto *details{
3807       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3808   if (!details) {
3809     return false;
3810   }
3811   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3812   for (const auto &[location, module] : details->occurrences()) {
3813     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3814         name.source, module->GetName().value());
3815   }
3816   context().SetError(*name.symbol);
3817   return true;
3818 }
3819 
3820 // Report error if accessibility of symbol doesn't match isPrivate.
3821 void DeclarationVisitor::CheckAccessibility(
3822     const SourceName &name, bool isPrivate, Symbol &symbol) {
3823   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3824     Say2(name,
3825         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3826         symbol, "Previous declaration of '%s'"_en_US);
3827   }
3828 }
3829 
3830 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3831   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3832     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3833       if (typeSpec->category() == DeclTypeSpec::Character) {
3834         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3835           Say("The type parameter LEN cannot be deferred without"
3836               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3837         }
3838       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3839         for (const auto &pair : derivedSpec->parameters()) {
3840           if (pair.second.isDeferred()) {
3841             Say(currStmtSource().value(),
3842                 "The value of type parameter '%s' cannot be deferred"
3843                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3844                 pair.first);
3845           }
3846         }
3847       }
3848     }
3849   }
3850   EndDecl();
3851 }
3852 
3853 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3854   DeclareObjectEntity(std::get<parser::Name>(x.t));
3855 }
3856 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3857   DeclareObjectEntity(std::get<parser::Name>(x.t));
3858 }
3859 
3860 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3861   // Defer inspection of initializers to Initialization() so that the
3862   // symbol being initialized will be available within the initialization
3863   // expression.
3864   return false;
3865 }
3866 
3867 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3868   const auto &name{std::get<parser::ObjectName>(x.t)};
3869   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3870   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3871   symbol.ReplaceName(name.source);
3872   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3873     if (ConvertToObjectEntity(symbol)) {
3874       Initialization(name, *init, false);
3875     }
3876   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3877     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3878   }
3879 }
3880 
3881 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3882   const auto &name{std::get<parser::Name>(x.t)};
3883   if (const auto &deferredShapeSpecs{
3884           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3885     CHECK(arraySpec().empty());
3886     BeginArraySpec();
3887     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3888     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3889     symbol.ReplaceName(name.source);
3890     EndArraySpec();
3891   } else {
3892     HandleAttributeStmt(Attr::POINTER, std::get<parser::Name>(x.t));
3893   }
3894 }
3895 
3896 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3897   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3898   auto &name{std::get<parser::Name>(x.t)};
3899   Symbol *symbol;
3900   if (kind == parser::BindEntity::Kind::Object) {
3901     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3902   } else {
3903     symbol = &MakeCommonBlockSymbol(name);
3904     symbol->attrs().set(Attr::BIND_C);
3905   }
3906   SetBindNameOn(*symbol);
3907   return false;
3908 }
3909 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3910   inOldStyleParameterStmt_ = true;
3911   Walk(x.v);
3912   inOldStyleParameterStmt_ = false;
3913   return false;
3914 }
3915 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3916   auto &name{std::get<parser::NamedConstant>(x.t).v};
3917   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3918   if (!ConvertToObjectEntity(symbol) ||
3919       symbol.test(Symbol::Flag::CrayPointer) ||
3920       symbol.test(Symbol::Flag::CrayPointee)) {
3921     SayWithDecl(
3922         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3923     return false;
3924   }
3925   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3926   auto &details{symbol.get<ObjectEntityDetails>()};
3927   if (inOldStyleParameterStmt_) {
3928     // non-standard extension PARAMETER statement (no parentheses)
3929     Walk(expr);
3930     auto folded{EvaluateExpr(expr)};
3931     if (details.type()) {
3932       SayWithDecl(name, symbol,
3933           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3934     } else if (folded) {
3935       auto at{expr.thing.value().source};
3936       if (evaluate::IsActuallyConstant(*folded)) {
3937         if (const auto *type{currScope().GetType(*folded)}) {
3938           if (type->IsPolymorphic()) {
3939             Say(at, "The expression must not be polymorphic"_err_en_US);
3940           } else if (auto shape{ToArraySpec(
3941                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3942             // The type of the named constant is assumed from the expression.
3943             details.set_type(*type);
3944             details.set_init(std::move(*folded));
3945             details.set_shape(std::move(*shape));
3946           } else {
3947             Say(at, "The expression must have constant shape"_err_en_US);
3948           }
3949         } else {
3950           Say(at, "The expression must have a known type"_err_en_US);
3951         }
3952       } else {
3953         Say(at, "The expression must be a constant of known type"_err_en_US);
3954       }
3955     }
3956   } else {
3957     // standard-conforming PARAMETER statement (with parentheses)
3958     ApplyImplicitRules(symbol);
3959     Walk(expr);
3960     if (auto converted{EvaluateNonPointerInitializer(
3961             symbol, expr, expr.thing.value().source)}) {
3962       details.set_init(std::move(*converted));
3963     }
3964   }
3965   return false;
3966 }
3967 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3968   const parser::Name &name{x.v};
3969   if (!FindSymbol(name)) {
3970     Say(name, "Named constant '%s' not found"_err_en_US);
3971   } else {
3972     CheckUseError(name);
3973   }
3974   return false;
3975 }
3976 
3977 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3978   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3979   Symbol *symbol{FindSymbol(name)};
3980   if (symbol && !symbol->has<UnknownDetails>()) {
3981     // Contrary to named constants appearing in a PARAMETER statement,
3982     // enumerator names should not have their type, dimension or any other
3983     // attributes defined before they are declared in the enumerator statement,
3984     // with the exception of accessibility.
3985     // This is not explicitly forbidden by the standard, but they are scalars
3986     // which type is left for the compiler to chose, so do not let users try to
3987     // tamper with that.
3988     SayAlreadyDeclared(name, *symbol);
3989     symbol = nullptr;
3990   } else {
3991     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3992     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3993     symbol->SetType(context().MakeNumericType(
3994         TypeCategory::Integer, evaluate::CInteger::kind));
3995   }
3996 
3997   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3998           enumerator.t)}) {
3999     Walk(*init); // Resolve names in expression before evaluation.
4000     if (auto value{EvaluateInt64(context(), *init)}) {
4001       // Cast all init expressions to C_INT so that they can then be
4002       // safely incremented (see 7.6 Note 2).
4003       enumerationState_.value = static_cast<int>(*value);
4004     } else {
4005       Say(name,
4006           "Enumerator value could not be computed "
4007           "from the given expression"_err_en_US);
4008       // Prevent resolution of next enumerators value
4009       enumerationState_.value = std::nullopt;
4010     }
4011   }
4012 
4013   if (symbol) {
4014     if (enumerationState_.value) {
4015       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
4016           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
4017     } else {
4018       context().SetError(*symbol);
4019     }
4020   }
4021 
4022   if (enumerationState_.value) {
4023     (*enumerationState_.value)++;
4024   }
4025   return false;
4026 }
4027 
4028 void DeclarationVisitor::Post(const parser::EnumDef &) {
4029   enumerationState_ = EnumeratorState{};
4030 }
4031 
4032 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
4033   Attr attr{AccessSpecToAttr(x)};
4034   if (!NonDerivedTypeScope().IsModule()) { // C817
4035     Say(currStmtSource().value(),
4036         "%s attribute may only appear in the specification part of a module"_err_en_US,
4037         EnumToString(attr));
4038   }
4039   CheckAndSet(attr);
4040   return false;
4041 }
4042 
4043 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
4044   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
4045 }
4046 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
4047   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
4048 }
4049 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
4050   HandleAttributeStmt(Attr::EXTERNAL, x.v);
4051   for (const auto &name : x.v) {
4052     auto *symbol{FindSymbol(name)};
4053     if (!ConvertToProcEntity(DEREF(symbol))) {
4054       SayWithDecl(
4055           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
4056     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
4057       Say(symbol->name(),
4058           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
4059           symbol->name());
4060     }
4061   }
4062   return false;
4063 }
4064 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
4065   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
4066   auto &names{std::get<std::list<parser::Name>>(x.t)};
4067   return CheckNotInBlock("INTENT") && // C1107
4068       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
4069 }
4070 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
4071   HandleAttributeStmt(Attr::INTRINSIC, x.v);
4072   for (const auto &name : x.v) {
4073     if (!IsIntrinsic(name.source, std::nullopt)) {
4074       Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
4075     }
4076     auto &symbol{DEREF(FindSymbol(name))};
4077     if (symbol.has<GenericDetails>()) {
4078       // Generic interface is extending intrinsic; ok
4079     } else if (!ConvertToProcEntity(symbol)) {
4080       SayWithDecl(
4081           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
4082     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
4083       Say(symbol.name(),
4084           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
4085           symbol.name());
4086     } else if (symbol.GetType()) {
4087       // These warnings are worded so that they should make sense in either
4088       // order.
4089       Say(symbol.name(),
4090           "Explicit type declaration ignored for intrinsic function '%s'"_warn_en_US,
4091           symbol.name())
4092           .Attach(name.source,
4093               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
4094               name.source);
4095     }
4096   }
4097   return false;
4098 }
4099 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
4100   return CheckNotInBlock("OPTIONAL") && // C1107
4101       HandleAttributeStmt(Attr::OPTIONAL, x.v);
4102 }
4103 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
4104   return HandleAttributeStmt(Attr::PROTECTED, x.v);
4105 }
4106 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
4107   return CheckNotInBlock("VALUE") && // C1107
4108       HandleAttributeStmt(Attr::VALUE, x.v);
4109 }
4110 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
4111   return HandleAttributeStmt(Attr::VOLATILE, x.v);
4112 }
4113 // Handle a statement that sets an attribute on a list of names.
4114 bool DeclarationVisitor::HandleAttributeStmt(
4115     Attr attr, const std::list<parser::Name> &names) {
4116   for (const auto &name : names) {
4117     HandleAttributeStmt(attr, name);
4118   }
4119   return false;
4120 }
4121 Symbol &DeclarationVisitor::HandleAttributeStmt(
4122     Attr attr, const parser::Name &name) {
4123   auto *symbol{FindInScope(name)};
4124   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
4125     // these can be set on a symbol that is host-assoc or use-assoc
4126     if (!symbol &&
4127         (currScope().kind() == Scope::Kind::Subprogram ||
4128             currScope().kind() == Scope::Kind::Block)) {
4129       if (auto *hostSymbol{FindSymbol(name)}) {
4130         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
4131       }
4132     }
4133   } else if (symbol && symbol->has<UseDetails>()) {
4134     Say(currStmtSource().value(),
4135         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
4136         EnumToString(attr), name.source);
4137     return *symbol;
4138   }
4139   if (!symbol) {
4140     symbol = &MakeSymbol(name, EntityDetails{});
4141   }
4142   symbol->attrs().set(attr);
4143   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
4144   return *symbol;
4145 }
4146 // C1107
4147 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
4148   if (currScope().kind() == Scope::Kind::Block) {
4149     Say(MessageFormattedText{
4150         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
4151     return false;
4152   } else {
4153     return true;
4154   }
4155 }
4156 
4157 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
4158   CHECK(objectDeclAttr_);
4159   const auto &name{std::get<parser::ObjectName>(x.t)};
4160   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
4161 }
4162 
4163 // Declare an entity not yet known to be an object or proc.
4164 Symbol &DeclarationVisitor::DeclareUnknownEntity(
4165     const parser::Name &name, Attrs attrs) {
4166   if (!arraySpec().empty() || !coarraySpec().empty()) {
4167     return DeclareObjectEntity(name, attrs);
4168   } else {
4169     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
4170     if (auto *type{GetDeclTypeSpec()}) {
4171       SetType(name, *type);
4172     }
4173     charInfo_.length.reset();
4174     SetBindNameOn(symbol);
4175     if (symbol.attrs().test(Attr::EXTERNAL)) {
4176       ConvertToProcEntity(symbol);
4177     }
4178     return symbol;
4179   }
4180 }
4181 
4182 bool DeclarationVisitor::HasCycle(
4183     const Symbol &procSymbol, const ProcInterface &interface) {
4184   SourceOrderedSymbolSet procsInCycle;
4185   procsInCycle.insert(procSymbol);
4186   const ProcInterface *thisInterface{&interface};
4187   bool haveInterface{true};
4188   while (haveInterface) {
4189     haveInterface = false;
4190     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
4191       if (procsInCycle.count(*interfaceSymbol) > 0) {
4192         for (const auto &procInCycle : procsInCycle) {
4193           Say(procInCycle->name(),
4194               "The interface for procedure '%s' is recursively "
4195               "defined"_err_en_US,
4196               procInCycle->name());
4197           context().SetError(*procInCycle);
4198         }
4199         return true;
4200       } else if (const auto *procDetails{
4201                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
4202         haveInterface = true;
4203         thisInterface = &procDetails->interface();
4204         procsInCycle.insert(*interfaceSymbol);
4205       }
4206     }
4207   }
4208   return false;
4209 }
4210 
4211 Symbol &DeclarationVisitor::DeclareProcEntity(
4212     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
4213   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
4214   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
4215     if (details->IsInterfaceSet()) {
4216       SayWithDecl(name, symbol,
4217           "The interface for procedure '%s' has already been "
4218           "declared"_err_en_US);
4219       context().SetError(symbol);
4220     } else if (HasCycle(symbol, interface)) {
4221       return symbol;
4222     } else if (interface.type()) {
4223       symbol.set(Symbol::Flag::Function);
4224     } else if (interface.symbol()) {
4225       if (interface.symbol()->test(Symbol::Flag::Function)) {
4226         symbol.set(Symbol::Flag::Function);
4227       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
4228         symbol.set(Symbol::Flag::Subroutine);
4229       }
4230     }
4231     details->set_interface(interface);
4232     SetBindNameOn(symbol);
4233     SetPassNameOn(symbol);
4234   }
4235   return symbol;
4236 }
4237 
4238 Symbol &DeclarationVisitor::DeclareObjectEntity(
4239     const parser::Name &name, Attrs attrs) {
4240   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
4241   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
4242     if (auto *type{GetDeclTypeSpec()}) {
4243       SetType(name, *type);
4244     }
4245     if (!arraySpec().empty()) {
4246       if (details->IsArray()) {
4247         if (!context().HasError(symbol)) {
4248           Say(name,
4249               "The dimensions of '%s' have already been declared"_err_en_US);
4250           context().SetError(symbol);
4251         }
4252       } else {
4253         details->set_shape(arraySpec());
4254       }
4255     }
4256     if (!coarraySpec().empty()) {
4257       if (details->IsCoarray()) {
4258         if (!context().HasError(symbol)) {
4259           Say(name,
4260               "The codimensions of '%s' have already been declared"_err_en_US);
4261           context().SetError(symbol);
4262         }
4263       } else {
4264         details->set_coshape(coarraySpec());
4265       }
4266     }
4267     SetBindNameOn(symbol);
4268   }
4269   ClearArraySpec();
4270   ClearCoarraySpec();
4271   charInfo_.length.reset();
4272   return symbol;
4273 }
4274 
4275 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
4276   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
4277 }
4278 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
4279   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
4280 }
4281 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
4282   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
4283 }
4284 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
4285   SetDeclTypeSpec(MakeLogicalType(x.kind));
4286 }
4287 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
4288   if (!charInfo_.length) {
4289     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
4290   }
4291   if (!charInfo_.kind) {
4292     charInfo_.kind =
4293         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
4294   }
4295   SetDeclTypeSpec(currScope().MakeCharacterType(
4296       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
4297   charInfo_ = {};
4298 }
4299 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
4300   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
4301   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
4302   if (intKind &&
4303       !evaluate::IsValidKindOfIntrinsicType(
4304           TypeCategory::Character, *intKind)) { // C715, C719
4305     Say(currStmtSource().value(),
4306         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
4307     charInfo_.kind = std::nullopt; // prevent further errors
4308   }
4309   if (x.length) {
4310     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
4311   }
4312 }
4313 void DeclarationVisitor::Post(const parser::CharLength &x) {
4314   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
4315     charInfo_.length = ParamValue{
4316         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
4317   } else {
4318     charInfo_.length = GetParamValue(
4319         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
4320   }
4321 }
4322 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
4323   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
4324     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
4325   }
4326 }
4327 
4328 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
4329   if (const auto *kind{std::get_if<
4330           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
4331           &x.u)}) {
4332     const parser::Name &name{kind->thing.thing.thing};
4333     if (!FindSymbol(name)) {
4334       Say(name, "Parameter '%s' not found"_err_en_US);
4335     }
4336   }
4337   return false;
4338 }
4339 
4340 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
4341   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
4342   return true;
4343 }
4344 
4345 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
4346   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
4347   if (const Symbol * derivedSymbol{derivedName.symbol}) {
4348     CheckForAbstractType(*derivedSymbol); // C706
4349   }
4350 }
4351 
4352 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4353   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4354   return true;
4355 }
4356 
4357 void DeclarationVisitor::Post(
4358     const parser::DeclarationTypeSpec::Class &parsedClass) {
4359   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4360   if (auto spec{ResolveDerivedType(typeName)};
4361       spec && !IsExtensibleType(&*spec)) { // C705
4362     SayWithDecl(typeName, *typeName.symbol,
4363         "Non-extensible derived type '%s' may not be used with CLASS"
4364         " keyword"_err_en_US);
4365   }
4366 }
4367 
4368 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4369   const auto &typeName{std::get<parser::Name>(x.t)};
4370   auto spec{ResolveDerivedType(typeName)};
4371   if (!spec) {
4372     return;
4373   }
4374   bool seenAnyName{false};
4375   for (const auto &typeParamSpec :
4376       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4377     const auto &optKeyword{
4378         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4379     std::optional<SourceName> name;
4380     if (optKeyword) {
4381       seenAnyName = true;
4382       name = optKeyword->v.source;
4383     } else if (seenAnyName) {
4384       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4385       continue;
4386     }
4387     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4388     // The expressions in a derived type specifier whose values define
4389     // non-defaulted type parameters are evaluated (folded) in the enclosing
4390     // scope.  The KIND/LEN distinction is resolved later in
4391     // DerivedTypeSpec::CookParameters().
