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 "check-omp-structure.h"
11 #include "mod-file.h"
12 #include "pointer-assignment.h"
13 #include "program-tree.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 identifiers starting with ch. May be null.
72   const DeclTypeSpec *GetType(char ch) const;
73   // Record the implicit type for the range of characters [fromLetter,
74   // toLetter].
75   void SetTypeMapping(const DeclTypeSpec &type, parser::Location fromLetter,
76       parser::Location toLetter);
77 
78 private:
79   static char Incr(char ch);
80 
81   ImplicitRules *parent_;
82   SemanticsContext &context_;
83   bool inheritFromParent_{false}; // look in parent if not specified here
84   bool isImplicitNoneType_{false};
85   bool isImplicitNoneExternal_{false};
86   // map_ contains the mapping between letters and types that were defined
87   // by the IMPLICIT statements of the related scope. It does not contain
88   // the default Fortran mappings nor the mapping defined in parents.
89   std::map<char, common::Reference<const DeclTypeSpec>> map_;
90 
91   friend llvm::raw_ostream &operator<<(
92       llvm::raw_ostream &, const ImplicitRules &);
93   friend void ShowImplicitRule(
94       llvm::raw_ostream &, const ImplicitRules &, char);
95 };
96 
97 // scope -> implicit rules for that scope
98 using ImplicitRulesMap = std::map<const Scope *, ImplicitRules>;
99 
100 // Track statement source locations and save messages.
101 class MessageHandler {
102 public:
103   MessageHandler() { DIE("MessageHandler: default-constructed"); }
104   explicit MessageHandler(SemanticsContext &c) : context_{&c} {}
105   Messages &messages() { return context_->messages(); };
106   const std::optional<SourceName> &currStmtSource() {
107     return context_->location();
108   }
109   void set_currStmtSource(const std::optional<SourceName> &source) {
110     context_->set_location(source);
111   }
112 
113   // Emit a message associated with the current statement source.
114   Message &Say(MessageFixedText &&);
115   Message &Say(MessageFormattedText &&);
116   // Emit a message about a SourceName
117   Message &Say(const SourceName &, MessageFixedText &&);
118   // Emit a formatted message associated with a source location.
119   template <typename... A>
120   Message &Say(const SourceName &source, MessageFixedText &&msg, A &&... args) {
121     return context_->Say(source, std::move(msg), std::forward<A>(args)...);
122   }
123 
124 private:
125   SemanticsContext *context_;
126 };
127 
128 // Inheritance graph for the parse tree visitation classes that follow:
129 //   BaseVisitor
130 //   + AttrsVisitor
131 //   | + DeclTypeSpecVisitor
132 //   |   + ImplicitRulesVisitor
133 //   |     + ScopeHandler -----------+--+
134 //   |       + ModuleVisitor ========|==+
135 //   |       + InterfaceVisitor      |  |
136 //   |       +-+ SubprogramVisitor ==|==+
137 //   + ArraySpecVisitor              |  |
138 //     + DeclarationVisitor <--------+  |
139 //       + ConstructVisitor             |
140 //         + ResolveNamesVisitor <------+
141 
142 class BaseVisitor {
143 public:
144   BaseVisitor() { DIE("BaseVisitor: default-constructed"); }
145   BaseVisitor(
146       SemanticsContext &c, ResolveNamesVisitor &v, ImplicitRulesMap &rules)
147       : implicitRulesMap_{&rules}, this_{&v}, context_{&c}, messageHandler_{c} {
148   }
149   template <typename T> void Walk(const T &);
150 
151   MessageHandler &messageHandler() { return messageHandler_; }
152   const std::optional<SourceName> &currStmtSource() {
153     return context_->location();
154   }
155   SemanticsContext &context() const { return *context_; }
156   evaluate::FoldingContext &GetFoldingContext() const {
157     return context_->foldingContext();
158   }
159 
160   // Make a placeholder symbol for a Name that otherwise wouldn't have one.
161   // It is not in any scope and always has MiscDetails.
162   void MakePlaceholder(const parser::Name &, MiscDetails::Kind);
163 
164   template <typename T> common::IfNoLvalue<T, T> FoldExpr(T &&expr) {
165     return evaluate::Fold(GetFoldingContext(), std::move(expr));
166   }
167 
168   template <typename T> MaybeExpr EvaluateExpr(const T &expr) {
169     return FoldExpr(AnalyzeExpr(*context_, expr));
170   }
171 
172   template <typename T>
173   MaybeExpr EvaluateConvertedExpr(
174       const Symbol &symbol, const T &expr, parser::CharBlock source) {
175     if (context().HasError(symbol)) {
176       return std::nullopt;
177     }
178     auto maybeExpr{AnalyzeExpr(*context_, expr)};
179     if (!maybeExpr) {
180       return std::nullopt;
181     }
182     auto exprType{maybeExpr->GetType()};
183     auto converted{evaluate::ConvertToType(symbol, std::move(*maybeExpr))};
184     if (!converted) {
185       if (exprType) {
186         Say(source,
187             "Initialization expression could not be converted to declared type of '%s' from %s"_err_en_US,
188             symbol.name(), exprType->AsFortran());
189       } else {
190         Say(source,
191             "Initialization expression could not be converted to declared type of '%s'"_err_en_US,
192             symbol.name());
193       }
194       return std::nullopt;
195     }
196     return FoldExpr(std::move(*converted));
197   }
198 
199   template <typename T> MaybeIntExpr EvaluateIntExpr(const T &expr) {
200     if (MaybeExpr maybeExpr{EvaluateExpr(expr)}) {
201       if (auto *intExpr{evaluate::UnwrapExpr<SomeIntExpr>(*maybeExpr)}) {
202         return std::move(*intExpr);
203       }
204     }
205     return std::nullopt;
206   }
207 
208   template <typename T>
209   MaybeSubscriptIntExpr EvaluateSubscriptIntExpr(const T &expr) {
210     if (MaybeIntExpr maybeIntExpr{EvaluateIntExpr(expr)}) {
211       return FoldExpr(evaluate::ConvertToType<evaluate::SubscriptInteger>(
212           std::move(*maybeIntExpr)));
213     } else {
214       return std::nullopt;
215     }
216   }
217 
218   template <typename... A> Message &Say(A &&... args) {
219     return messageHandler_.Say(std::forward<A>(args)...);
220   }
221   template <typename... A>
222   Message &Say(
223       const parser::Name &name, MessageFixedText &&text, const A &... args) {
224     return messageHandler_.Say(name.source, std::move(text), args...);
225   }
226 
227 protected:
228   ImplicitRulesMap *implicitRulesMap_{nullptr};
229 
230 private:
231   ResolveNamesVisitor *this_;
232   SemanticsContext *context_;
233   MessageHandler messageHandler_;
234 };
235 
236 // Provide Post methods to collect attributes into a member variable.
237 class AttrsVisitor : public virtual BaseVisitor {
238 public:
239   bool BeginAttrs(); // always returns true
240   Attrs GetAttrs();
241   Attrs EndAttrs();
242   bool SetPassNameOn(Symbol &);
243   bool SetBindNameOn(Symbol &);
244   void Post(const parser::LanguageBindingSpec &);
245   bool Pre(const parser::IntentSpec &);
246   bool Pre(const parser::Pass &);
247 
248   bool CheckAndSet(Attr);
249 
250 // Simple case: encountering CLASSNAME causes ATTRNAME to be set.
251 #define HANDLE_ATTR_CLASS(CLASSNAME, ATTRNAME) \
252   bool Pre(const parser::CLASSNAME &) { \
253     CheckAndSet(Attr::ATTRNAME); \
254     return false; \
255   }
256   HANDLE_ATTR_CLASS(PrefixSpec::Elemental, ELEMENTAL)
257   HANDLE_ATTR_CLASS(PrefixSpec::Impure, IMPURE)
258   HANDLE_ATTR_CLASS(PrefixSpec::Module, MODULE)
259   HANDLE_ATTR_CLASS(PrefixSpec::Non_Recursive, NON_RECURSIVE)
260   HANDLE_ATTR_CLASS(PrefixSpec::Pure, PURE)
261   HANDLE_ATTR_CLASS(PrefixSpec::Recursive, RECURSIVE)
262   HANDLE_ATTR_CLASS(TypeAttrSpec::BindC, BIND_C)
263   HANDLE_ATTR_CLASS(BindAttr::Deferred, DEFERRED)
264   HANDLE_ATTR_CLASS(BindAttr::Non_Overridable, NON_OVERRIDABLE)
265   HANDLE_ATTR_CLASS(Abstract, ABSTRACT)
266   HANDLE_ATTR_CLASS(Allocatable, ALLOCATABLE)
267   HANDLE_ATTR_CLASS(Asynchronous, ASYNCHRONOUS)
268   HANDLE_ATTR_CLASS(Contiguous, CONTIGUOUS)
269   HANDLE_ATTR_CLASS(External, EXTERNAL)
270   HANDLE_ATTR_CLASS(Intrinsic, INTRINSIC)
271   HANDLE_ATTR_CLASS(NoPass, NOPASS)
272   HANDLE_ATTR_CLASS(Optional, OPTIONAL)
273   HANDLE_ATTR_CLASS(Parameter, PARAMETER)
274   HANDLE_ATTR_CLASS(Pointer, POINTER)
275   HANDLE_ATTR_CLASS(Protected, PROTECTED)
276   HANDLE_ATTR_CLASS(Save, SAVE)
277   HANDLE_ATTR_CLASS(Target, TARGET)
278   HANDLE_ATTR_CLASS(Value, VALUE)
279   HANDLE_ATTR_CLASS(Volatile, VOLATILE)
280 #undef HANDLE_ATTR_CLASS
281 
282 protected:
283   std::optional<Attrs> attrs_;
284 
285   Attr AccessSpecToAttr(const parser::AccessSpec &x) {
286     switch (x.v) {
287     case parser::AccessSpec::Kind::Public:
288       return Attr::PUBLIC;
289     case parser::AccessSpec::Kind::Private:
290       return Attr::PRIVATE;
291     }
292     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
293   }
294   Attr IntentSpecToAttr(const parser::IntentSpec &x) {
295     switch (x.v) {
296     case parser::IntentSpec::Intent::In:
297       return Attr::INTENT_IN;
298     case parser::IntentSpec::Intent::Out:
299       return Attr::INTENT_OUT;
300     case parser::IntentSpec::Intent::InOut:
301       return Attr::INTENT_INOUT;
302     }
303     llvm_unreachable("Switch covers all cases"); // suppress g++ warning
304   }
305 
306 private:
307   bool IsDuplicateAttr(Attr);
308   bool HaveAttrConflict(Attr, Attr, Attr);
309   bool IsConflictingAttr(Attr);
310 
311   MaybeExpr bindName_; // from BIND(C, NAME="...")
312   std::optional<SourceName> passName_; // from PASS(...)
313 };
314 
315 // Find and create types from declaration-type-spec nodes.
316 class DeclTypeSpecVisitor : public AttrsVisitor {
317 public:
318   using AttrsVisitor::Post;
319   using AttrsVisitor::Pre;
320   void Post(const parser::IntrinsicTypeSpec::DoublePrecision &);
321   void Post(const parser::IntrinsicTypeSpec::DoubleComplex &);
322   void Post(const parser::DeclarationTypeSpec::ClassStar &);
323   void Post(const parser::DeclarationTypeSpec::TypeStar &);
324   bool Pre(const parser::TypeGuardStmt &);
325   void Post(const parser::TypeGuardStmt &);
326   void Post(const parser::TypeSpec &);
327 
328 protected:
329   struct State {
330     bool expectDeclTypeSpec{false}; // should see decl-type-spec only when true
331     const DeclTypeSpec *declTypeSpec{nullptr};
332     struct {
333       DerivedTypeSpec *type{nullptr};
334       DeclTypeSpec::Category category{DeclTypeSpec::TypeDerived};
335     } derived;
336     bool allowForwardReferenceToDerivedType{false};
337   };
338 
339   bool allowForwardReferenceToDerivedType() const {
340     return state_.allowForwardReferenceToDerivedType;
341   }
342   void set_allowForwardReferenceToDerivedType(bool yes) {
343     state_.allowForwardReferenceToDerivedType = yes;
344   }
345 
346   // Walk the parse tree of a type spec and return the DeclTypeSpec for it.
347   template <typename T>
348   const DeclTypeSpec *ProcessTypeSpec(const T &x, bool allowForward = false) {
349     auto restorer{common::ScopedSet(state_, State{})};
350     set_allowForwardReferenceToDerivedType(allowForward);
351     BeginDeclTypeSpec();
352     Walk(x);
353     const auto *type{GetDeclTypeSpec()};
354     EndDeclTypeSpec();
355     return type;
356   }
357 
358   const DeclTypeSpec *GetDeclTypeSpec();
359   void BeginDeclTypeSpec();
360   void EndDeclTypeSpec();
361   void SetDeclTypeSpec(const DeclTypeSpec &);
362   void SetDeclTypeSpecCategory(DeclTypeSpec::Category);
363   DeclTypeSpec::Category GetDeclTypeSpecCategory() const {
364     return state_.derived.category;
365   }
366   KindExpr GetKindParamExpr(
367       TypeCategory, const std::optional<parser::KindSelector> &);
368   void CheckForAbstractType(const Symbol &typeSymbol);
369 
370 private:
371   State state_;
372 
373   void MakeNumericType(TypeCategory, int kind);
374 };
375 
376 // Visit ImplicitStmt and related parse tree nodes and updates implicit rules.
377 class ImplicitRulesVisitor : public DeclTypeSpecVisitor {
378 public:
379   using DeclTypeSpecVisitor::Post;
380   using DeclTypeSpecVisitor::Pre;
381   using ImplicitNoneNameSpec = parser::ImplicitStmt::ImplicitNoneNameSpec;
382 
383   void Post(const parser::ParameterStmt &);
384   bool Pre(const parser::ImplicitStmt &);
385   bool Pre(const parser::LetterSpec &);
386   bool Pre(const parser::ImplicitSpec &);
387   void Post(const parser::ImplicitSpec &);
388 
389   ImplicitRules &implicitRules() { return *implicitRules_; }
390   const ImplicitRules &implicitRules() const { return *implicitRules_; }
391   bool isImplicitNoneType() const {
392     return implicitRules().isImplicitNoneType();
393   }
394   bool isImplicitNoneExternal() const {
395     return implicitRules().isImplicitNoneExternal();
396   }
397 
398 protected:
399   void BeginScope(const Scope &);
400   void SetScope(const Scope &);
401 
402 private:
403   // implicit rules in effect for current scope
404   ImplicitRules *implicitRules_{nullptr};
405   std::optional<SourceName> prevImplicit_;
406   std::optional<SourceName> prevImplicitNone_;
407   std::optional<SourceName> prevImplicitNoneType_;
408   std::optional<SourceName> prevParameterStmt_;
409 
410   bool HandleImplicitNone(const std::list<ImplicitNoneNameSpec> &nameSpecs);
411 };
412 
413 // Track array specifications. They can occur in AttrSpec, EntityDecl,
414 // ObjectDecl, DimensionStmt, CommonBlockObject, or BasedPointerStmt.
415 // 1. INTEGER, DIMENSION(10) :: x
416 // 2. INTEGER :: x(10)
417 // 3. ALLOCATABLE :: x(:)
418 // 4. DIMENSION :: x(10)
419 // 5. COMMON x(10)
420 // 6. BasedPointerStmt
421 class ArraySpecVisitor : public virtual BaseVisitor {
422 public:
423   void Post(const parser::ArraySpec &);
424   void Post(const parser::ComponentArraySpec &);
425   void Post(const parser::CoarraySpec &);
426   void Post(const parser::AttrSpec &) { PostAttrSpec(); }
427   void Post(const parser::ComponentAttrSpec &) { PostAttrSpec(); }
428 
429 protected:
430   const ArraySpec &arraySpec();
431   const ArraySpec &coarraySpec();
432   void BeginArraySpec();
433   void EndArraySpec();
434   void ClearArraySpec() { arraySpec_.clear(); }
435   void ClearCoarraySpec() { coarraySpec_.clear(); }
436 
437 private:
438   // arraySpec_/coarraySpec_ are populated from any ArraySpec/CoarraySpec
439   ArraySpec arraySpec_;
440   ArraySpec coarraySpec_;
441   // When an ArraySpec is under an AttrSpec or ComponentAttrSpec, it is moved
442   // into attrArraySpec_
443   ArraySpec attrArraySpec_;
444   ArraySpec attrCoarraySpec_;
445 
446   void PostAttrSpec();
447 };
448 
449 // Manage a stack of Scopes
450 class ScopeHandler : public ImplicitRulesVisitor {
451 public:
452   using ImplicitRulesVisitor::Post;
453   using ImplicitRulesVisitor::Pre;
454 
455   Scope &currScope() { return DEREF(currScope_); }
456   // The enclosing scope, skipping blocks and derived types.
457   // TODO: Will return the scope of a FORALL or implied DO loop; is this ok?
458   // If not, should call FindProgramUnitContaining() instead.
459   Scope &InclusiveScope();
460   // The enclosing scope, skipping derived types.
461   Scope &NonDerivedTypeScope();
462 
463   // Create a new scope and push it on the scope stack.
464   void PushScope(Scope::Kind kind, Symbol *symbol);
465   void PushScope(Scope &scope);
466   void PopScope();
467   void SetScope(Scope &);
468 
469   template <typename T> bool Pre(const parser::Statement<T> &x) {
470     messageHandler().set_currStmtSource(x.source);
471     currScope_->AddSourceRange(x.source);
472     return true;
473   }
474   template <typename T> void Post(const parser::Statement<T> &) {
475     messageHandler().set_currStmtSource(std::nullopt);
476   }
477 
478   // Special messages: already declared; referencing symbol's declaration;
479   // about a type; two names & locations
480   void SayAlreadyDeclared(const parser::Name &, Symbol &);
481   void SayAlreadyDeclared(const SourceName &, Symbol &);
482   void SayAlreadyDeclared(const SourceName &, const SourceName &);
483   void SayWithReason(
484       const parser::Name &, Symbol &, MessageFixedText &&, MessageFixedText &&);
485   void SayWithDecl(const parser::Name &, Symbol &, MessageFixedText &&);
486   void SayLocalMustBeVariable(const parser::Name &, Symbol &);
487   void SayDerivedType(const SourceName &, MessageFixedText &&, const Scope &);
488   void Say2(const SourceName &, MessageFixedText &&, const SourceName &,
489       MessageFixedText &&);
490   void Say2(
491       const SourceName &, MessageFixedText &&, Symbol &, MessageFixedText &&);
492   void Say2(
493       const parser::Name &, MessageFixedText &&, Symbol &, MessageFixedText &&);
494 
495   // Search for symbol by name in current, parent derived type, and
496   // containing scopes
497   Symbol *FindSymbol(const parser::Name &);
498   Symbol *FindSymbol(const Scope &, const parser::Name &);
499   // Search for name only in scope, not in enclosing scopes.
500   Symbol *FindInScope(const Scope &, const parser::Name &);
501   Symbol *FindInScope(const Scope &, const SourceName &);
502   // Search for name in a derived type scope and its parents.
503   Symbol *FindInTypeOrParents(const Scope &, const parser::Name &);
504   Symbol *FindInTypeOrParents(const parser::Name &);
505   void EraseSymbol(const parser::Name &);
506   void EraseSymbol(const Symbol &symbol) { currScope().erase(symbol.name()); }
507   // Make a new symbol with the name and attrs of an existing one
508   Symbol &CopySymbol(const SourceName &, const Symbol &);
509 
510   // Make symbols in the current or named scope
511   Symbol &MakeSymbol(Scope &, const SourceName &, Attrs);
512   Symbol &MakeSymbol(const SourceName &, Attrs = Attrs{});
513   Symbol &MakeSymbol(const parser::Name &, Attrs = Attrs{});
514 
515   template <typename D>
516   common::IfNoLvalue<Symbol &, D> MakeSymbol(
517       const parser::Name &name, D &&details) {
518     return MakeSymbol(name, Attrs{}, std::move(details));
519   }
520 
521   template <typename D>
522   common::IfNoLvalue<Symbol &, D> MakeSymbol(
523       const parser::Name &name, const Attrs &attrs, D &&details) {
524     return Resolve(name, MakeSymbol(name.source, attrs, std::move(details)));
525   }
526 
527   template <typename D>
528   common::IfNoLvalue<Symbol &, D> MakeSymbol(
529       const SourceName &name, const Attrs &attrs, D &&details) {
530     // Note: don't use FindSymbol here. If this is a derived type scope,
531     // we want to detect whether the name is already declared as a component.
532     auto *symbol{FindInScope(currScope(), name)};
533     if (!symbol) {
534       symbol = &MakeSymbol(name, attrs);
535       symbol->set_details(std::move(details));
536       return *symbol;
537     }
538     if constexpr (std::is_same_v<DerivedTypeDetails, D>) {
539       if (auto *d{symbol->detailsIf<GenericDetails>()}) {
540         if (!d->specific()) {
541           // derived type with same name as a generic
542           auto *derivedType{d->derivedType()};
543           if (!derivedType) {
544             derivedType =
545                 &currScope().MakeSymbol(name, attrs, std::move(details));
546             d->set_derivedType(*derivedType);
547           } else {
548             SayAlreadyDeclared(name, *derivedType);
549           }
550           return *derivedType;
551         }
552       }
553     }
554     if (symbol->CanReplaceDetails(details)) {
555       // update the existing symbol
556       symbol->attrs() |= attrs;
557       symbol->set_details(std::move(details));
558       return *symbol;
559     } else if constexpr (std::is_same_v<UnknownDetails, D>) {
560       symbol->attrs() |= attrs;
561       return *symbol;
562     } else {
563       SayAlreadyDeclared(name, *symbol);
564       // replace the old symbol with a new one with correct details
565       EraseSymbol(*symbol);
566       auto &result{MakeSymbol(name, attrs, std::move(details))};
567       context().SetError(result);
568       return result;
569     }
570   }
571 
572   void MakeExternal(Symbol &);
573 
574 protected:
575   // Apply the implicit type rules to this symbol.
576   void ApplyImplicitRules(Symbol &);
577   const DeclTypeSpec *GetImplicitType(Symbol &);
578   bool ConvertToObjectEntity(Symbol &);
579   bool ConvertToProcEntity(Symbol &);
580 
581   const DeclTypeSpec &MakeNumericType(
582       TypeCategory, const std::optional<parser::KindSelector> &);
583   const DeclTypeSpec &MakeLogicalType(
584       const std::optional<parser::KindSelector> &);
585 
586 private:
587   Scope *currScope_{nullptr};
588 };
589 
590 class ModuleVisitor : public virtual ScopeHandler {
591 public:
592   bool Pre(const parser::AccessStmt &);
593   bool Pre(const parser::Only &);
594   bool Pre(const parser::Rename::Names &);
595   bool Pre(const parser::Rename::Operators &);
596   bool Pre(const parser::UseStmt &);
597   void Post(const parser::UseStmt &);
598 
599   void BeginModule(const parser::Name &, bool isSubmodule);
600   bool BeginSubmodule(const parser::Name &, const parser::ParentIdentifier &);
601   void ApplyDefaultAccess();
602 
603 private:
604   // The default access spec for this module.
605   Attr defaultAccess_{Attr::PUBLIC};
606   // The location of the last AccessStmt without access-ids, if any.
607   std::optional<SourceName> prevAccessStmt_;
608   // The scope of the module during a UseStmt
609   const Scope *useModuleScope_{nullptr};
610 
611   Symbol &SetAccess(const SourceName &, Attr attr, Symbol * = nullptr);
612   // A rename in a USE statement: local => use
613   struct SymbolRename {
614     Symbol *local{nullptr};
615     Symbol *use{nullptr};
616   };
617   // Record a use from useModuleScope_ of use Name/Symbol as local Name/Symbol
618   SymbolRename AddUse(const SourceName &localName, const SourceName &useName);
619   SymbolRename AddUse(const SourceName &, const SourceName &, Symbol *);
620   void AddUse(const SourceName &, Symbol &localSymbol, const Symbol &useSymbol);
621   void AddUse(const GenericSpecInfo &);
622   Scope *FindModule(const parser::Name &, Scope *ancestor = nullptr);
623 };
624 
625 class InterfaceVisitor : public virtual ScopeHandler {
626 public:
627   bool Pre(const parser::InterfaceStmt &);
628   void Post(const parser::InterfaceStmt &);
629   void Post(const parser::EndInterfaceStmt &);
630   bool Pre(const parser::GenericSpec &);
631   bool Pre(const parser::ProcedureStmt &);
632   bool Pre(const parser::GenericStmt &);
633   void Post(const parser::GenericStmt &);
634 
635   bool inInterfaceBlock() const;
636   bool isGeneric() const;
637   bool isAbstract() const;
638 
639 protected:
640   GenericDetails &GetGenericDetails();
641   // Add to generic the symbol for the subprogram with the same name
642   void CheckGenericProcedures(Symbol &);
643 
644 private:
645   // A new GenericInfo is pushed for each interface block and generic stmt
646   struct GenericInfo {
647     GenericInfo(bool isInterface, bool isAbstract = false)
648         : isInterface{isInterface}, isAbstract{isAbstract} {}
649     bool isInterface; // in interface block
650     bool isAbstract; // in abstract interface block
651     Symbol *symbol{nullptr}; // the generic symbol being defined
652   };
653   std::stack<GenericInfo> genericInfo_;
654   const GenericInfo &GetGenericInfo() const { return genericInfo_.top(); }
655   void SetGenericSymbol(Symbol &symbol) { genericInfo_.top().symbol = &symbol; }
656 
657   using ProcedureKind = parser::ProcedureStmt::Kind;
658   // mapping of generic to its specific proc names and kinds
659   std::multimap<Symbol *, std::pair<const parser::Name *, ProcedureKind>>
660       specificProcs_;
661 
662   void AddSpecificProcs(const std::list<parser::Name> &, ProcedureKind);
663   void ResolveSpecificsInGeneric(Symbol &generic);
664 };
665 
666 class SubprogramVisitor : public virtual ScopeHandler, public InterfaceVisitor {
667 public:
668   bool HandleStmtFunction(const parser::StmtFunctionStmt &);
669   bool Pre(const parser::SubroutineStmt &);
670   void Post(const parser::SubroutineStmt &);
671   bool Pre(const parser::FunctionStmt &);
672   void Post(const parser::FunctionStmt &);
673   bool Pre(const parser::EntryStmt &);
674   void Post(const parser::EntryStmt &);
675   bool Pre(const parser::InterfaceBody::Subroutine &);
676   void Post(const parser::InterfaceBody::Subroutine &);
677   bool Pre(const parser::InterfaceBody::Function &);
678   void Post(const parser::InterfaceBody::Function &);
679   bool Pre(const parser::Suffix &);
680   bool Pre(const parser::PrefixSpec &);
681   void Post(const parser::ImplicitPart &);
682 
683   bool BeginSubprogram(
684       const parser::Name &, Symbol::Flag, bool hasModulePrefix = false);
685   bool BeginMpSubprogram(const parser::Name &);
686   void PushBlockDataScope(const parser::Name &);
687   void EndSubprogram();
688 
689 protected:
690   // Set when we see a stmt function that is really an array element assignment
691   bool badStmtFuncFound_{false};
692   bool inExecutionPart_{false};
693 
694 private:
695   // Info about the current function: parse tree of the type in the PrefixSpec;
696   // name and symbol of the function result from the Suffix; source location.
697   struct {
698     const parser::DeclarationTypeSpec *parsedType{nullptr};
699     const parser::Name *resultName{nullptr};
700     Symbol *resultSymbol{nullptr};
701     std::optional<SourceName> source;
702   } funcInfo_;
703 
704   // Create a subprogram symbol in the current scope and push a new scope.
705   void CheckExtantExternal(const parser::Name &, Symbol::Flag);
706   Symbol &PushSubprogramScope(const parser::Name &, Symbol::Flag);
707   Symbol *GetSpecificFromGeneric(const parser::Name &);
708   SubprogramDetails &PostSubprogramStmt(const parser::Name &);
709 };
710 
711 class DeclarationVisitor : public ArraySpecVisitor,
712                            public virtual ScopeHandler {
713 public:
714   using ArraySpecVisitor::Post;
715   using ScopeHandler::Post;
716   using ScopeHandler::Pre;
717 
718   bool Pre(const parser::Initialization &);
719   void Post(const parser::EntityDecl &);
720   void Post(const parser::ObjectDecl &);
721   void Post(const parser::PointerDecl &);
722   bool Pre(const parser::BindStmt &) { return BeginAttrs(); }
723   void Post(const parser::BindStmt &) { EndAttrs(); }
724   bool Pre(const parser::BindEntity &);
725   bool Pre(const parser::NamedConstantDef &);
726   bool Pre(const parser::NamedConstant &);
727   void Post(const parser::EnumDef &);
728   bool Pre(const parser::Enumerator &);
729   bool Pre(const parser::AccessSpec &);
730   bool Pre(const parser::AsynchronousStmt &);
731   bool Pre(const parser::ContiguousStmt &);
732   bool Pre(const parser::ExternalStmt &);
733   bool Pre(const parser::IntentStmt &);
734   bool Pre(const parser::IntrinsicStmt &);
735   bool Pre(const parser::OptionalStmt &);
736   bool Pre(const parser::ProtectedStmt &);
737   bool Pre(const parser::ValueStmt &);
738   bool Pre(const parser::VolatileStmt &);
739   bool Pre(const parser::AllocatableStmt &) {
740     objectDeclAttr_ = Attr::ALLOCATABLE;
741     return true;
742   }
743   void Post(const parser::AllocatableStmt &) { objectDeclAttr_ = std::nullopt; }
744   bool Pre(const parser::TargetStmt &) {
745     objectDeclAttr_ = Attr::TARGET;
746     return true;
747   }
748   void Post(const parser::TargetStmt &) { objectDeclAttr_ = std::nullopt; }
749   void Post(const parser::DimensionStmt::Declaration &);
750   void Post(const parser::CodimensionDecl &);
751   bool Pre(const parser::TypeDeclarationStmt &) { return BeginDecl(); }
752   void Post(const parser::TypeDeclarationStmt &);
753   void Post(const parser::IntegerTypeSpec &);
754   void Post(const parser::IntrinsicTypeSpec::Real &);
755   void Post(const parser::IntrinsicTypeSpec::Complex &);
756   void Post(const parser::IntrinsicTypeSpec::Logical &);
757   void Post(const parser::IntrinsicTypeSpec::Character &);
758   void Post(const parser::CharSelector::LengthAndKind &);
759   void Post(const parser::CharLength &);
760   void Post(const parser::LengthSelector &);
761   bool Pre(const parser::KindParam &);
762   bool Pre(const parser::DeclarationTypeSpec::Type &);
763   void Post(const parser::DeclarationTypeSpec::Type &);
764   bool Pre(const parser::DeclarationTypeSpec::Class &);
765   void Post(const parser::DeclarationTypeSpec::Class &);
766   bool Pre(const parser::DeclarationTypeSpec::Record &);
767   void Post(const parser::DerivedTypeSpec &);
768   bool Pre(const parser::DerivedTypeDef &);
769   bool Pre(const parser::DerivedTypeStmt &);
770   void Post(const parser::DerivedTypeStmt &);
771   bool Pre(const parser::TypeParamDefStmt &) { return BeginDecl(); }
772   void Post(const parser::TypeParamDefStmt &);
773   bool Pre(const parser::TypeAttrSpec::Extends &);
774   bool Pre(const parser::PrivateStmt &);
775   bool Pre(const parser::SequenceStmt &);
776   bool Pre(const parser::ComponentDefStmt &) { return BeginDecl(); }
777   void Post(const parser::ComponentDefStmt &) { EndDecl(); }
778   void Post(const parser::ComponentDecl &);
779   bool Pre(const parser::ProcedureDeclarationStmt &);
780   void Post(const parser::ProcedureDeclarationStmt &);
781   bool Pre(const parser::DataComponentDefStmt &); // returns false
782   bool Pre(const parser::ProcComponentDefStmt &);
783   void Post(const parser::ProcComponentDefStmt &);
784   bool Pre(const parser::ProcPointerInit &);
785   void Post(const parser::ProcInterface &);
786   void Post(const parser::ProcDecl &);
787   bool Pre(const parser::TypeBoundProcedurePart &);
788   void Post(const parser::TypeBoundProcedurePart &);
789   void Post(const parser::ContainsStmt &);
790   bool Pre(const parser::TypeBoundProcBinding &) { return BeginAttrs(); }
791   void Post(const parser::TypeBoundProcBinding &) { EndAttrs(); }
792   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &);
793   void Post(const parser::TypeBoundProcedureStmt::WithInterface &);
794   void Post(const parser::FinalProcedureStmt &);
795   bool Pre(const parser::TypeBoundGenericStmt &);
796   bool Pre(const parser::AllocateStmt &);
797   void Post(const parser::AllocateStmt &);
798   bool Pre(const parser::StructureConstructor &);
799   bool Pre(const parser::NamelistStmt::Group &);
800   bool Pre(const parser::IoControlSpec &);
801   bool Pre(const parser::CommonStmt::Block &);
802   void Post(const parser::CommonStmt::Block &);
803   bool Pre(const parser::CommonBlockObject &);
804   void Post(const parser::CommonBlockObject &);
805   bool Pre(const parser::EquivalenceStmt &);
806   bool Pre(const parser::SaveStmt &);
807   bool Pre(const parser::BasedPointerStmt &);
808 
809   void PointerInitialization(
810       const parser::Name &, const parser::InitialDataTarget &);
811   void PointerInitialization(
812       const parser::Name &, const parser::ProcPointerInit &);
813   void NonPointerInitialization(
814       const parser::Name &, const parser::ConstantExpr &, bool inComponentDecl);
815   void CheckExplicitInterface(const parser::Name &);
816   void CheckBindings(const parser::TypeBoundProcedureStmt::WithoutInterface &);
817 
818   const parser::Name *ResolveDesignator(const parser::Designator &);
819 
820 protected:
821   bool BeginDecl();
822   void EndDecl();
823   Symbol &DeclareObjectEntity(const parser::Name &, Attrs);
824   // Make sure that there's an entity in an enclosing scope called Name
825   Symbol &FindOrDeclareEnclosingEntity(const parser::Name &);
826   // Declare a LOCAL/LOCAL_INIT entity. If there isn't a type specified
827   // it comes from the entity in the containing scope, or implicit rules.
828   // Return pointer to the new symbol, or nullptr on error.
829   Symbol *DeclareLocalEntity(const parser::Name &);
830   // Declare a statement entity (e.g., an implied DO loop index).
831   // If there isn't a type specified, implicit rules apply.
832   // Return pointer to the new symbol, or nullptr on error.
833   Symbol *DeclareStatementEntity(
834       const parser::Name &, const std::optional<parser::IntegerTypeSpec> &);
835   bool CheckUseError(const parser::Name &);
836   void CheckAccessibility(const SourceName &, bool, Symbol &);
837   void CheckCommonBlocks();
838   void CheckSaveStmts();
839   void CheckEquivalenceSets();
840   bool CheckNotInBlock(const char *);
841   bool NameIsKnownOrIntrinsic(const parser::Name &);
842 
843   // Each of these returns a pointer to a resolved Name (i.e. with symbol)
844   // or nullptr in case of error.
845   const parser::Name *ResolveStructureComponent(
846       const parser::StructureComponent &);
847   const parser::Name *ResolveDataRef(const parser::DataRef &);
848   const parser::Name *ResolveVariable(const parser::Variable &);
849   const parser::Name *ResolveName(const parser::Name &);
850   bool PassesSharedLocalityChecks(const parser::Name &name, Symbol &symbol);
851   Symbol *NoteInterfaceName(const parser::Name &);
852 
853 private:
854   // The attribute corresponding to the statement containing an ObjectDecl
855   std::optional<Attr> objectDeclAttr_;
856   // Info about current character type while walking DeclTypeSpec.
857   // Also captures any "*length" specifier on an individual declaration.
858   struct {
859     std::optional<ParamValue> length;
860     std::optional<KindExpr> kind;
861   } charInfo_;
862   // Info about current derived type while walking DerivedTypeDef
863   struct {
864     const parser::Name *extends{nullptr}; // EXTENDS(name)
865     bool privateComps{false}; // components are private by default
866     bool privateBindings{false}; // bindings are private by default
867     bool sawContains{false}; // currently processing bindings
868     bool sequence{false}; // is a sequence type
869     const Symbol *type{nullptr}; // derived type being defined
870   } derivedTypeInfo_;
871   // Collect equivalence sets and process at end of specification part
872   std::vector<const std::list<parser::EquivalenceObject> *> equivalenceSets_;
873   // Info about common blocks in the current scope
874   struct {
875     Symbol *curr{nullptr}; // common block currently being processed
876     std::set<SourceName> names; // names in any common block of scope
877   } commonBlockInfo_;
878   // Info about about SAVE statements and attributes in current scope
879   struct {
880     std::optional<SourceName> saveAll; // "SAVE" without entity list
881     std::set<SourceName> entities; // names of entities with save attr
882     std::set<SourceName> commons; // names of common blocks with save attr
883   } saveInfo_;
884   // In a ProcedureDeclarationStmt or ProcComponentDefStmt, this is
885   // the interface name, if any.
886   const parser::Name *interfaceName_{nullptr};
887   // Map type-bound generic to binding names of its specific bindings
888   std::multimap<Symbol *, const parser::Name *> genericBindings_;
889   // Info about current ENUM
890   struct EnumeratorState {
891     // Enum value must hold inside a C_INT (7.6.2).
892     std::optional<int> value{0};
893   } enumerationState_;
894 
895   bool HandleAttributeStmt(Attr, const std::list<parser::Name> &);
896   Symbol &HandleAttributeStmt(Attr, const parser::Name &);
897   Symbol &DeclareUnknownEntity(const parser::Name &, Attrs);
898   Symbol &DeclareProcEntity(const parser::Name &, Attrs, const ProcInterface &);
899   void SetType(const parser::Name &, const DeclTypeSpec &);
900   std::optional<DerivedTypeSpec> ResolveDerivedType(const parser::Name &);
901   std::optional<DerivedTypeSpec> ResolveExtendsType(
902       const parser::Name &, const parser::Name *);
903   Symbol *MakeTypeSymbol(const SourceName &, Details &&);
904   Symbol *MakeTypeSymbol(const parser::Name &, Details &&);
905   bool OkToAddComponent(const parser::Name &, const Symbol * = nullptr);
906   ParamValue GetParamValue(
907       const parser::TypeParamValue &, common::TypeParamAttr attr);
908   Symbol &MakeCommonBlockSymbol(const parser::Name &);
909   void CheckCommonBlockDerivedType(const SourceName &, const Symbol &);
910   std::optional<MessageFixedText> CheckSaveAttr(const Symbol &);
911   Attrs HandleSaveName(const SourceName &, Attrs);
912   void AddSaveName(std::set<SourceName> &, const SourceName &);
913   void SetSaveAttr(Symbol &);
914   bool HandleUnrestrictedSpecificIntrinsicFunction(const parser::Name &);
915   const parser::Name *FindComponent(const parser::Name *, const parser::Name &);
916   bool CheckInitialDataTarget(const Symbol &, const SomeExpr &, SourceName);
917   void CheckInitialProcTarget(const Symbol &, const parser::Name &, SourceName);
918   void Initialization(const parser::Name &, const parser::Initialization &,
919       bool inComponentDecl);
920   bool PassesLocalityChecks(const parser::Name &name, Symbol &symbol);
921 
922   // Declare an object or procedure entity.
