Started implementing variable templates. Top level declarations should be fully supported, up to some limitations documented as FIXMEs or TODO. Static data member templates work very partially. Static data member templates of class templates need particular attention...

llvm-svn: 187762

6 files changed, 587 insertions, 39 deletions

diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index a3718fea338..63b1b0ead18 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1041,13 +1041,20 @@ void ASTContext::eraseDeclAttrs(const Decl *D) {
   }
 }
 
+// FIXME: Remove ?
 MemberSpecializationInfo *
 ASTContext::getInstantiatedFromStaticDataMember(const VarDecl *Var) {
   assert(Var->isStaticDataMember() && "Not a static data member");
-  llvm::DenseMap<const VarDecl *, MemberSpecializationInfo *>::iterator Pos
-    = InstantiatedFromStaticDataMember.find(Var);
-  if (Pos == InstantiatedFromStaticDataMember.end())
-    return 0;
+  return getTemplateOrSpecializationInfo(Var)
+      .dyn_cast<MemberSpecializationInfo *>();
+}
+
+ASTContext::TemplateOrSpecializationInfo
+ASTContext::getTemplateOrSpecializationInfo(const VarDecl *Var) {
+  llvm::DenseMap<const VarDecl *, TemplateOrSpecializationInfo>::iterator Pos =
+      TemplateOrInstantiation.find(Var);
+  if (Pos == TemplateOrInstantiation.end())
+    return TemplateOrSpecializationInfo();
 
   return Pos->second;
 }
@@ -1058,10 +1065,16 @@ ASTContext::setInstantiatedFromStaticDataMember(VarDecl *Inst, VarDecl *Tmpl,
                                           SourceLocation PointOfInstantiation) {
   assert(Inst->isStaticDataMember() && "Not a static data member");
   assert(Tmpl->isStaticDataMember() && "Not a static data member");
-  assert(!InstantiatedFromStaticDataMember[Inst] &&
-         "Already noted what static data member was instantiated from");
-  InstantiatedFromStaticDataMember[Inst] 
-    = new (*this) MemberSpecializationInfo(Tmpl, TSK, PointOfInstantiation);
+  setTemplateOrSpecializationInfo(Inst, new (*this) MemberSpecializationInfo(
+                                            Tmpl, TSK, PointOfInstantiation));
+}
+
+void
+ASTContext::setTemplateOrSpecializationInfo(VarDecl *Inst,
+                                            TemplateOrSpecializationInfo TSI) {
+  assert(!TemplateOrInstantiation[Inst] &&
+         "Already noted what the variable was instantiated from");
+  TemplateOrInstantiation[Inst] = TSI;
 }
 
 FunctionDecl *ASTContext::getClassScopeSpecializationPattern(
@@ -7973,20 +7986,20 @@ MangleContext *ASTContext::createMangleContext() {
 CXXABI::~CXXABI() {}
 
 size_t ASTContext::getSideTableAllocatedMemory() const {
-  return ASTRecordLayouts.getMemorySize()
-    + llvm::capacity_in_bytes(ObjCLayouts)
-    + llvm::capacity_in_bytes(KeyFunctions)
-    + llvm::capacity_in_bytes(ObjCImpls)
-    + llvm::capacity_in_bytes(BlockVarCopyInits)
-    + llvm::capacity_in_bytes(DeclAttrs)
-    + llvm::capacity_in_bytes(InstantiatedFromStaticDataMember)
-    + llvm::capacity_in_bytes(InstantiatedFromUsingDecl)
-    + llvm::capacity_in_bytes(InstantiatedFromUsingShadowDecl)
-    + llvm::capacity_in_bytes(InstantiatedFromUnnamedFieldDecl)
-    + llvm::capacity_in_bytes(OverriddenMethods)
-    + llvm::capacity_in_bytes(Types)
-    + llvm::capacity_in_bytes(VariableArrayTypes)
-    + llvm::capacity_in_bytes(ClassScopeSpecializationPattern);
+  return ASTRecordLayouts.getMemorySize() +
+         llvm::capacity_in_bytes(ObjCLayouts) +
+         llvm::capacity_in_bytes(KeyFunctions) +
+         llvm::capacity_in_bytes(ObjCImpls) +
+         llvm::capacity_in_bytes(BlockVarCopyInits) +
+         llvm::capacity_in_bytes(DeclAttrs) +
+         llvm::capacity_in_bytes(TemplateOrInstantiation) +
+         llvm::capacity_in_bytes(InstantiatedFromUsingDecl) +
+         llvm::capacity_in_bytes(InstantiatedFromUsingShadowDecl) +
+         llvm::capacity_in_bytes(InstantiatedFromUnnamedFieldDecl) +
+         llvm::capacity_in_bytes(OverriddenMethods) +
+         llvm::capacity_in_bytes(Types) +
+         llvm::capacity_in_bytes(VariableArrayTypes) +
+         llvm::capacity_in_bytes(ClassScopeSpecializationPattern);
 }
 
