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   bool hasBindCName_{false};
1051 
1052   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
1053   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
1054   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
1055   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
1056   void SetType(const parser::Name &, const DeclTypeSpec &);
1057   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
1058   std::optional<DerivedTypeSpec> ResolveExtendsType(
1059       const parser::Name &, const parser::Name *);
1060   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
1061   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1062   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
1063   ParamValue GetParamValue(
1064       const parser::TypeParamValue &, common::TypeParamAttr attr);
1065   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
1066   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
1067   Attrs HandleSaveName(const SourceName &, Attrs);
1068   void AddSaveName(std::set<SourceName> &, const SourceName &);
1069   void SetSaveAttr(Symbol &);
1070   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1071   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1072   void Initialization(const parser::Name &, const parser::Initialization &,
1073       bool inComponentDecl);
1074   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
1075   bool CheckForHostAssociatedImplicit(const parser::Name &);
1076 
1077   // Declare an object or procedure entity.
1078   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1079   template <typename T>
1080   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1081     Symbol &symbol{MakeSymbol(name, attrs)};
1082     if (context().HasError(symbol) || symbol.has<T>()) {
1083       return symbol; // OK or error already reported
1084     } else if (symbol.has<UnknownDetails>()) {
1085       symbol.set_details(T{});
1086       return symbol;
1087     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1088       symbol.set_details(T{std::move(*details)});
1089       return symbol;
1090     } else if (std::is_same_v<EntityDetails, T> &&
1091         (symbol.has<ObjectEntityDetails>() ||
1092             symbol.has<ProcEntityDetails>())) {
1093       return symbol; // OK
1094     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1095       Say(name.source,
1096           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1097           name.source, GetUsedModule(*details).name());
1098     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1099       if (details->kind() == SubprogramKind::Module) {
1100         Say2(name,
1101             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1102             symbol, "Module procedure definition"_en_US);
1103       } else if (details->kind() == SubprogramKind::Internal) {
1104         Say2(name,
1105             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1106             symbol, "Internal procedure definition"_en_US);
1107       } else {
1108         DIE("unexpected kind");
1109       }
1110     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1111         symbol.has<ProcEntityDetails>()) {
1112       SayWithDecl(
1113           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1114     } else if (std::is_same_v<ProcEntityDetails, T> &&
1115         symbol.has<ObjectEntityDetails>()) {
1116       if (InCommonBlock(symbol)) {
1117         SayWithDecl(name, symbol,
1118             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1119       } else {
1120         SayWithDecl(
1121             name, symbol, "'%s' is already declared as an object"_err_en_US);
1122       }
1123     } else if (!CheckPossibleBadForwardRef(symbol)) {
1124       SayAlreadyDeclared(name, symbol);
1125     }
1126     context().SetError(symbol);
1127     return symbol;
1128   }
1129   bool HasCycle(const Symbol &, const ProcInterface &);
1130 };
1131 
1132 // Resolve construct entities and statement entities.
1133 // Check that construct names don't conflict with other names.
1134 class ConstructVisitor : public virtual DeclarationVisitor {
1135 public:
1136   bool Pre(const parser::ConcurrentHeader &);
1137   bool Pre(const parser::LocalitySpec::Local &);
1138   bool Pre(const parser::LocalitySpec::LocalInit &);
1139   bool Pre(const parser::LocalitySpec::Shared &);
1140   bool Pre(const parser::AcSpec &);
1141   bool Pre(const parser::AcImpliedDo &);
1142   bool Pre(const parser::DataImpliedDo &);
1143   bool Pre(const parser::DataIDoObject &);
1144   bool Pre(const parser::DataStmtObject &);
1145   bool Pre(const parser::DataStmtValue &);
1146   bool Pre(const parser::DoConstruct &);
1147   void Post(const parser::DoConstruct &);
1148   bool Pre(const parser::ForallConstruct &);
1149   void Post(const parser::ForallConstruct &);
1150   bool Pre(const parser::ForallStmt &);
1151   void Post(const parser::ForallStmt &);
1152   bool Pre(const parser::BlockStmt &);
1153   bool Pre(const parser::EndBlockStmt &);
1154   void Post(const parser::Selector &);
1155   void Post(const parser::AssociateStmt &);
1156   void Post(const parser::EndAssociateStmt &);
1157   bool Pre(const parser::Association &);
1158   void Post(const parser::SelectTypeStmt &);
1159   void Post(const parser::SelectRankStmt &);
1160   bool Pre(const parser::SelectTypeConstruct &);
1161   void Post(const parser::SelectTypeConstruct &);
1162   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1163   void Post(const parser::SelectTypeConstruct::TypeCase &);
1164   // Creates Block scopes with neither symbol name nor symbol details.
1165   bool Pre(const parser::SelectRankConstruct::RankCase &);
1166   void Post(const parser::SelectRankConstruct::RankCase &);
1167   void Post(const parser::TypeGuardStmt::Guard &);
1168   void Post(const parser::SelectRankCaseStmt::Rank &);
1169   bool Pre(const parser::ChangeTeamStmt &);
1170   void Post(const parser::EndChangeTeamStmt &);
1171   void Post(const parser::CoarrayAssociation &);
1172 
1173   // Definitions of construct names
1174   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1175   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1176   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1177   bool Pre(const parser::LabelDoStmt &) {
1178     return false; // error recovery
1179   }
1180   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1181   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1182   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1183   bool Pre(const parser::SelectRankConstruct &);
1184   void Post(const parser::SelectRankConstruct &);
1185   bool Pre(const parser::SelectRankStmt &x) {
1186     return CheckDef(std::get<0>(x.t));
1187   }
1188   bool Pre(const parser::SelectTypeStmt &x) {
1189     return CheckDef(std::get<0>(x.t));
1190   }
1191 
1192   // References to construct names
1193   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1194   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1195   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1196   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1197   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1198   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1199   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1200   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1201   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1202   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1203   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1204   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1205   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1206   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1207   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1208 
1209 private:
1210   // R1105 selector -> expr | variable
1211   // expr is set in either case unless there were errors
1212   struct Selector {
1213     Selector() {}
1214     Selector(const SourceName &source, MaybeExpr &&expr)
1215         : source{source}, expr{std::move(expr)} {}
1216     operator bool() const { return expr.has_value(); }
1217     parser::CharBlock source;
1218     MaybeExpr expr;
1219   };
1220   // association -> [associate-name =>] selector
1221   struct Association {
1222     const parser::Name *name{nullptr};
1223     Selector selector;
1224   };
1225   std::vector<Association> associationStack_;
1226   Association *currentAssociation_{nullptr};
1227 
1228   template <typename T> bool CheckDef(const T &t) {
1229     return CheckDef(std::get<std::optional<parser::Name>>(t));
1230   }
1231   template <typename T> void CheckRef(const T &t) {
1232     CheckRef(std::get<std::optional<parser::Name>>(t));
1233   }
1234   bool CheckDef(const std::optional<parser::Name> &);
1235   void CheckRef(const std::optional<parser::Name> &);
1236   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1237   const DeclTypeSpec &ToDeclTypeSpec(
1238       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1239   Symbol *MakeAssocEntity();
1240   void SetTypeFromAssociation(Symbol &);
1241   void SetAttrsFromAssociation(Symbol &);
1242   Selector ResolveSelector(const parser::Selector &);
1243   void ResolveIndexName(const parser::ConcurrentControl &control);
1244   void SetCurrentAssociation(std::size_t n);
1245   Association &GetCurrentAssociation();
1246   void PushAssociation();
1247   void PopAssociation(std::size_t count = 1);
1248 };
1249 
1250 // Create scopes for OpenACC constructs
1251 class AccVisitor : public virtual DeclarationVisitor {
1252 public:
1253   void AddAccSourceRange(const parser::CharBlock &);
1254 
1255   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1256 
1257   bool Pre(const parser::OpenACCBlockConstruct &);
1258   void Post(const parser::OpenACCBlockConstruct &);
1259   bool Pre(const parser::AccBeginBlockDirective &x) {
1260     AddAccSourceRange(x.source);
1261     return true;
1262   }
1263   void Post(const parser::AccBeginBlockDirective &) {
1264     messageHandler().set_currStmtSource(std::nullopt);
1265   }
1266   bool Pre(const parser::AccEndBlockDirective &x) {
1267     AddAccSourceRange(x.source);
1268     return true;
1269   }
1270   void Post(const parser::AccEndBlockDirective &) {
1271     messageHandler().set_currStmtSource(std::nullopt);
1272   }
1273   bool Pre(const parser::AccBeginLoopDirective &x) {
1274     AddAccSourceRange(x.source);
1275     return true;
1276   }
1277   void Post(const parser::AccBeginLoopDirective &x) {
1278     messageHandler().set_currStmtSource(std::nullopt);
1279   }
1280 };
1281 
1282 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1283   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1284   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1285   switch (beginDir.v) {
1286   case llvm::acc::Directive::ACCD_data:
1287   case llvm::acc::Directive::ACCD_host_data:
1288   case llvm::acc::Directive::ACCD_kernels:
1289   case llvm::acc::Directive::ACCD_parallel:
1290   case llvm::acc::Directive::ACCD_serial:
1291     return true;
1292   default:
1293     return false;
1294   }
1295 }
1296 
1297 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1298   messageHandler().set_currStmtSource(source);
1299   currScope().AddSourceRange(source);
1300 }
1301 
1302 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1303   if (NeedsScope(x)) {
1304     PushScope(Scope::Kind::Block, nullptr);
1305   }
1306   return true;
1307 }
1308 
1309 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1310   if (NeedsScope(x)) {
1311     PopScope();
1312   }
1313 }
1314 
1315 // Create scopes for OpenMP constructs
1316 class OmpVisitor : public virtual DeclarationVisitor {
1317 public:
1318   void AddOmpSourceRange(const parser::CharBlock &);
1319 
1320   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1321 
1322   bool Pre(const parser::OpenMPBlockConstruct &);
1323   void Post(const parser::OpenMPBlockConstruct &);
1324   bool Pre(const parser::OmpBeginBlockDirective &x) {
1325     AddOmpSourceRange(x.source);
1326     return true;
1327   }
1328   void Post(const parser::OmpBeginBlockDirective &) {
1329     messageHandler().set_currStmtSource(std::nullopt);
1330   }
1331   bool Pre(const parser::OmpEndBlockDirective &x) {
1332     AddOmpSourceRange(x.source);
1333     return true;
1334   }
1335   void Post(const parser::OmpEndBlockDirective &) {
1336     messageHandler().set_currStmtSource(std::nullopt);
1337   }
1338 
1339   bool Pre(const parser::OpenMPLoopConstruct &) {
1340     PushScope(Scope::Kind::Block, nullptr);
1341     return true;
1342   }
1343   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1344   bool Pre(const parser::OmpBeginLoopDirective &x) {
1345     AddOmpSourceRange(x.source);
1346     return true;
1347   }
1348   void Post(const parser::OmpBeginLoopDirective &) {
1349     messageHandler().set_currStmtSource(std::nullopt);
1350   }
1351   bool Pre(const parser::OmpEndLoopDirective &x) {
1352     AddOmpSourceRange(x.source);
1353     return true;
1354   }
1355   void Post(const parser::OmpEndLoopDirective &) {
1356     messageHandler().set_currStmtSource(std::nullopt);
1357   }
1358 
1359   bool Pre(const parser::OpenMPSectionsConstruct &) {
1360     PushScope(Scope::Kind::Block, nullptr);
1361     return true;
1362   }
1363   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1364   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1365     AddOmpSourceRange(x.source);
1366     return true;
1367   }
1368   void Post(const parser::OmpBeginSectionsDirective &) {
1369     messageHandler().set_currStmtSource(std::nullopt);
1370   }
1371   bool Pre(const parser::OmpEndSectionsDirective &x) {
1372     AddOmpSourceRange(x.source);
1373     return true;
1374   }
1375   void Post(const parser::OmpEndSectionsDirective &) {
1376     messageHandler().set_currStmtSource(std::nullopt);
1377   }
1378 };
1379 
1380 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1381   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1382   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1383   switch (beginDir.v) {
1384   case llvm::omp::Directive::OMPD_target_data:
1385   case llvm::omp::Directive::OMPD_master:
1386   case llvm::omp::Directive::OMPD_ordered:
1387   case llvm::omp::Directive::OMPD_taskgroup:
1388     return false;
1389   default:
1390     return true;
1391   }
1392 }
1393 
1394 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1395   messageHandler().set_currStmtSource(source);
1396   currScope().AddSourceRange(source);
1397 }
1398 
1399 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1400   if (NeedsScope(x)) {
1401     PushScope(Scope::Kind::Block, nullptr);
1402   }
1403   return true;
1404 }
1405 
1406 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1407   if (NeedsScope(x)) {
1408     PopScope();
1409   }
1410 }
1411 
1412 // Walk the parse tree and resolve names to symbols.
1413 class ResolveNamesVisitor : public virtual ScopeHandler,
1414                             public ModuleVisitor,
1415                             public SubprogramVisitor,
1416                             public ConstructVisitor,
1417                             public OmpVisitor,
1418                             public AccVisitor {
1419 public:
1420   using AccVisitor::Post;
1421   using AccVisitor::Pre;
1422   using ArraySpecVisitor::Post;
1423   using ConstructVisitor::Post;
1424   using ConstructVisitor::Pre;
1425   using DeclarationVisitor::Post;
1426   using DeclarationVisitor::Pre;
1427   using ImplicitRulesVisitor::Post;
1428   using ImplicitRulesVisitor::Pre;
1429   using InterfaceVisitor::Post;
1430   using InterfaceVisitor::Pre;
1431   using ModuleVisitor::Post;
1432   using ModuleVisitor::Pre;
1433   using OmpVisitor::Post;
1434   using OmpVisitor::Pre;
1435   using ScopeHandler::Post;
1436   using ScopeHandler::Pre;
1437   using SubprogramVisitor::Post;
1438   using SubprogramVisitor::Pre;
1439 
1440   ResolveNamesVisitor(
1441       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1442       : BaseVisitor{context, *this, rules}, topScope_{top} {
1443     PushScope(top);
1444   }
1445 
1446   Scope &topScope() const { return topScope_; }
1447 
1448   // Default action for a parse tree node is to visit children.
1449   template <typename T> bool Pre(const T &) { return true; }
1450   template <typename T> void Post(const T &) {}
1451 
1452   bool Pre(const parser::SpecificationPart &);
1453   void Post(const parser::Program &);
1454   bool Pre(const parser::ImplicitStmt &);
1455   void Post(const parser::PointerObject &);
1456   void Post(const parser::AllocateObject &);
1457   bool Pre(const parser::PointerAssignmentStmt &);
1458   void Post(const parser::Designator &);
1459   template <typename A, typename B>
1460   void Post(const parser::LoopBounds<A, B> &x) {
1461     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1462   }
1463   void Post(const parser::ProcComponentRef &);
1464   bool Pre(const parser::FunctionReference &);
1465   bool Pre(const parser::CallStmt &);
1466   bool Pre(const parser::ImportStmt &);
1467   void Post(const parser::TypeGuardStmt &);
1468   bool Pre(const parser::StmtFunctionStmt &);
1469   bool Pre(const parser::DefinedOpName &);
1470   bool Pre(const parser::ProgramUnit &);
1471   void Post(const parser::AssignStmt &);
1472   void Post(const parser::AssignedGotoStmt &);
1473 
1474   // These nodes should never be reached: they are handled in ProgramUnit
1475   bool Pre(const parser::MainProgram &) {
1476     llvm_unreachable("This node is handled in ProgramUnit");
1477   }
1478   bool Pre(const parser::FunctionSubprogram &) {
1479     llvm_unreachable("This node is handled in ProgramUnit");
1480   }
1481   bool Pre(const parser::SubroutineSubprogram &) {
1482     llvm_unreachable("This node is handled in ProgramUnit");
1483   }
1484   bool Pre(const parser::SeparateModuleSubprogram &) {
1485     llvm_unreachable("This node is handled in ProgramUnit");
1486   }
1487   bool Pre(const parser::Module &) {
1488     llvm_unreachable("This node is handled in ProgramUnit");
1489   }
1490   bool Pre(const parser::Submodule &) {
1491     llvm_unreachable("This node is handled in ProgramUnit");
1492   }
1493   bool Pre(const parser::BlockData &) {
1494     llvm_unreachable("This node is handled in ProgramUnit");
1495   }
1496 
1497   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1498 
1499   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1500 
1501 private:
1502   // Kind of procedure we are expecting to see in a ProcedureDesignator
1503   std::optional<Symbol::Flag> expectedProcFlag_;
1504   std::optional<SourceName> prevImportStmt_;
1505   Scope &topScope_;
1506 
1507   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1508   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1509   void CreateGeneric(const parser::GenericSpec &);
1510   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1511   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1512   void CheckImports();
1513   void CheckImport(const SourceName &, const SourceName &);
1514   void HandleCall(Symbol::Flag, const parser::Call &);
1515   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1516   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1517   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1518   void ResolveSpecificationParts(ProgramTree &);
1519   void AddSubpNames(ProgramTree &);
1520   bool BeginScopeForNode(const ProgramTree &);
1521   void EndScopeForNode(const ProgramTree &);
1522   void FinishSpecificationParts(const ProgramTree &);
1523   void FinishDerivedTypeInstantiation(Scope &);
1524   void ResolveExecutionParts(const ProgramTree &);
1525 };
1526 
1527 // ImplicitRules implementation
1528 
1529 bool ImplicitRules::isImplicitNoneType() const {
1530   if (isImplicitNoneType_) {
1531     return true;
1532   } else if (map_.empty() && inheritFromParent_) {
1533     return parent_->isImplicitNoneType();
1534   } else {
1535     return false; // default if not specified
1536   }
1537 }
1538 
1539 bool ImplicitRules::isImplicitNoneExternal() const {
1540   if (isImplicitNoneExternal_) {
1541     return true;
1542   } else if (inheritFromParent_) {
1543     return parent_->isImplicitNoneExternal();
1544   } else {
1545     return false; // default if not specified
1546   }
1547 }
1548 
1549 const DeclTypeSpec *ImplicitRules::GetType(
1550     SourceName name, bool respectImplicitNoneType) const {
1551   char ch{name.begin()[0]};
1552   if (isImplicitNoneType_ && respectImplicitNoneType) {
1553     return nullptr;
1554   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1555     return &*it->second;
1556   } else if (inheritFromParent_) {
1557     return parent_->GetType(name, respectImplicitNoneType);
1558   } else if (ch >= 'i' && ch <= 'n') {
1559     return &context_.MakeNumericType(TypeCategory::Integer);
1560   } else if (ch >= 'a' && ch <= 'z') {
1561     return &context_.MakeNumericType(TypeCategory::Real);
1562   } else {
1563     return nullptr;
1564   }
1565 }
1566 
1567 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1568     parser::Location fromLetter, parser::Location toLetter) {
1569   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1570     auto res{map_.emplace(ch, type)};
1571     if (!res.second) {
1572       context_.Say(parser::CharBlock{fromLetter},
1573           "More than one implicit type specified for '%c'"_err_en_US, ch);
1574     }
1575     if (ch == *toLetter) {
1576       break;
1577     }
1578   }
1579 }
1580 
1581 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1582 // Return '\0' for the char after 'z'.
1583 char ImplicitRules::Incr(char ch) {
1584   switch (ch) {
1585   case 'i':
1586     return 'j';
1587   case 'r':
1588     return 's';
1589   case 'z':
1590     return '\0';
1591   default:
1592     return ch + 1;
1593   }
1594 }
1595 
1596 llvm::raw_ostream &operator<<(
1597     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1598   o << "ImplicitRules:\n";
1599   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1600     ShowImplicitRule(o, implicitRules, ch);
1601   }
1602   ShowImplicitRule(o, implicitRules, '_');
1603   ShowImplicitRule(o, implicitRules, '$');
1604   ShowImplicitRule(o, implicitRules, '@');
1605   return o;
1606 }
1607 void ShowImplicitRule(
1608     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1609   auto it{implicitRules.map_.find(ch)};
1610   if (it != implicitRules.map_.end()) {
1611     o << "  " << ch << ": " << *it->second << '\n';
1612   }
1613 }
1614 
1615 template <typename T> void BaseVisitor::Walk(const T &x) {
1616   parser::Walk(x, *this_);
1617 }
1618 
1619 void BaseVisitor::MakePlaceholder(
1620     const parser::Name &name, MiscDetails::Kind kind) {
1621   if (!name.symbol) {
1622     name.symbol = &context_->globalScope().MakeSymbol(
1623         name.source, Attrs{}, MiscDetails{kind});
1624   }
1625 }
1626 
1627 // AttrsVisitor implementation
1628 
1629 bool AttrsVisitor::BeginAttrs() {
1630   CHECK(!attrs_);
1631   attrs_ = std::make_optional<Attrs>();
1632   return true;
1633 }
1634 Attrs AttrsVisitor::GetAttrs() {
1635   CHECK(attrs_);
1636   return *attrs_;
1637 }
1638 Attrs AttrsVisitor::EndAttrs() {
1639   Attrs result{GetAttrs()};
1640   attrs_.reset();
1641   passName_ = std::nullopt;
1642   bindName_.reset();
1643   return result;
1644 }
1645 
1646 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1647   if (!passName_) {
1648     return false;
1649   }
1650   common::visit(common::visitors{
1651                     [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1652                     [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1653                     [](auto &) { common::die("unexpected pass name"); },
1654                 },
1655       symbol.details());
1656   return true;
1657 }
1658 
1659 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1660   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1661     return;
1662   }
1663   std::optional<std::string> label{
1664       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1665   if (ClassifyProcedure(symbol) == ProcedureDefinitionClass::Internal) {
1666     if (label) { // C1552: no NAME= allowed even if null
1667       Say(symbol.name(),
1668           "An internal procedure may not have a BIND(C,NAME=) binding label"_err_en_US);
1669     }
1670     return;
1671   }
1672   // 18.9.2(2): discard leading and trailing blanks
1673   if (label) {
1674     auto first{label->find_first_not_of(" ")};
1675     if (first == std::string::npos) {
1676       // Empty NAME= means no binding at all (18.10.2p2)
1677       return;
1678     }
1679     auto last{label->find_last_not_of(" ")};
1680     label = label->substr(first, last - first + 1);
1681   } else {
1682     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1683   }
1684   // Check if a symbol has two Bind names.
1685   std::string oldBindName;
1686   if (symbol.GetBindName()) {
1687     oldBindName = *symbol.GetBindName();
1688   }
1689   symbol.SetBindName(std::move(*label));
1690   if (!oldBindName.empty()) {
1691     if (const std::string * newBindName{symbol.GetBindName()}) {
1692       if (oldBindName.compare(*newBindName) != 0) {
1693         Say(symbol.name(), "The entity '%s' has multiple BIND names"_err_en_US);
1694       }
1695     }
1696   }
1697 }
1698 
1699 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1700   CHECK(attrs_);
1701   if (CheckAndSet(Attr::BIND_C)) {
1702     if (x.v) {
1703       bindName_ = EvaluateExpr(*x.v);
1704     }
1705   }
1706 }
1707 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1708   CHECK(attrs_);
1709   CheckAndSet(IntentSpecToAttr(x));
1710   return false;
1711 }
1712 bool AttrsVisitor::Pre(const parser::Pass &x) {
1713   if (CheckAndSet(Attr::PASS)) {
1714     if (x.v) {
1715       passName_ = x.v->source;
1716       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1717     }
1718   }
1719   return false;
1720 }
1721 
1722 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1723 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1724   if (attrs_->test(attrName)) {
1725     Say(currStmtSource().value(),
1726         "Attribute '%s' cannot be used more than once"_warn_en_US,
1727         AttrToString(attrName));
1728     return true;
1729   }
1730   return false;
1731 }
1732 
1733 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1734 // name attributes that cannot be used on the same declaration
1735 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1736   if ((attrName == attr1 && attrs_->test(attr2)) ||
1737       (attrName == attr2 && attrs_->test(attr1))) {
1738     Say(currStmtSource().value(),
1739         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1740         AttrToString(attr1), AttrToString(attr2));
1741     return true;
1742   }
1743   return false;
1744 }
1745 // C759, C1543
1746 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1747   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1748       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1749       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1750       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1751       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1752       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1753       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1754 }
1755 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1756   CHECK(attrs_);
1757   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1758     return false;
1759   }
1760   attrs_->set(attrName);
1761   return true;
1762 }
1763 
1764 // DeclTypeSpecVisitor implementation
1765 
1766 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1767   return state_.declTypeSpec;
1768 }
1769 
1770 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1771   CHECK(!state_.expectDeclTypeSpec);
1772   CHECK(!state_.declTypeSpec);
1773   state_.expectDeclTypeSpec = true;
1774 }
1775 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1776   CHECK(state_.expectDeclTypeSpec);
1777   state_ = {};
1778 }
1779 
1780 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1781     DeclTypeSpec::Category category) {
1782   CHECK(state_.expectDeclTypeSpec);
1783   state_.derived.category = category;
1784 }
1785 
1786 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1787   BeginDeclTypeSpec();
1788   return true;
1789 }
1790 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1791   EndDeclTypeSpec();
1792 }
1793 
1794 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1795   // Record the resolved DeclTypeSpec in the parse tree for use by
1796   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1797   // The grammar ensures that it's an intrinsic or derived type spec,
1798   // not TYPE(*) or CLASS(*) or CLASS(T).
1799   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1800     switch (spec->category()) {
1801     case DeclTypeSpec::Numeric:
1802     case DeclTypeSpec::Logical:
1803     case DeclTypeSpec::Character:
1804       typeSpec.declTypeSpec = spec;
1805       break;
1806     case DeclTypeSpec::TypeDerived:
1807       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1808         CheckForAbstractType(derived->typeSymbol()); // C703
1809         typeSpec.declTypeSpec = spec;
1810       }
1811       break;
1812     default:
1813       CRASH_NO_CASE;
1814     }
1815   }
1816 }
1817 
1818 void DeclTypeSpecVisitor::Post(
1819     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1820   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1821 }
1822 void DeclTypeSpecVisitor::Post(
1823     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1824   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1825 }
1826 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1827   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1828 }
1829 
1830 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1831   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1832     Say("ABSTRACT derived type may not be used here"_err_en_US);
1833   }
1834 }
1835 
1836 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1837   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1838 }
1839 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1840   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1841 }
1842 
1843 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1844 // and save it in state_.declTypeSpec.
