Improve the representation of template names in the AST. This

representation handles the various ways in which one can name a
template, including unqualified references ("vector"), qualified
references ("std::vector"), and dependent template names
("MetaFun::template apply").

One immediate effect of this change is that the representation of
nested-name-specifiers in type names for class template
specializations (e.g., std::vector<int>) is more accurate. Rather than
representing std::vector<int> as

  std::(vector<int>)

we represent it as

  (std::vector)<int>

which more closely follows the C++ grammar. 

Additionally, templates are no longer represented as declarations
(DeclPtrTy) in Parse-Sema interactions. Instead, I've introduced a new
OpaquePtr type (TemplateTy) that holds the representation of a
TemplateName. This will simplify the handling of dependent
template-names, once we get there.






git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68074 91177308-0d34-0410-b5e6-96231b3b80d8

21 files changed, 576 insertions, 200 deletions

diff --git a/include/clang/AST/ASTContext.h b/include/clang/AST/ASTContext.h
index bb2d80e7d1..b270ddca67 100644
--- a/include/clang/AST/ASTContext.h
+++ b/include/clang/AST/ASTContext.h
@@ -19,6 +19,7 @@
 #include "clang/AST/Builtins.h"
 #include "clang/AST/Decl.h"
 #include "clang/AST/NestedNameSpecifier.h"
+#include "clang/AST/TemplateName.h"
 #include "clang/AST/Type.h"
 #include "clang/Basic/SourceLocation.h"
 #include "llvm/ADT/DenseMap.h"
@@ -71,13 +72,15 @@ class ASTContext {
   llvm::FoldingSet<FunctionNoProtoType> FunctionNoProtoTypes;
   llvm::FoldingSet<FunctionProtoType> FunctionProtoTypes;
   llvm::FoldingSet<TemplateTypeParmType> TemplateTypeParmTypes;
-  llvm::FoldingSet<ClassTemplateSpecializationType> 
-    ClassTemplateSpecializationTypes;
+  llvm::FoldingSet<TemplateSpecializationType> TemplateSpecializationTypes;
   llvm::FoldingSet<QualifiedNameType> QualifiedNameTypes;
   llvm::FoldingSet<TypenameType> TypenameTypes;
   llvm::FoldingSet<ObjCQualifiedInterfaceType> ObjCQualifiedInterfaceTypes;
   llvm::FoldingSet<ObjCQualifiedIdType> ObjCQualifiedIdTypes;
 
+  llvm::FoldingSet<QualifiedTemplateName> QualifiedTemplateNames;
+  llvm::FoldingSet<DependentTemplateName> DependentTemplateNames;
+
   /// \brief The set of nested name specifiers.
   ///
   /// This set is managed by the NestedNameSpecifier class.
@@ -291,10 +294,10 @@ public:
   QualType getTemplateTypeParmType(unsigned Depth, unsigned Index, 
                                    IdentifierInfo *Name = 0);
 
-  QualType getClassTemplateSpecializationType(TemplateDecl *Template,
-                                              const TemplateArgument *Args,
-                                              unsigned NumArgs,
-                                              QualType Canon = QualType());
+  QualType getTemplateSpecializationType(TemplateName T,
+                                         const TemplateArgument *Args,
+                                         unsigned NumArgs,
+                                         QualType Canon = QualType());
 
   QualType getQualifiedNameType(NestedNameSpecifier *NNS,
                                 QualType NamedType);
@@ -407,6 +410,13 @@ public:
 
   QualType getFixedWidthIntType(unsigned Width, bool Signed);
 
+  TemplateName getQualifiedTemplateName(NestedNameSpecifier *NNS, 
+                                        bool TemplateKeyword,
+                                        TemplateDecl *Template);
+
+  TemplateName getDependentTemplateName(NestedNameSpecifier *NNS, 
+                                        const IdentifierInfo *Name);
+
 private:
   QualType getFromTargetType(unsigned Type) const;
 
diff --git a/include/clang/AST/DeclTemplate.h b/include/clang/AST/DeclTemplate.h
index 4638e6bef4..794ab2cf08 100644
--- a/include/clang/AST/DeclTemplate.h
+++ b/include/clang/AST/DeclTemplate.h
@@ -705,7 +705,7 @@ protected:
     llvm::FoldingSet<ClassTemplateSpecializationDecl> Specializations;
   };
 