923   // T is one of: EntityDetails, ObjectEntityDetails, ProcEntityDetails
924   template <typename T>
925   Symbol &DeclareEntity(const parser::Name &name, Attrs attrs) {
926     Symbol &symbol{MakeSymbol(name, attrs)};
927     if (symbol.has<T>()) {
928       // OK
929     } else if (symbol.has<UnknownDetails>()) {
930       symbol.set_details(T{});
931     } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
932       symbol.set_details(T{std::move(*details)});
933     } else if (std::is_same_v<EntityDetails, T> &&
934         (symbol.has<ObjectEntityDetails>() ||
935             symbol.has<ProcEntityDetails>())) {
936       // OK
937     } else if (auto *details{symbol.detailsIf<UseDetails>()}) {
938       Say(name.source,
939           "'%s' is use-associated from module '%s' and cannot be re-declared"_err_en_US,
940           name.source, GetUsedModule(*details).name());
941     } else if (auto *details{symbol.detailsIf<SubprogramNameDetails>()}) {
942       if (details->kind() == SubprogramKind::Module) {
943         Say2(name,
944             "Declaration of '%s' conflicts with its use as module procedure"_err_en_US,
945             symbol, "Module procedure definition"_en_US);
946       } else if (details->kind() == SubprogramKind::Internal) {
947         Say2(name,
948             "Declaration of '%s' conflicts with its use as internal procedure"_err_en_US,
949             symbol, "Internal procedure definition"_en_US);
950       } else {
951         DIE("unexpected kind");
952       }
953     } else if (std::is_same_v<ObjectEntityDetails, T> &&
954         symbol.has<ProcEntityDetails>()) {
955       SayWithDecl(
956           name, symbol, "'%s' is already declared as a procedure"_err_en_US);
957     } else if (std::is_same_v<ProcEntityDetails, T> &&
958         symbol.has<ObjectEntityDetails>()) {
959       SayWithDecl(
960           name, symbol, "'%s' is already declared as an object"_err_en_US);
961     } else {
962       SayAlreadyDeclared(name, symbol);
963     }
964     return symbol;
965   }
966 };
967 
968 // Resolve construct entities and statement entities.
969 // Check that construct names don't conflict with other names.
970 class ConstructVisitor : public virtual DeclarationVisitor {
971 public:
972   bool Pre(const parser::ConcurrentHeader &);
973   bool Pre(const parser::LocalitySpec::Local &);
974   bool Pre(const parser::LocalitySpec::LocalInit &);
975   bool Pre(const parser::LocalitySpec::Shared &);
976   bool Pre(const parser::AcSpec &);
977   bool Pre(const parser::AcImpliedDo &);
978   bool Pre(const parser::DataImpliedDo &);
979   bool Pre(const parser::DataIDoObject &);
980   bool Pre(const parser::DataStmtObject &);
981   bool Pre(const parser::DataStmtValue &);
982   bool Pre(const parser::DoConstruct &);
983   void Post(const parser::DoConstruct &);
984   bool Pre(const parser::ForallConstruct &);
985   void Post(const parser::ForallConstruct &);
986   bool Pre(const parser::ForallStmt &);
987   void Post(const parser::ForallStmt &);
988   bool Pre(const parser::BlockStmt &);
989   bool Pre(const parser::EndBlockStmt &);
990   void Post(const parser::Selector &);
991   bool Pre(const parser::AssociateStmt &);
992   void Post(const parser::EndAssociateStmt &);
993   void Post(const parser::Association &);
994   void Post(const parser::SelectTypeStmt &);
995   void Post(const parser::SelectRankStmt &);
996   bool Pre(const parser::SelectTypeConstruct &);
997   void Post(const parser::SelectTypeConstruct &);
998   bool Pre(const parser::SelectTypeConstruct::TypeCase &);
999   void Post(const parser::SelectTypeConstruct::TypeCase &);
1000   // Creates Block scopes with neither symbol name nor symbol details.
1001   bool Pre(const parser::SelectRankConstruct::RankCase &);
1002   void Post(const parser::SelectRankConstruct::RankCase &);
1003   void Post(const parser::TypeGuardStmt::Guard &);
1004   void Post(const parser::SelectRankCaseStmt::Rank &);
1005   bool Pre(const parser::ChangeTeamStmt &);
1006   void Post(const parser::EndChangeTeamStmt &);
1007   void Post(const parser::CoarrayAssociation &);
1008 
1009   // Definitions of construct names
1010   bool Pre(const parser::WhereConstructStmt &x) { return CheckDef(x.t); }
1011   bool Pre(const parser::ForallConstructStmt &x) { return CheckDef(x.t); }
1012   bool Pre(const parser::CriticalStmt &x) { return CheckDef(x.t); }
1013   bool Pre(const parser::LabelDoStmt &) {
1014     return false; // error recovery
1015   }
1016   bool Pre(const parser::NonLabelDoStmt &x) { return CheckDef(x.t); }
1017   bool Pre(const parser::IfThenStmt &x) { return CheckDef(x.t); }
1018   bool Pre(const parser::SelectCaseStmt &x) { return CheckDef(x.t); }
1019   bool Pre(const parser::SelectRankConstruct &);
1020   void Post(const parser::SelectRankConstruct &);
1021   bool Pre(const parser::SelectRankStmt &x) {
1022     return CheckDef(std::get<0>(x.t));
1023   }
1024   bool Pre(const parser::SelectTypeStmt &x) {
1025     return CheckDef(std::get<0>(x.t));
1026   }
1027 
1028   // References to construct names
1029   void Post(const parser::MaskedElsewhereStmt &x) { CheckRef(x.t); }
1030   void Post(const parser::ElsewhereStmt &x) { CheckRef(x.v); }
1031   void Post(const parser::EndWhereStmt &x) { CheckRef(x.v); }
1032   void Post(const parser::EndForallStmt &x) { CheckRef(x.v); }
1033   void Post(const parser::EndCriticalStmt &x) { CheckRef(x.v); }
1034   void Post(const parser::EndDoStmt &x) { CheckRef(x.v); }
1035   void Post(const parser::ElseIfStmt &x) { CheckRef(x.t); }
1036   void Post(const parser::ElseStmt &x) { CheckRef(x.v); }
1037   void Post(const parser::EndIfStmt &x) { CheckRef(x.v); }
1038   void Post(const parser::CaseStmt &x) { CheckRef(x.t); }
1039   void Post(const parser::EndSelectStmt &x) { CheckRef(x.v); }
1040   void Post(const parser::SelectRankCaseStmt &x) { CheckRef(x.t); }
1041   void Post(const parser::TypeGuardStmt &x) { CheckRef(x.t); }
1042   void Post(const parser::CycleStmt &x) { CheckRef(x.v); }
1043   void Post(const parser::ExitStmt &x) { CheckRef(x.v); }
1044 
1045 private:
1046   // R1105 selector -> expr | variable
1047   // expr is set in either case unless there were errors
1048   struct Selector {
1049     Selector() {}
1050     Selector(const SourceName &source, MaybeExpr &&expr)
1051         : source{source}, expr{std::move(expr)} {}
1052     operator bool() const { return expr.has_value(); }
1053     parser::CharBlock source;
1054     MaybeExpr expr;
1055   };
1056   // association -> [associate-name =>] selector
1057   struct Association {
1058     const parser::Name *name{nullptr};
1059     Selector selector;
1060   };
1061   std::vector<Association> associationStack_;
1062 
1063   template <typename T> bool CheckDef(const T &t) {
1064     return CheckDef(std::get<std::optional<parser::Name>>(t));
1065   }
1066   template <typename T> void CheckRef(const T &t) {
1067     CheckRef(std::get<std::optional<parser::Name>>(t));
1068   }
1069   bool CheckDef(const std::optional<parser::Name> &);
1070   void CheckRef(const std::optional<parser::Name> &);
1071   const DeclTypeSpec &ToDeclTypeSpec(evaluate::DynamicType &&);
1072   const DeclTypeSpec &ToDeclTypeSpec(
1073       evaluate::DynamicType &&, MaybeSubscriptIntExpr &&length);
1074   Symbol *MakeAssocEntity();
1075   void SetTypeFromAssociation(Symbol &);
1076   void SetAttrsFromAssociation(Symbol &);
1077   Selector ResolveSelector(const parser::Selector &);
1078   void ResolveIndexName(const parser::ConcurrentControl &control);
1079   Association &GetCurrentAssociation();
1080   void PushAssociation();
1081   void PopAssociation();
1082 };
1083 
1084 // Create scopes for OpenMP constructs
1085 class OmpVisitor : public virtual DeclarationVisitor {
1086 public:
1087   void AddOmpSourceRange(const parser::CharBlock &);
1088 
1089   static bool NeedsScope(const parser::OpenMPBlockConstruct &);
1090 
1091   bool Pre(const parser::OpenMPBlockConstruct &);
1092   void Post(const parser::OpenMPBlockConstruct &);
1093   bool Pre(const parser::OmpBeginBlockDirective &x) {
1094     AddOmpSourceRange(x.source);
1095     return true;
1096   }
1097   void Post(const parser::OmpBeginBlockDirective &) {
1098     messageHandler().set_currStmtSource(std::nullopt);
1099   }
1100   bool Pre(const parser::OmpEndBlockDirective &x) {
1101     AddOmpSourceRange(x.source);
1102     return true;
1103   }
1104   void Post(const parser::OmpEndBlockDirective &) {
1105     messageHandler().set_currStmtSource(std::nullopt);
1106   }
1107 
1108   bool Pre(const parser::OpenMPLoopConstruct &) {
1109     PushScope(Scope::Kind::Block, nullptr);
1110     return true;
1111   }
1112   void Post(const parser::OpenMPLoopConstruct &) { PopScope(); }
1113   bool Pre(const parser::OmpBeginLoopDirective &x) {
1114     AddOmpSourceRange(x.source);
1115     return true;
1116   }
1117   void Post(const parser::OmpBeginLoopDirective &) {
1118     messageHandler().set_currStmtSource(std::nullopt);
1119   }
1120   bool Pre(const parser::OmpEndLoopDirective &x) {
1121     AddOmpSourceRange(x.source);
1122     return true;
1123   }
1124   void Post(const parser::OmpEndLoopDirective &) {
1125     messageHandler().set_currStmtSource(std::nullopt);
1126   }
1127 
1128   bool Pre(const parser::OpenMPSectionsConstruct &) {
1129     PushScope(Scope::Kind::Block, nullptr);
1130     return true;
1131   }
1132   void Post(const parser::OpenMPSectionsConstruct &) { PopScope(); }
1133   bool Pre(const parser::OmpBeginSectionsDirective &x) {
1134     AddOmpSourceRange(x.source);
1135     return true;
1136   }
1137   void Post(const parser::OmpBeginSectionsDirective &) {
1138     messageHandler().set_currStmtSource(std::nullopt);
1139   }
1140   bool Pre(const parser::OmpEndSectionsDirective &x) {
1141     AddOmpSourceRange(x.source);
1142     return true;
1143   }
1144   void Post(const parser::OmpEndSectionsDirective &) {
1145     messageHandler().set_currStmtSource(std::nullopt);
1146   }
1147 };
1148 
1149 bool OmpVisitor::NeedsScope(const parser::OpenMPBlockConstruct &x) {
1150   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
1151   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
1152   switch (beginDir.v) {
1153   case parser::OmpBlockDirective::Directive::TargetData:
1154   case parser::OmpBlockDirective::Directive::Master:
1155   case parser::OmpBlockDirective::Directive::Ordered:
1156     return false;
1157   default:
1158     return true;
1159   }
1160 }
1161 
1162 void OmpVisitor::AddOmpSourceRange(const parser::CharBlock &source) {
1163   messageHandler().set_currStmtSource(source);
1164   currScope().AddSourceRange(source);
1165 }
1166 
1167 bool OmpVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
1168   if (NeedsScope(x)) {
1169     PushScope(Scope::Kind::Block, nullptr);
1170   }
1171   return true;
1172 }
1173 
1174 void OmpVisitor::Post(const parser::OpenMPBlockConstruct &x) {
1175   if (NeedsScope(x)) {
1176     PopScope();
1177   }
1178 }
1179 
1180 // Data-sharing and Data-mapping attributes for data-refs in OpenMP construct
1181 class OmpAttributeVisitor {
1182 public:
1183   explicit OmpAttributeVisitor(
1184       SemanticsContext &context, ResolveNamesVisitor &resolver)
1185       : context_{context}, resolver_{resolver} {}
1186 
1187   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
1188 
1189   template <typename A> bool Pre(const A &) { return true; }
1190   template <typename A> void Post(const A &) {}
1191 
1192   bool Pre(const parser::SpecificationPart &x) {
1193     Walk(std::get<std::list<parser::OpenMPDeclarativeConstruct>>(x.t));
1194     return false;
1195   }
1196 
1197   bool Pre(const parser::OpenMPBlockConstruct &);
1198   void Post(const parser::OpenMPBlockConstruct &) { PopContext(); }
1199   void Post(const parser::OmpBeginBlockDirective &) {
1200     GetContext().withinConstruct = true;
1201   }
1202 
1203   bool Pre(const parser::OpenMPLoopConstruct &);
1204   void Post(const parser::OpenMPLoopConstruct &) { PopContext(); }
1205   void Post(const parser::OmpBeginLoopDirective &) {
1206     GetContext().withinConstruct = true;
1207   }
1208   bool Pre(const parser::DoConstruct &);
1209 
1210   bool Pre(const parser::OpenMPSectionsConstruct &);
1211   void Post(const parser::OpenMPSectionsConstruct &) { PopContext(); }
1212 
1213   bool Pre(const parser::OpenMPThreadprivate &);
1214   void Post(const parser::OpenMPThreadprivate &) { PopContext(); }
1215 
1216   // 2.15.3 Data-Sharing Attribute Clauses
1217   void Post(const parser::OmpDefaultClause &);
1218   bool Pre(const parser::OmpClause::Shared &x) {
1219     ResolveOmpObjectList(x.v, Symbol::Flag::OmpShared);
1220     return false;
1221   }
1222   bool Pre(const parser::OmpClause::Private &x) {
1223     ResolveOmpObjectList(x.v, Symbol::Flag::OmpPrivate);
1224     return false;
1225   }
1226   bool Pre(const parser::OmpClause::Firstprivate &x) {
1227     ResolveOmpObjectList(x.v, Symbol::Flag::OmpFirstPrivate);
1228     return false;
1229   }
1230   bool Pre(const parser::OmpClause::Lastprivate &x) {
1231     ResolveOmpObjectList(x.v, Symbol::Flag::OmpLastPrivate);
1232     return false;
1233   }
1234 
1235   void Post(const parser::Name &);
1236 
1237 private:
1238   struct OmpContext {
1239     OmpContext(const parser::CharBlock &source, OmpDirective d, Scope &s)
1240         : directiveSource{source}, directive{d}, scope{s} {}
1241     parser::CharBlock directiveSource;
1242     OmpDirective directive;
1243     Scope &scope;
1244     // TODO: default DSA is implicitly determined in different ways
1245     Symbol::Flag defaultDSA{Symbol::Flag::OmpShared};
1246     // variables on Data-sharing attribute clauses
1247     std::map<const Symbol *, Symbol::Flag> objectWithDSA;
1248     bool withinConstruct{false};
1249     std::int64_t associatedLoopLevel{0};
1250   };
1251   // back() is the top of the stack
1252   OmpContext &GetContext() {
1253     CHECK(!ompContext_.empty());
1254     return ompContext_.back();
1255   }
1256   void PushContext(const parser::CharBlock &source, OmpDirective dir) {
1257     ompContext_.emplace_back(source, dir, context_.FindScope(source));
1258   }
1259   void PopContext() { ompContext_.pop_back(); }
1260   void SetContextDirectiveSource(parser::CharBlock &dir) {
1261     GetContext().directiveSource = dir;
1262   }
1263   void SetContextDirectiveEnum(OmpDirective dir) {
1264     GetContext().directive = dir;
1265   }
1266   Scope &currScope() { return GetContext().scope; }
1267   void SetContextDefaultDSA(Symbol::Flag flag) {
1268     GetContext().defaultDSA = flag;
1269   }
1270   void AddToContextObjectWithDSA(
1271       const Symbol &symbol, Symbol::Flag flag, OmpContext &context) {
1272     context.objectWithDSA.emplace(&symbol, flag);
1273   }
1274   void AddToContextObjectWithDSA(const Symbol &symbol, Symbol::Flag flag) {
1275     AddToContextObjectWithDSA(symbol, flag, GetContext());
1276   }
1277   bool IsObjectWithDSA(const Symbol &symbol) {
1278     auto it{GetContext().objectWithDSA.find(&symbol)};
1279     return it != GetContext().objectWithDSA.end();
1280   }
1281 
1282   void SetContextAssociatedLoopLevel(std::int64_t level) {
1283     GetContext().associatedLoopLevel = level;
1284   }
1285   std::int64_t GetAssociatedLoopLevelFromClauses(const parser::OmpClauseList &);
1286 
1287   Symbol &MakeAssocSymbol(const SourceName &name, Symbol &prev, Scope &scope) {
1288     const auto pair{scope.try_emplace(name, Attrs{}, HostAssocDetails{prev})};
1289     return *pair.first->second;
1290   }
1291   Symbol &MakeAssocSymbol(const SourceName &name, Symbol &prev) {
1292     return MakeAssocSymbol(name, prev, currScope());
1293   }
1294 
1295   static const parser::Name *GetDesignatorNameIfDataRef(
1296       const parser::Designator &designator) {
1297     const auto *dataRef{std::get_if<parser::DataRef>(&designator.u)};
1298     return dataRef ? std::get_if<parser::Name>(&dataRef->u) : nullptr;
1299   }
1300 
1301   static constexpr Symbol::Flags dataSharingAttributeFlags{
1302       Symbol::Flag::OmpShared, Symbol::Flag::OmpPrivate,
1303       Symbol::Flag::OmpFirstPrivate, Symbol::Flag::OmpLastPrivate,
1304       Symbol::Flag::OmpReduction, Symbol::Flag::OmpLinear};
1305 
1306   static constexpr Symbol::Flags ompFlagsRequireNewSymbol{
1307       Symbol::Flag::OmpPrivate, Symbol::Flag::OmpLinear,
1308       Symbol::Flag::OmpFirstPrivate, Symbol::Flag::OmpLastPrivate,
1309       Symbol::Flag::OmpReduction};
1310 
1311   static constexpr Symbol::Flags ompFlagsRequireMark{
1312       Symbol::Flag::OmpThreadprivate};
1313 
1314   void AddDataSharingAttributeObject(SymbolRef object) {
1315     dataSharingAttributeObjects_.insert(object);
1316   }
1317   void ClearDataSharingAttributeObjects() {
1318     dataSharingAttributeObjects_.clear();
1319   }
1320   bool HasDataSharingAttributeObject(const Symbol &);
1321 
1322   const parser::DoConstruct *GetDoConstructIf(
1323       const parser::ExecutionPartConstruct &);
1324   // Predetermined DSA rules
1325   void PrivatizeAssociatedLoopIndex(const parser::OpenMPLoopConstruct &);
1326   const parser::Name &GetLoopIndex(const parser::DoConstruct &);
1327   void ResolveSeqLoopIndexInParallelOrTaskConstruct(const parser::Name &);
1328 
1329   void ResolveOmpObjectList(const parser::OmpObjectList &, Symbol::Flag);
1330   void ResolveOmpObject(const parser::OmpObject &, Symbol::Flag);
1331   Symbol *ResolveOmp(const parser::Name &, Symbol::Flag, Scope &);
1332   Symbol *ResolveOmp(Symbol &, Symbol::Flag, Scope &);
1333   Symbol *ResolveOmpCommonBlockName(const parser::Name *);
1334   Symbol *DeclarePrivateAccessEntity(
1335       const parser::Name &, Symbol::Flag, Scope &);
1336   Symbol *DeclarePrivateAccessEntity(Symbol &, Symbol::Flag, Scope &);
1337   Symbol *DeclareOrMarkOtherAccessEntity(const parser::Name &, Symbol::Flag);
1338   Symbol *DeclareOrMarkOtherAccessEntity(Symbol &, Symbol::Flag);
1339   void CheckMultipleAppearances(
1340       const parser::Name &, const Symbol &, Symbol::Flag);
1341   SymbolSet dataSharingAttributeObjects_; // on one directive
1342 
1343   SemanticsContext &context_;
1344   ResolveNamesVisitor &resolver_;
1345   std::vector<OmpContext> ompContext_; // used as a stack
1346 };
1347 
1348 // Walk the parse tree and resolve names to symbols.
1349 class ResolveNamesVisitor : public virtual ScopeHandler,
1350                             public ModuleVisitor,
1351                             public SubprogramVisitor,
1352                             public ConstructVisitor,
1353                             public OmpVisitor {
1354 public:
1355   using ArraySpecVisitor::Post;
1356   using ConstructVisitor::Post;
1357   using ConstructVisitor::Pre;
1358   using DeclarationVisitor::Post;
1359   using DeclarationVisitor::Pre;
1360   using ImplicitRulesVisitor::Post;
1361   using ImplicitRulesVisitor::Pre;
1362   using InterfaceVisitor::Post;
1363   using InterfaceVisitor::Pre;
1364   using ModuleVisitor::Post;
1365   using ModuleVisitor::Pre;
1366   using OmpVisitor::Post;
1367   using OmpVisitor::Pre;
1368   using ScopeHandler::Post;
1369   using ScopeHandler::Pre;
1370   using SubprogramVisitor::Post;
1371   using SubprogramVisitor::Pre;
1372 
1373   ResolveNamesVisitor(SemanticsContext &context, ImplicitRulesMap &rules)
1374       : BaseVisitor{context, *this, rules} {
1375     PushScope(context.globalScope());
1376   }
1377 
1378   // Default action for a parse tree node is to visit children.
1379   template <typename T> bool Pre(const T &) { return true; }
1380   template <typename T> void Post(const T &) {}
1381 
1382   bool Pre(const parser::SpecificationPart &);
1383   void Post(const parser::Program &);
1384   bool Pre(const parser::ImplicitStmt &);
1385   void Post(const parser::PointerObject &);
1386   void Post(const parser::AllocateObject &);
1387   bool Pre(const parser::PointerAssignmentStmt &);
1388   void Post(const parser::Designator &);
1389   template <typename A, typename B>
1390   void Post(const parser::LoopBounds<A, B> &x) {
1391     ResolveName(*parser::Unwrap<parser::Name>(x.name));
1392   }
1393   void Post(const parser::ProcComponentRef &);
1394   bool Pre(const parser::ActualArg &);
1395   bool Pre(const parser::FunctionReference &);
1396   bool Pre(const parser::CallStmt &);
1397   bool Pre(const parser::ImportStmt &);
1398   void Post(const parser::TypeGuardStmt &);
1399   bool Pre(const parser::StmtFunctionStmt &);
1400   bool Pre(const parser::DefinedOpName &);
1401   bool Pre(const parser::ProgramUnit &);
1402   void Post(const parser::AssignStmt &);
1403   void Post(const parser::AssignedGotoStmt &);
1404 
1405   // These nodes should never be reached: they are handled in ProgramUnit
1406   bool Pre(const parser::MainProgram &) {
1407     llvm_unreachable("This node is handled in ProgramUnit");
1408   }
1409   bool Pre(const parser::FunctionSubprogram &) {
1410     llvm_unreachable("This node is handled in ProgramUnit");
1411   }
1412   bool Pre(const parser::SubroutineSubprogram &) {
1413     llvm_unreachable("This node is handled in ProgramUnit");
1414   }
1415   bool Pre(const parser::SeparateModuleSubprogram &) {
1416     llvm_unreachable("This node is handled in ProgramUnit");
1417   }
1418   bool Pre(const parser::Module &) {
1419     llvm_unreachable("This node is handled in ProgramUnit");
1420   }
1421   bool Pre(const parser::Submodule &) {
1422     llvm_unreachable("This node is handled in ProgramUnit");
1423   }
1424   bool Pre(const parser::BlockData &) {
1425     llvm_unreachable("This node is handled in ProgramUnit");
1426   }
1427 
1428   void NoteExecutablePartCall(Symbol::Flag, const parser::Call &);
1429 
1430   friend void ResolveSpecificationParts(SemanticsContext &, const Symbol &);
1431 
1432 private:
1433   // Kind of procedure we are expecting to see in a ProcedureDesignator
1434   std::optional<Symbol::Flag> expectedProcFlag_;
1435   std::optional<SourceName> prevImportStmt_;
1436 
1437   void PreSpecificationConstruct(const parser::SpecificationConstruct &);
1438   void CreateGeneric(const parser::GenericSpec &);
1439   void FinishSpecificationPart();
1440   void CheckImports();
1441   void CheckImport(const SourceName &, const SourceName &);
1442   void HandleCall(Symbol::Flag, const parser::Call &);
1443   void HandleProcedureName(Symbol::Flag, const parser::Name &);
1444   bool SetProcFlag(const parser::Name &, Symbol &, Symbol::Flag);
1445   void ResolveSpecificationParts(ProgramTree &);
1446   void AddSubpNames(ProgramTree &);
1447   bool BeginScopeForNode(const ProgramTree &);
1448   void FinishSpecificationParts(const ProgramTree &);
1449   void FinishDerivedTypeInstantiation(Scope &);
1450   void ResolveExecutionParts(const ProgramTree &);
1451   void ResolveOmpParts(const parser::ProgramUnit &);
1452 };
1453 
1454 // ImplicitRules implementation
1455 
1456 bool ImplicitRules::isImplicitNoneType() const {
1457   if (isImplicitNoneType_) {
1458     return true;
1459   } else if (map_.empty() && inheritFromParent_) {
1460     return parent_->isImplicitNoneType();
1461   } else {
1462     return false; // default if not specified
1463   }
1464 }
1465 
1466 bool ImplicitRules::isImplicitNoneExternal() const {
1467   if (isImplicitNoneExternal_) {
1468     return true;
1469   } else if (inheritFromParent_) {
1470     return parent_->isImplicitNoneExternal();
1471   } else {
1472     return false; // default if not specified
1473   }
1474 }
1475 
1476 const DeclTypeSpec *ImplicitRules::GetType(char ch) const {
1477   if (isImplicitNoneType_) {
1478     return nullptr;
1479   } else if (auto it{map_.find(ch)}; it != map_.end()) {
1480     return &*it->second;
1481   } else if (inheritFromParent_) {
1482     return parent_->GetType(ch);
1483   } else if (ch >= 'i' && ch <= 'n') {
1484     return &context_.MakeNumericType(TypeCategory::Integer);
1485   } else if (ch >= 'a' && ch <= 'z') {
1486     return &context_.MakeNumericType(TypeCategory::Real);
1487   } else {
1488     return nullptr;
1489   }
1490 }
1491 
1492 void ImplicitRules::SetTypeMapping(const DeclTypeSpec &type,
1493     parser::Location fromLetter, parser::Location toLetter) {
1494   for (char ch = *fromLetter; ch; ch = ImplicitRules::Incr(ch)) {
1495     auto res{map_.emplace(ch, type)};
1496     if (!res.second) {
1497       context_.Say(parser::CharBlock{fromLetter},
1498           "More than one implicit type specified for '%c'"_err_en_US, ch);
1499     }
1500     if (ch == *toLetter) {
1501       break;
1502     }
1503   }
1504 }
1505 
1506 // Return the next char after ch in a way that works for ASCII or EBCDIC.
1507 // Return '\0' for the char after 'z'.
1508 char ImplicitRules::Incr(char ch) {
1509   switch (ch) {
1510   case 'i':
1511     return 'j';
1512   case 'r':
1513     return 's';
1514   case 'z':
1515     return '\0';
1516   default:
1517     return ch + 1;
1518   }
1519 }
1520 
1521 llvm::raw_ostream &operator<<(
1522     llvm::raw_ostream &o, const ImplicitRules &implicitRules) {
1523   o << "ImplicitRules:\n";
1524   for (char ch = 'a'; ch; ch = ImplicitRules::Incr(ch)) {
1525     ShowImplicitRule(o, implicitRules, ch);
1526   }
1527   ShowImplicitRule(o, implicitRules, '_');
1528   ShowImplicitRule(o, implicitRules, '$');
1529   ShowImplicitRule(o, implicitRules, '@');
1530   return o;
1531 }
1532 void ShowImplicitRule(
1533     llvm::raw_ostream &o, const ImplicitRules &implicitRules, char ch) {
1534   auto it{implicitRules.map_.find(ch)};
1535   if (it != implicitRules.map_.end()) {
1536     o << "  " << ch << ": " << *it->second << '\n';
1537   }
1538 }
1539 
1540 template <typename T> void BaseVisitor::Walk(const T &x) {
1541   parser::Walk(x, *this_);
1542 }
1543 
1544 void BaseVisitor::MakePlaceholder(
1545     const parser::Name &name, MiscDetails::Kind kind) {
1546   if (!name.symbol) {
1547     name.symbol = &context_->globalScope().MakeSymbol(
1548         name.source, Attrs{}, MiscDetails{kind});
1549   }
1550 }
1551 
1552 // AttrsVisitor implementation
1553 
1554 bool AttrsVisitor::BeginAttrs() {
1555   CHECK(!attrs_);
1556   attrs_ = std::make_optional<Attrs>();
1557   return true;
1558 }
1559 Attrs AttrsVisitor::GetAttrs() {
1560   CHECK(attrs_);
1561   return *attrs_;
1562 }
1563 Attrs AttrsVisitor::EndAttrs() {
1564   Attrs result{GetAttrs()};
1565   attrs_.reset();
1566   passName_ = std::nullopt;
1567   bindName_.reset();
1568   return result;
1569 }
1570 
1571 bool AttrsVisitor::SetPassNameOn(Symbol &symbol) {
1572   if (!passName_) {
1573     return false;
1574   }
1575   std::visit(common::visitors{
1576                  [&](ProcEntityDetails &x) { x.set_passName(*passName_); },
1577                  [&](ProcBindingDetails &x) { x.set_passName(*passName_); },
1578                  [](auto &) { common::die("unexpected pass name"); },
1579              },
1580       symbol.details());
1581   return true;
1582 }
1583 
1584 bool AttrsVisitor::SetBindNameOn(Symbol &symbol) {
1585   if (!bindName_) {
1586     return false;
1587   }
1588   std::visit(
1589       common::visitors{
1590           [&](EntityDetails &x) { x.set_bindName(std::move(bindName_)); },
1591           [&](ObjectEntityDetails &x) { x.set_bindName(std::move(bindName_)); },
1592           [&](ProcEntityDetails &x) { x.set_bindName(std::move(bindName_)); },
1593           [&](SubprogramDetails &x) { x.set_bindName(std::move(bindName_)); },
1594           [&](CommonBlockDetails &x) { x.set_bindName(std::move(bindName_)); },
1595           [](auto &) { common::die("unexpected bind name"); },
1596       },
1597       symbol.details());
1598   return true;
1599 }
1600 
1601 void AttrsVisitor::Post(const parser::LanguageBindingSpec &x) {
1602   CHECK(attrs_);
1603   if (CheckAndSet(Attr::BIND_C)) {
1604     if (x.v) {
1605       bindName_ = EvaluateExpr(*x.v);
1606     }
1607   }
1608 }
1609 bool AttrsVisitor::Pre(const parser::IntentSpec &x) {
1610   CHECK(attrs_);
1611   CheckAndSet(IntentSpecToAttr(x));
1612   return false;
1613 }
1614 bool AttrsVisitor::Pre(const parser::Pass &x) {
1615   if (CheckAndSet(Attr::PASS)) {
1616     if (x.v) {
1617       passName_ = x.v->source;
1618       MakePlaceholder(*x.v, MiscDetails::Kind::PassName);
1619     }
1620   }
1621   return false;
1622 }
1623 
1624 // C730, C743, C755, C778, C1543 say no attribute or prefix repetitions
1625 bool AttrsVisitor::IsDuplicateAttr(Attr attrName) {
1626   if (attrs_->test(attrName)) {
1627     Say(currStmtSource().value(),
1628         "Attribute '%s' cannot be used more than once"_en_US,
1629         AttrToString(attrName));
1630     return true;
1631   }
1632   return false;
1633 }
1634 
1635 // See if attrName violates a constraint cause by a conflict.  attr1 and attr2
1636 // name attributes that cannot be used on the same declaration
1637 bool AttrsVisitor::HaveAttrConflict(Attr attrName, Attr attr1, Attr attr2) {
1638   if ((attrName == attr1 && attrs_->test(attr2)) ||
1639       (attrName == attr2 && attrs_->test(attr1))) {
1640     Say(currStmtSource().value(),
1641         "Attributes '%s' and '%s' conflict with each other"_err_en_US,
1642         AttrToString(attr1), AttrToString(attr2));
1643     return true;
1644   }
1645   return false;
1646 }
1647 // C759, C1543
1648 bool AttrsVisitor::IsConflictingAttr(Attr attrName) {
1649   return HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_INOUT) ||
1650       HaveAttrConflict(attrName, Attr::INTENT_IN, Attr::INTENT_OUT) ||
1651       HaveAttrConflict(attrName, Attr::INTENT_INOUT, Attr::INTENT_OUT) ||
1652       HaveAttrConflict(attrName, Attr::PASS, Attr::NOPASS) ||
1653       HaveAttrConflict(attrName, Attr::PURE, Attr::IMPURE) ||
1654       HaveAttrConflict(attrName, Attr::PUBLIC, Attr::PRIVATE) ||
1655       HaveAttrConflict(attrName, Attr::RECURSIVE, Attr::NON_RECURSIVE);
1656 }
1657 bool AttrsVisitor::CheckAndSet(Attr attrName) {
1658   CHECK(attrs_);
1659   if (IsConflictingAttr(attrName) || IsDuplicateAttr(attrName)) {
1660     return false;
1661   }
1662   attrs_->set(attrName);
1663   return true;
1664 }
1665 
1666 // DeclTypeSpecVisitor implementation
1667 
1668 const DeclTypeSpec *DeclTypeSpecVisitor::GetDeclTypeSpec() {
1669   return state_.declTypeSpec;
1670 }
1671 
1672 void DeclTypeSpecVisitor::BeginDeclTypeSpec() {
1673   CHECK(!state_.expectDeclTypeSpec);
1674   CHECK(!state_.declTypeSpec);
1675   state_.expectDeclTypeSpec = true;
1676 }
1677 void DeclTypeSpecVisitor::EndDeclTypeSpec() {
1678   CHECK(state_.expectDeclTypeSpec);
1679   state_ = {};
1680 }
1681 
1682 void DeclTypeSpecVisitor::SetDeclTypeSpecCategory(
1683     DeclTypeSpec::Category category) {
1684   CHECK(state_.expectDeclTypeSpec);
1685   state_.derived.category = category;
1686 }
1687 
1688 bool DeclTypeSpecVisitor::Pre(const parser::TypeGuardStmt &) {
1689   BeginDeclTypeSpec();
1690   return true;
1691 }
1692 void DeclTypeSpecVisitor::Post(const parser::TypeGuardStmt &) {
1693   EndDeclTypeSpec();
1694 }
1695 
1696 void DeclTypeSpecVisitor::Post(const parser::TypeSpec &typeSpec) {
1697   // Record the resolved DeclTypeSpec in the parse tree for use by
1698   // expression semantics if the DeclTypeSpec is a valid TypeSpec.
1699   // The grammar ensures that it's an intrinsic or derived type spec,
1700   // not TYPE(*) or CLASS(*) or CLASS(T).
1701   if (const DeclTypeSpec * spec{state_.declTypeSpec}) {
1702     switch (spec->category()) {
1703     case DeclTypeSpec::Numeric:
1704     case DeclTypeSpec::Logical:
1705     case DeclTypeSpec::Character:
1706       typeSpec.declTypeSpec = spec;
1707       break;
1708     case DeclTypeSpec::TypeDerived:
1709       if (const DerivedTypeSpec * derived{spec->AsDerived()}) {
1710         CheckForAbstractType(derived->typeSymbol()); // C703
1711         typeSpec.declTypeSpec = spec;
1712       }
1713       break;
1714     default:
1715       CRASH_NO_CASE;
1716     }
1717   }
1718 }
1719 
1720 void DeclTypeSpecVisitor::Post(
1721     const parser::IntrinsicTypeSpec::DoublePrecision &) {
1722   MakeNumericType(TypeCategory::Real, context().doublePrecisionKind());
1723 }
1724 void DeclTypeSpecVisitor::Post(
1725     const parser::IntrinsicTypeSpec::DoubleComplex &) {
1726   MakeNumericType(TypeCategory::Complex, context().doublePrecisionKind());
1727 }
1728 void DeclTypeSpecVisitor::MakeNumericType(TypeCategory category, int kind) {
1729   SetDeclTypeSpec(context().MakeNumericType(category, kind));
1730 }
1731 
1732 void DeclTypeSpecVisitor::CheckForAbstractType(const Symbol &typeSymbol) {
1733   if (typeSymbol.attrs().test(Attr::ABSTRACT)) {
1734     Say("ABSTRACT derived type may not be used here"_err_en_US);
1735   }
1736 }
1737 
1738 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::ClassStar &) {
1739   SetDeclTypeSpec(context().globalScope().MakeClassStarType());
1740 }
1741 void DeclTypeSpecVisitor::Post(const parser::DeclarationTypeSpec::TypeStar &) {
1742   SetDeclTypeSpec(context().globalScope().MakeTypeStarType());
1743 }
1744 
1745 // Check that we're expecting to see a DeclTypeSpec (and haven't seen one yet)
1746 // and save it in state_.declTypeSpec.
