1 //===--- SemaCXXScopeSpec.cpp - Semantic Analysis for C++ scope specifiers-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements C++ semantic analysis for scope specifiers.
12 //===----------------------------------------------------------------------===//
16 #include "clang/AST/ASTContext.h"
17 #include "clang/AST/DeclTemplate.h"
18 #include "clang/AST/ExprCXX.h"
19 #include "clang/AST/NestedNameSpecifier.h"
20 #include "clang/Basic/PartialDiagnostic.h"
21 #include "clang/Parse/DeclSpec.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/Support/raw_ostream.h"
24 using namespace clang;
26 /// \brief Find the current instantiation that associated with the given type.
27 static CXXRecordDecl *
28 getCurrentInstantiationOf(ASTContext &Context, DeclContext *CurContext,
33 T = Context.getCanonicalType(T);
35 for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getParent()) {
36 // If we've hit a namespace or the global scope, then the
37 // nested-name-specifier can't refer to the current instantiation.
38 if (Ctx->isFileContext())
41 // Skip non-class contexts.
42 CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
46 // If this record type is not dependent,
47 if (!Record->isDependentType())
50 // C++ [temp.dep.type]p1:
52 // In the definition of a class template, a nested class of a
53 // class template, a member of a class template, or a member of a
54 // nested class of a class template, a name refers to the current
55 // instantiation if it is
56 // -- the injected-class-name (9) of the class template or
58 // -- in the definition of a primary class template, the name
59 // of the class template followed by the template argument
60 // list of the primary template (as described below)
62 // -- in the definition of a nested class of a class template,
63 // the name of the nested class referenced as a member of
64 // the current instantiation, or
65 // -- in the definition of a partial specialization, the name
66 // of the class template followed by the template argument
67 // list of the partial specialization enclosed in <>. If
68 // the nth template parameter is a parameter pack, the nth
69 // template argument is a pack expansion (14.6.3) whose
70 // pattern is the name of the parameter pack.
71 // (FIXME: parameter packs)
73 // All of these options come down to having the
74 // nested-name-specifier type that is equivalent to the
75 // injected-class-name of one of the types that is currently in
77 if (Context.getCanonicalType(Context.getTypeDeclType(Record)) == T)
80 if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate()) {
81 QualType InjectedClassName
82 = Template->getInjectedClassNameType(Context);
83 if (T == Context.getCanonicalType(InjectedClassName))
84 return Template->getTemplatedDecl();
86 // FIXME: check for class template partial specializations
92 /// \brief Compute the DeclContext that is associated with the given type.
94 /// \param T the type for which we are attempting to find a DeclContext.
96 /// \returns the declaration context represented by the type T,
97 /// or NULL if the declaration context cannot be computed (e.g., because it is
98 /// dependent and not the current instantiation).
99 DeclContext *Sema::computeDeclContext(QualType T) {
100 if (const TagType *Tag = T->getAs<TagType>())
101 return Tag->getDecl();
103 return ::getCurrentInstantiationOf(Context, CurContext, T);
106 /// \brief Compute the DeclContext that is associated with the given
109 /// \param SS the C++ scope specifier as it appears in the source
111 /// \param EnteringContext when true, we will be entering the context of
112 /// this scope specifier, so we can retrieve the declaration context of a
113 /// class template or class template partial specialization even if it is
114 /// not the current instantiation.
116 /// \returns the declaration context represented by the scope specifier @p SS,
117 /// or NULL if the declaration context cannot be computed (e.g., because it is
118 /// dependent and not the current instantiation).
119 DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
120 bool EnteringContext) {
121 if (!SS.isSet() || SS.isInvalid())
124 NestedNameSpecifier *NNS
125 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
126 if (NNS->isDependent()) {
127 // If this nested-name-specifier refers to the current
128 // instantiation, return its DeclContext.
129 if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS))
132 if (EnteringContext) {
133 if (const TemplateSpecializationType *SpecType
134 = dyn_cast_or_null<TemplateSpecializationType>(NNS->getAsType())) {
135 // We are entering the context of the nested name specifier, so try to
136 // match the nested name specifier to either a primary class template
137 // or a class template partial specialization.
