Check in LLVM r95781.
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
new file mode 100644
index 0000000..1779bde
--- /dev/null
+++ b/lib/Sema/SemaTemplate.cpp
@@ -0,0 +1,5083 @@
+//===------- SemaTemplate.cpp - Semantic Analysis for C++ Templates -------===/
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//===----------------------------------------------------------------------===/
+//
+//  This file implements semantic analysis for C++ templates.
+//===----------------------------------------------------------------------===/
+
+#include "Sema.h"
+#include "Lookup.h"
+#include "TreeTransform.h"
+#include "clang/AST/ASTContext.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+#include "clang/AST/DeclTemplate.h"
+#include "clang/Parse/DeclSpec.h"
+#include "clang/Parse/Template.h"
+#include "clang/Basic/LangOptions.h"
+#include "clang/Basic/PartialDiagnostic.h"
+#include "llvm/ADT/StringExtras.h"
+using namespace clang;
+
+/// \brief Determine whether the declaration found is acceptable as the name
+/// of a template and, if so, return that template declaration. Otherwise,
+/// returns NULL.
+static NamedDecl *isAcceptableTemplateName(ASTContext &Context, NamedDecl *D) {
+  if (!D)
+    return 0;
+
+  if (isa<TemplateDecl>(D))
+    return D;
+
+  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D)) {
+    // C++ [temp.local]p1:
+    //   Like normal (non-template) classes, class templates have an
+    //   injected-class-name (Clause 9). The injected-class-name
+    //   can be used with or without a template-argument-list. When
+    //   it is used without a template-argument-list, it is
+    //   equivalent to the injected-class-name followed by the
+    //   template-parameters of the class template enclosed in
+    //   <>. When it is used with a template-argument-list, it
+    //   refers to the specified class template specialization,
+    //   which could be the current specialization or another
+    //   specialization.
+    if (Record->isInjectedClassName()) {
+      Record = cast<CXXRecordDecl>(Record->getDeclContext());
+      if (Record->getDescribedClassTemplate())
+        return Record->getDescribedClassTemplate();
+
+      if (ClassTemplateSpecializationDecl *Spec
+            = dyn_cast<ClassTemplateSpecializationDecl>(Record))
+        return Spec->getSpecializedTemplate();
+    }
+
+    return 0;
+  }
+
+  return 0;
+}
+
+static void FilterAcceptableTemplateNames(ASTContext &C, LookupResult &R) {
+  LookupResult::Filter filter = R.makeFilter();
+  while (filter.hasNext()) {
+    NamedDecl *Orig = filter.next();
+    NamedDecl *Repl = isAcceptableTemplateName(C, Orig->getUnderlyingDecl());
+    if (!Repl)
+      filter.erase();
+    else if (Repl != Orig)
+      filter.replace(Repl);
+  }
+  filter.done();
+}
+
+TemplateNameKind Sema::isTemplateName(Scope *S,
+                                      const CXXScopeSpec &SS,
+                                      UnqualifiedId &Name,
+                                      TypeTy *ObjectTypePtr,
+                                      bool EnteringContext,
+                                      TemplateTy &TemplateResult) {
+  assert(getLangOptions().CPlusPlus && "No template names in C!");
+
+  DeclarationName TName;
+  
+  switch (Name.getKind()) {
+  case UnqualifiedId::IK_Identifier:
+    TName = DeclarationName(Name.Identifier);
+    break;
+      
+  case UnqualifiedId::IK_OperatorFunctionId:
+    TName = Context.DeclarationNames.getCXXOperatorName(
+                                              Name.OperatorFunctionId.Operator);
+    break;
+
+  case UnqualifiedId::IK_LiteralOperatorId:
+    TName = Context.DeclarationNames.getCXXLiteralOperatorName(Name.Identifier);
+    break;
+
+  default:
+    return TNK_Non_template;
+  }
+
+  QualType ObjectType = QualType::getFromOpaquePtr(ObjectTypePtr);
+
+  LookupResult R(*this, TName, Name.getSourceRange().getBegin(), 
+                 LookupOrdinaryName);
+  R.suppressDiagnostics();
+  LookupTemplateName(R, S, SS, ObjectType, EnteringContext);
+  if (R.empty())
+    return TNK_Non_template;
+
+  TemplateName Template;
+  TemplateNameKind TemplateKind;
+
+  unsigned ResultCount = R.end() - R.begin();
+  if (ResultCount > 1) {
+    // We assume that we'll preserve the qualifier from a function
+    // template name in other ways.
+    Template = Context.getOverloadedTemplateName(R.begin(), R.end());
+    TemplateKind = TNK_Function_template;
+  } else {
+    TemplateDecl *TD = cast<TemplateDecl>((*R.begin())->getUnderlyingDecl());
+
+    if (SS.isSet() && !SS.isInvalid()) {
+      NestedNameSpecifier *Qualifier
+        = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
+      Template = Context.getQualifiedTemplateName(Qualifier, false, TD);
+    } else {
+      Template = TemplateName(TD);
+    }
+
+    if (isa<FunctionTemplateDecl>(TD))
+      TemplateKind = TNK_Function_template;
+    else {
+      assert(isa<ClassTemplateDecl>(TD) || isa<TemplateTemplateParmDecl>(TD));
+      TemplateKind = TNK_Type_template;
+    }
+  }
+
+  TemplateResult = TemplateTy::make(Template);
+  return TemplateKind;
+}
+
+bool Sema::DiagnoseUnknownTemplateName(const IdentifierInfo &II, 
+                                       SourceLocation IILoc,
+                                       Scope *S,
+                                       const CXXScopeSpec *SS,
+                                       TemplateTy &SuggestedTemplate,
+                                       TemplateNameKind &SuggestedKind) {
+  // We can't recover unless there's a dependent scope specifier preceding the
+  // template name.
+  if (!SS || !SS->isSet() || !isDependentScopeSpecifier(*SS) ||
+      computeDeclContext(*SS))
+    return false;
+  
+  // The code is missing a 'template' keyword prior to the dependent template
+  // name.
+  NestedNameSpecifier *Qualifier = (NestedNameSpecifier*)SS->getScopeRep();
+  Diag(IILoc, diag::err_template_kw_missing)
+    << Qualifier << II.getName()
+    << CodeModificationHint::CreateInsertion(IILoc, "template ");
+  SuggestedTemplate 
+    = TemplateTy::make(Context.getDependentTemplateName(Qualifier, &II));
+  SuggestedKind = TNK_Dependent_template_name;
+  return true;
+}
+
+void Sema::LookupTemplateName(LookupResult &Found,
+                              Scope *S, const CXXScopeSpec &SS,
+                              QualType ObjectType,
+                              bool EnteringContext) {
+  // Determine where to perform name lookup
+  DeclContext *LookupCtx = 0;
+  bool isDependent = false;
+  if (!ObjectType.isNull()) {
+    // This nested-name-specifier occurs in a member access expression, e.g.,
+    // x->B::f, and we are looking into the type of the object.
+    assert(!SS.isSet() && "ObjectType and scope specifier cannot coexist");
+    LookupCtx = computeDeclContext(ObjectType);
+    isDependent = ObjectType->isDependentType();
+    assert((isDependent || !ObjectType->isIncompleteType()) && 
+           "Caller should have completed object type");
+  } else if (SS.isSet()) {
+    // This nested-name-specifier occurs after another nested-name-specifier,
+    // so long into the context associated with the prior nested-name-specifier.
+    LookupCtx = computeDeclContext(SS, EnteringContext);
+    isDependent = isDependentScopeSpecifier(SS);
+    
+    // The declaration context must be complete.
+    if (LookupCtx && RequireCompleteDeclContext(SS))
+      return;
+  }
+
+  bool ObjectTypeSearchedInScope = false;
+  if (LookupCtx) {
+    // Perform "qualified" name lookup into the declaration context we
+    // computed, which is either the type of the base of a member access
+    // expression or the declaration context associated with a prior
+    // nested-name-specifier.
+    LookupQualifiedName(Found, LookupCtx);
+
+    if (!ObjectType.isNull() && Found.empty()) {
+      // C++ [basic.lookup.classref]p1:
+      //   In a class member access expression (5.2.5), if the . or -> token is
+      //   immediately followed by an identifier followed by a <, the
+      //   identifier must be looked up to determine whether the < is the
+      //   beginning of a template argument list (14.2) or a less-than operator.
+      //   The identifier is first looked up in the class of the object
+      //   expression. If the identifier is not found, it is then looked up in
+      //   the context of the entire postfix-expression and shall name a class
+      //   or function template.
+      //
+      // FIXME: When we're instantiating a template, do we actually have to
+      // look in the scope of the template? Seems fishy...
+      if (S) LookupName(Found, S);
+      ObjectTypeSearchedInScope = true;
+    }
+  } else if (isDependent) {
+    // We cannot look into a dependent object type or nested nme
+    // specifier.
+    return;
+  } else {
+    // Perform unqualified name lookup in the current scope.
+    LookupName(Found, S);
+  }
+
+  // FIXME: Cope with ambiguous name-lookup results.
+  assert(!Found.isAmbiguous() &&
+         "Cannot handle template name-lookup ambiguities");
+
+  if (Found.empty() && !isDependent) {
+    // If we did not find any names, attempt to correct any typos.
+    DeclarationName Name = Found.getLookupName();
+    if (CorrectTypo(Found, S, &SS, LookupCtx)) {
+      FilterAcceptableTemplateNames(Context, Found);
+      if (!Found.empty() && isa<TemplateDecl>(*Found.begin())) {
+        if (LookupCtx)
+          Diag(Found.getNameLoc(), diag::err_no_member_template_suggest)
+            << Name << LookupCtx << Found.getLookupName() << SS.getRange()
+            << CodeModificationHint::CreateReplacement(Found.getNameLoc(),
+                                          Found.getLookupName().getAsString());
+        else
+          Diag(Found.getNameLoc(), diag::err_no_template_suggest)
+            << Name << Found.getLookupName()
+            << CodeModificationHint::CreateReplacement(Found.getNameLoc(),
+                                          Found.getLookupName().getAsString());
+        if (TemplateDecl *Template = Found.getAsSingle<TemplateDecl>())
+          Diag(Template->getLocation(), diag::note_previous_decl)
+            << Template->getDeclName();
+      } else
+        Found.clear();
+    } else {
+      Found.clear();
+    }
+  }
+
+  FilterAcceptableTemplateNames(Context, Found);
+  if (Found.empty())
+    return;
+
+  if (S && !ObjectType.isNull() && !ObjectTypeSearchedInScope) {
+    // C++ [basic.lookup.classref]p1:
+    //   [...] If the lookup in the class of the object expression finds a
+    //   template, the name is also looked up in the context of the entire
+    //   postfix-expression and [...]
+    //
+    LookupResult FoundOuter(*this, Found.getLookupName(), Found.getNameLoc(),
+                            LookupOrdinaryName);
+    LookupName(FoundOuter, S);
+    FilterAcceptableTemplateNames(Context, FoundOuter);
+    // FIXME: Handle ambiguities in this lookup better
+
+    if (FoundOuter.empty()) {
+      //   - if the name is not found, the name found in the class of the
+      //     object expression is used, otherwise
+    } else if (!FoundOuter.getAsSingle<ClassTemplateDecl>()) {
+      //   - if the name is found in the context of the entire
+      //     postfix-expression and does not name a class template, the name
+      //     found in the class of the object expression is used, otherwise
+    } else {
+      //   - if the name found is a class template, it must refer to the same
+      //     entity as the one found in the class of the object expression,
+      //     otherwise the program is ill-formed.
+      if (!Found.isSingleResult() ||
+          Found.getFoundDecl()->getCanonicalDecl()
+            != FoundOuter.getFoundDecl()->getCanonicalDecl()) {
+        Diag(Found.getNameLoc(), 
+             diag::err_nested_name_member_ref_lookup_ambiguous)
+          << Found.getLookupName();
+        Diag(Found.getRepresentativeDecl()->getLocation(),
+             diag::note_ambig_member_ref_object_type)
+          << ObjectType;
+        Diag(FoundOuter.getFoundDecl()->getLocation(),
+             diag::note_ambig_member_ref_scope);
+
+        // Recover by taking the template that we found in the object
+        // expression's type.
+      }
+    }
+  }
+}
+
+/// ActOnDependentIdExpression - Handle a dependent id-expression that
+/// was just parsed.  This is only possible with an explicit scope
+/// specifier naming a dependent type.
+Sema::OwningExprResult
+Sema::ActOnDependentIdExpression(const CXXScopeSpec &SS,
+                                 DeclarationName Name,
+                                 SourceLocation NameLoc,
+                                 bool isAddressOfOperand,
+                           const TemplateArgumentListInfo *TemplateArgs) {
+  NestedNameSpecifier *Qualifier
+    = static_cast<NestedNameSpecifier*>(SS.getScopeRep());
+    
+  if (!isAddressOfOperand &&
+      isa<CXXMethodDecl>(CurContext) &&
+      cast<CXXMethodDecl>(CurContext)->isInstance()) {
+    QualType ThisType = cast<CXXMethodDecl>(CurContext)->getThisType(Context);
+    
+    // Since the 'this' expression is synthesized, we don't need to
+    // perform the double-lookup check.
+    NamedDecl *FirstQualifierInScope = 0;
+
+    return Owned(CXXDependentScopeMemberExpr::Create(Context,
+                                                     /*This*/ 0, ThisType,
+                                                     /*IsArrow*/ true,
+                                                     /*Op*/ SourceLocation(),
+                                                     Qualifier, SS.getRange(),
+                                                     FirstQualifierInScope,
+                                                     Name, NameLoc,
+                                                     TemplateArgs));
+  }
+
+  return BuildDependentDeclRefExpr(SS, Name, NameLoc, TemplateArgs);
+}
+
+Sema::OwningExprResult
+Sema::BuildDependentDeclRefExpr(const CXXScopeSpec &SS,
+                                DeclarationName Name,
+                                SourceLocation NameLoc,
+                                const TemplateArgumentListInfo *TemplateArgs) {
+  return Owned(DependentScopeDeclRefExpr::Create(Context,
+               static_cast<NestedNameSpecifier*>(SS.getScopeRep()),
+                                                 SS.getRange(),
+                                                 Name, NameLoc,
+                                                 TemplateArgs));
+}
+
+/// DiagnoseTemplateParameterShadow - Produce a diagnostic complaining
+/// that the template parameter 'PrevDecl' is being shadowed by a new
+/// declaration at location Loc. Returns true to indicate that this is
+/// an error, and false otherwise.