1747 void DeclTypeSpecVisitor::SetDeclTypeSpec(const DeclTypeSpec &declTypeSpec) {
1748   CHECK(state_.expectDeclTypeSpec);
1749   CHECK(!state_.declTypeSpec);
1750   state_.declTypeSpec = &declTypeSpec;
1751 }
1752 
1753 KindExpr DeclTypeSpecVisitor::GetKindParamExpr(
1754     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
1755   return AnalyzeKindSelector(context(), category, kind);
1756 }
1757 
1758 // MessageHandler implementation
1759 
1760 Message &MessageHandler::Say(MessageFixedText &&msg) {
1761   return context_->Say(currStmtSource().value(), std::move(msg));
1762 }
1763 Message &MessageHandler::Say(MessageFormattedText &&msg) {
1764   return context_->Say(currStmtSource().value(), std::move(msg));
1765 }
1766 Message &MessageHandler::Say(const SourceName &name, MessageFixedText &&msg) {
1767   return Say(name, std::move(msg), name);
1768 }
1769 
1770 // ImplicitRulesVisitor implementation
1771 
1772 void ImplicitRulesVisitor::Post(const parser::ParameterStmt &) {
1773   prevParameterStmt_ = currStmtSource();
1774 }
1775 
1776 bool ImplicitRulesVisitor::Pre(const parser::ImplicitStmt &x) {
1777   bool result{
1778       std::visit(common::visitors{
1779                      [&](const std::list<ImplicitNoneNameSpec> &y) {
1780                        return HandleImplicitNone(y);
1781                      },
1782                      [&](const std::list<parser::ImplicitSpec> &) {
1783                        if (prevImplicitNoneType_) {
1784                          Say("IMPLICIT statement after IMPLICIT NONE or "
1785                              "IMPLICIT NONE(TYPE) statement"_err_en_US);
1786                          return false;
1787                        } else {
1788                          implicitRules().set_isImplicitNoneType(false);
1789                        }
1790                        return true;
1791                      },
1792                  },
1793           x.u)};
1794   prevImplicit_ = currStmtSource();
1795   return result;
1796 }
1797 
1798 bool ImplicitRulesVisitor::Pre(const parser::LetterSpec &x) {
1799   auto loLoc{std::get<parser::Location>(x.t)};
1800   auto hiLoc{loLoc};
1801   if (auto hiLocOpt{std::get<std::optional<parser::Location>>(x.t)}) {
1802     hiLoc = *hiLocOpt;
1803     if (*hiLoc < *loLoc) {
1804       Say(hiLoc, "'%s' does not follow '%s' alphabetically"_err_en_US,
1805           std::string(hiLoc, 1), std::string(loLoc, 1));
1806       return false;
1807     }
1808   }
1809   implicitRules().SetTypeMapping(*GetDeclTypeSpec(), loLoc, hiLoc);
1810   return false;
1811 }
1812 
1813 bool ImplicitRulesVisitor::Pre(const parser::ImplicitSpec &) {
1814   BeginDeclTypeSpec();
1815   set_allowForwardReferenceToDerivedType(true);
1816   return true;
1817 }
1818 
1819 void ImplicitRulesVisitor::Post(const parser::ImplicitSpec &) {
1820   EndDeclTypeSpec();
1821 }
1822 
1823 void ImplicitRulesVisitor::SetScope(const Scope &scope) {
1824   implicitRules_ = &DEREF(implicitRulesMap_).at(&scope);
1825   prevImplicit_ = std::nullopt;
1826   prevImplicitNone_ = std::nullopt;
1827   prevImplicitNoneType_ = std::nullopt;
1828   prevParameterStmt_ = std::nullopt;
1829 }
1830 void ImplicitRulesVisitor::BeginScope(const Scope &scope) {
1831   // find or create implicit rules for this scope
1832   DEREF(implicitRulesMap_).try_emplace(&scope, context(), implicitRules_);
1833   SetScope(scope);
1834 }
1835 
1836 // TODO: for all of these errors, reference previous statement too
1837 bool ImplicitRulesVisitor::HandleImplicitNone(
1838     const std::list<ImplicitNoneNameSpec> &nameSpecs) {
1839   if (prevImplicitNone_) {
1840     Say("More than one IMPLICIT NONE statement"_err_en_US);
1841     Say(*prevImplicitNone_, "Previous IMPLICIT NONE statement"_en_US);
1842     return false;
1843   }
1844   if (prevParameterStmt_) {
1845     Say("IMPLICIT NONE statement after PARAMETER statement"_err_en_US);
1846     return false;
1847   }
1848   prevImplicitNone_ = currStmtSource();
1849   if (nameSpecs.empty()) {
1850     prevImplicitNoneType_ = currStmtSource();
1851     implicitRules().set_isImplicitNoneType(true);
1852     if (prevImplicit_) {
1853       Say("IMPLICIT NONE statement after IMPLICIT statement"_err_en_US);
1854       return false;
1855     }
1856   } else {
1857     int sawType{0};
1858     int sawExternal{0};
1859     for (const auto noneSpec : nameSpecs) {
1860       switch (noneSpec) {
1861       case ImplicitNoneNameSpec::External:
1862         implicitRules().set_isImplicitNoneExternal(true);
1863         ++sawExternal;
1864         break;
1865       case ImplicitNoneNameSpec::Type:
1866         prevImplicitNoneType_ = currStmtSource();
1867         implicitRules().set_isImplicitNoneType(true);
1868         if (prevImplicit_) {
1869           Say("IMPLICIT NONE(TYPE) after IMPLICIT statement"_err_en_US);
1870           return false;
1871         }
1872         ++sawType;
1873         break;
1874       }
1875     }
1876     if (sawType > 1) {
1877       Say("TYPE specified more than once in IMPLICIT NONE statement"_err_en_US);
1878       return false;
1879     }
1880     if (sawExternal > 1) {
1881       Say("EXTERNAL specified more than once in IMPLICIT NONE statement"_err_en_US);
1882       return false;
1883     }
1884   }
1885   return true;
1886 }
1887 
1888 // ArraySpecVisitor implementation
1889 
1890 void ArraySpecVisitor::Post(const parser::ArraySpec &x) {
1891   CHECK(arraySpec_.empty());
1892   arraySpec_ = AnalyzeArraySpec(context(), x);
1893 }
1894 void ArraySpecVisitor::Post(const parser::ComponentArraySpec &x) {
1895   CHECK(arraySpec_.empty());
1896   arraySpec_ = AnalyzeArraySpec(context(), x);
1897 }
1898 void ArraySpecVisitor::Post(const parser::CoarraySpec &x) {
1899   CHECK(coarraySpec_.empty());
1900   coarraySpec_ = AnalyzeCoarraySpec(context(), x);
1901 }
1902 
1903 const ArraySpec &ArraySpecVisitor::arraySpec() {
1904   return !arraySpec_.empty() ? arraySpec_ : attrArraySpec_;
1905 }
1906 const ArraySpec &ArraySpecVisitor::coarraySpec() {
1907   return !coarraySpec_.empty() ? coarraySpec_ : attrCoarraySpec_;
1908 }
1909 void ArraySpecVisitor::BeginArraySpec() {
1910   CHECK(arraySpec_.empty());
1911   CHECK(coarraySpec_.empty());
1912   CHECK(attrArraySpec_.empty());
1913   CHECK(attrCoarraySpec_.empty());
1914 }
1915 void ArraySpecVisitor::EndArraySpec() {
1916   CHECK(arraySpec_.empty());
1917   CHECK(coarraySpec_.empty());
1918   attrArraySpec_.clear();
1919   attrCoarraySpec_.clear();
1920 }
1921 void ArraySpecVisitor::PostAttrSpec() {
1922   // Save dimension/codimension from attrs so we can process array/coarray-spec
1923   // on the entity-decl
1924   if (!arraySpec_.empty()) {
1925     if (attrArraySpec_.empty()) {
1926       attrArraySpec_ = arraySpec_;
1927       arraySpec_.clear();
1928     } else {
1929       Say(currStmtSource().value(),
1930           "Attribute 'DIMENSION' cannot be used more than once"_err_en_US);
1931     }
1932   }
1933   if (!coarraySpec_.empty()) {
1934     if (attrCoarraySpec_.empty()) {
1935       attrCoarraySpec_ = coarraySpec_;
1936       coarraySpec_.clear();
1937     } else {
1938       Say(currStmtSource().value(),
1939           "Attribute 'CODIMENSION' cannot be used more than once"_err_en_US);
1940     }
1941   }
1942 }
1943 
1944 // ScopeHandler implementation
1945 
1946 void ScopeHandler::SayAlreadyDeclared(const parser::Name &name, Symbol &prev) {
1947   SayAlreadyDeclared(name.source, prev);
1948 }
1949 void ScopeHandler::SayAlreadyDeclared(const SourceName &name, Symbol &prev) {
1950   if (context().HasError(prev)) {
1951     // don't report another error about prev
1952   } else if (const auto *details{prev.detailsIf<UseDetails>()}) {
1953     Say(name, "'%s' is already declared in this scoping unit"_err_en_US)
1954         .Attach(details->location(),
1955             "It is use-associated with '%s' in module '%s'"_err_en_US,
1956             details->symbol().name(), GetUsedModule(*details).name());
1957   } else {
1958     SayAlreadyDeclared(name, prev.name());
1959   }
1960   context().SetError(prev);
1961 }
1962 void ScopeHandler::SayAlreadyDeclared(
1963     const SourceName &name1, const SourceName &name2) {
1964   if (name1.begin() < name2.begin()) {
1965     SayAlreadyDeclared(name2, name1);
1966   } else {
1967     Say(name1, "'%s' is already declared in this scoping unit"_err_en_US)
1968         .Attach(name2, "Previous declaration of '%s'"_en_US, name2);
1969   }
1970 }
1971 
1972 void ScopeHandler::SayWithReason(const parser::Name &name, Symbol &symbol,
1973     MessageFixedText &&msg1, MessageFixedText &&msg2) {
1974   Say2(name, std::move(msg1), symbol, std::move(msg2));
1975   context().SetError(symbol, msg1.isFatal());
1976 }
1977 
1978 void ScopeHandler::SayWithDecl(
1979     const parser::Name &name, Symbol &symbol, MessageFixedText &&msg) {
1980   SayWithReason(name, symbol, std::move(msg),
1981       symbol.test(Symbol::Flag::Implicit) ? "Implicit declaration of '%s'"_en_US
1982                                           : "Declaration of '%s'"_en_US);
1983 }
1984 
1985 void ScopeHandler::SayLocalMustBeVariable(
1986     const parser::Name &name, Symbol &symbol) {
1987   SayWithDecl(name, symbol,
1988       "The name '%s' must be a variable to appear"
1989       " in a locality-spec"_err_en_US);
1990 }
1991 
1992 void ScopeHandler::SayDerivedType(
1993     const SourceName &name, MessageFixedText &&msg, const Scope &type) {
1994   const Symbol &typeSymbol{DEREF(type.GetSymbol())};
1995   Say(name, std::move(msg), name, typeSymbol.name())
1996       .Attach(typeSymbol.name(), "Declaration of derived type '%s'"_en_US,
1997           typeSymbol.name());
1998 }
1999 void ScopeHandler::Say2(const SourceName &name1, MessageFixedText &&msg1,
2000     const SourceName &name2, MessageFixedText &&msg2) {
2001   Say(name1, std::move(msg1)).Attach(name2, std::move(msg2), name2);
2002 }
2003 void ScopeHandler::Say2(const SourceName &name, MessageFixedText &&msg1,
2004     Symbol &symbol, MessageFixedText &&msg2) {
2005   Say2(name, std::move(msg1), symbol.name(), std::move(msg2));
2006   context().SetError(symbol, msg1.isFatal());
2007 }
2008 void ScopeHandler::Say2(const parser::Name &name, MessageFixedText &&msg1,
2009     Symbol &symbol, MessageFixedText &&msg2) {
2010   Say2(name.source, std::move(msg1), symbol.name(), std::move(msg2));
2011   context().SetError(symbol, msg1.isFatal());
2012 }
2013 
2014 Scope &ScopeHandler::InclusiveScope() {
2015   for (auto *scope{&currScope()};; scope = &scope->parent()) {
2016     if (scope->kind() != Scope::Kind::Block && !scope->IsDerivedType()) {
2017       return *scope;
2018     }
2019   }
2020   DIE("inclusive scope not found");
2021 }
2022 
2023 Scope &ScopeHandler::NonDerivedTypeScope() {
2024   return currScope_->IsDerivedType() ? currScope_->parent() : *currScope_;
2025 }
2026 
2027 void ScopeHandler::PushScope(Scope::Kind kind, Symbol *symbol) {
2028   PushScope(currScope().MakeScope(kind, symbol));
2029 }
2030 void ScopeHandler::PushScope(Scope &scope) {
2031   currScope_ = &scope;
2032   auto kind{currScope_->kind()};
2033   if (kind != Scope::Kind::Block) {
2034     BeginScope(scope);
2035   }
2036   // The name of a module or submodule cannot be "used" in its scope,
2037   // as we read 19.3.1(2), so we allow the name to be used as a local
2038   // identifier in the module or submodule too.  Same with programs
2039   // (14.1(3)) and BLOCK DATA.
2040   if (!currScope_->IsDerivedType() && kind != Scope::Kind::Module &&
2041       kind != Scope::Kind::MainProgram && kind != Scope::Kind::BlockData) {
2042     if (auto *symbol{scope.symbol()}) {
2043       // Create a dummy symbol so we can't create another one with the same
2044       // name. It might already be there if we previously pushed the scope.
2045       if (!FindInScope(scope, symbol->name())) {
2046         auto &newSymbol{MakeSymbol(symbol->name())};
2047         if (kind == Scope::Kind::Subprogram) {
2048           // Allow for recursive references.  If this symbol is a function
2049           // without an explicit RESULT(), this new symbol will be discarded
2050           // and replaced with an object of the same name.
2051           newSymbol.set_details(HostAssocDetails{*symbol});
2052         } else {
2053           newSymbol.set_details(MiscDetails{MiscDetails::Kind::ScopeName});
2054         }
2055       }
2056     }
2057   }
2058 }
2059 void ScopeHandler::PopScope() {
2060   // Entities that are not yet classified as objects or procedures are now
2061   // assumed to be objects.
2062   // TODO: Statement functions
2063   for (auto &pair : currScope()) {
2064     ConvertToObjectEntity(*pair.second);
2065   }
2066   SetScope(currScope_->parent());
2067 }
2068 void ScopeHandler::SetScope(Scope &scope) {
2069   currScope_ = &scope;
2070   ImplicitRulesVisitor::SetScope(InclusiveScope());
2071 }
2072 
2073 Symbol *ScopeHandler::FindSymbol(const parser::Name &name) {
2074   return FindSymbol(currScope(), name);
2075 }
2076 Symbol *ScopeHandler::FindSymbol(const Scope &scope, const parser::Name &name) {
2077   if (scope.IsDerivedType()) {
2078     if (Symbol * symbol{scope.FindComponent(name.source)}) {
2079       if (!symbol->has<ProcBindingDetails>() &&
2080           !symbol->test(Symbol::Flag::ParentComp)) {
2081         return Resolve(name, symbol);
2082       }
2083     }
2084     return FindSymbol(scope.parent(), name);
2085   } else {
2086     return Resolve(name, scope.FindSymbol(name.source));
2087   }
2088 }
2089 
2090 Symbol &ScopeHandler::MakeSymbol(
2091     Scope &scope, const SourceName &name, Attrs attrs) {
2092   if (Symbol * symbol{FindInScope(scope, name)}) {
2093     symbol->attrs() |= attrs;
2094     return *symbol;
2095   } else {
2096     const auto pair{scope.try_emplace(name, attrs, UnknownDetails{})};
2097     CHECK(pair.second); // name was not found, so must be able to add
2098     return *pair.first->second;
2099   }
2100 }
2101 Symbol &ScopeHandler::MakeSymbol(const SourceName &name, Attrs attrs) {
2102   return MakeSymbol(currScope(), name, attrs);
2103 }
2104 Symbol &ScopeHandler::MakeSymbol(const parser::Name &name, Attrs attrs) {
2105   return Resolve(name, MakeSymbol(name.source, attrs));
2106 }
2107 Symbol &ScopeHandler::CopySymbol(const SourceName &name, const Symbol &symbol) {
2108   CHECK(!FindInScope(currScope(), name));
2109   return MakeSymbol(currScope(), name, symbol.attrs());
2110 }
2111 
2112 // Look for name only in scope, not in enclosing scopes.
2113 Symbol *ScopeHandler::FindInScope(
2114     const Scope &scope, const parser::Name &name) {
2115   return Resolve(name, FindInScope(scope, name.source));
2116 }
2117 Symbol *ScopeHandler::FindInScope(const Scope &scope, const SourceName &name) {
2118   if (auto it{scope.find(name)}; it != scope.end()) {
2119     return &*it->second;
2120   } else {
2121     return nullptr;
2122   }
2123 }
2124 
2125 // Find a component or type parameter by name in a derived type or its parents.
2126 Symbol *ScopeHandler::FindInTypeOrParents(
2127     const Scope &scope, const parser::Name &name) {
2128   return Resolve(name, scope.FindComponent(name.source));
2129 }
2130 Symbol *ScopeHandler::FindInTypeOrParents(const parser::Name &name) {
2131   return FindInTypeOrParents(currScope(), name);
2132 }
2133 
2134 void ScopeHandler::EraseSymbol(const parser::Name &name) {
2135   currScope().erase(name.source);
2136   name.symbol = nullptr;
2137 }
2138 
2139 static bool NeedsType(const Symbol &symbol) {
2140   return !symbol.GetType() &&
2141       std::visit(common::visitors{
2142                      [](const EntityDetails &) { return true; },
2143                      [](const ObjectEntityDetails &) { return true; },
2144                      [](const AssocEntityDetails &) { return true; },
2145                      [&](const ProcEntityDetails &p) {
2146                        return symbol.test(Symbol::Flag::Function) &&
2147                            !symbol.attrs().test(Attr::INTRINSIC) &&
2148                            !p.interface().type() && !p.interface().symbol();
2149                      },
2150                      [](const auto &) { return false; },
2151                  },
2152           symbol.details());
2153 }
2154 void ScopeHandler::ApplyImplicitRules(Symbol &symbol) {
2155   if (NeedsType(symbol)) {
2156     if (const DeclTypeSpec * type{GetImplicitType(symbol)}) {
2157       symbol.set(Symbol::Flag::Implicit);
2158       symbol.SetType(*type);
2159     } else if (symbol.has<ProcEntityDetails>() &&
2160         !symbol.attrs().test(Attr::EXTERNAL) &&
2161         context().intrinsics().IsIntrinsic(symbol.name().ToString())) {
2162       // type will be determined in expression semantics
2163       symbol.attrs().set(Attr::INTRINSIC);
2164     } else if (!context().HasError(symbol)) {
2165       Say(symbol.name(), "No explicit type declared for '%s'"_err_en_US);
2166       context().SetError(symbol);
2167     }
2168   }
2169 }
2170 const DeclTypeSpec *ScopeHandler::GetImplicitType(Symbol &symbol) {
2171   const DeclTypeSpec *type{implicitRules().GetType(symbol.name().begin()[0])};
2172   if (type) {
2173     if (const DerivedTypeSpec * derived{type->AsDerived()}) {
2174       // Resolve any forward-referenced derived type; a quick no-op else.
2175       auto &instantiatable{*const_cast<DerivedTypeSpec *>(derived)};
2176       instantiatable.Instantiate(currScope(), context());
2177     }
2178   }
2179   return type;
2180 }
2181 
2182 // Convert symbol to be a ObjectEntity or return false if it can't be.
2183 bool ScopeHandler::ConvertToObjectEntity(Symbol &symbol) {
2184   if (symbol.has<ObjectEntityDetails>()) {
2185     // nothing to do
2186   } else if (symbol.has<UnknownDetails>()) {
2187     symbol.set_details(ObjectEntityDetails{});
2188   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2189     symbol.set_details(ObjectEntityDetails{std::move(*details)});
2190   } else if (auto *useDetails{symbol.detailsIf<UseDetails>()}) {
2191     return useDetails->symbol().has<ObjectEntityDetails>();
2192   } else {
2193     return false;
2194   }
2195   return true;
2196 }
2197 // Convert symbol to be a ProcEntity or return false if it can't be.
2198 bool ScopeHandler::ConvertToProcEntity(Symbol &symbol) {
2199   if (symbol.has<ProcEntityDetails>()) {
2200     // nothing to do
2201   } else if (symbol.has<UnknownDetails>()) {
2202     symbol.set_details(ProcEntityDetails{});
2203   } else if (auto *details{symbol.detailsIf<EntityDetails>()}) {
2204     symbol.set_details(ProcEntityDetails{std::move(*details)});
2205     if (symbol.GetType() && !symbol.test(Symbol::Flag::Implicit)) {
2206       CHECK(!symbol.test(Symbol::Flag::Subroutine));
2207       symbol.set(Symbol::Flag::Function);
2208     }
2209   } else {
2210     return false;
2211   }
2212   return true;
2213 }
2214 
2215 const DeclTypeSpec &ScopeHandler::MakeNumericType(
2216     TypeCategory category, const std::optional<parser::KindSelector> &kind) {
2217   KindExpr value{GetKindParamExpr(category, kind)};
2218   if (auto known{evaluate::ToInt64(value)}) {
2219     return context().MakeNumericType(category, static_cast<int>(*known));
2220   } else {
2221     return currScope_->MakeNumericType(category, std::move(value));
2222   }
2223 }
2224 
2225 const DeclTypeSpec &ScopeHandler::MakeLogicalType(
2226     const std::optional<parser::KindSelector> &kind) {
2227   KindExpr value{GetKindParamExpr(TypeCategory::Logical, kind)};
2228   if (auto known{evaluate::ToInt64(value)}) {
2229     return context().MakeLogicalType(static_cast<int>(*known));
2230   } else {
2231     return currScope_->MakeLogicalType(std::move(value));
2232   }
2233 }
2234 
2235 void ScopeHandler::MakeExternal(Symbol &symbol) {
2236   if (!symbol.attrs().test(Attr::EXTERNAL)) {
2237     symbol.attrs().set(Attr::EXTERNAL);
2238     if (symbol.attrs().test(Attr::INTRINSIC)) { // C840
2239       Say(symbol.name(),
2240           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
2241           symbol.name());
2242     }
2243   }
2244 }
2245 
2246 // ModuleVisitor implementation
2247 
2248 bool ModuleVisitor::Pre(const parser::Only &x) {
2249   std::visit(common::visitors{
2250                  [&](const Indirection<parser::GenericSpec> &generic) {
2251                    AddUse(GenericSpecInfo{generic.value()});
2252                  },
2253                  [&](const parser::Name &name) {
2254                    Resolve(name, AddUse(name.source, name.source).use);
2255                  },
2256                  [&](const parser::Rename &rename) { Walk(rename); },
2257              },
2258       x.u);
2259   return false;
2260 }
2261 
2262 bool ModuleVisitor::Pre(const parser::Rename::Names &x) {
2263   const auto &localName{std::get<0>(x.t)};
2264   const auto &useName{std::get<1>(x.t)};
2265   SymbolRename rename{AddUse(localName.source, useName.source)};
2266   Resolve(useName, rename.use);
2267   Resolve(localName, rename.local);
2268   return false;
2269 }
2270 bool ModuleVisitor::Pre(const parser::Rename::Operators &x) {
2271   const parser::DefinedOpName &local{std::get<0>(x.t)};
2272   const parser::DefinedOpName &use{std::get<1>(x.t)};
2273   GenericSpecInfo localInfo{local};
2274   GenericSpecInfo useInfo{use};
2275   if (IsIntrinsicOperator(context(), local.v.source)) {
2276     Say(local.v,
2277         "Intrinsic operator '%s' may not be used as a defined operator"_err_en_US);
2278   } else if (IsLogicalConstant(context(), local.v.source)) {
2279     Say(local.v,
2280         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
2281   } else {
2282     SymbolRename rename{AddUse(localInfo.symbolName(), useInfo.symbolName())};
2283     useInfo.Resolve(rename.use);
2284     localInfo.Resolve(rename.local);
2285   }
2286   return false;
2287 }
2288 
2289 // Set useModuleScope_ to the Scope of the module being used.
2290 bool ModuleVisitor::Pre(const parser::UseStmt &x) {
2291   useModuleScope_ = FindModule(x.moduleName);
2292   return useModuleScope_ != nullptr;
2293 }
2294 void ModuleVisitor::Post(const parser::UseStmt &x) {
2295   if (const auto *list{std::get_if<std::list<parser::Rename>>(&x.u)}) {
2296     // Not a use-only: collect the names that were used in renames,
2297     // then add a use for each public name that was not renamed.
2298     std::set<SourceName> useNames;
2299     for (const auto &rename : *list) {
2300       std::visit(common::visitors{
2301                      [&](const parser::Rename::Names &names) {
2302                        useNames.insert(std::get<1>(names.t).source);
2303                      },
2304                      [&](const parser::Rename::Operators &ops) {
2305                        useNames.insert(std::get<1>(ops.t).v.source);
2306                      },
2307                  },
2308           rename.u);
2309     }
2310     for (const auto &[name, symbol] : *useModuleScope_) {
2311       if (symbol->attrs().test(Attr::PUBLIC) &&
2312           !symbol->detailsIf<MiscDetails>()) {
2313         if (useNames.count(name) == 0) {
2314           auto *localSymbol{FindInScope(currScope(), name)};
2315           if (!localSymbol) {
2316             localSymbol = &CopySymbol(name, *symbol);
2317           }
2318           AddUse(x.moduleName.source, *localSymbol, *symbol);
2319         }
2320       }
2321     }
2322   }
2323   useModuleScope_ = nullptr;
2324 }
2325 
2326 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2327     const SourceName &localName, const SourceName &useName) {
2328   return AddUse(localName, useName, FindInScope(*useModuleScope_, useName));
2329 }
2330 
2331 ModuleVisitor::SymbolRename ModuleVisitor::AddUse(
2332     const SourceName &localName, const SourceName &useName, Symbol *useSymbol) {
2333   if (!useModuleScope_) {
2334     return {}; // error occurred finding module
2335   }
2336   if (!useSymbol) {
2337     Say(useName,
2338         IsDefinedOperator(useName)
2339             ? "Operator '%s' not found in module '%s'"_err_en_US
2340             : "'%s' not found in module '%s'"_err_en_US,
2341         useName, useModuleScope_->GetName().value());
2342     return {};
2343   }
2344   if (useSymbol->attrs().test(Attr::PRIVATE)) {
2345     Say(useName,
2346         IsDefinedOperator(useName)
2347             ? "Operator '%s' is PRIVATE in '%s'"_err_en_US
2348             : "'%s' is PRIVATE in '%s'"_err_en_US,
2349         useName, useModuleScope_->GetName().value());
2350     return {};
2351   }
2352   auto &localSymbol{MakeSymbol(localName)};
2353   AddUse(useName, localSymbol, *useSymbol);
2354   return {&localSymbol, useSymbol};
2355 }
2356 
2357 // symbol must be either a Use or a Generic formed by merging two uses.
2358 // Convert it to a UseError with this additional location.
2359 static void ConvertToUseError(
2360     Symbol &symbol, const SourceName &location, const Scope &module) {
2361   const auto *useDetails{symbol.detailsIf<UseDetails>()};
2362   if (!useDetails) {
2363     auto &genericDetails{symbol.get<GenericDetails>()};
2364     useDetails = &genericDetails.useDetails().value();
2365   }
2366   symbol.set_details(
2367       UseErrorDetails{*useDetails}.add_occurrence(location, module));
2368 }
2369 
2370 void ModuleVisitor::AddUse(
2371     const SourceName &location, Symbol &localSymbol, const Symbol &useSymbol) {
2372   localSymbol.attrs() = useSymbol.attrs() & ~Attrs{Attr::PUBLIC, Attr::PRIVATE};
2373   localSymbol.flags() = useSymbol.flags();
2374   if (auto *useDetails{localSymbol.detailsIf<UseDetails>()}) {
2375     const Symbol &ultimate{localSymbol.GetUltimate()};
2376     if (ultimate == useSymbol.GetUltimate()) {
2377       // use-associating the same symbol again -- ok
2378     } else if (ultimate.has<GenericDetails>() &&
2379         useSymbol.has<GenericDetails>()) {
2380       // use-associating generics with the same names: merge them into a
2381       // new generic in this scope
2382       auto generic1{ultimate.get<GenericDetails>()};
2383       generic1.set_useDetails(*useDetails);
2384       // useSymbol has specific g and so does generic1
2385       auto &generic2{useSymbol.get<GenericDetails>()};
2386       if (generic1.specific() && generic2.specific() &&
2387           generic1.specific() != generic2.specific()) {
2388         Say(location,
2389             "Generic interface '%s' has ambiguous specific procedures"
2390             " from modules '%s' and '%s'"_err_en_US,
2391             localSymbol.name(), GetUsedModule(*useDetails).name(),
2392             useSymbol.owner().GetName().value());
2393       } else if (generic1.derivedType() && generic2.derivedType() &&
2394           generic1.derivedType() != generic2.derivedType()) {
2395         Say(location,
2396             "Generic interface '%s' has ambiguous derived types"
2397             " from modules '%s' and '%s'"_err_en_US,
2398             localSymbol.name(), GetUsedModule(*useDetails).name(),
2399             useSymbol.owner().GetName().value());
2400       } else {
2401         generic1.CopyFrom(generic2);
2402       }
2403       EraseSymbol(localSymbol);
2404       MakeSymbol(localSymbol.name(), ultimate.attrs(), std::move(generic1));
2405     } else {
2406       ConvertToUseError(localSymbol, location, *useModuleScope_);
2407     }
2408   } else {
2409     auto *genericDetails{localSymbol.detailsIf<GenericDetails>()};
2410     if (genericDetails && genericDetails->useDetails()) {
2411       // localSymbol came from merging two use-associated generics
2412       if (auto *useDetails{useSymbol.detailsIf<GenericDetails>()}) {
2413         genericDetails->CopyFrom(*useDetails);
2414       } else {
2415         ConvertToUseError(localSymbol, location, *useModuleScope_);
2416       }
2417     } else if (auto *details{localSymbol.detailsIf<UseErrorDetails>()}) {
2418       details->add_occurrence(location, *useModuleScope_);
2419     } else if (!localSymbol.has<UnknownDetails>()) {
2420       Say(location,
2421           "Cannot use-associate '%s'; it is already declared in this scope"_err_en_US,
2422           localSymbol.name())
2423           .Attach(localSymbol.name(), "Previous declaration of '%s'"_en_US,
2424               localSymbol.name());
2425     } else {
2426       localSymbol.set_details(UseDetails{location, useSymbol});
2427     }
2428   }
2429 }
2430 
2431 void ModuleVisitor::AddUse(const GenericSpecInfo &info) {
2432   if (useModuleScope_) {
2433     const auto &name{info.symbolName()};
2434     auto rename{
2435         AddUse(name, name, info.FindInScope(context(), *useModuleScope_))};
2436     info.Resolve(rename.use);
2437   }
2438 }
2439 
2440 bool ModuleVisitor::BeginSubmodule(
2441     const parser::Name &name, const parser::ParentIdentifier &parentId) {
2442   auto &ancestorName{std::get<parser::Name>(parentId.t)};
2443   auto &parentName{std::get<std::optional<parser::Name>>(parentId.t)};
2444   Scope *ancestor{FindModule(ancestorName)};
2445   if (!ancestor) {
2446     return false;
2447   }
2448   Scope *parentScope{parentName ? FindModule(*parentName, ancestor) : ancestor};
2449   if (!parentScope) {
2450     return false;
2451   }
2452   PushScope(*parentScope); // submodule is hosted in parent
2453   BeginModule(name, true);
2454   if (!ancestor->AddSubmodule(name.source, currScope())) {
2455     Say(name, "Module '%s' already has a submodule named '%s'"_err_en_US,
2456         ancestorName.source, name.source);
2457   }
2458   return true;
2459 }
2460 
2461 void ModuleVisitor::BeginModule(const parser::Name &name, bool isSubmodule) {
2462   auto &symbol{MakeSymbol(name, ModuleDetails{isSubmodule})};
2463   auto &details{symbol.get<ModuleDetails>()};
2464   PushScope(Scope::Kind::Module, &symbol);
2465   details.set_scope(&currScope());
2466   defaultAccess_ = Attr::PUBLIC;
2467   prevAccessStmt_ = std::nullopt;
2468 }
2469 
2470 // Find a module or submodule by name and return its scope.
2471 // If ancestor is present, look for a submodule of that ancestor module.
2472 // May have to read a .mod file to find it.
2473 // If an error occurs, report it and return nullptr.
2474 Scope *ModuleVisitor::FindModule(const parser::Name &name, Scope *ancestor) {
2475   ModFileReader reader{context()};
2476   Scope *scope{reader.Read(name.source, ancestor)};
2477   if (!scope) {
2478     return nullptr;
2479   }
2480   if (scope->kind() != Scope::Kind::Module) {
2481     Say(name, "'%s' is not a module"_err_en_US);
2482     return nullptr;
2483   }
2484   if (DoesScopeContain(scope, currScope())) { // 14.2.2(1)
2485     Say(name, "Module '%s' cannot USE itself"_err_en_US);
2486   }
2487   Resolve(name, scope->symbol());
2488   return scope;
2489 }
2490 
2491 void ModuleVisitor::ApplyDefaultAccess() {
2492   for (auto &pair : currScope()) {
2493     Symbol &symbol = *pair.second;
2494     if (!symbol.attrs().HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
2495       symbol.attrs().set(defaultAccess_);
2496     }
2497   }
2498 }
2499 
2500 // InterfaceVistor implementation
2501 
2502 bool InterfaceVisitor::Pre(const parser::InterfaceStmt &x) {
2503   bool isAbstract{std::holds_alternative<parser::Abstract>(x.u)};
2504   genericInfo_.emplace(/*isInterface*/ true, isAbstract);
2505   return BeginAttrs();
2506 }
2507 
2508 void InterfaceVisitor::Post(const parser::InterfaceStmt &) { EndAttrs(); }
2509 
2510 void InterfaceVisitor::Post(const parser::EndInterfaceStmt &) {
2511   genericInfo_.pop();
2512 }
2513 
2514 // Create a symbol in genericSymbol_ for this GenericSpec.
2515 bool InterfaceVisitor::Pre(const parser::GenericSpec &x) {
2516   if (auto *symbol{GenericSpecInfo{x}.FindInScope(context(), currScope())}) {
2517     SetGenericSymbol(*symbol);
2518   }
2519   return false;
2520 }
2521 
2522 bool InterfaceVisitor::Pre(const parser::ProcedureStmt &x) {
2523   if (!isGeneric()) {
2524     Say("A PROCEDURE statement is only allowed in a generic interface block"_err_en_US);
2525     return false;
2526   }
2527   auto kind{std::get<parser::ProcedureStmt::Kind>(x.t)};
2528   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2529   AddSpecificProcs(names, kind);
2530   return false;
2531 }
2532 
2533 bool InterfaceVisitor::Pre(const parser::GenericStmt &) {
2534   genericInfo_.emplace(/*isInterface*/ false);
2535   return true;
2536 }
2537 void InterfaceVisitor::Post(const parser::GenericStmt &x) {
2538   if (auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)}) {
2539     GetGenericInfo().symbol->attrs().set(AccessSpecToAttr(*accessSpec));
2540   }
2541   const auto &names{std::get<std::list<parser::Name>>(x.t)};
2542   AddSpecificProcs(names, ProcedureKind::Procedure);
2543   genericInfo_.pop();
2544 }
2545 
2546 bool InterfaceVisitor::inInterfaceBlock() const {
2547   return !genericInfo_.empty() && GetGenericInfo().isInterface;
2548 }
2549 bool InterfaceVisitor::isGeneric() const {
2550   return !genericInfo_.empty() && GetGenericInfo().symbol;
2551 }
2552 bool InterfaceVisitor::isAbstract() const {
2553   return !genericInfo_.empty() && GetGenericInfo().isAbstract;
2554 }
2555 GenericDetails &InterfaceVisitor::GetGenericDetails() {
2556   return GetGenericInfo().symbol->get<GenericDetails>();
2557 }
2558 
2559 void InterfaceVisitor::AddSpecificProcs(
2560     const std::list<parser::Name> &names, ProcedureKind kind) {
2561   for (const auto &name : names) {
2562     specificProcs_.emplace(
2563         GetGenericInfo().symbol, std::make_pair(&name, kind));
2564   }
2565 }
2566 
2567 // By now we should have seen all specific procedures referenced by name in
2568 // this generic interface. Resolve those names to symbols.
2569 void InterfaceVisitor::ResolveSpecificsInGeneric(Symbol &generic) {
2570   auto &details{generic.get<GenericDetails>()};
2571   std::set<SourceName> namesSeen; // to check for duplicate names
2572   for (const Symbol &symbol : details.specificProcs()) {
2573     namesSeen.insert(symbol.name());
2574   }
2575   auto range{specificProcs_.equal_range(&generic)};
2576   for (auto it{range.first}; it != range.second; ++it) {
2577     auto *name{it->second.first};
2578     auto kind{it->second.second};
2579     const auto *symbol{FindSymbol(*name)};
2580     if (!symbol) {
2581       Say(*name, "Procedure '%s' not found"_err_en_US);
2582       continue;
2583     }
2584     symbol = &symbol->GetUltimate();
2585     if (symbol == &generic) {
2586       if (auto *specific{generic.get<GenericDetails>().specific()}) {
2587         symbol = specific;
2588       }
2589     }
2590     if (!symbol->has<SubprogramDetails>() &&
2591         !symbol->has<SubprogramNameDetails>()) {
2592       Say(*name, "'%s' is not a subprogram"_err_en_US);
2593       continue;
2594     }
2595     if (kind == ProcedureKind::ModuleProcedure) {
2596       if (const auto *nd{symbol->detailsIf<SubprogramNameDetails>()}) {
2597         if (nd->kind() != SubprogramKind::Module) {
2598           Say(*name, "'%s' is not a module procedure"_err_en_US);
2599         }
2600       } else {
2601         // USE-associated procedure
2602         const auto *sd{symbol->detailsIf<SubprogramDetails>()};
2603         CHECK(sd);
2604         if (symbol->owner().kind() != Scope::Kind::Module ||
2605             sd->isInterface()) {
2606           Say(*name, "'%s' is not a module procedure"_err_en_US);
2607         }
2608       }
2609     }
2610     if (!namesSeen.insert(name->source).second) {
2611       Say(*name,
2612           details.kind().IsDefinedOperator()
2613               ? "Procedure '%s' is already specified in generic operator '%s'"_err_en_US
2614               : "Procedure '%s' is already specified in generic '%s'"_err_en_US,
2615           name->source, generic.name());
2616       continue;
2617     }
2618     details.AddSpecificProc(*symbol, name->source);
2619   }
2620   specificProcs_.erase(range.first, range.second);
2621 }
2622 
2623 // Check that the specific procedures are all functions or all subroutines.
2624 // If there is a derived type with the same name they must be functions.
2625 // Set the corresponding flag on generic.
