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 //===----------------------------------------------------------------------===//
15 #include "clang/AST/ASTContext.h"
16 #include "clang/AST/DeclTemplate.h"
17 #include "clang/AST/ExprCXX.h"
18 #include "clang/AST/NestedNameSpecifier.h"
19 #include "clang/Basic/PartialDiagnostic.h"
20 #include "clang/Parse/DeclSpec.h"
21 #include "llvm/ADT/STLExtras.h"
22 #include "llvm/Support/raw_ostream.h"
23 using namespace clang;
25 /// \brief Compute the DeclContext that is associated with the given type.
27 /// \param T the type for which we are attempting to find a DeclContext.
29 /// \returns the declaration context represented by the type T,
30 /// or NULL if the declaration context cannot be computed (e.g., because it is
31 /// dependent and not the current instantiation).
32 DeclContext *Sema::computeDeclContext(QualType T) {
33 if (const TagType *Tag = T->getAs<TagType>())
34 return Tag->getDecl();
39 /// \brief Compute the DeclContext that is associated with the given
42 /// \param SS the C++ scope specifier as it appears in the source
44 /// \param EnteringContext when true, we will be entering the context of
45 /// this scope specifier, so we can retrieve the declaration context of a
46 /// class template or class template partial specialization even if it is
47 /// not the current instantiation.
49 /// \returns the declaration context represented by the scope specifier @p SS,
50 /// or NULL if the declaration context cannot be computed (e.g., because it is
51 /// dependent and not the current instantiation).
52 DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
53 bool EnteringContext) {
54 if (!SS.isSet() || SS.isInvalid())
57 NestedNameSpecifier *NNS
58 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
59 if (NNS->isDependent()) {
60 // If this nested-name-specifier refers to the current
61 // instantiation, return its DeclContext.
62 if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS))
65 if (EnteringContext) {
66 if (const TemplateSpecializationType *SpecType
67 = dyn_cast_or_null<TemplateSpecializationType>(NNS->getAsType())) {
68 // We are entering the context of the nested name specifier, so try to
69 // match the nested name specifier to either a primary class template
70 // or a class template partial specialization.
71 if (ClassTemplateDecl *ClassTemplate
72 = dyn_cast_or_null<ClassTemplateDecl>(
73 SpecType->getTemplateName().getAsTemplateDecl())) {
75 = Context.getCanonicalType(QualType(SpecType, 0));
77 // If the type of the nested name specifier is the same as the
78 // injected class name of the named class template, we're entering
79 // into that class template definition.
80 QualType Injected = ClassTemplate->getInjectedClassNameType(Context);
81 if (Context.hasSameType(Injected, ContextType))
82 return ClassTemplate->getTemplatedDecl();
84 // If the type of the nested name specifier is the same as the
85 // type of one of the class template's class template partial
86 // specializations, we're entering into the definition of that
87 // class template partial specialization.
88 if (ClassTemplatePartialSpecializationDecl *PartialSpec
89 = ClassTemplate->findPartialSpecialization(ContextType))
92 } else if (const RecordType *RecordT
93 = dyn_cast_or_null<RecordType>(NNS->getAsType())) {
94 // The nested name specifier refers to a member of a class template.
95 return RecordT->getDecl();
102 switch (NNS->getKind()) {
103 case NestedNameSpecifier::Identifier:
104 assert(false && "Dependent nested-name-specifier has no DeclContext");
107 case NestedNameSpecifier::Namespace:
108 return NNS->getAsNamespace();
110 case NestedNameSpecifier::TypeSpec:
111 case NestedNameSpecifier::TypeSpecWithTemplate: {
112 const TagType *Tag = NNS->getAsType()->getAs<TagType>();
113 assert(Tag && "Non-tag type in nested-name-specifier");
114 return Tag->getDecl();
117 case NestedNameSpecifier::Global:
118 return Context.getTranslationUnitDecl();
121 // Required to silence a GCC warning.
125 bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
126 if (!SS.isSet() || SS.isInvalid())
129 NestedNameSpecifier *NNS
130 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
131 return NNS->isDependent();
134 // \brief Determine whether this C++ scope specifier refers to an
135 // unknown specialization, i.e., a dependent type that is not the
136 // current instantiation.
