1 //===-- lib/Semantics/resolve-names.cpp -----------------------------------===//
2 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
3 // See https://llvm.org/LICENSE.txt for license information.
4 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
5 //
6 //===----------------------------------------------------------------------===//
7 
8 #include "resolve-names.h"
9 #include "assignment.h"
10 #include "mod-file.h"
11 #include "pointer-assignment.h"
12 #include "program-tree.h"
13 #include "resolve-directives.h"
14 #include "resolve-names-utils.h"
15 #include "rewrite-parse-tree.h"
16 #include "flang/Common/Fortran.h"
17 #include "flang/Common/default-kinds.h"
18 #include "flang/Common/indirection.h"
19 #include "flang/Common/restorer.h"
20 #include "flang/Evaluate/characteristics.h"
21 #include "flang/Evaluate/check-expression.h"
22 #include "flang/Evaluate/common.h"
23 #include "flang/Evaluate/fold-designator.h"
24 #include "flang/Evaluate/fold.h"
25 #include "flang/Evaluate/intrinsics.h"
26 #include "flang/Evaluate/tools.h"
27 #include "flang/Evaluate/type.h"
28 #include "flang/Parser/parse-tree-visitor.h"
29 #include "flang/Parser/parse-tree.h"
30 #include "flang/Parser/tools.h"
31 #include "flang/Semantics/attr.h"
32 #include "flang/Semantics/expression.h"
33 #include "flang/Semantics/scope.h"
34 #include "flang/Semantics/semantics.h"
35 #include "flang/Semantics/symbol.h"
36 #include "flang/Semantics/tools.h"
37 #include "flang/Semantics/type.h"
38 #include "llvm/Support/raw_ostream.h"
39 #include <list>
40 #include <map>
41 #include <set>
42 #include <stack>
43 
44 namespace Fortran::semantics {
45 
46 using namespace parser::literals;
47 
48 template <typename T> using Indirection = common::Indirection<T>;
49 using Message = parser::Message;
50 using Messages = parser::Messages;
51 using MessageFixedText = parser::MessageFixedText;
52 using MessageFormattedText = parser::MessageFormattedText;
53 
54 class ResolveNamesVisitor;
55 class ScopeHandler;
56 
57 // ImplicitRules maps initial character of identifier to the DeclTypeSpec
58 // representing the implicit type; std::nullopt if none.
59 // It also records the presence of IMPLICIT NONE statements.
60 // When inheritFromParent is set, defaults come from the parent rules.
61 class ImplicitRules {
62 public:
63   ImplicitRules(SemanticsContext &context, ImplicitRules *parent)
64       : parent_{parent}, context_{context} {
65     inheritFromParent_ = parent != nullptr;
66   }
67   bool isImplicitNoneType() const;
68   bool isImplicitNoneExternal() const;
69   void set_isImplicitNoneType(bool x) { isImplicitNoneType_ = x; }
70   void set_isImplicitNoneExternal(bool x) { isImplicitNoneExternal_ = x; }
71   void set_inheritFromParent(bool x) { inheritFromParent_ = x; }
72   // Get the implicit type for this name. May be null.
73   const DeclTypeSpec *GetType(
74       SourceName, bool respectImplicitNone = true) const;
75   // Record the implicit type for the range of characters [fromLetter,
76   // toLetter].
77   void SetTypeMapping(const DeclTypeSpec &type, parser::Location fromLetter,
78       parser::Location toLetter);
79 
80 private:
81   static char Incr(char ch);
82 
83   ImplicitRules *parent_;
84   SemanticsContext &context_;
85   bool inheritFromParent_{false}; // look in parent if not specified here
86   bool isImplicitNoneType_{
87       context_.IsEnabled(common::LanguageFeature::ImplicitNoneTypeAlways)};
88   bool isImplicitNoneExternal_{false};
89   // map_ contains the mapping between letters and types that were defined
90   // by the IMPLICIT statements of the related scope. It does not contain
91   // the default Fortran mappings nor the mapping defined in parents.
92   std::map<char, common::Reference<const DeclTypeSpec>> map_;
93 
94   friend llvm::raw_ostream &operator<<(
95       llvm::raw_ostream &, const ImplicitRules &);
96   friend void ShowImplicitRule(
97       llvm::raw_ostream &, const ImplicitRules &, char);
98 };
99 
100 // scope -> implicit rules for that scope
101 using ImplicitRulesMap = std::map<const Scope *, ImplicitRules>;
102 
103 // Track statement source locations and save messages.
104 class MessageHandler {
105 public:
106   MessageHandler() { DIE("MessageHandler: default-constructed"); }
107   explicit MessageHandler(SemanticsContext &c) : context_{&c} {}
108   Messages &messages() { return context_->messages(); };
109   const std::optional<SourceName> &currStmtSource() {
110     return context_->location();
111   }
112   void set_currStmtSource(const std::optional<SourceName> &source) {
113     context_->set_location(source);
114   }
115 
116   // Emit a message associated with the current statement source.
117   Message &Say(MessageFixedText &&);
118   Message &Say(MessageFormattedText &&);
119   // Emit a message about a SourceName
120   Message &Say(const SourceName &, MessageFixedText &&);
121   // Emit a formatted message associated with a source location.
122   template <typename... A>
123   Message &Say(const SourceName &source, MessageFixedText &&msg, A &&...args) {
124     return context_->Say(source, std::move(msg), std::forward<A>(args)...);
125   }
126 
127 private:
128   SemanticsContext *context_;
129 };
130 
131 // Inheritance graph for the parse tree visitation classes that follow:
132 //   BaseVisitor
133 //   + AttrsVisitor
134 //   | + DeclTypeSpecVisitor
135 //   |   + ImplicitRulesVisitor
136 //   |     + ScopeHandler -----------+--+
137 //   |       + ModuleVisitor ========|==+
138 //   |       + InterfaceVisitor      |  |
139 //   |       +-+ SubprogramVisitor ==|==+
140 //   + ArraySpecVisitor              |  |
141 //     + DeclarationVisitor <--------+  |
142 //       + ConstructVisitor             |
143 //         + ResolveNamesVisitor <------+
144 
145 class BaseVisitor {
146 public:
147   BaseVisitor() { DIE("BaseVisitor: default-constructed"); }
148   BaseVisitor(
149       SemanticsContext &c, ResolveNamesVisitor &v, ImplicitRulesMap &rules)
150       : implicitRulesMap_{&rules}, this_{&v}, context_{&c}, messageHandler_{c} {
151   }
152   template <typename T> void Walk(const T &);
153 
154   MessageHandler &messageHandler() { return messageHandler_; }
155   const std::optional<SourceName> &currStmtSource() {
156     return context_->location();
157   }
158   SemanticsContext &context() const { return *context_; }
159   evaluate::FoldingContext &GetFoldingContext() const {
160     return context_->foldingContext();
161   }
162   bool IsIntrinsic(
163       const SourceName &name, std::optional<Symbol::Flag> flag) const {
164     if (!flag) {
165       return context_->intrinsics().IsIntrinsic(name.ToString());
166     } else if (flag == Symbol::Flag::Function) {
167       return context_->intrinsics().IsIntrinsicFunction(name.ToString());
168     } else if (flag == Symbol::Flag::Subroutine) {
169       return context_->intrinsics().IsIntrinsicSubroutine(name.ToString());
170     } else {
171       DIE("expected Subroutine or Function flag");
172     }
173   }
174 
175   // Make a placeholder symbol for a Name that otherwise wouldn't have one.
176   // It is not in any scope and always has MiscDetails.
177   void MakePlaceholder(const parser::Name &, MiscDetails::Kind);
178 
179   template <typename T> common::IfNoLvalue<T, T> FoldExpr(T &&expr) {
180     return evaluate::Fold(GetFoldingContext(), std::move(expr));
181   }
182 
183   template <typename T> MaybeExpr EvaluateExpr(const T &expr) {
184     return FoldExpr(AnalyzeExpr(*context_, expr));
185   }
186 
187   template <typename T>
188   MaybeExpr EvaluateNonPointerInitializer(
189       const Symbol &symbol, const T &expr, parser::CharBlock source) {
190     if (!context().HasError(symbol)) {
191       if (auto maybeExpr{AnalyzeExpr(*context_, expr)}) {
192         auto restorer{GetFoldingContext().messages().SetLocation(source)};
193         return evaluate::NonPointerInitializationExpr(
194             symbol, std::move(*maybeExpr), GetFoldingContext());
195       }
196     }
197     return std::nullopt;
198   }
199 
200   template <typename T> MaybeIntExpr EvaluateIntExpr(const T &expr) {
201     return semantics::EvaluateIntExpr(*context_, expr);
202   }
203 
204   template <typename T>
205   MaybeSubscriptIntExpr EvaluateSubscriptIntExpr(const T &expr) {
206     if (MaybeIntExpr maybeIntExpr{EvaluateIntExpr(expr)}) {
207       return FoldExpr(evaluate::ConvertToType<evaluate::SubscriptInteger>(
208           std::move(*maybeIntExpr)));
209     } else {
210       return std::nullopt;
211     }
212   }
213 
214   template <typename... A> Message &Say(A &&...args) {
215     return messageHandler_.Say(std::forward<A>(args)...);
216   }
217   template <typename... A>
218   Message &Say(
219       const parser::Name &name, MessageFixedText &&text, const A &...args) {
220     return messageHandler_.Say(name.source, std::move(text), args...);
221   }
222 
223 protected:
224   ImplicitRulesMap *implicitRulesMap_{nullptr};
225 
226 private:
227   ResolveNamesVisitor *this_;
228   SemanticsContext *context_;
229   MessageHandler messageHandler_;
230 };
231 
232 // Provide Post methods to collect attributes into a member variable.
233 class AttrsVisitor : public virtual BaseVisitor {
234 public:
235   bool BeginAttrs(); // always returns true
236   Attrs GetAttrs();
237   Attrs EndAttrs();
238   bool SetPassNameOn(Symbol &);
239   void SetBindNameOn(Symbol &);
240   void Post(const parser::LanguageBindingSpec &);
241   bool Pre(const parser::IntentSpec &);
242   bool Pre(const parser::Pass &);
243 
244   bool CheckAndSet(Attr);
245 
246 // Simple case: encountering CLASSNAME causes ATTRNAME to be set.
247 #define HANDLE_ATTR_CLASS(CLASSNAME, ATTRNAME) \
248   bool Pre(const parser::CLASSNAME &) { \
249     CheckAndSet(Attr::ATTRNAME); \
250     return false; \
251   }
252   HANDLE_ATTR_CLASS(PrefixSpec::Elemental, ELEMENTAL)
253   HANDLE_ATTR_CLASS(PrefixSpec::Impure, IMPURE)
254   HANDLE_ATTR_CLASS(PrefixSpec::Module, MODULE)
255   HANDLE_ATTR_CLASS(PrefixSpec::Non_Recursive, NON_RECURSIVE)
256   HANDLE_ATTR_CLASS(PrefixSpec::Pure, PURE)
257   HANDLE_ATTR_CLASS(PrefixSpec::Recursive, RECURSIVE)
258   HANDLE_ATTR_CLASS(TypeAttrSpec::BindC, BIND_C)
259   HANDLE_ATTR_CLASS(BindAttr::Deferred, DEFERRED)
260   HANDLE_ATTR_CLASS(BindAttr::Non_Overridable, NON_OVERRIDABLE)
261   HANDLE_ATTR_CLASS(Abstract, ABSTRACT)
262   HANDLE_ATTR_CLASS(Allocatable, ALLOCATABLE)
263   HANDLE_ATTR_CLASS(Asynchronous, ASYNCHRONOUS)
264   HANDLE_ATTR_CLASS(Contiguous, CONTIGUOUS)
265   HANDLE_ATTR_CLASS(External, EXTERNAL)
266   HANDLE_ATTR_CLASS(Intrinsic, INTRINSIC)
267   HANDLE_ATTR_CLASS(NoPass, NOPASS)
268   HANDLE_ATTR_CLASS(Optional, OPTIONAL)
269   HANDLE_ATTR_CLASS(Parameter, PARAMETER)
270   HANDLE_ATTR_CLASS(Pointer, POINTER)
271   HANDLE_ATTR_CLASS(Protected, PROTECTED)
272   HANDLE_ATTR_CLASS(Save, SAVE)
273   HANDLE_ATTR_CLASS(Target, TARGET)
274   HANDLE_ATTR_CLASS(Value, VALUE)
275   HANDLE_ATTR_CLASS(Volatile, VOLATILE)
276 #undef HANDLE_ATTR_CLASS
277 
278 protected:
279   std::optional<Attrs> attrs_;
280 
281   Attr AccessSpecToAttr(const parser::AccessSpec &x) {
282     switch (x.v) {
283     case parser::AccessSpec::Kind::Public:
284       return Attr::PUBLIC;
285     case parser::AccessSpec::Kind::Private:
286       return Attr::PRIVATE;
287     }
288     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
289   }
290   Attr IntentSpecToAttr(const parser::IntentSpec &x) {
291     switch (x.v) {
292     case parser::IntentSpec::Intent::In:
293       return Attr::INTENT_IN;
294     case parser::IntentSpec::Intent::Out:
295       return Attr::INTENT_OUT;
296     case parser::IntentSpec::Intent::InOut:
297       return Attr::INTENT_INOUT;
298     }
299     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
300   }
301 
302 private:
303   bool IsDuplicateAttr(Attr);
304   bool HaveAttrConflict(Attr, Attr, Attr);
305   bool IsConflictingAttr(Attr);
306 
307   MaybeExpr bindName_; // from BIND(C, NAME="...")
308   std::optional<SourceName> passName_; // from PASS(...)
309 };
310 
311 // Find and create types from declaration-type-spec nodes.
312 class DeclTypeSpecVisitor : public AttrsVisitor {
313 public:
314   using AttrsVisitor::Post;
315   using AttrsVisitor::Pre;
316   void Post(const parser::IntrinsicTypeSpec::DoublePrecision &);
317   void Post(const parser::IntrinsicTypeSpec::DoubleComplex &);
318   void Post(const parser::DeclarationTypeSpec::ClassStar &);
319   void Post(const parser::DeclarationTypeSpec::TypeStar &);
320   bool Pre(const parser::TypeGuardStmt &);
321   void Post(const parser::TypeGuardStmt &);
322   void Post(const parser::TypeSpec &);
323 
324   // Walk the parse tree of a type spec and return the DeclTypeSpec for it.
325   template <typename T>
326   const DeclTypeSpec *ProcessTypeSpec(const T &x, bool allowForward = false) {
327     auto restorer{common::ScopedSet(state_, State{})};
328     set_allowForwardReferenceToDerivedType(allowForward);
329     BeginDeclTypeSpec();
330     Walk(x);
331     const auto *type{GetDeclTypeSpec()};
332     EndDeclTypeSpec();
333     return type;
334   }
335 
336 protected:
337   struct State {
338     bool expectDeclTypeSpec{false}; // should see decl-type-spec only when true
339     const DeclTypeSpec *declTypeSpec{nullptr};
340     struct {
341       DerivedTypeSpec *type{nullptr};
342       DeclTypeSpec::Category category{DeclTypeSpec::TypeDerived};
343     } derived;
344     bool allowForwardReferenceToDerivedType{false};
345   };
346 
347   bool allowForwardReferenceToDerivedType() const {
348     return state_.allowForwardReferenceToDerivedType;
349   }
350   void set_allowForwardReferenceToDerivedType(bool yes) {
351     state_.allowForwardReferenceToDerivedType = yes;
352   }
353 
354   const DeclTypeSpec *GetDeclTypeSpec();
355   void BeginDeclTypeSpec();
356   void EndDeclTypeSpec();
357   void SetDeclTypeSpec(const DeclTypeSpec &);
358   void SetDeclTypeSpecCategory(DeclTypeSpec::Category);
359   DeclTypeSpec::Category GetDeclTypeSpecCategory() const {
360     return state_.derived.category;
361   }
362   KindExpr GetKindParamExpr(
363       TypeCategory, const std::optional<parser::KindSelector> &);
364   void CheckForAbstractType(const Symbol &typeSymbol);
365 
366 private:
367   State state_;
368 
369   void MakeNumericType(TypeCategory, int kind);
370 };
371 
372 // Visit ImplicitStmt and related parse tree nodes and updates implicit rules.
373 class ImplicitRulesVisitor : public DeclTypeSpecVisitor {
374 public:
375   using DeclTypeSpecVisitor::Post;
376   using DeclTypeSpecVisitor::Pre;
377   using ImplicitNoneNameSpec = parser::ImplicitStmt::ImplicitNoneNameSpec;
378 
379   void Post(const parser::ParameterStmt &);
380   bool Pre(const parser::ImplicitStmt &);
381   bool Pre(const parser::LetterSpec &);
382   bool Pre(const parser::ImplicitSpec &);
383   void Post(const parser::ImplicitSpec &);
384 
385   const DeclTypeSpec *GetType(
386       SourceName name, bool respectImplicitNoneType = true) {
387     return implicitRules_->GetType(name, respectImplicitNoneType);
388   }
389   bool isImplicitNoneType() const {
390     return implicitRules_->isImplicitNoneType();
391   }
392   bool isImplicitNoneType(const Scope &scope) const {
393     return implicitRulesMap_->at(&scope).isImplicitNoneType();
394   }
395   bool isImplicitNoneExternal() const {
396     return implicitRules_->isImplicitNoneExternal();
397   }
398   void set_inheritFromParent(bool x) {
399     implicitRules_->set_inheritFromParent(x);
400   }
401 
402 protected:
403   void BeginScope(const Scope &);
404   void SetScope(const Scope &);
405 
406 private:
407   // implicit rules in effect for current scope
408   ImplicitRules *implicitRules_{nullptr};
409   std::optional<SourceName> prevImplicit_;
410   std::optional<SourceName> prevImplicitNone_;
411   std::optional<SourceName> prevImplicitNoneType_;
412   std::optional<SourceName> prevParameterStmt_;
413 
414   bool HandleImplicitNone(const std::list<ImplicitNoneNameSpec> &nameSpecs);
415 };
416 
417 // Track array specifications. They can occur in AttrSpec, EntityDecl,
418 // ObjectDecl, DimensionStmt, CommonBlockObject, or BasedPointerStmt.
419 // 1. INTEGER, DIMENSION(10) :: x
420 // 2. INTEGER :: x(10)
421 // 3. ALLOCATABLE :: x(:)
422 // 4. DIMENSION :: x(10)
423 // 5. COMMON x(10)
424 // 6. BasedPointerStmt
425 class ArraySpecVisitor : public virtual BaseVisitor {
426 public:
427   void Post(const parser::ArraySpec &);
428   void Post(const parser::ComponentArraySpec &);
429   void Post(const parser::CoarraySpec &);
430   void Post(const parser::AttrSpec &) { PostAttrSpec(); }
431   void Post(const parser::ComponentAttrSpec &) { PostAttrSpec(); }
432 
433 protected:
434   const ArraySpec &arraySpec();
435   void set_arraySpec(const ArraySpec arraySpec) { arraySpec_ = arraySpec; }
436   const ArraySpec &coarraySpec();
437   void BeginArraySpec();
438   void EndArraySpec();
439   void ClearArraySpec() { arraySpec_.clear(); }
440   void ClearCoarraySpec() { coarraySpec_.clear(); }
441 
442 private:
443   // arraySpec_/coarraySpec_ are populated from any ArraySpec/CoarraySpec
444   ArraySpec arraySpec_;
445   ArraySpec coarraySpec_;
446   // When an ArraySpec is under an AttrSpec or ComponentAttrSpec, it is moved
447   // into attrArraySpec_
448   ArraySpec attrArraySpec_;
449   ArraySpec attrCoarraySpec_;
450 
451   void PostAttrSpec();
452 };
453 
454 // Manages a stack of function result information.  We defer the processing
455 // of a type specification that appears in the prefix of a FUNCTION statement
456 // until the function result variable appears in the specification part
457 // or the end of the specification part.  This allows for forward references
458 // in the type specification to resolve to local names.
459 class FuncResultStack {
460 public:
461   explicit FuncResultStack(ScopeHandler &scopeHandler)
462       : scopeHandler_{scopeHandler} {}
463   ~FuncResultStack();
464 
465   struct FuncInfo {
466     // Parse tree of the type specification in the FUNCTION prefix
467     const parser::DeclarationTypeSpec *parsedType{nullptr};
468     // Name of the function RESULT in the FUNCTION suffix, if any
469     const parser::Name *resultName{nullptr};
470     // Result symbol
471     Symbol *resultSymbol{nullptr};
472     std::optional<SourceName> source;
473     bool inFunctionStmt{false}; // true between Pre/Post of FunctionStmt
474   };
475 
476   // Completes the definition of the top function's result.
477   void CompleteFunctionResultType();
478   // Completes the definition of a symbol if it is the top function's result.
479   void CompleteTypeIfFunctionResult(Symbol &);
480 
481   FuncInfo *Top() { return stack_.empty() ? nullptr : &stack_.back(); }
482   FuncInfo &Push() { return stack_.emplace_back(); }
483   void Pop() { stack_.pop_back(); }
484 
485 private:
486   ScopeHandler &scopeHandler_;
487   std::vector<FuncInfo> stack_;
488 };
489 
490 // Manage a stack of Scopes
491 class ScopeHandler : public ImplicitRulesVisitor {
492 public:
493   using ImplicitRulesVisitor::Post;
494   using ImplicitRulesVisitor::Pre;
495 
496   Scope &currScope() { return DEREF(currScope_); }
497   // The enclosing host procedure if current scope is in an internal procedure
498   Scope *GetHostProcedure();
499   // The innermost enclosing program unit scope, ignoring BLOCK and other
500   // construct scopes.
501   Scope &InclusiveScope();
502   // The enclosing scope, skipping derived types.
503   Scope &NonDerivedTypeScope();
504 
505   // Create a new scope and push it on the scope stack.
506   void PushScope(Scope::Kind kind, Symbol *symbol);
507   void PushScope(Scope &scope);
508   void PopScope();
509   void SetScope(Scope &);
510 
511   template <typename T> bool Pre(const parser::Statement<T> &x) {
512     messageHandler().set_currStmtSource(x.source);
513     currScope_->AddSourceRange(x.source);
514     return true;
515   }
516   template <typename T> void Post(const parser::Statement<T> &) {
517     messageHandler().set_currStmtSource(std::nullopt);
518   }
519 
520   // Special messages: already declared; referencing symbol's declaration;
521   // about a type; two names & locations
522   void SayAlreadyDeclared(const parser::Name &, Symbol &);
523   void SayAlreadyDeclared(const SourceName &, Symbol &);
524   void SayAlreadyDeclared(const SourceName &, const SourceName &);
525   void SayWithReason(
526       const parser::Name &, Symbol &, MessageFixedText &&, Message &&);
527   void SayWithDecl(const parser::Name &, Symbol &, MessageFixedText &&);
528   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
529   void SayDerivedType(const SourceName &, MessageFixedText &&, const Scope &);
530   void Say2(const SourceName &, MessageFixedText &&, const SourceName &,
531       MessageFixedText &&);
532   void Say2(
533       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
534   void Say2(
535       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
536 
537   // Search for symbol by name in current, parent derived type, and
538   // containing scopes
539   Symbol *FindSymbol(const parser::Name &);
540   Symbol *FindSymbol(const Scope &, const parser::Name &);
541   // Search for name only in scope, not in enclosing scopes.
542   Symbol *FindInScope(const Scope &, const parser::Name &);
543   Symbol *FindInScope(const Scope &, const SourceName &);
544   template <typename T> Symbol *FindInScope(const T &name) {
545     return FindInScope(currScope(), name);
546   }
547   // Search for name in a derived type scope and its parents.
548   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
549   Symbol *FindInTypeOrParents(const parser::Name &);
550   void EraseSymbol(const parser::Name &);
551   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
552   // Make a new symbol with the name and attrs of an existing one
553   Symbol &CopySymbol(const SourceName &, const Symbol &);
554 
555   // Make symbols in the current or named scope
556   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
557   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
558   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
559   Symbol &MakeHostAssocSymbol(const parser::Name &, const Symbol &);
560 
561   template <typename D>
562   common::IfNoLvalue<Symbol &, D> MakeSymbol(
563       const parser::Name &name, D &&details) {
564     return MakeSymbol(name, Attrs{}, std::move(details));
565   }
566 
567   template <typename D>
568   common::IfNoLvalue<Symbol &, D> MakeSymbol(
569       const parser::Name &name, const Attrs &attrs, D &&details) {
570     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
571   }
572 
573   template <typename D>
574   common::IfNoLvalue<Symbol &, D> MakeSymbol(
575       const SourceName &name, const Attrs &attrs, D &&details) {
576     // Note: don't use FindSymbol here. If this is a derived type scope,
577     // we want to detect whether the name is already declared as a component.
578     auto *symbol{FindInScope(name)};
579     if (!symbol) {
580       symbol = &MakeSymbol(name, attrs);
581       symbol->set_details(std::move(details));
582       return *symbol;
583     }
584     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
585       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
586         if (!d->specific()) {
587           // derived type with same name as a generic
588           auto *derivedType{d->derivedType()};
589           if (!derivedType) {
590             derivedType =
591                 &currScope().MakeSymbol(name, attrs, std::move(details));
592             d->set_derivedType(*derivedType);
593           } else {
594             SayAlreadyDeclared(name, *derivedType);
595           }
596           return *derivedType;
597         }
598       }
599     }
600     if (symbol->CanReplaceDetails(details)) {
601       // update the existing symbol
602       symbol->attrs() |= attrs;
603       if constexpr (std::is_same_v<SubprogramDetails, D>) {
604         // Dummy argument defined by explicit interface
605         details.set_isDummy(IsDummy(*symbol));
606       }
607       symbol->set_details(std::move(details));
608       return *symbol;
609     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
610       symbol->attrs() |= attrs;
611       return *symbol;
612     } else {
613       if (!CheckPossibleBadForwardRef(*symbol)) {
614         SayAlreadyDeclared(name, *symbol);
615       }
616       // replace the old symbol with a new one with correct details
617       EraseSymbol(*symbol);
618       auto &result{MakeSymbol(name, attrs, std::move(details))};
619       context().SetError(result);
620       return result;
621     }
622   }
623 
624   void MakeExternal(Symbol &);
625 
626 protected:
627   FuncResultStack &funcResultStack() { return funcResultStack_; }
628 
629   // Apply the implicit type rules to this symbol.
630   void ApplyImplicitRules(Symbol &, bool allowForwardReference = false);
631   bool ImplicitlyTypeForwardRef(Symbol &);
632   void AcquireIntrinsicProcedureFlags(Symbol &);
633   const DeclTypeSpec *GetImplicitType(
634       Symbol &, bool respectImplicitNoneType = true);
635   bool ConvertToObjectEntity(Symbol &);
636   bool ConvertToProcEntity(Symbol &);
637 
638   const DeclTypeSpec &MakeNumericType(
639       TypeCategory, const std::optional<parser::KindSelector> &);
640   const DeclTypeSpec &MakeLogicalType(
641       const std::optional<parser::KindSelector> &);
642   void NotePossibleBadForwardRef(const parser::Name &);
643   std::optional<SourceName> HadForwardRef(const Symbol &) const;
644   bool CheckPossibleBadForwardRef(const Symbol &);
645 
646   bool inExecutionPart_{false};
647   bool inSpecificationPart_{false};
648   bool inEquivalenceStmt_{false};
649 
650   // Some information is collected from a specification part for deferred
651   // processing in DeclarationPartVisitor functions (e.g., CheckSaveStmts())
652   // that are called by ResolveNamesVisitor::FinishSpecificationPart().  Since
653   // specification parts can nest (e.g., INTERFACE bodies), the collected
654   // information that is not contained in the scope needs to be packaged
655   // and restorable.
656   struct SpecificationPartState {
657     std::set<SourceName> forwardRefs;
658     // Collect equivalence sets and process at end of specification part
659     std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets;
660     // Names of all common block objects in the scope
661     std::set<SourceName> commonBlockObjects;
662     // Info about about SAVE statements and attributes in current scope
663     struct {
664       std::optional<SourceName> saveAll; // "SAVE" without entity list
665       std::set<SourceName> entities; // names of entities with save attr
666       std::set<SourceName> commons; // names of common blocks with save attr
667     } saveInfo;
668   } specPartState_;
669 
670   // Some declaration processing can and should be deferred to
671   // ResolveExecutionParts() to avoid prematurely creating implicitly-typed
672   // local symbols that should be host associations.
673   struct DeferredDeclarationState {
674     // The content of each namelist group
675     std::list<const parser::NamelistStmt::Group *> namelistGroups;
676   };
677   DeferredDeclarationState *GetDeferredDeclarationState(bool add = false) {
678     if (!add && deferred_.find(&currScope()) == deferred_.end()) {
679       return nullptr;
680     } else {
681       return &deferred_.emplace(&currScope(), DeferredDeclarationState{})
682                   .first->second;
683     }
684   }
685 
686 private:
687   Scope *currScope_{nullptr};
688   FuncResultStack funcResultStack_{*this};
689   std::map<Scope *, DeferredDeclarationState> deferred_;
690 };
691 
692 class ModuleVisitor : public virtual ScopeHandler {
693 public:
694   bool Pre(const parser::AccessStmt &);
695   bool Pre(const parser::Only &);
696   bool Pre(const parser::Rename::Names &);
697   bool Pre(const parser::Rename::Operators &);
698   bool Pre(const parser::UseStmt &);
699   void Post(const parser::UseStmt &);
700 
701   void BeginModule(const parser::Name &, bool isSubmodule);
702   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
703   void ApplyDefaultAccess();
704   Symbol &AddGenericUse(GenericDetails &, const SourceName &, const Symbol &);
705   void AddAndCheckExplicitIntrinsicUse(SourceName, bool isIntrinsic);
706   void ClearUseRenames() { useRenames_.clear(); }
707   void ClearUseOnly() { useOnly_.clear(); }
708   void ClearExplicitIntrinsicUses() {
709     explicitIntrinsicUses_.clear();
710     explicitNonIntrinsicUses_.clear();
711   }
712 
713 private:
714   // The default access spec for this module.
715   Attr defaultAccess_{Attr::PUBLIC};
716   // The location of the last AccessStmt without access-ids, if any.
717   std::optional<SourceName> prevAccessStmt_;
718   // The scope of the module during a UseStmt
719   Scope *useModuleScope_{nullptr};
720   // Names that have appeared in a rename clause of a USE statement
721   std::set<std::pair<SourceName, Scope *>> useRenames_;
722   // Names that have appeared in an ONLY clause of a USE statement
723   std::set<std::pair<SourceName, Scope *>> useOnly_;
724   // Module names that have appeared in USE statements with explicit
725   // INTRINSIC or NON_INTRINSIC keywords
726   std::set<SourceName> explicitIntrinsicUses_;
727   std::set<SourceName> explicitNonIntrinsicUses_;
728 
729   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
730   // A rename in a USE statement: local => use
731   struct SymbolRename {
732     Symbol *local{nullptr};
733     Symbol *use{nullptr};
734   };
735   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
736   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
737   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
738   void DoAddUse(
739       SourceName, SourceName, Symbol &localSymbol, const Symbol &useSymbol);
740   void AddUse(const GenericSpecInfo &);
741   // If appropriate, erase a previously USE-associated symbol
742   void EraseRenamedSymbol(const Symbol &);
743   // Record a name appearing in a USE rename clause
744   void AddUseRename(const SourceName &name) {
745     useRenames_.emplace(std::make_pair(name, useModuleScope_));
746   }
747   bool IsUseRenamed(const SourceName &name) const {
748     return useRenames_.find({name, useModuleScope_}) != useRenames_.end();
749   }
750   // Record a name appearing in a USE ONLY clause
751   void AddUseOnly(const SourceName &name) {
752     useOnly_.emplace(std::make_pair(name, useModuleScope_));
753   }
754   bool IsUseOnly(const SourceName &name) const {
755     return useOnly_.find({name, useModuleScope_}) != useOnly_.end();
756   }
757   Scope *FindModule(const parser::Name &, std::optional<bool> isIntrinsic,
758       Scope *ancestor = nullptr);
759 };
760 
761 class InterfaceVisitor : public virtual ScopeHandler {
762 public:
763   bool Pre(const parser::InterfaceStmt &);
764   void Post(const parser::InterfaceStmt &);
765   void Post(const parser::EndInterfaceStmt &);
766   bool Pre(const parser::GenericSpec &);
767   bool Pre(const parser::ProcedureStmt &);
768   bool Pre(const parser::GenericStmt &);
769   void Post(const parser::GenericStmt &);
770 
771   bool inInterfaceBlock() const;
772   bool isGeneric() const;
773   bool isAbstract() const;
774 
775 protected:
776   Symbol &GetGenericSymbol() {
777     return DEREF(genericInfo_.top().symbol);
778   }
779   // Add to generic the symbol for the subprogram with the same name
780   void CheckGenericProcedures(Symbol &);
781 
782 private:
783   // A new GenericInfo is pushed for each interface block and generic stmt
784   struct GenericInfo {
785     GenericInfo(bool isInterface, bool isAbstract = false)
786         : isInterface{isInterface}, isAbstract{isAbstract} {}
787     bool isInterface; // in interface block
788     bool isAbstract; // in abstract interface block
789     Symbol *symbol{nullptr}; // the generic symbol being defined
790   };
791   std::stack<GenericInfo> genericInfo_;
792   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
793   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
794 
795   using ProcedureKind = parser::ProcedureStmt::Kind;
796   // mapping of generic to its specific proc names and kinds
797   std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>
798       specificProcs_;
799 
800   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
801   void ResolveSpecificsInGeneric(Symbol &generic);
802 };
803 
804 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
805 public:
806   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
807   bool Pre(const parser::SubroutineStmt &);
808   void Post(const parser::SubroutineStmt &);
809   bool Pre(const parser::FunctionStmt &);
810   void Post(const parser::FunctionStmt &);
811   bool Pre(const parser::EntryStmt &);
812   void Post(const parser::EntryStmt &);
813   bool Pre(const parser::InterfaceBody::Subroutine &);
814   void Post(const parser::InterfaceBody::Subroutine &);
815   bool Pre(const parser::InterfaceBody::Function &);
816   void Post(const parser::InterfaceBody::Function &);
817   bool Pre(const parser::Suffix &);
818   bool Pre(const parser::PrefixSpec &);
819 
820   bool BeginSubprogram(
821       const parser::Name &, Symbol::Flag, bool hasModulePrefix = false);
822   bool BeginMpSubprogram(const parser::Name &);
823   void PushBlockDataScope(const parser::Name &);
824   void EndSubprogram();
825 
826 protected:
827   // Set when we see a stmt function that is really an array element assignment
828   bool badStmtFuncFound_{false};
829 
830 private:
831   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
832   // so that it can be replaced by a later definition.