 void ASTContext::setManglingNumber(const NamedDecl *ND, unsigned Number) {
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index deac0c5dfbe..922172701f0 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -106,6 +106,8 @@ namespace clang {
 
     bool ImportDefinition(RecordDecl *From, RecordDecl *To, 
                           ImportDefinitionKind Kind = IDK_Default);
+    bool ImportDefinition(VarDecl *From, VarDecl *To,
+                          ImportDefinitionKind Kind = IDK_Default);
     bool ImportDefinition(EnumDecl *From, EnumDecl *To,
                           ImportDefinitionKind Kind = IDK_Default);
     bool ImportDefinition(ObjCInterfaceDecl *From, ObjCInterfaceDecl *To,
@@ -120,9 +122,12 @@ namespace clang {
                                SmallVectorImpl<TemplateArgument> &ToArgs);
     bool IsStructuralMatch(RecordDecl *FromRecord, RecordDecl *ToRecord,
                            bool Complain = true);
+    bool IsStructuralMatch(VarDecl *FromVar, VarDecl *ToVar,
+                           bool Complain = true);
     bool IsStructuralMatch(EnumDecl *FromEnum, EnumDecl *ToRecord);
     bool IsStructuralMatch(EnumConstantDecl *FromEC, EnumConstantDecl *ToEC);
     bool IsStructuralMatch(ClassTemplateDecl *From, ClassTemplateDecl *To);
+    bool IsStructuralMatch(VarTemplateDecl *From, VarTemplateDecl *To);
     Decl *VisitDecl(Decl *D);
     Decl *VisitTranslationUnitDecl(TranslationUnitDecl *D);
     Decl *VisitNamespaceDecl(NamespaceDecl *D);
@@ -157,7 +162,9 @@ namespace clang {
     Decl *VisitClassTemplateDecl(ClassTemplateDecl *D);
     Decl *VisitClassTemplateSpecializationDecl(
                                             ClassTemplateSpecializationDecl *D);
-                            
+    Decl *VisitVarTemplateDecl(VarTemplateDecl *D);
+    Decl *VisitVarTemplateSpecializationDecl(VarTemplateSpecializationDecl *D);
+
     // Importing statements
     Stmt *VisitStmt(Stmt *S);
 
@@ -2017,6 +2024,21 @@ bool ASTNodeImporter::ImportDefinition(RecordDecl *From, RecordDecl *To,
   return false;
 }
 
+bool ASTNodeImporter::ImportDefinition(VarDecl *From, VarDecl *To,
+                                       ImportDefinitionKind Kind) {
+  if (To->getDefinition())
+    return false;
+
+  // FIXME: Can we really import any initializer? Alternatively, we could force
+  // ourselves to import every declaration of a variable and then only use
+  // getInit() here.
+  To->setInit(Importer.Import(const_cast<Expr *>(From->getAnyInitializer())));
+
+  // FIXME: Other bits to merge?
+
+  return false;
+}
+
 bool ASTNodeImporter::ImportDefinition(EnumDecl *From, EnumDecl *To, 
                                        ImportDefinitionKind Kind) {
   if (To->getDefinition() || To->isBeingDefined()) {
@@ -2162,6 +2184,14 @@ bool ASTNodeImporter::IsStructuralMatch(RecordDecl *FromRecord,
   return Ctx.IsStructurallyEquivalent(FromRecord, ToRecord);
 }
 
+bool ASTNodeImporter::IsStructuralMatch(VarDecl *FromVar, VarDecl *ToVar,
+                                        bool Complain) {
+  StructuralEquivalenceContext Ctx(
+      Importer.getFromContext(), Importer.getToContext(),
+      Importer.getNonEquivalentDecls(), false, Complain);
+  return Ctx.IsStructurallyEquivalent(FromVar, ToVar);
+}
+
 bool ASTNodeImporter::IsStructuralMatch(EnumDecl *FromEnum, EnumDecl *ToEnum) {
   StructuralEquivalenceContext Ctx(Importer.getFromContext(),
                                    Importer.getToContext(),
@@ -2188,6 +2218,14 @@ bool ASTNodeImporter::IsStructuralMatch(ClassTemplateDecl *From,
   return Ctx.IsStructurallyEquivalent(From, To);  
 }
 
+bool ASTNodeImporter::IsStructuralMatch(VarTemplateDecl *From,
+                                        VarTemplateDecl *To) {
+  StructuralEquivalenceContext Ctx(Importer.getFromContext(),
+                                   Importer.getToContext(),
+                                   Importer.getNonEquivalentDecls());
+  return Ctx.IsStructurallyEquivalent(From, To);
+}
+
 Decl *ASTNodeImporter::VisitDecl(Decl *D) {
   Importer.FromDiag(D->getLocation(), diag::err_unsupported_ast_node)
     << D->getDeclKindName();
@@ -3092,13 +3130,9 @@ Decl *ASTNodeImporter::VisitVarDecl(VarDecl *D) {
   LexicalDC->addDeclInternal(ToVar);
 
