SemaCXXScopeSpec.cpp revision 16e46dd0c284296cea819dfbf67942ecef02894d 
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 "clang/Sema/SemaInternal.h"
15#include "clang/Sema/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/Sema/DeclSpec.h"
22#include "TypeLocBuilder.h"
23#include "llvm/ADT/STLExtras.h"
24#include "llvm/Support/raw_ostream.h"
25using namespace clang;
26
27/// \brief Find the current instantiation that associated with the given type.
28static CXXRecordDecl *getCurrentInstantiationOf(QualType T,
29                                                DeclContext *CurContext) {
30  if (T.isNull())
31    return 0;
32
33  const Type *Ty = T->getCanonicalTypeInternal().getTypePtr();
34  if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {
35    CXXRecordDecl *Record = cast<CXXRecordDecl>(RecordTy->getDecl());
36    if (!T->isDependentType())
37      return Record;
38
39    // This may be a member of a class template or class template partial
40    // specialization. If it's part of the current semantic context, then it's
41    // an injected-class-name;
42    for (; !CurContext->isFileContext(); CurContext = CurContext->getParent())
43      if (CurContext->Equals(Record))
44        return Record;
45
46    return 0;
47  } else if (isa<InjectedClassNameType>(Ty))
48    return cast<InjectedClassNameType>(Ty)->getDecl();
49  else
50    return 0;
51}
52
53/// \brief Compute the DeclContext that is associated with the given type.
54///
55/// \param T the type for which we are attempting to find a DeclContext.
56///
57/// \returns the declaration context represented by the type T,
58/// or NULL if the declaration context cannot be computed (e.g., because it is
59/// dependent and not the current instantiation).
60DeclContext *Sema::computeDeclContext(QualType T) {
61  if (!T->isDependentType())
62    if (const TagType *Tag = T->getAs<TagType>())
63      return Tag->getDecl();
64
65  return ::getCurrentInstantiationOf(T, CurContext);
66}
67
68/// \brief Compute the DeclContext that is associated with the given
69/// scope specifier.
70///
71/// \param SS the C++ scope specifier as it appears in the source
72///
73/// \param EnteringContext when true, we will be entering the context of
74/// this scope specifier, so we can retrieve the declaration context of a
75/// class template or class template partial specialization even if it is
76/// not the current instantiation.
77///
78/// \returns the declaration context represented by the scope specifier @p SS,
79/// or NULL if the declaration context cannot be computed (e.g., because it is
80/// dependent and not the current instantiation).
81DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
82                                      bool EnteringContext) {
83  if (!SS.isSet() || SS.isInvalid())
84    return 0;
85
86  NestedNameSpecifier *NNS
87    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
88  if (NNS->isDependent()) {
89    // If this nested-name-specifier refers to the current
90    // instantiation, return its DeclContext.
91    if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS))
92      return Record;
93
94    if (EnteringContext) {
95      const Type *NNSType = NNS->getAsType();
96      if (!NNSType) {
97        return 0;
98      }
99
100      // Look through type alias templates, per C++0x [temp.dep.type]p1.
101      NNSType = Context.getCanonicalType(NNSType);
102      if (const TemplateSpecializationType *SpecType
103            = NNSType->getAs<TemplateSpecializationType>()) {
104        // We are entering the context of the nested name specifier, so try to
105        // match the nested name specifier to either a primary class template
106        // or a class template partial specialization.
107        if (ClassTemplateDecl *ClassTemplate
108              = dyn_cast_or_null<ClassTemplateDecl>(
109                            SpecType->getTemplateName().getAsTemplateDecl())) {
110          QualType ContextType
111            = Context.getCanonicalType(QualType(SpecType, 0));
112
113          // If the type of the nested name specifier is the same as the
114          // injected class name of the named class template, we're entering
115          // into that class template definition.
116          QualType Injected
117            = ClassTemplate->getInjectedClassNameSpecialization();
118          if (Context.hasSameType(Injected, ContextType))
119            return ClassTemplate->getTemplatedDecl();
120
121          // If the type of the nested name specifier is the same as the
122          // type of one of the class template's class template partial
123          // specializations, we're entering into the definition of that
124          // class template partial specialization.
125          if (ClassTemplatePartialSpecializationDecl *PartialSpec
126                = ClassTemplate->findPartialSpecialization(ContextType))
127            return PartialSpec;
128        }
129      } else if (const RecordType *RecordT = NNSType->getAs<RecordType>()) {
130        // The nested name specifier refers to a member of a class template.