833   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
834   void CheckExtantProc(const parser::Name &, Symbol::Flag);
835   // Create a subprogram symbol in the current scope and push a new scope.
836   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag);
837   Symbol *GetSpecificFromGeneric(const parser::Name &);
838   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
839 };
840 
841 class DeclarationVisitor : public ArraySpecVisitor,
842                            public virtual ScopeHandler {
843 public:
844   using ArraySpecVisitor::Post;
845   using ScopeHandler::Post;
846   using ScopeHandler::Pre;
847 
848   bool Pre(const parser::Initialization &);
849   void Post(const parser::EntityDecl &);
850   void Post(const parser::ObjectDecl &);
851   void Post(const parser::PointerDecl &);
852   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
853   void Post(const parser::BindStmt &) { EndAttrs(); }
854   bool Pre(const parser::BindEntity &);
855   bool Pre(const parser::OldParameterStmt &);
856   bool Pre(const parser::NamedConstantDef &);
857   bool Pre(const parser::NamedConstant &);
858   void Post(const parser::EnumDef &);
859   bool Pre(const parser::Enumerator &);
860   bool Pre(const parser::AccessSpec &);
861   bool Pre(const parser::AsynchronousStmt &);
862   bool Pre(const parser::ContiguousStmt &);
863   bool Pre(const parser::ExternalStmt &);
864   bool Pre(const parser::IntentStmt &);
865   bool Pre(const parser::IntrinsicStmt &);
866   bool Pre(const parser::OptionalStmt &);
867   bool Pre(const parser::ProtectedStmt &);
868   bool Pre(const parser::ValueStmt &);
869   bool Pre(const parser::VolatileStmt &);
870   bool Pre(const parser::AllocatableStmt &) {
871     objectDeclAttr_ = Attr::ALLOCATABLE;
872     return true;
873   }
874   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
875   bool Pre(const parser::TargetStmt &) {
876     objectDeclAttr_ = Attr::TARGET;
877     return true;
878   }
879   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
880   void Post(const parser::DimensionStmt::Declaration &);
881   void Post(const parser::CodimensionDecl &);
882   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
883   void Post(const parser::TypeDeclarationStmt &);
884   void Post(const parser::IntegerTypeSpec &);
885   void Post(const parser::IntrinsicTypeSpec::Real &);
886   void Post(const parser::IntrinsicTypeSpec::Complex &);
887   void Post(const parser::IntrinsicTypeSpec::Logical &);
888   void Post(const parser::IntrinsicTypeSpec::Character &);
889   void Post(const parser::CharSelector::LengthAndKind &);
890   void Post(const parser::CharLength &);
891   void Post(const parser::LengthSelector &);
892   bool Pre(const parser::KindParam &);
893   bool Pre(const parser::DeclarationTypeSpec::Type &);
894   void Post(const parser::DeclarationTypeSpec::Type &);
895   bool Pre(const parser::DeclarationTypeSpec::Class &);
896   void Post(const parser::DeclarationTypeSpec::Class &);
897   void Post(const parser::DeclarationTypeSpec::Record &);
898   void Post(const parser::DerivedTypeSpec &);
899   bool Pre(const parser::DerivedTypeDef &);
900   bool Pre(const parser::DerivedTypeStmt &);
901   void Post(const parser::DerivedTypeStmt &);
902   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
903   void Post(const parser::TypeParamDefStmt &);
904   bool Pre(const parser::TypeAttrSpec::Extends &);
905   bool Pre(const parser::PrivateStmt &);
906   bool Pre(const parser::SequenceStmt &);
907   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
908   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
909   void Post(const parser::ComponentDecl &);
910   void Post(const parser::FillDecl &);
911   bool Pre(const parser::ProcedureDeclarationStmt &);
912   void Post(const parser::ProcedureDeclarationStmt &);
913   bool Pre(const parser::DataComponentDefStmt &); // returns false
914   bool Pre(const parser::ProcComponentDefStmt &);
915   void Post(const parser::ProcComponentDefStmt &);
916   bool Pre(const parser::ProcPointerInit &);
917   void Post(const parser::ProcInterface &);
918   void Post(const parser::ProcDecl &);
919   bool Pre(const parser::TypeBoundProcedurePart &);
920   void Post(const parser::TypeBoundProcedurePart &);
921   void Post(const parser::ContainsStmt &);
922   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
923   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
924   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
925   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
926   void Post(const parser::FinalProcedureStmt &);
927   bool Pre(const parser::TypeBoundGenericStmt &);
928   bool Pre(const parser::StructureDef &); // returns false
929   bool Pre(const parser::Union::UnionStmt &);
930   bool Pre(const parser::StructureField &);
931   void Post(const parser::StructureField &);
932   bool Pre(const parser::AllocateStmt &);
933   void Post(const parser::AllocateStmt &);
934   bool Pre(const parser::StructureConstructor &);
935   bool Pre(const parser::NamelistStmt::Group &);
936   bool Pre(const parser::IoControlSpec &);
937   bool Pre(const parser::CommonStmt::Block &);
938   bool Pre(const parser::CommonBlockObject &);
939   void Post(const parser::CommonBlockObject &);
940   bool Pre(const parser::EquivalenceStmt &);
941   bool Pre(const parser::SaveStmt &);
942   bool Pre(const parser::BasedPointerStmt &);
943 
944   void PointerInitialization(
945       const parser::Name &, const parser::InitialDataTarget &);
946   void PointerInitialization(
947       const parser::Name &, const parser::ProcPointerInit &);
948   void NonPointerInitialization(
949       const parser::Name &, const parser::ConstantExpr &);
950   void CheckExplicitInterface(const parser::Name &);
951   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
952 
953   const parser::Name *ResolveDesignator(const parser::Designator &);
954 
955 protected:
956   bool BeginDecl();
957   void EndDecl();
958   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
959   // Make sure that there's an entity in an enclosing scope called Name
960   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
961   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
962   // it comes from the entity in the containing scope, or implicit rules.
963   // Return pointer to the new symbol, or nullptr on error.
964   Symbol *DeclareLocalEntity(const parser::Name &);
965   // Declare a statement entity (i.e., an implied DO loop index for
966   // a DATA statement or an array constructor).  If there isn't an explict
967   // type specified, implicit rules apply. Return pointer to the new symbol,
968   // or nullptr on error.
969   Symbol *DeclareStatementEntity(const parser::DoVariable &,
970       const std::optional<parser::IntegerTypeSpec> &);
971   Symbol &MakeCommonBlockSymbol(const parser::Name &);
972   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
973   bool CheckUseError(const parser::Name &);
974   void CheckAccessibility(const SourceName &, bool, Symbol &);
975   void CheckCommonBlocks();
976   void CheckSaveStmts();
977   void CheckEquivalenceSets();
978   bool CheckNotInBlock(const char *);
979   bool NameIsKnownOrIntrinsic(const parser::Name &);
980   void FinishNamelists();
981 
982   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
983   // or nullptr in case of error.
984   const parser::Name *ResolveStructureComponent(
985       const parser::StructureComponent &);
986   const parser::Name *ResolveDataRef(const parser::DataRef &);
987   const parser::Name *ResolveName(const parser::Name &);
988   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
989   Symbol *NoteInterfaceName(const parser::Name &);
990   bool IsUplevelReference(const Symbol &);
991 
992   std::optional<SourceName> BeginCheckOnIndexUseInOwnBounds(
993       const parser::DoVariable &name) {
994     std::optional<SourceName> result{checkIndexUseInOwnBounds_};
995     checkIndexUseInOwnBounds_ = name.thing.thing.source;
996     return result;
997   }
998   void EndCheckOnIndexUseInOwnBounds(const std::optional<SourceName> &restore) {
999     checkIndexUseInOwnBounds_ = restore;
1000   }
1001 
1002 private:
1003   // The attribute corresponding to the statement containing an ObjectDecl
1004   std::optional<Attr> objectDeclAttr_;
1005   // Info about current character type while walking DeclTypeSpec.
1006   // Also captures any "*length" specifier on an individual declaration.
1007   struct {
1008     std::optional<ParamValue> length;
1009     std::optional<KindExpr> kind;
1010   } charInfo_;
1011   // Info about current derived type or STRUCTURE while walking
1012   // DerivedTypeDef / StructureDef
1013   struct {
1014     const parser::Name *extends{nullptr}; // EXTENDS(name)
1015     bool privateComps{false}; // components are private by default
1016     bool privateBindings{false}; // bindings are private by default
1017     bool sawContains{false}; // currently processing bindings
1018     bool sequence{false}; // is a sequence type
1019     const Symbol *type{nullptr}; // derived type being defined
1020     bool isStructure{false}; // is a DEC STRUCTURE
1021   } derivedTypeInfo_;
1022   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
1023   // the interface name, if any.
1024   const parser::Name *interfaceName_{nullptr};
1025   // Map type-bound generic to binding names of its specific bindings
1026   std::multimap<Symbol *, const parser::Name *> genericBindings_;
1027   // Info about current ENUM
1028   struct EnumeratorState {
1029     // Enum value must hold inside a C_INT (7.6.2).
1030     std::optional<int> value{0};
1031   } enumerationState_;
1032   // Set for OldParameterStmt processing
1033   bool inOldStyleParameterStmt_{false};
1034   // Set when walking DATA & array constructor implied DO loop bounds
1035   // to warn about use of the implied DO intex therein.
1036   std::optional<SourceName> checkIndexUseInOwnBounds_;
1037 
1038   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
1039   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
1040   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
1041   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
1042   void SetType(const parser::Name &, const DeclTypeSpec &);
1043   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
1044   std::optional<DerivedTypeSpec> ResolveExtendsType(
1045       const parser::Name &, const parser::Name *);
1046   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
1047   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
1048   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
1049   ParamValue GetParamValue(
1050       const parser::TypeParamValue &, common::TypeParamAttr attr);
1051   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
1052   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
1053   Attrs HandleSaveName(const SourceName &, Attrs);
1054   void AddSaveName(std::set<SourceName> &, const SourceName &);
1055   void SetSaveAttr(Symbol &);
1056   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
1057   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
1058   void Initialization(const parser::Name &, const parser::Initialization &,
1059       bool inComponentDecl);
1060   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
1061   bool CheckForHostAssociatedImplicit(const parser::Name &);
1062 
1063   // Declare an object or procedure entity.
1064   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
1065   template <typename T>
1066   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
1067     Symbol &symbol{MakeSymbol(name, attrs)};
1068     if (context().HasError(symbol) || symbol.has<T>()) {
1069       return symbol; // OK or error already reported
1070     } else if (symbol.has<UnknownDetails>()) {
1071       symbol.set_details(T{});
1072       return symbol;
1073     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
1074       symbol.set_details(T{std::move(*details)});
1075       return symbol;
1076     } else if (std::is_same_v<EntityDetails, T> &&
1077         (symbol.has<ObjectEntityDetails>() ||
1078             symbol.has<ProcEntityDetails>())) {
1079       return symbol; // OK
1080     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
1081       Say(name.source,
1082           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
1083           name.source, GetUsedModule(*details).name());
1084     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
1085       if (details->kind() == SubprogramKind::Module) {
1086         Say2(name,
1087             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
1088             symbol, "Module procedure definition"_en_US);
1089       } else if (details->kind() == SubprogramKind::Internal) {
1090         Say2(name,
1091             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
1092             symbol, "Internal procedure definition"_en_US);
1093       } else {
1094         DIE("unexpected kind");
1095       }
1096     } else if (std::is_same_v<ObjectEntityDetails, T> &&
1097         symbol.has<ProcEntityDetails>()) {
1098       SayWithDecl(
1099           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
1100     } else if (std::is_same_v<ProcEntityDetails, T> &&
1101         symbol.has<ObjectEntityDetails>()) {
1102       if (InCommonBlock(symbol)) {
1103         SayWithDecl(name, symbol,
1104             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1105       } else {
1106         SayWithDecl(
1107             name, symbol, "'%s' is already declared as an object"_err_en_US);
1108       }
1109     } else if (!CheckPossibleBadForwardRef(symbol)) {
1110       SayAlreadyDeclared(name, symbol);
1111     }
1112     context().SetError(symbol);
1113     return symbol;
1114   }
1115   bool HasCycle(const Symbol &, const ProcInterface &);
1116 };
1117 
1118 // Resolve construct entities and statement entities.
1119 // Check that construct names don't conflict with other names.
1120 class ConstructVisitor : public virtual DeclarationVisitor {
1121 public:
1122   bool Pre(const parser::ConcurrentHeader &);
1123   bool Pre(const parser::LocalitySpec::Local &);
1124   bool Pre(const parser::LocalitySpec::LocalInit &);
1125   bool Pre(const parser::LocalitySpec::Shared &);
1126   bool Pre(const parser::AcSpec &);
1127   bool Pre(const parser::AcImpliedDo &);
1128   bool Pre(const parser::DataImpliedDo &);
1129   bool Pre(const parser::DataIDoObject &);
1130   bool Pre(const parser::DataStmtObject &);
1131   bool Pre(const parser::DataStmtValue &);
1132   bool Pre(const parser::DoConstruct &);
1133   void Post(const parser::DoConstruct &);
1134   bool Pre(const parser::ForallConstruct &);
1135   void Post(const parser::ForallConstruct &);
1136   bool Pre(const parser::ForallStmt &);
1137   void Post(const parser::ForallStmt &);
1138   bool Pre(const parser::BlockStmt &);
1139   bool Pre(const parser::EndBlockStmt &);
1140   void Post(const parser::Selector &);
1141   void Post(const parser::AssociateStmt &);
1142   void Post(const parser::EndAssociateStmt &);
1143   bool Pre(const parser::Association &);
1144   void Post(const parser::SelectTypeStmt &);
1145   void Post(const parser::SelectRankStmt &);
1146   bool Pre(const parser::SelectTypeConstruct &);
1147   void Post(const parser::SelectTypeConstruct &);
1148   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1149   void Post(const parser::SelectTypeConstruct::TypeCase &);
1150   // Creates Block scopes with neither symbol name nor symbol details.
1151   bool Pre(const parser::SelectRankConstruct::RankCase &);
1152   void Post(const parser::SelectRankConstruct::RankCase &);
1153   void Post(const parser::TypeGuardStmt::Guard &);
1154   void Post(const parser::SelectRankCaseStmt::Rank &);
1155   bool Pre(const parser::ChangeTeamStmt &);
1156   void Post(const parser::EndChangeTeamStmt &);
1157   void Post(const parser::CoarrayAssociation &);
1158 
1159   // Definitions of construct names
1160   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1161   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1162   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1163   bool Pre(const parser::LabelDoStmt &) {
1164     return false; // error recovery
1165   }
1166   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1167   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1168   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1169   bool Pre(const parser::SelectRankConstruct &);
1170   void Post(const parser::SelectRankConstruct &);
1171   bool Pre(const parser::SelectRankStmt &x) {
1172     return CheckDef(std::get<0>(x.t));
1173   }
1174   bool Pre(const parser::SelectTypeStmt &x) {
1175     return CheckDef(std::get<0>(x.t));
1176   }
1177 
1178   // References to construct names
1179   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1180   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1181   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1182   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1183   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1184   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1185   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1186   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1187   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1188   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1189   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1190   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1191   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1192   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1193   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1194 
1195 private:
1196   // R1105 selector -> expr | variable
1197   // expr is set in either case unless there were errors
1198   struct Selector {
1199     Selector() {}
1200     Selector(const SourceName &source, MaybeExpr &&expr)
1201         : source{source}, expr{std::move(expr)} {}
1202     operator bool() const { return expr.has_value(); }
1203     parser::CharBlock source;
1204     MaybeExpr expr;
1205   };
1206   // association -> [associate-name =>] selector
1207   struct Association {
1208     const parser::Name *name{nullptr};
1209     Selector selector;
1210   };
1211   std::vector<Association> associationStack_;
1212   Association *currentAssociation_{nullptr};
1213 
1214   template <typename T> bool CheckDef(const T &t) {
1215     return CheckDef(std::get<std::optional<parser::Name>>(t));
1216   }
1217   template <typename T> void CheckRef(const T &t) {
1218     CheckRef(std::get<std::optional<parser::Name>>(t));
1219   }
1220   bool CheckDef(const std::optional<parser::Name> &);
1221   void CheckRef(const std::optional<parser::Name> &);
1222   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1223   const DeclTypeSpec &ToDeclTypeSpec(
1224       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1225   Symbol *MakeAssocEntity();
1226   void SetTypeFromAssociation(Symbol &);
1227   void SetAttrsFromAssociation(Symbol &);
1228   Selector ResolveSelector(const parser::Selector &);
1229   void ResolveIndexName(const parser::ConcurrentControl &control);
1230   void SetCurrentAssociation(std::size_t n);
1231   Association &GetCurrentAssociation();
1232   void PushAssociation();
1233   void PopAssociation(std::size_t count = 1);
1234 };
1235 
1236 // Create scopes for OpenACC constructs
1237 class AccVisitor : public virtual DeclarationVisitor {
1238 public:
1239   void AddAccSourceRange(const parser::CharBlock &);
1240 
1241   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1242 
1243   bool Pre(const parser::OpenACCBlockConstruct &);
1244   void Post(const parser::OpenACCBlockConstruct &);
1245   bool Pre(const parser::AccBeginBlockDirective &x) {
1246     AddAccSourceRange(x.source);
1247     return true;
1248   }
1249   void Post(const parser::AccBeginBlockDirective &) {
1250     messageHandler().set_currStmtSource(std::nullopt);
1251   }
1252   bool Pre(const parser::AccEndBlockDirective &x) {
1253     AddAccSourceRange(x.source);
1254     return true;
1255   }
1256   void Post(const parser::AccEndBlockDirective &) {
1257     messageHandler().set_currStmtSource(std::nullopt);
1258   }
1259   bool Pre(const parser::AccBeginLoopDirective &x) {
1260     AddAccSourceRange(x.source);
1261     return true;
1262   }
1263   void Post(const parser::AccBeginLoopDirective &x) {
1264     messageHandler().set_currStmtSource(std::nullopt);
1265   }
1266 };
1267 
1268 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1269   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1270   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1271   switch (beginDir.v) {
1272   case llvm::acc::Directive::ACCD_data:
1273   case llvm::acc::Directive::ACCD_host_data:
1274   case llvm::acc::Directive::ACCD_kernels:
1275   case llvm::acc::Directive::ACCD_parallel:
1276   case llvm::acc::Directive::ACCD_serial:
1277     return true;
1278   default:
1279     return false;
1280   }
1281 }
1282 
1283 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1284   messageHandler().set_currStmtSource(source);
1285   currScope().AddSourceRange(source);
1286 }
1287 
1288 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1289   if (NeedsScope(x)) {
1290     PushScope(Scope::Kind::Block, nullptr);
1291   }
1292   return true;
1293 }
1294 
1295 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1296   if (NeedsScope(x)) {
1297     PopScope();
1298   }
1299 }
1300 
1301 // Create scopes for OpenMP constructs
1302 class OmpVisitor : public virtual DeclarationVisitor {
1303 public:
1304   void AddOmpSourceRange(const parser::CharBlock &);
1305 
1306   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1307 
1308   bool Pre(const parser::OpenMPBlockConstruct &);
1309   void Post(const parser::OpenMPBlockConstruct &);
1310   bool Pre(const parser::OmpBeginBlockDirective &x) {
1311     AddOmpSourceRange(x.source);
1312     return true;
1313   }
1314   void Post(const parser::OmpBeginBlockDirective &) {
1315     messageHandler().set_currStmtSource(std::nullopt);
1316   }
1317   bool Pre(const parser::OmpEndBlockDirective &x) {
1318     AddOmpSourceRange(x.source);
1319     return true;
1320   }
1321   void Post(const parser::OmpEndBlockDirective &) {
1322     messageHandler().set_currStmtSource(std::nullopt);
1323   }
1324 
1325   bool Pre(const parser::OpenMPLoopConstruct &) {
1326     PushScope(Scope::Kind::Block, nullptr);
1327     return true;
1328   }
1329   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1330   bool Pre(const parser::OmpBeginLoopDirective &x) {
1331     AddOmpSourceRange(x.source);
1332     return true;
1333   }
1334   void Post(const parser::OmpBeginLoopDirective &) {
1335     messageHandler().set_currStmtSource(std::nullopt);
1336   }
1337   bool Pre(const parser::OmpEndLoopDirective &x) {
1338     AddOmpSourceRange(x.source);
1339     return true;
1340   }
1341   void Post(const parser::OmpEndLoopDirective &) {
1342     messageHandler().set_currStmtSource(std::nullopt);
1343   }
1344 
1345   bool Pre(const parser::OpenMPSectionsConstruct &) {
1346     PushScope(Scope::Kind::Block, nullptr);
1347     return true;
1348   }
1349   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1350   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1351     AddOmpSourceRange(x.source);
1352     return true;
1353   }
1354   void Post(const parser::OmpBeginSectionsDirective &) {
1355     messageHandler().set_currStmtSource(std::nullopt);
1356   }
1357   bool Pre(const parser::OmpEndSectionsDirective &x) {
1358     AddOmpSourceRange(x.source);
1359     return true;
1360   }
1361   void Post(const parser::OmpEndSectionsDirective &) {
1362     messageHandler().set_currStmtSource(std::nullopt);
1363   }
1364 };
1365 
1366 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1367   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1368   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1369   switch (beginDir.v) {
1370   case llvm::omp::Directive::OMPD_target_data:
1371   case llvm::omp::Directive::OMPD_master:
1372   case llvm::omp::Directive::OMPD_ordered:
1373   case llvm::omp::Directive::OMPD_taskgroup:
1374     return false;
1375   default:
1376     return true;
1377   }
1378 }
1379 
1380 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1381   messageHandler().set_currStmtSource(source);
1382   currScope().AddSourceRange(source);
1383 }
1384 
1385 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1386   if (NeedsScope(x)) {
1387     PushScope(Scope::Kind::Block, nullptr);
1388   }
1389   return true;
1390 }
1391 
1392 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1393   if (NeedsScope(x)) {
1394     PopScope();
1395   }
1396 }
1397 
1398 // Walk the parse tree and resolve names to symbols.
1399 class ResolveNamesVisitor : public virtual ScopeHandler,
1400                             public ModuleVisitor,
1401                             public SubprogramVisitor,
1402                             public ConstructVisitor,
1403                             public OmpVisitor,
1404                             public AccVisitor {
1405 public:
1406   using AccVisitor::Post;
1407   using AccVisitor::Pre;
1408   using ArraySpecVisitor::Post;
1409   using ConstructVisitor::Post;
1410   using ConstructVisitor::Pre;
1411   using DeclarationVisitor::Post;
1412   using DeclarationVisitor::Pre;
1413   using ImplicitRulesVisitor::Post;
1414   using ImplicitRulesVisitor::Pre;
1415   using InterfaceVisitor::Post;
1416   using InterfaceVisitor::Pre;
1417   using ModuleVisitor::Post;
1418   using ModuleVisitor::Pre;
1419   using OmpVisitor::Post;
1420   using OmpVisitor::Pre;
1421   using ScopeHandler::Post;
1422   using ScopeHandler::Pre;
1423   using SubprogramVisitor::Post;
1424   using SubprogramVisitor::Pre;
1425 
1426   ResolveNamesVisitor(
1427       SemanticsContext &context, ImplicitRulesMap &rules, Scope &top)
1428       : BaseVisitor{context, *this, rules}, topScope_{top} {
1429     PushScope(top);
1430   }
1431 
1432   Scope &topScope() const { return topScope_; }
1433 
1434   // Default action for a parse tree node is to visit children.
1435   template <typename T> bool Pre(const T &) { return true; }
1436   template <typename T> void Post(const T &) {}
1437 
1438   bool Pre(const parser::SpecificationPart &);
1439   void Post(const parser::Program &);
1440   bool Pre(const parser::ImplicitStmt &);
1441   void Post(const parser::PointerObject &);
1442   void Post(const parser::AllocateObject &);
1443   bool Pre(const parser::PointerAssignmentStmt &);
1444   void Post(const parser::Designator &);
1445   template <typename A, typename B>
1446   void Post(const parser::LoopBounds<A, B> &x) {
1447     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1448   }
1449   void Post(const parser::ProcComponentRef &);
1450   bool Pre(const parser::FunctionReference &);
1451   bool Pre(const parser::CallStmt &);
1452   bool Pre(const parser::ImportStmt &);
1453   void Post(const parser::TypeGuardStmt &);
1454   bool Pre(const parser::StmtFunctionStmt &);
1455   bool Pre(const parser::DefinedOpName &);
1456   bool Pre(const parser::ProgramUnit &);
1457   void Post(const parser::AssignStmt &);
1458   void Post(const parser::AssignedGotoStmt &);
1459 
1460   // These nodes should never be reached: they are handled in ProgramUnit
1461   bool Pre(const parser::MainProgram &) {
1462     llvm_unreachable("This node is handled in ProgramUnit");
1463   }
1464   bool Pre(const parser::FunctionSubprogram &) {
1465     llvm_unreachable("This node is handled in ProgramUnit");
1466   }
1467   bool Pre(const parser::SubroutineSubprogram &) {
1468     llvm_unreachable("This node is handled in ProgramUnit");
1469   }
1470   bool Pre(const parser::SeparateModuleSubprogram &) {
1471     llvm_unreachable("This node is handled in ProgramUnit");
1472   }
1473   bool Pre(const parser::Module &) {
1474     llvm_unreachable("This node is handled in ProgramUnit");
1475   }
1476   bool Pre(const parser::Submodule &) {
1477     llvm_unreachable("This node is handled in ProgramUnit");
1478   }
1479   bool Pre(const parser::BlockData &) {
1480     llvm_unreachable("This node is handled in ProgramUnit");
1481   }
1482 
1483   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1484 
1485   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1486 
1487 private:
1488   // Kind of procedure we are expecting to see in a ProcedureDesignator
1489   std::optional<Symbol::Flag> expectedProcFlag_;
1490   std::optional<SourceName> prevImportStmt_;
1491   Scope &topScope_;
1492 
1493   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1494   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1495   void CreateGeneric(const parser::GenericSpec &);
1496   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1497   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1498   void CheckImports();
1499   void CheckImport(const SourceName &, const SourceName &);
1500   void HandleCall(Symbol::Flag, const parser::Call &);
1501   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1502   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1503   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1504   void ResolveSpecificationParts(ProgramTree &);
1505   void AddSubpNames(ProgramTree &);
1506   bool BeginScopeForNode(const ProgramTree &);
1507   void EndScopeForNode(const ProgramTree &);
1508   void FinishSpecificationParts(const ProgramTree &);
1509   void FinishDerivedTypeInstantiation(Scope &);
1510   void ResolveExecutionParts(const ProgramTree &);
1511 };
1512 
1513 // ImplicitRules implementation
1514 
1515 bool ImplicitRules::isImplicitNoneType() const {
1516   if (isImplicitNoneType_) {
1517     return true;
1518   } else if (map_.empty() && inheritFromParent_) {
1519     return parent_->isImplicitNoneType();
1520   } else {
1521     return false; // default if not specified
1522   }
1523 }
1524 
1525 bool ImplicitRules::isImplicitNoneExternal() const {
1526   if (isImplicitNoneExternal_) {
1527     return true;
1528   } else if (inheritFromParent_) {
1529     return parent_->isImplicitNoneExternal();
1530   } else {
1531     return false; // default if not specified
1532   }
1533 }
1534 
1535 const DeclTypeSpec *ImplicitRules::GetType(
1536     SourceName name, bool respectImplicitNoneType) const {
1537   char ch{name.begin()[0]};
1538   if (isImplicitNoneType_ && respectImplicitNoneType) {
1539     return nullptr;
1540   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1541     return &*it->second;
1542   } else if (inheritFromParent_) {
1543     return parent_->GetType(name, respectImplicitNoneType);
1544   } else if (ch >= 'i' && ch <= 'n') {
1545     return &context_.MakeNumericType(TypeCategory::Integer);
1546   } else if (ch >= 'a' && ch <= 'z') {
1547     return &context_.MakeNumericType(TypeCategory::Real);
1548   } else {
1549     return nullptr;
1550   }
1551 }
1552 
1553 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1554     parser::Location fromLetter, parser::Location toLetter) {
1555   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1556     auto res{map_.emplace(ch, type)};
1557     if (!res.second) {
1558       context_.Say(parser::CharBlock{fromLetter},
1559           "More than one implicit type specified for '%c'"_err_en_US, ch);
1560     }
1561     if (ch == *toLetter) {
1562       break;
1563     }
1564   }
1565 }
1566 
1567 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1568 // Return '\0' for the char after 'z'.