4392     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4393     if (!param.isExplicit() || param.GetExplicit()) {
4394       spec->AddRawParamValue(optKeyword, std::move(param));
4395     }
4396   }
4397 
4398   // The DerivedTypeSpec *spec is used initially as a search key.
4399   // If it turns out to have the same name and actual parameter
4400   // value expressions as another DerivedTypeSpec in the current
4401   // scope does, then we'll use that extant spec; otherwise, when this
4402   // spec is distinct from all derived types previously instantiated
4403   // in the current scope, this spec will be moved into that collection.
4404   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4405   auto category{GetDeclTypeSpecCategory()};
4406   if (dtDetails.isForwardReferenced()) {
4407     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4408     SetDeclTypeSpec(type);
4409     return;
4410   }
4411   // Normalize parameters to produce a better search key.
4412   spec->CookParameters(GetFoldingContext());
4413   if (!spec->MightBeParameterized()) {
4414     spec->EvaluateParameters(context());
4415   }
4416   if (const DeclTypeSpec *
4417       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4418     // This derived type and parameter expressions (if any) are already present
4419     // in this scope.
4420     SetDeclTypeSpec(*extant);
4421   } else {
4422     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4423     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4424     if (derived.MightBeParameterized() &&
4425         currScope().IsParameterizedDerivedType()) {
4426       // Defer instantiation; use the derived type's definition's scope.
4427       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4428     } else if (&currScope() == spec->typeSymbol().scope()) {
4429       // Direct recursive use of a type in the definition of one of its
4430       // components: defer instantiation
4431     } else {
4432       auto restorer{
4433           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4434       derived.Instantiate(currScope());
4435     }
4436     SetDeclTypeSpec(type);
4437   }
4438   // Capture the DerivedTypeSpec in the parse tree for use in building
4439   // structure constructor expressions.
4440   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4441 }
4442 
4443 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4444   const auto &typeName{rec.v};
4445   if (auto spec{ResolveDerivedType(typeName)}) {
4446     spec->CookParameters(GetFoldingContext());
4447     spec->EvaluateParameters(context());
4448     if (const DeclTypeSpec *
4449         extant{currScope().FindInstantiatedDerivedType(
4450             *spec, DeclTypeSpec::TypeDerived)}) {
4451       SetDeclTypeSpec(*extant);
4452     } else {
4453       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4454           typeName.source);
4455     }
4456   }
4457 }
4458 
4459 // The descendents of DerivedTypeDef in the parse tree are visited directly
4460 // in this Pre() routine so that recursive use of the derived type can be
4461 // supported in the components.
4462 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4463   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4464   Walk(stmt);
4465   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4466   auto &scope{currScope()};
4467   CHECK(scope.symbol());
4468   CHECK(scope.symbol()->scope() == &scope);
4469   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4470   details.set_isForwardReferenced(false);
4471   std::set<SourceName> paramNames;
4472   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4473     details.add_paramName(paramName.source);
4474     auto *symbol{FindInScope(scope, paramName)};
4475     if (!symbol) {
4476       Say(paramName,
4477           "No definition found for type parameter '%s'"_err_en_US); // C742
4478       // No symbol for a type param.  Create one and mark it as containing an
4479       // error to improve subsequent semantic processing
4480       BeginAttrs();
4481       Symbol *typeParam{MakeTypeSymbol(
4482           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4483       context().SetError(*typeParam);
4484       EndAttrs();
4485     } else if (!symbol->has<TypeParamDetails>()) {
4486       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4487           *symbol, "Definition of '%s'"_en_US); // C741
4488     }
4489     if (!paramNames.insert(paramName.source).second) {
4490       Say(paramName,
4491           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4492     }
4493   }
4494   for (const auto &[name, symbol] : currScope()) {
4495     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4496       SayDerivedType(name,
4497           "'%s' is not a type parameter of this derived type"_err_en_US,
4498           currScope()); // C741
4499     }
4500   }
4501   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4502   const auto &componentDefs{
4503       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4504   Walk(componentDefs);
4505   if (derivedTypeInfo_.sequence) {
4506     details.set_sequence(true);
4507     if (componentDefs.empty()) { // C740
4508       Say(stmt.source,
4509           "A sequence type must have at least one component"_err_en_US);
4510     }
4511     if (!details.paramNames().empty()) { // C740
4512       Say(stmt.source,
4513           "A sequence type may not have type parameters"_err_en_US);
4514     }
4515     if (derivedTypeInfo_.extends) { // C735
4516       Say(stmt.source,
4517           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4518     }
4519   }
4520   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4521   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4522   derivedTypeInfo_ = {};
4523   PopScope();
4524   return false;
4525 }
4526 
4527 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4528   return BeginAttrs();
4529 }
4530 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4531   auto &name{std::get<parser::Name>(x.t)};
4532   // Resolve the EXTENDS() clause before creating the derived
4533   // type's symbol to foil attempts to recursively extend a type.
4534   auto *extendsName{derivedTypeInfo_.extends};
4535   std::optional<DerivedTypeSpec> extendsType{
4536       ResolveExtendsType(name, extendsName)};
4537   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4538   symbol.ReplaceName(name.source);
4539   derivedTypeInfo_.type = &symbol;
4540   PushScope(Scope::Kind::DerivedType, &symbol);
4541   if (extendsType) {
4542     // Declare the "parent component"; private if the type is.
4543     // Any symbol stored in the EXTENDS() clause is temporarily
4544     // hidden so that a new symbol can be created for the parent
4545     // component without producing spurious errors about already
4546     // existing.
4547     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4548     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4549     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4550       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4551       comp.attrs().set(
4552           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4553       comp.set(Symbol::Flag::ParentComp);
4554       DeclTypeSpec &type{currScope().MakeDerivedType(
4555           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4556       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4557       comp.SetType(type);
4558       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4559       details.add_component(comp);
4560     }
4561   }
4562   EndAttrs();
4563 }
4564 
4565 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4566   auto *type{GetDeclTypeSpec()};
4567   auto attr{std::get<common::TypeParamAttr>(x.t)};
4568   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4569     auto &name{std::get<parser::Name>(decl.t)};
4570     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4571       SetType(name, *type);
4572       if (auto &init{
4573               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4574         if (auto maybeExpr{EvaluateNonPointerInitializer(
4575                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4576           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4577             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4578           }
4579         }
4580       }
4581     }
4582   }
4583   EndDecl();
4584 }
4585 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4586   if (derivedTypeInfo_.extends) {
4587     Say(currStmtSource().value(),
4588         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4589   } else {
4590     derivedTypeInfo_.extends = &x.v;
4591   }
4592   return false;
4593 }
4594 
4595 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4596   if (!currScope().parent().IsModule()) {
4597     Say("PRIVATE is only allowed in a derived type that is"
4598         " in a module"_err_en_US); // C766
4599   } else if (derivedTypeInfo_.sawContains) {
4600     derivedTypeInfo_.privateBindings = true;
4601   } else if (!derivedTypeInfo_.privateComps) {
4602     derivedTypeInfo_.privateComps = true;
4603   } else {
4604     Say("PRIVATE may not appear more than once in"
4605         " derived type components"_warn_en_US); // C738
4606   }
4607   return false;
4608 }
4609 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4610   if (derivedTypeInfo_.sequence) {
4611     Say("SEQUENCE may not appear more than once in"
4612         " derived type components"_warn_en_US); // C738
4613   }
4614   derivedTypeInfo_.sequence = true;
4615   return false;
4616 }
4617 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4618   const auto &name{std::get<parser::Name>(x.t)};
4619   auto attrs{GetAttrs()};
4620   if (derivedTypeInfo_.privateComps &&
4621       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4622     attrs.set(Attr::PRIVATE);
4623   }
4624   if (const auto *declType{GetDeclTypeSpec()}) {
4625     if (const auto *derived{declType->AsDerived()}) {
4626       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4627         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4628           Say("Recursive use of the derived type requires "
4629               "POINTER or ALLOCATABLE"_err_en_US);
4630         }
4631       }
4632       // TODO: This would be more appropriate in CheckDerivedType()
4633       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4634         std::string ultimateName{it.BuildResultDesignatorName()};
4635         // Strip off the leading "%"
4636         if (ultimateName.length() > 1) {
4637           ultimateName.erase(0, 1);
4638           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4639             evaluate::AttachDeclaration(
4640                 Say(name.source,
4641                     "A component with a POINTER or ALLOCATABLE attribute may "
4642                     "not "
4643                     "be of a type with a coarray ultimate component (named "
4644                     "'%s')"_err_en_US,
4645                     ultimateName),
4646                 derived->typeSymbol());
4647           }
4648           if (!arraySpec().empty() || !coarraySpec().empty()) {
4649             evaluate::AttachDeclaration(
4650                 Say(name.source,
4651                     "An array or coarray component may not be of a type with a "
4652                     "coarray ultimate component (named '%s')"_err_en_US,
4653                     ultimateName),
4654                 derived->typeSymbol());
4655           }
4656         }
4657       }
4658     }
4659   }
4660   if (OkToAddComponent(name)) {
4661     auto &symbol{DeclareObjectEntity(name, attrs)};
4662     if (symbol.has<ObjectEntityDetails>()) {
4663       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4664         Initialization(name, *init, true);
4665       }
4666     }
4667     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4668   }
4669   ClearArraySpec();
4670   ClearCoarraySpec();
4671 }
4672 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4673   // Replace "%FILL" with a distinct generated name
4674   const auto &name{std::get<parser::Name>(x.t)};
4675   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4676   if (OkToAddComponent(name)) {
4677     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4678     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4679   }
4680   ClearArraySpec();
4681 }
4682 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4683   CHECK(!interfaceName_);
4684   return BeginDecl();
4685 }
4686 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4687   interfaceName_ = nullptr;
4688   EndDecl();
4689 }
4690 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4691   // Overrides parse tree traversal so as to handle attributes first,
4692   // so POINTER & ALLOCATABLE enable forward references to derived types.
4693   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4694   set_allowForwardReferenceToDerivedType(
4695       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4696   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4697   set_allowForwardReferenceToDerivedType(false);
4698   if (derivedTypeInfo_.sequence) { // C740
4699     if (const auto *declType{GetDeclTypeSpec()}) {
4700       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4701         if (GetAttrs().test(Attr::POINTER) &&
4702             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4703           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4704             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_port_en_US);
4705           }
4706         } else {
4707           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4708         }
4709       }
4710     }
4711   }
4712   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4713   return false;
4714 }
4715 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4716   CHECK(!interfaceName_);
4717   return true;
4718 }
4719 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4720   interfaceName_ = nullptr;
4721 }
4722 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4723   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4724     return !NameIsKnownOrIntrinsic(*name);
4725   }
4726   return true;
4727 }
4728 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4729   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4730     interfaceName_ = name;
4731     NoteInterfaceName(*name);
4732   }
4733 }
4734 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4735   const auto &name{std::get<parser::Name>(x.t)};
4736   ProcInterface interface;
4737   if (interfaceName_) {
4738     interface.set_symbol(*interfaceName_->symbol);
4739   } else if (auto *type{GetDeclTypeSpec()}) {
4740     interface.set_type(*type);
4741   }
4742   auto attrs{HandleSaveName(name.source, GetAttrs())};
4743   DerivedTypeDetails *dtDetails{nullptr};
4744   if (Symbol * symbol{currScope().symbol()}) {
4745     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4746   }
4747   if (!dtDetails) {
4748     attrs.set(Attr::EXTERNAL);
4749   }
4750   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4751   symbol.ReplaceName(name.source);
4752   if (dtDetails) {
4753     dtDetails->add_component(symbol);
4754   }
4755 }
4756 
4757 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4758   derivedTypeInfo_.sawContains = true;
4759   return true;
4760 }
4761 
4762 // Resolve binding names from type-bound generics, saved in genericBindings_.
