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 
56 // ImplicitRules maps initial character of identifier to the DeclTypeSpec
57 // representing the implicit type; std::nullopt if none.
58 // It also records the presence of IMPLICIT NONE statements.
59 // When inheritFromParent is set, defaults come from the parent rules.
60 class ImplicitRules {
61 public:
62   ImplicitRules(SemanticsContext &context, ImplicitRules *parent)
63       : parent_{parent}, context_{context} {
64     inheritFromParent_ = parent != nullptr;
65   }
66   bool isImplicitNoneType() const;
67   bool isImplicitNoneExternal() const;
68   void set_isImplicitNoneType(bool x) { isImplicitNoneType_ = x; }
69   void set_isImplicitNoneExternal(bool x) { isImplicitNoneExternal_ = x; }
70   void set_inheritFromParent(bool x) { inheritFromParent_ = x; }
71   // Get the implicit type for this name. May be null.
72   const DeclTypeSpec *GetType(
73       SourceName, bool respectImplicitNone = true) const;
74   // Record the implicit type for the range of characters [fromLetter,
75   // toLetter].
76   void SetTypeMapping(const DeclTypeSpec &type, parser::Location fromLetter,
77       parser::Location toLetter);
78 
79 private:
80   static char Incr(char ch);
81 
82   ImplicitRules *parent_;
83   SemanticsContext &context_;
84   bool inheritFromParent_{false}; // look in parent if not specified here
85   bool isImplicitNoneType_{
86       context_.IsEnabled(common::LanguageFeature::ImplicitNoneTypeAlways)};
87   bool isImplicitNoneExternal_{false};
88   // map_ contains the mapping between letters and types that were defined
89   // by the IMPLICIT statements of the related scope. It does not contain
90   // the default Fortran mappings nor the mapping defined in parents.
91   std::map<char, common::Reference<const DeclTypeSpec>> map_;
92 
93   friend llvm::raw_ostream &operator<<(
94       llvm::raw_ostream &, const ImplicitRules &);
95   friend void ShowImplicitRule(
96       llvm::raw_ostream &, const ImplicitRules &, char);
97 };
98 
99 // scope -> implicit rules for that scope
100 using ImplicitRulesMap = std::map<const Scope *, ImplicitRules>;
101 
102 // Track statement source locations and save messages.
103 class MessageHandler {
104 public:
105   MessageHandler() { DIE("MessageHandler: default-constructed"); }
106   explicit MessageHandler(SemanticsContext &c) : context_{&c} {}
107   Messages &messages() { return context_->messages(); };
108   const std::optional<SourceName> &currStmtSource() {
109     return context_->location();
110   }
111   void set_currStmtSource(const std::optional<SourceName> &source) {
112     context_->set_location(source);
113   }
114 
115   // Emit a message associated with the current statement source.
116   Message &Say(MessageFixedText &&);
117   Message &Say(MessageFormattedText &&);
118   // Emit a message about a SourceName
119   Message &Say(const SourceName &, MessageFixedText &&);
120   // Emit a formatted message associated with a source location.
121   template <typename... A>
122   Message &Say(const SourceName &source, MessageFixedText &&msg, A &&...args) {
123     return context_->Say(source, std::move(msg), std::forward<A>(args)...);
124   }
125 
126 private:
127   SemanticsContext *context_;
128 };
129 
130 // Inheritance graph for the parse tree visitation classes that follow:
131 //   BaseVisitor
132 //   + AttrsVisitor
133 //   | + DeclTypeSpecVisitor
134 //   |   + ImplicitRulesVisitor
135 //   |     + ScopeHandler -----------+--+
136 //   |       + ModuleVisitor ========|==+
137 //   |       + InterfaceVisitor      |  |
138 //   |       +-+ SubprogramVisitor ==|==+
139 //   + ArraySpecVisitor              |  |
140 //     + DeclarationVisitor <--------+  |
141 //       + ConstructVisitor             |
142 //         + ResolveNamesVisitor <------+
143 
144 class BaseVisitor {
145 public:
146   BaseVisitor() { DIE("BaseVisitor: default-constructed"); }
147   BaseVisitor(
148       SemanticsContext &c, ResolveNamesVisitor &v, ImplicitRulesMap &rules)
149       : implicitRulesMap_{&rules}, this_{&v}, context_{&c}, messageHandler_{c} {
150   }
151   template <typename T> void Walk(const T &);
152 
153   MessageHandler &messageHandler() { return messageHandler_; }
154   const std::optional<SourceName> &currStmtSource() {
155     return context_->location();
156   }
157   SemanticsContext &context() const { return *context_; }
158   evaluate::FoldingContext &GetFoldingContext() const {
159     return context_->foldingContext();
160   }
161   bool IsIntrinsic(
162       const SourceName &name, std::optional<Symbol::Flag> flag) const {
163     if (!flag) {
164       return context_->intrinsics().IsIntrinsic(name.ToString());
165     } else if (flag == Symbol::Flag::Function) {
166       return context_->intrinsics().IsIntrinsicFunction(name.ToString());
167     } else if (flag == Symbol::Flag::Subroutine) {
168       return context_->intrinsics().IsIntrinsicSubroutine(name.ToString());
169     } else {
170       DIE("expected Subroutine or Function flag");
171     }
172   }
173 
174   // Make a placeholder symbol for a Name that otherwise wouldn't have one.
175   // It is not in any scope and always has MiscDetails.
176   void MakePlaceholder(const parser::Name &, MiscDetails::Kind);
177 
178   template <typename T> common::IfNoLvalue<T, T> FoldExpr(T &&expr) {
179     return evaluate::Fold(GetFoldingContext(), std::move(expr));
180   }
181 
182   template <typename T> MaybeExpr EvaluateExpr(const T &expr) {
183     return FoldExpr(AnalyzeExpr(*context_, expr));
184   }
185 
186   template <typename T>
187   MaybeExpr EvaluateNonPointerInitializer(
188       const Symbol &symbol, const T &expr, parser::CharBlock source) {
189     if (!context().HasError(symbol)) {
190       if (auto maybeExpr{AnalyzeExpr(*context_, expr)}) {
191         auto restorer{GetFoldingContext().messages().SetLocation(source)};
192         return evaluate::NonPointerInitializationExpr(
193             symbol, std::move(*maybeExpr), GetFoldingContext());
194       }
195     }
196     return std::nullopt;
197   }
198 
199   template <typename T> MaybeIntExpr EvaluateIntExpr(const T &expr) {
200     return semantics::EvaluateIntExpr(*context_, expr);
201   }
202 
203   template <typename T>
204   MaybeSubscriptIntExpr EvaluateSubscriptIntExpr(const T &expr) {
205     if (MaybeIntExpr maybeIntExpr{EvaluateIntExpr(expr)}) {
206       return FoldExpr(evaluate::ConvertToType<evaluate::SubscriptInteger>(
207           std::move(*maybeIntExpr)));
208     } else {
209       return std::nullopt;
210     }
211   }
212 
213   template <typename... A> Message &Say(A &&...args) {
214     return messageHandler_.Say(std::forward<A>(args)...);
215   }
216   template <typename... A>
217   Message &Say(
218       const parser::Name &name, MessageFixedText &&text, const A &...args) {
219     return messageHandler_.Say(name.source, std::move(text), args...);
220   }
221 
222 protected:
223   ImplicitRulesMap *implicitRulesMap_{nullptr};
224 
225 private:
226   ResolveNamesVisitor *this_;
227   SemanticsContext *context_;
228   MessageHandler messageHandler_;
229 };
230 
231 // Provide Post methods to collect attributes into a member variable.
232 class AttrsVisitor : public virtual BaseVisitor {
233 public:
234   bool BeginAttrs(); // always returns true
235   Attrs GetAttrs();
236   Attrs EndAttrs();
237   bool SetPassNameOn(Symbol &);
238   void SetBindNameOn(Symbol &);
239   void Post(const parser::LanguageBindingSpec &);
240   bool Pre(const parser::IntentSpec &);
241   bool Pre(const parser::Pass &);
242 
243   bool CheckAndSet(Attr);
244 
245 // Simple case: encountering CLASSNAME causes ATTRNAME to be set.
246 #define HANDLE_ATTR_CLASS(CLASSNAME, ATTRNAME) \
247   bool Pre(const parser::CLASSNAME &) { \
248     CheckAndSet(Attr::ATTRNAME); \
249     return false; \
250   }
251   HANDLE_ATTR_CLASS(PrefixSpec::Elemental, ELEMENTAL)
252   HANDLE_ATTR_CLASS(PrefixSpec::Impure, IMPURE)
253   HANDLE_ATTR_CLASS(PrefixSpec::Module, MODULE)
254   HANDLE_ATTR_CLASS(PrefixSpec::Non_Recursive, NON_RECURSIVE)
255   HANDLE_ATTR_CLASS(PrefixSpec::Pure, PURE)
256   HANDLE_ATTR_CLASS(PrefixSpec::Recursive, RECURSIVE)
257   HANDLE_ATTR_CLASS(TypeAttrSpec::BindC, BIND_C)
258   HANDLE_ATTR_CLASS(BindAttr::Deferred, DEFERRED)
259   HANDLE_ATTR_CLASS(BindAttr::Non_Overridable, NON_OVERRIDABLE)
260   HANDLE_ATTR_CLASS(Abstract, ABSTRACT)
261   HANDLE_ATTR_CLASS(Allocatable, ALLOCATABLE)
262   HANDLE_ATTR_CLASS(Asynchronous, ASYNCHRONOUS)
263   HANDLE_ATTR_CLASS(Contiguous, CONTIGUOUS)
264   HANDLE_ATTR_CLASS(External, EXTERNAL)
265   HANDLE_ATTR_CLASS(Intrinsic, INTRINSIC)
266   HANDLE_ATTR_CLASS(NoPass, NOPASS)
267   HANDLE_ATTR_CLASS(Optional, OPTIONAL)
268   HANDLE_ATTR_CLASS(Parameter, PARAMETER)
269   HANDLE_ATTR_CLASS(Pointer, POINTER)
270   HANDLE_ATTR_CLASS(Protected, PROTECTED)
271   HANDLE_ATTR_CLASS(Save, SAVE)
272   HANDLE_ATTR_CLASS(Target, TARGET)
273   HANDLE_ATTR_CLASS(Value, VALUE)
274   HANDLE_ATTR_CLASS(Volatile, VOLATILE)
275 #undef HANDLE_ATTR_CLASS
276 
277 protected:
278   std::optional<Attrs> attrs_;
279 
280   Attr AccessSpecToAttr(const parser::AccessSpec &x) {
281     switch (x.v) {
282     case parser::AccessSpec::Kind::Public:
283       return Attr::PUBLIC;
284     case parser::AccessSpec::Kind::Private:
285       return Attr::PRIVATE;
286     }
287     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
288   }
289   Attr IntentSpecToAttr(const parser::IntentSpec &x) {
290     switch (x.v) {
291     case parser::IntentSpec::Intent::In:
292       return Attr::INTENT_IN;
293     case parser::IntentSpec::Intent::Out:
294       return Attr::INTENT_OUT;
295     case parser::IntentSpec::Intent::InOut:
296       return Attr::INTENT_INOUT;
297     }
298     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
299   }
300 
301 private:
302   bool IsDuplicateAttr(Attr);
303   bool HaveAttrConflict(Attr, Attr, Attr);
304   bool IsConflictingAttr(Attr);
305 
306   MaybeExpr bindName_; // from BIND(C, NAME="...")
307   std::optional<SourceName> passName_; // from PASS(...)
308 };
309 
310 // Find and create types from declaration-type-spec nodes.
311 class DeclTypeSpecVisitor : public AttrsVisitor {
312 public:
313   using AttrsVisitor::Post;
314   using AttrsVisitor::Pre;
315   void Post(const parser::IntrinsicTypeSpec::DoublePrecision &);
316   void Post(const parser::IntrinsicTypeSpec::DoubleComplex &);
317   void Post(const parser::DeclarationTypeSpec::ClassStar &);
318   void Post(const parser::DeclarationTypeSpec::TypeStar &);
319   bool Pre(const parser::TypeGuardStmt &);
320   void Post(const parser::TypeGuardStmt &);
321   void Post(const parser::TypeSpec &);
322 
323 protected:
324   struct State {
325     bool expectDeclTypeSpec{false}; // should see decl-type-spec only when true
326     const DeclTypeSpec *declTypeSpec{nullptr};
327     struct {
328       DerivedTypeSpec *type{nullptr};
329       DeclTypeSpec::Category category{DeclTypeSpec::TypeDerived};
330     } derived;
331     bool allowForwardReferenceToDerivedType{false};
332   };
333 
334   bool allowForwardReferenceToDerivedType() const {
335     return state_.allowForwardReferenceToDerivedType;
336   }
337   void set_allowForwardReferenceToDerivedType(bool yes) {
338     state_.allowForwardReferenceToDerivedType = yes;
339   }
340 
341   // Walk the parse tree of a type spec and return the DeclTypeSpec for it.
342   template <typename T>
343   const DeclTypeSpec *ProcessTypeSpec(const T &x, bool allowForward = false) {
344     auto restorer{common::ScopedSet(state_, State{})};
345     set_allowForwardReferenceToDerivedType(allowForward);
346     BeginDeclTypeSpec();
347     Walk(x);
348     const auto *type{GetDeclTypeSpec()};
349     EndDeclTypeSpec();
350     return type;
351   }
352 
353   const DeclTypeSpec *GetDeclTypeSpec();
354   void BeginDeclTypeSpec();
355   void EndDeclTypeSpec();
356   void SetDeclTypeSpec(const DeclTypeSpec &);
357   void SetDeclTypeSpecCategory(DeclTypeSpec::Category);
358   DeclTypeSpec::Category GetDeclTypeSpecCategory() const {
359     return state_.derived.category;
360   }
361   KindExpr GetKindParamExpr(
362       TypeCategory, const std::optional<parser::KindSelector> &);
363   void CheckForAbstractType(const Symbol &typeSymbol);
364 
365 private:
366   State state_;
367 
368   void MakeNumericType(TypeCategory, int kind);
369 };
370 
371 // Visit ImplicitStmt and related parse tree nodes and updates implicit rules.
372 class ImplicitRulesVisitor : public DeclTypeSpecVisitor {
373 public:
374   using DeclTypeSpecVisitor::Post;
375   using DeclTypeSpecVisitor::Pre;
376   using ImplicitNoneNameSpec = parser::ImplicitStmt::ImplicitNoneNameSpec;
377 
378   void Post(const parser::ParameterStmt &);
379   bool Pre(const parser::ImplicitStmt &);
380   bool Pre(const parser::LetterSpec &);
381   bool Pre(const parser::ImplicitSpec &);
382   void Post(const parser::ImplicitSpec &);
383 
384   const DeclTypeSpec *GetType(
385       SourceName name, bool respectImplicitNoneType = true) {
386     return implicitRules_->GetType(name, respectImplicitNoneType);
387   }
388   bool isImplicitNoneType() const {
389     return implicitRules_->isImplicitNoneType();
390   }
391   bool isImplicitNoneType(const Scope &scope) const {
392     return implicitRulesMap_->at(&scope).isImplicitNoneType();
393   }
394   bool isImplicitNoneExternal() const {
395     return implicitRules_->isImplicitNoneExternal();
396   }
397   void set_inheritFromParent(bool x) {
398     implicitRules_->set_inheritFromParent(x);
399   }
400 
401 protected:
402   void BeginScope(const Scope &);
403   void SetScope(const Scope &);
404 
405 private:
406   // implicit rules in effect for current scope
407   ImplicitRules *implicitRules_{nullptr};
408   std::optional<SourceName> prevImplicit_;
409   std::optional<SourceName> prevImplicitNone_;
410   std::optional<SourceName> prevImplicitNoneType_;
411   std::optional<SourceName> prevParameterStmt_;
412 
413   bool HandleImplicitNone(const std::list<ImplicitNoneNameSpec> &nameSpecs);
414 };
415 
416 // Track array specifications. They can occur in AttrSpec, EntityDecl,
417 // ObjectDecl, DimensionStmt, CommonBlockObject, or BasedPointerStmt.
418 // 1. INTEGER, DIMENSION(10) :: x
419 // 2. INTEGER :: x(10)
420 // 3. ALLOCATABLE :: x(:)
421 // 4. DIMENSION :: x(10)
422 // 5. COMMON x(10)
423 // 6. BasedPointerStmt
424 class ArraySpecVisitor : public virtual BaseVisitor {
425 public:
426   void Post(const parser::ArraySpec &);
427   void Post(const parser::ComponentArraySpec &);
428   void Post(const parser::CoarraySpec &);
429   void Post(const parser::AttrSpec &) { PostAttrSpec(); }
430   void Post(const parser::ComponentAttrSpec &) { PostAttrSpec(); }
431 
432 protected:
433   const ArraySpec &arraySpec();
434   void set_arraySpec(const ArraySpec arraySpec) { arraySpec_ = arraySpec; }
435   const ArraySpec &coarraySpec();
436   void BeginArraySpec();
437   void EndArraySpec();
438   void ClearArraySpec() { arraySpec_.clear(); }
439   void ClearCoarraySpec() { coarraySpec_.clear(); }
440 
441 private:
442   // arraySpec_/coarraySpec_ are populated from any ArraySpec/CoarraySpec
443   ArraySpec arraySpec_;
444   ArraySpec coarraySpec_;
445   // When an ArraySpec is under an AttrSpec or ComponentAttrSpec, it is moved
446   // into attrArraySpec_
447   ArraySpec attrArraySpec_;
448   ArraySpec attrCoarraySpec_;
449 
450   void PostAttrSpec();
451 };
452 
453 // Manage a stack of Scopes
454 class ScopeHandler : public ImplicitRulesVisitor {
455 public:
456   using ImplicitRulesVisitor::Post;
457   using ImplicitRulesVisitor::Pre;
458 
459   Scope &currScope() { return DEREF(currScope_); }
460   // The enclosing host procedure if current scope is in an internal procedure
461   Scope *GetHostProcedure();
462   // The enclosing scope, skipping blocks and derived types.
463   // TODO: Will return the scope of a FORALL or implied DO loop; is this ok?
464   // If not, should call FindProgramUnitContaining() instead.
465   Scope &InclusiveScope();
466   // The enclosing scope, skipping derived types.
467   Scope &NonDerivedTypeScope();
468 
469   // Create a new scope and push it on the scope stack.
470   void PushScope(Scope::Kind kind, Symbol *symbol);
471   void PushScope(Scope &scope);
472   void PopScope();
473   void SetScope(Scope &);
474 
475   template <typename T> bool Pre(const parser::Statement<T> &x) {
476     messageHandler().set_currStmtSource(x.source);
477     currScope_->AddSourceRange(x.source);
478     return true;
479   }
480   template <typename T> void Post(const parser::Statement<T> &) {
481     messageHandler().set_currStmtSource(std::nullopt);
482   }
483 
484   // Special messages: already declared; referencing symbol's declaration;
485   // about a type; two names & locations
486   void SayAlreadyDeclared(const parser::Name &, Symbol &);
487   void SayAlreadyDeclared(const SourceName &, Symbol &);
488   void SayAlreadyDeclared(const SourceName &, const SourceName &);
489   void SayWithReason(
490       const parser::Name &, Symbol &, MessageFixedText &&, MessageFixedText &&);
491   void SayWithDecl(const parser::Name &, Symbol &, MessageFixedText &&);
492   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
493   void SayDerivedType(const SourceName &, MessageFixedText &&, const Scope &);
494   void Say2(const SourceName &, MessageFixedText &&, const SourceName &,
495       MessageFixedText &&);
496   void Say2(
497       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
498   void Say2(
499       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
500 
501   // Search for symbol by name in current, parent derived type, and
502   // containing scopes
503   Symbol *FindSymbol(const parser::Name &);
504   Symbol *FindSymbol(const Scope &, const parser::Name &);
505   // Search for name only in scope, not in enclosing scopes.
506   Symbol *FindInScope(const Scope &, const parser::Name &);
507   Symbol *FindInScope(const Scope &, const SourceName &);
508   template <typename T> Symbol *FindInScope(const T &name) {
509     return FindInScope(currScope(), name);
510   }
511   // Search for name in a derived type scope and its parents.
512   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
513   Symbol *FindInTypeOrParents(const parser::Name &);
514   void EraseSymbol(const parser::Name &);
515   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
516   // Make a new symbol with the name and attrs of an existing one
517   Symbol &CopySymbol(const SourceName &, const Symbol &);
518 
519   // Make symbols in the current or named scope
520   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
521   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
522   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
523   Symbol &MakeHostAssocSymbol(const parser::Name &, const Symbol &);
524 
525   template <typename D>
526   common::IfNoLvalue<Symbol &, D> MakeSymbol(
527       const parser::Name &name, D &&details) {
528     return MakeSymbol(name, Attrs{}, std::move(details));
529   }
530 
531   template <typename D>
532   common::IfNoLvalue<Symbol &, D> MakeSymbol(
533       const parser::Name &name, const Attrs &attrs, D &&details) {
534     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
535   }
536 
537   template <typename D>
538   common::IfNoLvalue<Symbol &, D> MakeSymbol(
539       const SourceName &name, const Attrs &attrs, D &&details) {
540     // Note: don't use FindSymbol here. If this is a derived type scope,
541     // we want to detect whether the name is already declared as a component.
542     auto *symbol{FindInScope(name)};
543     if (!symbol) {
544       symbol = &MakeSymbol(name, attrs);
545       symbol->set_details(std::move(details));
546       return *symbol;
547     }
548     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
549       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
550         if (!d->specific()) {
551           // derived type with same name as a generic
552           auto *derivedType{d->derivedType()};
553           if (!derivedType) {
554             derivedType =
555                 &currScope().MakeSymbol(name, attrs, std::move(details));
556             d->set_derivedType(*derivedType);
557           } else {
558             SayAlreadyDeclared(name, *derivedType);
559           }
560           return *derivedType;
561         }
562       }
563     }
564     if (symbol->CanReplaceDetails(details)) {
565       // update the existing symbol
566       symbol->attrs() |= attrs;
567       symbol->set_details(std::move(details));
568       return *symbol;
569     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
570       symbol->attrs() |= attrs;
571       return *symbol;
572     } else {
573       if (!CheckPossibleBadForwardRef(*symbol)) {
574         SayAlreadyDeclared(name, *symbol);
575       }
576       // replace the old symbol with a new one with correct details
577       EraseSymbol(*symbol);
578       auto &result{MakeSymbol(name, attrs, std::move(details))};
579       context().SetError(result);
580       return result;
581     }
582   }
583 
584   void MakeExternal(Symbol &);
585 
586 protected:
587   // Apply the implicit type rules to this symbol.
588   void ApplyImplicitRules(Symbol &, bool allowForwardReference = false);
589   bool ImplicitlyTypeForwardRef(Symbol &);
590   void AcquireIntrinsicProcedureFlags(Symbol &);
591   const DeclTypeSpec *GetImplicitType(
592       Symbol &, bool respectImplicitNoneType = true);
593   bool ConvertToObjectEntity(Symbol &);
594   bool ConvertToProcEntity(Symbol &);
595 
596   const DeclTypeSpec &MakeNumericType(
597       TypeCategory, const std::optional<parser::KindSelector> &);
598   const DeclTypeSpec &MakeLogicalType(
599       const std::optional<parser::KindSelector> &);
600   void NotePossibleBadForwardRef(const parser::Name &);
601   std::optional<SourceName> HadForwardRef(const Symbol &) const;
602   bool CheckPossibleBadForwardRef(const Symbol &);
603 
604   bool inExecutionPart_{false};
605   bool inSpecificationPart_{false};
606   bool inEquivalenceStmt_{false};
607 
608   // Some information is collected from a specification part for deferred
609   // processing in DeclarationPartVisitor functions (e.g., CheckSaveStmts())
610   // that are called by ResolveNamesVisitor::FinishSpecificationPart().  Since
611   // specification parts can nest (e.g., INTERFACE bodies), the collected
612   // information that is not contained in the scope needs to be packaged
613   // and restorable.
614   struct SpecificationPartState {
615     std::set<SourceName> forwardRefs;
616     // Collect equivalence sets and process at end of specification part
617     std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets;
618     // Names of all common block objects in the scope
619     std::set<SourceName> commonBlockObjects;
620     // Info about about SAVE statements and attributes in current scope
621     struct {
622       std::optional<SourceName> saveAll; // "SAVE" without entity list
623       std::set<SourceName> entities; // names of entities with save attr
624       std::set<SourceName> commons; // names of common blocks with save attr
625     } saveInfo;
626   } specPartState_;
627 
628 private:
629   Scope *currScope_{nullptr};
630 };
631 
632 class ModuleVisitor : public virtual ScopeHandler {
633 public:
634   bool Pre(const parser::AccessStmt &);
635   bool Pre(const parser::Only &);
636   bool Pre(const parser::Rename::Names &);
637   bool Pre(const parser::Rename::Operators &);
638   bool Pre(const parser::UseStmt &);
639   void Post(const parser::UseStmt &);
640 
641   void BeginModule(const parser::Name &, bool isSubmodule);
642   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
643   void ApplyDefaultAccess();
644   void AddGenericUse(GenericDetails &, const SourceName &, const Symbol &);
645 
646 private:
647   // The default access spec for this module.
648   Attr defaultAccess_{Attr::PUBLIC};
649   // The location of the last AccessStmt without access-ids, if any.
650   std::optional<SourceName> prevAccessStmt_;
651   // The scope of the module during a UseStmt
652   Scope *useModuleScope_{nullptr};
653 
654   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
655   // A rename in a USE statement: local => use
656   struct SymbolRename {
657     Symbol *local{nullptr};
658     Symbol *use{nullptr};
659   };
660   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
661   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
662   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
663   void DoAddUse(const SourceName &, const SourceName &, Symbol &localSymbol,
664       const Symbol &useSymbol);
665   void AddUse(const GenericSpecInfo &);
666   Scope *FindModule(const parser::Name &, Scope *ancestor = nullptr);
667 };
668 
669 class InterfaceVisitor : public virtual ScopeHandler {
670 public:
671   bool Pre(const parser::InterfaceStmt &);
672   void Post(const parser::InterfaceStmt &);
673   void Post(const parser::EndInterfaceStmt &);
674   bool Pre(const parser::GenericSpec &);
675   bool Pre(const parser::ProcedureStmt &);
676   bool Pre(const parser::GenericStmt &);
677   void Post(const parser::GenericStmt &);
678 
679   bool inInterfaceBlock() const;
680   bool isGeneric() const;
681   bool isAbstract() const;
682 
683 protected:
684   Symbol &GetGenericSymbol() {
685     return DEREF(genericInfo_.top().symbol);
686   }
687   // Add to generic the symbol for the subprogram with the same name
688   void CheckGenericProcedures(Symbol &);
689 
690 private:
691   // A new GenericInfo is pushed for each interface block and generic stmt
692   struct GenericInfo {
693     GenericInfo(bool isInterface, bool isAbstract = false)
694         : isInterface{isInterface}, isAbstract{isAbstract} {}
695     bool isInterface; // in interface block
696     bool isAbstract; // in abstract interface block
697     Symbol *symbol{nullptr}; // the generic symbol being defined
698   };
699   std::stack<GenericInfo> genericInfo_;
700   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
701   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
702 
703   using ProcedureKind = parser::ProcedureStmt::Kind;
704   // mapping of generic to its specific proc names and kinds
705   std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>
706       specificProcs_;
707 
708   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
709   void ResolveSpecificsInGeneric(Symbol &generic);
710 };
711 
712 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
713 public:
714   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
715   bool Pre(const parser::SubroutineStmt &);
716   void Post(const parser::SubroutineStmt &);
717   bool Pre(const parser::FunctionStmt &);
718   void Post(const parser::FunctionStmt &);
719   bool Pre(const parser::EntryStmt &);
720   void Post(const parser::EntryStmt &);
721   bool Pre(const parser::InterfaceBody::Subroutine &);
722   void Post(const parser::InterfaceBody::Subroutine &);
723   bool Pre(const parser::InterfaceBody::Function &);
724   void Post(const parser::InterfaceBody::Function &);
725   bool Pre(const parser::Suffix &);
726   bool Pre(const parser::PrefixSpec &);
727   void Post(const parser::ImplicitPart &);
728 
729   bool BeginSubprogram(
730       const parser::Name &, Symbol::Flag, bool hasModulePrefix = false);
731   bool BeginMpSubprogram(const parser::Name &);
732   void PushBlockDataScope(const parser::Name &);
733   void EndSubprogram();
734 
735 protected:
736   // Set when we see a stmt function that is really an array element assignment
737   bool badStmtFuncFound_{false};
738 
739 private:
740   // Info about the current function: parse tree of the type in the PrefixSpec;
741   // name and symbol of the function result from the Suffix; source location.
742   struct {
743     const parser::DeclarationTypeSpec *parsedType{nullptr};
744     const parser::Name *resultName{nullptr};
745     Symbol *resultSymbol{nullptr};
746     std::optional<SourceName> source;
747   } funcInfo_;
748 
749   // Edits an existing symbol created for earlier calls to a subprogram or ENTRY
750   // so that it can be replaced by a later definition.
751   bool HandlePreviousCalls(const parser::Name &, Symbol &, Symbol::Flag);
752   // Create a subprogram symbol in the current scope and push a new scope.