+bool Sema::DiagnoseTemplateParameterShadow(SourceLocation Loc, Decl *PrevDecl) {
+  assert(PrevDecl->isTemplateParameter() && "Not a template parameter");
+
+  // Microsoft Visual C++ permits template parameters to be shadowed.
+  if (getLangOptions().Microsoft)
+    return false;
+
+  // C++ [temp.local]p4:
+  //   A template-parameter shall not be redeclared within its
+  //   scope (including nested scopes).
+  Diag(Loc, diag::err_template_param_shadow)
+    << cast<NamedDecl>(PrevDecl)->getDeclName();
+  Diag(PrevDecl->getLocation(), diag::note_template_param_here);
+  return true;
+}
+
+/// AdjustDeclIfTemplate - If the given decl happens to be a template, reset
+/// the parameter D to reference the templated declaration and return a pointer
+/// to the template declaration. Otherwise, do nothing to D and return null.
+TemplateDecl *Sema::AdjustDeclIfTemplate(DeclPtrTy &D) {
+  if (TemplateDecl *Temp = dyn_cast_or_null<TemplateDecl>(D.getAs<Decl>())) {
+    D = DeclPtrTy::make(Temp->getTemplatedDecl());
+    return Temp;
+  }
+  return 0;
+}
+
+static TemplateArgumentLoc translateTemplateArgument(Sema &SemaRef,
+                                            const ParsedTemplateArgument &Arg) {
+  
+  switch (Arg.getKind()) {
+  case ParsedTemplateArgument::Type: {
+    TypeSourceInfo *DI;
+    QualType T = SemaRef.GetTypeFromParser(Arg.getAsType(), &DI);
+    if (!DI) 
+      DI = SemaRef.Context.getTrivialTypeSourceInfo(T, Arg.getLocation());
+    return TemplateArgumentLoc(TemplateArgument(T), DI);
+  }
+    
+  case ParsedTemplateArgument::NonType: {
+    Expr *E = static_cast<Expr *>(Arg.getAsExpr());
+    return TemplateArgumentLoc(TemplateArgument(E), E);
+  }
+    
+  case ParsedTemplateArgument::Template: {
+    TemplateName Template
+      = TemplateName::getFromVoidPointer(Arg.getAsTemplate().get());
+    return TemplateArgumentLoc(TemplateArgument(Template),
+                               Arg.getScopeSpec().getRange(),
+                               Arg.getLocation());
+  }
+  }
+  
+  llvm_unreachable("Unhandled parsed template argument");
+  return TemplateArgumentLoc();
+}
+                                                     
+/// \brief Translates template arguments as provided by the parser
+/// into template arguments used by semantic analysis.
+void Sema::translateTemplateArguments(const ASTTemplateArgsPtr &TemplateArgsIn,
+                                      TemplateArgumentListInfo &TemplateArgs) {
+ for (unsigned I = 0, Last = TemplateArgsIn.size(); I != Last; ++I)
+   TemplateArgs.addArgument(translateTemplateArgument(*this,
+                                                      TemplateArgsIn[I]));
+}
+                                                     
+/// ActOnTypeParameter - Called when a C++ template type parameter
+/// (e.g., "typename T") has been parsed. Typename specifies whether
+/// the keyword "typename" was used to declare the type parameter
+/// (otherwise, "class" was used), and KeyLoc is the location of the
+/// "class" or "typename" keyword. ParamName is the name of the
+/// parameter (NULL indicates an unnamed template parameter) and
+/// ParamName is the location of the parameter name (if any).
+/// If the type parameter has a default argument, it will be added
+/// later via ActOnTypeParameterDefault.
+Sema::DeclPtrTy Sema::ActOnTypeParameter(Scope *S, bool Typename, bool Ellipsis,
+                                         SourceLocation EllipsisLoc,
+                                         SourceLocation KeyLoc,
+                                         IdentifierInfo *ParamName,
+                                         SourceLocation ParamNameLoc,
+                                         unsigned Depth, unsigned Position) {
+  assert(S->isTemplateParamScope() &&
+         "Template type parameter not in template parameter scope!");
+  bool Invalid = false;
+
+  if (ParamName) {
+    NamedDecl *PrevDecl = LookupSingleName(S, ParamName, LookupTagName);
+    if (PrevDecl && PrevDecl->isTemplateParameter())
+      Invalid = Invalid || DiagnoseTemplateParameterShadow(ParamNameLoc,
+                                                           PrevDecl);
+  }
+
+  SourceLocation Loc = ParamNameLoc;
+  if (!ParamName)
+    Loc = KeyLoc;
+
+  TemplateTypeParmDecl *Param
+    = TemplateTypeParmDecl::Create(Context, Context.getTranslationUnitDecl(),
+                                   Loc, Depth, Position, ParamName, Typename,
+                                   Ellipsis);
+  if (Invalid)
+    Param->setInvalidDecl();
+
+  if (ParamName) {
+    // Add the template parameter into the current scope.
+    S->AddDecl(DeclPtrTy::make(Param));
+    IdResolver.AddDecl(Param);
+  }
+
+  return DeclPtrTy::make(Param);
+}
+
+/// ActOnTypeParameterDefault - Adds a default argument (the type
+/// Default) to the given template type parameter (TypeParam).
+void Sema::ActOnTypeParameterDefault(DeclPtrTy TypeParam,
+                                     SourceLocation EqualLoc,
+                                     SourceLocation DefaultLoc,
+                                     TypeTy *DefaultT) {
+  TemplateTypeParmDecl *Parm
+    = cast<TemplateTypeParmDecl>(TypeParam.getAs<Decl>());
+
+  TypeSourceInfo *DefaultTInfo;
+  GetTypeFromParser(DefaultT, &DefaultTInfo);
+
+  assert(DefaultTInfo && "expected source information for type");
+
+  // C++0x [temp.param]p9:
+  // A default template-argument may be specified for any kind of
+  // template-parameter that is not a template parameter pack.
+  if (Parm->isParameterPack()) {
+    Diag(DefaultLoc, diag::err_template_param_pack_default_arg);
+    return;
+  }
+
+  // C++ [temp.param]p14:
+  //   A template-parameter shall not be used in its own default argument.
+  // FIXME: Implement this check! Needs a recursive walk over the types.
+
+  // Check the template argument itself.
+  if (CheckTemplateArgument(Parm, DefaultTInfo)) {
+    Parm->setInvalidDecl();
+    return;
+  }
+
+  Parm->setDefaultArgument(DefaultTInfo, false);
+}
+
+/// \brief Check that the type of a non-type template parameter is
+/// well-formed.
+///
+/// \returns the (possibly-promoted) parameter type if valid;
+/// otherwise, produces a diagnostic and returns a NULL type.
+QualType
+Sema::CheckNonTypeTemplateParameterType(QualType T, SourceLocation Loc) {
+  // C++ [temp.param]p4:
+  //
+  // A non-type template-parameter shall have one of the following
+  // (optionally cv-qualified) types:
+  //
+  //       -- integral or enumeration type,
+  if (T->isIntegralType() || T->isEnumeralType() ||
+      //   -- pointer to object or pointer to function,
+      (T->isPointerType() &&
+       (T->getAs<PointerType>()->getPointeeType()->isObjectType() ||
+        T->getAs<PointerType>()->getPointeeType()->isFunctionType())) ||
+      //   -- reference to object or reference to function,
+      T->isReferenceType() ||
+      //   -- pointer to member.
+      T->isMemberPointerType() ||
+      // If T is a dependent type, we can't do the check now, so we
+      // assume that it is well-formed.
+      T->isDependentType())
+    return T;
+  // C++ [temp.param]p8:
+  //
+  //   A non-type template-parameter of type "array of T" or
+  //   "function returning T" is adjusted to be of type "pointer to
+  //   T" or "pointer to function returning T", respectively.
+  else if (T->isArrayType())
+    // FIXME: Keep the type prior to promotion?
+    return Context.getArrayDecayedType(T);
+  else if (T->isFunctionType())
+    // FIXME: Keep the type prior to promotion?
+    return Context.getPointerType(T);
+
+  Diag(Loc, diag::err_template_nontype_parm_bad_type)
+    << T;
+
+  return QualType();
+}
+
+/// ActOnNonTypeTemplateParameter - Called when a C++ non-type
+/// template parameter (e.g., "int Size" in "template<int Size>
+/// class Array") has been parsed. S is the current scope and D is
+/// the parsed declarator.
+Sema::DeclPtrTy Sema::ActOnNonTypeTemplateParameter(Scope *S, Declarator &D,
+                                                    unsigned Depth,
+                                                    unsigned Position) {
+  TypeSourceInfo *TInfo = 0;
+  QualType T = GetTypeForDeclarator(D, S, &TInfo);
+
+  assert(S->isTemplateParamScope() &&
+         "Non-type template parameter not in template parameter scope!");
+  bool Invalid = false;
+
+  IdentifierInfo *ParamName = D.getIdentifier();
+  if (ParamName) {
+    NamedDecl *PrevDecl = LookupSingleName(S, ParamName, LookupTagName);
+    if (PrevDecl && PrevDecl->isTemplateParameter())
+      Invalid = Invalid || DiagnoseTemplateParameterShadow(D.getIdentifierLoc(),
+                                                           PrevDecl);
+  }
+
+  T = CheckNonTypeTemplateParameterType(T, D.getIdentifierLoc());
+  if (T.isNull()) {
+    T = Context.IntTy; // Recover with an 'int' type.
+    Invalid = true;
+  }
+
+  NonTypeTemplateParmDecl *Param
+    = NonTypeTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
+                                      D.getIdentifierLoc(),
+                                      Depth, Position, ParamName, T, TInfo);
+  if (Invalid)
+    Param->setInvalidDecl();
+
+  if (D.getIdentifier()) {
+    // Add the template parameter into the current scope.
+    S->AddDecl(DeclPtrTy::make(Param));
+    IdResolver.AddDecl(Param);
+  }
+  return DeclPtrTy::make(Param);
+}
+
+/// \brief Adds a default argument to the given non-type template
+/// parameter.
+void Sema::ActOnNonTypeTemplateParameterDefault(DeclPtrTy TemplateParamD,
+                                                SourceLocation EqualLoc,
+                                                ExprArg DefaultE) {
+  NonTypeTemplateParmDecl *TemplateParm
+    = cast<NonTypeTemplateParmDecl>(TemplateParamD.getAs<Decl>());
+  Expr *Default = static_cast<Expr *>(DefaultE.get());
+
+  // C++ [temp.param]p14:
+  //   A template-parameter shall not be used in its own default argument.
+  // FIXME: Implement this check! Needs a recursive walk over the types.
+
+  // Check the well-formedness of the default template argument.
+  TemplateArgument Converted;
+  if (CheckTemplateArgument(TemplateParm, TemplateParm->getType(), Default,
+                            Converted)) {
+    TemplateParm->setInvalidDecl();
+    return;
+  }
+
+  TemplateParm->setDefaultArgument(DefaultE.takeAs<Expr>());
+}
+
+
+/// ActOnTemplateTemplateParameter - Called when a C++ template template
+/// parameter (e.g. T in template <template <typename> class T> class array)
+/// has been parsed. S is the current scope.
+Sema::DeclPtrTy Sema::ActOnTemplateTemplateParameter(Scope* S,
+                                                     SourceLocation TmpLoc,
+                                                     TemplateParamsTy *Params,
+                                                     IdentifierInfo *Name,
+                                                     SourceLocation NameLoc,
+                                                     unsigned Depth,
+                                                     unsigned Position) {
+  assert(S->isTemplateParamScope() &&
+         "Template template parameter not in template parameter scope!");
+
+  // Construct the parameter object.
+  TemplateTemplateParmDecl *Param =
+    TemplateTemplateParmDecl::Create(Context, Context.getTranslationUnitDecl(),
+                                     TmpLoc, Depth, Position, Name,
+                                     (TemplateParameterList*)Params);
+
+  // Make sure the parameter is valid.
+  // FIXME: Decl object is not currently invalidated anywhere so this doesn't
+  // do anything yet. However, if the template parameter list or (eventual)
+  // default value is ever invalidated, that will propagate here.
+  bool Invalid = false;
+  if (Invalid) {
+    Param->setInvalidDecl();
+  }
+
+  // If the tt-param has a name, then link the identifier into the scope
+  // and lookup mechanisms.
+  if (Name) {
+    S->AddDecl(DeclPtrTy::make(Param));
+    IdResolver.AddDecl(Param);
+  }
+
+  return DeclPtrTy::make(Param);
+}
+
+/// \brief Adds a default argument to the given template template
+/// parameter.
+void Sema::ActOnTemplateTemplateParameterDefault(DeclPtrTy TemplateParamD,
+                                                 SourceLocation EqualLoc,
+                                        const ParsedTemplateArgument &Default) {
+  TemplateTemplateParmDecl *TemplateParm
+    = cast<TemplateTemplateParmDecl>(TemplateParamD.getAs<Decl>());
+  
+  // C++ [temp.param]p14:
+  //   A template-parameter shall not be used in its own default argument.
+  // FIXME: Implement this check! Needs a recursive walk over the types.
+
+  // Check only that we have a template template argument. We don't want to
+  // try to check well-formedness now, because our template template parameter
+  // might have dependent types in its template parameters, which we wouldn't
+  // be able to match now.
+  //
+  // If none of the template template parameter's template arguments mention
+  // other template parameters, we could actually perform more checking here.
+  // However, it isn't worth doing.
+  TemplateArgumentLoc DefaultArg = translateTemplateArgument(*this, Default);
+  if (DefaultArg.getArgument().getAsTemplate().isNull()) {
+    Diag(DefaultArg.getLocation(), diag::err_template_arg_not_class_template)
+      << DefaultArg.getSourceRange();
+    return;
+  }
+  
+  TemplateParm->setDefaultArgument(DefaultArg);
+}
+
+/// ActOnTemplateParameterList - Builds a TemplateParameterList that
+/// contains the template parameters in Params/NumParams.