4763 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4764   // track specifics seen for the current generic to detect duplicates:
4765   const Symbol *currGeneric{nullptr};
4766   std::set<SourceName> specifics;
4767   for (const auto &[generic, bindingName] : genericBindings_) {
4768     if (generic != currGeneric) {
4769       currGeneric = generic;
4770       specifics.clear();
4771     }
4772     auto [it, inserted]{specifics.insert(bindingName->source)};
4773     if (!inserted) {
4774       Say(*bindingName, // C773
4775           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4776           bindingName->source, generic->name())
4777           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4778       continue;
4779     }
4780     auto *symbol{FindInTypeOrParents(*bindingName)};
4781     if (!symbol) {
4782       Say(*bindingName, // C772
4783           "Binding name '%s' not found in this derived type"_err_en_US);
4784     } else if (!symbol->has<ProcBindingDetails>()) {
4785       SayWithDecl(*bindingName, *symbol, // C772
4786           "'%s' is not the name of a specific binding of this type"_err_en_US);
4787     } else {
4788       generic->get<GenericDetails>().AddSpecificProc(
4789           *symbol, bindingName->source);
4790     }
4791   }
4792   genericBindings_.clear();
4793 }
4794 
4795 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4796   if (derivedTypeInfo_.sequence) {
4797     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4798   }
4799 }
4800 
4801 void DeclarationVisitor::Post(
4802     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4803   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4804     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4805   }
4806   for (auto &declaration : x.declarations) {
4807     auto &bindingName{std::get<parser::Name>(declaration.t)};
4808     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4809     const parser::Name &procedureName{optName ? *optName : bindingName};
4810     Symbol *procedure{FindSymbol(procedureName)};
4811     if (!procedure) {
4812       procedure = NoteInterfaceName(procedureName);
4813     }
4814     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4815       SetPassNameOn(*s);
4816       if (GetAttrs().test(Attr::DEFERRED)) {
4817         context().SetError(*s);
4818       }
4819     }
4820   }
4821 }
4822 
4823 void DeclarationVisitor::CheckBindings(
4824     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4825   CHECK(currScope().IsDerivedType());
4826   for (auto &declaration : tbps.declarations) {
4827     auto &bindingName{std::get<parser::Name>(declaration.t)};
4828     if (Symbol * binding{FindInScope(bindingName)}) {
4829       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4830         const Symbol *procedure{FindSubprogram(details->symbol())};
4831         if (!CanBeTypeBoundProc(procedure)) {
4832           if (details->symbol().name() != binding->name()) {
4833             Say(binding->name(),
4834                 "The binding of '%s' ('%s') must be either an accessible "
4835                 "module procedure or an external procedure with "
4836                 "an explicit interface"_err_en_US,
4837                 binding->name(), details->symbol().name());
4838           } else {
4839             Say(binding->name(),
4840                 "'%s' must be either an accessible module procedure "
4841                 "or an external procedure with an explicit interface"_err_en_US,
4842                 binding->name());
4843           }
4844           context().SetError(*binding);
4845         }
4846       }
4847     }
4848   }
4849 }
4850 
4851 void DeclarationVisitor::Post(
4852     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4853   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4854     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4855   }
4856   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4857     for (auto &bindingName : x.bindingNames) {
4858       if (auto *s{
4859               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4860         SetPassNameOn(*s);
4861         if (!GetAttrs().test(Attr::DEFERRED)) {
4862           context().SetError(*s);
4863         }
4864       }
4865     }
4866   }
4867 }
4868 
4869 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4870   if (currScope().IsDerivedType() && currScope().symbol()) {
4871     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4872       for (const auto &subrName : x.v) {
4873         if (const auto *name{ResolveName(subrName)}) {
4874           auto pair{
4875               details->finals().emplace(name->source, DEREF(name->symbol))};
4876           if (!pair.second) { // C787
4877             Say(name->source,
4878                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4879                 name->source)
4880                 .Attach(pair.first->first,
4881                     "earlier appearance of this FINAL subroutine"_en_US);
4882           }
4883         }
4884       }
4885     }
4886   }
4887 }
4888 
4889 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4890   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4891   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4892   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4893   auto info{GenericSpecInfo{genericSpec.value()}};
4894   SourceName symbolName{info.symbolName()};
4895   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4896                             : derivedTypeInfo_.privateBindings};
4897   auto *genericSymbol{FindInScope(symbolName)};
4898   if (genericSymbol) {
4899     if (!genericSymbol->has<GenericDetails>()) {
4900       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4901     }
4902   } else {
4903     // look in parent types:
4904     Symbol *inheritedSymbol{nullptr};
4905     for (const auto &name : GetAllNames(context(), symbolName)) {
4906       inheritedSymbol = currScope().FindComponent(SourceName{name});
4907       if (inheritedSymbol) {
4908         break;
4909       }
4910     }
4911     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4912       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4913     }
4914   }
4915   if (genericSymbol) {
4916     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4917   } else {
4918     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4919     if (!genericSymbol) {
4920       return false;
4921     }
4922     if (isPrivate) {
4923       genericSymbol->attrs().set(Attr::PRIVATE);
4924     }
4925   }
4926   for (const parser::Name &bindingName : bindingNames) {
4927     genericBindings_.emplace(genericSymbol, &bindingName);
4928   }
4929   info.Resolve(genericSymbol);
4930   return false;
4931 }
4932 
4933 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4934 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4935   const auto &structureStatement{
4936       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4937   auto saveDerivedTypeInfo{derivedTypeInfo_};
4938   derivedTypeInfo_ = {};
4939   derivedTypeInfo_.isStructure = true;
4940   derivedTypeInfo_.sequence = true;
4941   Scope *previousStructure{nullptr};
4942   if (saveDerivedTypeInfo.isStructure) {
4943     previousStructure = &currScope();
4944     PopScope();
4945   }
4946   const parser::StructureStmt &structStmt{structureStatement.statement};
4947   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4948   if (!name) {
4949     // Construct a distinct generated name for an anonymous structure
4950     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4951     mutableName.emplace(
4952         parser::Name{context().GetTempName(currScope()), nullptr});
4953   }
4954   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4955   symbol.ReplaceName(name->source);
4956   symbol.get<DerivedTypeDetails>().set_sequence(true);
4957   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4958   derivedTypeInfo_.type = &symbol;
4959   PushScope(Scope::Kind::DerivedType, &symbol);
4960   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4961   Walk(fields);
4962   PopScope();
4963   // Complete the definition
4964   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4965   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4966   derivedTypeSpec.CookParameters(GetFoldingContext());
4967   derivedTypeSpec.EvaluateParameters(context());
4968   DeclTypeSpec &type{currScope().MakeDerivedType(
4969       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4970   type.derivedTypeSpec().Instantiate(currScope());
4971   // Restore previous structure definition context, if any
4972   derivedTypeInfo_ = saveDerivedTypeInfo;
4973   if (previousStructure) {
4974     PushScope(*previousStructure);
4975   }
4976   // Handle any entity declarations on the STRUCTURE statement
4977   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4978   if (!decls.empty()) {
4979     BeginDecl();
4980     SetDeclTypeSpec(type);
4981     Walk(decls);
4982     EndDecl();
4983   }
4984   return false;
4985 }
4986 
4987 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
4988   Say("support for UNION"_todo_en_US); // TODO
4989   return true;
4990 }
4991 
4992 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
4993   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4994           x.u)) {
4995     BeginDecl();
4996   }
4997   return true;
4998 }
4999 
5000 void DeclarationVisitor::Post(const parser::StructureField &x) {
5001   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
5002           x.u)) {
5003     EndDecl();
5004   }
5005 }
5006 
5007 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
5008   BeginDeclTypeSpec();
5009   return true;
5010 }
5011 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
5012   EndDeclTypeSpec();
5013 }
5014 
5015 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
5016   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
5017   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
5018   if (!type) {
5019     return false;
5020   }
5021   const DerivedTypeSpec *spec{type->AsDerived()};
5022   const Scope *typeScope{spec ? spec->scope() : nullptr};
5023   if (!typeScope) {
5024     return false;
5025   }
5026 
5027   // N.B C7102 is implicitly enforced by having inaccessible types not
5028   // being found in resolution.
5029   // More constraints are enforced in expression.cpp so that they
5030   // can apply to structure constructors that have been converted
5031   // from misparsed function references.
5032   for (const auto &component :
5033       std::get<std::list<parser::ComponentSpec>>(x.t)) {
5034     // Visit the component spec expression, but not the keyword, since
5035     // we need to resolve its symbol in the scope of the derived type.
5036     Walk(std::get<parser::ComponentDataSource>(component.t));
5037     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
5038       FindInTypeOrParents(*typeScope, kw->v);
5039     }
5040   }
5041   return false;
5042 }
5043 
5044 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
5045   for (const parser::BasedPointer &bp : x.v) {
5046     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
5047     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
5048     auto *pointer{FindSymbol(pointerName)};
5049     if (!pointer) {
5050       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
5051     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
5052       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
5053     } else if (pointer->Rank() > 0) {
5054       SayWithDecl(pointerName, *pointer,
5055           "Cray pointer '%s' must be a scalar"_err_en_US);
5056     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
5057       Say(pointerName,
5058           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
5059     }
5060     pointer->set(Symbol::Flag::CrayPointer);
5061     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
5062         context().defaultKinds().subscriptIntegerKind())};
5063     const auto *type{pointer->GetType()};
5064     if (!type) {
5065       pointer->SetType(pointerType);
5066     } else if (*type != pointerType) {
5067       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
5068           pointerName.source, pointerType.AsFortran());
5069     }
5070     if (ResolveName(pointeeName)) {
5071       Symbol &pointee{*pointeeName.symbol};
5072       if (pointee.has<UseDetails>()) {
5073         Say(pointeeName,
5074             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
5075         continue;
5076       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
5077         Say(pointeeName, "'%s' is not a variable"_err_en_US);
5078         continue;
5079       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
5080         Say(pointeeName,
5081             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
5082       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
5083         Say(pointeeName,
5084             "'%s' was already declared as a Cray pointee"_err_en_US);
5085       } else {
5086         pointee.set(Symbol::Flag::CrayPointee);
5087       }
5088       if (const auto *pointeeType{pointee.GetType()}) {
5089         if (const auto *derived{pointeeType->AsDerived()}) {
5090           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
5091             Say(pointeeName,
5092                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
5093           }
5094         }
5095       }
5096       // process the pointee array-spec, if present
5097       BeginArraySpec();
5098       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
5099       const auto &spec{arraySpec()};
5100       if (!spec.empty()) {
5101         auto &details{pointee.get<ObjectEntityDetails>()};
5102         if (details.shape().empty()) {
5103           details.set_shape(spec);
5104         } else {
5105           SayWithDecl(pointeeName, pointee,
5106               "Array spec was already declared for '%s'"_err_en_US);
5107         }
5108       }
5109       ClearArraySpec();
5110       currScope().add_crayPointer(pointeeName.source, *pointer);
5111     }
5112   }
5113   return false;
5114 }
5115 
5116 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
5117   if (!CheckNotInBlock("NAMELIST")) { // C1107
5118     return false;
5119   }
5120   const auto &groupName{std::get<parser::Name>(x.t)};
5121   auto *groupSymbol{FindInScope(groupName)};
5122   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
5123     groupSymbol = &MakeSymbol(groupName, NamelistDetails{});
5124     groupSymbol->ReplaceName(groupName.source);
5125   }
5126   // Name resolution of group items is deferred to FinishNamelists()
5127   // so that host association is handled correctly.
5128   GetDeferredDeclarationState(true)->namelistGroups.emplace_back(&x);
5129   return false;
5130 }
5131 
5132 void DeclarationVisitor::FinishNamelists() {
5133   if (auto *deferred{GetDeferredDeclarationState()}) {
5134     for (const parser::NamelistStmt::Group *group : deferred->namelistGroups) {
5135       if (auto *groupSymbol{FindInScope(std::get<parser::Name>(group->t))}) {
5136         if (auto *details{groupSymbol->detailsIf<NamelistDetails>()}) {
5137           for (const auto &name : std::get<std::list<parser::Name>>(group->t)) {
5138             auto *symbol{FindSymbol(name)};
5139             if (!symbol) {
5140               symbol = &MakeSymbol(name, ObjectEntityDetails{});
5141               ApplyImplicitRules(*symbol);
5142             } else if (!ConvertToObjectEntity(*symbol)) {
5143               SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
5144             }
5145             symbol->GetUltimate().set(Symbol::Flag::InNamelist);
5146             details->add_object(*symbol);
5147           }
5148         }
5149       }
5150     }
5151     deferred->namelistGroups.clear();
5152   }
5153 }
5154 
5155 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
5156   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
5157     auto *symbol{FindSymbol(*name)};
5158     if (!symbol) {
5159       Say(*name, "Namelist group '%s' not found"_err_en_US);
5160     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
5161       SayWithDecl(
5162           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
5163     }
5164   }
5165   return true;
5166 }
5167 
5168 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
5169   CheckNotInBlock("COMMON"); // C1107
5170   return true;
5171 }
5172 
5173 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
5174   BeginArraySpec();
5175   return true;
5176 }
5177 
5178 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
5179   const auto &name{std::get<parser::Name>(x.t)};
5180   DeclareObjectEntity(name);
5181   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
5182   if (!pair.second) {
5183     const SourceName &prev{*pair.first};
5184     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
5185         "Previous occurrence of '%s' in a COMMON block"_en_US);
5186   }
5187 }
5188 
5189 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
5190   // save equivalence sets to be processed after specification part
5191   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
5192     for (const std::list<parser::EquivalenceObject> &set : x.v) {
5193       specPartState_.equivalenceSets.push_back(&set);
5194     }
5195   }
5196   return false; // don't implicitly declare names yet
5197 }
5198 
5199 void DeclarationVisitor::CheckEquivalenceSets() {
5200   EquivalenceSets equivSets{context()};
5201   inEquivalenceStmt_ = true;
5202   for (const auto *set : specPartState_.equivalenceSets) {
5203     const auto &source{set->front().v.value().source};
5204     if (set->size() <= 1) { // R871
5205       Say(source, "Equivalence set must have more than one object"_err_en_US);
5206     }
5207     for (const parser::EquivalenceObject &object : *set) {
5208       const auto &designator{object.v.value()};
5209       // The designator was not resolved when it was encountered so do it now.
5210       // AnalyzeExpr causes array sections to be changed to substrings as needed
5211       Walk(designator);
5212       if (AnalyzeExpr(context(), designator)) {
5213         equivSets.AddToSet(designator);
5214       }
5215     }
5216     equivSets.FinishSet(source);
5217   }
5218   inEquivalenceStmt_ = false;
5219   for (auto &set : equivSets.sets()) {
5220     if (!set.empty()) {
5221       currScope().add_equivalenceSet(std::move(set));
5222     }
5223   }
5224   specPartState_.equivalenceSets.clear();
5225 }
5226 
5227 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
5228   if (x.v.empty()) {
5229     specPartState_.saveInfo.saveAll = currStmtSource();
5230     currScope().set_hasSAVE();
5231   } else {
5232     for (const parser::SavedEntity &y : x.v) {
5233       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
5234       const auto &name{std::get<parser::Name>(y.t)};
5235       if (kind == parser::SavedEntity::Kind::Common) {
5236         MakeCommonBlockSymbol(name);
5237         AddSaveName(specPartState_.saveInfo.commons, name.source);
5238       } else {
5239         HandleAttributeStmt(Attr::SAVE, name);
5240       }
5241     }
5242   }
5243   return false;
5244 }
5245 
5246 void DeclarationVisitor::CheckSaveStmts() {
5247   for (const SourceName &name : specPartState_.saveInfo.entities) {
5248     auto *symbol{FindInScope(name)};
5249     if (!symbol) {
5250       // error was reported
5251     } else if (specPartState_.saveInfo.saveAll) {
5252       // C889 - note that pgi, ifort, xlf do not enforce this constraint
5253       Say2(name,
5254           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_warn_en_US,
5255           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
5256     } else if (auto msg{CheckSaveAttr(*symbol)}) {
5257       Say(name, std::move(*msg));
5258       context().SetError(*symbol);
5259     } else {
5260       SetSaveAttr(*symbol);
5261     }
5262   }
5263   for (const SourceName &name : specPartState_.saveInfo.commons) {
5264     if (auto *symbol{currScope().FindCommonBlock(name)}) {
5265       auto &objects{symbol->get<CommonBlockDetails>().objects()};
5266       if (objects.empty()) {
5267         if (currScope().kind() != Scope::Kind::Block) {
5268           Say(name,
5269               "'%s' appears as a COMMON block in a SAVE statement but not in"
5270               " a COMMON statement"_err_en_US);
5271         } else { // C1108
5272           Say(name,
5273               "SAVE statement in BLOCK construct may not contain a"
5274               " common block name '%s'"_err_en_US);
5275         }
5276       } else {
5277         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
5278           SetSaveAttr(*object);
5279         }
5280       }
5281     }
5282   }
5283   if (specPartState_.saveInfo.saveAll) {
5284     // Apply SAVE attribute to applicable symbols
5285     for (auto pair : currScope()) {
5286       auto &symbol{*pair.second};
5287       if (!CheckSaveAttr(symbol)) {
5288         SetSaveAttr(symbol);
5289       }
5290     }
5291   }
5292   specPartState_.saveInfo = {};
5293 }
5294 
5295 // If SAVE attribute can't be set on symbol, return error message.