1845 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1846   CHECK(state_.expectDeclTypeSpec);
1847   CHECK(!state_.declTypeSpec);
1848   state_.declTypeSpec = &declTypeSpec;
1849 }
1850 
1851 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1852     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1853   return AnalyzeKindSelector(context(), category, kind);
1854 }
1855 
1856 // MessageHandler implementation
1857 
1858 Message &MessageHandler::Say(MessageFixedText &&msg) {
1859   return context_->Say(currStmtSource().value(), std::move(msg));
1860 }
1861 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1862   return context_->Say(currStmtSource().value(), std::move(msg));
1863 }
1864 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1865   return Say(name, std::move(msg), name);
1866 }
1867 
1868 // ImplicitRulesVisitor implementation
1869 
1870 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1871   prevParameterStmt_ = currStmtSource();
1872 }
1873 
1874 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1875   bool result{
1876       common::visit(common::visitors{
1877                         [&](const std::list<ImplicitNoneNameSpec> &y) {
1878                           return HandleImplicitNone(y);
1879                         },
1880                         [&](const std::list<parser::ImplicitSpec> &) {
1881                           if (prevImplicitNoneType_) {
1882                             Say("IMPLICIT statement after IMPLICIT NONE or "
1883                                 "IMPLICIT NONE(TYPE) statement"_err_en_US);
1884                             return false;
1885                           }
1886                           implicitRules_->set_isImplicitNoneType(false);
1887                           return true;
1888                         },
1889                     },
1890           x.u)};
1891   prevImplicit_ = currStmtSource();
1892   return result;
1893 }
1894 
1895 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1896   auto loLoc{std::get<parser::Location>(x.t)};
1897   auto hiLoc{loLoc};
1898   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1899     hiLoc = *hiLocOpt;
1900     if (*hiLoc < *loLoc) {
1901       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1902           std::string(hiLoc, 1), std::string(loLoc, 1));
1903       return false;
1904     }
1905   }
1906   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1907   return false;
1908 }
1909 
1910 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1911   BeginDeclTypeSpec();
1912   set_allowForwardReferenceToDerivedType(true);
1913   return true;
1914 }
1915 
1916 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1917   EndDeclTypeSpec();
1918 }
1919 
1920 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1921   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1922   prevImplicit_ = std::nullopt;
1923   prevImplicitNone_ = std::nullopt;
1924   prevImplicitNoneType_ = std::nullopt;
1925   prevParameterStmt_ = std::nullopt;
1926 }
1927 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1928   // find or create implicit rules for this scope
1929   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1930   SetScope(scope);
1931 }
1932 
1933 // TODO: for all of these errors, reference previous statement too
1934 bool ImplicitRulesVisitor::HandleImplicitNone(
1935     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1936   if (prevImplicitNone_) {
1937     Say("More than one IMPLICIT NONE statement"_err_en_US);
1938     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1939     return false;
1940   }
1941   if (prevParameterStmt_) {
1942     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1943     return false;
1944   }
1945   prevImplicitNone_ = currStmtSource();
1946   bool implicitNoneTypeNever{
1947       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1948   if (nameSpecs.empty()) {
1949     if (!implicitNoneTypeNever) {
1950       prevImplicitNoneType_ = currStmtSource();
1951       implicitRules_->set_isImplicitNoneType(true);
1952       if (prevImplicit_) {
1953         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1954         return false;
1955       }
1956     }
1957   } else {
1958     int sawType{0};
1959     int sawExternal{0};
1960     for (const auto noneSpec : nameSpecs) {
1961       switch (noneSpec) {
1962       case ImplicitNoneNameSpec::External:
1963         implicitRules_->set_isImplicitNoneExternal(true);
1964         ++sawExternal;
1965         break;
1966       case ImplicitNoneNameSpec::Type:
1967         if (!implicitNoneTypeNever) {
1968           prevImplicitNoneType_ = currStmtSource();
1969           implicitRules_->set_isImplicitNoneType(true);
1970           if (prevImplicit_) {
1971             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1972             return false;
1973           }
1974           ++sawType;
1975         }
1976         break;
1977       }
1978     }
1979     if (sawType > 1) {
1980       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1981       return false;
1982     }
1983     if (sawExternal > 1) {
1984       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1985       return false;
1986     }
1987   }
1988   return true;
1989 }
1990 
1991 // ArraySpecVisitor implementation
1992 
1993 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1994   CHECK(arraySpec_.empty());
1995   arraySpec_ = AnalyzeArraySpec(context(), x);
1996 }
1997 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1998   CHECK(arraySpec_.empty());
1999   arraySpec_ = AnalyzeArraySpec(context(), x);
2000 }
2001 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
2002   CHECK(coarraySpec_.empty());
2003   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
2004 }
2005 
2006 const ArraySpec &ArraySpecVisitor::arraySpec() {
2007   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
2008 }
2009 const ArraySpec &ArraySpecVisitor::coarraySpec() {
2010   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
2011 }
2012 void ArraySpecVisitor::BeginArraySpec() {
2013   CHECK(arraySpec_.empty());
2014   CHECK(coarraySpec_.empty());
2015   CHECK(attrArraySpec_.empty());
2016   CHECK(attrCoarraySpec_.empty());
2017 }
2018 void ArraySpecVisitor::EndArraySpec() {
2019   CHECK(arraySpec_.empty());
2020   CHECK(coarraySpec_.empty());
2021   attrArraySpec_.clear();
2022   attrCoarraySpec_.clear();
2023 }
2024 void ArraySpecVisitor::PostAttrSpec() {
2025   // Save dimension/codimension from attrs so we can process array/coarray-spec
2026   // on the entity-decl
2027   if (!arraySpec_.empty()) {
2028     if (attrArraySpec_.empty()) {
2029       attrArraySpec_ = arraySpec_;
2030       arraySpec_.clear();
2031     } else {
2032       Say(currStmtSource().value(),
2033           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
2034     }
2035   }
2036   if (!coarraySpec_.empty()) {
2037     if (attrCoarraySpec_.empty()) {
2038       attrCoarraySpec_ = coarraySpec_;
2039       coarraySpec_.clear();
2040     } else {
2041       Say(currStmtSource().value(),
2042           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
2043     }
2044   }
2045 }
2046 
2047 // FuncResultStack implementation
2048 
2049 FuncResultStack::~FuncResultStack() { CHECK(stack_.empty()); }
2050 
2051 void FuncResultStack::CompleteFunctionResultType() {
2052   // If the function has a type in the prefix, process it now.
2053   FuncInfo *info{Top()};
2054   if (info && &info->scope == &scopeHandler_.currScope()) {
2055     if (info->parsedType) {
2056       scopeHandler_.messageHandler().set_currStmtSource(info->source);
2057       if (const auto *type{
2058               scopeHandler_.ProcessTypeSpec(*info->parsedType, true)}) {
2059         if (!scopeHandler_.context().HasError(info->resultSymbol)) {
2060           info->resultSymbol->SetType(*type);
2061         }
2062       }
2063       info->parsedType = nullptr;
2064     }
2065   }
2066 }
2067 
2068 // Called from ConvertTo{Object/Proc}Entity to cope with any appearance
2069 // of the function result in a specification expression.
2070 void FuncResultStack::CompleteTypeIfFunctionResult(Symbol &symbol) {
2071   if (FuncInfo * info{Top()}) {
2072     if (info->resultSymbol == &symbol) {
2073       CompleteFunctionResultType();
2074     }
2075   }
2076 }
2077 
2078 void FuncResultStack::Pop() {
2079   if (!stack_.empty() && &stack_.back().scope == &scopeHandler_.currScope()) {
2080     stack_.pop_back();
2081   }
2082 }
2083 
2084 // ScopeHandler implementation
2085 
2086 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
2087   SayAlreadyDeclared(name.source, prev);
2088 }
2089 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
2090   if (context().HasError(prev)) {
2091     // don't report another error about prev
2092   } else {
2093     if (const auto *details{prev.detailsIf<UseDetails>()}) {
2094       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
2095           .Attach(details->location(),
2096               "It is use-associated with '%s' in module '%s'"_en_US,
2097               details->symbol().name(), GetUsedModule(*details).name());
2098     } else {
2099       SayAlreadyDeclared(name, prev.name());
2100     }
2101     context().SetError(prev);
2102   }
2103 }
2104 void ScopeHandler::SayAlreadyDeclared(
2105     const SourceName &name1, const SourceName &name2) {
2106   if (name1.begin() < name2.begin()) {
2107     SayAlreadyDeclared(name2, name1);
2108   } else {
2109     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
2110         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
2111   }
2112 }
2113 
2114 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
2115     MessageFixedText &&msg1, Message &&msg2) {
2116   Say(name, std::move(msg1), symbol.name()).Attach(std::move(msg2));
2117   context().SetError(symbol, msg1.isFatal());
2118 }
2119 
2120 void ScopeHandler::SayWithDecl(
2121     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
2122   Say(name, std::move(msg), symbol.name())
2123       .Attach(Message{name.source,
2124           symbol.test(Symbol::Flag::Implicit)
2125               ? "Implicit declaration of '%s'"_en_US
2126               : "Declaration of '%s'"_en_US,
2127           name.source});
2128   context().SetError(symbol, msg.isFatal());
2129 }
2130 
2131 void ScopeHandler::SayLocalMustBeVariable(
2132     const parser::Name &name, Symbol &symbol) {
2133   SayWithDecl(name, symbol,
2134       "The name '%s' must be a variable to appear"
2135       " in a locality-spec"_err_en_US);
2136 }
2137 
2138 void ScopeHandler::SayDerivedType(
2139     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2140   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2141   Say(name, std::move(msg), name, typeSymbol.name())
2142       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2143           typeSymbol.name());
2144 }
2145 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2146     const SourceName &name2, MessageFixedText &&msg2) {
2147   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2148 }
2149 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2150     Symbol &symbol, MessageFixedText &&msg2) {
2151   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2152   context().SetError(symbol, msg1.isFatal());
2153 }
2154 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2155     Symbol &symbol, MessageFixedText &&msg2) {
2156   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2157   context().SetError(symbol, msg1.isFatal());
2158 }
2159 
2160 // This is essentially GetProgramUnitContaining(), but it can return
2161 // a mutable Scope &, it ignores statement functions, and it fails
2162 // gracefully for error recovery (returning the original Scope).
2163 template <typename T> static T &GetInclusiveScope(T &scope) {
2164   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2165     switch (s->kind()) {
2166     case Scope::Kind::Module:
2167     case Scope::Kind::MainProgram:
2168     case Scope::Kind::Subprogram:
2169     case Scope::Kind::BlockData:
2170       if (!s->IsStmtFunction()) {
2171         return *s;
2172       }
2173       break;
2174     default:;
2175     }
2176   }
2177   return scope;
2178 }
2179 
2180 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2181 
2182 Scope *ScopeHandler::GetHostProcedure() {
2183   Scope &parent{InclusiveScope().parent()};
2184   switch (parent.kind()) {
2185   case Scope::Kind::Subprogram:
2186     return &parent;
2187   case Scope::Kind::MainProgram:
2188     return &parent;
2189   default:
2190     return nullptr;
2191   }
2192 }
2193 
2194 Scope &ScopeHandler::NonDerivedTypeScope() {
2195   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2196 }
2197 
2198 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2199   PushScope(currScope().MakeScope(kind, symbol));
2200 }
2201 void ScopeHandler::PushScope(Scope &scope) {
2202   currScope_ = &scope;
2203   auto kind{currScope_->kind()};
2204   if (kind != Scope::Kind::Block) {
2205     BeginScope(scope);
2206   }
2207   // The name of a module or submodule cannot be "used" in its scope,
2208   // as we read 19.3.1(2), so we allow the name to be used as a local
2209   // identifier in the module or submodule too.  Same with programs
2210   // (14.1(3)) and BLOCK DATA.
2211   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2212       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2213     if (auto *symbol{scope.symbol()}) {
2214       // Create a dummy symbol so we can't create another one with the same
2215       // name. It might already be there if we previously pushed the scope.
2216       SourceName name{symbol->name()};
2217       if (!FindInScope(scope, name)) {
2218         auto &newSymbol{MakeSymbol(name)};
2219         if (kind == Scope::Kind::Subprogram) {
2220           // Allow for recursive references.  If this symbol is a function
2221           // without an explicit RESULT(), this new symbol will be discarded
2222           // and replaced with an object of the same name.
2223           newSymbol.set_details(HostAssocDetails{*symbol});
2224         } else {
2225           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2226         }
2227       }
2228     }
2229   }
2230 }
2231 void ScopeHandler::PopScope() {
2232   // Entities that are not yet classified as objects or procedures are now
2233   // assumed to be objects.
2234   // TODO: Statement functions
2235   for (auto &pair : currScope()) {
2236     ConvertToObjectEntity(*pair.second);
2237   }
2238   funcResultStack_.Pop();
2239   // If popping back into a global scope, pop back to the main global scope.
2240   SetScope(currScope_->parent().IsGlobal() ? context().globalScope()
2241                                            : currScope_->parent());
2242 }
2243 void ScopeHandler::SetScope(Scope &scope) {
2244   currScope_ = &scope;
2245   ImplicitRulesVisitor::SetScope(InclusiveScope());
2246 }
2247 
2248 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2249   return FindSymbol(currScope(), name);
2250 }
2251 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2252   if (scope.IsDerivedType()) {
2253     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2254       if (!symbol->has<ProcBindingDetails>() &&
2255           !symbol->test(Symbol::Flag::ParentComp)) {
2256         return Resolve(name, symbol);
2257       }
2258     }
2259     return FindSymbol(scope.parent(), name);
2260   } else {
2261     // In EQUIVALENCE statements only resolve names in the local scope, see
2262     // 19.5.1.4, paragraph 2, item (10)
2263     return Resolve(name,
2264         inEquivalenceStmt_ ? FindInScope(scope, name)
2265                            : scope.FindSymbol(name.source));
2266   }
2267 }
2268 
2269 Symbol &ScopeHandler::MakeSymbol(
2270     Scope &scope, const SourceName &name, Attrs attrs) {
2271   if (Symbol * symbol{FindInScope(scope, name)}) {
2272     symbol->attrs() |= attrs;
2273     return *symbol;
2274   } else {
2275     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2276     CHECK(pair.second); // name was not found, so must be able to add
2277     return *pair.first->second;
2278   }
2279 }
2280 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2281   return MakeSymbol(currScope(), name, attrs);
2282 }
2283 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2284   return Resolve(name, MakeSymbol(name.source, attrs));
2285 }
2286 Symbol &ScopeHandler::MakeHostAssocSymbol(
2287     const parser::Name &name, const Symbol &hostSymbol) {
2288   Symbol &symbol{*NonDerivedTypeScope()
2289                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2290                       .first->second};
2291   name.symbol = &symbol;
2292   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2293   symbol.flags() = hostSymbol.flags();
2294   return symbol;
2295 }
2296 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2297   CHECK(!FindInScope(name));
2298   return MakeSymbol(currScope(), name, symbol.attrs());
2299 }
2300 
2301 // Look for name only in scope, not in enclosing scopes.
2302 Symbol *ScopeHandler::FindInScope(
2303     const Scope &scope, const parser::Name &name) {
2304   return Resolve(name, FindInScope(scope, name.source));
2305 }
2306 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2307   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2308   for (const std::string &n : GetAllNames(context(), name)) {
2309     auto it{scope.find(SourceName{n})};
2310     if (it != scope.end()) {
2311       return &*it->second;
2312     }
2313   }
2314   return nullptr;
2315 }
2316 
2317 // Find a component or type parameter by name in a derived type or its parents.
2318 Symbol *ScopeHandler::FindInTypeOrParents(
2319     const Scope &scope, const parser::Name &name) {
2320   return Resolve(name, scope.FindComponent(name.source));
2321 }
2322 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2323   return FindInTypeOrParents(currScope(), name);
2324 }
2325 
2326 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2327   currScope().erase(name.source);
2328   name.symbol = nullptr;
2329 }
2330 
2331 static bool NeedsType(const Symbol &symbol) {
2332   return !symbol.GetType() &&
2333       common::visit(common::visitors{
2334                         [](const EntityDetails &) { return true; },
2335                         [](const ObjectEntityDetails &) { return true; },
2336                         [](const AssocEntityDetails &) { return true; },
2337                         [&](const ProcEntityDetails &p) {
2338                           return symbol.test(Symbol::Flag::Function) &&
2339                               !symbol.attrs().test(Attr::INTRINSIC) &&
2340                               !p.interface().type() && !p.interface().symbol();
2341                         },
2342                         [](const auto &) { return false; },
2343                     },
2344           symbol.details());
2345 }
2346 
2347 void ScopeHandler::ApplyImplicitRules(
2348     Symbol &symbol, bool allowForwardReference) {
2349   funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2350   if (context().HasError(symbol) || !NeedsType(symbol)) {
2351     return;
2352   }
2353   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2354     symbol.set(Symbol::Flag::Implicit);
2355     symbol.SetType(*type);
2356     return;
2357   }
2358   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2359     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2360     if (symbol.test(Symbol::Flag::Function)) {
2361       functionOrSubroutineFlag = Symbol::Flag::Function;
2362     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2363       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2364     }
2365     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2366       // type will be determined in expression semantics
2367       AcquireIntrinsicProcedureFlags(symbol);
2368       return;
2369     }
2370   }
2371   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2372     return;
2373   }
2374   if (!context().HasError(symbol)) {
2375     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2376     context().SetError(symbol);
2377   }
2378 }
2379 
2380 // Extension: Allow forward references to scalar integer dummy arguments
2381 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2382 // what would otherwise have been their implicit type is default INTEGER.
2383 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2384   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2385       symbol.Rank() != 0 ||
2386       !context().languageFeatures().IsEnabled(
2387           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2388     return false;
2389   }
2390   const DeclTypeSpec *type{
2391       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2392   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2393     return false;
2394   }
2395   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2396   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2397     return false;
2398   }
2399   if (!ConvertToObjectEntity(symbol)) {
2400     return false;
2401   }
2402   // TODO: check no INTENT(OUT)?
2403   if (context().languageFeatures().ShouldWarn(
2404           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2405     Say(symbol.name(),
2406         "Dummy argument '%s' was used without being explicitly typed"_warn_en_US,
2407         symbol.name());
2408   }
2409   symbol.set(Symbol::Flag::Implicit);
2410   symbol.SetType(*type);
2411   return true;
2412 }
2413 
2414 // Ensure that the symbol for an intrinsic procedure is marked with
2415 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2416 // appropriate.
2417 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2418   symbol.attrs().set(Attr::INTRINSIC);
2419   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2420   case evaluate::IntrinsicClass::elementalFunction:
2421   case evaluate::IntrinsicClass::elementalSubroutine:
2422     symbol.attrs().set(Attr::ELEMENTAL);
2423     symbol.attrs().set(Attr::PURE);
2424     break;
2425   case evaluate::IntrinsicClass::impureSubroutine:
2426     break;
2427   default:
2428     symbol.attrs().set(Attr::PURE);
2429   }
2430 }
2431 
2432 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2433     Symbol &symbol, bool respectImplicitNoneType) {
2434   const Scope *scope{&symbol.owner()};
2435   if (scope->IsGlobal()) {
2436     scope = &currScope();
2437   }
2438   scope = &GetInclusiveScope(*scope);
2439   const auto *type{implicitRulesMap_->at(scope).GetType(
2440       symbol.name(), respectImplicitNoneType)};
2441   if (type) {
2442     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2443       // Resolve any forward-referenced derived type; a quick no-op else.
2444       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2445       instantiatable.Instantiate(currScope());
2446     }
2447   }
2448   return type;
2449 }
2450 
2451 // Convert symbol to be a ObjectEntity or return false if it can't be.
2452 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2453   if (symbol.has<ObjectEntityDetails>()) {
2454     // nothing to do
2455   } else if (symbol.has<UnknownDetails>()) {
2456     symbol.set_details(ObjectEntityDetails{});
2457   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2458     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2459     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2460   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2461     return useDetails->symbol().has<ObjectEntityDetails>();
2462   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2463     return hostDetails->symbol().has<ObjectEntityDetails>();
2464   } else {
2465     return false;
2466   }
2467   return true;
2468 }
2469 // Convert symbol to be a ProcEntity or return false if it can't be.
2470 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2471   if (symbol.has<ProcEntityDetails>()) {
2472     // nothing to do
2473   } else if (symbol.has<UnknownDetails>()) {
2474     symbol.set_details(ProcEntityDetails{});
2475   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2476     if (IsFunctionResult(symbol) &&
2477         !(IsPointer(symbol) && symbol.attrs().test(Attr::EXTERNAL))) {
2478       // Don't turn function result into a procedure pointer unless both
2479       // POUNTER and EXTERNAL
2480       return false;
2481     }
2482     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2483     symbol.set_details(ProcEntityDetails{std::move(*details)});
2484     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2485       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2486       symbol.set(Symbol::Flag::Function);
2487     }
2488   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2489     return useDetails->symbol().has<ProcEntityDetails>();
2490   } else if (auto *hostDetails{symbol.detailsIf<HostAssocDetails>()}) {
2491     return hostDetails->symbol().has<ProcEntityDetails>();
2492   } else {
2493     return false;
2494   }
2495   return true;
2496 }
2497 
2498 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2499     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2500   KindExpr value{GetKindParamExpr(category, kind)};
2501   if (auto known{evaluate::ToInt64(value)}) {
2502     return context().MakeNumericType(category, static_cast<int>(*known));
2503   } else {
2504     return currScope_->MakeNumericType(category, std::move(value));
2505   }
2506 }
2507 
2508 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2509     const std::optional<parser::KindSelector> &kind) {
2510   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2511   if (auto known{evaluate::ToInt64(value)}) {
2512     return context().MakeLogicalType(static_cast<int>(*known));
2513   } else {
2514     return currScope_->MakeLogicalType(std::move(value));
2515   }
2516 }
2517 
2518 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2519   if (inSpecificationPart_ && name.symbol) {
2520     auto kind{currScope().kind()};
2521     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2522         kind == Scope::Kind::Block) {
2523       bool isHostAssociated{&name.symbol->owner() == &currScope()
2524               ? name.symbol->has<HostAssocDetails>()
2525               : name.symbol->owner().Contains(currScope())};
2526       if (isHostAssociated) {
2527         specPartState_.forwardRefs.insert(name.source);
2528       }
2529     }
2530   }
2531 }
2532 
2533 std::optional<SourceName> ScopeHandler::HadForwardRef(
2534     const Symbol &symbol) const {
2535   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2536   if (iter != specPartState_.forwardRefs.end()) {
2537     return *iter;
2538   }
2539   return std::nullopt;
2540 }
2541 
2542 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2543   if (!context().HasError(symbol)) {
2544     if (auto fwdRef{HadForwardRef(symbol)}) {
2545       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2546       if (outer && symbol.has<UseDetails>() &&
2547           &symbol.GetUltimate() == &outer->GetUltimate()) {
2548         // e.g. IMPORT of host's USE association
2549         return false;
2550       }
2551       Say(*fwdRef,
2552           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2553           *fwdRef)
2554           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2555       context().SetError(symbol);
2556       return true;
2557     }
2558     if (IsDummy(symbol) && isImplicitNoneType() &&
2559         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2560       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2561       // ApplyImplicitRules() due to use in a specification expression,
2562       // and no explicit type declaration appeared later.
2563       Say(symbol.name(),
2564           "No explicit type declared for dummy argument '%s'"_err_en_US);
2565       context().SetError(symbol);
2566       return true;
2567     }
2568   }
2569   return false;
2570 }
2571 
2572 void ScopeHandler::MakeExternal(Symbol &symbol) {
2573   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2574     symbol.attrs().set(Attr::EXTERNAL);
2575     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2576       Say(symbol.name(),
2577           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2578           symbol.name());
2579     }
2580   }
2581 }
2582 
2583 // ModuleVisitor implementation
2584 
2585 bool ModuleVisitor::Pre(const parser::Only &x) {
2586   common::visit(common::visitors{
2587                     [&](const Indirection<parser::GenericSpec> &generic) {
2588                       GenericSpecInfo genericSpecInfo{generic.value()};
2589                       AddUseOnly(genericSpecInfo.symbolName());
2590                       AddUse(genericSpecInfo);
2591                     },
2592                     [&](const parser::Name &name) {
2593                       AddUseOnly(name.source);
2594                       Resolve(name, AddUse(name.source, name.source).use);
2595                     },
2596                     [&](const parser::Rename &rename) { Walk(rename); },
2597                 },
2598       x.u);
2599   return false;
2600 }
2601 
2602 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2603   const auto &localName{std::get<0>(x.t)};
2604   const auto &useName{std::get<1>(x.t)};
2605   AddUseRename(useName.source);
2606   SymbolRename rename{AddUse(localName.source, useName.source)};
2607   if (rename.use) {
2608     EraseRenamedSymbol(*rename.use);
2609   }
2610   Resolve(useName, rename.use);
2611   Resolve(localName, rename.local);
2612   return false;
2613 }
2614 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2615   const parser::DefinedOpName &local{std::get<0>(x.t)};
2616   const parser::DefinedOpName &use{std::get<1>(x.t)};
2617   GenericSpecInfo localInfo{local};
2618   GenericSpecInfo useInfo{use};
2619   if (IsIntrinsicOperator(context(), local.v.source)) {
2620     Say(local.v,
2621         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2622   } else if (IsLogicalConstant(context(), local.v.source)) {
2623     Say(local.v,
2624         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2625   } else {
2626     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2627     if (rename.use) {
2628       EraseRenamedSymbol(*rename.use);
2629     }
2630     useInfo.Resolve(rename.use);
2631     localInfo.Resolve(rename.local);
2632   }
2633   return false;
2634 }
2635 
2636 // Set useModuleScope_ to the Scope of the module being used.
2637 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2638   std::optional<bool> isIntrinsic;
2639   if (x.nature) {
2640     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2641     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2642   } else if (currScope().IsModule() && currScope().symbol() &&
2643       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2644     // Intrinsic modules USE only other intrinsic modules
2645     isIntrinsic = true;
2646   }
2647   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2648   if (!useModuleScope_) {
2649     return false;
2650   }
2651   // use the name from this source file
2652   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2653   return true;
2654 }
2655 
2656 void ModuleVisitor::Post(const parser::UseStmt &x) {
2657   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2658     // Not a use-only: collect the names that were used in renames,
2659     // then add a use for each public name that was not renamed.
2660     std::set<SourceName> useNames;
2661     for (const auto &rename : *list) {
2662       common::visit(common::visitors{
2663                         [&](const parser::Rename::Names &names) {
2664                           useNames.insert(std::get<1>(names.t).source);
2665                         },
2666                         [&](const parser::Rename::Operators &ops) {
2667                           useNames.insert(std::get<1>(ops.t).v.source);
2668                         },
2669                     },
2670           rename.u);
2671     }
2672     for (const auto &[name, symbol] : *useModuleScope_) {
2673       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2674           (!symbol->attrs().test(Attr::INTRINSIC) ||
2675               symbol->has<UseDetails>()) &&
2676           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2677         SourceName location{x.moduleName.source};
2678         if (auto *localSymbol{FindInScope(name)}) {
2679           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2680         } else {
2681           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2682         }
2683       }
2684     }
2685   }
2686   useModuleScope_ = nullptr;
2687 }
2688 
2689 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2690     const SourceName &localName, const SourceName &useName) {
2691   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2692 }
2693 
2694 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2695     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2696   if (!useModuleScope_) {
2697     return {}; // error occurred finding module
2698   }
2699   if (!useSymbol) {
2700     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2701         useModuleScope_->GetName().value());
2702     return {};
2703   }
2704   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2705       !FindModuleFileContaining(currScope())) {
2706     // Privacy is not enforced in module files so that generic interfaces
2707     // can be resolved to private specific procedures in specification
2708     // expressions.
2709     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2710         useModuleScope_->GetName().value());
2711     return {};
2712   }
2713   auto &localSymbol{MakeSymbol(localName)};
2714   DoAddUse(useName, localName, localSymbol, *useSymbol);
2715   return {&localSymbol, useSymbol};
2716 }
2717 
2718 // symbol must be either a Use or a Generic formed by merging two uses.
2719 // Convert it to a UseError with this additional location.
2720 static bool ConvertToUseError(
2721     Symbol &symbol, const SourceName &location, const Scope &module) {
2722   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2723   if (!useDetails) {
2724     if (auto *genericDetails{symbol.detailsIf<GenericDetails>()}) {
2725       if (!genericDetails->uses().empty()) {
2726         useDetails = &genericDetails->uses().at(0)->get<UseDetails>();
2727       }
2728     }
2729   }
2730   if (useDetails) {
2731     symbol.set_details(
2732         UseErrorDetails{*useDetails}.add_occurrence(location, module));
2733     return true;
2734   } else {
2735     return false;
2736   }
2737 }
2738 
2739 // If a symbol has previously been USE-associated and did not appear in a USE
2740 // ONLY clause, erase it from the current scope.  This is needed when a name
2741 // appears in a USE rename clause.
