SemaCXXScopeSpec.cpp revision 202879
1//===--- SemaCXXScopeSpec.cpp - Semantic Analysis for C++ scope specifiers-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file implements C++ semantic analysis for scope specifiers.
11//
12//===----------------------------------------------------------------------===//
13
14#include "Sema.h"
15#include "Lookup.h"
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"
24using namespace clang;
25
26/// \brief Find the current instantiation that associated with the given type.
27static CXXRecordDecl *
28getCurrentInstantiationOf(ASTContext &Context, DeclContext *CurContext,
29                          QualType T) {
30  if (T.isNull())
31    return 0;
32
33  T = Context.getCanonicalType(T).getUnqualifiedType();
34
35  for (DeclContext *Ctx = CurContext; Ctx; Ctx = Ctx->getLookupParent()) {
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())
39      return 0;
40
41    // Skip non-class contexts.
42    CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(Ctx);
43    if (!Record)
44      continue;
45
46    // If this record type is not dependent,
47    if (!Record->isDependentType())
48      return 0;
49
50    // C++ [temp.dep.type]p1:
51    //
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
57    //        nested class,
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)
61    //        enclosed in <>,
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)
72    //
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
76    // our context.
77    if (Context.getCanonicalType(Context.getTypeDeclType(Record)) == T)
78      return Record;
79
80    if (ClassTemplateDecl *Template = Record->getDescribedClassTemplate()) {
81      QualType InjectedClassName
82        = Template->getInjectedClassNameType(Context);
83      if (T == Context.getCanonicalType(InjectedClassName))
84        return Template->getTemplatedDecl();
85    }
86    // FIXME: check for class template partial specializations
87  }
88
89  return 0;
90}
91
92/// \brief Compute the DeclContext that is associated with the given type.
93///
94/// \param T the type for which we are attempting to find a DeclContext.
95///
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).
99DeclContext *Sema::computeDeclContext(QualType T) {
100  if (const TagType *Tag = T->getAs<TagType>())
101    return Tag->getDecl();
102
103  return ::getCurrentInstantiationOf(Context, CurContext, T);
104}
105
106/// \brief Compute the DeclContext that is associated with the given
107/// scope specifier.
108///
109/// \param SS the C++ scope specifier as it appears in the source
110///
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.
115///
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).
119DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
120                                      bool EnteringContext) {
121  if (!SS.isSet() || SS.isInvalid())
122    return 0;
123
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))
130      return Record;
131
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())) {
141          QualType ContextType
142            = Context.getCanonicalType(QualType(SpecType, 0));
143
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();
150
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))
157            return PartialSpec;
158        }
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();
163      }
164    }
165
166    return 0;
167  }
168
169  switch (NNS->getKind()) {
170  case NestedNameSpecifier::Identifier:
171    assert(false && "Dependent nested-name-specifier has no DeclContext");
172    break;
173
174  case NestedNameSpecifier::Namespace:
175    return NNS->getAsNamespace();
176
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();
182  } break;
183
184  case NestedNameSpecifier::Global:
185    return Context.getTranslationUnitDecl();
186  }
187
188  // Required to silence a GCC warning.
189  return 0;
190}
191
192bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
193  if (!SS.isSet() || SS.isInvalid())
194    return false;
195
196  NestedNameSpecifier *NNS
197    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
198  return NNS->isDependent();
199}
200
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.
204bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
205  if (!isDependentScopeSpecifier(SS))
206    return false;
207
208  NestedNameSpecifier *NNS
209    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
210  return getCurrentInstantiationOf(NNS) == 0;
211}
212
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).
216///
217/// \param NNS a dependent nested name specifier.
218CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
219  assert(getLangOptions().CPlusPlus && "Only callable in C++");
220  assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
221
222  if (!NNS->getAsType())
223    return 0;
224
225  QualType T = QualType(NNS->getAsType(), 0);
226  return ::getCurrentInstantiationOf(Context, CurContext, T);
227}
228
229/// \brief Require that the context specified by SS be complete.
230///
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.
238bool Sema::RequireCompleteDeclContext(const CXXScopeSpec &SS) {
239  if (!SS.isSet() || SS.isInvalid())
240    return false;
241
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())
248      return false;
249
250    // The type must be complete.