+Sema::TemplateParamsTy *
+Sema::ActOnTemplateParameterList(unsigned Depth,
+                                 SourceLocation ExportLoc,
+                                 SourceLocation TemplateLoc,
+                                 SourceLocation LAngleLoc,
+                                 DeclPtrTy *Params, unsigned NumParams,
+                                 SourceLocation RAngleLoc) {
+  if (ExportLoc.isValid())
+    Diag(ExportLoc, diag::warn_template_export_unsupported);
+
+  return TemplateParameterList::Create(Context, TemplateLoc, LAngleLoc,
+                                       (NamedDecl**)Params, NumParams, 
+                                       RAngleLoc);
+}
+
+Sema::DeclResult
+Sema::CheckClassTemplate(Scope *S, unsigned TagSpec, TagUseKind TUK,
+                         SourceLocation KWLoc, const CXXScopeSpec &SS,
+                         IdentifierInfo *Name, SourceLocation NameLoc,
+                         AttributeList *Attr,
+                         TemplateParameterList *TemplateParams,
+                         AccessSpecifier AS) {
+  assert(TemplateParams && TemplateParams->size() > 0 &&
+         "No template parameters");
+  assert(TUK != TUK_Reference && "Can only declare or define class templates");
+  bool Invalid = false;
+
+  // Check that we can declare a template here.
+  if (CheckTemplateDeclScope(S, TemplateParams))
+    return true;
+
+  TagDecl::TagKind Kind = TagDecl::getTagKindForTypeSpec(TagSpec);
+  assert(Kind != TagDecl::TK_enum && "can't build template of enumerated type");
+
+  // There is no such thing as an unnamed class template.
+  if (!Name) {
+    Diag(KWLoc, diag::err_template_unnamed_class);
+    return true;
+  }
+
+  // Find any previous declaration with this name.
+  DeclContext *SemanticContext;
+  LookupResult Previous(*this, Name, NameLoc, LookupOrdinaryName,
+                        ForRedeclaration);
+  if (SS.isNotEmpty() && !SS.isInvalid()) {
+    if (RequireCompleteDeclContext(SS))
+      return true;
+
+    SemanticContext = computeDeclContext(SS, true);
+    if (!SemanticContext) {
+      // FIXME: Produce a reasonable diagnostic here
+      return true;
+    }
+
+    LookupQualifiedName(Previous, SemanticContext);
+  } else {
+    SemanticContext = CurContext;
+    LookupName(Previous, S);
+  }
+
+  assert(!Previous.isAmbiguous() && "Ambiguity in class template redecl?");
+  NamedDecl *PrevDecl = 0;
+  if (Previous.begin() != Previous.end())
+    PrevDecl = *Previous.begin();
+
+  // If there is a previous declaration with the same name, check
+  // whether this is a valid redeclaration.
+  ClassTemplateDecl *PrevClassTemplate
+    = dyn_cast_or_null<ClassTemplateDecl>(PrevDecl);
+
+  // We may have found the injected-class-name of a class template,
+  // class template partial specialization, or class template specialization. 
+  // In these cases, grab the template that is being defined or specialized.
+  if (!PrevClassTemplate && PrevDecl && isa<CXXRecordDecl>(PrevDecl) && 
+      cast<CXXRecordDecl>(PrevDecl)->isInjectedClassName()) {
+    PrevDecl = cast<CXXRecordDecl>(PrevDecl->getDeclContext());
+    PrevClassTemplate 
+      = cast<CXXRecordDecl>(PrevDecl)->getDescribedClassTemplate();
+    if (!PrevClassTemplate && isa<ClassTemplateSpecializationDecl>(PrevDecl)) {
+      PrevClassTemplate
+        = cast<ClassTemplateSpecializationDecl>(PrevDecl)
+            ->getSpecializedTemplate();
+    }
+  }
+
+  if (TUK == TUK_Friend) {
+    // C++ [namespace.memdef]p3:
+    //   [...] When looking for a prior declaration of a class or a function 
+    //   declared as a friend, and when the name of the friend class or 
+    //   function is neither a qualified name nor a template-id, scopes outside
+    //   the innermost enclosing namespace scope are not considered.
+    DeclContext *OutermostContext = CurContext;
+    while (!OutermostContext->isFileContext())
+      OutermostContext = OutermostContext->getLookupParent();
+
+    if (PrevDecl &&
+        (OutermostContext->Equals(PrevDecl->getDeclContext()) ||
+         OutermostContext->Encloses(PrevDecl->getDeclContext()))) {
+      SemanticContext = PrevDecl->getDeclContext();
+    } else {
+      // Declarations in outer scopes don't matter. However, the outermost
+      // context we computed is the semantic context for our new 
+      // declaration.
+      PrevDecl = PrevClassTemplate = 0;
+      SemanticContext = OutermostContext;
+    }
+    
+    if (CurContext->isDependentContext()) {
+      // If this is a dependent context, we don't want to link the friend
+      // class template to the template in scope, because that would perform
+      // checking of the template parameter lists that can't be performed
+      // until the outer context is instantiated.
+      PrevDecl = PrevClassTemplate = 0;
+    }
+  } else if (PrevDecl && !isDeclInScope(PrevDecl, SemanticContext, S))
+    PrevDecl = PrevClassTemplate = 0;
+
+  if (PrevClassTemplate) {
+    // Ensure that the template parameter lists are compatible.
+    if (!TemplateParameterListsAreEqual(TemplateParams,
+                                   PrevClassTemplate->getTemplateParameters(),
+                                        /*Complain=*/true,
+                                        TPL_TemplateMatch))
+      return true;
+
+    // C++ [temp.class]p4:
+    //   In a redeclaration, partial specialization, explicit
+    //   specialization or explicit instantiation of a class template,
+    //   the class-key shall agree in kind with the original class
+    //   template declaration (7.1.5.3).
+    RecordDecl *PrevRecordDecl = PrevClassTemplate->getTemplatedDecl();
+    if (!isAcceptableTagRedeclaration(PrevRecordDecl, Kind, KWLoc, *Name)) {
+      Diag(KWLoc, diag::err_use_with_wrong_tag)
+        << Name
+        << CodeModificationHint::CreateReplacement(KWLoc,
+                            PrevRecordDecl->getKindName());
+      Diag(PrevRecordDecl->getLocation(), diag::note_previous_use);
+      Kind = PrevRecordDecl->getTagKind();
+    }
+
+    // Check for redefinition of this class template.
+    if (TUK == TUK_Definition) {
+      if (TagDecl *Def = PrevRecordDecl->getDefinition(Context)) {
+        Diag(NameLoc, diag::err_redefinition) << Name;
+        Diag(Def->getLocation(), diag::note_previous_definition);
+        // FIXME: Would it make sense to try to "forget" the previous
+        // definition, as part of error recovery?
+        return true;
+      }
+    }
+  } else if (PrevDecl && PrevDecl->isTemplateParameter()) {
+    // Maybe we will complain about the shadowed template parameter.
+    DiagnoseTemplateParameterShadow(NameLoc, PrevDecl);
+    // Just pretend that we didn't see the previous declaration.
+    PrevDecl = 0;
+  } else if (PrevDecl) {
+    // C++ [temp]p5:
+    //   A class template shall not have the same name as any other
+    //   template, class, function, object, enumeration, enumerator,
+    //   namespace, or type in the same scope (3.3), except as specified
+    //   in (14.5.4).
+    Diag(NameLoc, diag::err_redefinition_different_kind) << Name;
+    Diag(PrevDecl->getLocation(), diag::note_previous_definition);
+    return true;
+  }
+
+  // Check the template parameter list of this declaration, possibly
+  // merging in the template parameter list from the previous class
+  // template declaration.
+  if (CheckTemplateParameterList(TemplateParams,
+            PrevClassTemplate? PrevClassTemplate->getTemplateParameters() : 0,
+                                 TPC_ClassTemplate))
+    Invalid = true;
+
+  // FIXME: If we had a scope specifier, we better have a previous template
+  // declaration!
+
+  CXXRecordDecl *NewClass =
+    CXXRecordDecl::Create(Context, Kind, SemanticContext, NameLoc, Name, KWLoc,
+                          PrevClassTemplate?
+                            PrevClassTemplate->getTemplatedDecl() : 0,
+                          /*DelayTypeCreation=*/true);
+
+  ClassTemplateDecl *NewTemplate
+    = ClassTemplateDecl::Create(Context, SemanticContext, NameLoc,
+                                DeclarationName(Name), TemplateParams,
+                                NewClass, PrevClassTemplate);
+  NewClass->setDescribedClassTemplate(NewTemplate);
+
+  // Build the type for the class template declaration now.
+  QualType T =
+    Context.getTypeDeclType(NewClass,
+                            PrevClassTemplate?
+                              PrevClassTemplate->getTemplatedDecl() : 0);
+  assert(T->isDependentType() && "Class template type is not dependent?");
+  (void)T;
+
+  // If we are providing an explicit specialization of a member that is a 
+  // class template, make a note of that.
+  if (PrevClassTemplate && 
+      PrevClassTemplate->getInstantiatedFromMemberTemplate())
+    PrevClassTemplate->setMemberSpecialization();
+  
+  // Set the access specifier.
+  if (!Invalid && TUK != TUK_Friend)
+    SetMemberAccessSpecifier(NewTemplate, PrevClassTemplate, AS);
+
+  // Set the lexical context of these templates
+  NewClass->setLexicalDeclContext(CurContext);
+  NewTemplate->setLexicalDeclContext(CurContext);
+
+  if (TUK == TUK_Definition)
+    NewClass->startDefinition();
+
+  if (Attr)
+    ProcessDeclAttributeList(S, NewClass, Attr);
+
+  if (TUK != TUK_Friend)
+    PushOnScopeChains(NewTemplate, S);
+  else {
+    if (PrevClassTemplate && PrevClassTemplate->getAccess() != AS_none) {
+      NewTemplate->setAccess(PrevClassTemplate->getAccess());
+      NewClass->setAccess(PrevClassTemplate->getAccess());
+    }
+
+    NewTemplate->setObjectOfFriendDecl(/* PreviouslyDeclared = */
+                                       PrevClassTemplate != NULL);
+    
+    // Friend templates are visible in fairly strange ways.
+    if (!CurContext->isDependentContext()) {
+      DeclContext *DC = SemanticContext->getLookupContext();
+      DC->makeDeclVisibleInContext(NewTemplate, /* Recoverable = */ false);
+      if (Scope *EnclosingScope = getScopeForDeclContext(S, DC))
+        PushOnScopeChains(NewTemplate, EnclosingScope,
+                          /* AddToContext = */ false);      
+    }
+    
+    FriendDecl *Friend = FriendDecl::Create(Context, CurContext,
+                                            NewClass->getLocation(),
+                                            NewTemplate,
+                                    /*FIXME:*/NewClass->getLocation());
+    Friend->setAccess(AS_public);
+    CurContext->addDecl(Friend);
+  }
+
+  if (Invalid) {
+    NewTemplate->setInvalidDecl();
+    NewClass->setInvalidDecl();
+  }
+  return DeclPtrTy::make(NewTemplate);
+}
+
+/// \brief Diagnose the presence of a default template argument on a
+/// template parameter, which is ill-formed in certain contexts.
+///
+/// \returns true if the default template argument should be dropped.
+static bool DiagnoseDefaultTemplateArgument(Sema &S, 
+                                            Sema::TemplateParamListContext TPC,
+                                            SourceLocation ParamLoc,
+                                            SourceRange DefArgRange) {
+  switch (TPC) {
+  case Sema::TPC_ClassTemplate:
+    return false;
+
+  case Sema::TPC_FunctionTemplate:
+    // C++ [temp.param]p9: 
+    //   A default template-argument shall not be specified in a
+    //   function template declaration or a function template
+    //   definition [...]
+    // (This sentence is not in C++0x, per DR226).
+    if (!S.getLangOptions().CPlusPlus0x)
+      S.Diag(ParamLoc, 
+             diag::err_template_parameter_default_in_function_template)
+        << DefArgRange;
+    return false;
+
+  case Sema::TPC_ClassTemplateMember:
+    // C++0x [temp.param]p9:
+    //   A default template-argument shall not be specified in the
+    //   template-parameter-lists of the definition of a member of a
+    //   class template that appears outside of the member's class.
+    S.Diag(ParamLoc, diag::err_template_parameter_default_template_member)
+      << DefArgRange;
+    return true;
+
+  case Sema::TPC_FriendFunctionTemplate:
+    // C++ [temp.param]p9:
+    //   A default template-argument shall not be specified in a
+    //   friend template declaration.
+    S.Diag(ParamLoc, diag::err_template_parameter_default_friend_template)
+      << DefArgRange;
+    return true;
+
+    // FIXME: C++0x [temp.param]p9 allows default template-arguments
+    // for friend function templates if there is only a single
+    // declaration (and it is a definition). Strange!
+  }
+
+  return false;
+}
+
+/// \brief Checks the validity of a template parameter list, possibly
+/// considering the template parameter list from a previous
+/// declaration.
+///
+/// If an "old" template parameter list is provided, it must be
+/// equivalent (per TemplateParameterListsAreEqual) to the "new"
+/// template parameter list.
+///
+/// \param NewParams Template parameter list for a new template
+/// declaration. This template parameter list will be updated with any
+/// default arguments that are carried through from the previous
+/// template parameter list.
+///
+/// \param OldParams If provided, template parameter list from a
+/// previous declaration of the same template. Default template
+/// arguments will be merged from the old template parameter list to
+/// the new template parameter list.
+///
+/// \param TPC Describes the context in which we are checking the given
+/// template parameter list.
+///
+/// \returns true if an error occurred, false otherwise.
+bool Sema::CheckTemplateParameterList(TemplateParameterList *NewParams,
+                                      TemplateParameterList *OldParams,
+                                      TemplateParamListContext TPC) {
+  bool Invalid = false;
+
+  // C++ [temp.param]p10:
+  //   The set of default template-arguments available for use with a
+  //   template declaration or definition is obtained by merging the
+  //   default arguments from the definition (if in scope) and all
+  //   declarations in scope in the same way default function
+  //   arguments are (8.3.6).
+  bool SawDefaultArgument = false;
+  SourceLocation PreviousDefaultArgLoc;
+
+  bool SawParameterPack = false;
+  SourceLocation ParameterPackLoc;
+
+  // Dummy initialization to avoid warnings.
+  TemplateParameterList::iterator OldParam = NewParams->end();
+  if (OldParams)
+    OldParam = OldParams->begin();
+
+  for (TemplateParameterList::iterator NewParam = NewParams->begin(),
+                                    NewParamEnd = NewParams->end();
+       NewParam != NewParamEnd; ++NewParam) {
+    // Variables used to diagnose redundant default arguments
+    bool RedundantDefaultArg = false;
+    SourceLocation OldDefaultLoc;
+    SourceLocation NewDefaultLoc;
+
+    // Variables used to diagnose missing default arguments
+    bool MissingDefaultArg = false;
+
+    // C++0x [temp.param]p11:
+    // If a template parameter of a class template is a template parameter pack,
+    // it must be the last template parameter.