1569 char ImplicitRules::Incr(char ch) {
1570   switch (ch) {
1571   case 'i':
1572     return 'j';
1573   case 'r':
1574     return 's';
1575   case 'z':
1576     return '\0';
1577   default:
1578     return ch + 1;
1579   }
1580 }
1581 
1582 llvm::raw_ostream &operator<<(
1583     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1584   o << "ImplicitRules:\n";
1585   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1586     ShowImplicitRule(o, implicitRules, ch);
1587   }
1588   ShowImplicitRule(o, implicitRules, '_');
1589   ShowImplicitRule(o, implicitRules, '$');
1590   ShowImplicitRule(o, implicitRules, '@');
1591   return o;
1592 }
1593 void ShowImplicitRule(
1594     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1595   auto it{implicitRules.map_.find(ch)};
1596   if (it != implicitRules.map_.end()) {
1597     o << "  " << ch << ": " << *it->second << '\n';
1598   }
1599 }
1600 
1601 template <typename T> void BaseVisitor::Walk(const T &x) {
1602   parser::Walk(x, *this_);
1603 }
1604 
1605 void BaseVisitor::MakePlaceholder(
1606     const parser::Name &name, MiscDetails::Kind kind) {
1607   if (!name.symbol) {
1608     name.symbol = &context_->globalScope().MakeSymbol(
1609         name.source, Attrs{}, MiscDetails{kind});
1610   }
1611 }
1612 
1613 // AttrsVisitor implementation
1614 
1615 bool AttrsVisitor::BeginAttrs() {
1616   CHECK(!attrs_);
1617   attrs_ = std::make_optional<Attrs>();
1618   return true;
1619 }
1620 Attrs AttrsVisitor::GetAttrs() {
1621   CHECK(attrs_);
1622   return *attrs_;
1623 }
1624 Attrs AttrsVisitor::EndAttrs() {
1625   Attrs result{GetAttrs()};
1626   attrs_.reset();
1627   passName_ = std::nullopt;
1628   bindName_.reset();
1629   return result;
1630 }
1631 
1632 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1633   if (!passName_) {
1634     return false;
1635   }
1636   std::visit(common::visitors{
1637                  [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1638                  [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1639                  [](auto &) { common::die("unexpected pass name"); },
1640              },
1641       symbol.details());
1642   return true;
1643 }
1644 
1645 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1646   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1647     return;
1648   }
1649   std::optional<std::string> label{
1650       evaluate::GetScalarConstantValue<evaluate::Ascii>(bindName_)};
1651   // 18.9.2(2): discard leading and trailing blanks, ignore if all blank
1652   if (label) {
1653     auto first{label->find_first_not_of(" ")};
1654     if (first == std::string::npos) {
1655       // Empty NAME= means no binding at all (18.10.2p2)
1656       Say(currStmtSource().value(), "Blank binding label ignored"_warn_en_US);
1657       return;
1658     }
1659     auto last{label->find_last_not_of(" ")};
1660     label = label->substr(first, last - first + 1);
1661   } else {
1662     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1663   }
1664   symbol.SetBindName(std::move(*label));
1665 }
1666 
1667 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1668   CHECK(attrs_);
1669   if (CheckAndSet(Attr::BIND_C)) {
1670     if (x.v) {
1671       bindName_ = EvaluateExpr(*x.v);
1672     }
1673   }
1674 }
1675 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1676   CHECK(attrs_);
1677   CheckAndSet(IntentSpecToAttr(x));
1678   return false;
1679 }
1680 bool AttrsVisitor::Pre(const parser::Pass &x) {
1681   if (CheckAndSet(Attr::PASS)) {
1682     if (x.v) {
1683       passName_ = x.v->source;
1684       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1685     }
1686   }
1687   return false;
1688 }
1689 
1690 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1691 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1692   if (attrs_->test(attrName)) {
1693     Say(currStmtSource().value(),
1694         "Attribute '%s' cannot be used more than once"_warn_en_US,
1695         AttrToString(attrName));
1696     return true;
1697   }
1698   return false;
1699 }
1700 
1701 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1702 // name attributes that cannot be used on the same declaration
1703 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1704   if ((attrName == attr1 && attrs_->test(attr2)) ||
1705       (attrName == attr2 && attrs_->test(attr1))) {
1706     Say(currStmtSource().value(),
1707         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1708         AttrToString(attr1), AttrToString(attr2));
1709     return true;
1710   }
1711   return false;
1712 }
1713 // C759, C1543
1714 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1715   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1716       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1717       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1718       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1719       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1720       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1721       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1722 }
1723 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1724   CHECK(attrs_);
1725   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1726     return false;
1727   }
1728   attrs_->set(attrName);
1729   return true;
1730 }
1731 
1732 // DeclTypeSpecVisitor implementation
1733 
1734 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1735   return state_.declTypeSpec;
1736 }
1737 
1738 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1739   CHECK(!state_.expectDeclTypeSpec);
1740   CHECK(!state_.declTypeSpec);
1741   state_.expectDeclTypeSpec = true;
1742 }
1743 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1744   CHECK(state_.expectDeclTypeSpec);
1745   state_ = {};
1746 }
1747 
1748 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1749     DeclTypeSpec::Category category) {
1750   CHECK(state_.expectDeclTypeSpec);
1751   state_.derived.category = category;
1752 }
1753 
1754 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1755   BeginDeclTypeSpec();
1756   return true;
1757 }
1758 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1759   EndDeclTypeSpec();
1760 }
1761 
1762 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1763   // Record the resolved DeclTypeSpec in the parse tree for use by
1764   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1765   // The grammar ensures that it's an intrinsic or derived type spec,
1766   // not TYPE(*) or CLASS(*) or CLASS(T).
1767   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1768     switch (spec->category()) {
1769     case DeclTypeSpec::Numeric:
1770     case DeclTypeSpec::Logical:
1771     case DeclTypeSpec::Character:
1772       typeSpec.declTypeSpec = spec;
1773       break;
1774     case DeclTypeSpec::TypeDerived:
1775       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1776         CheckForAbstractType(derived->typeSymbol()); // C703
1777         typeSpec.declTypeSpec = spec;
1778       }
1779       break;
1780     default:
1781       CRASH_NO_CASE;
1782     }
1783   }
1784 }
1785 
1786 void DeclTypeSpecVisitor::Post(
1787     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1788   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1789 }
1790 void DeclTypeSpecVisitor::Post(
1791     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1792   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1793 }
1794 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1795   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1796 }
1797 
1798 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1799   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1800     Say("ABSTRACT derived type may not be used here"_err_en_US);
1801   }
1802 }
1803 
1804 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1805   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1806 }
1807 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1808   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1809 }
1810 
1811 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1812 // and save it in state_.declTypeSpec.
1813 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1814   CHECK(state_.expectDeclTypeSpec);
1815   CHECK(!state_.declTypeSpec);
1816   state_.declTypeSpec = &declTypeSpec;
1817 }
1818 
1819 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1820     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1821   return AnalyzeKindSelector(context(), category, kind);
1822 }
1823 
1824 // MessageHandler implementation
1825 
1826 Message &MessageHandler::Say(MessageFixedText &&msg) {
1827   return context_->Say(currStmtSource().value(), std::move(msg));
1828 }
1829 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1830   return context_->Say(currStmtSource().value(), std::move(msg));
1831 }
1832 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1833   return Say(name, std::move(msg), name);
1834 }
1835 
1836 // ImplicitRulesVisitor implementation
1837 
1838 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1839   prevParameterStmt_ = currStmtSource();
1840 }
1841 
1842 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1843   bool result{
1844       std::visit(common::visitors{
1845                      [&](const std::list<ImplicitNoneNameSpec> &y) {
1846                        return HandleImplicitNone(y);
1847                      },
1848                      [&](const std::list<parser::ImplicitSpec> &) {
1849                        if (prevImplicitNoneType_) {
1850                          Say("IMPLICIT statement after IMPLICIT NONE or "
1851                              "IMPLICIT NONE(TYPE) statement"_err_en_US);
1852                          return false;
1853                        }
1854                        implicitRules_->set_isImplicitNoneType(false);
1855                        return true;
1856                      },
1857                  },
1858           x.u)};
1859   prevImplicit_ = currStmtSource();
1860   return result;
1861 }
1862 
1863 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1864   auto loLoc{std::get<parser::Location>(x.t)};
1865   auto hiLoc{loLoc};
1866   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1867     hiLoc = *hiLocOpt;
1868     if (*hiLoc < *loLoc) {
1869       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1870           std::string(hiLoc, 1), std::string(loLoc, 1));
1871       return false;
1872     }
1873   }
1874   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1875   return false;
1876 }
1877 
1878 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1879   BeginDeclTypeSpec();
1880   set_allowForwardReferenceToDerivedType(true);
1881   return true;
1882 }
1883 
1884 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1885   EndDeclTypeSpec();
1886 }
1887 
1888 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1889   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1890   prevImplicit_ = std::nullopt;
1891   prevImplicitNone_ = std::nullopt;
1892   prevImplicitNoneType_ = std::nullopt;
1893   prevParameterStmt_ = std::nullopt;
1894 }
1895 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1896   // find or create implicit rules for this scope
1897   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1898   SetScope(scope);
1899 }
1900 
1901 // TODO: for all of these errors, reference previous statement too
1902 bool ImplicitRulesVisitor::HandleImplicitNone(
1903     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1904   if (prevImplicitNone_) {
1905     Say("More than one IMPLICIT NONE statement"_err_en_US);
1906     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1907     return false;
1908   }
1909   if (prevParameterStmt_) {
1910     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1911     return false;
1912   }
1913   prevImplicitNone_ = currStmtSource();
1914   bool implicitNoneTypeNever{
1915       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1916   if (nameSpecs.empty()) {
1917     if (!implicitNoneTypeNever) {
1918       prevImplicitNoneType_ = currStmtSource();
1919       implicitRules_->set_isImplicitNoneType(true);
1920       if (prevImplicit_) {
1921         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1922         return false;
1923       }
1924     }
1925   } else {
1926     int sawType{0};
1927     int sawExternal{0};
1928     for (const auto noneSpec : nameSpecs) {
1929       switch (noneSpec) {
1930       case ImplicitNoneNameSpec::External:
1931         implicitRules_->set_isImplicitNoneExternal(true);
1932         ++sawExternal;
1933         break;
1934       case ImplicitNoneNameSpec::Type:
1935         if (!implicitNoneTypeNever) {
1936           prevImplicitNoneType_ = currStmtSource();
1937           implicitRules_->set_isImplicitNoneType(true);
1938           if (prevImplicit_) {
1939             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1940             return false;
1941           }
1942           ++sawType;
1943         }
1944         break;
1945       }
1946     }
1947     if (sawType > 1) {
1948       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1949       return false;
1950     }
1951     if (sawExternal > 1) {
1952       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1953       return false;
1954     }
1955   }
1956   return true;
1957 }
1958 
1959 // ArraySpecVisitor implementation
1960 
1961 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1962   CHECK(arraySpec_.empty());
1963   arraySpec_ = AnalyzeArraySpec(context(), x);
1964 }
1965 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1966   CHECK(arraySpec_.empty());
1967   arraySpec_ = AnalyzeArraySpec(context(), x);
1968 }
1969 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1970   CHECK(coarraySpec_.empty());
1971   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1972 }
1973 
1974 const ArraySpec &ArraySpecVisitor::arraySpec() {
1975   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
1976 }
1977 const ArraySpec &ArraySpecVisitor::coarraySpec() {
1978   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
1979 }
1980 void ArraySpecVisitor::BeginArraySpec() {
1981   CHECK(arraySpec_.empty());
1982   CHECK(coarraySpec_.empty());
1983   CHECK(attrArraySpec_.empty());
1984   CHECK(attrCoarraySpec_.empty());
1985 }
1986 void ArraySpecVisitor::EndArraySpec() {
1987   CHECK(arraySpec_.empty());
1988   CHECK(coarraySpec_.empty());
1989   attrArraySpec_.clear();
1990   attrCoarraySpec_.clear();
1991 }
1992 void ArraySpecVisitor::PostAttrSpec() {
1993   // Save dimension/codimension from attrs so we can process array/coarray-spec
1994   // on the entity-decl
1995   if (!arraySpec_.empty()) {
1996     if (attrArraySpec_.empty()) {
1997       attrArraySpec_ = arraySpec_;
1998       arraySpec_.clear();
1999     } else {
2000       Say(currStmtSource().value(),
2001           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
2002     }
2003   }
2004   if (!coarraySpec_.empty()) {
2005     if (attrCoarraySpec_.empty()) {
2006       attrCoarraySpec_ = coarraySpec_;
2007       coarraySpec_.clear();
2008     } else {
2009       Say(currStmtSource().value(),
2010           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
2011     }
2012   }
2013 }
2014 
2015 // FuncResultStack implementation
2016 
2017 FuncResultStack::~FuncResultStack() { CHECK(stack_.empty()); }
2018 
2019 void FuncResultStack::CompleteFunctionResultType() {
2020   // If the function has a type in the prefix, process it now.
2021   if (IsFunction(scopeHandler_.currScope())) {
2022     FuncInfo &info{DEREF(Top())};
2023     if (info.parsedType) {
2024       scopeHandler_.messageHandler().set_currStmtSource(info.source);
2025       if (const auto *type{
2026               scopeHandler_.ProcessTypeSpec(*info.parsedType, true)}) {
2027         if (!scopeHandler_.context().HasError(info.resultSymbol)) {
2028           info.resultSymbol->SetType(*type);
2029         }
2030       }
2031       info.parsedType = nullptr;
2032     }
2033   }
2034 }
2035 
2036 // Called from ConvertTo{Object/Proc}Entity to cope with any appearance
2037 // of the function result in a specification expression.
2038 void FuncResultStack::CompleteTypeIfFunctionResult(Symbol &symbol) {
2039   if (FuncInfo * info{Top()}) {
2040     if (info->resultSymbol == &symbol) {
2041       CompleteFunctionResultType();
2042     }
2043   }
2044 }
2045 
2046 // ScopeHandler implementation
2047 
2048 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
2049   SayAlreadyDeclared(name.source, prev);
2050 }
2051 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
2052   if (context().HasError(prev)) {
2053     // don't report another error about prev
2054   } else {
2055     if (const auto *details{prev.detailsIf<UseDetails>()}) {
2056       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
2057           .Attach(details->location(),
2058               "It is use-associated with '%s' in module '%s'"_en_US,
2059               details->symbol().name(), GetUsedModule(*details).name());
2060     } else {
2061       SayAlreadyDeclared(name, prev.name());
2062     }
2063     context().SetError(prev);
2064   }
2065 }
2066 void ScopeHandler::SayAlreadyDeclared(
2067     const SourceName &name1, const SourceName &name2) {
2068   if (name1.begin() < name2.begin()) {
2069     SayAlreadyDeclared(name2, name1);
2070   } else {
2071     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
2072         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
2073   }
2074 }
2075 
2076 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
2077     MessageFixedText &&msg1, Message &&msg2) {
2078   Say(name, std::move(msg1), symbol.name()).Attach(std::move(msg2));
2079   context().SetError(symbol, msg1.isFatal());
2080 }
2081 
2082 void ScopeHandler::SayWithDecl(
2083     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
2084   Say(name, std::move(msg), symbol.name())
2085       .Attach(Message{name.source,
2086           symbol.test(Symbol::Flag::Implicit)
2087               ? "Implicit declaration of '%s'"_en_US
2088               : "Declaration of '%s'"_en_US,
2089           name.source});
2090   context().SetError(symbol, msg.isFatal());
2091 }
2092 
2093 void ScopeHandler::SayLocalMustBeVariable(
2094     const parser::Name &name, Symbol &symbol) {
2095   SayWithDecl(name, symbol,
2096       "The name '%s' must be a variable to appear"
2097       " in a locality-spec"_err_en_US);
2098 }
2099 
2100 void ScopeHandler::SayDerivedType(
2101     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
2102   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
2103   Say(name, std::move(msg), name, typeSymbol.name())
2104       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
2105           typeSymbol.name());
2106 }
2107 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2108     const SourceName &name2, MessageFixedText &&msg2) {
2109   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2110 }
2111 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2112     Symbol &symbol, MessageFixedText &&msg2) {
2113   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2114   context().SetError(symbol, msg1.isFatal());
2115 }
2116 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2117     Symbol &symbol, MessageFixedText &&msg2) {
2118   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2119   context().SetError(symbol, msg1.isFatal());
2120 }
2121 
2122 // This is essentially GetProgramUnitContaining(), but it can return
2123 // a mutable Scope &, it ignores statement functions, and it fails
2124 // gracefully for error recovery (returning the original Scope).
2125 template <typename T> static T &GetInclusiveScope(T &scope) {
2126   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
2127     switch (s->kind()) {
2128     case Scope::Kind::Module:
2129     case Scope::Kind::MainProgram:
2130     case Scope::Kind::Subprogram:
2131     case Scope::Kind::BlockData:
2132       if (!s->IsStmtFunction()) {
2133         return *s;
2134       }
2135       break;
2136     default:;
2137     }
2138   }
2139   return scope;
2140 }
2141 
2142 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
2143 
2144 Scope *ScopeHandler::GetHostProcedure() {
2145   Scope &parent{InclusiveScope().parent()};
2146   switch (parent.kind()) {
2147   case Scope::Kind::Subprogram:
2148     return &parent;
2149   case Scope::Kind::MainProgram:
2150     return &parent;
2151   default:
2152     return nullptr;
2153   }
2154 }
2155 
2156 Scope &ScopeHandler::NonDerivedTypeScope() {
2157   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2158 }
2159 
2160 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2161   PushScope(currScope().MakeScope(kind, symbol));
2162 }
2163 void ScopeHandler::PushScope(Scope &scope) {
2164   currScope_ = &scope;
2165   auto kind{currScope_->kind()};
2166   if (kind != Scope::Kind::Block) {
2167     BeginScope(scope);
2168   }
2169   // The name of a module or submodule cannot be "used" in its scope,
2170   // as we read 19.3.1(2), so we allow the name to be used as a local
2171   // identifier in the module or submodule too.  Same with programs
2172   // (14.1(3)) and BLOCK DATA.
2173   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2174       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2175     if (auto *symbol{scope.symbol()}) {
2176       // Create a dummy symbol so we can't create another one with the same
2177       // name. It might already be there if we previously pushed the scope.
2178       if (!FindInScope(scope, symbol->name())) {
2179         auto &newSymbol{MakeSymbol(symbol->name())};
2180         if (kind == Scope::Kind::Subprogram) {
2181           // Allow for recursive references.  If this symbol is a function
2182           // without an explicit RESULT(), this new symbol will be discarded
2183           // and replaced with an object of the same name.
2184           newSymbol.set_details(HostAssocDetails{*symbol});
2185         } else {
2186           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2187         }
2188       }
2189     }
2190   }
2191 }
2192 void ScopeHandler::PopScope() {
2193   // Entities that are not yet classified as objects or procedures are now
2194   // assumed to be objects.
2195   // TODO: Statement functions
2196   for (auto &pair : currScope()) {
2197     ConvertToObjectEntity(*pair.second);
2198   }
2199   SetScope(currScope_->parent());
2200 }
2201 void ScopeHandler::SetScope(Scope &scope) {
2202   currScope_ = &scope;
2203   ImplicitRulesVisitor::SetScope(InclusiveScope());
2204 }
2205 
2206 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2207   return FindSymbol(currScope(), name);
2208 }
2209 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2210   if (scope.IsDerivedType()) {
2211     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2212       if (!symbol->has<ProcBindingDetails>() &&
2213           !symbol->test(Symbol::Flag::ParentComp)) {
2214         return Resolve(name, symbol);
2215       }
2216     }
2217     return FindSymbol(scope.parent(), name);
2218   } else {
2219     // In EQUIVALENCE statements only resolve names in the local scope, see
2220     // 19.5.1.4, paragraph 2, item (10)
2221     return Resolve(name,
2222         inEquivalenceStmt_ ? FindInScope(scope, name)
2223                            : scope.FindSymbol(name.source));
2224   }
2225 }
2226 
2227 Symbol &ScopeHandler::MakeSymbol(
2228     Scope &scope, const SourceName &name, Attrs attrs) {
2229   if (Symbol * symbol{FindInScope(scope, name)}) {
2230     symbol->attrs() |= attrs;
2231     return *symbol;
2232   } else {
2233     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2234     CHECK(pair.second); // name was not found, so must be able to add
2235     return *pair.first->second;
2236   }
2237 }
2238 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2239   return MakeSymbol(currScope(), name, attrs);
2240 }
2241 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2242   return Resolve(name, MakeSymbol(name.source, attrs));
2243 }
2244 Symbol &ScopeHandler::MakeHostAssocSymbol(
2245     const parser::Name &name, const Symbol &hostSymbol) {
2246   Symbol &symbol{*NonDerivedTypeScope()
2247                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2248                       .first->second};
2249   name.symbol = &symbol;
2250   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2251   symbol.flags() = hostSymbol.flags();
2252   return symbol;
2253 }
2254 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2255   CHECK(!FindInScope(name));
2256   return MakeSymbol(currScope(), name, symbol.attrs());
2257 }
2258 
2259 // Look for name only in scope, not in enclosing scopes.
2260 Symbol *ScopeHandler::FindInScope(
2261     const Scope &scope, const parser::Name &name) {
2262   return Resolve(name, FindInScope(scope, name.source));
2263 }
2264 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2265   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2266   for (const std::string &n : GetAllNames(context(), name)) {
2267     auto it{scope.find(SourceName{n})};
2268     if (it != scope.end()) {
2269       return &*it->second;
2270     }
2271   }
2272   return nullptr;
2273 }
2274 
2275 // Find a component or type parameter by name in a derived type or its parents.
2276 Symbol *ScopeHandler::FindInTypeOrParents(
2277     const Scope &scope, const parser::Name &name) {
2278   return Resolve(name, scope.FindComponent(name.source));
2279 }
2280 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2281   return FindInTypeOrParents(currScope(), name);
2282 }
2283 
2284 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2285   currScope().erase(name.source);
2286   name.symbol = nullptr;
2287 }
2288 
2289 static bool NeedsType(const Symbol &symbol) {
2290   return !symbol.GetType() &&
2291       std::visit(common::visitors{
2292                      [](const EntityDetails &) { return true; },
2293                      [](const ObjectEntityDetails &) { return true; },
2294                      [](const AssocEntityDetails &) { return true; },
2295                      [&](const ProcEntityDetails &p) {
2296                        return symbol.test(Symbol::Flag::Function) &&
2297                            !symbol.attrs().test(Attr::INTRINSIC) &&
2298                            !p.interface().type() && !p.interface().symbol();
2299                      },
2300                      [](const auto &) { return false; },
2301                  },
2302           symbol.details());
2303 }
2304 
2305 void ScopeHandler::ApplyImplicitRules(
2306     Symbol &symbol, bool allowForwardReference) {
2307   funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2308   if (context().HasError(symbol) || !NeedsType(symbol)) {
2309     return;
2310   }
2311   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2312     symbol.set(Symbol::Flag::Implicit);
2313     symbol.SetType(*type);
2314     return;
2315   }
2316   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2317     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2318     if (symbol.test(Symbol::Flag::Function)) {
2319       functionOrSubroutineFlag = Symbol::Flag::Function;
2320     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2321       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2322     }
2323     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2324       // type will be determined in expression semantics
2325       AcquireIntrinsicProcedureFlags(symbol);
2326       return;
2327     }
2328   }
2329   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2330     return;
2331   }
2332   if (!context().HasError(symbol)) {
2333     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2334     context().SetError(symbol);
2335   }
2336 }
2337 
2338 // Extension: Allow forward references to scalar integer dummy arguments
2339 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2340 // what would otherwise have been their implicit type is default INTEGER.
2341 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2342   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2343       symbol.Rank() != 0 ||
2344       !context().languageFeatures().IsEnabled(
2345           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2346     return false;
2347   }
2348   const DeclTypeSpec *type{
2349       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2350   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2351     return false;
2352   }
2353   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2354   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2355     return false;
2356   }
2357   if (!ConvertToObjectEntity(symbol)) {
2358     return false;
2359   }
2360   // TODO: check no INTENT(OUT)?
2361   if (context().languageFeatures().ShouldWarn(
2362           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2363     Say(symbol.name(),
2364         "Dummy argument '%s' was used without being explicitly typed"_warn_en_US,
2365         symbol.name());
2366   }
2367   symbol.set(Symbol::Flag::Implicit);
2368   symbol.SetType(*type);
2369   return true;
2370 }
2371 
2372 // Ensure that the symbol for an intrinsic procedure is marked with
2373 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2374 // appropriate.
2375 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2376   symbol.attrs().set(Attr::INTRINSIC);
2377   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2378   case evaluate::IntrinsicClass::elementalFunction:
2379   case evaluate::IntrinsicClass::elementalSubroutine:
2380     symbol.attrs().set(Attr::ELEMENTAL);
2381     symbol.attrs().set(Attr::PURE);
2382     break;
2383   case evaluate::IntrinsicClass::impureSubroutine:
2384     break;
2385   default:
2386     symbol.attrs().set(Attr::PURE);
2387   }
2388 }
2389 
2390 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2391     Symbol &symbol, bool respectImplicitNoneType) {
2392   const Scope *scope{&symbol.owner()};
2393   if (scope->IsGlobal()) {
2394     scope = &currScope();
2395   }
2396   scope = &GetInclusiveScope(*scope);
2397   const auto *type{implicitRulesMap_->at(scope).GetType(
2398       symbol.name(), respectImplicitNoneType)};
2399   if (type) {
2400     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2401       // Resolve any forward-referenced derived type; a quick no-op else.
2402       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2403       instantiatable.Instantiate(currScope());
2404     }
2405   }
2406   return type;
2407 }
2408 
2409 // Convert symbol to be a ObjectEntity or return false if it can't be.
2410 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2411   if (symbol.has<ObjectEntityDetails>()) {
2412     // nothing to do
2413   } else if (symbol.has<UnknownDetails>()) {
2414     symbol.set_details(ObjectEntityDetails{});
2415   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2416     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2417     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2418   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2419     return useDetails->symbol().has<ObjectEntityDetails>();
2420   } else {
2421     return false;
2422   }
2423   return true;
2424 }
2425 // Convert symbol to be a ProcEntity or return false if it can't be.
2426 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2427   if (symbol.has<ProcEntityDetails>()) {
2428     // nothing to do
2429   } else if (symbol.has<UnknownDetails>()) {
2430     symbol.set_details(ProcEntityDetails{});
2431   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2432     funcResultStack_.CompleteTypeIfFunctionResult(symbol);
2433     symbol.set_details(ProcEntityDetails{std::move(*details)});
2434     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2435       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2436       symbol.set(Symbol::Flag::Function);
2437     }
2438   } else {
2439     return false;
2440   }
2441   return true;
2442 }
2443 
2444 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2445     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2446   KindExpr value{GetKindParamExpr(category, kind)};
2447   if (auto known{evaluate::ToInt64(value)}) {
2448     return context().MakeNumericType(category, static_cast<int>(*known));
2449   } else {
2450     return currScope_->MakeNumericType(category, std::move(value));
2451   }
2452 }
2453 
2454 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2455     const std::optional<parser::KindSelector> &kind) {
2456   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2457   if (auto known{evaluate::ToInt64(value)}) {
2458     return context().MakeLogicalType(static_cast<int>(*known));
2459   } else {
2460     return currScope_->MakeLogicalType(std::move(value));
2461   }
2462 }
2463 
2464 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2465   if (inSpecificationPart_ && name.symbol) {
2466     auto kind{currScope().kind()};
2467     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2468         kind == Scope::Kind::Block) {
2469       bool isHostAssociated{&name.symbol->owner() == &currScope()
2470               ? name.symbol->has<HostAssocDetails>()
2471               : name.symbol->owner().Contains(currScope())};
2472       if (isHostAssociated) {
2473         specPartState_.forwardRefs.insert(name.source);
2474       }
2475     }
2476   }
2477 }
2478 
2479 std::optional<SourceName> ScopeHandler::HadForwardRef(
2480     const Symbol &symbol) const {
2481   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2482   if (iter != specPartState_.forwardRefs.end()) {
2483     return *iter;
2484   }
2485   return std::nullopt;
2486 }
2487 
2488 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2489   if (!context().HasError(symbol)) {
2490     if (auto fwdRef{HadForwardRef(symbol)}) {
2491       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2492       if (outer && symbol.has<UseDetails>() &&
2493           &symbol.GetUltimate() == &outer->GetUltimate()) {
2494         // e.g. IMPORT of host's USE association
2495         return false;
2496       }
2497       Say(*fwdRef,
2498           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2499           *fwdRef)
2500           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2501       context().SetError(symbol);
2502       return true;
2503     }
2504     if (IsDummy(symbol) && isImplicitNoneType() &&
2505         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2506       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2507       // ApplyImplicitRules() due to use in a specification expression,
2508       // and no explicit type declaration appeared later.
2509       Say(symbol.name(),
2510           "No explicit type declared for dummy argument '%s'"_err_en_US);
2511       context().SetError(symbol);
2512       return true;
2513     }
2514   }
2515   return false;
2516 }
2517 
2518 void ScopeHandler::MakeExternal(Symbol &symbol) {
2519   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2520     symbol.attrs().set(Attr::EXTERNAL);
2521     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2522       Say(symbol.name(),
2523           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2524           symbol.name());
2525     }
2526   }
2527 }
2528 
2529 // ModuleVisitor implementation
2530 
2531 bool ModuleVisitor::Pre(const parser::Only &x) {
2532   std::visit(common::visitors{
2533                  [&](const Indirection<parser::GenericSpec> &generic) {
2534                    GenericSpecInfo genericSpecInfo{generic.value()};
2535                    AddUseOnly(genericSpecInfo.symbolName());
2536                    AddUse(genericSpecInfo);
2537                  },
2538                  [&](const parser::Name &name) {
2539                    AddUseOnly(name.source);
2540                    Resolve(name, AddUse(name.source, name.source).use);
2541                  },
2542                  [&](const parser::Rename &rename) { Walk(rename); },
2543              },
2544       x.u);
2545   return false;
2546 }
2547 
2548 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2549   const auto &localName{std::get<0>(x.t)};
2550   const auto &useName{std::get<1>(x.t)};
2551   AddUseRename(useName.source);
2552   SymbolRename rename{AddUse(localName.source, useName.source)};
2553   if (rename.use) {
2554     EraseRenamedSymbol(*rename.use);
2555   }
2556   Resolve(useName, rename.use);
2557   Resolve(localName, rename.local);
2558   return false;
2559 }
2560 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2561   const parser::DefinedOpName &local{std::get<0>(x.t)};
2562   const parser::DefinedOpName &use{std::get<1>(x.t)};
2563   GenericSpecInfo localInfo{local};
2564   GenericSpecInfo useInfo{use};
2565   if (IsIntrinsicOperator(context(), local.v.source)) {
2566     Say(local.v,
2567         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2568   } else if (IsLogicalConstant(context(), local.v.source)) {
2569     Say(local.v,
2570         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2571   } else {
2572     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2573     if (rename.use) {
2574       EraseRenamedSymbol(*rename.use);
2575     }
2576     useInfo.Resolve(rename.use);
2577     localInfo.Resolve(rename.local);
2578   }
2579   return false;
2580 }
2581 
2582 // Set useModuleScope_ to the Scope of the module being used.
2583 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2584   std::optional<bool> isIntrinsic;
2585   if (x.nature) {
2586     isIntrinsic = *x.nature == parser::UseStmt::ModuleNature::Intrinsic;
2587     AddAndCheckExplicitIntrinsicUse(x.moduleName.source, *isIntrinsic);
2588   } else if (currScope().IsModule() && currScope().symbol() &&
2589       currScope().symbol()->attrs().test(Attr::INTRINSIC)) {
2590     // Intrinsic modules USE only other intrinsic modules
2591     isIntrinsic = true;
2592   }
2593   useModuleScope_ = FindModule(x.moduleName, isIntrinsic);
2594   if (!useModuleScope_) {
2595     return false;
2596   }
2597   // use the name from this source file
2598   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2599   return true;
2600 }
2601 
2602 void ModuleVisitor::Post(const parser::UseStmt &x) {
2603   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2604     // Not a use-only: collect the names that were used in renames,
2605     // then add a use for each public name that was not renamed.
2606     std::set<SourceName> useNames;
2607     for (const auto &rename : *list) {
2608       std::visit(common::visitors{
2609                      [&](const parser::Rename::Names &names) {
2610                        useNames.insert(std::get<1>(names.t).source);
2611                      },
2612                      [&](const parser::Rename::Operators &ops) {
2613                        useNames.insert(std::get<1>(ops.t).v.source);
2614                      },
2615                  },
2616           rename.u);
2617     }
2618     for (const auto &[name, symbol] : *useModuleScope_) {
2619       if (symbol->attrs().test(Attr::PUBLIC) && !IsUseRenamed(symbol->name()) &&
2620           (!symbol->attrs().test(Attr::INTRINSIC) ||
2621               symbol->has<UseDetails>()) &&
2622           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2623         SourceName location{x.moduleName.source};
2624         if (auto *localSymbol{FindInScope(name)}) {
2625           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2626         } else {
2627           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2628         }
2629       }
2630     }
2631   }
2632   useModuleScope_ = nullptr;
2633 }
2634 
2635 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2636     const SourceName &localName, const SourceName &useName) {
2637   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2638 }
2639 
2640 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2641     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2642   if (!useModuleScope_) {
2643     return {}; // error occurred finding module
2644   }
2645   if (!useSymbol) {
2646     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2647         useModuleScope_->GetName().value());
2648     return {};
2649   }
2650   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2651       !FindModuleFileContaining(currScope())) {
2652     // Privacy is not enforced in module files so that generic interfaces
2653     // can be resolved to private specific procedures in specification
2654     // expressions.
2655     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2656         useModuleScope_->GetName().value());
2657     return {};
2658   }
2659   auto &localSymbol{MakeSymbol(localName)};
2660   DoAddUse(useName, localName, localSymbol, *useSymbol);
2661   return {&localSymbol, useSymbol};
2662 }
2663 
2664 // symbol must be either a Use or a Generic formed by merging two uses.
2665 // Convert it to a UseError with this additional location.