-  /// \brief Previous declaration of 
+  /// \brief Previous declaration of this class template.
   ClassTemplateDecl *PreviousDeclaration;
 
   /// \brief Pointer to the data that is common to all of the
diff --git a/include/clang/AST/TemplateName.h b/include/clang/AST/TemplateName.h
new file mode 100644
index 0000000000..3107a35841
--- /dev/null
+++ b/include/clang/AST/TemplateName.h
@@ -0,0 +1,246 @@
+//===--- TemplateName.h - C++ Template Name Representation-------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the TemplateName interface and subclasses.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_AST_TEMPLATENAME_H
+#define LLVM_CLANG_AST_TEMPLATENAME_H
+
+#include "llvm/ADT/FoldingSet.h"
+#include "llvm/ADT/PointerUnion.h"
+#include "llvm/Support/PointerLikeTypeTraits.h"
+
+namespace llvm {
+  class raw_ostream;
+}
+
+namespace clang {
+
+class DependentTemplateName;
+class IdentifierInfo;
+class NestedNameSpecifier;
+class QualifiedTemplateName;
+class TemplateDecl;
+
+/// \brief Represents a C++ template name within the type system.
+///
+/// A C++ template name refers to a template within the C++ type
+/// system. In most cases, a template name is simply a reference to a
+/// class template, e.g.
+///
+/// \code
+/// template<typename T> class X { };
+///
+/// X<int> xi;
+/// \endcode
+///
+/// Here, the 'X' in \c X<int> is a template name that refers to the
+/// declaration of the class template X, above. Template names can
+/// also refer to function templates, C++0x template aliases, etc.
+///
+/// Some template names are dependent. For example, consider:
+///
+/// \code
+/// template<typename MetaFun, typename T1, typename T2> struct apply2 {
+///   typedef typename MetaFun::template apply<T1, T2>::type type;
+/// };
+/// \endcode
+///
+/// Here, "apply" is treated as a template name within the typename
+/// specifier in the typedef. "apply" is a nested template, and can
+/// only be understood in the context of
+class TemplateName {
+  typedef llvm::PointerUnion3<TemplateDecl *, QualifiedTemplateName *, 
+                              DependentTemplateName *> StorageType;
+
+  StorageType Storage;
+
+  explicit TemplateName(void *Ptr) {
+    Storage = StorageType::getFromOpaqueValue(Ptr);
+  }
+
+public:
+  TemplateName() : Storage() { }
+  explicit TemplateName(TemplateDecl *Template) : Storage(Template) { }
+  explicit TemplateName(QualifiedTemplateName *Qual) : Storage(Qual) { }
+  explicit TemplateName(DependentTemplateName *Dep) : Storage(Dep) { }
+
+  /// \brief Retrieve the the underlying template declaration that
+  /// this template name refers to, if known.
+  ///
+  /// \returns The template declaration that this template name refers
+  /// to, if any. If the template name does not refer to a specific
+  /// declaration because it is a dependent name, returns NULL.
+  TemplateDecl *getAsTemplateDecl() const;
+
+  /// \brief Retrieve the underlying qualified template name
+  /// structure, if any.
+  QualifiedTemplateName *getAsQualifiedTemplateName() const {
+    return Storage.dyn_cast<QualifiedTemplateName *>();
+  }
+
+  /// \brief Retrieve the underlying dependent template name
+  /// structure, if any.
+  DependentTemplateName *getAsDependentTemplateName() const {
+    return Storage.dyn_cast<DependentTemplateName *>();
+  }
+
+  /// \brief Determines whether this is a dependent template name.
+  bool isDependent() const;
+
+  /// \brief Print the template name.
+  void Print(llvm::raw_ostream &OS) const;
+
+  void Profile(llvm::FoldingSetNodeID &ID) {
+    ID.AddPointer(Storage.getOpaqueValue());
+  }
+
+  /// \brief Retrieve the template name as a void pointer.
+  void *getAsVoidPointer() const { return Storage.getOpaqueValue(); }
+
+  /// \brief Build a template name from a void pointer.
+  static TemplateName getFromVoidPointer(void *Ptr) { 
+    return TemplateName(Ptr); 
+  }
+};
+
+/// \brief Represents a template name that was expressed as a
+/// qualified name.
+///
+/// This kind of template name refers to a template name that was
+/// preceded by a nested name specifier, e.g., \c std::vector. Here,
+/// the nested name specifier is "std::" and the template name is the
+/// declaration for "vector". The QualifiedTemplateName class is only
+/// used to provide "sugar" for template names that were expressed
+/// with a qualified name, and has no semantic meaning. In this
+/// manner, it is to TemplateName what QualifiedNameType is to Type,