2742 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2743   const SourceName &name{useSymbol.name()};
2744   if (const Symbol * symbol{FindInScope(name)}) {
2745     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2746       const Symbol &moduleSymbol{useDetails->symbol()};
2747       if (moduleSymbol.name() == name &&
2748           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2749           !IsUseOnly(name)) {
2750         EraseSymbol(*symbol);
2751       }
2752     }
2753   }
2754 }
2755 
2756 void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
2757     Symbol &localSymbol, const Symbol &useSymbol) {
2758   if (localName != useSymbol.name()) {
2759     EraseRenamedSymbol(useSymbol);
2760   }
2761   if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2762     details->add_occurrence(location, *useModuleScope_);
2763     return;
2764   }
2765 
2766   if (localSymbol.has<UnknownDetails>()) {
2767     localSymbol.set_details(UseDetails{localName, useSymbol});
2768     localSymbol.attrs() =
2769         useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2770     localSymbol.flags() = useSymbol.flags();
2771     return;
2772   }
2773 
2774   Symbol &localUltimate{localSymbol.GetUltimate()};
2775   const Symbol &useUltimate{useSymbol.GetUltimate()};
2776   if (&localUltimate == &useUltimate) {
2777     // use-associating the same symbol again -- ok
2778     return;
2779   }
2780 
2781   auto checkAmbiguousDerivedType{[this, location, localName](
2782                                      const Symbol *t1, const Symbol *t2) {
2783     if (!t1 || !t2) {
2784       return true;
2785     } else {
2786       t1 = &t1->GetUltimate();
2787       t2 = &t2->GetUltimate();
2788       if (&t1 != &t2) {
2789         Say(location,
2790             "Generic interface '%s' has ambiguous derived types from modules '%s' and '%s'"_err_en_US,
2791             localName, t1->owner().GetName().value(),
2792             t2->owner().GetName().value());
2793         return false;
2794       }
2795     }
2796   }};
2797 
2798   auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
2799   const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
2800   auto combine{false};
2801   if (localGeneric) {
2802     if (useGeneric) {
2803       if (!checkAmbiguousDerivedType(
2804               localGeneric->derivedType(), useGeneric->derivedType())) {
2805         return;
2806       }
2807       combine = true;
2808     } else if (useUltimate.has<DerivedTypeDetails>()) {
2809       if (checkAmbiguousDerivedType(
2810               &useUltimate, localGeneric->derivedType())) {
2811         combine = true;
2812       } else {
2813         return;
2814       }
2815     } else if (&useUltimate == &BypassGeneric(localUltimate)) {
2816       return; // nothing to do; used subprogram is local's specific
2817     }
2818   } else if (useGeneric) {
2819     if (localUltimate.has<DerivedTypeDetails>()) {
2820       if (checkAmbiguousDerivedType(
2821               &localUltimate, useGeneric->derivedType())) {
2822         combine = true;
2823       } else {
2824         return;
2825       }
2826     } else if (&localUltimate == &BypassGeneric(useUltimate).GetUltimate()) {
2827       // Local is the specific of the used generic; replace it.
2828       EraseSymbol(localSymbol);
2829       Symbol &newSymbol{MakeSymbol(localName,
2830           useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2831           UseDetails{localName, useUltimate})};
2832       newSymbol.flags() = useSymbol.flags();
2833       return;
2834     }
2835   }
2836   if (!combine) {
2837     if (!ConvertToUseError(localSymbol, location, *useModuleScope_)) {
2838       Say(location,
2839           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2840           localName)
2841           .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2842               localName);
2843     }
2844     return;
2845   }
2846 
2847   // Two items are being use-associated from different modules
2848   // to the same local name.  At least one of them must be a generic,
2849   // and the other one can be a generic or a derived type.
2850   // (It could also have been the specific of the generic, but those
2851   // cases are handled above without needing to make a local copy of the
2852   // generic.)
2853 
2854   if (localGeneric) {
2855     if (localSymbol.has<UseDetails>()) {
2856       // Create a local copy of a previously use-associated generic so that
2857       // it can be locally extended without corrupting the original.
2858       GenericDetails generic;
2859       generic.CopyFrom(*localGeneric);
2860       EraseSymbol(localSymbol);
2861       Symbol &newSymbol{MakeSymbol(
2862           localSymbol.name(), localSymbol.attrs(), std::move(generic))};
2863       newSymbol.flags() = localSymbol.flags();
2864       localGeneric = &newSymbol.get<GenericDetails>();
2865       localGeneric->AddUse(localSymbol);
2866     }
2867     if (useGeneric) {
2868       // Combine two use-associated generics
2869       localSymbol.attrs() =
2870           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2871       localSymbol.flags() = useSymbol.flags();
2872       AddGenericUse(*localGeneric, localName, useUltimate);
2873       localGeneric->CopyFrom(*useGeneric);
2874     } else {
2875       CHECK(useUltimate.has<DerivedTypeDetails>());
2876       localGeneric->set_derivedType(
2877           AddGenericUse(*localGeneric, localName, useUltimate));
2878     }
2879   } else {
2880     CHECK(useGeneric && localUltimate.has<DerivedTypeDetails>());
2881     CHECK(localSymbol.has<UseDetails>());
2882     // Create a local copy of the use-associated generic, then extend it
2883     // with the local derived type.
2884     GenericDetails generic;
2885     generic.CopyFrom(*useGeneric);
2886     EraseSymbol(localSymbol);
2887     Symbol &newSymbol{MakeSymbol(localName,
2888         useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2889         std::move(generic))};
2890     newSymbol.flags() = useUltimate.flags();
2891     auto &newUseGeneric{newSymbol.get<GenericDetails>()};
2892     AddGenericUse(newUseGeneric, localName, useUltimate);
2893     newUseGeneric.AddUse(localSymbol);
2894     newUseGeneric.set_derivedType(localSymbol);
2895   }
2896 }
2897 
2898 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2899   if (useModuleScope_) {
2900     const auto &name{info.symbolName()};
2901     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2902     info.Resolve(rename.use);
2903   }
2904 }
2905 
2906 // Create a UseDetails symbol for this USE and add it to generic
2907 Symbol &ModuleVisitor::AddGenericUse(
2908     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2909   Symbol &newSymbol{
2910       currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol})};
2911   generic.AddUse(newSymbol);
2912   return newSymbol;
2913 }
2914 
2915 // Enforce C1406
2916 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2917     SourceName name, bool isIntrinsic) {
2918   if (isIntrinsic) {
2919     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2920         iter != explicitNonIntrinsicUses_.end()) {
2921       Say(name,
2922           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2923           name)
2924           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2925     }
2926     explicitIntrinsicUses_.insert(name);
2927   } else {
2928     if (auto iter{explicitIntrinsicUses_.find(name)};
2929         iter != explicitIntrinsicUses_.end()) {
2930       Say(name,
2931           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2932           name)
2933           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2934     }
2935     explicitNonIntrinsicUses_.insert(name);
2936   }
2937 }
2938 
2939 bool ModuleVisitor::BeginSubmodule(
2940     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2941   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2942   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2943   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2944   if (!ancestor) {
2945     return false;
2946   }
2947   Scope *parentScope{parentName
2948           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2949           : ancestor};
2950   if (!parentScope) {
2951     return false;
2952   }
2953   PushScope(*parentScope); // submodule is hosted in parent
2954   BeginModule(name, true);
2955   if (!ancestor->AddSubmodule(name.source, currScope())) {
2956     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2957         ancestorName.source, name.source);
2958   }
2959   return true;
2960 }
2961 
2962 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2963   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2964   auto &details{symbol.get<ModuleDetails>()};
2965   PushScope(Scope::Kind::Module, &symbol);
2966   details.set_scope(&currScope());
2967   defaultAccess_ = Attr::PUBLIC;
2968   prevAccessStmt_ = std::nullopt;
2969 }
2970 
2971 // Find a module or submodule by name and return its scope.
2972 // If ancestor is present, look for a submodule of that ancestor module.
2973 // May have to read a .mod file to find it.
2974 // If an error occurs, report it and return nullptr.
2975 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2976     std::optional<bool> isIntrinsic, Scope *ancestor) {
2977   ModFileReader reader{context()};
2978   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2979   if (!scope) {
2980     return nullptr;
2981   }
2982   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2983     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2984   }
2985   Resolve(name, scope->symbol());
2986   return scope;
2987 }
2988 
2989 void ModuleVisitor::ApplyDefaultAccess() {
2990   for (auto &pair : currScope()) {
2991     Symbol &symbol = *pair.second;
2992     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2993       symbol.attrs().set(defaultAccess_);
2994     }
2995   }
2996 }
2997 
2998 // InterfaceVistor implementation
2999 
3000 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
3001   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
3002   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
3003   return BeginAttrs();
3004 }
3005 
3006 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
3007 
3008 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
3009   genericInfo_.pop();
3010 }
3011 
3012 // Create a symbol in genericSymbol_ for this GenericSpec.
3013 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
3014   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
3015     SetGenericSymbol(*symbol);
3016   }
3017   return false;
3018 }
3019 
3020 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
3021   if (!isGeneric()) {
3022     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
3023     return false;
3024   }
3025   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
3026   const auto &names{std::get<std::list<parser::Name>>(x.t)};
3027   AddSpecificProcs(names, kind);
3028   return false;
3029 }
3030 
3031 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
3032   genericInfo_.emplace(/*isInterface*/ false);
3033   return true;
3034 }
3035 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
3036   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
3037     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
3038   }
3039   const auto &names{std::get<std::list<parser::Name>>(x.t)};
3040   AddSpecificProcs(names, ProcedureKind::Procedure);
3041   genericInfo_.pop();
3042 }
3043 
3044 bool InterfaceVisitor::inInterfaceBlock() const {
3045   return !genericInfo_.empty() && GetGenericInfo().isInterface;
3046 }
3047 bool InterfaceVisitor::isGeneric() const {
3048   return !genericInfo_.empty() && GetGenericInfo().symbol;
3049 }
3050 bool InterfaceVisitor::isAbstract() const {
3051   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
3052 }
3053 
3054 void InterfaceVisitor::AddSpecificProcs(
3055     const std::list<parser::Name> &names, ProcedureKind kind) {
3056   for (const auto &name : names) {
3057     specificProcs_.emplace(
3058         GetGenericInfo().symbol, std::make_pair(&name, kind));
3059   }
3060 }
3061 
3062 // By now we should have seen all specific procedures referenced by name in
3063 // this generic interface. Resolve those names to symbols.
3064 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
3065   auto &details{generic.get<GenericDetails>()};
3066   UnorderedSymbolSet symbolsSeen;
3067   for (const Symbol &symbol : details.specificProcs()) {
3068     symbolsSeen.insert(symbol.GetUltimate());
3069   }
3070   auto range{specificProcs_.equal_range(&generic)};
3071   for (auto it{range.first}; it != range.second; ++it) {
3072     const parser::Name *name{it->second.first};
3073     auto kind{it->second.second};
3074     const auto *symbol{FindSymbol(*name)};
3075     if (!symbol) {
3076       Say(*name, "Procedure '%s' not found"_err_en_US);
3077       continue;
3078     }
3079     const Symbol &specific{BypassGeneric(*symbol)};
3080     const Symbol &ultimate{specific.GetUltimate()};
3081     if (!ultimate.has<SubprogramDetails>() &&
3082         !ultimate.has<SubprogramNameDetails>()) {
3083       Say(*name, "'%s' is not a subprogram"_err_en_US);
3084       continue;
3085     }
3086     if (kind == ProcedureKind::ModuleProcedure) {
3087       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
3088         if (nd->kind() != SubprogramKind::Module) {
3089           Say(*name, "'%s' is not a module procedure"_err_en_US);
3090         }
3091       } else {
3092         // USE-associated procedure
3093         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
3094         CHECK(sd);
3095         if (ultimate.owner().kind() != Scope::Kind::Module ||
3096             sd->isInterface()) {
3097           Say(*name, "'%s' is not a module procedure"_err_en_US);
3098         }
3099       }
3100     }
3101     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
3102       // When a specific procedure is a USE association, that association
3103       // is saved in the generic's specifics, not its ultimate symbol,
3104       // so that module file output of interfaces can distinguish them.
3105       details.AddSpecificProc(specific, name->source);
3106     } else if (&specific == &ultimate) {
3107       Say(name->source,
3108           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
3109           name->source, MakeOpName(generic.name()));
3110     } else {
3111       Say(name->source,
3112           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
3113           ultimate.name(), ultimate.owner().GetName().value(),
3114           MakeOpName(generic.name()));
3115     }
3116   }
3117   specificProcs_.erase(range.first, range.second);
3118 }
3119 
3120 // Check that the specific procedures are all functions or all subroutines.
3121 // If there is a derived type with the same name they must be functions.
3122 // Set the corresponding flag on generic.
3123 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
3124   ResolveSpecificsInGeneric(generic);
3125   auto &details{generic.get<GenericDetails>()};
3126   if (auto *proc{details.CheckSpecific()}) {
3127     auto msg{
3128         "'%s' may not be the name of both a generic interface and a"
3129         " procedure unless it is a specific procedure of the generic"_err_en_US};
3130     if (proc->name().begin() > generic.name().begin()) {
3131       Say(proc->name(), std::move(msg));
3132     } else {
3133       Say(generic.name(), std::move(msg));
3134     }
3135   }
3136   auto &specifics{details.specificProcs()};
3137   if (specifics.empty()) {
3138     if (details.derivedType()) {
3139       generic.set(Symbol::Flag::Function);
3140     }
3141     return;
3142   }
3143   const Symbol &firstSpecific{specifics.front()};
3144   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
3145   for (const Symbol &specific : specifics) {
3146     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
3147       auto &msg{Say(generic.name(),
3148           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
3149       if (isFunction) {
3150         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
3151         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
3152       } else {
3153         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
3154         msg.Attach(specific.name(), "Function declaration"_en_US);
3155       }
3156     }
3157   }
3158   if (!isFunction && details.derivedType()) {
3159     SayDerivedType(generic.name(),
3160         "Generic interface '%s' may only contain functions due to derived type"
3161         " with same name"_err_en_US,
3162         *details.derivedType()->scope());
3163   }
3164   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
3165 }
3166 
3167 // SubprogramVisitor implementation
3168 
3169 // Return false if it is actually an assignment statement.
3170 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
3171   const auto &name{std::get<parser::Name>(x.t)};
3172   const DeclTypeSpec *resultType{nullptr};
3173   // Look up name: provides return type or tells us if it's an array
3174   if (auto *symbol{FindSymbol(name)}) {
3175     auto *details{symbol->detailsIf<EntityDetails>()};
3176     if (!details) {
3177       badStmtFuncFound_ = true;
3178       return false;
3179     }
3180     // TODO: check that attrs are compatible with stmt func
3181     resultType = details->type();
3182     symbol->details() = UnknownDetails{}; // will be replaced below
3183   }
3184   if (badStmtFuncFound_) {
3185     Say(name, "'%s' has not been declared as an array"_err_en_US);
3186     return true;
3187   }
3188   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
3189   symbol.set(Symbol::Flag::StmtFunction);
3190   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
3191   auto &details{symbol.get<SubprogramDetails>()};
3192   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
3193     ObjectEntityDetails dummyDetails{true};
3194     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
3195       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
3196         if (d->type()) {
3197           dummyDetails.set_type(*d->type());
3198         }
3199       }
3200     }
3201     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
3202     ApplyImplicitRules(dummy);
3203     details.add_dummyArg(dummy);
3204   }
3205   ObjectEntityDetails resultDetails;
3206   if (resultType) {
3207     resultDetails.set_type(*resultType);
3208   }
3209   resultDetails.set_funcResult(true);
3210   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
3211   ApplyImplicitRules(result);
3212   details.set_result(result);
3213   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
3214   Walk(parsedExpr);
3215   // The analysis of the expression that constitutes the body of the
3216   // statement function is deferred to FinishSpecificationPart() so that
3217   // all declarations and implicit typing are complete.
3218   PopScope();
3219   return true;
3220 }
3221 
3222 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3223   if (suffix.resultName) {
3224     if (IsFunction(currScope())) {
3225       if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3226         if (info->inFunctionStmt) {
3227           info->resultName = &suffix.resultName.value();
3228         } else {
3229           // will check the result name in Post(EntryStmt)
3230         }
3231       }
3232     } else {
3233       Message &msg{Say(*suffix.resultName,
3234           "RESULT(%s) may appear only in a function"_err_en_US)};
3235       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3236         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3237       }
3238     }
3239   }
3240   // LanguageBindingSpec deferred to Post(EntryStmt) or, for FunctionStmt,
3241   // all the way to EndSubprogram().
3242   return false;
3243 }
3244 
3245 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3246   // Save this to process after UseStmt and ImplicitPart
3247   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3248     FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3249     if (info.parsedType) { // C1543
3250       Say(currStmtSource().value(),
3251           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3252       return false;
3253     } else {
3254       info.parsedType = parsedType;
3255       info.source = currStmtSource();
3256       return false;
3257     }
3258   } else {
3259     return true;
3260   }
3261 }
3262 
3263 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3264   const auto &name{std::get<parser::Name>(
3265       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3266   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3267 }
3268 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &x) {
3269   const auto &stmt{std::get<parser::Statement<parser::SubroutineStmt>>(x.t)};
3270   EndSubprogram(stmt.source,
3271       &std::get<std::optional<parser::LanguageBindingSpec>>(stmt.statement.t));
3272 }
3273 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3274   const auto &name{std::get<parser::Name>(
3275       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3276   return BeginSubprogram(name, Symbol::Flag::Function);
3277 }
3278 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &x) {
3279   const auto &stmt{std::get<parser::Statement<parser::FunctionStmt>>(x.t)};
3280   const auto &maybeSuffix{
3281       std::get<std::optional<parser::Suffix>>(stmt.statement.t)};
3282   EndSubprogram(stmt.source, maybeSuffix ? &maybeSuffix->binding : nullptr);
3283 }
3284 
3285 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &stmt) {
3286   BeginAttrs();
3287   Walk(std::get<std::list<parser::PrefixSpec>>(stmt.t));
3288   Walk(std::get<parser::Name>(stmt.t));
3289   Walk(std::get<std::list<parser::DummyArg>>(stmt.t));
3290   // Don't traverse the LanguageBindingSpec now; it's deferred to EndSubprogram.
3291   const auto &name{std::get<parser::Name>(stmt.t)};
3292   auto &details{PostSubprogramStmt(name)};
3293   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3294     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3295       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3296       details.add_dummyArg(dummy);
3297     } else {
3298       details.add_alternateReturn();
3299     }
3300   }
3301   return false;
3302 }
3303 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3304   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3305   CHECK(!info.inFunctionStmt);
3306   info.inFunctionStmt = true;
3307   return BeginAttrs();
3308 }
3309 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3310 
3311 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3312   const auto &name{std::get<parser::Name>(stmt.t)};
3313   auto &details{PostSubprogramStmt(name)};
3314   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3315     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3316     details.add_dummyArg(dummy);
3317   }
3318   const parser::Name *funcResultName;
3319   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3320   CHECK(info.inFunctionStmt);
3321   info.inFunctionStmt = false;
3322   bool distinctResultName{
3323       info.resultName && info.resultName->source != name.source};
3324   if (distinctResultName) {
3325     // Note that RESULT is ignored if it has the same name as the function.
3326     // The symbol created by PushScope() is retained as a place-holder
3327     // for error detection.
3328     funcResultName = info.resultName;
3329   } else {
3330     EraseSymbol(name); // was added by PushScope()
3331     funcResultName = &name;
3332   }
3333   if (details.isFunction()) {
3334     CHECK(context().HasError(currScope().symbol()));
3335   } else {
3336     // RESULT(x) can be the same explicitly-named RESULT(x) as an ENTRY
3337     // statement.
3338     Symbol *result{nullptr};
3339     if (distinctResultName) {
3340       if (auto iter{currScope().find(funcResultName->source)};
3341           iter != currScope().end()) {
3342         Symbol &entryResult{*iter->second};
3343         if (IsFunctionResult(entryResult)) {
3344           result = &entryResult;
3345         }
3346       }
3347     }
3348     if (result) {
3349       Resolve(*funcResultName, *result);
3350     } else {
3351       // add function result to function scope
3352       EntityDetails funcResultDetails;
3353       funcResultDetails.set_funcResult(true);
3354       result = &MakeSymbol(*funcResultName, std::move(funcResultDetails));
3355     }
3356     info.resultSymbol = result;
3357     details.set_result(*result);
3358   }
3359   // C1560.
3360   if (info.resultName && !distinctResultName) {
3361     Say(info.resultName->source,
3362         "The function name should not appear in RESULT, references to '%s' "
3363         "inside the function will be considered as references to the "
3364         "result only"_warn_en_US,
3365         name.source);
3366     // RESULT name was ignored above, the only side effect from doing so will be
3367     // the inability to make recursive calls. The related parser::Name is still
3368     // resolved to the created function result symbol because every parser::Name
3369     // should be resolved to avoid internal errors.
3370     Resolve(*info.resultName, info.resultSymbol);
3371   }
3372   name.symbol = currScope().symbol(); // must not be function result symbol
3373   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3374   // has a RESULT() suffix.
3375   info.resultName = nullptr;
3376 }
3377 
3378 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3379     const parser::Name &name) {
3380   Symbol &symbol{*currScope().symbol()};
3381   symbol.attrs() |= EndAttrs();
3382   if (symbol.attrs().test(Attr::MODULE)) {
3383     symbol.attrs().set(Attr::EXTERNAL, false);
3384   }
3385   return symbol.get<SubprogramDetails>();
3386 }
3387 
3388 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3389   if (const auto &suffix{std::get<std::optional<parser::Suffix>>(stmt.t)}) {
3390     Walk(suffix->binding);
3391   }
3392   PostEntryStmt(stmt);
3393   EndAttrs();
3394 }
3395 
3396 void SubprogramVisitor::CreateEntry(
3397     const parser::EntryStmt &stmt, Symbol &subprogram) {
3398   const auto &entryName{std::get<parser::Name>(stmt.t)};
3399   Scope &outer{currScope().parent()};
3400   Symbol::Flag subpFlag{subprogram.test(Symbol::Flag::Function)
3401           ? Symbol::Flag::Function
3402           : Symbol::Flag::Subroutine};
3403   Attrs attrs;
3404   if (Symbol * extant{FindSymbol(outer, entryName)}) {
3405     if (!HandlePreviousCalls(entryName, *extant, subpFlag)) {
3406       if (outer.IsTopLevel()) {
3407         Say2(entryName,
3408             "'%s' is already defined as a global identifier"_err_en_US, *extant,
3409             "Previous definition of '%s'"_en_US);
3410       } else {
3411         SayAlreadyDeclared(entryName, *extant);
3412       }
3413       return;
3414     }
3415     attrs = extant->attrs();
3416   }
3417   const auto &suffix{std::get<std::optional<parser::Suffix>>(stmt.t)};
3418   bool badResultName{false};
3419   std::optional<SourceName> distinctResultName;
3420   if (suffix && suffix->resultName &&
3421       suffix->resultName->source != entryName.source) {
3422     distinctResultName = suffix->resultName->source;
3423     const parser::Name &resultName{*suffix->resultName};
3424     if (resultName.source == subprogram.name()) { // C1574
3425       Say2(resultName.source,
3426           "RESULT(%s) may not have the same name as the function"_err_en_US,
3427           subprogram, "Containing function"_en_US);
3428       badResultName = true;
3429     } else if (const Symbol * extant{FindSymbol(outer, resultName)}) { // C1574
3430       if (const auto *details{extant->detailsIf<SubprogramDetails>()}) {
3431         if (details->entryScope() == &currScope()) {
3432           Say2(resultName.source,
3433               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3434               extant->name(), "Conflicting ENTRY"_en_US);
3435           badResultName = true;
3436         }
3437       }
3438     }
3439   }
3440   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3441     attrs.set(Attr::PUBLIC);
3442   }
3443   Symbol *entrySymbol{FindInScope(outer, entryName.source)};
3444   if (entrySymbol) {
3445     if (auto *generic{entrySymbol->detailsIf<GenericDetails>()}) {
3446       if (auto *specific{generic->specific()}) {
3447         // Forward reference to ENTRY from a generic interface
3448         entrySymbol = specific;
3449         entrySymbol->attrs() |= attrs;
3450       }
3451     }
3452   } else {
3453     entrySymbol = &MakeSymbol(outer, entryName.source, attrs);
3454   }
3455   SubprogramDetails entryDetails;
3456   entryDetails.set_entryScope(currScope());
3457   entrySymbol->set(subpFlag);
3458   if (subpFlag == Symbol::Flag::Function) {
3459     Symbol *result{nullptr};
3460     EntityDetails resultDetails;
3461     resultDetails.set_funcResult(true);
3462     if (distinctResultName) {
3463       if (!badResultName) {
3464         // RESULT(x) can be the same explicitly-named RESULT(x) as
3465         // the enclosing function or another ENTRY.
3466         if (auto iter{currScope().find(suffix->resultName->source)};
3467             iter != currScope().end()) {
3468           result = &*iter->second;
3469         }
3470         if (!result) {
3471           result = &MakeSymbol(
3472               *distinctResultName, Attrs{}, std::move(resultDetails));
3473         }
3474         Resolve(*suffix->resultName, *result);
3475       }
3476     } else {
3477       result = &MakeSymbol(entryName.source, Attrs{}, std::move(resultDetails));
3478     }
3479     if (result) {
3480       entryDetails.set_result(*result);
3481     }
3482   }
3483   if (subpFlag == Symbol::Flag::Subroutine ||
3484       (distinctResultName && !badResultName)) {
3485     Symbol &assoc{MakeSymbol(entryName.source)};
3486     assoc.set_details(HostAssocDetails{*entrySymbol});
3487     assoc.set(Symbol::Flag::Subroutine);
3488   }
3489   Resolve(entryName, *entrySymbol);
3490   Details details{std::move(entryDetails)};
3491   entrySymbol->set_details(std::move(entryDetails));
3492 }
3493 
3494 void SubprogramVisitor::PostEntryStmt(const parser::EntryStmt &stmt) {
3495   // The entry symbol should have already been created and resolved
3496   // in CreateEntry(), called by BeginSubprogram(), with one exception (below).
3497   const auto &name{std::get<parser::Name>(stmt.t)};
3498   Scope &inclusiveScope{InclusiveScope()};
3499   if (!name.symbol) {
3500     if (inclusiveScope.kind() != Scope::Kind::Subprogram) {
3501       Say(name.source,
3502           "ENTRY '%s' may appear only in a subroutine or function"_err_en_US,
3503           name.source);
3504     } else if (FindSeparateModuleSubprogramInterface(inclusiveScope.symbol())) {
3505       Say(name.source,
3506           "ENTRY '%s' may not appear in a separate module procedure"_err_en_US,
3507           name.source);
3508     } else {
3509       // C1571 - entry is nested, so was not put into the program tree; error
3510       // is emitted from MiscChecker in semantics.cpp.