753   void CheckExtantProc(const parser::Name &, Symbol::Flag);
754   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag);
755   Symbol *GetSpecificFromGeneric(const parser::Name &);
756   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
757 };
758 
759 class DeclarationVisitor : public ArraySpecVisitor,
760                            public virtual ScopeHandler {
761 public:
762   using ArraySpecVisitor::Post;
763   using ScopeHandler::Post;
764   using ScopeHandler::Pre;
765 
766   bool Pre(const parser::Initialization &);
767   void Post(const parser::EntityDecl &);
768   void Post(const parser::ObjectDecl &);
769   void Post(const parser::PointerDecl &);
770   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
771   void Post(const parser::BindStmt &) { EndAttrs(); }
772   bool Pre(const parser::BindEntity &);
773   bool Pre(const parser::OldParameterStmt &);
774   bool Pre(const parser::NamedConstantDef &);
775   bool Pre(const parser::NamedConstant &);
776   void Post(const parser::EnumDef &);
777   bool Pre(const parser::Enumerator &);
778   bool Pre(const parser::AccessSpec &);
779   bool Pre(const parser::AsynchronousStmt &);
780   bool Pre(const parser::ContiguousStmt &);
781   bool Pre(const parser::ExternalStmt &);
782   bool Pre(const parser::IntentStmt &);
783   bool Pre(const parser::IntrinsicStmt &);
784   bool Pre(const parser::OptionalStmt &);
785   bool Pre(const parser::ProtectedStmt &);
786   bool Pre(const parser::ValueStmt &);
787   bool Pre(const parser::VolatileStmt &);
788   bool Pre(const parser::AllocatableStmt &) {
789     objectDeclAttr_ = Attr::ALLOCATABLE;
790     return true;
791   }
792   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
793   bool Pre(const parser::TargetStmt &) {
794     objectDeclAttr_ = Attr::TARGET;
795     return true;
796   }
797   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
798   void Post(const parser::DimensionStmt::Declaration &);
799   void Post(const parser::CodimensionDecl &);
800   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
801   void Post(const parser::TypeDeclarationStmt &);
802   void Post(const parser::IntegerTypeSpec &);
803   void Post(const parser::IntrinsicTypeSpec::Real &);
804   void Post(const parser::IntrinsicTypeSpec::Complex &);
805   void Post(const parser::IntrinsicTypeSpec::Logical &);
806   void Post(const parser::IntrinsicTypeSpec::Character &);
807   void Post(const parser::CharSelector::LengthAndKind &);
808   void Post(const parser::CharLength &);
809   void Post(const parser::LengthSelector &);
810   bool Pre(const parser::KindParam &);
811   bool Pre(const parser::DeclarationTypeSpec::Type &);
812   void Post(const parser::DeclarationTypeSpec::Type &);
813   bool Pre(const parser::DeclarationTypeSpec::Class &);
814   void Post(const parser::DeclarationTypeSpec::Class &);
815   bool Pre(const parser::DeclarationTypeSpec::Record &);
816   void Post(const parser::DerivedTypeSpec &);
817   bool Pre(const parser::DerivedTypeDef &);
818   bool Pre(const parser::DerivedTypeStmt &);
819   void Post(const parser::DerivedTypeStmt &);
820   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
821   void Post(const parser::TypeParamDefStmt &);
822   bool Pre(const parser::TypeAttrSpec::Extends &);
823   bool Pre(const parser::PrivateStmt &);
824   bool Pre(const parser::SequenceStmt &);
825   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
826   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
827   void Post(const parser::ComponentDecl &);
828   bool Pre(const parser::ProcedureDeclarationStmt &);
829   void Post(const parser::ProcedureDeclarationStmt &);
830   bool Pre(const parser::DataComponentDefStmt &); // returns false
831   bool Pre(const parser::ProcComponentDefStmt &);
832   void Post(const parser::ProcComponentDefStmt &);
833   bool Pre(const parser::ProcPointerInit &);
834   void Post(const parser::ProcInterface &);
835   void Post(const parser::ProcDecl &);
836   bool Pre(const parser::TypeBoundProcedurePart &);
837   void Post(const parser::TypeBoundProcedurePart &);
838   void Post(const parser::ContainsStmt &);
839   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
840   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
841   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
842   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
843   void Post(const parser::FinalProcedureStmt &);
844   bool Pre(const parser::TypeBoundGenericStmt &);
845   bool Pre(const parser::AllocateStmt &);
846   void Post(const parser::AllocateStmt &);
847   bool Pre(const parser::StructureConstructor &);
848   bool Pre(const parser::NamelistStmt::Group &);
849   bool Pre(const parser::IoControlSpec &);
850   bool Pre(const parser::CommonStmt::Block &);
851   bool Pre(const parser::CommonBlockObject &);
852   void Post(const parser::CommonBlockObject &);
853   bool Pre(const parser::EquivalenceStmt &);
854   bool Pre(const parser::SaveStmt &);
855   bool Pre(const parser::BasedPointerStmt &);
856 
857   void PointerInitialization(
858       const parser::Name &, const parser::InitialDataTarget &);
859   void PointerInitialization(
860       const parser::Name &, const parser::ProcPointerInit &);
861   void NonPointerInitialization(
862       const parser::Name &, const parser::ConstantExpr &);
863   void CheckExplicitInterface(const parser::Name &);
864   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
865 
866   const parser::Name *ResolveDesignator(const parser::Designator &);
867 
868 protected:
869   bool BeginDecl();
870   void EndDecl();
871   Symbol &DeclareObjectEntity(const parser::Name &, Attrs = Attrs{});
872   // Make sure that there's an entity in an enclosing scope called Name
873   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
874   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
875   // it comes from the entity in the containing scope, or implicit rules.
876   // Return pointer to the new symbol, or nullptr on error.
877   Symbol *DeclareLocalEntity(const parser::Name &);
878   // Declare a statement entity (e.g., an implied DO loop index).
879   // If there isn't a type specified, implicit rules apply.
880   // Return pointer to the new symbol, or nullptr on error.
881   Symbol *DeclareStatementEntity(
882       const parser::Name &, const std::optional<parser::IntegerTypeSpec> &);
883   Symbol &MakeCommonBlockSymbol(const parser::Name &);
884   Symbol &MakeCommonBlockSymbol(const std::optional<parser::Name> &);
885   bool CheckUseError(const parser::Name &);
886   void CheckAccessibility(const SourceName &, bool, Symbol &);
887   void CheckCommonBlocks();
888   void CheckSaveStmts();
889   void CheckEquivalenceSets();
890   bool CheckNotInBlock(const char *);
891   bool NameIsKnownOrIntrinsic(const parser::Name &);
892 
893   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
894   // or nullptr in case of error.
895   const parser::Name *ResolveStructureComponent(
896       const parser::StructureComponent &);
897   const parser::Name *ResolveDataRef(const parser::DataRef &);
898   const parser::Name *ResolveName(const parser::Name &);
899   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
900   Symbol *NoteInterfaceName(const parser::Name &);
901 
902 private:
903   // The attribute corresponding to the statement containing an ObjectDecl
904   std::optional<Attr> objectDeclAttr_;
905   // Info about current character type while walking DeclTypeSpec.
906   // Also captures any "*length" specifier on an individual declaration.
907   struct {
908     std::optional<ParamValue> length;
909     std::optional<KindExpr> kind;
910   } charInfo_;
911   // Info about current derived type while walking DerivedTypeDef
912   struct {
913     const parser::Name *extends{nullptr}; // EXTENDS(name)
914     bool privateComps{false}; // components are private by default
915     bool privateBindings{false}; // bindings are private by default
916     bool sawContains{false}; // currently processing bindings
917     bool sequence{false}; // is a sequence type
918     const Symbol *type{nullptr}; // derived type being defined
919   } derivedTypeInfo_;
920   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
921   // the interface name, if any.
922   const parser::Name *interfaceName_{nullptr};
923   // Map type-bound generic to binding names of its specific bindings
924   std::multimap<Symbol *, const parser::Name *> genericBindings_;
925   // Info about current ENUM
926   struct EnumeratorState {
927     // Enum value must hold inside a C_INT (7.6.2).
928     std::optional<int> value{0};
929   } enumerationState_;
930   // Set for OldParameterStmt processing
931   bool inOldStyleParameterStmt_{false};
932 
933   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
934   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
935   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
936   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
937   void SetType(const parser::Name &, const DeclTypeSpec &);
938   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
939   std::optional<DerivedTypeSpec> ResolveExtendsType(
940       const parser::Name &, const parser::Name *);
941   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
942   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
943   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
944   ParamValue GetParamValue(
945       const parser::TypeParamValue &, common::TypeParamAttr attr);
946   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
947   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
948   Attrs HandleSaveName(const SourceName &, Attrs);
949   void AddSaveName(std::set<SourceName> &, const SourceName &);
950   void SetSaveAttr(Symbol &);
951   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
952   bool IsUplevelReference(const Symbol &);
953   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
954   void Initialization(const parser::Name &, const parser::Initialization &,
955       bool inComponentDecl);
956   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
957   bool CheckForHostAssociatedImplicit(const parser::Name &);
958 
959   // Declare an object or procedure entity.
960   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
961   template <typename T>
962   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
963     Symbol &symbol{MakeSymbol(name, attrs)};
964     if (context().HasError(symbol) || symbol.has<T>()) {
965       return symbol; // OK or error already reported
966     } else if (symbol.has<UnknownDetails>()) {
967       symbol.set_details(T{});
968       return symbol;
969     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
970       symbol.set_details(T{std::move(*details)});
971       return symbol;
972     } else if (std::is_same_v<EntityDetails, T> &&
973         (symbol.has<ObjectEntityDetails>() ||
974             symbol.has<ProcEntityDetails>())) {
975       return symbol; // OK
976     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
977       Say(name.source,
978           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
979           name.source, GetUsedModule(*details).name());
980     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
981       if (details->kind() == SubprogramKind::Module) {
982         Say2(name,
983             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
984             symbol, "Module procedure definition"_en_US);
985       } else if (details->kind() == SubprogramKind::Internal) {
986         Say2(name,
987             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
988             symbol, "Internal procedure definition"_en_US);
989       } else {
990         DIE("unexpected kind");
991       }
992     } else if (std::is_same_v<ObjectEntityDetails, T> &&
993         symbol.has<ProcEntityDetails>()) {
994       SayWithDecl(
995           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
996     } else if (std::is_same_v<ProcEntityDetails, T> &&
997         symbol.has<ObjectEntityDetails>()) {
998       if (InCommonBlock(symbol)) {
999         SayWithDecl(name, symbol,
1000             "'%s' may not be a procedure as it is in a COMMON block"_err_en_US);
1001       } else {
1002         SayWithDecl(
1003             name, symbol, "'%s' is already declared as an object"_err_en_US);
1004       }
1005     } else if (!CheckPossibleBadForwardRef(symbol)) {
1006       SayAlreadyDeclared(name, symbol);
1007     }
1008     context().SetError(symbol);
1009     return symbol;
1010   }
1011   bool HasCycle(const Symbol &, const ProcInterface &);
1012 };
1013 
1014 // Resolve construct entities and statement entities.
1015 // Check that construct names don't conflict with other names.
1016 class ConstructVisitor : public virtual DeclarationVisitor {
1017 public:
1018   bool Pre(const parser::ConcurrentHeader &);
1019   bool Pre(const parser::LocalitySpec::Local &);
1020   bool Pre(const parser::LocalitySpec::LocalInit &);
1021   bool Pre(const parser::LocalitySpec::Shared &);
1022   bool Pre(const parser::AcSpec &);
1023   bool Pre(const parser::AcImpliedDo &);
1024   bool Pre(const parser::DataImpliedDo &);
1025   bool Pre(const parser::DataIDoObject &);
1026   bool Pre(const parser::DataStmtObject &);
1027   bool Pre(const parser::DataStmtValue &);
1028   bool Pre(const parser::DoConstruct &);
1029   void Post(const parser::DoConstruct &);
1030   bool Pre(const parser::ForallConstruct &);
1031   void Post(const parser::ForallConstruct &);
1032   bool Pre(const parser::ForallStmt &);
1033   void Post(const parser::ForallStmt &);
1034   bool Pre(const parser::BlockStmt &);
1035   bool Pre(const parser::EndBlockStmt &);
1036   void Post(const parser::Selector &);
1037   void Post(const parser::AssociateStmt &);
1038   void Post(const parser::EndAssociateStmt &);
1039   bool Pre(const parser::Association &);
1040   void Post(const parser::SelectTypeStmt &);
1041   void Post(const parser::SelectRankStmt &);
1042   bool Pre(const parser::SelectTypeConstruct &);
1043   void Post(const parser::SelectTypeConstruct &);
1044   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
1045   void Post(const parser::SelectTypeConstruct::TypeCase &);
1046   // Creates Block scopes with neither symbol name nor symbol details.
1047   bool Pre(const parser::SelectRankConstruct::RankCase &);
1048   void Post(const parser::SelectRankConstruct::RankCase &);
1049   void Post(const parser::TypeGuardStmt::Guard &);
1050   void Post(const parser::SelectRankCaseStmt::Rank &);
1051   bool Pre(const parser::ChangeTeamStmt &);
1052   void Post(const parser::EndChangeTeamStmt &);
1053   void Post(const parser::CoarrayAssociation &);
1054 
1055   // Definitions of construct names
1056   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1057   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1058   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1059   bool Pre(const parser::LabelDoStmt &) {
1060     return false; // error recovery
1061   }
1062   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1063   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1064   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1065   bool Pre(const parser::SelectRankConstruct &);
1066   void Post(const parser::SelectRankConstruct &);
1067   bool Pre(const parser::SelectRankStmt &x) {
1068     return CheckDef(std::get<0>(x.t));
1069   }
1070   bool Pre(const parser::SelectTypeStmt &x) {
1071     return CheckDef(std::get<0>(x.t));
1072   }
1073 
1074   // References to construct names
1075   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1076   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1077   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1078   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1079   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1080   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1081   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1082   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1083   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1084   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1085   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1086   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1087   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1088   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1089   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1090 
1091 private:
1092   // R1105 selector -> expr | variable
1093   // expr is set in either case unless there were errors
1094   struct Selector {
1095     Selector() {}
1096     Selector(const SourceName &source, MaybeExpr &&expr)
1097         : source{source}, expr{std::move(expr)} {}
1098     operator bool() const { return expr.has_value(); }
1099     parser::CharBlock source;
1100     MaybeExpr expr;
1101   };
1102   // association -> [associate-name =>] selector
1103   struct Association {
1104     const parser::Name *name{nullptr};
1105     Selector selector;
1106   };
1107   std::vector<Association> associationStack_;
1108   Association *currentAssociation_{nullptr};
1109 
1110   template <typename T> bool CheckDef(const T &t) {
1111     return CheckDef(std::get<std::optional<parser::Name>>(t));
1112   }
1113   template <typename T> void CheckRef(const T &t) {
1114     CheckRef(std::get<std::optional<parser::Name>>(t));
1115   }
1116   bool CheckDef(const std::optional<parser::Name> &);
1117   void CheckRef(const std::optional<parser::Name> &);
1118   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1119   const DeclTypeSpec &ToDeclTypeSpec(
1120       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1121   Symbol *MakeAssocEntity();
1122   void SetTypeFromAssociation(Symbol &);
1123   void SetAttrsFromAssociation(Symbol &);
1124   Selector ResolveSelector(const parser::Selector &);
1125   void ResolveIndexName(const parser::ConcurrentControl &control);
1126   void SetCurrentAssociation(std::size_t n);
1127   Association &GetCurrentAssociation();
1128   void PushAssociation();
1129   void PopAssociation(std::size_t count = 1);
1130 };
1131 
1132 // Create scopes for OpenACC constructs
1133 class AccVisitor : public virtual DeclarationVisitor {
1134 public:
1135   void AddAccSourceRange(const parser::CharBlock &);
1136 
1137   static bool NeedsScope(const parser::OpenACCBlockConstruct &);
1138 
1139   bool Pre(const parser::OpenACCBlockConstruct &);
1140   void Post(const parser::OpenACCBlockConstruct &);
1141   bool Pre(const parser::AccBeginBlockDirective &x) {
1142     AddAccSourceRange(x.source);
1143     return true;
1144   }
1145   void Post(const parser::AccBeginBlockDirective &) {
1146     messageHandler().set_currStmtSource(std::nullopt);
1147   }
1148   bool Pre(const parser::AccEndBlockDirective &x) {
1149     AddAccSourceRange(x.source);
1150     return true;
1151   }
1152   void Post(const parser::AccEndBlockDirective &) {
1153     messageHandler().set_currStmtSource(std::nullopt);
1154   }
1155   bool Pre(const parser::AccBeginLoopDirective &x) {
1156     AddAccSourceRange(x.source);
1157     return true;
1158   }
1159   void Post(const parser::AccBeginLoopDirective &x) {
1160     messageHandler().set_currStmtSource(std::nullopt);
1161   }
1162 };
1163 
1164 bool AccVisitor::NeedsScope(const parser::OpenACCBlockConstruct &x) {
1165   const auto &beginBlockDir{std::get<parser::AccBeginBlockDirective>(x.t)};
1166   const auto &beginDir{std::get<parser::AccBlockDirective>(beginBlockDir.t)};
1167   switch (beginDir.v) {
1168   case llvm::acc::Directive::ACCD_data:
1169   case llvm::acc::Directive::ACCD_host_data:
1170   case llvm::acc::Directive::ACCD_kernels:
1171   case llvm::acc::Directive::ACCD_parallel:
1172   case llvm::acc::Directive::ACCD_serial:
1173     return true;
1174   default:
1175     return false;
1176   }
1177 }
1178 
1179 void AccVisitor::AddAccSourceRange(const parser::CharBlock &source) {
1180   messageHandler().set_currStmtSource(source);
1181   currScope().AddSourceRange(source);
1182 }
1183 
1184 bool AccVisitor::Pre(const parser::OpenACCBlockConstruct &x) {
1185   if (NeedsScope(x)) {
1186     PushScope(Scope::Kind::Block, nullptr);
1187   }
1188   return true;
1189 }
1190 
1191 void AccVisitor::Post(const parser::OpenACCBlockConstruct &x) {
1192   if (NeedsScope(x)) {
1193     PopScope();
1194   }
1195 }
1196 
1197 // Create scopes for OpenMP constructs
1198 class OmpVisitor : public virtual DeclarationVisitor {
1199 public:
1200   void AddOmpSourceRange(const parser::CharBlock &);
1201 
1202   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1203 
1204   bool Pre(const parser::OpenMPBlockConstruct &);
1205   void Post(const parser::OpenMPBlockConstruct &);
1206   bool Pre(const parser::OmpBeginBlockDirective &x) {
1207     AddOmpSourceRange(x.source);
1208     return true;
1209   }
1210   void Post(const parser::OmpBeginBlockDirective &) {
1211     messageHandler().set_currStmtSource(std::nullopt);
1212   }
1213   bool Pre(const parser::OmpEndBlockDirective &x) {
1214     AddOmpSourceRange(x.source);
1215     return true;
1216   }
1217   void Post(const parser::OmpEndBlockDirective &) {
1218     messageHandler().set_currStmtSource(std::nullopt);
1219   }
1220 
1221   bool Pre(const parser::OpenMPLoopConstruct &) {
1222     PushScope(Scope::Kind::Block, nullptr);
1223     return true;
1224   }
1225   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1226   bool Pre(const parser::OmpBeginLoopDirective &x) {
1227     AddOmpSourceRange(x.source);
1228     return true;
1229   }
1230   void Post(const parser::OmpBeginLoopDirective &) {
1231     messageHandler().set_currStmtSource(std::nullopt);
1232   }
1233   bool Pre(const parser::OmpEndLoopDirective &x) {
1234     AddOmpSourceRange(x.source);
1235     return true;
1236   }
1237   void Post(const parser::OmpEndLoopDirective &) {
1238     messageHandler().set_currStmtSource(std::nullopt);
1239   }
1240 
1241   bool Pre(const parser::OpenMPSectionsConstruct &) {
1242     PushScope(Scope::Kind::Block, nullptr);
1243     return true;
1244   }
1245   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1246   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1247     AddOmpSourceRange(x.source);
1248     return true;
1249   }
1250   void Post(const parser::OmpBeginSectionsDirective &) {
1251     messageHandler().set_currStmtSource(std::nullopt);
1252   }
1253   bool Pre(const parser::OmpEndSectionsDirective &x) {
1254     AddOmpSourceRange(x.source);
1255     return true;
1256   }
1257   void Post(const parser::OmpEndSectionsDirective &) {
1258     messageHandler().set_currStmtSource(std::nullopt);
1259   }
1260 };
1261 
1262 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1263   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1264   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1265   switch (beginDir.v) {
1266   case llvm::omp::Directive::OMPD_target_data:
1267   case llvm::omp::Directive::OMPD_master:
1268   case llvm::omp::Directive::OMPD_ordered:
1269     return false;
1270   default:
1271     return true;
1272   }
1273 }
1274 
1275 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1276   messageHandler().set_currStmtSource(source);
1277   currScope().AddSourceRange(source);
1278 }
1279 
1280 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1281   if (NeedsScope(x)) {
1282     PushScope(Scope::Kind::Block, nullptr);
1283   }
1284   return true;
1285 }
1286 
1287 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1288   if (NeedsScope(x)) {
1289     PopScope();
1290   }
1291 }
1292 
1293 // Walk the parse tree and resolve names to symbols.
1294 class ResolveNamesVisitor : public virtual ScopeHandler,
1295                             public ModuleVisitor,
1296                             public SubprogramVisitor,
1297                             public ConstructVisitor,
1298                             public OmpVisitor,
1299                             public AccVisitor {
1300 public:
1301   using AccVisitor::Post;
1302   using AccVisitor::Pre;
1303   using ArraySpecVisitor::Post;
1304   using ConstructVisitor::Post;
1305   using ConstructVisitor::Pre;
1306   using DeclarationVisitor::Post;
1307   using DeclarationVisitor::Pre;
1308   using ImplicitRulesVisitor::Post;
1309   using ImplicitRulesVisitor::Pre;
1310   using InterfaceVisitor::Post;
1311   using InterfaceVisitor::Pre;
1312   using ModuleVisitor::Post;
1313   using ModuleVisitor::Pre;
1314   using OmpVisitor::Post;
1315   using OmpVisitor::Pre;
1316   using ScopeHandler::Post;
1317   using ScopeHandler::Pre;
1318   using SubprogramVisitor::Post;
1319   using SubprogramVisitor::Pre;
1320 
1321   ResolveNamesVisitor(SemanticsContext &context, ImplicitRulesMap &rules)
1322       : BaseVisitor{context, *this, rules} {
1323     PushScope(context.globalScope());
1324   }
1325 
1326   // Default action for a parse tree node is to visit children.
1327   template <typename T> bool Pre(const T &) { return true; }
1328   template <typename T> void Post(const T &) {}
1329 
1330   bool Pre(const parser::SpecificationPart &);
1331   void Post(const parser::Program &);
1332   bool Pre(const parser::ImplicitStmt &);
1333   void Post(const parser::PointerObject &);
1334   void Post(const parser::AllocateObject &);
1335   bool Pre(const parser::PointerAssignmentStmt &);
1336   void Post(const parser::Designator &);
1337   template <typename A, typename B>
1338   void Post(const parser::LoopBounds<A, B> &x) {
1339     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1340   }
1341   void Post(const parser::ProcComponentRef &);
1342   bool Pre(const parser::FunctionReference &);
1343   bool Pre(const parser::CallStmt &);
1344   bool Pre(const parser::ImportStmt &);
1345   void Post(const parser::TypeGuardStmt &);
1346   bool Pre(const parser::StmtFunctionStmt &);
1347   bool Pre(const parser::DefinedOpName &);
1348   bool Pre(const parser::ProgramUnit &);
1349   void Post(const parser::AssignStmt &);
1350   void Post(const parser::AssignedGotoStmt &);
1351 
1352   // These nodes should never be reached: they are handled in ProgramUnit
1353   bool Pre(const parser::MainProgram &) {
1354     llvm_unreachable("This node is handled in ProgramUnit");
1355   }
1356   bool Pre(const parser::FunctionSubprogram &) {
1357     llvm_unreachable("This node is handled in ProgramUnit");
1358   }
1359   bool Pre(const parser::SubroutineSubprogram &) {
1360     llvm_unreachable("This node is handled in ProgramUnit");
1361   }
1362   bool Pre(const parser::SeparateModuleSubprogram &) {
1363     llvm_unreachable("This node is handled in ProgramUnit");
1364   }
1365   bool Pre(const parser::Module &) {
1366     llvm_unreachable("This node is handled in ProgramUnit");
1367   }
1368   bool Pre(const parser::Submodule &) {
1369     llvm_unreachable("This node is handled in ProgramUnit");
1370   }
1371   bool Pre(const parser::BlockData &) {
1372     llvm_unreachable("This node is handled in ProgramUnit");
1373   }
1374 
1375   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1376 
1377   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1378 
1379 private:
1380   // Kind of procedure we are expecting to see in a ProcedureDesignator
1381   std::optional<Symbol::Flag> expectedProcFlag_;
1382   std::optional<SourceName> prevImportStmt_;
1383 
1384   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1385   void CreateCommonBlockSymbols(const parser::CommonStmt &);
1386   void CreateGeneric(const parser::GenericSpec &);
1387   void FinishSpecificationPart(const std::list<parser::DeclarationConstruct> &);
1388   void AnalyzeStmtFunctionStmt(const parser::StmtFunctionStmt &);
1389   void CheckImports();
1390   void CheckImport(const SourceName &, const SourceName &);
1391   void HandleCall(Symbol::Flag, const parser::Call &);
1392   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1393   bool CheckImplicitNoneExternal(const SourceName &, const Symbol &);
1394   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1395   void ResolveSpecificationParts(ProgramTree &);
1396   void AddSubpNames(ProgramTree &);
1397   bool BeginScopeForNode(const ProgramTree &);
1398   void FinishSpecificationParts(const ProgramTree &);
1399   void FinishDerivedTypeInstantiation(Scope &);
1400   void ResolveExecutionParts(const ProgramTree &);
1401 };
1402 
1403 // ImplicitRules implementation
1404 
1405 bool ImplicitRules::isImplicitNoneType() const {
1406   if (isImplicitNoneType_) {
1407     return true;
1408   } else if (map_.empty() && inheritFromParent_) {
1409     return parent_->isImplicitNoneType();
1410   } else {
1411     return false; // default if not specified
1412   }
1413 }
1414 
1415 bool ImplicitRules::isImplicitNoneExternal() const {
1416   if (isImplicitNoneExternal_) {
1417     return true;
1418   } else if (inheritFromParent_) {
1419     return parent_->isImplicitNoneExternal();
1420   } else {
1421     return false; // default if not specified
1422   }
1423 }
1424 
1425 const DeclTypeSpec *ImplicitRules::GetType(
1426     SourceName name, bool respectImplicitNoneType) const {
1427   char ch{name.begin()[0]};
1428   if (isImplicitNoneType_ && respectImplicitNoneType) {
1429     return nullptr;
1430   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1431     return &*it->second;
1432   } else if (inheritFromParent_) {
1433     return parent_->GetType(name, respectImplicitNoneType);
1434   } else if (ch >= 'i' && ch <= 'n') {
1435     return &context_.MakeNumericType(TypeCategory::Integer);
1436   } else if (ch >= 'a' && ch <= 'z') {
1437     return &context_.MakeNumericType(TypeCategory::Real);
1438   } else {
1439     return nullptr;
1440   }
1441 }
1442 
1443 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1444     parser::Location fromLetter, parser::Location toLetter) {
1445   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1446     auto res{map_.emplace(ch, type)};
1447     if (!res.second) {
1448       context_.Say(parser::CharBlock{fromLetter},
1449           "More than one implicit type specified for '%c'"_err_en_US, ch);
1450     }
1451     if (ch == *toLetter) {
1452       break;
1453     }
1454   }
1455 }
1456 
1457 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1458 // Return '\0' for the char after 'z'.
1459 char ImplicitRules::Incr(char ch) {
1460   switch (ch) {
1461   case 'i':
1462     return 'j';
1463   case 'r':
1464     return 's';
1465   case 'z':
1466     return '\0';
1467   default:
1468     return ch + 1;
1469   }
1470 }
1471 
1472 llvm::raw_ostream &operator<<(
1473     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1474   o << "ImplicitRules:\n";
1475   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1476     ShowImplicitRule(o, implicitRules, ch);
1477   }
1478   ShowImplicitRule(o, implicitRules, '_');
1479   ShowImplicitRule(o, implicitRules, '$');
1480   ShowImplicitRule(o, implicitRules, '@');
1481   return o;
1482 }
1483 void ShowImplicitRule(
1484     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1485   auto it{implicitRules.map_.find(ch)};
1486   if (it != implicitRules.map_.end()) {
1487     o << "  " << ch << ": " << *it->second << '\n';
1488   }
1489 }
1490 
1491 template <typename T> void BaseVisitor::Walk(const T &x) {
1492   parser::Walk(x, *this_);
1493 }
1494 
1495 void BaseVisitor::MakePlaceholder(
1496     const parser::Name &name, MiscDetails::Kind kind) {
1497   if (!name.symbol) {
1498     name.symbol = &context_->globalScope().MakeSymbol(
1499         name.source, Attrs{}, MiscDetails{kind});
1500   }
1501 }
1502 
1503 // AttrsVisitor implementation
1504 
1505 bool AttrsVisitor::BeginAttrs() {
1506   CHECK(!attrs_);
1507   attrs_ = std::make_optional<Attrs>();
1508   return true;
1509 }
1510 Attrs AttrsVisitor::GetAttrs() {
1511   CHECK(attrs_);
1512   return *attrs_;
1513 }
1514 Attrs AttrsVisitor::EndAttrs() {
1515   Attrs result{GetAttrs()};
1516   attrs_.reset();
1517   passName_ = std::nullopt;
1518   bindName_.reset();
1519   return result;
1520 }
1521 
1522 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1523   if (!passName_) {
1524     return false;
1525   }
1526   std::visit(common::visitors{
1527                  [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1528                  [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1529                  [](auto &) { common::die("unexpected pass name"); },
1530              },
1531       symbol.details());
1532   return true;
1533 }
1534 
1535 void AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1536   if (!attrs_ || !attrs_->test(Attr::BIND_C)) {
1537     return;
1538   }
1539   std::optional<std::string> label{evaluate::GetScalarConstantValue<
1540       evaluate::Type<TypeCategory::Character, 1>>(bindName_)};
1541   // 18.9.2(2): discard leading and trailing blanks, ignore if all blank
1542   if (label) {
1543     auto first{label->find_first_not_of(" ")};
1544     if (first == std::string::npos) {
1545       // Empty NAME= means no binding at all (18.10.2p2)
1546       Say(currStmtSource().value(), "Blank binding label ignored"_en_US);
1547       return;
1548     }
1549     auto last{label->find_last_not_of(" ")};
1550     label = label->substr(first, last - first + 1);
1551   } else {
1552     label = parser::ToLowerCaseLetters(symbol.name().ToString());
1553   }
1554   symbol.SetBindName(std::move(*label));
1555 }
1556 
1557 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1558   CHECK(attrs_);
1559   if (CheckAndSet(Attr::BIND_C)) {
1560     if (x.v) {
1561       bindName_ = EvaluateExpr(*x.v);
1562     }
1563   }
1564 }
1565 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1566   CHECK(attrs_);
1567   CheckAndSet(IntentSpecToAttr(x));
1568   return false;
1569 }
1570 bool AttrsVisitor::Pre(const parser::Pass &x) {
1571   if (CheckAndSet(Attr::PASS)) {
1572     if (x.v) {
1573       passName_ = x.v->source;
1574       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1575     }
1576   }
1577   return false;
1578 }
1579 
1580 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1581 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1582   if (attrs_->test(attrName)) {
1583     Say(currStmtSource().value(),
1584         "Attribute '%s' cannot be used more than once"_en_US,
1585         AttrToString(attrName));
1586     return true;
1587   }
1588   return false;
1589 }
1590 
1591 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1592 // name attributes that cannot be used on the same declaration
1593 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1594   if ((attrName == attr1 && attrs_->test(attr2)) ||
1595       (attrName == attr2 && attrs_->test(attr1))) {
1596     Say(currStmtSource().value(),
1597         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1598         AttrToString(attr1), AttrToString(attr2));
1599     return true;
1600   }
1601   return false;
1602 }
1603 // C759, C1543
1604 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1605   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1606       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1607       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1608       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) || // C781
1609       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1610       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1611       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1612 }
1613 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1614   CHECK(attrs_);
1615   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1616     return false;
1617   }
1618   attrs_->set(attrName);
1619   return true;
1620 }
1621 
1622 // DeclTypeSpecVisitor implementation
1623 
1624 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1625   return state_.declTypeSpec;
1626 }
1627 
1628 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1629   CHECK(!state_.expectDeclTypeSpec);
1630   CHECK(!state_.declTypeSpec);
1631   state_.expectDeclTypeSpec = true;
1632 }
1633 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1634   CHECK(state_.expectDeclTypeSpec);
1635   state_ = {};
1636 }
1637 
1638 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1639     DeclTypeSpec::Category category) {
1640   CHECK(state_.expectDeclTypeSpec);
1641   state_.derived.category = category;
1642 }
1643 
1644 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1645   BeginDeclTypeSpec();
1646   return true;
1647 }
1648 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1649   EndDeclTypeSpec();
1650 }
1651 
1652 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1653   // Record the resolved DeclTypeSpec in the parse tree for use by
1654   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1655   // The grammar ensures that it's an intrinsic or derived type spec,
1656   // not TYPE(*) or CLASS(*) or CLASS(T).