+/// providing extra syntactic sugar for downstream clients.
+class QualifiedTemplateName : public llvm::FoldingSetNode {
+  /// \brief The nested name specifier that qualifies the template name.
+  ///
+  /// The bit is used to indicate whether the "template" keyword was
+  /// present before the template name itself. Note that the
+  /// "template" keyword is always redundant in this case (otherwise,
+  /// the template name would be a dependent name and we would express
+  /// this name with DependentTemplateName).
+  llvm::PointerIntPair<NestedNameSpecifier *, 1> Qualifier;
+
+  /// \brief The template declaration that this qualified name refers
+  /// to.
+  TemplateDecl *Template;
+
+  friend class ASTContext;
+
+  QualifiedTemplateName(NestedNameSpecifier *NNS, bool TemplateKeyword,
+                        TemplateDecl *Template)
+    : Qualifier(NNS, TemplateKeyword? 1 : 0), Template(Template) { }
+
+public:
+  /// \brief Return the nested name specifier that qualifies this name.
+  NestedNameSpecifier *getQualifier() const { return Qualifier.getPointer(); }
+
+  /// \brief Whether the template name was prefixed by the "template"
+  /// keyword.
+  bool hasTemplateKeyword() const { return Qualifier.getInt(); }
+
+  /// \brief The template declaration to which this qualified name
+  /// refers.
+  TemplateDecl *getTemplateDecl() const { return Template; }
+
+  void Profile(llvm::FoldingSetNodeID &ID) {
+    Profile(ID, getQualifier(), hasTemplateKeyword(), getTemplateDecl());
+  }
+
+  static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS, 
+                      bool TemplateKeyword, TemplateDecl *Template) {
+    ID.AddPointer(NNS);
+    ID.AddBoolean(TemplateKeyword);
+    ID.AddPointer(Template);
+  }
+};
+
+/// \brief Represents a dependent template name that cannot be
+/// resolved prior to template instantiation.
+///
+/// This kind of template name refers to a dependent template name,
+/// including its nested name specifier. For example,
+/// DependentTemplateName can refer to "MetaFun::template apply",
+/// where "MetaFun::" is the nested name specifier and "apply" is the
+/// template name referenced. The "template" keyword is implied.
+class DependentTemplateName : public llvm::FoldingSetNode {
+  /// \brief The nested name specifier that qualifies the template
+  /// name.
+  NestedNameSpecifier *Qualifier;
+
+  /// \brief The dependent template name.
+  const IdentifierInfo *Name;
+
+  /// \brief The canonical template name to which this dependent
+  /// template name refers.
+  ///
+  /// The canonical template name for a dependent template name is
+  /// another dependent template name whose nested name specifier is
+  /// canonical.
+  TemplateName CanonicalTemplateName;
+
+  friend class ASTContext;
+
+  DependentTemplateName(NestedNameSpecifier *Qualifier, 
+                        const IdentifierInfo *Name)
+    : Qualifier(Qualifier), Name(Name), CanonicalTemplateName(this) { }
+
+  DependentTemplateName(NestedNameSpecifier *Qualifier, 
+                        const IdentifierInfo *Name,
+                        TemplateName Canon)
+    : Qualifier(Qualifier), Name(Name), CanonicalTemplateName(Canon) { }
+
+public:
+  /// \brief Return the nested name specifier that qualifies this name.
+  NestedNameSpecifier *getQualifier() const { return Qualifier; }
+
+  /// \brief Return the name to which this dependent template name
+  /// refers.
+  const IdentifierInfo *getName() const { return Name; }
+
+  void Profile(llvm::FoldingSetNodeID &ID) {
+    Profile(ID, getQualifier(), getName());
+  }
+
+  static void Profile(llvm::FoldingSetNodeID &ID, NestedNameSpecifier *NNS, 
+                      const IdentifierInfo *Name) {
+    ID.AddPointer(NNS);
+    ID.AddPointer(Name);
+  }
+};
+
+}
+
+namespace llvm {
+
+/// \brief The clang::TemplateName class is effectively a pointer.
+template<>
+class PointerLikeTypeTraits<clang::TemplateName> {
+public:
+  static inline void *getAsVoidPointer(clang::TemplateName TN) {
+    return TN.getAsVoidPointer();
+  }
+
+  static inline clang::TemplateName getFromVoidPointer(void *Ptr) {
+    return clang::TemplateName::getFromVoidPointer(Ptr);
+  }
+
+  // No bits are available!
+  enum { NumLowBitsAvailable = 0 };
+};
+
+}
+
+#endif
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index ea1b496cd3..62cd2787ac 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -16,11 +16,13 @@
 