3511     }
3512     return;
3513   }
3514   Symbol &entrySymbol{*name.symbol};
3515   if (context().HasError(entrySymbol)) {
3516     return;
3517   }
3518   if (!entrySymbol.has<SubprogramDetails>()) {
3519     SayAlreadyDeclared(name, entrySymbol);
3520     return;
3521   }
3522   SubprogramDetails &entryDetails{entrySymbol.get<SubprogramDetails>()};
3523   CHECK(entryDetails.entryScope() == &inclusiveScope);
3524   entrySymbol.attrs() |= GetAttrs();
3525   SetBindNameOn(entrySymbol);
3526   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3527     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3528       Symbol *dummy{FindSymbol(*dummyName)};
3529       if (dummy) {
3530         common::visit(
3531             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3532                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3533                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3534                 [](SubprogramDetails &x) { x.set_isDummy(); },
3535                 [&](const auto &) {
3536                   Say2(dummyName->source,
3537                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3538                       dummy->name(), "Previous declaration of '%s'"_en_US);
3539                 }},
3540             dummy->details());
3541       } else {
3542         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3543         if (!inSpecificationPart_) {
3544           ApplyImplicitRules(*dummy);
3545         }
3546       }
3547       entryDetails.add_dummyArg(*dummy);
3548     } else {
3549       if (entrySymbol.test(Symbol::Flag::Function)) { // C1573
3550         Say(name,
3551             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3552         break;
3553       }
3554       entryDetails.add_alternateReturn();
3555     }
3556   }
3557 }
3558 
3559 // A subprogram declared with MODULE PROCEDURE
3560 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3561   auto *symbol{FindSymbol(name)};
3562   if (symbol && symbol->has<SubprogramNameDetails>()) {
3563     symbol = FindSymbol(currScope().parent(), name);
3564   }
3565   if (!IsSeparateModuleProcedureInterface(symbol)) {
3566     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3567     return false;
3568   }
3569   if (symbol->owner() == currScope() && symbol->scope()) {
3570     // This is a MODULE PROCEDURE whose interface appears in its host.
3571     // Convert the module procedure's interface into a subprogram.
3572     SetScope(DEREF(symbol->scope()));
3573     symbol->get<SubprogramDetails>().set_isInterface(false);
3574   } else {
3575     // Copy the interface into a new subprogram scope.
3576     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3577     PushScope(Scope::Kind::Subprogram, &newSymbol);
3578     const auto &details{symbol->get<SubprogramDetails>()};
3579     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3580     newDetails.set_moduleInterface(*symbol);
3581     for (const Symbol *dummyArg : details.dummyArgs()) {
3582       if (!dummyArg) {
3583         newDetails.add_alternateReturn();
3584       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3585         newDetails.add_dummyArg(*copy);
3586       }
3587     }
3588     if (details.isFunction()) {
3589       currScope().erase(symbol->name());
3590       newDetails.set_result(*currScope().CopySymbol(details.result()));
3591     }
3592   }
3593   return true;
3594 }
3595 
3596 // A subprogram or interface declared with SUBROUTINE or FUNCTION
3597 bool SubprogramVisitor::BeginSubprogram(const parser::Name &name,
3598     Symbol::Flag subpFlag, bool hasModulePrefix,
3599     const parser::LanguageBindingSpec *bindingSpec,
3600     const ProgramTree::EntryStmtList *entryStmts) {
3601   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3602     Say(name,
3603         "'%s' is a MODULE procedure which must be declared within a "
3604         "MODULE or SUBMODULE"_err_en_US);
3605     return false;
3606   }
3607   Symbol *moduleInterface{nullptr};
3608   if (hasModulePrefix && !inInterfaceBlock()) {
3609     moduleInterface = FindSymbol(currScope(), name);
3610     if (IsSeparateModuleProcedureInterface(moduleInterface)) {
3611       // Subprogram is MODULE FUNCTION or MODULE SUBROUTINE with an interface
3612       // previously defined in the same scope.
3613       currScope().erase(moduleInterface->name());
3614     } else {
3615       moduleInterface = nullptr;
3616     }
3617     if (!moduleInterface) {
3618       moduleInterface = FindSymbol(currScope().parent(), name);
3619       if (!IsSeparateModuleProcedureInterface(moduleInterface)) {
3620         Say(name,
3621             "'%s' was not declared a separate module procedure"_err_en_US);
3622         return false;
3623       }
3624     }
3625   }
3626   Symbol &newSymbol{PushSubprogramScope(name, subpFlag, bindingSpec)};
3627   if (moduleInterface) {
3628     newSymbol.get<SubprogramDetails>().set_moduleInterface(*moduleInterface);
3629     if (moduleInterface->attrs().test(Attr::PRIVATE)) {
3630       newSymbol.attrs().set(Attr::PRIVATE);
3631     } else if (moduleInterface->attrs().test(Attr::PUBLIC)) {
3632       newSymbol.attrs().set(Attr::PUBLIC);
3633     }
3634   }
3635   if (entryStmts) {
3636     for (const auto &ref : *entryStmts) {
3637       CreateEntry(*ref, newSymbol);
3638     }
3639   }
3640   return true;
3641 }
3642 
3643 void SubprogramVisitor::EndSubprogram(
3644     std::optional<parser::CharBlock> stmtSource,
3645     const std::optional<parser::LanguageBindingSpec> *binding) {
3646   if (binding && *binding && currScope().symbol()) {
3647     // Finally process the BIND(C,NAME=name) now that symbols in the name
3648     // expression will resolve local names.
3649     auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
3650     auto originalStmtSource{messageHandler().currStmtSource()};
3651     messageHandler().set_currStmtSource(stmtSource);
3652     BeginAttrs();
3653     Walk(**binding);
3654     SetBindNameOn(*currScope().symbol());
3655     currScope().symbol()->attrs() |= EndAttrs();
3656     messageHandler().set_currStmtSource(originalStmtSource);
3657   }
3658   PopScope();
3659 }
3660 
3661 bool SubprogramVisitor::HandlePreviousCalls(
3662     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3663   // If the extant symbol is a generic, check its homonymous specific
3664   // procedure instead if it has one.
3665   if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
3666     return generic->specific() &&
3667         HandlePreviousCalls(name, *generic->specific(), subpFlag);
3668   } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3669              !proc->isDummy() &&
3670              !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3671     // There's a symbol created for previous calls to this subprogram or
3672     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3673     // obligation to rewrite symbol pointers in the parse tree.
3674     if (!symbol.test(subpFlag)) {
3675       Say2(name,
3676           subpFlag == Symbol::Flag::Function
3677               ? "'%s' was previously called as a subroutine"_err_en_US
3678               : "'%s' was previously called as a function"_err_en_US,
3679           symbol, "Previous call of '%s'"_en_US);
3680     }
3681     EntityDetails entity;
3682     if (proc->type()) {
3683       entity.set_type(*proc->type());
3684     }
3685     symbol.details() = std::move(entity);
3686     return true;
3687   } else {
3688     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3689   }
3690 }
3691 
3692 void SubprogramVisitor::CheckExtantProc(
3693     const parser::Name &name, Symbol::Flag subpFlag) {
3694   if (auto *prev{FindSymbol(name)}) {
3695     if (IsDummy(*prev)) {
3696     } else if (auto *entity{prev->detailsIf<EntityDetails>()};
3697                IsPointer(*prev) && !entity->type()) {
3698       // POINTER attribute set before interface
3699     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3700       // Procedures in an INTERFACE block do not resolve to symbols
3701       // in scopes between the global scope and the current scope.
3702     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3703       SayAlreadyDeclared(name, *prev);
3704     }
3705   }
3706 }
3707 
3708 Symbol &SubprogramVisitor::PushSubprogramScope(const parser::Name &name,
3709     Symbol::Flag subpFlag, const parser::LanguageBindingSpec *bindingSpec) {
3710   Symbol *symbol{GetSpecificFromGeneric(name)};
3711   if (!symbol) {
3712     if (bindingSpec && currScope().IsGlobal() && bindingSpec->v) {
3713       // Create this new top-level subprogram with a binding label
3714       // in a new global scope, so that its symbol's name won't clash
3715       // with another symbol that has a distinct binding label.
3716       PushScope(Scope::Kind::Global,
3717           &MakeSymbol(context().GetTempName(currScope()), Attrs{},
3718               MiscDetails{MiscDetails::Kind::ScopeName}));
3719     }
3720     CheckExtantProc(name, subpFlag);
3721     symbol = &MakeSymbol(name, SubprogramDetails{});
3722   }
3723   symbol->ReplaceName(name.source);
3724   symbol->set(subpFlag);
3725   PushScope(Scope::Kind::Subprogram, symbol);
3726   if (subpFlag == Symbol::Flag::Function) {
3727     funcResultStack().Push(currScope());
3728   }
3729   if (inInterfaceBlock()) {
3730     auto &details{symbol->get<SubprogramDetails>()};
3731     details.set_isInterface();
3732     if (isAbstract()) {
3733       symbol->attrs().set(Attr::ABSTRACT);
3734     } else {
3735       MakeExternal(*symbol);
3736     }
3737     if (isGeneric()) {
3738       Symbol &genericSymbol{GetGenericSymbol()};
3739       if (genericSymbol.has<GenericDetails>()) {
3740         genericSymbol.get<GenericDetails>().AddSpecificProc(
3741             *symbol, name.source);
3742       } else {
3743         CHECK(context().HasError(genericSymbol));
3744       }
3745     }
3746     set_inheritFromParent(false);
3747   }
3748   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3749   return *symbol;
3750 }
3751 
3752 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3753   if (auto *prev{FindSymbol(name)}) {
3754     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3755       if (prev->test(Symbol::Flag::Subroutine) ||
3756           prev->test(Symbol::Flag::Function)) {
3757         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3758             "Previous call of '%s'"_en_US);
3759       }
3760       EraseSymbol(name);
3761     }
3762   }
3763   if (name.source.empty()) {
3764     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3765     PushScope(Scope::Kind::BlockData, nullptr);
3766   } else {
3767     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3768   }
3769 }
3770 
3771 // If name is a generic, return specific subprogram with the same name.
3772 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3773   // Search for the name but don't resolve it
3774   if (auto *symbol{currScope().FindSymbol(name.source)}) {
3775     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3776       // found generic, want subprogram
3777       auto *specific{details->specific()};
3778       if (!specific) {
3779         specific =
3780             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3781         if (details->derivedType()) {
3782           // A specific procedure with the same name as a derived type
3783           SayAlreadyDeclared(name, *details->derivedType());
3784         } else {
3785           details->set_specific(Resolve(name, *specific));
3786         }
3787       } else if (isGeneric()) {
3788         SayAlreadyDeclared(name, *specific);
3789       }
3790       if (!specific->has<SubprogramDetails>()) {
3791         specific->set_details(SubprogramDetails{});
3792       }
3793       return specific;
3794     }
3795   }
3796   return nullptr;
3797 }
3798 
3799 // DeclarationVisitor implementation
3800 
3801 bool DeclarationVisitor::BeginDecl() {
3802   BeginDeclTypeSpec();
3803   BeginArraySpec();
3804   return BeginAttrs();
3805 }
3806 void DeclarationVisitor::EndDecl() {
3807   EndDeclTypeSpec();
3808   EndArraySpec();
3809   EndAttrs();
3810 }
3811 
3812 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3813   const auto *details{
3814       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3815   if (!details) {
3816     return false;
3817   }
3818   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3819   for (const auto &[location, module] : details->occurrences()) {
3820     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3821         name.source, module->GetName().value());
3822   }
3823   context().SetError(*name.symbol);
3824   return true;
3825 }
3826 
3827 // Report error if accessibility of symbol doesn't match isPrivate.
3828 void DeclarationVisitor::CheckAccessibility(
3829     const SourceName &name, bool isPrivate, Symbol &symbol) {
3830   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3831     Say2(name,
3832         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3833         symbol, "Previous declaration of '%s'"_en_US);
3834   }
3835 }
3836 
3837 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3838   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3839     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3840       if (typeSpec->category() == DeclTypeSpec::Character) {
3841         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3842           Say("The type parameter LEN cannot be deferred without"
3843               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3844         }
3845       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3846         for (const auto &pair : derivedSpec->parameters()) {
3847           if (pair.second.isDeferred()) {
3848             Say(currStmtSource().value(),
3849                 "The value of type parameter '%s' cannot be deferred"
3850                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3851                 pair.first);
3852           }
3853         }
3854       }
3855     }
3856   }
3857   EndDecl();
3858 }
3859 
3860 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3861   DeclareObjectEntity(std::get<parser::Name>(x.t));
3862 }
3863 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3864   DeclareObjectEntity(std::get<parser::Name>(x.t));
3865 }
3866 
3867 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3868   // Defer inspection of initializers to Initialization() so that the
3869   // symbol being initialized will be available within the initialization
3870   // expression.
3871   return false;
3872 }
3873 
3874 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3875   const auto &name{std::get<parser::ObjectName>(x.t)};
3876   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3877   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3878   symbol.ReplaceName(name.source);
3879   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3880     if (ConvertToObjectEntity(symbol)) {
3881       Initialization(name, *init, false);
3882     }
3883   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3884     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3885   }
3886 }
3887 
3888 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3889   const auto &name{std::get<parser::Name>(x.t)};
3890   if (const auto &deferredShapeSpecs{
3891           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3892     CHECK(arraySpec().empty());
3893     BeginArraySpec();
3894     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3895     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3896     symbol.ReplaceName(name.source);
3897     EndArraySpec();
3898   } else {
3899     HandleAttributeStmt(Attr::POINTER, std::get<parser::Name>(x.t));
3900   }
3901 }
3902 
3903 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3904   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3905   auto &name{std::get<parser::Name>(x.t)};
3906   Symbol *symbol;
3907   if (kind == parser::BindEntity::Kind::Object) {
3908     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3909   } else {
3910     symbol = &MakeCommonBlockSymbol(name);
3911     symbol->attrs().set(Attr::BIND_C);
3912   }
3913   SetBindNameOn(*symbol);
3914   return false;
3915 }
3916 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3917   inOldStyleParameterStmt_ = true;
3918   Walk(x.v);
3919   inOldStyleParameterStmt_ = false;
3920   return false;
3921 }
3922 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3923   auto &name{std::get<parser::NamedConstant>(x.t).v};
3924   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3925   if (!ConvertToObjectEntity(symbol) ||
3926       symbol.test(Symbol::Flag::CrayPointer) ||
3927       symbol.test(Symbol::Flag::CrayPointee)) {
3928     SayWithDecl(
3929         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3930     return false;
3931   }
3932   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3933   auto &details{symbol.get<ObjectEntityDetails>()};
3934   if (inOldStyleParameterStmt_) {
3935     // non-standard extension PARAMETER statement (no parentheses)
3936     Walk(expr);
3937     auto folded{EvaluateExpr(expr)};
3938     if (details.type()) {
3939       SayWithDecl(name, symbol,
3940           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3941     } else if (folded) {
3942       auto at{expr.thing.value().source};
3943       if (evaluate::IsActuallyConstant(*folded)) {
3944         if (const auto *type{currScope().GetType(*folded)}) {
3945           if (type->IsPolymorphic()) {
3946             Say(at, "The expression must not be polymorphic"_err_en_US);
3947           } else if (auto shape{ToArraySpec(
3948                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3949             // The type of the named constant is assumed from the expression.
3950             details.set_type(*type);
3951             details.set_init(std::move(*folded));
3952             details.set_shape(std::move(*shape));
3953           } else {
3954             Say(at, "The expression must have constant shape"_err_en_US);
3955           }
3956         } else {
3957           Say(at, "The expression must have a known type"_err_en_US);
3958         }
3959       } else {
3960         Say(at, "The expression must be a constant of known type"_err_en_US);
3961       }
3962     }
3963   } else {
3964     // standard-conforming PARAMETER statement (with parentheses)
3965     ApplyImplicitRules(symbol);
3966     Walk(expr);
3967     if (auto converted{EvaluateNonPointerInitializer(
3968             symbol, expr, expr.thing.value().source)}) {
3969       details.set_init(std::move(*converted));
3970     }
3971   }
3972   return false;
3973 }
3974 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3975   const parser::Name &name{x.v};
3976   if (!FindSymbol(name)) {
3977     Say(name, "Named constant '%s' not found"_err_en_US);
3978   } else {
3979     CheckUseError(name);
3980   }
3981   return false;
3982 }
3983 
3984 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3985   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3986   Symbol *symbol{FindSymbol(name)};
3987   if (symbol && !symbol->has<UnknownDetails>()) {
3988     // Contrary to named constants appearing in a PARAMETER statement,
3989     // enumerator names should not have their type, dimension or any other
3990     // attributes defined before they are declared in the enumerator statement,
3991     // with the exception of accessibility.
3992     // This is not explicitly forbidden by the standard, but they are scalars
3993     // which type is left for the compiler to chose, so do not let users try to
3994     // tamper with that.
3995     SayAlreadyDeclared(name, *symbol);
3996     symbol = nullptr;
3997   } else {
3998     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3999     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
4000     symbol->SetType(context().MakeNumericType(
4001         TypeCategory::Integer, evaluate::CInteger::kind));
4002   }
4003 
4004   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
4005           enumerator.t)}) {
4006     Walk(*init); // Resolve names in expression before evaluation.
4007     if (auto value{EvaluateInt64(context(), *init)}) {
4008       // Cast all init expressions to C_INT so that they can then be
4009       // safely incremented (see 7.6 Note 2).
4010       enumerationState_.value = static_cast<int>(*value);
4011     } else {
4012       Say(name,
4013           "Enumerator value could not be computed "
4014           "from the given expression"_err_en_US);
4015       // Prevent resolution of next enumerators value
4016       enumerationState_.value = std::nullopt;
4017     }
4018   }
4019 
4020   if (symbol) {
4021     if (enumerationState_.value) {
4022       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
4023           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
4024     } else {
4025       context().SetError(*symbol);
4026     }
4027   }
4028 
4029   if (enumerationState_.value) {
4030     (*enumerationState_.value)++;
4031   }
4032   return false;
4033 }
4034 
4035 void DeclarationVisitor::Post(const parser::EnumDef &) {
4036   enumerationState_ = EnumeratorState{};
4037 }
4038 
4039 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
4040   Attr attr{AccessSpecToAttr(x)};
4041   if (!NonDerivedTypeScope().IsModule()) { // C817
4042     Say(currStmtSource().value(),
4043         "%s attribute may only appear in the specification part of a module"_err_en_US,
4044         EnumToString(attr));
4045   }
4046   CheckAndSet(attr);
4047   return false;
4048 }
4049 
4050 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
4051   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
4052 }
4053 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
4054   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
4055 }
4056 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
4057   HandleAttributeStmt(Attr::EXTERNAL, x.v);
4058   for (const auto &name : x.v) {
4059     auto *symbol{FindSymbol(name)};
4060     if (!ConvertToProcEntity(DEREF(symbol))) {
4061       SayWithDecl(
4062           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
4063     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
4064       Say(symbol->name(),
4065           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
4066           symbol->name());
4067     }
4068   }
4069   return false;
4070 }
4071 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
4072   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
4073   auto &names{std::get<std::list<parser::Name>>(x.t)};
4074   return CheckNotInBlock("INTENT") && // C1107
4075       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
4076 }
4077 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
4078   HandleAttributeStmt(Attr::INTRINSIC, x.v);
4079   for (const auto &name : x.v) {
4080     if (!IsIntrinsic(name.source, std::nullopt)) {
4081       Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
4082     }
4083     auto &symbol{DEREF(FindSymbol(name))};
4084     if (symbol.has<GenericDetails>()) {
4085       // Generic interface is extending intrinsic; ok
4086     } else if (!ConvertToProcEntity(symbol)) {
4087       SayWithDecl(
4088           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
4089     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
4090       Say(symbol.name(),
4091           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
4092           symbol.name());
4093     } else if (symbol.GetType()) {
4094       // These warnings are worded so that they should make sense in either
4095       // order.
4096       Say(symbol.name(),
4097           "Explicit type declaration ignored for intrinsic function '%s'"_warn_en_US,
4098           symbol.name())
4099           .Attach(name.source,
4100               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
4101               name.source);
4102     }
4103   }
4104   return false;
4105 }
4106 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
4107   return CheckNotInBlock("OPTIONAL") && // C1107
4108       HandleAttributeStmt(Attr::OPTIONAL, x.v);
4109 }
4110 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
4111   return HandleAttributeStmt(Attr::PROTECTED, x.v);
4112 }
4113 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
4114   return CheckNotInBlock("VALUE") && // C1107
4115       HandleAttributeStmt(Attr::VALUE, x.v);
4116 }
4117 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
4118   return HandleAttributeStmt(Attr::VOLATILE, x.v);
4119 }
4120 // Handle a statement that sets an attribute on a list of names.
4121 bool DeclarationVisitor::HandleAttributeStmt(
4122     Attr attr, const std::list<parser::Name> &names) {
4123   for (const auto &name : names) {
4124     HandleAttributeStmt(attr, name);
4125   }
4126   return false;
4127 }
4128 Symbol &DeclarationVisitor::HandleAttributeStmt(
4129     Attr attr, const parser::Name &name) {
4130   auto *symbol{FindInScope(name)};
4131   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
4132     // these can be set on a symbol that is host-assoc or use-assoc
4133     if (!symbol &&
4134         (currScope().kind() == Scope::Kind::Subprogram ||
4135             currScope().kind() == Scope::Kind::Block)) {
4136       if (auto *hostSymbol{FindSymbol(name)}) {
4137         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
4138       }
4139     }
4140   } else if (symbol && symbol->has<UseDetails>()) {
4141     Say(currStmtSource().value(),
4142         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
4143         EnumToString(attr), name.source);
4144     return *symbol;
4145   }
4146   if (!symbol) {
4147     symbol = &MakeSymbol(name, EntityDetails{});
4148   }
4149   symbol->attrs().set(attr);
4150   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
4151   return *symbol;
4152 }
4153 // C1107
4154 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
4155   if (currScope().kind() == Scope::Kind::Block) {
4156     Say(MessageFormattedText{
4157         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
4158     return false;
4159   } else {
4160     return true;
4161   }
4162 }
4163 
4164 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
4165   CHECK(objectDeclAttr_);
4166   const auto &name{std::get<parser::ObjectName>(x.t)};
4167   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
4168 }
4169 
4170 // Declare an entity not yet known to be an object or proc.
4171 Symbol &DeclarationVisitor::DeclareUnknownEntity(
4172     const parser::Name &name, Attrs attrs) {
4173   if (!arraySpec().empty() || !coarraySpec().empty()) {
4174     return DeclareObjectEntity(name, attrs);
4175   } else {
4176     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
4177     if (auto *type{GetDeclTypeSpec()}) {
4178       SetType(name, *type);
4179     }
4180     charInfo_.length.reset();
4181     if (symbol.attrs().test(Attr::EXTERNAL)) {
4182       ConvertToProcEntity(symbol);
4183     }
4184     SetBindNameOn(symbol);
4185     return symbol;
4186   }
4187 }
4188 
4189 bool DeclarationVisitor::HasCycle(
4190     const Symbol &procSymbol, const ProcInterface &interface) {
4191   SourceOrderedSymbolSet procsInCycle;
4192   procsInCycle.insert(procSymbol);
4193   const ProcInterface *thisInterface{&interface};
4194   bool haveInterface{true};
4195   while (haveInterface) {
4196     haveInterface = false;
4197     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
4198       if (procsInCycle.count(*interfaceSymbol) > 0) {
4199         for (const auto &procInCycle : procsInCycle) {
4200           Say(procInCycle->name(),
4201               "The interface for procedure '%s' is recursively "
4202               "defined"_err_en_US,
4203               procInCycle->name());
4204           context().SetError(*procInCycle);
4205         }
4206         return true;
4207       } else if (const auto *procDetails{
4208                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
4209         haveInterface = true;
4210         thisInterface = &procDetails->interface();
4211         procsInCycle.insert(*interfaceSymbol);
4212       }
4213     }
4214   }
4215   return false;
4216 }
4217 
4218 Symbol &DeclarationVisitor::DeclareProcEntity(
4219     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
4220   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
4221   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
4222     if (details->IsInterfaceSet()) {
4223       SayWithDecl(name, symbol,
4224           "The interface for procedure '%s' has already been "
4225           "declared"_err_en_US);
4226       context().SetError(symbol);
4227     } else if (HasCycle(symbol, interface)) {
4228       return symbol;
4229     } else if (interface.type()) {
4230       symbol.set(Symbol::Flag::Function);
4231     } else if (interface.symbol()) {
4232       if (interface.symbol()->test(Symbol::Flag::Function)) {
4233         symbol.set(Symbol::Flag::Function);
4234       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
4235         symbol.set(Symbol::Flag::Subroutine);
4236       }
4237     }
4238     details->set_interface(interface);
4239     SetBindNameOn(symbol);
4240     SetPassNameOn(symbol);
4241   }
4242   return symbol;
4243 }
4244 
4245 Symbol &DeclarationVisitor::DeclareObjectEntity(
4246     const parser::Name &name, Attrs attrs) {
4247   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
4248   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
4249     if (auto *type{GetDeclTypeSpec()}) {
4250       SetType(name, *type);
4251     }
4252     if (!arraySpec().empty()) {
4253       if (details->IsArray()) {
4254         if (!context().HasError(symbol)) {
4255           Say(name,
4256               "The dimensions of '%s' have already been declared"_err_en_US);
4257           context().SetError(symbol);
4258         }
4259       } else {
4260         details->set_shape(arraySpec());
4261       }
4262     }
4263     if (!coarraySpec().empty()) {
4264       if (details->IsCoarray()) {
4265         if (!context().HasError(symbol)) {
4266           Say(name,
4267               "The codimensions of '%s' have already been declared"_err_en_US);
4268           context().SetError(symbol);
4269         }
4270       } else {
4271         details->set_coshape(coarraySpec());
4272       }
4273     }
4274     SetBindNameOn(symbol);
4275   }
4276   ClearArraySpec();
4277   ClearCoarraySpec();
4278   charInfo_.length.reset();
4279   return symbol;
4280 }
4281 
4282 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
4283   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
4284 }
4285 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
4286   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
4287 }
4288 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
4289   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
4290 }
4291 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
4292   SetDeclTypeSpec(MakeLogicalType(x.kind));
4293 }
4294 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
4295   if (!charInfo_.length) {
4296     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
4297   }
4298   if (!charInfo_.kind) {
4299     charInfo_.kind =
4300         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
4301   }
4302   SetDeclTypeSpec(currScope().MakeCharacterType(
4303       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
4304   charInfo_ = {};
4305 }
4306 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
4307   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
4308   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
4309   if (intKind &&
4310       !evaluate::IsValidKindOfIntrinsicType(
4311           TypeCategory::Character, *intKind)) { // C715, C719
4312     Say(currStmtSource().value(),
4313         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
4314     charInfo_.kind = std::nullopt; // prevent further errors
4315   }
4316   if (x.length) {
4317     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
4318   }
4319 }
4320 void DeclarationVisitor::Post(const parser::CharLength &x) {
4321   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
4322     charInfo_.length = ParamValue{
4323         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
4324   } else {
4325     charInfo_.length = GetParamValue(
4326         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
4327   }
4328 }
4329 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
4330   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
4331     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
4332   }
4333 }
4334 
4335 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
4336   if (const auto *kind{std::get_if<
4337           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
4338           &x.u)}) {
4339     const parser::Name &name{kind->thing.thing.thing};
4340     if (!FindSymbol(name)) {
4341       Say(name, "Parameter '%s' not found"_err_en_US);
4342     }
4343   }
4344   return false;
4345 }
4346 
4347 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
4348   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
4349   return true;
4350 }
4351 
4352 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
4353   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
4354   if (const Symbol * derivedSymbol{derivedName.symbol}) {
4355     CheckForAbstractType(*derivedSymbol); // C706
4356   }
4357 }
4358 
4359 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4360   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4361   return true;
4362 }
4363 
4364 void DeclarationVisitor::Post(
4365     const parser::DeclarationTypeSpec::Class &parsedClass) {
4366   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4367   if (auto spec{ResolveDerivedType(typeName)};
4368       spec && !IsExtensibleType(&*spec)) { // C705
4369     SayWithDecl(typeName, *typeName.symbol,
4370         "Non-extensible derived type '%s' may not be used with CLASS"
4371         " keyword"_err_en_US);
4372   }
4373 }
4374 
4375 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4376   const auto &typeName{std::get<parser::Name>(x.t)};
4377   auto spec{ResolveDerivedType(typeName)};
4378   if (!spec) {
4379     return;
4380   }
4381   bool seenAnyName{false};
4382   for (const auto &typeParamSpec :
4383       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4384     const auto &optKeyword{
4385         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4386     std::optional<SourceName> name;
4387     if (optKeyword) {
4388       seenAnyName = true;
4389       name = optKeyword->v.source;
4390     } else if (seenAnyName) {
4391       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4392       continue;
4393     }
4394     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4395     // The expressions in a derived type specifier whose values define
4396     // non-defaulted type parameters are evaluated (folded) in the enclosing
4397     // scope.  The KIND/LEN distinction is resolved later in
4398     // DerivedTypeSpec::CookParameters().