2666 static void ConvertToUseError(
2667     Symbol &symbol, const SourceName &location, const Scope &module) {
2668   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2669   if (!useDetails) {
2670     auto &genericDetails{symbol.get<GenericDetails>()};
2671     useDetails = &genericDetails.uses().at(0)->get<UseDetails>();
2672   }
2673   symbol.set_details(
2674       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2675 }
2676 
2677 // If a symbol has previously been USE-associated and did not appear in a USE
2678 // ONLY clause, erase it from the current scope.  This is needed when a name
2679 // appears in a USE rename clause.
2680 void ModuleVisitor::EraseRenamedSymbol(const Symbol &useSymbol) {
2681   const SourceName &name{useSymbol.name()};
2682   if (const Symbol * symbol{FindInScope(name)}) {
2683     if (auto *useDetails{symbol->detailsIf<UseDetails>()}) {
2684       const Symbol &moduleSymbol{useDetails->symbol()};
2685       if (moduleSymbol.name() == name &&
2686           moduleSymbol.owner() == useSymbol.owner() && IsUseRenamed(name) &&
2687           !IsUseOnly(name)) {
2688         EraseSymbol(*symbol);
2689       }
2690     }
2691   }
2692 }
2693 
2694 void ModuleVisitor::DoAddUse(SourceName location, SourceName localName,
2695     Symbol &localSymbol, const Symbol &useSymbol) {
2696   if (localName != useSymbol.name()) {
2697     EraseRenamedSymbol(useSymbol);
2698   }
2699   if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2700     details->add_occurrence(location, *useModuleScope_);
2701     return;
2702   }
2703 
2704   if (localSymbol.has<UnknownDetails>()) {
2705     localSymbol.set_details(UseDetails{localName, useSymbol});
2706     localSymbol.attrs() =
2707         useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2708     localSymbol.flags() = useSymbol.flags();
2709     return;
2710   }
2711 
2712   Symbol &localUltimate{localSymbol.GetUltimate()};
2713   const Symbol &useUltimate{useSymbol.GetUltimate()};
2714   if (&localUltimate == &useUltimate) {
2715     // use-associating the same symbol again -- ok
2716     return;
2717   }
2718 
2719   auto checkAmbiguousDerivedType{[this, location, localName](
2720                                      const Symbol *t1, const Symbol *t2) {
2721     if (!t1 || !t2) {
2722       return true;
2723     } else {
2724       t1 = &t1->GetUltimate();
2725       t2 = &t2->GetUltimate();
2726       if (&t1 != &t2) {
2727         Say(location,
2728             "Generic interface '%s' has ambiguous derived types from modules '%s' and '%s'"_err_en_US,
2729             localName, t1->owner().GetName().value(),
2730             t2->owner().GetName().value());
2731         return false;
2732       }
2733     }
2734   }};
2735 
2736   auto *localGeneric{localUltimate.detailsIf<GenericDetails>()};
2737   const auto *useGeneric{useUltimate.detailsIf<GenericDetails>()};
2738   auto combine{false};
2739   if (localGeneric) {
2740     if (useGeneric) {
2741       if (!checkAmbiguousDerivedType(
2742               localGeneric->derivedType(), useGeneric->derivedType())) {
2743         return;
2744       }
2745       combine = true;
2746     } else if (useUltimate.has<DerivedTypeDetails>()) {
2747       if (checkAmbiguousDerivedType(
2748               &useUltimate, localGeneric->derivedType())) {
2749         combine = true;
2750       } else {
2751         return;
2752       }
2753     } else if (&useUltimate == &BypassGeneric(localUltimate)) {
2754       return; // nothing to do; used subprogram is local's specific
2755     }
2756   } else if (useGeneric) {
2757     if (localUltimate.has<DerivedTypeDetails>()) {
2758       if (checkAmbiguousDerivedType(
2759               &localUltimate, useGeneric->derivedType())) {
2760         combine = true;
2761       } else {
2762         return;
2763       }
2764     } else if (&localUltimate == &BypassGeneric(useUltimate).GetUltimate()) {
2765       // Local is the specific of the used generic; replace it.
2766       EraseSymbol(localSymbol);
2767       Symbol &newSymbol{MakeSymbol(localName,
2768           useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2769           UseDetails{localName, useUltimate})};
2770       newSymbol.flags() = useSymbol.flags();
2771       return;
2772     }
2773   }
2774   if (!combine) {
2775     if (localSymbol.has<UseDetails>() || localSymbol.has<GenericDetails>()) {
2776       ConvertToUseError(localSymbol, location, *useModuleScope_);
2777     } else {
2778       Say(location,
2779           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2780           localName)
2781           .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2782               localName);
2783     }
2784     return;
2785   }
2786 
2787   // Two items are being use-associated from different modules
2788   // to the same local name.  At least one of them must be a generic,
2789   // and the other one can be a generic or a derived type.
2790   // (It could also have been the specific of the generic, but those
2791   // cases are handled above without needing to make a local copy of the
2792   // generic.)
2793 
2794   if (localGeneric) {
2795     if (localSymbol.has<UseDetails>()) {
2796       // Create a local copy of a previously use-associated generic so that
2797       // it can be locally extended without corrupting the original.
2798       GenericDetails generic;
2799       generic.CopyFrom(*localGeneric);
2800       EraseSymbol(localSymbol);
2801       Symbol &newSymbol{MakeSymbol(
2802           localSymbol.name(), localSymbol.attrs(), std::move(generic))};
2803       newSymbol.flags() = localSymbol.flags();
2804       localGeneric = &newSymbol.get<GenericDetails>();
2805       localGeneric->AddUse(localSymbol);
2806     }
2807     if (useGeneric) {
2808       // Combine two use-associated generics
2809       localSymbol.attrs() =
2810           useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2811       localSymbol.flags() = useSymbol.flags();
2812       AddGenericUse(*localGeneric, localName, useUltimate);
2813       localGeneric->CopyFrom(*useGeneric);
2814     } else {
2815       CHECK(useUltimate.has<DerivedTypeDetails>());
2816       localGeneric->set_derivedType(
2817           AddGenericUse(*localGeneric, localName, useUltimate));
2818     }
2819   } else {
2820     CHECK(useGeneric && localUltimate.has<DerivedTypeDetails>());
2821     CHECK(localSymbol.has<UseDetails>());
2822     // Create a local copy of the use-associated generic, then extend it
2823     // with the local derived type.
2824     GenericDetails generic;
2825     generic.CopyFrom(*useGeneric);
2826     EraseSymbol(localSymbol);
2827     Symbol &newSymbol{MakeSymbol(localName,
2828         useUltimate.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE},
2829         std::move(generic))};
2830     newSymbol.flags() = useUltimate.flags();
2831     auto &newUseGeneric{newSymbol.get<GenericDetails>()};
2832     AddGenericUse(newUseGeneric, localName, useUltimate);
2833     newUseGeneric.AddUse(localSymbol);
2834     newUseGeneric.set_derivedType(localSymbol);
2835   }
2836 }
2837 
2838 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2839   if (useModuleScope_) {
2840     const auto &name{info.symbolName()};
2841     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2842     info.Resolve(rename.use);
2843   }
2844 }
2845 
2846 // Create a UseDetails symbol for this USE and add it to generic
2847 Symbol &ModuleVisitor::AddGenericUse(
2848     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2849   Symbol &newSymbol{
2850       currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol})};
2851   generic.AddUse(newSymbol);
2852   return newSymbol;
2853 }
2854 
2855 // Enforce C1406
2856 void ModuleVisitor::AddAndCheckExplicitIntrinsicUse(
2857     SourceName name, bool isIntrinsic) {
2858   if (isIntrinsic) {
2859     if (auto iter{explicitNonIntrinsicUses_.find(name)};
2860         iter != explicitNonIntrinsicUses_.end()) {
2861       Say(name,
2862           "Cannot USE,INTRINSIC module '%s' in the same scope as USE,NON_INTRINSIC"_err_en_US,
2863           name)
2864           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2865     }
2866     explicitIntrinsicUses_.insert(name);
2867   } else {
2868     if (auto iter{explicitIntrinsicUses_.find(name)};
2869         iter != explicitIntrinsicUses_.end()) {
2870       Say(name,
2871           "Cannot USE,NON_INTRINSIC module '%s' in the same scope as USE,INTRINSIC"_err_en_US,
2872           name)
2873           .Attach(*iter, "Previous USE of '%s'"_en_US, *iter);
2874     }
2875     explicitNonIntrinsicUses_.insert(name);
2876   }
2877 }
2878 
2879 bool ModuleVisitor::BeginSubmodule(
2880     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2881   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2882   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2883   Scope *ancestor{FindModule(ancestorName, false /*not intrinsic*/)};
2884   if (!ancestor) {
2885     return false;
2886   }
2887   Scope *parentScope{parentName
2888           ? FindModule(*parentName, false /*not intrinsic*/, ancestor)
2889           : ancestor};
2890   if (!parentScope) {
2891     return false;
2892   }
2893   PushScope(*parentScope); // submodule is hosted in parent
2894   BeginModule(name, true);
2895   if (!ancestor->AddSubmodule(name.source, currScope())) {
2896     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2897         ancestorName.source, name.source);
2898   }
2899   return true;
2900 }
2901 
2902 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2903   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2904   auto &details{symbol.get<ModuleDetails>()};
2905   PushScope(Scope::Kind::Module, &symbol);
2906   details.set_scope(&currScope());
2907   defaultAccess_ = Attr::PUBLIC;
2908   prevAccessStmt_ = std::nullopt;
2909 }
2910 
2911 // Find a module or submodule by name and return its scope.
2912 // If ancestor is present, look for a submodule of that ancestor module.
2913 // May have to read a .mod file to find it.
2914 // If an error occurs, report it and return nullptr.
2915 Scope *ModuleVisitor::FindModule(const parser::Name &name,
2916     std::optional<bool> isIntrinsic, Scope *ancestor) {
2917   ModFileReader reader{context()};
2918   Scope *scope{reader.Read(name.source, isIntrinsic, ancestor)};
2919   if (!scope) {
2920     return nullptr;
2921   }
2922   if (scope->kind() != Scope::Kind::Module) {
2923     Say(name, "'%s' is not a module"_err_en_US);
2924     return nullptr;
2925   }
2926   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2927     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2928   }
2929   Resolve(name, scope->symbol());
2930   return scope;
2931 }
2932 
2933 void ModuleVisitor::ApplyDefaultAccess() {
2934   for (auto &pair : currScope()) {
2935     Symbol &symbol = *pair.second;
2936     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2937       symbol.attrs().set(defaultAccess_);
2938     }
2939   }
2940 }
2941 
2942 // InterfaceVistor implementation
2943 
2944 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2945   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2946   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2947   return BeginAttrs();
2948 }
2949 
2950 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2951 
2952 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2953   genericInfo_.pop();
2954 }
2955 
2956 // Create a symbol in genericSymbol_ for this GenericSpec.
2957 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2958   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
2959     SetGenericSymbol(*symbol);
2960   }
2961   return false;
2962 }
2963 
2964 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2965   if (!isGeneric()) {
2966     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2967     return false;
2968   }
2969   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2970   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2971   AddSpecificProcs(names, kind);
2972   return false;
2973 }
2974 
2975 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2976   genericInfo_.emplace(/*isInterface*/ false);
2977   return true;
2978 }
2979 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2980   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2981     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2982   }
2983   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2984   AddSpecificProcs(names, ProcedureKind::Procedure);
2985   genericInfo_.pop();
2986 }
2987 
2988 bool InterfaceVisitor::inInterfaceBlock() const {
2989   return !genericInfo_.empty() && GetGenericInfo().isInterface;
2990 }
2991 bool InterfaceVisitor::isGeneric() const {
2992   return !genericInfo_.empty() && GetGenericInfo().symbol;
2993 }
2994 bool InterfaceVisitor::isAbstract() const {
2995   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
2996 }
2997 
2998 void InterfaceVisitor::AddSpecificProcs(
2999     const std::list<parser::Name> &names, ProcedureKind kind) {
3000   for (const auto &name : names) {
3001     specificProcs_.emplace(
3002         GetGenericInfo().symbol, std::make_pair(&name, kind));
3003   }
3004 }
3005 
3006 // By now we should have seen all specific procedures referenced by name in
3007 // this generic interface. Resolve those names to symbols.
3008 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
3009   auto &details{generic.get<GenericDetails>()};
3010   UnorderedSymbolSet symbolsSeen;
3011   for (const Symbol &symbol : details.specificProcs()) {
3012     symbolsSeen.insert(symbol.GetUltimate());
3013   }
3014   auto range{specificProcs_.equal_range(&generic)};
3015   for (auto it{range.first}; it != range.second; ++it) {
3016     const parser::Name *name{it->second.first};
3017     auto kind{it->second.second};
3018     const auto *symbol{FindSymbol(*name)};
3019     if (!symbol) {
3020       Say(*name, "Procedure '%s' not found"_err_en_US);
3021       continue;
3022     }
3023     const Symbol &specific{BypassGeneric(*symbol)};
3024     const Symbol &ultimate{specific.GetUltimate()};
3025     if (!ultimate.has<SubprogramDetails>() &&
3026         !ultimate.has<SubprogramNameDetails>()) {
3027       Say(*name, "'%s' is not a subprogram"_err_en_US);
3028       continue;
3029     }
3030     if (kind == ProcedureKind::ModuleProcedure) {
3031       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
3032         if (nd->kind() != SubprogramKind::Module) {
3033           Say(*name, "'%s' is not a module procedure"_err_en_US);
3034         }
3035       } else {
3036         // USE-associated procedure
3037         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
3038         CHECK(sd);
3039         if (ultimate.owner().kind() != Scope::Kind::Module ||
3040             sd->isInterface()) {
3041           Say(*name, "'%s' is not a module procedure"_err_en_US);
3042         }
3043       }
3044     }
3045     if (symbolsSeen.insert(ultimate).second /*true if added*/) {
3046       // When a specific procedure is a USE association, that association
3047       // is saved in the generic's specifics, not its ultimate symbol,
3048       // so that module file output of interfaces can distinguish them.
3049       details.AddSpecificProc(specific, name->source);
3050     } else if (&specific == &ultimate) {
3051       Say(name->source,
3052           "Procedure '%s' is already specified in generic '%s'"_err_en_US,
3053           name->source, MakeOpName(generic.name()));
3054     } else {
3055       Say(name->source,
3056           "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
3057           ultimate.name(), ultimate.owner().GetName().value(),
3058           MakeOpName(generic.name()));
3059     }
3060   }
3061   specificProcs_.erase(range.first, range.second);
3062 }
3063 
3064 // Check that the specific procedures are all functions or all subroutines.
3065 // If there is a derived type with the same name they must be functions.
3066 // Set the corresponding flag on generic.
3067 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
3068   ResolveSpecificsInGeneric(generic);
3069   auto &details{generic.get<GenericDetails>()};
3070   if (auto *proc{details.CheckSpecific()}) {
3071     auto msg{
3072         "'%s' may not be the name of both a generic interface and a"
3073         " procedure unless it is a specific procedure of the generic"_err_en_US};
3074     if (proc->name().begin() > generic.name().begin()) {
3075       Say(proc->name(), std::move(msg));
3076     } else {
3077       Say(generic.name(), std::move(msg));
3078     }
3079   }
3080   auto &specifics{details.specificProcs()};
3081   if (specifics.empty()) {
3082     if (details.derivedType()) {
3083       generic.set(Symbol::Flag::Function);
3084     }
3085     return;
3086   }
3087   const Symbol &firstSpecific{specifics.front()};
3088   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
3089   for (const Symbol &specific : specifics) {
3090     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
3091       auto &msg{Say(generic.name(),
3092           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
3093       if (isFunction) {
3094         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
3095         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
3096       } else {
3097         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
3098         msg.Attach(specific.name(), "Function declaration"_en_US);
3099       }
3100     }
3101   }
3102   if (!isFunction && details.derivedType()) {
3103     SayDerivedType(generic.name(),
3104         "Generic interface '%s' may only contain functions due to derived type"
3105         " with same name"_err_en_US,
3106         *details.derivedType()->scope());
3107   }
3108   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
3109 }
3110 
3111 // SubprogramVisitor implementation
3112 
3113 // Return false if it is actually an assignment statement.
3114 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
3115   const auto &name{std::get<parser::Name>(x.t)};
3116   const DeclTypeSpec *resultType{nullptr};
3117   // Look up name: provides return type or tells us if it's an array
3118   if (auto *symbol{FindSymbol(name)}) {
3119     auto *details{symbol->detailsIf<EntityDetails>()};
3120     if (!details) {
3121       badStmtFuncFound_ = true;
3122       return false;
3123     }
3124     // TODO: check that attrs are compatible with stmt func
3125     resultType = details->type();
3126     symbol->details() = UnknownDetails{}; // will be replaced below
3127   }
3128   if (badStmtFuncFound_) {
3129     Say(name, "'%s' has not been declared as an array"_err_en_US);
3130     return true;
3131   }
3132   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
3133   symbol.set(Symbol::Flag::StmtFunction);
3134   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
3135   auto &details{symbol.get<SubprogramDetails>()};
3136   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
3137     ObjectEntityDetails dummyDetails{true};
3138     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
3139       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
3140         if (d->type()) {
3141           dummyDetails.set_type(*d->type());
3142         }
3143       }
3144     }
3145     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
3146     ApplyImplicitRules(dummy);
3147     details.add_dummyArg(dummy);
3148   }
3149   ObjectEntityDetails resultDetails;
3150   if (resultType) {
3151     resultDetails.set_type(*resultType);
3152   }
3153   resultDetails.set_funcResult(true);
3154   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
3155   ApplyImplicitRules(result);
3156   details.set_result(result);
3157   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
3158   Walk(parsedExpr);
3159   // The analysis of the expression that constitutes the body of the
3160   // statement function is deferred to FinishSpecificationPart() so that
3161   // all declarations and implicit typing are complete.
3162   PopScope();
3163   return true;
3164 }
3165 
3166 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
3167   if (suffix.resultName) {
3168     if (IsFunction(currScope())) {
3169       if (FuncResultStack::FuncInfo * info{funcResultStack().Top()}) {
3170         if (info->inFunctionStmt) {
3171           info->resultName = &suffix.resultName.value();
3172         } else {
3173           // will check the result name in Post(EntryStmt)
3174         }
3175       }
3176     } else {
3177       Message &msg{Say(*suffix.resultName,
3178           "RESULT(%s) may appear only in a function"_err_en_US)};
3179       if (const Symbol * subprogram{InclusiveScope().symbol()}) {
3180         msg.Attach(subprogram->name(), "Containing subprogram"_en_US);
3181       }
3182     }
3183   }
3184   return true;
3185 }
3186 
3187 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
3188   // Save this to process after UseStmt and ImplicitPart
3189   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
3190     FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3191     if (info.parsedType) { // C1543
3192       Say(currStmtSource().value(),
3193           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
3194       return false;
3195     } else {
3196       info.parsedType = parsedType;
3197       info.source = currStmtSource();
3198       return false;
3199     }
3200   } else {
3201     return true;
3202   }
3203 }
3204 
3205 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
3206   const auto &name{std::get<parser::Name>(
3207       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
3208   return BeginSubprogram(name, Symbol::Flag::Subroutine);
3209 }
3210 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
3211   EndSubprogram();
3212 }
3213 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
3214   const auto &name{std::get<parser::Name>(
3215       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
3216   return BeginSubprogram(name, Symbol::Flag::Function);
3217 }
3218 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
3219   EndSubprogram();
3220 }
3221 
3222 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
3223   return BeginAttrs();
3224 }
3225 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
3226   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3227   CHECK(!info.inFunctionStmt);
3228   info.inFunctionStmt = true;
3229   return BeginAttrs();
3230 }
3231 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
3232 
3233 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
3234   const auto &name{std::get<parser::Name>(stmt.t)};
3235   auto &details{PostSubprogramStmt(name)};
3236   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3237     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3238       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails{true})};
3239       details.add_dummyArg(dummy);
3240     } else {
3241       details.add_alternateReturn();
3242     }
3243   }
3244 }
3245 
3246 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
3247   const auto &name{std::get<parser::Name>(stmt.t)};
3248   auto &details{PostSubprogramStmt(name)};
3249   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
3250     Symbol &dummy{MakeSymbol(dummyName, EntityDetails{true})};
3251     details.add_dummyArg(dummy);
3252   }
3253   const parser::Name *funcResultName;
3254   FuncResultStack::FuncInfo &info{DEREF(funcResultStack().Top())};
3255   CHECK(info.inFunctionStmt);
3256   info.inFunctionStmt = false;
3257   if (info.resultName && info.resultName->source != name.source) {
3258     // Note that RESULT is ignored if it has the same name as the function.
3259     funcResultName = info.resultName;
3260   } else {
3261     EraseSymbol(name); // was added by PushSubprogramScope
3262     funcResultName = &name;
3263   }
3264   // add function result to function scope
3265   if (details.isFunction()) {
3266     CHECK(context().HasError(currScope().symbol()));
3267   } else {
3268     // add function result to function scope
3269     EntityDetails funcResultDetails;
3270     funcResultDetails.set_funcResult(true);
3271     Symbol &result{MakeSymbol(*funcResultName, std::move(funcResultDetails))};
3272     info.resultSymbol = &result;
3273     details.set_result(result);
3274   }
3275   // C1560.
3276   if (info.resultName && info.resultName->source == name.source) {
3277     Say(info.resultName->source,
3278         "The function name should not appear in RESULT, references to '%s' "
3279         "inside the function will be considered as references to the "
3280         "result only"_warn_en_US,
3281         name.source);
3282     // RESULT name was ignored above, the only side effect from doing so will be
3283     // the inability to make recursive calls. The related parser::Name is still
3284     // resolved to the created function result symbol because every parser::Name
3285     // should be resolved to avoid internal errors.
3286     Resolve(*info.resultName, info.resultSymbol);
3287   }
3288   name.symbol = currScope().symbol(); // must not be function result symbol
3289   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
3290   // has a RESULT() suffix.
3291   info.resultName = nullptr;
3292 }
3293 
3294 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
3295     const parser::Name &name) {
3296   Symbol &symbol{*currScope().symbol()};
3297   CHECK(name.source == symbol.name());
3298   SetBindNameOn(symbol);
3299   symbol.attrs() |= EndAttrs();
3300   if (symbol.attrs().test(Attr::MODULE)) {
3301     symbol.attrs().set(Attr::EXTERNAL, false);
3302   }
3303   return symbol.get<SubprogramDetails>();
3304 }
3305 
3306 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
3307   auto attrs{EndAttrs()}; // needs to be called even if early return
3308   Scope &inclusiveScope{InclusiveScope()};
3309   const Symbol *subprogram{inclusiveScope.symbol()};
3310   if (!subprogram) {
3311     CHECK(context().AnyFatalError());
3312     return;
3313   }
3314   const auto &name{std::get<parser::Name>(stmt.t)};
3315   const parser::Name *resultName{nullptr};
3316   if (const auto &maybeSuffix{
3317           std::get<std::optional<parser::Suffix>>(stmt.t)}) {
3318     resultName = common::GetPtrFromOptional(maybeSuffix->resultName);
3319   }
3320   bool inFunction{IsFunction(currScope())};
3321   if (resultName) { // RESULT(result) is present
3322     if (!inFunction) {
3323       // error was already emitted for the suffix
3324     } else if (resultName->source == subprogram->name()) { // C1574
3325       Say2(resultName->source,
3326           "RESULT(%s) may not have the same name as the function"_err_en_US,
3327           subprogram->name(), "Containing function"_en_US);
3328     } else if (const Symbol *
3329         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
3330       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
3331         if (details->entryScope() == &inclusiveScope) {
3332           Say2(resultName->source,
3333               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3334               symbol->name(), "Conflicting ENTRY"_en_US);
3335         }
3336       }
3337     }
3338     if (Symbol * symbol{FindSymbol(name)}) { // C1570
3339       // When RESULT() appears, ENTRY name can't have been already declared
3340       if (inclusiveScope.Contains(symbol->owner())) {
3341         Say2(name,
3342             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
3343             *symbol, "Previous declaration of '%s'"_en_US);
3344       }
3345     }
3346     if (resultName->source == name.source) {
3347       // ignore RESULT() hereafter when it's the same name as the ENTRY
3348       resultName = nullptr;
3349     }
3350   }
3351   SubprogramDetails entryDetails;
3352   entryDetails.set_entryScope(inclusiveScope);
3353   if (inFunction) {
3354     // Create the entity to hold the function result, if necessary.
3355     Symbol *resultSymbol{nullptr};
3356     auto &effectiveResultName{*(resultName ? resultName : &name)};
3357     resultSymbol = FindInScope(currScope(), effectiveResultName);
3358     if (resultSymbol) { // C1574
3359       std::visit(
3360           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
3361               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
3362               [](ProcEntityDetails &x) { x.set_funcResult(true); },
3363               [&](const auto &) {
3364                 Say2(effectiveResultName.source,
3365                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
3366                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
3367                 context().SetError(*resultSymbol);
3368               }},
3369           resultSymbol->details());
3370     } else if (inExecutionPart_) {
3371       ObjectEntityDetails entity;
3372       entity.set_funcResult(true);
3373       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3374       ApplyImplicitRules(*resultSymbol);
3375     } else {
3376       EntityDetails entity;
3377       entity.set_funcResult(true);
3378       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3379     }
3380     if (!resultName) {
3381       name.symbol = nullptr; // symbol will be used for entry point below
3382     }
3383     entryDetails.set_result(*resultSymbol);
3384   }
3385 
3386   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3387     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3388       Symbol *dummy{FindSymbol(*dummyName)};
3389       if (dummy) {
3390         std::visit(
3391             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3392                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3393                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3394                 [](SubprogramDetails &x) { x.set_isDummy(); },
3395                 [&](const auto &) {
3396                   Say2(dummyName->source,
3397                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3398                       dummy->name(), "Previous declaration of '%s'"_en_US);
3399                 }},
3400             dummy->details());
3401       } else {
3402         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3403         if (inExecutionPart_) {
3404           ApplyImplicitRules(*dummy);
3405         }
3406       }
3407       entryDetails.add_dummyArg(*dummy);
3408     } else {
3409       if (inFunction) { // C1573
3410         Say(name,
3411             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3412         break;
3413       }
3414       entryDetails.add_alternateReturn();
3415     }
3416   }
3417 
3418   Symbol::Flag subpFlag{
3419       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
3420   Scope &outer{inclusiveScope.parent()}; // global or module scope
3421   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3422     attrs.set(Attr::PUBLIC);
3423   }
3424   if (Symbol * extant{FindSymbol(outer, name)}) {
3425     if (!HandlePreviousCalls(name, *extant, subpFlag)) {
3426       if (outer.IsGlobal()) {
3427         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
3428             *extant, "Previous definition of '%s'"_en_US);
3429       } else {
3430         SayAlreadyDeclared(name, *extant);
3431       }
3432       return;
3433     }
3434   }
3435 
3436   Symbol *entrySymbol{&MakeSymbol(outer, name.source, attrs)};
3437   if (auto *generic{entrySymbol->detailsIf<GenericDetails>()}) {
3438     CHECK(generic->specific());
3439     entrySymbol = generic->specific();
3440   }
3441   entrySymbol->set_details(std::move(entryDetails));
3442   SetBindNameOn(*entrySymbol);
3443   entrySymbol->set(subpFlag);
3444   Resolve(name, *entrySymbol);
3445 }
3446 
3447 // A subprogram declared with MODULE PROCEDURE
3448 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3449   auto *symbol{FindSymbol(name)};
3450   if (symbol && symbol->has<SubprogramNameDetails>()) {
3451     symbol = FindSymbol(currScope().parent(), name);
3452   }
3453   if (!IsSeparateModuleProcedureInterface(symbol)) {
3454     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3455     return false;
3456   }
3457   if (symbol->owner() == currScope() && symbol->scope()) {
3458     // This is a MODULE PROCEDURE whose interface appears in its host.
3459     // Convert the module procedure's interface into a subprogram.
3460     SetScope(DEREF(symbol->scope()));
3461     symbol->get<SubprogramDetails>().set_isInterface(false);
3462     if (IsFunction(*symbol)) {
3463       funcResultStack().Push(); // just to be popped later
3464     }
3465   } else {
3466     // Copy the interface into a new subprogram scope.
3467     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3468     PushScope(Scope::Kind::Subprogram, &newSymbol);
3469     const auto &details{symbol->get<SubprogramDetails>()};
3470     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3471     newDetails.set_moduleInterface(*symbol);
3472     for (const Symbol *dummyArg : details.dummyArgs()) {
3473       if (!dummyArg) {
3474         newDetails.add_alternateReturn();
3475       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3476         newDetails.add_dummyArg(*copy);
3477       }
3478     }
3479     if (details.isFunction()) {
3480       currScope().erase(symbol->name());
3481       newDetails.set_result(*currScope().CopySymbol(details.result()));
3482       funcResultStack().Push(); // just to be popped later
3483     }
3484   }
3485   return true;
3486 }
3487 
3488 // A subprogram or interface declared with SUBROUTINE or FUNCTION
3489 bool SubprogramVisitor::BeginSubprogram(
3490     const parser::Name &name, Symbol::Flag subpFlag, bool hasModulePrefix) {
3491   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3492     Say(name,
3493         "'%s' is a MODULE procedure which must be declared within a "
3494         "MODULE or SUBMODULE"_err_en_US);
3495     return false;
3496   }
3497   Symbol *moduleInterface{nullptr};
3498   if (hasModulePrefix && !inInterfaceBlock()) {
3499     moduleInterface = FindSymbol(currScope(), name);
3500     if (IsSeparateModuleProcedureInterface(moduleInterface)) {
3501       // Subprogram is MODULE FUNCTION or MODULE SUBROUTINE with an interface
3502       // previously defined in the same scope.
3503       currScope().erase(moduleInterface->name());
3504     } else {
3505       moduleInterface = nullptr;
3506     }
3507     if (!moduleInterface) {
3508       moduleInterface = FindSymbol(currScope().parent(), name);
3509       if (!IsSeparateModuleProcedureInterface(moduleInterface)) {
3510         Say(name,
3511             "'%s' was not declared a separate module procedure"_err_en_US);
3512         return false;
3513       }
3514     }
3515   }
3516   Symbol &newSymbol{PushSubprogramScope(name, subpFlag)};
3517   if (moduleInterface) {
3518     newSymbol.get<SubprogramDetails>().set_moduleInterface(*moduleInterface);
3519     if (moduleInterface->attrs().test(Attr::PRIVATE)) {
3520       newSymbol.attrs().set(Attr::PRIVATE);
3521     } else if (moduleInterface->attrs().test(Attr::PUBLIC)) {
3522       newSymbol.attrs().set(Attr::PUBLIC);
3523     }
3524   }
3525   if (IsFunction(currScope())) {
3526     funcResultStack().Push();
3527   }
3528   return true;
3529 }
3530 
3531 void SubprogramVisitor::EndSubprogram() {
3532   if (IsFunction(currScope())) {
3533     funcResultStack().Pop();
3534   }
3535   PopScope();
3536 }
3537 
3538 bool SubprogramVisitor::HandlePreviousCalls(
3539     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3540   // If the extant symbol is a generic, check its homonymous specific
3541   // procedure instead if it has one.
3542   if (auto *generic{symbol.detailsIf<GenericDetails>()}) {
3543     return generic->specific() &&
3544         HandlePreviousCalls(name, *generic->specific(), subpFlag);
3545   } else if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3546              !proc->isDummy() &&
3547              !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3548     // There's a symbol created for previous calls to this subprogram or
3549     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3550     // obligation to rewrite symbol pointers in the parse tree.
3551     if (!symbol.test(subpFlag)) {
3552       Say2(name,
3553           subpFlag == Symbol::Flag::Function
3554               ? "'%s' was previously called as a subroutine"_err_en_US
3555               : "'%s' was previously called as a function"_err_en_US,
3556           symbol, "Previous call of '%s'"_en_US);
3557     }
3558     EntityDetails entity;
3559     if (proc->type()) {
3560       entity.set_type(*proc->type());
3561     }
3562     symbol.details() = std::move(entity);
3563     return true;
3564   } else {
3565     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3566   }
3567 }
3568 
3569 void SubprogramVisitor::CheckExtantProc(
3570     const parser::Name &name, Symbol::Flag subpFlag) {
3571   if (auto *prev{FindSymbol(name)}) {
3572     if (IsDummy(*prev)) {
3573     } else if (inInterfaceBlock() && currScope() != prev->owner()) {
3574       // Procedures in an INTERFACE block do not resolve to symbols
3575       // in scopes between the global scope and the current scope.