2626 void InterfaceVisitor::CheckGenericProcedures(Symbol &generic) {
2627   ResolveSpecificsInGeneric(generic);
2628   auto &details{generic.get<GenericDetails>()};
2629   if (auto *proc{details.CheckSpecific()}) {
2630     auto msg{
2631         "'%s' may not be the name of both a generic interface and a"
2632         " procedure unless it is a specific procedure of the generic"_err_en_US};
2633     if (proc->name().begin() > generic.name().begin()) {
2634       Say(proc->name(), std::move(msg));
2635     } else {
2636       Say(generic.name(), std::move(msg));
2637     }
2638   }
2639   auto &specifics{details.specificProcs()};
2640   if (specifics.empty()) {
2641     if (details.derivedType()) {
2642       generic.set(Symbol::Flag::Function);
2643     }
2644     return;
2645   }
2646   const Symbol &firstSpecific{specifics.front()};
2647   bool isFunction{firstSpecific.test(Symbol::Flag::Function)};
2648   for (const Symbol &specific : specifics) {
2649     if (isFunction != specific.test(Symbol::Flag::Function)) { // C1514
2650       auto &msg{Say(generic.name(),
2651           "Generic interface '%s' has both a function and a subroutine"_err_en_US)};
2652       if (isFunction) {
2653         msg.Attach(firstSpecific.name(), "Function declaration"_en_US);
2654         msg.Attach(specific.name(), "Subroutine declaration"_en_US);
2655       } else {
2656         msg.Attach(firstSpecific.name(), "Subroutine declaration"_en_US);
2657         msg.Attach(specific.name(), "Function declaration"_en_US);
2658       }
2659     }
2660   }
2661   if (!isFunction && details.derivedType()) {
2662     SayDerivedType(generic.name(),
2663         "Generic interface '%s' may only contain functions due to derived type"
2664         " with same name"_err_en_US,
2665         *details.derivedType()->scope());
2666   }
2667   generic.set(isFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
2668 }
2669 
2670 // SubprogramVisitor implementation
2671 
2672 // Return false if it is actually an assignment statement.
2673 bool SubprogramVisitor::HandleStmtFunction(const parser::StmtFunctionStmt &x) {
2674   const auto &name{std::get<parser::Name>(x.t)};
2675   const DeclTypeSpec *resultType{nullptr};
2676   // Look up name: provides return type or tells us if it's an array
2677   if (auto *symbol{FindSymbol(name)}) {
2678     auto *details{symbol->detailsIf<EntityDetails>()};
2679     if (!details) {
2680       badStmtFuncFound_ = true;
2681       return false;
2682     }
2683     // TODO: check that attrs are compatible with stmt func
2684     resultType = details->type();
2685     symbol->details() = UnknownDetails{}; // will be replaced below
2686   }
2687   if (badStmtFuncFound_) {
2688     Say(name, "'%s' has not been declared as an array"_err_en_US);
2689     return true;
2690   }
2691   auto &symbol{PushSubprogramScope(name, Symbol::Flag::Function)};
2692   EraseSymbol(symbol); // removes symbol added by PushSubprogramScope
2693   auto &details{symbol.get<SubprogramDetails>()};
2694   for (const auto &dummyName : std::get<std::list<parser::Name>>(x.t)) {
2695     ObjectEntityDetails dummyDetails{true};
2696     if (auto *dummySymbol{FindInScope(currScope().parent(), dummyName)}) {
2697       if (auto *d{dummySymbol->detailsIf<EntityDetails>()}) {
2698         if (d->type()) {
2699           dummyDetails.set_type(*d->type());
2700         }
2701       }
2702     }
2703     Symbol &dummy{MakeSymbol(dummyName, std::move(dummyDetails))};
2704     ApplyImplicitRules(dummy);
2705     details.add_dummyArg(dummy);
2706   }
2707   ObjectEntityDetails resultDetails;
2708   if (resultType) {
2709     resultDetails.set_type(*resultType);
2710   }
2711   resultDetails.set_funcResult(true);
2712   Symbol &result{MakeSymbol(name, std::move(resultDetails))};
2713   ApplyImplicitRules(result);
2714   details.set_result(result);
2715   const auto &parsedExpr{std::get<parser::Scalar<parser::Expr>>(x.t)};
2716   Walk(parsedExpr);
2717   if (auto expr{AnalyzeExpr(context(), parsedExpr)}) {
2718     details.set_stmtFunction(std::move(*expr));
2719   } else {
2720     context().SetError(symbol);
2721   }
2722   PopScope();
2723   return true;
2724 }
2725 
2726 bool SubprogramVisitor::Pre(const parser::Suffix &suffix) {
2727   if (suffix.resultName) {
2728     funcInfo_.resultName = &suffix.resultName.value();
2729   }
2730   return true;
2731 }
2732 
2733 bool SubprogramVisitor::Pre(const parser::PrefixSpec &x) {
2734   // Save this to process after UseStmt and ImplicitPart
2735   if (const auto *parsedType{std::get_if<parser::DeclarationTypeSpec>(&x.u)}) {
2736     if (funcInfo_.parsedType) { // C1543
2737       Say(currStmtSource().value(),
2738           "FUNCTION prefix cannot specify the type more than once"_err_en_US);
2739       return false;
2740     } else {
2741       funcInfo_.parsedType = parsedType;
2742       funcInfo_.source = currStmtSource();
2743       return false;
2744     }
2745   } else {
2746     return true;
2747   }
2748 }
2749 
2750 void SubprogramVisitor::Post(const parser::ImplicitPart &) {
2751   // If the function has a type in the prefix, process it now
2752   if (funcInfo_.parsedType) {
2753     messageHandler().set_currStmtSource(funcInfo_.source);
2754     if (const auto *type{ProcessTypeSpec(*funcInfo_.parsedType, true)}) {
2755       funcInfo_.resultSymbol->SetType(*type);
2756     }
2757   }
2758   funcInfo_ = {};
2759 }
2760 
2761 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Subroutine &x) {
2762   const auto &name{std::get<parser::Name>(
2763       std::get<parser::Statement<parser::SubroutineStmt>>(x.t).statement.t)};
2764   return BeginSubprogram(name, Symbol::Flag::Subroutine);
2765 }
2766 void SubprogramVisitor::Post(const parser::InterfaceBody::Subroutine &) {
2767   EndSubprogram();
2768 }
2769 bool SubprogramVisitor::Pre(const parser::InterfaceBody::Function &x) {
2770   const auto &name{std::get<parser::Name>(
2771       std::get<parser::Statement<parser::FunctionStmt>>(x.t).statement.t)};
2772   return BeginSubprogram(name, Symbol::Flag::Function);
2773 }
2774 void SubprogramVisitor::Post(const parser::InterfaceBody::Function &) {
2775   EndSubprogram();
2776 }
2777 
2778 bool SubprogramVisitor::Pre(const parser::SubroutineStmt &) {
2779   return BeginAttrs();
2780 }
2781 bool SubprogramVisitor::Pre(const parser::FunctionStmt &) {
2782   return BeginAttrs();
2783 }
2784 bool SubprogramVisitor::Pre(const parser::EntryStmt &) { return BeginAttrs(); }
2785 
2786 void SubprogramVisitor::Post(const parser::SubroutineStmt &stmt) {
2787   const auto &name{std::get<parser::Name>(stmt.t)};
2788   auto &details{PostSubprogramStmt(name)};
2789   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
2790     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
2791       Symbol &dummy{MakeSymbol(*dummyName, EntityDetails(true))};
2792       details.add_dummyArg(dummy);
2793     } else {
2794       details.add_alternateReturn();
2795     }
2796   }
2797 }
2798 
2799 void SubprogramVisitor::Post(const parser::FunctionStmt &stmt) {
2800   const auto &name{std::get<parser::Name>(stmt.t)};
2801   auto &details{PostSubprogramStmt(name)};
2802   for (const auto &dummyName : std::get<std::list<parser::Name>>(stmt.t)) {
2803     Symbol &dummy{MakeSymbol(dummyName, EntityDetails(true))};
2804     details.add_dummyArg(dummy);
2805   }
2806   const parser::Name *funcResultName;
2807   if (funcInfo_.resultName && funcInfo_.resultName->source != name.source) {
2808     // Note that RESULT is ignored if it has the same name as the function.
2809     funcResultName = funcInfo_.resultName;
2810   } else {
2811     EraseSymbol(name); // was added by PushSubprogramScope
2812     funcResultName = &name;
2813   }
2814   // add function result to function scope
2815   EntityDetails funcResultDetails;
2816   funcResultDetails.set_funcResult(true);
2817   funcInfo_.resultSymbol =
2818       &MakeSymbol(*funcResultName, std::move(funcResultDetails));
2819   details.set_result(*funcInfo_.resultSymbol);
2820 
2821   // C1560.
2822   if (funcInfo_.resultName && funcInfo_.resultName->source == name.source) {
2823     Say(funcInfo_.resultName->source,
2824         "The function name should not appear in RESULT, references to '%s' "
2825         "inside"
2826         " the function will be considered as references to the result only"_en_US,
2827         name.source);
2828     // RESULT name was ignored above, the only side effect from doing so will be
2829     // the inability to make recursive calls. The related parser::Name is still
2830     // resolved to the created function result symbol because every parser::Name
2831     // should be resolved to avoid internal errors.
2832     Resolve(*funcInfo_.resultName, funcInfo_.resultSymbol);
2833   }
2834   name.symbol = currScope().symbol(); // must not be function result symbol
2835   // Clear the RESULT() name now in case an ENTRY statement in the implicit-part
2836   // has a RESULT() suffix.
2837   funcInfo_.resultName = nullptr;
2838 }
2839 
2840 SubprogramDetails &SubprogramVisitor::PostSubprogramStmt(
2841     const parser::Name &name) {
2842   Symbol &symbol{*currScope().symbol()};
2843   CHECK(name.source == symbol.name());
2844   SetBindNameOn(symbol);
2845   symbol.attrs() |= EndAttrs();
2846   if (symbol.attrs().test(Attr::MODULE)) {
2847     symbol.attrs().set(Attr::EXTERNAL, false);
2848   }
2849   return symbol.get<SubprogramDetails>();
2850 }
2851 
2852 void SubprogramVisitor::Post(const parser::EntryStmt &stmt) {
2853   auto attrs{EndAttrs()}; // needs to be called even if early return
2854   Scope &inclusiveScope{InclusiveScope()};
2855   const Symbol *subprogram{inclusiveScope.symbol()};
2856   if (!subprogram) {
2857     CHECK(context().AnyFatalError());
2858     return;
2859   }
2860   const auto &name{std::get<parser::Name>(stmt.t)};
2861   const auto *parentDetails{subprogram->detailsIf<SubprogramDetails>()};
2862   bool inFunction{parentDetails && parentDetails->isFunction()};
2863   const parser::Name *resultName{funcInfo_.resultName};
2864   if (resultName) { // RESULT(result) is present
2865     funcInfo_.resultName = nullptr;
2866     if (!inFunction) {
2867       Say2(resultName->source,
2868           "RESULT(%s) may appear only in a function"_err_en_US,
2869           subprogram->name(), "Containing subprogram"_en_US);
2870     } else if (resultName->source == subprogram->name()) { // C1574
2871       Say2(resultName->source,
2872           "RESULT(%s) may not have the same name as the function"_err_en_US,
2873           subprogram->name(), "Containing function"_en_US);
2874     } else if (const Symbol *
2875         symbol{FindSymbol(inclusiveScope.parent(), *resultName)}) { // C1574
2876       if (const auto *details{symbol->detailsIf<SubprogramDetails>()}) {
2877         if (details->entryScope() == &inclusiveScope) {
2878           Say2(resultName->source,
2879               "RESULT(%s) may not have the same name as an ENTRY in the function"_err_en_US,
2880               symbol->name(), "Conflicting ENTRY"_en_US);
2881         }
2882       }
2883     }
2884     if (Symbol * symbol{FindSymbol(name)}) { // C1570
2885       // When RESULT() appears, ENTRY name can't have been already declared
2886       if (inclusiveScope.Contains(symbol->owner())) {
2887         Say2(name,
2888             "ENTRY name '%s' may not be declared when RESULT() is present"_err_en_US,
2889             *symbol, "Previous declaration of '%s'"_en_US);
2890       }
2891     }
2892     if (resultName->source == name.source) {
2893       // ignore RESULT() hereafter when it's the same name as the ENTRY
2894       resultName = nullptr;
2895     }
2896   }
2897   SubprogramDetails entryDetails;
2898   entryDetails.set_entryScope(inclusiveScope);
2899   if (inFunction) {
2900     // Create the entity to hold the function result, if necessary.
2901     Symbol *resultSymbol{nullptr};
2902     auto &effectiveResultName{*(resultName ? resultName : &name)};
2903     resultSymbol = FindInScope(currScope(), effectiveResultName);
2904     if (resultSymbol) { // C1574
2905       std::visit(
2906           common::visitors{[](EntityDetails &x) { x.set_funcResult(true); },
2907               [](ObjectEntityDetails &x) { x.set_funcResult(true); },
2908               [](ProcEntityDetails &x) { x.set_funcResult(true); },
2909               [&](const auto &) {
2910                 Say2(effectiveResultName.source,
2911                     "'%s' was previously declared as an item that may not be used as a function result"_err_en_US,
2912                     resultSymbol->name(), "Previous declaration of '%s'"_en_US);
2913               }},
2914           resultSymbol->details());
2915     } else if (inExecutionPart_) {
2916       ObjectEntityDetails entity;
2917       entity.set_funcResult(true);
2918       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
2919       ApplyImplicitRules(*resultSymbol);
2920     } else {
2921       EntityDetails entity;
2922       entity.set_funcResult(true);
2923       resultSymbol = &MakeSymbol(effectiveResultName, std::move(entity));
2924     }
2925     if (!resultName) {
2926       name.symbol = nullptr; // symbol will be used for entry point below
2927     }
2928     entryDetails.set_result(*resultSymbol);
2929   }
2930 
2931   for (const auto &dummyArg : std::get<std::list<parser::DummyArg>>(stmt.t)) {
2932     if (const auto *dummyName{std::get_if<parser::Name>(&dummyArg.u)}) {
2933       Symbol *dummy{FindSymbol(*dummyName)};
2934       if (dummy) {
2935         std::visit(
2936             common::visitors{[](EntityDetails &x) { x.set_isDummy(); },
2937                 [](ObjectEntityDetails &x) { x.set_isDummy(); },
2938                 [](ProcEntityDetails &x) { x.set_isDummy(); },
2939                 [&](const auto &) {
2940                   Say2(dummyName->source,
2941                       "ENTRY dummy argument '%s' is previously declared as an item that may not be used as a dummy argument"_err_en_US,
2942                       dummy->name(), "Previous declaration of '%s'"_en_US);
2943                 }},
2944             dummy->details());
2945       } else {
2946         dummy = &MakeSymbol(*dummyName, EntityDetails(true));
2947       }
2948       entryDetails.add_dummyArg(*dummy);
2949     } else {
2950       if (inFunction) { // C1573
2951         Say(name,
2952             "ENTRY in a function may not have an alternate return dummy argument"_err_en_US);
2953         break;
2954       }
2955       entryDetails.add_alternateReturn();
2956     }
2957   }
2958 
2959   Symbol::Flag subpFlag{
2960       inFunction ? Symbol::Flag::Function : Symbol::Flag::Subroutine};
2961   CheckExtantExternal(name, subpFlag);
2962   Scope &outer{inclusiveScope.parent()}; // global or module scope
2963   if (Symbol * extant{FindSymbol(outer, name)}) {
2964     if (extant->has<ProcEntityDetails>()) {
2965       if (!extant->test(subpFlag)) {
2966         Say2(name,
2967             subpFlag == Symbol::Flag::Function
2968                 ? "'%s' was previously called as a subroutine"_err_en_US
2969                 : "'%s' was previously called as a function"_err_en_US,
2970             *extant, "Previous call of '%s'"_en_US);
2971       }
2972       if (extant->attrs().test(Attr::PRIVATE)) {
2973         attrs.set(Attr::PRIVATE);
2974       }
2975       outer.erase(extant->name());
2976     } else {
2977       if (outer.IsGlobal()) {
2978         Say2(name, "'%s' is already defined as a global identifier"_err_en_US,
2979             *extant, "Previous definition of '%s'"_en_US);
2980       } else {
2981         SayAlreadyDeclared(name, *extant);
2982       }
2983       return;
2984     }
2985   }
2986   if (outer.IsModule() && !attrs.test(Attr::PRIVATE)) {
2987     attrs.set(Attr::PUBLIC);
2988   }
2989   Symbol &entrySymbol{MakeSymbol(outer, name.source, attrs)};
2990   entrySymbol.set_details(std::move(entryDetails));
2991   if (outer.IsGlobal()) {
2992     MakeExternal(entrySymbol);
2993   }
2994   SetBindNameOn(entrySymbol);
2995   entrySymbol.set(subpFlag);
2996   Resolve(name, entrySymbol);
2997 }
2998 
2999 // A subprogram declared with MODULE PROCEDURE
3000 bool SubprogramVisitor::BeginMpSubprogram(const parser::Name &name) {
3001   auto *symbol{FindSymbol(name)};
3002   if (symbol && symbol->has<SubprogramNameDetails>()) {
3003     symbol = FindSymbol(currScope().parent(), name);
3004   }
3005   if (!IsSeparateModuleProcedureInterface(symbol)) {
3006     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3007     return false;
3008   }
3009   if (symbol->owner() == currScope()) {
3010     PushScope(Scope::Kind::Subprogram, symbol);
3011   } else {
3012     Symbol &newSymbol{MakeSymbol(name, SubprogramDetails{})};
3013     PushScope(Scope::Kind::Subprogram, &newSymbol);
3014     const auto &details{symbol->get<SubprogramDetails>()};
3015     auto &newDetails{newSymbol.get<SubprogramDetails>()};
3016     for (const Symbol *dummyArg : details.dummyArgs()) {
3017       if (!dummyArg) {
3018         newDetails.add_alternateReturn();
3019       } else if (Symbol * copy{currScope().CopySymbol(*dummyArg)}) {
3020         newDetails.add_dummyArg(*copy);
3021       }
3022     }
3023     if (details.isFunction()) {
3024       currScope().erase(symbol->name());
3025       newDetails.set_result(*currScope().CopySymbol(details.result()));
3026     }
3027   }
3028   return true;
3029 }
3030 
3031 // A subprogram declared with SUBROUTINE or FUNCTION
3032 bool SubprogramVisitor::BeginSubprogram(
3033     const parser::Name &name, Symbol::Flag subpFlag, bool hasModulePrefix) {
3034   if (hasModulePrefix && !inInterfaceBlock() &&
3035       !IsSeparateModuleProcedureInterface(
3036           FindSymbol(currScope().parent(), name))) {
3037     Say(name, "'%s' was not declared a separate module procedure"_err_en_US);
3038     return false;
3039   }
3040   PushSubprogramScope(name, subpFlag);
3041   return true;
3042 }
3043 
3044 void SubprogramVisitor::EndSubprogram() { PopScope(); }
3045 
3046 void SubprogramVisitor::CheckExtantExternal(
3047     const parser::Name &name, Symbol::Flag subpFlag) {
3048   if (auto *prev{FindSymbol(name)}) {
3049     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3050       // this subprogram was previously called, now being declared
3051       if (!prev->test(subpFlag)) {
3052         Say2(name,
3053             subpFlag == Symbol::Flag::Function
3054                 ? "'%s' was previously called as a subroutine"_err_en_US
3055                 : "'%s' was previously called as a function"_err_en_US,
3056             *prev, "Previous call of '%s'"_en_US);
3057       }
3058       EraseSymbol(name);
3059     }
3060   }
3061 }
3062 
3063 Symbol &SubprogramVisitor::PushSubprogramScope(
3064     const parser::Name &name, Symbol::Flag subpFlag) {
3065   auto *symbol{GetSpecificFromGeneric(name)};
3066   if (!symbol) {
3067     CheckExtantExternal(name, subpFlag);
3068     symbol = &MakeSymbol(name, SubprogramDetails{});
3069   }
3070   symbol->set(subpFlag);
3071   PushScope(Scope::Kind::Subprogram, symbol);
3072   auto &details{symbol->get<SubprogramDetails>()};
3073   if (inInterfaceBlock()) {
3074     details.set_isInterface();
3075     if (!isAbstract()) {
3076       MakeExternal(*symbol);
3077     }
3078     if (isGeneric()) {
3079       GetGenericDetails().AddSpecificProc(*symbol, name.source);
3080     }
3081     implicitRules().set_inheritFromParent(false);
3082   }
3083   FindSymbol(name)->set(subpFlag); // PushScope() created symbol
3084   return *symbol;
3085 }
3086 
3087 void SubprogramVisitor::PushBlockDataScope(const parser::Name &name) {
3088   if (auto *prev{FindSymbol(name)}) {
3089     if (prev->attrs().test(Attr::EXTERNAL) && prev->has<ProcEntityDetails>()) {
3090       if (prev->test(Symbol::Flag::Subroutine) ||
3091           prev->test(Symbol::Flag::Function)) {
3092         Say2(name, "BLOCK DATA '%s' has been called"_err_en_US, *prev,
3093             "Previous call of '%s'"_en_US);
3094       }
3095       EraseSymbol(name);
3096     }
3097   }
3098   if (name.source.empty()) {
3099     // Don't let unnamed BLOCK DATA conflict with unnamed PROGRAM
3100     PushScope(Scope::Kind::BlockData, nullptr);
3101   } else {
3102     PushScope(Scope::Kind::BlockData, &MakeSymbol(name, SubprogramDetails{}));
3103   }
3104 }
3105 
3106 // If name is a generic, return specific subprogram with the same name.
3107 Symbol *SubprogramVisitor::GetSpecificFromGeneric(const parser::Name &name) {
3108   if (auto *symbol{FindSymbol(name)}) {
3109     if (auto *details{symbol->detailsIf<GenericDetails>()}) {
3110       // found generic, want subprogram
3111       auto *specific{details->specific()};
3112       if (!specific) {
3113         specific =
3114             &currScope().MakeSymbol(name.source, Attrs{}, SubprogramDetails{});
3115         details->set_specific(Resolve(name, *specific));
3116       } else if (isGeneric()) {
3117         SayAlreadyDeclared(name, *specific);
3118       } else if (!specific->has<SubprogramDetails>()) {
3119         specific->set_details(SubprogramDetails{});
3120       }
3121       return specific;
3122     }
3123   }
3124   return nullptr;
3125 }
3126 
3127 // DeclarationVisitor implementation
3128 
3129 bool DeclarationVisitor::BeginDecl() {
3130   BeginDeclTypeSpec();
3131   BeginArraySpec();
3132   return BeginAttrs();
3133 }
3134 void DeclarationVisitor::EndDecl() {
3135   EndDeclTypeSpec();
3136   EndArraySpec();
3137   EndAttrs();
3138 }
3139 
3140 bool DeclarationVisitor::CheckUseError(const parser::Name &name) {
3141   const auto *details{name.symbol->detailsIf<UseErrorDetails>()};
3142   if (!details) {
3143     return false;
3144   }
3145   Message &msg{Say(name, "Reference to '%s' is ambiguous"_err_en_US)};
3146   for (const auto &[location, module] : details->occurrences()) {
3147     msg.Attach(location, "'%s' was use-associated from module '%s'"_en_US,
3148         name.source, module->GetName().value());
3149   }
3150   return true;
3151 }
3152 
3153 // Report error if accessibility of symbol doesn't match isPrivate.
3154 void DeclarationVisitor::CheckAccessibility(
3155     const SourceName &name, bool isPrivate, Symbol &symbol) {
3156   if (symbol.attrs().test(Attr::PRIVATE) != isPrivate) {
3157     Say2(name,
3158         "'%s' does not have the same accessibility as its previous declaration"_err_en_US,
3159         symbol, "Previous declaration of '%s'"_en_US);
3160   }
3161 }
3162 
3163 void DeclarationVisitor::Post(const parser::TypeDeclarationStmt &) {
3164   if (!GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE})) { // C702
3165     if (const auto *typeSpec{GetDeclTypeSpec()}) {
3166       if (typeSpec->category() == DeclTypeSpec::Character) {
3167         if (typeSpec->characterTypeSpec().length().isDeferred()) {
3168           Say("The type parameter LEN cannot be deferred without"
3169               " the POINTER or ALLOCATABLE attribute"_err_en_US);
3170         }
3171       } else if (const DerivedTypeSpec * derivedSpec{typeSpec->AsDerived()}) {
3172         for (const auto &pair : derivedSpec->parameters()) {
3173           if (pair.second.isDeferred()) {
3174             Say(currStmtSource().value(),
3175                 "The value of type parameter '%s' cannot be deferred"
3176                 " without the POINTER or ALLOCATABLE attribute"_err_en_US,
3177                 pair.first);
3178           }
3179         }
3180       }
3181     }
3182   }
3183   EndDecl();
3184 }
3185 
3186 void DeclarationVisitor::Post(const parser::DimensionStmt::Declaration &x) {
3187   const auto &name{std::get<parser::Name>(x.t)};
3188   DeclareObjectEntity(name, Attrs{});
3189 }
3190 void DeclarationVisitor::Post(const parser::CodimensionDecl &x) {
3191   const auto &name{std::get<parser::Name>(x.t)};
3192   DeclareObjectEntity(name, Attrs{});
3193 }
3194 
3195 bool DeclarationVisitor::Pre(const parser::Initialization &) {
3196   // Defer inspection of initializers to Initialization() so that the
3197   // symbol being initialized will be available within the initialization
3198   // expression.
3199   return false;
3200 }
3201 
3202 void DeclarationVisitor::Post(const parser::EntityDecl &x) {
3203   // TODO: may be under StructureStmt
3204   const auto &name{std::get<parser::ObjectName>(x.t)};
3205   Attrs attrs{attrs_ ? HandleSaveName(name.source, *attrs_) : Attrs{}};
3206   Symbol &symbol{DeclareUnknownEntity(name, attrs)};
3207   symbol.ReplaceName(name.source);
3208   if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3209     if (ConvertToObjectEntity(symbol)) {
3210       Initialization(name, *init, false);
3211     }
3212   } else if (attrs.test(Attr::PARAMETER)) { // C882, C883
3213     Say(name, "Missing initialization for parameter '%s'"_err_en_US);
3214   }
3215 }
3216 
3217 void DeclarationVisitor::Post(const parser::PointerDecl &x) {
3218   const auto &name{std::get<parser::Name>(x.t)};
3219   Symbol &symbol{DeclareUnknownEntity(name, Attrs{Attr::POINTER})};
3220   symbol.ReplaceName(name.source);
3221 }
3222 
3223 bool DeclarationVisitor::Pre(const parser::BindEntity &x) {
3224   auto kind{std::get<parser::BindEntity::Kind>(x.t)};
3225   auto &name{std::get<parser::Name>(x.t)};
3226   Symbol *symbol;
3227   if (kind == parser::BindEntity::Kind::Object) {
3228     symbol = &HandleAttributeStmt(Attr::BIND_C, name);
3229   } else {
3230     symbol = &MakeCommonBlockSymbol(name);
3231     symbol->attrs().set(Attr::BIND_C);
3232   }
3233   SetBindNameOn(*symbol);
3234   return false;
3235 }
3236 bool DeclarationVisitor::Pre(const parser::NamedConstantDef &x) {
3237   auto &name{std::get<parser::NamedConstant>(x.t).v};
3238   auto &symbol{HandleAttributeStmt(Attr::PARAMETER, name)};
3239   if (!ConvertToObjectEntity(symbol) ||
3240       symbol.test(Symbol::Flag::CrayPointer) ||
3241       symbol.test(Symbol::Flag::CrayPointee)) {
3242     SayWithDecl(
3243         name, symbol, "PARAMETER attribute not allowed on '%s'"_err_en_US);
3244     return false;
3245   }
3246   const auto &expr{std::get<parser::ConstantExpr>(x.t)};
3247   ApplyImplicitRules(symbol);
3248   Walk(expr);
3249   if (auto converted{
3250           EvaluateConvertedExpr(symbol, expr, expr.thing.value().source)}) {
3251     symbol.get<ObjectEntityDetails>().set_init(std::move(*converted));
3252   }
3253   return false;
3254 }
3255 bool DeclarationVisitor::Pre(const parser::NamedConstant &x) {
3256   const parser::Name &name{x.v};
3257   if (!FindSymbol(name)) {
3258     Say(name, "Named constant '%s' not found"_err_en_US);
3259   } else {
3260     CheckUseError(name);
3261   }
3262   return false;
3263 }
3264 
3265 bool DeclarationVisitor::Pre(const parser::Enumerator &enumerator) {
3266   const parser::Name &name{std::get<parser::NamedConstant>(enumerator.t).v};
3267   Symbol *symbol{FindSymbol(name)};
3268   if (symbol) {
3269     // Contrary to named constants appearing in a PARAMETER statement,
3270     // enumerator names should not have their type, dimension or any other
3271     // attributes defined before they are declared in the enumerator statement.
3272     // This is not explicitly forbidden by the standard, but they are scalars
3273     // which type is left for the compiler to chose, so do not let users try to
3274     // tamper with that.
3275     SayAlreadyDeclared(name, *symbol);
3276     symbol = nullptr;
3277   } else {
3278     // Enumerators are treated as PARAMETER (section 7.6 paragraph (4))
3279     symbol = &MakeSymbol(name, Attrs{Attr::PARAMETER}, ObjectEntityDetails{});
3280     symbol->SetType(context().MakeNumericType(
3281         TypeCategory::Integer, evaluate::CInteger::kind));
3282   }
3283 
3284   if (auto &init{std::get<std::optional<parser::ScalarIntConstantExpr>>(
3285           enumerator.t)}) {
3286     Walk(*init); // Resolve names in expression before evaluation.
3287     MaybeIntExpr expr{EvaluateIntExpr(*init)};
3288     if (auto value{evaluate::ToInt64(expr)}) {
3289       // Cast all init expressions to C_INT so that they can then be
3290       // safely incremented (see 7.6 Note 2).
3291       enumerationState_.value = static_cast<int>(*value);
3292     } else {
3293       Say(name,
3294           "Enumerator value could not be computed "
3295           "from the given expression"_err_en_US);
3296       // Prevent resolution of next enumerators value
3297       enumerationState_.value = std::nullopt;
3298     }
3299   }
3300 
3301   if (symbol) {
3302     if (enumerationState_.value) {
3303       symbol->get<ObjectEntityDetails>().set_init(SomeExpr{
3304           evaluate::Expr<evaluate::CInteger>{*enumerationState_.value}});
3305     } else {
3306       context().SetError(*symbol);
3307     }
3308   }
3309 
3310   if (enumerationState_.value) {
3311     (*enumerationState_.value)++;
3312   }
3313   return false;
3314 }
3315 
3316 void DeclarationVisitor::Post(const parser::EnumDef &) {
3317   enumerationState_ = EnumeratorState{};
3318 }
3319 
3320 bool DeclarationVisitor::Pre(const parser::AccessSpec &x) {
3321   Attr attr{AccessSpecToAttr(x)};
3322   if (!NonDerivedTypeScope().IsModule()) { // C817
3323     Say(currStmtSource().value(),
3324         "%s attribute may only appear in the specification part of a module"_err_en_US,
3325         EnumToString(attr));
3326   }
3327   CheckAndSet(attr);
3328   return false;
3329 }
3330 
3331 bool DeclarationVisitor::Pre(const parser::AsynchronousStmt &x) {
3332   return HandleAttributeStmt(Attr::ASYNCHRONOUS, x.v);
3333 }
3334 bool DeclarationVisitor::Pre(const parser::ContiguousStmt &x) {
3335   return HandleAttributeStmt(Attr::CONTIGUOUS, x.v);
3336 }
3337 bool DeclarationVisitor::Pre(const parser::ExternalStmt &x) {
3338   HandleAttributeStmt(Attr::EXTERNAL, x.v);
3339   for (const auto &name : x.v) {
3340     auto *symbol{FindSymbol(name)};
3341     if (!ConvertToProcEntity(*symbol)) {
3342       SayWithDecl(
3343           name, *symbol, "EXTERNAL attribute not allowed on '%s'"_err_en_US);
3344     }
3345   }
3346   return false;
3347 }
3348 bool DeclarationVisitor::Pre(const parser::IntentStmt &x) {
3349   auto &intentSpec{std::get<parser::IntentSpec>(x.t)};
3350   auto &names{std::get<std::list<parser::Name>>(x.t)};
3351   return CheckNotInBlock("INTENT") && // C1107
3352       HandleAttributeStmt(IntentSpecToAttr(intentSpec), names);
3353 }
3354 bool DeclarationVisitor::Pre(const parser::IntrinsicStmt &x) {
3355   HandleAttributeStmt(Attr::INTRINSIC, x.v);
3356   for (const auto &name : x.v) {
3357     auto *symbol{FindSymbol(name)};
3358     if (!ConvertToProcEntity(*symbol)) {
3359       SayWithDecl(
3360           name, *symbol, "INTRINSIC attribute not allowed on '%s'"_err_en_US);
3361     } else if (symbol->attrs().test(Attr::EXTERNAL)) { // C840
3362       Say(symbol->name(),
3363           "Symbol '%s' cannot have both EXTERNAL and INTRINSIC attributes"_err_en_US,
3364           symbol->name());
3365     }
3366   }
3367   return false;
3368 }
3369 bool DeclarationVisitor::Pre(const parser::OptionalStmt &x) {
3370   return CheckNotInBlock("OPTIONAL") && // C1107
3371       HandleAttributeStmt(Attr::OPTIONAL, x.v);
3372 }
3373 bool DeclarationVisitor::Pre(const parser::ProtectedStmt &x) {
3374   return HandleAttributeStmt(Attr::PROTECTED, x.v);
3375 }
3376 bool DeclarationVisitor::Pre(const parser::ValueStmt &x) {
3377   return CheckNotInBlock("VALUE") && // C1107
3378       HandleAttributeStmt(Attr::VALUE, x.v);
3379 }
3380 bool DeclarationVisitor::Pre(const parser::VolatileStmt &x) {
3381   return HandleAttributeStmt(Attr::VOLATILE, x.v);
3382 }
3383 // Handle a statement that sets an attribute on a list of names.
3384 bool DeclarationVisitor::HandleAttributeStmt(
3385     Attr attr, const std::list<parser::Name> &names) {
3386   for (const auto &name : names) {
3387     HandleAttributeStmt(attr, name);
3388   }
3389   return false;
3390 }
3391 Symbol &DeclarationVisitor::HandleAttributeStmt(
3392     Attr attr, const parser::Name &name) {
3393   if (attr == Attr::INTRINSIC &&
3394       !context().intrinsics().IsIntrinsic(name.source.ToString())) {
3395     Say(name.source, "'%s' is not a known intrinsic procedure"_err_en_US);
3396   }
3397   auto *symbol{FindInScope(currScope(), name)};
3398   if (attr == Attr::ASYNCHRONOUS || attr == Attr::VOLATILE) {
3399     // these can be set on a symbol that is host-assoc or use-assoc
3400     if (!symbol &&
3401         (currScope().kind() == Scope::Kind::Subprogram ||
3402             currScope().kind() == Scope::Kind::Block)) {
3403       if (auto *hostSymbol{FindSymbol(name)}) {
3404         name.symbol = nullptr;
3405         symbol = &MakeSymbol(name, HostAssocDetails{*hostSymbol});
3406       }
3407     }
3408   } else if (symbol && symbol->has<UseDetails>()) {
3409     Say(currStmtSource().value(),
3410         "Cannot change %s attribute on use-associated '%s'"_err_en_US,
3411         EnumToString(attr), name.source);
3412     return *symbol;
3413   }
3414   if (!symbol) {
3415     symbol = &MakeSymbol(name, EntityDetails{});
3416   }
3417   symbol->attrs().set(attr);
3418   symbol->attrs() = HandleSaveName(name.source, symbol->attrs());
3419   return *symbol;
3420 }
3421 // C1107
3422 bool DeclarationVisitor::CheckNotInBlock(const char *stmt) {
3423   if (currScope().kind() == Scope::Kind::Block) {
3424     Say(MessageFormattedText{
3425         "%s statement is not allowed in a BLOCK construct"_err_en_US, stmt});
3426     return false;
3427   } else {
3428     return true;
3429   }
3430 }
3431 
3432 void DeclarationVisitor::Post(const parser::ObjectDecl &x) {
3433   CHECK(objectDeclAttr_);
3434   const auto &name{std::get<parser::ObjectName>(x.t)};
3435   DeclareObjectEntity(name, Attrs{*objectDeclAttr_});
3436 }
3437 
3438 // Declare an entity not yet known to be an object or proc.
