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      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 "TypeLocBuilder.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 "clang/Sema/Lookup.h"
     23 #include "clang/Sema/Template.h"
     24 #include "llvm/ADT/STLExtras.h"
     25 #include "llvm/Support/raw_ostream.h"
     26 using namespace clang;
     27 
     28 /// \brief Find the current instantiation that associated with the given type.
     29 static CXXRecordDecl *getCurrentInstantiationOf(QualType T,
     30                                                 DeclContext *CurContext) {
     31   if (T.isNull())
     32     return 0;
     33 
     34   const Type *Ty = T->getCanonicalTypeInternal().getTypePtr();
     35   if (const RecordType *RecordTy = dyn_cast<RecordType>(Ty)) {
     36     CXXRecordDecl *Record = cast<CXXRecordDecl>(RecordTy->getDecl());
     37     if (!Record->isDependentContext() ||
     38         Record->isCurrentInstantiation(CurContext))
     39       return Record;
     40 
     41     return 0;
     42   } else if (isa<InjectedClassNameType>(Ty))
     43     return cast<InjectedClassNameType>(Ty)->getDecl();
     44   else
     45     return 0;
     46 }
     47 
     48 /// \brief Compute the DeclContext that is associated with the given type.
     49 ///
     50 /// \param T the type for which we are attempting to find a DeclContext.
     51 ///
     52 /// \returns the declaration context represented by the type T,
     53 /// or NULL if the declaration context cannot be computed (e.g., because it is
     54 /// dependent and not the current instantiation).
     55 DeclContext *Sema::computeDeclContext(QualType T) {
     56   if (!T->isDependentType())
     57     if (const TagType *Tag = T->getAs<TagType>())
     58       return Tag->getDecl();
     59 
     60   return ::getCurrentInstantiationOf(T, CurContext);
     61 }
     62 
     63 /// \brief Compute the DeclContext that is associated with the given
     64 /// scope specifier.
     65 ///
     66 /// \param SS the C++ scope specifier as it appears in the source
     67 ///
     68 /// \param EnteringContext when true, we will be entering the context of
     69 /// this scope specifier, so we can retrieve the declaration context of a
     70 /// class template or class template partial specialization even if it is
     71 /// not the current instantiation.
     72 ///
     73 /// \returns the declaration context represented by the scope specifier @p SS,
     74 /// or NULL if the declaration context cannot be computed (e.g., because it is
     75 /// dependent and not the current instantiation).
     76 DeclContext *Sema::computeDeclContext(const CXXScopeSpec &SS,
     77                                       bool EnteringContext) {
     78   if (!SS.isSet() || SS.isInvalid())
     79     return 0;
     80 
     81   NestedNameSpecifier *NNS
     82     = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
     83   if (NNS->isDependent()) {
     84     // If this nested-name-specifier refers to the current
     85     // instantiation, return its DeclContext.
     86     if (CXXRecordDecl *Record = getCurrentInstantiationOf(NNS))
     87       return Record;
     88 
     89     if (EnteringContext) {
     90       const Type *NNSType = NNS->getAsType();
     91       if (!NNSType) {
     92         return 0;
     93       }
     94 
     95       // Look through type alias templates, per C++0x [temp.dep.type]p1.
     96       NNSType = Context.getCanonicalType(NNSType);
     97       if (const TemplateSpecializationType *SpecType
     98             = NNSType->getAs<TemplateSpecializationType>()) {
     99         // We are entering the context of the nested name specifier, so try to
    100         // match the nested name specifier to either a primary class template
    101         // or a class template partial specialization.
    102         if (ClassTemplateDecl *ClassTemplate
    103               = dyn_cast_or_null<ClassTemplateDecl>(
    104                             SpecType->getTemplateName().getAsTemplateDecl())) {
    105           QualType ContextType
    106             = Context.getCanonicalType(QualType(SpecType, 0));
    107 
    108           // If the type of the nested name specifier is the same as the
    109           // injected class name of the named class template, we're entering
    110           // into that class template definition.
    111           QualType Injected
    112             = ClassTemplate->getInjectedClassNameSpecialization();
    113           if (Context.hasSameType(Injected, ContextType))
    114             return ClassTemplate->getTemplatedDecl();
    115 
    116           // If the type of the nested name specifier is the same as the
    117           // type of one of the class template's class template partial
    118           // specializations, we're entering into the definition of that
    119           // class template partial specialization.
    120           if (ClassTemplatePartialSpecializationDecl *PartialSpec
    121                 = ClassTemplate->findPartialSpecialization(ContextType))
    122             return PartialSpec;
    123         }
    124       } else if (const RecordType *RecordT = NNSType->getAs<RecordType>()) {
    125         // The nested name specifier refers to a member of a class template.