131        return RecordT->getDecl();
132      }
133    }
134
135    return 0;
136  }
137
138  switch (NNS->getKind()) {
139  case NestedNameSpecifier::Identifier:
140    llvm_unreachable("Dependent nested-name-specifier has no DeclContext");
141
142  case NestedNameSpecifier::Namespace:
143    return NNS->getAsNamespace();
144
145  case NestedNameSpecifier::NamespaceAlias:
146    return NNS->getAsNamespaceAlias()->getNamespace();
147
148  case NestedNameSpecifier::TypeSpec:
149  case NestedNameSpecifier::TypeSpecWithTemplate: {
150    const TagType *Tag = NNS->getAsType()->getAs<TagType>();
151    assert(Tag && "Non-tag type in nested-name-specifier");
152    return Tag->getDecl();
153  }
154
155  case NestedNameSpecifier::Global:
156    return Context.getTranslationUnitDecl();
157  }
158
159  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
160}
161
162bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
163  if (!SS.isSet() || SS.isInvalid())
164    return false;
165
166  NestedNameSpecifier *NNS
167    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
168  return NNS->isDependent();
169}
170
171// \brief Determine whether this C++ scope specifier refers to an
172// unknown specialization, i.e., a dependent type that is not the
173// current instantiation.
174bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
175  if (!isDependentScopeSpecifier(SS))
176    return false;
177
178  NestedNameSpecifier *NNS
179    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
180  return getCurrentInstantiationOf(NNS) == 0;
181}
182
183/// \brief If the given nested name specifier refers to the current
184/// instantiation, return the declaration that corresponds to that
185/// current instantiation (C++0x [temp.dep.type]p1).
186///
187/// \param NNS a dependent nested name specifier.
188CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
189  assert(getLangOptions().CPlusPlus && "Only callable in C++");
190  assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
191
192  if (!NNS->getAsType())
193    return 0;
194
195  QualType T = QualType(NNS->getAsType(), 0);
196  return ::getCurrentInstantiationOf(T, CurContext);
197}
198
199/// \brief Require that the context specified by SS be complete.
200///
201/// If SS refers to a type, this routine checks whether the type is
202/// complete enough (or can be made complete enough) for name lookup
203/// into the DeclContext. A type that is not yet completed can be
204/// considered "complete enough" if it is a class/struct/union/enum
205/// that is currently being defined. Or, if we have a type that names
206/// a class template specialization that is not a complete type, we
207/// will attempt to instantiate that class template.
208bool Sema::RequireCompleteDeclContext(CXXScopeSpec &SS,
209                                      DeclContext *DC) {
210  assert(DC != 0 && "given null context");
211
212  if (TagDecl *tag = dyn_cast<TagDecl>(DC)) {
213    // If this is a dependent type, then we consider it complete.
214    if (tag->isDependentContext())
215      return false;
216
217    // If we're currently defining this type, then lookup into the
218    // type is okay: don't complain that it isn't complete yet.
219    QualType type = Context.getTypeDeclType(tag);
220    const TagType *tagType = type->getAs<TagType>();
221    if (tagType && tagType->isBeingDefined())
222      return false;
223
224    SourceLocation loc = SS.getLastQualifierNameLoc();
225    if (loc.isInvalid()) loc = SS.getRange().getBegin();
226
227    // The type must be complete.
228    if (RequireCompleteType(loc, type,
229                            PDiag(diag::err_incomplete_nested_name_spec)
230                              << SS.getRange())) {
231      SS.SetInvalid(SS.getRange());
232      return true;
233    }
234
235    // Fixed enum types are complete, but they aren't valid as scopes
236    // until we see a definition, so awkwardly pull out this special
237    // case.
238    if (const EnumType *enumType = dyn_cast_or_null<EnumType>(tagType)) {
239      if (!enumType->getDecl()->isCompleteDefinition()) {
240        Diag(loc, diag::err_incomplete_nested_name_spec)
241          << type << SS.getRange();
242        SS.SetInvalid(SS.getRange());
243        return true;
244      }
245    }
246  }
247
248  return false;
249}
250
251bool Sema::ActOnCXXGlobalScopeSpecifier(Scope *S, SourceLocation CCLoc,
252                                        CXXScopeSpec &SS) {
253  SS.MakeGlobal(Context, CCLoc);
254  return false;
255}
256
257/// \brief Determines whether the given declaration is an valid acceptable
258/// result for name lookup of a nested-name-specifier.
259bool Sema::isAcceptableNestedNameSpecifier(NamedDecl *SD) {
260  if (!SD)
261    return false;
262
263  // Namespace and namespace aliases are fine.