3576     } else if (!HandlePreviousCalls(name, *prev, subpFlag)) {
3577       SayAlreadyDeclared(name, *prev);
3578     }
3579   }
3580 }
3581 
3582 Symbol &SubprogramVisitor::PushSubprogramScope(
3583     const parser::Name &name, Symbol::Flag subpFlag) {
3584   auto *symbol{GetSpecificFromGeneric(name)};
3585   if (!symbol) {
3586     CheckExtantProc(name, subpFlag);
3587     symbol = &MakeSymbol(name, SubprogramDetails{});
3588   }
3589   symbol->set(subpFlag);
3590   symbol->ReplaceName(name.source);
3591   PushScope(Scope::Kind::Subprogram, symbol);
3592   auto &details{symbol->get<SubprogramDetails>()};
3593   if (inInterfaceBlock()) {
3594     details.set_isInterface();
3595     if (isAbstract()) {
3596       symbol->attrs().set(Attr::ABSTRACT);
3597     } else {
3598       MakeExternal(*symbol);
3599     }
3600     if (isGeneric()) {
3601       Symbol &genericSymbol{GetGenericSymbol()};
3602       if (genericSymbol.has<GenericDetails>()) {
3603         genericSymbol.get<GenericDetails>().AddSpecificProc(
3604             *symbol, name.source);
3605       } else {
3606         CHECK(context().HasError(genericSymbol));
3607       }
3608     }
3609     set_inheritFromParent(false);
3610   }
3611   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3612   return *symbol;
3613 }
3614 
3615 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3616   if (auto *prev{FindSymbol(name)}) {
3617     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3618       if (prev->test(Symbol::Flag::Subroutine) ||
3619           prev->test(Symbol::Flag::Function)) {
3620         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3621             "Previous call of '%s'"_en_US);
3622       }
3623       EraseSymbol(name);
3624     }
3625   }
3626   if (name.source.empty()) {
3627     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3628     PushScope(Scope::Kind::BlockData, nullptr);
3629   } else {
3630     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3631   }
3632 }
3633 
3634 // If name is a generic, return specific subprogram with the same name.
3635 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3636   if (auto *symbol{FindSymbol(name)}) {
3637     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3638       // found generic, want subprogram
3639       auto *specific{details->specific()};
3640       if (!specific) {
3641         specific =
3642             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3643         if (details->derivedType()) {
3644           // A specific procedure with the same name as a derived type
3645           SayAlreadyDeclared(name, *details->derivedType());
3646         } else {
3647           details->set_specific(Resolve(name, *specific));
3648         }
3649       } else if (isGeneric()) {
3650         SayAlreadyDeclared(name, *specific);
3651       }
3652       if (!specific->has<SubprogramDetails>()) {
3653         specific->set_details(SubprogramDetails{});
3654       }
3655       return specific;
3656     }
3657   }
3658   return nullptr;
3659 }
3660 
3661 // DeclarationVisitor implementation
3662 
3663 bool DeclarationVisitor::BeginDecl() {
3664   BeginDeclTypeSpec();
3665   BeginArraySpec();
3666   return BeginAttrs();
3667 }
3668 void DeclarationVisitor::EndDecl() {
3669   EndDeclTypeSpec();
3670   EndArraySpec();
3671   EndAttrs();
3672 }
3673 
3674 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3675   const auto *details{
3676       name.symbol ? name.symbol->detailsIf<UseErrorDetails>() : nullptr};
3677   if (!details) {
3678     return false;
3679   }
3680   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3681   for (const auto &[location, module] : details->occurrences()) {
3682     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3683         name.source, module->GetName().value());
3684   }
3685   context().SetError(*name.symbol);
3686   return true;
3687 }
3688 
3689 // Report error if accessibility of symbol doesn't match isPrivate.
3690 void DeclarationVisitor::CheckAccessibility(
3691     const SourceName &name, bool isPrivate, Symbol &symbol) {
3692   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3693     Say2(name,
3694         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3695         symbol, "Previous declaration of '%s'"_en_US);
3696   }
3697 }
3698 
3699 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3700   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3701     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3702       if (typeSpec->category() == DeclTypeSpec::Character) {
3703         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3704           Say("The type parameter LEN cannot be deferred without"
3705               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3706         }
3707       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3708         for (const auto &pair : derivedSpec->parameters()) {
3709           if (pair.second.isDeferred()) {
3710             Say(currStmtSource().value(),
3711                 "The value of type parameter '%s' cannot be deferred"
3712                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3713                 pair.first);
3714           }
3715         }
3716       }
3717     }
3718   }
3719   EndDecl();
3720 }
3721 
3722 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3723   DeclareObjectEntity(std::get<parser::Name>(x.t));
3724 }
3725 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3726   DeclareObjectEntity(std::get<parser::Name>(x.t));
3727 }
3728 
3729 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3730   // Defer inspection of initializers to Initialization() so that the
3731   // symbol being initialized will be available within the initialization
3732   // expression.
3733   return false;
3734 }
3735 
3736 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3737   const auto &name{std::get<parser::ObjectName>(x.t)};
3738   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3739   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3740   symbol.ReplaceName(name.source);
3741   if (const auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3742     if (ConvertToObjectEntity(symbol)) {
3743       Initialization(name, *init, false);
3744     }
3745   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3746     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3747   }
3748 }
3749 
3750 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3751   const auto &name{std::get<parser::Name>(x.t)};
3752   if (const auto &deferredShapeSpecs{
3753           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3754     CHECK(arraySpec().empty());
3755     BeginArraySpec();
3756     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3757     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3758     symbol.ReplaceName(name.source);
3759     EndArraySpec();
3760   } else {
3761     Symbol &symbol{DeclareUnknownEntity(name, Attrs{Attr::POINTER})};
3762     symbol.ReplaceName(name.source);
3763   }
3764 }
3765 
3766 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3767   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3768   auto &name{std::get<parser::Name>(x.t)};
3769   Symbol *symbol;
3770   if (kind == parser::BindEntity::Kind::Object) {
3771     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3772   } else {
3773     symbol = &MakeCommonBlockSymbol(name);
3774     symbol->attrs().set(Attr::BIND_C);
3775   }
3776   SetBindNameOn(*symbol);
3777   return false;
3778 }
3779 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3780   inOldStyleParameterStmt_ = true;
3781   Walk(x.v);
3782   inOldStyleParameterStmt_ = false;
3783   return false;
3784 }
3785 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3786   auto &name{std::get<parser::NamedConstant>(x.t).v};
3787   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3788   if (!ConvertToObjectEntity(symbol) ||
3789       symbol.test(Symbol::Flag::CrayPointer) ||
3790       symbol.test(Symbol::Flag::CrayPointee)) {
3791     SayWithDecl(
3792         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3793     return false;
3794   }
3795   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3796   auto &details{symbol.get<ObjectEntityDetails>()};
3797   if (inOldStyleParameterStmt_) {
3798     // non-standard extension PARAMETER statement (no parentheses)
3799     Walk(expr);
3800     auto folded{EvaluateExpr(expr)};
3801     if (details.type()) {
3802       SayWithDecl(name, symbol,
3803           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3804     } else if (folded) {
3805       auto at{expr.thing.value().source};
3806       if (evaluate::IsActuallyConstant(*folded)) {
3807         if (const auto *type{currScope().GetType(*folded)}) {
3808           if (type->IsPolymorphic()) {
3809             Say(at, "The expression must not be polymorphic"_err_en_US);
3810           } else if (auto shape{ToArraySpec(
3811                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3812             // The type of the named constant is assumed from the expression.
3813             details.set_type(*type);
3814             details.set_init(std::move(*folded));
3815             details.set_shape(std::move(*shape));
3816           } else {
3817             Say(at, "The expression must have constant shape"_err_en_US);
3818           }
3819         } else {
3820           Say(at, "The expression must have a known type"_err_en_US);
3821         }
3822       } else {
3823         Say(at, "The expression must be a constant of known type"_err_en_US);
3824       }
3825     }
3826   } else {
3827     // standard-conforming PARAMETER statement (with parentheses)
3828     ApplyImplicitRules(symbol);
3829     Walk(expr);
3830     if (auto converted{EvaluateNonPointerInitializer(
3831             symbol, expr, expr.thing.value().source)}) {
3832       details.set_init(std::move(*converted));
3833     }
3834   }
3835   return false;
3836 }
3837 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3838   const parser::Name &name{x.v};
3839   if (!FindSymbol(name)) {
3840     Say(name, "Named constant '%s' not found"_err_en_US);
3841   } else {
3842     CheckUseError(name);
3843   }
3844   return false;
3845 }
3846 
3847 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3848   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3849   Symbol *symbol{FindSymbol(name)};
3850   if (symbol && !symbol->has<UnknownDetails>()) {
3851     // Contrary to named constants appearing in a PARAMETER statement,
3852     // enumerator names should not have their type, dimension or any other
3853     // attributes defined before they are declared in the enumerator statement,
3854     // with the exception of accessibility.
3855     // This is not explicitly forbidden by the standard, but they are scalars
3856     // which type is left for the compiler to chose, so do not let users try to
3857     // tamper with that.
3858     SayAlreadyDeclared(name, *symbol);
3859     symbol = nullptr;
3860   } else {
3861     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3862     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3863     symbol->SetType(context().MakeNumericType(
3864         TypeCategory::Integer, evaluate::CInteger::kind));
3865   }
3866 
3867   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3868           enumerator.t)}) {
3869     Walk(*init); // Resolve names in expression before evaluation.
3870     if (auto value{EvaluateInt64(context(), *init)}) {
3871       // Cast all init expressions to C_INT so that they can then be
3872       // safely incremented (see 7.6 Note 2).
3873       enumerationState_.value = static_cast<int>(*value);
3874     } else {
3875       Say(name,
3876           "Enumerator value could not be computed "
3877           "from the given expression"_err_en_US);
3878       // Prevent resolution of next enumerators value
3879       enumerationState_.value = std::nullopt;
3880     }
3881   }
3882 
3883   if (symbol) {
3884     if (enumerationState_.value) {
3885       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3886           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3887     } else {
3888       context().SetError(*symbol);
3889     }
3890   }
3891 
3892   if (enumerationState_.value) {
3893     (*enumerationState_.value)++;
3894   }
3895   return false;
3896 }
3897 
3898 void DeclarationVisitor::Post(const parser::EnumDef &) {
3899   enumerationState_ = EnumeratorState{};
3900 }
3901 
3902 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3903   Attr attr{AccessSpecToAttr(x)};
3904   if (!NonDerivedTypeScope().IsModule()) { // C817
3905     Say(currStmtSource().value(),
3906         "%s attribute may only appear in the specification part of a module"_err_en_US,
3907         EnumToString(attr));
3908   }
3909   CheckAndSet(attr);
3910   return false;
3911 }
3912 
3913 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3914   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3915 }
3916 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3917   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3918 }
3919 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3920   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3921   for (const auto &name : x.v) {
3922     auto *symbol{FindSymbol(name)};
3923     if (!ConvertToProcEntity(DEREF(symbol))) {
3924       SayWithDecl(
3925           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3926     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
3927       Say(symbol->name(),
3928           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
3929           symbol->name());
3930     }
3931   }
3932   return false;
3933 }
3934 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3935   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3936   auto &names{std::get<std::list<parser::Name>>(x.t)};
3937   return CheckNotInBlock("INTENT") && // C1107
3938       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3939 }
3940 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3941   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3942   for (const auto &name : x.v) {
3943     auto &symbol{DEREF(FindSymbol(name))};
3944     if (symbol.has<GenericDetails>()) {
3945       // Generic interface is extending intrinsic; ok
3946     } else if (!symbol.has<HostAssocDetails>() &&
3947         !ConvertToProcEntity(symbol)) {
3948       SayWithDecl(
3949           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3950     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
3951       Say(symbol.name(),
3952           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3953           symbol.name());
3954     } else if (symbol.GetType()) {
3955       // These warnings are worded so that they should make sense in either
3956       // order.
3957       Say(symbol.name(),
3958           "Explicit type declaration ignored for intrinsic function '%s'"_warn_en_US,
3959           symbol.name())
3960           .Attach(name.source,
3961               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
3962               name.source);
3963     }
3964   }
3965   return false;
3966 }
3967 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3968   return CheckNotInBlock("OPTIONAL") && // C1107
3969       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3970 }
3971 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3972   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3973 }
3974 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3975   return CheckNotInBlock("VALUE") && // C1107
3976       HandleAttributeStmt(Attr::VALUE, x.v);
3977 }
3978 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
3979   return HandleAttributeStmt(Attr::VOLATILE, x.v);
3980 }
3981 // Handle a statement that sets an attribute on a list of names.
3982 bool DeclarationVisitor::HandleAttributeStmt(
3983     Attr attr, const std::list<parser::Name> &names) {
3984   for (const auto &name : names) {
3985     HandleAttributeStmt(attr, name);
3986   }
3987   return false;
3988 }
3989 Symbol &DeclarationVisitor::HandleAttributeStmt(
3990     Attr attr, const parser::Name &name) {
3991   if (attr == Attr::INTRINSIC) {
3992     if (!IsIntrinsic(name.source, std::nullopt)) {
3993       Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
3994     } else if (currScope().kind() == Scope::Kind::Subprogram ||
3995         currScope().kind() == Scope::Kind::Block) {
3996       if (auto *symbol{FindSymbol(name)}) {
3997         if (symbol->GetUltimate().has<GenericDetails>() &&
3998             symbol->owner() != currScope()) {
3999           // Declaring a name INTRINSIC when there is a generic
4000           // interface of the same name in the host scope.
4001           // Host-associate the generic and mark it INTRINSIC
4002           // rather than completely overriding the generic.
4003           symbol = &MakeHostAssocSymbol(name, *symbol);
4004           symbol->attrs().set(Attr::INTRINSIC);
4005           return *symbol;
4006         }
4007       }
4008     }
4009   }
4010   auto *symbol{FindInScope(name)};
4011   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
4012     // these can be set on a symbol that is host-assoc or use-assoc
4013     if (!symbol &&
4014         (currScope().kind() == Scope::Kind::Subprogram ||
4015             currScope().kind() == Scope::Kind::Block)) {
4016       if (auto *hostSymbol{FindSymbol(name)}) {
4017         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
4018       }
4019     }
4020   } else if (symbol && symbol->has<UseDetails>()) {
4021     Say(currStmtSource().value(),
4022         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
4023         EnumToString(attr), name.source);
4024     return *symbol;
4025   }
4026   if (!symbol) {
4027     symbol = &MakeSymbol(name, EntityDetails{});
4028   }
4029   symbol->attrs().set(attr);
4030   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
4031   return *symbol;
4032 }
4033 // C1107
4034 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
4035   if (currScope().kind() == Scope::Kind::Block) {
4036     Say(MessageFormattedText{
4037         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
4038     return false;
4039   } else {
4040     return true;
4041   }
4042 }
4043 
4044 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
4045   CHECK(objectDeclAttr_);
4046   const auto &name{std::get<parser::ObjectName>(x.t)};
4047   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
4048 }
4049 
4050 // Declare an entity not yet known to be an object or proc.
4051 Symbol &DeclarationVisitor::DeclareUnknownEntity(
4052     const parser::Name &name, Attrs attrs) {
4053   if (!arraySpec().empty() || !coarraySpec().empty()) {
4054     return DeclareObjectEntity(name, attrs);
4055   } else {
4056     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
4057     if (auto *type{GetDeclTypeSpec()}) {
4058       SetType(name, *type);
4059     }
4060     charInfo_.length.reset();
4061     SetBindNameOn(symbol);
4062     if (symbol.attrs().test(Attr::EXTERNAL)) {
4063       ConvertToProcEntity(symbol);
4064     }
4065     return symbol;
4066   }
4067 }
4068 
4069 bool DeclarationVisitor::HasCycle(
4070     const Symbol &procSymbol, const ProcInterface &interface) {
4071   SourceOrderedSymbolSet procsInCycle;
4072   procsInCycle.insert(procSymbol);
4073   const ProcInterface *thisInterface{&interface};
4074   bool haveInterface{true};
4075   while (haveInterface) {
4076     haveInterface = false;
4077     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
4078       if (procsInCycle.count(*interfaceSymbol) > 0) {
4079         for (const auto &procInCycle : procsInCycle) {
4080           Say(procInCycle->name(),
4081               "The interface for procedure '%s' is recursively "
4082               "defined"_err_en_US,
4083               procInCycle->name());
4084           context().SetError(*procInCycle);
4085         }
4086         return true;
4087       } else if (const auto *procDetails{
4088                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
4089         haveInterface = true;
4090         thisInterface = &procDetails->interface();
4091         procsInCycle.insert(*interfaceSymbol);
4092       }
4093     }
4094   }
4095   return false;
4096 }
4097 
4098 Symbol &DeclarationVisitor::DeclareProcEntity(
4099     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
4100   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
4101   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
4102     if (details->IsInterfaceSet()) {
4103       SayWithDecl(name, symbol,
4104           "The interface for procedure '%s' has already been "
4105           "declared"_err_en_US);
4106       context().SetError(symbol);
4107     } else if (HasCycle(symbol, interface)) {
4108       return symbol;
4109     } else if (interface.type()) {
4110       symbol.set(Symbol::Flag::Function);
4111     } else if (interface.symbol()) {
4112       if (interface.symbol()->test(Symbol::Flag::Function)) {
4113         symbol.set(Symbol::Flag::Function);
4114       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
4115         symbol.set(Symbol::Flag::Subroutine);
4116       }
4117     }
4118     details->set_interface(interface);
4119     SetBindNameOn(symbol);
4120     SetPassNameOn(symbol);
4121   }
4122   return symbol;
4123 }
4124 
4125 Symbol &DeclarationVisitor::DeclareObjectEntity(
4126     const parser::Name &name, Attrs attrs) {
4127   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
4128   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
4129     if (auto *type{GetDeclTypeSpec()}) {
4130       SetType(name, *type);
4131     }
4132     if (!arraySpec().empty()) {
4133       if (details->IsArray()) {
4134         if (!context().HasError(symbol)) {
4135           Say(name,
4136               "The dimensions of '%s' have already been declared"_err_en_US);
4137           context().SetError(symbol);
4138         }
4139       } else {
4140         details->set_shape(arraySpec());
4141       }
4142     }
4143     if (!coarraySpec().empty()) {
4144       if (details->IsCoarray()) {
4145         if (!context().HasError(symbol)) {
4146           Say(name,
4147               "The codimensions of '%s' have already been declared"_err_en_US);
4148           context().SetError(symbol);
4149         }
4150       } else {
4151         details->set_coshape(coarraySpec());
4152       }
4153     }
4154     SetBindNameOn(symbol);
4155   }
4156   ClearArraySpec();
4157   ClearCoarraySpec();
4158   charInfo_.length.reset();
4159   return symbol;
4160 }
4161 
4162 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
4163   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
4164 }
4165 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
4166   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
4167 }
4168 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
4169   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
4170 }
4171 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
4172   SetDeclTypeSpec(MakeLogicalType(x.kind));
4173 }
4174 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
4175   if (!charInfo_.length) {
4176     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
4177   }
4178   if (!charInfo_.kind) {
4179     charInfo_.kind =
4180         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
4181   }
4182   SetDeclTypeSpec(currScope().MakeCharacterType(
4183       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
4184   charInfo_ = {};
4185 }
4186 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
4187   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
4188   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
4189   if (intKind &&
4190       !evaluate::IsValidKindOfIntrinsicType(
4191           TypeCategory::Character, *intKind)) { // C715, C719
4192     Say(currStmtSource().value(),
4193         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
4194     charInfo_.kind = std::nullopt; // prevent further errors
4195   }
4196   if (x.length) {
4197     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
4198   }
4199 }
4200 void DeclarationVisitor::Post(const parser::CharLength &x) {
4201   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
4202     charInfo_.length = ParamValue{
4203         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
4204   } else {
4205     charInfo_.length = GetParamValue(
4206         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
4207   }
4208 }
4209 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
4210   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
4211     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
4212   }
4213 }
4214 
4215 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
4216   if (const auto *kind{std::get_if<
4217           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
4218           &x.u)}) {
4219     const parser::Name &name{kind->thing.thing.thing};
4220     if (!FindSymbol(name)) {
4221       Say(name, "Parameter '%s' not found"_err_en_US);
4222     }
4223   }
4224   return false;
4225 }
4226 
4227 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
4228   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
4229   return true;
4230 }
4231 
4232 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
4233   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
4234   if (const Symbol * derivedSymbol{derivedName.symbol}) {
4235     CheckForAbstractType(*derivedSymbol); // C706
4236   }
4237 }
4238 
4239 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
4240   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
4241   return true;
4242 }
4243 
4244 void DeclarationVisitor::Post(
4245     const parser::DeclarationTypeSpec::Class &parsedClass) {
4246   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
4247   if (auto spec{ResolveDerivedType(typeName)};
4248       spec && !IsExtensibleType(&*spec)) { // C705
4249     SayWithDecl(typeName, *typeName.symbol,
4250         "Non-extensible derived type '%s' may not be used with CLASS"
4251         " keyword"_err_en_US);
4252   }
4253 }
4254 
4255 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
4256   const auto &typeName{std::get<parser::Name>(x.t)};
4257   auto spec{ResolveDerivedType(typeName)};
4258   if (!spec) {
4259     return;
4260   }
4261   bool seenAnyName{false};
4262   for (const auto &typeParamSpec :
4263       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
4264     const auto &optKeyword{
4265         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
4266     std::optional<SourceName> name;
4267     if (optKeyword) {
4268       seenAnyName = true;
4269       name = optKeyword->v.source;
4270     } else if (seenAnyName) {
4271       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
4272       continue;
4273     }
4274     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
4275     // The expressions in a derived type specifier whose values define
4276     // non-defaulted type parameters are evaluated (folded) in the enclosing
4277     // scope.  The KIND/LEN distinction is resolved later in
4278     // DerivedTypeSpec::CookParameters().
4279     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
4280     if (!param.isExplicit() || param.GetExplicit()) {
4281       spec->AddRawParamValue(optKeyword, std::move(param));
4282     }
4283   }
4284 
4285   // The DerivedTypeSpec *spec is used initially as a search key.
4286   // If it turns out to have the same name and actual parameter
4287   // value expressions as another DerivedTypeSpec in the current
4288   // scope does, then we'll use that extant spec; otherwise, when this
4289   // spec is distinct from all derived types previously instantiated
4290   // in the current scope, this spec will be moved into that collection.
4291   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
4292   auto category{GetDeclTypeSpecCategory()};
4293   if (dtDetails.isForwardReferenced()) {
4294     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4295     SetDeclTypeSpec(type);
4296     return;
4297   }
4298   // Normalize parameters to produce a better search key.
4299   spec->CookParameters(GetFoldingContext());
4300   if (!spec->MightBeParameterized()) {
4301     spec->EvaluateParameters(context());
4302   }
4303   if (const DeclTypeSpec *
4304       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
4305     // This derived type and parameter expressions (if any) are already present
4306     // in this scope.
4307     SetDeclTypeSpec(*extant);
4308   } else {
4309     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
4310     DerivedTypeSpec &derived{type.derivedTypeSpec()};
4311     if (derived.MightBeParameterized() &&
4312         currScope().IsParameterizedDerivedType()) {
4313       // Defer instantiation; use the derived type's definition's scope.
4314       derived.set_scope(DEREF(spec->typeSymbol().scope()));
4315     } else if (&currScope() == spec->typeSymbol().scope()) {
4316       // Direct recursive use of a type in the definition of one of its
4317       // components: defer instantiation
4318     } else {
4319       auto restorer{
4320           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
4321       derived.Instantiate(currScope());
4322     }
4323     SetDeclTypeSpec(type);
4324   }
4325   // Capture the DerivedTypeSpec in the parse tree for use in building
4326   // structure constructor expressions.
4327   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
4328 }
4329 
4330 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Record &rec) {
4331   const auto &typeName{rec.v};
4332   if (auto spec{ResolveDerivedType(typeName)}) {
4333     spec->CookParameters(GetFoldingContext());
4334     spec->EvaluateParameters(context());
4335     if (const DeclTypeSpec *
4336         extant{currScope().FindInstantiatedDerivedType(
4337             *spec, DeclTypeSpec::TypeDerived)}) {
4338       SetDeclTypeSpec(*extant);
4339     } else {
4340       Say(typeName.source, "%s is not a known STRUCTURE"_err_en_US,
4341           typeName.source);
4342     }
4343   }
4344 }
4345 
4346 // The descendents of DerivedTypeDef in the parse tree are visited directly
4347 // in this Pre() routine so that recursive use of the derived type can be
4348 // supported in the components.
4349 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
4350   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
4351   Walk(stmt);
4352   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
4353   auto &scope{currScope()};
4354   CHECK(scope.symbol());
4355   CHECK(scope.symbol()->scope() == &scope);
4356   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
4357   details.set_isForwardReferenced(false);
4358   std::set<SourceName> paramNames;
4359   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
4360     details.add_paramName(paramName.source);
4361     auto *symbol{FindInScope(scope, paramName)};
4362     if (!symbol) {
4363       Say(paramName,
4364           "No definition found for type parameter '%s'"_err_en_US); // C742
4365       // No symbol for a type param.  Create one and mark it as containing an
4366       // error to improve subsequent semantic processing
4367       BeginAttrs();
4368       Symbol *typeParam{MakeTypeSymbol(
4369           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
4370       context().SetError(*typeParam);
4371       EndAttrs();
4372     } else if (!symbol->has<TypeParamDetails>()) {
4373       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
4374           *symbol, "Definition of '%s'"_en_US); // C741
4375     }
4376     if (!paramNames.insert(paramName.source).second) {
4377       Say(paramName,
4378           "Duplicate type parameter name: '%s'"_err_en_US); // C731
4379     }
4380   }
4381   for (const auto &[name, symbol] : currScope()) {
4382     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
4383       SayDerivedType(name,
4384           "'%s' is not a type parameter of this derived type"_err_en_US,
4385           currScope()); // C741
4386     }
4387   }
4388   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
4389   const auto &componentDefs{
4390       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
4391   Walk(componentDefs);
4392   if (derivedTypeInfo_.sequence) {
4393     details.set_sequence(true);
4394     if (componentDefs.empty()) { // C740
4395       Say(stmt.source,
4396           "A sequence type must have at least one component"_err_en_US);
4397     }
4398     if (!details.paramNames().empty()) { // C740
4399       Say(stmt.source,
4400           "A sequence type may not have type parameters"_err_en_US);
4401     }
4402     if (derivedTypeInfo_.extends) { // C735
4403       Say(stmt.source,
4404           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4405     }
4406   }
4407   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4408   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4409   derivedTypeInfo_ = {};
4410   PopScope();
4411   return false;
4412 }
4413 
4414 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4415   return BeginAttrs();
4416 }
4417 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4418   auto &name{std::get<parser::Name>(x.t)};
4419   // Resolve the EXTENDS() clause before creating the derived
4420   // type's symbol to foil attempts to recursively extend a type.
4421   auto *extendsName{derivedTypeInfo_.extends};
4422   std::optional<DerivedTypeSpec> extendsType{
4423       ResolveExtendsType(name, extendsName)};
4424   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4425   symbol.ReplaceName(name.source);
4426   derivedTypeInfo_.type = &symbol;
4427   PushScope(Scope::Kind::DerivedType, &symbol);
4428   if (extendsType) {
4429     // Declare the "parent component"; private if the type is.
4430     // Any symbol stored in the EXTENDS() clause is temporarily
4431     // hidden so that a new symbol can be created for the parent
4432     // component without producing spurious errors about already
4433     // existing.
4434     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4435     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4436     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4437       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4438       comp.attrs().set(
4439           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4440       comp.set(Symbol::Flag::ParentComp);
4441       DeclTypeSpec &type{currScope().MakeDerivedType(
4442           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4443       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4444       comp.SetType(type);
4445       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4446       details.add_component(comp);
4447     }
4448   }
4449   EndAttrs();
4450 }
4451 
4452 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4453   auto *type{GetDeclTypeSpec()};
4454   auto attr{std::get<common::TypeParamAttr>(x.t)};
4455   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4456     auto &name{std::get<parser::Name>(decl.t)};
4457     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4458       SetType(name, *type);
4459       if (auto &init{
4460               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4461         if (auto maybeExpr{EvaluateNonPointerInitializer(
4462                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4463           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4464             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4465           }
4466         }
4467       }
4468     }
4469   }
4470   EndDecl();
4471 }
4472 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4473   if (derivedTypeInfo_.extends) {
4474     Say(currStmtSource().value(),
4475         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4476   } else {
4477     derivedTypeInfo_.extends = &x.v;
4478   }
4479   return false;
4480 }
4481 
4482 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4483   if (!currScope().parent().IsModule()) {
4484     Say("PRIVATE is only allowed in a derived type that is"
4485         " in a module"_err_en_US); // C766
4486   } else if (derivedTypeInfo_.sawContains) {
4487     derivedTypeInfo_.privateBindings = true;
4488   } else if (!derivedTypeInfo_.privateComps) {
4489     derivedTypeInfo_.privateComps = true;
4490   } else {
4491     Say("PRIVATE may not appear more than once in"
4492         " derived type components"_warn_en_US); // C738
4493   }
4494   return false;
4495 }
4496 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4497   if (derivedTypeInfo_.sequence) {
4498     Say("SEQUENCE may not appear more than once in"
4499         " derived type components"_warn_en_US); // C738
4500   }
4501   derivedTypeInfo_.sequence = true;
4502   return false;
4503 }
4504 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4505   const auto &name{std::get<parser::Name>(x.t)};
4506   auto attrs{GetAttrs()};
4507   if (derivedTypeInfo_.privateComps &&
4508       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4509     attrs.set(Attr::PRIVATE);
4510   }
4511   if (const auto *declType{GetDeclTypeSpec()}) {
4512     if (const auto *derived{declType->AsDerived()}) {
4513       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4514         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4515           Say("Recursive use of the derived type requires "
4516               "POINTER or ALLOCATABLE"_err_en_US);
4517         }
4518       }
4519       // TODO: This would be more appropriate in CheckDerivedType()
4520       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4521         std::string ultimateName{it.BuildResultDesignatorName()};
4522         // Strip off the leading "%"
4523         if (ultimateName.length() > 1) {
4524           ultimateName.erase(0, 1);
4525           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4526             evaluate::AttachDeclaration(
4527                 Say(name.source,
4528                     "A component with a POINTER or ALLOCATABLE attribute may "
4529                     "not "
4530                     "be of a type with a coarray ultimate component (named "
4531                     "'%s')"_err_en_US,
4532                     ultimateName),
4533                 derived->typeSymbol());
4534           }
4535           if (!arraySpec().empty() || !coarraySpec().empty()) {
4536             evaluate::AttachDeclaration(
4537                 Say(name.source,
4538                     "An array or coarray component may not be of a type with a "
4539                     "coarray ultimate component (named '%s')"_err_en_US,
4540                     ultimateName),
4541                 derived->typeSymbol());
4542           }
4543         }
4544       }
4545     }
4546   }
4547   if (OkToAddComponent(name)) {
4548     auto &symbol{DeclareObjectEntity(name, attrs)};
4549     if (symbol.has<ObjectEntityDetails>()) {
4550       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4551         Initialization(name, *init, true);
4552       }
4553     }
4554     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4555   }
4556   ClearArraySpec();
4557   ClearCoarraySpec();
4558 }
4559 void DeclarationVisitor::Post(const parser::FillDecl &x) {
4560   // Replace "%FILL" with a distinct generated name
4561   const auto &name{std::get<parser::Name>(x.t)};
4562   const_cast<SourceName &>(name.source) = context().GetTempName(currScope());
4563   if (OkToAddComponent(name)) {
4564     auto &symbol{DeclareObjectEntity(name, GetAttrs())};
4565     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4566   }
4567   ClearArraySpec();
4568 }
4569 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4570   CHECK(!interfaceName_);
4571   return BeginDecl();
4572 }
4573 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4574   interfaceName_ = nullptr;
4575   EndDecl();
4576 }
4577 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4578   // Overrides parse tree traversal so as to handle attributes first,
4579   // so POINTER & ALLOCATABLE enable forward references to derived types.