    126         return RecordT->getDecl();
    127       }
    128     }
    129 
    130     return 0;
    131   }
    132 
    133   switch (NNS->getKind()) {
    134   case NestedNameSpecifier::Identifier:
    135     llvm_unreachable("Dependent nested-name-specifier has no DeclContext");
    136 
    137   case NestedNameSpecifier::Namespace:
    138     return NNS->getAsNamespace();
    139 
    140   case NestedNameSpecifier::NamespaceAlias:
    141     return NNS->getAsNamespaceAlias()->getNamespace();
    142 
    143   case NestedNameSpecifier::TypeSpec:
    144   case NestedNameSpecifier::TypeSpecWithTemplate: {
    145     const TagType *Tag = NNS->getAsType()->getAs<TagType>();
    146     assert(Tag && "Non-tag type in nested-name-specifier");
    147     return Tag->getDecl();
    148   }
    149 
    150   case NestedNameSpecifier::Global:
    151     return Context.getTranslationUnitDecl();
    152   }
    153 
    154   llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
    155 }
    156 
    157 bool Sema::isDependentScopeSpecifier(const CXXScopeSpec &SS) {
    158   if (!SS.isSet() || SS.isInvalid())
    159     return false;
    160 
    161   NestedNameSpecifier *NNS
    162     = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
    163   return NNS->isDependent();
    164 }
    165 
    166 // \brief Determine whether this C++ scope specifier refers to an
    167 // unknown specialization, i.e., a dependent type that is not the
    168 // current instantiation.
    169 bool Sema::isUnknownSpecialization(const CXXScopeSpec &SS) {
    170   if (!isDependentScopeSpecifier(SS))
    171     return false;
    172 
    173   NestedNameSpecifier *NNS
    174     = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
    175   return getCurrentInstantiationOf(NNS) == 0;
    176 }
    177 
    178 /// \brief If the given nested name specifier refers to the current
    179 /// instantiation, return the declaration that corresponds to that
    180 /// current instantiation (C++0x [temp.dep.type]p1).
    181 ///
    182 /// \param NNS a dependent nested name specifier.
    183 CXXRecordDecl *Sema::getCurrentInstantiationOf(NestedNameSpecifier *NNS) {
    184   assert(getLangOpts().CPlusPlus && "Only callable in C++");
    185   assert(NNS->isDependent() && "Only dependent nested-name-specifier allowed");
    186 
    187   if (!NNS->getAsType())
    188     return 0;
    189 
    190   QualType T = QualType(NNS->getAsType(), 0);
    191   return ::getCurrentInstantiationOf(T, CurContext);
    192 }
    193 
    194 /// \brief Require that the context specified by SS be complete.
    195 ///
    196 /// If SS refers to a type, this routine checks whether the type is
    197 /// complete enough (or can be made complete enough) for name lookup
    198 /// into the DeclContext. A type that is not yet completed can be
    199 /// considered "complete enough" if it is a class/struct/union/enum
    200 /// that is currently being defined. Or, if we have a type that names
    201 /// a class template specialization that is not a complete type, we
    202 /// will attempt to instantiate that class template.
    203 bool Sema::RequireCompleteDeclContext(CXXScopeSpec &SS,
    204                                       DeclContext *DC) {
    205   assert(DC != 0 && "given null context");
    206 
    207   TagDecl *tag = dyn_cast<TagDecl>(DC);
    208 
    209   // If this is a dependent type, then we consider it complete.
    210   if (!tag || tag->isDependentContext())
    211     return false;
    212 
    213   // If we're currently defining this type, then lookup into the
    214   // type is okay: don't complain that it isn't complete yet.
    215   QualType type = Context.getTypeDeclType(tag);
    216   const TagType *tagType = type->getAs<TagType>();
    217   if (tagType && tagType->isBeingDefined())
    218     return false;
    219 
    220   SourceLocation loc = SS.getLastQualifierNameLoc();
    221   if (loc.isInvalid()) loc = SS.getRange().getBegin();
    222 
    223   // The type must be complete.
    224   if (RequireCompleteType(loc, type, diag::err_incomplete_nested_name_spec,
    225                           SS.getRange())) {
    226     SS.SetInvalid(SS.getRange());
    227     return true;
    228   }
    229 
    230   // Fixed enum types are complete, but they aren't valid as scopes
    231   // until we see a definition, so awkwardly pull out this special
    232   // case.
    233   const EnumType *enumType = dyn_cast_or_null<EnumType>(tagType);
    234   if (!enumType || enumType->getDecl()->isCompleteDefinition())
    235     return false;
    236 
    237   // Try to instantiate the definition, if this is a specialization of an
    238   // enumeration temploid.
    239   EnumDecl *ED = enumType->getDecl();
    240   if (EnumDecl *Pattern = ED->getInstantiatedFromMemberEnum()) {
    241     MemberSpecializationInfo *MSI = ED->getMemberSpecializationInfo();
    242     if (MSI->getTemplateSpecializationKind() != TSK_ExplicitSpecialization) {
    243       if (InstantiateEnum(loc, ED, Pattern, getTemplateInstantiationArgs(ED),
    244                           TSK_ImplicitInstantiation)) {
    245         SS.SetInvalid(SS.getRange());
    246         return true;
    247       }
    248       return false;
    249     }
    250   }
    251 
    252   Diag(loc, diag::err_incomplete_nested_name_spec)
    253     << type << SS.getRange();
    254   SS.SetInvalid(SS.getRange());
    255   return true;
    256 }
    257 
    258 bool Sema::ActOnCXXGlobalScopeSpecifier(Scope *S, SourceLocation CCLoc,
    259                                         CXXScopeSpec &SS) {
    260   SS.MakeGlobal(Context, CCLoc);
    261   return false;
    262 }
    263 
    264 /// \brief Determines whether the given declaration is an valid acceptable
    265 /// result for name lookup of a nested-name-specifier.