264  if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD))
265    return true;
266
267  if (!isa<TypeDecl>(SD))
268    return false;
269
270  // Determine whether we have a class (or, in C++11, an enum) or
271  // a typedef thereof. If so, build the nested-name-specifier.
272  QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
273  if (T->isDependentType())
274    return true;
275  else if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(SD)) {
276    if (TD->getUnderlyingType()->isRecordType() ||
277        (Context.getLangOptions().CPlusPlus0x &&
278         TD->getUnderlyingType()->isEnumeralType()))
279      return true;
280  } else if (isa<RecordDecl>(SD) ||
281             (Context.getLangOptions().CPlusPlus0x && isa<EnumDecl>(SD)))
282    return true;
283
284  return false;
285}
286
287/// \brief If the given nested-name-specifier begins with a bare identifier
288/// (e.g., Base::), perform name lookup for that identifier as a
289/// nested-name-specifier within the given scope, and return the result of that
290/// name lookup.
291NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
292  if (!S || !NNS)
293    return 0;
294
295  while (NNS->getPrefix())
296    NNS = NNS->getPrefix();
297
298  if (NNS->getKind() != NestedNameSpecifier::Identifier)
299    return 0;
300
301  LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(),
302                     LookupNestedNameSpecifierName);
303  LookupName(Found, S);
304  assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
305
306  if (!Found.isSingleResult())
307    return 0;
308
309  NamedDecl *Result = Found.getFoundDecl();
310  if (isAcceptableNestedNameSpecifier(Result))
311    return Result;
312
313  return 0;
314}
315
316bool Sema::isNonTypeNestedNameSpecifier(Scope *S, CXXScopeSpec &SS,
317                                        SourceLocation IdLoc,
318                                        IdentifierInfo &II,
319                                        ParsedType ObjectTypePtr) {
320  QualType ObjectType = GetTypeFromParser(ObjectTypePtr);
321  LookupResult Found(*this, &II, IdLoc, LookupNestedNameSpecifierName);
322
323  // Determine where to perform name lookup
324  DeclContext *LookupCtx = 0;
325  bool isDependent = false;
326  if (!ObjectType.isNull()) {
327    // This nested-name-specifier occurs in a member access expression, e.g.,
328    // x->B::f, and we are looking into the type of the object.
329    assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
330    LookupCtx = computeDeclContext(ObjectType);
331    isDependent = ObjectType->isDependentType();
332  } else if (SS.isSet()) {
333    // This nested-name-specifier occurs after another nested-name-specifier,
334    // so long into the context associated with the prior nested-name-specifier.
335    LookupCtx = computeDeclContext(SS, false);
336    isDependent = isDependentScopeSpecifier(SS);
337    Found.setContextRange(SS.getRange());
338  }
339
340  if (LookupCtx) {
341    // Perform "qualified" name lookup into the declaration context we
342    // computed, which is either the type of the base of a member access
343    // expression or the declaration context associated with a prior
344    // nested-name-specifier.
345
346    // The declaration context must be complete.
347    if (!LookupCtx->isDependentContext() &&
348        RequireCompleteDeclContext(SS, LookupCtx))
349      return false;
350
351    LookupQualifiedName(Found, LookupCtx);
352  } else if (isDependent) {
353    return false;
354  } else {
355    LookupName(Found, S);
356  }
357  Found.suppressDiagnostics();
358
359  if (NamedDecl *ND = Found.getAsSingle<NamedDecl>())
360    return isa<NamespaceDecl>(ND) || isa<NamespaceAliasDecl>(ND);
361
362  return false;
363}
364
365namespace {
366
367// Callback to only accept typo corrections that can be a valid C++ member
368// intializer: either a non-static field member or a base class.
369class NestedNameSpecifierValidatorCCC : public CorrectionCandidateCallback {
370 public:
371  explicit NestedNameSpecifierValidatorCCC(Sema &SRef)
372      : SRef(SRef) {}
373
374  virtual bool ValidateCandidate(const TypoCorrection &candidate) {
375    return SRef.isAcceptableNestedNameSpecifier(candidate.getCorrectionDecl());
376  }
377
378 private:
379  Sema &SRef;
380};
381
382}
383
384/// \brief Build a new nested-name-specifier for "identifier::", as described
385/// by ActOnCXXNestedNameSpecifier.
386///
387/// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
388/// that it contains an extra parameter \p ScopeLookupResult, which provides
389/// the result of name lookup within the scope of the nested-name-specifier
390/// that was computed at template definition time.