4399     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4400     if (!param.isExplicit() || param.GetExplicit()) {
4401       spec->AddRawParamValue(optKeyword, std::move(param));
4402     }
4403   }
4404 
4405   // The DerivedTypeSpec *spec is used initially as a search key.
4406   // If it turns out to have the same name and actual parameter
4407   // value expressions as another DerivedTypeSpec in the current
4408   // scope does, then we'll use that extant spec; otherwise, when this
4409   // spec is distinct from all derived types previously instantiated
4410   // in the current scope, this spec will be moved into that collection.
4411   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4412   auto category{GetDeclTypeSpecCategory()};
4413   if (dtDetails.isForwardReferenced()) {
4414     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4415     SetDeclTypeSpec(type);
4416     return;
4417   }
4418   // Normalize parameters to produce a better search key.
4419   spec->CookParameters(GetFoldingContext());
4420   if (!spec->MightBeParameterized()) {
4421     spec->EvaluateParameters(context());
4422   }
4423   if (const DeclTypeSpec *
4424       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4425     // This derived type and parameter expressions (if any) are already present
4426     // in this scope.
4427     SetDeclTypeSpec(*extant);
4428   } else {
4429     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4430     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4431     if (derived.MightBeParameterized() &&
4432         currScope().IsParameterizedDerivedType()) {
4433       // Defer instantiation; use the derived type's definition's scope.
4434       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4435     } else if (&currScope() == spec->typeSymbol().scope()) {
4436       // Direct recursive use of a type in the definition of one of its
4437       // components: defer instantiation
4438     } else {
4439       auto restorer{
4440           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4441       derived.Instantiate(currScope());
4442     }
4443     SetDeclTypeSpec(type);
4444   }
4445   // Capture the DerivedTypeSpec in the parse tree for use in building
4446   // structure constructor expressions.
4447   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4448 }
4449 
4450 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4451   const auto &typeName{rec.v};
4452   if (auto spec{ResolveDerivedType(typeName)}) {
4453     spec->CookParameters(GetFoldingContext());
4454     spec->EvaluateParameters(context());
4455     if (const DeclTypeSpec *
4456         extant{currScope().FindInstantiatedDerivedType(
4457             *spec, DeclTypeSpec::TypeDerived)}) {
4458       SetDeclTypeSpec(*extant);
4459     } else {
4460       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4461           typeName.source);
4462     }
4463   }
4464 }
4465 
4466 // The descendents of DerivedTypeDef in the parse tree are visited directly
4467 // in this Pre() routine so that recursive use of the derived type can be
4468 // supported in the components.
4469 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4470   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4471   Walk(stmt);
4472   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4473   auto &scope{currScope()};
4474   CHECK(scope.symbol());
4475   CHECK(scope.symbol()->scope() == &scope);
4476   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4477   details.set_isForwardReferenced(false);
4478   std::set<SourceName> paramNames;
4479   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4480     details.add_paramName(paramName.source);
4481     auto *symbol{FindInScope(scope, paramName)};
4482     if (!symbol) {
4483       Say(paramName,
4484           "No definition found for type parameter '%s'"_err_en_US); // C742
4485       // No symbol for a type param.  Create one and mark it as containing an
4486       // error to improve subsequent semantic processing
4487       BeginAttrs();
4488       Symbol *typeParam{MakeTypeSymbol(
4489           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4490       context().SetError(*typeParam);
4491       EndAttrs();
4492     } else if (!symbol->has<TypeParamDetails>()) {
4493       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4494           *symbol, "Definition of '%s'"_en_US); // C741
4495     }
4496     if (!paramNames.insert(paramName.source).second) {
4497       Say(paramName,
4498           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4499     }
4500   }
4501   for (const auto &[name, symbol] : currScope()) {
4502     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4503       SayDerivedType(name,
4504           "'%s' is not a type parameter of this derived type"_err_en_US,
4505           currScope()); // C741
4506     }
4507   }
4508   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4509   const auto &componentDefs{
4510       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4511   Walk(componentDefs);
4512   if (derivedTypeInfo_.sequence) {
4513     details.set_sequence(true);
4514     if (componentDefs.empty()) { // C740
4515       Say(stmt.source,
4516           "A sequence type must have at least one component"_err_en_US);
4517     }
4518     if (!details.paramNames().empty()) { // C740
4519       Say(stmt.source,
4520           "A sequence type may not have type parameters"_err_en_US);
4521     }
4522     if (derivedTypeInfo_.extends) { // C735
4523       Say(stmt.source,
4524           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4525     }
4526   }
4527   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4528   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4529   derivedTypeInfo_ = {};
4530   PopScope();
4531   return false;
4532 }
4533 
4534 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4535   return BeginAttrs();
4536 }
4537 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4538   auto &name{std::get<parser::Name>(x.t)};
4539   // Resolve the EXTENDS() clause before creating the derived
4540   // type's symbol to foil attempts to recursively extend a type.
4541   auto *extendsName{derivedTypeInfo_.extends};
4542   std::optional<DerivedTypeSpec> extendsType{
4543       ResolveExtendsType(name, extendsName)};
4544   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4545   symbol.ReplaceName(name.source);
4546   derivedTypeInfo_.type = &symbol;
4547   PushScope(Scope::Kind::DerivedType, &symbol);
4548   if (extendsType) {
4549     // Declare the "parent component"; private if the type is.
4550     // Any symbol stored in the EXTENDS() clause is temporarily
4551     // hidden so that a new symbol can be created for the parent
4552     // component without producing spurious errors about already
4553     // existing.
4554     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4555     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4556     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4557       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4558       comp.attrs().set(
4559           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4560       comp.set(Symbol::Flag::ParentComp);
4561       DeclTypeSpec &type{currScope().MakeDerivedType(
4562           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4563       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4564       comp.SetType(type);
4565       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4566       details.add_component(comp);
4567     }
4568   }
4569   EndAttrs();
4570 }
4571 
4572 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4573   auto *type{GetDeclTypeSpec()};
4574   auto attr{std::get<common::TypeParamAttr>(x.t)};
4575   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4576     auto &name{std::get<parser::Name>(decl.t)};
4577     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4578       SetType(name, *type);
4579       if (auto &init{
4580               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4581         if (auto maybeExpr{EvaluateNonPointerInitializer(
4582                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4583           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4584             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4585           }
4586         }
4587       }
4588     }
4589   }
4590   EndDecl();
4591 }
4592 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4593   if (derivedTypeInfo_.extends) {
4594     Say(currStmtSource().value(),
4595         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4596   } else {
4597     derivedTypeInfo_.extends = &x.v;
4598   }
4599   return false;
4600 }
4601 
4602 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4603   if (!currScope().parent().IsModule()) {
4604     Say("PRIVATE is only allowed in a derived type that is"
4605         " in a module"_err_en_US); // C766
4606   } else if (derivedTypeInfo_.sawContains) {
4607     derivedTypeInfo_.privateBindings = true;
4608   } else if (!derivedTypeInfo_.privateComps) {
4609     derivedTypeInfo_.privateComps = true;
4610   } else {
4611     Say("PRIVATE may not appear more than once in"
4612         " derived type components"_warn_en_US); // C738
4613   }
4614   return false;
4615 }
4616 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4617   if (derivedTypeInfo_.sequence) {
4618     Say("SEQUENCE may not appear more than once in"
4619         " derived type components"_warn_en_US); // C738
4620   }
4621   derivedTypeInfo_.sequence = true;
4622   return false;
4623 }
4624 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4625   const auto &name{std::get<parser::Name>(x.t)};
4626   auto attrs{GetAttrs()};
4627   if (derivedTypeInfo_.privateComps &&
4628       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4629     attrs.set(Attr::PRIVATE);
4630   }
4631   if (const auto *declType{GetDeclTypeSpec()}) {
4632     if (const auto *derived{declType->AsDerived()}) {
4633       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4634         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4635           Say("Recursive use of the derived type requires "
4636               "POINTER or ALLOCATABLE"_err_en_US);
4637         }
4638       }
4639       // TODO: This would be more appropriate in CheckDerivedType()
4640       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4641         std::string ultimateName{it.BuildResultDesignatorName()};
4642         // Strip off the leading "%"
4643         if (ultimateName.length() > 1) {
4644           ultimateName.erase(0, 1);
4645           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4646             evaluate::AttachDeclaration(
4647                 Say(name.source,
4648                     "A component with a POINTER or ALLOCATABLE attribute may "
4649                     "not "
4650                     "be of a type with a coarray ultimate component (named "
4651                     "'%s')"_err_en_US,
4652                     ultimateName),
4653                 derived->typeSymbol());
4654           }
4655           if (!arraySpec().empty() || !coarraySpec().empty()) {
4656             evaluate::AttachDeclaration(
4657                 Say(name.source,
4658                     "An array or coarray component may not be of a type with a "
4659                     "coarray ultimate component (named '%s')"_err_en_US,
4660                     ultimateName),
4661                 derived->typeSymbol());
4662           }
4663         }
4664       }
4665     }
4666   }
4667   if (OkToAddComponent(name)) {
4668     auto &symbol{DeclareObjectEntity(name, attrs)};
4669     if (symbol.has<ObjectEntityDetails>()) {
4670       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4671         Initialization(name, *init, true);
4672       }
4673     }
4674     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4675   }
4676   ClearArraySpec();
4677   ClearCoarraySpec();
4678 }
4679 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4680   // Replace "%FILL" with a distinct generated name
4681   const auto &name{std::get<parser::Name>(x.t)};
4682   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4683   if (OkToAddComponent(name)) {
4684     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4685     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4686   }
4687   ClearArraySpec();
4688 }
4689 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &x) {
4690   CHECK(!interfaceName_);
4691   const auto &procAttrSpec{std::get<std::list<parser::ProcAttrSpec>>(x.t)};
4692   for (const parser::ProcAttrSpec &procAttr : procAttrSpec) {
4693     if (auto *bindC{std::get_if<parser::LanguageBindingSpec>(&procAttr.u)}) {
4694       if (bindC->v.has_value()) {
4695         hasBindCName_ = true;
4696         break;
4697       }
4698     }
4699   }
4700   return BeginDecl();
4701 }
4702 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4703   interfaceName_ = nullptr;
4704   hasBindCName_ = false;
4705   EndDecl();
4706 }
4707 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4708   // Overrides parse tree traversal so as to handle attributes first,
4709   // so POINTER & ALLOCATABLE enable forward references to derived types.
4710   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4711   set_allowForwardReferenceToDerivedType(
4712       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4713   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4714   set_allowForwardReferenceToDerivedType(false);
4715   if (derivedTypeInfo_.sequence) { // C740
4716     if (const auto *declType{GetDeclTypeSpec()}) {
4717       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4718         if (GetAttrs().test(Attr::POINTER) &&
4719             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4720           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4721             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_port_en_US);
4722           }
4723         } else {
4724           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4725         }
4726       }
4727     }
4728   }
4729   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4730   return false;
4731 }
4732 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4733   CHECK(!interfaceName_);
4734   return true;
4735 }
4736 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4737   interfaceName_ = nullptr;
4738 }
4739 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4740   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4741     return !NameIsKnownOrIntrinsic(*name);
4742   }
4743   return true;
4744 }
4745 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4746   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4747     interfaceName_ = name;
4748     NoteInterfaceName(*name);
4749   }
4750 }
4751 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4752   const auto &name{std::get<parser::Name>(x.t)};
4753   ProcInterface interface;
4754   if (interfaceName_) {
4755     interface.set_symbol(*interfaceName_->symbol);
4756   } else if (auto *type{GetDeclTypeSpec()}) {
4757     interface.set_type(*type);
4758   }
4759   auto attrs{HandleSaveName(name.source, GetAttrs())};
4760   DerivedTypeDetails *dtDetails{nullptr};
4761   if (Symbol * symbol{currScope().symbol()}) {
4762     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4763   }
4764   if (!dtDetails) {
4765     attrs.set(Attr::EXTERNAL);
4766   }
4767   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4768   symbol.ReplaceName(name.source);
4769   if (dtDetails) {
4770     dtDetails->add_component(symbol);
4771   }
4772   if (hasBindCName_ && (IsPointer(symbol) || IsDummy(symbol))) {
4773     Say(symbol.name(),
4774         "BIND(C) procedure with NAME= specified can neither have POINTER attribute nor be a dummy procedure"_err_en_US);
4775   }
4776 }
4777 
4778 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4779   derivedTypeInfo_.sawContains = true;
4780   return true;
4781 }
4782 
4783 // Resolve binding names from type-bound generics, saved in genericBindings_.
4784 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4785   // track specifics seen for the current generic to detect duplicates:
4786   const Symbol *currGeneric{nullptr};
4787   std::set<SourceName> specifics;
4788   for (const auto &[generic, bindingName] : genericBindings_) {
4789     if (generic != currGeneric) {
4790       currGeneric = generic;
4791       specifics.clear();
4792     }
4793     auto [it, inserted]{specifics.insert(bindingName->source)};
4794     if (!inserted) {
4795       Say(*bindingName, // C773
4796           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4797           bindingName->source, generic->name())
4798           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4799       continue;
4800     }
4801     auto *symbol{FindInTypeOrParents(*bindingName)};
4802     if (!symbol) {
4803       Say(*bindingName, // C772
4804           "Binding name '%s' not found in this derived type"_err_en_US);
4805     } else if (!symbol->has<ProcBindingDetails>()) {
4806       SayWithDecl(*bindingName, *symbol, // C772
4807           "'%s' is not the name of a specific binding of this type"_err_en_US);
4808     } else {
4809       generic->get<GenericDetails>().AddSpecificProc(
4810           *symbol, bindingName->source);
4811     }
4812   }
4813   genericBindings_.clear();
4814 }
4815 
4816 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4817   if (derivedTypeInfo_.sequence) {
4818     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4819   }
4820 }
4821 
4822 void DeclarationVisitor::Post(
4823     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4824   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4825     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4826   }
4827   for (auto &declaration : x.declarations) {
4828     auto &bindingName{std::get<parser::Name>(declaration.t)};
4829     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4830     const parser::Name &procedureName{optName ? *optName : bindingName};
4831     Symbol *procedure{FindSymbol(procedureName)};
4832     if (!procedure) {
4833       procedure = NoteInterfaceName(procedureName);
4834     }
4835     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4836       SetPassNameOn(*s);
4837       if (GetAttrs().test(Attr::DEFERRED)) {
4838         context().SetError(*s);
4839       }
4840     }
4841   }
4842 }
4843 
4844 void DeclarationVisitor::CheckBindings(
4845     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4846   CHECK(currScope().IsDerivedType());
4847   for (auto &declaration : tbps.declarations) {
4848     auto &bindingName{std::get<parser::Name>(declaration.t)};
4849     if (Symbol * binding{FindInScope(bindingName)}) {
4850       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4851         const Symbol *procedure{FindSubprogram(details->symbol())};
4852         if (!CanBeTypeBoundProc(procedure)) {
4853           if (details->symbol().name() != binding->name()) {
4854             Say(binding->name(),
4855                 "The binding of '%s' ('%s') must be either an accessible "
4856                 "module procedure or an external procedure with "
4857                 "an explicit interface"_err_en_US,
4858                 binding->name(), details->symbol().name());
4859           } else {
4860             Say(binding->name(),
4861                 "'%s' must be either an accessible module procedure "
4862                 "or an external procedure with an explicit interface"_err_en_US,
4863                 binding->name());
4864           }
4865           context().SetError(*binding);
4866         }
4867       }
4868     }
4869   }
4870 }
4871 
4872 void DeclarationVisitor::Post(
4873     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4874   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4875     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4876   }
4877   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4878     for (auto &bindingName : x.bindingNames) {
4879       if (auto *s{
4880               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4881         SetPassNameOn(*s);
4882         if (!GetAttrs().test(Attr::DEFERRED)) {
4883           context().SetError(*s);
4884         }
4885       }
4886     }
4887   }
4888 }
4889 
4890 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4891   if (currScope().IsDerivedType() && currScope().symbol()) {
4892     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4893       for (const auto &subrName : x.v) {
4894         if (const auto *name{ResolveName(subrName)}) {
4895           auto pair{
4896               details->finals().emplace(name->source, DEREF(name->symbol))};
4897           if (!pair.second) { // C787
4898             Say(name->source,
4899                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4900                 name->source)
4901                 .Attach(pair.first->first,
4902                     "earlier appearance of this FINAL subroutine"_en_US);
4903           }
4904         }
4905       }
4906     }
4907   }
4908 }
4909 
4910 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4911   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4912   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4913   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4914   auto info{GenericSpecInfo{genericSpec.value()}};
4915   SourceName symbolName{info.symbolName()};
4916   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4917                             : derivedTypeInfo_.privateBindings};
4918   auto *genericSymbol{FindInScope(symbolName)};
4919   if (genericSymbol) {
4920     if (!genericSymbol->has<GenericDetails>()) {
4921       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4922     }
4923   } else {
4924     // look in parent types:
4925     Symbol *inheritedSymbol{nullptr};
4926     for (const auto &name : GetAllNames(context(), symbolName)) {
4927       inheritedSymbol = currScope().FindComponent(SourceName{name});
4928       if (inheritedSymbol) {
4929         break;
4930       }
4931     }
4932     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4933       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4934     }
4935   }
4936   if (genericSymbol) {
4937     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4938   } else {
4939     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4940     if (!genericSymbol) {
4941       return false;
4942     }
4943     if (isPrivate) {
4944       genericSymbol->attrs().set(Attr::PRIVATE);
4945     }
4946   }
4947   for (const parser::Name &bindingName : bindingNames) {
4948     genericBindings_.emplace(genericSymbol, &bindingName);
4949   }
4950   info.Resolve(genericSymbol);
4951   return false;
4952 }
4953 
4954 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4955 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4956   const auto &structureStatement{
4957       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4958   auto saveDerivedTypeInfo{derivedTypeInfo_};
4959   derivedTypeInfo_ = {};
4960   derivedTypeInfo_.isStructure = true;
4961   derivedTypeInfo_.sequence = true;
4962   Scope *previousStructure{nullptr};
4963   if (saveDerivedTypeInfo.isStructure) {
4964     previousStructure = &currScope();
4965     PopScope();
4966   }
4967   const parser::StructureStmt &structStmt{structureStatement.statement};
4968   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4969   if (!name) {
4970     // Construct a distinct generated name for an anonymous structure
4971     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4972     mutableName.emplace(
4973         parser::Name{context().GetTempName(currScope()), nullptr});
4974   }
4975   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4976   symbol.ReplaceName(name->source);
4977   symbol.get<DerivedTypeDetails>().set_sequence(true);
4978   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4979   derivedTypeInfo_.type = &symbol;
4980   PushScope(Scope::Kind::DerivedType, &symbol);
4981   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4982   Walk(fields);
4983   PopScope();
4984   // Complete the definition
4985   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4986   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4987   derivedTypeSpec.CookParameters(GetFoldingContext());
4988   derivedTypeSpec.EvaluateParameters(context());
4989   DeclTypeSpec &type{currScope().MakeDerivedType(
4990       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4991   type.derivedTypeSpec().Instantiate(currScope());
4992   // Restore previous structure definition context, if any
4993   derivedTypeInfo_ = saveDerivedTypeInfo;
4994   if (previousStructure) {
4995     PushScope(*previousStructure);
4996   }
4997   // Handle any entity declarations on the STRUCTURE statement
4998   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4999   if (!decls.empty()) {
5000     BeginDecl();
5001     SetDeclTypeSpec(type);
5002     Walk(decls);
5003     EndDecl();
5004   }
5005   return false;
5006 }
5007 
5008 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
5009   Say("support for UNION"_todo_en_US); // TODO
5010   return true;
5011 }
5012 
5013 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
5014   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
5015           x.u)) {
5016     BeginDecl();
5017   }
5018   return true;
5019 }
5020 
5021 void DeclarationVisitor::Post(const parser::StructureField &x) {
5022   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
5023           x.u)) {
5024     EndDecl();
5025   }
5026 }
5027 
5028 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
5029   BeginDeclTypeSpec();
5030   return true;
5031 }
5032 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
5033   EndDeclTypeSpec();
5034 }
5035 
5036 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
5037   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
5038   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
5039   if (!type) {
5040     return false;
5041   }
5042   const DerivedTypeSpec *spec{type->AsDerived()};
5043   const Scope *typeScope{spec ? spec->scope() : nullptr};
5044   if (!typeScope) {
5045     return false;
5046   }
5047 
5048   // N.B C7102 is implicitly enforced by having inaccessible types not
5049   // being found in resolution.
5050   // More constraints are enforced in expression.cpp so that they
5051   // can apply to structure constructors that have been converted
5052   // from misparsed function references.
5053   for (const auto &component :
5054       std::get<std::list<parser::ComponentSpec>>(x.t)) {
5055     // Visit the component spec expression, but not the keyword, since
5056     // we need to resolve its symbol in the scope of the derived type.
5057     Walk(std::get<parser::ComponentDataSource>(component.t));
5058     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
5059       FindInTypeOrParents(*typeScope, kw->v);
5060     }
5061   }
5062   return false;
5063 }
5064 
5065 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
5066   for (const parser::BasedPointer &bp : x.v) {
5067     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
5068     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
5069     auto *pointer{FindSymbol(pointerName)};
5070     if (!pointer) {
5071       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
5072     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
5073       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
5074     } else if (pointer->Rank() > 0) {
5075       SayWithDecl(pointerName, *pointer,
5076           "Cray pointer '%s' must be a scalar"_err_en_US);
5077     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
5078       Say(pointerName,
5079           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
5080     }
5081     pointer->set(Symbol::Flag::CrayPointer);
5082     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
5083         context().defaultKinds().subscriptIntegerKind())};
5084     const auto *type{pointer->GetType()};
5085     if (!type) {
5086       pointer->SetType(pointerType);
5087     } else if (*type != pointerType) {
5088       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
5089           pointerName.source, pointerType.AsFortran());
5090     }
5091     if (ResolveName(pointeeName)) {
5092       Symbol &pointee{*pointeeName.symbol};
5093       if (pointee.has<UseDetails>()) {
5094         Say(pointeeName,
5095             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
5096         continue;
5097       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
5098         Say(pointeeName, "'%s' is not a variable"_err_en_US);
5099         continue;
5100       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
5101         Say(pointeeName,
5102             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
5103       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
5104         Say(pointeeName,
5105             "'%s' was already declared as a Cray pointee"_err_en_US);
5106       } else {
5107         pointee.set(Symbol::Flag::CrayPointee);
5108       }
5109       if (const auto *pointeeType{pointee.GetType()}) {
5110         if (const auto *derived{pointeeType->AsDerived()}) {
5111           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
5112             Say(pointeeName,
5113                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
5114           }
5115         }
5116       }
5117       // process the pointee array-spec, if present
5118       BeginArraySpec();
5119       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
5120       const auto &spec{arraySpec()};
5121       if (!spec.empty()) {
5122         auto &details{pointee.get<ObjectEntityDetails>()};
5123         if (details.shape().empty()) {
5124           details.set_shape(spec);
5125         } else {
5126           SayWithDecl(pointeeName, pointee,
5127               "Array spec was already declared for '%s'"_err_en_US);
5128         }
5129       }
5130       ClearArraySpec();
5131       currScope().add_crayPointer(pointeeName.source, *pointer);
5132     }
5133   }
5134   return false;
5135 }
5136 
5137 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
5138   if (!CheckNotInBlock("NAMELIST")) { // C1107
5139     return false;
5140   }
5141   const auto &groupName{std::get<parser::Name>(x.t)};
5142   auto *groupSymbol{FindInScope(groupName)};
5143   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
5144     groupSymbol = &MakeSymbol(groupName, NamelistDetails{});
5145     groupSymbol->ReplaceName(groupName.source);
5146   }
5147   // Name resolution of group items is deferred to FinishNamelists()
5148   // so that host association is handled correctly.
5149   GetDeferredDeclarationState(true)->namelistGroups.emplace_back(&x);
5150   return false;
5151 }
5152 
5153 void DeclarationVisitor::FinishNamelists() {
5154   if (auto *deferred{GetDeferredDeclarationState()}) {
5155     for (const parser::NamelistStmt::Group *group : deferred->namelistGroups) {
5156       if (auto *groupSymbol{FindInScope(std::get<parser::Name>(group->t))}) {
5157         if (auto *details{groupSymbol->detailsIf<NamelistDetails>()}) {
5158           for (const auto &name : std::get<std::list<parser::Name>>(group->t)) {
5159             auto *symbol{FindSymbol(name)};
5160             if (!symbol) {
5161               symbol = &MakeSymbol(name, ObjectEntityDetails{});
5162               ApplyImplicitRules(*symbol);
5163             } else if (!ConvertToObjectEntity(*symbol)) {
5164               SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
5165             }
5166             symbol->GetUltimate().set(Symbol::Flag::InNamelist);
5167             details->add_object(*symbol);
5168           }
5169         }
5170       }
5171     }
5172     deferred->namelistGroups.clear();
5173   }
5174 }
5175 
5176 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
5177   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
5178     auto *symbol{FindSymbol(*name)};
5179     if (!symbol) {
5180       Say(*name, "Namelist group '%s' not found"_err_en_US);
5181     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
5182       SayWithDecl(
5183           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
5184     }
5185   }
5186   return true;
5187 }
5188 
5189 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
5190   CheckNotInBlock("COMMON"); // C1107
5191   return true;
5192 }
5193 
5194 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
5195   BeginArraySpec();
5196   return true;
5197 }
5198 
5199 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
5200   const auto &name{std::get<parser::Name>(x.t)};
5201   DeclareObjectEntity(name);
5202   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
5203   if (!pair.second) {
5204     const SourceName &prev{*pair.first};
5205     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
5206         "Previous occurrence of '%s' in a COMMON block"_en_US);
5207   }
5208 }
5209 
5210 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
5211   // save equivalence sets to be processed after specification part
5212   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
5213     for (const std::list<parser::EquivalenceObject> &set : x.v) {
5214       specPartState_.equivalenceSets.push_back(&set);
5215     }
5216   }
5217   return false; // don't implicitly declare names yet
5218 }
5219 
5220 void DeclarationVisitor::CheckEquivalenceSets() {
5221   EquivalenceSets equivSets{context()};
5222   inEquivalenceStmt_ = true;
5223   for (const auto *set : specPartState_.equivalenceSets) {
5224     const auto &source{set->front().v.value().source};
5225     if (set->size() <= 1) { // R871
5226       Say(source, "Equivalence set must have more than one object"_err_en_US);
5227     }
5228     for (const parser::EquivalenceObject &object : *set) {
5229       const auto &designator{object.v.value()};
5230       // The designator was not resolved when it was encountered so do it now.