1657   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1658     switch (spec->category()) {
1659     case DeclTypeSpec::Numeric:
1660     case DeclTypeSpec::Logical:
1661     case DeclTypeSpec::Character:
1662       typeSpec.declTypeSpec = spec;
1663       break;
1664     case DeclTypeSpec::TypeDerived:
1665       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1666         CheckForAbstractType(derived->typeSymbol()); // C703
1667         typeSpec.declTypeSpec = spec;
1668       }
1669       break;
1670     default:
1671       CRASH_NO_CASE;
1672     }
1673   }
1674 }
1675 
1676 void DeclTypeSpecVisitor::Post(
1677     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1678   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1679 }
1680 void DeclTypeSpecVisitor::Post(
1681     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1682   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1683 }
1684 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1685   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1686 }
1687 
1688 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1689   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1690     Say("ABSTRACT derived type may not be used here"_err_en_US);
1691   }
1692 }
1693 
1694 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1695   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1696 }
1697 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1698   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1699 }
1700 
1701 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1702 // and save it in state_.declTypeSpec.
1703 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1704   CHECK(state_.expectDeclTypeSpec);
1705   CHECK(!state_.declTypeSpec);
1706   state_.declTypeSpec = &declTypeSpec;
1707 }
1708 
1709 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1710     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1711   return AnalyzeKindSelector(context(), category, kind);
1712 }
1713 
1714 // MessageHandler implementation
1715 
1716 Message &MessageHandler::Say(MessageFixedText &&msg) {
1717   return context_->Say(currStmtSource().value(), std::move(msg));
1718 }
1719 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1720   return context_->Say(currStmtSource().value(), std::move(msg));
1721 }
1722 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1723   return Say(name, std::move(msg), name);
1724 }
1725 
1726 // ImplicitRulesVisitor implementation
1727 
1728 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1729   prevParameterStmt_ = currStmtSource();
1730 }
1731 
1732 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1733   bool result{
1734       std::visit(common::visitors{
1735                      [&](const std::list<ImplicitNoneNameSpec> &y) {
1736                        return HandleImplicitNone(y);
1737                      },
1738                      [&](const std::list<parser::ImplicitSpec> &) {
1739                        if (prevImplicitNoneType_) {
1740                          Say("IMPLICIT statement after IMPLICIT NONE or "
1741                              "IMPLICIT NONE(TYPE) statement"_err_en_US);
1742                          return false;
1743                        }
1744                        implicitRules_->set_isImplicitNoneType(false);
1745                        return true;
1746                      },
1747                  },
1748           x.u)};
1749   prevImplicit_ = currStmtSource();
1750   return result;
1751 }
1752 
1753 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1754   auto loLoc{std::get<parser::Location>(x.t)};
1755   auto hiLoc{loLoc};
1756   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1757     hiLoc = *hiLocOpt;
1758     if (*hiLoc < *loLoc) {
1759       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1760           std::string(hiLoc, 1), std::string(loLoc, 1));
1761       return false;
1762     }
1763   }
1764   implicitRules_->SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1765   return false;
1766 }
1767 
1768 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1769   BeginDeclTypeSpec();
1770   set_allowForwardReferenceToDerivedType(true);
1771   return true;
1772 }
1773 
1774 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1775   EndDeclTypeSpec();
1776 }
1777 
1778 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1779   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1780   prevImplicit_ = std::nullopt;
1781   prevImplicitNone_ = std::nullopt;
1782   prevImplicitNoneType_ = std::nullopt;
1783   prevParameterStmt_ = std::nullopt;
1784 }
1785 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1786   // find or create implicit rules for this scope
1787   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1788   SetScope(scope);
1789 }
1790 
1791 // TODO: for all of these errors, reference previous statement too
1792 bool ImplicitRulesVisitor::HandleImplicitNone(
1793     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1794   if (prevImplicitNone_) {
1795     Say("More than one IMPLICIT NONE statement"_err_en_US);
1796     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1797     return false;
1798   }
1799   if (prevParameterStmt_) {
1800     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1801     return false;
1802   }
1803   prevImplicitNone_ = currStmtSource();
1804   bool implicitNoneTypeNever{
1805       context().IsEnabled(common::LanguageFeature::ImplicitNoneTypeNever)};
1806   if (nameSpecs.empty()) {
1807     if (!implicitNoneTypeNever) {
1808       prevImplicitNoneType_ = currStmtSource();
1809       implicitRules_->set_isImplicitNoneType(true);
1810       if (prevImplicit_) {
1811         Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1812         return false;
1813       }
1814     }
1815   } else {
1816     int sawType{0};
1817     int sawExternal{0};
1818     for (const auto noneSpec : nameSpecs) {
1819       switch (noneSpec) {
1820       case ImplicitNoneNameSpec::External:
1821         implicitRules_->set_isImplicitNoneExternal(true);
1822         ++sawExternal;
1823         break;
1824       case ImplicitNoneNameSpec::Type:
1825         if (!implicitNoneTypeNever) {
1826           prevImplicitNoneType_ = currStmtSource();
1827           implicitRules_->set_isImplicitNoneType(true);
1828           if (prevImplicit_) {
1829             Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1830             return false;
1831           }
1832           ++sawType;
1833         }
1834         break;
1835       }
1836     }
1837     if (sawType > 1) {
1838       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1839       return false;
1840     }
1841     if (sawExternal > 1) {
1842       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1843       return false;
1844     }
1845   }
1846   return true;
1847 }
1848 
1849 // ArraySpecVisitor implementation
1850 
1851 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1852   CHECK(arraySpec_.empty());
1853   arraySpec_ = AnalyzeArraySpec(context(), x);
1854 }
1855 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1856   CHECK(arraySpec_.empty());
1857   arraySpec_ = AnalyzeArraySpec(context(), x);
1858 }
1859 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1860   CHECK(coarraySpec_.empty());
1861   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1862 }
1863 
1864 const ArraySpec &ArraySpecVisitor::arraySpec() {
1865   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
1866 }
1867 const ArraySpec &ArraySpecVisitor::coarraySpec() {
1868   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
1869 }
1870 void ArraySpecVisitor::BeginArraySpec() {
1871   CHECK(arraySpec_.empty());
1872   CHECK(coarraySpec_.empty());
1873   CHECK(attrArraySpec_.empty());
1874   CHECK(attrCoarraySpec_.empty());
1875 }
1876 void ArraySpecVisitor::EndArraySpec() {
1877   CHECK(arraySpec_.empty());
1878   CHECK(coarraySpec_.empty());
1879   attrArraySpec_.clear();
1880   attrCoarraySpec_.clear();
1881 }
1882 void ArraySpecVisitor::PostAttrSpec() {
1883   // Save dimension/codimension from attrs so we can process array/coarray-spec
1884   // on the entity-decl
1885   if (!arraySpec_.empty()) {
1886     if (attrArraySpec_.empty()) {
1887       attrArraySpec_ = arraySpec_;
1888       arraySpec_.clear();
1889     } else {
1890       Say(currStmtSource().value(),
1891           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
1892     }
1893   }
1894   if (!coarraySpec_.empty()) {
1895     if (attrCoarraySpec_.empty()) {
1896       attrCoarraySpec_ = coarraySpec_;
1897       coarraySpec_.clear();
1898     } else {
1899       Say(currStmtSource().value(),
1900           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
1901     }
1902   }
1903 }
1904 
1905 // ScopeHandler implementation
1906 
1907 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
1908   SayAlreadyDeclared(name.source, prev);
1909 }
1910 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
1911   if (context().HasError(prev)) {
1912     // don't report another error about prev
1913   } else {
1914     if (const auto *details{prev.detailsIf<UseDetails>()}) {
1915       Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
1916           .Attach(details->location(),
1917               "It is use-associated with '%s' in module '%s'"_err_en_US,
1918               details->symbol().name(), GetUsedModule(*details).name());
1919     } else {
1920       SayAlreadyDeclared(name, prev.name());
1921     }
1922     context().SetError(prev);
1923   }
1924 }
1925 void ScopeHandler::SayAlreadyDeclared(
1926     const SourceName &name1, const SourceName &name2) {
1927   if (name1.begin() < name2.begin()) {
1928     SayAlreadyDeclared(name2, name1);
1929   } else {
1930     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
1931         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
1932   }
1933 }
1934 
1935 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
1936     MessageFixedText &&msg1, MessageFixedText &&msg2) {
1937   Say2(name, std::move(msg1), symbol, std::move(msg2));
1938   context().SetError(symbol, msg1.isFatal());
1939 }
1940 
1941 void ScopeHandler::SayWithDecl(
1942     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
1943   SayWithReason(name, symbol, std::move(msg),
1944       symbol.test(Symbol::Flag::Implicit) ? "Implicit declaration of '%s'"_en_US
1945                                           : "Declaration of '%s'"_en_US);
1946 }
1947 
1948 void ScopeHandler::SayLocalMustBeVariable(
1949     const parser::Name &name, Symbol &symbol) {
1950   SayWithDecl(name, symbol,
1951       "The name '%s' must be a variable to appear"
1952       " in a locality-spec"_err_en_US);
1953 }
1954 
1955 void ScopeHandler::SayDerivedType(
1956     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
1957   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
1958   Say(name, std::move(msg), name, typeSymbol.name())
1959       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
1960           typeSymbol.name());
1961 }
1962 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
1963     const SourceName &name2, MessageFixedText &&msg2) {
1964   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
1965 }
1966 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
1967     Symbol &symbol, MessageFixedText &&msg2) {
1968   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
1969   context().SetError(symbol, msg1.isFatal());
1970 }
1971 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
1972     Symbol &symbol, MessageFixedText &&msg2) {
1973   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
1974   context().SetError(symbol, msg1.isFatal());
1975 }
1976 
1977 // T may be `Scope` or `const Scope`
1978 template <typename T> static T &GetInclusiveScope(T &scope) {
1979   for (T *s{&scope}; !s->IsGlobal(); s = &s->parent()) {
1980     if (s->kind() != Scope::Kind::Block && !s->IsDerivedType() &&
1981         !s->IsStmtFunction()) {
1982       return *s;
1983     }
1984   }
1985   return scope;
1986 }
1987 
1988 Scope &ScopeHandler::InclusiveScope() { return GetInclusiveScope(currScope()); }
1989 
1990 Scope *ScopeHandler::GetHostProcedure() {
1991   Scope &parent{InclusiveScope().parent()};
1992   return parent.kind() == Scope::Kind::Subprogram ? &parent : nullptr;
1993 }
1994 
1995 Scope &ScopeHandler::NonDerivedTypeScope() {
1996   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
1997 }
1998 
1999 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2000   PushScope(currScope().MakeScope(kind, symbol));
2001 }
2002 void ScopeHandler::PushScope(Scope &scope) {
2003   currScope_ = &scope;
2004   auto kind{currScope_->kind()};
2005   if (kind != Scope::Kind::Block) {
2006     BeginScope(scope);
2007   }
2008   // The name of a module or submodule cannot be "used" in its scope,
2009   // as we read 19.3.1(2), so we allow the name to be used as a local
2010   // identifier in the module or submodule too.  Same with programs
2011   // (14.1(3)) and BLOCK DATA.
2012   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2013       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2014     if (auto *symbol{scope.symbol()}) {
2015       // Create a dummy symbol so we can't create another one with the same
2016       // name. It might already be there if we previously pushed the scope.
2017       if (!FindInScope(scope, symbol->name())) {
2018         auto &newSymbol{MakeSymbol(symbol->name())};
2019         if (kind == Scope::Kind::Subprogram) {
2020           // Allow for recursive references.  If this symbol is a function
2021           // without an explicit RESULT(), this new symbol will be discarded
2022           // and replaced with an object of the same name.
2023           newSymbol.set_details(HostAssocDetails{*symbol});
2024         } else {
2025           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2026         }
2027       }
2028     }
2029   }
2030 }
2031 void ScopeHandler::PopScope() {
2032   // Entities that are not yet classified as objects or procedures are now
2033   // assumed to be objects.
2034   // TODO: Statement functions
2035   for (auto &pair : currScope()) {
2036     ConvertToObjectEntity(*pair.second);
2037   }
2038   SetScope(currScope_->parent());
2039 }
2040 void ScopeHandler::SetScope(Scope &scope) {
2041   currScope_ = &scope;
2042   ImplicitRulesVisitor::SetScope(InclusiveScope());
2043 }
2044 
2045 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2046   return FindSymbol(currScope(), name);
2047 }
2048 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2049   if (scope.IsDerivedType()) {
2050     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2051       if (!symbol->has<ProcBindingDetails>() &&
2052           !symbol->test(Symbol::Flag::ParentComp)) {
2053         return Resolve(name, symbol);
2054       }
2055     }
2056     return FindSymbol(scope.parent(), name);
2057   } else {
2058     // In EQUIVALENCE statements only resolve names in the local scope, see
2059     // 19.5.1.4, paragraph 2, item (10)
2060     return Resolve(name,
2061         inEquivalenceStmt_ ? FindInScope(scope, name)
2062                            : scope.FindSymbol(name.source));
2063   }
2064 }
2065 
2066 Symbol &ScopeHandler::MakeSymbol(
2067     Scope &scope, const SourceName &name, Attrs attrs) {
2068   if (Symbol * symbol{FindInScope(scope, name)}) {
2069     symbol->attrs() |= attrs;
2070     return *symbol;
2071   } else {
2072     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2073     CHECK(pair.second); // name was not found, so must be able to add
2074     return *pair.first->second;
2075   }
2076 }
2077 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2078   return MakeSymbol(currScope(), name, attrs);
2079 }
2080 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2081   return Resolve(name, MakeSymbol(name.source, attrs));
2082 }
2083 Symbol &ScopeHandler::MakeHostAssocSymbol(
2084     const parser::Name &name, const Symbol &hostSymbol) {
2085   Symbol &symbol{*NonDerivedTypeScope()
2086                       .try_emplace(name.source, HostAssocDetails{hostSymbol})
2087                       .first->second};
2088   name.symbol = &symbol;
2089   symbol.attrs() = hostSymbol.attrs(); // TODO: except PRIVATE, PUBLIC?
2090   symbol.flags() = hostSymbol.flags();
2091   return symbol;
2092 }
2093 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2094   CHECK(!FindInScope(name));
2095   return MakeSymbol(currScope(), name, symbol.attrs());
2096 }
2097 
2098 // Look for name only in scope, not in enclosing scopes.
2099 Symbol *ScopeHandler::FindInScope(
2100     const Scope &scope, const parser::Name &name) {
2101   return Resolve(name, FindInScope(scope, name.source));
2102 }
2103 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2104   // all variants of names, e.g. "operator(.ne.)" for "operator(/=)"
2105   for (const std::string &n : GetAllNames(context(), name)) {
2106     auto it{scope.find(SourceName{n})};
2107     if (it != scope.end()) {
2108       return &*it->second;
2109     }
2110   }
2111   return nullptr;
2112 }
2113 
2114 // Find a component or type parameter by name in a derived type or its parents.
2115 Symbol *ScopeHandler::FindInTypeOrParents(
2116     const Scope &scope, const parser::Name &name) {
2117   return Resolve(name, scope.FindComponent(name.source));
2118 }
2119 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2120   return FindInTypeOrParents(currScope(), name);
2121 }
2122 
2123 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2124   currScope().erase(name.source);
2125   name.symbol = nullptr;
2126 }
2127 
2128 static bool NeedsType(const Symbol &symbol) {
2129   return !symbol.GetType() &&
2130       std::visit(common::visitors{
2131                      [](const EntityDetails &) { return true; },
2132                      [](const ObjectEntityDetails &) { return true; },
2133                      [](const AssocEntityDetails &) { return true; },
2134                      [&](const ProcEntityDetails &p) {
2135                        return symbol.test(Symbol::Flag::Function) &&
2136                            !symbol.attrs().test(Attr::INTRINSIC) &&
2137                            !p.interface().type() && !p.interface().symbol();
2138                      },
2139                      [](const auto &) { return false; },
2140                  },
2141           symbol.details());
2142 }
2143 
2144 void ScopeHandler::ApplyImplicitRules(
2145     Symbol &symbol, bool allowForwardReference) {
2146   if (context().HasError(symbol) || !NeedsType(symbol)) {
2147     return;
2148   }
2149   if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2150     symbol.set(Symbol::Flag::Implicit);
2151     symbol.SetType(*type);
2152     return;
2153   }
2154   if (symbol.has<ProcEntityDetails>() && !symbol.attrs().test(Attr::EXTERNAL)) {
2155     std::optional<Symbol::Flag> functionOrSubroutineFlag;
2156     if (symbol.test(Symbol::Flag::Function)) {
2157       functionOrSubroutineFlag = Symbol::Flag::Function;
2158     } else if (symbol.test(Symbol::Flag::Subroutine)) {
2159       functionOrSubroutineFlag = Symbol::Flag::Subroutine;
2160     }
2161     if (IsIntrinsic(symbol.name(), functionOrSubroutineFlag)) {
2162       // type will be determined in expression semantics
2163       AcquireIntrinsicProcedureFlags(symbol);
2164       return;
2165     }
2166   }
2167   if (allowForwardReference && ImplicitlyTypeForwardRef(symbol)) {
2168     return;
2169   }
2170   if (!context().HasError(symbol)) {
2171     Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2172     context().SetError(symbol);
2173   }
2174 }
2175 
2176 // Extension: Allow forward references to scalar integer dummy arguments
2177 // to appear in specification expressions under IMPLICIT NONE(TYPE) when
2178 // what would otherwise have been their implicit type is default INTEGER.
2179 bool ScopeHandler::ImplicitlyTypeForwardRef(Symbol &symbol) {
2180   if (!inSpecificationPart_ || context().HasError(symbol) || !IsDummy(symbol) ||
2181       symbol.Rank() != 0 ||
2182       !context().languageFeatures().IsEnabled(
2183           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2184     return false;
2185   }
2186   const DeclTypeSpec *type{
2187       GetImplicitType(symbol, false /*ignore IMPLICIT NONE*/)};
2188   if (!type || !type->IsNumeric(TypeCategory::Integer)) {
2189     return false;
2190   }
2191   auto kind{evaluate::ToInt64(type->numericTypeSpec().kind())};
2192   if (!kind || *kind != context().GetDefaultKind(TypeCategory::Integer)) {
2193     return false;
2194   }
2195   if (!ConvertToObjectEntity(symbol)) {
2196     return false;
2197   }
2198   // TODO: check no INTENT(OUT)?
2199   if (context().languageFeatures().ShouldWarn(
2200           common::LanguageFeature::ForwardRefDummyImplicitNone)) {
2201     Say(symbol.name(),
2202         "Dummy argument '%s' was used without being explicitly typed"_en_US,
2203         symbol.name());
2204   }
2205   symbol.set(Symbol::Flag::Implicit);
2206   symbol.SetType(*type);
2207   return true;
2208 }
2209 
2210 // Ensure that the symbol for an intrinsic procedure is marked with
2211 // the INTRINSIC attribute.  Also set PURE &/or ELEMENTAL as
2212 // appropriate.
2213 void ScopeHandler::AcquireIntrinsicProcedureFlags(Symbol &symbol) {
2214   symbol.attrs().set(Attr::INTRINSIC);
2215   switch (context().intrinsics().GetIntrinsicClass(symbol.name().ToString())) {
2216   case evaluate::IntrinsicClass::elementalFunction:
2217   case evaluate::IntrinsicClass::elementalSubroutine:
2218     symbol.attrs().set(Attr::ELEMENTAL);
2219     symbol.attrs().set(Attr::PURE);
2220     break;
2221   case evaluate::IntrinsicClass::impureSubroutine:
2222     break;
2223   default:
2224     symbol.attrs().set(Attr::PURE);
2225   }
2226 }
2227 
2228 const DeclTypeSpec *ScopeHandler::GetImplicitType(
2229     Symbol &symbol, bool respectImplicitNoneType) {
2230   const Scope *scope{&symbol.owner()};
2231   if (scope->IsGlobal()) {
2232     scope = &currScope();
2233   }
2234   scope = &GetInclusiveScope(*scope);
2235   const auto *type{implicitRulesMap_->at(scope).GetType(
2236       symbol.name(), respectImplicitNoneType)};
2237   if (type) {
2238     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2239       // Resolve any forward-referenced derived type; a quick no-op else.
2240       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2241       instantiatable.Instantiate(currScope());
2242     }
2243   }
2244   return type;
2245 }
2246 
2247 // Convert symbol to be a ObjectEntity or return false if it can't be.
2248 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2249   if (symbol.has<ObjectEntityDetails>()) {
2250     // nothing to do
2251   } else if (symbol.has<UnknownDetails>()) {
2252     symbol.set_details(ObjectEntityDetails{});
2253   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2254     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2255   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2256     return useDetails->symbol().has<ObjectEntityDetails>();
2257   } else {
2258     return false;
2259   }
2260   return true;
2261 }
2262 // Convert symbol to be a ProcEntity or return false if it can't be.
2263 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2264   if (symbol.has<ProcEntityDetails>()) {
2265     // nothing to do
2266   } else if (symbol.has<UnknownDetails>()) {
2267     symbol.set_details(ProcEntityDetails{});
2268   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2269     symbol.set_details(ProcEntityDetails{std::move(*details)});
2270     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2271       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2272       symbol.set(Symbol::Flag::Function);
2273     }
2274   } else {
2275     return false;
2276   }
2277   return true;
2278 }
2279 
2280 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2281     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2282   KindExpr value{GetKindParamExpr(category, kind)};
2283   if (auto known{evaluate::ToInt64(value)}) {
2284     return context().MakeNumericType(category, static_cast<int>(*known));
2285   } else {
2286     return currScope_->MakeNumericType(category, std::move(value));
2287   }
2288 }
2289 
2290 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2291     const std::optional<parser::KindSelector> &kind) {
2292   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2293   if (auto known{evaluate::ToInt64(value)}) {
2294     return context().MakeLogicalType(static_cast<int>(*known));
2295   } else {
2296     return currScope_->MakeLogicalType(std::move(value));
2297   }
2298 }
2299 
2300 void ScopeHandler::NotePossibleBadForwardRef(const parser::Name &name) {
2301   if (inSpecificationPart_ && name.symbol) {
2302     auto kind{currScope().kind()};
2303     if ((kind == Scope::Kind::Subprogram && !currScope().IsStmtFunction()) ||
2304         kind == Scope::Kind::Block) {
2305       bool isHostAssociated{&name.symbol->owner() == &currScope()
2306               ? name.symbol->has<HostAssocDetails>()
2307               : name.symbol->owner().Contains(currScope())};
2308       if (isHostAssociated) {
2309         specPartState_.forwardRefs.insert(name.source);
2310       }
2311     }
2312   }
2313 }
2314 
2315 std::optional<SourceName> ScopeHandler::HadForwardRef(
2316     const Symbol &symbol) const {
2317   auto iter{specPartState_.forwardRefs.find(symbol.name())};
2318   if (iter != specPartState_.forwardRefs.end()) {
2319     return *iter;
2320   }
2321   return std::nullopt;
2322 }
2323 
2324 bool ScopeHandler::CheckPossibleBadForwardRef(const Symbol &symbol) {
2325   if (!context().HasError(symbol)) {
2326     if (auto fwdRef{HadForwardRef(symbol)}) {
2327       const Symbol *outer{symbol.owner().FindSymbol(symbol.name())};
2328       if (outer && symbol.has<UseDetails>() &&
2329           &symbol.GetUltimate() == &outer->GetUltimate()) {
2330         // e.g. IMPORT of host's USE association
2331         return false;
2332       }
2333       Say(*fwdRef,
2334           "Forward reference to '%s' is not allowed in the same specification part"_err_en_US,
2335           *fwdRef)
2336           .Attach(symbol.name(), "Later declaration of '%s'"_en_US, *fwdRef);
2337       context().SetError(symbol);
2338       return true;
2339     }
2340     if (IsDummy(symbol) && isImplicitNoneType() &&
2341         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
2342       // Dummy was implicitly typed despite IMPLICIT NONE(TYPE) in
2343       // ApplyImplicitRules() due to use in a specification expression,
2344       // and no explicit type declaration appeared later.
2345       Say(symbol.name(),
2346           "No explicit type declared for dummy argument '%s'"_err_en_US);
2347       context().SetError(symbol);
2348       return true;
2349     }
2350   }
2351   return false;
2352 }
2353 
2354 void ScopeHandler::MakeExternal(Symbol &symbol) {
2355   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2356     symbol.attrs().set(Attr::EXTERNAL);
2357     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2358       Say(symbol.name(),
2359           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2360           symbol.name());
2361     }
2362   }
2363 }
2364 
2365 // ModuleVisitor implementation
2366 
2367 bool ModuleVisitor::Pre(const parser::Only &x) {
2368   std::visit(common::visitors{
2369                  [&](const Indirection<parser::GenericSpec> &generic) {
2370                    AddUse(GenericSpecInfo{generic.value()});
2371                  },
2372                  [&](const parser::Name &name) {
2373                    Resolve(name, AddUse(name.source, name.source).use);
2374                  },
2375                  [&](const parser::Rename &rename) { Walk(rename); },
2376              },
2377       x.u);
2378   return false;
2379 }
2380 
2381 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2382   const auto &localName{std::get<0>(x.t)};
2383   const auto &useName{std::get<1>(x.t)};
2384   SymbolRename rename{AddUse(localName.source, useName.source)};
2385   Resolve(useName, rename.use);
2386   Resolve(localName, rename.local);
2387   return false;
2388 }
2389 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2390   const parser::DefinedOpName &local{std::get<0>(x.t)};
2391   const parser::DefinedOpName &use{std::get<1>(x.t)};
2392   GenericSpecInfo localInfo{local};
2393   GenericSpecInfo useInfo{use};
2394   if (IsIntrinsicOperator(context(), local.v.source)) {
2395     Say(local.v,
2396         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2397   } else if (IsLogicalConstant(context(), local.v.source)) {
2398     Say(local.v,
2399         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2400   } else {
2401     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2402     useInfo.Resolve(rename.use);
2403     localInfo.Resolve(rename.local);
2404   }
2405   return false;
2406 }
2407 
2408 // Set useModuleScope_ to the Scope of the module being used.
2409 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2410   useModuleScope_ = FindModule(x.moduleName);
2411   if (!useModuleScope_) {
2412     return false;
2413   }
2414   // use the name from this source file
2415   useModuleScope_->symbol()->ReplaceName(x.moduleName.source);
2416   return true;
2417 }
2418 
2419 void ModuleVisitor::Post(const parser::UseStmt &x) {
2420   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2421     // Not a use-only: collect the names that were used in renames,
2422     // then add a use for each public name that was not renamed.
2423     std::set<SourceName> useNames;
2424     for (const auto &rename : *list) {
2425       std::visit(common::visitors{
2426                      [&](const parser::Rename::Names &names) {
2427                        useNames.insert(std::get<1>(names.t).source);
2428                      },
2429                      [&](const parser::Rename::Operators &ops) {
2430                        useNames.insert(std::get<1>(ops.t).v.source);
2431                      },
2432                  },
2433           rename.u);
2434     }
2435     for (const auto &[name, symbol] : *useModuleScope_) {
2436       if (symbol->attrs().test(Attr::PUBLIC) &&
2437           (!symbol->attrs().test(Attr::INTRINSIC) ||
2438               symbol->has<UseDetails>()) &&
2439           !symbol->has<MiscDetails>() && useNames.count(name) == 0) {
2440         SourceName location{x.moduleName.source};
2441         if (auto *localSymbol{FindInScope(name)}) {
2442           DoAddUse(location, localSymbol->name(), *localSymbol, *symbol);
2443         } else {
2444           DoAddUse(location, location, CopySymbol(name, *symbol), *symbol);
2445         }
2446       }
2447     }
2448   }
2449   useModuleScope_ = nullptr;
2450 }
2451 
2452 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2453     const SourceName &localName, const SourceName &useName) {
2454   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2455 }
2456 
2457 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2458     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2459   if (!useModuleScope_) {
2460     return {}; // error occurred finding module
2461   }
2462   if (!useSymbol) {
2463     Say(useName, "'%s' not found in module '%s'"_err_en_US, MakeOpName(useName),
2464         useModuleScope_->GetName().value());
2465     return {};
2466   }
2467   if (useSymbol->attrs().test(Attr::PRIVATE) &&
2468       !FindModuleFileContaining(currScope())) {
2469     // Privacy is not enforced in module files so that generic interfaces
2470     // can be resolved to private specific procedures in specification
2471     // expressions.