    266 bool Sema::isAcceptableNestedNameSpecifier(const NamedDecl *SD) {
    267   if (!SD)
    268     return false;
    269 
    270   // Namespace and namespace aliases are fine.
    271   if (isa<NamespaceDecl>(SD) || isa<NamespaceAliasDecl>(SD))
    272     return true;
    273 
    274   if (!isa<TypeDecl>(SD))
    275     return false;
    276 
    277   // Determine whether we have a class (or, in C++11, an enum) or
    278   // a typedef thereof. If so, build the nested-name-specifier.
    279   QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
    280   if (T->isDependentType())
    281     return true;
    282   else if (const TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(SD)) {
    283     if (TD->getUnderlyingType()->isRecordType() ||
    284         (Context.getLangOpts().CPlusPlus11 &&
    285          TD->getUnderlyingType()->isEnumeralType()))
    286       return true;
    287   } else if (isa<RecordDecl>(SD) ||
    288              (Context.getLangOpts().CPlusPlus11 && isa<EnumDecl>(SD)))
    289     return true;
    290 
    291   return false;
    292 }
    293 
    294 /// \brief If the given nested-name-specifier begins with a bare identifier
    295 /// (e.g., Base::), perform name lookup for that identifier as a
    296 /// nested-name-specifier within the given scope, and return the result of that
    297 /// name lookup.
    298 NamedDecl *Sema::FindFirstQualifierInScope(Scope *S, NestedNameSpecifier *NNS) {
    299   if (!S || !NNS)
    300     return 0;
    301 
    302   while (NNS->getPrefix())
    303     NNS = NNS->getPrefix();
    304 
    305   if (NNS->getKind() != NestedNameSpecifier::Identifier)
    306     return 0;
    307 
    308   LookupResult Found(*this, NNS->getAsIdentifier(), SourceLocation(),
    309                      LookupNestedNameSpecifierName);
    310   LookupName(Found, S);
    311   assert(!Found.isAmbiguous() && "Cannot handle ambiguities here yet");
    312 
    313   if (!Found.isSingleResult())
    314     return 0;
    315 
    316   NamedDecl *Result = Found.getFoundDecl();
    317   if (isAcceptableNestedNameSpecifier(Result))
    318     return Result;
    319 
    320   return 0;
    321 }
    322 
    323 bool Sema::isNonTypeNestedNameSpecifier(Scope *S, CXXScopeSpec &SS,
    324                                         SourceLocation IdLoc,
    325                                         IdentifierInfo &II,
    326                                         ParsedType ObjectTypePtr) {
    327   QualType ObjectType = GetTypeFromParser(ObjectTypePtr);
    328   LookupResult Found(*this, &II, IdLoc, LookupNestedNameSpecifierName);
    329 
    330   // Determine where to perform name lookup
    331   DeclContext *LookupCtx = 0;
    332   bool isDependent = false;
    333   if (!ObjectType.isNull()) {
    334     // This nested-name-specifier occurs in a member access expression, e.g.,
    335     // x->B::f, and we are looking into the type of the object.
    336     assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
    337     LookupCtx = computeDeclContext(ObjectType);
    338     isDependent = ObjectType->isDependentType();
    339   } else if (SS.isSet()) {
    340     // This nested-name-specifier occurs after another nested-name-specifier,
    341     // so long into the context associated with the prior nested-name-specifier.
    342     LookupCtx = computeDeclContext(SS, false);
    343     isDependent = isDependentScopeSpecifier(SS);
    344     Found.setContextRange(SS.getRange());
    345   }
    346 
    347   if (LookupCtx) {
    348     // Perform "qualified" name lookup into the declaration context we
    349     // computed, which is either the type of the base of a member access
    350     // expression or the declaration context associated with a prior
    351     // nested-name-specifier.
    352 
    353     // The declaration context must be complete.
    354     if (!LookupCtx->isDependentContext() &&
    355         RequireCompleteDeclContext(SS, LookupCtx))
    356       return false;
    357 
    358     LookupQualifiedName(Found, LookupCtx);
    359   } else if (isDependent) {
    360     return false;
    361   } else {
    362     LookupName(Found, S);
    363   }
    364   Found.suppressDiagnostics();
    365 
    366   if (NamedDecl *ND = Found.getAsSingle<NamedDecl>())
    367     return isa<NamespaceDecl>(ND) || isa<NamespaceAliasDecl>(ND);
    368 
    369   return false;
    370 }
    371 
    372 namespace {
    373 
    374 // Callback to only accept typo corrections that can be a valid C++ member
    375 // intializer: either a non-static field member or a base class.
    376 class NestedNameSpecifierValidatorCCC : public CorrectionCandidateCallback {
    377  public:
    378   explicit NestedNameSpecifierValidatorCCC(Sema &SRef)
    379       : SRef(SRef) {}
    380 
    381   virtual bool ValidateCandidate(const TypoCorrection &candidate) {
    382     return SRef.isAcceptableNestedNameSpecifier(candidate.getCorrectionDecl());
    383   }
    384 
    385  private:
    386   Sema &SRef;
    387 };
    388 
    389 }
    390 
    391 /// \brief Build a new nested-name-specifier for "identifier::", as described
    392 /// by ActOnCXXNestedNameSpecifier.
    393 ///
    394 /// This routine differs only slightly from ActOnCXXNestedNameSpecifier, in
    395 /// that it contains an extra parameter \p ScopeLookupResult, which provides
    396 /// the result of name lookup within the scope of the nested-name-specifier
    397 /// that was computed at template definition time.