3439 Symbol &DeclarationVisitor::DeclareUnknownEntity(
3440     const parser::Name &name, Attrs attrs) {
3441   if (!arraySpec().empty() || !coarraySpec().empty()) {
3442     return DeclareObjectEntity(name, attrs);
3443   } else {
3444     Symbol &symbol{DeclareEntity<EntityDetails>(name, attrs)};
3445     if (auto *type{GetDeclTypeSpec()}) {
3446       SetType(name, *type);
3447     }
3448     charInfo_.length.reset();
3449     SetBindNameOn(symbol);
3450     if (symbol.attrs().test(Attr::EXTERNAL)) {
3451       ConvertToProcEntity(symbol);
3452     }
3453     return symbol;
3454   }
3455 }
3456 
3457 Symbol &DeclarationVisitor::DeclareProcEntity(
3458     const parser::Name &name, Attrs attrs, const ProcInterface &interface) {
3459   Symbol &symbol{DeclareEntity<ProcEntityDetails>(name, attrs)};
3460   if (auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
3461     if (details->IsInterfaceSet()) {
3462       SayWithDecl(name, symbol,
3463           "The interface for procedure '%s' has already been "
3464           "declared"_err_en_US);
3465       context().SetError(symbol);
3466     } else {
3467       if (interface.type()) {
3468         symbol.set(Symbol::Flag::Function);
3469       } else if (interface.symbol()) {
3470         if (interface.symbol()->test(Symbol::Flag::Function)) {
3471           symbol.set(Symbol::Flag::Function);
3472         } else if (interface.symbol()->test(Symbol::Flag::Subroutine)) {
3473           symbol.set(Symbol::Flag::Subroutine);
3474         }
3475       }
3476       details->set_interface(interface);
3477       SetBindNameOn(symbol);
3478       SetPassNameOn(symbol);
3479     }
3480   }
3481   return symbol;
3482 }
3483 
3484 Symbol &DeclarationVisitor::DeclareObjectEntity(
3485     const parser::Name &name, Attrs attrs) {
3486   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, attrs)};
3487   if (auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
3488     if (auto *type{GetDeclTypeSpec()}) {
3489       SetType(name, *type);
3490     }
3491     if (!arraySpec().empty()) {
3492       if (details->IsArray()) {
3493         if (!context().HasError(symbol)) {
3494           Say(name,
3495               "The dimensions of '%s' have already been declared"_err_en_US);
3496           context().SetError(symbol);
3497         }
3498       } else {
3499         details->set_shape(arraySpec());
3500       }
3501     }
3502     if (!coarraySpec().empty()) {
3503       if (details->IsCoarray()) {
3504         if (!context().HasError(symbol)) {
3505           Say(name,
3506               "The codimensions of '%s' have already been declared"_err_en_US);
3507           context().SetError(symbol);
3508         }
3509       } else {
3510         details->set_coshape(coarraySpec());
3511       }
3512     }
3513     SetBindNameOn(symbol);
3514   }
3515   ClearArraySpec();
3516   ClearCoarraySpec();
3517   charInfo_.length.reset();
3518   return symbol;
3519 }
3520 
3521 void DeclarationVisitor::Post(const parser::IntegerTypeSpec &x) {
3522   SetDeclTypeSpec(MakeNumericType(TypeCategory::Integer, x.v));
3523 }
3524 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Real &x) {
3525   SetDeclTypeSpec(MakeNumericType(TypeCategory::Real, x.kind));
3526 }
3527 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Complex &x) {
3528   SetDeclTypeSpec(MakeNumericType(TypeCategory::Complex, x.kind));
3529 }
3530 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Logical &x) {
3531   SetDeclTypeSpec(MakeLogicalType(x.kind));
3532 }
3533 void DeclarationVisitor::Post(const parser::IntrinsicTypeSpec::Character &) {
3534   if (!charInfo_.length) {
3535     charInfo_.length = ParamValue{1, common::TypeParamAttr::Len};
3536   }
3537   if (!charInfo_.kind) {
3538     charInfo_.kind =
3539         KindExpr{context().GetDefaultKind(TypeCategory::Character)};
3540   }
3541   SetDeclTypeSpec(currScope().MakeCharacterType(
3542       std::move(*charInfo_.length), std::move(*charInfo_.kind)));
3543   charInfo_ = {};
3544 }
3545 void DeclarationVisitor::Post(const parser::CharSelector::LengthAndKind &x) {
3546   charInfo_.kind = EvaluateSubscriptIntExpr(x.kind);
3547   std::optional<std::int64_t> intKind{ToInt64(charInfo_.kind)};
3548   if (intKind &&
3549       !evaluate::IsValidKindOfIntrinsicType(
3550           TypeCategory::Character, *intKind)) { // C715, C719
3551     Say(currStmtSource().value(),
3552         "KIND value (%jd) not valid for CHARACTER"_err_en_US, *intKind);
3553   }
3554   if (x.length) {
3555     charInfo_.length = GetParamValue(*x.length, common::TypeParamAttr::Len);
3556   }
3557 }
3558 void DeclarationVisitor::Post(const parser::CharLength &x) {
3559   if (const auto *length{std::get_if<std::uint64_t>(&x.u)}) {
3560     charInfo_.length = ParamValue{
3561         static_cast<ConstantSubscript>(*length), common::TypeParamAttr::Len};
3562   } else {
3563     charInfo_.length = GetParamValue(
3564         std::get<parser::TypeParamValue>(x.u), common::TypeParamAttr::Len);
3565   }
3566 }
3567 void DeclarationVisitor::Post(const parser::LengthSelector &x) {
3568   if (const auto *param{std::get_if<parser::TypeParamValue>(&x.u)}) {
3569     charInfo_.length = GetParamValue(*param, common::TypeParamAttr::Len);
3570   }
3571 }
3572 
3573 bool DeclarationVisitor::Pre(const parser::KindParam &x) {
3574   if (const auto *kind{std::get_if<
3575           parser::Scalar<parser::Integer<parser::Constant<parser::Name>>>>(
3576           &x.u)}) {
3577     const parser::Name &name{kind->thing.thing.thing};
3578     if (!FindSymbol(name)) {
3579       Say(name, "Parameter '%s' not found"_err_en_US);
3580     }
3581   }
3582   return false;
3583 }
3584 
3585 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Type &) {
3586   CHECK(GetDeclTypeSpecCategory() == DeclTypeSpec::Category::TypeDerived);
3587   return true;
3588 }
3589 
3590 void DeclarationVisitor::Post(const parser::DeclarationTypeSpec::Type &type) {
3591   const parser::Name &derivedName{std::get<parser::Name>(type.derived.t)};
3592   if (const Symbol * derivedSymbol{derivedName.symbol}) {
3593     CheckForAbstractType(*derivedSymbol); // C706
3594   }
3595 }
3596 
3597 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Class &) {
3598   SetDeclTypeSpecCategory(DeclTypeSpec::Category::ClassDerived);
3599   return true;
3600 }
3601 
3602 void DeclarationVisitor::Post(
3603     const parser::DeclarationTypeSpec::Class &parsedClass) {
3604   const auto &typeName{std::get<parser::Name>(parsedClass.derived.t)};
3605   if (auto spec{ResolveDerivedType(typeName)};
3606       spec && !IsExtensibleType(&*spec)) { // C705
3607     SayWithDecl(typeName, *typeName.symbol,
3608         "Non-extensible derived type '%s' may not be used with CLASS"
3609         " keyword"_err_en_US);
3610   }
3611 }
3612 
3613 bool DeclarationVisitor::Pre(const parser::DeclarationTypeSpec::Record &) {
3614   // TODO
3615   return true;
3616 }
3617 
3618 void DeclarationVisitor::Post(const parser::DerivedTypeSpec &x) {
3619   const auto &typeName{std::get<parser::Name>(x.t)};
3620   auto spec{ResolveDerivedType(typeName)};
3621   if (!spec) {
3622     return;
3623   }
3624   bool seenAnyName{false};
3625   for (const auto &typeParamSpec :
3626       std::get<std::list<parser::TypeParamSpec>>(x.t)) {
3627     const auto &optKeyword{
3628         std::get<std::optional<parser::Keyword>>(typeParamSpec.t)};
3629     std::optional<SourceName> name;
3630     if (optKeyword) {
3631       seenAnyName = true;
3632       name = optKeyword->v.source;
3633     } else if (seenAnyName) {
3634       Say(typeName.source, "Type parameter value must have a name"_err_en_US);
3635       continue;
3636     }
3637     const auto &value{std::get<parser::TypeParamValue>(typeParamSpec.t)};
3638     // The expressions in a derived type specifier whose values define
3639     // non-defaulted type parameters are evaluated (folded) in the enclosing
3640     // scope.  The KIND/LEN distinction is resolved later in
3641     // DerivedTypeSpec::CookParameters().
3642     ParamValue param{GetParamValue(value, common::TypeParamAttr::Kind)};
3643     if (!param.isExplicit() || param.GetExplicit()) {
3644       spec->AddRawParamValue(optKeyword, std::move(param));
3645     }
3646   }
3647 
3648   // The DerivedTypeSpec *spec is used initially as a search key.
3649   // If it turns out to have the same name and actual parameter
3650   // value expressions as another DerivedTypeSpec in the current
3651   // scope does, then we'll use that extant spec; otherwise, when this
3652   // spec is distinct from all derived types previously instantiated
3653   // in the current scope, this spec will be moved into that collection.
3654   const auto &dtDetails{spec->typeSymbol().get<DerivedTypeDetails>()};
3655   auto category{GetDeclTypeSpecCategory()};
3656   if (dtDetails.isForwardReferenced()) {
3657     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
3658     SetDeclTypeSpec(type);
3659     return;
3660   }
3661   // Normalize parameters to produce a better search key.
3662   spec->CookParameters(GetFoldingContext());
3663   if (!spec->MightBeParameterized()) {
3664     spec->EvaluateParameters(GetFoldingContext());
3665   }
3666   if (const DeclTypeSpec *
3667       extant{currScope().FindInstantiatedDerivedType(*spec, category)}) {
3668     // This derived type and parameter expressions (if any) are already present
3669     // in this scope.
3670     SetDeclTypeSpec(*extant);
3671   } else {
3672     DeclTypeSpec &type{currScope().MakeDerivedType(category, std::move(*spec))};
3673     DerivedTypeSpec &derived{type.derivedTypeSpec()};
3674     if (derived.MightBeParameterized() &&
3675         currScope().IsParameterizedDerivedType()) {
3676       // Defer instantiation; use the derived type's definition's scope.
3677       derived.set_scope(DEREF(spec->typeSymbol().scope()));
3678     } else {
3679       auto restorer{
3680           GetFoldingContext().messages().SetLocation(currStmtSource().value())};
3681       derived.Instantiate(currScope(), context());
3682     }
3683     SetDeclTypeSpec(type);
3684   }
3685   // Capture the DerivedTypeSpec in the parse tree for use in building
3686   // structure constructor expressions.
3687   x.derivedTypeSpec = &GetDeclTypeSpec()->derivedTypeSpec();
3688 }
3689 
3690 // The descendents of DerivedTypeDef in the parse tree are visited directly
3691 // in this Pre() routine so that recursive use of the derived type can be
3692 // supported in the components.
3693 bool DeclarationVisitor::Pre(const parser::DerivedTypeDef &x) {
3694   auto &stmt{std::get<parser::Statement<parser::DerivedTypeStmt>>(x.t)};
3695   Walk(stmt);
3696   Walk(std::get<std::list<parser::Statement<parser::TypeParamDefStmt>>>(x.t));
3697   auto &scope{currScope()};
3698   CHECK(scope.symbol());
3699   CHECK(scope.symbol()->scope() == &scope);
3700   auto &details{scope.symbol()->get<DerivedTypeDetails>()};
3701   std::set<SourceName> paramNames;
3702   for (auto &paramName : std::get<std::list<parser::Name>>(stmt.statement.t)) {
3703     details.add_paramName(paramName.source);
3704     auto *symbol{FindInScope(scope, paramName)};
3705     if (!symbol) {
3706       Say(paramName,
3707           "No definition found for type parameter '%s'"_err_en_US); // C742
3708       // No symbol for a type param.  Create one and mark it as containing an
3709       // error to improve subsequent semantic processing
3710       BeginAttrs();
3711       Symbol *typeParam{MakeTypeSymbol(
3712           paramName, TypeParamDetails{common::TypeParamAttr::Len})};
3713       typeParam->set(Symbol::Flag::Error);
3714       EndAttrs();
3715     } else if (!symbol->has<TypeParamDetails>()) {
3716       Say2(paramName, "'%s' is not defined as a type parameter"_err_en_US,
3717           *symbol, "Definition of '%s'"_en_US); // C741
3718     }
3719     if (!paramNames.insert(paramName.source).second) {
3720       Say(paramName,
3721           "Duplicate type parameter name: '%s'"_err_en_US); // C731
3722     }
3723   }
3724   for (const auto &[name, symbol] : currScope()) {
3725     if (symbol->has<TypeParamDetails>() && !paramNames.count(name)) {
3726       SayDerivedType(name,
3727           "'%s' is not a type parameter of this derived type"_err_en_US,
3728           currScope()); // C741
3729     }
3730   }
3731   Walk(std::get<std::list<parser::Statement<parser::PrivateOrSequence>>>(x.t));
3732   const auto &componentDefs{
3733       std::get<std::list<parser::Statement<parser::ComponentDefStmt>>>(x.t)};
3734   Walk(componentDefs);
3735   if (derivedTypeInfo_.sequence) {
3736     details.set_sequence(true);
3737     if (componentDefs.empty()) { // C740
3738       Say(stmt.source,
3739           "A sequence type must have at least one component"_err_en_US);
3740     }
3741     if (!details.paramNames().empty()) { // C740
3742       Say(stmt.source,
3743           "A sequence type may not have type parameters"_err_en_US);
3744     }
3745     if (derivedTypeInfo_.extends) { // C735
3746       Say(stmt.source,
3747           "A sequence type may not have the EXTENDS attribute"_err_en_US);
3748     } else {
3749       for (const auto &componentName : details.componentNames()) {
3750         const Symbol *componentSymbol{scope.FindComponent(componentName)};
3751         if (componentSymbol && componentSymbol->has<ObjectEntityDetails>()) {
3752           const auto &componentDetails{
3753               componentSymbol->get<ObjectEntityDetails>()};
3754           const DeclTypeSpec *componentType{componentDetails.type()};
3755           if (componentType && // C740
3756               !componentType->AsIntrinsic() &&
3757               !componentType->IsSequenceType()) {
3758             Say(componentSymbol->name(),
3759                 "A sequence type data component must either be of an"
3760                 " intrinsic type or a derived sequence type"_err_en_US);
3761           }
3762         }
3763       }
3764     }
3765   }
3766   Walk(std::get<std::optional<parser::TypeBoundProcedurePart>>(x.t));
3767   Walk(std::get<parser::Statement<parser::EndTypeStmt>>(x.t));
3768   derivedTypeInfo_ = {};
3769   PopScope();
3770   return false;
3771 }
3772 bool DeclarationVisitor::Pre(const parser::DerivedTypeStmt &) {
3773   return BeginAttrs();
3774 }
3775 void DeclarationVisitor::Post(const parser::DerivedTypeStmt &x) {
3776   auto &name{std::get<parser::Name>(x.t)};
3777   // Resolve the EXTENDS() clause before creating the derived
3778   // type's symbol to foil attempts to recursively extend a type.
3779   auto *extendsName{derivedTypeInfo_.extends};
3780   std::optional<DerivedTypeSpec> extendsType{
3781       ResolveExtendsType(name, extendsName)};
3782   auto &symbol{MakeSymbol(name, GetAttrs(), DerivedTypeDetails{})};
3783   symbol.ReplaceName(name.source);
3784   derivedTypeInfo_.type = &symbol;
3785   PushScope(Scope::Kind::DerivedType, &symbol);
3786   if (extendsType) {
3787     // Declare the "parent component"; private if the type is.
3788     // Any symbol stored in the EXTENDS() clause is temporarily
3789     // hidden so that a new symbol can be created for the parent
3790     // component without producing spurious errors about already
3791     // existing.
3792     const Symbol &extendsSymbol{extendsType->typeSymbol()};
3793     auto restorer{common::ScopedSet(extendsName->symbol, nullptr)};
3794     if (OkToAddComponent(*extendsName, &extendsSymbol)) {
3795       auto &comp{DeclareEntity<ObjectEntityDetails>(*extendsName, Attrs{})};
3796       comp.attrs().set(
3797           Attr::PRIVATE, extendsSymbol.attrs().test(Attr::PRIVATE));
3798       comp.set(Symbol::Flag::ParentComp);
3799       DeclTypeSpec &type{currScope().MakeDerivedType(
3800           DeclTypeSpec::TypeDerived, std::move(*extendsType))};
3801       type.derivedTypeSpec().set_scope(*extendsSymbol.scope());
3802       comp.SetType(type);
3803       DerivedTypeDetails &details{symbol.get<DerivedTypeDetails>()};
3804       details.add_component(comp);
3805     }
3806   }
3807   EndAttrs();
3808 }
3809 
3810 void DeclarationVisitor::Post(const parser::TypeParamDefStmt &x) {
3811   auto *type{GetDeclTypeSpec()};
3812   auto attr{std::get<common::TypeParamAttr>(x.t)};
3813   for (auto &decl : std::get<std::list<parser::TypeParamDecl>>(x.t)) {
3814     auto &name{std::get<parser::Name>(decl.t)};
3815     if (Symbol * symbol{MakeTypeSymbol(name, TypeParamDetails{attr})}) {
3816       SetType(name, *type);
3817       if (auto &init{
3818               std::get<std::optional<parser::ScalarIntConstantExpr>>(decl.t)}) {
3819         if (auto maybeExpr{EvaluateConvertedExpr(
3820                 *symbol, *init, init->thing.thing.thing.value().source)}) {
3821           auto *intExpr{std::get_if<SomeIntExpr>(&maybeExpr->u)};
3822           CHECK(intExpr);
3823           symbol->get<TypeParamDetails>().set_init(std::move(*intExpr));
3824         }
3825       }
3826     }
3827   }
3828   EndDecl();
3829 }
3830 bool DeclarationVisitor::Pre(const parser::TypeAttrSpec::Extends &x) {
3831   if (derivedTypeInfo_.extends) {
3832     Say(currStmtSource().value(),
3833         "Attribute 'EXTENDS' cannot be used more than once"_err_en_US);
3834   } else {
3835     derivedTypeInfo_.extends = &x.v;
3836   }
3837   return false;
3838 }
3839 
3840 bool DeclarationVisitor::Pre(const parser::PrivateStmt &) {
3841   if (!currScope().parent().IsModule()) {
3842     Say("PRIVATE is only allowed in a derived type that is"
3843         " in a module"_err_en_US); // C766
3844   } else if (derivedTypeInfo_.sawContains) {
3845     derivedTypeInfo_.privateBindings = true;
3846   } else if (!derivedTypeInfo_.privateComps) {
3847     derivedTypeInfo_.privateComps = true;
3848   } else {
3849     Say("PRIVATE may not appear more than once in"
3850         " derived type components"_en_US); // C738
3851   }
3852   return false;
3853 }
3854 bool DeclarationVisitor::Pre(const parser::SequenceStmt &) {
3855   if (derivedTypeInfo_.sequence) {
3856     Say("SEQUENCE may not appear more than once in"
3857         " derived type components"_en_US); // C738
3858   }
3859   derivedTypeInfo_.sequence = true;
3860   return false;
3861 }
3862 void DeclarationVisitor::Post(const parser::ComponentDecl &x) {
3863   const auto &name{std::get<parser::Name>(x.t)};
3864   auto attrs{GetAttrs()};
3865   if (derivedTypeInfo_.privateComps &&
3866       !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
3867     attrs.set(Attr::PRIVATE);
3868   }
3869   if (const auto *declType{GetDeclTypeSpec()}) {
3870     if (const auto *derived{declType->AsDerived()}) {
3871       if (!attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
3872         if (derivedTypeInfo_.type == &derived->typeSymbol()) { // C744
3873           Say("Recursive use of the derived type requires "
3874               "POINTER or ALLOCATABLE"_err_en_US);
3875         }
3876       }
3877       if (!coarraySpec().empty()) { // C747
3878         if (IsTeamType(derived)) {
3879           Say("A coarray component may not be of type TEAM_TYPE from "
3880               "ISO_FORTRAN_ENV"_err_en_US);
3881         } else {
3882           if (IsIsoCType(derived)) {
3883             Say("A coarray component may not be of type C_PTR or C_FUNPTR from "
3884                 "ISO_C_BINDING"_err_en_US);
3885           }
3886         }
3887       }
3888       if (auto it{FindCoarrayUltimateComponent(*derived)}) { // C748
3889         std::string ultimateName{it.BuildResultDesignatorName()};
3890         // Strip off the leading "%"
3891         if (ultimateName.length() > 1) {
3892           ultimateName.erase(0, 1);
3893           if (attrs.HasAny({Attr::POINTER, Attr::ALLOCATABLE})) {
3894             evaluate::AttachDeclaration(
3895                 Say(name.source,
3896                     "A component with a POINTER or ALLOCATABLE attribute may "
3897                     "not "
3898                     "be of a type with a coarray ultimate component (named "
3899                     "'%s')"_err_en_US,
3900                     ultimateName),
3901                 derived->typeSymbol());
3902           }
3903           if (!arraySpec().empty() || !coarraySpec().empty()) {
3904             evaluate::AttachDeclaration(
3905                 Say(name.source,
3906                     "An array or coarray component may not be of a type with a "
3907                     "coarray ultimate component (named '%s')"_err_en_US,
3908                     ultimateName),
3909                 derived->typeSymbol());
3910           }
3911         }
3912       }
3913     }
3914   }
3915   if (OkToAddComponent(name)) {
3916     auto &symbol{DeclareObjectEntity(name, attrs)};
3917     if (symbol.has<ObjectEntityDetails>()) {
3918       if (auto &init{std::get<std::optional<parser::Initialization>>(x.t)}) {
3919         Initialization(name, *init, true);
3920       }
3921     }
3922     currScope().symbol()->get<DerivedTypeDetails>().add_component(symbol);
3923   }
3924   ClearArraySpec();
3925   ClearCoarraySpec();
3926 }
3927 bool DeclarationVisitor::Pre(const parser::ProcedureDeclarationStmt &) {
3928   CHECK(!interfaceName_);
3929   return BeginDecl();
3930 }
3931 void DeclarationVisitor::Post(const parser::ProcedureDeclarationStmt &) {
3932   interfaceName_ = nullptr;
3933   EndDecl();
3934 }
3935 bool DeclarationVisitor::Pre(const parser::DataComponentDefStmt &x) {
3936   // Overrides parse tree traversal so as to handle attributes first,
3937   // so POINTER & ALLOCATABLE enable forward references to derived types.
3938   Walk(std::get<std::list<parser::ComponentAttrSpec>>(x.t));
3939   set_allowForwardReferenceToDerivedType(
3940       GetAttrs().HasAny({Attr::POINTER, Attr::ALLOCATABLE}));
3941   Walk(std::get<parser::DeclarationTypeSpec>(x.t));
3942   set_allowForwardReferenceToDerivedType(false);
3943   Walk(std::get<std::list<parser::ComponentDecl>>(x.t));
3944   return false;
3945 }
3946 bool DeclarationVisitor::Pre(const parser::ProcComponentDefStmt &) {
3947   CHECK(!interfaceName_);
3948   return true;
3949 }
3950 void DeclarationVisitor::Post(const parser::ProcComponentDefStmt &) {
3951   interfaceName_ = nullptr;
3952 }
3953 bool DeclarationVisitor::Pre(const parser::ProcPointerInit &x) {
3954   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
3955     return !NameIsKnownOrIntrinsic(*name);
3956   }
3957   return true;
3958 }
3959 void DeclarationVisitor::Post(const parser::ProcInterface &x) {
3960   if (auto *name{std::get_if<parser::Name>(&x.u)}) {
3961     interfaceName_ = name;
3962     NoteInterfaceName(*name);
3963   }
3964 }
3965 
3966 void DeclarationVisitor::Post(const parser::ProcDecl &x) {
3967   const auto &name{std::get<parser::Name>(x.t)};
3968   ProcInterface interface;
3969   if (interfaceName_) {
3970     interface.set_symbol(*interfaceName_->symbol);
3971   } else if (auto *type{GetDeclTypeSpec()}) {
3972     interface.set_type(*type);
3973   }
3974   auto attrs{HandleSaveName(name.source, GetAttrs())};
3975   DerivedTypeDetails *dtDetails{nullptr};
3976   if (Symbol * symbol{currScope().symbol()}) {
3977     dtDetails = symbol->detailsIf<DerivedTypeDetails>();
3978   }
3979   if (!dtDetails) {
3980     attrs.set(Attr::EXTERNAL);
3981   }
3982   Symbol &symbol{DeclareProcEntity(name, attrs, interface)};
3983   symbol.ReplaceName(name.source);
3984   if (dtDetails) {
3985     dtDetails->add_component(symbol);
3986   }
3987 }
3988 
3989 bool DeclarationVisitor::Pre(const parser::TypeBoundProcedurePart &) {
3990   derivedTypeInfo_.sawContains = true;
3991   return true;
3992 }
3993 
3994 // Resolve binding names from type-bound generics, saved in genericBindings_.
3995 void DeclarationVisitor::Post(const parser::TypeBoundProcedurePart &) {
3996   // track specifics seen for the current generic to detect duplicates:
3997   const Symbol *currGeneric{nullptr};
3998   std::set<SourceName> specifics;
3999   for (const auto &[generic, bindingName] : genericBindings_) {
4000     if (generic != currGeneric) {
4001       currGeneric = generic;
4002       specifics.clear();
4003     }
4004     auto [it, inserted]{specifics.insert(bindingName->source)};
4005     if (!inserted) {
4006       Say(*bindingName, // C773
4007           "Binding name '%s' was already specified for generic '%s'"_err_en_US,
4008           bindingName->source, generic->name())
4009           .Attach(*it, "Previous specification of '%s'"_en_US, *it);
4010       continue;
4011     }
4012     auto *symbol{FindInTypeOrParents(*bindingName)};
4013     if (!symbol) {
4014       Say(*bindingName, // C772
4015           "Binding name '%s' not found in this derived type"_err_en_US);
4016     } else if (!symbol->has<ProcBindingDetails>()) {
4017       SayWithDecl(*bindingName, *symbol, // C772
4018           "'%s' is not the name of a specific binding of this type"_err_en_US);
4019     } else {
4020       generic->get<GenericDetails>().AddSpecificProc(
4021           *symbol, bindingName->source);
4022     }
4023   }
4024   genericBindings_.clear();
4025 }
4026 
4027 void DeclarationVisitor::Post(const parser::ContainsStmt &) {
4028   if (derivedTypeInfo_.sequence) {
4029     Say("A sequence type may not have a CONTAINS statement"_err_en_US); // C740
4030   }
4031 }
4032 
4033 void DeclarationVisitor::Post(
4034     const parser::TypeBoundProcedureStmt::WithoutInterface &x) {
4035   if (GetAttrs().test(Attr::DEFERRED)) { // C783
4036     Say("DEFERRED is only allowed when an interface-name is provided"_err_en_US);
4037   }
4038   for (auto &declaration : x.declarations) {
4039     auto &bindingName{std::get<parser::Name>(declaration.t)};
4040     auto &optName{std::get<std::optional<parser::Name>>(declaration.t)};
4041     const parser::Name &procedureName{optName ? *optName : bindingName};
4042     Symbol *procedure{FindSymbol(procedureName)};
4043     if (!procedure) {
4044       procedure = NoteInterfaceName(procedureName);
4045     }
4046     if (auto *s{MakeTypeSymbol(bindingName, ProcBindingDetails{*procedure})}) {
4047       SetPassNameOn(*s);
4048       if (GetAttrs().test(Attr::DEFERRED)) {
4049         context().SetError(*s);
4050       }
4051     }
4052   }
4053 }
4054 
4055 void DeclarationVisitor::CheckBindings(
4056     const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
4057   CHECK(currScope().IsDerivedType());
4058   for (auto &declaration : tbps.declarations) {
4059     auto &bindingName{std::get<parser::Name>(declaration.t)};
4060     if (Symbol * binding{FindInScope(currScope(), bindingName)}) {
4061       if (auto *details{binding->detailsIf<ProcBindingDetails>()}) {
4062         const Symbol *procedure{FindSubprogram(details->symbol())};
4063         if (!CanBeTypeBoundProc(procedure)) {
4064           if (details->symbol().name() != binding->name()) {
4065             Say(binding->name(),
4066                 "The binding of '%s' ('%s') must be either an accessible "
4067                 "module procedure or an external procedure with "
4068                 "an explicit interface"_err_en_US,
4069                 binding->name(), details->symbol().name());
4070           } else {
4071             Say(binding->name(),
4072                 "'%s' must be either an accessible module procedure "
4073                 "or an external procedure with an explicit interface"_err_en_US,
4074                 binding->name());
4075           }
4076           context().SetError(*binding);
4077         }
4078       }
4079     }
4080   }
4081 }
4082 
4083 void DeclarationVisitor::Post(
4084     const parser::TypeBoundProcedureStmt::WithInterface &x) {
4085   if (!GetAttrs().test(Attr::DEFERRED)) { // C783
4086     Say("DEFERRED is required when an interface-name is provided"_err_en_US);
4087   }
4088   if (Symbol * interface{NoteInterfaceName(x.interfaceName)}) {
4089     for (auto &bindingName : x.bindingNames) {
4090       if (auto *s{
4091               MakeTypeSymbol(bindingName, ProcBindingDetails{*interface})}) {
4092         SetPassNameOn(*s);
4093         if (!GetAttrs().test(Attr::DEFERRED)) {
4094           context().SetError(*s);
4095         }
4096       }
4097     }
4098   }
4099 }
4100 
4101 void DeclarationVisitor::Post(const parser::FinalProcedureStmt &x) {
4102   for (auto &name : x.v) {
4103     MakeTypeSymbol(name, FinalProcDetails{});
4104   }
4105 }
4106 
4107 bool DeclarationVisitor::Pre(const parser::TypeBoundGenericStmt &x) {
4108   const auto &accessSpec{std::get<std::optional<parser::AccessSpec>>(x.t)};
4109   const auto &genericSpec{std::get<Indirection<parser::GenericSpec>>(x.t)};
4110   const auto &bindingNames{std::get<std::list<parser::Name>>(x.t)};
4111   auto info{GenericSpecInfo{genericSpec.value()}};
4112   SourceName symbolName{info.symbolName()};
4113   bool isPrivate{accessSpec ? accessSpec->v == parser::AccessSpec::Kind::Private
4114                             : derivedTypeInfo_.privateBindings};
4115   auto *genericSymbol{info.FindInScope(context(), currScope())};
4116   if (genericSymbol) {
4117     if (!genericSymbol->has<GenericDetails>()) {
4118       genericSymbol = nullptr; // MakeTypeSymbol will report the error below
4119     }
4120   } else {
4121     // look in parent types:
4122     Symbol *inheritedSymbol{nullptr};
4123     for (const auto &name : info.GetAllNames(context())) {
4124       inheritedSymbol = currScope().FindComponent(SourceName{name});
4125       if (inheritedSymbol) {
4126         break;
4127       }
4128     }
4129     if (inheritedSymbol && inheritedSymbol->has<GenericDetails>()) {
4130       CheckAccessibility(symbolName, isPrivate, *inheritedSymbol); // C771
4131     }
4132   }
4133   if (genericSymbol) {
4134     CheckAccessibility(symbolName, isPrivate, *genericSymbol); // C771
4135   } else {
4136     genericSymbol = MakeTypeSymbol(symbolName, GenericDetails{});
4137     if (!genericSymbol) {
4138       return false;
4139     }
4140     if (isPrivate) {
4141       genericSymbol->attrs().set(Attr::PRIVATE);
4142     }
4143   }
4144   for (const parser::Name &bindingName : bindingNames) {
4145     genericBindings_.emplace(genericSymbol, &bindingName);
4146   }
4147   info.Resolve(genericSymbol);
4148   return false;
4149 }
4150 
4151 bool DeclarationVisitor::Pre(const parser::AllocateStmt &) {
4152   BeginDeclTypeSpec();
4153   return true;
4154 }
4155 void DeclarationVisitor::Post(const parser::AllocateStmt &) {
4156   EndDeclTypeSpec();
4157 }
4158 
4159 bool DeclarationVisitor::Pre(const parser::StructureConstructor &x) {
4160   auto &parsedType{std::get<parser::DerivedTypeSpec>(x.t)};
4161   const DeclTypeSpec *type{ProcessTypeSpec(parsedType)};
4162   if (!type) {
4163     return false;
4164   }
4165   const DerivedTypeSpec *spec{type->AsDerived()};
4166   const Scope *typeScope{spec ? spec->scope() : nullptr};
4167   if (!typeScope) {
4168     return false;
4169   }
4170 
4171   // N.B C7102 is implicitly enforced by having inaccessible types not
4172   // being found in resolution.
4173   // More constraints are enforced in expression.cpp so that they
4174   // can apply to structure constructors that have been converted
4175   // from misparsed function references.
4176   for (const auto &component :
4177       std::get<std::list<parser::ComponentSpec>>(x.t)) {
4178     // Visit the component spec expression, but not the keyword, since
4179     // we need to resolve its symbol in the scope of the derived type.
4180     Walk(std::get<parser::ComponentDataSource>(component.t));
4181     if (const auto &kw{std::get<std::optional<parser::Keyword>>(component.t)}) {
4182       FindInTypeOrParents(*typeScope, kw->v);
4183     }
4184   }
4185   return false;
4186 }
4187 
4188 bool DeclarationVisitor::Pre(const parser::BasedPointerStmt &x) {
4189   for (const parser::BasedPointer &bp : x.v) {
4190     const parser::ObjectName &pointerName{std::get<0>(bp.t)};
4191     const parser::ObjectName &pointeeName{std::get<1>(bp.t)};
4192     auto *pointer{FindSymbol(pointerName)};
4193     if (!pointer) {
4194       pointer = &MakeSymbol(pointerName, ObjectEntityDetails{});
4195     } else if (!ConvertToObjectEntity(*pointer) || IsNamedConstant(*pointer)) {
4196       SayWithDecl(pointerName, *pointer, "'%s' is not a variable"_err_en_US);
4197     } else if (pointer->Rank() > 0) {
4198       SayWithDecl(pointerName, *pointer,
4199           "Cray pointer '%s' must be a scalar"_err_en_US);
4200     } else if (pointer->test(Symbol::Flag::CrayPointee)) {
4201       Say(pointerName,
4202           "'%s' cannot be a Cray pointer as it is already a Cray pointee"_err_en_US);
4203     }
4204     pointer->set(Symbol::Flag::CrayPointer);
4205     const DeclTypeSpec &pointerType{MakeNumericType(TypeCategory::Integer,
4206         context().defaultKinds().subscriptIntegerKind())};
4207     const auto *type{pointer->GetType()};
4208     if (!type) {
4209       pointer->SetType(pointerType);
4210     } else if (*type != pointerType) {
4211       Say(pointerName.source, "Cray pointer '%s' must have type %s"_err_en_US,
4212           pointerName.source, pointerType.AsFortran());
4213     }
4214     if (ResolveName(pointeeName)) {
4215       Symbol &pointee{*pointeeName.symbol};
4216       if (pointee.has<UseDetails>()) {
4217         Say(pointeeName,
4218             "'%s' cannot be a Cray pointee as it is use-associated"_err_en_US);
4219         continue;
4220       } else if (!ConvertToObjectEntity(pointee) || IsNamedConstant(pointee)) {
4221         Say(pointeeName, "'%s' is not a variable"_err_en_US);
4222         continue;
4223       } else if (pointee.test(Symbol::Flag::CrayPointer)) {
4224         Say(pointeeName,
4225             "'%s' cannot be a Cray pointee as it is already a Cray pointer"_err_en_US);
4226       } else if (pointee.test(Symbol::Flag::CrayPointee)) {
4227         Say(pointeeName,
4228             "'%s' was already declared as a Cray pointee"_err_en_US);
4229       } else {
4230         pointee.set(Symbol::Flag::CrayPointee);
4231       }
4232       if (const auto *pointeeType{pointee.GetType()}) {
4233         if (const auto *derived{pointeeType->AsDerived()}) {
4234           if (!derived->typeSymbol().get<DerivedTypeDetails>().sequence()) {
4235             Say(pointeeName,
4236                 "Type of Cray pointee '%s' is a non-sequence derived type"_err_en_US);
4237           }
4238         }
4239       }
4240       // process the pointee array-spec, if present
4241       BeginArraySpec();
4242       Walk(std::get<std::optional<parser::ArraySpec>>(bp.t));
4243       const auto &spec{arraySpec()};
4244       if (!spec.empty()) {
4245         auto &details{pointee.get<ObjectEntityDetails>()};
4246         if (details.shape().empty()) {
4247           details.set_shape(spec);
4248         } else {
4249           SayWithDecl(pointeeName, pointee,
4250               "Array spec was already declared for '%s'"_err_en_US);
4251         }
4252       }
4253       ClearArraySpec();
4254       currScope().add_crayPointer(pointeeName.source, *pointer);
4255     }
4256   }
4257   return false;
4258 }
4259 
4260 bool DeclarationVisitor::Pre(const parser::NamelistStmt::Group &x) {
4261   if (!CheckNotInBlock("NAMELIST")) { // C1107
4262     return false;
4263   }
4264 
4265   NamelistDetails details;
4266   for (const auto &name : std::get<std::list<parser::Name>>(x.t)) {
4267     auto *symbol{FindSymbol(name)};
4268     if (!symbol) {
4269       symbol = &MakeSymbol(name, ObjectEntityDetails{});
4270       ApplyImplicitRules(*symbol);
4271     } else if (!ConvertToObjectEntity(*symbol)) {
4272       SayWithDecl(name, *symbol, "'%s' is not a variable"_err_en_US);
4273     }
4274     details.add_object(*symbol);
4275   }
4276 
4277   const auto &groupName{std::get<parser::Name>(x.t)};
4278   auto *groupSymbol{FindInScope(currScope(), groupName)};
4279   if (!groupSymbol || !groupSymbol->has<NamelistDetails>()) {
4280     groupSymbol = &MakeSymbol(groupName, std::move(details));
4281     groupSymbol->ReplaceName(groupName.source);
4282   }
4283   groupSymbol->get<NamelistDetails>().add_objects(details.objects());
4284   return false;
4285 }
4286 
4287 bool DeclarationVisitor::Pre(const parser::IoControlSpec &x) {
4288   if (const auto *name{std::get_if<parser::Name>(&x.u)}) {
4289     auto *symbol{FindSymbol(*name)};
4290     if (!symbol) {
4291       Say(*name, "Namelist group '%s' not found"_err_en_US);
4292     } else if (!symbol->GetUltimate().has<NamelistDetails>()) {
4293       SayWithDecl(
4294           *name, *symbol, "'%s' is not the name of a namelist group"_err_en_US);
4295     }
4296   }
4297   return true;
4298 }
4299 
4300 bool DeclarationVisitor::Pre(const parser::CommonStmt::Block &x) {
4301   CheckNotInBlock("COMMON"); // C1107
4302   const auto &optName{std::get<std::optional<parser::Name>>(x.t)};
4303   parser::Name blankCommon;
4304   blankCommon.source =
4305       SourceName{currStmtSource().value().begin(), std::size_t{0}};
4306   CHECK(!commonBlockInfo_.curr);
4307   commonBlockInfo_.curr =
4308       &MakeCommonBlockSymbol(optName ? *optName : blankCommon);
4309   return true;
4310 }
4311 
4312 void DeclarationVisitor::Post(const parser::CommonStmt::Block &) {
4313   commonBlockInfo_.curr = nullptr;
4314 }
4315 
4316 bool DeclarationVisitor::Pre(const parser::CommonBlockObject &) {
4317   BeginArraySpec();
4318   return true;
4319 }
4320 
4321 void DeclarationVisitor::Post(const parser::CommonBlockObject &x) {
4322   CHECK(commonBlockInfo_.curr);
4323   const auto &name{std::get<parser::Name>(x.t)};
4324   auto &symbol{DeclareObjectEntity(name, Attrs{})};
4325   ClearArraySpec();
4326   ClearCoarraySpec();
4327   auto *details{symbol.detailsIf<ObjectEntityDetails>()};
4328   if (!details) {
4329     return; // error was reported
4330   }
4331   commonBlockInfo_.curr->get<CommonBlockDetails>().add_object(symbol);
4332   auto pair{commonBlockInfo_.names.insert(name.source)};
4333   if (!pair.second) {
4334     const SourceName &prev{*pair.first};
4335     Say2(name.source, "'%s' is already in a COMMON block"_err_en_US, prev,
4336         "Previous occurrence of '%s' in a COMMON block"_en_US);
4337     return;
4338   }
4339   details->set_commonBlock(*commonBlockInfo_.curr);
4340 }
4341 
4342 bool DeclarationVisitor::Pre(const parser::EquivalenceStmt &x) {
4343   // save equivalence sets to be processed after specification part
4344   CheckNotInBlock("EQUIVALENCE"); // C1107
4345   for (const std::list<parser::EquivalenceObject> &set : x.v) {
4346     equivalenceSets_.push_back(&set);
4347   }
4348   return false; // don't implicitly declare names yet
4349 }
4350 
4351 void DeclarationVisitor::CheckEquivalenceSets() {
4352   EquivalenceSets equivSets{context()};
4353   for (const auto *set : equivalenceSets_) {
4354     const auto &source{set->front().v.value().source};
4355     if (set->size() <= 1) { // R871
4356       Say(source, "Equivalence set must have more than one object"_err_en_US);
4357     }
4358     for (const parser::EquivalenceObject &object : *set) {
4359       const auto &designator{object.v.value()};
4360       // The designator was not resolved when it was encountered so do it now.