 #include "clang/Basic/Diagnostic.h"
 #include "clang/AST/NestedNameSpecifier.h"
+#include "clang/AST/TemplateName.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/ADT/APSInt.h"
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/PointerIntPair.h"
 #include "llvm/Bitcode/SerializationFwd.h"
+
 using llvm::isa;
 using llvm::cast;
 using llvm::cast_or_null;
@@ -39,7 +41,7 @@ namespace clang {
   class TemplateDecl;
   class TemplateTypeParmDecl;
   class NonTypeTemplateParmDecl;
-  class TemplateTemplateParamDecl;
+  class TemplateTemplateParmDecl;
   class TagDecl;
   class RecordDecl;
   class CXXRecordDecl;
@@ -437,8 +439,8 @@ public:
   const ObjCQualifiedIdType *getAsObjCQualifiedIdType() const;
   const TemplateTypeParmType *getAsTemplateTypeParmType() const;
 
-  const ClassTemplateSpecializationType *
-    getAsClassTemplateSpecializationType() const;
+  const TemplateSpecializationType *
+    getAsTemplateSpecializationType() const;
   
   /// getAsPointerToObjCInterfaceType - If this is a pointer to an ObjC
   /// interface, return the interface type, otherwise return null.
@@ -1494,32 +1496,34 @@ protected:
   friend class Type;
 };
 
-/// \brief Represents the type of a class template specialization as
-/// written in the source code.
+/// \brief Represents the type of a template specialization as written
+/// in the source code.
 ///
-/// Class template specialization types represent the syntactic form
-/// of a template-id that refers to a type, e.g., @c vector<int>. All
-/// class template specialization types are syntactic sugar, whose
-/// canonical type will point to some other type node that represents
-/// the instantiation or class template specialization. For example, a
+/// Template specialization types represent the syntactic form of a
+/// template-id that refers to a type, e.g., @c vector<int>. Some
+/// template specialization types are syntactic sugar, whose canonical
+/// type will point to some other type node that represents the
+/// instantiation or class template specialization. For example, a
 /// class template specialization type of @c vector<int> will refer to
-/// a tag type for the instantiation
+/// a tag type for the instantiation 
 /// @c std::vector<int, std::allocator<int>>.
-class ClassTemplateSpecializationType 
+///
+/// Other template specialization types, for which the template name
+/// is dependent, may be canonical types. These types are always
+/// dependent.
+class TemplateSpecializationType 
   : public Type, public llvm::FoldingSetNode {
 