137 bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
138 if (!isDependentScopeSpecifier(SS))
141 NestedNameSpecifier *NNS
142 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
143 return getCurrentInstantiationOf(NNS) == 0;
146 /// \brief If the given nested name specifier refers to the current
147 /// instantiation, return the declaration that corresponds to that
148 /// current instantiation (C++0x [temp.dep.type]p1).
150 /// \param NNS a dependent nested name specifier.
151 CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
152 assert(getLangOptions().CPlusPlus && "Only callable in C++");
153 assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
155 if (!NNS->getAsType())
158 QualType T = QualType(NNS->getAsType(), 0);
159 // If the nested name specifier does not refer to a type, then it
160 // does not refer to the current instantiation.
164 T = Context.getCanonicalType(T);
166 for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getParent()) {
167 // If we've hit a namespace or the global scope, then the
168 // nested-name-specifier can't refer to the current instantiation.
169 if (Ctx->isFileContext())
172 // Skip non-class contexts.
173 CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
177 // If this record type is not dependent,
178 if (!Record->isDependentType())
181 // C++ [temp.dep.type]p1:
183 // In the definition of a class template, a nested class of a
184 // class template, a member of a class template, or a member of a
185 // nested class of a class template, a name refers to the current
186 // instantiation if it is
187 // -- the injected-class-name (9) of the class template or
189 // -- in the definition of a primary class template, the name
190 // of the class template followed by the template argument
191 // list of the primary template (as described below)
193 // -- in the definition of a nested class of a class template,
194 // the name of the nested class referenced as a member of
195 // the current instantiation, or
196 // -- in the definition of a partial specialization, the name
197 // of the class template followed by the template argument
198 // list of the partial specialization enclosed in <>. If
199 // the nth template parameter is a parameter pack, the nth
200 // template argument is a pack expansion (14.6.3) whose
201 // pattern is the name of the parameter pack.
202 // (FIXME: parameter packs)
204 // All of these options come down to having the
205 // nested-name-specifier type that is equivalent to the
206 // injected-class-name of one of the types that is currently in
208 if (Context.getCanonicalType(Context.getTypeDeclType(Record)) == T)
211 if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate()) {
212 QualType InjectedClassName
213 = Template->getInjectedClassNameType(Context);
214 if (T == Context.getCanonicalType(InjectedClassName))
215 return Template->getTemplatedDecl();
217 // FIXME: check for class template partial specializations
223 /// \brief Require that the context specified by SS be complete.
225 /// If SS refers to a type, this routine checks whether the type is
226 /// complete enough (or can be made complete enough) for name lookup
227 /// into the DeclContext. A type that is not yet completed can be
228 /// considered "complete enough" if it is a class/struct/union/enum
229 /// that is currently being defined. Or, if we have a type that names
230 /// a class template specialization that is not a complete type, we
231 /// will attempt to instantiate that class template.
232 bool Sema::RequireCompleteDeclContext(const CXXScopeSpec &SS) {
233 if (!SS.isSet() || SS.isInvalid())
236 DeclContext *DC = computeDeclContext(SS, true);
237 if (TagDecl *Tag = dyn_cast<TagDecl>(DC)) {
238 // If we're currently defining this type, then lookup into the
239 // type is okay: don't complain that it isn't complete yet.
240 const TagType *TagT = Context.getTypeDeclType(Tag)->getAs<TagType>();
241 if (TagT->isBeingDefined())
244 // The type must be complete.
245 return RequireCompleteType(SS.getRange().getBegin(),
246 Context.getTypeDeclType(Tag),
247 PDiag(diag::err_incomplete_nested_name_spec)
254 /// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
255 /// global scope ('::').
256 Sema::CXXScopeTy *Sema::ActOnCXXGlobalScopeSpecifier(Scope *S,
257 SourceLocation CCLoc) {
258 return NestedNameSpecifier::GlobalSpecifier(Context);
261 /// \brief Determines whether the given declaration is an valid acceptable
262 /// result for name lookup of a nested-name-specifier.
263 bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD) {
267 // Namespace and namespace aliases are fine.
268 if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD))
271 if (!isa<TypeDecl>(SD))
274 // Determine whether we have a class (or, in C++0x, an enum) or
275 // a typedef thereof. If so, build the nested-name-specifier.