5296 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
5297     const Symbol &symbol) {
5298   if (IsDummy(symbol)) {
5299     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
5300   } else if (symbol.IsFuncResult()) {
5301     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
5302   } else if (symbol.has<ProcEntityDetails>() &&
5303       !symbol.attrs().test(Attr::POINTER)) {
5304     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
5305   } else if (IsAutomatic(symbol)) {
5306     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
5307   } else {
5308     return std::nullopt;
5309   }
5310 }
5311 
5312 // Record SAVEd names in specPartState_.saveInfo.entities.
5313 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
5314   if (attrs.test(Attr::SAVE)) {
5315     AddSaveName(specPartState_.saveInfo.entities, name);
5316   }
5317   return attrs;
5318 }
5319 
5320 // Record a name in a set of those to be saved.
5321 void DeclarationVisitor::AddSaveName(
5322     std::set<SourceName> &set, const SourceName &name) {
5323   auto pair{set.insert(name)};
5324   if (!pair.second) {
5325     Say2(name, "SAVE attribute was already specified on '%s'"_warn_en_US,
5326         *pair.first, "Previous specification of SAVE attribute"_en_US);
5327   }
5328 }
5329 
5330 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
5331 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
5332   if (!IsSaved(symbol)) {
5333     symbol.attrs().set(Attr::SAVE);
5334   }
5335 }
5336 
5337 // Check types of common block objects, now that they are known.
5338 void DeclarationVisitor::CheckCommonBlocks() {
5339   // check for empty common blocks
5340   for (const auto &pair : currScope().commonBlocks()) {
5341     const auto &symbol{*pair.second};
5342     if (symbol.get<CommonBlockDetails>().objects().empty() &&
5343         symbol.attrs().test(Attr::BIND_C)) {
5344       Say(symbol.name(),
5345           "'%s' appears as a COMMON block in a BIND statement but not in"
5346           " a COMMON statement"_err_en_US);
5347     }
5348   }
5349   // check objects in common blocks
5350   for (const auto &name : specPartState_.commonBlockObjects) {
5351     const auto *symbol{currScope().FindSymbol(name)};
5352     if (!symbol) {
5353       continue;
5354     }
5355     const auto &attrs{symbol->attrs()};
5356     if (attrs.test(Attr::ALLOCATABLE)) {
5357       Say(name,
5358           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
5359     } else if (attrs.test(Attr::BIND_C)) {
5360       Say(name,
5361           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
5362     } else if (IsNamedConstant(*symbol)) {
5363       Say(name,
5364           "A named constant '%s' may not appear in a COMMON block"_err_en_US);
5365     } else if (IsDummy(*symbol)) {
5366       Say(name,
5367           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5368     } else if (symbol->IsFuncResult()) {
5369       Say(name,
5370           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5371     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5372       if (type->category() == DeclTypeSpec::ClassStar) {
5373         Say(name,
5374             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5375       } else if (const auto *derived{type->AsDerived()}) {
5376         auto &typeSymbol{derived->typeSymbol()};
5377         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5378             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5379           Say(name,
5380               "Derived type '%s' in COMMON block must have the BIND or"
5381               " SEQUENCE attribute"_err_en_US);
5382         }
5383         CheckCommonBlockDerivedType(name, typeSymbol);
5384       }
5385     }
5386   }
5387   specPartState_.commonBlockObjects = {};
5388 }
5389 
5390 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5391   return Resolve(name, currScope().MakeCommonBlock(name.source));
5392 }
5393 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5394     const std::optional<parser::Name> &name) {
5395   if (name) {
5396     return MakeCommonBlockSymbol(*name);
5397   } else {
5398     return MakeCommonBlockSymbol(parser::Name{});
5399   }
5400 }
5401 
5402 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5403   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5404 }
5405 
5406 // Check if this derived type can be in a COMMON block.
5407 void DeclarationVisitor::CheckCommonBlockDerivedType(
5408     const SourceName &name, const Symbol &typeSymbol) {
5409   if (const auto *scope{typeSymbol.scope()}) {
5410     for (const auto &pair : *scope) {
5411       const Symbol &component{*pair.second};
5412       if (component.attrs().test(Attr::ALLOCATABLE)) {
5413         Say2(name,
5414             "Derived type variable '%s' may not appear in a COMMON block"
5415             " due to ALLOCATABLE component"_err_en_US,
5416             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5417         return;
5418       }
5419       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5420       if (component.test(Symbol::Flag::InDataStmt) ||
5421           (details && details->init())) {
5422         Say2(name,
5423             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5424             component.name(), "Component with default initialization"_en_US);
5425         return;
5426       }
5427       if (details) {
5428         if (const auto *type{details->type()}) {
5429           if (const auto *derived{type->AsDerived()}) {
5430             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5431           }
5432         }
5433       }
5434     }
5435   }
5436 }
5437 
5438 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5439     const parser::Name &name) {
5440   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5441           name.source.ToString())}) {
5442     // Unrestricted specific intrinsic function names (e.g., "cos")
5443     // are acceptable as procedure interfaces.  The presence of the
5444     // INTRINSIC flag will cause this symbol to have a complete interface
5445     // recreated for it later on demand, but capturing its result type here
5446     // will make GetType() return a correct result without having to
5447     // probe the intrinsics table again.
5448     Symbol &symbol{
5449         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5450     CHECK(interface->functionResult.has_value());
5451     evaluate::DynamicType dyType{
5452         DEREF(interface->functionResult->GetTypeAndShape()).type()};
5453     CHECK(common::IsNumericTypeCategory(dyType.category()));
5454     const DeclTypeSpec &typeSpec{
5455         MakeNumericType(dyType.category(), dyType.kind())};
5456     ProcEntityDetails details;
5457     ProcInterface procInterface;
5458     procInterface.set_type(typeSpec);
5459     details.set_interface(procInterface);
5460     symbol.set_details(std::move(details));
5461     symbol.set(Symbol::Flag::Function);
5462     if (interface->IsElemental()) {
5463       symbol.attrs().set(Attr::ELEMENTAL);
5464     }
5465     if (interface->IsPure()) {
5466       symbol.attrs().set(Attr::PURE);
5467     }
5468     Resolve(name, symbol);
5469     return true;
5470   } else {
5471     return false;
5472   }
5473 }
5474 
5475 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5476 bool DeclarationVisitor::PassesSharedLocalityChecks(
5477     const parser::Name &name, Symbol &symbol) {
5478   if (!IsVariableName(symbol)) {
5479     SayLocalMustBeVariable(name, symbol); // C1124
5480     return false;
5481   }
5482   if (symbol.owner() == currScope()) { // C1125 and C1126
5483     SayAlreadyDeclared(name, symbol);
5484     return false;
5485   }
5486   return true;
5487 }
5488 
5489 // Checks for locality-specs LOCAL and LOCAL_INIT
5490 bool DeclarationVisitor::PassesLocalityChecks(
5491     const parser::Name &name, Symbol &symbol) {
5492   if (IsAllocatable(symbol)) { // C1128
5493     SayWithDecl(name, symbol,
5494         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5495     return false;
5496   }
5497   if (IsOptional(symbol)) { // C1128
5498     SayWithDecl(name, symbol,
5499         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5500     return false;
5501   }
5502   if (IsIntentIn(symbol)) { // C1128
5503     SayWithDecl(name, symbol,
5504         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5505     return false;
5506   }
5507   if (IsFinalizable(symbol)) { // C1128
5508     SayWithDecl(name, symbol,
5509         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5510     return false;
5511   }
5512   if (evaluate::IsCoarray(symbol)) { // C1128
5513     SayWithDecl(
5514         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5515     return false;
5516   }
5517   if (const DeclTypeSpec * type{symbol.GetType()}) {
5518     if (type->IsPolymorphic() && IsDummy(symbol) &&
5519         !IsPointer(symbol)) { // C1128
5520       SayWithDecl(name, symbol,
5521           "Nonpointer polymorphic argument '%s' not allowed in a "
5522           "locality-spec"_err_en_US);
5523       return false;
5524     }
5525   }
5526   if (IsAssumedSizeArray(symbol)) { // C1128
5527     SayWithDecl(name, symbol,
5528         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5529     return false;
5530   }
5531   if (std::optional<Message> msg{WhyNotModifiable(symbol, currScope())}) {
5532     SayWithReason(name, symbol,
5533         "'%s' may not appear in a locality-spec because it is not "
5534         "definable"_err_en_US,
5535         std::move(*msg));
5536     return false;
5537   }
5538   return PassesSharedLocalityChecks(name, symbol);
5539 }
5540 
5541 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5542     const parser::Name &name) {
5543   Symbol *prev{FindSymbol(name)};
5544   if (!prev) {
5545     // Declare the name as an object in the enclosing scope so that
5546     // the name can't be repurposed there later as something else.
5547     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5548     ConvertToObjectEntity(*prev);
5549     ApplyImplicitRules(*prev);
5550   }
5551   return *prev;
5552 }
5553 
5554 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5555   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5556   if (!PassesLocalityChecks(name, prev)) {
5557     return nullptr;
5558   }
5559   return &MakeHostAssocSymbol(name, prev);
5560 }
5561 
5562 Symbol *DeclarationVisitor::DeclareStatementEntity(
5563     const parser::DoVariable &doVar,
5564     const std::optional<parser::IntegerTypeSpec> &type) {
5565   const parser::Name &name{doVar.thing.thing};
5566   const DeclTypeSpec *declTypeSpec{nullptr};
5567   if (auto *prev{FindSymbol(name)}) {
5568     if (prev->owner() == currScope()) {
5569       SayAlreadyDeclared(name, *prev);
5570       return nullptr;
5571     }
5572     name.symbol = nullptr;
5573     declTypeSpec = prev->GetType();
5574   }
5575   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5576   if (!symbol.has<ObjectEntityDetails>()) {
5577     return nullptr; // error was reported in DeclareEntity
5578   }
5579   if (type) {
5580     declTypeSpec = ProcessTypeSpec(*type);
5581   }
5582   if (declTypeSpec) {
5583     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5584     // declaration of this implied DO loop control variable.
5585     auto restorer{
5586         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5587     SetType(name, *declTypeSpec);
5588   } else {
5589     ApplyImplicitRules(symbol);
5590   }
5591   Symbol *result{Resolve(name, &symbol)};
5592   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5593   return result;
5594 }
5595 
5596 // Set the type of an entity or report an error.
5597 void DeclarationVisitor::SetType(
5598     const parser::Name &name, const DeclTypeSpec &type) {
5599   CHECK(name.symbol);
5600   auto &symbol{*name.symbol};
5601   if (charInfo_.length) { // Declaration has "*length" (R723)
5602     auto length{std::move(*charInfo_.length)};
5603     charInfo_.length.reset();
5604     if (type.category() == DeclTypeSpec::Character) {
5605       auto kind{type.characterTypeSpec().kind()};
5606       // Recurse with correct type.
5607       SetType(name,
5608           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5609       return;
5610     } else { // C753
5611       Say(name,
5612           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5613     }
5614   }
5615   auto *prevType{symbol.GetType()};
5616   if (!prevType) {
5617     symbol.SetType(type);
5618   } else if (symbol.has<UseDetails>()) {
5619     // error recovery case, redeclaration of use-associated name
5620   } else if (HadForwardRef(symbol)) {
5621     // error recovery after use of host-associated name
5622   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5623     SayWithDecl(
5624         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5625     context().SetError(symbol);
5626   } else if (type != *prevType) {
5627     SayWithDecl(name, symbol,
5628         "The type of '%s' has already been implicitly declared"_err_en_US);
5629     context().SetError(symbol);
5630   } else {
5631     symbol.set(Symbol::Flag::Implicit, false);
5632   }
5633 }
5634 
5635 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5636     const parser::Name &name) {
5637   Scope &outer{NonDerivedTypeScope()};
5638   Symbol *symbol{FindSymbol(outer, name)};
5639   Symbol *ultimate{symbol ? &symbol->GetUltimate() : nullptr};
5640   auto *generic{ultimate ? ultimate->detailsIf<GenericDetails>() : nullptr};
5641   if (generic) {
5642     if (Symbol * genDT{generic->derivedType()}) {
5643       symbol = genDT;
5644       generic = nullptr;
5645     }
5646   }
5647   if (!symbol || symbol->has<UnknownDetails>() ||
5648       (generic && &ultimate->owner() == &outer)) {
5649     if (allowForwardReferenceToDerivedType()) {
5650       if (!symbol) {
5651         symbol = &MakeSymbol(outer, name.source, Attrs{});
5652         Resolve(name, *symbol);
5653       } else if (generic) {
5654         // forward ref to type with later homonymous generic
5655         symbol = &outer.MakeSymbol(name.source, Attrs{}, UnknownDetails{});
5656         generic->set_derivedType(*symbol);
5657         name.symbol = symbol;
5658       }
5659       DerivedTypeDetails details;
5660       details.set_isForwardReferenced(true);
5661       symbol->set_details(std::move(details));
5662     } else { // C732
5663       Say(name, "Derived type '%s' not found"_err_en_US);
5664       return std::nullopt;
5665     }
5666   }
5667   if (CheckUseError(name)) {
5668     return std::nullopt;
5669   }
5670   symbol = &symbol->GetUltimate();
5671   if (symbol->has<DerivedTypeDetails>()) {
5672     return DerivedTypeSpec{name.source, *symbol};
5673   } else {
5674     Say(name, "'%s' is not a derived type"_err_en_US);
5675     return std::nullopt;
5676   }
5677 }
5678 
5679 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5680     const parser::Name &typeName, const parser::Name *extendsName) {
5681   if (!extendsName) {
5682     return std::nullopt;
5683   } else if (typeName.source == extendsName->source) {
5684     Say(extendsName->source,
5685         "Derived type '%s' cannot extend itself"_err_en_US);
5686     return std::nullopt;
5687   } else {
5688     return ResolveDerivedType(*extendsName);
5689   }
5690 }
5691 
5692 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5693   // The symbol is checked later by CheckExplicitInterface() and
5694   // CheckBindings().  It can be a forward reference.
5695   if (!NameIsKnownOrIntrinsic(name)) {
5696     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5697     Resolve(name, symbol);
5698   }
5699   return name.symbol;
5700 }
5701 
5702 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5703   if (const Symbol * symbol{name.symbol}) {
5704     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5705       Say(name,
5706           "'%s' must be an abstract interface or a procedure with "
5707           "an explicit interface"_err_en_US,
5708           symbol->name());
5709     }
5710   }
5711 }
5712 
5713 // Create a symbol for a type parameter, component, or procedure binding in
5714 // the current derived type scope. Return false on error.
5715 Symbol *DeclarationVisitor::MakeTypeSymbol(
5716     const parser::Name &name, Details &&details) {
5717   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5718 }
5719 Symbol *DeclarationVisitor::MakeTypeSymbol(
5720     const SourceName &name, Details &&details) {
5721   Scope &derivedType{currScope()};
5722   CHECK(derivedType.IsDerivedType());
5723   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5724     Say2(name,
5725         "Type parameter, component, or procedure binding '%s'"
5726         " already defined in this type"_err_en_US,
5727         *symbol, "Previous definition of '%s'"_en_US);
5728     return nullptr;
5729   } else {
5730     auto attrs{GetAttrs()};
5731     // Apply binding-private-stmt if present and this is a procedure binding
5732     if (derivedTypeInfo_.privateBindings &&
5733         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5734         std::holds_alternative<ProcBindingDetails>(details)) {
5735       attrs.set(Attr::PRIVATE);
5736     }
5737     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5738     if (result.has<TypeParamDetails>()) {
5739       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5740     }
5741     return &result;
5742   }
5743 }
5744 
5745 // Return true if it is ok to declare this component in the current scope.
5746 // Otherwise, emit an error and return false.