391///
392/// If ErrorRecoveryLookup is true, then this call is used to improve error
393/// recovery.  This means that it should not emit diagnostics, it should
394/// just return true on failure.  It also means it should only return a valid
395/// scope if it *knows* that the result is correct.  It should not return in a
396/// dependent context, for example. Nor will it extend \p SS with the scope
397/// specifier.
398bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
399                                       IdentifierInfo &Identifier,
400                                       SourceLocation IdentifierLoc,
401                                       SourceLocation CCLoc,
402                                       QualType ObjectType,
403                                       bool EnteringContext,
404                                       CXXScopeSpec &SS,
405                                       NamedDecl *ScopeLookupResult,
406                                       bool ErrorRecoveryLookup) {
407  LookupResult Found(*this, &Identifier, IdentifierLoc,
408                     LookupNestedNameSpecifierName);
409
410  // Determine where to perform name lookup
411  DeclContext *LookupCtx = 0;
412  bool isDependent = false;
413  if (!ObjectType.isNull()) {
414    // This nested-name-specifier occurs in a member access expression, e.g.,
415    // x->B::f, and we are looking into the type of the object.
416    assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
417    LookupCtx = computeDeclContext(ObjectType);
418    isDependent = ObjectType->isDependentType();
419  } else if (SS.isSet()) {
420    // This nested-name-specifier occurs after another nested-name-specifier,
421    // so look into the context associated with the prior nested-name-specifier.
422    LookupCtx = computeDeclContext(SS, EnteringContext);
423    isDependent = isDependentScopeSpecifier(SS);
424    Found.setContextRange(SS.getRange());
425  }
426
427
428  bool ObjectTypeSearchedInScope = false;
429  if (LookupCtx) {
430    // Perform "qualified" name lookup into the declaration context we
431    // computed, which is either the type of the base of a member access
432    // expression or the declaration context associated with a prior
433    // nested-name-specifier.
434
435    // The declaration context must be complete.
436    if (!LookupCtx->isDependentContext() &&
437        RequireCompleteDeclContext(SS, LookupCtx))
438      return true;
439
440    LookupQualifiedName(Found, LookupCtx);
441
442    if (!ObjectType.isNull() && Found.empty()) {
443      // C++ [basic.lookup.classref]p4:
444      //   If the id-expression in a class member access is a qualified-id of
445      //   the form
446      //
447      //        class-name-or-namespace-name::...
448      //
449      //   the class-name-or-namespace-name following the . or -> operator is
450      //   looked up both in the context of the entire postfix-expression and in
451      //   the scope of the class of the object expression. If the name is found
452      //   only in the scope of the class of the object expression, the name
453      //   shall refer to a class-name. If the name is found only in the
454      //   context of the entire postfix-expression, the name shall refer to a
455      //   class-name or namespace-name. [...]
456      //
457      // Qualified name lookup into a class will not find a namespace-name,
458      // so we do not need to diagnose that case specifically. However,
459      // this qualified name lookup may find nothing. In that case, perform
460      // unqualified name lookup in the given scope (if available) or
461      // reconstruct the result from when name lookup was performed at template
462      // definition time.
463      if (S)
464        LookupName(Found, S);
465      else if (ScopeLookupResult)
466        Found.addDecl(ScopeLookupResult);
467
468      ObjectTypeSearchedInScope = true;
469    }
470  } else if (!isDependent) {
471    // Perform unqualified name lookup in the current scope.
472    LookupName(Found, S);
473  }
474
475  // If we performed lookup into a dependent context and did not find anything,
476  // that's fine: just build a dependent nested-name-specifier.
477  if (Found.empty() && isDependent &&
478      !(LookupCtx && LookupCtx->isRecord() &&
479        (!cast<CXXRecordDecl>(LookupCtx)->hasDefinition() ||
480         !cast<CXXRecordDecl>(LookupCtx)->hasAnyDependentBases()))) {
481    // Don't speculate if we're just trying to improve error recovery.
482    if (ErrorRecoveryLookup)
483      return true;
484
485    // We were not able to compute the declaration context for a dependent
486    // base object type or prior nested-name-specifier, so this
487    // nested-name-specifier refers to an unknown specialization. Just build
488    // a dependent nested-name-specifier.
489    SS.Extend(Context, &Identifier, IdentifierLoc, CCLoc);
490    return false;
491  }
492
493  // FIXME: Deal with ambiguities cleanly.
494
495  if (Found.empty() && !ErrorRecoveryLookup) {
496    // We haven't found anything, and we're not recovering from a
497    // different kind of error, so look for typos.