2472     Say(useName, "'%s' is PRIVATE in '%s'"_err_en_US, MakeOpName(useName),
2473         useModuleScope_->GetName().value());
2474     return {};
2475   }
2476   auto &localSymbol{MakeSymbol(localName)};
2477   DoAddUse(useName, localName, localSymbol, *useSymbol);
2478   return {&localSymbol, useSymbol};
2479 }
2480 
2481 // symbol must be either a Use or a Generic formed by merging two uses.
2482 // Convert it to a UseError with this additional location.
2483 static void ConvertToUseError(
2484     Symbol &symbol, const SourceName &location, const Scope &module) {
2485   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2486   if (!useDetails) {
2487     auto &genericDetails{symbol.get<GenericDetails>()};
2488     useDetails = &genericDetails.uses().at(0)->get<UseDetails>();
2489   }
2490   symbol.set_details(
2491       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2492 }
2493 
2494 void ModuleVisitor::DoAddUse(const SourceName &location,
2495     const SourceName &localName, Symbol &localSymbol, const Symbol &useSymbol) {
2496   localSymbol.attrs() = useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2497   localSymbol.flags() = useSymbol.flags();
2498   const Symbol &useUltimate{useSymbol.GetUltimate()};
2499   if (auto *useDetails{localSymbol.detailsIf<UseDetails>()}) {
2500     const Symbol &localUltimate{localSymbol.GetUltimate()};
2501     if (localUltimate == useUltimate) {
2502       // use-associating the same symbol again -- ok
2503     } else if (localUltimate.has<GenericDetails>() &&
2504         useUltimate.has<GenericDetails>()) {
2505       // use-associating generics with the same names: merge them into a
2506       // new generic in this scope
2507       auto generic1{localUltimate.get<GenericDetails>()};
2508       AddGenericUse(generic1, localName, useUltimate);
2509       generic1.AddUse(localSymbol);
2510       // useSymbol has specific g and so does generic1
2511       auto &generic2{useUltimate.get<GenericDetails>()};
2512       if (generic1.derivedType() && generic2.derivedType() &&
2513           generic1.derivedType() != generic2.derivedType()) {
2514         Say(location,
2515             "Generic interface '%s' has ambiguous derived types"
2516             " from modules '%s' and '%s'"_err_en_US,
2517             localSymbol.name(), GetUsedModule(*useDetails).name(),
2518             useUltimate.owner().GetName().value());
2519         context().SetError(localSymbol);
2520       } else {
2521         generic1.CopyFrom(generic2);
2522       }
2523       EraseSymbol(localSymbol);
2524       MakeSymbol(localSymbol.name(), localSymbol.attrs(), std::move(generic1));
2525     } else {
2526       ConvertToUseError(localSymbol, location, *useModuleScope_);
2527     }
2528   } else if (auto *genericDetails{localSymbol.detailsIf<GenericDetails>()}) {
2529     if (const auto *useDetails{useUltimate.detailsIf<GenericDetails>()}) {
2530       AddGenericUse(*genericDetails, localName, useUltimate);
2531       if (genericDetails->derivedType() && useDetails->derivedType() &&
2532           genericDetails->derivedType() != useDetails->derivedType()) {
2533         Say(location,
2534             "Generic interface '%s' has ambiguous derived types"
2535             " from modules '%s' and '%s'"_err_en_US,
2536             localSymbol.name(),
2537             genericDetails->derivedType()->owner().GetName().value(),
2538             useDetails->derivedType()->owner().GetName().value());
2539       } else {
2540         genericDetails->CopyFrom(*useDetails);
2541       }
2542     } else {
2543       ConvertToUseError(localSymbol, location, *useModuleScope_);
2544     }
2545   } else if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2546     details->add_occurrence(location, *useModuleScope_);
2547   } else if (!localSymbol.has<UnknownDetails>()) {
2548     Say(location,
2549         "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2550         localName)
2551         .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2552             localName);
2553   } else {
2554     localSymbol.set_details(UseDetails{localName, useSymbol});
2555   }
2556 }
2557 
2558 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2559   if (useModuleScope_) {
2560     const auto &name{info.symbolName()};
2561     auto rename{AddUse(name, name, FindInScope(*useModuleScope_, name))};
2562     info.Resolve(rename.use);
2563   }
2564 }
2565 
2566 // Create a UseDetails symbol for this USE and add it to generic
2567 void ModuleVisitor::AddGenericUse(
2568     GenericDetails &generic, const SourceName &name, const Symbol &useSymbol) {
2569   generic.AddUse(currScope().MakeSymbol(name, {}, UseDetails{name, useSymbol}));
2570 }
2571 
2572 bool ModuleVisitor::BeginSubmodule(
2573     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2574   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2575   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2576   Scope *ancestor{FindModule(ancestorName)};
2577   if (!ancestor) {
2578     return false;
2579   }
2580   Scope *parentScope{parentName ? FindModule(*parentName, ancestor) : ancestor};
2581   if (!parentScope) {
2582     return false;
2583   }
2584   PushScope(*parentScope); // submodule is hosted in parent
2585   BeginModule(name, true);
2586   if (!ancestor->AddSubmodule(name.source, currScope())) {
2587     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2588         ancestorName.source, name.source);
2589   }
2590   return true;
2591 }
2592 
2593 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2594   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2595   auto &details{symbol.get<ModuleDetails>()};
2596   PushScope(Scope::Kind::Module, &symbol);
2597   details.set_scope(&currScope());
2598   defaultAccess_ = Attr::PUBLIC;
2599   prevAccessStmt_ = std::nullopt;
2600 }
2601 
2602 // Find a module or submodule by name and return its scope.
2603 // If ancestor is present, look for a submodule of that ancestor module.
2604 // May have to read a .mod file to find it.
2605 // If an error occurs, report it and return nullptr.
2606 Scope *ModuleVisitor::FindModule(const parser::Name &name, Scope *ancestor) {
2607   ModFileReader reader{context()};
2608   Scope *scope{reader.Read(name.source, ancestor)};
2609   if (!scope) {
2610     return nullptr;
2611   }
2612   if (scope->kind() != Scope::Kind::Module) {
2613     Say(name, "'%s' is not a module"_err_en_US);
2614     return nullptr;
2615   }
2616   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2617     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2618   }
2619   Resolve(name, scope->symbol());
2620   return scope;
2621 }
2622 
2623 void ModuleVisitor::ApplyDefaultAccess() {
2624   for (auto &pair : currScope()) {
2625     Symbol &symbol = *pair.second;
2626     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2627       symbol.attrs().set(defaultAccess_);
2628     }
2629   }
2630 }
2631 
2632 // InterfaceVistor implementation
2633 
2634 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2635   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2636   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2637   return BeginAttrs();
2638 }
2639 
2640 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2641 
2642 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2643   genericInfo_.pop();
2644 }
2645 
2646 // Create a symbol in genericSymbol_ for this GenericSpec.
2647 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2648   if (auto *symbol{FindInScope(GenericSpecInfo{x}.symbolName())}) {
2649     SetGenericSymbol(*symbol);
2650   }
2651   return false;
2652 }
2653 
2654 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2655   if (!isGeneric()) {
2656     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2657     return false;
2658   }
2659   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2660   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2661   AddSpecificProcs(names, kind);
2662   return false;
2663 }
2664 
2665 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2666   genericInfo_.emplace(/*isInterface*/ false);
2667   return true;
2668 }
2669 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2670   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2671     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2672   }
2673   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2674   AddSpecificProcs(names, ProcedureKind::Procedure);
2675   genericInfo_.pop();
2676 }
2677 
2678 bool InterfaceVisitor::inInterfaceBlock() const {
2679   return !genericInfo_.empty() && GetGenericInfo().isInterface;
2680 }
2681 bool InterfaceVisitor::isGeneric() const {
2682   return !genericInfo_.empty() && GetGenericInfo().symbol;
2683 }
2684 bool InterfaceVisitor::isAbstract() const {
2685   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
2686 }
2687 
2688 void InterfaceVisitor::AddSpecificProcs(
2689     const std::list<parser::Name> &names, ProcedureKind kind) {
2690   for (const auto &name : names) {
2691     specificProcs_.emplace(
2692         GetGenericInfo().symbol, std::make_pair(&name, kind));
2693   }
2694 }
2695 
2696 // By now we should have seen all specific procedures referenced by name in
2697 // this generic interface. Resolve those names to symbols.
2698 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
2699   auto &details{generic.get<GenericDetails>()};
2700   UnorderedSymbolSet symbolsSeen;
2701   for (const Symbol &symbol : details.specificProcs()) {
2702     symbolsSeen.insert(symbol);
2703   }
2704   auto range{specificProcs_.equal_range(&generic)};
2705   for (auto it{range.first}; it != range.second; ++it) {
2706     auto *name{it->second.first};
2707     auto kind{it->second.second};
2708     const auto *symbol{FindSymbol(*name)};
2709     if (!symbol) {
2710       Say(*name, "Procedure '%s' not found"_err_en_US);
2711       continue;
2712     }
2713     if (symbol == &generic) {
2714       if (auto *specific{generic.get<GenericDetails>().specific()}) {
2715         symbol = specific;
2716       }
2717     }
2718     const Symbol &ultimate{symbol->GetUltimate()};
2719     if (!ultimate.has<SubprogramDetails>() &&
2720         !ultimate.has<SubprogramNameDetails>()) {
2721       Say(*name, "'%s' is not a subprogram"_err_en_US);
2722       continue;
2723     }
2724     if (kind == ProcedureKind::ModuleProcedure) {
2725       if (const auto *nd{ultimate.detailsIf<SubprogramNameDetails>()}) {
2726         if (nd->kind() != SubprogramKind::Module) {
2727           Say(*name, "'%s' is not a module procedure"_err_en_US);
2728         }
2729       } else {
2730         // USE-associated procedure
2731         const auto *sd{ultimate.detailsIf<SubprogramDetails>()};
2732         CHECK(sd);
2733         if (ultimate.owner().kind() != Scope::Kind::Module ||
2734             sd->isInterface()) {
2735           Say(*name, "'%s' is not a module procedure"_err_en_US);
2736         }
2737       }
2738     }
2739     if (!symbolsSeen.insert(ultimate).second) {
2740       if (symbol == &ultimate) {
2741         Say(name->source,
2742             "Procedure '%s' is already specified in generic '%s'"_err_en_US,
2743             name->source, MakeOpName(generic.name()));
2744       } else {
2745         Say(name->source,
2746             "Procedure '%s' from module '%s' is already specified in generic '%s'"_err_en_US,
2747             ultimate.name(), ultimate.owner().GetName().value(),
2748             MakeOpName(generic.name()));
2749       }
2750       continue;
2751     }
2752     details.AddSpecificProc(*symbol, name->source);
2753   }
2754   specificProcs_.erase(range.first, range.second);
2755 }
2756 
2757 // Check that the specific procedures are all functions or all subroutines.
2758 // If there is a derived type with the same name they must be functions.
2759 // Set the corresponding flag on generic.
2760 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
2761   ResolveSpecificsInGeneric(generic);
2762   auto &details{generic.get<GenericDetails>()};
2763   if (auto *proc{details.CheckSpecific()}) {
2764     auto msg{
2765         "'%s' may not be the name of both a generic interface and a"
2766         " procedure unless it is a specific procedure of the generic"_err_en_US};
2767     if (proc->name().begin() > generic.name().begin()) {
2768       Say(proc->name(), std::move(msg));
2769     } else {
2770       Say(generic.name(), std::move(msg));
2771     }
2772   }
2773   auto &specifics{details.specificProcs()};
2774   if (specifics.empty()) {
2775     if (details.derivedType()) {
2776       generic.set(Symbol::Flag::Function);
2777     }
2778     return;
2779   }
2780   const Symbol &firstSpecific{specifics.front()};
2781   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
2782   for (const Symbol &specific : specifics) {
2783     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
2784       auto &msg{Say(generic.name(),
2785           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
2786       if (isFunction) {
2787         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
2788         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
2789       } else {
2790         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
2791         msg.Attach(specific.name(), "Function declaration"_en_US);
2792       }
2793     }
2794   }
2795   if (!isFunction && details.derivedType()) {
2796     SayDerivedType(generic.name(),
2797         "Generic interface '%s' may only contain functions due to derived type"
2798         " with same name"_err_en_US,
2799         *details.derivedType()->scope());
2800   }
2801   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
2802 }
2803 
2804 // SubprogramVisitor implementation
2805 
2806 // Return false if it is actually an assignment statement.
2807 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
2808   const auto &name{std::get<parser::Name>(x.t)};
2809   const DeclTypeSpec *resultType{nullptr};
2810   // Look up name: provides return type or tells us if it's an array
2811   if (auto *symbol{FindSymbol(name)}) {
2812     auto *details{symbol->detailsIf<EntityDetails>()};
2813     if (!details) {
2814       badStmtFuncFound_ = true;
2815       return false;
2816     }
2817     // TODO: check that attrs are compatible with stmt func
2818     resultType = details->type();
2819     symbol->details() = UnknownDetails{}; // will be replaced below
2820   }
2821   if (badStmtFuncFound_) {
2822     Say(name, "'%s' has not been declared as an array"_err_en_US);
2823     return true;
2824   }
2825   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
2826   symbol.set(Symbol::Flag::StmtFunction);
2827   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
2828   auto &details{symbol.get<SubprogramDetails>()};
2829   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
2830     ObjectEntityDetails dummyDetails{true};
2831     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
2832       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
2833         if (d->type()) {
2834           dummyDetails.set_type(*d->type());
2835         }
2836       }
2837     }
2838     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
2839     ApplyImplicitRules(dummy);
2840     details.add_dummyArg(dummy);
2841   }
2842   ObjectEntityDetails resultDetails;
2843   if (resultType) {
2844     resultDetails.set_type(*resultType);
2845   }
2846   resultDetails.set_funcResult(true);
2847   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
2848   ApplyImplicitRules(result);
2849   details.set_result(result);
2850   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
2851   Walk(parsedExpr);
2852   // The analysis of the expression that constitutes the body of the
2853   // statement function is deferred to FinishSpecificationPart() so that
2854   // all declarations and implicit typing are complete.
2855   PopScope();
2856   return true;
2857 }
2858 
2859 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
2860   if (suffix.resultName) {
2861     funcInfo_.resultName = &suffix.resultName.value();
2862   }
2863   return true;
2864 }
2865 
2866 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
2867   // Save this to process after UseStmt and ImplicitPart
2868   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
2869     if (funcInfo_.parsedType) { // C1543
2870       Say(currStmtSource().value(),
2871           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
2872       return false;
2873     } else {
2874       funcInfo_.parsedType = parsedType;
2875       funcInfo_.source = currStmtSource();
2876       return false;
2877     }
2878   } else {
2879     return true;
2880   }
2881 }
2882 
2883 void SubprogramVisitor::Post(const parser::ImplicitPart &) {
2884   // If the function has a type in the prefix, process it now
2885   if (funcInfo_.parsedType) {
2886     messageHandler().set_currStmtSource(funcInfo_.source);
2887     if (const auto *type{ProcessTypeSpec(*funcInfo_.parsedType, true)}) {
2888       if (!context().HasError(funcInfo_.resultSymbol)) {
2889         funcInfo_.resultSymbol->SetType(*type);
2890       }
2891     }
2892   }
2893   funcInfo_ = {};
2894 }
2895 
2896 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
2897   const auto &name{std::get<parser::Name>(
2898       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
2899   return BeginSubprogram(name, Symbol::Flag::Subroutine);
2900 }
2901 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
2902   EndSubprogram();
2903 }
2904 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
2905   const auto &name{std::get<parser::Name>(
2906       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
2907   return BeginSubprogram(name, Symbol::Flag::Function);
2908 }
2909 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
2910   EndSubprogram();
2911 }
2912 
2913 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
2914   return BeginAttrs();
2915 }
2916 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
2917   return BeginAttrs();
2918 }
2919 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
2920 
2921 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
2922   const auto &name{std::get<parser::Name>(stmt.t)};
2923   auto &details{PostSubprogramStmt(name)};
2924   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
2925     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
2926       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails(true))};
2927       details.add_dummyArg(dummy);
2928     } else {
2929       details.add_alternateReturn();
2930     }
2931   }
2932 }
2933 
2934 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
2935   const auto &name{std::get<parser::Name>(stmt.t)};
2936   auto &details{PostSubprogramStmt(name)};
2937   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
2938     Symbol &dummy{MakeSymbol(dummyName, EntityDetails(true))};
2939     details.add_dummyArg(dummy);
2940   }
2941   const parser::Name *funcResultName;
2942   if (funcInfo_.resultName && funcInfo_.resultName->source != name.source) {
2943     // Note that RESULT is ignored if it has the same name as the function.
2944     funcResultName = funcInfo_.resultName;
2945   } else {
2946     EraseSymbol(name); // was added by PushSubprogramScope
2947     funcResultName = &name;
2948   }
2949   // add function result to function scope
2950   if (details.isFunction()) {
2951     CHECK(context().HasError(currScope().symbol()));
2952   } else {
2953     // add function result to function scope
2954     EntityDetails funcResultDetails;
2955     funcResultDetails.set_funcResult(true);
2956     funcInfo_.resultSymbol =
2957         &MakeSymbol(*funcResultName, std::move(funcResultDetails));
2958     details.set_result(*funcInfo_.resultSymbol);
2959   }
2960 
2961   // C1560.
2962   if (funcInfo_.resultName && funcInfo_.resultName->source == name.source) {
2963     Say(funcInfo_.resultName->source,
2964         "The function name should not appear in RESULT, references to '%s' "
2965         "inside"
2966         " the function will be considered as references to the result only"_en_US,
2967         name.source);
2968     // RESULT name was ignored above, the only side effect from doing so will be
2969     // the inability to make recursive calls. The related parser::Name is still
2970     // resolved to the created function result symbol because every parser::Name
2971     // should be resolved to avoid internal errors.
2972     Resolve(*funcInfo_.resultName, funcInfo_.resultSymbol);
2973   }
2974   name.symbol = currScope().symbol(); // must not be function result symbol
2975   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
2976   // has a RESULT() suffix.
2977   funcInfo_.resultName = nullptr;
2978 }
2979 
2980 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
2981     const parser::Name &name) {
2982   Symbol &symbol{*currScope().symbol()};
2983   CHECK(name.source == symbol.name());
2984   SetBindNameOn(symbol);
2985   symbol.attrs() |= EndAttrs();
2986   if (symbol.attrs().test(Attr::MODULE)) {
2987     symbol.attrs().set(Attr::EXTERNAL, false);
2988   }
2989   return symbol.get<SubprogramDetails>();
2990 }
2991 
2992 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
2993   auto attrs{EndAttrs()}; // needs to be called even if early return
2994   Scope &inclusiveScope{InclusiveScope()};
2995   const Symbol *subprogram{inclusiveScope.symbol()};
2996   if (!subprogram) {
2997     CHECK(context().AnyFatalError());
2998     return;
2999   }
3000   const auto &name{std::get<parser::Name>(stmt.t)};
3001   const auto *parentDetails{subprogram->detailsIf<SubprogramDetails>()};
3002   bool inFunction{parentDetails && parentDetails->isFunction()};
3003   const parser::Name *resultName{funcInfo_.resultName};
3004   if (resultName) { // RESULT(result) is present
3005     funcInfo_.resultName = nullptr;
3006     if (!inFunction) {
3007       Say2(resultName->source,
3008           "RESULT(%s) may appear only in a function"_err_en_US,
3009           subprogram->name(), "Containing subprogram"_en_US);
3010     } else if (resultName->source == subprogram->name()) { // C1574
3011       Say2(resultName->source,
3012           "RESULT(%s) may not have the same name as the function"_err_en_US,
3013           subprogram->name(), "Containing function"_en_US);
3014     } else if (const Symbol *
3015         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
3016       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
3017         if (details->entryScope() == &inclusiveScope) {
3018           Say2(resultName->source,
3019               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
3020               symbol->name(), "Conflicting ENTRY"_en_US);
3021         }
3022       }
3023     }
3024     if (Symbol * symbol{FindSymbol(name)}) { // C1570
3025       // When RESULT() appears, ENTRY name can't have been already declared
3026       if (inclusiveScope.Contains(symbol->owner())) {
3027         Say2(name,
3028             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
3029             *symbol, "Previous declaration of '%s'"_en_US);
3030       }
3031     }
3032     if (resultName->source == name.source) {
3033       // ignore RESULT() hereafter when it's the same name as the ENTRY
3034       resultName = nullptr;
3035     }
3036   }
3037   SubprogramDetails entryDetails;
3038   entryDetails.set_entryScope(inclusiveScope);
3039   if (inFunction) {
3040     // Create the entity to hold the function result, if necessary.
3041     Symbol *resultSymbol{nullptr};
3042     auto &effectiveResultName{*(resultName ? resultName : &name)};
3043     resultSymbol = FindInScope(currScope(), effectiveResultName);
3044     if (resultSymbol) { // C1574
3045       std::visit(
3046           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
3047               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
3048               [](ProcEntityDetails &x) { x.set_funcResult(true); },
3049               [&](const auto &) {
3050                 Say2(effectiveResultName.source,
3051                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
3052                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
3053               }},
3054           resultSymbol->details());
3055     } else if (inExecutionPart_) {
3056       ObjectEntityDetails entity;
3057       entity.set_funcResult(true);
3058       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3059       ApplyImplicitRules(*resultSymbol);
3060     } else {
3061       EntityDetails entity;
3062       entity.set_funcResult(true);
3063       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
3064     }
3065     if (!resultName) {
3066       name.symbol = nullptr; // symbol will be used for entry point below
3067     }
3068     entryDetails.set_result(*resultSymbol);
3069   }
3070 
3071   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
3072     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
3073       Symbol *dummy{FindSymbol(*dummyName)};
3074       if (dummy) {
3075         std::visit(
3076             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
3077                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
3078                 [](ProcEntityDetails &x) { x.set_isDummy(); },
3079                 [&](const auto &) {
3080                   Say2(dummyName->source,
3081                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
3082                       dummy->name(), "Previous declaration of '%s'"_en_US);
3083                 }},
3084             dummy->details());
3085       } else {
3086         dummy = &MakeSymbol(*dummyName, EntityDetails{true});
3087         if (inExecutionPart_) {
3088           ApplyImplicitRules(*dummy);
3089         }
3090       }
3091       entryDetails.add_dummyArg(*dummy);
3092     } else {
3093       if (inFunction) { // C1573
3094         Say(name,
3095             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
3096         break;
3097       }
3098       entryDetails.add_alternateReturn();
3099     }
3100   }
3101 
3102   Symbol::Flag subpFlag{
3103       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
3104   Scope &outer{inclusiveScope.parent()}; // global or module scope
3105   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
3106     attrs.set(Attr::PUBLIC);
3107   }
3108   if (Symbol * extant{FindSymbol(outer, name)}) {
3109     if (!HandlePreviousCalls(name, *extant, subpFlag)) {
3110       if (outer.IsGlobal()) {
3111         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
3112             *extant, "Previous definition of '%s'"_en_US);
3113       } else {
3114         SayAlreadyDeclared(name, *extant);
3115       }
3116       return;
3117     }
3118   }
3119   Symbol &entrySymbol{MakeSymbol(outer, name.source, attrs)};
3120   entrySymbol.set_details(std::move(entryDetails));
3121   SetBindNameOn(entrySymbol);
3122   entrySymbol.set(subpFlag);
3123   Resolve(name, entrySymbol);
3124 }
3125 
3126 // A subprogram declared with MODULE PROCEDURE
3127 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3128   auto *symbol{FindSymbol(name)};
3129   if (symbol && symbol->has<SubprogramNameDetails>()) {
3130     symbol = FindSymbol(currScope().parent(), name);
3131   }
3132   if (!IsSeparateModuleProcedureInterface(symbol)) {
3133     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3134     return false;
3135   }
3136   if (symbol->owner() == currScope()) {
3137     PushScope(Scope::Kind::Subprogram, symbol);
3138   } else {
3139     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3140     PushScope(Scope::Kind::Subprogram, &newSymbol);
3141     const auto &details{symbol->get<SubprogramDetails>()};
3142     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3143     for (const Symbol *dummyArg : details.dummyArgs()) {
3144       if (!dummyArg) {
3145         newDetails.add_alternateReturn();
3146       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3147         newDetails.add_dummyArg(*copy);
3148       }
3149     }
3150     if (details.isFunction()) {
3151       currScope().erase(symbol->name());
3152       newDetails.set_result(*currScope().CopySymbol(details.result()));
3153     }
3154   }
3155   return true;
3156 }
3157 
3158 // A subprogram declared with SUBROUTINE or FUNCTION
3159 bool SubprogramVisitor::BeginSubprogram(
3160     const parser::Name &name, Symbol::Flag subpFlag, bool hasModulePrefix) {
3161   if (hasModulePrefix && currScope().IsGlobal()) { // C1547
3162     Say(name,
3163         "'%s' is a MODULE procedure which must be declared within a "
3164         "MODULE or SUBMODULE"_err_en_US);
3165     return false;
3166   }
3167 
3168   if (hasModulePrefix && !inInterfaceBlock() &&
3169       !IsSeparateModuleProcedureInterface(
3170           FindSymbol(currScope().parent(), name))) {
3171     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3172     return false;
3173   }
3174   PushSubprogramScope(name, subpFlag);
3175   return true;
3176 }
3177 
3178 void SubprogramVisitor::EndSubprogram() { PopScope(); }
3179 
3180 bool SubprogramVisitor::HandlePreviousCalls(
3181     const parser::Name &name, Symbol &symbol, Symbol::Flag subpFlag) {
3182   if (const auto *proc{symbol.detailsIf<ProcEntityDetails>()}; proc &&
3183       !proc->isDummy() &&
3184       !symbol.attrs().HasAny(Attrs{Attr::INTRINSIC, Attr::POINTER})) {
3185     // There's a symbol created for previous calls to this subprogram or
3186     // ENTRY's name.  We have to replace that symbol in situ to avoid the
3187     // obligation to rewrite symbol pointers in the parse tree.
3188     if (!symbol.test(subpFlag)) {
3189       Say2(name,
3190           subpFlag == Symbol::Flag::Function
3191               ? "'%s' was previously called as a subroutine"_err_en_US
3192               : "'%s' was previously called as a function"_err_en_US,
3193           symbol, "Previous call of '%s'"_en_US);
3194     }
3195     EntityDetails entity;
3196     if (proc->type()) {
3197       entity.set_type(*proc->type());
3198     }
3199     symbol.details() = std::move(entity);
3200     return true;
3201   } else {
3202     return symbol.has<UnknownDetails>() || symbol.has<SubprogramNameDetails>();
3203   }
3204 }
3205 
3206 void SubprogramVisitor::CheckExtantProc(
3207     const parser::Name &name, Symbol::Flag subpFlag) {
3208   if (auto *prev{FindSymbol(name)}) {
3209     if (!IsDummy(*prev) && !HandlePreviousCalls(name, *prev, subpFlag)) {
3210       SayAlreadyDeclared(name, *prev);
3211     }
3212   }
3213 }
3214 
3215 Symbol &SubprogramVisitor::PushSubprogramScope(
3216     const parser::Name &name, Symbol::Flag subpFlag) {
3217   auto *symbol{GetSpecificFromGeneric(name)};
3218   if (!symbol) {
3219     CheckExtantProc(name, subpFlag);
3220     symbol = &MakeSymbol(name, SubprogramDetails{});
3221   }
3222   symbol->set(subpFlag);
3223   symbol->ReplaceName(name.source);
3224   PushScope(Scope::Kind::Subprogram, symbol);
3225   auto &details{symbol->get<SubprogramDetails>()};
3226   if (inInterfaceBlock()) {
3227     details.set_isInterface();
3228     if (isAbstract()) {
3229       symbol->attrs().set(Attr::ABSTRACT);
3230     } else {
3231       MakeExternal(*symbol);
3232     }
3233     if (isGeneric()) {
3234       Symbol &genericSymbol{GetGenericSymbol()};
3235       if (genericSymbol.has<GenericDetails>()) {
3236         genericSymbol.get<GenericDetails>().AddSpecificProc(
3237             *symbol, name.source);
3238       } else {
3239         CHECK(context().HasError(genericSymbol));
3240       }
3241     }
3242     set_inheritFromParent(false);
3243   }
3244   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3245   return *symbol;
3246 }
3247 
3248 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3249   if (auto *prev{FindSymbol(name)}) {
3250     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3251       if (prev->test(Symbol::Flag::Subroutine) ||
3252           prev->test(Symbol::Flag::Function)) {
3253         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3254             "Previous call of '%s'"_en_US);
3255       }
3256       EraseSymbol(name);
3257     }
3258   }
3259   if (name.source.empty()) {
3260     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3261     PushScope(Scope::Kind::BlockData, nullptr);
3262   } else {
3263     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3264   }
3265 }
3266 
3267 // If name is a generic, return specific subprogram with the same name.
3268 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3269   if (auto *symbol{FindSymbol(name)}) {
3270     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3271       // found generic, want subprogram
3272       auto *specific{details->specific()};
3273       if (!specific) {
3274         specific =
3275             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3276         if (details->derivedType()) {
3277           // A specific procedure with the same name as a derived type
3278           SayAlreadyDeclared(name, *details->derivedType());
3279         } else {
3280           details->set_specific(Resolve(name, *specific));
3281         }
3282       } else if (isGeneric()) {
3283         SayAlreadyDeclared(name, *specific);
3284       }
3285       if (!specific->has<SubprogramDetails>()) {
3286         specific->set_details(SubprogramDetails{});
3287       }
3288       return specific;
3289     }
3290   }
3291   return nullptr;
3292 }
3293 
3294 // DeclarationVisitor implementation
3295 
3296 bool DeclarationVisitor::BeginDecl() {
3297   BeginDeclTypeSpec();
3298   BeginArraySpec();
3299   return BeginAttrs();
3300 }
3301 void DeclarationVisitor::EndDecl() {
3302   EndDeclTypeSpec();
3303   EndArraySpec();
3304   EndAttrs();
3305 }
3306 
3307 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3308   const auto *details{name.symbol->detailsIf<UseErrorDetails>()};
3309   if (!details) {
3310     return false;
3311   }
3312   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3313   for (const auto &[location, module] : details->occurrences()) {
3314     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3315         name.source, module->GetName().value());
3316   }
3317   return true;
3318 }
3319 
3320 // Report error if accessibility of symbol doesn't match isPrivate.