138 if (ClassTemplateDecl *ClassTemplate
139 = dyn_cast_or_null<ClassTemplateDecl>(
140 SpecType->getTemplateName().getAsTemplateDecl())) {
142 = Context.getCanonicalType(QualType(SpecType, 0));
144 // If the type of the nested name specifier is the same as the
145 // injected class name of the named class template, we're entering
146 // into that class template definition.
147 QualType Injected = ClassTemplate->getInjectedClassNameType(Context);
148 if (Context.hasSameType(Injected, ContextType))
149 return ClassTemplate->getTemplatedDecl();
151 // If the type of the nested name specifier is the same as the
152 // type of one of the class template's class template partial
153 // specializations, we're entering into the definition of that
154 // class template partial specialization.
155 if (ClassTemplatePartialSpecializationDecl *PartialSpec
156 = ClassTemplate->findPartialSpecialization(ContextType))
159 } else if (const RecordType *RecordT
160 = dyn_cast_or_null<RecordType>(NNS->getAsType())) {
161 // The nested name specifier refers to a member of a class template.
162 return RecordT->getDecl();
169 switch (NNS->getKind()) {
170 case NestedNameSpecifier::Identifier:
171 assert(false && "Dependent nested-name-specifier has no DeclContext");
174 case NestedNameSpecifier::Namespace:
175 return NNS->getAsNamespace();
177 case NestedNameSpecifier::TypeSpec:
178 case NestedNameSpecifier::TypeSpecWithTemplate: {
179 const TagType *Tag = NNS->getAsType()->getAs<TagType>();
180 assert(Tag && "Non-tag type in nested-name-specifier");
181 return Tag->getDecl();
184 case NestedNameSpecifier::Global:
185 return Context.getTranslationUnitDecl();
188 // Required to silence a GCC warning.
192 bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
193 if (!SS.isSet() || SS.isInvalid())
196 NestedNameSpecifier *NNS
197 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
198 return NNS->isDependent();
201 // \brief Determine whether this C++ scope specifier refers to an
202 // unknown specialization, i.e., a dependent type that is not the
203 // current instantiation.
204 bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
205 if (!isDependentScopeSpecifier(SS))
208 NestedNameSpecifier *NNS
209 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
210 return getCurrentInstantiationOf(NNS) == 0;
213 /// \brief If the given nested name specifier refers to the current
214 /// instantiation, return the declaration that corresponds to that
215 /// current instantiation (C++0x [temp.dep.type]p1).
217 /// \param NNS a dependent nested name specifier.
218 CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
219 assert(getLangOptions().CPlusPlus && "Only callable in C++");
220 assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
222 if (!NNS->getAsType())
225 QualType T = QualType(NNS->getAsType(), 0);
226 return ::getCurrentInstantiationOf(Context, CurContext, T);
229 /// \brief Require that the context specified by SS be complete.
231 /// If SS refers to a type, this routine checks whether the type is
232 /// complete enough (or can be made complete enough) for name lookup
233 /// into the DeclContext. A type that is not yet completed can be
234 /// considered "complete enough" if it is a class/struct/union/enum
235 /// that is currently being defined. Or, if we have a type that names
236 /// a class template specialization that is not a complete type, we
237 /// will attempt to instantiate that class template.
238 bool Sema::RequireCompleteDeclContext(const CXXScopeSpec &SS) {
239 if (!SS.isSet() || SS.isInvalid())
242 DeclContext *DC = computeDeclContext(SS, true);
243 if (TagDecl *Tag = dyn_cast<TagDecl>(DC)) {
244 // If we're currently defining this type, then lookup into the
245 // type is okay: don't complain that it isn't complete yet.
246 const TagType *TagT = Context.getTypeDeclType(Tag)->getAs<TagType>();
247 if (TagT->isBeingDefined())
250 // The type must be complete.
251 return RequireCompleteType(SS.getRange().getBegin(),
252 Context.getTypeDeclType(Tag),
253 PDiag(diag::err_incomplete_nested_name_spec)
260 /// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
261 /// global scope ('::').