276 QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
277 if (T->isDependentType())
279 else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(SD)) {
280 if (TD->getUnderlyingType()->isRecordType() ||
281 (Context.getLangOptions().CPlusPlus0x &&
282 TD->getUnderlyingType()->isEnumeralType()))
284 } else if (isa<RecordDecl>(SD) ||
285 (Context.getLangOptions().CPlusPlus0x && isa<EnumDecl>(SD)))
291 /// \brief If the given nested-name-specifier begins with a bare identifier
292 /// (e.g., Base::), perform name lookup for that identifier as a
293 /// nested-name-specifier within the given scope, and return the result of that
295 NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
299 while (NNS->getPrefix())
300 NNS = NNS->getPrefix();
302 if (NNS->getKind() != NestedNameSpecifier::Identifier)
306 LookupName(Found, S, NNS->getAsIdentifier(), LookupNestedNameSpecifierName);
307 assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
309 NamedDecl *Result = Found.getAsSingleDecl(Context);
310 if (isAcceptableNestedNameSpecifier(Result))
316 /// \brief Build a new nested-name-specifier for "identifier::", as described
317 /// by ActOnCXXNestedNameSpecifier.
319 /// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
320 /// that it contains an extra parameter \p ScopeLookupResult, which provides
321 /// the result of name lookup within the scope of the nested-name-specifier
322 /// that was computed at template definitino time.
323 Sema::CXXScopeTy *Sema::BuildCXXNestedNameSpecifier(Scope *S,
324 const CXXScopeSpec &SS,
325 SourceLocation IdLoc,
326 SourceLocation CCLoc,
329 NamedDecl *ScopeLookupResult,
330 bool EnteringContext) {
331 NestedNameSpecifier *Prefix
332 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
334 // Determine where to perform name lookup
335 DeclContext *LookupCtx = 0;
336 bool isDependent = false;
337 if (!ObjectType.isNull()) {
338 // This nested-name-specifier occurs in a member access expression, e.g.,
339 // x->B::f, and we are looking into the type of the object.
340 assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
341 LookupCtx = computeDeclContext(ObjectType);
342 isDependent = ObjectType->isDependentType();
343 } else if (SS.isSet()) {
344 // This nested-name-specifier occurs after another nested-name-specifier,
345 // so long into the context associated with the prior nested-name-specifier.
346 LookupCtx = computeDeclContext(SS, EnteringContext);
347 isDependent = isDependentScopeSpecifier(SS);
351 bool ObjectTypeSearchedInScope = false;
353 // Perform "qualified" name lookup into the declaration context we
354 // computed, which is either the type of the base of a member access
355 // expression or the declaration context associated with a prior
356 // nested-name-specifier.
358 // The declaration context must be complete.
359 if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS))
362 LookupQualifiedName(Found, LookupCtx, &II, LookupNestedNameSpecifierName,
365 if (!ObjectType.isNull() && Found.getKind() == LookupResult::NotFound) {
366 // C++ [basic.lookup.classref]p4:
367 // If the id-expression in a class member access is a qualified-id of
370 // class-name-or-namespace-name::...
372 // the class-name-or-namespace-name following the . or -> operator is
373 // looked up both in the context of the entire postfix-expression and in
374 // the scope of the class of the object expression. If the name is found
375 // only in the scope of the class of the object expression, the name
376 // shall refer to a class-name. If the name is found only in the
377 // context of the entire postfix-expression, the name shall refer to a
378 // class-name or namespace-name. [...]
380 // Qualified name lookup into a class will not find a namespace-name,
381 // so we do not need to diagnoste that case specifically. However,
382 // this qualified name lookup may find nothing. In that case, perform
383 // unqualified name lookup in the given scope (if available) or
384 // reconstruct the result from when name lookup was performed at template
387 LookupName(Found, S, &II, LookupNestedNameSpecifierName);
388 else if (ScopeLookupResult)
389 Found.addDecl(ScopeLookupResult);
391 ObjectTypeSearchedInScope = true;
393 } else if (isDependent) {
394 // We were not able to compute the declaration context for a dependent
395 // base object type or prior nested-name-specifier, so this
396 // nested-name-specifier refers to an unknown specialization. Just build
397 // a dependent nested-name-specifier.
399 return NestedNameSpecifier::Create(Context, &II);
401 return NestedNameSpecifier::Create(Context, Prefix, &II);
403 // Perform unqualified name lookup in the current scope.
404 LookupName(Found, S, &II, LookupNestedNameSpecifierName);
407 // FIXME: Deal with ambiguities cleanly.