498    DeclarationName Name = Found.getLookupName();
499    NestedNameSpecifierValidatorCCC Validator(*this);
500    TypoCorrection Corrected;
501    Found.clear();
502    if ((Corrected = CorrectTypo(Found.getLookupNameInfo(),
503                                 Found.getLookupKind(), S, &SS, Validator,
504                                 LookupCtx, EnteringContext))) {
505      std::string CorrectedStr(Corrected.getAsString(getLangOptions()));
506      std::string CorrectedQuotedStr(Corrected.getQuoted(getLangOptions()));
507      if (LookupCtx)
508        Diag(Found.getNameLoc(), diag::err_no_member_suggest)
509          << Name << LookupCtx << CorrectedQuotedStr << SS.getRange()
510          << FixItHint::CreateReplacement(Found.getNameLoc(), CorrectedStr);
511      else
512        Diag(Found.getNameLoc(), diag::err_undeclared_var_use_suggest)
513          << Name << CorrectedQuotedStr
514          << FixItHint::CreateReplacement(Found.getNameLoc(), CorrectedStr);
515
516      if (NamedDecl *ND = Corrected.getCorrectionDecl()) {
517        Diag(ND->getLocation(), diag::note_previous_decl) << CorrectedQuotedStr;
518        Found.addDecl(ND);
519      }
520      Found.setLookupName(Corrected.getCorrection());
521    } else {
522      Found.setLookupName(&Identifier);
523    }
524  }
525
526  NamedDecl *SD = Found.getAsSingle<NamedDecl>();
527  if (isAcceptableNestedNameSpecifier(SD)) {
528    if (!ObjectType.isNull() && !ObjectTypeSearchedInScope) {
529      // C++ [basic.lookup.classref]p4:
530      //   [...] If the name is found in both contexts, the
531      //   class-name-or-namespace-name shall refer to the same entity.
532      //
533      // We already found the name in the scope of the object. Now, look
534      // into the current scope (the scope of the postfix-expression) to
535      // see if we can find the same name there. As above, if there is no
536      // scope, reconstruct the result from the template instantiation itself.
537      NamedDecl *OuterDecl;
538      if (S) {
539        LookupResult FoundOuter(*this, &Identifier, IdentifierLoc,
540                                LookupNestedNameSpecifierName);
541        LookupName(FoundOuter, S);
542        OuterDecl = FoundOuter.getAsSingle<NamedDecl>();
543      } else
544        OuterDecl = ScopeLookupResult;
545
546      if (isAcceptableNestedNameSpecifier(OuterDecl) &&
547          OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
548          (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
549           !Context.hasSameType(
550                            Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
551                               Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
552         if (ErrorRecoveryLookup)
553           return true;
554
555         Diag(IdentifierLoc,
556              diag::err_nested_name_member_ref_lookup_ambiguous)
557           << &Identifier;
558         Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
559           << ObjectType;
560         Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope);
561
562         // Fall through so that we'll pick the name we found in the object
563         // type, since that's probably what the user wanted anyway.
564       }
565    }
566
567    // If we're just performing this lookup for error-recovery purposes,
568    // don't extend the nested-name-specifier. Just return now.
569    if (ErrorRecoveryLookup)
570      return false;
571
572    if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD)) {
573      SS.Extend(Context, Namespace, IdentifierLoc, CCLoc);
574      return false;
575    }
576
577    if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD)) {
578      SS.Extend(Context, Alias, IdentifierLoc, CCLoc);
579      return false;
580    }
581
582    QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
583    TypeLocBuilder TLB;
584    if (isa<InjectedClassNameType>(T)) {
585      InjectedClassNameTypeLoc InjectedTL
586        = TLB.push<InjectedClassNameTypeLoc>(T);
587      InjectedTL.setNameLoc(IdentifierLoc);
588    } else if (isa<RecordType>(T)) {
589      RecordTypeLoc RecordTL = TLB.push<RecordTypeLoc>(T);
590      RecordTL.setNameLoc(IdentifierLoc);
591    } else if (isa<TypedefType>(T)) {
592      TypedefTypeLoc TypedefTL = TLB.push<TypedefTypeLoc>(T);
593      TypedefTL.setNameLoc(IdentifierLoc);
594    } else if (isa<EnumType>(T)) {
595      EnumTypeLoc EnumTL = TLB.push<EnumTypeLoc>(T);
596      EnumTL.setNameLoc(IdentifierLoc);
597    } else if (isa<TemplateTypeParmType>(T)) {
598      TemplateTypeParmTypeLoc TemplateTypeTL
599        = TLB.push<TemplateTypeParmTypeLoc>(T);
600      TemplateTypeTL.setNameLoc(IdentifierLoc);
601    } else if (isa<UnresolvedUsingType>(T)) {
602      UnresolvedUsingTypeLoc UnresolvedTL
603        = TLB.push<UnresolvedUsingTypeLoc>(T);
604      UnresolvedTL.setNameLoc(IdentifierLoc);
605    } else if (isa<SubstTemplateTypeParmType>(T)) {
606      SubstTemplateTypeParmTypeLoc TL
607        = TLB.push<SubstTemplateTypeParmTypeLoc>(T);
608      TL.setNameLoc(IdentifierLoc);
609    } else if (isa<SubstTemplateTypeParmPackType>(T)) {
610      SubstTemplateTypeParmPackTypeLoc TL
611        = TLB.push<SubstTemplateTypeParmPackTypeLoc>(T);
612      TL.setNameLoc(IdentifierLoc);
613    } else {
614      llvm_unreachable("Unhandled TypeDecl node in nested-name-specifier");
615    }
616
617    if (T->isEnumeralType())
618      Diag(IdentifierLoc, diag::warn_cxx98_compat_enum_nested_name_spec);
619
620    SS.Extend(Context, SourceLocation(), TLB.getTypeLocInContext(Context, T),
621              CCLoc);
622    return false;
623  }
624
625  // Otherwise, we have an error case.  If we don't want diagnostics, just
626  // return an error now.