-  // FIXME: Do we want templates to have a representation in the type
-  // system? It will probably help with dependent templates and
-  // possibly with template-names preceded by a nested-name-specifier.
-  TemplateDecl *Template;
+  /// \brief The name of the template being specialized.
+  TemplateName Template;
 
   /// \brief - The number of template arguments named in this class
   /// template specialization.
   unsigned NumArgs;
 
-  ClassTemplateSpecializationType(TemplateDecl *T, 
-                                  const TemplateArgument *Args,
-                                  unsigned NumArgs, QualType Canon);
+  TemplateSpecializationType(TemplateName T,
+                             const TemplateArgument *Args,
+                             unsigned NumArgs, QualType Canon);
 
   virtual void Destroy(ASTContext& C);
 
@@ -1541,8 +1545,8 @@ public:
   iterator begin() const { return getArgs(); }
   iterator end() const;
 
-  /// \brief Retrieve the template that we are specializing.
-  TemplateDecl *getTemplate() const { return Template; }
+  /// \brief Retrieve the name of the template that we are specializing.
+  TemplateName getTemplateName() const { return Template; }
 
   /// \brief Retrieve the template arguments.
   const TemplateArgument *getArgs() const { 
@@ -1562,13 +1566,13 @@ public:
     Profile(ID, Template, getArgs(), NumArgs);
   }
 
-  static void Profile(llvm::FoldingSetNodeID &ID, TemplateDecl *T,
+  static void Profile(llvm::FoldingSetNodeID &ID, TemplateName T,
                       const TemplateArgument *Args, unsigned NumArgs);
 
   static bool classof(const Type *T) { 
-    return T->getTypeClass() == ClassTemplateSpecialization; 
+    return T->getTypeClass() == TemplateSpecialization; 
   }
-  static bool classof(const ClassTemplateSpecializationType *T) { return true; }
+  static bool classof(const TemplateSpecializationType *T) { return true; }
 
 protected:
   virtual void EmitImpl(llvm::Serializer& S) const;
diff --git a/include/clang/AST/TypeNodes.def b/include/clang/AST/TypeNodes.def
index 42057139f8..e98ff4200f 100644
--- a/include/clang/AST/TypeNodes.def
+++ b/include/clang/AST/TypeNodes.def
@@ -72,7 +72,7 @@ ABSTRACT_TYPE(Tag, Type)
 TYPE(Record, TagType)
 TYPE(Enum, TagType)
 DEPENDENT_TYPE(TemplateTypeParm, Type)
-NON_CANONICAL_TYPE(ClassTemplateSpecialization, Type)
+TYPE(TemplateSpecialization, Type)
 NON_CANONICAL_TYPE(QualifiedName, Type)
 DEPENDENT_TYPE(Typename, Type)
 TYPE(ObjCInterface, Type)
diff --git a/include/clang/Parse/Action.h b/include/clang/Parse/Action.h
index a58fc81c83..f1837faac5 100644
--- a/include/clang/Parse/Action.h
+++ b/include/clang/Parse/Action.h
@@ -72,7 +72,8 @@ public:
   typedef ActionBase::StmtTy StmtTy;
   typedef OpaquePtr<0> DeclPtrTy;
   typedef OpaquePtr<1> DeclGroupPtrTy;
-  typedef void TypeTy;  // FIXME: Change TypeTy to use OpaquePtr<1>.
+  typedef void TypeTy;  // FIXME: Change TypeTy to use OpaquePtr<N>.
+  typedef OpaquePtr<2> TemplateTy;
   typedef void AttrTy;
   typedef void BaseTy;
   typedef void MemInitTy;
@@ -157,7 +158,7 @@ public:
   /// optional CXXScope can be passed to indicate the C++ scope in
   /// which the identifier will be found.
   virtual TemplateNameKind isTemplateName(IdentifierInfo &II, Scope *S,
-                                          DeclPtrTy &TemplateDecl,
+                                          TemplateTy &Template,
                                           const CXXScopeSpec *SS = 0) = 0;
 
   /// ActOnCXXGlobalScopeSpecifier - Return the object that represents the
@@ -1206,8 +1207,8 @@ public:
     return DeclResult();
   }
 