5747 bool DeclarationVisitor::OkToAddComponent(
5748     const parser::Name &name, const Symbol *extends) {
5749   for (const Scope *scope{&currScope()}; scope;) {
5750     CHECK(scope->IsDerivedType());
5751     if (auto *prev{FindInScope(*scope, name)}) {
5752       if (!context().HasError(*prev)) {
5753         parser::MessageFixedText msg;
5754         if (extends) {
5755           msg = "Type cannot be extended as it has a component named"
5756                 " '%s'"_err_en_US;
5757         } else if (prev->test(Symbol::Flag::ParentComp)) {
5758           msg = "'%s' is a parent type of this type and so cannot be"
5759                 " a component"_err_en_US;
5760         } else if (scope != &currScope()) {
5761           msg = "Component '%s' is already declared in a parent of this"
5762                 " derived type"_err_en_US;
5763         } else {
5764           msg = "Component '%s' is already declared in this"
5765                 " derived type"_err_en_US;
5766         }
5767         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5768       }
5769       return false;
5770     }
5771     if (scope == &currScope() && extends) {
5772       // The parent component has not yet been added to the scope.
5773       scope = extends->scope();
5774     } else {
5775       scope = scope->GetDerivedTypeParent();
5776     }
5777   }
5778   return true;
5779 }
5780 
5781 ParamValue DeclarationVisitor::GetParamValue(
5782     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5783   return common::visit(
5784       common::visitors{
5785           [=](const parser::ScalarIntExpr &x) { // C704
5786             return ParamValue{EvaluateIntExpr(x), attr};
5787           },
5788           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5789           [=](const parser::TypeParamValue::Deferred &) {
5790             return ParamValue::Deferred(attr);
5791           },
5792       },
5793       x.u);
5794 }
5795 
5796 // ConstructVisitor implementation
5797 
5798 void ConstructVisitor::ResolveIndexName(
5799     const parser::ConcurrentControl &control) {
5800   const parser::Name &name{std::get<parser::Name>(control.t)};
5801   auto *prev{FindSymbol(name)};
5802   if (prev) {
5803     if (prev->owner().kind() == Scope::Kind::Forall ||
5804         prev->owner() == currScope()) {
5805       SayAlreadyDeclared(name, *prev);
5806       return;
5807     }
5808     name.symbol = nullptr;
5809   }
5810   auto &symbol{DeclareObjectEntity(name)};
5811   if (symbol.GetType()) {
5812     // type came from explicit type-spec
5813   } else if (!prev) {
5814     ApplyImplicitRules(symbol);
5815   } else {
5816     const Symbol &prevRoot{ResolveAssociations(*prev)};
5817     // prev could be host- use- or construct-associated with another symbol
5818     if (!prevRoot.has<ObjectEntityDetails>() &&
5819         !prevRoot.has<EntityDetails>()) {
5820       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5821           *prev, "Previous declaration of '%s'"_en_US);
5822       context().SetError(symbol);
5823       return;
5824     } else {
5825       if (const auto *type{prevRoot.GetType()}) {
5826         symbol.SetType(*type);
5827       }
5828       if (prevRoot.IsObjectArray()) {
5829         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5830         return;
5831       }
5832     }
5833   }
5834   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5835 }
5836 
5837 // We need to make sure that all of the index-names get declared before the
5838 // expressions in the loop control are evaluated so that references to the
5839 // index-names in the expressions are correctly detected.
5840 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5841   BeginDeclTypeSpec();
5842   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5843   const auto &controls{
5844       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5845   for (const auto &control : controls) {
5846     ResolveIndexName(control);
5847   }
5848   Walk(controls);
5849   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5850   EndDeclTypeSpec();
5851   return false;
5852 }
5853 
5854 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5855   for (auto &name : x.v) {
5856     if (auto *symbol{DeclareLocalEntity(name)}) {
5857       symbol->set(Symbol::Flag::LocalityLocal);
5858     }
5859   }
5860   return false;
5861 }
5862 
5863 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5864   for (auto &name : x.v) {
5865     if (auto *symbol{DeclareLocalEntity(name)}) {
5866       symbol->set(Symbol::Flag::LocalityLocalInit);
5867     }
5868   }
5869   return false;
5870 }
5871 
5872 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5873   for (const auto &name : x.v) {
5874     if (!FindSymbol(name)) {
5875       Say(name,
5876           "Variable '%s' with SHARED locality implicitly declared"_warn_en_US);
5877     }
5878     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5879     if (PassesSharedLocalityChecks(name, prev)) {
5880       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5881     }
5882   }
5883   return false;
5884 }
5885 
5886 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5887   ProcessTypeSpec(x.type);
5888   Walk(x.values);
5889   return false;
5890 }
5891 
5892 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5893 // enclosing ac-implied-do
5894 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5895   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5896   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5897   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5898   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5899   // F'2018 has the scope of the implied DO variable covering the entire
5900   // implied DO production (19.4(5)), which seems wrong in cases where the name
5901   // of the implied DO variable appears in one of the bound expressions. Thus
5902   // this extension, which shrinks the scope of the variable to exclude the
5903   // expressions in the bounds.
5904   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5905   Walk(bounds.lower);
5906   Walk(bounds.upper);
5907   Walk(bounds.step);
5908   EndCheckOnIndexUseInOwnBounds(restore);
5909   PushScope(Scope::Kind::ImpliedDos, nullptr);
5910   DeclareStatementEntity(bounds.name, type);
5911   Walk(values);
5912   PopScope();
5913   return false;
5914 }
5915 
5916 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5917   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5918   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5919   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5920   // See comment in Pre(AcImpliedDo) above.
5921   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5922   Walk(bounds.lower);
5923   Walk(bounds.upper);
5924   Walk(bounds.step);
5925   EndCheckOnIndexUseInOwnBounds(restore);
5926   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5927   if (pushScope) {
5928     PushScope(Scope::Kind::ImpliedDos, nullptr);
5929   }
5930   DeclareStatementEntity(bounds.name, type);
5931   Walk(objects);
5932   if (pushScope) {
5933     PopScope();
5934   }
5935   return false;
5936 }
5937 
5938 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5939 // statement so that the predicate IsInitialized() will be true
5940 // during semantic analysis before the symbol's initializer is constructed.
5941 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5942   common::visit(
5943       common::visitors{
5944           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5945             Walk(y.thing.value());
5946             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5947             if (first.symbol) {
5948               first.symbol->set(Symbol::Flag::InDataStmt);
5949             }
5950           },
5951           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5952       },
5953       x.u);
5954   return false;
5955 }
5956 
5957 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5958   // Subtle: DATA statements may appear in both the specification and
5959   // execution parts, but should be treated as if in the execution part
5960   // for purposes of implicit variable declaration vs. host association.
5961   // When a name first appears as an object in a DATA statement, it should
5962   // be implicitly declared locally as if it had been assigned.
5963   auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
5964   common::visit(common::visitors{
5965                     [&](const Indirection<parser::Variable> &y) {
5966                       Walk(y.value());
5967                       const parser::Name &first{
5968                           parser::GetFirstName(y.value())};
5969                       if (first.symbol) {
5970                         first.symbol->set(Symbol::Flag::InDataStmt);
5971                       }
5972                     },
5973                     [&](const parser::DataImpliedDo &y) {
5974                       PushScope(Scope::Kind::ImpliedDos, nullptr);
5975                       Walk(y);
5976                       PopScope();
5977                     },
5978                 },
5979       x.u);
5980   return false;
5981 }
5982 
5983 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5984   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5985   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5986   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5987     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5988       if (const Symbol * symbol{FindSymbol(*name)}) {
5989         const Symbol &ultimate{symbol->GetUltimate()};
5990         if (ultimate.has<DerivedTypeDetails>()) {
5991           mutableData.u = elem->ConvertToStructureConstructor(
5992               DerivedTypeSpec{name->source, ultimate});
5993         }
5994       }
5995     }
5996   }
5997   return true;
5998 }
5999 
6000 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
6001   if (x.IsDoConcurrent()) {
6002     PushScope(Scope::Kind::Block, nullptr);
6003   }
6004   return true;
6005 }
6006 void ConstructVisitor::Post(const parser::DoConstruct &x) {
6007   if (x.IsDoConcurrent()) {
6008     PopScope();
6009   }
6010 }
6011 
6012 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
6013   PushScope(Scope::Kind::Forall, nullptr);
6014   return true;
6015 }
6016 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
6017 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
6018   PushScope(Scope::Kind::Forall, nullptr);
6019   return true;
6020 }
6021 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
6022 
6023 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
6024   CheckDef(x.v);
6025   PushScope(Scope::Kind::Block, nullptr);
6026   return false;
6027 }
6028 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
6029   PopScope();
6030   CheckRef(x.v);
6031   return false;
6032 }
6033 
6034 void ConstructVisitor::Post(const parser::Selector &x) {
6035   GetCurrentAssociation().selector = ResolveSelector(x);
6036 }
6037 
6038 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
6039   CheckDef(x.t);
6040   PushScope(Scope::Kind::Block, nullptr);
6041   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
6042   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
6043     SetCurrentAssociation(nthLastAssoc);
6044     if (auto *symbol{MakeAssocEntity()}) {
6045       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
6046         Say("Selector must not be a coindexed object"_err_en_US);
6047       }
6048       SetTypeFromAssociation(*symbol);
6049       SetAttrsFromAssociation(*symbol);
6050     }
6051   }
6052   PopAssociation(assocCount);
6053 }
6054 
6055 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
6056   PopScope();
6057   CheckRef(x.v);
6058 }
6059 
6060 bool ConstructVisitor::Pre(const parser::Association &x) {
6061   PushAssociation();
6062   const auto &name{std::get<parser::Name>(x.t)};
6063   GetCurrentAssociation().name = &name;
6064   return true;
6065 }
6066 
6067 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
6068   CheckDef(x.t);
6069   PushScope(Scope::Kind::Block, nullptr);
6070   PushAssociation();
6071   return true;
6072 }
6073 
6074 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
6075   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
6076   const auto &name{std::get<parser::Name>(decl.t)};
6077   if (auto *symbol{FindInScope(name)}) {
6078     const auto &selector{std::get<parser::Selector>(x.t)};
6079     if (auto sel{ResolveSelector(selector)}) {
6080       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
6081       if (!whole || whole->Corank() == 0) {
6082         Say(sel.source, // C1116
6083             "Selector in coarray association must name a coarray"_err_en_US);
6084       } else if (auto dynType{sel.expr->GetType()}) {
6085         if (!symbol->GetType()) {
6086           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
6087         }
6088       }
6089     }
6090   }
6091 }
6092 
6093 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
6094   PopAssociation();
6095   PopScope();
6096   CheckRef(x.t);
6097 }
6098 
6099 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
6100   PushAssociation();
6101   return true;
6102 }
6103 
6104 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
6105   PopAssociation();
6106 }
6107 
6108 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
6109   auto &association{GetCurrentAssociation()};
6110   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6111     // This isn't a name in the current scope, it is in each TypeGuardStmt
6112     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
6113     association.name = &*name;
6114     auto exprType{association.selector.expr->GetType()};
6115     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
6116       Say("Selector must not be a coindexed object"_err_en_US);
6117     }
6118     if (exprType && !exprType->IsPolymorphic()) { // C1159
6119       Say(association.selector.source,
6120           "Selector '%s' in SELECT TYPE statement must be "
6121           "polymorphic"_err_en_US);
6122     }
6123   } else {
6124     if (const Symbol *
6125         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6126       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
6127       if (!IsVariableName(*whole)) {
6128         Say(association.selector.source, // C901
6129             "Selector is not a variable"_err_en_US);
6130         association = {};
6131       }
6132       if (const DeclTypeSpec * type{whole->GetType()}) {
6133         if (!type->IsPolymorphic()) { // C1159
6134           Say(association.selector.source,
6135               "Selector '%s' in SELECT TYPE statement must be "
6136               "polymorphic"_err_en_US);
6137         }
6138       }
6139     } else {
6140       Say(association.selector.source, // C1157
6141           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
6142       association = {};
6143     }
6144   }
6145 }
6146 
6147 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
6148   auto &association{GetCurrentAssociation()};
6149   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6150     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
6151     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
6152     association.name = &*name;
6153   }
6154 }
6155 
6156 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
6157   PushScope(Scope::Kind::Block, nullptr);
6158   return true;
6159 }
6160 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
6161   PopScope();
6162 }
6163 
6164 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
6165   PushScope(Scope::Kind::Block, nullptr);
6166   return true;
6167 }
6168 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
6169   PopScope();
6170 }
6171 
6172 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
6173   if (auto *symbol{MakeAssocEntity()}) {
6174     if (std::holds_alternative<parser::Default>(x.u)) {
6175       SetTypeFromAssociation(*symbol);
6176     } else if (const auto *type{GetDeclTypeSpec()}) {
6177       symbol->SetType(*type);
6178     }
6179     SetAttrsFromAssociation(*symbol);
6180   }
6181 }
6182 
6183 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
6184   if (auto *symbol{MakeAssocEntity()}) {
6185     SetTypeFromAssociation(*symbol);
6186     SetAttrsFromAssociation(*symbol);
6187     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
6188       if (auto val{EvaluateInt64(context(), *init)}) {
6189         auto &details{symbol->get<AssocEntityDetails>()};
6190         details.set_rank(*val);
6191       }
6192     }
6193   }
6194 }
6195 
6196 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
6197   PushAssociation();
6198   return true;
6199 }
6200 
6201 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
6202   PopAssociation();
6203 }
6204 
6205 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
6206   if (x) {
6207     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
6208   }
6209   return true;
6210 }
6211 
6212 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
6213   if (x) {
6214     // Just add an occurrence of this name; checking is done in ValidateLabels
6215     FindSymbol(*x);
6216   }
6217 }
6218 
6219 // Make a symbol for the associating entity of the current association.
6220 Symbol *ConstructVisitor::MakeAssocEntity() {
6221   Symbol *symbol{nullptr};
6222   auto &association{GetCurrentAssociation()};
6223   if (association.name) {
6224     symbol = &MakeSymbol(*association.name, UnknownDetails{});
6225     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
6226       Say(*association.name, // C1102
6227           "The associate name '%s' is already used in this associate statement"_err_en_US);
6228       return nullptr;
6229     }
6230   } else if (const Symbol *
6231       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6232     symbol = &MakeSymbol(whole->name());
6233   } else {
6234     return nullptr;
6235   }
6236   if (auto &expr{association.selector.expr}) {
6237     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
6238   } else {
6239     symbol->set_details(AssocEntityDetails{});
6240   }
6241   return symbol;
6242 }
6243 
6244 // Set the type of symbol based on the current association selector.
6245 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
6246   auto &details{symbol.get<AssocEntityDetails>()};
6247   const MaybeExpr *pexpr{&details.expr()};
6248   if (!*pexpr) {
6249     pexpr = &GetCurrentAssociation().selector.expr;
6250   }
6251   if (*pexpr) {
6252     const SomeExpr &expr{**pexpr};
6253     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
6254       if (const auto *charExpr{
6255               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
6256                   expr)}) {
6257         symbol.SetType(ToDeclTypeSpec(std::move(*type),
6258             FoldExpr(common::visit(
6259                 [](const auto &kindChar) { return kindChar.LEN(); },
6260                 charExpr->u))));
6261       } else {
6262         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
6263       }
6264     } else {
6265       // BOZ literals, procedure designators, &c. are not acceptable
6266       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
6267     }
6268   }
6269 }
6270 
6271 // If current selector is a variable, set some of its attributes on symbol.
6272 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
6273   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
6274   symbol.attrs() |= attrs &
6275       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
6276   if (attrs.test(Attr::POINTER)) {
6277     symbol.attrs().set(Attr::TARGET);
6278   }
6279 }
6280 
6281 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
6282     const parser::Selector &x) {
6283   return common::visit(common::visitors{
6284                            [&](const parser::Expr &expr) {
6285                              return Selector{expr.source, EvaluateExpr(x)};
6286                            },
6287                            [&](const parser::Variable &var) {
6288                              return Selector{var.GetSource(), EvaluateExpr(x)};
6289                            },
6290                        },
6291       x.u);
6292 }
6293 
6294 // Set the current association to the nth to the last association on the
6295 // association stack.  The top of the stack is at n = 1.  This allows access
6296 // to the interior of a list of associations at the top of the stack.