627  if (ErrorRecoveryLookup)
628    return true;
629
630  // If we didn't find anything during our lookup, try again with
631  // ordinary name lookup, which can help us produce better error
632  // messages.
633  if (Found.empty()) {
634    Found.clear(LookupOrdinaryName);
635    LookupName(Found, S);
636  }
637
638  // In Microsoft mode, if we are within a templated function and we can't
639  // resolve Identifier, then extend the SS with Identifier. This will have
640  // the effect of resolving Identifier during template instantiation.
641  // The goal is to be able to resolve a function call whose
642  // nested-name-specifier is located inside a dependent base class.
643  // Example:
644  //
645  // class C {
646  // public:
647  //    static void foo2() {  }
648  // };
649  // template <class T> class A { public: typedef C D; };
650  //
651  // template <class T> class B : public A<T> {
652  // public:
653  //   void foo() { D::foo2(); }
654  // };
655  if (getLangOptions().MicrosoftExt) {
656    DeclContext *DC = LookupCtx ? LookupCtx : CurContext;
657    if (DC->isDependentContext() && DC->isFunctionOrMethod()) {
658      SS.Extend(Context, &Identifier, IdentifierLoc, CCLoc);
659      return false;
660    }
661  }
662
663  unsigned DiagID;
664  if (!Found.empty())
665    DiagID = diag::err_expected_class_or_namespace;
666  else if (SS.isSet()) {
667    Diag(IdentifierLoc, diag::err_no_member)
668      << &Identifier << LookupCtx << SS.getRange();
669    return true;
670  } else
671    DiagID = diag::err_undeclared_var_use;
672
673  if (SS.isSet())
674    Diag(IdentifierLoc, DiagID) << &Identifier << SS.getRange();
675  else
676    Diag(IdentifierLoc, DiagID) << &Identifier;
677
678  return true;
679}
680
681bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
682                                       IdentifierInfo &Identifier,
683                                       SourceLocation IdentifierLoc,
684                                       SourceLocation CCLoc,
685                                       ParsedType ObjectType,
686                                       bool EnteringContext,
687                                       CXXScopeSpec &SS) {
688  if (SS.isInvalid())
689    return true;
690
691  return BuildCXXNestedNameSpecifier(S, Identifier, IdentifierLoc, CCLoc,
692                                     GetTypeFromParser(ObjectType),
693                                     EnteringContext, SS,
694                                     /*ScopeLookupResult=*/0, false);
695}
696
697bool Sema::ActOnCXXNestedNameSpecifierDecltype(CXXScopeSpec &SS,
698                                               const DeclSpec &DS,
699                                               SourceLocation ColonColonLoc) {
700  if (SS.isInvalid() || DS.getTypeSpecType() == DeclSpec::TST_error)
701    return true;
702
703  assert(DS.getTypeSpecType() == DeclSpec::TST_decltype);
704
705  QualType T = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
706  if (!T->isDependentType() && !T->getAs<TagType>()) {
707    Diag(DS.getTypeSpecTypeLoc(), diag::err_expected_class)
708      << T << getLangOptions().CPlusPlus;
709    return true;
710  }
711
712  TypeLocBuilder TLB;
713  DecltypeTypeLoc DecltypeTL = TLB.push<DecltypeTypeLoc>(T);
714  DecltypeTL.setNameLoc(DS.getTypeSpecTypeLoc());
715  SS.Extend(Context, SourceLocation(), TLB.getTypeLocInContext(Context, T),
716            ColonColonLoc);
717  return false;
718}
719
720/// IsInvalidUnlessNestedName - This method is used for error recovery
721/// purposes to determine whether the specified identifier is only valid as
722/// a nested name specifier, for example a namespace name.  It is
723/// conservatively correct to always return false from this method.