   // Merge the initializer.
-  // FIXME: Can we really import any initializer? Alternatively, we could force
-  // ourselves to import every declaration of a variable and then only use
-  // getInit() here.
-  ToVar->setInit(Importer.Import(const_cast<Expr *>(D->getAnyInitializer())));
+  if (ImportDefinition(D, ToVar))
+    return 0;
 
-  // FIXME: Other bits to merge?
-  
   return ToVar;
 }
 
@@ -4112,6 +4146,205 @@ Decl *ASTNodeImporter::VisitClassTemplateSpecializationDecl(
   return D2;
 }
 
+Decl *ASTNodeImporter::VisitVarTemplateDecl(VarTemplateDecl *D) {
+  // If this variable has a definition in the translation unit we're coming
+  // from,
+  // but this particular declaration is not that definition, import the
+  // definition and map to that.
+  VarDecl *Definition =
+      cast_or_null<VarDecl>(D->getTemplatedDecl()->getDefinition());
+  if (Definition && Definition != D->getTemplatedDecl()) {
+    Decl *ImportedDef = Importer.Import(Definition->getDescribedVarTemplate());
+    if (!ImportedDef)
+      return 0;
+
+    return Importer.Imported(D, ImportedDef);
+  }
+
+  // Import the major distinguishing characteristics of this variable template.
+  DeclContext *DC, *LexicalDC;
+  DeclarationName Name;
+  SourceLocation Loc;
+  if (ImportDeclParts(D, DC, LexicalDC, Name, Loc))
+    return 0;
+
+  // We may already have a template of the same name; try to find and match it.
+  assert(!DC->isFunctionOrMethod() &&
+         "Variable templates cannot be declared at function scope");
+  SmallVector<NamedDecl *, 4> ConflictingDecls;
+  SmallVector<NamedDecl *, 2> FoundDecls;
+  DC->localUncachedLookup(Name, FoundDecls);
+  for (unsigned I = 0, N = FoundDecls.size(); I != N; ++I) {
+    if (!FoundDecls[I]->isInIdentifierNamespace(Decl::IDNS_Ordinary))
+      continue;
+
+    Decl *Found = FoundDecls[I];
+    if (VarTemplateDecl *FoundTemplate = dyn_cast<VarTemplateDecl>(Found)) {
+      if (IsStructuralMatch(D, FoundTemplate)) {
+        // The variable templates structurally match; call it the same template.
+        Importer.Imported(D->getTemplatedDecl(),
+                          FoundTemplate->getTemplatedDecl());
+        return Importer.Imported(D, FoundTemplate);
+      }
+    }
+
+    ConflictingDecls.push_back(FoundDecls[I]);
+  }
+
+  if (!ConflictingDecls.empty()) {
+    Name = Importer.HandleNameConflict(Name, DC, Decl::IDNS_Ordinary,
+                                       ConflictingDecls.data(),
+                                       ConflictingDecls.size());
+  }
+
+  if (!Name)
+    return 0;
+
+  VarDecl *DTemplated = D->getTemplatedDecl();
+
+  // Import the type.
+  QualType T = Importer.Import(DTemplated->getType());
+  if (T.isNull())
+    return 0;
+
+  // Create the declaration that is being templated.
+  SourceLocation StartLoc = Importer.Import(DTemplated->getLocStart());
+  SourceLocation IdLoc = Importer.Import(DTemplated->getLocation());
+  TypeSourceInfo *TInfo = Importer.Import(DTemplated->getTypeSourceInfo());
+  VarDecl *D2Templated = VarDecl::Create(Importer.getToContext(), DC, StartLoc,
+                                         IdLoc, Name.getAsIdentifierInfo(), T,
+                                         TInfo, DTemplated->getStorageClass());
+  D2Templated->setAccess(DTemplated->getAccess());
+  D2Templated->setQualifierInfo(Importer.Import(DTemplated->getQualifierLoc()));
+  D2Templated->setLexicalDeclContext(LexicalDC);
+
+  // Importer.Imported(DTemplated, D2Templated);
+  // LexicalDC->addDeclInternal(D2Templated);
+
+  // Merge the initializer.
+  if (ImportDefinition(DTemplated, D2Templated))
+    return 0;
+
+  // Create the variable template declaration itself.
+  TemplateParameterList *TemplateParams =
+      ImportTemplateParameterList(D->getTemplateParameters());
+  if (!TemplateParams)
+    return 0;
+
+  VarTemplateDecl *D2 = VarTemplateDecl::Create(
+      Importer.getToContext(), DC, Loc, Name, TemplateParams, D2Templated,
+      /*PrevDecl=*/0);
+  D2Templated->setDescribedVarTemplate(D2);
+
+  D2->setAccess(D->getAccess());