262 Sema::CXXScopeTy *Sema::ActOnCXXGlobalScopeSpecifier(Scope *S,
263 SourceLocation CCLoc) {
264 return NestedNameSpecifier::GlobalSpecifier(Context);
267 /// \brief Determines whether the given declaration is an valid acceptable
268 /// result for name lookup of a nested-name-specifier.
269 bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD) {
273 // Namespace and namespace aliases are fine.
274 if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD))
277 if (!isa<TypeDecl>(SD))
280 // Determine whether we have a class (or, in C++0x, an enum) or
281 // a typedef thereof. If so, build the nested-name-specifier.
282 QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
283 if (T->isDependentType())
285 else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(SD)) {
286 if (TD->getUnderlyingType()->isRecordType() ||
287 (Context.getLangOptions().CPlusPlus0x &&
288 TD->getUnderlyingType()->isEnumeralType()))
290 } else if (isa<RecordDecl>(SD) ||
291 (Context.getLangOptions().CPlusPlus0x && isa<EnumDecl>(SD)))
297 /// \brief If the given nested-name-specifier begins with a bare identifier
298 /// (e.g., Base::), perform name lookup for that identifier as a
299 /// nested-name-specifier within the given scope, and return the result of that
301 NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
305 while (NNS->getPrefix())
306 NNS = NNS->getPrefix();
308 if (NNS->getKind() != NestedNameSpecifier::Identifier)
311 LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(),
312 LookupNestedNameSpecifierName);
313 LookupName(Found, S);
314 assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
316 if (!Found.isSingleResult())
319 NamedDecl *Result = Found.getFoundDecl();
320 if (isAcceptableNestedNameSpecifier(Result))
326 /// \brief Build a new nested-name-specifier for "identifier::", as described
327 /// by ActOnCXXNestedNameSpecifier.
329 /// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
330 /// that it contains an extra parameter \p ScopeLookupResult, which provides
331 /// the result of name lookup within the scope of the nested-name-specifier
332 /// that was computed at template definitino time.
334 /// If ErrorRecoveryLookup is true, then this call is used to improve error
335 /// recovery. This means that it should not emit diagnostics, it should
336 /// just return null on failure. It also means it should only return a valid
337 /// scope if it *knows* that the result is correct. It should not return in a
338 /// dependent context, for example.
339 Sema::CXXScopeTy *Sema::BuildCXXNestedNameSpecifier(Scope *S,
340 const CXXScopeSpec &SS,
341 SourceLocation IdLoc,
342 SourceLocation CCLoc,
345 NamedDecl *ScopeLookupResult,
346 bool EnteringContext,
347 bool ErrorRecoveryLookup) {
348 NestedNameSpecifier *Prefix
349 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
351 LookupResult Found(*this, &II, IdLoc, LookupNestedNameSpecifierName);
353 // Determine where to perform name lookup
354 DeclContext *LookupCtx = 0;
355 bool isDependent = false;
356 if (!ObjectType.isNull()) {
357 // This nested-name-specifier occurs in a member access expression, e.g.,
358 // x->B::f, and we are looking into the type of the object.
359 assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
360 LookupCtx = computeDeclContext(ObjectType);
361 isDependent = ObjectType->isDependentType();
362 } else if (SS.isSet()) {
363 // This nested-name-specifier occurs after another nested-name-specifier,
364 // so long into the context associated with the prior nested-name-specifier.
365 LookupCtx = computeDeclContext(SS, EnteringContext);
366 isDependent = isDependentScopeSpecifier(SS);
367 Found.setContextRange(SS.getRange());
371 bool ObjectTypeSearchedInScope = false;
373 // Perform "qualified" name lookup into the declaration context we
374 // computed, which is either the type of the base of a member access
375 // expression or the declaration context associated with a prior
376 // nested-name-specifier.
378 // The declaration context must be complete.
379 if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS))
382 LookupQualifiedName(Found, LookupCtx);
384 if (!ObjectType.isNull() && Found.empty()) {
385 // C++ [basic.lookup.classref]p4:
386 // If the id-expression in a class member access is a qualified-id of
389 // class-name-or-namespace-name::...