5231       // AnalyzeExpr causes array sections to be changed to substrings as needed
5232       Walk(designator);
5233       if (AnalyzeExpr(context(), designator)) {
5234         equivSets.AddToSet(designator);
5235       }
5236     }
5237     equivSets.FinishSet(source);
5238   }
5239   inEquivalenceStmt_ = false;
5240   for (auto &set : equivSets.sets()) {
5241     if (!set.empty()) {
5242       currScope().add_equivalenceSet(std::move(set));
5243     }
5244   }
5245   specPartState_.equivalenceSets.clear();
5246 }
5247 
5248 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
5249   if (x.v.empty()) {
5250     specPartState_.saveInfo.saveAll = currStmtSource();
5251     currScope().set_hasSAVE();
5252   } else {
5253     for (const parser::SavedEntity &y : x.v) {
5254       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
5255       const auto &name{std::get<parser::Name>(y.t)};
5256       if (kind == parser::SavedEntity::Kind::Common) {
5257         MakeCommonBlockSymbol(name);
5258         AddSaveName(specPartState_.saveInfo.commons, name.source);
5259       } else {
5260         HandleAttributeStmt(Attr::SAVE, name);
5261       }
5262     }
5263   }
5264   return false;
5265 }
5266 
5267 void DeclarationVisitor::CheckSaveStmts() {
5268   for (const SourceName &name : specPartState_.saveInfo.entities) {
5269     auto *symbol{FindInScope(name)};
5270     if (!symbol) {
5271       // error was reported
5272     } else if (specPartState_.saveInfo.saveAll) {
5273       // C889 - note that pgi, ifort, xlf do not enforce this constraint
5274       Say2(name,
5275           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_warn_en_US,
5276           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
5277     } else if (auto msg{CheckSaveAttr(*symbol)}) {
5278       Say(name, std::move(*msg));
5279       context().SetError(*symbol);
5280     } else {
5281       SetSaveAttr(*symbol);
5282     }
5283   }
5284   for (const SourceName &name : specPartState_.saveInfo.commons) {
5285     if (auto *symbol{currScope().FindCommonBlock(name)}) {
5286       auto &objects{symbol->get<CommonBlockDetails>().objects()};
5287       if (objects.empty()) {
5288         if (currScope().kind() != Scope::Kind::Block) {
5289           Say(name,
5290               "'%s' appears as a COMMON block in a SAVE statement but not in"
5291               " a COMMON statement"_err_en_US);
5292         } else { // C1108
5293           Say(name,
5294               "SAVE statement in BLOCK construct may not contain a"
5295               " common block name '%s'"_err_en_US);
5296         }
5297       } else {
5298         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
5299           SetSaveAttr(*object);
5300         }
5301       }
5302     }
5303   }
5304   if (specPartState_.saveInfo.saveAll) {
5305     // Apply SAVE attribute to applicable symbols
5306     for (auto pair : currScope()) {
5307       auto &symbol{*pair.second};
5308       if (!CheckSaveAttr(symbol)) {
5309         SetSaveAttr(symbol);
5310       }
5311     }
5312   }
5313   specPartState_.saveInfo = {};
5314 }
5315 
5316 // If SAVE attribute can't be set on symbol, return error message.
5317 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
5318     const Symbol &symbol) {
5319   if (IsDummy(symbol)) {
5320     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
5321   } else if (symbol.IsFuncResult()) {
5322     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
5323   } else if (symbol.has<ProcEntityDetails>() &&
5324       !symbol.attrs().test(Attr::POINTER)) {
5325     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
5326   } else if (IsAutomatic(symbol)) {
5327     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
5328   } else {
5329     return std::nullopt;
5330   }
5331 }
5332 
5333 // Record SAVEd names in specPartState_.saveInfo.entities.
5334 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
5335   if (attrs.test(Attr::SAVE)) {
5336     AddSaveName(specPartState_.saveInfo.entities, name);
5337   }
5338   return attrs;
5339 }
5340 
5341 // Record a name in a set of those to be saved.
5342 void DeclarationVisitor::AddSaveName(
5343     std::set<SourceName> &set, const SourceName &name) {
5344   auto pair{set.insert(name)};
5345   if (!pair.second) {
5346     Say2(name, "SAVE attribute was already specified on '%s'"_warn_en_US,
5347         *pair.first, "Previous specification of SAVE attribute"_en_US);
5348   }
5349 }
5350 
5351 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
5352 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
5353   if (!IsSaved(symbol)) {
5354     symbol.attrs().set(Attr::SAVE);
5355   }
5356 }
5357 
5358 // Check types of common block objects, now that they are known.
5359 void DeclarationVisitor::CheckCommonBlocks() {
5360   // check for empty common blocks
5361   for (const auto &pair : currScope().commonBlocks()) {
5362     const auto &symbol{*pair.second};
5363     if (symbol.get<CommonBlockDetails>().objects().empty() &&
5364         symbol.attrs().test(Attr::BIND_C)) {
5365       Say(symbol.name(),
5366           "'%s' appears as a COMMON block in a BIND statement but not in"
5367           " a COMMON statement"_err_en_US);
5368     }
5369   }
5370   // check objects in common blocks
5371   for (const auto &name : specPartState_.commonBlockObjects) {
5372     const auto *symbol{currScope().FindSymbol(name)};
5373     if (!symbol) {
5374       continue;
5375     }
5376     const auto &attrs{symbol->attrs()};
5377     if (attrs.test(Attr::ALLOCATABLE)) {
5378       Say(name,
5379           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
5380     } else if (attrs.test(Attr::BIND_C)) {
5381       Say(name,
5382           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
5383     } else if (IsNamedConstant(*symbol)) {
5384       Say(name,
5385           "A named constant '%s' may not appear in a COMMON block"_err_en_US);
5386     } else if (IsDummy(*symbol)) {
5387       Say(name,
5388           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5389     } else if (symbol->IsFuncResult()) {
5390       Say(name,
5391           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5392     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5393       if (type->category() == DeclTypeSpec::ClassStar) {
5394         Say(name,
5395             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5396       } else if (const auto *derived{type->AsDerived()}) {
5397         auto &typeSymbol{derived->typeSymbol()};
5398         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5399             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5400           Say(name,
5401               "Derived type '%s' in COMMON block must have the BIND or"
5402               " SEQUENCE attribute"_err_en_US);
5403         }
5404         CheckCommonBlockDerivedType(name, typeSymbol);
5405       }
5406     }
5407   }
5408   specPartState_.commonBlockObjects = {};
5409 }
5410 
5411 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5412   return Resolve(name, currScope().MakeCommonBlock(name.source));
5413 }
5414 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5415     const std::optional<parser::Name> &name) {
5416   if (name) {
5417     return MakeCommonBlockSymbol(*name);
5418   } else {
5419     return MakeCommonBlockSymbol(parser::Name{});
5420   }
5421 }
5422 
5423 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5424   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5425 }
5426 
5427 // Check if this derived type can be in a COMMON block.
5428 void DeclarationVisitor::CheckCommonBlockDerivedType(
5429     const SourceName &name, const Symbol &typeSymbol) {
5430   if (const auto *scope{typeSymbol.scope()}) {
5431     for (const auto &pair : *scope) {
5432       const Symbol &component{*pair.second};
5433       if (component.attrs().test(Attr::ALLOCATABLE)) {
5434         Say2(name,
5435             "Derived type variable '%s' may not appear in a COMMON block"
5436             " due to ALLOCATABLE component"_err_en_US,
5437             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5438         return;
5439       }
5440       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5441       if (component.test(Symbol::Flag::InDataStmt) ||
5442           (details && details->init())) {
5443         Say2(name,
5444             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5445             component.name(), "Component with default initialization"_en_US);
5446         return;
5447       }
5448       if (details) {
5449         if (const auto *type{details->type()}) {
5450           if (const auto *derived{type->AsDerived()}) {
5451             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5452           }
5453         }
5454       }
5455     }
5456   }
5457 }
5458 
5459 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5460     const parser::Name &name) {
5461   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5462           name.source.ToString())}) {
5463     // Unrestricted specific intrinsic function names (e.g., "cos")
5464     // are acceptable as procedure interfaces.  The presence of the
5465     // INTRINSIC flag will cause this symbol to have a complete interface
5466     // recreated for it later on demand, but capturing its result type here
5467     // will make GetType() return a correct result without having to
5468     // probe the intrinsics table again.
5469     Symbol &symbol{
5470         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5471     CHECK(interface->functionResult.has_value());
5472     evaluate::DynamicType dyType{
5473         DEREF(interface->functionResult->GetTypeAndShape()).type()};
5474     CHECK(common::IsNumericTypeCategory(dyType.category()));
5475     const DeclTypeSpec &typeSpec{
5476         MakeNumericType(dyType.category(), dyType.kind())};
5477     ProcEntityDetails details;
5478     ProcInterface procInterface;
5479     procInterface.set_type(typeSpec);
5480     details.set_interface(procInterface);
5481     symbol.set_details(std::move(details));
5482     symbol.set(Symbol::Flag::Function);
5483     if (interface->IsElemental()) {
5484       symbol.attrs().set(Attr::ELEMENTAL);
5485     }
5486     if (interface->IsPure()) {
5487       symbol.attrs().set(Attr::PURE);
5488     }
5489     Resolve(name, symbol);
5490     return true;
5491   } else {
5492     return false;
5493   }
5494 }
5495 
5496 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5497 bool DeclarationVisitor::PassesSharedLocalityChecks(
5498     const parser::Name &name, Symbol &symbol) {
5499   if (!IsVariableName(symbol)) {
5500     SayLocalMustBeVariable(name, symbol); // C1124
5501     return false;
5502   }
5503   if (symbol.owner() == currScope()) { // C1125 and C1126
5504     SayAlreadyDeclared(name, symbol);
5505     return false;
5506   }
5507   return true;
5508 }
5509 
5510 // Checks for locality-specs LOCAL and LOCAL_INIT
5511 bool DeclarationVisitor::PassesLocalityChecks(
5512     const parser::Name &name, Symbol &symbol) {
5513   if (IsAllocatable(symbol)) { // C1128
5514     SayWithDecl(name, symbol,
5515         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5516     return false;
5517   }
5518   if (IsOptional(symbol)) { // C1128
5519     SayWithDecl(name, symbol,
5520         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5521     return false;
5522   }
5523   if (IsIntentIn(symbol)) { // C1128
5524     SayWithDecl(name, symbol,
5525         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5526     return false;
5527   }
5528   if (IsFinalizable(symbol)) { // C1128
5529     SayWithDecl(name, symbol,
5530         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5531     return false;
5532   }
5533   if (evaluate::IsCoarray(symbol)) { // C1128
5534     SayWithDecl(
5535         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5536     return false;
5537   }
5538   if (const DeclTypeSpec * type{symbol.GetType()}) {
5539     if (type->IsPolymorphic() && IsDummy(symbol) &&
5540         !IsPointer(symbol)) { // C1128
5541       SayWithDecl(name, symbol,
5542           "Nonpointer polymorphic argument '%s' not allowed in a "
5543           "locality-spec"_err_en_US);
5544       return false;
5545     }
5546   }
5547   if (IsAssumedSizeArray(symbol)) { // C1128
5548     SayWithDecl(name, symbol,
5549         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5550     return false;
5551   }
5552   if (std::optional<Message> msg{WhyNotModifiable(symbol, currScope())}) {
5553     SayWithReason(name, symbol,
5554         "'%s' may not appear in a locality-spec because it is not "
5555         "definable"_err_en_US,
5556         std::move(*msg));
5557     return false;
5558   }
5559   return PassesSharedLocalityChecks(name, symbol);
5560 }
5561 
5562 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5563     const parser::Name &name) {
5564   Symbol *prev{FindSymbol(name)};
5565   if (!prev) {
5566     // Declare the name as an object in the enclosing scope so that
5567     // the name can't be repurposed there later as something else.
5568     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5569     ConvertToObjectEntity(*prev);
5570     ApplyImplicitRules(*prev);
5571   }
5572   return *prev;
5573 }
5574 
5575 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5576   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5577   if (!PassesLocalityChecks(name, prev)) {
5578     return nullptr;
5579   }
5580   return &MakeHostAssocSymbol(name, prev);
5581 }
5582 
5583 Symbol *DeclarationVisitor::DeclareStatementEntity(
5584     const parser::DoVariable &doVar,
5585     const std::optional<parser::IntegerTypeSpec> &type) {
5586   const parser::Name &name{doVar.thing.thing};
5587   const DeclTypeSpec *declTypeSpec{nullptr};
5588   if (auto *prev{FindSymbol(name)}) {
5589     if (prev->owner() == currScope()) {
5590       SayAlreadyDeclared(name, *prev);
5591       return nullptr;
5592     }
5593     name.symbol = nullptr;
5594     declTypeSpec = prev->GetType();
5595   }
5596   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5597   if (!symbol.has<ObjectEntityDetails>()) {
5598     return nullptr; // error was reported in DeclareEntity
5599   }
5600   if (type) {
5601     declTypeSpec = ProcessTypeSpec(*type);
5602   }
5603   if (declTypeSpec) {
5604     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5605     // declaration of this implied DO loop control variable.
5606     auto restorer{
5607         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5608     SetType(name, *declTypeSpec);
5609   } else {
5610     ApplyImplicitRules(symbol);
5611   }
5612   Symbol *result{Resolve(name, &symbol)};
5613   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5614   return result;
5615 }
5616 
5617 // Set the type of an entity or report an error.
5618 void DeclarationVisitor::SetType(
5619     const parser::Name &name, const DeclTypeSpec &type) {
5620   CHECK(name.symbol);
5621   auto &symbol{*name.symbol};
5622   if (charInfo_.length) { // Declaration has "*length" (R723)
5623     auto length{std::move(*charInfo_.length)};
5624     charInfo_.length.reset();
5625     if (type.category() == DeclTypeSpec::Character) {
5626       auto kind{type.characterTypeSpec().kind()};
5627       // Recurse with correct type.
5628       SetType(name,
5629           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5630       return;
5631     } else { // C753
5632       Say(name,
5633           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5634     }
5635   }
5636   auto *prevType{symbol.GetType()};
5637   if (!prevType) {
5638     symbol.SetType(type);
5639   } else if (symbol.has<UseDetails>()) {
5640     // error recovery case, redeclaration of use-associated name
5641   } else if (HadForwardRef(symbol)) {
5642     // error recovery after use of host-associated name
5643   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5644     SayWithDecl(
5645         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5646     context().SetError(symbol);
5647   } else if (type != *prevType) {
5648     SayWithDecl(name, symbol,
5649         "The type of '%s' has already been implicitly declared"_err_en_US);
5650     context().SetError(symbol);
5651   } else {
5652     symbol.set(Symbol::Flag::Implicit, false);
5653   }
5654 }
5655 
5656 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5657     const parser::Name &name) {
5658   Scope &outer{NonDerivedTypeScope()};
5659   Symbol *symbol{FindSymbol(outer, name)};
5660   Symbol *ultimate{symbol ? &symbol->GetUltimate() : nullptr};
5661   auto *generic{ultimate ? ultimate->detailsIf<GenericDetails>() : nullptr};
5662   if (generic) {
5663     if (Symbol * genDT{generic->derivedType()}) {
5664       symbol = genDT;
5665       generic = nullptr;
5666     }
5667   }
5668   if (!symbol || symbol->has<UnknownDetails>() ||
5669       (generic && &ultimate->owner() == &outer)) {
5670     if (allowForwardReferenceToDerivedType()) {
5671       if (!symbol) {
5672         symbol = &MakeSymbol(outer, name.source, Attrs{});
5673         Resolve(name, *symbol);
5674       } else if (generic) {
5675         // forward ref to type with later homonymous generic
5676         symbol = &outer.MakeSymbol(name.source, Attrs{}, UnknownDetails{});
5677         generic->set_derivedType(*symbol);
5678         name.symbol = symbol;
5679       }
5680       DerivedTypeDetails details;
5681       details.set_isForwardReferenced(true);
5682       symbol->set_details(std::move(details));
5683     } else { // C732
5684       Say(name, "Derived type '%s' not found"_err_en_US);
5685       return std::nullopt;
5686     }
5687   }
5688   if (CheckUseError(name)) {
5689     return std::nullopt;
5690   }
5691   symbol = &symbol->GetUltimate();
5692   if (symbol->has<DerivedTypeDetails>()) {
5693     return DerivedTypeSpec{name.source, *symbol};
5694   } else {
5695     Say(name, "'%s' is not a derived type"_err_en_US);
5696     return std::nullopt;
5697   }
5698 }
5699 
5700 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5701     const parser::Name &typeName, const parser::Name *extendsName) {
5702   if (!extendsName) {
5703     return std::nullopt;
5704   } else if (typeName.source == extendsName->source) {
5705     Say(extendsName->source,
5706         "Derived type '%s' cannot extend itself"_err_en_US);
5707     return std::nullopt;
5708   } else {
5709     return ResolveDerivedType(*extendsName);
5710   }
5711 }
5712 
5713 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5714   // The symbol is checked later by CheckExplicitInterface() and
5715   // CheckBindings().  It can be a forward reference.
5716   if (!NameIsKnownOrIntrinsic(name)) {
5717     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5718     Resolve(name, symbol);
5719   }
5720   return name.symbol;
5721 }
5722 
5723 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5724   if (const Symbol * symbol{name.symbol}) {
5725     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5726       Say(name,
5727           "'%s' must be an abstract interface or a procedure with "
5728           "an explicit interface"_err_en_US,
5729           symbol->name());
5730     }
5731   }
5732 }
5733 
5734 // Create a symbol for a type parameter, component, or procedure binding in
5735 // the current derived type scope. Return false on error.
5736 Symbol *DeclarationVisitor::MakeTypeSymbol(
5737     const parser::Name &name, Details &&details) {
5738   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5739 }
5740 Symbol *DeclarationVisitor::MakeTypeSymbol(
5741     const SourceName &name, Details &&details) {
5742   Scope &derivedType{currScope()};
5743   CHECK(derivedType.IsDerivedType());
5744   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5745     Say2(name,
5746         "Type parameter, component, or procedure binding '%s'"
5747         " already defined in this type"_err_en_US,
5748         *symbol, "Previous definition of '%s'"_en_US);
5749     return nullptr;
5750   } else {
5751     auto attrs{GetAttrs()};
5752     // Apply binding-private-stmt if present and this is a procedure binding
5753     if (derivedTypeInfo_.privateBindings &&
5754         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5755         std::holds_alternative<ProcBindingDetails>(details)) {
5756       attrs.set(Attr::PRIVATE);
5757     }
5758     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5759     if (result.has<TypeParamDetails>()) {
5760       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5761     }
5762     return &result;
5763   }
5764 }
5765 
5766 // Return true if it is ok to declare this component in the current scope.
5767 // Otherwise, emit an error and return false.
5768 bool DeclarationVisitor::OkToAddComponent(
5769     const parser::Name &name, const Symbol *extends) {
5770   for (const Scope *scope{&currScope()}; scope;) {
5771     CHECK(scope->IsDerivedType());
5772     if (auto *prev{FindInScope(*scope, name)}) {
5773       if (!context().HasError(*prev)) {
5774         parser::MessageFixedText msg;
5775         if (extends) {
5776           msg = "Type cannot be extended as it has a component named"
5777                 " '%s'"_err_en_US;
5778         } else if (prev->test(Symbol::Flag::ParentComp)) {
5779           msg = "'%s' is a parent type of this type and so cannot be"
5780                 " a component"_err_en_US;
5781         } else if (scope != &currScope()) {
5782           msg = "Component '%s' is already declared in a parent of this"
5783                 " derived type"_err_en_US;
5784         } else {
5785           msg = "Component '%s' is already declared in this"
5786                 " derived type"_err_en_US;
5787         }
5788         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5789       }
5790       return false;
5791     }
5792     if (scope == &currScope() && extends) {
5793       // The parent component has not yet been added to the scope.
5794       scope = extends->scope();
5795     } else {
5796       scope = scope->GetDerivedTypeParent();
5797     }
5798   }
5799   return true;
5800 }
5801 
5802 ParamValue DeclarationVisitor::GetParamValue(
5803     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5804   return common::visit(
5805       common::visitors{
5806           [=](const parser::ScalarIntExpr &x) { // C704
5807             return ParamValue{EvaluateIntExpr(x), attr};
5808           },
5809           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5810           [=](const parser::TypeParamValue::Deferred &) {
5811             return ParamValue::Deferred(attr);
5812           },
5813       },
5814       x.u);
5815 }
5816 
5817 // ConstructVisitor implementation
5818 
5819 void ConstructVisitor::ResolveIndexName(
5820     const parser::ConcurrentControl &control) {
5821   const parser::Name &name{std::get<parser::Name>(control.t)};
5822   auto *prev{FindSymbol(name)};
5823   if (prev) {
5824     if (prev->owner().kind() == Scope::Kind::Forall ||
5825         prev->owner() == currScope()) {
5826       SayAlreadyDeclared(name, *prev);
5827       return;
5828     }
5829     name.symbol = nullptr;
5830   }
5831   auto &symbol{DeclareObjectEntity(name)};
5832   if (symbol.GetType()) {
5833     // type came from explicit type-spec
5834   } else if (!prev) {
5835     ApplyImplicitRules(symbol);
5836   } else {
5837     const Symbol &prevRoot{ResolveAssociations(*prev)};
5838     // prev could be host- use- or construct-associated with another symbol
5839     if (!prevRoot.has<ObjectEntityDetails>() &&
5840         !prevRoot.has<EntityDetails>()) {
5841       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5842           *prev, "Previous declaration of '%s'"_en_US);
5843       context().SetError(symbol);
5844       return;
5845     } else {
5846       if (const auto *type{prevRoot.GetType()}) {
5847         symbol.SetType(*type);
5848       }
5849       if (prevRoot.IsObjectArray()) {
5850         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5851         return;
5852       }
5853     }
5854   }
5855   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5856 }
5857 
5858 // We need to make sure that all of the index-names get declared before the
5859 // expressions in the loop control are evaluated so that references to the
5860 // index-names in the expressions are correctly detected.
5861 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5862   BeginDeclTypeSpec();
5863   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5864   const auto &controls{
5865       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5866   for (const auto &control : controls) {
5867     ResolveIndexName(control);
5868   }
5869   Walk(controls);
5870   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5871   EndDeclTypeSpec();
5872   return false;
5873 }
5874 
5875 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5876   for (auto &name : x.v) {
5877     if (auto *symbol{DeclareLocalEntity(name)}) {
5878       symbol->set(Symbol::Flag::LocalityLocal);
5879     }
5880   }
5881   return false;
5882 }
5883 
5884 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5885   for (auto &name : x.v) {
5886     if (auto *symbol{DeclareLocalEntity(name)}) {
5887       symbol->set(Symbol::Flag::LocalityLocalInit);
5888     }
5889   }
5890   return false;
5891 }
5892 
5893 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5894   for (const auto &name : x.v) {
5895     if (!FindSymbol(name)) {
5896       Say(name,
5897           "Variable '%s' with SHARED locality implicitly declared"_warn_en_US);
5898     }
5899     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5900     if (PassesSharedLocalityChecks(name, prev)) {
5901       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5902     }
5903   }
5904   return false;
5905 }
5906 
5907 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5908   ProcessTypeSpec(x.type);
5909   Walk(x.values);
5910   return false;
5911 }
5912 
5913 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5914 // enclosing ac-implied-do
5915 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5916   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5917   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5918   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5919   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5920   // F'2018 has the scope of the implied DO variable covering the entire
5921   // implied DO production (19.4(5)), which seems wrong in cases where the name
5922   // of the implied DO variable appears in one of the bound expressions. Thus
5923   // this extension, which shrinks the scope of the variable to exclude the
5924   // expressions in the bounds.
5925   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5926   Walk(bounds.lower);
5927   Walk(bounds.upper);
5928   Walk(bounds.step);
5929   EndCheckOnIndexUseInOwnBounds(restore);
5930   PushScope(Scope::Kind::ImpliedDos, nullptr);
5931   DeclareStatementEntity(bounds.name, type);
5932   Walk(values);
5933   PopScope();
5934   return false;
5935 }
5936 
5937 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5938   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5939   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5940   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5941   // See comment in Pre(AcImpliedDo) above.
5942   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5943   Walk(bounds.lower);
5944   Walk(bounds.upper);
5945   Walk(bounds.step);
5946   EndCheckOnIndexUseInOwnBounds(restore);
5947   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5948   if (pushScope) {
5949     PushScope(Scope::Kind::ImpliedDos, nullptr);
5950   }
5951   DeclareStatementEntity(bounds.name, type);
5952   Walk(objects);
5953   if (pushScope) {
5954     PopScope();
5955   }
5956   return false;
5957 }
5958 
5959 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5960 // statement so that the predicate IsInitialized() will be true
5961 // during semantic analysis before the symbol's initializer is constructed.
5962 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5963   common::visit(
5964       common::visitors{
5965           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5966             Walk(y.thing.value());
5967             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5968             if (first.symbol) {
5969               first.symbol->set(Symbol::Flag::InDataStmt);
5970             }
5971           },
5972           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5973       },
5974       x.u);
5975   return false;
5976 }
5977 
5978 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5979   // Subtle: DATA statements may appear in both the specification and
5980   // execution parts, but should be treated as if in the execution part
5981   // for purposes of implicit variable declaration vs. host association.
5982   // When a name first appears as an object in a DATA statement, it should
5983   // be implicitly declared locally as if it had been assigned.