+  D2->setLexicalDeclContext(LexicalDC);
+  LexicalDC->addDeclInternal(D2);
+
+  // Note the relationship between the variable templates.
+  Importer.Imported(D, D2);
+  Importer.Imported(DTemplated, D2Templated);
+
+  if (DTemplated->isThisDeclarationADefinition() &&
+      !D2Templated->isThisDeclarationADefinition()) {
+    // FIXME: Import definition!
+  }
+
+  return D2;
+}
+
+Decl *ASTNodeImporter::VisitVarTemplateSpecializationDecl(
+    VarTemplateSpecializationDecl *D) {
+  // If this record has a definition in the translation unit we're coming from,
+  // but this particular declaration is not that definition, import the
+  // definition and map to that.
+  VarDecl *Definition = D->getDefinition();
+  if (Definition && Definition != D) {
+    Decl *ImportedDef = Importer.Import(Definition);
+    if (!ImportedDef)
+      return 0;
+
+    return Importer.Imported(D, ImportedDef);
+  }
+
+  VarTemplateDecl *VarTemplate = cast_or_null<VarTemplateDecl>(
+      Importer.Import(D->getSpecializedTemplate()));
+  if (!VarTemplate)
+    return 0;
+
+  // Import the context of this declaration.
+  DeclContext *DC = VarTemplate->getDeclContext();
+  if (!DC)
+    return 0;
+
+  DeclContext *LexicalDC = DC;
+  if (D->getDeclContext() != D->getLexicalDeclContext()) {
+    LexicalDC = Importer.ImportContext(D->getLexicalDeclContext());
+    if (!LexicalDC)
+      return 0;
+  }
+
+  // Import the location of this declaration.
+  SourceLocation StartLoc = Importer.Import(D->getLocStart());
+  SourceLocation IdLoc = Importer.Import(D->getLocation());
+
+  // Import template arguments.
+  SmallVector<TemplateArgument, 2> TemplateArgs;
+  if (ImportTemplateArguments(D->getTemplateArgs().data(),
+                              D->getTemplateArgs().size(), TemplateArgs))
+    return 0;
+
+  // Try to find an existing specialization with these template arguments.
+  void *InsertPos = 0;
+  VarTemplateSpecializationDecl *D2 = VarTemplate->findSpecialization(
+      TemplateArgs.data(), TemplateArgs.size(), InsertPos);
+  if (D2) {
+    // We already have a variable template specialization with these template
+    // arguments.
+
+    // FIXME: Check for specialization vs. instantiation errors.
+
+    if (VarDecl *FoundDef = D2->getDefinition()) {
+      if (!D->isThisDeclarationADefinition() ||
+          IsStructuralMatch(D, FoundDef)) {
+        // The record types structurally match, or the "from" translation
+        // unit only had a forward declaration anyway; call it the same
+        // variable.
+        return Importer.Imported(D, FoundDef);
+      }
+    }
+  } else {
+
+    // Import the type.
+    QualType T = Importer.Import(D->getType());
+    if (T.isNull())
+      return 0;
+    TypeSourceInfo *TInfo = Importer.Import(D->getTypeSourceInfo());
+
+    // Create a new specialization.
+    D2 = VarTemplateSpecializationDecl::Create(
+        Importer.getToContext(), DC, StartLoc, IdLoc, VarTemplate, T, TInfo,
+        D->getStorageClass(), TemplateArgs.data(), TemplateArgs.size());
+    D2->setSpecializationKind(D->getSpecializationKind());
+    D2->setTemplateArgsInfo(D->getTemplateArgsInfo());
+
+    // Add this specialization to the class template.
+    VarTemplate->AddSpecialization(D2, InsertPos);
+
+    // Import the qualifier, if any.
+    D2->setQualifierInfo(Importer.Import(D->getQualifierLoc()));
+
+    // Add the specialization to this context.
+    D2->setLexicalDeclContext(LexicalDC);
+    LexicalDC->addDeclInternal(D2);
+  }
+  Importer.Imported(D, D2);
+
+  if (D->isThisDeclarationADefinition() && ImportDefinition(D, D2))
+    return 0;
+
+  return D2;
+}
+
 //----------------------------------------------------------------------------
 // Import Statements
 //----------------------------------------------------------------------------
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 772f7353c36..9562879de6a 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -1557,6 +1557,17 @@ const char *VarDecl::getStorageClassSpecifierString(StorageClass SC) {
   llvm_unreachable("Invalid storage class");
 }
 