251    return RequireCompleteType(SS.getRange().getBegin(),
252                               Context.getTypeDeclType(Tag),
253                               PDiag(diag::err_incomplete_nested_name_spec)
254                                 << SS.getRange());
255  }
256
257  return false;
258}
259
260/// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
261/// global scope ('::').
262Sema::CXXScopeTy *Sema::ActOnCXXGlobalScopeSpecifier(Scope *S,
263                                                     SourceLocation CCLoc) {
264  return NestedNameSpecifier::GlobalSpecifier(Context);
265}
266
267/// \brief Determines whether the given declaration is an valid acceptable
268/// result for name lookup of a nested-name-specifier.
269bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD) {
270  if (!SD)
271    return false;
272
273  // Namespace and namespace aliases are fine.
274  if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD))
275    return true;
276
277  if (!isa<TypeDecl>(SD))
278    return false;
279
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())
284    return true;
285  else if (TypedefDecl *TD = dyn_cast<TypedefDecl>(SD)) {
286    if (TD->getUnderlyingType()->isRecordType() ||
287        (Context.getLangOptions().CPlusPlus0x &&
288         TD->getUnderlyingType()->isEnumeralType()))
289      return true;
290  } else if (isa<RecordDecl>(SD) ||
291             (Context.getLangOptions().CPlusPlus0x && isa<EnumDecl>(SD)))
292    return true;
293
294  return false;
295}
296
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
300/// name lookup.
301NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
302  if (!S || !NNS)
303    return 0;
304
305  while (NNS->getPrefix())
306    NNS = NNS->getPrefix();
307
308  if (NNS->getKind() != NestedNameSpecifier::Identifier)
309    return 0;
310
311  LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(),
312                     LookupNestedNameSpecifierName);
313  LookupName(Found, S);
314  assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
315
316  if (!Found.isSingleResult())
317    return 0;
318
319  NamedDecl *Result = Found.getFoundDecl();
320  if (isAcceptableNestedNameSpecifier(Result))
321    return Result;
322
323  return 0;
324}
325
326/// \brief Build a new nested-name-specifier for "identifier::", as described
327/// by ActOnCXXNestedNameSpecifier.
328///
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 definition time.
333///
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.
339Sema::CXXScopeTy *Sema::BuildCXXNestedNameSpecifier(Scope *S,
340                                                    const CXXScopeSpec &SS,
341                                                    SourceLocation IdLoc,
342                                                    SourceLocation CCLoc,
343                                                    IdentifierInfo &II,
344                                                    QualType ObjectType,
345                                                  NamedDecl *ScopeLookupResult,
346                                                    bool EnteringContext,
347                                                    bool ErrorRecoveryLookup) {
348  NestedNameSpecifier *Prefix
349    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
350
351  LookupResult Found(*this, &II, IdLoc, LookupNestedNameSpecifierName);
352
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());
368  }
369
370
371  bool ObjectTypeSearchedInScope = false;
372  if (LookupCtx) {
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.
377
378    // The declaration context must be complete.
379    if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS))
380      return 0;
381
382    LookupQualifiedName(Found, LookupCtx);
383
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
387      //   the form
388      //
389      //        class-name-or-namespace-name::...
390      //
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. [...]
398      //
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
404      // definition time.
405      if (S)
406        LookupName(Found, S);
407      else if (ScopeLookupResult)
408        Found.addDecl(ScopeLookupResult);
409
410      ObjectTypeSearchedInScope = true;
411    }
412  } else if (isDependent) {
413    // Don't speculate if we're just trying to improve error recovery.
414    if (ErrorRecoveryLookup)
415      return 0;
416
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.
421    if (!Prefix)
422      return NestedNameSpecifier::Create(Context, &II);
423
424    return NestedNameSpecifier::Create(Context, Prefix, &II);
425  } else {
426    // Perform unqualified name lookup in the current scope.
427    LookupName(Found, S);
428  }
429
430  // FIXME: Deal with ambiguities cleanly.
431
432  if (Found.empty() && !ErrorRecoveryLookup) {
433    // We haven't found anything, and we're not recovering from a
434    // different kind of error, so look for typos.