4361       // AnalyzeExpr causes array sections to be changed to substrings as needed
4362       Walk(designator);
4363       if (AnalyzeExpr(context(), designator)) {
4364         equivSets.AddToSet(designator);
4365       }
4366     }
4367     equivSets.FinishSet(source);
4368   }
4369   for (auto &set : equivSets.sets()) {
4370     if (!set.empty()) {
4371       currScope().add_equivalenceSet(std::move(set));
4372     }
4373   }
4374   equivalenceSets_.clear();
4375 }
4376 
4377 bool DeclarationVisitor::Pre(const parser::SaveStmt &x) {
4378   if (x.v.empty()) {
4379     saveInfo_.saveAll = currStmtSource();
4380     currScope().set_hasSAVE();
4381   } else {
4382     for (const parser::SavedEntity &y : x.v) {
4383       auto kind{std::get<parser::SavedEntity::Kind>(y.t)};
4384       const auto &name{std::get<parser::Name>(y.t)};
4385       if (kind == parser::SavedEntity::Kind::Common) {
4386         MakeCommonBlockSymbol(name);
4387         AddSaveName(saveInfo_.commons, name.source);
4388       } else {
4389         HandleAttributeStmt(Attr::SAVE, name);
4390       }
4391     }
4392   }
4393   return false;
4394 }
4395 
4396 void DeclarationVisitor::CheckSaveStmts() {
4397   for (const SourceName &name : saveInfo_.entities) {
4398     auto *symbol{FindInScope(currScope(), name)};
4399     if (!symbol) {
4400       // error was reported
4401     } else if (saveInfo_.saveAll) {
4402       // C889 - note that pgi, ifort, xlf do not enforce this constraint
4403       Say2(name,
4404           "Explicit SAVE of '%s' is redundant due to global SAVE statement"_err_en_US,
4405           *saveInfo_.saveAll, "Global SAVE statement"_en_US);
4406     } else if (auto msg{CheckSaveAttr(*symbol)}) {
4407       Say(name, std::move(*msg));
4408       context().SetError(*symbol);
4409     } else {
4410       SetSaveAttr(*symbol);
4411     }
4412   }
4413   for (const SourceName &name : saveInfo_.commons) {
4414     if (auto *symbol{currScope().FindCommonBlock(name)}) {
4415       auto &objects{symbol->get<CommonBlockDetails>().objects()};
4416       if (objects.empty()) {
4417         if (currScope().kind() != Scope::Kind::Block) {
4418           Say(name,
4419               "'%s' appears as a COMMON block in a SAVE statement but not in"
4420               " a COMMON statement"_err_en_US);
4421         } else { // C1108
4422           Say(name,
4423               "SAVE statement in BLOCK construct may not contain a"
4424               " common block name '%s'"_err_en_US);
4425         }
4426       } else {
4427         for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
4428           SetSaveAttr(*object);
4429         }
4430       }
4431     }
4432   }
4433   if (saveInfo_.saveAll) {
4434     // Apply SAVE attribute to applicable symbols
4435     for (auto pair : currScope()) {
4436       auto &symbol{*pair.second};
4437       if (!CheckSaveAttr(symbol)) {
4438         SetSaveAttr(symbol);
4439       }
4440     }
4441   }
4442   saveInfo_ = {};
4443 }
4444 
4445 // If SAVE attribute can't be set on symbol, return error message.
4446 std::optional<MessageFixedText> DeclarationVisitor::CheckSaveAttr(
4447     const Symbol &symbol) {
4448   if (IsDummy(symbol)) {
4449     return "SAVE attribute may not be applied to dummy argument '%s'"_err_en_US;
4450   } else if (symbol.IsFuncResult()) {
4451     return "SAVE attribute may not be applied to function result '%s'"_err_en_US;
4452   } else if (symbol.has<ProcEntityDetails>() &&
4453       !symbol.attrs().test(Attr::POINTER)) {
4454     return "Procedure '%s' with SAVE attribute must also have POINTER attribute"_err_en_US;
4455   } else {
4456     return std::nullopt;
4457   }
4458 }
4459 
4460 // Record SAVEd names in saveInfo_.entities.
4461 Attrs DeclarationVisitor::HandleSaveName(const SourceName &name, Attrs attrs) {
4462   if (attrs.test(Attr::SAVE)) {
4463     AddSaveName(saveInfo_.entities, name);
4464   }
4465   return attrs;
4466 }
4467 
4468 // Record a name in a set of those to be saved.
4469 void DeclarationVisitor::AddSaveName(
4470     std::set<SourceName> &set, const SourceName &name) {
4471   auto pair{set.insert(name)};
4472   if (!pair.second) {
4473     Say2(name, "SAVE attribute was already specified on '%s'"_err_en_US,
4474         *pair.first, "Previous specification of SAVE attribute"_en_US);
4475   }
4476 }
4477 
4478 // Set the SAVE attribute on symbol unless it is implicitly saved anyway.
4479 void DeclarationVisitor::SetSaveAttr(Symbol &symbol) {
4480   if (!IsSaved(symbol)) {
4481     symbol.attrs().set(Attr::SAVE);
4482   }
4483 }
4484 
4485 // Check types of common block objects, now that they are known.
4486 void DeclarationVisitor::CheckCommonBlocks() {
4487   // check for empty common blocks
4488   for (const auto &pair : currScope().commonBlocks()) {
4489     const auto &symbol{*pair.second};
4490     if (symbol.get<CommonBlockDetails>().objects().empty() &&
4491         symbol.attrs().test(Attr::BIND_C)) {
4492       Say(symbol.name(),
4493           "'%s' appears as a COMMON block in a BIND statement but not in"
4494           " a COMMON statement"_err_en_US);
4495     }
4496   }
4497   // check objects in common blocks
4498   for (const auto &name : commonBlockInfo_.names) {
4499     const auto *symbol{currScope().FindSymbol(name)};
4500     if (!symbol) {
4501       continue;
4502     }
4503     const auto &attrs{symbol->attrs()};
4504     if (attrs.test(Attr::ALLOCATABLE)) {
4505       Say(name,
4506           "ALLOCATABLE object '%s' may not appear in a COMMON block"_err_en_US);
4507     } else if (attrs.test(Attr::BIND_C)) {
4508       Say(name,
4509           "Variable '%s' with BIND attribute may not appear in a COMMON block"_err_en_US);
4510     } else if (IsDummy(*symbol)) {
4511       Say(name,
4512           "Dummy argument '%s' may not appear in a COMMON block"_err_en_US);
4513     } else if (symbol->IsFuncResult()) {
4514       Say(name,
4515           "Function result '%s' may not appear in a COMMON block"_err_en_US);
4516     } else if (const DeclTypeSpec * type{symbol->GetType()}) {
4517       if (type->category() == DeclTypeSpec::ClassStar) {
4518         Say(name,
4519             "Unlimited polymorphic pointer '%s' may not appear in a COMMON block"_err_en_US);
4520       } else if (const auto *derived{type->AsDerived()}) {
4521         auto &typeSymbol{derived->typeSymbol()};
4522         if (!typeSymbol.attrs().test(Attr::BIND_C) &&
4523             !typeSymbol.get<DerivedTypeDetails>().sequence()) {
4524           Say(name,
4525               "Derived type '%s' in COMMON block must have the BIND or"
4526               " SEQUENCE attribute"_err_en_US);
4527         }
4528         CheckCommonBlockDerivedType(name, typeSymbol);
4529       }
4530     }
4531   }
4532   commonBlockInfo_ = {};
4533 }
4534 
4535 Symbol &DeclarationVisitor::MakeCommonBlockSymbol(const parser::Name &name) {
4536   return Resolve(name, currScope().MakeCommonBlock(name.source));
4537 }
4538 
4539 bool DeclarationVisitor::NameIsKnownOrIntrinsic(const parser::Name &name) {
4540   return FindSymbol(name) || HandleUnrestrictedSpecificIntrinsicFunction(name);
4541 }
4542 
4543 // Check if this derived type can be in a COMMON block.
4544 void DeclarationVisitor::CheckCommonBlockDerivedType(
4545     const SourceName &name, const Symbol &typeSymbol) {
4546   if (const auto *scope{typeSymbol.scope()}) {
4547     for (const auto &pair : *scope) {
4548       const Symbol &component{*pair.second};
4549       if (component.attrs().test(Attr::ALLOCATABLE)) {
4550         Say2(name,
4551             "Derived type variable '%s' may not appear in a COMMON block"
4552             " due to ALLOCATABLE component"_err_en_US,
4553             component.name(), "Component with ALLOCATABLE attribute"_en_US);
4554         return;
4555       }
4556       if (const auto *details{component.detailsIf<ObjectEntityDetails>()}) {
4557         if (details->init()) {
4558           Say2(name,
4559               "Derived type variable '%s' may not appear in a COMMON block"
4560               " due to component with default initialization"_err_en_US,
4561               component.name(), "Component with default initialization"_en_US);
4562           return;
4563         }
4564         if (const auto *type{details->type()}) {
4565           if (const auto *derived{type->AsDerived()}) {
4566             CheckCommonBlockDerivedType(name, derived->typeSymbol());
4567           }
4568         }
4569       }
4570     }
4571   }
4572 }
4573 
4574 bool DeclarationVisitor::HandleUnrestrictedSpecificIntrinsicFunction(
4575     const parser::Name &name) {
4576   if (auto interface{context().intrinsics().IsSpecificIntrinsicFunction(
4577           name.source.ToString())}) {
4578     // Unrestricted specific intrinsic function names (e.g., "cos")
4579     // are acceptable as procedure interfaces.
4580     Symbol &symbol{
4581         MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC})};
4582     if (interface->IsElemental()) {
4583       symbol.attrs().set(Attr::ELEMENTAL);
4584     }
4585     symbol.set_details(ProcEntityDetails{});
4586     Resolve(name, symbol);
4587     return true;
4588   } else {
4589     return false;
4590   }
4591 }
4592 
4593 // Checks for all locality-specs: LOCAL, LOCAL_INIT, and SHARED
4594 bool DeclarationVisitor::PassesSharedLocalityChecks(
4595     const parser::Name &name, Symbol &symbol) {
4596   if (!IsVariableName(symbol)) {
4597     SayLocalMustBeVariable(name, symbol); // C1124
4598     return false;
4599   }
4600   if (symbol.owner() == currScope()) { // C1125 and C1126
4601     SayAlreadyDeclared(name, symbol);
4602     return false;
4603   }
4604   return true;
4605 }
4606 
4607 // Checks for locality-specs LOCAL and LOCAL_INIT
4608 bool DeclarationVisitor::PassesLocalityChecks(
4609     const parser::Name &name, Symbol &symbol) {
4610   if (IsAllocatable(symbol)) { // C1128
4611     SayWithDecl(name, symbol,
4612         "ALLOCATABLE variable '%s' not allowed in a locality-spec"_err_en_US);
4613     return false;
4614   }
4615   if (IsOptional(symbol)) { // C1128
4616     SayWithDecl(name, symbol,
4617         "OPTIONAL argument '%s' not allowed in a locality-spec"_err_en_US);
4618     return false;
4619   }
4620   if (IsIntentIn(symbol)) { // C1128
4621     SayWithDecl(name, symbol,
4622         "INTENT IN argument '%s' not allowed in a locality-spec"_err_en_US);
4623     return false;
4624   }
4625   if (IsFinalizable(symbol)) { // C1128
4626     SayWithDecl(name, symbol,
4627         "Finalizable variable '%s' not allowed in a locality-spec"_err_en_US);
4628     return false;
4629   }
4630   if (IsCoarray(symbol)) { // C1128
4631     SayWithDecl(
4632         name, symbol, "Coarray '%s' not allowed in a locality-spec"_err_en_US);
4633     return false;
4634   }
4635   if (const DeclTypeSpec * type{symbol.GetType()}) {
4636     if (type->IsPolymorphic() && IsDummy(symbol) &&
4637         !IsPointer(symbol)) { // C1128
4638       SayWithDecl(name, symbol,
4639           "Nonpointer polymorphic argument '%s' not allowed in a "
4640           "locality-spec"_err_en_US);
4641       return false;
4642     }
4643   }
4644   if (IsAssumedSizeArray(symbol)) { // C1128
4645     SayWithDecl(name, symbol,
4646         "Assumed size array '%s' not allowed in a locality-spec"_err_en_US);
4647     return false;
4648   }
4649   if (std::optional<MessageFixedText> msg{
4650           WhyNotModifiable(symbol, currScope())}) {
4651     SayWithReason(name, symbol,
4652         "'%s' may not appear in a locality-spec because it is not "
4653         "definable"_err_en_US,
4654         std::move(*msg));
4655     return false;
4656   }
4657   return PassesSharedLocalityChecks(name, symbol);
4658 }
4659 
4660 Symbol &DeclarationVisitor::FindOrDeclareEnclosingEntity(
4661     const parser::Name &name) {
4662   Symbol *prev{FindSymbol(name)};
4663   if (!prev) {
4664     // Declare the name as an object in the enclosing scope so that
4665     // the name can't be repurposed there later as something else.
4666     prev = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
4667     ConvertToObjectEntity(*prev);
4668     ApplyImplicitRules(*prev);
4669   }
4670   return *prev;
4671 }
4672 
4673 Symbol *DeclarationVisitor::DeclareLocalEntity(const parser::Name &name) {
4674   Symbol &prev{FindOrDeclareEnclosingEntity(name)};
4675   if (!PassesLocalityChecks(name, prev)) {
4676     return nullptr;
4677   }
4678   Symbol &symbol{MakeSymbol(name, HostAssocDetails{prev})};
4679   name.symbol = &symbol;
4680   return &symbol;
4681 }
4682 
4683 Symbol *DeclarationVisitor::DeclareStatementEntity(const parser::Name &name,
4684     const std::optional<parser::IntegerTypeSpec> &type) {
4685   const DeclTypeSpec *declTypeSpec{nullptr};
4686   if (auto *prev{FindSymbol(name)}) {
4687     if (prev->owner() == currScope()) {
4688       SayAlreadyDeclared(name, *prev);
4689       return nullptr;
4690     }
4691     name.symbol = nullptr;
4692     declTypeSpec = prev->GetType();
4693   }
4694   Symbol &symbol{DeclareEntity<ObjectEntityDetails>(name, {})};
4695   if (!symbol.has<ObjectEntityDetails>()) {
4696     return nullptr; // error was reported in DeclareEntity
4697   }
4698   if (type) {
4699     declTypeSpec = ProcessTypeSpec(*type);
4700   }
4701   if (declTypeSpec) {
4702     // Subtlety: Don't let a "*length" specifier (if any is pending) affect the
4703     // declaration of this implied DO loop control variable.
4704     auto restorer{
4705         common::ScopedSet(charInfo_.length, std::optional<ParamValue>{})};
4706     SetType(name, *declTypeSpec);
4707   } else {
4708     ApplyImplicitRules(symbol);
4709   }
4710   return Resolve(name, &symbol);
4711 }
4712 
4713 // Set the type of an entity or report an error.
4714 void DeclarationVisitor::SetType(
4715     const parser::Name &name, const DeclTypeSpec &type) {
4716   CHECK(name.symbol);
4717   auto &symbol{*name.symbol};
4718   if (charInfo_.length) { // Declaration has "*length" (R723)
4719     auto length{std::move(*charInfo_.length)};
4720     charInfo_.length.reset();
4721     if (type.category() == DeclTypeSpec::Character) {
4722       auto kind{type.characterTypeSpec().kind()};
4723       // Recurse with correct type.
4724       SetType(name,
4725           currScope().MakeCharacterType(std::move(length), std::move(kind)));
4726       return;
4727     } else { // C753
4728       Say(name,
4729           "A length specifier cannot be used to declare the non-character entity '%s'"_err_en_US);
4730     }
4731   }
4732   auto *prevType{symbol.GetType()};
4733   if (!prevType) {
4734     symbol.SetType(type);
4735   } else if (symbol.has<UseDetails>()) {
4736     // error recovery case, redeclaration of use-associated name
4737   } else if (!symbol.test(Symbol::Flag::Implicit)) {
4738     SayWithDecl(
4739         name, symbol, "The type of '%s' has already been declared"_err_en_US);
4740     context().SetError(symbol);
4741   } else if (type != *prevType) {
4742     SayWithDecl(name, symbol,
4743         "The type of '%s' has already been implicitly declared"_err_en_US);
4744     context().SetError(symbol);
4745   } else {
4746     symbol.set(Symbol::Flag::Implicit, false);
4747   }
4748 }
4749 
4750 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveDerivedType(
4751     const parser::Name &name) {
4752   Symbol *symbol{FindSymbol(NonDerivedTypeScope(), name)};
4753   if (!symbol || symbol->has<UnknownDetails>()) {
4754     if (allowForwardReferenceToDerivedType()) {
4755       if (!symbol) {
4756         symbol = &MakeSymbol(InclusiveScope(), name.source, Attrs{});
4757         Resolve(name, *symbol);
4758       };
4759       DerivedTypeDetails details;
4760       details.set_isForwardReferenced();
4761       symbol->set_details(std::move(details));
4762     } else { // C732
4763       Say(name, "Derived type '%s' not found"_err_en_US);
4764       return std::nullopt;
4765     }
4766   }
4767   if (CheckUseError(name)) {
4768     return std::nullopt;
4769   }
4770   symbol = &symbol->GetUltimate();
4771   if (auto *details{symbol->detailsIf<GenericDetails>()}) {
4772     if (details->derivedType()) {
4773       symbol = details->derivedType();
4774     }
4775   }
4776   if (symbol->has<DerivedTypeDetails>()) {
4777     return DerivedTypeSpec{name.source, *symbol};
4778   } else {
4779     Say(name, "'%s' is not a derived type"_err_en_US);
4780     return std::nullopt;
4781   }
4782 }
4783 
4784 std::optional<DerivedTypeSpec> DeclarationVisitor::ResolveExtendsType(
4785     const parser::Name &typeName, const parser::Name *extendsName) {
4786   if (!extendsName) {
4787     return std::nullopt;
4788   } else if (typeName.source == extendsName->source) {
4789     Say(extendsName->source,
4790         "Derived type '%s' cannot extend itself"_err_en_US);
4791     return std::nullopt;
4792   } else {
4793     return ResolveDerivedType(*extendsName);
4794   }
4795 }
4796 
4797 Symbol *DeclarationVisitor::NoteInterfaceName(const parser::Name &name) {
4798   // The symbol is checked later by CheckExplicitInterface() and
4799   // CheckBindings().  It can be a forward reference.
4800   if (!NameIsKnownOrIntrinsic(name)) {
4801     Symbol &symbol{MakeSymbol(InclusiveScope(), name.source, Attrs{})};
4802     Resolve(name, symbol);
4803   }
4804   return name.symbol;
4805 }
4806 
4807 void DeclarationVisitor::CheckExplicitInterface(const parser::Name &name) {
4808   if (const Symbol * symbol{name.symbol}) {
4809     if (!symbol->HasExplicitInterface()) {
4810       Say(name,
4811           "'%s' must be an abstract interface or a procedure with "
4812           "an explicit interface"_err_en_US,
4813           symbol->name());
4814     }
4815   }
4816 }
4817 
4818 // Create a symbol for a type parameter, component, or procedure binding in
4819 // the current derived type scope. Return false on error.
4820 Symbol *DeclarationVisitor::MakeTypeSymbol(
4821     const parser::Name &name, Details &&details) {
4822   return Resolve(name, MakeTypeSymbol(name.source, std::move(details)));
4823 }
4824 Symbol *DeclarationVisitor::MakeTypeSymbol(
4825     const SourceName &name, Details &&details) {
4826   Scope &derivedType{currScope()};
4827   CHECK(derivedType.IsDerivedType());
4828   if (auto *symbol{FindInScope(derivedType, name)}) { // C742
4829     Say2(name,
4830         "Type parameter, component, or procedure binding '%s'"
4831         " already defined in this type"_err_en_US,
4832         *symbol, "Previous definition of '%s'"_en_US);
4833     return nullptr;
4834   } else {
4835     auto attrs{GetAttrs()};
4836     // Apply binding-private-stmt if present and this is a procedure binding
4837     if (derivedTypeInfo_.privateBindings &&
4838         !attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE}) &&
4839         std::holds_alternative<ProcBindingDetails>(details)) {
4840       attrs.set(Attr::PRIVATE);
4841     }
4842     Symbol &result{MakeSymbol(name, attrs, std::move(details))};
4843     if (result.has<TypeParamDetails>()) {
4844       derivedType.symbol()->get<DerivedTypeDetails>().add_paramDecl(result);
4845     }
4846     return &result;
4847   }
4848 }
4849 
4850 // Return true if it is ok to declare this component in the current scope.
4851 // Otherwise, emit an error and return false.
4852 bool DeclarationVisitor::OkToAddComponent(
4853     const parser::Name &name, const Symbol *extends) {
4854   for (const Scope *scope{&currScope()}; scope;) {
4855     CHECK(scope->IsDerivedType());
4856     if (auto *prev{FindInScope(*scope, name)}) {
4857       if (!prev->test(Symbol::Flag::Error)) {
4858         auto msg{""_en_US};
4859         if (extends) {
4860           msg = "Type cannot be extended as it has a component named"
4861                 " '%s'"_err_en_US;
4862         } else if (prev->test(Symbol::Flag::ParentComp)) {
4863           msg = "'%s' is a parent type of this type and so cannot be"
4864                 " a component"_err_en_US;
4865         } else if (scope != &currScope()) {
4866           msg = "Component '%s' is already declared in a parent of this"
4867                 " derived type"_err_en_US;
4868         } else {
4869           msg = "Component '%s' is already declared in this"
4870                 " derived type"_err_en_US;
4871         }
4872         Say2(name, std::move(msg), *prev, "Previous declaration of '%s'"_en_US);
4873       }
4874       return false;
4875     }
4876     if (scope == &currScope() && extends) {
4877       // The parent component has not yet been added to the scope.
4878       scope = extends->scope();
4879     } else {
4880       scope = scope->GetDerivedTypeParent();
4881     }
4882   }
4883   return true;
4884 }
4885 
4886 ParamValue DeclarationVisitor::GetParamValue(
4887     const parser::TypeParamValue &x, common::TypeParamAttr attr) {
4888   return std::visit(
4889       common::visitors{
4890           [=](const parser::ScalarIntExpr &x) { // C704
4891             return ParamValue{EvaluateIntExpr(x), attr};
4892           },
4893           [=](const parser::Star &) { return ParamValue::Assumed(attr); },
4894           [=](const parser::TypeParamValue::Deferred &) {
4895             return ParamValue::Deferred(attr);
4896           },
4897       },
4898       x.u);
4899 }
4900 
4901 // ConstructVisitor implementation
4902 
4903 void ConstructVisitor::ResolveIndexName(
4904     const parser::ConcurrentControl &control) {
4905   const parser::Name &name{std::get<parser::Name>(control.t)};
4906   auto *prev{FindSymbol(name)};
4907   if (prev) {
4908     if (prev->owner().kind() == Scope::Kind::Forall ||
4909         prev->owner() == currScope()) {
4910       SayAlreadyDeclared(name, *prev);
4911       return;
4912     }
4913     name.symbol = nullptr;
4914   }
4915   auto &symbol{DeclareObjectEntity(name, {})};
4916 
4917   if (symbol.GetType()) {
4918     // type came from explicit type-spec
4919   } else if (!prev) {
4920     ApplyImplicitRules(symbol);
4921   } else if (!prev->has<ObjectEntityDetails>() && !prev->has<EntityDetails>()) {
4922     Say2(name, "Index name '%s' conflicts with existing identifier"_err_en_US,
4923         *prev, "Previous declaration of '%s'"_en_US);
4924     return;
4925   } else {
4926     if (const auto *type{prev->GetType()}) {
4927       symbol.SetType(*type);
4928     }
4929     if (prev->IsObjectArray()) {
4930       SayWithDecl(name, *prev, "Index variable '%s' is not scalar"_err_en_US);
4931       return;
4932     }
4933   }
4934   EvaluateExpr(parser::Scalar{parser::Integer{common::Clone(name)}});
4935 }
4936 
4937 // We need to make sure that all of the index-names get declared before the
4938 // expressions in the loop control are evaluated so that references to the
4939 // index-names in the expressions are correctly detected.
4940 bool ConstructVisitor::Pre(const parser::ConcurrentHeader &header) {
4941   BeginDeclTypeSpec();
4942   Walk(std::get<std::optional<parser::IntegerTypeSpec>>(header.t));
4943   const auto &controls{
4944       std::get<std::list<parser::ConcurrentControl>>(header.t)};
4945   for (const auto &control : controls) {
4946     ResolveIndexName(control);
4947   }
4948   Walk(controls);
4949   Walk(std::get<std::optional<parser::ScalarLogicalExpr>>(header.t));
4950   EndDeclTypeSpec();
4951   return false;
4952 }
4953 
4954 bool ConstructVisitor::Pre(const parser::LocalitySpec::Local &x) {
4955   for (auto &name : x.v) {
4956     if (auto *symbol{DeclareLocalEntity(name)}) {
4957       symbol->set(Symbol::Flag::LocalityLocal);
4958     }
4959   }
4960   return false;
4961 }
4962 
4963 bool ConstructVisitor::Pre(const parser::LocalitySpec::LocalInit &x) {
4964   for (auto &name : x.v) {
4965     if (auto *symbol{DeclareLocalEntity(name)}) {
4966       symbol->set(Symbol::Flag::LocalityLocalInit);
4967     }
4968   }
4969   return false;
4970 }
4971 
4972 bool ConstructVisitor::Pre(const parser::LocalitySpec::Shared &x) {
4973   for (const auto &name : x.v) {
4974     if (!FindSymbol(name)) {
4975       Say(name, "Variable '%s' with SHARED locality implicitly declared"_en_US);
4976     }
4977     Symbol &prev{FindOrDeclareEnclosingEntity(name)};
4978     if (PassesSharedLocalityChecks(name, prev)) {
4979       auto &symbol{MakeSymbol(name, HostAssocDetails{prev})};
4980       symbol.set(Symbol::Flag::LocalityShared);
4981       name.symbol = &symbol; // override resolution to parent
4982     }
4983   }
4984   return false;
4985 }
4986 
4987 bool ConstructVisitor::Pre(const parser::AcSpec &x) {
4988   ProcessTypeSpec(x.type);
4989   PushScope(Scope::Kind::ImpliedDos, nullptr);
4990   Walk(x.values);
4991   PopScope();
4992   return false;
4993 }
4994 
4995 bool ConstructVisitor::Pre(const parser::AcImpliedDo &x) {
4996   auto &values{std::get<std::list<parser::AcValue>>(x.t)};
4997   auto &control{std::get<parser::AcImpliedDoControl>(x.t)};
4998   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(control.t)};
4999   auto &bounds{std::get<parser::AcImpliedDoControl::Bounds>(control.t)};
5000   DeclareStatementEntity(bounds.name.thing.thing, type);
5001   Walk(bounds);
5002   Walk(values);
5003   return false;
5004 }
5005 
5006 bool ConstructVisitor::Pre(const parser::DataImpliedDo &x) {
5007   auto &objects{std::get<std::list<parser::DataIDoObject>>(x.t)};
5008   auto &type{std::get<std::optional<parser::IntegerTypeSpec>>(x.t)};
5009   auto &bounds{std::get<parser::DataImpliedDo::Bounds>(x.t)};
5010   DeclareStatementEntity(bounds.name.thing.thing, type);
5011   Walk(bounds);
5012   Walk(objects);
5013   return false;
5014 }
5015 
5016 // Sets InDataStmt flag on a variable (or misidentified function) in a DATA
5017 // statement so that the predicate IsInitialized(base symbol) will be true
5018 // during semantic analysis before the symbol's initializer is constructed.
5019 bool ConstructVisitor::Pre(const parser::DataIDoObject &x) {
5020   std::visit(
5021       common::visitors{
5022           [&](const parser::Scalar<Indirection<parser::Designator>> &y) {
5023             Walk(y.thing.value());
5024             const parser::Name &first{parser::GetFirstName(y.thing.value())};
5025             if (first.symbol) {
5026               first.symbol->set(Symbol::Flag::InDataStmt);
5027             }
5028           },
5029           [&](const Indirection<parser::DataImpliedDo> &y) { Walk(y.value()); },
5030       },
5031       x.u);
5032   return false;
5033 }
5034 
5035 bool ConstructVisitor::Pre(const parser::DataStmtObject &x) {
5036   std::visit(common::visitors{
5037                  [&](const Indirection<parser::Variable> &y) {
5038                    Walk(y.value());
5039                    const parser::Name &first{parser::GetFirstName(y.value())};
5040                    if (first.symbol) {
5041                      first.symbol->set(Symbol::Flag::InDataStmt);
5042                    }
5043                  },
5044                  [&](const parser::DataImpliedDo &y) {
5045                    PushScope(Scope::Kind::ImpliedDos, nullptr);
5046                    Walk(y);
5047                    PopScope();
5048                  },
5049              },
5050       x.u);
5051   return false;
5052 }
5053 
5054 bool ConstructVisitor::Pre(const parser::DataStmtValue &x) {
5055   const auto &data{std::get<parser::DataStmtConstant>(x.t)};
5056   auto &mutableData{const_cast<parser::DataStmtConstant &>(data)};
5057   if (auto *elem{parser::Unwrap<parser::ArrayElement>(mutableData)}) {
5058     if (const auto *name{std::get_if<parser::Name>(&elem->base.u)}) {
5059       if (const Symbol * symbol{FindSymbol(*name)}) {
5060         if (const Symbol * ultimate{GetAssociationRoot(*symbol)}) {
5061           if (ultimate->has<DerivedTypeDetails>()) {
5062             mutableData.u = parser::Constant<parser::StructureConstructor>{
5063                 elem->ConvertToStructureConstructor(
5064                     DerivedTypeSpec{name->source, *ultimate})};
5065           }
5066         }
5067       }
5068     }
5069   }
5070   return true;
5071 }
5072 
5073 bool ConstructVisitor::Pre(const parser::DoConstruct &x) {
5074   if (x.IsDoConcurrent()) {
5075     PushScope(Scope::Kind::Block, nullptr);
5076   }
5077   return true;
5078 }
5079 void ConstructVisitor::Post(const parser::DoConstruct &x) {
5080   if (x.IsDoConcurrent()) {
5081     PopScope();
5082   }
5083 }
5084 
5085 bool ConstructVisitor::Pre(const parser::ForallConstruct &) {
5086   PushScope(Scope::Kind::Forall, nullptr);
5087   return true;
5088 }
5089 void ConstructVisitor::Post(const parser::ForallConstruct &) { PopScope(); }
5090 bool ConstructVisitor::Pre(const parser::ForallStmt &) {
5091   PushScope(Scope::Kind::Forall, nullptr);
5092   return true;
5093 }
5094 void ConstructVisitor::Post(const parser::ForallStmt &) { PopScope(); }
5095 
5096 bool ConstructVisitor::Pre(const parser::BlockStmt &x) {
5097   CheckDef(x.v);
5098   PushScope(Scope::Kind::Block, nullptr);
5099   return false;
5100 }
5101 bool ConstructVisitor::Pre(const parser::EndBlockStmt &x) {
5102   PopScope();
5103   CheckRef(x.v);
5104   return false;
5105 }
5106 
5107 void ConstructVisitor::Post(const parser::Selector &x) {
5108   GetCurrentAssociation().selector = ResolveSelector(x);
5109 }
5110 
5111 bool ConstructVisitor::Pre(const parser::AssociateStmt &x) {
5112   CheckDef(x.t);
5113   PushScope(Scope::Kind::Block, nullptr);
5114   PushAssociation();
5115   return true;
5116 }
5117 void ConstructVisitor::Post(const parser::EndAssociateStmt &x) {
5118   PopAssociation();
5119   PopScope();
5120   CheckRef(x.v);
5121 }
5122 
5123 void ConstructVisitor::Post(const parser::Association &x) {
5124   const auto &name{std::get<parser::Name>(x.t)};
5125   GetCurrentAssociation().name = &name;
5126   if (auto *symbol{MakeAssocEntity()}) {
5127     SetTypeFromAssociation(*symbol);
5128     SetAttrsFromAssociation(*symbol);
5129   }
5130   GetCurrentAssociation() = {}; // clean for further parser::Association.
5131 }
5132 
5133 bool ConstructVisitor::Pre(const parser::ChangeTeamStmt &x) {
5134   CheckDef(x.t);
5135   PushScope(Scope::Kind::Block, nullptr);
5136   PushAssociation();
5137   return true;
5138 }
5139 
5140 void ConstructVisitor::Post(const parser::CoarrayAssociation &x) {
5141   const auto &decl{std::get<parser::CodimensionDecl>(x.t)};
5142   const auto &name{std::get<parser::Name>(decl.t)};
5143   if (auto *symbol{FindInScope(currScope(), name)}) {
5144     const auto &selector{std::get<parser::Selector>(x.t)};
5145     if (auto sel{ResolveSelector(selector)}) {
5146       const Symbol *whole{UnwrapWholeSymbolDataRef(sel.expr)};
5147       if (!whole || whole->Corank() == 0) {
5148         Say(sel.source, // C1116
5149             "Selector in coarray association must name a coarray"_err_en_US);
5150       } else if (auto dynType{sel.expr->GetType()}) {
5151         if (!symbol->GetType()) {
5152           symbol->SetType(ToDeclTypeSpec(std::move(*dynType)));
5153         }
5154       }
5155     }
5156   }
5157 }
5158 
5159 void ConstructVisitor::Post(const parser::EndChangeTeamStmt &x) {
5160   PopAssociation();
5161   PopScope();
5162   CheckRef(x.t);
5163 }
5164 
5165 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct &) {
5166   PushAssociation();
5167   return true;
5168 }
5169 
5170 void ConstructVisitor::Post(const parser::SelectTypeConstruct &) {
5171   PopAssociation();
5172 }
5173 
5174 void ConstructVisitor::Post(const parser::SelectTypeStmt &x) {
5175   auto &association{GetCurrentAssociation()};
5176   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5177     // This isn't a name in the current scope, it is in each TypeGuardStmt
5178     MakePlaceholder(*name, MiscDetails::Kind::SelectTypeAssociateName);
5179     association.name = &*name;
5180     auto exprType{association.selector.expr->GetType()};
5181     if (exprType && !exprType->IsPolymorphic()) { // C1159
5182       Say(association.selector.source,
5183           "Selector '%s' in SELECT TYPE statement must be "
5184           "polymorphic"_err_en_US);
5185     }
5186   } else {
5187     if (const Symbol *
5188         whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5189       ConvertToObjectEntity(const_cast<Symbol &>(*whole));
5190       if (!IsVariableName(*whole)) {
5191         Say(association.selector.source, // C901
5192             "Selector is not a variable"_err_en_US);
5193         association = {};
5194       }
5195       if (const DeclTypeSpec * type{whole->GetType()}) {
5196         if (!type->IsPolymorphic()) { // C1159
5197           Say(association.selector.source,
5198               "Selector '%s' in SELECT TYPE statement must be "
5199               "polymorphic"_err_en_US);
5200         }
5201       }
5202     } else {
5203       Say(association.selector.source, // C1157
5204           "Selector is not a named variable: 'associate-name =>' is required"_err_en_US);
5205       association = {};
5206     }
5207   }
5208 }
5209 
5210 void ConstructVisitor::Post(const parser::SelectRankStmt &x) {
5211   auto &association{GetCurrentAssociation()};
5212   if (const std::optional<parser::Name> &name{std::get<1>(x.t)}) {
5213     // This isn't a name in the current scope, it is in each SelectRankCaseStmt
5214     MakePlaceholder(*name, MiscDetails::Kind::SelectRankAssociateName);
5215     association.name = &*name;
5216   }
5217 }
5218 
5219 bool ConstructVisitor::Pre(const parser::SelectTypeConstruct::TypeCase &) {
5220   PushScope(Scope::Kind::Block, nullptr);
5221   return true;
5222 }
5223 void ConstructVisitor::Post(const parser::SelectTypeConstruct::TypeCase &) {
5224   PopScope();
5225 }
5226 
5227 bool ConstructVisitor::Pre(const parser::SelectRankConstruct::RankCase &) {
5228   PushScope(Scope::Kind::Block, nullptr);
5229   return true;
5230 }
5231 void ConstructVisitor::Post(const parser::SelectRankConstruct::RankCase &) {
5232   PopScope();
5233 }
5234 
5235 void ConstructVisitor::Post(const parser::TypeGuardStmt::Guard &x) {
5236   if (auto *symbol{MakeAssocEntity()}) {
5237     if (std::holds_alternative<parser::Default>(x.u)) {
5238       SetTypeFromAssociation(*symbol);
5239     } else if (const auto *type{GetDeclTypeSpec()}) {
5240       symbol->SetType(*type);
5241     }
5242     SetAttrsFromAssociation(*symbol);
5243   }
5244 }
5245 
5246 void ConstructVisitor::Post(const parser::SelectRankCaseStmt::Rank &x) {
5247   if (auto *symbol{MakeAssocEntity()}) {
5248     SetTypeFromAssociation(*symbol);
5249     SetAttrsFromAssociation(*symbol);
5250     if (const auto *init{std::get_if<parser::ScalarIntConstantExpr>(&x.u)}) {
5251       MaybeIntExpr expr{EvaluateIntExpr(*init)};
5252       if (auto val{evaluate::ToInt64(expr)}) {
5253         auto &details{symbol->get<AssocEntityDetails>()};
5254         details.set_rank(*val);
5255       }
5256     }
5257   }
5258 }
5259 
5260 bool ConstructVisitor::Pre(const parser::SelectRankConstruct &) {
5261   PushAssociation();
5262   return true;
5263 }
5264 
5265 void ConstructVisitor::Post(const parser::SelectRankConstruct &) {
5266   PopAssociation();
5267 }
5268 
5269 bool ConstructVisitor::CheckDef(const std::optional<parser::Name> &x) {
5270   if (x) {
5271     MakeSymbol(*x, MiscDetails{MiscDetails::Kind::ConstructName});
5272   }
5273   return true;
5274 }
5275 
5276 void ConstructVisitor::CheckRef(const std::optional<parser::Name> &x) {
5277   if (x) {
5278     // Just add an occurrence of this name; checking is done in ValidateLabels
5279     FindSymbol(*x);
5280   }
5281 }
5282 
5283 // Make a symbol representing an associating entity from current association.