5984   auto flagRestorer{common::ScopedSet(inSpecificationPart_, false)};
5985   common::visit(common::visitors{
5986                     [&](const Indirection<parser::Variable> &y) {
5987                       Walk(y.value());
5988                       const parser::Name &first{
5989                           parser::GetFirstName(y.value())};
5990                       if (first.symbol) {
5991                         first.symbol->set(Symbol::Flag::InDataStmt);
5992                       }
5993                     },
5994                     [&](const parser::DataImpliedDo &y) {
5995                       PushScope(Scope::Kind::ImpliedDos, nullptr);
5996                       Walk(y);
5997                       PopScope();
5998                     },
5999                 },
6000       x.u);
6001   return false;
6002 }
6003 
6004 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
6005   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
6006   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
6007   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
6008     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
6009       if (const Symbol * symbol{FindSymbol(*name)}) {
6010         const Symbol &ultimate{symbol->GetUltimate()};
6011         if (ultimate.has<DerivedTypeDetails>()) {
6012           mutableData.u = elem->ConvertToStructureConstructor(
6013               DerivedTypeSpec{name->source, ultimate});
6014         }
6015       }
6016     }
6017   }
6018   return true;
6019 }
6020 
6021 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
6022   if (x.IsDoConcurrent()) {
6023     PushScope(Scope::Kind::Block, nullptr);
6024   }
6025   return true;
6026 }
6027 void ConstructVisitor::Post(const parser::DoConstruct &x) {
6028   if (x.IsDoConcurrent()) {
6029     PopScope();
6030   }
6031 }
6032 
6033 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
6034   PushScope(Scope::Kind::Forall, nullptr);
6035   return true;
6036 }
6037 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
6038 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
6039   PushScope(Scope::Kind::Forall, nullptr);
6040   return true;
6041 }
6042 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
6043 
6044 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
6045   CheckDef(x.v);
6046   PushScope(Scope::Kind::Block, nullptr);
6047   return false;
6048 }
6049 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
6050   PopScope();
6051   CheckRef(x.v);
6052   return false;
6053 }
6054 
6055 void ConstructVisitor::Post(const parser::Selector &x) {
6056   GetCurrentAssociation().selector = ResolveSelector(x);
6057 }
6058 
6059 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
6060   CheckDef(x.t);
6061   PushScope(Scope::Kind::Block, nullptr);
6062   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
6063   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
6064     SetCurrentAssociation(nthLastAssoc);
6065     if (auto *symbol{MakeAssocEntity()}) {
6066       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
6067         Say("Selector must not be a coindexed object"_err_en_US);
6068       }
6069       SetTypeFromAssociation(*symbol);
6070       SetAttrsFromAssociation(*symbol);
6071     }
6072   }
6073   PopAssociation(assocCount);
6074 }
6075 
6076 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
6077   PopScope();
6078   CheckRef(x.v);
6079 }
6080 
6081 bool ConstructVisitor::Pre(const parser::Association &x) {
6082   PushAssociation();
6083   const auto &name{std::get<parser::Name>(x.t)};
6084   GetCurrentAssociation().name = &name;
6085   return true;
6086 }
6087 
6088 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
6089   CheckDef(x.t);
6090   PushScope(Scope::Kind::Block, nullptr);
6091   PushAssociation();
6092   return true;
6093 }
6094 
6095 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
6096   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
6097   const auto &name{std::get<parser::Name>(decl.t)};
6098   if (auto *symbol{FindInScope(name)}) {
6099     const auto &selector{std::get<parser::Selector>(x.t)};
6100     if (auto sel{ResolveSelector(selector)}) {
6101       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
6102       if (!whole || whole->Corank() == 0) {
6103         Say(sel.source, // C1116
6104             "Selector in coarray association must name a coarray"_err_en_US);
6105       } else if (auto dynType{sel.expr->GetType()}) {
6106         if (!symbol->GetType()) {
6107           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
6108         }
6109       }
6110     }
6111   }
6112 }
6113 
6114 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
6115   PopAssociation();
6116   PopScope();
6117   CheckRef(x.t);
6118 }
6119 
6120 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
6121   PushAssociation();
6122   return true;
6123 }
6124 
6125 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
6126   PopAssociation();
6127 }
6128 
6129 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
6130   auto &association{GetCurrentAssociation()};
6131   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6132     // This isn't a name in the current scope, it is in each TypeGuardStmt
6133     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
6134     association.name = &*name;
6135     auto exprType{association.selector.expr->GetType()};
6136     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
6137       Say("Selector must not be a coindexed object"_err_en_US);
6138     }
6139     if (exprType && !exprType->IsPolymorphic()) { // C1159
6140       Say(association.selector.source,
6141           "Selector '%s' in SELECT TYPE statement must be "
6142           "polymorphic"_err_en_US);
6143     }
6144   } else {
6145     if (const Symbol *
6146         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6147       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
6148       if (!IsVariableName(*whole)) {
6149         Say(association.selector.source, // C901
6150             "Selector is not a variable"_err_en_US);
6151         association = {};
6152       }
6153       if (const DeclTypeSpec * type{whole->GetType()}) {
6154         if (!type->IsPolymorphic()) { // C1159
6155           Say(association.selector.source,
6156               "Selector '%s' in SELECT TYPE statement must be "
6157               "polymorphic"_err_en_US);
6158         }
6159       }
6160     } else {
6161       Say(association.selector.source, // C1157
6162           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
6163       association = {};
6164     }
6165   }
6166 }
6167 
6168 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
6169   auto &association{GetCurrentAssociation()};
6170   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6171     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
6172     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
6173     association.name = &*name;
6174   }
6175 }
6176 
6177 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
6178   PushScope(Scope::Kind::Block, nullptr);
6179   return true;
6180 }
6181 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
6182   PopScope();
6183 }
6184 
6185 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
6186   PushScope(Scope::Kind::Block, nullptr);
6187   return true;
6188 }
6189 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
6190   PopScope();
6191 }
6192 
6193 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
6194   if (auto *symbol{MakeAssocEntity()}) {
6195     if (std::holds_alternative<parser::Default>(x.u)) {
6196       SetTypeFromAssociation(*symbol);
6197     } else if (const auto *type{GetDeclTypeSpec()}) {
6198       symbol->SetType(*type);
6199     }
6200     SetAttrsFromAssociation(*symbol);
6201   }
6202 }
6203 
6204 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
6205   if (auto *symbol{MakeAssocEntity()}) {
6206     SetTypeFromAssociation(*symbol);
6207     SetAttrsFromAssociation(*symbol);
6208     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
6209       if (auto val{EvaluateInt64(context(), *init)}) {
6210         auto &details{symbol->get<AssocEntityDetails>()};
6211         details.set_rank(*val);
6212       }
6213     }
6214   }
6215 }
6216 
6217 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
6218   PushAssociation();
6219   return true;
6220 }
6221 
6222 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
6223   PopAssociation();
6224 }
6225 
6226 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
6227   if (x) {
6228     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
6229   }
6230   return true;
6231 }
6232 
6233 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
6234   if (x) {
6235     // Just add an occurrence of this name; checking is done in ValidateLabels
6236     FindSymbol(*x);
6237   }
6238 }
6239 
6240 // Make a symbol for the associating entity of the current association.
6241 Symbol *ConstructVisitor::MakeAssocEntity() {
6242   Symbol *symbol{nullptr};
6243   auto &association{GetCurrentAssociation()};
6244   if (association.name) {
6245     symbol = &MakeSymbol(*association.name, UnknownDetails{});
6246     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
6247       Say(*association.name, // C1102
6248           "The associate name '%s' is already used in this associate statement"_err_en_US);
6249       return nullptr;
6250     }
6251   } else if (const Symbol *
6252       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6253     symbol = &MakeSymbol(whole->name());
6254   } else {
6255     return nullptr;
6256   }
6257   if (auto &expr{association.selector.expr}) {
6258     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
6259   } else {
6260     symbol->set_details(AssocEntityDetails{});
6261   }
6262   return symbol;
6263 }
6264 
6265 // Set the type of symbol based on the current association selector.
6266 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
6267   auto &details{symbol.get<AssocEntityDetails>()};
6268   const MaybeExpr *pexpr{&details.expr()};
6269   if (!*pexpr) {
6270     pexpr = &GetCurrentAssociation().selector.expr;
6271   }
6272   if (*pexpr) {
6273     const SomeExpr &expr{**pexpr};
6274     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
6275       if (const auto *charExpr{
6276               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
6277                   expr)}) {
6278         symbol.SetType(ToDeclTypeSpec(std::move(*type),
6279             FoldExpr(common::visit(
6280                 [](const auto &kindChar) { return kindChar.LEN(); },
6281                 charExpr->u))));
6282       } else {
6283         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
6284       }
6285     } else {
6286       // BOZ literals, procedure designators, &c. are not acceptable
6287       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
6288     }
6289   }
6290 }
6291 
6292 // If current selector is a variable, set some of its attributes on symbol.
6293 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
6294   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
6295   symbol.attrs() |= attrs &
6296       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
6297   if (attrs.test(Attr::POINTER)) {
6298     symbol.attrs().set(Attr::TARGET);
6299   }
6300 }
6301 
6302 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
6303     const parser::Selector &x) {
6304   return common::visit(common::visitors{
6305                            [&](const parser::Expr &expr) {
6306                              return Selector{expr.source, EvaluateExpr(x)};
6307                            },
6308                            [&](const parser::Variable &var) {
6309                              return Selector{var.GetSource(), EvaluateExpr(x)};
6310                            },
6311                        },
6312       x.u);
6313 }
6314 
6315 // Set the current association to the nth to the last association on the
6316 // association stack.  The top of the stack is at n = 1.  This allows access
6317 // to the interior of a list of associations at the top of the stack.
6318 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
6319   CHECK(n > 0 && n <= associationStack_.size());
6320   currentAssociation_ = &associationStack_[associationStack_.size() - n];
6321 }
6322 
6323 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
6324   CHECK(currentAssociation_);
6325   return *currentAssociation_;
6326 }
6327 
6328 void ConstructVisitor::PushAssociation() {
6329   associationStack_.emplace_back(Association{});
6330   currentAssociation_ = &associationStack_.back();
6331 }
6332 
6333 void ConstructVisitor::PopAssociation(std::size_t count) {
6334   CHECK(count > 0 && count <= associationStack_.size());
6335   associationStack_.resize(associationStack_.size() - count);
6336   currentAssociation_ =
6337       associationStack_.empty() ? nullptr : &associationStack_.back();
6338 }
6339 
6340 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6341     evaluate::DynamicType &&type) {
6342   switch (type.category()) {
6343     SWITCH_COVERS_ALL_CASES
6344   case common::TypeCategory::Integer:
6345   case common::TypeCategory::Real:
6346   case common::TypeCategory::Complex:
6347     return context().MakeNumericType(type.category(), type.kind());
6348   case common::TypeCategory::Logical:
6349     return context().MakeLogicalType(type.kind());
6350   case common::TypeCategory::Derived:
6351     if (type.IsAssumedType()) {
6352       return currScope().MakeTypeStarType();
6353     } else if (type.IsUnlimitedPolymorphic()) {
6354       return currScope().MakeClassStarType();
6355     } else {
6356       return currScope().MakeDerivedType(
6357           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
6358                                : DeclTypeSpec::TypeDerived,
6359           common::Clone(type.GetDerivedTypeSpec())
6360 
6361       );
6362     }
6363   case common::TypeCategory::Character:
6364     CRASH_NO_CASE;
6365   }
6366 }
6367 
6368 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6369     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
6370   CHECK(type.category() == common::TypeCategory::Character);
6371   if (length) {
6372     return currScope().MakeCharacterType(
6373         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
6374         KindExpr{type.kind()});
6375   } else {
6376     return currScope().MakeCharacterType(
6377         ParamValue::Deferred(common::TypeParamAttr::Len),
6378         KindExpr{type.kind()});
6379   }
6380 }
6381 
6382 // ResolveNamesVisitor implementation
6383 
6384 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
6385   HandleCall(Symbol::Flag::Function, x.v);
6386   return false;
6387 }
6388 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
6389   HandleCall(Symbol::Flag::Subroutine, x.v);
6390   return false;
6391 }
6392 
6393 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
6394   auto &scope{currScope()};
6395   // Check C896 and C899: where IMPORT statements are allowed
6396   switch (scope.kind()) {
6397   case Scope::Kind::Module:
6398     if (scope.IsModule()) {
6399       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
6400       return false;
6401     } else if (x.kind == common::ImportKind::None) {
6402       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
6403       return false;
6404     }
6405     break;
6406   case Scope::Kind::MainProgram:
6407     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
6408     return false;
6409   case Scope::Kind::Subprogram:
6410     if (scope.parent().IsGlobal()) {
6411       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
6412       return false;
6413     }
6414     break;
6415   case Scope::Kind::BlockData: // C1415 (in part)
6416     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
6417     return false;
6418   default:;
6419   }
6420   if (auto error{scope.SetImportKind(x.kind)}) {
6421     Say(std::move(*error));
6422   }
6423   for (auto &name : x.names) {
6424     if (FindSymbol(scope.parent(), name)) {
6425       scope.add_importName(name.source);
6426     } else {
6427       Say(name, "'%s' not found in host scope"_err_en_US);
6428     }
6429   }
6430   prevImportStmt_ = currStmtSource();
6431   return false;
6432 }
6433 
6434 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6435     const parser::StructureComponent &x) {
6436   return FindComponent(ResolveDataRef(x.base), x.component);
6437 }
6438 
6439 const parser::Name *DeclarationVisitor::ResolveDesignator(
6440     const parser::Designator &x) {
6441   return common::visit(
6442       common::visitors{
6443           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6444           [&](const parser::Substring &x) {
6445             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6446           },
6447       },
6448       x.u);
6449 }
6450 
6451 const parser::Name *DeclarationVisitor::ResolveDataRef(
6452     const parser::DataRef &x) {
6453   return common::visit(
6454       common::visitors{
6455           [=](const parser::Name &y) { return ResolveName(y); },
6456           [=](const Indirection<parser::StructureComponent> &y) {
6457             return ResolveStructureComponent(y.value());
6458           },
6459           [&](const Indirection<parser::ArrayElement> &y) {
6460             Walk(y.value().subscripts);
6461             const parser::Name *name{ResolveDataRef(y.value().base)};
6462             if (name && name->symbol) {
6463               if (!IsProcedure(*name->symbol)) {
6464                 ConvertToObjectEntity(*name->symbol);
6465               } else if (!context().HasError(*name->symbol)) {
6466                 SayWithDecl(*name, *name->symbol,
6467                     "Cannot reference function '%s' as data"_err_en_US);
6468               }
6469             }
6470             return name;
6471           },
6472           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6473             Walk(y.value().imageSelector);
6474             return ResolveDataRef(y.value().base);
6475           },
6476       },
6477       x.u);
6478 }
6479 
6480 // If implicit types are allowed, ensure name is in the symbol table.
6481 // Otherwise, report an error if it hasn't been declared.
6482 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6483   FindSymbol(name);
6484   if (CheckForHostAssociatedImplicit(name)) {
6485     NotePossibleBadForwardRef(name);
6486     return &name;
6487   }
6488   if (Symbol * symbol{name.symbol}) {
6489     if (CheckUseError(name)) {
6490       return nullptr; // reported an error
6491     }
6492     NotePossibleBadForwardRef(name);
6493     symbol->set(Symbol::Flag::ImplicitOrError, false);
6494     if (IsUplevelReference(*symbol)) {
6495       MakeHostAssocSymbol(name, *symbol);
6496     } else if (IsDummy(*symbol) ||
6497         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6498       ConvertToObjectEntity(*symbol);
6499       ApplyImplicitRules(*symbol);
6500     }
6501     if (checkIndexUseInOwnBounds_ &&
6502         *checkIndexUseInOwnBounds_ == name.source) {
6503       Say(name,
6504           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_port_en_US,
6505           name.source);
6506     }
6507     return &name;
6508   }
6509   if (isImplicitNoneType()) {
6510     Say(name, "No explicit type declared for '%s'"_err_en_US);
6511     return nullptr;
6512   }
6513   // Create the symbol then ensure it is accessible
6514   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6515     Say(name,
6516         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6517         name.source);
6518   }
6519   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6520   auto *symbol{FindSymbol(name)};
6521   if (!symbol) {
6522     Say(name,
6523         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6524     return nullptr;
6525   }
6526   ConvertToObjectEntity(*symbol);
6527   ApplyImplicitRules(*symbol);
6528   NotePossibleBadForwardRef(name);
6529   return &name;
6530 }
6531 
6532 // A specification expression may refer to a symbol in the host procedure that
6533 // is implicitly typed. Because specification parts are processed before
6534 // execution parts, this may be the first time we see the symbol. It can't be a
6535 // local in the current scope (because it's in a specification expression) so
6536 // either it is implicitly declared in the host procedure or it is an error.
6537 // We create a symbol in the host assuming it is the former; if that proves to
6538 // be wrong we report an error later in CheckDeclarations().
6539 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6540     const parser::Name &name) {
6541   if (!inSpecificationPart_) {
6542     return false;
6543   }
6544   if (name.symbol) {
6545     ApplyImplicitRules(*name.symbol, true);
6546   }
6547   Symbol *hostSymbol;
6548   Scope *host{GetHostProcedure()};
6549   if (!host || isImplicitNoneType(*host)) {
6550     return false;
6551   }
6552   if (!name.symbol) {
6553     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6554     ConvertToObjectEntity(*hostSymbol);
6555     ApplyImplicitRules(*hostSymbol);
6556     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6557   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6558     hostSymbol = name.symbol;
6559   } else {
6560     return false;
6561   }
6562   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6563   if (isImplicitNoneType()) {
6564     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6565   } else {
6566     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6567   }
6568   return true;
6569 }
6570 
6571 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6572   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6573   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6574     return false;
6575   } else {
6576     Scope::Kind kind{symbolUnit.kind()};
6577     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6578   }
6579 }
6580 
6581 // base is a part-ref of a derived type; find the named component in its type.
6582 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6583 // COMPLEX component references (%re, %im).
6584 const parser::Name *DeclarationVisitor::FindComponent(
6585     const parser::Name *base, const parser::Name &component) {
6586   if (!base || !base->symbol) {
6587     return nullptr;
6588   }
6589   if (auto *misc{base->symbol->detailsIf<MiscDetails>()}) {
6590     if (component.source == "kind") {
6591       if (misc->kind() == MiscDetails::Kind::ComplexPartRe ||
6592           misc->kind() == MiscDetails::Kind::ComplexPartIm ||
6593           misc->kind() == MiscDetails::Kind::KindParamInquiry ||
6594           misc->kind() == MiscDetails::Kind::LenParamInquiry) {
6595         // x%{re,im,kind,len}%kind
6596         MakePlaceholder(component, MiscDetails::Kind::KindParamInquiry);
6597         return &component;
6598       }
6599     }
6600   }
6601   auto &symbol{base->symbol->GetUltimate()};
6602   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6603     SayWithDecl(*base, symbol,
6604         "'%s' is an invalid base for a component reference"_err_en_US);
6605     return nullptr;
6606   }
6607   auto *type{symbol.GetType()};
6608   if (!type) {
6609     return nullptr; // should have already reported error
6610   }
6611   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6612     auto category{intrinsic->category()};
6613     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6614     if (component.source == "kind") {
6615       miscKind = MiscDetails::Kind::KindParamInquiry;
6616     } else if (category == TypeCategory::Character) {
6617       if (component.source == "len") {
6618         miscKind = MiscDetails::Kind::LenParamInquiry;
6619       }
6620     } else if (category == TypeCategory::Complex) {
6621       if (component.source == "re") {
6622         miscKind = MiscDetails::Kind::ComplexPartRe;
6623       } else if (component.source == "im") {
6624         miscKind = MiscDetails::Kind::ComplexPartIm;
6625       }
6626     }
6627     if (miscKind != MiscDetails::Kind::None) {
6628       MakePlaceholder(component, miscKind);
6629       return &component;
6630     }
6631   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6632     if (const Scope * scope{derived->scope()}) {
6633       if (Resolve(component, scope->FindComponent(component.source))) {
6634         if (auto msg{
6635                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6636           context().Say(component.source, *msg);
6637         }
6638         return &component;
6639       } else {
6640         SayDerivedType(component.source,
6641             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6642       }
6643     }
6644     return nullptr;
6645   }
6646   if (symbol.test(Symbol::Flag::Implicit)) {
6647     Say(*base,
6648         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6649   } else {
6650     SayWithDecl(
6651         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6652   }
6653   return nullptr;
6654 }
6655 
6656 void DeclarationVisitor::Initialization(const parser::Name &name,
6657     const parser::Initialization &init, bool inComponentDecl) {
6658   // Traversal of the initializer was deferred to here so that the
6659   // symbol being declared can be available for use in the expression, e.g.:
6660   //   real, parameter :: x = tiny(x)
6661   if (!name.symbol) {
6662     return;
6663   }
6664   Symbol &ultimate{name.symbol->GetUltimate()};
6665   if (IsAllocatable(ultimate)) {
6666     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6667     return;
6668   }
6669   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6670     // TODO: check C762 - all bounds and type parameters of component
6671     // are colons or constant expressions if component is initialized
6672     common::visit(
6673         common::visitors{
6674             [&](const parser::ConstantExpr &expr) {
6675               NonPointerInitialization(name, expr);
6676             },
6677             [&](const parser::NullInit &null) {
6678               Walk(null);
6679               if (auto nullInit{EvaluateExpr(null)}) {
6680                 if (!evaluate::IsNullPointer(*nullInit)) {
6681                   Say(name,
6682                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6683                 } else if (IsPointer(ultimate)) {
6684                   object->set_init(std::move(*nullInit));
6685                 } else {
6686                   Say(name,
6687                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6688                 }
6689               }
6690             },
6691             [&](const parser::InitialDataTarget &) {
6692               // Defer analysis to the end of the specification part
6693               // so that forward references and attribute checks like SAVE
6694               // work better.
6695               ultimate.set(Symbol::Flag::InDataStmt);
6696             },
6697             [&](const std::list<Indirection<parser::DataStmtValue>> &values) {
6698               // Handled later in data-to-inits conversion
6699               ultimate.set(Symbol::Flag::InDataStmt);
6700               Walk(values);
6701             },
6702         },
6703         init.u);
6704   }
6705 }
6706 
6707 void DeclarationVisitor::PointerInitialization(
6708     const parser::Name &name, const parser::InitialDataTarget &target) {
6709   if (name.symbol) {
6710     Symbol &ultimate{name.symbol->GetUltimate()};
6711     if (!context().HasError(ultimate)) {
6712       if (IsPointer(ultimate)) {
6713         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6714           CHECK(!details->init());
6715           Walk(target);
6716           if (MaybeExpr expr{EvaluateExpr(target)}) {
6717             // Validation is done in declaration checking.
6718             details->set_init(std::move(*expr));
6719           }
6720         }
6721       } else {
6722         Say(name,
6723             "'%s' is not a pointer but is initialized like one"_err_en_US);
6724         context().SetError(ultimate);
6725       }
6726     }
6727   }
6728 }
6729 void DeclarationVisitor::PointerInitialization(
6730     const parser::Name &name, const parser::ProcPointerInit &target) {
6731   if (name.symbol) {
6732     Symbol &ultimate{name.symbol->GetUltimate()};
6733     if (!context().HasError(ultimate)) {
6734       if (IsProcedurePointer(ultimate)) {
6735         auto &details{ultimate.get<ProcEntityDetails>()};
6736         CHECK(!details.init());
6737         Walk(target);
6738         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6739           if (targetName->symbol) {
6740             // Validation is done in declaration checking.
6741             details.set_init(*targetName->symbol);
6742           }
6743         } else {
6744           details.set_init(nullptr); // explicit NULL()
6745         }
6746       } else {
6747         Say(name,
6748             "'%s' is not a procedure pointer but is initialized "
6749             "like one"_err_en_US);
6750         context().SetError(ultimate);
6751       }
6752     }
6753   }
6754 }
6755 
6756 void DeclarationVisitor::NonPointerInitialization(
6757     const parser::Name &name, const parser::ConstantExpr &expr) {
6758   if (name.symbol) {
6759     Symbol &ultimate{name.symbol->GetUltimate()};
6760     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6761       if (IsPointer(ultimate)) {
6762         Say(name,
6763             "'%s' is a pointer but is not initialized like one"_err_en_US);
6764       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6765         CHECK(!details->init());
6766         Walk(expr);
6767         if (ultimate.owner().IsParameterizedDerivedType()) {
6768           // Save the expression for per-instantiation analysis.
6769           details->set_unanalyzedPDTComponentInit(&expr.thing.value());
6770         } else {
6771           if (MaybeExpr folded{EvaluateNonPointerInitializer(
6772                   ultimate, expr, expr.thing.value().source)}) {
6773             details->set_init(std::move(*folded));
6774           }
6775         }
6776       }
6777     }
6778   }
6779 }
6780 
6781 void ResolveNamesVisitor::HandleCall(
6782     Symbol::Flag procFlag, const parser::Call &call) {
6783   common::visit(
6784       common::visitors{
6785           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6786           [&](const parser::ProcComponentRef &x) { Walk(x); },
6787       },
6788       std::get<parser::ProcedureDesignator>(call.t).u);
6789   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6790 }
6791 
6792 void ResolveNamesVisitor::HandleProcedureName(
6793     Symbol::Flag flag, const parser::Name &name) {
6794   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6795   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6796   if (!symbol) {
6797     if (IsIntrinsic(name.source, flag)) {
6798       symbol =
6799           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6800     } else {
6801       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6802     }
6803     Resolve(name, *symbol);
6804     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6805       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6806         MakeExternal(*symbol);
6807       }
6808     }
6809     ConvertToProcEntity(*symbol);
6810     SetProcFlag(name, *symbol, flag);
6811   } else if (CheckUseError(name)) {
6812     // error was reported
6813   } else {
6814     auto &nonUltimateSymbol{*symbol};
6815     symbol = &Resolve(name, symbol)->GetUltimate();
6816     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6817     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6818         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6819       AcquireIntrinsicProcedureFlags(*symbol);
6820     }
6821     if (!SetProcFlag(name, *symbol, flag)) {
6822       return; // reported error
6823     }
6824     if (!symbol->has<GenericDetails>()) {
6825       CheckImplicitNoneExternal(name.source, *symbol);
6826     }
6827     if (symbol->has<SubprogramDetails>() &&
6828         symbol->attrs().test(Attr::ABSTRACT)) {
6829       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6830     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6831         symbol->has<AssocEntityDetails>()) {
6832       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6833       // here as procedure-designators because this means the related
6834       // FunctionReference are mis-parsed structure constructors or array
6835       // references that will be fixed later when analyzing expressions.
6836     } else if (symbol->has<ObjectEntityDetails>()) {
6837       // Symbols with ObjectEntityDetails are also accepted because this can be
6838       // a mis-parsed array references that will be fixed later. Ensure that if
6839       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6840       // is created for the current scope.
6841       // Operate on non ultimate symbol so that HostAssocDetails are also
6842       // created for symbols used associated in the host procedure.
6843       if (IsUplevelReference(nonUltimateSymbol)) {
6844         MakeHostAssocSymbol(name, nonUltimateSymbol);
6845       }
6846     } else if (symbol->test(Symbol::Flag::Implicit)) {
6847       Say(name,
6848           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6849     } else {
6850       SayWithDecl(name, *symbol,
6851           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6852     }
6853   }
6854 }
6855 
6856 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6857     const SourceName &name, const Symbol &symbol) {
6858   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6859       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6860     Say(name,
6861         "'%s' is an external procedure without the EXTERNAL"
6862         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6863     return false;
6864   }
6865   return true;
6866 }
6867 
6868 // Variant of HandleProcedureName() for use while skimming the executable
6869 // part of a subprogram to catch calls to dummy procedures that are part
6870 // of the subprogram's interface, and to mark as procedures any symbols
6871 // that might otherwise have been miscategorized as objects.
6872 void ResolveNamesVisitor::NoteExecutablePartCall(
6873     Symbol::Flag flag, const parser::Call &call) {
6874   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6875   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6876     // Subtlety: The symbol pointers in the parse tree are not set, because
6877     // they might end up resolving elsewhere (e.g., construct entities in
6878     // SELECT TYPE).
6879     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6880       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6881               ? Symbol::Flag::Function
6882               : Symbol::Flag::Subroutine};
6883       if (!symbol->test(other)) {
6884         ConvertToProcEntity(*symbol);
6885         if (symbol->has<ProcEntityDetails>()) {
6886           symbol->set(flag);
6887           if (IsDummy(*symbol)) {
6888             symbol->attrs().set(Attr::EXTERNAL);
6889           }
6890           ApplyImplicitRules(*symbol);
6891         }
6892       }
6893     }
6894   }
6895 }
6896 
6897 static bool IsLocallyImplicitGlobalSymbol(
6898     const Symbol &symbol, const parser::Name &localName) {
6899   return symbol.owner().IsGlobal() &&
6900       (!symbol.scope() ||
6901           !symbol.scope()->sourceRange().Contains(localName.source));
6902 }
6903 
6904 static bool TypesMismatchIfNonNull(
6905     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
6906   return type1 && type2 && *type1 != *type2;
6907 }
6908 
6909 // Check and set the Function or Subroutine flag on symbol; false on error.