6297 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
6298   CHECK(n > 0 && n <= associationStack_.size());
6299   currentAssociation_ = &associationStack_[associationStack_.size() - n];
6300 }
6301 
6302 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
6303   CHECK(currentAssociation_);
6304   return *currentAssociation_;
6305 }
6306 
6307 void ConstructVisitor::PushAssociation() {
6308   associationStack_.emplace_back(Association{});
6309   currentAssociation_ = &associationStack_.back();
6310 }
6311 
6312 void ConstructVisitor::PopAssociation(std::size_t count) {
6313   CHECK(count > 0 && count <= associationStack_.size());
6314   associationStack_.resize(associationStack_.size() - count);
6315   currentAssociation_ =
6316       associationStack_.empty() ? nullptr : &associationStack_.back();
6317 }
6318 
6319 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6320     evaluate::DynamicType &&type) {
6321   switch (type.category()) {
6322     SWITCH_COVERS_ALL_CASES
6323   case common::TypeCategory::Integer:
6324   case common::TypeCategory::Real:
6325   case common::TypeCategory::Complex:
6326     return context().MakeNumericType(type.category(), type.kind());
6327   case common::TypeCategory::Logical:
6328     return context().MakeLogicalType(type.kind());
6329   case common::TypeCategory::Derived:
6330     if (type.IsAssumedType()) {
6331       return currScope().MakeTypeStarType();
6332     } else if (type.IsUnlimitedPolymorphic()) {
6333       return currScope().MakeClassStarType();
6334     } else {
6335       return currScope().MakeDerivedType(
6336           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
6337                                : DeclTypeSpec::TypeDerived,
6338           common::Clone(type.GetDerivedTypeSpec())
6339 
6340       );
6341     }
6342   case common::TypeCategory::Character:
6343     CRASH_NO_CASE;
6344   }
6345 }
6346 
6347 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6348     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
6349   CHECK(type.category() == common::TypeCategory::Character);
6350   if (length) {
6351     return currScope().MakeCharacterType(
6352         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
6353         KindExpr{type.kind()});
6354   } else {
6355     return currScope().MakeCharacterType(
6356         ParamValue::Deferred(common::TypeParamAttr::Len),
6357         KindExpr{type.kind()});
6358   }
6359 }
6360 
6361 // ResolveNamesVisitor implementation
6362 
6363 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
6364   HandleCall(Symbol::Flag::Function, x.v);
6365   return false;
6366 }
6367 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
6368   HandleCall(Symbol::Flag::Subroutine, x.v);
6369   return false;
6370 }
6371 
6372 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
6373   auto &scope{currScope()};
6374   // Check C896 and C899: where IMPORT statements are allowed
6375   switch (scope.kind()) {
6376   case Scope::Kind::Module:
6377     if (scope.IsModule()) {
6378       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
6379       return false;
6380     } else if (x.kind == common::ImportKind::None) {
6381       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
6382       return false;
6383     }
6384     break;
6385   case Scope::Kind::MainProgram:
6386     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
6387     return false;
6388   case Scope::Kind::Subprogram:
6389     if (scope.parent().IsGlobal()) {
6390       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
6391       return false;
6392     }
6393     break;
6394   case Scope::Kind::BlockData: // C1415 (in part)
6395     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
6396     return false;
6397   default:;
6398   }
6399   if (auto error{scope.SetImportKind(x.kind)}) {
6400     Say(std::move(*error));
6401   }
6402   for (auto &name : x.names) {
6403     if (FindSymbol(scope.parent(), name)) {
6404       scope.add_importName(name.source);
6405     } else {
6406       Say(name, "'%s' not found in host scope"_err_en_US);
6407     }
6408   }
6409   prevImportStmt_ = currStmtSource();
6410   return false;
6411 }
6412 
6413 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6414     const parser::StructureComponent &x) {
6415   return FindComponent(ResolveDataRef(x.base), x.component);
6416 }
6417 
6418 const parser::Name *DeclarationVisitor::ResolveDesignator(
6419     const parser::Designator &x) {
6420   return common::visit(
6421       common::visitors{
6422           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6423           [&](const parser::Substring &x) {
6424             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6425           },
6426       },
6427       x.u);
6428 }
6429 
6430 const parser::Name *DeclarationVisitor::ResolveDataRef(
6431     const parser::DataRef &x) {
6432   return common::visit(
6433       common::visitors{
6434           [=](const parser::Name &y) { return ResolveName(y); },
6435           [=](const Indirection<parser::StructureComponent> &y) {
6436             return ResolveStructureComponent(y.value());
6437           },
6438           [&](const Indirection<parser::ArrayElement> &y) {
6439             Walk(y.value().subscripts);
6440             const parser::Name *name{ResolveDataRef(y.value().base)};
6441             if (name && name->symbol) {
6442               if (!IsProcedure(*name->symbol)) {
6443                 ConvertToObjectEntity(*name->symbol);
6444               } else if (!context().HasError(*name->symbol)) {
6445                 SayWithDecl(*name, *name->symbol,
6446                     "Cannot reference function '%s' as data"_err_en_US);
6447               }
6448             }
6449             return name;
6450           },
6451           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6452             Walk(y.value().imageSelector);
6453             return ResolveDataRef(y.value().base);
6454           },
6455       },
6456       x.u);
6457 }
6458 
6459 // If implicit types are allowed, ensure name is in the symbol table.
6460 // Otherwise, report an error if it hasn't been declared.
6461 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6462   FindSymbol(name);
6463   if (CheckForHostAssociatedImplicit(name)) {
6464     NotePossibleBadForwardRef(name);
6465     return &name;
6466   }
6467   if (Symbol * symbol{name.symbol}) {
6468     if (CheckUseError(name)) {
6469       return nullptr; // reported an error
6470     }
6471     NotePossibleBadForwardRef(name);
6472     symbol->set(Symbol::Flag::ImplicitOrError, false);
6473     if (IsUplevelReference(*symbol)) {
6474       MakeHostAssocSymbol(name, *symbol);
6475     } else if (IsDummy(*symbol) ||
6476         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6477       ConvertToObjectEntity(*symbol);
6478       ApplyImplicitRules(*symbol);
6479     }
6480     if (checkIndexUseInOwnBounds_ &&
6481         *checkIndexUseInOwnBounds_ == name.source) {
6482       Say(name,
6483           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_port_en_US,
6484           name.source);
6485     }
6486     return &name;
6487   }
6488   if (isImplicitNoneType()) {
6489     Say(name, "No explicit type declared for '%s'"_err_en_US);
6490     return nullptr;
6491   }
6492   // Create the symbol then ensure it is accessible
6493   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6494     Say(name,
6495         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6496         name.source);
6497   }
6498   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6499   auto *symbol{FindSymbol(name)};
6500   if (!symbol) {
6501     Say(name,
6502         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6503     return nullptr;
6504   }
6505   ConvertToObjectEntity(*symbol);
6506   ApplyImplicitRules(*symbol);
6507   NotePossibleBadForwardRef(name);
6508   return &name;
6509 }
6510 
6511 // A specification expression may refer to a symbol in the host procedure that
6512 // is implicitly typed. Because specification parts are processed before
6513 // execution parts, this may be the first time we see the symbol. It can't be a
6514 // local in the current scope (because it's in a specification expression) so
6515 // either it is implicitly declared in the host procedure or it is an error.
6516 // We create a symbol in the host assuming it is the former; if that proves to
6517 // be wrong we report an error later in CheckDeclarations().
6518 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6519     const parser::Name &name) {
6520   if (!inSpecificationPart_) {
6521     return false;
6522   }
6523   if (name.symbol) {
6524     ApplyImplicitRules(*name.symbol, true);
6525   }
6526   Symbol *hostSymbol;
6527   Scope *host{GetHostProcedure()};
6528   if (!host || isImplicitNoneType(*host)) {
6529     return false;
6530   }
6531   if (!name.symbol) {
6532     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6533     ConvertToObjectEntity(*hostSymbol);
6534     ApplyImplicitRules(*hostSymbol);
6535     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6536   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6537     hostSymbol = name.symbol;
6538   } else {
6539     return false;
6540   }
6541   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6542   if (isImplicitNoneType()) {
6543     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6544   } else {
6545     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6546   }
6547   return true;
6548 }
6549 
6550 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6551   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6552   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6553     return false;
6554   } else {
6555     Scope::Kind kind{symbolUnit.kind()};
6556     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6557   }
6558 }
6559 
6560 // base is a part-ref of a derived type; find the named component in its type.
6561 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6562 // COMPLEX component references (%re, %im).
6563 const parser::Name *DeclarationVisitor::FindComponent(
6564     const parser::Name *base, const parser::Name &component) {
6565   if (!base || !base->symbol) {
6566     return nullptr;
6567   }
6568   if (auto *misc{base->symbol->detailsIf<MiscDetails>()}) {
6569     if (component.source == "kind") {
6570       if (misc->kind() == MiscDetails::Kind::ComplexPartRe ||
6571           misc->kind() == MiscDetails::Kind::ComplexPartIm ||
6572           misc->kind() == MiscDetails::Kind::KindParamInquiry ||
6573           misc->kind() == MiscDetails::Kind::LenParamInquiry) {
6574         // x%{re,im,kind,len}%kind
6575         MakePlaceholder(component, MiscDetails::Kind::KindParamInquiry);
6576         return &component;
6577       }
6578     }
6579   }
6580   auto &symbol{base->symbol->GetUltimate()};
6581   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6582     SayWithDecl(*base, symbol,
6583         "'%s' is an invalid base for a component reference"_err_en_US);
6584     return nullptr;
6585   }
6586   auto *type{symbol.GetType()};
6587   if (!type) {
6588     return nullptr; // should have already reported error
6589   }
6590   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6591     auto category{intrinsic->category()};
6592     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6593     if (component.source == "kind") {
6594       miscKind = MiscDetails::Kind::KindParamInquiry;
6595     } else if (category == TypeCategory::Character) {
6596       if (component.source == "len") {
6597         miscKind = MiscDetails::Kind::LenParamInquiry;
6598       }
6599     } else if (category == TypeCategory::Complex) {
6600       if (component.source == "re") {
6601         miscKind = MiscDetails::Kind::ComplexPartRe;
6602       } else if (component.source == "im") {
6603         miscKind = MiscDetails::Kind::ComplexPartIm;
6604       }
6605     }
6606     if (miscKind != MiscDetails::Kind::None) {
6607       MakePlaceholder(component, miscKind);
6608       return &component;
6609     }
6610   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6611     if (const Scope * scope{derived->scope()}) {
6612       if (Resolve(component, scope->FindComponent(component.source))) {
6613         if (auto msg{
6614                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6615           context().Say(component.source, *msg);
6616         }
6617         return &component;
6618       } else {
6619         SayDerivedType(component.source,
6620             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6621       }
6622     }
6623     return nullptr;
6624   }
6625   if (symbol.test(Symbol::Flag::Implicit)) {
6626     Say(*base,
6627         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6628   } else {
6629     SayWithDecl(
6630         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6631   }
6632   return nullptr;
6633 }
6634 
6635 void DeclarationVisitor::Initialization(const parser::Name &name,
6636     const parser::Initialization &init, bool inComponentDecl) {
6637   // Traversal of the initializer was deferred to here so that the
6638   // symbol being declared can be available for use in the expression, e.g.:
6639   //   real, parameter :: x = tiny(x)
6640   if (!name.symbol) {
6641     return;
6642   }
6643   Symbol &ultimate{name.symbol->GetUltimate()};
6644   if (IsAllocatable(ultimate)) {
6645     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6646     return;
6647   }
6648   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6649     // TODO: check C762 - all bounds and type parameters of component
6650     // are colons or constant expressions if component is initialized
6651     common::visit(
6652         common::visitors{
6653             [&](const parser::ConstantExpr &expr) {
6654               NonPointerInitialization(name, expr);
6655             },
6656             [&](const parser::NullInit &null) {
6657               Walk(null);
6658               if (auto nullInit{EvaluateExpr(null)}) {
6659                 if (!evaluate::IsNullPointer(*nullInit)) {
6660                   Say(name,
6661                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6662                 } else if (IsPointer(ultimate)) {
6663                   object->set_init(std::move(*nullInit));
6664                 } else {
6665                   Say(name,
6666                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6667                 }
6668               }
6669             },
6670             [&](const parser::InitialDataTarget &) {
6671               // Defer analysis to the end of the specification part
6672               // so that forward references and attribute checks like SAVE
6673               // work better.
6674               ultimate.set(Symbol::Flag::InDataStmt);
6675             },
6676             [&](const std::list<Indirection<parser::DataStmtValue>> &values) {
6677               // Handled later in data-to-inits conversion
6678               ultimate.set(Symbol::Flag::InDataStmt);
6679               Walk(values);
6680             },
6681         },
6682         init.u);
6683   }
6684 }
6685 
6686 void DeclarationVisitor::PointerInitialization(
6687     const parser::Name &name, const parser::InitialDataTarget &target) {
6688   if (name.symbol) {
6689     Symbol &ultimate{name.symbol->GetUltimate()};
6690     if (!context().HasError(ultimate)) {
6691       if (IsPointer(ultimate)) {
6692         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6693           CHECK(!details->init());
6694           Walk(target);
6695           if (MaybeExpr expr{EvaluateExpr(target)}) {
6696             // Validation is done in declaration checking.
6697             details->set_init(std::move(*expr));
6698           }
6699         }
6700       } else {
6701         Say(name,
6702             "'%s' is not a pointer but is initialized like one"_err_en_US);
6703         context().SetError(ultimate);
6704       }
6705     }
6706   }
6707 }
6708 void DeclarationVisitor::PointerInitialization(
6709     const parser::Name &name, const parser::ProcPointerInit &target) {
6710   if (name.symbol) {
6711     Symbol &ultimate{name.symbol->GetUltimate()};
6712     if (!context().HasError(ultimate)) {
6713       if (IsProcedurePointer(ultimate)) {
6714         auto &details{ultimate.get<ProcEntityDetails>()};
6715         CHECK(!details.init());
6716         Walk(target);
6717         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6718           if (targetName->symbol) {
6719             // Validation is done in declaration checking.
6720             details.set_init(*targetName->symbol);
6721           }
6722         } else {
6723           details.set_init(nullptr); // explicit NULL()
6724         }
6725       } else {
6726         Say(name,
6727             "'%s' is not a procedure pointer but is initialized "
6728             "like one"_err_en_US);
6729         context().SetError(ultimate);
6730       }
6731     }
6732   }
6733 }
6734 
6735 void DeclarationVisitor::NonPointerInitialization(
6736     const parser::Name &name, const parser::ConstantExpr &expr) {
6737   if (name.symbol) {
6738     Symbol &ultimate{name.symbol->GetUltimate()};
6739     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6740       if (IsPointer(ultimate)) {
6741         Say(name,
6742             "'%s' is a pointer but is not initialized like one"_err_en_US);
6743       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6744         CHECK(!details->init());
6745         Walk(expr);
6746         if (ultimate.owner().IsParameterizedDerivedType()) {
6747           // Save the expression for per-instantiation analysis.