408 NamedDecl *SD = Found.getAsSingleDecl(Context);
409 if (isAcceptableNestedNameSpecifier(SD)) {
410 if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) {
411 // C++ [basic.lookup.classref]p4:
412 // [...] If the name is found in both contexts, the
413 // class-name-or-namespace-name shall refer to the same entity.
415 // We already found the name in the scope of the object. Now, look
416 // into the current scope (the scope of the postfix-expression) to
417 // see if we can find the same name there. As above, if there is no
418 // scope, reconstruct the result from the template instantiation itself.
419 NamedDecl *OuterDecl;
421 LookupResult FoundOuter;
422 LookupName(FoundOuter, S, &II, LookupNestedNameSpecifierName);
423 // FIXME: Handle ambiguities!
424 OuterDecl = FoundOuter.getAsSingleDecl(Context);
426 OuterDecl = ScopeLookupResult;
428 if (isAcceptableNestedNameSpecifier(OuterDecl) &&
429 OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
430 (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
431 !Context.hasSameType(
432 Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
433 Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
434 Diag(IdLoc, diag::err_nested_name_member_ref_lookup_ambiguous)
436 Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
438 Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope);
440 // Fall through so that we'll pick the name we found in the object type,
441 // since that's probably what the user wanted anyway.
445 if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD))
446 return NestedNameSpecifier::Create(Context, Prefix, Namespace);
448 // FIXME: It would be nice to maintain the namespace alias name, then
449 // see through that alias when resolving the nested-name-specifier down to
450 // a declaration context.
451 if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD))
452 return NestedNameSpecifier::Create(Context, Prefix,
454 Alias->getNamespace());
456 QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
457 return NestedNameSpecifier::Create(Context, Prefix, false,
461 // If we didn't find anything during our lookup, try again with
462 // ordinary name lookup, which can help us produce better error
466 LookupName(Found, S, &II, LookupOrdinaryName);
467 SD = Found.getAsSingleDecl(Context);
472 DiagID = diag::err_expected_class_or_namespace;
473 else if (SS.isSet()) {
474 Diag(IdLoc, diag::err_no_member) << &II << LookupCtx << SS.getRange();
477 DiagID = diag::err_undeclared_var_use;
480 Diag(IdLoc, DiagID) << &II << SS.getRange();
482 Diag(IdLoc, DiagID) << &II;
487 /// ActOnCXXNestedNameSpecifier - Called during parsing of a
488 /// nested-name-specifier. e.g. for "foo::bar::" we parsed "foo::" and now
489 /// we want to resolve "bar::". 'SS' is empty or the previously parsed
490 /// nested-name part ("foo::"), 'IdLoc' is the source location of 'bar',
491 /// 'CCLoc' is the location of '::' and 'II' is the identifier for 'bar'.
492 /// Returns a CXXScopeTy* object representing the C++ scope.
493 Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
494 const CXXScopeSpec &SS,
495 SourceLocation IdLoc,
496 SourceLocation CCLoc,
498 TypeTy *ObjectTypePtr,
499 bool EnteringContext) {
500 return BuildCXXNestedNameSpecifier(S, SS, IdLoc, CCLoc, II,
501 QualType::getFromOpaquePtr(ObjectTypePtr),
502 /*ScopeLookupResult=*/0, EnteringContext);
505 Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
506 const CXXScopeSpec &SS,
508 SourceRange TypeRange,
509 SourceLocation CCLoc) {
510 NestedNameSpecifier *Prefix
511 = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
512 QualType T = GetTypeFromParser(Ty);
513 return NestedNameSpecifier::Create(Context, Prefix, /*FIXME:*/false,
517 /// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
518 /// scope or nested-name-specifier) is parsed, part of a declarator-id.
519 /// After this method is called, according to [C++ 3.4.3p3], names should be
520 /// looked up in the declarator-id's scope, until the declarator is parsed and
521 /// ActOnCXXExitDeclaratorScope is called.
522 /// The 'SS' should be a non-empty valid CXXScopeSpec.
523 bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
524 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
525 if (DeclContext *DC = computeDeclContext(SS, true)) {
526 // Before we enter a declarator's context, we need to make sure that
527 // it is a complete declaration context.
528 if (!DC->isDependentContext() && RequireCompleteDeclContext(SS))
531 EnterDeclaratorContext(S, DC);
537 /// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
538 /// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
539 /// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
540 /// Used to indicate that names should revert to being looked up in the
542 void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
543 assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
546 if (computeDeclContext(SS, true))
547 ExitDeclaratorContext(S);