+    if (SawParameterPack) {
+      Diag(ParameterPackLoc,
+           diag::err_template_param_pack_must_be_last_template_parameter);
+      Invalid = true;
+    }
+
+    if (TemplateTypeParmDecl *NewTypeParm
+          = dyn_cast<TemplateTypeParmDecl>(*NewParam)) {
+      // Check the presence of a default argument here.
+      if (NewTypeParm->hasDefaultArgument() && 
+          DiagnoseDefaultTemplateArgument(*this, TPC, 
+                                          NewTypeParm->getLocation(), 
+               NewTypeParm->getDefaultArgumentInfo()->getTypeLoc()
+                                                       .getFullSourceRange()))
+        NewTypeParm->removeDefaultArgument();
+
+      // Merge default arguments for template type parameters.
+      TemplateTypeParmDecl *OldTypeParm
+          = OldParams? cast<TemplateTypeParmDecl>(*OldParam) : 0;
+
+      if (NewTypeParm->isParameterPack()) {
+        assert(!NewTypeParm->hasDefaultArgument() &&
+               "Parameter packs can't have a default argument!");
+        SawParameterPack = true;
+        ParameterPackLoc = NewTypeParm->getLocation();
+      } else if (OldTypeParm && OldTypeParm->hasDefaultArgument() &&
+                 NewTypeParm->hasDefaultArgument()) {
+        OldDefaultLoc = OldTypeParm->getDefaultArgumentLoc();
+        NewDefaultLoc = NewTypeParm->getDefaultArgumentLoc();
+        SawDefaultArgument = true;
+        RedundantDefaultArg = true;
+        PreviousDefaultArgLoc = NewDefaultLoc;
+      } else if (OldTypeParm && OldTypeParm->hasDefaultArgument()) {
+        // Merge the default argument from the old declaration to the
+        // new declaration.
+        SawDefaultArgument = true;
+        NewTypeParm->setDefaultArgument(OldTypeParm->getDefaultArgumentInfo(),
+                                        true);
+        PreviousDefaultArgLoc = OldTypeParm->getDefaultArgumentLoc();
+      } else if (NewTypeParm->hasDefaultArgument()) {
+        SawDefaultArgument = true;
+        PreviousDefaultArgLoc = NewTypeParm->getDefaultArgumentLoc();
+      } else if (SawDefaultArgument)
+        MissingDefaultArg = true;
+    } else if (NonTypeTemplateParmDecl *NewNonTypeParm
+               = dyn_cast<NonTypeTemplateParmDecl>(*NewParam)) {
+      // Check the presence of a default argument here.
+      if (NewNonTypeParm->hasDefaultArgument() && 
+          DiagnoseDefaultTemplateArgument(*this, TPC, 
+                                          NewNonTypeParm->getLocation(), 
+                    NewNonTypeParm->getDefaultArgument()->getSourceRange())) {
+        NewNonTypeParm->getDefaultArgument()->Destroy(Context);
+        NewNonTypeParm->setDefaultArgument(0);
+      }
+
+      // Merge default arguments for non-type template parameters
+      NonTypeTemplateParmDecl *OldNonTypeParm
+        = OldParams? cast<NonTypeTemplateParmDecl>(*OldParam) : 0;
+      if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument() &&
+          NewNonTypeParm->hasDefaultArgument()) {
+        OldDefaultLoc = OldNonTypeParm->getDefaultArgumentLoc();
+        NewDefaultLoc = NewNonTypeParm->getDefaultArgumentLoc();
+        SawDefaultArgument = true;
+        RedundantDefaultArg = true;
+        PreviousDefaultArgLoc = NewDefaultLoc;
+      } else if (OldNonTypeParm && OldNonTypeParm->hasDefaultArgument()) {
+        // Merge the default argument from the old declaration to the
+        // new declaration.
+        SawDefaultArgument = true;
+        // FIXME: We need to create a new kind of "default argument"
+        // expression that points to a previous template template
+        // parameter.
+        NewNonTypeParm->setDefaultArgument(
+                                        OldNonTypeParm->getDefaultArgument());
+        PreviousDefaultArgLoc = OldNonTypeParm->getDefaultArgumentLoc();
+      } else if (NewNonTypeParm->hasDefaultArgument()) {
+        SawDefaultArgument = true;
+        PreviousDefaultArgLoc = NewNonTypeParm->getDefaultArgumentLoc();
+      } else if (SawDefaultArgument)
+        MissingDefaultArg = true;
+    } else {
+      // Check the presence of a default argument here.
+      TemplateTemplateParmDecl *NewTemplateParm
+        = cast<TemplateTemplateParmDecl>(*NewParam);
+      if (NewTemplateParm->hasDefaultArgument() && 
+          DiagnoseDefaultTemplateArgument(*this, TPC, 
+                                          NewTemplateParm->getLocation(), 
+                     NewTemplateParm->getDefaultArgument().getSourceRange()))
+        NewTemplateParm->setDefaultArgument(TemplateArgumentLoc());
+
+      // Merge default arguments for template template parameters
+      TemplateTemplateParmDecl *OldTemplateParm
+        = OldParams? cast<TemplateTemplateParmDecl>(*OldParam) : 0;
+      if (OldTemplateParm && OldTemplateParm->hasDefaultArgument() &&
+          NewTemplateParm->hasDefaultArgument()) {
+        OldDefaultLoc = OldTemplateParm->getDefaultArgument().getLocation();
+        NewDefaultLoc = NewTemplateParm->getDefaultArgument().getLocation();
+        SawDefaultArgument = true;
+        RedundantDefaultArg = true;
+        PreviousDefaultArgLoc = NewDefaultLoc;
+      } else if (OldTemplateParm && OldTemplateParm->hasDefaultArgument()) {
+        // Merge the default argument from the old declaration to the
+        // new declaration.
+        SawDefaultArgument = true;
+        // FIXME: We need to create a new kind of "default argument" expression
+        // that points to a previous template template parameter.
+        NewTemplateParm->setDefaultArgument(
+                                        OldTemplateParm->getDefaultArgument());
+        PreviousDefaultArgLoc
+          = OldTemplateParm->getDefaultArgument().getLocation();
+      } else if (NewTemplateParm->hasDefaultArgument()) {
+        SawDefaultArgument = true;
+        PreviousDefaultArgLoc
+          = NewTemplateParm->getDefaultArgument().getLocation();
+      } else if (SawDefaultArgument)
+        MissingDefaultArg = true;
+    }
+
+    if (RedundantDefaultArg) {
+      // C++ [temp.param]p12:
+      //   A template-parameter shall not be given default arguments
+      //   by two different declarations in the same scope.
+      Diag(NewDefaultLoc, diag::err_template_param_default_arg_redefinition);
+      Diag(OldDefaultLoc, diag::note_template_param_prev_default_arg);
+      Invalid = true;
+    } else if (MissingDefaultArg) {
+      // C++ [temp.param]p11:
+      //   If a template-parameter has a default template-argument,
+      //   all subsequent template-parameters shall have a default
+      //   template-argument supplied.
+      Diag((*NewParam)->getLocation(),
+           diag::err_template_param_default_arg_missing);
+      Diag(PreviousDefaultArgLoc, diag::note_template_param_prev_default_arg);
+      Invalid = true;
+    }
+
+    // If we have an old template parameter list that we're merging
+    // in, move on to the next parameter.
+    if (OldParams)
+      ++OldParam;
+  }
+
+  return Invalid;
+}
+
+/// \brief Match the given template parameter lists to the given scope
+/// specifier, returning the template parameter list that applies to the
+/// name.
+///
+/// \param DeclStartLoc the start of the declaration that has a scope
+/// specifier or a template parameter list.
+///
+/// \param SS the scope specifier that will be matched to the given template
+/// parameter lists. This scope specifier precedes a qualified name that is
+/// being declared.
+///
+/// \param ParamLists the template parameter lists, from the outermost to the
+/// innermost template parameter lists.
+///
+/// \param NumParamLists the number of template parameter lists in ParamLists.
+///
+/// \param IsExplicitSpecialization will be set true if the entity being
+/// declared is an explicit specialization, false otherwise.
+///
+/// \returns the template parameter list, if any, that corresponds to the
+/// name that is preceded by the scope specifier @p SS. This template
+/// parameter list may be have template parameters (if we're declaring a
+/// template) or may have no template parameters (if we're declaring a
+/// template specialization), or may be NULL (if we were's declaring isn't
+/// itself a template).
+TemplateParameterList *
+Sema::MatchTemplateParametersToScopeSpecifier(SourceLocation DeclStartLoc,
+                                              const CXXScopeSpec &SS,
+                                          TemplateParameterList **ParamLists,
+                                              unsigned NumParamLists,
+                                              bool &IsExplicitSpecialization) {
+  IsExplicitSpecialization = false;
+  
+  // Find the template-ids that occur within the nested-name-specifier. These
+  // template-ids will match up with the template parameter lists.
+  llvm::SmallVector<const TemplateSpecializationType *, 4>
+    TemplateIdsInSpecifier;
+  llvm::SmallVector<ClassTemplateSpecializationDecl *, 4>
+    ExplicitSpecializationsInSpecifier;
+  for (NestedNameSpecifier *NNS = (NestedNameSpecifier *)SS.getScopeRep();
+       NNS; NNS = NNS->getPrefix()) {
+    const Type *T = NNS->getAsType();
+    if (!T) break;
+
+    // C++0x [temp.expl.spec]p17:
+    //   A member or a member template may be nested within many
+    //   enclosing class templates. In an explicit specialization for
+    //   such a member, the member declaration shall be preceded by a
+    //   template<> for each enclosing class template that is
+    //   explicitly specialized.
+    // We interpret this as forbidding typedefs of template
+    // specializations in the scope specifiers of out-of-line decls.
+    if (const TypedefType *TT = dyn_cast<TypedefType>(T)) {
+      const Type *UnderlyingT = TT->LookThroughTypedefs().getTypePtr();
+      if (isa<TemplateSpecializationType>(UnderlyingT))
+        // FIXME: better source location information.
+        Diag(DeclStartLoc, diag::err_typedef_in_def_scope) << QualType(T,0);
+      T = UnderlyingT;
+    }
+
+    if (const TemplateSpecializationType *SpecType
+          = dyn_cast<TemplateSpecializationType>(T)) {
+      TemplateDecl *Template = SpecType->getTemplateName().getAsTemplateDecl();
+      if (!Template)
+        continue; // FIXME: should this be an error? probably...
+
+      if (const RecordType *Record = SpecType->getAs<RecordType>()) {
+        ClassTemplateSpecializationDecl *SpecDecl
+          = cast<ClassTemplateSpecializationDecl>(Record->getDecl());
+        // If the nested name specifier refers to an explicit specialization,
+        // we don't need a template<> header.
+        if (SpecDecl->getSpecializationKind() == TSK_ExplicitSpecialization) {
+          ExplicitSpecializationsInSpecifier.push_back(SpecDecl);
+          continue;
+        }
+      }
+
+      TemplateIdsInSpecifier.push_back(SpecType);
+    }
+  }
+
+  // Reverse the list of template-ids in the scope specifier, so that we can
+  // more easily match up the template-ids and the template parameter lists.
+  std::reverse(TemplateIdsInSpecifier.begin(), TemplateIdsInSpecifier.end());
+
+  SourceLocation FirstTemplateLoc = DeclStartLoc;
+  if (NumParamLists)
+    FirstTemplateLoc = ParamLists[0]->getTemplateLoc();
+
+  // Match the template-ids found in the specifier to the template parameter
+  // lists.
+  unsigned Idx = 0;
+  for (unsigned NumTemplateIds = TemplateIdsInSpecifier.size();
+       Idx != NumTemplateIds; ++Idx) {
+    QualType TemplateId = QualType(TemplateIdsInSpecifier[Idx], 0);
+    bool DependentTemplateId = TemplateId->isDependentType();
+    if (Idx >= NumParamLists) {
+      // We have a template-id without a corresponding template parameter
+      // list.
+      if (DependentTemplateId) {
+        // FIXME: the location information here isn't great.
+        Diag(SS.getRange().getBegin(),
+             diag::err_template_spec_needs_template_parameters)
+          << TemplateId
+          << SS.getRange();
+      } else {
+        Diag(SS.getRange().getBegin(), diag::err_template_spec_needs_header)
+          << SS.getRange()
+          << CodeModificationHint::CreateInsertion(FirstTemplateLoc,
+                                                   "template<> ");
+        IsExplicitSpecialization = true;
+      }
+      return 0;
+    }
+
+    // Check the template parameter list against its corresponding template-id.
+    if (DependentTemplateId) {
+      TemplateDecl *Template
+        = TemplateIdsInSpecifier[Idx]->getTemplateName().getAsTemplateDecl();
+
+      if (ClassTemplateDecl *ClassTemplate
+            = dyn_cast<ClassTemplateDecl>(Template)) {
+        TemplateParameterList *ExpectedTemplateParams = 0;
+        // Is this template-id naming the primary template?
+        if (Context.hasSameType(TemplateId,
+                             ClassTemplate->getInjectedClassNameType(Context)))
+          ExpectedTemplateParams = ClassTemplate->getTemplateParameters();
+        // ... or a partial specialization?
+        else if (ClassTemplatePartialSpecializationDecl *PartialSpec
+                   = ClassTemplate->findPartialSpecialization(TemplateId))
+          ExpectedTemplateParams = PartialSpec->getTemplateParameters();
+
+        if (ExpectedTemplateParams)
+          TemplateParameterListsAreEqual(ParamLists[Idx],
+                                         ExpectedTemplateParams,
+                                         true, TPL_TemplateMatch);
+      }
+
+      CheckTemplateParameterList(ParamLists[Idx], 0, TPC_ClassTemplateMember);
+    } else if (ParamLists[Idx]->size() > 0)
+      Diag(ParamLists[Idx]->getTemplateLoc(),
+           diag::err_template_param_list_matches_nontemplate)
+        << TemplateId
+        << ParamLists[Idx]->getSourceRange();
+    else
+      IsExplicitSpecialization = true;
+  }
+
+  // If there were at least as many template-ids as there were template
+  // parameter lists, then there are no template parameter lists remaining for
+  // the declaration itself.
+  if (Idx >= NumParamLists)
+    return 0;
+
+  // If there were too many template parameter lists, complain about that now.