6748           details->set_unanalyzedPDTComponentInit(&expr.thing.value());
6749         } else {
6750           if (MaybeExpr folded{EvaluateNonPointerInitializer(
6751                   ultimate, expr, expr.thing.value().source)}) {
6752             details->set_init(std::move(*folded));
6753           }
6754         }
6755       }
6756     }
6757   }
6758 }
6759 
6760 void ResolveNamesVisitor::HandleCall(
6761     Symbol::Flag procFlag, const parser::Call &call) {
6762   common::visit(
6763       common::visitors{
6764           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6765           [&](const parser::ProcComponentRef &x) { Walk(x); },
6766       },
6767       std::get<parser::ProcedureDesignator>(call.t).u);
6768   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6769 }
6770 
6771 void ResolveNamesVisitor::HandleProcedureName(
6772     Symbol::Flag flag, const parser::Name &name) {
6773   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6774   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6775   if (!symbol) {
6776     if (IsIntrinsic(name.source, flag)) {
6777       symbol =
6778           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6779     } else {
6780       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6781     }
6782     Resolve(name, *symbol);
6783     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6784       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6785         MakeExternal(*symbol);
6786       }
6787     }
6788     ConvertToProcEntity(*symbol);
6789     SetProcFlag(name, *symbol, flag);
6790   } else if (CheckUseError(name)) {
6791     // error was reported
6792   } else {
6793     auto &nonUltimateSymbol{*symbol};
6794     symbol = &Resolve(name, symbol)->GetUltimate();
6795     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6796     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6797         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6798       AcquireIntrinsicProcedureFlags(*symbol);
6799     }
6800     if (!SetProcFlag(name, *symbol, flag)) {
6801       return; // reported error
6802     }
6803     if (!symbol->has<GenericDetails>()) {
6804       CheckImplicitNoneExternal(name.source, *symbol);
6805     }
6806     if (symbol->has<SubprogramDetails>() &&
6807         symbol->attrs().test(Attr::ABSTRACT)) {
6808       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6809     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6810         symbol->has<AssocEntityDetails>()) {
6811       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6812       // here as procedure-designators because this means the related
6813       // FunctionReference are mis-parsed structure constructors or array
6814       // references that will be fixed later when analyzing expressions.
6815     } else if (symbol->has<ObjectEntityDetails>()) {
6816       // Symbols with ObjectEntityDetails are also accepted because this can be
6817       // a mis-parsed array references that will be fixed later. Ensure that if
6818       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6819       // is created for the current scope.
6820       // Operate on non ultimate symbol so that HostAssocDetails are also
6821       // created for symbols used associated in the host procedure.
6822       if (IsUplevelReference(nonUltimateSymbol)) {
6823         MakeHostAssocSymbol(name, nonUltimateSymbol);
6824       }
6825     } else if (symbol->test(Symbol::Flag::Implicit)) {
6826       Say(name,
6827           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6828     } else {
6829       SayWithDecl(name, *symbol,
6830           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6831     }
6832   }
6833 }
6834 
6835 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6836     const SourceName &name, const Symbol &symbol) {
6837   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6838       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6839     Say(name,
6840         "'%s' is an external procedure without the EXTERNAL"
6841         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6842     return false;
6843   }
6844   return true;
6845 }
6846 
6847 // Variant of HandleProcedureName() for use while skimming the executable
6848 // part of a subprogram to catch calls to dummy procedures that are part
6849 // of the subprogram's interface, and to mark as procedures any symbols
6850 // that might otherwise have been miscategorized as objects.
6851 void ResolveNamesVisitor::NoteExecutablePartCall(
6852     Symbol::Flag flag, const parser::Call &call) {
6853   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6854   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6855     // Subtlety: The symbol pointers in the parse tree are not set, because
6856     // they might end up resolving elsewhere (e.g., construct entities in
6857     // SELECT TYPE).
6858     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6859       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6860               ? Symbol::Flag::Function
6861               : Symbol::Flag::Subroutine};
6862       if (!symbol->test(other)) {
6863         ConvertToProcEntity(*symbol);
6864         if (symbol->has<ProcEntityDetails>()) {
6865           symbol->set(flag);
6866           if (IsDummy(*symbol)) {
6867             symbol->attrs().set(Attr::EXTERNAL);
6868           }
6869           ApplyImplicitRules(*symbol);
6870         }
6871       }
6872     }
6873   }
6874 }
6875 
6876 static bool IsLocallyImplicitGlobalSymbol(
6877     const Symbol &symbol, const parser::Name &localName) {
6878   return symbol.owner().IsGlobal() &&
6879       (!symbol.scope() ||
6880           !symbol.scope()->sourceRange().Contains(localName.source));
6881 }
6882 
6883 static bool TypesMismatchIfNonNull(
6884     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
6885   return type1 && type2 && *type1 != *type2;
6886 }
6887 
6888 // Check and set the Function or Subroutine flag on symbol; false on error.
6889 bool ResolveNamesVisitor::SetProcFlag(
6890     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6891   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6892     SayWithDecl(
6893         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6894     return false;
6895   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6896       flag == Symbol::Flag::Function) {
6897     SayWithDecl(
6898         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6899     return false;
6900   } else if (flag == Symbol::Flag::Function &&
6901       IsLocallyImplicitGlobalSymbol(symbol, name) &&
6902       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
6903     SayWithDecl(name, symbol,
6904         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
6905     return false;
6906   } else if (symbol.has<ProcEntityDetails>()) {
6907     symbol.set(flag); // in case it hasn't been set yet
6908     if (flag == Symbol::Flag::Function) {
6909       ApplyImplicitRules(symbol);
6910     }
6911     if (symbol.attrs().test(Attr::INTRINSIC)) {
6912       AcquireIntrinsicProcedureFlags(symbol);
6913     }
6914   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6915     SayWithDecl(
6916         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6917   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6918     AcquireIntrinsicProcedureFlags(symbol);
6919   }
6920   return true;
6921 }
6922 
6923 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6924   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6925   if (!currScope().IsModule()) { // C869
6926     Say(currStmtSource().value(),
6927         "%s statement may only appear in the specification part of a module"_err_en_US,
6928         EnumToString(accessAttr));
6929     return false;
6930   }
6931   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6932   if (accessIds.empty()) {
6933     if (prevAccessStmt_) { // C869
6934       Say("The default accessibility of this module has already been declared"_err_en_US)
6935           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6936     }
6937     prevAccessStmt_ = currStmtSource();
6938     defaultAccess_ = accessAttr;
6939   } else {
6940     for (const auto &accessId : accessIds) {
6941       common::visit(
6942           common::visitors{
6943               [=](const parser::Name &y) {
6944                 Resolve(y, SetAccess(y.source, accessAttr));
6945               },
6946               [=](const Indirection<parser::GenericSpec> &y) {
6947                 auto info{GenericSpecInfo{y.value()}};
6948                 const auto &symbolName{info.symbolName()};
6949                 if (auto *symbol{FindInScope(symbolName)}) {
6950                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6951                 } else if (info.kind().IsName()) {
6952                   info.Resolve(&SetAccess(symbolName, accessAttr));
6953                 } else {
6954                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6955                 }
6956               },
6957           },
6958           accessId.u);
6959     }
6960   }
6961   return false;
6962 }
6963 
6964 // Set the access specification for this symbol.
6965 Symbol &ModuleVisitor::SetAccess(
6966     const SourceName &name, Attr attr, Symbol *symbol) {
6967   if (!symbol) {
6968     symbol = &MakeSymbol(name);
6969   }
6970   Attrs &attrs{symbol->attrs()};
6971   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6972     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6973     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6974     Say(name,
6975         WithSeverity(
6976             "The accessibility of '%s' has already been specified as %s"_warn_en_US,
6977             attr != prev ? parser::Severity::Error : parser::Severity::Warning),
6978         MakeOpName(name), EnumToString(prev));
6979   } else {
6980     attrs.set(attr);
6981   }
6982   return *symbol;
6983 }
6984 
6985 static bool NeedsExplicitType(const Symbol &symbol) {
6986   if (symbol.has<UnknownDetails>()) {
6987     return true;
6988   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6989     return !details->type();
6990   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6991     return !details->type();
6992   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6993     return !details->interface().symbol() && !details->interface().type();
6994   } else {
6995     return false;
6996   }
6997 }
6998 
6999 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
7000   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
7001       implicitPart, decls] = x.t;
7002   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
7003   auto stateRestorer{
7004       common::ScopedSet(specPartState_, SpecificationPartState{})};
7005   Walk(accDecls);
7006   Walk(ompDecls);
7007   Walk(compilerDirectives);
7008   Walk(useStmts);
7009   ClearUseRenames();
7010   ClearUseOnly();
7011   ClearExplicitIntrinsicUses();
7012   Walk(importStmts);
7013   Walk(implicitPart);
7014   for (const auto &decl : decls) {
7015     if (const auto *spec{
7016             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
7017       PreSpecificationConstruct(*spec);
7018     }
7019   }
7020   Walk(decls);
7021   FinishSpecificationPart(decls);
7022   return false;
7023 }
7024 
7025 // Initial processing on specification constructs, before visiting them.
7026 void ResolveNamesVisitor::PreSpecificationConstruct(
7027     const parser::SpecificationConstruct &spec) {
7028   common::visit(
7029       common::visitors{
7030           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
7031             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
7032           },
7033           [&](const Indirection<parser::InterfaceBlock> &y) {
7034             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
7035                 y.value().t)};
7036             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
7037               CreateGeneric(*spec);
7038             }
7039           },
7040           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
7041             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
7042               CreateCommonBlockSymbols(*commonStmt);
7043             }
7044           },
7045           [&](const auto &) {},
7046       },
7047       spec.u);
7048 }
7049 
7050 void ResolveNamesVisitor::CreateCommonBlockSymbols(
7051     const parser::CommonStmt &commonStmt) {
7052   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
7053     const auto &[name, objects] = block.t;
7054     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
7055     for (const auto &object : objects) {
7056       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
7057       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
7058         details->set_commonBlock(commonBlock);
7059         commonBlock.get<CommonBlockDetails>().add_object(obj);
7060       }
7061     }
7062   }
7063 }
7064 
7065 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
7066   auto info{GenericSpecInfo{x}};
7067   SourceName symbolName{info.symbolName()};
7068   if (IsLogicalConstant(context(), symbolName)) {
7069     Say(symbolName,
7070         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7071     return;
7072   }
7073   GenericDetails genericDetails;
7074   Symbol *existing{nullptr};
7075   // Check all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
7076   for (const std::string &n : GetAllNames(context(), symbolName)) {
7077     if (auto iter{currScope().find(n)}; iter != currScope().end()) {
7078       existing = &*iter->second;
7079       break;
7080     }
7081   }
7082   if (existing) {
7083     Symbol &ultimate{existing->GetUltimate()};
7084     if (const auto *existingGeneric{ultimate.detailsIf<GenericDetails>()}) {
7085       if (const auto *existingUse{existing->detailsIf<UseDetails>()}) {
7086         // Create a local copy of a use associated generic so that
7087         // it can be locally extended without corrupting the original.
7088         genericDetails.CopyFrom(*existingGeneric);
7089         AddGenericUse(genericDetails, existing->name(), existingUse->symbol());
7090       } else if (existing == &ultimate) {
7091         // Extending an extant generic in the same scope
7092         info.Resolve(existing);
7093         return;
7094       } else {
7095         // Host association of a generic is handled in ResolveGeneric()
7096         CHECK(existing->has<HostAssocDetails>());
7097       }
7098     } else if (ultimate.has<SubprogramDetails>() ||
7099         ultimate.has<SubprogramNameDetails>()) {
7100       genericDetails.set_specific(ultimate);
7101     } else if (ultimate.has<DerivedTypeDetails>()) {
7102       genericDetails.set_derivedType(ultimate);
7103     } else {
7104       SayAlreadyDeclared(symbolName, *existing);
7105       return;
7106     }
7107     EraseSymbol(*existing);
7108   }
7109   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
7110 }
7111 
7112 void ResolveNamesVisitor::FinishSpecificationPart(
7113     const std::list<parser::DeclarationConstruct> &decls) {
7114   badStmtFuncFound_ = false;
7115   funcResultStack().CompleteFunctionResultType();
7116   CheckImports();
7117   bool inModule{currScope().kind() == Scope::Kind::Module};
7118   for (auto &pair : currScope()) {
7119     auto &symbol{*pair.second};
7120     if (NeedsExplicitType(symbol)) {
7121       ApplyImplicitRules(symbol);
7122     }
7123     if (IsDummy(symbol) && isImplicitNoneType() &&
7124         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
7125       Say(symbol.name(),
7126           "No explicit type declared for dummy argument '%s'"_err_en_US);
7127       context().SetError(symbol);
7128     }
7129     if (symbol.has<GenericDetails>()) {
7130       CheckGenericProcedures(symbol);
7131     }
7132     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
7133         !symbol.test(Symbol::Flag::Function) &&
7134         !symbol.test(Symbol::Flag::Subroutine)) {
7135       // in a module, external proc without return type is subroutine
7136       symbol.set(
7137           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
7138     }
7139     if (!symbol.has<HostAssocDetails>()) {
7140       CheckPossibleBadForwardRef(symbol);
7141     }
7142   }
7143   currScope().InstantiateDerivedTypes();
7144   for (const auto &decl : decls) {
7145     if (const auto *statement{std::get_if<
7146             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
7147             &decl.u)}) {
7148       AnalyzeStmtFunctionStmt(statement->statement.value());
7149     }
7150   }
7151   // TODO: what about instantiations in BLOCK?
7152   CheckSaveStmts();
7153   CheckCommonBlocks();
7154   if (!inInterfaceBlock()) {
7155     // TODO: warn for the case where the EQUIVALENCE statement is in a
7156     // procedure declaration in an interface block
7157     CheckEquivalenceSets();
7158   }
7159 }
7160 
7161 // Analyze the bodies of statement functions now that the symbols in this
7162 // specification part have been fully declared and implicitly typed.
7163 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
7164     const parser::StmtFunctionStmt &stmtFunc) {
7165   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
7166   if (!symbol || !symbol->has<SubprogramDetails>()) {
7167     return;
7168   }
7169   auto &details{symbol->get<SubprogramDetails>()};
7170   auto expr{AnalyzeExpr(
7171       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
7172   if (!expr) {
7173     context().SetError(*symbol);
7174     return;
7175   }
7176   if (auto type{evaluate::DynamicType::From(*symbol)}) {
7177     auto converted{ConvertToType(*type, std::move(*expr))};
7178     if (!converted) {
7179       context().SetError(*symbol);
7180       return;
7181     }
7182     details.set_stmtFunction(std::move(*converted));
7183   } else {
7184     details.set_stmtFunction(std::move(*expr));
7185   }
7186 }
7187 
7188 void ResolveNamesVisitor::CheckImports() {
7189   auto &scope{currScope()};
7190   switch (scope.GetImportKind()) {
7191   case common::ImportKind::None:
7192     break;
7193   case common::ImportKind::All:
7194     // C8102: all entities in host must not be hidden
7195     for (const auto &pair : scope.parent()) {
7196       auto &name{pair.first};
7197       std::optional<SourceName> scopeName{scope.GetName()};
7198       if (!scopeName || name != *scopeName) {
7199         CheckImport(prevImportStmt_.value(), name);
7200       }
7201     }
7202     break;
7203   case common::ImportKind::Default:
7204   case common::ImportKind::Only:
7205     // C8102: entities named in IMPORT must not be hidden
7206     for (auto &name : scope.importNames()) {
7207       CheckImport(name, name);
7208     }
7209     break;
7210   }
7211 }
7212 
7213 void ResolveNamesVisitor::CheckImport(
7214     const SourceName &location, const SourceName &name) {
7215   if (auto *symbol{FindInScope(name)}) {
7216     const Symbol &ultimate{symbol->GetUltimate()};
7217     if (&ultimate.owner() == &currScope()) {
7218       Say(location, "'%s' from host is not accessible"_err_en_US, name)
7219           .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
7220               symbol->name());
7221     }
7222   }
7223 }
7224 
7225 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
7226   return CheckNotInBlock("IMPLICIT") && // C1107
7227       ImplicitRulesVisitor::Pre(x);
7228 }
7229 
7230 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
7231   common::visit(common::visitors{
7232                     [&](const parser::Name &x) { ResolveName(x); },
7233                     [&](const parser::StructureComponent &x) {
7234                       ResolveStructureComponent(x);
7235                     },
7236                 },
7237       x.u);
7238 }
7239 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
7240   common::visit(common::visitors{
7241                     [&](const parser::Name &x) { ResolveName(x); },
7242                     [&](const parser::StructureComponent &x) {
7243                       ResolveStructureComponent(x);
7244                     },
7245                 },
7246       x.u);
7247 }
7248 
7249 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
7250   const auto &dataRef{std::get<parser::DataRef>(x.t)};
7251   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
7252   const auto &expr{std::get<parser::Expr>(x.t)};
7253   ResolveDataRef(dataRef);
7254   Walk(bounds);
7255   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
7256   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
7257     if (NameIsKnownOrIntrinsic(*name)) {
7258       // If the name is known because it is an object entity from a host
7259       // procedure, create a host associated symbol.