    398 ///
    399 /// If ErrorRecoveryLookup is true, then this call is used to improve error
    400 /// recovery.  This means that it should not emit diagnostics, it should
    401 /// just return true on failure.  It also means it should only return a valid
    402 /// scope if it *knows* that the result is correct.  It should not return in a
    403 /// dependent context, for example. Nor will it extend \p SS with the scope
    404 /// specifier.
    405 bool Sema::BuildCXXNestedNameSpecifier(Scope *S,
    406                                        IdentifierInfo &Identifier,
    407                                        SourceLocation IdentifierLoc,
    408                                        SourceLocation CCLoc,
    409                                        QualType ObjectType,
    410                                        bool EnteringContext,
    411                                        CXXScopeSpec &SS,
    412                                        NamedDecl *ScopeLookupResult,
    413                                        bool ErrorRecoveryLookup) {
    414   LookupResult Found(*this, &Identifier, IdentifierLoc,
    415                      LookupNestedNameSpecifierName);
    416 
    417   // Determine where to perform name lookup
    418   DeclContext *LookupCtx = 0;
    419   bool isDependent = false;
    420   if (!ObjectType.isNull()) {
    421     // This nested-name-specifier occurs in a member access expression, e.g.,
    422     // x->B::f, and we are looking into the type of the object.
    423     assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
    424     LookupCtx = computeDeclContext(ObjectType);
    425     isDependent = ObjectType->isDependentType();
    426   } else if (SS.isSet()) {
    427     // This nested-name-specifier occurs after another nested-name-specifier,
    428     // so look into the context associated with the prior nested-name-specifier.
    429     LookupCtx = computeDeclContext(SS, EnteringContext);
    430     isDependent = isDependentScopeSpecifier(SS);
    431     Found.setContextRange(SS.getRange());
    432   }
    433 
    434 
    435   bool ObjectTypeSearchedInScope = false;
    436   if (LookupCtx) {
    437     // Perform "qualified" name lookup into the declaration context we
    438     // computed, which is either the type of the base of a member access
    439     // expression or the declaration context associated with a prior
    440     // nested-name-specifier.
    441 
    442     // The declaration context must be complete.
    443     if (!LookupCtx->isDependentContext() &&
    444         RequireCompleteDeclContext(SS, LookupCtx))
    445       return true;
    446 
    447     LookupQualifiedName(Found, LookupCtx);
    448 
    449     if (!ObjectType.isNull() && Found.empty()) {
    450       // C++ [basic.lookup.classref]p4:
    451       //   If the id-expression in a class member access is a qualified-id of
    452       //   the form
    453       //
    454       //        class-name-or-namespace-name::...
    455       //
    456       //   the class-name-or-namespace-name following the . or -> operator is
    457       //   looked up both in the context of the entire postfix-expression and in
    458       //   the scope of the class of the object expression. If the name is found
    459       //   only in the scope of the class of the object expression, the name
    460       //   shall refer to a class-name. If the name is found only in the
    461       //   context of the entire postfix-expression, the name shall refer to a
    462       //   class-name or namespace-name. [...]
    463       //
    464       // Qualified name lookup into a class will not find a namespace-name,
    465       // so we do not need to diagnose that case specifically. However,
    466       // this qualified name lookup may find nothing. In that case, perform
    467       // unqualified name lookup in the given scope (if available) or
    468       // reconstruct the result from when name lookup was performed at template
    469       // definition time.
    470       if (S)
    471         LookupName(Found, S);
    472       else if (ScopeLookupResult)
    473         Found.addDecl(ScopeLookupResult);
    474 
    475       ObjectTypeSearchedInScope = true;
    476     }
    477   } else if (!isDependent) {
    478     // Perform unqualified name lookup in the current scope.
    479     LookupName(Found, S);
    480   }
    481 
    482   // If we performed lookup into a dependent context and did not find anything,
    483   // that's fine: just build a dependent nested-name-specifier.
    484   if (Found.empty() && isDependent &&
    485       !(LookupCtx && LookupCtx->isRecord() &&
    486         (!cast<CXXRecordDecl>(LookupCtx)->hasDefinition() ||
    487          !cast<CXXRecordDecl>(LookupCtx)->hasAnyDependentBases()))) {
    488     // Don't speculate if we're just trying to improve error recovery.
    489     if (ErrorRecoveryLookup)
    490       return true;
    491 
    492     // We were not able to compute the declaration context for a dependent
    493     // base object type or prior nested-name-specifier, so this
    494     // nested-name-specifier refers to an unknown specialization. Just build
    495     // a dependent nested-name-specifier.
    496     SS.Extend(Context, &Identifier, IdentifierLoc, CCLoc);
    497     return false;
    498   }
    499 
    500   // FIXME: Deal with ambiguities cleanly.
    501 
    502   if (Found.empty() && !ErrorRecoveryLookup) {
    503     // We haven't found anything, and we're not recovering from a
    504     // different kind of error, so look for typos.