5284 Symbol *ConstructVisitor::MakeAssocEntity() {
5285   Symbol *symbol{nullptr};
5286   auto &association{GetCurrentAssociation()};
5287   if (association.name) {
5288     symbol = &MakeSymbol(*association.name, UnknownDetails{});
5289     if (symbol->has<AssocEntityDetails>() && symbol->owner() == currScope()) {
5290       Say(*association.name, // C1104
5291           "The associate name '%s' is already used in this associate statement"_err_en_US);
5292       return nullptr;
5293     }
5294   } else if (const Symbol *
5295       whole{UnwrapWholeSymbolDataRef(association.selector.expr)}) {
5296     symbol = &MakeSymbol(whole->name());
5297   } else {
5298     return nullptr;
5299   }
5300   if (auto &expr{association.selector.expr}) {
5301     symbol->set_details(AssocEntityDetails{common::Clone(*expr)});
5302   } else {
5303     symbol->set_details(AssocEntityDetails{});
5304   }
5305   return symbol;
5306 }
5307 
5308 // Set the type of symbol based on the current association selector.
5309 void ConstructVisitor::SetTypeFromAssociation(Symbol &symbol) {
5310   auto &details{symbol.get<AssocEntityDetails>()};
5311   const MaybeExpr *pexpr{&details.expr()};
5312   if (!*pexpr) {
5313     pexpr = &GetCurrentAssociation().selector.expr;
5314   }
5315   if (*pexpr) {
5316     const SomeExpr &expr{**pexpr};
5317     if (std::optional<evaluate::DynamicType> type{expr.GetType()}) {
5318       if (const auto *charExpr{
5319               evaluate::UnwrapExpr<evaluate::Expr<evaluate::SomeCharacter>>(
5320                   expr)}) {
5321         symbol.SetType(ToDeclTypeSpec(std::move(*type),
5322             FoldExpr(
5323                 std::visit([](const auto &kindChar) { return kindChar.LEN(); },
5324                     charExpr->u))));
5325       } else {
5326         symbol.SetType(ToDeclTypeSpec(std::move(*type)));
5327       }
5328     } else {
5329       // BOZ literals, procedure designators, &c. are not acceptable
5330       Say(symbol.name(), "Associate name '%s' must have a type"_err_en_US);
5331     }
5332   }
5333 }
5334 
5335 // If current selector is a variable, set some of its attributes on symbol.
5336 void ConstructVisitor::SetAttrsFromAssociation(Symbol &symbol) {
5337   Attrs attrs{evaluate::GetAttrs(GetCurrentAssociation().selector.expr)};
5338   symbol.attrs() |= attrs &
5339       Attrs{Attr::TARGET, Attr::ASYNCHRONOUS, Attr::VOLATILE, Attr::CONTIGUOUS};
5340   if (attrs.test(Attr::POINTER)) {
5341     symbol.attrs().set(Attr::TARGET);
5342   }
5343 }
5344 
5345 ConstructVisitor::Selector ConstructVisitor::ResolveSelector(
5346     const parser::Selector &x) {
5347   return std::visit(common::visitors{
5348                         [&](const parser::Expr &expr) {
5349                           return Selector{expr.source, EvaluateExpr(expr)};
5350                         },
5351                         [&](const parser::Variable &var) {
5352                           return Selector{var.GetSource(), EvaluateExpr(var)};
5353                         },
5354                     },
5355       x.u);
5356 }
5357 
5358 ConstructVisitor::Association &ConstructVisitor::GetCurrentAssociation() {
5359   CHECK(!associationStack_.empty());
5360   return associationStack_.back();
5361 }
5362 
5363 void ConstructVisitor::PushAssociation() {
5364   associationStack_.emplace_back(Association{});
5365 }
5366 
5367 void ConstructVisitor::PopAssociation() {
5368   CHECK(!associationStack_.empty());
5369   associationStack_.pop_back();
5370 }
5371 
5372 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5373     evaluate::DynamicType &&type) {
5374   switch (type.category()) {
5375     SWITCH_COVERS_ALL_CASES
5376   case common::TypeCategory::Integer:
5377   case common::TypeCategory::Real:
5378   case common::TypeCategory::Complex:
5379     return context().MakeNumericType(type.category(), type.kind());
5380   case common::TypeCategory::Logical:
5381     return context().MakeLogicalType(type.kind());
5382   case common::TypeCategory::Derived:
5383     if (type.IsAssumedType()) {
5384       return currScope().MakeTypeStarType();
5385     } else if (type.IsUnlimitedPolymorphic()) {
5386       return currScope().MakeClassStarType();
5387     } else {
5388       return currScope().MakeDerivedType(
5389           type.IsPolymorphic() ? DeclTypeSpec::ClassDerived
5390                                : DeclTypeSpec::TypeDerived,
5391           common::Clone(type.GetDerivedTypeSpec())
5392 
5393       );
5394     }
5395   case common::TypeCategory::Character:
5396     CRASH_NO_CASE;
5397   }
5398 }
5399 
5400 const DeclTypeSpec &ConstructVisitor::ToDeclTypeSpec(
5401     evaluate::DynamicType &&type, MaybeSubscriptIntExpr &&length) {
5402   CHECK(type.category() == common::TypeCategory::Character);
5403   if (length) {
5404     return currScope().MakeCharacterType(
5405         ParamValue{SomeIntExpr{*std::move(length)}, common::TypeParamAttr::Len},
5406         KindExpr{type.kind()});
5407   } else {
5408     return currScope().MakeCharacterType(
5409         ParamValue::Deferred(common::TypeParamAttr::Len),
5410         KindExpr{type.kind()});
5411   }
5412 }
5413 
5414 // ResolveNamesVisitor implementation
5415 
5416 // Ensures that bare undeclared intrinsic procedure names passed as actual
5417 // arguments get recognized as being intrinsics.
5418 bool ResolveNamesVisitor::Pre(const parser::ActualArg &arg) {
5419   if (const auto *expr{std::get_if<Indirection<parser::Expr>>(&arg.u)}) {
5420     if (const auto *designator{
5421             std::get_if<Indirection<parser::Designator>>(&expr->value().u)}) {
5422       if (const auto *dataRef{
5423               std::get_if<parser::DataRef>(&designator->value().u)}) {
5424         if (const auto *name{std::get_if<parser::Name>(&dataRef->u)}) {
5425           NameIsKnownOrIntrinsic(*name);
5426         }
5427       }
5428     }
5429   }
5430   return true;
5431 }
5432 
5433 bool ResolveNamesVisitor::Pre(const parser::FunctionReference &x) {
5434   HandleCall(Symbol::Flag::Function, x.v);
5435   return false;
5436 }
5437 bool ResolveNamesVisitor::Pre(const parser::CallStmt &x) {
5438   HandleCall(Symbol::Flag::Subroutine, x.v);
5439   return false;
5440 }
5441 
5442 bool ResolveNamesVisitor::Pre(const parser::ImportStmt &x) {
5443   auto &scope{currScope()};
5444   // Check C896 and C899: where IMPORT statements are allowed
5445   switch (scope.kind()) {
5446   case Scope::Kind::Module:
5447     if (scope.IsModule()) {
5448       Say("IMPORT is not allowed in a module scoping unit"_err_en_US);
5449       return false;
5450     } else if (x.kind == common::ImportKind::None) {
5451       Say("IMPORT,NONE is not allowed in a submodule scoping unit"_err_en_US);
5452       return false;
5453     }
5454     break;
5455   case Scope::Kind::MainProgram:
5456     Say("IMPORT is not allowed in a main program scoping unit"_err_en_US);
5457     return false;
5458   case Scope::Kind::Subprogram:
5459     if (scope.parent().IsGlobal()) {
5460       Say("IMPORT is not allowed in an external subprogram scoping unit"_err_en_US);
5461       return false;
5462     }
5463     break;
5464   case Scope::Kind::BlockData: // C1415 (in part)
5465     Say("IMPORT is not allowed in a BLOCK DATA subprogram"_err_en_US);
5466     return false;
5467   default:;
5468   }
5469   if (auto error{scope.SetImportKind(x.kind)}) {
5470     Say(std::move(*error));
5471   }
5472   for (auto &name : x.names) {
5473     if (FindSymbol(scope.parent(), name)) {
5474       scope.add_importName(name.source);
5475     } else {
5476       Say(name, "'%s' not found in host scope"_err_en_US);
5477     }
5478   }
5479   prevImportStmt_ = currStmtSource();
5480   return false;
5481 }
5482 
5483 const parser::Name *DeclarationVisitor::ResolveStructureComponent(
5484     const parser::StructureComponent &x) {
5485   return FindComponent(ResolveDataRef(x.base), x.component);
5486 }
5487 
5488 const parser::Name *DeclarationVisitor::ResolveDesignator(
5489     const parser::Designator &x) {
5490   return std::visit(
5491       common::visitors{
5492           [&](const parser::DataRef &x) { return ResolveDataRef(x); },
5493           [&](const parser::Substring &x) {
5494             return ResolveDataRef(std::get<parser::DataRef>(x.t));
5495           },
5496       },
5497       x.u);
5498 }
5499 
5500 const parser::Name *DeclarationVisitor::ResolveDataRef(
5501     const parser::DataRef &x) {
5502   return std::visit(
5503       common::visitors{
5504           [=](const parser::Name &y) { return ResolveName(y); },
5505           [=](const Indirection<parser::StructureComponent> &y) {
5506             return ResolveStructureComponent(y.value());
5507           },
5508           [&](const Indirection<parser::ArrayElement> &y) {
5509             Walk(y.value().subscripts);
5510             return ResolveDataRef(y.value().base);
5511           },
5512           [&](const Indirection<parser::CoindexedNamedObject> &y) {
5513             Walk(y.value().imageSelector);
5514             return ResolveDataRef(y.value().base);
5515           },
5516       },
5517       x.u);
5518 }
5519 
5520 const parser::Name *DeclarationVisitor::ResolveVariable(
5521     const parser::Variable &x) {
5522   return std::visit(
5523       common::visitors{
5524           [&](const Indirection<parser::Designator> &y) {
5525             return ResolveDesignator(y.value());
5526           },
5527           [&](const Indirection<parser::FunctionReference> &y) {
5528             const auto &proc{
5529                 std::get<parser::ProcedureDesignator>(y.value().v.t)};
5530             return std::visit(common::visitors{
5531                                   [&](const parser::Name &z) { return &z; },
5532                                   [&](const parser::ProcComponentRef &z) {
5533                                     return ResolveStructureComponent(z.v.thing);
5534                                   },
5535                               },
5536                 proc.u);
5537           },
5538       },
5539       x.u);
5540 }
5541 
5542 // If implicit types are allowed, ensure name is in the symbol table.
5543 // Otherwise, report an error if it hasn't been declared.
5544 const parser::Name *DeclarationVisitor::ResolveName(const parser::Name &name) {
5545   if (Symbol * symbol{FindSymbol(name)}) {
5546     if (CheckUseError(name)) {
5547       return nullptr; // reported an error
5548     }
5549     if (IsDummy(*symbol) ||
5550         (!symbol->GetType() && FindCommonBlockContaining(*symbol))) {
5551       ConvertToObjectEntity(*symbol);
5552       ApplyImplicitRules(*symbol);
5553     }
5554     return &name;
5555   }
5556   if (isImplicitNoneType()) {
5557     Say(name, "No explicit type declared for '%s'"_err_en_US);
5558     return nullptr;
5559   }
5560   // Create the symbol then ensure it is accessible
5561   MakeSymbol(InclusiveScope(), name.source, Attrs{});
5562   auto *symbol{FindSymbol(name)};
5563   if (!symbol) {
5564     Say(name,
5565         "'%s' from host scoping unit is not accessible due to IMPORT"_err_en_US);
5566     return nullptr;
5567   }
5568   ConvertToObjectEntity(*symbol);
5569   ApplyImplicitRules(*symbol);
5570   return &name;
5571 }
5572 
5573 // base is a part-ref of a derived type; find the named component in its type.
5574 // Also handles intrinsic type parameter inquiries (%kind, %len) and
5575 // COMPLEX component references (%re, %im).
5576 const parser::Name *DeclarationVisitor::FindComponent(
5577     const parser::Name *base, const parser::Name &component) {
5578   if (!base || !base->symbol) {
5579     return nullptr;
5580   }
5581   auto &symbol{base->symbol->GetUltimate()};
5582   if (!symbol.has<AssocEntityDetails>() && !ConvertToObjectEntity(symbol)) {
5583     SayWithDecl(*base, symbol,
5584         "'%s' is an invalid base for a component reference"_err_en_US);
5585     return nullptr;
5586   }
5587   auto *type{symbol.GetType()};
5588   if (!type) {
5589     return nullptr; // should have already reported error
5590   }
5591   if (const IntrinsicTypeSpec * intrinsic{type->AsIntrinsic()}) {
5592     auto name{component.ToString()};
5593     auto category{intrinsic->category()};
5594     MiscDetails::Kind miscKind{MiscDetails::Kind::None};
5595     if (name == "kind") {
5596       miscKind = MiscDetails::Kind::KindParamInquiry;
5597     } else if (category == TypeCategory::Character) {
5598       if (name == "len") {
5599         miscKind = MiscDetails::Kind::LenParamInquiry;
5600       }
5601     } else if (category == TypeCategory::Complex) {
5602       if (name == "re") {
5603         miscKind = MiscDetails::Kind::ComplexPartRe;
5604       } else if (name == "im") {
5605         miscKind = MiscDetails::Kind::ComplexPartIm;
5606       }
5607     }
5608     if (miscKind != MiscDetails::Kind::None) {
5609       MakePlaceholder(component, miscKind);
5610       return nullptr;
5611     }
5612   } else if (const DerivedTypeSpec * derived{type->AsDerived()}) {
5613     if (const Scope * scope{derived->scope()}) {
5614       if (Resolve(component, scope->FindComponent(component.source))) {
5615         if (auto msg{
5616                 CheckAccessibleComponent(currScope(), *component.symbol)}) {
5617           context().Say(component.source, *msg);
5618         }
5619         return &component;
5620       } else {
5621         SayDerivedType(component.source,
5622             "Component '%s' not found in derived type '%s'"_err_en_US, *scope);
5623       }
5624     }
5625     return nullptr;
5626   }
5627   if (symbol.test(Symbol::Flag::Implicit)) {
5628     Say(*base,
5629         "'%s' is not an object of derived type; it is implicitly typed"_err_en_US);
5630   } else {
5631     SayWithDecl(
5632         *base, symbol, "'%s' is not an object of derived type"_err_en_US);
5633   }
5634   return nullptr;
5635 }
5636 
5637 // C764, C765
5638 bool DeclarationVisitor::CheckInitialDataTarget(
5639     const Symbol &pointer, const SomeExpr &expr, SourceName source) {
5640   auto &context{GetFoldingContext()};
5641   auto restorer{context.messages().SetLocation(source)};
5642   auto dyType{evaluate::DynamicType::From(pointer)};
5643   CHECK(dyType);
5644   auto designator{evaluate::TypedWrapper<evaluate::Designator>(
5645       *dyType, evaluate::DataRef{pointer})};
5646   CHECK(designator);
5647   return CheckInitialTarget(context, *designator, expr);
5648 }
5649 
5650 void DeclarationVisitor::CheckInitialProcTarget(
5651     const Symbol &pointer, const parser::Name &target, SourceName source) {
5652   // C1519 - must be nonelemental external or module procedure,
5653   // or an unrestricted specific intrinsic function.
5654   if (const Symbol * targetSym{target.symbol}) {
5655     const Symbol &ultimate{targetSym->GetUltimate()};
5656     if (ultimate.attrs().test(Attr::INTRINSIC)) {
5657     } else if (!ultimate.attrs().test(Attr::EXTERNAL) &&
5658         ultimate.owner().kind() != Scope::Kind::Module) {
5659       Say(source,
5660           "Procedure pointer '%s' initializer '%s' is neither "
5661           "an external nor a module procedure"_err_en_US,
5662           pointer.name(), ultimate.name());
5663     } else if (ultimate.attrs().test(Attr::ELEMENTAL)) {
5664       Say(source,
5665           "Procedure pointer '%s' cannot be initialized with the "
5666           "elemental procedure '%s"_err_en_US,
5667           pointer.name(), ultimate.name());
5668     } else {
5669       // TODO: Check the "shalls" in the 15.4.3.6 paragraphs 7-10.
5670     }
5671   }
5672 }
5673 
5674 void DeclarationVisitor::Initialization(const parser::Name &name,
5675     const parser::Initialization &init, bool inComponentDecl) {
5676   // Traversal of the initializer was deferred to here so that the
5677   // symbol being declared can be available for use in the expression, e.g.:
5678   //   real, parameter :: x = tiny(x)
5679   if (!name.symbol) {
5680     return;
5681   }
5682   Symbol &ultimate{name.symbol->GetUltimate()};
5683   if (IsAllocatable(ultimate)) {
5684     Say(name, "Allocatable component '%s' cannot be initialized"_err_en_US);
5685     return;
5686   }
5687   if (std::holds_alternative<parser::InitialDataTarget>(init.u)) {
5688     // Defer analysis further to the end of the specification parts so that
5689     // forward references and attribute checks (e.g., SAVE) work better.
5690     // TODO: But pointer initializers of components in named constants of
5691     // derived types may still need more attention.
5692     return;
5693   }
5694   if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
5695     // TODO: check C762 - all bounds and type parameters of component
5696     // are colons or constant expressions if component is initialized
5697     bool isNullPointer{false};
5698     std::visit(
5699         common::visitors{
5700             [&](const parser::ConstantExpr &expr) {
5701               NonPointerInitialization(name, expr, inComponentDecl);
5702             },
5703             [&](const parser::NullInit &) {
5704               isNullPointer = true;
5705               details->set_init(SomeExpr{evaluate::NullPointer{}});
5706             },
5707             [&](const parser::InitialDataTarget &) {
5708               DIE("InitialDataTarget can't appear here");
5709             },
5710             [&](const std::list<Indirection<parser::DataStmtValue>> &) {
5711               // TODO: Need to Walk(init.u); when implementing this case
5712               if (inComponentDecl) {
5713                 Say(name,
5714                     "Component '%s' initialized with DATA statement values"_err_en_US);
5715               } else {
5716                 // TODO - DATA statements and DATA-like initialization extension
5717               }
5718             },
5719         },
5720         init.u);
5721     if (isNullPointer) {
5722       if (!IsPointer(ultimate)) {
5723         Say(name,
5724             "Non-pointer component '%s' initialized with null pointer"_err_en_US);
5725       }
5726     } else if (IsPointer(ultimate)) {
5727       Say(name,
5728           "Object pointer component '%s' initialized with non-pointer expression"_err_en_US);
5729     }
5730   }
5731 }
5732 
5733 void DeclarationVisitor::PointerInitialization(
5734     const parser::Name &name, const parser::InitialDataTarget &target) {
5735   if (name.symbol) {
5736     Symbol &ultimate{name.symbol->GetUltimate()};
5737     if (!context().HasError(ultimate)) {
5738       if (IsPointer(ultimate)) {
5739         if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
5740           CHECK(!details->init());
5741           Walk(target);
5742           if (MaybeExpr expr{EvaluateExpr(target)}) {
5743             CheckInitialDataTarget(ultimate, *expr, target.value().source);
5744             details->set_init(std::move(*expr));
5745           }
5746         }
5747       } else {
5748         Say(name,
5749             "'%s' is not a pointer but is initialized like one"_err_en_US);
5750         context().SetError(ultimate);
5751       }
5752     }
5753   }
5754 }
5755 void DeclarationVisitor::PointerInitialization(
5756     const parser::Name &name, const parser::ProcPointerInit &target) {
5757   if (name.symbol) {
5758     Symbol &ultimate{name.symbol->GetUltimate()};
5759     if (!context().HasError(ultimate)) {
5760       if (IsProcedurePointer(ultimate)) {
5761         auto &details{ultimate.get<ProcEntityDetails>()};
5762         CHECK(!details.init());
5763         Walk(target);
5764         if (const auto *targetName{std::get_if<parser::Name>(&target.u)}) {
5765           CheckInitialProcTarget(ultimate, *targetName, name.source);
5766           if (targetName->symbol) {
5767             details.set_init(*targetName->symbol);
5768           }
5769         } else {
5770           details.set_init(nullptr); // explicit NULL()
5771         }
5772       } else {
5773         Say(name,
5774             "'%s' is not a procedure pointer but is initialized "
5775             "like one"_err_en_US);
5776         context().SetError(ultimate);
5777       }
5778     }
5779   }
5780 }
5781 
5782 void DeclarationVisitor::NonPointerInitialization(const parser::Name &name,
5783     const parser::ConstantExpr &expr, bool inComponentDecl) {
5784   if (name.symbol) {
5785     Symbol &ultimate{name.symbol->GetUltimate()};
5786     if (IsPointer(ultimate)) {
5787       Say(name, "'%s' is a pointer but is not initialized like one"_err_en_US);
5788     } else if (auto *details{ultimate.detailsIf<ObjectEntityDetails>()}) {
5789       CHECK(!details->init());
5790       Walk(expr);
5791       // TODO: check C762 - all bounds and type parameters of component
5792       // are colons or constant expressions if component is initialized
5793       if (inComponentDecl) {
5794         // Can't convert to type of component, which might not yet
5795         // be known; that's done later during instantiation.
5796         if (MaybeExpr value{EvaluateExpr(expr)}) {
5797           details->set_init(std::move(*value));
5798         }
5799       } else if (MaybeExpr folded{EvaluateConvertedExpr(
5800                      ultimate, expr, expr.thing.value().source)}) {
5801         details->set_init(std::move(*folded));
5802       }
5803     }
5804   }
5805 }
5806 
5807 void ResolveNamesVisitor::HandleCall(
5808     Symbol::Flag procFlag, const parser::Call &call) {
5809   std::visit(
5810       common::visitors{
5811           [&](const parser::Name &x) { HandleProcedureName(procFlag, x); },
5812           [&](const parser::ProcComponentRef &x) { Walk(x); },
5813       },
5814       std::get<parser::ProcedureDesignator>(call.t).u);
5815   Walk(std::get<std::list<parser::ActualArgSpec>>(call.t));
5816 }
5817 
5818 void ResolveNamesVisitor::HandleProcedureName(
5819     Symbol::Flag flag, const parser::Name &name) {
5820   CHECK(flag == Symbol::Flag::Function || flag == Symbol::Flag::Subroutine);
5821   auto *symbol{FindSymbol(NonDerivedTypeScope(), name)};
5822   if (!symbol) {
5823     if (context().intrinsics().IsIntrinsic(name.source.ToString())) {
5824       symbol =
5825           &MakeSymbol(InclusiveScope(), name.source, Attrs{Attr::INTRINSIC});
5826     } else {
5827       symbol = &MakeSymbol(context().globalScope(), name.source, Attrs{});
5828     }
5829     Resolve(name, *symbol);
5830     if (symbol->has<ModuleDetails>()) {
5831       SayWithDecl(name, *symbol,
5832           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
5833       return;
5834     }
5835     if (!symbol->attrs().test(Attr::INTRINSIC)) {
5836       if (isImplicitNoneExternal() && !symbol->attrs().test(Attr::EXTERNAL)) {
5837         Say(name,
5838             "'%s' is an external procedure without the EXTERNAL"
5839             " attribute in a scope with IMPLICIT NONE(EXTERNAL)"_err_en_US);
5840         return;
5841       }
5842       MakeExternal(*symbol);
5843     }
5844     ConvertToProcEntity(*symbol);
5845     SetProcFlag(name, *symbol, flag);
5846   } else if (symbol->has<UnknownDetails>()) {
5847     DIE("unexpected UnknownDetails");
5848   } else if (CheckUseError(name)) {
5849     // error was reported
5850   } else {
5851     symbol = &Resolve(name, symbol)->GetUltimate();
5852     ConvertToProcEntity(*symbol);
5853     if (!SetProcFlag(name, *symbol, flag)) {
5854       return; // reported error
5855     }
5856     if (IsProcedure(*symbol) || symbol->has<DerivedTypeDetails>() ||
5857         symbol->has<ObjectEntityDetails>() ||
5858         symbol->has<AssocEntityDetails>()) {
5859       // Symbols with DerivedTypeDetails, ObjectEntityDetails and
5860       // AssocEntityDetails are accepted here as procedure-designators because
5861       // this means the related FunctionReference are mis-parsed structure
5862       // constructors or array references that will be fixed later when
5863       // analyzing expressions.
5864     } else if (symbol->test(Symbol::Flag::Implicit)) {
5865       Say(name,
5866           "Use of '%s' as a procedure conflicts with its implicit definition"_err_en_US);
5867     } else {
5868       SayWithDecl(name, *symbol,
5869           "Use of '%s' as a procedure conflicts with its declaration"_err_en_US);
5870     }
5871   }
5872 }
5873 
5874 // Variant of HandleProcedureName() for use while skimming the executable
5875 // part of a subprogram to catch calls to dummy procedures that are part
5876 // of the subprogram's interface, and to mark as procedures any symbols
5877 // that might otherwise have been miscategorized as objects.
5878 void ResolveNamesVisitor::NoteExecutablePartCall(
5879     Symbol::Flag flag, const parser::Call &call) {
5880   auto &designator{std::get<parser::ProcedureDesignator>(call.t)};
5881   if (const auto *name{std::get_if<parser::Name>(&designator.u)}) {
5882     // Subtlety: The symbol pointers in the parse tree are not set, because
5883     // they might end up resolving elsewhere (e.g., construct entities in
5884     // SELECT TYPE).
5885     if (Symbol * symbol{currScope().FindSymbol(name->source)}) {
5886       Symbol::Flag other{flag == Symbol::Flag::Subroutine
5887               ? Symbol::Flag::Function
5888               : Symbol::Flag::Subroutine};
5889       if (!symbol->test(other)) {
5890         ConvertToProcEntity(*symbol);
5891         if (symbol->has<ProcEntityDetails>()) {
5892           symbol->set(flag);
5893           if (IsDummy(*symbol)) {
5894             symbol->attrs().set(Attr::EXTERNAL);
5895           }
5896           ApplyImplicitRules(*symbol);
5897         }
5898       }
5899     }
5900   }
5901 }
5902 
5903 // Check and set the Function or Subroutine flag on symbol; false on error.
5904 bool ResolveNamesVisitor::SetProcFlag(
5905     const parser::Name &name, Symbol &symbol, Symbol::Flag flag) {
5906   if (symbol.test(Symbol::Flag::Function) && flag == Symbol::Flag::Subroutine) {
5907     SayWithDecl(
5908         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
5909     return false;
5910   } else if (symbol.test(Symbol::Flag::Subroutine) &&
5911       flag == Symbol::Flag::Function) {
5912     SayWithDecl(
5913         name, symbol, "Cannot call subroutine '%s' like a function"_err_en_US);
5914     return false;
5915   } else if (symbol.has<ProcEntityDetails>()) {
5916     symbol.set(flag); // in case it hasn't been set yet
5917     if (flag == Symbol::Flag::Function) {
5918       ApplyImplicitRules(symbol);
5919     }
5920   } else if (symbol.GetType() && flag == Symbol::Flag::Subroutine) {
5921     SayWithDecl(
5922         name, symbol, "Cannot call function '%s' like a subroutine"_err_en_US);
5923   }
5924   return true;
5925 }
5926 
5927 bool ModuleVisitor::Pre(const parser::AccessStmt &x) {
5928   Attr accessAttr{AccessSpecToAttr(std::get<parser::AccessSpec>(x.t))};
5929   if (!currScope().IsModule()) { // C869
5930     Say(currStmtSource().value(),
5931         "%s statement may only appear in the specification part of a module"_err_en_US,
5932         EnumToString(accessAttr));
5933     return false;
5934   }
5935   const auto &accessIds{std::get<std::list<parser::AccessId>>(x.t)};
5936   if (accessIds.empty()) {
5937     if (prevAccessStmt_) { // C869
5938       Say("The default accessibility of this module has already been declared"_err_en_US)
5939           .Attach(*prevAccessStmt_, "Previous declaration"_en_US);
5940     }
5941     prevAccessStmt_ = currStmtSource();
5942     defaultAccess_ = accessAttr;
5943   } else {
5944     for (const auto &accessId : accessIds) {
5945       std::visit(
5946           common::visitors{
5947               [=](const parser::Name &y) {
5948                 Resolve(y, SetAccess(y.source, accessAttr));
5949               },
5950               [=](const Indirection<parser::GenericSpec> &y) {
5951                 auto info{GenericSpecInfo{y.value()}};
5952                 const auto &symbolName{info.symbolName()};
5953                 if (auto *symbol{info.FindInScope(context(), currScope())}) {
5954                   info.Resolve(&SetAccess(symbolName, accessAttr, symbol));
5955                 } else if (info.kind().IsName()) {
5956                   info.Resolve(&SetAccess(symbolName, accessAttr));
5957                 } else {
5958                   Say(symbolName, "Generic spec '%s' not found"_err_en_US);
5959                 }
5960               },
5961           },
5962           accessId.u);
5963     }
5964   }
5965   return false;
5966 }
5967 
5968 // Set the access specification for this symbol.
5969 Symbol &ModuleVisitor::SetAccess(
5970     const SourceName &name, Attr attr, Symbol *symbol) {
5971   if (!symbol) {
5972     symbol = &MakeSymbol(name);
5973   }
5974   Attrs &attrs{symbol->attrs()};
5975   if (attrs.HasAny({Attr::PUBLIC, Attr::PRIVATE})) {
5976     // PUBLIC/PRIVATE already set: make it a fatal error if it changed
5977     Attr prev = attrs.test(Attr::PUBLIC) ? Attr::PUBLIC : Attr::PRIVATE;
5978     auto msg{IsDefinedOperator(name)
5979             ? "The accessibility of operator '%s' has already been specified as %s"_en_US
5980             : "The accessibility of '%s' has already been specified as %s"_en_US};
5981     Say(name, WithIsFatal(msg, attr != prev), name, EnumToString(prev));
5982   } else {
5983     attrs.set(attr);
5984   }
5985   return *symbol;
5986 }
5987 
5988 static bool NeedsExplicitType(const Symbol &symbol) {
5989   if (symbol.has<UnknownDetails>()) {
5990     return true;
5991   } else if (const auto *details{symbol.detailsIf<EntityDetails>()}) {
5992     return !details->type();
5993   } else if (const auto *details{symbol.detailsIf<ObjectEntityDetails>()}) {
5994     return !details->type();
5995   } else if (const auto *details{symbol.detailsIf<ProcEntityDetails>()}) {
5996     return !details->interface().symbol() && !details->interface().type();
5997   } else {
5998     return false;
5999   }
6000 }
6001 
6002 bool ResolveNamesVisitor::Pre(const parser::SpecificationPart &x) {
6003   Walk(std::get<0>(x.t));
6004   Walk(std::get<1>(x.t));
6005   Walk(std::get<2>(x.t));
6006   Walk(std::get<3>(x.t));
6007   const std::list<parser::DeclarationConstruct> &decls{std::get<4>(x.t)};
6008   for (const auto &decl : decls) {
6009     if (const auto *spec{
6010             std::get_if<parser::SpecificationConstruct>(&decl.u)}) {
6011       PreSpecificationConstruct(*spec);
6012     }
6013   }
6014   Walk(decls);
6015   FinishSpecificationPart();
6016   return false;
6017 }
6018 
6019 // Initial processing on specification constructs, before visiting them.
6020 void ResolveNamesVisitor::PreSpecificationConstruct(
6021     const parser::SpecificationConstruct &spec) {
6022   std::visit(
6023       common::visitors{
6024           [&](const Indirection<parser::DerivedTypeDef> &) {},
6025           [&](const parser::Statement<Indirection<parser::GenericStmt>> &y) {
6026             CreateGeneric(std::get<parser::GenericSpec>(y.statement.value().t));
6027           },
6028           [&](const Indirection<parser::InterfaceBlock> &y) {
6029             const auto &stmt{std::get<parser::Statement<parser::InterfaceStmt>>(
6030                 y.value().t)};
6031             const auto *spec{std::get_if<std::optional<parser::GenericSpec>>(
6032                 &stmt.statement.u)};
6033             if (spec && *spec) {
6034               CreateGeneric(**spec);
6035             }
6036           },
6037           [&](const auto &) {},
6038       },
6039       spec.u);
6040 }
6041 
6042 void ResolveNamesVisitor::CreateGeneric(const parser::GenericSpec &x) {
6043   auto info{GenericSpecInfo{x}};
6044   const SourceName &symbolName{info.symbolName()};
6045   if (IsLogicalConstant(context(), symbolName)) {
6046     Say(symbolName,
6047         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6048     return;
6049   }
6050   GenericDetails genericDetails;
6051   if (Symbol * existing{info.FindInScope(context(), currScope())}) {
6052     if (existing->has<GenericDetails>()) {
6053       info.Resolve(existing);
6054       return; // already have generic, add to it
6055     }
6056     Symbol &ultimate{existing->GetUltimate()};
6057     if (auto *ultimateDetails{ultimate.detailsIf<GenericDetails>()}) {
6058       genericDetails.CopyFrom(*ultimateDetails);
6059     } else if (ultimate.has<SubprogramDetails>() ||
6060         ultimate.has<SubprogramNameDetails>()) {
6061       genericDetails.set_specific(ultimate);
6062     } else if (ultimate.has<DerivedTypeDetails>()) {
6063       genericDetails.set_derivedType(ultimate);
6064     } else {
6065       SayAlreadyDeclared(symbolName, *existing);
6066     }
6067     EraseSymbol(*existing);
6068   }
6069   info.Resolve(&MakeSymbol(symbolName, Attrs{}, std::move(genericDetails)));
6070 }
6071 
6072 void ResolveNamesVisitor::FinishSpecificationPart() {
6073   badStmtFuncFound_ = false;
6074   CheckImports();
6075   bool inModule{currScope().kind() == Scope::Kind::Module};
6076   for (auto &pair : currScope()) {
6077     auto &symbol{*pair.second};
6078     if (NeedsExplicitType(symbol)) {
6079       ApplyImplicitRules(symbol);
6080     }
6081     if (symbol.has<GenericDetails>()) {
6082       CheckGenericProcedures(symbol);
6083     }
6084     if (inModule && symbol.attrs().test(Attr::EXTERNAL) &&
6085         !symbol.test(Symbol::Flag::Function) &&
6086         !symbol.test(Symbol::Flag::Subroutine)) {
6087       // in a module, external proc without return type is subroutine
6088       symbol.set(
6089           symbol.GetType() ? Symbol::Flag::Function : Symbol::Flag::Subroutine);
6090     }
6091   }
6092   currScope().InstantiateDerivedTypes(context());
6093   // TODO: what about instantiations in BLOCK?
6094   CheckSaveStmts();
6095   CheckCommonBlocks();
6096   CheckEquivalenceSets();
6097 }
6098 
6099 void ResolveNamesVisitor::CheckImports() {
6100   auto &scope{currScope()};
6101   switch (scope.GetImportKind()) {
6102   case common::ImportKind::None:
6103     break;
6104   case common::ImportKind::All:
6105     // C8102: all entities in host must not be hidden
6106     for (const auto &pair : scope.parent()) {
6107       auto &name{pair.first};
6108       std::optional<SourceName> scopeName{scope.GetName()};
6109       if (!scopeName || name != *scopeName) {
6110         CheckImport(prevImportStmt_.value(), name);
6111       }
6112     }
6113     break;
6114   case common::ImportKind::Default:
6115   case common::ImportKind::Only:
6116     // C8102: entities named in IMPORT must not be hidden
6117     for (auto &name : scope.importNames()) {
6118       CheckImport(name, name);
6119     }
6120     break;
6121   }
6122 }
6123 
6124 void ResolveNamesVisitor::CheckImport(
6125     const SourceName &location, const SourceName &name) {
6126   if (auto *symbol{FindInScope(currScope(), name)}) {
6127     Say(location, "'%s' from host is not accessible"_err_en_US, name)
6128         .Attach(symbol->name(), "'%s' is hidden by this entity"_en_US,
6129             symbol->name());
6130   }
6131 }
6132 
6133 bool ResolveNamesVisitor::Pre(const parser::ImplicitStmt &x) {
6134   return CheckNotInBlock("IMPLICIT") && // C1107
6135       ImplicitRulesVisitor::Pre(x);
6136 }
6137 
6138 void ResolveNamesVisitor::Post(const parser::PointerObject &x) {
6139   std::visit(common::visitors{
6140                  [&](const parser::Name &x) { ResolveName(x); },
6141                  [&](const parser::StructureComponent &x) {
6142                    ResolveStructureComponent(x);
6143                  },
6144              },
6145       x.u);
6146 }
6147 void ResolveNamesVisitor::Post(const parser::AllocateObject &x) {
6148   std::visit(common::visitors{
6149                  [&](const parser::Name &x) { ResolveName(x); },
6150                  [&](const parser::StructureComponent &x) {
6151                    ResolveStructureComponent(x);
6152                  },
6153              },
6154       x.u);
6155 }
6156 
6157 bool ResolveNamesVisitor::Pre(const parser::PointerAssignmentStmt &x) {
6158   const auto &dataRef{std::get<parser::DataRef>(x.t)};
6159   const auto &bounds{std::get<parser::PointerAssignmentStmt::Bounds>(x.t)};
6160   const auto &expr{std::get<parser::Expr>(x.t)};
6161   ResolveDataRef(dataRef);
6162   Walk(bounds);
6163   // Resolve unrestricted specific intrinsic procedures as in "p => cos".