+VarDecl::VarDecl(Kind DK, DeclContext *DC, SourceLocation StartLoc,
+                 SourceLocation IdLoc, IdentifierInfo *Id, QualType T,
+                 TypeSourceInfo *TInfo, StorageClass SC)
+    : DeclaratorDecl(DK, DC, IdLoc, Id, T, TInfo, StartLoc), Init() {
+  assert(sizeof(VarDeclBitfields) <= sizeof(unsigned));
+  assert(sizeof(ParmVarDeclBitfields) <= sizeof(unsigned));
+  AllBits = 0;
+  VarDeclBits.SClass = SC;
+  // Everything else is implicitly initialized to false.
+}
+
 VarDecl *VarDecl::Create(ASTContext &C, DeclContext *DC,
                          SourceLocation StartL, SourceLocation IdL,
                          IdentifierInfo *Id, QualType T, TypeSourceInfo *TInfo,
@@ -1952,28 +1963,63 @@ VarDecl *VarDecl::getInstantiatedFromStaticDataMember() const {
 }
 
 TemplateSpecializationKind VarDecl::getTemplateSpecializationKind() const {
+  if (const VarTemplateSpecializationDecl *Spec =
+          dyn_cast<VarTemplateSpecializationDecl>(this))
+    return Spec->getSpecializationKind();
+
   if (MemberSpecializationInfo *MSI = getMemberSpecializationInfo())
     return MSI->getTemplateSpecializationKind();
   
   return TSK_Undeclared;
 }
 
+VarTemplateDecl *VarDecl::getDescribedVarTemplate() const {
+  return getASTContext().getTemplateOrSpecializationInfo(this)
+      .dyn_cast<VarTemplateDecl *>();
+}
+
+void VarDecl::setDescribedVarTemplate(VarTemplateDecl *Template) {
+  getASTContext().setTemplateOrSpecializationInfo(this, Template);
+}
+
 MemberSpecializationInfo *VarDecl::getMemberSpecializationInfo() const {
   if (isStaticDataMember())
-    return getASTContext().getInstantiatedFromStaticDataMember(this);
-
+    // FIXME: Remove ?
+    // return getASTContext().getInstantiatedFromStaticDataMember(this);
+    return getASTContext().getTemplateOrSpecializationInfo(this)
+        .dyn_cast<MemberSpecializationInfo *>();
   return 0;
 }
 
 void VarDecl::setTemplateSpecializationKind(TemplateSpecializationKind TSK,
                                          SourceLocation PointOfInstantiation) {
-  MemberSpecializationInfo *MSI = getMemberSpecializationInfo();
-  assert(MSI && "Not an instantiated static data member?");
-  MSI->setTemplateSpecializationKind(TSK);
-  if (TSK != TSK_ExplicitSpecialization &&
-      PointOfInstantiation.isValid() &&
-      MSI->getPointOfInstantiation().isInvalid())
-    MSI->setPointOfInstantiation(PointOfInstantiation);
+  if (VarTemplateSpecializationDecl *Spec =
+          dyn_cast<VarTemplateSpecializationDecl>(this)) {
+    Spec->setSpecializationKind(TSK);
+    if (TSK != TSK_ExplicitSpecialization && PointOfInstantiation.isValid() &&
+        Spec->getPointOfInstantiation().isInvalid())
+      Spec->setPointOfInstantiation(PointOfInstantiation);
+    return;
+  }
+
+  if (MemberSpecializationInfo *MSI = getMemberSpecializationInfo()) {
+    MSI->setTemplateSpecializationKind(TSK);
+    if (TSK != TSK_ExplicitSpecialization && PointOfInstantiation.isValid() &&
+        MSI->getPointOfInstantiation().isInvalid())
+      MSI->setPointOfInstantiation(PointOfInstantiation);
+    return;
+  }
+
+  llvm_unreachable(
+      "Not a variable or static data member template specialization");
+}
+
+void
+VarDecl::setInstantiationOfStaticDataMember(VarDecl *VD,
+                                            TemplateSpecializationKind TSK) {
+  assert(getASTContext().getTemplateOrSpecializationInfo(this).isNull() &&
+         "Previous template or instantiation?");
+  getASTContext().setInstantiatedFromStaticDataMember(this, VD, TSK);
 }
 