724///
725/// The arguments are the same as those passed to ActOnCXXNestedNameSpecifier.
726bool Sema::IsInvalidUnlessNestedName(Scope *S, CXXScopeSpec &SS,
727                                     IdentifierInfo &Identifier,
728                                     SourceLocation IdentifierLoc,
729                                     SourceLocation ColonLoc,
730                                     ParsedType ObjectType,
731                                     bool EnteringContext) {
732  if (SS.isInvalid())
733    return false;
734
735  return !BuildCXXNestedNameSpecifier(S, Identifier, IdentifierLoc, ColonLoc,
736                                      GetTypeFromParser(ObjectType),
737                                      EnteringContext, SS,
738                                      /*ScopeLookupResult=*/0, true);
739}
740
741bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
742                                       CXXScopeSpec &SS,
743                                       SourceLocation TemplateKWLoc,
744                                       TemplateTy Template,
745                                       SourceLocation TemplateNameLoc,
746                                       SourceLocation LAngleLoc,
747                                       ASTTemplateArgsPtr TemplateArgsIn,
748                                       SourceLocation RAngleLoc,
749                                       SourceLocation CCLoc,
750                                       bool EnteringContext) {
751  if (SS.isInvalid())
752    return true;
753
754  // Translate the parser's template argument list in our AST format.
755  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
756  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
757
758  if (DependentTemplateName *DTN = Template.get().getAsDependentTemplateName()){
759    // Handle a dependent template specialization for which we cannot resolve
760    // the template name.
761    assert(DTN->getQualifier()
762             == static_cast<NestedNameSpecifier*>(SS.getScopeRep()));
763    QualType T = Context.getDependentTemplateSpecializationType(ETK_None,
764                                                          DTN->getQualifier(),
765                                                          DTN->getIdentifier(),
766                                                                TemplateArgs);
767
768    // Create source-location information for this type.
769    TypeLocBuilder Builder;
770    DependentTemplateSpecializationTypeLoc SpecTL
771      = Builder.push<DependentTemplateSpecializationTypeLoc>(T);
772    SpecTL.setLAngleLoc(LAngleLoc);
773    SpecTL.setRAngleLoc(RAngleLoc);
774    SpecTL.setKeywordLoc(SourceLocation());
775    SpecTL.setNameLoc(TemplateNameLoc);
776    SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
777    for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
778      SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
779
780    SS.Extend(Context, TemplateKWLoc, Builder.getTypeLocInContext(Context, T),
781              CCLoc);
782    return false;
783  }
784
785
786  if (Template.get().getAsOverloadedTemplate() ||
787      isa<FunctionTemplateDecl>(Template.get().getAsTemplateDecl())) {
788    SourceRange R(TemplateNameLoc, RAngleLoc);
789    if (SS.getRange().isValid())
790      R.setBegin(SS.getRange().getBegin());
791
792    Diag(CCLoc, diag::err_non_type_template_in_nested_name_specifier)
793      << Template.get() << R;
794    NoteAllFoundTemplates(Template.get());
795    return true;
796  }
797
798  // We were able to resolve the template name to an actual template.
799  // Build an appropriate nested-name-specifier.
800  QualType T = CheckTemplateIdType(Template.get(), TemplateNameLoc,
801                                   TemplateArgs);
802  if (T.isNull())
803    return true;
804
805  // Alias template specializations can produce types which are not valid
806  // nested name specifiers.
807  if (!T->isDependentType() && !T->getAs<TagType>()) {
808    Diag(TemplateNameLoc, diag::err_nested_name_spec_non_tag) << T;
809    NoteAllFoundTemplates(Template.get());
810    return true;
811  }
812
813  // Provide source-location information for the template specialization
814  // type.