+  if (Idx != NumParamLists - 1) {
+    while (Idx < NumParamLists - 1) {
+      bool isExplicitSpecHeader = ParamLists[Idx]->size() == 0;
+      Diag(ParamLists[Idx]->getTemplateLoc(),
+           isExplicitSpecHeader? diag::warn_template_spec_extra_headers
+                               : diag::err_template_spec_extra_headers)
+        << SourceRange(ParamLists[Idx]->getTemplateLoc(),
+                       ParamLists[Idx]->getRAngleLoc());
+
+      if (isExplicitSpecHeader && !ExplicitSpecializationsInSpecifier.empty()) {
+        Diag(ExplicitSpecializationsInSpecifier.back()->getLocation(),
+             diag::note_explicit_template_spec_does_not_need_header)
+          << ExplicitSpecializationsInSpecifier.back();
+        ExplicitSpecializationsInSpecifier.pop_back();
+      }
+        
+      ++Idx;
+    }
+  }
+
+  // Return the last template parameter list, which corresponds to the
+  // entity being declared.
+  return ParamLists[NumParamLists - 1];
+}
+
+QualType Sema::CheckTemplateIdType(TemplateName Name,
+                                   SourceLocation TemplateLoc,
+                              const TemplateArgumentListInfo &TemplateArgs) {
+  TemplateDecl *Template = Name.getAsTemplateDecl();
+  if (!Template) {
+    // The template name does not resolve to a template, so we just
+    // build a dependent template-id type.
+    return Context.getTemplateSpecializationType(Name, TemplateArgs);
+  }
+
+  // Check that the template argument list is well-formed for this
+  // template.
+  TemplateArgumentListBuilder Converted(Template->getTemplateParameters(),
+                                        TemplateArgs.size());
+  if (CheckTemplateArgumentList(Template, TemplateLoc, TemplateArgs,
+                                false, Converted))
+    return QualType();
+
+  assert((Converted.structuredSize() ==
+            Template->getTemplateParameters()->size()) &&
+         "Converted template argument list is too short!");
+
+  QualType CanonType;
+
+  if (Name.isDependent() ||
+      TemplateSpecializationType::anyDependentTemplateArguments(
+                                                      TemplateArgs)) {
+    // This class template specialization is a dependent
+    // type. Therefore, its canonical type is another class template
+    // specialization type that contains all of the converted
+    // arguments in canonical form. This ensures that, e.g., A<T> and
+    // A<T, T> have identical types when A is declared as:
+    //
+    //   template<typename T, typename U = T> struct A;
+    TemplateName CanonName = Context.getCanonicalTemplateName(Name);
+    CanonType = Context.getTemplateSpecializationType(CanonName,
+                                                   Converted.getFlatArguments(),
+                                                   Converted.flatSize());
+
+    // FIXME: CanonType is not actually the canonical type, and unfortunately
+    // it is a TemplateSpecializationType that we will never use again.
+    // In the future, we need to teach getTemplateSpecializationType to only
+    // build the canonical type and return that to us.
+    CanonType = Context.getCanonicalType(CanonType);
+  } else if (ClassTemplateDecl *ClassTemplate
+               = dyn_cast<ClassTemplateDecl>(Template)) {
+    // Find the class template specialization declaration that
+    // corresponds to these arguments.
+    llvm::FoldingSetNodeID ID;
+    ClassTemplateSpecializationDecl::Profile(ID,
+                                             Converted.getFlatArguments(),
+                                             Converted.flatSize(),
+                                             Context);
+    void *InsertPos = 0;
+    ClassTemplateSpecializationDecl *Decl
+      = ClassTemplate->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
+    if (!Decl) {
+      // This is the first time we have referenced this class template
+      // specialization. Create the canonical declaration and add it to
+      // the set of specializations.
+      Decl = ClassTemplateSpecializationDecl::Create(Context,
+                                    ClassTemplate->getDeclContext(),
+                                    ClassTemplate->getLocation(),
+                                    ClassTemplate,
+                                    Converted, 0);
+      ClassTemplate->getSpecializations().InsertNode(Decl, InsertPos);
+      Decl->setLexicalDeclContext(CurContext);
+    }
+
+    CanonType = Context.getTypeDeclType(Decl);
+  }
+
+  // Build the fully-sugared type for this class template
+  // specialization, which refers back to the class template
+  // specialization we created or found.
+  return Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
+}
+
+Action::TypeResult
+Sema::ActOnTemplateIdType(TemplateTy TemplateD, SourceLocation TemplateLoc,
+                          SourceLocation LAngleLoc,
+                          ASTTemplateArgsPtr TemplateArgsIn,
+                          SourceLocation RAngleLoc) {
+  TemplateName Template = TemplateD.getAsVal<TemplateName>();
+
+  // Translate the parser's template argument list in our AST format.
+  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
+  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
+
+  QualType Result = CheckTemplateIdType(Template, TemplateLoc, TemplateArgs);
+  TemplateArgsIn.release();
+
+  if (Result.isNull())
+    return true;
+
+  TypeSourceInfo *DI = Context.CreateTypeSourceInfo(Result);
+  TemplateSpecializationTypeLoc TL
+    = cast<TemplateSpecializationTypeLoc>(DI->getTypeLoc());
+  TL.setTemplateNameLoc(TemplateLoc);
+  TL.setLAngleLoc(LAngleLoc);
+  TL.setRAngleLoc(RAngleLoc);
+  for (unsigned i = 0, e = TL.getNumArgs(); i != e; ++i)
+    TL.setArgLocInfo(i, TemplateArgs[i].getLocInfo());
+
+  return CreateLocInfoType(Result, DI).getAsOpaquePtr();
+}
+
+Sema::TypeResult Sema::ActOnTagTemplateIdType(TypeResult TypeResult,
+                                              TagUseKind TUK,
+                                              DeclSpec::TST TagSpec,
+                                              SourceLocation TagLoc) {
+  if (TypeResult.isInvalid())
+    return Sema::TypeResult();
+
+  // FIXME: preserve source info, ideally without copying the DI.
+  TypeSourceInfo *DI;
+  QualType Type = GetTypeFromParser(TypeResult.get(), &DI);
+
+  // Verify the tag specifier.
+  TagDecl::TagKind TagKind = TagDecl::getTagKindForTypeSpec(TagSpec);
+
+  if (const RecordType *RT = Type->getAs<RecordType>()) {
+    RecordDecl *D = RT->getDecl();
+
+    IdentifierInfo *Id = D->getIdentifier();
+    assert(Id && "templated class must have an identifier");
+
+    if (!isAcceptableTagRedeclaration(D, TagKind, TagLoc, *Id)) {
+      Diag(TagLoc, diag::err_use_with_wrong_tag)
+        << Type
+        << CodeModificationHint::CreateReplacement(SourceRange(TagLoc),
+                                                   D->getKindName());
+      Diag(D->getLocation(), diag::note_previous_use);
+    }
+  }
+
+  QualType ElabType = Context.getElaboratedType(Type, TagKind);
+
+  return ElabType.getAsOpaquePtr();
+}
+
+Sema::OwningExprResult Sema::BuildTemplateIdExpr(const CXXScopeSpec &SS,
+                                                 LookupResult &R,
+                                                 bool RequiresADL,
+                                 const TemplateArgumentListInfo &TemplateArgs) {
+  // FIXME: Can we do any checking at this point? I guess we could check the
+  // template arguments that we have against the template name, if the template
+  // name refers to a single template. That's not a terribly common case,
+  // though.
+
+  // These should be filtered out by our callers.
+  assert(!R.empty() && "empty lookup results when building templateid");
+  assert(!R.isAmbiguous() && "ambiguous lookup when building templateid");
+
+  NestedNameSpecifier *Qualifier = 0;
+  SourceRange QualifierRange;
+  if (SS.isSet()) {
+    Qualifier = static_cast<NestedNameSpecifier*>(SS.getScopeRep());
+    QualifierRange = SS.getRange();
+  }
+
+  // We don't want lookup warnings at this point.
+  R.suppressDiagnostics();
+  
+  bool Dependent
+    = UnresolvedLookupExpr::ComputeDependence(R.begin(), R.end(),
+                                              &TemplateArgs);
+  UnresolvedLookupExpr *ULE
+    = UnresolvedLookupExpr::Create(Context, Dependent, R.getNamingClass(),
+                                   Qualifier, QualifierRange,
+                                   R.getLookupName(), R.getNameLoc(),
+                                   RequiresADL, TemplateArgs);
+  ULE->addDecls(R.begin(), R.end());
+
+  return Owned(ULE);
+}
+
+// We actually only call this from template instantiation.
+Sema::OwningExprResult
+Sema::BuildQualifiedTemplateIdExpr(const CXXScopeSpec &SS,
+                                   DeclarationName Name,
+                                   SourceLocation NameLoc,
+                             const TemplateArgumentListInfo &TemplateArgs) {
+  DeclContext *DC;
+  if (!(DC = computeDeclContext(SS, false)) ||
+      DC->isDependentContext() ||
+      RequireCompleteDeclContext(SS))
+    return BuildDependentDeclRefExpr(SS, Name, NameLoc, &TemplateArgs);
+
+  LookupResult R(*this, Name, NameLoc, LookupOrdinaryName);
+  LookupTemplateName(R, (Scope*) 0, SS, QualType(), /*Entering*/ false);
+
+  if (R.isAmbiguous())
+    return ExprError();
+  
+  if (R.empty()) {
+    Diag(NameLoc, diag::err_template_kw_refers_to_non_template)
+      << Name << SS.getRange();
+    return ExprError();
+  }
+
+  if (ClassTemplateDecl *Temp = R.getAsSingle<ClassTemplateDecl>()) {
+    Diag(NameLoc, diag::err_template_kw_refers_to_class_template)
+      << (NestedNameSpecifier*) SS.getScopeRep() << Name << SS.getRange();
+    Diag(Temp->getLocation(), diag::note_referenced_class_template);
+    return ExprError();
+  }
+
+  return BuildTemplateIdExpr(SS, R, /* ADL */ false, TemplateArgs);
+}
+
+/// \brief Form a dependent template name.
+///
+/// This action forms a dependent template name given the template
+/// name and its (presumably dependent) scope specifier. For
+/// example, given "MetaFun::template apply", the scope specifier \p
+/// SS will be "MetaFun::", \p TemplateKWLoc contains the location
+/// of the "template" keyword, and "apply" is the \p Name.
+Sema::TemplateTy
+Sema::ActOnDependentTemplateName(SourceLocation TemplateKWLoc,
+                                 const CXXScopeSpec &SS,
+                                 UnqualifiedId &Name,
+                                 TypeTy *ObjectType,
+                                 bool EnteringContext) {
+  DeclContext *LookupCtx = 0;
+  if (SS.isSet())
+    LookupCtx = computeDeclContext(SS, EnteringContext);
+  if (!LookupCtx && ObjectType)
+    LookupCtx = computeDeclContext(QualType::getFromOpaquePtr(ObjectType));
+  if (LookupCtx) {
+    // C++0x [temp.names]p5:
+    //   If a name prefixed by the keyword template is not the name of
+    //   a template, the program is ill-formed. [Note: the keyword
+    //   template may not be applied to non-template members of class
+    //   templates. -end note ] [ Note: as is the case with the
+    //   typename prefix, the template prefix is allowed in cases
+    //   where it is not strictly necessary; i.e., when the
+    //   nested-name-specifier or the expression on the left of the ->
+    //   or . is not dependent on a template-parameter, or the use
+    //   does not appear in the scope of a template. -end note]
+    //
+    // Note: C++03 was more strict here, because it banned the use of
+    // the "template" keyword prior to a template-name that was not a
+    // dependent name. C++ DR468 relaxed this requirement (the
+    // "template" keyword is now permitted). We follow the C++0x
+    // rules, even in C++03 mode, retroactively applying the DR.
+    TemplateTy Template;
+    TemplateNameKind TNK = isTemplateName(0, SS, Name, ObjectType,
+                                          EnteringContext, Template);
+    if (TNK == TNK_Non_template && LookupCtx->isDependentContext() &&
+        isa<CXXRecordDecl>(LookupCtx) &&
+        cast<CXXRecordDecl>(LookupCtx)->hasAnyDependentBases()) {
+      // This is a dependent template.
+    } else if (TNK == TNK_Non_template) {
+      Diag(Name.getSourceRange().getBegin(), 
+           diag::err_template_kw_refers_to_non_template)
+        << GetNameFromUnqualifiedId(Name)
+        << Name.getSourceRange();
+      return TemplateTy();
+    } else {
+      // We found something; return it.
+      return Template;
+    }
+  }
+
+  NestedNameSpecifier *Qualifier
+    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
+  
+  switch (Name.getKind()) {
+  case UnqualifiedId::IK_Identifier:
+    return TemplateTy::make(Context.getDependentTemplateName(Qualifier, 
+                                                             Name.Identifier));
+    
+  case UnqualifiedId::IK_OperatorFunctionId:
+    return TemplateTy::make(Context.getDependentTemplateName(Qualifier,
+                                             Name.OperatorFunctionId.Operator));
+
+  case UnqualifiedId::IK_LiteralOperatorId:
+    assert(false && "We don't support these; Parse shouldn't have allowed propagation");
+
+  default:
+    break;
+  }
+  
+  Diag(Name.getSourceRange().getBegin(), 
+       diag::err_template_kw_refers_to_non_template)
+    << GetNameFromUnqualifiedId(Name)
+    << Name.getSourceRange();
+  return TemplateTy();
+}
+
+bool Sema::CheckTemplateTypeArgument(TemplateTypeParmDecl *Param,
+                                     const TemplateArgumentLoc &AL,
+                                     TemplateArgumentListBuilder &Converted) {
+  const TemplateArgument &Arg = AL.getArgument();
+
+  // Check template type parameter.
+  if (Arg.getKind() != TemplateArgument::Type) {
+    // C++ [temp.arg.type]p1:
+    //   A template-argument for a template-parameter which is a
+    //   type shall be a type-id.
+
+    // We have a template type parameter but the template argument
+    // is not a type.
+    SourceRange SR = AL.getSourceRange();
+    Diag(SR.getBegin(), diag::err_template_arg_must_be_type) << SR;
+    Diag(Param->getLocation(), diag::note_template_param_here);
+
+    return true;
+  }
+
+  if (CheckTemplateArgument(Param, AL.getTypeSourceInfo()))
+    return true;
+
+  // Add the converted template type argument.
+  Converted.Append(
+                 TemplateArgument(Context.getCanonicalType(Arg.getAsType())));
+  return false;
+}
+
+/// \brief Substitute template arguments into the default template argument for
+/// the given template type parameter.
+///
+/// \param SemaRef the semantic analysis object for which we are performing
+/// the substitution.
+///
+/// \param Template the template that we are synthesizing template arguments 
+/// for.
+///
+/// \param TemplateLoc the location of the template name that started the
+/// template-id we are checking.