-  /// \brief Form a class template specialization from a template and
-  /// a list of template arguments.
+  /// \brief Form a type from a template and a list of template
+  /// arguments.
   ///
   /// This action merely forms the type for the template-id, possibly
   /// checking well-formedness of the template arguments. It does not
@@ -1219,13 +1220,12 @@ public:
   /// \param IsSpecialization true when we are naming the class
   /// template specialization as part of an explicit class
   /// specialization or class template partial specialization.
-  virtual TypeResult ActOnClassTemplateId(DeclPtrTy Template,
-                                          SourceLocation TemplateLoc,
-                                          SourceLocation LAngleLoc,
-                                          ASTTemplateArgsPtr TemplateArgs,
-                                          SourceLocation *TemplateArgLocs,
-                                          SourceLocation RAngleLoc,
-                                          const CXXScopeSpec *SS) {
+  virtual TypeResult ActOnTemplateIdType(TemplateTy Template,
+                                         SourceLocation TemplateLoc,
+                                         SourceLocation LAngleLoc,
+                                         ASTTemplateArgsPtr TemplateArgs,
+                                         SourceLocation *TemplateArgLocs,
+                                         SourceLocation RAngleLoc) {
     return TypeResult();
   };
 
@@ -1279,7 +1279,7 @@ public:
   ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec, TagKind TK,
                                    SourceLocation KWLoc, 
                                    const CXXScopeSpec &SS,
-                                   DeclPtrTy Template,
+                                   TemplateTy Template,
                                    SourceLocation TemplateNameLoc,
                                    SourceLocation LAngleLoc,
                                    ASTTemplateArgsPtr TemplateArgs,
@@ -1569,7 +1569,7 @@ public:
                                   const CXXScopeSpec *SS);
 
   virtual TemplateNameKind isTemplateName(IdentifierInfo &II, Scope *S,
-                                          DeclPtrTy &TemplateDecl,
+                                          TemplateTy &Template,
                                           const CXXScopeSpec *SS = 0);
 
   /// ActOnDeclarator - If this is a typedef declarator, we modify the
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index ca2d706f23..86bda4551a 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -126,6 +126,7 @@ public:
   typedef Action::MemInitTy MemInitTy;
   typedef Action::CXXScopeTy CXXScopeTy;
   typedef Action::TemplateParamsTy TemplateParamsTy;
+  typedef Action::TemplateTy TemplateTy;
 
   typedef llvm::SmallVector<TemplateParamsTy *, 4> TemplateParameterLists;
 
@@ -1050,7 +1051,7 @@ private:
   typedef llvm::SmallVector<bool, 16> TemplateArgIsTypeList;
   typedef llvm::SmallVector<SourceLocation, 16> TemplateArgLocationList;
 
-  bool ParseTemplateIdAfterTemplateName(DeclPtrTy Template,
+  bool ParseTemplateIdAfterTemplateName(TemplateTy Template,
                                         SourceLocation TemplateNameLoc, 
                                         const CXXScopeSpec *SS,
                                         bool ConsumeLastToken,
@@ -1060,7 +1061,7 @@ private:
                                TemplateArgLocationList &TemplateArgLocations,
                                         SourceLocation &RAngleLoc);
 
-  void AnnotateTemplateIdToken(DeclPtrTy Template, TemplateNameKind TNK,
+  void AnnotateTemplateIdToken(TemplateTy Template, TemplateNameKind TNK,
                                const CXXScopeSpec *SS,
                                SourceLocation TemplateKWLoc = SourceLocation(),
                                bool AllowTypeAnnotation = true);
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index f3cf6b18eb..bb17954727 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -483,6 +483,10 @@ ASTContext::getTypeInfo(const Type *T) {
     Align = Layout.getAlignment();
     break;
   }
+
+  case Type::TemplateSpecialization:
+    assert(false && "Dependent types have no size");
+    break;
   }
   
   assert(Align && (Align & (Align-1)) == 0 && "Alignment must be power of 2");
@@ -1358,30 +1362,31 @@ QualType ASTContext::getTemplateTypeParmType(unsigned Depth, unsigned Index,
 }
 