4580   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4581   set_allowForwardReferenceToDerivedType(
4582       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4583   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4584   set_allowForwardReferenceToDerivedType(false);
4585   if (derivedTypeInfo_.sequence) { // C740
4586     if (const auto *declType{GetDeclTypeSpec()}) {
4587       if (!declType->AsIntrinsic() && !declType->IsSequenceType()) {
4588         if (GetAttrs().test(Attr::POINTER) &&
4589             context().IsEnabled(common::LanguageFeature::PointerInSeqType)) {
4590           if (context().ShouldWarn(common::LanguageFeature::PointerInSeqType)) {
4591             Say("A sequence type data component that is a pointer to a non-sequence type is not standard"_port_en_US);
4592           }
4593         } else {
4594           Say("A sequence type data component must either be of an intrinsic type or a derived sequence type"_err_en_US);
4595         }
4596       }
4597     }
4598   }
4599   Walk(std::get<std::list<parser::ComponentOrFill>>(x.t));
4600   return false;
4601 }
4602 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4603   CHECK(!interfaceName_);
4604   return true;
4605 }
4606 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4607   interfaceName_ = nullptr;
4608 }
4609 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4610   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4611     return !NameIsKnownOrIntrinsic(*name);
4612   }
4613   return true;
4614 }
4615 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4616   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4617     interfaceName_ = name;
4618     NoteInterfaceName(*name);
4619   }
4620 }
4621 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4622   const auto &name{std::get<parser::Name>(x.t)};
4623   ProcInterface interface;
4624   if (interfaceName_) {
4625     interface.set_symbol(*interfaceName_->symbol);
4626   } else if (auto *type{GetDeclTypeSpec()}) {
4627     interface.set_type(*type);
4628   }
4629   auto attrs{HandleSaveName(name.source, GetAttrs())};
4630   DerivedTypeDetails *dtDetails{nullptr};
4631   if (Symbol * symbol{currScope().symbol()}) {
4632     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4633   }
4634   if (!dtDetails) {
4635     attrs.set(Attr::EXTERNAL);
4636   }
4637   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4638   symbol.ReplaceName(name.source);
4639   if (dtDetails) {
4640     dtDetails->add_component(symbol);
4641   }
4642 }
4643 
4644 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4645   derivedTypeInfo_.sawContains = true;
4646   return true;
4647 }
4648 
4649 // Resolve binding names from type-bound generics, saved in genericBindings_.
4650 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4651   // track specifics seen for the current generic to detect duplicates:
4652   const Symbol *currGeneric{nullptr};
4653   std::set<SourceName> specifics;
4654   for (const auto &[generic, bindingName] : genericBindings_) {
4655     if (generic != currGeneric) {
4656       currGeneric = generic;
4657       specifics.clear();
4658     }
4659     auto [it, inserted]{specifics.insert(bindingName->source)};
4660     if (!inserted) {
4661       Say(*bindingName, // C773
4662           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4663           bindingName->source, generic->name())
4664           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4665       continue;
4666     }
4667     auto *symbol{FindInTypeOrParents(*bindingName)};
4668     if (!symbol) {
4669       Say(*bindingName, // C772
4670           "Binding name '%s' not found in this derived type"_err_en_US);
4671     } else if (!symbol->has<ProcBindingDetails>()) {
4672       SayWithDecl(*bindingName, *symbol, // C772
4673           "'%s' is not the name of a specific binding of this type"_err_en_US);
4674     } else {
4675       generic->get<GenericDetails>().AddSpecificProc(
4676           *symbol, bindingName->source);
4677     }
4678   }
4679   genericBindings_.clear();
4680 }
4681 
4682 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4683   if (derivedTypeInfo_.sequence) {
4684     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4685   }
4686 }
4687 
4688 void DeclarationVisitor::Post(
4689     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4690   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4691     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4692   }
4693   for (auto &declaration : x.declarations) {
4694     auto &bindingName{std::get<parser::Name>(declaration.t)};
4695     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4696     const parser::Name &procedureName{optName ? *optName : bindingName};
4697     Symbol *procedure{FindSymbol(procedureName)};
4698     if (!procedure) {
4699       procedure = NoteInterfaceName(procedureName);
4700     }
4701     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4702       SetPassNameOn(*s);
4703       if (GetAttrs().test(Attr::DEFERRED)) {
4704         context().SetError(*s);
4705       }
4706     }
4707   }
4708 }
4709 
4710 void DeclarationVisitor::CheckBindings(
4711     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4712   CHECK(currScope().IsDerivedType());
4713   for (auto &declaration : tbps.declarations) {
4714     auto &bindingName{std::get<parser::Name>(declaration.t)};
4715     if (Symbol * binding{FindInScope(bindingName)}) {
4716       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4717         const Symbol *procedure{FindSubprogram(details->symbol())};
4718         if (!CanBeTypeBoundProc(procedure)) {
4719           if (details->symbol().name() != binding->name()) {
4720             Say(binding->name(),
4721                 "The binding of '%s' ('%s') must be either an accessible "
4722                 "module procedure or an external procedure with "
4723                 "an explicit interface"_err_en_US,
4724                 binding->name(), details->symbol().name());
4725           } else {
4726             Say(binding->name(),
4727                 "'%s' must be either an accessible module procedure "
4728                 "or an external procedure with an explicit interface"_err_en_US,
4729                 binding->name());
4730           }
4731           context().SetError(*binding);
4732         }
4733       }
4734     }
4735   }
4736 }
4737 
4738 void DeclarationVisitor::Post(
4739     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4740   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4741     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4742   }
4743   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4744     for (auto &bindingName : x.bindingNames) {
4745       if (auto *s{
4746               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4747         SetPassNameOn(*s);
4748         if (!GetAttrs().test(Attr::DEFERRED)) {
4749           context().SetError(*s);
4750         }
4751       }
4752     }
4753   }
4754 }
4755 
4756 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4757   if (currScope().IsDerivedType() && currScope().symbol()) {
4758     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4759       for (const auto &subrName : x.v) {
4760         if (const auto *name{ResolveName(subrName)}) {
4761           auto pair{
4762               details->finals().emplace(name->source, DEREF(name->symbol))};
4763           if (!pair.second) { // C787
4764             Say(name->source,
4765                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4766                 name->source)
4767                 .Attach(pair.first->first,
4768                     "earlier appearance of this FINAL subroutine"_en_US);
4769           }
4770         }
4771       }
4772     }
4773   }
4774 }
4775 
4776 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4777   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4778   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4779   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4780   auto info{GenericSpecInfo{genericSpec.value()}};
4781   SourceName symbolName{info.symbolName()};
4782   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4783                             : derivedTypeInfo_.privateBindings};
4784   auto *genericSymbol{FindInScope(symbolName)};
4785   if (genericSymbol) {
4786     if (!genericSymbol->has<GenericDetails>()) {
4787       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4788     }
4789   } else {
4790     // look in parent types:
4791     Symbol *inheritedSymbol{nullptr};
4792     for (const auto &name : GetAllNames(context(), symbolName)) {
4793       inheritedSymbol = currScope().FindComponent(SourceName{name});
4794       if (inheritedSymbol) {
4795         break;
4796       }
4797     }
4798     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4799       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4800     }
4801   }
4802   if (genericSymbol) {
4803     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4804   } else {
4805     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4806     if (!genericSymbol) {
4807       return false;
4808     }
4809     if (isPrivate) {
4810       genericSymbol->attrs().set(Attr::PRIVATE);
4811     }
4812   }
4813   for (const parser::Name &bindingName : bindingNames) {
4814     genericBindings_.emplace(genericSymbol, &bindingName);
4815   }
4816   info.Resolve(genericSymbol);
4817   return false;
4818 }
4819 
4820 // DEC STRUCTUREs are handled thus to allow for nested definitions.
4821 bool DeclarationVisitor::Pre(const parser::StructureDef &def) {
4822   const auto &structureStatement{
4823       std::get<parser::Statement<parser::StructureStmt>>(def.t)};
4824   auto saveDerivedTypeInfo{derivedTypeInfo_};
4825   derivedTypeInfo_ = {};
4826   derivedTypeInfo_.isStructure = true;
4827   derivedTypeInfo_.sequence = true;
4828   Scope *previousStructure{nullptr};
4829   if (saveDerivedTypeInfo.isStructure) {
4830     previousStructure = &currScope();
4831     PopScope();
4832   }
4833   const parser::StructureStmt &structStmt{structureStatement.statement};
4834   const auto &name{std::get<std::optional<parser::Name>>(structStmt.t)};
4835   if (!name) {
4836     // Construct a distinct generated name for an anonymous structure
4837     auto &mutableName{const_cast<std::optional<parser::Name> &>(name)};
4838     mutableName.emplace(
4839         parser::Name{context().GetTempName(currScope()), nullptr});
4840   }
4841   auto &symbol{MakeSymbol(*name, DerivedTypeDetails{})};
4842   symbol.ReplaceName(name->source);
4843   symbol.get<DerivedTypeDetails>().set_sequence(true);
4844   symbol.get<DerivedTypeDetails>().set_isDECStructure(true);
4845   derivedTypeInfo_.type = &symbol;
4846   PushScope(Scope::Kind::DerivedType, &symbol);
4847   const auto &fields{std::get<std::list<parser::StructureField>>(def.t)};
4848   Walk(fields);
4849   PopScope();
4850   // Complete the definition
4851   DerivedTypeSpec derivedTypeSpec{symbol.name(), symbol};
4852   derivedTypeSpec.set_scope(DEREF(symbol.scope()));
4853   derivedTypeSpec.CookParameters(GetFoldingContext());
4854   derivedTypeSpec.EvaluateParameters(context());
4855   DeclTypeSpec &type{currScope().MakeDerivedType(
4856       DeclTypeSpec::TypeDerived, std::move(derivedTypeSpec))};
4857   type.derivedTypeSpec().Instantiate(currScope());
4858   // Restore previous structure definition context, if any
4859   derivedTypeInfo_ = saveDerivedTypeInfo;
4860   if (previousStructure) {
4861     PushScope(*previousStructure);
4862   }
4863   // Handle any entity declarations on the STRUCTURE statement
4864   const auto &decls{std::get<std::list<parser::EntityDecl>>(structStmt.t)};
4865   if (!decls.empty()) {
4866     BeginDecl();
4867     SetDeclTypeSpec(type);
4868     Walk(decls);
4869     EndDecl();
4870   }
4871   return false;
4872 }
4873 
4874 bool DeclarationVisitor::Pre(const parser::Union::UnionStmt &) {
4875   Say("not yet implemented: support for UNION"_err_en_US); // TODO
4876   return true;
4877 }
4878 
4879 bool DeclarationVisitor::Pre(const parser::StructureField &x) {
4880   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4881           x.u)) {
4882     BeginDecl();
4883   }
4884   return true;
4885 }
4886 
4887 void DeclarationVisitor::Post(const parser::StructureField &x) {
4888   if (std::holds_alternative<parser::Statement<parser::DataComponentDefStmt>>(
4889           x.u)) {
4890     EndDecl();
4891   }
4892 }
4893 
4894 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4895   BeginDeclTypeSpec();
4896   return true;
4897 }
4898 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4899   EndDeclTypeSpec();
4900 }
4901 
4902 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4903   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4904   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4905   if (!type) {
4906     return false;
4907   }
4908   const DerivedTypeSpec *spec{type->AsDerived()};
4909   const Scope *typeScope{spec ? spec->scope() : nullptr};
4910   if (!typeScope) {
4911     return false;
4912   }
4913 
4914   // N.B C7102 is implicitly enforced by having inaccessible types not
4915   // being found in resolution.
4916   // More constraints are enforced in expression.cpp so that they
4917   // can apply to structure constructors that have been converted
4918   // from misparsed function references.
4919   for (const auto &component :
4920       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4921     // Visit the component spec expression, but not the keyword, since
4922     // we need to resolve its symbol in the scope of the derived type.
4923     Walk(std::get<parser::ComponentDataSource>(component.t));
4924     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4925       FindInTypeOrParents(*typeScope, kw->v);
4926     }
4927   }
4928   return false;
4929 }
4930 
4931 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4932   for (const parser::BasedPointer &bp : x.v) {
4933     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4934     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4935     auto *pointer{FindSymbol(pointerName)};
4936     if (!pointer) {
4937       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4938     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4939       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4940     } else if (pointer->Rank() > 0) {
4941       SayWithDecl(pointerName, *pointer,
4942           "Cray pointer '%s' must be a scalar"_err_en_US);
4943     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4944       Say(pointerName,
4945           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4946     }
4947     pointer->set(Symbol::Flag::CrayPointer);
4948     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4949         context().defaultKinds().subscriptIntegerKind())};
4950     const auto *type{pointer->GetType()};
4951     if (!type) {
4952       pointer->SetType(pointerType);
4953     } else if (*type != pointerType) {
4954       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4955           pointerName.source, pointerType.AsFortran());
4956     }
4957     if (ResolveName(pointeeName)) {
4958       Symbol &pointee{*pointeeName.symbol};
4959       if (pointee.has<UseDetails>()) {
4960         Say(pointeeName,
4961             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4962         continue;
4963       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4964         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4965         continue;
4966       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4967         Say(pointeeName,
4968             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4969       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4970         Say(pointeeName,
4971             "'%s' was already declared as a Cray pointee"_err_en_US);
4972       } else {
4973         pointee.set(Symbol::Flag::CrayPointee);
4974       }
4975       if (const auto *pointeeType{pointee.GetType()}) {
4976         if (const auto *derived{pointeeType->AsDerived()}) {
4977           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
4978             Say(pointeeName,
4979                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
4980           }
4981         }
4982       }
4983       // process the pointee array-spec, if present
4984       BeginArraySpec();
4985       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
4986       const auto &spec{arraySpec()};
4987       if (!spec.empty()) {
4988         auto &details{pointee.get<ObjectEntityDetails>()};
4989         if (details.shape().empty()) {
4990           details.set_shape(spec);
4991         } else {
4992           SayWithDecl(pointeeName, pointee,
4993               "Array spec was already declared for '%s'"_err_en_US);
4994         }
4995       }
4996       ClearArraySpec();
4997       currScope().add_crayPointer(pointeeName.source, *pointer);
4998     }
4999   }
5000   return false;
5001 }
5002 
5003 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
5004   if (!CheckNotInBlock("NAMELIST")) { // C1107
5005     return false;
5006   }
5007   const auto &groupName{std::get<parser::Name>(x.t)};
5008   auto *groupSymbol{FindInScope(groupName)};
5009   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
5010     groupSymbol = &MakeSymbol(groupName, NamelistDetails{});
5011     groupSymbol->ReplaceName(groupName.source);
5012   }
5013   // Name resolution of group items is deferred to FinishNamelists()
5014   // so that host association is handled correctly.
5015   GetDeferredDeclarationState(true)->namelistGroups.emplace_back(&x);
5016   return false;
5017 }
5018 
5019 void DeclarationVisitor::FinishNamelists() {
5020   if (auto *deferred{GetDeferredDeclarationState()}) {
5021     for (const parser::NamelistStmt::Group *group : deferred->namelistGroups) {
5022       if (auto *groupSymbol{FindInScope(std::get<parser::Name>(group->t))}) {
5023         if (auto *details{groupSymbol->detailsIf<NamelistDetails>()}) {
5024           for (const auto &name : std::get<std::list<parser::Name>>(group->t)) {
5025             auto *symbol{FindSymbol(name)};
5026             if (!symbol) {
5027               symbol = &MakeSymbol(name, ObjectEntityDetails{});
5028               ApplyImplicitRules(*symbol);
5029             } else if (!ConvertToObjectEntity(*symbol)) {
5030               SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
5031             }
5032             symbol->GetUltimate().set(Symbol::Flag::InNamelist);
5033             details->add_object(*symbol);
5034           }
5035         }
5036       }
5037     }
5038     deferred->namelistGroups.clear();
5039   }
5040 }
5041 
5042 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
5043   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
5044     auto *symbol{FindSymbol(*name)};
5045     if (!symbol) {
5046       Say(*name, "Namelist group '%s' not found"_err_en_US);
5047     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
5048       SayWithDecl(
5049           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
5050     }
5051   }
5052   return true;
5053 }
5054 
5055 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
5056   CheckNotInBlock("COMMON"); // C1107
5057   return true;
5058 }
5059 
5060 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
5061   BeginArraySpec();
5062   return true;
5063 }
5064 
5065 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
5066   const auto &name{std::get<parser::Name>(x.t)};
5067   DeclareObjectEntity(name);
5068   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
5069   if (!pair.second) {
5070     const SourceName &prev{*pair.first};
5071     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
5072         "Previous occurrence of '%s' in a COMMON block"_en_US);
5073   }
5074 }
5075 
5076 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
5077   // save equivalence sets to be processed after specification part
5078   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
5079     for (const std::list<parser::EquivalenceObject> &set : x.v) {
5080       specPartState_.equivalenceSets.push_back(&set);
5081     }
5082   }
5083   return false; // don't implicitly declare names yet
5084 }
5085 
5086 void DeclarationVisitor::CheckEquivalenceSets() {
5087   EquivalenceSets equivSets{context()};
5088   inEquivalenceStmt_ = true;
5089   for (const auto *set : specPartState_.equivalenceSets) {
5090     const auto &source{set->front().v.value().source};
5091     if (set->size() <= 1) { // R871
5092       Say(source, "Equivalence set must have more than one object"_err_en_US);
5093     }
5094     for (const parser::EquivalenceObject &object : *set) {
5095       const auto &designator{object.v.value()};
5096       // The designator was not resolved when it was encountered so do it now.
5097       // AnalyzeExpr causes array sections to be changed to substrings as needed
5098       Walk(designator);
5099       if (AnalyzeExpr(context(), designator)) {
5100         equivSets.AddToSet(designator);
5101       }
5102     }
5103     equivSets.FinishSet(source);
5104   }
5105   inEquivalenceStmt_ = false;
5106   for (auto &set : equivSets.sets()) {
5107     if (!set.empty()) {
5108       currScope().add_equivalenceSet(std::move(set));
5109     }
5110   }
5111   specPartState_.equivalenceSets.clear();
5112 }
5113 
5114 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
5115   if (x.v.empty()) {
5116     specPartState_.saveInfo.saveAll = currStmtSource();
5117     currScope().set_hasSAVE();
5118   } else {
5119     for (const parser::SavedEntity &y : x.v) {
5120       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
5121       const auto &name{std::get<parser::Name>(y.t)};
5122       if (kind == parser::SavedEntity::Kind::Common) {
5123         MakeCommonBlockSymbol(name);
5124         AddSaveName(specPartState_.saveInfo.commons, name.source);
5125       } else {
5126         HandleAttributeStmt(Attr::SAVE, name);
5127       }
5128     }
5129   }
5130   return false;
5131 }
5132 
5133 void DeclarationVisitor::CheckSaveStmts() {
5134   for (const SourceName &name : specPartState_.saveInfo.entities) {
5135     auto *symbol{FindInScope(name)};
5136     if (!symbol) {
5137       // error was reported
5138     } else if (specPartState_.saveInfo.saveAll) {
5139       // C889 - note that pgi, ifort, xlf do not enforce this constraint
5140       Say2(name,
5141           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
5142           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
5143     } else if (auto msg{CheckSaveAttr(*symbol)}) {
5144       Say(name, std::move(*msg));
5145       context().SetError(*symbol);
5146     } else {
5147       SetSaveAttr(*symbol);
5148     }
5149   }
5150   for (const SourceName &name : specPartState_.saveInfo.commons) {
5151     if (auto *symbol{currScope().FindCommonBlock(name)}) {
5152       auto &objects{symbol->get<CommonBlockDetails>().objects()};
5153       if (objects.empty()) {
5154         if (currScope().kind() != Scope::Kind::Block) {
5155           Say(name,
5156               "'%s' appears as a COMMON block in a SAVE statement but not in"
5157               " a COMMON statement"_err_en_US);
5158         } else { // C1108
5159           Say(name,
5160               "SAVE statement in BLOCK construct may not contain a"
5161               " common block name '%s'"_err_en_US);
5162         }
5163       } else {
5164         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
5165           SetSaveAttr(*object);
5166         }
5167       }
5168     }
5169   }
5170   if (specPartState_.saveInfo.saveAll) {
5171     // Apply SAVE attribute to applicable symbols
5172     for (auto pair : currScope()) {
5173       auto &symbol{*pair.second};
5174       if (!CheckSaveAttr(symbol)) {
5175         SetSaveAttr(symbol);
5176       }
5177     }
5178   }
5179   specPartState_.saveInfo = {};
5180 }
5181 
5182 // If SAVE attribute can't be set on symbol, return error message.
5183 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
5184     const Symbol &symbol) {
5185   if (IsDummy(symbol)) {
5186     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
5187   } else if (symbol.IsFuncResult()) {
5188     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
5189   } else if (symbol.has<ProcEntityDetails>() &&
5190       !symbol.attrs().test(Attr::POINTER)) {
5191     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
5192   } else if (IsAutomatic(symbol)) {
5193     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
5194   } else {
5195     return std::nullopt;
5196   }
5197 }
5198 
5199 // Record SAVEd names in specPartState_.saveInfo.entities.
5200 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
5201   if (attrs.test(Attr::SAVE)) {
5202     AddSaveName(specPartState_.saveInfo.entities, name);
5203   }
5204   return attrs;
5205 }
5206 
5207 // Record a name in a set of those to be saved.
5208 void DeclarationVisitor::AddSaveName(
5209     std::set<SourceName> &set, const SourceName &name) {
5210   auto pair{set.insert(name)};
5211   if (!pair.second) {
5212     Say2(name, "SAVE attribute was already specified on '%s'"_warn_en_US,
5213         *pair.first, "Previous specification of SAVE attribute"_en_US);
5214   }
5215 }
5216 
5217 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
5218 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
5219   if (!IsSaved(symbol)) {
5220     symbol.attrs().set(Attr::SAVE);
5221   }
5222 }
5223 
5224 // Check types of common block objects, now that they are known.
5225 void DeclarationVisitor::CheckCommonBlocks() {
5226   // check for empty common blocks
5227   for (const auto &pair : currScope().commonBlocks()) {
5228     const auto &symbol{*pair.second};
5229     if (symbol.get<CommonBlockDetails>().objects().empty() &&
5230         symbol.attrs().test(Attr::BIND_C)) {
5231       Say(symbol.name(),
5232           "'%s' appears as a COMMON block in a BIND statement but not in"
5233           " a COMMON statement"_err_en_US);
5234     }
5235   }
5236   // check objects in common blocks
5237   for (const auto &name : specPartState_.commonBlockObjects) {
5238     const auto *symbol{currScope().FindSymbol(name)};
5239     if (!symbol) {
5240       continue;
5241     }
5242     const auto &attrs{symbol->attrs()};
5243     if (attrs.test(Attr::ALLOCATABLE)) {
5244       Say(name,
5245           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
5246     } else if (attrs.test(Attr::BIND_C)) {
5247       Say(name,
5248           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
5249     } else if (IsDummy(*symbol)) {
5250       Say(name,
5251           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
5252     } else if (symbol->IsFuncResult()) {
5253       Say(name,
5254           "Function result '%s' may not appear in a COMMON block"_err_en_US);
5255     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
5256       if (type->category() == DeclTypeSpec::ClassStar) {
5257         Say(name,
5258             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
5259       } else if (const auto *derived{type->AsDerived()}) {
5260         auto &typeSymbol{derived->typeSymbol()};
5261         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
5262             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
5263           Say(name,
5264               "Derived type '%s' in COMMON block must have the BIND or"
5265               " SEQUENCE attribute"_err_en_US);
5266         }
5267         CheckCommonBlockDerivedType(name, typeSymbol);
5268       }
5269     }
5270   }
5271   specPartState_.commonBlockObjects = {};
5272 }
5273 
5274 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
5275   return Resolve(name, currScope().MakeCommonBlock(name.source));
5276 }
5277 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
5278     const std::optional<parser::Name> &name) {
5279   if (name) {
5280     return MakeCommonBlockSymbol(*name);
5281   } else {
5282     return MakeCommonBlockSymbol(parser::Name{});
5283   }
5284 }
5285 
5286 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
5287   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
5288 }
5289 
5290 // Check if this derived type can be in a COMMON block.
5291 void DeclarationVisitor::CheckCommonBlockDerivedType(
5292     const SourceName &name, const Symbol &typeSymbol) {
5293   if (const auto *scope{typeSymbol.scope()}) {
5294     for (const auto &pair : *scope) {
5295       const Symbol &component{*pair.second};
5296       if (component.attrs().test(Attr::ALLOCATABLE)) {
5297         Say2(name,
5298             "Derived type variable '%s' may not appear in a COMMON block"
5299             " due to ALLOCATABLE component"_err_en_US,
5300             component.name(), "Component with ALLOCATABLE attribute"_en_US);
5301         return;
5302       }
5303       const auto *details{component.detailsIf<ObjectEntityDetails>()};
5304       if (component.test(Symbol::Flag::InDataStmt) ||
5305           (details && details->init())) {
5306         Say2(name,
5307             "Derived type variable '%s' may not appear in a COMMON block due to component with default initialization"_err_en_US,
5308             component.name(), "Component with default initialization"_en_US);
5309         return;
5310       }
5311       if (details) {
5312         if (const auto *type{details->type()}) {
5313           if (const auto *derived{type->AsDerived()}) {
5314             CheckCommonBlockDerivedType(name, derived->typeSymbol());
5315           }
5316         }
5317       }
5318     }
5319   }
5320 }
5321 
5322 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
5323     const parser::Name &name) {
5324   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
5325           name.source.ToString())}) {
5326     // Unrestricted specific intrinsic function names (e.g., "cos")
5327     // are acceptable as procedure interfaces.  The presence of the
5328     // INTRINSIC flag will cause this symbol to have a complete interface
5329     // recreated for it later on demand, but capturing its result type here
5330     // will make GetType() return a correct result without having to
5331     // probe the intrinsics table again.
5332     Symbol &symbol{
5333         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
5334     CHECK(interface->functionResult.has_value());
5335     evaluate::DynamicType dyType{
5336         DEREF(interface->functionResult->GetTypeAndShape()).type()};
5337     CHECK(common::IsNumericTypeCategory(dyType.category()));
5338     const DeclTypeSpec &typeSpec{
5339         MakeNumericType(dyType.category(), dyType.kind())};
5340     ProcEntityDetails details;
5341     ProcInterface procInterface;
5342     procInterface.set_type(typeSpec);
5343     details.set_interface(procInterface);
5344     symbol.set_details(std::move(details));
5345     symbol.set(Symbol::Flag::Function);
5346     if (interface->IsElemental()) {
5347       symbol.attrs().set(Attr::ELEMENTAL);
5348     }
5349     if (interface->IsPure()) {
5350       symbol.attrs().set(Attr::PURE);
5351     }
5352     Resolve(name, symbol);
5353     return true;
5354   } else {
5355     return false;
5356   }
5357 }
5358 
5359 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
5360 bool DeclarationVisitor::PassesSharedLocalityChecks(
5361     const parser::Name &name, Symbol &symbol) {
5362   if (!IsVariableName(symbol)) {
5363     SayLocalMustBeVariable(name, symbol); // C1124
5364     return false;
5365   }
5366   if (symbol.owner() == currScope()) { // C1125 and C1126
5367     SayAlreadyDeclared(name, symbol);
5368     return false;
5369   }
5370   return true;
5371 }
5372 
5373 // Checks for locality-specs LOCAL and LOCAL_INIT
5374 bool DeclarationVisitor::PassesLocalityChecks(
5375     const parser::Name &name, Symbol &symbol) {
5376   if (IsAllocatable(symbol)) { // C1128
5377     SayWithDecl(name, symbol,
5378         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
5379     return false;
5380   }
5381   if (IsOptional(symbol)) { // C1128
5382     SayWithDecl(name, symbol,
5383         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
5384     return false;
5385   }
5386   if (IsIntentIn(symbol)) { // C1128
5387     SayWithDecl(name, symbol,
5388         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
5389     return false;
5390   }
5391   if (IsFinalizable(symbol)) { // C1128
5392     SayWithDecl(name, symbol,
5393         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
5394     return false;
5395   }
5396   if (evaluate::IsCoarray(symbol)) { // C1128
5397     SayWithDecl(
5398         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
5399     return false;
5400   }
5401   if (const DeclTypeSpec * type{symbol.GetType()}) {
5402     if (type->IsPolymorphic() && IsDummy(symbol) &&
5403         !IsPointer(symbol)) { // C1128
5404       SayWithDecl(name, symbol,
5405           "Nonpointer polymorphic argument '%s' not allowed in a "
5406           "locality-spec"_err_en_US);
5407       return false;
5408     }
5409   }
5410   if (IsAssumedSizeArray(symbol)) { // C1128
5411     SayWithDecl(name, symbol,
5412         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
5413     return false;
5414   }
5415   if (std::optional<Message> msg{WhyNotModifiable(symbol, currScope())}) {
5416     SayWithReason(name, symbol,
5417         "'%s' may not appear in a locality-spec because it is not "
5418         "definable"_err_en_US,
5419         std::move(*msg));
5420     return false;
5421   }
5422   return PassesSharedLocalityChecks(name, symbol);
5423 }
5424 
5425 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
5426     const parser::Name &name) {
5427   Symbol *prev{FindSymbol(name)};
5428   if (!prev) {
5429     // Declare the name as an object in the enclosing scope so that
5430     // the name can't be repurposed there later as something else.
5431     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5432     ConvertToObjectEntity(*prev);
5433     ApplyImplicitRules(*prev);
5434   }
5435   return *prev;
5436 }
5437 
5438 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
5439   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5440   if (!PassesLocalityChecks(name, prev)) {
5441     return nullptr;
5442   }
5443   return &MakeHostAssocSymbol(name, prev);
5444 }
5445 
5446 Symbol *DeclarationVisitor::DeclareStatementEntity(
5447     const parser::DoVariable &doVar,
5448     const std::optional<parser::IntegerTypeSpec> &type) {
5449   const parser::Name &name{doVar.thing.thing};
5450   const DeclTypeSpec *declTypeSpec{nullptr};
5451   if (auto *prev{FindSymbol(name)}) {
5452     if (prev->owner() == currScope()) {
5453       SayAlreadyDeclared(name, *prev);
5454       return nullptr;
5455     }
5456     name.symbol = nullptr;
5457     declTypeSpec = prev->GetType();
5458   }
5459   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
5460   if (!symbol.has<ObjectEntityDetails>()) {
5461     return nullptr; // error was reported in DeclareEntity
5462   }
5463   if (type) {
5464     declTypeSpec = ProcessTypeSpec(*type);
5465   }
5466   if (declTypeSpec) {
5467     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
5468     // declaration of this implied DO loop control variable.
5469     auto restorer{
5470         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
5471     SetType(name, *declTypeSpec);
5472   } else {
5473     ApplyImplicitRules(symbol);
5474   }
5475   Symbol *result{Resolve(name, &symbol)};
5476   AnalyzeExpr(context(), doVar); // enforce INTEGER type
5477   return result;
5478 }
5479 
5480 // Set the type of an entity or report an error.
5481 void DeclarationVisitor::SetType(
5482     const parser::Name &name, const DeclTypeSpec &type) {
5483   CHECK(name.symbol);
5484   auto &symbol{*name.symbol};
5485   if (charInfo_.length) { // Declaration has "*length" (R723)
5486     auto length{std::move(*charInfo_.length)};
5487     charInfo_.length.reset();
5488     if (type.category() == DeclTypeSpec::Character) {
5489       auto kind{type.characterTypeSpec().kind()};
5490       // Recurse with correct type.
5491       SetType(name,
5492           currScope().MakeCharacterType(std::move(length), std::move(kind)));
5493       return;
5494     } else { // C753
5495       Say(name,
5496           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
5497     }
5498   }
5499   auto *prevType{symbol.GetType()};
5500   if (!prevType) {
5501     symbol.SetType(type);
5502   } else if (symbol.has<UseDetails>()) {
5503     // error recovery case, redeclaration of use-associated name
5504   } else if (HadForwardRef(symbol)) {
5505     // error recovery after use of host-associated name
5506   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5507     SayWithDecl(
5508         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5509     context().SetError(symbol);
5510   } else if (type != *prevType) {
5511     SayWithDecl(name, symbol,
5512         "The type of '%s' has already been implicitly declared"_err_en_US);
5513     context().SetError(symbol);
5514   } else {
5515     symbol.set(Symbol::Flag::Implicit, false);
5516   }
5517 }
5518 
5519 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5520     const parser::Name &name) {
5521   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5522   if (!symbol || symbol->has<UnknownDetails>()) {
5523     if (allowForwardReferenceToDerivedType()) {
5524       if (!symbol) {
5525         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5526         Resolve(name, *symbol);
5527       };
5528       DerivedTypeDetails details;
5529       details.set_isForwardReferenced(true);
5530       symbol->set_details(std::move(details));
5531     } else { // C732
5532       Say(name, "Derived type '%s' not found"_err_en_US);
5533       return std::nullopt;
5534     }
5535   }
5536   if (CheckUseError(name)) {
5537     return std::nullopt;
5538   }
5539   symbol = &symbol->GetUltimate();
5540   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
5541     if (details->derivedType()) {
5542       symbol = &details->derivedType()->GetUltimate();
5543     }
5544   }
5545   if (symbol->has<DerivedTypeDetails>()) {
5546     return DerivedTypeSpec{name.source, *symbol};
5547   } else {
5548     Say(name, "'%s' is not a derived type"_err_en_US);
5549     return std::nullopt;
5550   }
5551 }
5552 
5553 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5554     const parser::Name &typeName, const parser::Name *extendsName) {
5555   if (!extendsName) {
5556     return std::nullopt;
5557   } else if (typeName.source == extendsName->source) {
5558     Say(extendsName->source,
5559         "Derived type '%s' cannot extend itself"_err_en_US);
5560     return std::nullopt;
5561   } else {
5562     return ResolveDerivedType(*extendsName);
5563   }
5564 }
5565 
5566 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5567   // The symbol is checked later by CheckExplicitInterface() and
5568   // CheckBindings().  It can be a forward reference.