391 // the class-name-or-namespace-name following the . or -> operator is
392 // looked up both in the context of the entire postfix-expression and in
393 // the scope of the class of the object expression. If the name is found
394 // only in the scope of the class of the object expression, the name
395 // shall refer to a class-name. If the name is found only in the
396 // context of the entire postfix-expression, the name shall refer to a
397 // class-name or namespace-name. [...]
399 // Qualified name lookup into a class will not find a namespace-name,
400 // so we do not need to diagnoste that case specifically. However,
401 // this qualified name lookup may find nothing. In that case, perform
402 // unqualified name lookup in the given scope (if available) or
403 // reconstruct the result from when name lookup was performed at template
406 LookupName(Found, S);
407 else if (ScopeLookupResult)
408 Found.addDecl(ScopeLookupResult);
410 ObjectTypeSearchedInScope = true;
412 } else if (isDependent) {
413 // Don't speculate if we're just trying to improve error recovery.
414 if (ErrorRecoveryLookup)
417 // We were not able to compute the declaration context for a dependent
418 // base object type or prior nested-name-specifier, so this
419 // nested-name-specifier refers to an unknown specialization. Just build
420 // a dependent nested-name-specifier.
422 return NestedNameSpecifier::Create(Context, &II);
424 return NestedNameSpecifier::Create(Context, Prefix, &II);
426 // Perform unqualified name lookup in the current scope.
427 LookupName(Found, S);
430 // FIXME: Deal with ambiguities cleanly.
431 NamedDecl *SD = Found.getAsSingle<NamedDecl>();
432 if (isAcceptableNestedNameSpecifier(SD)) {
433 if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) {
434 // C++ [basic.lookup.classref]p4:
435 // [...] If the name is found in both contexts, the
436 // class-name-or-namespace-name shall refer to the same entity.
438 // We already found the name in the scope of the object. Now, look
439 // into the current scope (the scope of the postfix-expression) to
440 // see if we can find the same name there. As above, if there is no
441 // scope, reconstruct the result from the template instantiation itself.
442 NamedDecl *OuterDecl;
444 LookupResult FoundOuter(*this, &II, IdLoc, LookupNestedNameSpecifierName);
445 LookupName(FoundOuter, S);
446 OuterDecl = FoundOuter.getAsSingle<NamedDecl>();
448 OuterDecl = ScopeLookupResult;
450 if (isAcceptableNestedNameSpecifier(OuterDecl) &&
451 OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
452 (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
453 !Context.hasSameType(
454 Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
455 Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
456 if (ErrorRecoveryLookup)
459 Diag(IdLoc, diag::err_nested_name_member_ref_lookup_ambiguous)
461 Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
463 Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope);
465 // Fall through so that we'll pick the name we found in the object
466 // type, since that's probably what the user wanted anyway.
470 if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD))
471 return NestedNameSpecifier::Create(Context, Prefix, Namespace);
473 // FIXME: It would be nice to maintain the namespace alias name, then
474 // see through that alias when resolving the nested-name-specifier down to
475 // a declaration context.
476 if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD))
477 return NestedNameSpecifier::Create(Context, Prefix,
479 Alias->getNamespace());
481 QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
482 return NestedNameSpecifier::Create(Context, Prefix, false,
486 // Otherwise, we have an error case. If we don't want diagnostics, just
487 // return an error now.
488 if (ErrorRecoveryLookup)
491 // If we didn't find anything during our lookup, try again with
492 // ordinary name lookup, which can help us produce better error
495 Found.clear(LookupOrdinaryName);
496 LookupName(Found, S);
501 DiagID = diag::err_expected_class_or_namespace;
502 else if (SS.isSet()) {
503 Diag(IdLoc, diag::err_no_member) << &II << LookupCtx << SS.getRange();
506 DiagID = diag::err_undeclared_var_use;
509 Diag(IdLoc, DiagID) << &II << SS.getRange();
511 Diag(IdLoc, DiagID) << &II;
516 /// ActOnCXXNestedNameSpecifier - Called during parsing of a
517 /// nested-name-specifier. e.g. for "foo::bar::" we parsed "foo::" and now
518 /// we want to resolve "bar::". 'SS' is empty or the previously parsed
519 /// nested-name part ("foo::"), 'IdLoc' is the source location of 'bar',
520 /// 'CCLoc' is the location of '::' and 'II' is the identifier for 'bar'.