 QualType 
-ASTContext::getClassTemplateSpecializationType(TemplateDecl *Template,
-                                               const TemplateArgument *Args,
-                                               unsigned NumArgs,
-                                               QualType Canon) {
+ASTContext::getTemplateSpecializationType(TemplateName Template,
+                                          const TemplateArgument *Args,
+                                          unsigned NumArgs,
+                                          QualType Canon) {
+  // FIXME: If Template is dependent, canonicalize it!
+
   if (!Canon.isNull())
     Canon = getCanonicalType(Canon);
 
   llvm::FoldingSetNodeID ID;
-  ClassTemplateSpecializationType::Profile(ID, Template, Args, NumArgs);
+  TemplateSpecializationType::Profile(ID, Template, Args, NumArgs);
 
   void *InsertPos = 0;
-  ClassTemplateSpecializationType *Spec
-    = ClassTemplateSpecializationTypes.FindNodeOrInsertPos(ID, InsertPos);
+  TemplateSpecializationType *Spec
+    = TemplateSpecializationTypes.FindNodeOrInsertPos(ID, InsertPos);
 
   if (Spec)
     return QualType(Spec, 0);
   
-  void *Mem = Allocate((sizeof(ClassTemplateSpecializationType) + 
+  void *Mem = Allocate((sizeof(TemplateSpecializationType) + 
                         sizeof(TemplateArgument) * NumArgs),
                        8);
-  Spec = new (Mem) ClassTemplateSpecializationType(Template, Args, NumArgs, 
-                                                   Canon);
+  Spec = new (Mem) TemplateSpecializationType(Template, Args, NumArgs, Canon);
   Types.push_back(Spec);
-  ClassTemplateSpecializationTypes.InsertNode(Spec, InsertPos);
+  TemplateSpecializationTypes.InsertNode(Spec, InsertPos);
 
   return QualType(Spec, 0);  
 }
@@ -2486,6 +2491,53 @@ void ASTContext::setObjCConstantStringInterface(ObjCInterfaceDecl *Decl) {
   ObjCConstantStringType = getObjCInterfaceType(Decl);
 }
 
+/// \brief Retrieve the template name that represents a qualified
+/// template name such as \c std::vector.
+TemplateName ASTContext::getQualifiedTemplateName(NestedNameSpecifier *NNS, 
+                                                  bool TemplateKeyword,
+                                                  TemplateDecl *Template) {
+  llvm::FoldingSetNodeID ID;
+  QualifiedTemplateName::Profile(ID, NNS, TemplateKeyword, Template);
+
+  void *InsertPos = 0;
+  QualifiedTemplateName *QTN =
+    QualifiedTemplateNames.FindNodeOrInsertPos(ID, InsertPos);
+  if (!QTN) {
+    QTN = new (*this,4) QualifiedTemplateName(NNS, TemplateKeyword, Template);
+    QualifiedTemplateNames.InsertNode(QTN, InsertPos);
+  }
+
+  return TemplateName(QTN);
+}
+
+/// \brief Retrieve the template name that represents a dependent
+/// template name such as \c MetaFun::template apply.
+TemplateName ASTContext::getDependentTemplateName(NestedNameSpecifier *NNS, 
+                                                  const IdentifierInfo *Name) {
+  assert(NNS->isDependent() && "Nested name specifier must be dependent");
+
+  llvm::FoldingSetNodeID ID;
+  DependentTemplateName::Profile(ID, NNS, Name);
+
+  void *InsertPos = 0;
+  DependentTemplateName *QTN =
+    DependentTemplateNames.FindNodeOrInsertPos(ID, InsertPos);
+
+  if (QTN)
+    return TemplateName(QTN);
+
+  NestedNameSpecifier *CanonNNS = getCanonicalNestedNameSpecifier(NNS);
+  if (CanonNNS == NNS) {
+    QTN = new (*this,4) DependentTemplateName(NNS, Name);
+  } else {
+    TemplateName Canon = getDependentTemplateName(CanonNNS, Name);
+    QTN = new (*this,4) DependentTemplateName(NNS, Name, Canon);
+  }
+
+  DependentTemplateNames.InsertNode(QTN, InsertPos);
+  return TemplateName(QTN);
+}
+
 /// getFromTargetType - Given one of the integer types provided by
 /// TargetInfo, produce the corresponding type. The unsigned @p Type
 /// is actually a value of type @c TargetInfo::IntType.
@@ -3033,6 +3085,10 @@ QualType ASTContext::mergeTypes(QualType LHS, QualType RHS) {
     ResultType.setCVRQualifiers(LHSCan.getCVRQualifiers());
     return ResultType;
 #endif
+
+  case Type::TemplateSpecialization:
+    assert(false && "Dependent types have no size");
+    break;
   }
 