6910 bool ResolveNamesVisitor::SetProcFlag(
6911     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6912   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6913     SayWithDecl(
6914         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6915     return false;
6916   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6917       flag == Symbol::Flag::Function) {
6918     SayWithDecl(
6919         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6920     return false;
6921   } else if (flag == Symbol::Flag::Function &&
6922       IsLocallyImplicitGlobalSymbol(symbol, name) &&
6923       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
6924     SayWithDecl(name, symbol,
6925         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
6926     return false;
6927   } else if (symbol.has<ProcEntityDetails>()) {
6928     symbol.set(flag); // in case it hasn't been set yet
6929     if (flag == Symbol::Flag::Function) {
6930       ApplyImplicitRules(symbol);
6931     }
6932     if (symbol.attrs().test(Attr::INTRINSIC)) {
6933       AcquireIntrinsicProcedureFlags(symbol);
6934     }
6935   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6936     SayWithDecl(
6937         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6938   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6939     AcquireIntrinsicProcedureFlags(symbol);
6940   }
6941   return true;
6942 }
6943 
6944 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6945   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6946   if (!currScope().IsModule()) { // C869
6947     Say(currStmtSource().value(),
6948         "%s statement may only appear in the specification part of a module"_err_en_US,
6949         EnumToString(accessAttr));
6950     return false;
6951   }
6952   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6953   if (accessIds.empty()) {
6954     if (prevAccessStmt_) { // C869
6955       Say("The default accessibility of this module has already been declared"_err_en_US)
6956           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6957     }
6958     prevAccessStmt_ = currStmtSource();
6959     defaultAccess_ = accessAttr;
6960   } else {
6961     for (const auto &accessId : accessIds) {
6962       common::visit(
6963           common::visitors{
6964               [=](const parser::Name &y) {
6965                 Resolve(y, SetAccess(y.source, accessAttr));
6966               },
6967               [=](const Indirection<parser::GenericSpec> &y) {
6968                 auto info{GenericSpecInfo{y.value()}};
6969                 const auto &symbolName{info.symbolName()};
6970                 if (auto *symbol{FindInScope(symbolName)}) {
6971                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6972                 } else if (info.kind().IsName()) {
6973                   info.Resolve(&SetAccess(symbolName, accessAttr));
6974                 } else {
6975                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6976                 }
6977               },
6978           },
6979           accessId.u);
6980     }
6981   }
6982   return false;
6983 }
6984 
6985 // Set the access specification for this symbol.
6986 Symbol &ModuleVisitor::SetAccess(
6987     const SourceName &name, Attr attr, Symbol *symbol) {
6988   if (!symbol) {
6989     symbol = &MakeSymbol(name);
6990   }
6991   Attrs &attrs{symbol->attrs()};
6992   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6993     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6994     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6995     Say(name,
6996         WithSeverity(
6997             "The accessibility of '%s' has already been specified as %s"_warn_en_US,
6998             attr != prev ? parser::Severity::Error : parser::Severity::Warning),
6999         MakeOpName(name), EnumToString(prev));
7000   } else {
7001     attrs.set(attr);
7002   }
7003   return *symbol;
7004 }
7005 
7006 static bool NeedsExplicitType(const Symbol &symbol) {
7007   if (symbol.has<UnknownDetails>()) {
7008     return true;
7009   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
7010     return !details->type();
7011   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
7012     return !details->type();
7013   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
7014     return !details->interface().symbol() && !details->interface().type();
7015   } else {
7016     return false;
7017   }
7018 }
7019 
7020 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
7021   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
7022       implicitPart, decls] = x.t;
7023   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
7024   auto stateRestorer{
7025       common::ScopedSet(specPartState_, SpecificationPartState{})};
7026   Walk(accDecls);
7027   Walk(ompDecls);
7028   Walk(compilerDirectives);
7029   Walk(useStmts);
7030   ClearUseRenames();
7031   ClearUseOnly();
7032   ClearExplicitIntrinsicUses();
7033   Walk(importStmts);
7034   Walk(implicitPart);
7035   for (const auto &decl : decls) {
7036     if (const auto *spec{
7037             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
7038       PreSpecificationConstruct(*spec);
7039     }
7040   }
7041   Walk(decls);
7042   FinishSpecificationPart(decls);
7043   return false;
7044 }
7045 
7046 // Initial processing on specification constructs, before visiting them.
7047 void ResolveNamesVisitor::PreSpecificationConstruct(
7048     const parser::SpecificationConstruct &spec) {
7049   common::visit(
7050       common::visitors{
7051           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
7052             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
7053           },
7054           [&](const Indirection<parser::InterfaceBlock> &y) {
7055             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
7056                 y.value().t)};
7057             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
7058               CreateGeneric(*spec);
7059             }
7060           },
7061           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
7062             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
7063               CreateCommonBlockSymbols(*commonStmt);
7064             }
7065           },
7066           [&](const auto &) {},
7067       },
7068       spec.u);
7069 }
7070 
7071 void ResolveNamesVisitor::CreateCommonBlockSymbols(
7072     const parser::CommonStmt &commonStmt) {
7073   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
7074     const auto &[name, objects] = block.t;
7075     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
7076     for (const auto &object : objects) {
7077       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
7078       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
7079         details->set_commonBlock(commonBlock);
7080         commonBlock.get<CommonBlockDetails>().add_object(obj);
7081       }
7082     }
7083   }
7084 }
7085 
7086 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
7087   auto info{GenericSpecInfo{x}};
7088   SourceName symbolName{info.symbolName()};
7089   if (IsLogicalConstant(context(), symbolName)) {
7090     Say(symbolName,
7091         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7092     return;
7093   }
7094   GenericDetails genericDetails;
7095   Symbol *existing{nullptr};
7096   // Check all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
7097   for (const std::string &n : GetAllNames(context(), symbolName)) {
7098     if (auto iter{currScope().find(n)}; iter != currScope().end()) {
7099       existing = &*iter->second;
7100       break;
7101     }
7102   }
7103   if (existing) {
7104     Symbol &ultimate{existing->GetUltimate()};
7105     if (const auto *existingGeneric{ultimate.detailsIf<GenericDetails>()}) {
7106       if (const auto *existingUse{existing->detailsIf<UseDetails>()}) {
7107         // Create a local copy of a use associated generic so that
7108         // it can be locally extended without corrupting the original.
7109         genericDetails.CopyFrom(*existingGeneric);
7110         AddGenericUse(genericDetails, existing->name(), existingUse->symbol());
7111       } else if (existing == &ultimate) {
7112         // Extending an extant generic in the same scope
7113         info.Resolve(existing);
7114         return;
7115       } else {
7116         // Host association of a generic is handled in ResolveGeneric()
7117         CHECK(existing->has<HostAssocDetails>());
7118       }
7119     } else if (ultimate.has<SubprogramDetails>() ||
7120         ultimate.has<SubprogramNameDetails>()) {
7121       genericDetails.set_specific(ultimate);
7122     } else if (ultimate.has<DerivedTypeDetails>()) {
7123       genericDetails.set_derivedType(ultimate);
7124     } else {
7125       SayAlreadyDeclared(symbolName, *existing);
7126       return;
7127     }
7128     EraseSymbol(*existing);
7129   }
7130   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
7131 }
7132 
7133 void ResolveNamesVisitor::FinishSpecificationPart(
7134     const std::list<parser::DeclarationConstruct> &decls) {
7135   badStmtFuncFound_ = false;
7136   funcResultStack().CompleteFunctionResultType();
7137   CheckImports();
7138   bool inModule{currScope().kind() == Scope::Kind::Module};
7139   for (auto &pair : currScope()) {
7140     auto &symbol{*pair.second};
7141     if (NeedsExplicitType(symbol)) {
7142       ApplyImplicitRules(symbol);
7143     }
7144     if (IsDummy(symbol) && isImplicitNoneType() &&
7145         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
7146       Say(symbol.name(),
7147           "No explicit type declared for dummy argument '%s'"_err_en_US);
7148       context().SetError(symbol);
7149     }
7150     if (symbol.has<GenericDetails>()) {
7151       CheckGenericProcedures(symbol);
7152     }
7153     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
7154         !symbol.test(Symbol::Flag::Function) &&
7155         !symbol.test(Symbol::Flag::Subroutine)) {
7156       // in a module, external proc without return type is subroutine
7157       symbol.set(
7158           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
7159     }
7160     if (!symbol.has<HostAssocDetails>()) {
7161       CheckPossibleBadForwardRef(symbol);
7162     }
7163   }
7164   currScope().InstantiateDerivedTypes();
7165   for (const auto &decl : decls) {
7166     if (const auto *statement{std::get_if<
7167             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
7168             &decl.u)}) {
7169       AnalyzeStmtFunctionStmt(statement->statement.value());
7170     }
7171   }
7172   // TODO: what about instantiations in BLOCK?
7173   CheckSaveStmts();
7174   CheckCommonBlocks();
7175   if (!inInterfaceBlock()) {
7176     // TODO: warn for the case where the EQUIVALENCE statement is in a
7177     // procedure declaration in an interface block
7178     CheckEquivalenceSets();
7179   }
7180 }
7181 
7182 // Analyze the bodies of statement functions now that the symbols in this
7183 // specification part have been fully declared and implicitly typed.
7184 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
7185     const parser::StmtFunctionStmt &stmtFunc) {
7186   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
7187   if (!symbol || !symbol->has<SubprogramDetails>()) {
7188     return;
7189   }
7190   auto &details{symbol->get<SubprogramDetails>()};
7191   auto expr{AnalyzeExpr(
7192       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
7193   if (!expr) {
7194     context().SetError(*symbol);
7195     return;
7196   }
7197   if (auto type{evaluate::DynamicType::From(*symbol)}) {
7198     auto converted{ConvertToType(*type, std::move(*expr))};
7199     if (!converted) {
7200       context().SetError(*symbol);
7201       return;
7202     }
7203     details.set_stmtFunction(std::move(*converted));
7204   } else {
7205     details.set_stmtFunction(std::move(*expr));
7206   }
7207 }
7208 
7209 void ResolveNamesVisitor::CheckImports() {
7210   auto &scope{currScope()};
7211   switch (scope.GetImportKind()) {
7212   case common::ImportKind::None:
7213     break;
7214   case common::ImportKind::All:
7215     // C8102: all entities in host must not be hidden
7216     for (const auto &pair : scope.parent()) {
7217       auto &name{pair.first};
7218       std::optional<SourceName> scopeName{scope.GetName()};
7219       if (!scopeName || name != *scopeName) {
7220         CheckImport(prevImportStmt_.value(), name);
7221       }
7222     }
7223     break;
7224   case common::ImportKind::Default:
7225   case common::ImportKind::Only:
7226     // C8102: entities named in IMPORT must not be hidden
7227     for (auto &name : scope.importNames()) {
7228       CheckImport(name, name);
7229     }
7230     break;
7231   }
7232 }
7233 
7234 void ResolveNamesVisitor::CheckImport(
7235     const SourceName &location, const SourceName &name) {
7236   if (auto *symbol{FindInScope(name)}) {
7237     const Symbol &ultimate{symbol->GetUltimate()};
7238     if (&ultimate.owner() == &currScope()) {
7239       Say(location, "'%s' from host is not accessible"_err_en_US, name)
7240           .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
7241               symbol->name());
7242     }
7243   }
7244 }
7245 
7246 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
7247   return CheckNotInBlock("IMPLICIT") && // C1107
7248       ImplicitRulesVisitor::Pre(x);
7249 }
7250 
7251 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
7252   common::visit(common::visitors{
7253                     [&](const parser::Name &x) { ResolveName(x); },
7254                     [&](const parser::StructureComponent &x) {
7255                       ResolveStructureComponent(x);
7256                     },
7257                 },
7258       x.u);
7259 }
7260 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
7261   common::visit(common::visitors{
7262                     [&](const parser::Name &x) { ResolveName(x); },
7263                     [&](const parser::StructureComponent &x) {
7264                       ResolveStructureComponent(x);
7265                     },
7266                 },
7267       x.u);
7268 }
7269 
7270 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
7271   const auto &dataRef{std::get<parser::DataRef>(x.t)};
7272   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
7273   const auto &expr{std::get<parser::Expr>(x.t)};
7274   ResolveDataRef(dataRef);
7275   Walk(bounds);
7276   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
7277   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
7278     if (NameIsKnownOrIntrinsic(*name)) {
7279       // If the name is known because it is an object entity from a host
7280       // procedure, create a host associated symbol.
7281       if (Symbol * symbol{name->symbol}; symbol &&
7282           symbol->GetUltimate().has<ObjectEntityDetails>() &&
7283           IsUplevelReference(*symbol)) {
7284         MakeHostAssocSymbol(*name, *symbol);
7285       }
7286       return false;
7287     }
7288   }
7289   Walk(expr);
7290   return false;
7291 }
7292 void ResolveNamesVisitor::Post(const parser::Designator &x) {
7293   ResolveDesignator(x);
7294 }
7295 
7296 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
7297   ResolveStructureComponent(x.v.thing);
7298 }
7299 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
7300   DeclTypeSpecVisitor::Post(x);
7301   ConstructVisitor::Post(x);
7302 }
7303 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
7304   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
7305   if (HandleStmtFunction(x)) {
7306     return false;
7307   } else {
7308     // This is an array element assignment: resolve names of indices
7309     const auto &names{std::get<std::list<parser::Name>>(x.t)};
7310     for (auto &name : names) {
7311       ResolveName(name);
7312     }
7313     return true;
7314   }
7315 }
7316 
7317 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
7318   const parser::Name &name{x.v};
7319   if (FindSymbol(name)) {
7320     // OK
7321   } else if (IsLogicalConstant(context(), name.source)) {
7322     Say(name,
7323         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7324   } else {
7325     // Resolved later in expression semantics
7326     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
7327   }
7328   return false;
7329 }
7330 
7331 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
7332   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7333     ConvertToObjectEntity(DEREF(name->symbol));
7334   }
7335 }
7336 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
7337   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7338     ConvertToObjectEntity(DEREF(name->symbol));
7339   }
7340 }
7341 
7342 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
7343   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
7344           x.u)) {
7345     // TODO: global directives
7346     return true;
7347   }
7348   auto root{ProgramTree::Build(x)};
7349   SetScope(topScope_);
7350   ResolveSpecificationParts(root);
7351   FinishSpecificationParts(root);
7352   ResolveExecutionParts(root);
7353   ResolveAccParts(context(), x);
7354   ResolveOmpParts(context(), x);
7355   return false;
7356 }
7357 
7358 // References to procedures need to record that their symbols are known
7359 // to be procedures, so that they don't get converted to objects by default.
7360 class ExecutionPartSkimmer {
7361 public:
7362   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
7363       : resolver_{resolver} {}
7364 
7365   void Walk(const parser::ExecutionPart *exec) {
7366     if (exec) {
7367       parser::Walk(*exec, *this);
7368     }
7369   }
7370 
7371   template <typename A> bool Pre(const A &) { return true; }
7372   template <typename A> void Post(const A &) {}
7373   void Post(const parser::FunctionReference &fr) {
7374     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
7375   }
7376   void Post(const parser::CallStmt &cs) {
7377     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
7378   }
7379 
7380 private:
7381   ResolveNamesVisitor &resolver_;
7382 };
7383 
7384 // Build the scope tree and resolve names in the specification parts of this
7385 // node and its children
7386 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
7387   if (node.isSpecificationPartResolved()) {
7388     return; // been here already
7389   }
7390   node.set_isSpecificationPartResolved();
7391   if (!BeginScopeForNode(node)) {
7392     return; // an error prevented scope from being created
7393   }
7394   Scope &scope{currScope()};
7395   node.set_scope(scope);
7396   AddSubpNames(node);
7397   common::visit(
7398       [&](const auto *x) {
7399         if (x) {
7400           Walk(*x);
7401         }
7402       },
7403       node.stmt());
7404   Walk(node.spec());
7405   // If this is a function, convert result to an object. This is to prevent the
7406   // result from being converted later to a function symbol if it is called
7407   // inside the function.
7408   // If the result is function pointer, then ConvertToObjectEntity will not
7409   // convert the result to an object, and calling the symbol inside the function
7410   // will result in calls to the result pointer.
7411   // A function cannot be called recursively if RESULT was not used to define a
7412   // distinct result name (15.6.2.2 point 4.).
7413   if (Symbol * symbol{scope.symbol()}) {
7414     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
7415       if (details->isFunction()) {
7416         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
7417       }
7418     }
7419   }
7420   if (node.IsModule()) {
7421     ApplyDefaultAccess();
7422   }
7423   for (auto &child : node.children()) {
7424     ResolveSpecificationParts(child);
7425   }
7426   ExecutionPartSkimmer{*this}.Walk(node.exec());
7427   EndScopeForNode(node);
7428   // Ensure that every object entity has a type.
7429   for (auto &pair : *node.scope()) {
7430     ApplyImplicitRules(*pair.second);
7431   }
7432 }
7433 
7434 // Add SubprogramNameDetails symbols for module and internal subprograms and
7435 // their ENTRY statements.
7436 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
7437   auto kind{
7438       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
7439   for (auto &child : node.children()) {
7440     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
7441     auto childKind{child.GetKind()};
7442     if (childKind == ProgramTree::Kind::Function) {
7443       symbol.set(Symbol::Flag::Function);
7444     } else if (childKind == ProgramTree::Kind::Subroutine) {
7445       symbol.set(Symbol::Flag::Subroutine);
7446     } else {
7447       continue; // make ENTRY symbols only where valid
7448     }
7449     for (const auto &entryStmt : child.entryStmts()) {
7450       SubprogramNameDetails details{kind, child};
7451       auto &symbol{
7452           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
7453       symbol.set(child.GetSubpFlag());
7454     }
7455   }
7456   for (const auto &generic : node.genericSpecs()) {
7457     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
7458       if (currScope().find(name->source) != currScope().end()) {
7459         // If this scope has both a generic interface and a contained
7460         // subprogram with the same name, create the generic's symbol
7461         // now so that any other generics of the same name that are pulled
7462         // into scope later via USE association will properly merge instead
7463         // of raising a bogus error due a conflict with the subprogram.
7464         CreateGeneric(*generic);
7465       }
7466     }
7467   }
7468 }
7469 
7470 // Push a new scope for this node or return false on error.
7471 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
7472   switch (node.GetKind()) {
7473     SWITCH_COVERS_ALL_CASES
7474   case ProgramTree::Kind::Program:
7475     PushScope(Scope::Kind::MainProgram,
7476         &MakeSymbol(node.name(), MainProgramDetails{}));
7477     return true;
7478   case ProgramTree::Kind::Function:
7479   case ProgramTree::Kind::Subroutine:
7480     return BeginSubprogram(node.name(), node.GetSubpFlag(),
7481         node.HasModulePrefix(), node.bindingSpec(), &node.entryStmts());
7482   case ProgramTree::Kind::MpSubprogram:
7483     return BeginMpSubprogram(node.name());
7484   case ProgramTree::Kind::Module:
7485     BeginModule(node.name(), false);
7486     return true;
7487   case ProgramTree::Kind::Submodule:
7488     return BeginSubmodule(node.name(), node.GetParentId());
7489   case ProgramTree::Kind::BlockData:
7490     PushBlockDataScope(node.name());
7491     return true;
7492   }
7493 }
7494 
7495 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
7496   std::optional<parser::CharBlock> stmtSource;
7497   const std::optional<parser::LanguageBindingSpec> *binding{nullptr};
7498   common::visit(
7499       common::visitors{
7500           [&](const parser::Statement<parser::FunctionStmt> *stmt) {
7501             if (stmt) {
7502               stmtSource = stmt->source;
7503               if (const auto &maybeSuffix{
7504                       std::get<std::optional<parser::Suffix>>(
7505                           stmt->statement.t)}) {
7506                 binding = &maybeSuffix->binding;
7507               }
7508             }
7509           },
7510           [&](const parser::Statement<parser::SubroutineStmt> *stmt) {
7511             if (stmt) {
7512               stmtSource = stmt->source;
7513               binding = &std::get<std::optional<parser::LanguageBindingSpec>>(
7514                   stmt->statement.t);
7515             }
7516           },
7517           [](const auto *) {},
7518       },
7519       node.stmt());
7520   EndSubprogram(stmtSource, binding);
7521 }
7522 
7523 // Some analyses and checks, such as the processing of initializers of
7524 // pointers, are deferred until all of the pertinent specification parts
7525 // have been visited.  This deferred processing enables the use of forward
7526 // references in these circumstances.
7527 class DeferredCheckVisitor {
7528 public:
7529   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7530       : resolver_{resolver} {}
7531 
7532   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7533 
7534   template <typename A> bool Pre(const A &) { return true; }
7535   template <typename A> void Post(const A &) {}
7536 
7537   void Post(const parser::DerivedTypeStmt &x) {
7538     const auto &name{std::get<parser::Name>(x.t)};
7539     if (Symbol * symbol{name.symbol}) {
7540       if (Scope * scope{symbol->scope()}) {
7541         if (scope->IsDerivedType()) {
7542           resolver_.PushScope(*scope);
7543           pushedScope_ = true;
7544         }
7545       }
7546     }
7547   }
7548   void Post(const parser::EndTypeStmt &) {
7549     if (pushedScope_) {
7550       resolver_.PopScope();
7551       pushedScope_ = false;
7552     }
7553   }
7554 
7555   void Post(const parser::ProcInterface &pi) {
7556     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7557       resolver_.CheckExplicitInterface(*name);
7558     }
7559   }
7560   bool Pre(const parser::EntityDecl &decl) {
7561     Init(std::get<parser::Name>(decl.t),
7562         std::get<std::optional<parser::Initialization>>(decl.t));
7563     return false;
7564   }
7565   bool Pre(const parser::ComponentDecl &decl) {
7566     Init(std::get<parser::Name>(decl.t),
7567         std::get<std::optional<parser::Initialization>>(decl.t));
7568     return false;
7569   }
7570   bool Pre(const parser::ProcDecl &decl) {
7571     if (const auto &init{
7572             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7573       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7574     }
7575     return false;
7576   }
7577   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7578     resolver_.CheckExplicitInterface(tbps.interfaceName);
7579   }
7580   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7581     if (pushedScope_) {
7582       resolver_.CheckBindings(tbps);
7583     }
7584   }
7585 
7586 private:
7587   void Init(const parser::Name &name,
7588       const std::optional<parser::Initialization> &init) {
7589     if (init) {
7590       if (const auto *target{
7591               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7592         resolver_.PointerInitialization(name, *target);
7593       }
7594     }
7595   }
7596 
7597   ResolveNamesVisitor &resolver_;
7598   bool pushedScope_{false};
7599 };
7600 
7601 // Perform checks and completions that need to happen after all of
7602 // the specification parts but before any of the execution parts.
7603 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7604   if (!node.scope()) {
7605     return; // error occurred creating scope
7606   }
7607   SetScope(*node.scope());
7608   // The initializers of pointers, the default initializers of pointer
7609   // components, and non-deferred type-bound procedure bindings have not
7610   // yet been traversed.
7611   // We do that now, when any (formerly) forward references that appear
7612   // in those initializers will resolve to the right symbols without
7613   // incurring spurious errors with IMPLICIT NONE.
7614   DeferredCheckVisitor{*this}.Walk(node.spec());
7615   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7616   for (Scope &childScope : currScope().children()) {
7617     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7618       FinishDerivedTypeInstantiation(childScope);
7619     }
7620   }
7621   for (const auto &child : node.children()) {
7622     FinishSpecificationParts(child);
7623   }
7624 }
7625 
7626 // Duplicate and fold component object pointer default initializer designators
7627 // using the actual type parameter values of each particular instantiation.
7628 // Validation is done later in declaration checking.
7629 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7630   CHECK(scope.IsDerivedType() && !scope.symbol());
7631   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7632     spec->Instantiate(currScope());
7633     const Symbol &origTypeSymbol{spec->typeSymbol()};
7634     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7635       CHECK(origTypeScope->IsDerivedType() &&
7636           origTypeScope->symbol() == &origTypeSymbol);
7637       auto &foldingContext{GetFoldingContext()};
7638       auto restorer{foldingContext.WithPDTInstance(*spec)};
7639       for (auto &pair : scope) {
7640         Symbol &comp{*pair.second};
7641         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7642         if (IsPointer(comp)) {
7643           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7644             auto origDetails{origComp.get<ObjectEntityDetails>()};
7645             if (const MaybeExpr & init{origDetails.init()}) {
7646               SomeExpr newInit{*init};
7647               MaybeExpr folded{
7648                   evaluate::Fold(foldingContext, std::move(newInit))};
7649               details->set_init(std::move(folded));
7650             }
7651           }
7652         }
7653       }
7654     }
7655   }
7656 }
7657 
7658 // Resolve names in the execution part of this node and its children
7659 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7660   if (!node.scope()) {
7661     return; // error occurred creating scope
7662   }
7663   SetScope(*node.scope());
7664   if (const auto *exec{node.exec()}) {
7665     Walk(*exec);
7666   }
7667   FinishNamelists();
7668   PopScope(); // converts unclassified entities into objects
7669   for (const auto &child : node.children()) {
7670     ResolveExecutionParts(child);
7671   }
7672 }
7673 
7674 void ResolveNamesVisitor::Post(const parser::Program &) {
7675   // ensure that all temps were deallocated
7676   CHECK(!attrs_);
7677   CHECK(!GetDeclTypeSpec());
7678 }
7679 
7680 // A singleton instance of the scope -> IMPLICIT rules mapping is
7681 // shared by all instances of ResolveNamesVisitor and accessed by this
7682 // pointer when the visitors (other than the top-level original) are
7683 // constructed.
7684 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7685 
7686 bool ResolveNames(
7687     SemanticsContext &context, const parser::Program &program, Scope &top) {
7688   ImplicitRulesMap implicitRulesMap;
7689   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7690   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7691   return !context.AnyFatalError();
7692 }
7693 
7694 // Processes a module (but not internal) function when it is referenced
7695 // in a specification expression in a sibling procedure.
7696 void ResolveSpecificationParts(
7697     SemanticsContext &context, const Symbol &subprogram) {
7698   auto originalLocation{context.location()};
7699   ImplicitRulesMap implicitRulesMap;
7700   bool localImplicitRulesMap{false};
7701   if (!sharedImplicitRulesMap) {
7702     sharedImplicitRulesMap = &implicitRulesMap;
7703     localImplicitRulesMap = true;
7704   }
7705   ResolveNamesVisitor visitor{
7706       context, *sharedImplicitRulesMap, context.globalScope()};
7707   const auto &details{subprogram.get<SubprogramNameDetails>()};
7708   ProgramTree &node{details.node()};
7709   const Scope &moduleScope{subprogram.owner()};
7710   if (localImplicitRulesMap) {
7711     visitor.BeginScope(const_cast<Scope &>(moduleScope));
7712   } else {
7713     visitor.SetScope(const_cast<Scope &>(moduleScope));
7714   }
7715   visitor.ResolveSpecificationParts(node);
7716   context.set_location(std::move(originalLocation));
7717   if (localImplicitRulesMap) {
7718     sharedImplicitRulesMap = nullptr;
7719   }
7720 }
7721 
7722 } // namespace Fortran::semantics
7723