    505     DeclarationName Name = Found.getLookupName();
    506     NestedNameSpecifierValidatorCCC Validator(*this);
    507     TypoCorrection Corrected;
    508     Found.clear();
    509     if ((Corrected = CorrectTypo(Found.getLookupNameInfo(),
    510                                  Found.getLookupKind(), S, &SS, Validator,
    511                                  LookupCtx, EnteringContext))) {
    512       std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
    513       std::string CorrectedQuotedStr(Corrected.getQuoted(getLangOpts()));
    514       if (LookupCtx)
    515         Diag(Found.getNameLoc(), diag::err_no_member_suggest)
    516           << Name << LookupCtx << CorrectedQuotedStr << SS.getRange()
    517           << FixItHint::CreateReplacement(Corrected.getCorrectionRange(),
    518                                           CorrectedStr);
    519       else
    520         Diag(Found.getNameLoc(), diag::err_undeclared_var_use_suggest)
    521           << Name << CorrectedQuotedStr
    522           << FixItHint::CreateReplacement(Found.getNameLoc(), CorrectedStr);
    523 
    524       if (NamedDecl *ND = Corrected.getCorrectionDecl()) {
    525         Diag(ND->getLocation(), diag::note_previous_decl) << CorrectedQuotedStr;
    526         Found.addDecl(ND);
    527       }
    528       Found.setLookupName(Corrected.getCorrection());
    529     } else {
    530       Found.setLookupName(&Identifier);
    531     }
    532   }
    533 
    534   NamedDecl *SD = Found.getAsSingle<NamedDecl>();
    535   if (isAcceptableNestedNameSpecifier(SD)) {
    536     if (!ObjectType.isNull() && !ObjectTypeSearchedInScope &&
    537         !getLangOpts().CPlusPlus11) {
    538       // C++03 [basic.lookup.classref]p4:
    539       //   [...] If the name is found in both contexts, the
    540       //   class-name-or-namespace-name shall refer to the same entity.
    541       //
    542       // We already found the name in the scope of the object. Now, look
    543       // into the current scope (the scope of the postfix-expression) to
    544       // see if we can find the same name there. As above, if there is no
    545       // scope, reconstruct the result from the template instantiation itself.
    546       //
    547       // Note that C++11 does *not* perform this redundant lookup.
    548       NamedDecl *OuterDecl;
    549       if (S) {
    550         LookupResult FoundOuter(*this, &Identifier, IdentifierLoc,
    551                                 LookupNestedNameSpecifierName);
    552         LookupName(FoundOuter, S);
    553         OuterDecl = FoundOuter.getAsSingle<NamedDecl>();
    554       } else
    555         OuterDecl = ScopeLookupResult;
    556 
    557       if (isAcceptableNestedNameSpecifier(OuterDecl) &&
    558           OuterDecl->getCanonicalDecl() != SD->getCanonicalDecl() &&
    559           (!isa<TypeDecl>(OuterDecl) || !isa<TypeDecl>(SD) ||
    560            !Context.hasSameType(
    561                             Context.getTypeDeclType(cast<TypeDecl>(OuterDecl)),
    562                                Context.getTypeDeclType(cast<TypeDecl>(SD))))) {
    563          if (ErrorRecoveryLookup)
    564            return true;
    565 
    566          Diag(IdentifierLoc,
    567               diag::err_nested_name_member_ref_lookup_ambiguous)
    568            << &Identifier;
    569          Diag(SD->getLocation(), diag::note_ambig_member_ref_object_type)
    570            << ObjectType;
    571          Diag(OuterDecl->getLocation(), diag::note_ambig_member_ref_scope);
    572 
    573          // Fall through so that we'll pick the name we found in the object
    574          // type, since that's probably what the user wanted anyway.
    575        }
    576     }
    577 
    578     // If we're just performing this lookup for error-recovery purposes,
    579     // don't extend the nested-name-specifier. Just return now.
    580     if (ErrorRecoveryLookup)
    581       return false;
    582 
    583     if (NamespaceDecl *Namespace = dyn_cast<NamespaceDecl>(SD)) {
    584       SS.Extend(Context, Namespace, IdentifierLoc, CCLoc);
    585       return false;
    586     }
    587 
    588     if (NamespaceAliasDecl *Alias = dyn_cast<NamespaceAliasDecl>(SD)) {
    589       SS.Extend(Context, Alias, IdentifierLoc, CCLoc);
    590       return false;
    591     }
    592 
    593     QualType T = Context.getTypeDeclType(cast<TypeDecl>(SD));
    594     TypeLocBuilder TLB;
    595     if (isa<InjectedClassNameType>(T)) {
    596       InjectedClassNameTypeLoc InjectedTL
    597         = TLB.push<InjectedClassNameTypeLoc>(T);
    598       InjectedTL.setNameLoc(IdentifierLoc);
    599     } else if (isa<RecordType>(T)) {
    600       RecordTypeLoc RecordTL = TLB.push<RecordTypeLoc>(T);
    601       RecordTL.setNameLoc(IdentifierLoc);
    602     } else if (isa<TypedefType>(T)) {
    603       TypedefTypeLoc TypedefTL = TLB.push<TypedefTypeLoc>(T);
    604       TypedefTL.setNameLoc(IdentifierLoc);
    605     } else if (isa<EnumType>(T)) {
    606       EnumTypeLoc EnumTL = TLB.push<EnumTypeLoc>(T);
    607       EnumTL.setNameLoc(IdentifierLoc);
    608     } else if (isa<TemplateTypeParmType>(T)) {
    609       TemplateTypeParmTypeLoc TemplateTypeTL
    610         = TLB.push<TemplateTypeParmTypeLoc>(T);
    611       TemplateTypeTL.setNameLoc(IdentifierLoc);
    612     } else if (isa<UnresolvedUsingType>(T)) {
    613       UnresolvedUsingTypeLoc UnresolvedTL
    614         = TLB.push<UnresolvedUsingTypeLoc>(T);
    615       UnresolvedTL.setNameLoc(IdentifierLoc);
    616     } else if (isa<SubstTemplateTypeParmType>(T)) {
    617       SubstTemplateTypeParmTypeLoc TL
    618         = TLB.push<SubstTemplateTypeParmTypeLoc>(T);
    619       TL.setNameLoc(IdentifierLoc);
    620     } else if (isa<SubstTemplateTypeParmPackType>(T)) {
    621       SubstTemplateTypeParmPackTypeLoc TL
    622         = TLB.push<SubstTemplateTypeParmPackTypeLoc>(T);
    623       TL.setNameLoc(IdentifierLoc);
    624     } else {
    625       llvm_unreachable("Unhandled TypeDecl node in nested-name-specifier");
    626     }
    627 
    628     if (T->isEnumeralType())
    629       Diag(IdentifierLoc, diag::warn_cxx98_compat_enum_nested_name_spec);
    630 
    631     SS.Extend(Context, SourceLocation(), TLB.getTypeLocInContext(Context, T),
    632               CCLoc);
    633     return false;
    634   }
    635 
    636   // Otherwise, we have an error case.  If we don't want diagnostics, just
    637   // return an error now.