3321 void DeclarationVisitor::CheckAccessibility(
3322     const SourceName &name, bool isPrivate, Symbol &symbol) {
3323   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3324     Say2(name,
3325         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3326         symbol, "Previous declaration of '%s'"_en_US);
3327   }
3328 }
3329 
3330 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3331   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3332     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3333       if (typeSpec->category() == DeclTypeSpec::Character) {
3334         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3335           Say("The type parameter LEN cannot be deferred without"
3336               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3337         }
3338       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3339         for (const auto &pair : derivedSpec->parameters()) {
3340           if (pair.second.isDeferred()) {
3341             Say(currStmtSource().value(),
3342                 "The value of type parameter '%s' cannot be deferred"
3343                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3344                 pair.first);
3345           }
3346         }
3347       }
3348     }
3349   }
3350   EndDecl();
3351 }
3352 
3353 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3354   DeclareObjectEntity(std::get<parser::Name>(x.t));
3355 }
3356 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3357   DeclareObjectEntity(std::get<parser::Name>(x.t));
3358 }
3359 
3360 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3361   // Defer inspection of initializers to Initialization() so that the
3362   // symbol being initialized will be available within the initialization
3363   // expression.
3364   return false;
3365 }
3366 
3367 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3368   // TODO: may be under StructureStmt
3369   const auto &name{std::get<parser::ObjectName>(x.t)};
3370   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3371   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3372   symbol.ReplaceName(name.source);
3373   if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3374     if (ConvertToObjectEntity(symbol)) {
3375       Initialization(name, *init, false);
3376     }
3377   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3378     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3379   }
3380 }
3381 
3382 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3383   const auto &name{std::get<parser::Name>(x.t)};
3384   if (const auto &deferredShapeSpecs{
3385           std::get<std::optional<parser::DeferredShapeSpecList>>(x.t)}) {
3386     CHECK(arraySpec().empty());
3387     BeginArraySpec();
3388     set_arraySpec(AnalyzeDeferredShapeSpecList(context(), *deferredShapeSpecs));
3389     Symbol &symbol{DeclareObjectEntity(name, Attrs{Attr::POINTER})};
3390     symbol.ReplaceName(name.source);
3391     EndArraySpec();
3392   } else {
3393     Symbol &symbol{DeclareUnknownEntity(name, Attrs{Attr::POINTER})};
3394     symbol.ReplaceName(name.source);
3395   }
3396 }
3397 
3398 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3399   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3400   auto &name{std::get<parser::Name>(x.t)};
3401   Symbol *symbol;
3402   if (kind == parser::BindEntity::Kind::Object) {
3403     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3404   } else {
3405     symbol = &MakeCommonBlockSymbol(name);
3406     symbol->attrs().set(Attr::BIND_C);
3407   }
3408   SetBindNameOn(*symbol);
3409   return false;
3410 }
3411 bool DeclarationVisitor::Pre(const parser::OldParameterStmt &x) {
3412   inOldStyleParameterStmt_ = true;
3413   Walk(x.v);
3414   inOldStyleParameterStmt_ = false;
3415   return false;
3416 }
3417 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3418   auto &name{std::get<parser::NamedConstant>(x.t).v};
3419   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3420   if (!ConvertToObjectEntity(symbol) ||
3421       symbol.test(Symbol::Flag::CrayPointer) ||
3422       symbol.test(Symbol::Flag::CrayPointee)) {
3423     SayWithDecl(
3424         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3425     return false;
3426   }
3427   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3428   auto &details{symbol.get<ObjectEntityDetails>()};
3429   if (inOldStyleParameterStmt_) {
3430     // non-standard extension PARAMETER statement (no parentheses)
3431     Walk(expr);
3432     auto folded{EvaluateExpr(expr)};
3433     if (details.type()) {
3434       SayWithDecl(name, symbol,
3435           "Alternative style PARAMETER '%s' must not already have an explicit type"_err_en_US);
3436     } else if (folded) {
3437       auto at{expr.thing.value().source};
3438       if (evaluate::IsActuallyConstant(*folded)) {
3439         if (const auto *type{currScope().GetType(*folded)}) {
3440           if (type->IsPolymorphic()) {
3441             Say(at, "The expression must not be polymorphic"_err_en_US);
3442           } else if (auto shape{ToArraySpec(
3443                          GetFoldingContext(), evaluate::GetShape(*folded))}) {
3444             // The type of the named constant is assumed from the expression.
3445             details.set_type(*type);
3446             details.set_init(std::move(*folded));
3447             details.set_shape(std::move(*shape));
3448           } else {
3449             Say(at, "The expression must have constant shape"_err_en_US);
3450           }
3451         } else {
3452           Say(at, "The expression must have a known type"_err_en_US);
3453         }
3454       } else {
3455         Say(at, "The expression must be a constant of known type"_err_en_US);
3456       }
3457     }
3458   } else {
3459     // standard-conforming PARAMETER statement (with parentheses)
3460     ApplyImplicitRules(symbol);
3461     Walk(expr);
3462     if (auto converted{EvaluateNonPointerInitializer(
3463             symbol, expr, expr.thing.value().source)}) {
3464       details.set_init(std::move(*converted));
3465     }
3466   }
3467   return false;
3468 }
3469 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3470   const parser::Name &name{x.v};
3471   if (!FindSymbol(name)) {
3472     Say(name, "Named constant '%s' not found"_err_en_US);
3473   } else {
3474     CheckUseError(name);
3475   }
3476   return false;
3477 }
3478 
3479 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3480   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3481   Symbol *symbol{FindSymbol(name)};
3482   if (symbol && !symbol->has<UnknownDetails>()) {
3483     // Contrary to named constants appearing in a PARAMETER statement,
3484     // enumerator names should not have their type, dimension or any other
3485     // attributes defined before they are declared in the enumerator statement,
3486     // with the exception of accessibility.
3487     // This is not explicitly forbidden by the standard, but they are scalars
3488     // which type is left for the compiler to chose, so do not let users try to
3489     // tamper with that.
3490     SayAlreadyDeclared(name, *symbol);
3491     symbol = nullptr;
3492   } else {
3493     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3494     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3495     symbol->SetType(context().MakeNumericType(
3496         TypeCategory::Integer, evaluate::CInteger::kind));
3497   }
3498 
3499   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3500           enumerator.t)}) {
3501     Walk(*init); // Resolve names in expression before evaluation.
3502     if (auto value{EvaluateInt64(context(), *init)}) {
3503       // Cast all init expressions to C_INT so that they can then be
3504       // safely incremented (see 7.6 Note 2).
3505       enumerationState_.value = static_cast<int>(*value);
3506     } else {
3507       Say(name,
3508           "Enumerator value could not be computed "
3509           "from the given expression"_err_en_US);
3510       // Prevent resolution of next enumerators value
3511       enumerationState_.value = std::nullopt;
3512     }
3513   }
3514 
3515   if (symbol) {
3516     if (enumerationState_.value) {
3517       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3518           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3519     } else {
3520       context().SetError(*symbol);
3521     }
3522   }
3523 
3524   if (enumerationState_.value) {
3525     (*enumerationState_.value)++;
3526   }
3527   return false;
3528 }
3529 
3530 void DeclarationVisitor::Post(const parser::EnumDef &) {
3531   enumerationState_ = EnumeratorState{};
3532 }
3533 
3534 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3535   Attr attr{AccessSpecToAttr(x)};
3536   if (!NonDerivedTypeScope().IsModule()) { // C817
3537     Say(currStmtSource().value(),
3538         "%s attribute may only appear in the specification part of a module"_err_en_US,
3539         EnumToString(attr));
3540   }
3541   CheckAndSet(attr);
3542   return false;
3543 }
3544 
3545 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3546   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3547 }
3548 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3549   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3550 }
3551 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3552   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3553   for (const auto &name : x.v) {
3554     auto *symbol{FindSymbol(name)};
3555     if (!ConvertToProcEntity(*symbol)) {
3556       SayWithDecl(
3557           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3558     } else if (symbol->attrs().test(Attr::INTRINSIC)) { // C840
3559       Say(symbol->name(),
3560           "Symbol '%s' cannot have both INTRINSIC and EXTERNAL attributes"_err_en_US,
3561           symbol->name());
3562     }
3563   }
3564   return false;
3565 }
3566 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3567   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3568   auto &names{std::get<std::list<parser::Name>>(x.t)};
3569   return CheckNotInBlock("INTENT") && // C1107
3570       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3571 }
3572 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3573   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3574   for (const auto &name : x.v) {
3575     auto &symbol{DEREF(FindSymbol(name))};
3576     if (!ConvertToProcEntity(symbol)) {
3577       SayWithDecl(
3578           name, symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3579     } else if (symbol.attrs().test(Attr::EXTERNAL)) { // C840
3580       Say(symbol.name(),
3581           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3582           symbol.name());
3583     } else if (symbol.GetType()) {
3584       // These warnings are worded so that they should make sense in either
3585       // order.
3586       Say(symbol.name(),
3587           "Explicit type declaration ignored for intrinsic function '%s'"_en_US,
3588           symbol.name())
3589           .Attach(name.source,
3590               "INTRINSIC statement for explicitly-typed '%s'"_en_US,
3591               name.source);
3592     }
3593   }
3594   return false;
3595 }
3596 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3597   return CheckNotInBlock("OPTIONAL") && // C1107
3598       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3599 }
3600 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3601   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3602 }
3603 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3604   return CheckNotInBlock("VALUE") && // C1107
3605       HandleAttributeStmt(Attr::VALUE, x.v);
3606 }
3607 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
3608   return HandleAttributeStmt(Attr::VOLATILE, x.v);
3609 }
3610 // Handle a statement that sets an attribute on a list of names.
3611 bool DeclarationVisitor::HandleAttributeStmt(
3612     Attr attr, const std::list<parser::Name> &names) {
3613   for (const auto &name : names) {
3614     HandleAttributeStmt(attr, name);
3615   }
3616   return false;
3617 }
3618 Symbol &DeclarationVisitor::HandleAttributeStmt(
3619     Attr attr, const parser::Name &name) {
3620   if (attr == Attr::INTRINSIC && !IsIntrinsic(name.source, std::nullopt)) {
3621     Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
3622   }
3623   auto *symbol{FindInScope(name)};
3624   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
3625     // these can be set on a symbol that is host-assoc or use-assoc
3626     if (!symbol &&
3627         (currScope().kind() == Scope::Kind::Subprogram ||
3628             currScope().kind() == Scope::Kind::Block)) {
3629       if (auto *hostSymbol{FindSymbol(name)}) {
3630         symbol = &MakeHostAssocSymbol(name, *hostSymbol);
3631       }
3632     }
3633   } else if (symbol && symbol->has<UseDetails>()) {
3634     Say(currStmtSource().value(),
3635         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
3636         EnumToString(attr), name.source);
3637     return *symbol;
3638   }
3639   if (!symbol) {
3640     symbol = &MakeSymbol(name, EntityDetails{});
3641   }
3642   symbol->attrs().set(attr);
3643   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
3644   return *symbol;
3645 }
3646 // C1107
3647 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
3648   if (currScope().kind() == Scope::Kind::Block) {
3649     Say(MessageFormattedText{
3650         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
3651     return false;
3652   } else {
3653     return true;
3654   }
3655 }
3656 
3657 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
3658   CHECK(objectDeclAttr_);
3659   const auto &name{std::get<parser::ObjectName>(x.t)};
3660   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
3661 }
3662 
3663 // Declare an entity not yet known to be an object or proc.
3664 Symbol &DeclarationVisitor::DeclareUnknownEntity(
3665     const parser::Name &name, Attrs attrs) {
3666   if (!arraySpec().empty() || !coarraySpec().empty()) {
3667     return DeclareObjectEntity(name, attrs);
3668   } else {
3669     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
3670     if (auto *type{GetDeclTypeSpec()}) {
3671       SetType(name, *type);
3672     }
3673     charInfo_.length.reset();
3674     SetBindNameOn(symbol);
3675     if (symbol.attrs().test(Attr::EXTERNAL)) {
3676       ConvertToProcEntity(symbol);
3677     }
3678     return symbol;
3679   }
3680 }
3681 
3682 bool DeclarationVisitor::HasCycle(
3683     const Symbol &procSymbol, const ProcInterface &interface) {
3684   OrderedSymbolSet procsInCycle;
3685   procsInCycle.insert(procSymbol);
3686   const ProcInterface *thisInterface{&interface};
3687   bool haveInterface{true};
3688   while (haveInterface) {
3689     haveInterface = false;
3690     if (const Symbol * interfaceSymbol{thisInterface->symbol()}) {
3691       if (procsInCycle.count(*interfaceSymbol) > 0) {
3692         for (const auto &procInCycle : procsInCycle) {
3693           Say(procInCycle->name(),
3694               "The interface for procedure '%s' is recursively "
3695               "defined"_err_en_US,
3696               procInCycle->name());
3697           context().SetError(*procInCycle);
3698         }
3699         return true;
3700       } else if (const auto *procDetails{
3701                      interfaceSymbol->detailsIf<ProcEntityDetails>()}) {
3702         haveInterface = true;
3703         thisInterface = &procDetails->interface();
3704         procsInCycle.insert(*interfaceSymbol);
3705       }
3706     }
3707   }
3708   return false;
3709 }
3710 
3711 Symbol &DeclarationVisitor::DeclareProcEntity(
3712     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
3713   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
3714   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
3715     if (details->IsInterfaceSet()) {
3716       SayWithDecl(name, symbol,
3717           "The interface for procedure '%s' has already been "
3718           "declared"_err_en_US);
3719       context().SetError(symbol);
3720     } else if (HasCycle(symbol, interface)) {
3721       return symbol;
3722     } else if (interface.type()) {
3723       symbol.set(Symbol::Flag::Function);
3724     } else if (interface.symbol()) {
3725       if (interface.symbol()->test(Symbol::Flag::Function)) {
3726         symbol.set(Symbol::Flag::Function);
3727       } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
3728         symbol.set(Symbol::Flag::Subroutine);
3729       }
3730     }
3731     details->set_interface(interface);
3732     SetBindNameOn(symbol);
3733     SetPassNameOn(symbol);
3734   }
3735   return symbol;
3736 }
3737 
3738 Symbol &DeclarationVisitor::DeclareObjectEntity(
3739     const parser::Name &name, Attrs attrs) {
3740   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
3741   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
3742     if (auto *type{GetDeclTypeSpec()}) {
3743       SetType(name, *type);
3744     }
3745     if (!arraySpec().empty()) {
3746       if (details->IsArray()) {
3747         if (!context().HasError(symbol)) {
3748           Say(name,
3749               "The dimensions of '%s' have already been declared"_err_en_US);
3750           context().SetError(symbol);
3751         }
3752       } else {
3753         details->set_shape(arraySpec());
3754       }
3755     }
3756     if (!coarraySpec().empty()) {
3757       if (details->IsCoarray()) {
3758         if (!context().HasError(symbol)) {
3759           Say(name,
3760               "The codimensions of '%s' have already been declared"_err_en_US);
3761           context().SetError(symbol);
3762         }
3763       } else {
3764         details->set_coshape(coarraySpec());
3765       }
3766     }
3767     SetBindNameOn(symbol);
3768   }
3769   ClearArraySpec();
3770   ClearCoarraySpec();
3771   charInfo_.length.reset();
3772   return symbol;
3773 }
3774 
3775 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
3776   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
3777 }
3778 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
3779   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
3780 }
3781 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
3782   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
3783 }
3784 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
3785   SetDeclTypeSpec(MakeLogicalType(x.kind));
3786 }
3787 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
3788   if (!charInfo_.length) {
3789     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
3790   }
3791   if (!charInfo_.kind) {
3792     charInfo_.kind =
3793         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
3794   }
3795   SetDeclTypeSpec(currScope().MakeCharacterType(
3796       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
3797   charInfo_ = {};
3798 }
3799 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
3800   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
3801   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
3802   if (intKind &&
3803       !evaluate::IsValidKindOfIntrinsicType(
3804           TypeCategory::Character, *intKind)) { // C715, C719
3805     Say(currStmtSource().value(),
3806         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
3807     charInfo_.kind = std::nullopt; // prevent further errors
3808   }
3809   if (x.length) {
3810     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
3811   }
3812 }
3813 void DeclarationVisitor::Post(const parser::CharLength &x) {
3814   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
3815     charInfo_.length = ParamValue{
3816         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
3817   } else {
3818     charInfo_.length = GetParamValue(
3819         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
3820   }
3821 }
3822 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
3823   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
3824     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
3825   }
3826 }
3827 
3828 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
3829   if (const auto *kind{std::get_if<
3830           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
3831           &x.u)}) {
3832     const parser::Name &name{kind->thing.thing.thing};
3833     if (!FindSymbol(name)) {
3834       Say(name, "Parameter '%s' not found"_err_en_US);
3835     }
3836   }
3837   return false;
3838 }
3839 
3840 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
3841   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
3842   return true;
3843 }
3844 
3845 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
3846   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
3847   if (const Symbol * derivedSymbol{derivedName.symbol}) {
3848     CheckForAbstractType(*derivedSymbol); // C706
3849   }
3850 }
3851 
3852 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
3853   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
3854   return true;
3855 }
3856 
3857 void DeclarationVisitor::Post(
3858     const parser::DeclarationTypeSpec::Class &parsedClass) {
3859   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
3860   if (auto spec{ResolveDerivedType(typeName)};
3861       spec && !IsExtensibleType(&*spec)) { // C705
3862     SayWithDecl(typeName, *typeName.symbol,
3863         "Non-extensible derived type '%s' may not be used with CLASS"
3864         " keyword"_err_en_US);
3865   }
3866 }
3867 
3868 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Record &) {
3869   // TODO
3870   return true;
3871 }
3872 
3873 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
3874   const auto &typeName{std::get<parser::Name>(x.t)};
3875   auto spec{ResolveDerivedType(typeName)};
3876   if (!spec) {
3877     return;
3878   }
3879   bool seenAnyName{false};
3880   for (const auto &typeParamSpec :
3881       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
3882     const auto &optKeyword{
3883         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
3884     std::optional<SourceName> name;
3885     if (optKeyword) {
3886       seenAnyName = true;
3887       name = optKeyword->v.source;
3888     } else if (seenAnyName) {
3889       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
3890       continue;
3891     }
3892     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
3893     // The expressions in a derived type specifier whose values define
3894     // non-defaulted type parameters are evaluated (folded) in the enclosing
3895     // scope.  The KIND/LEN distinction is resolved later in
3896     // DerivedTypeSpec::CookParameters().
3897     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
3898     if (!param.isExplicit() || param.GetExplicit()) {
3899       spec->AddRawParamValue(optKeyword, std::move(param));
3900     }
3901   }
3902 
3903   // The DerivedTypeSpec *spec is used initially as a search key.
3904   // If it turns out to have the same name and actual parameter
3905   // value expressions as another DerivedTypeSpec in the current
3906   // scope does, then we'll use that extant spec; otherwise, when this
3907   // spec is distinct from all derived types previously instantiated
3908   // in the current scope, this spec will be moved into that collection.
3909   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
3910   auto category{GetDeclTypeSpecCategory()};
3911   if (dtDetails.isForwardReferenced()) {
3912     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
3913     SetDeclTypeSpec(type);
3914     return;
3915   }
3916   // Normalize parameters to produce a better search key.
3917   spec->CookParameters(GetFoldingContext());
3918   if (!spec->MightBeParameterized()) {
3919     spec->EvaluateParameters(context());
3920   }
3921   if (const DeclTypeSpec *
3922       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
3923     // This derived type and parameter expressions (if any) are already present
3924     // in this scope.
3925     SetDeclTypeSpec(*extant);
3926   } else {
3927     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
3928     DerivedTypeSpec &derived{type.derivedTypeSpec()};
3929     if (derived.MightBeParameterized() &&
3930         currScope().IsParameterizedDerivedType()) {
3931       // Defer instantiation; use the derived type's definition's scope.
3932       derived.set_scope(DEREF(spec->typeSymbol().scope()));
3933     } else {
3934       auto restorer{
3935           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
3936       derived.Instantiate(currScope());
3937     }
3938     SetDeclTypeSpec(type);
3939   }
3940   // Capture the DerivedTypeSpec in the parse tree for use in building
3941   // structure constructor expressions.
3942   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
3943 }
3944 
3945 // The descendents of DerivedTypeDef in the parse tree are visited directly
3946 // in this Pre() routine so that recursive use of the derived type can be
3947 // supported in the components.
3948 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
3949   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
3950   Walk(stmt);
3951   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
3952   auto &scope{currScope()};
3953   CHECK(scope.symbol());
3954   CHECK(scope.symbol()->scope() == &scope);
3955   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
3956   std::set<SourceName> paramNames;
3957   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
3958     details.add_paramName(paramName.source);
3959     auto *symbol{FindInScope(scope, paramName)};
3960     if (!symbol) {
3961       Say(paramName,
3962           "No definition found for type parameter '%s'"_err_en_US); // C742
3963       // No symbol for a type param.  Create one and mark it as containing an
3964       // error to improve subsequent semantic processing
3965       BeginAttrs();
3966       Symbol *typeParam{MakeTypeSymbol(
3967           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
3968       context().SetError(*typeParam);
3969       EndAttrs();
3970     } else if (!symbol->has<TypeParamDetails>()) {
3971       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
3972           *symbol, "Definition of '%s'"_en_US); // C741
3973     }
3974     if (!paramNames.insert(paramName.source).second) {
3975       Say(paramName,
3976           "Duplicate type parameter name: '%s'"_err_en_US); // C731
3977     }
3978   }
3979   for (const auto &[name, symbol] : currScope()) {
3980     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
3981       SayDerivedType(name,
3982           "'%s' is not a type parameter of this derived type"_err_en_US,
3983           currScope()); // C741
3984     }
3985   }
3986   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
3987   const auto &componentDefs{
3988       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
3989   Walk(componentDefs);
3990   if (derivedTypeInfo_.sequence) {
3991     details.set_sequence(true);
3992     if (componentDefs.empty()) { // C740
3993       Say(stmt.source,
3994           "A sequence type must have at least one component"_err_en_US);
3995     }
3996     if (!details.paramNames().empty()) { // C740
3997       Say(stmt.source,
3998           "A sequence type may not have type parameters"_err_en_US);
3999     }
4000     if (derivedTypeInfo_.extends) { // C735
4001       Say(stmt.source,
4002           "A sequence type may not have the EXTENDS attribute"_err_en_US);
4003     } else {
4004       for (const auto &componentName : details.componentNames()) {
4005         const Symbol *componentSymbol{scope.FindComponent(componentName)};
4006         if (componentSymbol && componentSymbol->has<ObjectEntityDetails>()) {
4007           const auto &componentDetails{
4008               componentSymbol->get<ObjectEntityDetails>()};
4009           const DeclTypeSpec *componentType{componentDetails.type()};
4010           if (componentType && // C740
4011               !componentType->AsIntrinsic() &&
4012               !componentType->IsSequenceType()) {
4013             Say(componentSymbol->name(),
4014                 "A sequence type data component must either be of an"
4015                 " intrinsic type or a derived sequence type"_err_en_US);
4016           }
4017         }
4018       }
4019     }
4020   }
4021   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
4022   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
4023   derivedTypeInfo_ = {};
4024   PopScope();
4025   return false;
4026 }
4027 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
4028   return BeginAttrs();
4029 }
4030 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
4031   auto &name{std::get<parser::Name>(x.t)};
4032   // Resolve the EXTENDS() clause before creating the derived
4033   // type's symbol to foil attempts to recursively extend a type.
4034   auto *extendsName{derivedTypeInfo_.extends};
4035   std::optional<DerivedTypeSpec> extendsType{
4036       ResolveExtendsType(name, extendsName)};
4037   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
4038   symbol.ReplaceName(name.source);
4039   derivedTypeInfo_.type = &symbol;
4040   PushScope(Scope::Kind::DerivedType, &symbol);
4041   if (extendsType) {
4042     // Declare the "parent component"; private if the type is.
4043     // Any symbol stored in the EXTENDS() clause is temporarily
4044     // hidden so that a new symbol can be created for the parent
4045     // component without producing spurious errors about already
4046     // existing.
4047     const Symbol &extendsSymbol{extendsType->typeSymbol()};
4048     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
4049     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
4050       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
4051       comp.attrs().set(
4052           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
4053       comp.set(Symbol::Flag::ParentComp);
4054       DeclTypeSpec &type{currScope().MakeDerivedType(
4055           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
4056       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
4057       comp.SetType(type);
4058       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
4059       details.add_component(comp);
4060     }
4061   }
4062   EndAttrs();
4063 }
4064 
4065 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
4066   auto *type{GetDeclTypeSpec()};
4067   auto attr{std::get<common::TypeParamAttr>(x.t)};
4068   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
4069     auto &name{std::get<parser::Name>(decl.t)};
4070     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
4071       SetType(name, *type);
4072       if (auto &init{
4073               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
4074         if (auto maybeExpr{EvaluateNonPointerInitializer(
4075                 *symbol, *init, init->thing.thing.thing.value().source)}) {
4076           if (auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)}) {
4077             symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
4078           }
4079         }
4080       }
4081     }
4082   }
4083   EndDecl();
4084 }
4085 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
4086   if (derivedTypeInfo_.extends) {
4087     Say(currStmtSource().value(),
4088         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
4089   } else {
4090     derivedTypeInfo_.extends = &x.v;
4091   }
4092   return false;
4093 }
4094 
4095 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
4096   if (!currScope().parent().IsModule()) {
4097     Say("PRIVATE is only allowed in a derived type that is"
4098         " in a module"_err_en_US); // C766
4099   } else if (derivedTypeInfo_.sawContains) {
4100     derivedTypeInfo_.privateBindings = true;
4101   } else if (!derivedTypeInfo_.privateComps) {
4102     derivedTypeInfo_.privateComps = true;
4103   } else {
4104     Say("PRIVATE may not appear more than once in"
4105         " derived type components"_en_US); // C738
4106   }
4107   return false;
4108 }
4109 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
4110   if (derivedTypeInfo_.sequence) {
4111     Say("SEQUENCE may not appear more than once in"
4112         " derived type components"_en_US); // C738
4113   }
4114   derivedTypeInfo_.sequence = true;
4115   return false;
4116 }
4117 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
4118   const auto &name{std::get<parser::Name>(x.t)};
4119   auto attrs{GetAttrs()};
4120   if (derivedTypeInfo_.privateComps &&
4121       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
4122     attrs.set(Attr::PRIVATE);
4123   }
4124   if (const auto *declType{GetDeclTypeSpec()}) {
4125     if (const auto *derived{declType->AsDerived()}) {
4126       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4127         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
4128           Say("Recursive use of the derived type requires "
4129               "POINTER or ALLOCATABLE"_err_en_US);
4130         }
4131       }
4132       if (!coarraySpec().empty()) { // C747
4133         if (IsTeamType(derived)) {
4134           Say("A coarray component may not be of type TEAM_TYPE from "
4135               "ISO_FORTRAN_ENV"_err_en_US);
4136         } else {
4137           if (IsIsoCType(derived)) {
4138             Say("A coarray component may not be of type C_PTR or C_FUNPTR from "
4139                 "ISO_C_BINDING"_err_en_US);
4140           }
4141         }
4142       }
4143       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
4144         std::string ultimateName{it.BuildResultDesignatorName()};
4145         // Strip off the leading "%"
4146         if (ultimateName.length() > 1) {
4147           ultimateName.erase(0, 1);
4148           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
4149             evaluate::AttachDeclaration(
4150                 Say(name.source,
4151                     "A component with a POINTER or ALLOCATABLE attribute may "
4152                     "not "
4153                     "be of a type with a coarray ultimate component (named "
4154                     "'%s')"_err_en_US,
4155                     ultimateName),
4156                 derived->typeSymbol());
4157           }
4158           if (!arraySpec().empty() || !coarraySpec().empty()) {
4159             evaluate::AttachDeclaration(
4160                 Say(name.source,
4161                     "An array or coarray component may not be of a type with a "
4162                     "coarray ultimate component (named '%s')"_err_en_US,
4163                     ultimateName),
4164                 derived->typeSymbol());
4165           }
4166         }
4167       }
4168     }
4169   }
4170   if (OkToAddComponent(name)) {
4171     auto &symbol{DeclareObjectEntity(name, attrs)};
4172     if (symbol.has<ObjectEntityDetails>()) {
4173       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
4174         Initialization(name, *init, true);
4175       }
4176     }
4177     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
4178   }
4179   ClearArraySpec();
4180   ClearCoarraySpec();
4181 }
4182 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
4183   CHECK(!interfaceName_);
4184   return BeginDecl();
4185 }
4186 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
4187   interfaceName_ = nullptr;
4188   EndDecl();
4189 }
4190 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
4191   // Overrides parse tree traversal so as to handle attributes first,
4192   // so POINTER & ALLOCATABLE enable forward references to derived types.