6164   if (const parser::Name * name{parser::Unwrap<parser::Name>(expr)}) {
6165     if (NameIsKnownOrIntrinsic(*name)) {
6166       return false;
6167     }
6168   }
6169   Walk(expr);
6170   return false;
6171 }
6172 void ResolveNamesVisitor::Post(const parser::Designator &x) {
6173   ResolveDesignator(x);
6174 }
6175 
6176 void ResolveNamesVisitor::Post(const parser::ProcComponentRef &x) {
6177   ResolveStructureComponent(x.v.thing);
6178 }
6179 void ResolveNamesVisitor::Post(const parser::TypeGuardStmt &x) {
6180   DeclTypeSpecVisitor::Post(x);
6181   ConstructVisitor::Post(x);
6182 }
6183 bool ResolveNamesVisitor::Pre(const parser::StmtFunctionStmt &x) {
6184   CheckNotInBlock("STATEMENT FUNCTION"); // C1107
6185   if (HandleStmtFunction(x)) {
6186     return false;
6187   } else {
6188     // This is an array element assignment: resolve names of indices
6189     const auto &names{std::get<std::list<parser::Name>>(x.t)};
6190     for (auto &name : names) {
6191       ResolveName(name);
6192     }
6193     return true;
6194   }
6195 }
6196 
6197 bool ResolveNamesVisitor::Pre(const parser::DefinedOpName &x) {
6198   const parser::Name &name{x.v};
6199   if (FindSymbol(name)) {
6200     // OK
6201   } else if (IsLogicalConstant(context(), name.source)) {
6202     Say(name,
6203         "Logical constant '%s' may not be used as a defined operator"_err_en_US);
6204   } else {
6205     // Resolved later in expression semantics
6206     MakePlaceholder(name, MiscDetails::Kind::TypeBoundDefinedOp);
6207   }
6208   return false;
6209 }
6210 
6211 void ResolveNamesVisitor::Post(const parser::AssignStmt &x) {
6212   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6213     ConvertToObjectEntity(DEREF(name->symbol));
6214   }
6215 }
6216 void ResolveNamesVisitor::Post(const parser::AssignedGotoStmt &x) {
6217   if (auto *name{ResolveName(std::get<parser::Name>(x.t))}) {
6218     ConvertToObjectEntity(DEREF(name->symbol));
6219   }
6220 }
6221 
6222 bool ResolveNamesVisitor::Pre(const parser::ProgramUnit &x) {
6223   auto root{ProgramTree::Build(x)};
6224   SetScope(context().globalScope());
6225   ResolveSpecificationParts(root);
6226   FinishSpecificationParts(root);
6227   inExecutionPart_ = true;
6228   ResolveExecutionParts(root);
6229   inExecutionPart_ = false;
6230   ResolveOmpParts(x);
6231   return false;
6232 }
6233 
6234 // References to procedures need to record that their symbols are known
6235 // to be procedures, so that they don't get converted to objects by default.
6236 class ExecutionPartSkimmer {
6237 public:
6238   explicit ExecutionPartSkimmer(ResolveNamesVisitor &resolver)
6239       : resolver_{resolver} {}
6240 
6241   void Walk(const parser::ExecutionPart *exec) {
6242     if (exec) {
6243       parser::Walk(*exec, *this);
6244     }
6245   }
6246 
6247   template <typename A> bool Pre(const A &) { return true; }
6248   template <typename A> void Post(const A &) {}
6249   void Post(const parser::FunctionReference &fr) {
6250     resolver_.NoteExecutablePartCall(Symbol::Flag::Function, fr.v);
6251   }
6252   void Post(const parser::CallStmt &cs) {
6253     resolver_.NoteExecutablePartCall(Symbol::Flag::Subroutine, cs.v);
6254   }
6255 
6256 private:
6257   ResolveNamesVisitor &resolver_;
6258 };
6259 
6260 // Build the scope tree and resolve names in the specification parts of this
6261 // node and its children
6262 void ResolveNamesVisitor::ResolveSpecificationParts(ProgramTree &node) {
6263   if (node.isSpecificationPartResolved()) {
6264     return; // been here already
6265   }
6266   node.set_isSpecificationPartResolved();
6267   if (!BeginScopeForNode(node)) {
6268     return; // an error prevented scope from being created
6269   }
6270   Scope &scope{currScope()};
6271   node.set_scope(scope);
6272   AddSubpNames(node);
6273   std::visit(
6274       [&](const auto *x) {
6275         if (x) {
6276           Walk(*x);
6277         }
6278       },
6279       node.stmt());
6280   Walk(node.spec());
6281   // If this is a function, convert result to an object. This is to prevent the
6282   // result to be converted later to a function symbol if it is called inside
6283   // the function.
6284   // If the result is function pointer, then ConvertToObjectEntity will not
6285   // convert the result to an object, and calling the symbol inside the function
6286   // will result in calls to the result pointer.
6287   // A function cannot be called recursively if RESULT was not used to define a
6288   // distinct result name (15.6.2.2 point 4.).
6289   if (Symbol * symbol{scope.symbol()}) {
6290     if (auto *details{symbol->detailsIf<SubprogramDetails>()}) {
6291       if (details->isFunction()) {
6292         ConvertToObjectEntity(const_cast<Symbol &>(details->result()));
6293       }
6294     }
6295   }
6296   if (node.IsModule()) {
6297     ApplyDefaultAccess();
6298   }
6299   for (auto &child : node.children()) {
6300     ResolveSpecificationParts(child);
6301   }
6302   ExecutionPartSkimmer{*this}.Walk(node.exec());
6303   PopScope();
6304   // Ensure that every object entity has a type.
6305   for (auto &pair : *node.scope()) {
6306     ApplyImplicitRules(*pair.second);
6307   }
6308 }
6309 
6310 // Add SubprogramNameDetails symbols for module and internal subprograms
6311 void ResolveNamesVisitor::AddSubpNames(ProgramTree &node) {
6312   auto kind{
6313       node.IsModule() ? SubprogramKind::Module : SubprogramKind::Internal};
6314   for (auto &child : node.children()) {
6315     auto &symbol{MakeSymbol(child.name(), SubprogramNameDetails{kind, child})};
6316     symbol.set(child.GetSubpFlag());
6317   }
6318 }
6319 
6320 // Push a new scope for this node or return false on error.
6321 bool ResolveNamesVisitor::BeginScopeForNode(const ProgramTree &node) {
6322   switch (node.GetKind()) {
6323     SWITCH_COVERS_ALL_CASES
6324   case ProgramTree::Kind::Program:
6325     PushScope(Scope::Kind::MainProgram,
6326         &MakeSymbol(node.name(), MainProgramDetails{}));
6327     return true;
6328   case ProgramTree::Kind::Function:
6329   case ProgramTree::Kind::Subroutine:
6330     return BeginSubprogram(
6331         node.name(), node.GetSubpFlag(), node.HasModulePrefix());
6332   case ProgramTree::Kind::MpSubprogram:
6333     return BeginMpSubprogram(node.name());
6334   case ProgramTree::Kind::Module:
6335     BeginModule(node.name(), false);
6336     return true;
6337   case ProgramTree::Kind::Submodule:
6338     return BeginSubmodule(node.name(), node.GetParentId());
6339   case ProgramTree::Kind::BlockData:
6340     PushBlockDataScope(node.name());
6341     return true;
6342   }
6343 }
6344 
6345 // Some analyses and checks, such as the processing of initializers of
6346 // pointers, are deferred until all of the pertinent specification parts
6347 // have been visited.  This deferred processing enables the use of forward
6348 // references in these circumstances.
6349 class DeferredCheckVisitor {
6350 public:
6351   explicit DeferredCheckVisitor(ResolveNamesVisitor &resolver)
6352       : resolver_{resolver} {}
6353 
6354   template <typename A> void Walk(const A &x) { parser::Walk(x, *this); }
6355 
6356   template <typename A> bool Pre(const A &) { return true; }
6357   template <typename A> void Post(const A &) {}
6358 
6359   void Post(const parser::DerivedTypeStmt &x) {
6360     const auto &name{std::get<parser::Name>(x.t)};
6361     if (Symbol * symbol{name.symbol}) {
6362       if (Scope * scope{symbol->scope()}) {
6363         if (scope->IsDerivedType()) {
6364           resolver_.PushScope(*scope);
6365           pushedScope_ = true;
6366         }
6367       }
6368     }
6369   }
6370   void Post(const parser::EndTypeStmt &) {
6371     if (pushedScope_) {
6372       resolver_.PopScope();
6373       pushedScope_ = false;
6374     }
6375   }
6376 
6377   void Post(const parser::ProcInterface &pi) {
6378     if (const auto *name{std::get_if<parser::Name>(&pi.u)}) {
6379       resolver_.CheckExplicitInterface(*name);
6380     }
6381   }
6382   bool Pre(const parser::EntityDecl &decl) {
6383     Init(std::get<parser::Name>(decl.t),
6384         std::get<std::optional<parser::Initialization>>(decl.t));
6385     return false;
6386   }
6387   bool Pre(const parser::ComponentDecl &decl) {
6388     Init(std::get<parser::Name>(decl.t),
6389         std::get<std::optional<parser::Initialization>>(decl.t));
6390     return false;
6391   }
6392   bool Pre(const parser::ProcDecl &decl) {
6393     if (const auto &init{
6394             std::get<std::optional<parser::ProcPointerInit>>(decl.t)}) {
6395       resolver_.PointerInitialization(std::get<parser::Name>(decl.t), *init);
6396     }
6397     return false;
6398   }
6399   void Post(const parser::TypeBoundProcedureStmt::WithInterface &tbps) {
6400     resolver_.CheckExplicitInterface(tbps.interfaceName);
6401   }
6402   void Post(const parser::TypeBoundProcedureStmt::WithoutInterface &tbps) {
6403     if (pushedScope_) {
6404       resolver_.CheckBindings(tbps);
6405     }
6406   }
6407 
6408 private:
6409   void Init(const parser::Name &name,
6410       const std::optional<parser::Initialization> &init) {
6411     if (init) {
6412       if (const auto *target{
6413               std::get_if<parser::InitialDataTarget>(&init->u)}) {
6414         resolver_.PointerInitialization(name, *target);
6415       }
6416     }
6417   }
6418 
6419   ResolveNamesVisitor &resolver_;
6420   bool pushedScope_{false};
6421 };
6422 
6423 bool OmpAttributeVisitor::Pre(const parser::OpenMPBlockConstruct &x) {
6424   const auto &beginBlockDir{std::get<parser::OmpBeginBlockDirective>(x.t)};
6425   const auto &beginDir{std::get<parser::OmpBlockDirective>(beginBlockDir.t)};
6426   switch (beginDir.v) {
6427   case parser::OmpBlockDirective::Directive::Master:
6428     PushContext(beginDir.source, OmpDirective::MASTER);
6429     break;
6430   case parser::OmpBlockDirective::Directive::Ordered:
6431     PushContext(beginDir.source, OmpDirective::ORDERED);
6432     break;
6433   case parser::OmpBlockDirective::Directive::Parallel:
6434     PushContext(beginDir.source, OmpDirective::PARALLEL);
6435     break;
6436   case parser::OmpBlockDirective::Directive::Single:
6437     PushContext(beginDir.source, OmpDirective::SINGLE);
6438     break;
6439   case parser::OmpBlockDirective::Directive::Target:
6440     PushContext(beginDir.source, OmpDirective::TARGET);
6441     break;
6442   case parser::OmpBlockDirective::Directive::TargetData:
6443     PushContext(beginDir.source, OmpDirective::TARGET_DATA);
6444     break;
6445   case parser::OmpBlockDirective::Directive::Task:
6446     PushContext(beginDir.source, OmpDirective::TASK);
6447     break;
6448   case parser::OmpBlockDirective::Directive::Teams:
6449     PushContext(beginDir.source, OmpDirective::TEAMS);
6450     break;
6451   case parser::OmpBlockDirective::Directive::Workshare:
6452     PushContext(beginDir.source, OmpDirective::WORKSHARE);
6453     break;
6454   case parser::OmpBlockDirective::Directive::ParallelWorkshare:
6455     PushContext(beginDir.source, OmpDirective::PARALLEL_WORKSHARE);
6456     break;
6457   case parser::OmpBlockDirective::Directive::TargetTeams:
6458     PushContext(beginDir.source, OmpDirective::TARGET_TEAMS);
6459     break;
6460   case parser::OmpBlockDirective::Directive::TargetParallel:
6461     PushContext(beginDir.source, OmpDirective::TARGET_PARALLEL);
6462     break;
6463   default:
6464     // TODO others
6465     break;
6466   }
6467   ClearDataSharingAttributeObjects();
6468   return true;
6469 }
6470 
6471 bool OmpAttributeVisitor::Pre(const parser::OpenMPLoopConstruct &x) {
6472   const auto &beginLoopDir{std::get<parser::OmpBeginLoopDirective>(x.t)};
6473   const auto &beginDir{std::get<parser::OmpLoopDirective>(beginLoopDir.t)};
6474   const auto &clauseList{std::get<parser::OmpClauseList>(beginLoopDir.t)};
6475   switch (beginDir.v) {
6476   case parser::OmpLoopDirective::Directive::Distribute:
6477     PushContext(beginDir.source, OmpDirective::DISTRIBUTE);
6478     break;
6479   case parser::OmpLoopDirective::Directive::DistributeParallelDo:
6480     PushContext(beginDir.source, OmpDirective::DISTRIBUTE_PARALLEL_DO);
6481     break;
6482   case parser::OmpLoopDirective::Directive::DistributeParallelDoSimd:
6483     PushContext(beginDir.source, OmpDirective::DISTRIBUTE_PARALLEL_DO_SIMD);
6484     break;
6485   case parser::OmpLoopDirective::Directive::DistributeSimd:
6486     PushContext(beginDir.source, OmpDirective::DISTRIBUTE_SIMD);
6487     break;
6488   case parser::OmpLoopDirective::Directive::Do:
6489     PushContext(beginDir.source, OmpDirective::DO);
6490     break;
6491   case parser::OmpLoopDirective::Directive::DoSimd:
6492     PushContext(beginDir.source, OmpDirective::DO_SIMD);
6493     break;
6494   case parser::OmpLoopDirective::Directive::ParallelDo:
6495     PushContext(beginDir.source, OmpDirective::PARALLEL_DO);
6496     break;
6497   case parser::OmpLoopDirective::Directive::ParallelDoSimd:
6498     PushContext(beginDir.source, OmpDirective::PARALLEL_DO_SIMD);
6499     break;
6500   case parser::OmpLoopDirective::Directive::Simd:
6501     PushContext(beginDir.source, OmpDirective::SIMD);
6502     break;
6503   case parser::OmpLoopDirective::Directive::TargetParallelDo:
6504     PushContext(beginDir.source, OmpDirective::TARGET_PARALLEL_DO);
6505     break;
6506   case parser::OmpLoopDirective::Directive::TargetParallelDoSimd:
6507     PushContext(beginDir.source, OmpDirective::TARGET_PARALLEL_DO_SIMD);
6508     break;
6509   case parser::OmpLoopDirective::Directive::TargetTeamsDistribute:
6510     PushContext(beginDir.source, OmpDirective::TARGET_TEAMS_DISTRIBUTE);
6511     break;
6512   case parser::OmpLoopDirective::Directive::TargetTeamsDistributeParallelDo:
6513     PushContext(
6514         beginDir.source, OmpDirective::TARGET_TEAMS_DISTRIBUTE_PARALLEL_DO);
6515     break;
6516   case parser::OmpLoopDirective::Directive::TargetTeamsDistributeParallelDoSimd:
6517     PushContext(beginDir.source,
6518         OmpDirective::TARGET_TEAMS_DISTRIBUTE_PARALLEL_DO_SIMD);
6519     break;
6520   case parser::OmpLoopDirective::Directive::TargetTeamsDistributeSimd:
6521     PushContext(beginDir.source, OmpDirective::TARGET_TEAMS_DISTRIBUTE_SIMD);
6522     break;
6523   case parser::OmpLoopDirective::Directive::TargetSimd:
6524     PushContext(beginDir.source, OmpDirective::TARGET_SIMD);
6525     break;
6526   case parser::OmpLoopDirective::Directive::Taskloop:
6527     PushContext(beginDir.source, OmpDirective::TASKLOOP);
6528     break;
6529   case parser::OmpLoopDirective::Directive::TaskloopSimd:
6530     PushContext(beginDir.source, OmpDirective::TASKLOOP_SIMD);
6531     break;
6532   case parser::OmpLoopDirective::Directive::TeamsDistribute:
6533     PushContext(beginDir.source, OmpDirective::TEAMS_DISTRIBUTE);
6534     break;
6535   case parser::OmpLoopDirective::Directive::TeamsDistributeParallelDo:
6536     PushContext(beginDir.source, OmpDirective::TEAMS_DISTRIBUTE_PARALLEL_DO);
6537     break;
6538   case parser::OmpLoopDirective::Directive::TeamsDistributeParallelDoSimd:
6539     PushContext(
6540         beginDir.source, OmpDirective::TEAMS_DISTRIBUTE_PARALLEL_DO_SIMD);
6541     break;
6542   case parser::OmpLoopDirective::Directive::TeamsDistributeSimd:
6543     PushContext(beginDir.source, OmpDirective::TEAMS_DISTRIBUTE_SIMD);
6544     break;
6545   }
6546   ClearDataSharingAttributeObjects();
6547   SetContextAssociatedLoopLevel(GetAssociatedLoopLevelFromClauses(clauseList));
6548   PrivatizeAssociatedLoopIndex(x);
6549   return true;
6550 }
6551 
6552 const parser::Name &OmpAttributeVisitor::GetLoopIndex(
6553     const parser::DoConstruct &x) {
6554   auto &loopControl{x.GetLoopControl().value()};
6555   using Bounds = parser::LoopControl::Bounds;
6556   const Bounds &bounds{std::get<Bounds>(loopControl.u)};
6557   return bounds.name.thing;
6558 }
6559 
6560 void OmpAttributeVisitor::ResolveSeqLoopIndexInParallelOrTaskConstruct(
6561     const parser::Name &iv) {
6562   auto targetIt{ompContext_.rbegin()};
6563   for (;; ++targetIt) {
6564     if (targetIt == ompContext_.rend()) {
6565       return;
6566     }
6567     if (parallelSet.test(targetIt->directive) ||
6568         taskGeneratingSet.test(targetIt->directive)) {
6569       break;
6570     }
6571   }
6572   if (auto *symbol{ResolveOmp(iv, Symbol::Flag::OmpPrivate, targetIt->scope)}) {
6573     targetIt++;
6574     symbol->set(Symbol::Flag::OmpPreDetermined);
6575     iv.symbol = symbol; // adjust the symbol within region
6576     for (auto it{ompContext_.rbegin()}; it != targetIt; ++it) {
6577       AddToContextObjectWithDSA(*symbol, Symbol::Flag::OmpPrivate, *it);
6578     }
6579   }
6580 }
6581 
6582 // 2.15.1.1 Data-sharing Attribute Rules - Predetermined
6583 //   - A loop iteration variable for a sequential loop in a parallel
6584 //     or task generating construct is private in the innermost such
6585 //     construct that encloses the loop
6586 bool OmpAttributeVisitor::Pre(const parser::DoConstruct &x) {
6587   if (!ompContext_.empty() && GetContext().withinConstruct) {
6588     if (const auto &iv{GetLoopIndex(x)}; iv.symbol) {
6589       if (!iv.symbol->test(Symbol::Flag::OmpPreDetermined)) {
6590         ResolveSeqLoopIndexInParallelOrTaskConstruct(iv);
6591       } else {
6592         // TODO: conflict checks with explicitly determined DSA
6593       }
6594     }
6595   }
6596   return true;
6597 }
6598 
6599 const parser::DoConstruct *OmpAttributeVisitor::GetDoConstructIf(
6600     const parser::ExecutionPartConstruct &x) {
6601   if (auto *y{std::get_if<parser::ExecutableConstruct>(&x.u)}) {
6602     if (auto *z{std::get_if<Indirection<parser::DoConstruct>>(&y->u)}) {
6603       return &z->value();
6604     }
6605   }
6606   return nullptr;
6607 }
6608 
6609 std::int64_t OmpAttributeVisitor::GetAssociatedLoopLevelFromClauses(
6610     const parser::OmpClauseList &x) {
6611   std::int64_t orderedLevel{0};
6612   std::int64_t collapseLevel{0};
6613   for (const auto &clause : x.v) {
6614     if (const auto *orderedClause{
6615             std::get_if<parser::OmpClause::Ordered>(&clause.u)}) {
6616       if (const auto v{
6617               evaluate::ToInt64(resolver_.EvaluateIntExpr(orderedClause->v))}) {
6618         orderedLevel = *v;
6619       }
6620     }
6621     if (const auto *collapseClause{
6622             std::get_if<parser::OmpClause::Collapse>(&clause.u)}) {
6623       if (const auto v{evaluate::ToInt64(
6624               resolver_.EvaluateIntExpr(collapseClause->v))}) {
6625         collapseLevel = *v;
6626       }
6627     }
6628   }
6629 
6630   if (orderedLevel && (!collapseLevel || orderedLevel >= collapseLevel)) {
6631     return orderedLevel;
6632   } else if (!orderedLevel && collapseLevel) {
6633     return collapseLevel;
6634   } // orderedLevel < collapseLevel is an error handled in structural checks
6635   return 1; // default is outermost loop
6636 }
6637 
6638 // 2.15.1.1 Data-sharing Attribute Rules - Predetermined
6639 //   - The loop iteration variable(s) in the associated do-loop(s) of a do,
6640 //     parallel do, taskloop, or distribute construct is (are) private.
6641 //   - The loop iteration variable in the associated do-loop of a simd construct
6642 //     with just one associated do-loop is linear with a linear-step that is the
6643 //     increment of the associated do-loop.
6644 //   - The loop iteration variables in the associated do-loops of a simd
6645 //     construct with multiple associated do-loops are lastprivate.
6646 //
6647 // TODO: revisit after semantics checks are completed for do-loop association of
6648 //       collapse and ordered
6649 void OmpAttributeVisitor::PrivatizeAssociatedLoopIndex(
6650     const parser::OpenMPLoopConstruct &x) {
6651   std::int64_t level{GetContext().associatedLoopLevel};
6652   if (level <= 0)
6653     return;
6654   Symbol::Flag ivDSA{Symbol::Flag::OmpPrivate};
6655   if (simdSet.test(GetContext().directive)) {
6656     if (level == 1) {
6657       ivDSA = Symbol::Flag::OmpLinear;
6658     } else {
6659       ivDSA = Symbol::Flag::OmpLastPrivate;
6660     }
6661   }
6662 
6663   auto &outer{std::get<std::optional<parser::DoConstruct>>(x.t)};
6664   for (const parser::DoConstruct *loop{&*outer}; loop && level > 0; --level) {
6665     // go through all the nested do-loops and resolve index variables
6666     const parser::Name &iv{GetLoopIndex(*loop)};
6667     if (auto *symbol{ResolveOmp(iv, ivDSA, currScope())}) {
6668       symbol->set(Symbol::Flag::OmpPreDetermined);
6669       iv.symbol = symbol; // adjust the symbol within region
6670       AddToContextObjectWithDSA(*symbol, ivDSA);
6671     }
6672 
6673     const auto &block{std::get<parser::Block>(loop->t)};
6674     const auto it{block.begin()};
6675     loop = it != block.end() ? GetDoConstructIf(*it) : nullptr;
6676   }
6677   CHECK(level == 0);
6678 }
6679 
6680 bool OmpAttributeVisitor::Pre(const parser::OpenMPSectionsConstruct &x) {
6681   const auto &beginSectionsDir{
6682       std::get<parser::OmpBeginSectionsDirective>(x.t)};
6683   const auto &beginDir{
6684       std::get<parser::OmpSectionsDirective>(beginSectionsDir.t)};
6685   switch (beginDir.v) {
6686   case parser::OmpSectionsDirective::Directive::ParallelSections:
6687     PushContext(beginDir.source, OmpDirective::PARALLEL_SECTIONS);
6688     break;
6689   case parser::OmpSectionsDirective::Directive::Sections:
6690     PushContext(beginDir.source, OmpDirective::SECTIONS);
6691     break;
6692   }
6693   ClearDataSharingAttributeObjects();
6694   return true;
6695 }
6696 
6697 bool OmpAttributeVisitor::Pre(const parser::OpenMPThreadprivate &x) {
6698   PushContext(x.source, OmpDirective::THREADPRIVATE);
6699   const auto &list{std::get<parser::OmpObjectList>(x.t)};
6700   ResolveOmpObjectList(list, Symbol::Flag::OmpThreadprivate);
6701   return false;
6702 }
6703 
6704 void OmpAttributeVisitor::Post(const parser::OmpDefaultClause &x) {
6705   if (!ompContext_.empty()) {
6706     switch (x.v) {
6707     case parser::OmpDefaultClause::Type::Private:
6708       SetContextDefaultDSA(Symbol::Flag::OmpPrivate);
6709       break;
6710     case parser::OmpDefaultClause::Type::Firstprivate:
6711       SetContextDefaultDSA(Symbol::Flag::OmpFirstPrivate);
6712       break;
6713     case parser::OmpDefaultClause::Type::Shared:
6714       SetContextDefaultDSA(Symbol::Flag::OmpShared);
6715       break;
6716     case parser::OmpDefaultClause::Type::None:
6717       SetContextDefaultDSA(Symbol::Flag::OmpNone);
6718       break;
6719     }
6720   }
6721 }
6722 
6723 // For OpenMP constructs, check all the data-refs within the constructs
6724 // and adjust the symbol for each Name if necessary
6725 void OmpAttributeVisitor::Post(const parser::Name &name) {
6726   auto *symbol{name.symbol};
6727   if (symbol && !ompContext_.empty() && GetContext().withinConstruct) {
6728     if (!symbol->owner().IsDerivedType() && !symbol->has<ProcEntityDetails>() &&
6729         !IsObjectWithDSA(*symbol)) {
6730       // TODO: create a separate function to go through the rules for
6731       //       predetermined, explicitly determined, and implicitly
6732       //       determined data-sharing attributes (2.15.1.1).
6733       if (Symbol * found{currScope().FindSymbol(name.source)}) {
6734         if (symbol != found) {
6735           name.symbol = found; // adjust the symbol within region
6736         } else if (GetContext().defaultDSA == Symbol::Flag::OmpNone) {
6737           context_.Say(name.source,
6738               "The DEFAULT(NONE) clause requires that '%s' must be listed in "
6739               "a data-sharing attribute clause"_err_en_US,
6740               symbol->name());
6741         }
6742       }
6743     }
6744   } // within OpenMP construct
6745 }
6746 
6747 bool OmpAttributeVisitor::HasDataSharingAttributeObject(const Symbol &object) {
6748   auto it{dataSharingAttributeObjects_.find(object)};
6749   return it != dataSharingAttributeObjects_.end();
6750 }
6751 
6752 Symbol *OmpAttributeVisitor::ResolveOmpCommonBlockName(
6753     const parser::Name *name) {
6754   if (auto *prev{name
6755               ? GetContext().scope.parent().FindCommonBlock(name->source)
6756               : nullptr}) {
6757     name->symbol = prev;
6758     return prev;
6759   } else {
6760     return nullptr;
6761   }
6762 }
6763 
6764 void OmpAttributeVisitor::ResolveOmpObjectList(
6765     const parser::OmpObjectList &ompObjectList, Symbol::Flag ompFlag) {
6766   for (const auto &ompObject : ompObjectList.v) {
6767     ResolveOmpObject(ompObject, ompFlag);
6768   }
6769 }
6770 
6771 void OmpAttributeVisitor::ResolveOmpObject(
6772     const parser::OmpObject &ompObject, Symbol::Flag ompFlag) {
6773   std::visit(
6774       common::visitors{
6775           [&](const parser::Designator &designator) {
6776             if (const auto *name{GetDesignatorNameIfDataRef(designator)}) {
6777               if (auto *symbol{ResolveOmp(*name, ompFlag, currScope())}) {
6778                 AddToContextObjectWithDSA(*symbol, ompFlag);
6779                 if (dataSharingAttributeFlags.test(ompFlag)) {
6780                   CheckMultipleAppearances(*name, *symbol, ompFlag);
6781                 }
6782               }
6783             } else if (const auto *designatorName{
6784                            resolver_.ResolveDesignator(designator)};
6785                        designatorName->symbol) {
6786               // Array sections to be changed to substrings as needed
6787               if (AnalyzeExpr(context_, designator)) {
6788                 if (std::holds_alternative<parser::Substring>(designator.u)) {
6789                   context_.Say(designator.source,
6790                       "Substrings are not allowed on OpenMP "
6791                       "directives or clauses"_err_en_US);
6792                 }
6793               }
6794               // other checks, more TBD
6795               if (const auto *details{designatorName->symbol
6796                                           ->detailsIf<ObjectEntityDetails>()}) {
6797                 if (details->IsArray()) {
6798                   // TODO: check Array Sections
6799                 } else if (designatorName->symbol->owner().IsDerivedType()) {
6800                   // TODO: check Structure Component
6801                 }
6802               }
6803             }
6804           },
6805           [&](const parser::Name &name) { // common block
6806             if (auto *symbol{ResolveOmpCommonBlockName(&name)}) {
6807               CheckMultipleAppearances(
6808                   name, *symbol, Symbol::Flag::OmpCommonBlock);
6809               // 2.15.3 When a named common block appears in a list, it has the
6810               // same meaning as if every explicit member of the common block
6811               // appeared in the list
6812               for (auto &object : symbol->get<CommonBlockDetails>().objects()) {
6813                 if (auto *resolvedObject{
6814                         ResolveOmp(*object, ompFlag, currScope())}) {
6815                   AddToContextObjectWithDSA(*resolvedObject, ompFlag);
6816                 }
6817               }
6818             } else {
6819               context_.Say(name.source, // 2.15.3
6820                   "COMMON block must be declared in the same scoping unit "
6821                   "in which the OpenMP directive or clause appears"_err_en_US);
6822             }
6823           },
6824       },
6825       ompObject.u);
6826 }
6827 
6828 Symbol *OmpAttributeVisitor::ResolveOmp(
6829     const parser::Name &name, Symbol::Flag ompFlag, Scope &scope) {
6830   if (ompFlagsRequireNewSymbol.test(ompFlag)) {
6831     return DeclarePrivateAccessEntity(name, ompFlag, scope);
6832   } else {
6833     return DeclareOrMarkOtherAccessEntity(name, ompFlag);
6834   }
6835 }
6836 
6837 Symbol *OmpAttributeVisitor::ResolveOmp(
6838     Symbol &symbol, Symbol::Flag ompFlag, Scope &scope) {
6839   if (ompFlagsRequireNewSymbol.test(ompFlag)) {
6840     return DeclarePrivateAccessEntity(symbol, ompFlag, scope);
6841   } else {
6842     return DeclareOrMarkOtherAccessEntity(symbol, ompFlag);
6843   }
6844 }
6845 
6846 Symbol *OmpAttributeVisitor::DeclarePrivateAccessEntity(
6847     const parser::Name &name, Symbol::Flag ompFlag, Scope &scope) {
6848   if (!name.symbol) {
6849     return nullptr; // not resolved by Name Resolution step, do nothing
6850   }
6851   name.symbol = DeclarePrivateAccessEntity(*name.symbol, ompFlag, scope);
6852   return name.symbol;
6853 }
6854 
6855 Symbol *OmpAttributeVisitor::DeclarePrivateAccessEntity(
6856     Symbol &object, Symbol::Flag ompFlag, Scope &scope) {
6857   if (object.owner() != currScope()) {
6858     auto &symbol{MakeAssocSymbol(object.name(), object, scope)};
6859     symbol.set(ompFlag);
6860     return &symbol;
6861   } else {
6862     object.set(ompFlag);
6863     return &object;
6864   }
6865 }
6866 
6867 Symbol *OmpAttributeVisitor::DeclareOrMarkOtherAccessEntity(
6868     const parser::Name &name, Symbol::Flag ompFlag) {
6869   Symbol *prev{currScope().FindSymbol(name.source)};
6870   if (!name.symbol || !prev) {
6871     return nullptr;
6872   } else if (prev != name.symbol) {
6873     name.symbol = prev;
6874   }
6875   return DeclareOrMarkOtherAccessEntity(*prev, ompFlag);
6876 }
6877 
6878 Symbol *OmpAttributeVisitor::DeclareOrMarkOtherAccessEntity(
6879     Symbol &object, Symbol::Flag ompFlag) {
6880   if (ompFlagsRequireMark.test(ompFlag)) {
6881     object.set(ompFlag);
6882   }
6883   return &object;
6884 }
6885 
6886 static bool WithMultipleAppearancesException(
6887     const Symbol &symbol, Symbol::Flag ompFlag) {
6888   return (ompFlag == Symbol::Flag::OmpFirstPrivate &&
6889              symbol.test(Symbol::Flag::OmpLastPrivate)) ||
6890       (ompFlag == Symbol::Flag::OmpLastPrivate &&
6891           symbol.test(Symbol::Flag::OmpFirstPrivate));
6892 }
6893 
6894 void OmpAttributeVisitor::CheckMultipleAppearances(
6895     const parser::Name &name, const Symbol &symbol, Symbol::Flag ompFlag) {
6896   const auto *target{&symbol};
6897   if (ompFlagsRequireNewSymbol.test(ompFlag)) {
6898     if (const auto *details{symbol.detailsIf<HostAssocDetails>()}) {
6899       target = &details->symbol();
6900     }
6901   }
6902   if (HasDataSharingAttributeObject(*target) &&
6903       !WithMultipleAppearancesException(symbol, ompFlag)) {
6904     context_.Say(name.source,
6905         "'%s' appears in more than one data-sharing clause "
6906         "on the same OpenMP directive"_err_en_US,
6907         name.ToString());
6908   } else {
6909     AddDataSharingAttributeObject(*target);
6910   }
6911 }
6912 
6913 // Perform checks and completions that need to happen after all of
6914 // the specification parts but before any of the execution parts.
6915 void ResolveNamesVisitor::FinishSpecificationParts(const ProgramTree &node) {
6916   if (!node.scope()) {
6917     return; // error occurred creating scope
6918   }
6919   SetScope(*node.scope());
6920   // The initializers of pointers, pointer components, and non-deferred
6921   // type-bound procedure bindings have not yet been traversed.
6922   // We do that now, when any (formerly) forward references that appear
6923   // in those initializers will resolve to the right symbols.
6924   DeferredCheckVisitor{*this}.Walk(node.spec());
6925   DeferredCheckVisitor{*this}.Walk(node.exec()); // for BLOCK
6926   for (Scope &childScope : currScope().children()) {
6927     if (childScope.IsDerivedType() && !childScope.symbol()) {
6928       FinishDerivedTypeInstantiation(childScope);
6929     }
6930   }
6931   for (const auto &child : node.children()) {
6932     FinishSpecificationParts(child);
6933   }
6934 }
6935 
6936 // Fold object pointer initializer designators with the actual
6937 // type parameter values of a particular instantiation.
6938 void ResolveNamesVisitor::FinishDerivedTypeInstantiation(Scope &scope) {
6939   CHECK(scope.IsDerivedType() && !scope.symbol());
6940   if (DerivedTypeSpec * spec{scope.derivedTypeSpec()}) {
6941     spec->Instantiate(currScope(), context());
6942     const Symbol &origTypeSymbol{spec->typeSymbol()};
6943     if (const Scope * origTypeScope{origTypeSymbol.scope()}) {
6944       CHECK(origTypeScope->IsDerivedType() &&
6945           origTypeScope->symbol() == &origTypeSymbol);
6946       auto &foldingContext{GetFoldingContext()};
6947       auto restorer{foldingContext.WithPDTInstance(*spec)};
6948       for (auto &pair : scope) {
6949         Symbol &comp{*pair.second};
6950         const Symbol &origComp{DEREF(FindInScope(*origTypeScope, comp.name()))};
6951         if (IsPointer(comp)) {
6952           if (auto *details{comp.detailsIf<ObjectEntityDetails>()}) {
6953             auto origDetails{origComp.get<ObjectEntityDetails>()};
6954             if (const MaybeExpr & init{origDetails.init()}) {
6955               SomeExpr newInit{*init};
6956               MaybeExpr folded{
6957                   evaluate::Fold(foldingContext, std::move(newInit))};
6958               details->set_init(std::move(folded));
6959             }
6960           }
6961         }
6962       }
6963     }
6964   }
6965 }
6966 
6967 // Resolve names in the execution part of this node and its children
6968 void ResolveNamesVisitor::ResolveExecutionParts(const ProgramTree &node) {
6969   if (!node.scope()) {
6970     return; // error occurred creating scope
6971   }
6972   SetScope(*node.scope());
6973   if (const auto *exec{node.exec()}) {
6974     Walk(*exec);
6975   }
6976   PopScope(); // converts unclassified entities into objects
6977   for (const auto &child : node.children()) {
6978     ResolveExecutionParts(child);
6979   }
6980 }
6981 
6982 void ResolveNamesVisitor::ResolveOmpParts(const parser::ProgramUnit &node) {
6983   OmpAttributeVisitor{context(), *this}.Walk(node);
6984   if (!context().AnyFatalError()) {
6985     // The data-sharing attribute of the loop iteration variable for a
6986     // sequential loop (2.15.1.1) can only be determined when visiting
6987     // the corresponding DoConstruct, a second walk is to adjust the
6988     // symbols for all the data-refs of that loop iteration variable
6989     // prior to the DoConstruct.
6990     OmpAttributeVisitor{context(), *this}.Walk(node);
6991   }
6992 }
6993 
6994 void ResolveNamesVisitor::Post(const parser::Program &) {
6995   // ensure that all temps were deallocated
6996   CHECK(!attrs_);
6997   CHECK(!GetDeclTypeSpec());
6998 }
6999 
7000 // A singleton instance of the scope -> IMPLICIT rules mapping is
7001 // shared by all instances of ResolveNamesVisitor and accessed by this
7002 // pointer when the visitors (other than the top-level original) are
7003 // constructed.
7004 static ImplicitRulesMap *sharedImplicitRulesMap{nullptr};
7005 
7006 bool ResolveNames(SemanticsContext &context, const parser::Program &program) {
7007   ImplicitRulesMap implicitRulesMap;
7008   auto restorer{common::ScopedSet(sharedImplicitRulesMap, &implicitRulesMap)};
7009   ResolveNamesVisitor{context, implicitRulesMap}.Walk(program);
7010   return !context.AnyFatalError();
7011 }
7012 
7013 // Processes a module (but not internal) function when it is referenced
7014 // in a specification expression in a sibling procedure.
7015 void ResolveSpecificationParts(
7016     SemanticsContext &context, const Symbol &subprogram) {
7017   auto originalLocation{context.location()};
7018   ResolveNamesVisitor visitor{context, DEREF(sharedImplicitRulesMap)};
7019   ProgramTree &node{subprogram.get<SubprogramNameDetails>().node()};
7020   const Scope &moduleScope{subprogram.owner()};
7021   visitor.SetScope(const_cast<Scope &>(moduleScope));
7022   visitor.ResolveSpecificationParts(node);
7023   context.set_location(std::move(originalLocation));
7024 }
7025 } // namespace Fortran::semantics
7026