+///
+/// \param RAngleLoc the location of the right angle bracket ('>') that
+/// terminates the template-id.
+///
+/// \param Param the template template parameter whose default we are
+/// substituting into.
+///
+/// \param Converted the list of template arguments provided for template
+/// parameters that precede \p Param in the template parameter list.
+///
+/// \returns the substituted template argument, or NULL if an error occurred.
+static TypeSourceInfo *
+SubstDefaultTemplateArgument(Sema &SemaRef,
+                             TemplateDecl *Template,
+                             SourceLocation TemplateLoc,
+                             SourceLocation RAngleLoc,
+                             TemplateTypeParmDecl *Param,
+                             TemplateArgumentListBuilder &Converted) {
+  TypeSourceInfo *ArgType = Param->getDefaultArgumentInfo();
+
+  // If the argument type is dependent, instantiate it now based
+  // on the previously-computed template arguments.
+  if (ArgType->getType()->isDependentType()) {
+    TemplateArgumentList TemplateArgs(SemaRef.Context, Converted,
+                                      /*TakeArgs=*/false);
+    
+    MultiLevelTemplateArgumentList AllTemplateArgs
+      = SemaRef.getTemplateInstantiationArgs(Template, &TemplateArgs);
+
+    Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
+                                     Template, Converted.getFlatArguments(),
+                                     Converted.flatSize(),
+                                     SourceRange(TemplateLoc, RAngleLoc));
+    
+    ArgType = SemaRef.SubstType(ArgType, AllTemplateArgs,
+                                Param->getDefaultArgumentLoc(),
+                                Param->getDeclName());
+  }
+
+  return ArgType;
+}
+
+/// \brief Substitute template arguments into the default template argument for
+/// the given non-type template parameter.
+///
+/// \param SemaRef the semantic analysis object for which we are performing
+/// the substitution.
+///
+/// \param Template the template that we are synthesizing template arguments 
+/// for.
+///
+/// \param TemplateLoc the location of the template name that started the
+/// template-id we are checking.
+///
+/// \param RAngleLoc the location of the right angle bracket ('>') that
+/// terminates the template-id.
+///
+/// \param Param the non-type template parameter whose default we are
+/// substituting into.
+///
+/// \param Converted the list of template arguments provided for template
+/// parameters that precede \p Param in the template parameter list.
+///
+/// \returns the substituted template argument, or NULL if an error occurred.
+static Sema::OwningExprResult
+SubstDefaultTemplateArgument(Sema &SemaRef,
+                             TemplateDecl *Template,
+                             SourceLocation TemplateLoc,
+                             SourceLocation RAngleLoc,
+                             NonTypeTemplateParmDecl *Param,
+                             TemplateArgumentListBuilder &Converted) {
+  TemplateArgumentList TemplateArgs(SemaRef.Context, Converted,
+                                    /*TakeArgs=*/false);
+    
+  MultiLevelTemplateArgumentList AllTemplateArgs
+    = SemaRef.getTemplateInstantiationArgs(Template, &TemplateArgs);
+    
+  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
+                                   Template, Converted.getFlatArguments(),
+                                   Converted.flatSize(),
+                                   SourceRange(TemplateLoc, RAngleLoc));
+
+  return SemaRef.SubstExpr(Param->getDefaultArgument(), AllTemplateArgs);
+}
+
+/// \brief Substitute template arguments into the default template argument for
+/// the given template template parameter.
+///
+/// \param SemaRef the semantic analysis object for which we are performing
+/// the substitution.
+///
+/// \param Template the template that we are synthesizing template arguments 
+/// for.
+///
+/// \param TemplateLoc the location of the template name that started the
+/// template-id we are checking.
+///
+/// \param RAngleLoc the location of the right angle bracket ('>') that
+/// terminates the template-id.
+///
+/// \param Param the template template parameter whose default we are
+/// substituting into.
+///
+/// \param Converted the list of template arguments provided for template
+/// parameters that precede \p Param in the template parameter list.
+///
+/// \returns the substituted template argument, or NULL if an error occurred.
+static TemplateName
+SubstDefaultTemplateArgument(Sema &SemaRef,
+                             TemplateDecl *Template,
+                             SourceLocation TemplateLoc,
+                             SourceLocation RAngleLoc,
+                             TemplateTemplateParmDecl *Param,
+                             TemplateArgumentListBuilder &Converted) {
+  TemplateArgumentList TemplateArgs(SemaRef.Context, Converted,
+                                    /*TakeArgs=*/false);
+  
+  MultiLevelTemplateArgumentList AllTemplateArgs
+    = SemaRef.getTemplateInstantiationArgs(Template, &TemplateArgs);
+  
+  Sema::InstantiatingTemplate Inst(SemaRef, TemplateLoc,
+                                   Template, Converted.getFlatArguments(),
+                                   Converted.flatSize(),
+                                   SourceRange(TemplateLoc, RAngleLoc));
+  
+  return SemaRef.SubstTemplateName(
+                      Param->getDefaultArgument().getArgument().getAsTemplate(),
+                              Param->getDefaultArgument().getTemplateNameLoc(), 
+                                   AllTemplateArgs);
+}
+
+/// \brief If the given template parameter has a default template
+/// argument, substitute into that default template argument and
+/// return the corresponding template argument.
+TemplateArgumentLoc 
+Sema::SubstDefaultTemplateArgumentIfAvailable(TemplateDecl *Template,
+                                              SourceLocation TemplateLoc,
+                                              SourceLocation RAngleLoc,
+                                              Decl *Param,
+                                     TemplateArgumentListBuilder &Converted) {
+  if (TemplateTypeParmDecl *TypeParm = dyn_cast<TemplateTypeParmDecl>(Param)) {
+    if (!TypeParm->hasDefaultArgument())
+      return TemplateArgumentLoc();
+
+    TypeSourceInfo *DI = SubstDefaultTemplateArgument(*this, Template,
+                                                      TemplateLoc,
+                                                      RAngleLoc,
+                                                      TypeParm,
+                                                      Converted);
+    if (DI)
+      return TemplateArgumentLoc(TemplateArgument(DI->getType()), DI);
+
+    return TemplateArgumentLoc();
+  }
+
+  if (NonTypeTemplateParmDecl *NonTypeParm
+        = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
+    if (!NonTypeParm->hasDefaultArgument())
+      return TemplateArgumentLoc();
+
+    OwningExprResult Arg = SubstDefaultTemplateArgument(*this, Template,
+                                                        TemplateLoc,
+                                                        RAngleLoc,
+                                                        NonTypeParm,
+                                                        Converted);
+    if (Arg.isInvalid())
+      return TemplateArgumentLoc();
+
+    Expr *ArgE = Arg.takeAs<Expr>();
+    return TemplateArgumentLoc(TemplateArgument(ArgE), ArgE);
+  }
+
+  TemplateTemplateParmDecl *TempTempParm
+    = cast<TemplateTemplateParmDecl>(Param);
+  if (!TempTempParm->hasDefaultArgument())
+    return TemplateArgumentLoc();
+
+  TemplateName TName = SubstDefaultTemplateArgument(*this, Template,
+                                                    TemplateLoc, 
+                                                    RAngleLoc,
+                                                    TempTempParm,
+                                                    Converted);
+  if (TName.isNull())
+    return TemplateArgumentLoc();
+
+  return TemplateArgumentLoc(TemplateArgument(TName), 
+                TempTempParm->getDefaultArgument().getTemplateQualifierRange(),
+                TempTempParm->getDefaultArgument().getTemplateNameLoc());
+}
+
+/// \brief Check that the given template argument corresponds to the given
+/// template parameter.
+bool Sema::CheckTemplateArgument(NamedDecl *Param,
+                                 const TemplateArgumentLoc &Arg,
+                                 TemplateDecl *Template,
+                                 SourceLocation TemplateLoc,
+                                 SourceLocation RAngleLoc,
+                                 TemplateArgumentListBuilder &Converted) {
+  // Check template type parameters.
+  if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param))
+    return CheckTemplateTypeArgument(TTP, Arg, Converted);
+  
+  // Check non-type template parameters.
+  if (NonTypeTemplateParmDecl *NTTP =dyn_cast<NonTypeTemplateParmDecl>(Param)) {    
+    // Do substitution on the type of the non-type template parameter
+    // with the template arguments we've seen thus far.
+    QualType NTTPType = NTTP->getType();
+    if (NTTPType->isDependentType()) {
+      // Do substitution on the type of the non-type template parameter.
+      InstantiatingTemplate Inst(*this, TemplateLoc, Template,
+                                 NTTP, Converted.getFlatArguments(),
+                                 Converted.flatSize(),
+                                 SourceRange(TemplateLoc, RAngleLoc));
+      
+      TemplateArgumentList TemplateArgs(Context, Converted,
+                                        /*TakeArgs=*/false);
+      NTTPType = SubstType(NTTPType,
+                           MultiLevelTemplateArgumentList(TemplateArgs),
+                           NTTP->getLocation(),
+                           NTTP->getDeclName());
+      // If that worked, check the non-type template parameter type
+      // for validity.
+      if (!NTTPType.isNull())
+        NTTPType = CheckNonTypeTemplateParameterType(NTTPType,
+                                                     NTTP->getLocation());
+      if (NTTPType.isNull())
+        return true;
+    }
+    
+    switch (Arg.getArgument().getKind()) {
+    case TemplateArgument::Null:
+      assert(false && "Should never see a NULL template argument here");
+      return true;
+      
+    case TemplateArgument::Expression: {
+      Expr *E = Arg.getArgument().getAsExpr();
+      TemplateArgument Result;
+      if (CheckTemplateArgument(NTTP, NTTPType, E, Result))
+        return true;
+      
+      Converted.Append(Result);
+      break;
+    }
+      
+    case TemplateArgument::Declaration:
+    case TemplateArgument::Integral:
+      // We've already checked this template argument, so just copy
+      // it to the list of converted arguments.
+      Converted.Append(Arg.getArgument());
+      break;
+      
+    case TemplateArgument::Template:
+      // We were given a template template argument. It may not be ill-formed;
+      // see below.
+      if (DependentTemplateName *DTN
+            = Arg.getArgument().getAsTemplate().getAsDependentTemplateName()) {
+        // We have a template argument such as \c T::template X, which we
+        // parsed as a template template argument. However, since we now
+        // know that we need a non-type template argument, convert this
+        // template name into an expression.          
+        Expr *E = DependentScopeDeclRefExpr::Create(Context,
+                                                    DTN->getQualifier(),
+                                               Arg.getTemplateQualifierRange(),
+                                                    DTN->getIdentifier(),
+                                                    Arg.getTemplateNameLoc());
+        
+        TemplateArgument Result;
+        if (CheckTemplateArgument(NTTP, NTTPType, E, Result))
+          return true;
+        
+        Converted.Append(Result);
+        break;
+      }
+      
+      // We have a template argument that actually does refer to a class
+      // template, template alias, or template template parameter, and
+      // therefore cannot be a non-type template argument.
+      Diag(Arg.getLocation(), diag::err_template_arg_must_be_expr)
+        << Arg.getSourceRange();
+      
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+      
+    case TemplateArgument::Type: {
+      // We have a non-type template parameter but the template
+      // argument is a type.
+      
+      // C++ [temp.arg]p2:
+      //   In a template-argument, an ambiguity between a type-id and
+      //   an expression is resolved to a type-id, regardless of the
+      //   form of the corresponding template-parameter.
+      //
+      // We warn specifically about this case, since it can be rather
+      // confusing for users.
+      QualType T = Arg.getArgument().getAsType();
+      SourceRange SR = Arg.getSourceRange();
+      if (T->isFunctionType())
+        Diag(SR.getBegin(), diag::err_template_arg_nontype_ambig) << SR << T;
+      else
+        Diag(SR.getBegin(), diag::err_template_arg_must_be_expr) << SR;
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+      
+    case TemplateArgument::Pack:
+      llvm_unreachable("Caller must expand template argument packs");
+      break;
+    }
+    
+    return false;
+  } 
+  
+  
+  // Check template template parameters.
+  TemplateTemplateParmDecl *TempParm = cast<TemplateTemplateParmDecl>(Param);
+    
+  // Substitute into the template parameter list of the template
+  // template parameter, since previously-supplied template arguments
+  // may appear within the template template parameter.
+  {
+    // Set up a template instantiation context.
+    LocalInstantiationScope Scope(*this);
+    InstantiatingTemplate Inst(*this, TemplateLoc, Template,
+                               TempParm, Converted.getFlatArguments(),
+                               Converted.flatSize(),
+                               SourceRange(TemplateLoc, RAngleLoc));
+    
+    TemplateArgumentList TemplateArgs(Context, Converted,
+                                      /*TakeArgs=*/false);
+    TempParm = cast_or_null<TemplateTemplateParmDecl>(
+                      SubstDecl(TempParm, CurContext, 
+                                MultiLevelTemplateArgumentList(TemplateArgs)));
+    if (!TempParm)
+      return true;
+    
+    // FIXME: TempParam is leaked.
+  }
+    
+  switch (Arg.getArgument().getKind()) {
+  case TemplateArgument::Null:
+    assert(false && "Should never see a NULL template argument here");
+    return true;
+    
+  case TemplateArgument::Template:
+    if (CheckTemplateArgument(TempParm, Arg))
+      return true;
+      
+    Converted.Append(Arg.getArgument());
+    break;
+    
+  case TemplateArgument::Expression:
+  case TemplateArgument::Type:
+    // We have a template template parameter but the template
+    // argument does not refer to a template.
+    Diag(Arg.getLocation(), diag::err_template_arg_must_be_template);
+    return true;
+      
+  case TemplateArgument::Declaration:
+    llvm_unreachable(
+                       "Declaration argument with template template parameter");
+    break;
+  case TemplateArgument::Integral:
+    llvm_unreachable(
+                          "Integral argument with template template parameter");
+    break;
+    
+  case TemplateArgument::Pack:
+    llvm_unreachable("Caller must expand template argument packs");
+    break;
+  }
+  
+  return false;
+}
+
+/// \brief Check that the given template argument list is well-formed
+/// for specializing the given template.