521 /// Returns a CXXScopeTy* object representing the C++ scope.
522 Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
523 const CXXScopeSpec &SS,
524 SourceLocation IdLoc,
525 SourceLocation CCLoc,
527 TypeTy *ObjectTypePtr,
528 bool EnteringContext) {
529 return BuildCXXNestedNameSpecifier(S, SS, IdLoc, CCLoc, II,
530 QualType::getFromOpaquePtr(ObjectTypePtr),
531 /*ScopeLookupResult=*/0, EnteringContext,
535 /// IsInvalidUnlessNestedName - This method is used for error recovery
536 /// purposes to determine whether the specified identifier is only valid as
537 /// a nested name specifier, for example a namespace name. It is
538 /// conservatively correct to always return false from this method.
540 /// The arguments are the same as those passed to ActOnCXXNestedNameSpecifier.
541 bool Sema::IsInvalidUnlessNestedName(Scope *S, const CXXScopeSpec &SS,
542 IdentifierInfo &II, TypeTy *ObjectType,
543 bool EnteringContext) {
544 return BuildCXXNestedNameSpecifier(S, SS, SourceLocation(), SourceLocation(),
545 II, QualType::getFromOpaquePtr(ObjectType),
546 /*ScopeLookupResult=*/0, EnteringContext,
550 Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
551 const CXXScopeSpec &SS,
553 SourceRange TypeRange,
554 SourceLocation CCLoc) {
555 NestedNameSpecifier *Prefix
556 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
557 QualType T = GetTypeFromParser(Ty);
558 return NestedNameSpecifier::Create(Context, Prefix, /*FIXME:*/false,
562 bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
563 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
565 NestedNameSpecifier *Qualifier =
566 static_cast<NestedNameSpecifier*>(SS.getScopeRep());
568 // There are only two places a well-formed program may qualify a
569 // declarator: first, when defining a namespace or class member
570 // out-of-line, and second, when naming an explicitly-qualified
571 // friend function. The latter case is governed by
572 // C++03 [basic.lookup.unqual]p10:
573 // In a friend declaration naming a member function, a name used
574 // in the function declarator and not part of a template-argument
575 // in a template-id is first looked up in the scope of the member
576 // function's class. If it is not found, or if the name is part of
577 // a template-argument in a template-id, the look up is as
578 // described for unqualified names in the definition of the class
579 // granting friendship.
580 // i.e. we don't push a scope unless it's a class member.
582 switch (Qualifier->getKind()) {
583 case NestedNameSpecifier::Global:
584 case NestedNameSpecifier::Namespace:
585 // These are always namespace scopes. We never want to enter a
586 // namespace scope from anything but a file context.
587 return CurContext->getLookupContext()->isFileContext();
589 case NestedNameSpecifier::Identifier:
590 case NestedNameSpecifier::TypeSpec:
591 case NestedNameSpecifier::TypeSpecWithTemplate:
592 // These are never namespace scopes.
596 // Silence bogus warning.
600 /// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
601 /// scope or nested-name-specifier) is parsed, part of a declarator-id.
602 /// After this method is called, according to [C++ 3.4.3p3], names should be
603 /// looked up in the declarator-id's scope, until the declarator is parsed and
604 /// ActOnCXXExitDeclaratorScope is called.
605 /// The 'SS' should be a non-empty valid CXXScopeSpec.
606 bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
607 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
608 if (DeclContext *DC = computeDeclContext(SS, true)) {
609 // Before we enter a declarator's context, we need to make sure that
610 // it is a complete declaration context.
611 if (!DC->isDependentContext() && RequireCompleteDeclContext(SS))
614 EnterDeclaratorContext(S, DC);
620 /// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
621 /// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
622 /// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
623 /// Used to indicate that names should revert to being looked up in the
625 void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
626 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
629 if (computeDeclContext(SS, true))
630 ExitDeclaratorContext(S);