 //===----------------------------------------------------------------------===//
diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 13bde4ca860..e99f7ec5b06 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -538,6 +538,7 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
       return IDNS_Namespace;
 
     case FunctionTemplate:
+    case VarTemplate:
       return IDNS_Ordinary;
 
     case ClassTemplate:
@@ -560,6 +561,8 @@ unsigned Decl::getIdentifierNamespaceForKind(Kind DeclKind) {
     case ClassTemplateSpecialization:
     case ClassTemplatePartialSpecialization:
     case ClassScopeFunctionSpecialization:
+    case VarTemplateSpecialization:
+    case VarTemplatePartialSpecialization:
     case ObjCImplementation:
     case ObjCCategory:
     case ObjCCategoryImpl:
diff --git a/clang/lib/AST/DeclTemplate.cpp b/clang/lib/AST/DeclTemplate.cpp
index ac0d54f5011..555800a8bef 100644
--- a/clang/lib/AST/DeclTemplate.cpp
+++ b/clang/lib/AST/DeclTemplate.cpp
@@ -958,3 +958,248 @@ ClassScopeFunctionSpecializationDecl::CreateDeserialized(ASTContext &C,
   return new (Mem) ClassScopeFunctionSpecializationDecl(0, SourceLocation(), 0,
                                              false, TemplateArgumentListInfo());
 }
+
+//===----------------------------------------------------------------------===//
+// VarTemplateDecl Implementation
+//===----------------------------------------------------------------------===//
+
+void VarTemplateDecl::DeallocateCommon(void *Ptr) {
+  static_cast<Common *>(Ptr)->~Common();
+}
+
+VarTemplateDecl *VarTemplateDecl::Create(ASTContext &C, DeclContext *DC,
+                                         SourceLocation L, DeclarationName Name,
+                                         TemplateParameterList *Params,
+                                         NamedDecl *Decl,
+                                         VarTemplateDecl *PrevDecl) {
+  VarTemplateDecl *New = new (C) VarTemplateDecl(DC, L, Name, Params, Decl);
+  New->setPreviousDeclaration(PrevDecl);
+  return New;
+}
+
+VarTemplateDecl *VarTemplateDecl::CreateDeserialized(ASTContext &C,
+                                                     unsigned ID) {
+  void *Mem = AllocateDeserializedDecl(C, ID, sizeof(VarTemplateDecl));
+  return new (Mem) VarTemplateDecl(EmptyShell());
+}
+
+// FIXME: Should this be unified accross class, function and variable
+// templates? Perhaps also moved to RedeclarableTemplateDecl?
+void VarTemplateDecl::LoadLazySpecializations() const {
+  Common *CommonPtr = getCommonPtr();
+  if (CommonPtr->LazySpecializations) {
+    ASTContext &Context = getASTContext();
+    uint32_t *Specs = CommonPtr->LazySpecializations;
+    CommonPtr->LazySpecializations = 0;
+    for (uint32_t I = 0, N = *Specs++; I != N; ++I)
+      (void)Context.getExternalSource()->GetExternalDecl(Specs[I]);
+  }
+}
+
+llvm::FoldingSetVector<VarTemplateSpecializationDecl> &
+VarTemplateDecl::getSpecializations() const {
+  LoadLazySpecializations();
+  return getCommonPtr()->Specializations;
+}
+
+llvm::FoldingSetVector<VarTemplatePartialSpecializationDecl> &
+VarTemplateDecl::getPartialSpecializations() {
+  LoadLazySpecializations();
+  return getCommonPtr()->PartialSpecializations;
+}
+
+RedeclarableTemplateDecl::CommonBase *
+VarTemplateDecl::newCommon(ASTContext &C) const {
+  Common *CommonPtr = new (C) Common;
+  C.AddDeallocation(DeallocateCommon, CommonPtr);
+  return CommonPtr;
+}
+
+VarTemplateSpecializationDecl *
+VarTemplateDecl::findSpecialization(const TemplateArgument *Args,
+                                    unsigned NumArgs, void *&InsertPos) {
+  return findSpecializationImpl(getSpecializations(), Args, NumArgs, InsertPos);
+}
+
+void VarTemplateDecl::AddSpecialization(VarTemplateSpecializationDecl *D,
+                                        void *InsertPos) {
+  if (InsertPos)
+    getSpecializations().InsertNode(D, InsertPos);
+  else {
+    VarTemplateSpecializationDecl *Existing =
+        getSpecializations().GetOrInsertNode(D);
+    (void)Existing;
+    assert(Existing->isCanonicalDecl() && "Non-canonical specialization?");
+  }
+  if (ASTMutationListener *L = getASTMutationListener())
+    L->AddedCXXTemplateSpecialization(this, D);
+}
+
+VarTemplatePartialSpecializationDecl *