    638   if (ErrorRecoveryLookup)
    639     return true;
    640 
    641   // If we didn't find anything during our lookup, try again with
    642   // ordinary name lookup, which can help us produce better error
    643   // messages.
    644   if (Found.empty()) {
    645     Found.clear(LookupOrdinaryName);
    646     LookupName(Found, S);
    647   }
    648 
    649   // In Microsoft mode, if we are within a templated function and we can't
    650   // resolve Identifier, then extend the SS with Identifier. This will have
    651   // the effect of resolving Identifier during template instantiation.
    652   // The goal is to be able to resolve a function call whose
    653   // nested-name-specifier is located inside a dependent base class.
    654   // Example:
    655   //
    656   // class C {
    657   // public:
    658   //    static void foo2() {  }
    659   // };
    660   // template <class T> class A { public: typedef C D; };
    661   //
    662   // template <class T> class B : public A<T> {
    663   // public:
    664   //   void foo() { D::foo2(); }
    665   // };
    666   if (getLangOpts().MicrosoftExt) {
    667     DeclContext *DC = LookupCtx ? LookupCtx : CurContext;
    668     if (DC->isDependentContext() && DC->isFunctionOrMethod()) {
    669       SS.Extend(Context, &Identifier, IdentifierLoc, CCLoc);
    670       return false;
    671     }
    672   }
    673 
    674   unsigned DiagID;
    675   if (!Found.empty())
    676     DiagID = diag::err_expected_class_or_namespace;
    677   else if (SS.isSet()) {
    678     Diag(IdentifierLoc, diag::err_no_member)
    679       << &Identifier << LookupCtx << SS.getRange();
    680     return true;
    681   } else
    682     DiagID = diag::err_undeclared_var_use;
    683 
    684   if (SS.isSet())
    685     Diag(IdentifierLoc, DiagID) << &Identifier << SS.getRange();
    686   else
    687     Diag(IdentifierLoc, DiagID) << &Identifier;
    688 
    689   return true;
    690 }
    691 
    692 bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
    693                                        IdentifierInfo &Identifier,
    694                                        SourceLocation IdentifierLoc,
    695                                        SourceLocation CCLoc,
    696                                        ParsedType ObjectType,
    697                                        bool EnteringContext,
    698                                        CXXScopeSpec &SS) {
    699   if (SS.isInvalid())
    700     return true;
    701 
    702   return BuildCXXNestedNameSpecifier(S, Identifier, IdentifierLoc, CCLoc,
    703                                      GetTypeFromParser(ObjectType),
    704                                      EnteringContext, SS,
    705                                      /*ScopeLookupResult=*/0, false);
    706 }
    707 
    708 bool Sema::ActOnCXXNestedNameSpecifierDecltype(CXXScopeSpec &SS,
    709                                                const DeclSpec &DS,
    710                                                SourceLocation ColonColonLoc) {
    711   if (SS.isInvalid() || DS.getTypeSpecType() == DeclSpec::TST_error)
    712     return true;
    713 
    714   assert(DS.getTypeSpecType() == DeclSpec::TST_decltype);
    715 
    716   QualType T = BuildDecltypeType(DS.getRepAsExpr(), DS.getTypeSpecTypeLoc());
    717   if (!T->isDependentType() && !T->getAs<TagType>()) {
    718     Diag(DS.getTypeSpecTypeLoc(), diag::err_expected_class)
    719       << T << getLangOpts().CPlusPlus;
    720     return true;
    721   }
    722 
    723   TypeLocBuilder TLB;
    724   DecltypeTypeLoc DecltypeTL = TLB.push<DecltypeTypeLoc>(T);
    725   DecltypeTL.setNameLoc(DS.getTypeSpecTypeLoc());
    726   SS.Extend(Context, SourceLocation(), TLB.getTypeLocInContext(Context, T),
    727             ColonColonLoc);
    728   return false;
    729 }
    730 
    731 /// IsInvalidUnlessNestedName - This method is used for error recovery
    732 /// purposes to determine whether the specified identifier is only valid as
    733 /// a nested name specifier, for example a namespace name.  It is
    734 /// conservatively correct to always return false from this method.