5569   if (!NameIsKnownOrIntrinsic(name)) {
5570     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5571     Resolve(name, symbol);
5572   }
5573   return name.symbol;
5574 }
5575 
5576 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5577   if (const Symbol * symbol{name.symbol}) {
5578     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5579       Say(name,
5580           "'%s' must be an abstract interface or a procedure with "
5581           "an explicit interface"_err_en_US,
5582           symbol->name());
5583     }
5584   }
5585 }
5586 
5587 // Create a symbol for a type parameter, component, or procedure binding in
5588 // the current derived type scope. Return false on error.
5589 Symbol *DeclarationVisitor::MakeTypeSymbol(
5590     const parser::Name &name, Details &&details) {
5591   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5592 }
5593 Symbol *DeclarationVisitor::MakeTypeSymbol(
5594     const SourceName &name, Details &&details) {
5595   Scope &derivedType{currScope()};
5596   CHECK(derivedType.IsDerivedType());
5597   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5598     Say2(name,
5599         "Type parameter, component, or procedure binding '%s'"
5600         " already defined in this type"_err_en_US,
5601         *symbol, "Previous definition of '%s'"_en_US);
5602     return nullptr;
5603   } else {
5604     auto attrs{GetAttrs()};
5605     // Apply binding-private-stmt if present and this is a procedure binding
5606     if (derivedTypeInfo_.privateBindings &&
5607         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5608         std::holds_alternative<ProcBindingDetails>(details)) {
5609       attrs.set(Attr::PRIVATE);
5610     }
5611     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5612     if (result.has<TypeParamDetails>()) {
5613       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5614     }
5615     return &result;
5616   }
5617 }
5618 
5619 // Return true if it is ok to declare this component in the current scope.
5620 // Otherwise, emit an error and return false.
5621 bool DeclarationVisitor::OkToAddComponent(
5622     const parser::Name &name, const Symbol *extends) {
5623   for (const Scope *scope{&currScope()}; scope;) {
5624     CHECK(scope->IsDerivedType());
5625     if (auto *prev{FindInScope(*scope, name)}) {
5626       if (!context().HasError(*prev)) {
5627         parser::MessageFixedText msg;
5628         if (extends) {
5629           msg = "Type cannot be extended as it has a component named"
5630                 " '%s'"_err_en_US;
5631         } else if (prev->test(Symbol::Flag::ParentComp)) {
5632           msg = "'%s' is a parent type of this type and so cannot be"
5633                 " a component"_err_en_US;
5634         } else if (scope != &currScope()) {
5635           msg = "Component '%s' is already declared in a parent of this"
5636                 " derived type"_err_en_US;
5637         } else {
5638           msg = "Component '%s' is already declared in this"
5639                 " derived type"_err_en_US;
5640         }
5641         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5642       }
5643       return false;
5644     }
5645     if (scope == &currScope() && extends) {
5646       // The parent component has not yet been added to the scope.
5647       scope = extends->scope();
5648     } else {
5649       scope = scope->GetDerivedTypeParent();
5650     }
5651   }
5652   return true;
5653 }
5654 
5655 ParamValue DeclarationVisitor::GetParamValue(
5656     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5657   return std::visit(
5658       common::visitors{
5659           [=](const parser::ScalarIntExpr &x) { // C704
5660             return ParamValue{EvaluateIntExpr(x), attr};
5661           },
5662           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5663           [=](const parser::TypeParamValue::Deferred &) {
5664             return ParamValue::Deferred(attr);
5665           },
5666       },
5667       x.u);
5668 }
5669 
5670 // ConstructVisitor implementation
5671 
5672 void ConstructVisitor::ResolveIndexName(
5673     const parser::ConcurrentControl &control) {
5674   const parser::Name &name{std::get<parser::Name>(control.t)};
5675   auto *prev{FindSymbol(name)};
5676   if (prev) {
5677     if (prev->owner().kind() == Scope::Kind::Forall ||
5678         prev->owner() == currScope()) {
5679       SayAlreadyDeclared(name, *prev);
5680       return;
5681     }
5682     name.symbol = nullptr;
5683   }
5684   auto &symbol{DeclareObjectEntity(name)};
5685   if (symbol.GetType()) {
5686     // type came from explicit type-spec
5687   } else if (!prev) {
5688     ApplyImplicitRules(symbol);
5689   } else {
5690     const Symbol &prevRoot{ResolveAssociations(*prev)};
5691     // prev could be host- use- or construct-associated with another symbol
5692     if (!prevRoot.has<ObjectEntityDetails>() &&
5693         !prevRoot.has<EntityDetails>()) {
5694       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5695           *prev, "Previous declaration of '%s'"_en_US);
5696       context().SetError(symbol);
5697       return;
5698     } else {
5699       if (const auto *type{prevRoot.GetType()}) {
5700         symbol.SetType(*type);
5701       }
5702       if (prevRoot.IsObjectArray()) {
5703         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5704         return;
5705       }
5706     }
5707   }
5708   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5709 }
5710 
5711 // We need to make sure that all of the index-names get declared before the
5712 // expressions in the loop control are evaluated so that references to the
5713 // index-names in the expressions are correctly detected.
5714 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5715   BeginDeclTypeSpec();
5716   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5717   const auto &controls{
5718       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5719   for (const auto &control : controls) {
5720     ResolveIndexName(control);
5721   }
5722   Walk(controls);
5723   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5724   EndDeclTypeSpec();
5725   return false;
5726 }
5727 
5728 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5729   for (auto &name : x.v) {
5730     if (auto *symbol{DeclareLocalEntity(name)}) {
5731       symbol->set(Symbol::Flag::LocalityLocal);
5732     }
5733   }
5734   return false;
5735 }
5736 
5737 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5738   for (auto &name : x.v) {
5739     if (auto *symbol{DeclareLocalEntity(name)}) {
5740       symbol->set(Symbol::Flag::LocalityLocalInit);
5741     }
5742   }
5743   return false;
5744 }
5745 
5746 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5747   for (const auto &name : x.v) {
5748     if (!FindSymbol(name)) {
5749       Say(name,
5750           "Variable '%s' with SHARED locality implicitly declared"_warn_en_US);
5751     }
5752     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5753     if (PassesSharedLocalityChecks(name, prev)) {
5754       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5755     }
5756   }
5757   return false;
5758 }
5759 
5760 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5761   ProcessTypeSpec(x.type);
5762   Walk(x.values);
5763   return false;
5764 }
5765 
5766 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5767 // enclosing ac-implied-do
5768 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5769   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5770   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5771   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5772   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5773   // F'2018 has the scope of the implied DO variable covering the entire
5774   // implied DO production (19.4(5)), which seems wrong in cases where the name
5775   // of the implied DO variable appears in one of the bound expressions. Thus
5776   // this extension, which shrinks the scope of the variable to exclude the
5777   // expressions in the bounds.
5778   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5779   Walk(bounds.lower);
5780   Walk(bounds.upper);
5781   Walk(bounds.step);
5782   EndCheckOnIndexUseInOwnBounds(restore);
5783   PushScope(Scope::Kind::ImpliedDos, nullptr);
5784   DeclareStatementEntity(bounds.name, type);
5785   Walk(values);
5786   PopScope();
5787   return false;
5788 }
5789 
5790 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5791   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5792   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5793   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5794   // See comment in Pre(AcImpliedDo) above.
5795   auto restore{BeginCheckOnIndexUseInOwnBounds(bounds.name)};
5796   Walk(bounds.lower);
5797   Walk(bounds.upper);
5798   Walk(bounds.step);
5799   EndCheckOnIndexUseInOwnBounds(restore);
5800   bool pushScope{currScope().kind() != Scope::Kind::ImpliedDos};
5801   if (pushScope) {
5802     PushScope(Scope::Kind::ImpliedDos, nullptr);
5803   }
5804   DeclareStatementEntity(bounds.name, type);
5805   Walk(objects);
5806   if (pushScope) {
5807     PopScope();
5808   }
5809   return false;
5810 }
5811 
5812 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5813 // statement so that the predicate IsInitialized() will be true
5814 // during semantic analysis before the symbol's initializer is constructed.
5815 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5816   std::visit(
5817       common::visitors{
5818           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5819             Walk(y.thing.value());
5820             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5821             if (first.symbol) {
5822               first.symbol->set(Symbol::Flag::InDataStmt);
5823             }
5824           },
5825           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5826       },
5827       x.u);
5828   return false;
5829 }
5830 
5831 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5832   std::visit(common::visitors{
5833                  [&](const Indirection<parser::Variable> &y) {
5834                    Walk(y.value());
5835                    const parser::Name &first{parser::GetFirstName(y.value())};
5836                    if (first.symbol) {
5837                      first.symbol->set(Symbol::Flag::InDataStmt);
5838                    }
5839                  },
5840                  [&](const parser::DataImpliedDo &y) {
5841                    PushScope(Scope::Kind::ImpliedDos, nullptr);
5842                    Walk(y);
5843                    PopScope();
5844                  },
5845              },
5846       x.u);
5847   return false;
5848 }
5849 
5850 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5851   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5852   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5853   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5854     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5855       if (const Symbol * symbol{FindSymbol(*name)}) {
5856         const Symbol &ultimate{symbol->GetUltimate()};
5857         if (ultimate.has<DerivedTypeDetails>()) {
5858           mutableData.u = elem->ConvertToStructureConstructor(
5859               DerivedTypeSpec{name->source, ultimate});
5860         }
5861       }
5862     }
5863   }
5864   return true;
5865 }
5866 
5867 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5868   if (x.IsDoConcurrent()) {
5869     PushScope(Scope::Kind::Block, nullptr);
5870   }
5871   return true;
5872 }
5873 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5874   if (x.IsDoConcurrent()) {
5875     PopScope();
5876   }
5877 }
5878 
5879 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5880   PushScope(Scope::Kind::Forall, nullptr);
5881   return true;
5882 }
5883 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5884 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5885   PushScope(Scope::Kind::Forall, nullptr);
5886   return true;
5887 }
5888 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5889 
5890 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5891   CheckDef(x.v);
5892   PushScope(Scope::Kind::Block, nullptr);
5893   return false;
5894 }
5895 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5896   PopScope();
5897   CheckRef(x.v);
5898   return false;
5899 }
5900 
5901 void ConstructVisitor::Post(const parser::Selector &x) {
5902   GetCurrentAssociation().selector = ResolveSelector(x);
5903 }
5904 
5905 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
5906   CheckDef(x.t);
5907   PushScope(Scope::Kind::Block, nullptr);
5908   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
5909   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
5910     SetCurrentAssociation(nthLastAssoc);
5911     if (auto *symbol{MakeAssocEntity()}) {
5912       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
5913         Say("Selector must not be a coindexed object"_err_en_US);
5914       }
5915       SetTypeFromAssociation(*symbol);
5916       SetAttrsFromAssociation(*symbol);
5917     }
5918   }
5919   PopAssociation(assocCount);
5920 }
5921 
5922 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5923   PopScope();
5924   CheckRef(x.v);
5925 }
5926 
5927 bool ConstructVisitor::Pre(const parser::Association &x) {
5928   PushAssociation();
5929   const auto &name{std::get<parser::Name>(x.t)};
5930   GetCurrentAssociation().name = &name;
5931   return true;
5932 }
5933 
5934 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5935   CheckDef(x.t);
5936   PushScope(Scope::Kind::Block, nullptr);
5937   PushAssociation();
5938   return true;
5939 }
5940 
5941 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5942   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5943   const auto &name{std::get<parser::Name>(decl.t)};
5944   if (auto *symbol{FindInScope(name)}) {
5945     const auto &selector{std::get<parser::Selector>(x.t)};
5946     if (auto sel{ResolveSelector(selector)}) {
5947       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5948       if (!whole || whole->Corank() == 0) {
5949         Say(sel.source, // C1116
5950             "Selector in coarray association must name a coarray"_err_en_US);
5951       } else if (auto dynType{sel.expr->GetType()}) {
5952         if (!symbol->GetType()) {
5953           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5954         }
5955       }
5956     }
5957   }
5958 }
5959 
5960 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5961   PopAssociation();
5962   PopScope();
5963   CheckRef(x.t);
5964 }
5965 
5966 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5967   PushAssociation();
5968   return true;
5969 }
5970 
5971 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5972   PopAssociation();
5973 }
5974 
5975 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
5976   auto &association{GetCurrentAssociation()};
5977   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5978     // This isn't a name in the current scope, it is in each TypeGuardStmt
5979     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
5980     association.name = &*name;
5981     auto exprType{association.selector.expr->GetType()};
5982     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
5983       Say("Selector must not be a coindexed object"_err_en_US);
5984     }
5985     if (exprType && !exprType->IsPolymorphic()) { // C1159
5986       Say(association.selector.source,
5987           "Selector '%s' in SELECT TYPE statement must be "
5988           "polymorphic"_err_en_US);
5989     }
5990   } else {
5991     if (const Symbol *
5992         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5993       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
5994       if (!IsVariableName(*whole)) {
5995         Say(association.selector.source, // C901
5996             "Selector is not a variable"_err_en_US);
5997         association = {};
5998       }
5999       if (const DeclTypeSpec * type{whole->GetType()}) {
6000         if (!type->IsPolymorphic()) { // C1159
6001           Say(association.selector.source,
6002               "Selector '%s' in SELECT TYPE statement must be "
6003               "polymorphic"_err_en_US);
6004         }
6005       }
6006     } else {
6007       Say(association.selector.source, // C1157
6008           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
6009       association = {};
6010     }
6011   }
6012 }
6013 
6014 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
6015   auto &association{GetCurrentAssociation()};
6016   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
6017     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
6018     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
6019     association.name = &*name;
6020   }
6021 }
6022 
6023 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
6024   PushScope(Scope::Kind::Block, nullptr);
6025   return true;
6026 }
6027 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
6028   PopScope();
6029 }
6030 
6031 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
6032   PushScope(Scope::Kind::Block, nullptr);
6033   return true;
6034 }
6035 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
6036   PopScope();
6037 }
6038 
6039 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
6040   if (auto *symbol{MakeAssocEntity()}) {
6041     if (std::holds_alternative<parser::Default>(x.u)) {
6042       SetTypeFromAssociation(*symbol);
6043     } else if (const auto *type{GetDeclTypeSpec()}) {
6044       symbol->SetType(*type);
6045     }
6046     SetAttrsFromAssociation(*symbol);
6047   }
6048 }
6049 
6050 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
6051   if (auto *symbol{MakeAssocEntity()}) {
6052     SetTypeFromAssociation(*symbol);
6053     SetAttrsFromAssociation(*symbol);
6054     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
6055       if (auto val{EvaluateInt64(context(), *init)}) {
6056         auto &details{symbol->get<AssocEntityDetails>()};
6057         details.set_rank(*val);
6058       }
6059     }
6060   }
6061 }
6062 
6063 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
6064   PushAssociation();
6065   return true;
6066 }
6067 
6068 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
6069   PopAssociation();
6070 }
6071 
6072 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
6073   if (x) {
6074     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
6075   }
6076   return true;
6077 }
6078 
6079 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
6080   if (x) {
6081     // Just add an occurrence of this name; checking is done in ValidateLabels
6082     FindSymbol(*x);
6083   }
6084 }
6085 
6086 // Make a symbol for the associating entity of the current association.
6087 Symbol *ConstructVisitor::MakeAssocEntity() {
6088   Symbol *symbol{nullptr};
6089   auto &association{GetCurrentAssociation()};
6090   if (association.name) {
6091     symbol = &MakeSymbol(*association.name, UnknownDetails{});
6092     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
6093       Say(*association.name, // C1102
6094           "The associate name '%s' is already used in this associate statement"_err_en_US);
6095       return nullptr;
6096     }
6097   } else if (const Symbol *
6098       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
6099     symbol = &MakeSymbol(whole->name());
6100   } else {
6101     return nullptr;
6102   }
6103   if (auto &expr{association.selector.expr}) {
6104     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
6105   } else {
6106     symbol->set_details(AssocEntityDetails{});
6107   }
6108   return symbol;
6109 }
6110 
6111 // Set the type of symbol based on the current association selector.
6112 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
6113   auto &details{symbol.get<AssocEntityDetails>()};
6114   const MaybeExpr *pexpr{&details.expr()};
6115   if (!*pexpr) {
6116     pexpr = &GetCurrentAssociation().selector.expr;
6117   }
6118   if (*pexpr) {
6119     const SomeExpr &expr{**pexpr};
6120     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
6121       if (const auto *charExpr{
6122               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
6123                   expr)}) {
6124         symbol.SetType(ToDeclTypeSpec(std::move(*type),
6125             FoldExpr(
6126                 std::visit([](const auto &kindChar) { return kindChar.LEN(); },
6127                     charExpr->u))));
6128       } else {
6129         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
6130       }
6131     } else {
6132       // BOZ literals, procedure designators, &c. are not acceptable
6133       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
6134     }
6135   }
6136 }
6137 
6138 // If current selector is a variable, set some of its attributes on symbol.
6139 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
6140   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
6141   symbol.attrs() |= attrs &
6142       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
6143   if (attrs.test(Attr::POINTER)) {
6144     symbol.attrs().set(Attr::TARGET);
6145   }
6146 }
6147 
6148 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
6149     const parser::Selector &x) {
6150   return std::visit(common::visitors{
6151                         [&](const parser::Expr &expr) {
6152                           return Selector{expr.source, EvaluateExpr(x)};
6153                         },
6154                         [&](const parser::Variable &var) {
6155                           return Selector{var.GetSource(), EvaluateExpr(x)};
6156                         },
6157                     },
6158       x.u);
6159 }
6160 
6161 // Set the current association to the nth to the last association on the
6162 // association stack.  The top of the stack is at n = 1.  This allows access
6163 // to the interior of a list of associations at the top of the stack.
6164 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
6165   CHECK(n > 0 && n <= associationStack_.size());
6166   currentAssociation_ = &associationStack_[associationStack_.size() - n];
6167 }
6168 
6169 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
6170   CHECK(currentAssociation_);
6171   return *currentAssociation_;
6172 }
6173 
6174 void ConstructVisitor::PushAssociation() {
6175   associationStack_.emplace_back(Association{});
6176   currentAssociation_ = &associationStack_.back();
6177 }
6178 
6179 void ConstructVisitor::PopAssociation(std::size_t count) {
6180   CHECK(count > 0 && count <= associationStack_.size());
6181   associationStack_.resize(associationStack_.size() - count);
6182   currentAssociation_ =
6183       associationStack_.empty() ? nullptr : &associationStack_.back();
6184 }
6185 
6186 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6187     evaluate::DynamicType &&type) {
6188   switch (type.category()) {
6189     SWITCH_COVERS_ALL_CASES
6190   case common::TypeCategory::Integer:
6191   case common::TypeCategory::Real:
6192   case common::TypeCategory::Complex:
6193     return context().MakeNumericType(type.category(), type.kind());
6194   case common::TypeCategory::Logical:
6195     return context().MakeLogicalType(type.kind());
6196   case common::TypeCategory::Derived:
6197     if (type.IsAssumedType()) {
6198       return currScope().MakeTypeStarType();
6199     } else if (type.IsUnlimitedPolymorphic()) {
6200       return currScope().MakeClassStarType();
6201     } else {
6202       return currScope().MakeDerivedType(
6203           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
6204                                : DeclTypeSpec::TypeDerived,
6205           common::Clone(type.GetDerivedTypeSpec())
6206 
6207       );
6208     }
6209   case common::TypeCategory::Character:
6210     CRASH_NO_CASE;
6211   }
6212 }
6213 
6214 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
6215     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
6216   CHECK(type.category() == common::TypeCategory::Character);
6217   if (length) {
6218     return currScope().MakeCharacterType(
6219         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
6220         KindExpr{type.kind()});
6221   } else {
6222     return currScope().MakeCharacterType(
6223         ParamValue::Deferred(common::TypeParamAttr::Len),
6224         KindExpr{type.kind()});
6225   }
6226 }
6227 
6228 // ResolveNamesVisitor implementation
6229 
6230 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
6231   HandleCall(Symbol::Flag::Function, x.v);
6232   return false;
6233 }
6234 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
6235   HandleCall(Symbol::Flag::Subroutine, x.v);
6236   return false;
6237 }
6238 
6239 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
6240   auto &scope{currScope()};
6241   // Check C896 and C899: where IMPORT statements are allowed
6242   switch (scope.kind()) {
6243   case Scope::Kind::Module:
6244     if (scope.IsModule()) {
6245       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
6246       return false;
6247     } else if (x.kind == common::ImportKind::None) {
6248       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
6249       return false;
6250     }
6251     break;
6252   case Scope::Kind::MainProgram:
6253     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
6254     return false;
6255   case Scope::Kind::Subprogram:
6256     if (scope.parent().IsGlobal()) {
6257       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
6258       return false;
6259     }
6260     break;
6261   case Scope::Kind::BlockData: // C1415 (in part)
6262     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
6263     return false;
6264   default:;
6265   }
6266   if (auto error{scope.SetImportKind(x.kind)}) {
6267     Say(std::move(*error));
6268   }
6269   for (auto &name : x.names) {
6270     if (FindSymbol(scope.parent(), name)) {
6271       scope.add_importName(name.source);
6272     } else {
6273       Say(name, "'%s' not found in host scope"_err_en_US);
6274     }
6275   }
6276   prevImportStmt_ = currStmtSource();
6277   return false;
6278 }
6279 
6280 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
6281     const parser::StructureComponent &x) {
6282   return FindComponent(ResolveDataRef(x.base), x.component);
6283 }
6284 
6285 const parser::Name *DeclarationVisitor::ResolveDesignator(
6286     const parser::Designator &x) {
6287   return std::visit(
6288       common::visitors{
6289           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
6290           [&](const parser::Substring &x) {
6291             return ResolveDataRef(std::get<parser::DataRef>(x.t));
6292           },
6293       },
6294       x.u);
6295 }
6296 
6297 const parser::Name *DeclarationVisitor::ResolveDataRef(
6298     const parser::DataRef &x) {
6299   return std::visit(
6300       common::visitors{
6301           [=](const parser::Name &y) { return ResolveName(y); },
6302           [=](const Indirection<parser::StructureComponent> &y) {
6303             return ResolveStructureComponent(y.value());
6304           },
6305           [&](const Indirection<parser::ArrayElement> &y) {
6306             Walk(y.value().subscripts);
6307             const parser::Name *name{ResolveDataRef(y.value().base)};
6308             if (name && name->symbol) {
6309               if (!IsProcedure(*name->symbol)) {
6310                 ConvertToObjectEntity(*name->symbol);
6311               } else if (!context().HasError(*name->symbol)) {
6312                 SayWithDecl(*name, *name->symbol,
6313                     "Cannot reference function '%s' as data"_err_en_US);
6314               }
6315             }
6316             return name;
6317           },
6318           [&](const Indirection<parser::CoindexedNamedObject> &y) {
6319             Walk(y.value().imageSelector);
6320             return ResolveDataRef(y.value().base);
6321           },
6322       },
6323       x.u);
6324 }
6325 
6326 // If implicit types are allowed, ensure name is in the symbol table.
6327 // Otherwise, report an error if it hasn't been declared.
6328 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
6329   FindSymbol(name);
6330   if (CheckForHostAssociatedImplicit(name)) {
6331     NotePossibleBadForwardRef(name);
6332     return &name;
6333   }
6334   if (Symbol * symbol{name.symbol}) {
6335     if (CheckUseError(name)) {
6336       return nullptr; // reported an error
6337     }
6338     NotePossibleBadForwardRef(name);
6339     symbol->set(Symbol::Flag::ImplicitOrError, false);
6340     if (IsUplevelReference(*symbol)) {
6341       MakeHostAssocSymbol(name, *symbol);
6342     } else if (IsDummy(*symbol) ||
6343         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
6344       ConvertToObjectEntity(*symbol);
6345       ApplyImplicitRules(*symbol);
6346     }
6347     if (checkIndexUseInOwnBounds_ &&
6348         *checkIndexUseInOwnBounds_ == name.source) {
6349       Say(name,
6350           "Implied DO index '%s' uses an object of the same name in its bounds expressions"_port_en_US,
6351           name.source);
6352     }
6353     return &name;
6354   }
6355   if (isImplicitNoneType()) {
6356     Say(name, "No explicit type declared for '%s'"_err_en_US);
6357     return nullptr;
6358   }
6359   // Create the symbol then ensure it is accessible
6360   if (checkIndexUseInOwnBounds_ && *checkIndexUseInOwnBounds_ == name.source) {
6361     Say(name,
6362         "Implied DO index '%s' uses itself in its own bounds expressions"_err_en_US,
6363         name.source);
6364   }
6365   MakeSymbol(InclusiveScope(), name.source, Attrs{});
6366   auto *symbol{FindSymbol(name)};
6367   if (!symbol) {
6368     Say(name,
6369         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
6370     return nullptr;
6371   }
6372   ConvertToObjectEntity(*symbol);
6373   ApplyImplicitRules(*symbol);
6374   NotePossibleBadForwardRef(name);
6375   return &name;
6376 }
6377 
6378 // A specification expression may refer to a symbol in the host procedure that
6379 // is implicitly typed. Because specification parts are processed before
6380 // execution parts, this may be the first time we see the symbol. It can't be a
6381 // local in the current scope (because it's in a specification expression) so
6382 // either it is implicitly declared in the host procedure or it is an error.
6383 // We create a symbol in the host assuming it is the former; if that proves to
6384 // be wrong we report an error later in CheckDeclarations().
6385 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
6386     const parser::Name &name) {
6387   if (inExecutionPart_) {
6388     return false;
6389   }
6390   if (name.symbol) {
6391     ApplyImplicitRules(*name.symbol, true);
6392   }
6393   Symbol *hostSymbol;
6394   Scope *host{GetHostProcedure()};
6395   if (!host || isImplicitNoneType(*host)) {
6396     return false;
6397   }
6398   if (!name.symbol) {
6399     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
6400     ConvertToObjectEntity(*hostSymbol);
6401     ApplyImplicitRules(*hostSymbol);
6402     hostSymbol->set(Symbol::Flag::ImplicitOrError);
6403   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
6404     hostSymbol = name.symbol;
6405   } else {
6406     return false;
6407   }
6408   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
6409   if (isImplicitNoneType()) {
6410     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
6411   } else {
6412     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
6413   }
6414   return true;
6415 }
6416 
6417 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
6418   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
6419   if (symbolUnit == GetProgramUnitContaining(currScope())) {
6420     return false;
6421   } else {
6422     Scope::Kind kind{symbolUnit.kind()};
6423     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
6424   }
6425 }
6426 
6427 // base is a part-ref of a derived type; find the named component in its type.
6428 // Also handles intrinsic type parameter inquiries (%kind, %len) and
6429 // COMPLEX component references (%re, %im).
6430 const parser::Name *DeclarationVisitor::FindComponent(
6431     const parser::Name *base, const parser::Name &component) {
6432   if (!base || !base->symbol) {
6433     return nullptr;
6434   }
6435   auto &symbol{base->symbol->GetUltimate()};
6436   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
6437     SayWithDecl(*base, symbol,
6438         "'%s' is an invalid base for a component reference"_err_en_US);
6439     return nullptr;
6440   }
6441   auto *type{symbol.GetType()};
6442   if (!type) {
6443     return nullptr; // should have already reported error
6444   }
6445   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
6446     auto name{component.ToString()};
6447     auto category{intrinsic->category()};
6448     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
6449     if (name == "kind") {
6450       miscKind = MiscDetails::Kind::KindParamInquiry;
6451     } else if (category == TypeCategory::Character) {
6452       if (name == "len") {
6453         miscKind = MiscDetails::Kind::LenParamInquiry;
6454       }
6455     } else if (category == TypeCategory::Complex) {
6456       if (name == "re") {
6457         miscKind = MiscDetails::Kind::ComplexPartRe;
6458       } else if (name == "im") {
6459         miscKind = MiscDetails::Kind::ComplexPartIm;
6460       }
6461     }
6462     if (miscKind != MiscDetails::Kind::None) {
6463       MakePlaceholder(component, miscKind);
6464       return nullptr;
6465     }
6466   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
6467     if (const Scope * scope{derived->scope()}) {
6468       if (Resolve(component, scope->FindComponent(component.source))) {
6469         if (auto msg{
6470                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
6471           context().Say(component.source, *msg);
6472         }
6473         return &component;
6474       } else {
6475         SayDerivedType(component.source,
6476             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
6477       }
6478     }
6479     return nullptr;
6480   }
6481   if (symbol.test(Symbol::Flag::Implicit)) {
6482     Say(*base,
6483         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
6484   } else {
6485     SayWithDecl(
6486         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
6487   }
6488   return nullptr;
6489 }
6490 
6491 void DeclarationVisitor::Initialization(const parser::Name &name,
6492     const parser::Initialization &init, bool inComponentDecl) {
6493   // Traversal of the initializer was deferred to here so that the
6494   // symbol being declared can be available for use in the expression, e.g.:
6495   //   real, parameter :: x = tiny(x)
6496   if (!name.symbol) {
6497     return;
6498   }
6499   Symbol &ultimate{name.symbol->GetUltimate()};
6500   if (IsAllocatable(ultimate)) {
6501     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
6502     return;
6503   }
6504   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
6505     // TODO: check C762 - all bounds and type parameters of component
6506     // are colons or constant expressions if component is initialized
6507     std::visit(
6508         common::visitors{
6509             [&](const parser::ConstantExpr &expr) {
6510               NonPointerInitialization(name, expr);
6511             },
6512             [&](const parser::NullInit &null) {
6513               Walk(null);
6514               if (auto nullInit{EvaluateExpr(null)}) {
6515                 if (!evaluate::IsNullPointer(*nullInit)) {
6516                   Say(name,
6517                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
6518                 } else if (IsPointer(ultimate)) {
6519                   object->set_init(std::move(*nullInit));
6520                 } else {
6521                   Say(name,
6522                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
6523                 }
6524               }
6525             },
6526             [&](const parser::InitialDataTarget &) {
6527               // Defer analysis to the end of the specification part
6528               // so that forward references and attribute checks like SAVE
6529               // work better.
6530               ultimate.set(Symbol::Flag::InDataStmt);
6531             },
6532             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
6533               // Handled later in data-to-inits conversion
6534               ultimate.set(Symbol::Flag::InDataStmt);
6535             },
6536         },
6537         init.u);
6538   }
6539 }
6540 
6541 void DeclarationVisitor::PointerInitialization(
6542     const parser::Name &name, const parser::InitialDataTarget &target) {
6543   if (name.symbol) {
6544     Symbol &ultimate{name.symbol->GetUltimate()};
6545     if (!context().HasError(ultimate)) {
6546       if (IsPointer(ultimate)) {
6547         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6548           CHECK(!details->init());
6549           Walk(target);
6550           if (MaybeExpr expr{EvaluateExpr(target)}) {
6551             // Validation is done in declaration checking.
6552             details->set_init(std::move(*expr));
6553           }
6554         }
6555       } else {
6556         Say(name,
6557             "'%s' is not a pointer but is initialized like one"_err_en_US);
6558         context().SetError(ultimate);
6559       }
6560     }
6561   }
6562 }
6563 void DeclarationVisitor::PointerInitialization(
6564     const parser::Name &name, const parser::ProcPointerInit &target) {
6565   if (name.symbol) {
6566     Symbol &ultimate{name.symbol->GetUltimate()};
6567     if (!context().HasError(ultimate)) {
6568       if (IsProcedurePointer(ultimate)) {
6569         auto &details{ultimate.get<ProcEntityDetails>()};
6570         CHECK(!details.init());
6571         Walk(target);
6572         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6573           if (targetName->symbol) {
6574             // Validation is done in declaration checking.