   return QualType();
diff --git a/lib/AST/TemplateName.cpp b/lib/AST/TemplateName.cpp
new file mode 100644
index 0000000000..4e54fe4955
--- /dev/null
+++ b/lib/AST/TemplateName.cpp
@@ -0,0 +1,54 @@
+//===--- TemplateName.h - C++ Template Name Representation-------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the TemplateName interface and subclasses.
+//
+//===----------------------------------------------------------------------===//
+#include "clang/AST/TemplateName.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/AST/NestedNameSpecifier.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+
+TemplateDecl *TemplateName::getAsTemplateDecl() const {
+  if (TemplateDecl *Template = Storage.dyn_cast<TemplateDecl *>())
+    return Template;
+  
+  if (QualifiedTemplateName *QTN = getAsQualifiedTemplateName())
+    return QTN->getTemplateDecl();
+
+  return 0;
+}
+
+bool TemplateName::isDependent() const {
+  if (TemplateDecl *Template = getAsTemplateDecl()) {
+    // FIXME: We don't yet have a notion of dependent
+    // declarations. When we do, check that. This hack won't last
+    // long!.
+    return isa<TemplateTemplateParmDecl>(Template);
+  }
+
+  return true;
+}
+
+void TemplateName::Print(llvm::raw_ostream &OS) const {
+  if (TemplateDecl *Template = Storage.dyn_cast<TemplateDecl *>())
+    OS << Template->getIdentifier()->getName();
+  else if (QualifiedTemplateName *QTN = getAsQualifiedTemplateName()) {
+    QTN->getQualifier()->Print(OS);
+    if (QTN->hasTemplateKeyword())
+      OS << "template ";
+    OS << QTN->getTemplateDecl()->getIdentifier()->getName();
+  } else if (DependentTemplateName *DTN = getAsDependentTemplateName()) {
+    DTN->getQualifier()->Print(OS);
+    OS << "template ";
+    OS << DTN->getName()->getName();
+  }
+}
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 0a3e8f91f0..6922dcc6c0 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -93,8 +93,8 @@ QualType Type::getDesugaredType() const {
     return TOE->getUnderlyingExpr()->getType().getDesugaredType();
   if (const TypeOfType *TOT = dyn_cast<TypeOfType>(this))
     return TOT->getUnderlyingType().getDesugaredType();
-  if (const ClassTemplateSpecializationType *Spec 
-        = dyn_cast<ClassTemplateSpecializationType>(this))
+  if (const TemplateSpecializationType *Spec 
+        = dyn_cast<TemplateSpecializationType>(this))
     return Spec->getCanonicalTypeInternal().getDesugaredType();
   if (const QualifiedNameType *QualName  = dyn_cast<QualifiedNameType>(this))
     return QualName->getNamedType().getDesugaredType();
@@ -549,11 +549,11 @@ const TemplateTypeParmType *Type::getAsTemplateTypeParmType() const {
   return dyn_cast<TemplateTypeParmType>(CanonicalType);
 }
 
-const ClassTemplateSpecializationType *
-Type::getAsClassTemplateSpecializationType() const {
+const TemplateSpecializationType *
+Type::getAsTemplateSpecializationType() const {
   // There is no sugar for class template specialization types, so
   // just return the canonical type pointer if it is the right class.
-  return dyn_cast<ClassTemplateSpecializati