7260       if (Symbol * symbol{name->symbol}; symbol &&
7261           symbol->GetUltimate().has<ObjectEntityDetails>() &&
7262           IsUplevelReference(*symbol)) {
7263         MakeHostAssocSymbol(*name, *symbol);
7264       }
7265       return false;
7266     }
7267   }
7268   Walk(expr);
7269   return false;
7270 }
7271 void ResolveNamesVisitor::Post(const parser::Designator &x) {
7272   ResolveDesignator(x);
7273 }
7274 
7275 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
7276   ResolveStructureComponent(x.v.thing);
7277 }
7278 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
7279   DeclTypeSpecVisitor::Post(x);
7280   ConstructVisitor::Post(x);
7281 }
7282 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
7283   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
7284   if (HandleStmtFunction(x)) {
7285     return false;
7286   } else {
7287     // This is an array element assignment: resolve names of indices
7288     const auto &names{std::get<std::list<parser::Name>>(x.t)};
7289     for (auto &name : names) {
7290       ResolveName(name);
7291     }
7292     return true;
7293   }
7294 }
7295 
7296 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
7297   const parser::Name &name{x.v};
7298   if (FindSymbol(name)) {
7299     // OK
7300   } else if (IsLogicalConstant(context(), name.source)) {
7301     Say(name,
7302         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7303   } else {
7304     // Resolved later in expression semantics
7305     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
7306   }
7307   return false;
7308 }
7309 
7310 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
7311   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7312     ConvertToObjectEntity(DEREF(name->symbol));
7313   }
7314 }
7315 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
7316   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7317     ConvertToObjectEntity(DEREF(name->symbol));
7318   }
7319 }
7320 
7321 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
7322   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
7323           x.u)) {
7324     // TODO: global directives
7325     return true;
7326   }
7327   auto root{ProgramTree::Build(x)};
7328   SetScope(topScope_);
7329   ResolveSpecificationParts(root);
7330   FinishSpecificationParts(root);
7331   ResolveExecutionParts(root);
7332   ResolveAccParts(context(), x);
7333   ResolveOmpParts(context(), x);
7334   return false;
7335 }
7336 
7337 // References to procedures need to record that their symbols are known
7338 // to be procedures, so that they don't get converted to objects by default.
7339 class ExecutionPartSkimmer {
7340 public:
7341   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
7342       : resolver_{resolver} {}
7343 
7344   void Walk(const parser::ExecutionPart *exec) {
7345     if (exec) {
7346       parser::Walk(*exec, *this);
7347     }
7348   }
7349 
7350   template <typename A> bool Pre(const A &) { return true; }
7351   template <typename A> void Post(const A &) {}
7352   void Post(const parser::FunctionReference &fr) {
7353     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
7354   }
7355   void Post(const parser::CallStmt &cs) {
7356     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
7357   }
7358 
7359 private:
7360   ResolveNamesVisitor &resolver_;
7361 };
7362 
7363 // Build the scope tree and resolve names in the specification parts of this
7364 // node and its children
7365 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
7366   if (node.isSpecificationPartResolved()) {
7367     return; // been here already
7368   }
7369   node.set_isSpecificationPartResolved();
7370   if (!BeginScopeForNode(node)) {
7371     return; // an error prevented scope from being created
7372   }
7373   Scope &scope{currScope()};
7374   node.set_scope(scope);
7375   AddSubpNames(node);
7376   common::visit(
7377       [&](const auto *x) {
7378         if (x) {
7379           Walk(*x);
7380         }
7381       },
7382       node.stmt());
7383   Walk(node.spec());
7384   // If this is a function, convert result to an object. This is to prevent the
7385   // result from being converted later to a function symbol if it is called
7386   // inside the function.
7387   // If the result is function pointer, then ConvertToObjectEntity will not
7388   // convert the result to an object, and calling the symbol inside the function
7389   // will result in calls to the result pointer.
7390   // A function cannot be called recursively if RESULT was not used to define a
7391   // distinct result name (15.6.2.2 point 4.).
7392   if (Symbol * symbol{scope.symbol()}) {
7393     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
7394       if (details->isFunction()) {
7395         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
7396       }
7397     }
7398   }
7399   if (node.IsModule()) {
7400     ApplyDefaultAccess();
7401   }
7402   for (auto &child : node.children()) {
7403     ResolveSpecificationParts(child);
7404   }
7405   ExecutionPartSkimmer{*this}.Walk(node.exec());
7406   EndScopeForNode(node);
7407   // Ensure that every object entity has a type.
7408   for (auto &pair : *node.scope()) {
7409     ApplyImplicitRules(*pair.second);
7410   }
7411 }
7412 
7413 // Add SubprogramNameDetails symbols for module and internal subprograms and
7414 // their ENTRY statements.
7415 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
7416   auto kind{
7417       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
7418   for (auto &child : node.children()) {
7419     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
7420     auto childKind{child.GetKind()};
7421     if (childKind == ProgramTree::Kind::Function) {
7422       symbol.set(Symbol::Flag::Function);
7423     } else if (childKind == ProgramTree::Kind::Subroutine) {
7424       symbol.set(Symbol::Flag::Subroutine);
7425     } else {
7426       continue; // make ENTRY symbols only where valid
7427     }
7428     for (const auto &entryStmt : child.entryStmts()) {
7429       SubprogramNameDetails details{kind, child};
7430       auto &symbol{
7431           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
7432       symbol.set(child.GetSubpFlag());
7433     }
7434   }
7435   for (const auto &generic : node.genericSpecs()) {
7436     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
7437       if (currScope().find(name->source) != currScope().end()) {
7438         // If this scope has both a generic interface and a contained
7439         // subprogram with the same name, create the generic's symbol
7440         // now so that any other generics of the same name that are pulled
7441         // into scope later via USE association will properly merge instead
7442         // of raising a bogus error due a conflict with the subprogram.
7443         CreateGeneric(*generic);
7444       }
7445     }
7446   }
7447 }
7448 
7449 // Push a new scope for this node or return false on error.
7450 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
7451   switch (node.GetKind()) {
7452     SWITCH_COVERS_ALL_CASES
7453   case ProgramTree::Kind::Program:
7454     PushScope(Scope::Kind::MainProgram,
7455         &MakeSymbol(node.name(), MainProgramDetails{}));
7456     return true;
7457   case ProgramTree::Kind::Function:
7458   case ProgramTree::Kind::Subroutine:
7459     return BeginSubprogram(node.name(), node.GetSubpFlag(),
7460         node.HasModulePrefix(), node.bindingSpec(), &node.entryStmts());
7461   case ProgramTree::Kind::MpSubprogram:
7462     return BeginMpSubprogram(node.name());
7463   case ProgramTree::Kind::Module:
7464     BeginModule(node.name(), false);
7465     return true;
7466   case ProgramTree::Kind::Submodule:
7467     return BeginSubmodule(node.name(), node.GetParentId());
7468   case ProgramTree::Kind::BlockData:
7469     PushBlockDataScope(node.name());
7470     return true;
7471   }
7472 }
7473 
7474 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
7475   std::optional<parser::CharBlock> stmtSource;
7476   const std::optional<parser::LanguageBindingSpec> *binding{nullptr};
7477   common::visit(
7478       common::visitors{
7479           [&](const parser::Statement<parser::FunctionStmt> *stmt) {
7480             if (stmt) {
7481               stmtSource = stmt->source;
7482               if (const auto &maybeSuffix{
7483                       std::get<std::optional<parser::Suffix>>(
7484                           stmt->statement.t)}) {
7485                 binding = &maybeSuffix->binding;
7486               }
7487             }
7488           },
7489           [&](const parser::Statement<parser::SubroutineStmt> *stmt) {
7490             if (stmt) {
7491               stmtSource = stmt->source;
7492               binding = &std::get<std::optional<parser::LanguageBindingSpec>>(
7493                   stmt->statement.t);
7494             }
7495           },
7496           [](const auto *) {},
7497       },
7498       node.stmt());
7499   EndSubprogram(stmtSource, binding);
7500 }
7501 
7502 // Some analyses and checks, such as the processing of initializers of
7503 // pointers, are deferred until all of the pertinent specification parts
7504 // have been visited.  This deferred processing enables the use of forward
7505 // references in these circumstances.
7506 class DeferredCheckVisitor {
7507 public:
7508   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7509       : resolver_{resolver} {}
7510 
7511   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7512 
7513   template <typename A> bool Pre(const A &) { return true; }
7514   template <typename A> void Post(const A &) {}
7515 
7516   void Post(const parser::DerivedTypeStmt &x) {
7517     const auto &name{std::get<parser::Name>(x.t)};
7518     if (Symbol * symbol{name.symbol}) {
7519       if (Scope * scope{symbol->scope()}) {
7520         if (scope->IsDerivedType()) {
7521           resolver_.PushScope(*scope);
7522           pushedScope_ = true;
7523         }
7524       }
7525     }
7526   }
7527   void Post(const parser::EndTypeStmt &) {
7528     if (pushedScope_) {
7529       resolver_.PopScope();
7530       pushedScope_ = false;
7531     }
7532   }
7533 
7534   void Post(const parser::ProcInterface &pi) {
7535     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7536       resolver_.CheckExplicitInterface(*name);
7537     }
7538   }
7539   bool Pre(const parser::EntityDecl &decl) {
7540     Init(std::get<parser::Name>(decl.t),
7541         std::get<std::optional<parser::Initialization>>(decl.t));
7542     return false;
7543   }
7544   bool Pre(const parser::ComponentDecl &decl) {
7545     Init(std::get<parser::Name>(decl.t),
7546         std::get<std::optional<parser::Initialization>>(decl.t));
7547     return false;
7548   }
7549   bool Pre(const parser::ProcDecl &decl) {
7550     if (const auto &init{
7551             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7552       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7553     }
7554     return false;
7555   }
7556   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7557     resolver_.CheckExplicitInterface(tbps.interfaceName);
7558   }
7559   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7560     if (pushedScope_) {
7561       resolver_.CheckBindings(tbps);
7562     }
7563   }
7564 
7565 private:
7566   void Init(const parser::Name &name,
7567       const std::optional<parser::Initialization> &init) {
7568     if (init) {
7569       if (const auto *target{
7570               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7571         resolver_.PointerInitialization(name, *target);
7572       }
7573     }
7574   }
7575 
7576   ResolveNamesVisitor &resolver_;
7577   bool pushedScope_{false};
7578 };
7579 
7580 // Perform checks and completions that need to happen after all of
7581 // the specification parts but before any of the execution parts.
7582 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7583   if (!node.scope()) {
7584     return; // error occurred creating scope
7585   }
7586   SetScope(*node.scope());
7587   // The initializers of pointers, the default initializers of pointer
7588   // components, and non-deferred type-bound procedure bindings have not
7589   // yet been traversed.
7590   // We do that now, when any (formerly) forward references that appear
7591   // in those initializers will resolve to the right symbols without
7592   // incurring spurious errors with IMPLICIT NONE.
7593   DeferredCheckVisitor{*this}.Walk(node.spec());
7594   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7595   for (Scope &childScope : currScope().children()) {
7596     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7597       FinishDerivedTypeInstantiation(childScope);
7598     }
7599   }
7600   for (const auto &child : node.children()) {
7601     FinishSpecificationParts(child);
7602   }
7603 }
7604 
7605 // Duplicate and fold component object pointer default initializer designators
7606 // using the actual type parameter values of each particular instantiation.
7607 // Validation is done later in declaration checking.
7608 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7609   CHECK(scope.IsDerivedType() && !scope.symbol());
7610   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7611     spec->Instantiate(currScope());
7612     const Symbol &origTypeSymbol{spec->typeSymbol()};
7613     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7614       CHECK(origTypeScope->IsDerivedType() &&
7615           origTypeScope->symbol() == &origTypeSymbol);
7616       auto &foldingContext{GetFoldingContext()};
7617       auto restorer{foldingContext.WithPDTInstance(*spec)};
7618       for (auto &pair : scope) {
7619         Symbol &comp{*pair.second};
7620         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7621         if (IsPointer(comp)) {
7622           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7623             auto origDetails{origComp.get<ObjectEntityDetails>()};
7624             if (const MaybeExpr & init{origDetails.init()}) {
7625               SomeExpr newInit{*init};
7626               MaybeExpr folded{
7627                   evaluate::Fold(foldingContext, std::move(newInit))};
7628               details->set_init(std::move(folded));
7629             }
7630           }
7631         }
7632       }
7633     }
7634   }
7635 }
7636 
7637 // Resolve names in the execution part of this node and its children
7638 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7639   if (!node.scope()) {
7640     return; // error occurred creating scope
7641   }
7642   SetScope(*node.scope());
7643   if (const auto *exec{node.exec()}) {
7644     Walk(*exec);
7645   }
7646   FinishNamelists();
7647   PopScope(); // converts unclassified entities into objects
7648   for (const auto &child : node.children()) {
7649     ResolveExecutionParts(child);
7650   }
7651 }
7652 
7653 void ResolveNamesVisitor::Post(const parser::Program &) {
7654   // ensure that all temps were deallocated
7655   CHECK(!attrs_);
7656   CHECK(!GetDeclTypeSpec());
7657 }
7658 
7659 // A singleton instance of the scope -> IMPLICIT rules mapping is
7660 // shared by all instances of ResolveNamesVisitor and accessed by this
7661 // pointer when the visitors (other than the top-level original) are
7662 // constructed.
7663 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7664 
7665 bool ResolveNames(
7666     SemanticsContext &context, const parser::Program &program, Scope &top) {
7667   ImplicitRulesMap implicitRulesMap;
7668   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7669   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7670   return !context.AnyFatalError();
7671 }
7672 
7673 // Processes a module (but not internal) function when it is referenced
7674 // in a specification expression in a sibling procedure.
7675 void ResolveSpecificationParts(
7676     SemanticsContext &context, const Symbol &subprogram) {
7677   auto originalLocation{context.location()};
7678   ImplicitRulesMap implicitRulesMap;
7679   bool localImplicitRulesMap{false};
7680   if (!sharedImplicitRulesMap) {
7681     sharedImplicitRulesMap = &implicitRulesMap;
7682     localImplicitRulesMap = true;
7683   }
7684   ResolveNamesVisitor visitor{
7685       context, *sharedImplicitRulesMap, context.globalScope()};
7686   const auto &details{subprogram.get<SubprogramNameDetails>()};
7687   ProgramTree &node{details.node()};
7688   const Scope &moduleScope{subprogram.owner()};
7689   if (localImplicitRulesMap) {
7690     visitor.BeginScope(const_cast<Scope &>(moduleScope));
7691   } else {
7692     visitor.SetScope(const_cast<Scope &>(moduleScope));
7693   }
7694   visitor.ResolveSpecificationParts(node);
7695   context.set_location(std::move(originalLocation));
7696   if (localImplicitRulesMap) {
7697     sharedImplicitRulesMap = nullptr;
7698   }
7699 }
7700 
7701 } // namespace Fortran::semantics
7702