435    DeclarationName Name = Found.getLookupName();
436    if (CorrectTypo(Found, S, &SS, LookupCtx, EnteringContext) &&
437        Found.isSingleResult() &&
438        isAcceptableNestedNameSpecifier(Found.getAsSingle<NamedDecl>())) {
439      if (LookupCtx)
440        Diag(Found.getNameLoc(), diag::err_no_member_suggest)
441          << Name << LookupCtx << Found.getLookupName() << SS.getRange()
442          << CodeModificationHint::CreateReplacement(Found.getNameLoc(),
443                                           Found.getLookupName().getAsString());
444      else
445        Diag(Found.getNameLoc(), diag::err_undeclared_var_use_suggest)
446          << Name << Found.getLookupName()
447          << CodeModificationHint::CreateReplacement(Found.getNameLoc(),
448                                           Found.getLookupName().getAsString());
449
450      if (NamedDecl *ND = Found.getAsSingle<NamedDecl>())
451        Diag(ND->getLocation(), diag::note_previous_decl)
452          << ND->getDeclName();
453    } else
454      Found.clear();
455  }
456
457  NamedDecl *SD = Found.getAsSingle<NamedDecl>();
458  if (isAcceptableNestedNameSpecifier(SD)) {
459    if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) {
460      // C++ [basic.lookup.classref]p4:
461      //   [...] If the name is found in both contexts, the
462      //   class-name-or-namespace-name shall refer to the same entity.
463      //
464      // We already found the name in the scope of the object. Now, look
465      // into the current scope (the scope of the postfix-expression) to
466      // see if we can find the same name there. As above, if there is no
467      // scope, reconstruct the result from the template instantiation itself.
468      NamedDecl *OuterDecl;
469      if (S) {
470        LookupResult FoundOuter(*this, &II, IdLoc, LookupNestedNameSpecifierName);
471        LookupName(FoundOuter, S);
472        OuterDecl = FoundOuter.getAsSingle<NamedDecl>();
473      } else
474        OuterDecl = ScopeLookupResult;
475
476      if (isAcceptableNestedNameSpecifier(OuterDecl) &&
477          OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
478          (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
479           !Context.hasSameType(
480                            Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
481                               Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
482             if (ErrorRecoveryLookup)
483               return 0;
484
485             Diag(IdLoc, diag::err_nested_name_member_ref_lookup_ambiguous)
486               << &II;
487             Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
488               << ObjectType;
489             Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope);
490
491             // Fall through so that we'll pick the name we found in the object
492             // type, since that's probably what the user wanted anyway.
493           }
494    }
495
496    if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD))
497      return NestedNameSpecifier::Create(Context, Prefix, Namespace);
498
499    // FIXME: It would be nice to maintain the namespace alias name, then
500    // see through that alias when resolving the nested-name-specifier down to
501    // a declaration context.
502    if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD))
503      return NestedNameSpecifier::Create(Context, Prefix,
504
505                                         Alias->getNamespace());
506
507    QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
508    return NestedNameSpecifier::Create(Context, Prefix, false,
509                                       T.getTypePtr());
510  }
511
512  // Otherwise, we have an error case.  If we don't want diagnostics, just
513  // return an error now.
514  if (ErrorRecoveryLookup)
515    return 0;
516
517  // If we didn't find anything during our lookup, try again with
518  // ordinary name lookup, which can help us produce better error
519  // messages.
520  if (Found.empty()) {
521    Found.clear(LookupOrdinaryName);
522    LookupName(Found, S);
523  }
524
525  unsigned DiagID;
526  if (!Found.empty())
527    DiagID = diag::err_expected_class_or_namespace;
528  else if (SS.isSet()) {
529    Diag(IdLoc, diag::err_no_member) << &II << LookupCtx << SS.getRange();
530    return 0;
531  } else
532    DiagID = diag::err_undeclared_var_use;
533
534  if (SS.isSet())
535    Diag(IdLoc, DiagID) << &II << SS.getRange();
536  else
537    Diag(IdLoc, DiagID) << &II;
538
539  return 0;
540}
541
542/// ActOnCXXNestedNameSpecifier - Called during parsing of a
543/// nested-name-specifier. e.g. for "foo::bar::" we parsed "foo::" and now
544/// we want to resolve "bar::". 'SS' is empty or the previously parsed
545/// nested-name part ("foo::"), 'IdLoc' is the source location of 'bar',
546/// 'CCLoc' is the location of '::' and 'II' is the identifier for 'bar'.
547/// Returns a CXXScopeTy* object representing the C++ scope.
548Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
549                                                    const CXXScopeSpec &SS,
550                                                    SourceLocation IdLoc,
551                                                    SourceLocation CCLoc,
552                                                    IdentifierInfo &II,
553                                                    TypeTy *ObjectTypePtr,
554                                                    bool EnteringContext) {
555  return BuildCXXNestedNameSpecifier(S, SS, IdLoc, CCLoc, II,
556                                     QualType::getFromOpaquePtr(ObjectTypePtr),
557                                     /*ScopeLookupResult=*/0, EnteringContext,
558                                     false);
559}
560
561/// IsInvalidUnlessNestedName - This method is used for error recovery
562/// purposes to determine whether the specified identifier is only valid as
563/// a nested name specifier, for example a namespace name.  It is
564/// conservatively correct to always return false from this method.
565///
566/// The arguments are the same as those passed to ActOnCXXNestedNameSpecifier.
567bool Sema::IsInvalidUnlessNestedName(Scope *S, const CXXScopeSpec &SS,
568                                     IdentifierInfo &II, TypeTy *ObjectType,
569                                     bool EnteringContext) {
570  return BuildCXXNestedNameSpecifier(S, SS, SourceLocation(), SourceLocation(),
571                                     II, QualType::getFromOpaquePtr(ObjectType),
572                                     /*ScopeLookupResult=*/0, EnteringContext,
573                                     true);
574}
575
576Sema::CXXScopeTy *Sema::ActOnCXXNestedNameSpecifier(Scope *S,
577                                                    const CXXScopeSpec &SS,
578                                                    TypeTy *Ty,
579                                                    SourceRange TypeRange,
580                                                    SourceLocation CCLoc) {
581  NestedNameSpecifier *Prefix
582    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
583  QualType T = GetTypeFromParser(Ty);
584  return NestedNameSpecifier::Create(Context, Prefix, /*FIXME:*/false,
585                                     T.getTypePtr());
586}
587
588bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
589  assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
590
591  NestedNameSpecifier *Qualifier =
592    static_cast<NestedNameSpecifier*>(SS.getScopeRep());
593
594  // There are only two places a well-formed program may qualify a
595  // declarator: first, when defining a namespace or class member
596  // out-of-line, and second, when naming an explicitly-qualified
597  // friend function.  The latter case is governed by
598  // C++03 [basic.lookup.unqual]p10:
599  //   In a friend declaration naming a member function, a name used
600  //   in the function declarator and not part of a template-argument
601  //   in a template-id is first looked up in the scope of the member
602  //   function's class. If it is not found, or if the name is part of
603  //   a template-argument in a template-id, the look up is as
604  //   described for unqualified names in the definition of the class
605  //   granting friendship.
606  // i.e. we don't push a scope unless it's a class member.
607
608  switch (Qualifier->getKind()) {
609  case NestedNameSpecifier::Global:
610  case NestedNameSpecifier::Namespace:
611    // These are always namespace scopes.  We never want to enter a
612    // namespace scope from anything but a file context.
613    return CurContext->getLookupContext()->isFileContext();
614
615  case NestedNameSpecifier::Identifier:
616  case NestedNameSpecifier::TypeSpec:
617  case NestedNameSpecifier::TypeSpecWithTemplate:
618    // These are never namespace scopes.
619    return true;
620  }
621
622  // Silence bogus warning.
623  return false;
624}
625
626/// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
627/// scope or nested-name-specifier) is parsed, part of a declarator-id.
628/// After this method is called, according to [C++ 3.4.3p3], names should be
629/// looked up in the declarator-id's scope, until the declarator is parsed and
630/// ActOnCXXExitDeclaratorScope is called.
631/// The 'SS' should be a non-empty valid CXXScopeSpec.
632bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
633  assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
634
635  if (SS.isInvalid()) return true;
636
637  DeclContext *DC = computeDeclContext(SS, true);
638  if (!DC) return true;
639
640  // Before we enter a declarator's context, we need to make sure that
641  // it is a complete declaration context.
642  if (!DC->isDependentContext() && RequireCompleteDeclContext(SS))
643    return true;
644
645  EnterDeclaratorContext(S, DC);
646  return false;
647}
648
649/// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
650/// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
651/// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
652/// Used to indicate that names should revert to being looked up in the
653/// defining scope.
654void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
655  assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
656  if (SS.isInvalid())
657    return;
658  assert(!SS.isInvalid() && computeDeclContext(SS, true) &&
659         "exiting declarator scope we never really entered");
660  ExitDeclaratorContext(S);
661}
662