4193   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
4194   set_allowForwardReferenceToDerivedType(
4195       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
4196   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
4197   set_allowForwardReferenceToDerivedType(false);
4198   Walk(std::get<std::list<parser::ComponentDecl>>(x.t));
4199   return false;
4200 }
4201 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
4202   CHECK(!interfaceName_);
4203   return true;
4204 }
4205 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
4206   interfaceName_ = nullptr;
4207 }
4208 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
4209   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4210     return !NameIsKnownOrIntrinsic(*name);
4211   }
4212   return true;
4213 }
4214 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
4215   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
4216     interfaceName_ = name;
4217     NoteInterfaceName(*name);
4218   }
4219 }
4220 
4221 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
4222   const auto &name{std::get<parser::Name>(x.t)};
4223   ProcInterface interface;
4224   if (interfaceName_) {
4225     interface.set_symbol(*interfaceName_->symbol);
4226   } else if (auto *type{GetDeclTypeSpec()}) {
4227     interface.set_type(*type);
4228   }
4229   auto attrs{HandleSaveName(name.source, GetAttrs())};
4230   DerivedTypeDetails *dtDetails{nullptr};
4231   if (Symbol * symbol{currScope().symbol()}) {
4232     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
4233   }
4234   if (!dtDetails) {
4235     attrs.set(Attr::EXTERNAL);
4236   }
4237   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
4238   symbol.ReplaceName(name.source);
4239   if (dtDetails) {
4240     dtDetails->add_component(symbol);
4241   }
4242 }
4243 
4244 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
4245   derivedTypeInfo_.sawContains = true;
4246   return true;
4247 }
4248 
4249 // Resolve binding names from type-bound generics, saved in genericBindings_.
4250 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
4251   // track specifics seen for the current generic to detect duplicates:
4252   const Symbol *currGeneric{nullptr};
4253   std::set<SourceName> specifics;
4254   for (const auto &[generic, bindingName] : genericBindings_) {
4255     if (generic != currGeneric) {
4256       currGeneric = generic;
4257       specifics.clear();
4258     }
4259     auto [it, inserted]{specifics.insert(bindingName->source)};
4260     if (!inserted) {
4261       Say(*bindingName, // C773
4262           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4263           bindingName->source, generic->name())
4264           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4265       continue;
4266     }
4267     auto *symbol{FindInTypeOrParents(*bindingName)};
4268     if (!symbol) {
4269       Say(*bindingName, // C772
4270           "Binding name '%s' not found in this derived type"_err_en_US);
4271     } else if (!symbol->has<ProcBindingDetails>()) {
4272       SayWithDecl(*bindingName, *symbol, // C772
4273           "'%s' is not the name of a specific binding of this type"_err_en_US);
4274     } else {
4275       generic->get<GenericDetails>().AddSpecificProc(
4276           *symbol, bindingName->source);
4277     }
4278   }
4279   genericBindings_.clear();
4280 }
4281 
4282 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4283   if (derivedTypeInfo_.sequence) {
4284     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4285   }
4286 }
4287 
4288 void DeclarationVisitor::Post(
4289     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4290   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4291     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4292   }
4293   for (auto &declaration : x.declarations) {
4294     auto &bindingName{std::get<parser::Name>(declaration.t)};
4295     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4296     const parser::Name &procedureName{optName ? *optName : bindingName};
4297     Symbol *procedure{FindSymbol(procedureName)};
4298     if (!procedure) {
4299       procedure = NoteInterfaceName(procedureName);
4300     }
4301     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4302       SetPassNameOn(*s);
4303       if (GetAttrs().test(Attr::DEFERRED)) {
4304         context().SetError(*s);
4305       }
4306     }
4307   }
4308 }
4309 
4310 void DeclarationVisitor::CheckBindings(
4311     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4312   CHECK(currScope().IsDerivedType());
4313   for (auto &declaration : tbps.declarations) {
4314     auto &bindingName{std::get<parser::Name>(declaration.t)};
4315     if (Symbol * binding{FindInScope(bindingName)}) {
4316       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4317         const Symbol *procedure{FindSubprogram(details->symbol())};
4318         if (!CanBeTypeBoundProc(procedure)) {
4319           if (details->symbol().name() != binding->name()) {
4320             Say(binding->name(),
4321                 "The binding of '%s' ('%s') must be either an accessible "
4322                 "module procedure or an external procedure with "
4323                 "an explicit interface"_err_en_US,
4324                 binding->name(), details->symbol().name());
4325           } else {
4326             Say(binding->name(),
4327                 "'%s' must be either an accessible module procedure "
4328                 "or an external procedure with an explicit interface"_err_en_US,
4329                 binding->name());
4330           }
4331           context().SetError(*binding);
4332         }
4333       }
4334     }
4335   }
4336 }
4337 
4338 void DeclarationVisitor::Post(
4339     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4340   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4341     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4342   }
4343   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4344     for (auto &bindingName : x.bindingNames) {
4345       if (auto *s{
4346               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4347         SetPassNameOn(*s);
4348         if (!GetAttrs().test(Attr::DEFERRED)) {
4349           context().SetError(*s);
4350         }
4351       }
4352     }
4353   }
4354 }
4355 
4356 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4357   if (currScope().IsDerivedType() && currScope().symbol()) {
4358     if (auto *details{currScope().symbol()->detailsIf<DerivedTypeDetails>()}) {
4359       for (const auto &subrName : x.v) {
4360         if (const auto *name{ResolveName(subrName)}) {
4361           auto pair{
4362               details->finals().emplace(name->source, DEREF(name->symbol))};
4363           if (!pair.second) { // C787
4364             Say(name->source,
4365                 "FINAL subroutine '%s' already appeared in this derived type"_err_en_US,
4366                 name->source)
4367                 .Attach(pair.first->first,
4368                     "earlier appearance of this FINAL subroutine"_en_US);
4369           }
4370         }
4371       }
4372     }
4373   }
4374 }
4375 
4376 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4377   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4378   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4379   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4380   auto info{GenericSpecInfo{genericSpec.value()}};
4381   SourceName symbolName{info.symbolName()};
4382   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4383                             : derivedTypeInfo_.privateBindings};
4384   auto *genericSymbol{FindInScope(symbolName)};
4385   if (genericSymbol) {
4386     if (!genericSymbol->has<GenericDetails>()) {
4387       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4388     }
4389   } else {
4390     // look in parent types:
4391     Symbol *inheritedSymbol{nullptr};
4392     for (const auto &name : GetAllNames(context(), symbolName)) {
4393       inheritedSymbol = currScope().FindComponent(SourceName{name});
4394       if (inheritedSymbol) {
4395         break;
4396       }
4397     }
4398     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4399       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4400     }
4401   }
4402   if (genericSymbol) {
4403     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4404   } else {
4405     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4406     if (!genericSymbol) {
4407       return false;
4408     }
4409     if (isPrivate) {
4410       genericSymbol->attrs().set(Attr::PRIVATE);
4411     }
4412   }
4413   for (const parser::Name &bindingName : bindingNames) {
4414     genericBindings_.emplace(genericSymbol, &bindingName);
4415   }
4416   info.Resolve(genericSymbol);
4417   return false;
4418 }
4419 
4420 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4421   BeginDeclTypeSpec();
4422   return true;
4423 }
4424 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4425   EndDeclTypeSpec();
4426 }
4427 
4428 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4429   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4430   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4431   if (!type) {
4432     return false;
4433   }
4434   const DerivedTypeSpec *spec{type->AsDerived()};
4435   const Scope *typeScope{spec ? spec->scope() : nullptr};
4436   if (!typeScope) {
4437     return false;
4438   }
4439 
4440   // N.B C7102 is implicitly enforced by having inaccessible types not
4441   // being found in resolution.
4442   // More constraints are enforced in expression.cpp so that they
4443   // can apply to structure constructors that have been converted
4444   // from misparsed function references.
4445   for (const auto &component :
4446       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4447     // Visit the component spec expression, but not the keyword, since
4448     // we need to resolve its symbol in the scope of the derived type.
4449     Walk(std::get<parser::ComponentDataSource>(component.t));
4450     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4451       FindInTypeOrParents(*typeScope, kw->v);
4452     }
4453   }
4454   return false;
4455 }
4456 
4457 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4458   for (const parser::BasedPointer &bp : x.v) {
4459     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4460     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4461     auto *pointer{FindSymbol(pointerName)};
4462     if (!pointer) {
4463       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4464     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4465       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4466     } else if (pointer->Rank() > 0) {
4467       SayWithDecl(pointerName, *pointer,
4468           "Cray pointer '%s' must be a scalar"_err_en_US);
4469     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4470       Say(pointerName,
4471           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4472     }
4473     pointer->set(Symbol::Flag::CrayPointer);
4474     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4475         context().defaultKinds().subscriptIntegerKind())};
4476     const auto *type{pointer->GetType()};
4477     if (!type) {
4478       pointer->SetType(pointerType);
4479     } else if (*type != pointerType) {
4480       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4481           pointerName.source, pointerType.AsFortran());
4482     }
4483     if (ResolveName(pointeeName)) {
4484       Symbol &pointee{*pointeeName.symbol};
4485       if (pointee.has<UseDetails>()) {
4486         Say(pointeeName,
4487             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4488         continue;
4489       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4490         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4491         continue;
4492       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4493         Say(pointeeName,
4494             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4495       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4496         Say(pointeeName,
4497             "'%s' was already declared as a Cray pointee"_err_en_US);
4498       } else {
4499         pointee.set(Symbol::Flag::CrayPointee);
4500       }
4501       if (const auto *pointeeType{pointee.GetType()}) {
4502         if (const auto *derived{pointeeType->AsDerived()}) {
4503           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
4504             Say(pointeeName,
4505                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
4506           }
4507         }
4508       }
4509       // process the pointee array-spec, if present
4510       BeginArraySpec();
4511       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
4512       const auto &spec{arraySpec()};
4513       if (!spec.empty()) {
4514         auto &details{pointee.get<ObjectEntityDetails>()};
4515         if (details.shape().empty()) {
4516           details.set_shape(spec);
4517         } else {
4518           SayWithDecl(pointeeName, pointee,
4519               "Array spec was already declared for '%s'"_err_en_US);
4520         }
4521       }
4522       ClearArraySpec();
4523       currScope().add_crayPointer(pointeeName.source, *pointer);
4524     }
4525   }
4526   return false;
4527 }
4528 
4529 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
4530   if (!CheckNotInBlock("NAMELIST")) { // C1107
4531     return false;
4532   }
4533 
4534   NamelistDetails details;
4535   for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
4536     auto *symbol{FindSymbol(name)};
4537     if (!symbol) {
4538       symbol = &MakeSymbol(name, ObjectEntityDetails{});
4539       ApplyImplicitRules(*symbol);
4540     } else if (!ConvertToObjectEntity(*symbol)) {
4541       SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
4542     }
4543     symbol->GetUltimate().set(Symbol::Flag::InNamelist);
4544     details.add_object(*symbol);
4545   }
4546 
4547   const auto &groupName{std::get<parser::Name>(x.t)};
4548   auto *groupSymbol{FindInScope(groupName)};
4549   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
4550     groupSymbol = &MakeSymbol(groupName, std::move(details));
4551     groupSymbol->ReplaceName(groupName.source);
4552   }
4553   groupSymbol->get<NamelistDetails>().add_objects(details.objects());
4554   return false;
4555 }
4556 
4557 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
4558   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
4559     auto *symbol{FindSymbol(*name)};
4560     if (!symbol) {
4561       Say(*name, "Namelist group '%s' not found"_err_en_US);
4562     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
4563       SayWithDecl(
4564           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
4565     }
4566   }
4567   return true;
4568 }
4569 
4570 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
4571   CheckNotInBlock("COMMON"); // C1107
4572   return true;
4573 }
4574 
4575 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
4576   BeginArraySpec();
4577   return true;
4578 }
4579 
4580 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
4581   const auto &name{std::get<parser::Name>(x.t)};
4582   DeclareObjectEntity(name);
4583   auto pair{specPartState_.commonBlockObjects.insert(name.source)};
4584   if (!pair.second) {
4585     const SourceName &prev{*pair.first};
4586     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
4587         "Previous occurrence of '%s' in a COMMON block"_en_US);
4588   }
4589 }
4590 
4591 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
4592   // save equivalence sets to be processed after specification part
4593   if (CheckNotInBlock("EQUIVALENCE")) { // C1107
4594     for (const std::list<parser::EquivalenceObject> &set : x.v) {
4595       specPartState_.equivalenceSets.push_back(&set);
4596     }
4597   }
4598   return false; // don't implicitly declare names yet
4599 }
4600 
4601 void DeclarationVisitor::CheckEquivalenceSets() {
4602   EquivalenceSets equivSets{context()};
4603   inEquivalenceStmt_ = true;
4604   for (const auto *set : specPartState_.equivalenceSets) {
4605     const auto &source{set->front().v.value().source};
4606     if (set->size() <= 1) { // R871
4607       Say(source, "Equivalence set must have more than one object"_err_en_US);
4608     }
4609     for (const parser::EquivalenceObject &object : *set) {
4610       const auto &designator{object.v.value()};
4611       // The designator was not resolved when it was encountered so do it now.
4612       // AnalyzeExpr causes array sections to be changed to substrings as needed
4613       Walk(designator);
4614       if (AnalyzeExpr(context(), designator)) {
4615         equivSets.AddToSet(designator);
4616       }
4617     }
4618     equivSets.FinishSet(source);
4619   }
4620   inEquivalenceStmt_ = false;
4621   for (auto &set : equivSets.sets()) {
4622     if (!set.empty()) {
4623       currScope().add_equivalenceSet(std::move(set));
4624     }
4625   }
4626   specPartState_.equivalenceSets.clear();
4627 }
4628 
4629 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
4630   if (x.v.empty()) {
4631     specPartState_.saveInfo.saveAll = currStmtSource();
4632     currScope().set_hasSAVE();
4633   } else {
4634     for (const parser::SavedEntity &y : x.v) {
4635       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
4636       const auto &name{std::get<parser::Name>(y.t)};
4637       if (kind == parser::SavedEntity::Kind::Common) {
4638         MakeCommonBlockSymbol(name);
4639         AddSaveName(specPartState_.saveInfo.commons, name.source);
4640       } else {
4641         HandleAttributeStmt(Attr::SAVE, name);
4642       }
4643     }
4644   }
4645   return false;
4646 }
4647 
4648 void DeclarationVisitor::CheckSaveStmts() {
4649   for (const SourceName &name : specPartState_.saveInfo.entities) {
4650     auto *symbol{FindInScope(name)};
4651     if (!symbol) {
4652       // error was reported
4653     } else if (specPartState_.saveInfo.saveAll) {
4654       // C889 - note that pgi, ifort, xlf do not enforce this constraint
4655       Say2(name,
4656           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
4657           *specPartState_.saveInfo.saveAll, "Global SAVE statement"_en_US);
4658     } else if (auto msg{CheckSaveAttr(*symbol)}) {
4659       Say(name, std::move(*msg));
4660       context().SetError(*symbol);
4661     } else {
4662       SetSaveAttr(*symbol);
4663     }
4664   }
4665   for (const SourceName &name : specPartState_.saveInfo.commons) {
4666     if (auto *symbol{currScope().FindCommonBlock(name)}) {
4667       auto &objects{symbol->get<CommonBlockDetails>().objects()};
4668       if (objects.empty()) {
4669         if (currScope().kind() != Scope::Kind::Block) {
4670           Say(name,
4671               "'%s' appears as a COMMON block in a SAVE statement but not in"
4672               " a COMMON statement"_err_en_US);
4673         } else { // C1108
4674           Say(name,
4675               "SAVE statement in BLOCK construct may not contain a"
4676               " common block name '%s'"_err_en_US);
4677         }
4678       } else {
4679         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
4680           SetSaveAttr(*object);
4681         }
4682       }
4683     }
4684   }
4685   if (specPartState_.saveInfo.saveAll) {
4686     // Apply SAVE attribute to applicable symbols
4687     for (auto pair : currScope()) {
4688       auto &symbol{*pair.second};
4689       if (!CheckSaveAttr(symbol)) {
4690         SetSaveAttr(symbol);
4691       }
4692     }
4693   }
4694   specPartState_.saveInfo = {};
4695 }
4696 
4697 // If SAVE attribute can't be set on symbol, return error message.
4698 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
4699     const Symbol &symbol) {
4700   if (IsDummy(symbol)) {
4701     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
4702   } else if (symbol.IsFuncResult()) {
4703     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
4704   } else if (symbol.has<ProcEntityDetails>() &&
4705       !symbol.attrs().test(Attr::POINTER)) {
4706     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
4707   } else if (IsAutomatic(symbol)) {
4708     return "SAVE attribute may not be applied to automatic data object '%s'"_err_en_US;
4709   } else {
4710     return std::nullopt;
4711   }
4712 }
4713 
4714 // Record SAVEd names in specPartState_.saveInfo.entities.
4715 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
4716   if (attrs.test(Attr::SAVE)) {
4717     AddSaveName(specPartState_.saveInfo.entities, name);
4718   }
4719   return attrs;
4720 }
4721 
4722 // Record a name in a set of those to be saved.
4723 void DeclarationVisitor::AddSaveName(
4724     std::set<SourceName> &set, const SourceName &name) {
4725   auto pair{set.insert(name)};
4726   if (!pair.second) {
4727     Say2(name, "SAVE attribute was already specified on '%s'"_err_en_US,
4728         *pair.first, "Previous specification of SAVE attribute"_en_US);
4729   }
4730 }
4731 
4732 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
4733 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
4734   if (!IsSaved(symbol)) {
4735     symbol.attrs().set(Attr::SAVE);
4736   }
4737 }
4738 
4739 // Check types of common block objects, now that they are known.
4740 void DeclarationVisitor::CheckCommonBlocks() {
4741   // check for empty common blocks
4742   for (const auto &pair : currScope().commonBlocks()) {
4743     const auto &symbol{*pair.second};
4744     if (symbol.get<CommonBlockDetails>().objects().empty() &&
4745         symbol.attrs().test(Attr::BIND_C)) {
4746       Say(symbol.name(),
4747           "'%s' appears as a COMMON block in a BIND statement but not in"
4748           " a COMMON statement"_err_en_US);
4749     }
4750   }
4751   // check objects in common blocks
4752   for (const auto &name : specPartState_.commonBlockObjects) {
4753     const auto *symbol{currScope().FindSymbol(name)};
4754     if (!symbol) {
4755       continue;
4756     }
4757     const auto &attrs{symbol->attrs()};
4758     if (attrs.test(Attr::ALLOCATABLE)) {
4759       Say(name,
4760           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
4761     } else if (attrs.test(Attr::BIND_C)) {
4762       Say(name,
4763           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
4764     } else if (IsDummy(*symbol)) {
4765       Say(name,
4766           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
4767     } else if (symbol->IsFuncResult()) {
4768       Say(name,
4769           "Function result '%s' may not appear in a COMMON block"_err_en_US);
4770     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
4771       if (type->category() == DeclTypeSpec::ClassStar) {
4772         Say(name,
4773             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
4774       } else if (const auto *derived{type->AsDerived()}) {
4775         auto &typeSymbol{derived->typeSymbol()};
4776         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
4777             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
4778           Say(name,
4779               "Derived type '%s' in COMMON block must have the BIND or"
4780               " SEQUENCE attribute"_err_en_US);
4781         }
4782         CheckCommonBlockDerivedType(name, typeSymbol);
4783       }
4784     }
4785   }
4786   specPartState_.commonBlockObjects = {};
4787 }
4788 
4789 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
4790   return Resolve(name, currScope().MakeCommonBlock(name.source));
4791 }
4792 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(
4793     const std::optional<parser::Name> &name) {
4794   if (name) {
4795     return MakeCommonBlockSymbol(*name);
4796   } else {
4797     return MakeCommonBlockSymbol(parser::Name{});
4798   }
4799 }
4800 
4801 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
4802   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
4803 }
4804 
4805 // Check if this derived type can be in a COMMON block.
4806 void DeclarationVisitor::CheckCommonBlockDerivedType(
4807     const SourceName &name, const Symbol &typeSymbol) {
4808   if (const auto *scope{typeSymbol.scope()}) {
4809     for (const auto &pair : *scope) {
4810       const Symbol &component{*pair.second};
4811       if (component.attrs().test(Attr::ALLOCATABLE)) {
4812         Say2(name,
4813             "Derived type variable '%s' may not appear in a COMMON block"
4814             " due to ALLOCATABLE component"_err_en_US,
4815             component.name(), "Component with ALLOCATABLE attribute"_en_US);
4816         return;
4817       }
4818       if (const auto *details{component.detailsIf<ObjectEntityDetails>()}) {
4819         if (details->init()) {
4820           Say2(name,
4821               "Derived type variable '%s' may not appear in a COMMON block"
4822               " due to component with default initialization"_err_en_US,
4823               component.name(), "Component with default initialization"_en_US);
4824           return;
4825         }
4826         if (const auto *type{details->type()}) {
4827           if (const auto *derived{type->AsDerived()}) {
4828             CheckCommonBlockDerivedType(name, derived->typeSymbol());
4829           }
4830         }
4831       }
4832     }
4833   }
4834 }
4835 
4836 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
4837     const parser::Name &name) {
4838   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
4839           name.source.ToString())}) {
4840     // Unrestricted specific intrinsic function names (e.g., "cos")
4841     // are acceptable as procedure interfaces.
4842     Symbol &symbol{
4843         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
4844     symbol.set_details(ProcEntityDetails{});
4845     symbol.set(Symbol::Flag::Function);
4846     if (interface->IsElemental()) {
4847       symbol.attrs().set(Attr::ELEMENTAL);
4848     }
4849     if (interface->IsPure()) {
4850       symbol.attrs().set(Attr::PURE);
4851     }
4852     Resolve(name, symbol);
4853     return true;
4854   } else {
4855     return false;
4856   }
4857 }
4858 
4859 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
4860 bool DeclarationVisitor::PassesSharedLocalityChecks(
4861     const parser::Name &name, Symbol &symbol) {
4862   if (!IsVariableName(symbol)) {
4863     SayLocalMustBeVariable(name, symbol); // C1124
4864     return false;
4865   }
4866   if (symbol.owner() == currScope()) { // C1125 and C1126
4867     SayAlreadyDeclared(name, symbol);
4868     return false;
4869   }
4870   return true;
4871 }
4872 
4873 // Checks for locality-specs LOCAL and LOCAL_INIT
4874 bool DeclarationVisitor::PassesLocalityChecks(
4875     const parser::Name &name, Symbol &symbol) {
4876   if (IsAllocatable(symbol)) { // C1128
4877     SayWithDecl(name, symbol,
4878         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
4879     return false;
4880   }
4881   if (IsOptional(symbol)) { // C1128
4882     SayWithDecl(name, symbol,
4883         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
4884     return false;
4885   }
4886   if (IsIntentIn(symbol)) { // C1128
4887     SayWithDecl(name, symbol,
4888         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
4889     return false;
4890   }
4891   if (IsFinalizable(symbol)) { // C1128
4892     SayWithDecl(name, symbol,
4893         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
4894     return false;
4895   }
4896   if (IsCoarray(symbol)) { // C1128
4897     SayWithDecl(
4898         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
4899     return false;
4900   }
4901   if (const DeclTypeSpec * type{symbol.GetType()}) {
4902     if (type->IsPolymorphic() && IsDummy(symbol) &&
4903         !IsPointer(symbol)) { // C1128
4904       SayWithDecl(name, symbol,
4905           "Nonpointer polymorphic argument '%s' not allowed in a "
4906           "locality-spec"_err_en_US);
4907       return false;
4908     }
4909   }
4910   if (IsAssumedSizeArray(symbol)) { // C1128
4911     SayWithDecl(name, symbol,
4912         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
4913     return false;
4914   }
4915   if (std::optional<MessageFixedText> msg{
4916           WhyNotModifiable(symbol, currScope())}) {
4917     SayWithReason(name, symbol,
4918         "'%s' may not appear in a locality-spec because it is not "
4919         "definable"_err_en_US,
4920         std::move(*msg));
4921     return false;
4922   }
4923   return PassesSharedLocalityChecks(name, symbol);
4924 }
4925 
4926 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
4927     const parser::Name &name) {
4928   Symbol *prev{FindSymbol(name)};
4929   if (!prev) {
4930     // Declare the name as an object in the enclosing scope so that
4931     // the name can't be repurposed there later as something else.
4932     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
4933     ConvertToObjectEntity(*prev);
4934     ApplyImplicitRules(*prev);
4935   }
4936   return *prev;
4937 }
4938 
4939 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
4940   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
4941   if (!PassesLocalityChecks(name, prev)) {
4942     return nullptr;
4943   }
4944   return &MakeHostAssocSymbol(name, prev);
4945 }
4946 
4947 Symbol *DeclarationVisitor::DeclareStatementEntity(const parser::Name &name,
4948     const std::optional<parser::IntegerTypeSpec> &type) {
4949   const DeclTypeSpec *declTypeSpec{nullptr};
4950   if (auto *prev{FindSymbol(name)}) {
4951     if (prev->owner() == currScope()) {
4952       SayAlreadyDeclared(name, *prev);
4953       return nullptr;
4954     }
4955     name.symbol = nullptr;
4956     declTypeSpec = prev->GetType();
4957   }
4958   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
4959   if (!symbol.has<ObjectEntityDetails>()) {
4960     return nullptr; // error was reported in DeclareEntity
4961   }
4962   if (type) {
4963     declTypeSpec = ProcessTypeSpec(*type);
4964   }
4965   if (declTypeSpec) {
4966     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
4967     // declaration of this implied DO loop control variable.
4968     auto restorer{
4969         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
4970     SetType(name, *declTypeSpec);
4971   } else {
4972     ApplyImplicitRules(symbol);
4973   }
4974   return Resolve(name, &symbol);
4975 }
4976 
4977 // Set the type of an entity or report an error.
4978 void DeclarationVisitor::SetType(
4979     const parser::Name &name, const DeclTypeSpec &type) {
4980   CHECK(name.symbol);
4981   auto &symbol{*name.symbol};
4982   if (charInfo_.length) { // Declaration has "*length" (R723)
4983     auto length{std::move(*charInfo_.length)};
4984     charInfo_.length.reset();
4985     if (type.category() == DeclTypeSpec::Character) {
4986       auto kind{type.characterTypeSpec().kind()};
4987       // Recurse with correct type.
4988       SetType(name,
4989           currScope().MakeCharacterType(std::move(length), std::move(kind)));
4990       return;
4991     } else { // C753
4992       Say(name,
4993           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
4994     }
4995   }
4996   auto *prevType{symbol.GetType()};
4997   if (!prevType) {
4998     symbol.SetType(type);
4999   } else if (symbol.has<UseDetails>()) {
5000     // error recovery case, redeclaration of use-associated name
5001   } else if (HadForwardRef(symbol)) {
5002     // error recovery after use of host-associated name
5003   } else if (!symbol.test(Symbol::Flag::Implicit)) {
5004     SayWithDecl(
5005         name, symbol, "The type of '%s' has already been declared"_err_en_US);
5006     context().SetError(symbol);
5007   } else if (type != *prevType) {
5008     SayWithDecl(name, symbol,
5009         "The type of '%s' has already been implicitly declared"_err_en_US);
5010     context().SetError(symbol);
5011   } else {
5012     symbol.set(Symbol::Flag::Implicit, false);
5013   }
5014 }
5015 
5016 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
5017     const parser::Name &name) {
5018   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5019   if (!symbol || symbol->has<UnknownDetails>()) {
5020     if (allowForwardReferenceToDerivedType()) {
5021       if (!symbol) {
5022         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
5023         Resolve(name, *symbol);
5024       };
5025       DerivedTypeDetails details;
5026       details.set_isForwardReferenced();
5027       symbol->set_details(std::move(details));
5028     } else { // C732
5029       Say(name, "Derived type '%s' not found"_err_en_US);
5030       return std::nullopt;
5031     }
5032   }
5033   if (CheckUseError(name)) {
5034     return std::nullopt;
5035   }
5036   symbol = &symbol->GetUltimate();
5037   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
5038     if (details->derivedType()) {
5039       symbol = details->derivedType();
5040     }
5041   }
5042   if (symbol->has<DerivedTypeDetails>()) {
5043     return DerivedTypeSpec{name.source, *symbol};
5044   } else {
5045     Say(name, "'%s' is not a derived type"_err_en_US);
5046     return std::nullopt;
5047   }
5048 }
5049 
5050 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
5051     const parser::Name &typeName, const parser::Name *extendsName) {
5052   if (!extendsName) {
5053     return std::nullopt;
5054   } else if (typeName.source == extendsName->source) {
5055     Say(extendsName->source,
5056         "Derived type '%s' cannot extend itself"_err_en_US);
5057     return std::nullopt;
5058   } else {
5059     return ResolveDerivedType(*extendsName);
5060   }
5061 }
5062 
5063 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
5064   // The symbol is checked later by CheckExplicitInterface() and
5065   // CheckBindings().  It can be a forward reference.
5066   if (!NameIsKnownOrIntrinsic(name)) {
5067     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
5068     Resolve(name, symbol);
5069   }
5070   return name.symbol;
5071 }
5072 
5073 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
5074   if (const Symbol * symbol{name.symbol}) {
5075     if (!context().HasError(*symbol) && !symbol->HasExplicitInterface()) {
5076       Say(name,
5077           "'%s' must be an abstract interface or a procedure with "
5078           "an explicit interface"_err_en_US,
5079           symbol->name());
5080     }
5081   }
5082 }
5083 
5084 // Create a symbol for a type parameter, component, or procedure binding in
5085 // the current derived type scope. Return false on error.
5086 Symbol *DeclarationVisitor::MakeTypeSymbol(
5087     const parser::Name &name, Details &&details) {
5088   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
5089 }
5090 Symbol *DeclarationVisitor::MakeTypeSymbol(
5091     const SourceName &name, Details &&details) {
5092   Scope &derivedType{currScope()};
5093   CHECK(derivedType.IsDerivedType());
5094   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
5095     Say2(name,
5096         "Type parameter, component, or procedure binding '%s'"
5097         " already defined in this type"_err_en_US,
5098         *symbol, "Previous definition of '%s'"_en_US);
5099     return nullptr;
5100   } else {
5101     auto attrs{GetAttrs()};
5102     // Apply binding-private-stmt if present and this is a procedure binding
5103     if (derivedTypeInfo_.privateBindings &&
5104         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
5105         std::holds_alternative<ProcBindingDetails>(details)) {
5106       attrs.set(Attr::PRIVATE);
5107     }
5108     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
5109     if (result.has<TypeParamDetails>()) {
5110       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
5111     }
5112     return &result;
5113   }
5114 }
5115 
5116 // Return true if it is ok to declare this component in the current scope.
5117 // Otherwise, emit an error and return false.