    735 ///
    736 /// The arguments are the same as those passed to ActOnCXXNestedNameSpecifier.
    737 bool Sema::IsInvalidUnlessNestedName(Scope *S, CXXScopeSpec &SS,
    738                                      IdentifierInfo &Identifier,
    739                                      SourceLocation IdentifierLoc,
    740                                      SourceLocation ColonLoc,
    741                                      ParsedType ObjectType,
    742                                      bool EnteringContext) {
    743   if (SS.isInvalid())
    744     return false;
    745 
    746   return !BuildCXXNestedNameSpecifier(S, Identifier, IdentifierLoc, ColonLoc,
    747                                       GetTypeFromParser(ObjectType),
    748                                       EnteringContext, SS,
    749                                       /*ScopeLookupResult=*/0, true);
    750 }
    751 
    752 bool Sema::ActOnCXXNestedNameSpecifier(Scope *S,
    753                                        CXXScopeSpec &SS,
    754                                        SourceLocation TemplateKWLoc,
    755                                        TemplateTy Template,
    756                                        SourceLocation TemplateNameLoc,
    757                                        SourceLocation LAngleLoc,
    758                                        ASTTemplateArgsPtr TemplateArgsIn,
    759                                        SourceLocation RAngleLoc,
    760                                        SourceLocation CCLoc,
    761                                        bool EnteringContext) {
    762   if (SS.isInvalid())
    763     return true;
    764 
    765   // Translate the parser's template argument list in our AST format.
    766   TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
    767   translateTemplateArguments(TemplateArgsIn, TemplateArgs);
    768 
    769   if (DependentTemplateName *DTN = Template.get().getAsDependentTemplateName()){
    770     // Handle a dependent template specialization for which we cannot resolve
    771     // the template name.
    772     assert(DTN->getQualifier()
    773              == static_cast<NestedNameSpecifier*>(SS.getScopeRep()));
    774     QualType T = Context.getDependentTemplateSpecializationType(ETK_None,
    775                                                           DTN->getQualifier(),
    776                                                           DTN->getIdentifier(),
    777                                                                 TemplateArgs);
    778 
    779     // Create source-location information for this type.
    780     TypeLocBuilder Builder;
    781     DependentTemplateSpecializationTypeLoc SpecTL
    782       = Builder.push<DependentTemplateSpecializationTypeLoc>(T);
    783     SpecTL.setElaboratedKeywordLoc(SourceLocation());
    784     SpecTL.setQualifierLoc(SS.getWithLocInContext(Context));
    785     SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
    786     SpecTL.setTemplateNameLoc(TemplateNameLoc);
    787     SpecTL.setLAngleLoc(LAngleLoc);
    788     SpecTL.setRAngleLoc(RAngleLoc);
    789     for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
    790       SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
    791 
    792     SS.Extend(Context, TemplateKWLoc, Builder.getTypeLocInContext(Context, T),
    793               CCLoc);
    794     return false;
    795   }
    796 
    797 
    798   if (Template.get().getAsOverloadedTemplate() ||
    799       isa<FunctionTemplateDecl>(Template.get().getAsTemplateDecl())) {
    800     SourceRange R(TemplateNameLoc, RAngleLoc);
    801     if (SS.getRange().isValid())
    802       R.setBegin(SS.getRange().getBegin());
    803 
    804     Diag(CCLoc, diag::err_non_type_template_in_nested_name_specifier)
    805       << Template.get() << R;
    806     NoteAllFoundTemplates(Template.get());
    807     return true;
    808   }
    809 
    810   // We were able to resolve the template name to an actual template.
    811   // Build an appropriate nested-name-specifier.
    812   QualType T = CheckTemplateIdType(Template.get(), TemplateNameLoc,
    813                                    TemplateArgs);
    814   if (T.isNull())
    815     return true;
    816 
    817   // Alias template specializations can produce types which are not valid
    818   // nested name specifiers.
    819   if (!T->isDependentType() && !T->getAs<TagType>()) {
    820     Diag(TemplateNameLoc, diag::err_nested_name_spec_non_tag) << T;
    821     NoteAllFoundTemplates(Template.get());
    822     return true;
    823   }
    824 
    825   // Provide source-location information for the template specialization type.