+bool Sema::CheckTemplateArgumentList(TemplateDecl *Template,
+                                     SourceLocation TemplateLoc,
+                                const TemplateArgumentListInfo &TemplateArgs,
+                                     bool PartialTemplateArgs,
+                                     TemplateArgumentListBuilder &Converted) {
+  TemplateParameterList *Params = Template->getTemplateParameters();
+  unsigned NumParams = Params->size();
+  unsigned NumArgs = TemplateArgs.size();
+  bool Invalid = false;
+
+  SourceLocation RAngleLoc = TemplateArgs.getRAngleLoc();
+
+  bool HasParameterPack =
+    NumParams > 0 && Params->getParam(NumParams - 1)->isTemplateParameterPack();
+
+  if ((NumArgs > NumParams && !HasParameterPack) ||
+      (NumArgs < Params->getMinRequiredArguments() &&
+       !PartialTemplateArgs)) {
+    // FIXME: point at either the first arg beyond what we can handle,
+    // or the '>', depending on whether we have too many or too few
+    // arguments.
+    SourceRange Range;
+    if (NumArgs > NumParams)
+      Range = SourceRange(TemplateArgs[NumParams].getLocation(), RAngleLoc);
+    Diag(TemplateLoc, diag::err_template_arg_list_different_arity)
+      << (NumArgs > NumParams)
+      << (isa<ClassTemplateDecl>(Template)? 0 :
+          isa<FunctionTemplateDecl>(Template)? 1 :
+          isa<TemplateTemplateParmDecl>(Template)? 2 : 3)
+      << Template << Range;
+    Diag(Template->getLocation(), diag::note_template_decl_here)
+      << Params->getSourceRange();
+    Invalid = true;
+  }
+
+  // C++ [temp.arg]p1:
+  //   [...] The type and form of each template-argument specified in
+  //   a template-id shall match the type and form specified for the
+  //   corresponding parameter declared by the template in its
+  //   template-parameter-list.
+  unsigned ArgIdx = 0;
+  for (TemplateParameterList::iterator Param = Params->begin(),
+                                       ParamEnd = Params->end();
+       Param != ParamEnd; ++Param, ++ArgIdx) {
+    if (ArgIdx > NumArgs && PartialTemplateArgs)
+      break;
+
+    // If we have a template parameter pack, check every remaining template
+    // argument against that template parameter pack.
+    if ((*Param)->isTemplateParameterPack()) {
+      Converted.BeginPack();
+      for (; ArgIdx < NumArgs; ++ArgIdx) {
+        if (CheckTemplateArgument(*Param, TemplateArgs[ArgIdx], Template,
+                                  TemplateLoc, RAngleLoc, Converted)) {
+          Invalid = true;
+          break;
+        }
+      }
+      Converted.EndPack();
+      continue;
+    }
+    
+    if (ArgIdx < NumArgs) {
+      // Check the template argument we were given.
+      if (CheckTemplateArgument(*Param, TemplateArgs[ArgIdx], Template, 
+                                TemplateLoc, RAngleLoc, Converted))
+        return true;
+      
+      continue;
+    }
+    
+    // We have a default template argument that we will use.
+    TemplateArgumentLoc Arg;
+    
+    // Retrieve the default template argument from the template
+    // parameter. For each kind of template parameter, we substitute the
+    // template arguments provided thus far and any "outer" template arguments
+    // (when the template parameter was part of a nested template) into 
+    // the default argument.
+    if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(*Param)) {
+      if (!TTP->hasDefaultArgument()) {
+        assert((Invalid || PartialTemplateArgs) && "Missing default argument");
+        break;
+      }
+
+      TypeSourceInfo *ArgType = SubstDefaultTemplateArgument(*this, 
+                                                             Template,
+                                                             TemplateLoc,
+                                                             RAngleLoc,
+                                                             TTP,
+                                                             Converted);
+      if (!ArgType)
+        return true;
+                                                             
+      Arg = TemplateArgumentLoc(TemplateArgument(ArgType->getType()),
+                                ArgType);
+    } else if (NonTypeTemplateParmDecl *NTTP
+                 = dyn_cast<NonTypeTemplateParmDecl>(*Param)) {
+      if (!NTTP->hasDefaultArgument()) {
+        assert((Invalid || PartialTemplateArgs) && "Missing default argument");
+        break;
+      }
+
+      Sema::OwningExprResult E = SubstDefaultTemplateArgument(*this, Template,
+                                                              TemplateLoc, 
+                                                              RAngleLoc, 
+                                                              NTTP, 
+                                                              Converted);
+      if (E.isInvalid())
+        return true;
+
+      Expr *Ex = E.takeAs<Expr>();
+      Arg = TemplateArgumentLoc(TemplateArgument(Ex), Ex);
+    } else {
+      TemplateTemplateParmDecl *TempParm
+        = cast<TemplateTemplateParmDecl>(*Param);
+
+      if (!TempParm->hasDefaultArgument()) {
+        assert((Invalid || PartialTemplateArgs) && "Missing default argument");
+        break;
+      }
+
+      TemplateName Name = SubstDefaultTemplateArgument(*this, Template,
+                                                       TemplateLoc, 
+                                                       RAngleLoc, 
+                                                       TempParm,
+                                                       Converted);
+      if (Name.isNull())
+        return true;
+      
+      Arg = TemplateArgumentLoc(TemplateArgument(Name), 
+                  TempParm->getDefaultArgument().getTemplateQualifierRange(),
+                  TempParm->getDefaultArgument().getTemplateNameLoc());
+    }
+    
+    // Introduce an instantiation record that describes where we are using
+    // the default template argument.
+    InstantiatingTemplate Instantiating(*this, RAngleLoc, Template, *Param,
+                                        Converted.getFlatArguments(),
+                                        Converted.flatSize(),
+                                        SourceRange(TemplateLoc, RAngleLoc));    
+    
+    // Check the default template argument.
+    if (CheckTemplateArgument(*Param, Arg, Template, TemplateLoc,
+                              RAngleLoc, Converted))
+      return true;
+  }
+
+  return Invalid;
+}
+
+/// \brief Check a template argument against its corresponding
+/// template type parameter.
+///
+/// This routine implements the semantics of C++ [temp.arg.type]. It
+/// returns true if an error occurred, and false otherwise.
+bool Sema::CheckTemplateArgument(TemplateTypeParmDecl *Param,
+                                 TypeSourceInfo *ArgInfo) {
+  assert(ArgInfo && "invalid TypeSourceInfo");
+  QualType Arg = ArgInfo->getType();
+
+  // C++ [temp.arg.type]p2:
+  //   A local type, a type with no linkage, an unnamed type or a type
+  //   compounded from any of these types shall not be used as a
+  //   template-argument for a template type-parameter.
+  //
+  // FIXME: Perform the recursive and no-linkage type checks.
+  const TagType *Tag = 0;
+  if (const EnumType *EnumT = Arg->getAs<EnumType>())
+    Tag = EnumT;
+  else if (const RecordType *RecordT = Arg->getAs<RecordType>())
+    Tag = RecordT;
+  if (Tag && Tag->getDecl()->getDeclContext()->isFunctionOrMethod()) {
+    SourceRange SR = ArgInfo->getTypeLoc().getFullSourceRange();
+    return Diag(SR.getBegin(), diag::err_template_arg_local_type)
+      << QualType(Tag, 0) << SR;
+  } else if (Tag && !Tag->getDecl()->getDeclName() &&
+           !Tag->getDecl()->getTypedefForAnonDecl()) {
+    SourceRange SR = ArgInfo->getTypeLoc().getFullSourceRange();
+    Diag(SR.getBegin(), diag::err_template_arg_unnamed_type) << SR;
+    Diag(Tag->getDecl()->getLocation(), diag::note_template_unnamed_type_here);
+    return true;
+  } else if (Context.hasSameUnqualifiedType(Arg, Context.OverloadTy)) {
+    SourceRange SR = ArgInfo->getTypeLoc().getFullSourceRange();
+    return Diag(SR.getBegin(), diag::err_template_arg_overload_type) << SR;
+  }
+
+  return false;
+}
+
+/// \brief Checks whether the given template argument is the address
+/// of an object or function according to C++ [temp.arg.nontype]p1.
+bool Sema::CheckTemplateArgumentAddressOfObjectOrFunction(Expr *Arg,
+                                                          NamedDecl *&Entity) {
+  bool Invalid = false;
+
+  // See through any implicit casts we added to fix the type.
+  while (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(Arg))
+    Arg = Cast->getSubExpr();
+
+  // C++0x allows nullptr, and there's no further checking to be done for that.
+  if (Arg->getType()->isNullPtrType())
+    return false;
+
+  // C++ [temp.arg.nontype]p1:
+  //
+  //   A template-argument for a non-type, non-template
+  //   template-parameter shall be one of: [...]
+  //
+  //     -- the address of an object or function with external
+  //        linkage, including function templates and function
+  //        template-ids but excluding non-static class members,
+  //        expressed as & id-expression where the & is optional if
+  //        the name refers to a function or array, or if the
+  //        corresponding template-parameter is a reference; or
+  DeclRefExpr *DRE = 0;
+
+  // Ignore (and complain about) any excess parentheses.
+  while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
+    if (!Invalid) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_extra_parens)
+        << Arg->getSourceRange();
+      Invalid = true;
+    }
+
+    Arg = Parens->getSubExpr();
+  }
+
+  if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
+    if (UnOp->getOpcode() == UnaryOperator::AddrOf)
+      DRE = dyn_cast<DeclRefExpr>(UnOp->getSubExpr());
+  } else
+    DRE = dyn_cast<DeclRefExpr>(Arg);
+
+  if (!DRE)
+    return Diag(Arg->getSourceRange().getBegin(),
+                diag::err_template_arg_not_decl_ref)
+      << Arg->getSourceRange();
+
+  // Stop checking the precise nature of the argument if it is value dependent,
+  // it should be checked when instantiated.
+  if (Arg->isValueDependent())
+    return false;
+
+  if (!isa<ValueDecl>(DRE->getDecl()))
+    return Diag(Arg->getSourceRange().getBegin(),
+                diag::err_template_arg_not_object_or_func_form)
+      << Arg->getSourceRange();
+
+  // Cannot refer to non-static data members
+  if (FieldDecl *Field = dyn_cast<FieldDecl>(DRE->getDecl()))
+    return Diag(Arg->getSourceRange().getBegin(), diag::err_template_arg_field)
+      << Field << Arg->getSourceRange();
+
+  // Cannot refer to non-static member functions
+  if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(DRE->getDecl()))
+    if (!Method->isStatic())
+      return Diag(Arg->getSourceRange().getBegin(),
+                  diag::err_template_arg_method)
+        << Method << Arg->getSourceRange();
+
+  // Functions must have external linkage.
+  if (FunctionDecl *Func = dyn_cast<FunctionDecl>(DRE->getDecl())) {
+    if (!isExternalLinkage(Func->getLinkage())) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_function_not_extern)
+        << Func << Arg->getSourceRange();
+      Diag(Func->getLocation(), diag::note_template_arg_internal_object)
+        << true;
+      return true;
+    }
+
+    // Okay: we've named a function with external linkage.
+    Entity = Func;
+    return Invalid;
+  }
+
+  if (VarDecl *Var = dyn_cast<VarDecl>(DRE->getDecl())) {
+    if (!isExternalLinkage(Var->getLinkage())) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_object_not_extern)
+        << Var << Arg->getSourceRange();
+      Diag(Var->getLocation(), diag::note_template_arg_internal_object)
+        << true;
+      return true;
+    }
+
+    // Okay: we've named an object with external linkage
+    Entity = Var;
+    return Invalid;
+  }
+
+  // We found something else, but we don't know specifically what it is.
+  Diag(Arg->getSourceRange().getBegin(),
+       diag::err_template_arg_not_object_or_func)
+      << Arg->getSourceRange();
+  Diag(DRE->getDecl()->getLocation(),
+       diag::note_template_arg_refers_here);
+  return true;
+}
+
+/// \brief Checks whether the given template argument is a pointer to
+/// member constant according to C++ [temp.arg.nontype]p1.
+bool Sema::CheckTemplateArgumentPointerToMember(Expr *Arg, 
+                                                TemplateArgument &Converted) {
+  bool Invalid = false;
+
+  // See through any implicit casts we added to fix the type.
+  while (ImplicitCastExpr *Cast = dyn_cast<ImplicitCastExpr>(Arg))
+    Arg = Cast->getSubExpr();
+
+  // C++0x allows nullptr, and there's no further checking to be done for that.
+  if (Arg->getType()->isNullPtrType())
+    return false;
+
+  // C++ [temp.arg.nontype]p1:
+  //
+  //   A template-argument for a non-type, non-template
+  //   template-parameter shall be one of: [...]
+  //
+  //     -- a pointer to member expressed as described in 5.3.1.
+  DeclRefExpr *DRE = 0;
+
+  // Ignore (and complain about) any excess parentheses.
+  while (ParenExpr *Parens = dyn_cast<ParenExpr>(Arg)) {
+    if (!Invalid) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_extra_parens)
+        << Arg->getSourceRange();
+      Invalid = true;
+    }
+
+    Arg = Parens->getSubExpr();
+  }
+
+  // A pointer-to-member constant written &Class::member.
+  if (UnaryOperator *UnOp = dyn_cast<UnaryOperator>(Arg)) {
+    if (UnOp->getOpcode() == UnaryOperator::AddrOf) {
+      DRE = dyn_cast<DeclRefExpr>(UnOp->getSubExpr());
+      if (DRE && !DRE->getQualifier())
+        DRE = 0;
+    }
+  } 
+  // A constant of pointer-to-member type.
+  else if ((DRE = dyn_cast<DeclRefExpr>(Arg))) {
+    if (ValueDecl *VD = dyn_cast<ValueDecl>(DRE->getDecl())) {
+      if (VD->getType()->isMemberPointerType()) {
+        if (isa<NonTypeTemplateParmDecl>(VD) ||
+            (isa<VarDecl>(VD) && 
+             Context.getCanonicalType(VD->getType()).isConstQualified())) {
+          if (Arg->isTypeDependent() || Arg->isValueDependent())
+            Converted = TemplateArgument(Arg->Retain());
+          else
+            Converted = TemplateArgument(VD->getCanonicalDecl());
+          return Invalid;
+        }
+      }
+    }
+    
+    DRE = 0;
+  }
+  
+  if (!DRE)
+    return Diag(Arg->getSourceRange().getBegin(),
+                diag::err_template_arg_not_pointer_to_member_form)
+      << Arg->getSourceRange();
+
+  if (isa<FieldDecl>(DRE->getDecl()) || isa<CXXMethodDecl>(DRE->getDecl())) {
+    assert((isa<FieldDecl>(DRE->getDecl()) ||
+            !cast<CXXMethodDecl>(DRE->getDecl())->isStatic()) &&
+           "Only non-static member pointers can make it here");
+
+    // Okay: this is the address of a non-static member, and therefore
+    // a member pointer constant.