5118 bool DeclarationVisitor::OkToAddComponent(
5119     const parser::Name &name, const Symbol *extends) {
5120   for (const Scope *scope{&currScope()}; scope;) {
5121     CHECK(scope->IsDerivedType());
5122     if (auto *prev{FindInScope(*scope, name)}) {
5123       if (!context().HasError(*prev)) {
5124         auto msg{""_en_US};
5125         if (extends) {
5126           msg = "Type cannot be extended as it has a component named"
5127                 " '%s'"_err_en_US;
5128         } else if (prev->test(Symbol::Flag::ParentComp)) {
5129           msg = "'%s' is a parent type of this type and so cannot be"
5130                 " a component"_err_en_US;
5131         } else if (scope != &currScope()) {
5132           msg = "Component '%s' is already declared in a parent of this"
5133                 " derived type"_err_en_US;
5134         } else {
5135           msg = "Component '%s' is already declared in this"
5136                 " derived type"_err_en_US;
5137         }
5138         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
5139       }
5140       return false;
5141     }
5142     if (scope == &currScope() && extends) {
5143       // The parent component has not yet been added to the scope.
5144       scope = extends->scope();
5145     } else {
5146       scope = scope->GetDerivedTypeParent();
5147     }
5148   }
5149   return true;
5150 }
5151 
5152 ParamValue DeclarationVisitor::GetParamValue(
5153     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
5154   return std::visit(
5155       common::visitors{
5156           [=](const parser::ScalarIntExpr &x) { // C704
5157             return ParamValue{EvaluateIntExpr(x), attr};
5158           },
5159           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
5160           [=](const parser::TypeParamValue::Deferred &) {
5161             return ParamValue::Deferred(attr);
5162           },
5163       },
5164       x.u);
5165 }
5166 
5167 // ConstructVisitor implementation
5168 
5169 void ConstructVisitor::ResolveIndexName(
5170     const parser::ConcurrentControl &control) {
5171   const parser::Name &name{std::get<parser::Name>(control.t)};
5172   auto *prev{FindSymbol(name)};
5173   if (prev) {
5174     if (prev->owner().kind() == Scope::Kind::Forall ||
5175         prev->owner() == currScope()) {
5176       SayAlreadyDeclared(name, *prev);
5177       return;
5178     }
5179     name.symbol = nullptr;
5180   }
5181   auto &symbol{DeclareObjectEntity(name)};
5182   if (symbol.GetType()) {
5183     // type came from explicit type-spec
5184   } else if (!prev) {
5185     ApplyImplicitRules(symbol);
5186   } else {
5187     const Symbol &prevRoot{ResolveAssociations(*prev)};
5188     // prev could be host- use- or construct-associated with another symbol
5189     if (!prevRoot.has<ObjectEntityDetails>() &&
5190         !prevRoot.has<EntityDetails>()) {
5191       Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
5192           *prev, "Previous declaration of '%s'"_en_US);
5193       return;
5194     } else {
5195       if (const auto *type{prevRoot.GetType()}) {
5196         symbol.SetType(*type);
5197       }
5198       if (prevRoot.IsObjectArray()) {
5199         SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
5200         return;
5201       }
5202     }
5203   }
5204   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
5205 }
5206 
5207 // We need to make sure that all of the index-names get declared before the
5208 // expressions in the loop control are evaluated so that references to the
5209 // index-names in the expressions are correctly detected.
5210 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
5211   BeginDeclTypeSpec();
5212   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
5213   const auto &controls{
5214       std::get<std::list<parser::ConcurrentControl>>(header.t)};
5215   for (const auto &control : controls) {
5216     ResolveIndexName(control);
5217   }
5218   Walk(controls);
5219   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
5220   EndDeclTypeSpec();
5221   return false;
5222 }
5223 
5224 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
5225   for (auto &name : x.v) {
5226     if (auto *symbol{DeclareLocalEntity(name)}) {
5227       symbol->set(Symbol::Flag::LocalityLocal);
5228     }
5229   }
5230   return false;
5231 }
5232 
5233 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
5234   for (auto &name : x.v) {
5235     if (auto *symbol{DeclareLocalEntity(name)}) {
5236       symbol->set(Symbol::Flag::LocalityLocalInit);
5237     }
5238   }
5239   return false;
5240 }
5241 
5242 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
5243   for (const auto &name : x.v) {
5244     if (!FindSymbol(name)) {
5245       Say(name, "Variable '%s' with SHARED locality implicitly declared"_en_US);
5246     }
5247     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
5248     if (PassesSharedLocalityChecks(name, prev)) {
5249       MakeHostAssocSymbol(name, prev).set(Symbol::Flag::LocalityShared);
5250     }
5251   }
5252   return false;
5253 }
5254 
5255 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
5256   ProcessTypeSpec(x.type);
5257   PushScope(Scope::Kind::ImpliedDos, nullptr);
5258   Walk(x.values);
5259   PopScope();
5260   return false;
5261 }
5262 
5263 // Section 19.4, paragraph 5 says that each ac-do-variable has the scope of the
5264 // enclosing ac-implied-do
5265 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
5266   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
5267   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
5268   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
5269   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5270   PushScope(Scope::Kind::ImpliedDos, nullptr);
5271   DeclareStatementEntity(bounds.name.thing.thing, type);
5272   Walk(bounds);
5273   Walk(values);
5274   PopScope();
5275   return false;
5276 }
5277 
5278 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5279   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5280   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5281   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5282   DeclareStatementEntity(bounds.name.thing.thing, type);
5283   Walk(bounds);
5284   Walk(objects);
5285   return false;
5286 }
5287 
5288 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5289 // statement so that the predicate IsStaticallyInitialized() will be true
5290 // during semantic analysis before the symbol's initializer is constructed.
5291 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5292   std::visit(
5293       common::visitors{
5294           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5295             Walk(y.thing.value());
5296             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5297             if (first.symbol) {
5298               first.symbol->set(Symbol::Flag::InDataStmt);
5299             }
5300           },
5301           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5302       },
5303       x.u);
5304   return false;
5305 }
5306 
5307 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5308   std::visit(common::visitors{
5309                  [&](const Indirection<parser::Variable> &y) {
5310                    Walk(y.value());
5311                    const parser::Name &first{parser::GetFirstName(y.value())};
5312                    if (first.symbol) {
5313                      first.symbol->set(Symbol::Flag::InDataStmt);
5314                    }
5315                  },
5316                  [&](const parser::DataImpliedDo &y) {
5317                    PushScope(Scope::Kind::ImpliedDos, nullptr);
5318                    Walk(y);
5319                    PopScope();
5320                  },
5321              },
5322       x.u);
5323   return false;
5324 }
5325 
5326 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5327   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5328   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5329   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5330     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5331       if (const Symbol * symbol{FindSymbol(*name)}) {
5332         const Symbol &ultimate{symbol->GetUltimate()};
5333         if (ultimate.has<DerivedTypeDetails>()) {
5334           mutableData.u = elem->ConvertToStructureConstructor(
5335               DerivedTypeSpec{name->source, ultimate});
5336         }
5337       }
5338     }
5339   }
5340   return true;
5341 }
5342 
5343 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5344   if (x.IsDoConcurrent()) {
5345     PushScope(Scope::Kind::Block, nullptr);
5346   }
5347   return true;
5348 }
5349 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5350   if (x.IsDoConcurrent()) {
5351     PopScope();
5352   }
5353 }
5354 
5355 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5356   PushScope(Scope::Kind::Forall, nullptr);
5357   return true;
5358 }
5359 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5360 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5361   PushScope(Scope::Kind::Forall, nullptr);
5362   return true;
5363 }
5364 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5365 
5366 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5367   CheckDef(x.v);
5368   PushScope(Scope::Kind::Block, nullptr);
5369   return false;
5370 }
5371 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5372   PopScope();
5373   CheckRef(x.v);
5374   return false;
5375 }
5376 
5377 void ConstructVisitor::Post(const parser::Selector &x) {
5378   GetCurrentAssociation().selector = ResolveSelector(x);
5379 }
5380 
5381 void ConstructVisitor::Post(const parser::AssociateStmt &x) {
5382   CheckDef(x.t);
5383   PushScope(Scope::Kind::Block, nullptr);
5384   const auto assocCount{std::get<std::list<parser::Association>>(x.t).size()};
5385   for (auto nthLastAssoc{assocCount}; nthLastAssoc > 0; --nthLastAssoc) {
5386     SetCurrentAssociation(nthLastAssoc);
5387     if (auto *symbol{MakeAssocEntity()}) {
5388       if (ExtractCoarrayRef(GetCurrentAssociation().selector.expr)) { // C1103
5389         Say("Selector must not be a coindexed object"_err_en_US);
5390       }
5391       SetTypeFromAssociation(*symbol);
5392       SetAttrsFromAssociation(*symbol);
5393     }
5394   }
5395   PopAssociation(assocCount);
5396 }
5397 
5398 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5399   PopScope();
5400   CheckRef(x.v);
5401 }
5402 
5403 bool ConstructVisitor::Pre(const parser::Association &x) {
5404   PushAssociation();
5405   const auto &name{std::get<parser::Name>(x.t)};
5406   GetCurrentAssociation().name = &name;
5407   return true;
5408 }
5409 
5410 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5411   CheckDef(x.t);
5412   PushScope(Scope::Kind::Block, nullptr);
5413   PushAssociation();
5414   return true;
5415 }
5416 
5417 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5418   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5419   const auto &name{std::get<parser::Name>(decl.t)};
5420   if (auto *symbol{FindInScope(name)}) {
5421     const auto &selector{std::get<parser::Selector>(x.t)};
5422     if (auto sel{ResolveSelector(selector)}) {
5423       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5424       if (!whole || whole->Corank() == 0) {
5425         Say(sel.source, // C1116
5426             "Selector in coarray association must name a coarray"_err_en_US);
5427       } else if (auto dynType{sel.expr->GetType()}) {
5428         if (!symbol->GetType()) {
5429           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5430         }
5431       }
5432     }
5433   }
5434 }
5435 
5436 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5437   PopAssociation();
5438   PopScope();
5439   CheckRef(x.t);
5440 }
5441 
5442 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5443   PushAssociation();
5444   return true;
5445 }
5446 
5447 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5448   PopAssociation();
5449 }
5450 
5451 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
5452   auto &association{GetCurrentAssociation()};
5453   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5454     // This isn't a name in the current scope, it is in each TypeGuardStmt
5455     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
5456     association.name = &*name;
5457     auto exprType{association.selector.expr->GetType()};
5458     if (ExtractCoarrayRef(association.selector.expr)) { // C1103
5459       Say("Selector must not be a coindexed object"_err_en_US);
5460     }
5461     if (exprType && !exprType->IsPolymorphic()) { // C1159
5462       Say(association.selector.source,
5463           "Selector '%s' in SELECT TYPE statement must be "
5464           "polymorphic"_err_en_US);
5465     }
5466   } else {
5467     if (const Symbol *
5468         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5469       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
5470       if (!IsVariableName(*whole)) {
5471         Say(association.selector.source, // C901
5472             "Selector is not a variable"_err_en_US);
5473         association = {};
5474       }
5475       if (const DeclTypeSpec * type{whole->GetType()}) {
5476         if (!type->IsPolymorphic()) { // C1159
5477           Say(association.selector.source,
5478               "Selector '%s' in SELECT TYPE statement must be "
5479               "polymorphic"_err_en_US);
5480         }
5481       }
5482     } else {
5483       Say(association.selector.source, // C1157
5484           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
5485       association = {};
5486     }
5487   }
5488 }
5489 
5490 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
5491   auto &association{GetCurrentAssociation()};
5492   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5493     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
5494     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
5495     association.name = &*name;
5496   }
5497 }
5498 
5499 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
5500   PushScope(Scope::Kind::Block, nullptr);
5501   return true;
5502 }
5503 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
5504   PopScope();
5505 }
5506 
5507 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
5508   PushScope(Scope::Kind::Block, nullptr);
5509   return true;
5510 }
5511 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
5512   PopScope();
5513 }
5514 
5515 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
5516   if (auto *symbol{MakeAssocEntity()}) {
5517     if (std::holds_alternative<parser::Default>(x.u)) {
5518       SetTypeFromAssociation(*symbol);
5519     } else if (const auto *type{GetDeclTypeSpec()}) {
5520       symbol->SetType(*type);
5521     }
5522     SetAttrsFromAssociation(*symbol);
5523   }
5524 }
5525 
5526 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
5527   if (auto *symbol{MakeAssocEntity()}) {
5528     SetTypeFromAssociation(*symbol);
5529     SetAttrsFromAssociation(*symbol);
5530     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
5531       if (auto val{EvaluateInt64(context(), *init)}) {
5532         auto &details{symbol->get<AssocEntityDetails>()};
5533         details.set_rank(*val);
5534       }
5535     }
5536   }
5537 }
5538 
5539 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
5540   PushAssociation();
5541   return true;
5542 }
5543 
5544 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
5545   PopAssociation();
5546 }
5547 
5548 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
5549   if (x) {
5550     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
5551   }
5552   return true;
5553 }
5554 
5555 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
5556   if (x) {
5557     // Just add an occurrence of this name; checking is done in ValidateLabels
5558     FindSymbol(*x);
5559   }
5560 }
5561 
5562 // Make a symbol for the associating entity of the current association.
5563 Symbol *ConstructVisitor::MakeAssocEntity() {
5564   Symbol *symbol{nullptr};
5565   auto &association{GetCurrentAssociation()};
5566   if (association.name) {
5567     symbol = &MakeSymbol(*association.name, UnknownDetails{});
5568     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
5569       Say(*association.name, // C1102
5570           "The associate name '%s' is already used in this associate statement"_err_en_US);
5571       return nullptr;
5572     }
5573   } else if (const Symbol *
5574       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5575     symbol = &MakeSymbol(whole->name());
5576   } else {
5577     return nullptr;
5578   }
5579   if (auto &expr{association.selector.expr}) {
5580     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
5581   } else {
5582     symbol->set_details(AssocEntityDetails{});
5583   }
5584   return symbol;
5585 }
5586 
5587 // Set the type of symbol based on the current association selector.
5588 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
5589   auto &details{symbol.get<AssocEntityDetails>()};
5590   const MaybeExpr *pexpr{&details.expr()};
5591   if (!*pexpr) {
5592     pexpr = &GetCurrentAssociation().selector.expr;
5593   }
5594   if (*pexpr) {
5595     const SomeExpr &expr{**pexpr};
5596     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
5597       if (const auto *charExpr{
5598               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
5599                   expr)}) {
5600         symbol.SetType(ToDeclTypeSpec(std::move(*type),
5601             FoldExpr(
5602                 std::visit([](const auto &kindChar) { return kindChar.LEN(); },
5603                     charExpr->u))));
5604       } else {
5605         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
5606       }
5607     } else {
5608       // BOZ literals, procedure designators, &c. are not acceptable
5609       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
5610     }
5611   }
5612 }
5613 
5614 // If current selector is a variable, set some of its attributes on symbol.
5615 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
5616   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
5617   symbol.attrs() |= attrs &
5618       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
5619   if (attrs.test(Attr::POINTER)) {
5620     symbol.attrs().set(Attr::TARGET);
5621   }
5622 }
5623 
5624 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
5625     const parser::Selector &x) {
5626   return std::visit(common::visitors{
5627                         [&](const parser::Expr &expr) {
5628                           return Selector{expr.source, EvaluateExpr(expr)};
5629                         },
5630                         [&](const parser::Variable &var) {
5631                           return Selector{var.GetSource(), EvaluateExpr(var)};
5632                         },
5633                     },
5634       x.u);
5635 }
5636 
5637 // Set the current association to the nth to the last association on the
5638 // association stack.  The top of the stack is at n = 1.  This allows access
5639 // to the interior of a list of associations at the top of the stack.
5640 void ConstructVisitor::SetCurrentAssociation(std::size_t n) {
5641   CHECK(n > 0 && n <= associationStack_.size());
5642   currentAssociation_ = &associationStack_[associationStack_.size() - n];
5643 }
5644 
5645 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
5646   CHECK(currentAssociation_);
5647   return *currentAssociation_;
5648 }
5649 
5650 void ConstructVisitor::PushAssociation() {
5651   associationStack_.emplace_back(Association{});
5652   currentAssociation_ = &associationStack_.back();
5653 }
5654 
5655 void ConstructVisitor::PopAssociation(std::size_t count) {
5656   CHECK(count > 0 && count <= associationStack_.size());
5657   associationStack_.resize(associationStack_.size() - count);
5658   currentAssociation_ =
5659       associationStack_.empty() ? nullptr : &associationStack_.back();
5660 }
5661 
5662 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5663     evaluate::DynamicType &&type) {
5664   switch (type.category()) {
5665     SWITCH_COVERS_ALL_CASES
5666   case common::TypeCategory::Integer:
5667   case common::TypeCategory::Real:
5668   case common::TypeCategory::Complex:
5669     return context().MakeNumericType(type.category(), type.kind());
5670   case common::TypeCategory::Logical:
5671     return context().MakeLogicalType(type.kind());
5672   case common::TypeCategory::Derived:
5673     if (type.IsAssumedType()) {
5674       return currScope().MakeTypeStarType();
5675     } else if (type.IsUnlimitedPolymorphic()) {
5676       return currScope().MakeClassStarType();
5677     } else {
5678       return currScope().MakeDerivedType(
5679           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
5680                                : DeclTypeSpec::TypeDerived,
5681           common::Clone(type.GetDerivedTypeSpec())
5682 
5683       );
5684     }
5685   case common::TypeCategory::Character:
5686     CRASH_NO_CASE;
5687   }
5688 }
5689 
5690 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5691     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
5692   CHECK(type.category() == common::TypeCategory::Character);
5693   if (length) {
5694     return currScope().MakeCharacterType(
5695         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
5696         KindExpr{type.kind()});
5697   } else {
5698     return currScope().MakeCharacterType(
5699         ParamValue::Deferred(common::TypeParamAttr::Len),
5700         KindExpr{type.kind()});
5701   }
5702 }
5703 
5704 // ResolveNamesVisitor implementation
5705 
5706 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
5707   HandleCall(Symbol::Flag::Function, x.v);
5708   return false;
5709 }
5710 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
5711   HandleCall(Symbol::Flag::Subroutine, x.v);
5712   return false;
5713 }
5714 
5715 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
5716   auto &scope{currScope()};
5717   // Check C896 and C899: where IMPORT statements are allowed
5718   switch (scope.kind()) {
5719   case Scope::Kind::Module:
5720     if (scope.IsModule()) {
5721       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
5722       return false;
5723     } else if (x.kind == common::ImportKind::None) {
5724       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
5725       return false;
5726     }
5727     break;
5728   case Scope::Kind::MainProgram:
5729     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
5730     return false;
5731   case Scope::Kind::Subprogram:
5732     if (scope.parent().IsGlobal()) {
5733       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
5734       return false;
5735     }
5736     break;
5737   case Scope::Kind::BlockData: // C1415 (in part)
5738     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
5739     return false;
5740   default:;
5741   }
5742   if (auto error{scope.SetImportKind(x.kind)}) {
5743     Say(std::move(*error));
5744   }
5745   for (auto &name : x.names) {
5746     if (FindSymbol(scope.parent(), name)) {
5747       scope.add_importName(name.source);
5748     } else {
5749       Say(name, "'%s' not found in host scope"_err_en_US);
5750     }
5751   }
5752   prevImportStmt_ = currStmtSource();
5753   return false;
5754 }
5755 
5756 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
5757     const parser::StructureComponent &x) {
5758   return FindComponent(ResolveDataRef(x.base), x.component);
5759 }
5760 
5761 const parser::Name *DeclarationVisitor::ResolveDesignator(
5762     const parser::Designator &x) {
5763   return std::visit(
5764       common::visitors{
5765           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
5766           [&](const parser::Substring &x) {
5767             return ResolveDataRef(std::get<parser::DataRef>(x.t));
5768           },
5769       },
5770       x.u);
5771 }
5772 
5773 const parser::Name *DeclarationVisitor::ResolveDataRef(
5774     const parser::DataRef &x) {
5775   return std::visit(
5776       common::visitors{
5777           [=](const parser::Name &y) { return ResolveName(y); },
5778           [=](const Indirection<parser::StructureComponent> &y) {
5779             return ResolveStructureComponent(y.value());
5780           },
5781           [&](const Indirection<parser::ArrayElement> &y) {
5782             Walk(y.value().subscripts);
5783             const parser::Name *name{ResolveDataRef(y.value().base)};
5784             if (!name) {
5785             } else if (!name->symbol->has<ProcEntityDetails>()) {
5786               ConvertToObjectEntity(*name->symbol);
5787             } else if (!context().HasError(*name->symbol)) {
5788               SayWithDecl(*name, *name->symbol,
5789                   "Cannot reference function '%s' as data"_err_en_US);
5790             }
5791             return name;
5792           },
5793           [&](const Indirection<parser::CoindexedNamedObject> &y) {
5794             Walk(y.value().imageSelector);
5795             return ResolveDataRef(y.value().base);
5796           },
5797       },
5798       x.u);
5799 }
5800 
5801 // If implicit types are allowed, ensure name is in the symbol table.
5802 // Otherwise, report an error if it hasn't been declared.
5803 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
5804   FindSymbol(name);
5805   if (CheckForHostAssociatedImplicit(name)) {
5806     NotePossibleBadForwardRef(name);
5807     return &name;
5808   }
5809   if (Symbol * symbol{name.symbol}) {
5810     if (CheckUseError(name)) {
5811       return nullptr; // reported an error
5812     }
5813     NotePossibleBadForwardRef(name);
5814     symbol->set(Symbol::Flag::ImplicitOrError, false);
5815     if (IsUplevelReference(*symbol)) {
5816       MakeHostAssocSymbol(name, *symbol);
5817     } else if (IsDummy(*symbol) ||
5818         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
5819       ConvertToObjectEntity(*symbol);
5820       ApplyImplicitRules(*symbol);
5821     }
5822     return &name;
5823   }
5824   if (isImplicitNoneType()) {
5825     Say(name, "No explicit type declared for '%s'"_err_en_US);
5826     return nullptr;
5827   }
5828   // Create the symbol then ensure it is accessible
5829   MakeSymbol(InclusiveScope(), name.source, Attrs{});
5830   auto *symbol{FindSymbol(name)};
5831   if (!symbol) {
5832     Say(name,
5833         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
5834     return nullptr;
5835   }
5836   ConvertToObjectEntity(*symbol);
5837   ApplyImplicitRules(*symbol);
5838   NotePossibleBadForwardRef(name);
5839   return &name;
5840 }
5841 
5842 // A specification expression may refer to a symbol in the host procedure that
5843 // is implicitly typed. Because specification parts are processed before
5844 // execution parts, this may be the first time we see the symbol. It can't be a
5845 // local in the current scope (because it's in a specification expression) so
5846 // either it is implicitly declared in the host procedure or it is an error.
5847 // We create a symbol in the host assuming it is the former; if that proves to
5848 // be wrong we report an error later in CheckDeclarations().
5849 bool DeclarationVisitor::CheckForHostAssociatedImplicit(
5850     const parser::Name &name) {
5851   if (inExecutionPart_) {
5852     return false;
5853   }
5854   if (name.symbol) {
5855     ApplyImplicitRules(*name.symbol, true);
5856   }
5857   Symbol *hostSymbol;
5858   Scope *host{GetHostProcedure()};
5859   if (!host || isImplicitNoneType(*host)) {
5860     return false;
5861   }
5862   if (!name.symbol) {
5863     hostSymbol = &MakeSymbol(*host, name.source, Attrs{});
5864     ConvertToObjectEntity(*hostSymbol);
5865     ApplyImplicitRules(*hostSymbol);
5866     hostSymbol->set(Symbol::Flag::ImplicitOrError);
5867   } else if (name.symbol->test(Symbol::Flag::ImplicitOrError)) {
5868     hostSymbol = name.symbol;
5869   } else {
5870     return false;
5871   }
5872   Symbol &symbol{MakeHostAssocSymbol(name, *hostSymbol)};
5873   if (isImplicitNoneType()) {
5874     symbol.get<HostAssocDetails>().implicitOrExplicitTypeError = true;
5875   } else {
5876     symbol.get<HostAssocDetails>().implicitOrSpecExprError = true;
5877   }
5878   return true;
5879 }
5880 
5881 bool DeclarationVisitor::IsUplevelReference(const Symbol &symbol) {
5882   const Scope &symbolUnit{GetProgramUnitContaining(symbol)};
5883   if (symbolUnit == GetProgramUnitContaining(currScope())) {
5884     return false;
5885   } else {
5886     Scope::Kind kind{symbolUnit.kind()};
5887     return kind == Scope::Kind::Subprogram || kind == Scope::Kind::MainProgram;
5888   }
5889 }
5890 
5891 // base is a part-ref of a derived type; find the named component in its type.
5892 // Also handles intrinsic type parameter inquiries (%kind, %len) and
5893 // COMPLEX component references (%re, %im).
5894 const parser::Name *DeclarationVisitor::FindComponent(
5895     const parser::Name *base, const parser::Name &component) {
5896   if (!base || !base->symbol) {
5897     return nullptr;
5898   }
5899   auto &symbol{base->symbol->GetUltimate()};
5900   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
5901     SayWithDecl(*base, symbol,
5902         "'%s' is an invalid base for a component reference"_err_en_US);
5903     return nullptr;
5904   }
5905   auto *type{symbol.GetType()};
5906   if (!type) {
5907     return nullptr; // should have already reported error
5908   }
5909   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
5910     auto name{component.ToString()};
5911     auto category{intrinsic->category()};
5912     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
5913     if (name == "kind") {
5914       miscKind = MiscDetails::Kind::KindParamInquiry;
5915     } else if (category == TypeCategory::Character) {
5916       if (name == "len") {
5917         miscKind = MiscDetails::Kind::LenParamInquiry;
5918       }
5919     } else if (category == TypeCategory::Complex) {
5920       if (name == "re") {
5921         miscKind = MiscDetails::Kind::ComplexPartRe;
5922       } else if (name == "im") {
5923         miscKind = MiscDetails::Kind::ComplexPartIm;
5924       }
5925     }
5926     if (miscKind != MiscDetails::Kind::None) {
5927       MakePlaceholder(component, miscKind);
5928       return nullptr;
5929     }
5930   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
5931     if (const Scope * scope{derived->scope()}) {
5932       if (Resolve(component, scope->FindComponent(component.source))) {
5933         if (auto msg{
5934                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
5935           context().Say(component.source, *msg);
5936         }
5937         return &component;
5938       } else {
5939         SayDerivedType(component.source,
5940             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
5941       }
5942     }
5943     return nullptr;
5944   }
5945   if (symbol.test(Symbol::Flag::Implicit)) {
5946     Say(*base,
5947         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
5948   } else {
5949     SayWithDecl(
5950         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
5951   }
5952   return nullptr;
5953 }
5954 
5955 void DeclarationVisitor::Initialization(const parser::Name &name,
5956     const parser::Initialization &init, bool inComponentDecl) {
5957   // Traversal of the initializer was deferred to here so that the
5958   // symbol being declared can be available for use in the expression, e.g.:
5959   //   real, parameter :: x = tiny(x)
5960   if (!name.symbol) {
5961     return;
5962   }
5963   Symbol &ultimate{name.symbol->GetUltimate()};
5964   if (IsAllocatable(ultimate)) {
5965     Say(name, "Allocatable object '%s' cannot be initialized"_err_en_US);
5966     return;
5967   }
5968   if (auto *object{ultimate.detailsIf<ObjectEntityDetails>()}) {
5969     // TODO: check C762 - all bounds and type parameters of component
5970     // are colons or constant expressions if component is initialized
5971     std::visit(
5972         common::visitors{
5973             [&](const parser::ConstantExpr &expr) {
5974               NonPointerInitialization(name, expr);
5975             },
5976             [&](const parser::NullInit &null) {
5977               Walk(null);
5978               if (auto nullInit{EvaluateExpr(null)}) {
5979                 if (!evaluate::IsNullPointer(*nullInit)) {
5980                   Say(name,
5981                       "Pointer initializer must be intrinsic NULL()"_err_en_US); // C813
5982                 } else if (IsPointer(ultimate)) {
5983                   object->set_init(std::move(*nullInit));
5984                 } else {
5985                   Say(name,
5986                       "Non-pointer component '%s' initialized with null pointer"_err_en_US);
5987                 }
5988               }
5989             },
5990             [&](const parser::InitialDataTarget &) {
5991               // Defer analysis to the end of the specification part
5992               // so that forward references and attribute checks like SAVE
5993               // work better.
5994             },
5995             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
5996               // TODO: Need to Walk(init.u); when implementing this case
5997               if (inComponentDecl) {
5998                 Say(name,
5999                     "Component '%s' initialized with DATA statement values"_err_en_US);
6000               } else {
6001                 // TODO - DATA statements and DATA-like initialization extension
6002               }
6003             },
6004         },
6005         init.u);
6006   }
6007 }
6008 
6009 void DeclarationVisitor::PointerInitialization(
6010     const parser::Name &name, const parser::InitialDataTarget &target) {
6011   if (name.symbol) {
6012     Symbol &ultimate{name.symbol->GetUltimate()};
6013     if (!context().HasError(ultimate)) {
6014       if (IsPointer(ultimate)) {
6015         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6016           CHECK(!details->init());
6017           Walk(target);
6018           if (MaybeExpr expr{EvaluateExpr(target)}) {
6019             // Validation is done in declaration checking.
6020             details->set_init(std::move(*expr));
6021           }
6022         }
6023       } else {
6024         Say(name,
6025             "'%s' is not a pointer but is initialized like one"_err_en_US);
6026         context().SetError(ultimate);
6027       }
6028     }
6029   }
6030 }
6031 void DeclarationVisitor::PointerInitialization(
6032     const parser::Name &name, const parser::ProcPointerInit &target) {
6033   if (name.symbol) {
6034     Symbol &ultimate{name.symbol->GetUltimate()};
6035     if (!context().HasError(ultimate)) {
6036       if (IsProcedurePointer(ultimate)) {
6037         auto &details{ultimate.get<ProcEntityDetails>()};
6038         CHECK(!details.init());
6039         Walk(target);
6040         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
6041           if (targetName->symbol) {
6042             // Validation is done in declaration checking.