6575             details.set_init(*targetName->symbol);
6576           }
6577         } else {
6578           details.set_init(nullptr); // explicit NULL()
6579         }
6580       } else {
6581         Say(name,
6582             "'%s' is not a procedure pointer but is initialized "
6583             "like one"_err_en_US);
6584         context().SetError(ultimate);
6585       }
6586     }
6587   }
6588 }
6589 
6590 void DeclarationVisitor::NonPointerInitialization(
6591     const parser::Name &name, const parser::ConstantExpr &expr) {
6592   if (name.symbol) {
6593     Symbol &ultimate{name.symbol->GetUltimate()};
6594     if (!context().HasError(ultimate) && !context().HasError(name.symbol)) {
6595       if (IsPointer(ultimate)) {
6596         Say(name,
6597             "'%s' is a pointer but is not initialized like one"_err_en_US);
6598       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6599         CHECK(!details->init());
6600         Walk(expr);
6601         if (ultimate.owner().IsParameterizedDerivedType()) {
6602           // Can't convert to type of component, which might not yet
6603           // be known; that's done later during PDT instantiation.
6604           if (MaybeExpr value{EvaluateExpr(expr)}) {
6605             details->set_init(std::move(*value));
6606           }
6607         } else if (MaybeExpr folded{EvaluateNonPointerInitializer(
6608                        ultimate, expr, expr.thing.value().source)}) {
6609           details->set_init(std::move(*folded));
6610         }
6611       }
6612     }
6613   }
6614 }
6615 
6616 void ResolveNamesVisitor::HandleCall(
6617     Symbol::Flag procFlag, const parser::Call &call) {
6618   std::visit(
6619       common::visitors{
6620           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6621           [&](const parser::ProcComponentRef &x) { Walk(x); },
6622       },
6623       std::get<parser::ProcedureDesignator>(call.t).u);
6624   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6625 }
6626 
6627 void ResolveNamesVisitor::HandleProcedureName(
6628     Symbol::Flag flag, const parser::Name &name) {
6629   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6630   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6631   if (!symbol) {
6632     if (IsIntrinsic(name.source, flag)) {
6633       symbol =
6634           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6635     } else {
6636       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6637     }
6638     Resolve(name, *symbol);
6639     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6640       if (CheckImplicitNoneExternal(name.source, *symbol)) {
6641         MakeExternal(*symbol);
6642       }
6643     }
6644     ConvertToProcEntity(*symbol);
6645     SetProcFlag(name, *symbol, flag);
6646   } else if (CheckUseError(name)) {
6647     // error was reported
6648   } else {
6649     auto &nonUltimateSymbol = *symbol;
6650     symbol = &Resolve(name, symbol)->GetUltimate();
6651     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6652     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6653         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6654       AcquireIntrinsicProcedureFlags(*symbol);
6655     }
6656     if (!SetProcFlag(name, *symbol, flag)) {
6657       return; // reported error
6658     }
6659     if (!symbol->has<GenericDetails>()) {
6660       CheckImplicitNoneExternal(name.source, *symbol);
6661     }
6662     if (symbol->has<SubprogramDetails>() &&
6663         symbol->attrs().test(Attr::ABSTRACT)) {
6664       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6665     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6666         symbol->has<AssocEntityDetails>()) {
6667       // Symbols with DerivedTypeDetails and AssocEntityDetails are accepted
6668       // here as procedure-designators because this means the related
6669       // FunctionReference are mis-parsed structure constructors or array
6670       // references that will be fixed later when analyzing expressions.
6671     } else if (symbol->has<ObjectEntityDetails>()) {
6672       // Symbols with ObjectEntityDetails are also accepted because this can be
6673       // a mis-parsed array references that will be fixed later. Ensure that if
6674       // this is a symbol from a host procedure, a symbol with HostAssocDetails
6675       // is created for the current scope.
6676       // Operate on non ultimate symbol so that HostAssocDetails are also
6677       // created for symbols used associated in the host procedure.
6678       if (IsUplevelReference(nonUltimateSymbol)) {
6679         MakeHostAssocSymbol(name, nonUltimateSymbol);
6680       }
6681     } else if (symbol->test(Symbol::Flag::Implicit)) {
6682       Say(name,
6683           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6684     } else {
6685       SayWithDecl(name, *symbol,
6686           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6687     }
6688   }
6689 }
6690 
6691 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6692     const SourceName &name, const Symbol &symbol) {
6693   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6694       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6695     Say(name,
6696         "'%s' is an external procedure without the EXTERNAL"
6697         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6698     return false;
6699   }
6700   return true;
6701 }
6702 
6703 // Variant of HandleProcedureName() for use while skimming the executable
6704 // part of a subprogram to catch calls to dummy procedures that are part
6705 // of the subprogram's interface, and to mark as procedures any symbols
6706 // that might otherwise have been miscategorized as objects.
6707 void ResolveNamesVisitor::NoteExecutablePartCall(
6708     Symbol::Flag flag, const parser::Call &call) {
6709   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6710   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6711     // Subtlety: The symbol pointers in the parse tree are not set, because
6712     // they might end up resolving elsewhere (e.g., construct entities in
6713     // SELECT TYPE).
6714     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6715       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6716               ? Symbol::Flag::Function
6717               : Symbol::Flag::Subroutine};
6718       if (!symbol->test(other)) {
6719         ConvertToProcEntity(*symbol);
6720         if (symbol->has<ProcEntityDetails>()) {
6721           symbol->set(flag);
6722           if (IsDummy(*symbol)) {
6723             symbol->attrs().set(Attr::EXTERNAL);
6724           }
6725           ApplyImplicitRules(*symbol);
6726         }
6727       }
6728     }
6729   }
6730 }
6731 
6732 static bool IsLocallyImplicitGlobalSymbol(
6733     const Symbol &symbol, const parser::Name &localName) {
6734   return symbol.owner().IsGlobal() &&
6735       (!symbol.scope() ||
6736           !symbol.scope()->sourceRange().Contains(localName.source));
6737 }
6738 
6739 static bool TypesMismatchIfNonNull(
6740     const DeclTypeSpec *type1, const DeclTypeSpec *type2) {
6741   return type1 && type2 && *type1 != *type2;
6742 }
6743 
6744 // Check and set the Function or Subroutine flag on symbol; false on error.
6745 bool ResolveNamesVisitor::SetProcFlag(
6746     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6747   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6748     SayWithDecl(
6749         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6750     return false;
6751   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6752       flag == Symbol::Flag::Function) {
6753     SayWithDecl(
6754         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6755     return false;
6756   } else if (flag == Symbol::Flag::Function &&
6757       IsLocallyImplicitGlobalSymbol(symbol, name) &&
6758       TypesMismatchIfNonNull(symbol.GetType(), GetImplicitType(symbol))) {
6759     SayWithDecl(name, symbol,
6760         "Implicit declaration of function '%s' has a different result type than in previous declaration"_err_en_US);
6761     return false;
6762   } else if (symbol.has<ProcEntityDetails>()) {
6763     symbol.set(flag); // in case it hasn't been set yet
6764     if (flag == Symbol::Flag::Function) {
6765       ApplyImplicitRules(symbol);
6766     }
6767     if (symbol.attrs().test(Attr::INTRINSIC)) {
6768       AcquireIntrinsicProcedureFlags(symbol);
6769     }
6770   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6771     SayWithDecl(
6772         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6773   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6774     AcquireIntrinsicProcedureFlags(symbol);
6775   }
6776   return true;
6777 }
6778 
6779 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6780   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6781   if (!currScope().IsModule()) { // C869
6782     Say(currStmtSource().value(),
6783         "%s statement may only appear in the specification part of a module"_err_en_US,
6784         EnumToString(accessAttr));
6785     return false;
6786   }
6787   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6788   if (accessIds.empty()) {
6789     if (prevAccessStmt_) { // C869
6790       Say("The default accessibility of this module has already been declared"_err_en_US)
6791           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6792     }
6793     prevAccessStmt_ = currStmtSource();
6794     defaultAccess_ = accessAttr;
6795   } else {
6796     for (const auto &accessId : accessIds) {
6797       std::visit(
6798           common::visitors{
6799               [=](const parser::Name &y) {
6800                 Resolve(y, SetAccess(y.source, accessAttr));
6801               },
6802               [=](const Indirection<parser::GenericSpec> &y) {
6803                 auto info{GenericSpecInfo{y.value()}};
6804                 const auto &symbolName{info.symbolName()};
6805                 if (auto *symbol{FindInScope(symbolName)}) {
6806                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6807                 } else if (info.kind().IsName()) {
6808                   info.Resolve(&SetAccess(symbolName, accessAttr));
6809                 } else {
6810                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6811                 }
6812               },
6813           },
6814           accessId.u);
6815     }
6816   }
6817   return false;
6818 }
6819 
6820 // Set the access specification for this symbol.
6821 Symbol &ModuleVisitor::SetAccess(
6822     const SourceName &name, Attr attr, Symbol *symbol) {
6823   if (!symbol) {
6824     symbol = &MakeSymbol(name);
6825   }
6826   Attrs &attrs{symbol->attrs()};
6827   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6828     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6829     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6830     Say(name,
6831         WithSeverity(
6832             "The accessibility of '%s' has already been specified as %s"_warn_en_US,
6833             attr != prev ? parser::Severity::Error : parser::Severity::Warning),
6834         MakeOpName(name), EnumToString(prev));
6835   } else {
6836     attrs.set(attr);
6837   }
6838   return *symbol;
6839 }
6840 
6841 static bool NeedsExplicitType(const Symbol &symbol) {
6842   if (symbol.has<UnknownDetails>()) {
6843     return true;
6844   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6845     return !details->type();
6846   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6847     return !details->type();
6848   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6849     return !details->interface().symbol() && !details->interface().type();
6850   } else {
6851     return false;
6852   }
6853 }
6854 
6855 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6856   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
6857       implicitPart, decls] = x.t;
6858   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
6859   auto stateRestorer{
6860       common::ScopedSet(specPartState_, SpecificationPartState{})};
6861   Walk(accDecls);
6862   Walk(ompDecls);
6863   Walk(compilerDirectives);
6864   Walk(useStmts);
6865   ClearUseRenames();
6866   ClearUseOnly();
6867   ClearExplicitIntrinsicUses();
6868   Walk(importStmts);
6869   Walk(implicitPart);
6870   for (const auto &decl : decls) {
6871     if (const auto *spec{
6872             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6873       PreSpecificationConstruct(*spec);
6874     }
6875   }
6876   Walk(decls);
6877   FinishSpecificationPart(decls);
6878   return false;
6879 }
6880 
6881 // Initial processing on specification constructs, before visiting them.
6882 void ResolveNamesVisitor::PreSpecificationConstruct(
6883     const parser::SpecificationConstruct &spec) {
6884   std::visit(
6885       common::visitors{
6886           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6887             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6888           },
6889           [&](const Indirection<parser::InterfaceBlock> &y) {
6890             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6891                 y.value().t)};
6892             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
6893               CreateGeneric(*spec);
6894             }
6895           },
6896           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
6897             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
6898               CreateCommonBlockSymbols(*commonStmt);
6899             }
6900           },
6901           [&](const auto &) {},
6902       },
6903       spec.u);
6904 }
6905 
6906 void ResolveNamesVisitor::CreateCommonBlockSymbols(
6907     const parser::CommonStmt &commonStmt) {
6908   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
6909     const auto &[name, objects] = block.t;
6910     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
6911     for (const auto &object : objects) {
6912       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
6913       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
6914         details->set_commonBlock(commonBlock);
6915         commonBlock.get<CommonBlockDetails>().add_object(obj);
6916       }
6917     }
6918   }
6919 }
6920 
6921 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6922   auto info{GenericSpecInfo{x}};
6923   SourceName symbolName{info.symbolName()};
6924   if (IsLogicalConstant(context(), symbolName)) {
6925     Say(symbolName,
6926         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6927     return;
6928   }
6929   GenericDetails genericDetails;
6930   Symbol *existing{nullptr};
6931   // Check all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
6932   for (const std::string &n : GetAllNames(context(), symbolName)) {
6933     existing = currScope().FindSymbol(n);
6934     if (existing) {
6935       break;
6936     }
6937   }
6938   if (existing) {
6939     Symbol &ultimate{existing->GetUltimate()};
6940     if (const auto *existingGeneric{ultimate.detailsIf<GenericDetails>()}) {
6941       if (&ultimate.owner() != &currScope()) {
6942         // Create a local copy of a host or use associated generic so that
6943         // it can be locally extended without corrupting the original.
6944         genericDetails.CopyFrom(*existingGeneric);
6945         if (const auto *use{existing->detailsIf<UseDetails>()}) {
6946           AddGenericUse(genericDetails, existing->name(), use->symbol());
6947           EraseSymbol(*existing);
6948         }
6949         existing = &MakeSymbol(symbolName, Attrs{}, std::move(genericDetails));
6950       }
6951       info.Resolve(existing);
6952       return;
6953     }
6954     if (ultimate.has<SubprogramDetails>() ||
6955         ultimate.has<SubprogramNameDetails>()) {
6956       genericDetails.set_specific(ultimate);
6957     } else if (ultimate.has<DerivedTypeDetails>()) {
6958       genericDetails.set_derivedType(ultimate);
6959     } else {
6960       SayAlreadyDeclared(symbolName, *existing);
6961       return;
6962     }
6963     EraseSymbol(*existing);
6964   }
6965   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
6966 }
6967 
6968 void ResolveNamesVisitor::FinishSpecificationPart(
6969     const std::list<parser::DeclarationConstruct> &decls) {
6970   badStmtFuncFound_ = false;
6971   funcResultStack().CompleteFunctionResultType();
6972   CheckImports();
6973   bool inModule{currScope().kind() == Scope::Kind::Module};
6974   for (auto &pair : currScope()) {
6975     auto &symbol{*pair.second};
6976     if (NeedsExplicitType(symbol)) {
6977       ApplyImplicitRules(symbol);
6978     }
6979     if (IsDummy(symbol) && isImplicitNoneType() &&
6980         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
6981       Say(symbol.name(),
6982           "No explicit type declared for dummy argument '%s'"_err_en_US);
6983       context().SetError(symbol);
6984     }
6985     if (symbol.has<GenericDetails>()) {
6986       CheckGenericProcedures(symbol);
6987     }
6988     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
6989         !symbol.test(Symbol::Flag::Function) &&
6990         !symbol.test(Symbol::Flag::Subroutine)) {
6991       // in a module, external proc without return type is subroutine
6992       symbol.set(
6993           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
6994     }
6995     if (!symbol.has<HostAssocDetails>()) {
6996       CheckPossibleBadForwardRef(symbol);
6997     }
6998   }
6999   currScope().InstantiateDerivedTypes();
7000   for (const auto &decl : decls) {
7001     if (const auto *statement{std::get_if<
7002             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
7003             &decl.u)}) {
7004       AnalyzeStmtFunctionStmt(statement->statement.value());
7005     }
7006   }
7007   // TODO: what about instantiations in BLOCK?
7008   CheckSaveStmts();
7009   CheckCommonBlocks();
7010   if (!inInterfaceBlock()) {
7011     // TODO: warn for the case where the EQUIVALENCE statement is in a
7012     // procedure declaration in an interface block
7013     CheckEquivalenceSets();
7014   }
7015 }
7016 
7017 // Analyze the bodies of statement functions now that the symbols in this
7018 // specification part have been fully declared and implicitly typed.
7019 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
7020     const parser::StmtFunctionStmt &stmtFunc) {
7021   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
7022   if (!symbol || !symbol->has<SubprogramDetails>()) {
7023     return;
7024   }
7025   auto &details{symbol->get<SubprogramDetails>()};
7026   auto expr{AnalyzeExpr(
7027       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
7028   if (!expr) {
7029     context().SetError(*symbol);
7030     return;
7031   }
7032   if (auto type{evaluate::DynamicType::From(*symbol)}) {
7033     auto converted{ConvertToType(*type, std::move(*expr))};
7034     if (!converted) {
7035       context().SetError(*symbol);
7036       return;
7037     }
7038     details.set_stmtFunction(std::move(*converted));
7039   } else {
7040     details.set_stmtFunction(std::move(*expr));
7041   }
7042 }
7043 
7044 void ResolveNamesVisitor::CheckImports() {
7045   auto &scope{currScope()};
7046   switch (scope.GetImportKind()) {
7047   case common::ImportKind::None:
7048     break;
7049   case common::ImportKind::All:
7050     // C8102: all entities in host must not be hidden
7051     for (const auto &pair : scope.parent()) {
7052       auto &name{pair.first};
7053       std::optional<SourceName> scopeName{scope.GetName()};
7054       if (!scopeName || name != *scopeName) {
7055         CheckImport(prevImportStmt_.value(), name);
7056       }
7057     }
7058     break;
7059   case common::ImportKind::Default:
7060   case common::ImportKind::Only:
7061     // C8102: entities named in IMPORT must not be hidden
7062     for (auto &name : scope.importNames()) {
7063       CheckImport(name, name);
7064     }
7065     break;
7066   }
7067 }
7068 
7069 void ResolveNamesVisitor::CheckImport(
7070     const SourceName &location, const SourceName &name) {
7071   if (auto *symbol{FindInScope(name)}) {
7072     const Symbol &ultimate{symbol->GetUltimate()};
7073     if (&ultimate.owner() == &currScope()) {
7074       Say(location, "'%s' from host is not accessible"_err_en_US, name)
7075           .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
7076               symbol->name());
7077     }
7078   }
7079 }
7080 
7081 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
7082   return CheckNotInBlock("IMPLICIT") && // C1107
7083       ImplicitRulesVisitor::Pre(x);
7084 }
7085 
7086 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
7087   std::visit(common::visitors{
7088                  [&](const parser::Name &x) { ResolveName(x); },
7089                  [&](const parser::StructureComponent &x) {
7090                    ResolveStructureComponent(x);
7091                  },
7092              },
7093       x.u);
7094 }
7095 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
7096   std::visit(common::visitors{
7097                  [&](const parser::Name &x) { ResolveName(x); },
7098                  [&](const parser::StructureComponent &x) {
7099                    ResolveStructureComponent(x);
7100                  },
7101              },
7102       x.u);
7103 }
7104 
7105 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
7106   const auto &dataRef{std::get<parser::DataRef>(x.t)};
7107   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
7108   const auto &expr{std::get<parser::Expr>(x.t)};
7109   ResolveDataRef(dataRef);
7110   Walk(bounds);
7111   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
7112   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
7113     if (NameIsKnownOrIntrinsic(*name)) {
7114       // If the name is known because it is an object entity from a host
7115       // procedure, create a host associated symbol.
7116       if (Symbol * symbol{name->symbol}; symbol &&
7117           symbol->GetUltimate().has<ObjectEntityDetails>() &&
7118           IsUplevelReference(*symbol)) {
7119         MakeHostAssocSymbol(*name, *symbol);
7120       }
7121       return false;
7122     }
7123   }
7124   Walk(expr);
7125   return false;
7126 }
7127 void ResolveNamesVisitor::Post(const parser::Designator &x) {
7128   ResolveDesignator(x);
7129 }
7130 
7131 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
7132   ResolveStructureComponent(x.v.thing);
7133 }
7134 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
7135   DeclTypeSpecVisitor::Post(x);
7136   ConstructVisitor::Post(x);
7137 }
7138 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
7139   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
7140   if (HandleStmtFunction(x)) {
7141     return false;
7142   } else {
7143     // This is an array element assignment: resolve names of indices
7144     const auto &names{std::get<std::list<parser::Name>>(x.t)};
7145     for (auto &name : names) {
7146       ResolveName(name);
7147     }
7148     return true;
7149   }
7150 }
7151 
7152 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
7153   const parser::Name &name{x.v};
7154   if (FindSymbol(name)) {
7155     // OK
7156   } else if (IsLogicalConstant(context(), name.source)) {
7157     Say(name,
7158         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
7159   } else {
7160     // Resolved later in expression semantics
7161     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
7162   }
7163   return false;
7164 }
7165 
7166 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
7167   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7168     ConvertToObjectEntity(DEREF(name->symbol));
7169   }
7170 }
7171 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
7172   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
7173     ConvertToObjectEntity(DEREF(name->symbol));
7174   }
7175 }
7176 
7177 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
7178   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
7179           x.u)) {
7180     // TODO: global directives
7181     return true;
7182   }
7183   auto root{ProgramTree::Build(x)};
7184   SetScope(topScope_);
7185   ResolveSpecificationParts(root);
7186   FinishSpecificationParts(root);
7187   inExecutionPart_ = true;
7188   ResolveExecutionParts(root);
7189   inExecutionPart_ = false;
7190   ResolveAccParts(context(), x);
7191   ResolveOmpParts(context(), x);
7192   return false;
7193 }
7194 
7195 // References to procedures need to record that their symbols are known
7196 // to be procedures, so that they don't get converted to objects by default.
7197 class ExecutionPartSkimmer {
7198 public:
7199   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
7200       : resolver_{resolver} {}
7201 
7202   void Walk(const parser::ExecutionPart *exec) {
7203     if (exec) {
7204       parser::Walk(*exec, *this);
7205     }
7206   }
7207 
7208   template <typename A> bool Pre(const A &) { return true; }
7209   template <typename A> void Post(const A &) {}
7210   void Post(const parser::FunctionReference &fr) {
7211     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
7212   }
7213   void Post(const parser::CallStmt &cs) {
7214     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
7215   }
7216 
7217 private:
7218   ResolveNamesVisitor &resolver_;
7219 };
7220 
7221 // Build the scope tree and resolve names in the specification parts of this
7222 // node and its children
7223 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
7224   if (node.isSpecificationPartResolved()) {
7225     return; // been here already
7226   }
7227   node.set_isSpecificationPartResolved();
7228   if (!BeginScopeForNode(node)) {
7229     return; // an error prevented scope from being created
7230   }
7231   Scope &scope{currScope()};
7232   node.set_scope(scope);
7233   AddSubpNames(node);
7234   std::visit(
7235       [&](const auto *x) {
7236         if (x) {
7237           Walk(*x);
7238         }
7239       },
7240       node.stmt());
7241   Walk(node.spec());
7242   // If this is a function, convert result to an object. This is to prevent the
7243   // result from being converted later to a function symbol if it is called
7244   // inside the function.
7245   // If the result is function pointer, then ConvertToObjectEntity will not
7246   // convert the result to an object, and calling the symbol inside the function
7247   // will result in calls to the result pointer.
7248   // A function cannot be called recursively if RESULT was not used to define a
7249   // distinct result name (15.6.2.2 point 4.).
7250   if (Symbol * symbol{scope.symbol()}) {
7251     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
7252       if (details->isFunction()) {
7253         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
7254       }
7255     }
7256   }
7257   if (node.IsModule()) {
7258     ApplyDefaultAccess();
7259   }
7260   for (auto &child : node.children()) {
7261     ResolveSpecificationParts(child);
7262   }
7263   ExecutionPartSkimmer{*this}.Walk(node.exec());
7264   EndScopeForNode(node);
7265   // Ensure that every object entity has a type.
7266   for (auto &pair : *node.scope()) {
7267     ApplyImplicitRules(*pair.second);
7268   }
7269 }
7270 
7271 // Add SubprogramNameDetails symbols for module and internal subprograms and
7272 // their ENTRY statements.
7273 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
7274   auto kind{
7275       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
7276   for (auto &child : node.children()) {
7277     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
7278     auto childKind{child.GetKind()};
7279     if (childKind == ProgramTree::Kind::Function) {
7280       symbol.set(Symbol::Flag::Function);
7281     } else if (childKind == ProgramTree::Kind::Subroutine) {
7282       symbol.set(Symbol::Flag::Subroutine);
7283     }
7284     for (const auto &entryStmt : child.entryStmts()) {
7285       SubprogramNameDetails details{kind, child};
7286       details.set_isEntryStmt();
7287       auto &symbol{
7288           MakeSymbol(std::get<parser::Name>(entryStmt->t), std::move(details))};
7289       symbol.set(child.GetSubpFlag());
7290     }
7291   }
7292   for (const auto &generic : node.genericSpecs()) {
7293     if (const auto *name{std::get_if<parser::Name>(&generic->u)}) {
7294       if (currScope().find(name->source) != currScope().end()) {
7295         // If this scope has both a generic interface and a contained
7296         // subprogram with the same name, create the generic's symbol
7297         // now so that any other generics of the same name that are pulled
7298         // into scope later via USE association will properly merge instead
7299         // of raising a bogus error due a conflict with the subprogram.
7300         CreateGeneric(*generic);
7301       }
7302     }
7303   }
7304 }
7305 
7306 // Push a new scope for this node or return false on error.
7307 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
7308   switch (node.GetKind()) {
7309     SWITCH_COVERS_ALL_CASES
7310   case ProgramTree::Kind::Program:
7311     PushScope(Scope::Kind::MainProgram,
7312         &MakeSymbol(node.name(), MainProgramDetails{}));
7313     return true;
7314   case ProgramTree::Kind::Function:
7315   case ProgramTree::Kind::Subroutine:
7316     return BeginSubprogram(
7317         node.name(), node.GetSubpFlag(), node.HasModulePrefix());
7318   case ProgramTree::Kind::MpSubprogram:
7319     return BeginMpSubprogram(node.name());
7320   case ProgramTree::Kind::Module:
7321     BeginModule(node.name(), false);
7322     return true;
7323   case ProgramTree::Kind::Submodule:
7324     return BeginSubmodule(node.name(), node.GetParentId());
7325   case ProgramTree::Kind::BlockData:
7326     PushBlockDataScope(node.name());
7327     return true;
7328   }
7329 }
7330 
7331 void ResolveNamesVisitor::EndScopeForNode(const ProgramTree &node) {
7332   EndSubprogram();
7333 }
7334 
7335 // Some analyses and checks, such as the processing of initializers of
7336 // pointers, are deferred until all of the pertinent specification parts
7337 // have been visited.  This deferred processing enables the use of forward
7338 // references in these circumstances.
7339 class DeferredCheckVisitor {
7340 public:
7341   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
7342       : resolver_{resolver} {}
7343 
7344   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
7345 
7346   template <typename A> bool Pre(const A &) { return true; }
7347   template <typename A> void Post(const A &) {}
7348 
7349   void Post(const parser::DerivedTypeStmt &x) {
7350     const auto &name{std::get<parser::Name>(x.t)};
7351     if (Symbol * symbol{name.symbol}) {
7352       if (Scope * scope{symbol->scope()}) {
7353         if (scope->IsDerivedType()) {
7354           resolver_.PushScope(*scope);
7355           pushedScope_ = true;
7356         }
7357       }
7358     }
7359   }
7360   void Post(const parser::EndTypeStmt &) {
7361     if (pushedScope_) {
7362       resolver_.PopScope();
7363       pushedScope_ = false;
7364     }
7365   }
7366 
7367   void Post(const parser::ProcInterface &pi) {
7368     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
7369       resolver_.CheckExplicitInterface(*name);
7370     }
7371   }
7372   bool Pre(const parser::EntityDecl &decl) {
7373     Init(std::get<parser::Name>(decl.t),
7374         std::get<std::optional<parser::Initialization>>(decl.t));
7375     return false;
7376   }
7377   bool Pre(const parser::ComponentDecl &decl) {
7378     Init(std::get<parser::Name>(decl.t),
7379         std::get<std::optional<parser::Initialization>>(decl.t));
7380     return false;
7381   }
7382   bool Pre(const parser::ProcDecl &decl) {
7383     if (const auto &init{
7384             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
7385       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
7386     }
7387     return false;
7388   }
7389   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
7390     resolver_.CheckExplicitInterface(tbps.interfaceName);
7391   }
7392   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
7393     if (pushedScope_) {
7394       resolver_.CheckBindings(tbps);
7395     }
7396   }
7397 
7398 private:
7399   void Init(const parser::Name &name,
7400       const std::optional<parser::Initialization> &init) {
7401     if (init) {
7402       if (const auto *target{
7403               std::get_if<parser::InitialDataTarget>(&init->u)}) {
7404         resolver_.PointerInitialization(name, *target);
7405       }
7406     }
7407   }
7408 
7409   ResolveNamesVisitor &resolver_;
7410   bool pushedScope_{false};
7411 };
7412 
7413 // Perform checks and completions that need to happen after all of
7414 // the specification parts but before any of the execution parts.
7415 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
7416   if (!node.scope()) {
7417     return; // error occurred creating scope
7418   }
7419   SetScope(*node.scope());
7420   // The initializers of pointers, the default initializers of pointer
7421   // components, and non-deferred type-bound procedure bindings have not
7422   // yet been traversed.
7423   // We do that now, when any (formerly) forward references that appear
7424   // in those initializers will resolve to the right symbols without
7425   // incurring spurious errors with IMPLICIT NONE.
7426   DeferredCheckVisitor{*this}.Walk(node.spec());
7427   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
7428   for (Scope &childScope : currScope().children()) {
7429     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
7430       FinishDerivedTypeInstantiation(childScope);
7431     }
7432   }
7433   for (const auto &child : node.children()) {
7434     FinishSpecificationParts(child);
7435   }
7436 }
7437 
7438 // Duplicate and fold component object pointer default initializer designators
7439 // using the actual type parameter values of each particular instantiation.
7440 // Validation is done later in declaration checking.
7441 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
7442   CHECK(scope.IsDerivedType() && !scope.symbol());
7443   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
7444     spec->Instantiate(currScope());
7445     const Symbol &origTypeSymbol{spec->typeSymbol()};
7446     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
7447       CHECK(origTypeScope->IsDerivedType() &&
7448           origTypeScope->symbol() == &origTypeSymbol);
7449       auto &foldingContext{GetFoldingContext()};
7450       auto restorer{foldingContext.WithPDTInstance(*spec)};
7451       for (auto &pair : scope) {
7452         Symbol &comp{*pair.second};
7453         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
7454         if (IsPointer(comp)) {
7455           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
7456             auto origDetails{origComp.get<ObjectEntityDetails>()};
7457             if (const MaybeExpr & init{origDetails.init()}) {
7458               SomeExpr newInit{*init};
7459               MaybeExpr folded{
7460                   evaluate::Fold(foldingContext, std::move(newInit))};
7461               details->set_init(std::move(folded));
7462             }
7463           }
7464         }
7465       }
7466     }
7467   }
7468 }
7469 
7470 // Resolve names in the execution part of this node and its children
7471 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
7472   if (!node.scope()) {
7473     return; // error occurred creating scope
7474   }
7475   SetScope(*node.scope());
7476   if (const auto *exec{node.exec()}) {
7477     Walk(*exec);
7478   }
7479   FinishNamelists();
7480   PopScope(); // converts unclassified entities into objects
7481   for (const auto &child : node.children()) {
7482     ResolveExecutionParts(child);
7483   }
7484 }
7485 
7486 void ResolveNamesVisitor::Post(const parser::Program &) {
7487   // ensure that all temps were deallocated
7488   CHECK(!attrs_);
7489   CHECK(!GetDeclTypeSpec());
7490 }
7491 
7492 // A singleton instance of the scope -> IMPLICIT rules mapping is
7493 // shared by all instances of ResolveNamesVisitor and accessed by this
7494 // pointer when the visitors (other than the top-level original) are
7495 // constructed.
7496 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7497 
7498 bool ResolveNames(
7499     SemanticsContext &context, const parser::Program &program, Scope &top) {
7500   ImplicitRulesMap implicitRulesMap;
7501   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7502   ResolveNamesVisitor{context, implicitRulesMap, top}.Walk(program);
7503   return !context.AnyFatalError();
7504 }
7505 
7506 // Processes a module (but not internal) function when it is referenced
7507 // in a specification expression in a sibling procedure.
7508 void ResolveSpecificationParts(
7509     SemanticsContext &context, const Symbol &subprogram) {
7510   auto originalLocation{context.location()};
7511   ImplicitRulesMap implicitRulesMap;
7512   bool localImplicitRulesMap{false};
7513   if (!sharedImplicitRulesMap) {
7514     sharedImplicitRulesMap = &implicitRulesMap;
7515     localImplicitRulesMap = true;
7516   }
7517   ResolveNamesVisitor visitor{
7518       context, *sharedImplicitRulesMap, context.globalScope()};
7519   const auto &details{subprogram.get<SubprogramNameDetails>()};
7520   ProgramTree &node{details.node()};
7521   const Scope &moduleScope{subprogram.owner()};
7522   if (localImplicitRulesMap) {
7523     visitor.BeginScope(const_cast<Scope &>(moduleScope));
7524   } else {
7525     visitor.SetScope(const_cast<Scope &>(moduleScope));
7526   }
7527   visitor.ResolveSpecificationParts(node);
7528   context.set_location(std::move(originalLocation));
7529   if (localImplicitRulesMap) {
7530     sharedImplicitRulesMap = nullptr;
7531   }
7532 }
7533 
7534 } // namespace Fortran::semantics
7535