815  TypeLocBuilder Builder;
816  TemplateSpecializationTypeLoc SpecTL
817    = Builder.push<TemplateSpecializationTypeLoc>(T);
818
819  SpecTL.setLAngleLoc(LAngleLoc);
820  SpecTL.setRAngleLoc(RAngleLoc);
821  SpecTL.setTemplateNameLoc(TemplateNameLoc);
822  for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
823    SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
824
825
826  SS.Extend(Context, TemplateKWLoc, Builder.getTypeLocInContext(Context, T),
827            CCLoc);
828  return false;
829}
830
831namespace {
832  /// \brief A structure that stores a nested-name-specifier annotation,
833  /// including both the nested-name-specifier
834  struct NestedNameSpecifierAnnotation {
835    NestedNameSpecifier *NNS;
836  };
837}
838
839void *Sema::SaveNestedNameSpecifierAnnotation(CXXScopeSpec &SS) {
840  if (SS.isEmpty() || SS.isInvalid())
841    return 0;
842
843  void *Mem = Context.Allocate((sizeof(NestedNameSpecifierAnnotation) +
844                                                        SS.location_size()),
845                               llvm::alignOf<NestedNameSpecifierAnnotation>());
846  NestedNameSpecifierAnnotation *Annotation
847    = new (Mem) NestedNameSpecifierAnnotation;
848  Annotation->NNS = SS.getScopeRep();
849  memcpy(Annotation + 1, SS.location_data(), SS.location_size());
850  return Annotation;
851}
852
853void Sema::RestoreNestedNameSpecifierAnnotation(void *AnnotationPtr,
854                                                SourceRange AnnotationRange,
855                                                CXXScopeSpec &SS) {
856  if (!AnnotationPtr) {
857    SS.SetInvalid(AnnotationRange);
858    return;
859  }
860
861  NestedNameSpecifierAnnotation *Annotation
862    = static_cast<NestedNameSpecifierAnnotation *>(AnnotationPtr);
863  SS.Adopt(NestedNameSpecifierLoc(Annotation->NNS, Annotation + 1));
864}
865
866bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
867  assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
868
869  NestedNameSpecifier *Qualifier =
870    static_cast<NestedNameSpecifier*>(SS.getScopeRep());
871
872  // There are only two places a well-formed program may qualify a
873  // declarator: first, when defining a namespace or class member
874  // out-of-line, and second, when naming an explicitly-qualified
875  // friend function.  The latter case is governed by
876  // C++03 [basic.lookup.unqual]p10:
877  //   In a friend declaration naming a member function, a name used
878  //   in the function declarator and not part of a template-argument
879  //   in a template-id is first looked up in the scope of the member
880  //   function's class. If it is not found, or if the name is part of
881  //   a template-argument in a template-id, the look up is as
882  //   described for unqualified names in the definition of the class
883  //   granting friendship.
884  // i.e. we don't push a scope unless it's a class member.
885
886  switch (Qualifier->getKind()) {
887  case NestedNameSpecifier::Global:
888  case NestedNameSpecifier::Namespace:
889  case NestedNameSpecifier::NamespaceAlias:
890    // These are always namespace scopes.  We never want to enter a
891    // namespace scope from anything but a file context.
892    return CurContext->getRedeclContext()->isFileContext();
893
894  case NestedNameSpecifier::Identifier:
895  case NestedNameSpecifier::TypeSpec:
896  case NestedNameSpecifier::TypeSpecWithTemplate:
897    // These are never namespace scopes.
898    return true;
899  }
900
901  llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
902}
903
904/// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
905/// scope or nested-name-specifier) is parsed, part of a declarator-id.
906/// After this method is called, according to [C++ 3.4.3p3], names should be
907/// looked up in the declarator-id's scope, until the declarator is parsed and
908/// ActOnCXXExitDeclaratorScope is called.
909/// The 'SS' should be a non-empty valid CXXScopeSpec.
910bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, CXXScopeSpec &SS) {
911  assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
912
913  if (SS.isInvalid()) return true;
914
915  DeclContext *DC = computeDeclContext(SS, true);
916  if (!DC) return true;
917
918  // Before we enter a declarator's context, we need to make sure that
919  // it is a complete declaration context.
920  if (!DC->isDependentContext() && RequireCompleteDeclContext(SS, DC))
921    return true;
922
923  EnterDeclaratorContext(S, DC);
924
925  // Rebuild the nested name specifier for the new scope.
926  if (DC->isDependentContext())
927    RebuildNestedNameSpecifierInCurrentInstantiation(SS);
928
929  return false;
930}
931
932/// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
933/// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
934/// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
935/// Used to indicate that names should revert to being looked up in the
936/// defining scope.
937void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
938  assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
939  if (SS.isInvalid())
940    return;
941  assert(!SS.isInvalid() && computeDeclContext(SS, true) &&
942         "exiting declarator scope we never really entered");
943  ExitDeclaratorContext(S);
944}
945