    826   TypeLocBuilder Builder;
    827   TemplateSpecializationTypeLoc SpecTL
    828     = Builder.push<TemplateSpecializationTypeLoc>(T);
    829   SpecTL.setTemplateKeywordLoc(TemplateKWLoc);
    830   SpecTL.setTemplateNameLoc(TemplateNameLoc);
    831   SpecTL.setLAngleLoc(LAngleLoc);
    832   SpecTL.setRAngleLoc(RAngleLoc);
    833   for (unsigned I = 0, N = TemplateArgs.size(); I != N; ++I)
    834     SpecTL.setArgLocInfo(I, TemplateArgs[I].getLocInfo());
    835 
    836 
    837   SS.Extend(Context, TemplateKWLoc, Builder.getTypeLocInContext(Context, T),
    838             CCLoc);
    839   return false;
    840 }
    841 
    842 namespace {
    843   /// \brief A structure that stores a nested-name-specifier annotation,
    844   /// including both the nested-name-specifier
    845   struct NestedNameSpecifierAnnotation {
    846     NestedNameSpecifier *NNS;
    847   };
    848 }
    849 
    850 void *Sema::SaveNestedNameSpecifierAnnotation(CXXScopeSpec &SS) {
    851   if (SS.isEmpty() || SS.isInvalid())
    852     return 0;
    853 
    854   void *Mem = Context.Allocate((sizeof(NestedNameSpecifierAnnotation) +
    855                                                         SS.location_size()),
    856                                llvm::alignOf<NestedNameSpecifierAnnotation>());
    857   NestedNameSpecifierAnnotation *Annotation
    858     = new (Mem) NestedNameSpecifierAnnotation;
    859   Annotation->NNS = SS.getScopeRep();
    860   memcpy(Annotation + 1, SS.location_data(), SS.location_size());
    861   return Annotation;
    862 }
    863 
    864 void Sema::RestoreNestedNameSpecifierAnnotation(void *AnnotationPtr,
    865                                                 SourceRange AnnotationRange,
    866                                                 CXXScopeSpec &SS) {
    867   if (!AnnotationPtr) {
    868     SS.SetInvalid(AnnotationRange);
    869     return;
    870   }
    871 
    872   NestedNameSpecifierAnnotation *Annotation
    873     = static_cast<NestedNameSpecifierAnnotation *>(AnnotationPtr);
    874   SS.Adopt(NestedNameSpecifierLoc(Annotation->NNS, Annotation + 1));
    875 }
    876 
    877 bool Sema::ShouldEnterDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
    878   assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
    879 
    880   NestedNameSpecifier *Qualifier =
    881     static_cast<NestedNameSpecifier*>(SS.getScopeRep());
    882 
    883   // There are only two places a well-formed program may qualify a
    884   // declarator: first, when defining a namespace or class member
    885   // out-of-line, and second, when naming an explicitly-qualified
    886   // friend function.  The latter case is governed by
    887   // C++03 [basic.lookup.unqual]p10:
    888   //   In a friend declaration naming a member function, a name used
    889   //   in the function declarator and not part of a template-argument
    890   //   in a template-id is first looked up in the scope of the member
    891   //   function's class. If it is not found, or if the name is part of
    892   //   a template-argument in a template-id, the look up is as
    893   //   described for unqualified names in the definition of the class
    894   //   granting friendship.
    895   // i.e. we don't push a scope unless it's a class member.
    896 
    897   switch (Qualifier->getKind()) {
    898   case NestedNameSpecifier::Global:
    899   case NestedNameSpecifier::Namespace:
    900   case NestedNameSpecifier::NamespaceAlias:
    901     // These are always namespace scopes.  We never want to enter a
    902     // namespace scope from anything but a file context.
    903     return CurContext->getRedeclContext()->isFileContext();
    904 
    905   case NestedNameSpecifier::Identifier:
    906   case NestedNameSpecifier::TypeSpec:
    907   case NestedNameSpecifier::TypeSpecWithTemplate:
    908     // These are never namespace scopes.
    909     return true;
    910   }
    911 
    912   llvm_unreachable("Invalid NestedNameSpecifier::Kind!");
    913 }
    914 
    915 /// ActOnCXXEnterDeclaratorScope - Called when a C++ scope specifier (global
    916 /// scope or nested-name-specifier) is parsed, part of a declarator-id.
    917 /// After this method is called, according to [C++ 3.4.3p3], names should be
    918 /// looked up in the declarator-id's scope, until the declarator is parsed and
    919 /// ActOnCXXExitDeclaratorScope is called.
    920 /// The 'SS' should be a non-empty valid CXXScopeSpec.
    921 bool Sema::ActOnCXXEnterDeclaratorScope(Scope *S, CXXScopeSpec &SS) {
    922   assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
    923 
    924   if (SS.isInvalid()) return true;
    925 
    926   DeclContext *DC = computeDeclContext(SS, true);
    927   if (!DC) return true;
    928 
    929   // Before we enter a declarator's context, we need to make sure that
    930   // it is a complete declaration context.
    931   if (!DC->isDependentContext() && RequireCompleteDeclContext(SS, DC))
    932     return true;
    933 
    934   EnterDeclaratorContext(S, DC);
    935 
    936   // Rebuild the nested name specifier for the new scope.
    937   if (DC->isDependentContext())
    938     RebuildNestedNameSpecifierInCurrentInstantiation(SS);
    939 
    940   return false;
    941 }
    942 
    943 /// ActOnCXXExitDeclaratorScope - Called when a declarator that previously
    944 /// invoked ActOnCXXEnterDeclaratorScope(), is finished. 'SS' is the same
    945 /// CXXScopeSpec that was passed to ActOnCXXEnterDeclaratorScope as well.
    946 /// Used to indicate that names should revert to being looked up in the
    947 /// defining scope.
    948 void Sema::ActOnCXXExitDeclaratorScope(Scope *S, const CXXScopeSpec &SS) {
    949   assert(SS.isSet() && "Parser passed invalid CXXScopeSpec.");
    950   if (SS.isInvalid())
    951     return;
    952   assert(!SS.isInvalid() && computeDeclContext(SS, true) &&
    953          "exiting declarator scope we never really entered");
    954   ExitDeclaratorContext(S);
    955 }
    956