+VarTemplateDecl::findPartialSpecialization(const TemplateArgument *Args,
+                                           unsigned NumArgs, void *&InsertPos) {
+  return findSpecializationImpl(getPartialSpecializations(), Args, NumArgs,
+                                InsertPos);
+}
+
+void VarTemplateDecl::AddPartialSpecialization(
+    VarTemplatePartialSpecializationDecl *D, void *InsertPos) {
+  if (InsertPos)
+    getPartialSpecializations().InsertNode(D, InsertPos);
+  else {
+    VarTemplatePartialSpecializationDecl *Existing =
+        getPartialSpecializations().GetOrInsertNode(D);
+    (void)Existing;
+    assert(Existing->isCanonicalDecl() && "Non-canonical specialization?");
+  }
+
+  if (ASTMutationListener *L = getASTMutationListener())
+    L->AddedCXXTemplateSpecialization(this, D);
+}
+
+void VarTemplateDecl::getPartialSpecializations(
+    SmallVectorImpl<VarTemplatePartialSpecializationDecl *> &PS) {
+  llvm::FoldingSetVector<VarTemplatePartialSpecializationDecl> &PartialSpecs =
+      getPartialSpecializations();
+  PS.clear();
+  PS.resize(PartialSpecs.size());
+  for (llvm::FoldingSetVector<VarTemplatePartialSpecializationDecl>::iterator
+           P = PartialSpecs.begin(),
+           PEnd = PartialSpecs.end();
+       P != PEnd; ++P) {
+    assert(!PS[P->getSequenceNumber()]);
+    PS[P->getSequenceNumber()] = P->getMostRecentDecl();
+  }
+}
+
+VarTemplatePartialSpecializationDecl *
+VarTemplateDecl::findPartialSpecInstantiatedFromMember(
+    VarTemplatePartialSpecializationDecl *D) {
+  Decl *DCanon = D->getCanonicalDecl();
+  for (llvm::FoldingSetVector<VarTemplatePartialSpecializationDecl>::iterator
+           P = getPartialSpecializations().begin(),
+           PEnd = getPartialSpecializations().end();
+       P != PEnd; ++P) {
+    if (P->getInstantiatedFromMember()->getCanonicalDecl() == DCanon)
+      return P->getMostRecentDecl();
+  }
+
+  return 0;
+}
+
+//===----------------------------------------------------------------------===//
+// VarTemplateSpecializationDecl Implementation
+//===----------------------------------------------------------------------===//
+VarTemplateSpecializationDecl::VarTemplateSpecializationDecl(
+    ASTContext &Context, Kind DK, DeclContext *DC, SourceLocation StartLoc,
+    SourceLocation IdLoc, VarTemplateDecl *SpecializedTemplate, QualType T,
+    TypeSourceInfo *TInfo, StorageClass S, const TemplateArgument *Args,
+    unsigned NumArgs)
+    : VarDecl(DK, DC, StartLoc, IdLoc, SpecializedTemplate->getIdentifier(), T,
+              TInfo, S),
+      SpecializedTemplate(SpecializedTemplate), ExplicitInfo(0),
+      TemplateArgs(TemplateArgumentList::CreateCopy(Context, Args, NumArgs)),
+      SpecializationKind(TSK_Undeclared) {}
+
+VarTemplateSpecializationDecl::VarTemplateSpecializationDecl(Kind DK)
+    : VarDecl(DK, 0, SourceLocation(), SourceLocation(), 0, QualType(), 0,
+              SC_None),
+      ExplicitInfo(0), SpecializationKind(TSK_Undeclared) {}
+
+VarTemplateSpecializationDecl *VarTemplateSpecializationDecl::Create(
+    ASTContext &Context, DeclContext *DC, SourceLocation StartLoc,
+    SourceLocation IdLoc, VarTemplateDecl *SpecializedTemplate, QualType T,
+    TypeSourceInfo *TInfo, StorageClass S, const TemplateArgument *Args,
+    unsigned NumArgs) {
+  VarTemplateSpecializationDecl *Result = new (Context)
+      VarTemplateSpecializationDecl(Context, VarTemplateSpecialization, DC,
+                                    StartLoc, IdLoc, SpecializedTemplate, T,
+                                    TInfo, S, Args, NumArgs);
+  return Result;
+}
+
+VarTemplateSpecializationDecl *
+VarTemplateSpecializationDecl::CreateDeserialized(ASTContext &C, unsigned ID) {
+  void *Mem =
+      AllocateDeserializedDecl(C, ID, sizeof(VarTemplateSpecializationDecl));
+  VarTemplateSpecializationDecl *Result =
+      new (Mem) VarTemplateSpecializationDecl(VarTemplateSpecialization);
+  return Result;
+}
+
+void VarTemplateSpecializationDecl::getNameForDiagnostic(
+    raw_ostream &OS, const PrintingPolicy &Policy, bool Qualified) const {
+  NamedDecl::getNameForDiagnostic(OS, Policy, Qualified);
+
+  const TemplateArgumentList &TemplateArgs = getTemplateArgs();
+  TemplateSpecializationType::PrintTemplateArgumentList(
+      OS, TemplateArgs.data(), TemplateArgs.size(), Policy);
+}
+