6043             details.set_init(*targetName->symbol);
6044           }
6045         } else {
6046           details.set_init(nullptr); // explicit NULL()
6047         }
6048       } else {
6049         Say(name,
6050             "'%s' is not a procedure pointer but is initialized "
6051             "like one"_err_en_US);
6052         context().SetError(ultimate);
6053       }
6054     }
6055   }
6056 }
6057 
6058 void DeclarationVisitor::NonPointerInitialization(
6059     const parser::Name &name, const parser::ConstantExpr &expr) {
6060   if (name.symbol) {
6061     Symbol &ultimate{name.symbol->GetUltimate()};
6062     if (!context().HasError(ultimate)) {
6063       if (IsPointer(ultimate)) {
6064         Say(name,
6065             "'%s' is a pointer but is not initialized like one"_err_en_US);
6066       } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
6067         CHECK(!details->init());
6068         Walk(expr);
6069         if (ultimate.owner().IsParameterizedDerivedType()) {
6070           // Can't convert to type of component, which might not yet
6071           // be known; that's done later during PDT instantiation.
6072           if (MaybeExpr value{EvaluateExpr(expr)}) {
6073             details->set_init(std::move(*value));
6074           }
6075         } else if (MaybeExpr folded{EvaluateNonPointerInitializer(
6076                        ultimate, expr, expr.thing.value().source)}) {
6077           details->set_init(std::move(*folded));
6078         }
6079       }
6080     }
6081   }
6082 }
6083 
6084 void ResolveNamesVisitor::HandleCall(
6085     Symbol::Flag procFlag, const parser::Call &call) {
6086   std::visit(
6087       common::visitors{
6088           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
6089           [&](const parser::ProcComponentRef &x) { Walk(x); },
6090       },
6091       std::get<parser::ProcedureDesignator>(call.t).u);
6092   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
6093 }
6094 
6095 void ResolveNamesVisitor::HandleProcedureName(
6096     Symbol::Flag flag, const parser::Name &name) {
6097   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
6098   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
6099   if (!symbol) {
6100     if (IsIntrinsic(name.source, flag)) {
6101       symbol =
6102           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
6103     } else {
6104       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
6105     }
6106     Resolve(name, *symbol);
6107     if (symbol->has<ModuleDetails>()) {
6108       SayWithDecl(name, *symbol,
6109           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6110       return;
6111     }
6112     if (!symbol->attrs().test(Attr::INTRINSIC)) {
6113       if (!CheckImplicitNoneExternal(name.source, *symbol)) {
6114         return;
6115       }
6116       MakeExternal(*symbol);
6117     }
6118     ConvertToProcEntity(*symbol);
6119     SetProcFlag(name, *symbol, flag);
6120   } else if (CheckUseError(name)) {
6121     // error was reported
6122   } else {
6123     symbol = &Resolve(name, symbol)->GetUltimate();
6124     bool convertedToProcEntity{ConvertToProcEntity(*symbol)};
6125     if (convertedToProcEntity && !symbol->attrs().test(Attr::EXTERNAL) &&
6126         IsIntrinsic(symbol->name(), flag) && !IsDummy(*symbol)) {
6127       AcquireIntrinsicProcedureFlags(*symbol);
6128     }
6129     if (!SetProcFlag(name, *symbol, flag)) {
6130       return; // reported error
6131     }
6132     CheckImplicitNoneExternal(name.source, *symbol);
6133     if (symbol->has<SubprogramDetails>() &&
6134         symbol->attrs().test(Attr::ABSTRACT)) {
6135       Say(name, "Abstract interface '%s' may not be called"_err_en_US);
6136     } else if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
6137         symbol->has<ObjectEntityDetails>() ||
6138         symbol->has<AssocEntityDetails>()) {
6139       // Symbols with DerivedTypeDetails, ObjectEntityDetails and
6140       // AssocEntityDetails are accepted here as procedure-designators because
6141       // this means the related FunctionReference are mis-parsed structure
6142       // constructors or array references that will be fixed later when
6143       // analyzing expressions.
6144     } else if (symbol->test(Symbol::Flag::Implicit)) {
6145       Say(name,
6146           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
6147     } else {
6148       SayWithDecl(name, *symbol,
6149           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
6150     }
6151   }
6152 }
6153 
6154 bool ResolveNamesVisitor::CheckImplicitNoneExternal(
6155     const SourceName &name, const Symbol &symbol) {
6156   if (isImplicitNoneExternal() && !symbol.attrs().test(Attr::EXTERNAL) &&
6157       !symbol.attrs().test(Attr::INTRINSIC) && !symbol.HasExplicitInterface()) {
6158     Say(name,
6159         "'%s' is an external procedure without the EXTERNAL"
6160         " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
6161     return false;
6162   }
6163   return true;
6164 }
6165 
6166 // Variant of HandleProcedureName() for use while skimming the executable
6167 // part of a subprogram to catch calls to dummy procedures that are part
6168 // of the subprogram's interface, and to mark as procedures any symbols
6169 // that might otherwise have been miscategorized as objects.
6170 void ResolveNamesVisitor::NoteExecutablePartCall(
6171     Symbol::Flag flag, const parser::Call &call) {
6172   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
6173   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
6174     // Subtlety: The symbol pointers in the parse tree are not set, because
6175     // they might end up resolving elsewhere (e.g., construct entities in
6176     // SELECT TYPE).
6177     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
6178       Symbol::Flag other{flag == Symbol::Flag::Subroutine
6179               ? Symbol::Flag::Function
6180               : Symbol::Flag::Subroutine};
6181       if (!symbol->test(other)) {
6182         ConvertToProcEntity(*symbol);
6183         if (symbol->has<ProcEntityDetails>()) {
6184           symbol->set(flag);
6185           if (IsDummy(*symbol)) {
6186             symbol->attrs().set(Attr::EXTERNAL);
6187           }
6188           ApplyImplicitRules(*symbol);
6189         }
6190       }
6191     }
6192   }
6193 }
6194 
6195 // Check and set the Function or Subroutine flag on symbol; false on error.
6196 bool ResolveNamesVisitor::SetProcFlag(
6197     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
6198   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
6199     SayWithDecl(
6200         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6201     return false;
6202   } else if (symbol.test(Symbol::Flag::Subroutine) &&
6203       flag == Symbol::Flag::Function) {
6204     SayWithDecl(
6205         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
6206     return false;
6207   } else if (symbol.has<ProcEntityDetails>()) {
6208     symbol.set(flag); // in case it hasn't been set yet
6209     if (flag == Symbol::Flag::Function) {
6210       ApplyImplicitRules(symbol);
6211     }
6212     if (symbol.attrs().test(Attr::INTRINSIC)) {
6213       AcquireIntrinsicProcedureFlags(symbol);
6214     }
6215   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
6216     SayWithDecl(
6217         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
6218   } else if (symbol.attrs().test(Attr::INTRINSIC)) {
6219     AcquireIntrinsicProcedureFlags(symbol);
6220   }
6221   return true;
6222 }
6223 
6224 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
6225   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
6226   if (!currScope().IsModule()) { // C869
6227     Say(currStmtSource().value(),
6228         "%s statement may only appear in the specification part of a module"_err_en_US,
6229         EnumToString(accessAttr));
6230     return false;
6231   }
6232   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
6233   if (accessIds.empty()) {
6234     if (prevAccessStmt_) { // C869
6235       Say("The default accessibility of this module has already been declared"_err_en_US)
6236           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
6237     }
6238     prevAccessStmt_ = currStmtSource();
6239     defaultAccess_ = accessAttr;
6240   } else {
6241     for (const auto &accessId : accessIds) {
6242       std::visit(
6243           common::visitors{
6244               [=](const parser::Name &y) {
6245                 Resolve(y, SetAccess(y.source, accessAttr));
6246               },
6247               [=](const Indirection<parser::GenericSpec> &y) {
6248                 auto info{GenericSpecInfo{y.value()}};
6249                 const auto &symbolName{info.symbolName()};
6250                 if (auto *symbol{FindInScope(symbolName)}) {
6251                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
6252                 } else if (info.kind().IsName()) {
6253                   info.Resolve(&SetAccess(symbolName, accessAttr));
6254                 } else {
6255                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
6256                 }
6257               },
6258           },
6259           accessId.u);
6260     }
6261   }
6262   return false;
6263 }
6264 
6265 // Set the access specification for this symbol.
6266 Symbol &ModuleVisitor::SetAccess(
6267     const SourceName &name, Attr attr, Symbol *symbol) {
6268   if (!symbol) {
6269     symbol = &MakeSymbol(name);
6270   }
6271   Attrs &attrs{symbol->attrs()};
6272   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
6273     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
6274     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
6275     Say(name,
6276         WithIsFatal(
6277             "The accessibility of '%s' has already been specified as %s"_en_US,
6278             attr != prev),
6279         MakeOpName(name), EnumToString(prev));
6280   } else {
6281     attrs.set(attr);
6282   }
6283   return *symbol;
6284 }
6285 
6286 static bool NeedsExplicitType(const Symbol &symbol) {
6287   if (symbol.has<UnknownDetails>()) {
6288     return true;
6289   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
6290     return !details->type();
6291   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
6292     return !details->type();
6293   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
6294     return !details->interface().symbol() && !details->interface().type();
6295   } else {
6296     return false;
6297   }
6298 }
6299 
6300 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6301   const auto &[accDecls, ompDecls, compilerDirectives, useStmts, importStmts,
6302       implicitPart, decls] = x.t;
6303   auto flagRestorer{common::ScopedSet(inSpecificationPart_, true)};
6304   auto stateRestorer{
6305       common::ScopedSet(specPartState_, SpecificationPartState{})};
6306   Walk(accDecls);
6307   Walk(ompDecls);
6308   Walk(compilerDirectives);
6309   Walk(useStmts);
6310   Walk(importStmts);
6311   Walk(implicitPart);
6312   for (const auto &decl : decls) {
6313     if (const auto *spec{
6314             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6315       PreSpecificationConstruct(*spec);
6316     }
6317   }
6318   Walk(decls);
6319   FinishSpecificationPart(decls);
6320   return false;
6321 }
6322 
6323 // Initial processing on specification constructs, before visiting them.
6324 void ResolveNamesVisitor::PreSpecificationConstruct(
6325     const parser::SpecificationConstruct &spec) {
6326   std::visit(
6327       common::visitors{
6328           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6329             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6330           },
6331           [&](const Indirection<parser::InterfaceBlock> &y) {
6332             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6333                 y.value().t)};
6334             if (const auto *spec{parser::Unwrap<parser::GenericSpec>(stmt)}) {
6335               CreateGeneric(*spec);
6336             }
6337           },
6338           [&](const parser::Statement<parser::OtherSpecificationStmt> &y) {
6339             if (const auto *commonStmt{parser::Unwrap<parser::CommonStmt>(y)}) {
6340               CreateCommonBlockSymbols(*commonStmt);
6341             }
6342           },
6343           [&](const auto &) {},
6344       },
6345       spec.u);
6346 }
6347 
6348 void ResolveNamesVisitor::CreateCommonBlockSymbols(
6349     const parser::CommonStmt &commonStmt) {
6350   for (const parser::CommonStmt::Block &block : commonStmt.blocks) {
6351     const auto &[name, objects] = block.t;
6352     Symbol &commonBlock{MakeCommonBlockSymbol(name)};
6353     for (const auto &object : objects) {
6354       Symbol &obj{DeclareObjectEntity(std::get<parser::Name>(object.t))};
6355       if (auto *details{obj.detailsIf<ObjectEntityDetails>()}) {
6356         details->set_commonBlock(commonBlock);
6357         commonBlock.get<CommonBlockDetails>().add_object(obj);
6358       }
6359     }
6360   }
6361 }
6362 
6363 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6364   auto info{GenericSpecInfo{x}};
6365   const SourceName &symbolName{info.symbolName()};
6366   if (IsLogicalConstant(context(), symbolName)) {
6367     Say(symbolName,
6368         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6369     return;
6370   }
6371   GenericDetails genericDetails;
6372   if (Symbol * existing{FindInScope(symbolName)}) {
6373     if (existing->has<GenericDetails>()) {
6374       info.Resolve(existing);
6375       return; // already have generic, add to it
6376     }
6377     Symbol &ultimate{existing->GetUltimate()};
6378     if (auto *ultimateDetails{ultimate.detailsIf<GenericDetails>()}) {
6379       // convert a use-associated generic into a local generic
6380       genericDetails.CopyFrom(*ultimateDetails);
6381       AddGenericUse(genericDetails, existing->name(),
6382           existing->get<UseDetails>().symbol());
6383     } else if (ultimate.has<SubprogramDetails>() ||
6384         ultimate.has<SubprogramNameDetails>()) {
6385       genericDetails.set_specific(ultimate);
6386     } else if (ultimate.has<DerivedTypeDetails>()) {
6387       genericDetails.set_derivedType(ultimate);
6388     } else {
6389       SayAlreadyDeclared(symbolName, *existing);
6390     }
6391     EraseSymbol(*existing);
6392   }
6393   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
6394 }
6395 
6396 void ResolveNamesVisitor::FinishSpecificationPart(
6397     const std::list<parser::DeclarationConstruct> &decls) {
6398   badStmtFuncFound_ = false;
6399   CheckImports();
6400   bool inModule{currScope().kind() == Scope::Kind::Module};
6401   for (auto &pair : currScope()) {
6402     auto &symbol{*pair.second};
6403     if (NeedsExplicitType(symbol)) {
6404       ApplyImplicitRules(symbol);
6405     }
6406     if (IsDummy(symbol) && isImplicitNoneType() &&
6407         symbol.test(Symbol::Flag::Implicit) && !context().HasError(symbol)) {
6408       Say(symbol.name(),
6409           "No explicit type declared for dummy argument '%s'"_err_en_US);
6410       context().SetError(symbol);
6411     }
6412     if (symbol.has<GenericDetails>()) {
6413       CheckGenericProcedures(symbol);
6414     }
6415     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
6416         !symbol.test(Symbol::Flag::Function) &&
6417         !symbol.test(Symbol::Flag::Subroutine)) {
6418       // in a module, external proc without return type is subroutine
6419       symbol.set(
6420           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
6421     }
6422     if (!symbol.has<HostAssocDetails>()) {
6423       CheckPossibleBadForwardRef(symbol);
6424     }
6425   }
6426   currScope().InstantiateDerivedTypes();
6427   for (const auto &decl : decls) {
6428     if (const auto *statement{std::get_if<
6429             parser::Statement<common::Indirection<parser::StmtFunctionStmt>>>(
6430             &decl.u)}) {
6431       AnalyzeStmtFunctionStmt(statement->statement.value());
6432     }
6433   }
6434   // TODO: what about instantiations in BLOCK?
6435   CheckSaveStmts();
6436   CheckCommonBlocks();
6437   if (!inInterfaceBlock()) {
6438     // TODO: warn for the case where the EQUIVALENCE statement is in a
6439     // procedure declaration in an interface block
6440     CheckEquivalenceSets();
6441   }
6442 }
6443 
6444 // Analyze the bodies of statement functions now that the symbols in this
6445 // specification part have been fully declared and implicitly typed.
6446 void ResolveNamesVisitor::AnalyzeStmtFunctionStmt(
6447     const parser::StmtFunctionStmt &stmtFunc) {
6448   Symbol *symbol{std::get<parser::Name>(stmtFunc.t).symbol};
6449   if (!symbol || !symbol->has<SubprogramDetails>()) {
6450     return;
6451   }
6452   auto &details{symbol->get<SubprogramDetails>()};
6453   auto expr{AnalyzeExpr(
6454       context(), std::get<parser::Scalar<parser::Expr>>(stmtFunc.t))};
6455   if (!expr) {
6456     context().SetError(*symbol);
6457     return;
6458   }
6459   if (auto type{evaluate::DynamicType::From(*symbol)}) {
6460     auto converted{ConvertToType(*type, std::move(*expr))};
6461     if (!converted) {
6462       context().SetError(*symbol);
6463       return;
6464     }
6465     details.set_stmtFunction(std::move(*converted));
6466   } else {
6467     details.set_stmtFunction(std::move(*expr));
6468   }
6469 }
6470 
6471 void ResolveNamesVisitor::CheckImports() {
6472   auto &scope{currScope()};
6473   switch (scope.GetImportKind()) {
6474   case common::ImportKind::None:
6475     break;
6476   case common::ImportKind::All:
6477     // C8102: all entities in host must not be hidden
6478     for (const auto &pair : scope.parent()) {
6479       auto &name{pair.first};
6480       std::optional<SourceName> scopeName{scope.GetName()};
6481       if (!scopeName || name != *scopeName) {
6482         CheckImport(prevImportStmt_.value(), name);
6483       }
6484     }
6485     break;
6486   case common::ImportKind::Default:
6487   case common::ImportKind::Only:
6488     // C8102: entities named in IMPORT must not be hidden
6489     for (auto &name : scope.importNames()) {
6490       CheckImport(name, name);
6491     }
6492     break;
6493   }
6494 }
6495 
6496 void ResolveNamesVisitor::CheckImport(
6497     const SourceName &location, const SourceName &name) {
6498   if (auto *symbol{FindInScope(name)}) {
6499     Say(location, "'%s' from host is not accessible"_err_en_US, name)
6500         .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
6501             symbol->name());
6502   }
6503 }
6504 
6505 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
6506   return CheckNotInBlock("IMPLICIT") && // C1107
6507       ImplicitRulesVisitor::Pre(x);
6508 }
6509 
6510 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
6511   std::visit(common::visitors{
6512                  [&](const parser::Name &x) { ResolveName(x); },
6513                  [&](const parser::StructureComponent &x) {
6514                    ResolveStructureComponent(x);
6515                  },
6516              },
6517       x.u);
6518 }
6519 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
6520   std::visit(common::visitors{
6521                  [&](const parser::Name &x) { ResolveName(x); },
6522                  [&](const parser::StructureComponent &x) {
6523                    ResolveStructureComponent(x);
6524                  },
6525              },
6526       x.u);
6527 }
6528 
6529 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
6530   const auto &dataRef{std::get<parser::DataRef>(x.t)};
6531   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
6532   const auto &expr{std::get<parser::Expr>(x.t)};
6533   ResolveDataRef(dataRef);
6534   Walk(bounds);
6535   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
6536   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
6537     if (NameIsKnownOrIntrinsic(*name)) {
6538       return false;
6539     }
6540   }
6541   Walk(expr);
6542   return false;
6543 }
6544 void ResolveNamesVisitor::Post(const parser::Designator &x) {
6545   ResolveDesignator(x);
6546 }
6547 
6548 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
6549   ResolveStructureComponent(x.v.thing);
6550 }
6551 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
6552   DeclTypeSpecVisitor::Post(x);
6553   ConstructVisitor::Post(x);
6554 }
6555 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
6556   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
6557   if (HandleStmtFunction(x)) {
6558     return false;
6559   } else {
6560     // This is an array element assignment: resolve names of indices
6561     const auto &names{std::get<std::list<parser::Name>>(x.t)};
6562     for (auto &name : names) {
6563       ResolveName(name);
6564     }
6565     return true;
6566   }
6567 }
6568 
6569 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
6570   const parser::Name &name{x.v};
6571   if (FindSymbol(name)) {
6572     // OK
6573   } else if (IsLogicalConstant(context(), name.source)) {
6574     Say(name,
6575         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6576   } else {
6577     // Resolved later in expression semantics
6578     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
6579   }
6580   return false;
6581 }
6582 
6583 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
6584   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6585     ConvertToObjectEntity(DEREF(name->symbol));
6586   }
6587 }
6588 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
6589   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6590     ConvertToObjectEntity(DEREF(name->symbol));
6591   }
6592 }
6593 
6594 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
6595   if (std::holds_alternative<common::Indirection<parser::CompilerDirective>>(
6596           x.u)) {
6597     // TODO: global directives
6598     return true;
6599   }
6600   auto root{ProgramTree::Build(x)};
6601   SetScope(context().globalScope());
6602   ResolveSpecificationParts(root);
6603   FinishSpecificationParts(root);
6604   inExecutionPart_ = true;
6605   ResolveExecutionParts(root);
6606   inExecutionPart_ = false;
6607   ResolveAccParts(context(), x);
6608   ResolveOmpParts(context(), x);
6609   return false;
6610 }
6611 
6612 // References to procedures need to record that their symbols are known
6613 // to be procedures, so that they don't get converted to objects by default.
6614 class ExecutionPartSkimmer {
6615 public:
6616   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
6617       : resolver_{resolver} {}
6618 
6619   void Walk(const parser::ExecutionPart *exec) {
6620     if (exec) {
6621       parser::Walk(*exec, *this);
6622     }
6623   }
6624 
6625   template <typename A> bool Pre(const A &) { return true; }
6626   template <typename A> void Post(const A &) {}
6627   void Post(const parser::FunctionReference &fr) {
6628     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
6629   }
6630   void Post(const parser::CallStmt &cs) {
6631     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
6632   }
6633 
6634 private:
6635   ResolveNamesVisitor &resolver_;
6636 };
6637 
6638 // Build the scope tree and resolve names in the specification parts of this
6639 // node and its children
6640 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
6641   if (node.isSpecificationPartResolved()) {
6642     return; // been here already
6643   }
6644   node.set_isSpecificationPartResolved();
6645   if (!BeginScopeForNode(node)) {
6646     return; // an error prevented scope from being created
6647   }
6648   Scope &scope{currScope()};
6649   node.set_scope(scope);
6650   AddSubpNames(node);
6651   std::visit(
6652       [&](const auto *x) {
6653         if (x) {
6654           Walk(*x);
6655         }
6656       },
6657       node.stmt());
6658   Walk(node.spec());
6659   // If this is a function, convert result to an object. This is to prevent the
6660   // result from being converted later to a function symbol if it is called
6661   // inside the function.
6662   // If the result is function pointer, then ConvertToObjectEntity will not
6663   // convert the result to an object, and calling the symbol inside the function
6664   // will result in calls to the result pointer.
6665   // A function cannot be called recursively if RESULT was not used to define a
6666   // distinct result name (15.6.2.2 point 4.).
6667   if (Symbol * symbol{scope.symbol()}) {
6668     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
6669       if (details->isFunction()) {
6670         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
6671       }
6672     }
6673   }
6674   if (node.IsModule()) {
6675     ApplyDefaultAccess();
6676   }
6677   for (auto &child : node.children()) {
6678     ResolveSpecificationParts(child);
6679   }
6680   ExecutionPartSkimmer{*this}.Walk(node.exec());
6681   PopScope();
6682   // Ensure that every object entity has a type.
6683   for (auto &pair : *node.scope()) {
6684     ApplyImplicitRules(*pair.second);
6685   }
6686 }
6687 
6688 // Add SubprogramNameDetails symbols for module and internal subprograms
6689 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
6690   auto kind{
6691       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
6692   for (auto &child : node.children()) {
6693     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
6694     symbol.set(child.GetSubpFlag());
6695   }
6696 }
6697 
6698 // Push a new scope for this node or return false on error.
6699 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
6700   switch (node.GetKind()) {
6701     SWITCH_COVERS_ALL_CASES
6702   case ProgramTree::Kind::Program:
6703     PushScope(Scope::Kind::MainProgram,
6704         &MakeSymbol(node.name(), MainProgramDetails{}));
6705     return true;
6706   case ProgramTree::Kind::Function:
6707   case ProgramTree::Kind::Subroutine:
6708     return BeginSubprogram(
6709         node.name(), node.GetSubpFlag(), node.HasModulePrefix());
6710   case ProgramTree::Kind::MpSubprogram:
6711     return BeginMpSubprogram(node.name());
6712   case ProgramTree::Kind::Module:
6713     BeginModule(node.name(), false);
6714     return true;
6715   case ProgramTree::Kind::Submodule:
6716     return BeginSubmodule(node.name(), node.GetParentId());
6717   case ProgramTree::Kind::BlockData:
6718     PushBlockDataScope(node.name());
6719     return true;
6720   }
6721 }
6722 
6723 // Some analyses and checks, such as the processing of initializers of
6724 // pointers, are deferred until all of the pertinent specification parts
6725 // have been visited.  This deferred processing enables the use of forward
6726 // references in these circumstances.
6727 class DeferredCheckVisitor {
6728 public:
6729   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
6730       : resolver_{resolver} {}
6731 
6732   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
6733 
6734   template <typename A> bool Pre(const A &) { return true; }
6735   template <typename A> void Post(const A &) {}
6736 
6737   void Post(const parser::DerivedTypeStmt &x) {
6738     const auto &name{std::get<parser::Name>(x.t)};
6739     if (Symbol * symbol{name.symbol}) {
6740       if (Scope * scope{symbol->scope()}) {
6741         if (scope->IsDerivedType()) {
6742           resolver_.PushScope(*scope);
6743           pushedScope_ = true;
6744         }
6745       }
6746     }
6747   }
6748   void Post(const parser::EndTypeStmt &) {
6749     if (pushedScope_) {
6750       resolver_.PopScope();
6751       pushedScope_ = false;
6752     }
6753   }
6754 
6755   void Post(const parser::ProcInterface &pi) {
6756     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
6757       resolver_.CheckExplicitInterface(*name);
6758     }
6759   }
6760   bool Pre(const parser::EntityDecl &decl) {
6761     Init(std::get<parser::Name>(decl.t),
6762         std::get<std::optional<parser::Initialization>>(decl.t));
6763     return false;
6764   }
6765   bool Pre(const parser::ComponentDecl &decl) {
6766     Init(std::get<parser::Name>(decl.t),
6767         std::get<std::optional<parser::Initialization>>(decl.t));
6768     return false;
6769   }
6770   bool Pre(const parser::ProcDecl &decl) {
6771     if (const auto &init{
6772             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
6773       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
6774     }
6775     return false;
6776   }
6777   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
6778     resolver_.CheckExplicitInterface(tbps.interfaceName);
6779   }
6780   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
6781     if (pushedScope_) {
6782       resolver_.CheckBindings(tbps);
6783     }
6784   }
6785 
6786 private:
6787   void Init(const parser::Name &name,
6788       const std::optional<parser::Initialization> &init) {
6789     if (init) {
6790       if (const auto *target{
6791               std::get_if<parser::InitialDataTarget>(&init->u)}) {
6792         resolver_.PointerInitialization(name, *target);
6793       }
6794     }
6795   }
6796 
6797   ResolveNamesVisitor &resolver_;
6798   bool pushedScope_{false};
6799 };
6800 
6801 // Perform checks and completions that need to happen after all of
6802 // the specification parts but before any of the execution parts.
6803 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
6804   if (!node.scope()) {
6805     return; // error occurred creating scope
6806   }
6807   SetScope(*node.scope());
6808   // The initializers of pointers, the default initializers of pointer
6809   // components, and non-deferred type-bound procedure bindings have not
6810   // yet been traversed.
6811   // We do that now, when any (formerly) forward references that appear
6812   // in those initializers will resolve to the right symbols without
6813   // incurring spurious errors with IMPLICIT NONE.
6814   DeferredCheckVisitor{*this}.Walk(node.spec());
6815   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
6816   for (Scope &childScope : currScope().children()) {
6817     if (childScope.IsParameterizedDerivedTypeInstantiation()) {
6818       FinishDerivedTypeInstantiation(childScope);
6819     }
6820   }
6821   for (const auto &child : node.children()) {
6822     FinishSpecificationParts(child);
6823   }
6824 }
6825 
6826 // Duplicate and fold component object pointer default initializer designators
6827 // using the actual type parameter values of each particular instantiation.
6828 // Validation is done later in declaration checking.
6829 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
6830   CHECK(scope.IsDerivedType() && !scope.symbol());
6831   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
6832     spec->Instantiate(currScope());
6833     const Symbol &origTypeSymbol{spec->typeSymbol()};
6834     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
6835       CHECK(origTypeScope->IsDerivedType() &&
6836           origTypeScope->symbol() == &origTypeSymbol);
6837       auto &foldingContext{GetFoldingContext()};
6838       auto restorer{foldingContext.WithPDTInstance(*spec)};
6839       for (auto &pair : scope) {
6840         Symbol &comp{*pair.second};
6841         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
6842         if (IsPointer(comp)) {
6843           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
6844             auto origDetails{origComp.get<ObjectEntityDetails>()};
6845             if (const MaybeExpr & init{origDetails.init()}) {
6846               SomeExpr newInit{*init};
6847               MaybeExpr folded{
6848                   evaluate::Fold(foldingContext, std::move(newInit))};
6849               details->set_init(std::move(folded));
6850             }
6851           }
6852         }
6853       }
6854     }
6855   }
6856 }
6857 
6858 // Resolve names in the execution part of this node and its children
6859 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
6860   if (!node.scope()) {
6861     return; // error occurred creating scope
6862   }
6863   SetScope(*node.scope());
6864   if (const auto *exec{node.exec()}) {
6865     Walk(*exec);
6866   }
6867   PopScope(); // converts unclassified entities into objects
6868   for (const auto &child : node.children()) {
6869     ResolveExecutionParts(child);
6870   }
6871 }
6872 
6873 void ResolveNamesVisitor::Post(const parser::Program &) {
6874   // ensure that all temps were deallocated
6875   CHECK(!attrs_);
6876   CHECK(!GetDeclTypeSpec());
6877 }
6878 
6879 // A singleton instance of the scope -> IMPLICIT rules mapping is
6880 // shared by all instances of ResolveNamesVisitor and accessed by this
6881 // pointer when the visitors (other than the top-level original) are
6882 // constructed.
6883 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
6884 
6885 bool ResolveNames(SemanticsContext &context, const parser::Program &program) {
6886   ImplicitRulesMap implicitRulesMap;
6887   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
6888   ResolveNamesVisitor{context, implicitRulesMap}.Walk(program);
6889   return !context.AnyFatalError();
6890 }
6891 
6892 // Processes a module (but not internal) function when it is referenced
6893 // in a specification expression in a sibling procedure.
6894 void ResolveSpecificationParts(
6895     SemanticsContext &context, const Symbol &subprogram) {
6896   auto originalLocation{context.location()};
6897   ResolveNamesVisitor visitor{context, DEREF(sharedImplicitRulesMap)};
6898   ProgramTree &node{subprogram.get<SubprogramNameDetails>().node()};
6899   const Scope &moduleScope{subprogram.owner()};
6900   visitor.SetScope(const_cast<Scope &>(moduleScope));
6901   visitor.ResolveSpecificationParts(node);
6902   context.set_location(std::move(originalLocation));
6903 }
6904 
6905 } // namespace Fortran::semantics
6906