+VarTemplateDecl *VarTemplateSpecializationDecl::getSpecializedTemplate() const {
+  if (SpecializedPartialSpecialization *PartialSpec =
+          SpecializedTemplate.dyn_cast<SpecializedPartialSpecialization *>())
+    return PartialSpec->PartialSpecialization->getSpecializedTemplate();
+  return SpecializedTemplate.get<VarTemplateDecl *>();
+}
+
+void VarTemplateSpecializationDecl::setTemplateArgsInfo(
+    const TemplateArgumentListInfo &ArgsInfo) {
+  unsigned N = ArgsInfo.size();
+  TemplateArgsInfo.setLAngleLoc(ArgsInfo.getLAngleLoc());
+  TemplateArgsInfo.setRAngleLoc(ArgsInfo.getRAngleLoc());
+  for (unsigned I = 0; I != N; ++I)
+    TemplateArgsInfo.addArgument(ArgsInfo[I]);
+}
+
+//===----------------------------------------------------------------------===//
+// VarTemplatePartialSpecializationDecl Implementation
+//===----------------------------------------------------------------------===//
+void VarTemplatePartialSpecializationDecl::anchor() {}
+
+VarTemplatePartialSpecializationDecl::VarTemplatePartialSpecializationDecl(
+    ASTContext &Context, DeclContext *DC, SourceLocation StartLoc,
+    SourceLocation IdLoc, TemplateParameterList *Params,
+    VarTemplateDecl *SpecializedTemplate, QualType T, TypeSourceInfo *TInfo,
+    StorageClass S, const TemplateArgument *Args, unsigned NumArgs,
+    TemplateArgumentLoc *ArgInfos, unsigned NumArgInfos,
+    unsigned SequenceNumber)
+    : VarTemplateSpecializationDecl(Context, VarTemplatePartialSpecialization,
+                                    DC, StartLoc, IdLoc, SpecializedTemplate, T,
+                                    TInfo, S, Args, NumArgs),
+      TemplateParams(Params), ArgsAsWritten(ArgInfos),
+      NumArgsAsWritten(NumArgInfos), SequenceNumber(SequenceNumber),
+      InstantiatedFromMember(0, false) {
+  // TODO: The template parameters should be in DC by now. Verify.
+  // AdoptTemplateParameterList(Params, DC);
+}
+
+VarTemplatePartialSpecializationDecl *
+VarTemplatePartialSpecializationDecl::Create(
+    ASTContext &Context, DeclContext *DC, SourceLocation StartLoc,
+    SourceLocation IdLoc, TemplateParameterList *Params,
+    VarTemplateDecl *SpecializedTemplate, QualType T, TypeSourceInfo *TInfo,
+    StorageClass S, const TemplateArgument *Args, unsigned NumArgs,
+    const TemplateArgumentListInfo &ArgInfos, unsigned SequenceNumber) {
+  unsigned N = ArgInfos.size();
+  TemplateArgumentLoc *ClonedArgs = new (Context) TemplateArgumentLoc[N];
+  for (unsigned I = 0; I != N; ++I)
+    ClonedArgs[I] = ArgInfos[I];
+
+  VarTemplatePartialSpecializationDecl *Result =
+      new (Context) VarTemplatePartialSpecializationDecl(
+          Context, DC, StartLoc, IdLoc, Params, SpecializedTemplate, T, TInfo,
+          S, Args, NumArgs, ClonedArgs, N, SequenceNumber);
+  Result->setSpecializationKind(TSK_ExplicitSpecialization);
+  return Result;
+}
+
+VarTemplatePartialSpecializationDecl *
+VarTemplatePartialSpecializationDecl::CreateDeserialized(ASTContext &C,
+                                                         unsigned ID) {
+  void *Mem = AllocateDeserializedDecl(
+      C, ID, sizeof(VarTemplatePartialSpecializationDecl));
+  VarTemplatePartialSpecializationDecl *Result =
+      new (Mem) VarTemplatePartialSpecializationDecl();
+  return Result;
+}
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 9bce9a0fa3b..ac551d8695b 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -432,7 +432,8 @@ bool ItaniumMangleContext::shouldMangleDeclName(const NamedDecl *D) {
     if (DC->isFunctionOrMethod() && D->hasLinkage())
       while (!DC->isNamespace() && !DC->isTranslationUnit())
         DC = getEffectiveParentContext(DC);
-    if (DC->isTranslationUnit() && D->getFormalLinkage() != InternalLinkage)
+    if (DC->isTranslationUnit() && D->getFormalLinkage() != InternalLinkage &&
+        !isa<VarTemplateSpecializationDecl>(D))
       return false;
   }
 
@@ -554,6 +555,13 @@ isTemplate(const NamedDecl *ND, const TemplateArgumentList *&TemplateArgs) {
     return Spec->getSpecializedTemplate();
   }
 
+  // Check if we have a variable template.
+  if (const VarTemplateSpecializationDecl *Spec =
+          dyn_cast<VarTemplateSpecializationDecl>(ND)) {
+    TemplateArgs = &Spec->getTemplateArgs();
+    return Spec->getSpecializedTemplate();
+  }
+
   return 0;
 }