+    if (Arg->isTypeDependent() || Arg->isValueDependent())
+      Converted = TemplateArgument(Arg->Retain());
+    else
+      Converted = TemplateArgument(DRE->getDecl()->getCanonicalDecl());
+    return Invalid;
+  }
+
+  // We found something else, but we don't know specifically what it is.
+  Diag(Arg->getSourceRange().getBegin(),
+       diag::err_template_arg_not_pointer_to_member_form)
+      << Arg->getSourceRange();
+  Diag(DRE->getDecl()->getLocation(),
+       diag::note_template_arg_refers_here);
+  return true;
+}
+
+/// \brief Check a template argument against its corresponding
+/// non-type template parameter.
+///
+/// This routine implements the semantics of C++ [temp.arg.nontype].
+/// It returns true if an error occurred, and false otherwise. \p
+/// InstantiatedParamType is the type of the non-type template
+/// parameter after it has been instantiated.
+///
+/// If no error was detected, Converted receives the converted template argument.
+bool Sema::CheckTemplateArgument(NonTypeTemplateParmDecl *Param,
+                                 QualType InstantiatedParamType, Expr *&Arg,
+                                 TemplateArgument &Converted) {
+  SourceLocation StartLoc = Arg->getSourceRange().getBegin();
+
+  // If either the parameter has a dependent type or the argument is
+  // type-dependent, there's nothing we can check now.
+  // FIXME: Add template argument to Converted!
+  if (InstantiatedParamType->isDependentType() || Arg->isTypeDependent()) {
+    // FIXME: Produce a cloned, canonical expression?
+    Converted = TemplateArgument(Arg);
+    return false;
+  }
+
+  // C++ [temp.arg.nontype]p5:
+  //   The following conversions are performed on each expression used
+  //   as a non-type template-argument. If a non-type
+  //   template-argument cannot be converted to the type of the
+  //   corresponding template-parameter then the program is
+  //   ill-formed.
+  //
+  //     -- for a non-type template-parameter of integral or
+  //        enumeration type, integral promotions (4.5) and integral
+  //        conversions (4.7) are applied.
+  QualType ParamType = InstantiatedParamType;
+  QualType ArgType = Arg->getType();
+  if (ParamType->isIntegralType() || ParamType->isEnumeralType()) {
+    // C++ [temp.arg.nontype]p1:
+    //   A template-argument for a non-type, non-template
+    //   template-parameter shall be one of:
+    //
+    //     -- an integral constant-expression of integral or enumeration
+    //        type; or
+    //     -- the name of a non-type template-parameter; or
+    SourceLocation NonConstantLoc;
+    llvm::APSInt Value;
+    if (!ArgType->isIntegralType() && !ArgType->isEnumeralType()) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_not_integral_or_enumeral)
+        << ArgType << Arg->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    } else if (!Arg->isValueDependent() &&
+               !Arg->isIntegerConstantExpr(Value, Context, &NonConstantLoc)) {
+      Diag(NonConstantLoc, diag::err_template_arg_not_ice)
+        << ArgType << Arg->getSourceRange();
+      return true;
+    }
+
+    // FIXME: We need some way to more easily get the unqualified form
+    // of the types without going all the way to the
+    // canonical type.
+    if (Context.getCanonicalType(ParamType).getCVRQualifiers())
+      ParamType = Context.getCanonicalType(ParamType).getUnqualifiedType();
+    if (Context.getCanonicalType(ArgType).getCVRQualifiers())
+      ArgType = Context.getCanonicalType(ArgType).getUnqualifiedType();
+
+    // Try to convert the argument to the parameter's type.
+    if (Context.hasSameType(ParamType, ArgType)) {
+      // Okay: no conversion necessary
+    } else if (IsIntegralPromotion(Arg, ArgType, ParamType) ||
+               !ParamType->isEnumeralType()) {
+      // This is an integral promotion or conversion.
+      ImpCastExprToType(Arg, ParamType, CastExpr::CK_IntegralCast);
+    } else {
+      // We can't perform this conversion.
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_not_convertible)
+        << Arg->getType() << InstantiatedParamType << Arg->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+
+    QualType IntegerType = Context.getCanonicalType(ParamType);
+    if (const EnumType *Enum = IntegerType->getAs<EnumType>())
+      IntegerType = Context.getCanonicalType(Enum->getDecl()->getIntegerType());
+
+    if (!Arg->isValueDependent()) {
+      // Check that an unsigned parameter does not receive a negative
+      // value.
+      if (IntegerType->isUnsignedIntegerType()
+          && (Value.isSigned() && Value.isNegative())) {
+        Diag(Arg->getSourceRange().getBegin(), diag::err_template_arg_negative)
+          << Value.toString(10) << Param->getType()
+          << Arg->getSourceRange();
+        Diag(Param->getLocation(), diag::note_template_param_here);
+        return true;
+      }
+
+      // Check that we don't overflow the template parameter type.
+      unsigned AllowedBits = Context.getTypeSize(IntegerType);
+      unsigned RequiredBits;
+      if (IntegerType->isUnsignedIntegerType())
+        RequiredBits = Value.getActiveBits();
+      else if (Value.isUnsigned())
+        RequiredBits = Value.getActiveBits() + 1;
+      else
+        RequiredBits = Value.getMinSignedBits();
+      if (RequiredBits > AllowedBits) {
+        Diag(Arg->getSourceRange().getBegin(),
+             diag::err_template_arg_too_large)
+          << Value.toString(10) << Param->getType()
+          << Arg->getSourceRange();
+        Diag(Param->getLocation(), diag::note_template_param_here);
+        return true;
+      }
+
+      if (Value.getBitWidth() != AllowedBits)
+        Value.extOrTrunc(AllowedBits);
+      Value.setIsSigned(IntegerType->isSignedIntegerType());
+    }
+
+    // Add the value of this argument to the list of converted
+    // arguments. We use the bitwidth and signedness of the template
+    // parameter.
+    if (Arg->isValueDependent()) {
+      // The argument is value-dependent. Create a new
+      // TemplateArgument with the converted expression.
+      Converted = TemplateArgument(Arg);
+      return false;
+    }
+
+    Converted = TemplateArgument(Value,
+                                 ParamType->isEnumeralType() ? ParamType
+                                                             : IntegerType);
+    return false;
+  }
+
+  // Handle pointer-to-function, reference-to-function, and
+  // pointer-to-member-function all in (roughly) the same way.
+  if (// -- For a non-type template-parameter of type pointer to
+      //    function, only the function-to-pointer conversion (4.3) is
+      //    applied. If the template-argument represents a set of
+      //    overloaded functions (or a pointer to such), the matching
+      //    function is selected from the set (13.4).
+      // In C++0x, any std::nullptr_t value can be converted.
+      (ParamType->isPointerType() &&
+       ParamType->getAs<PointerType>()->getPointeeType()->isFunctionType()) ||
+      // -- For a non-type template-parameter of type reference to
+      //    function, no conversions apply. If the template-argument
+      //    represents a set of overloaded functions, the matching
+      //    function is selected from the set (13.4).
+      (ParamType->isReferenceType() &&
+       ParamType->getAs<ReferenceType>()->getPointeeType()->isFunctionType()) ||
+      // -- For a non-type template-parameter of type pointer to
+      //    member function, no conversions apply. If the
+      //    template-argument represents a set of overloaded member
+      //    functions, the matching member function is selected from
+      //    the set (13.4).
+      // Again, C++0x allows a std::nullptr_t value.
+      (ParamType->isMemberPointerType() &&
+       ParamType->getAs<MemberPointerType>()->getPointeeType()
+         ->isFunctionType())) {
+    if (Context.hasSameUnqualifiedType(ArgType,
+                                       ParamType.getNonReferenceType())) {
+      // We don't have to do anything: the types already match.
+    } else if (ArgType->isNullPtrType() && (ParamType->isPointerType() ||
+                 ParamType->isMemberPointerType())) {
+      ArgType = ParamType;
+      if (ParamType->isMemberPointerType())
+        ImpCastExprToType(Arg, ParamType, CastExpr::CK_NullToMemberPointer);
+      else
+        ImpCastExprToType(Arg, ParamType, CastExpr::CK_BitCast);
+    } else if (ArgType->isFunctionType() && ParamType->isPointerType()) {
+      ArgType = Context.getPointerType(ArgType);
+      ImpCastExprToType(Arg, ArgType, CastExpr::CK_FunctionToPointerDecay);
+    } else if (FunctionDecl *Fn
+                 = ResolveAddressOfOverloadedFunction(Arg, ParamType, true)) {
+      if (DiagnoseUseOfDecl(Fn, Arg->getSourceRange().getBegin()))
+        return true;
+
+      Arg = FixOverloadedFunctionReference(Arg, Fn);
+      ArgType = Arg->getType();
+      if (ArgType->isFunctionType() && ParamType->isPointerType()) {
+        ArgType = Context.getPointerType(Arg->getType());
+        ImpCastExprToType(Arg, ArgType, CastExpr::CK_FunctionToPointerDecay);
+      }
+    }
+
+    if (!Context.hasSameUnqualifiedType(ArgType,
+                                        ParamType.getNonReferenceType())) {
+      // We can't perform this conversion.
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_not_convertible)
+        << Arg->getType() << InstantiatedParamType << Arg->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+
+    if (ParamType->isMemberPointerType())
+      return CheckTemplateArgumentPointerToMember(Arg, Converted);
+
+    NamedDecl *Entity = 0;
+    if (CheckTemplateArgumentAddressOfObjectOrFunction(Arg, Entity))
+      return true;
+
+    if (Arg->isValueDependent()) {
+      Converted = TemplateArgument(Arg);
+    } else {
+      if (Entity)
+        Entity = cast<NamedDecl>(Entity->getCanonicalDecl());
+      Converted = TemplateArgument(Entity);
+    }
+    return false;
+  }
+
+  if (ParamType->isPointerType()) {
+    //   -- for a non-type template-parameter of type pointer to
+    //      object, qualification conversions (4.4) and the
+    //      array-to-pointer conversion (4.2) are applied.
+    // C++0x also allows a value of std::nullptr_t.
+    assert(ParamType->getAs<PointerType>()->getPointeeType()->isObjectType() &&
+           "Only object pointers allowed here");
+
+    if (ArgType->isNullPtrType()) {
+      ArgType = ParamType;
+      ImpCastExprToType(Arg, ParamType, CastExpr::CK_BitCast);
+    } else if (ArgType->isArrayType()) {
+      ArgType = Context.getArrayDecayedType(ArgType);
+      ImpCastExprToType(Arg, ArgType, CastExpr::CK_ArrayToPointerDecay);
+    }
+
+    if (IsQualificationConversion(ArgType, ParamType)) {
+      ArgType = ParamType;
+      ImpCastExprToType(Arg, ParamType, CastExpr::CK_NoOp);
+    }
+
+    if (!Context.hasSameUnqualifiedType(ArgType, ParamType)) {
+      // We can't perform this conversion.
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_not_convertible)
+        << Arg->getType() << InstantiatedParamType << Arg->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+
+    NamedDecl *Entity = 0;
+    if (CheckTemplateArgumentAddressOfObjectOrFunction(Arg, Entity))
+      return true;
+
+    if (Arg->isValueDependent()) {
+      Converted = TemplateArgument(Arg);
+    } else {
+      if (Entity)
+        Entity = cast<NamedDecl>(Entity->getCanonicalDecl());
+      Converted = TemplateArgument(Entity);
+    }
+    return false;
+  }
+
+  if (const ReferenceType *ParamRefType = ParamType->getAs<ReferenceType>()) {
+    //   -- For a non-type template-parameter of type reference to
+    //      object, no conversions apply. The type referred to by the
+    //      reference may be more cv-qualified than the (otherwise
+    //      identical) type of the template-argument. The
+    //      template-parameter is bound directly to the
+    //      template-argument, which must be an lvalue.
+    assert(ParamRefType->getPointeeType()->isObjectType() &&
+           "Only object references allowed here");
+
+    QualType ReferredType = ParamRefType->getPointeeType();
+    if (!Context.hasSameUnqualifiedType(ReferredType, ArgType)) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_no_ref_bind)
+        << InstantiatedParamType << Arg->getType()
+        << Arg->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+
+    unsigned ParamQuals
+      = Context.getCanonicalType(ReferredType).getCVRQualifiers();
+    unsigned ArgQuals = Context.getCanonicalType(ArgType).getCVRQualifiers();
+
+    if ((ParamQuals | ArgQuals) != ParamQuals) {
+      Diag(Arg->getSourceRange().getBegin(),
+           diag::err_template_arg_ref_bind_ignores_quals)
+        << InstantiatedParamType << Arg->getType()
+        << Arg->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+
+    NamedDecl *Entity = 0;
+    if (CheckTemplateArgumentAddressOfObjectOrFunction(Arg, Entity))
+      return true;
+
+    if (Arg->isValueDependent()) {
+      Converted = TemplateArgument(Arg);
+    } else {
+      Entity = cast<NamedDecl>(Entity->getCanonicalDecl());
+      Converted = TemplateArgument(Entity);
+    }
+    return false;
+  }
+
+  //     -- For a non-type template-parameter of type pointer to data
+  //        member, qualification conversions (4.4) are applied.
+  // C++0x allows std::nullptr_t values.
+  assert(ParamType->isMemberPointerType() && "Only pointers to members remain");
+
+  if (Context.hasSameUnqualifiedType(ParamType, ArgType)) {
+    // Types match exactly: nothing more to do here.
+  } else if (ArgType->isNullPtrType()) {
+    ImpCastExprToType(Arg, ParamType, CastExpr::CK_NullToMemberPointer);
+  } else if (IsQualificationConversion(ArgType, ParamType)) {
+    ImpCastExprToType(Arg, ParamType, CastExpr::CK_NoOp);
+  } else {
+    // We can't perform this conversion.
+    Diag(Arg->getSourceRange().getBegin(),
+         diag::err_template_arg_not_convertible)
+      << Arg->getType() << InstantiatedParamType << Arg->getSourceRange();
+    Diag(Param->getLocation(), diag::note_template_param_here);
+    return true;
+  }
+
+  return CheckTemplateArgumentPointerToMember(Arg, Converted);
+}
+
+/// \brief Check a template argument against its corresponding
+/// template template parameter.
+///
+/// This routine implements the semantics of C++ [temp.arg.template].
+/// It returns true if an error occurred, and false otherwise.
+bool Sema::CheckTemplateArgument(TemplateTemplateParmDecl *Param,
+                                 const TemplateArgumentLoc &Arg) {
+  TemplateName Name = Arg.getArgument().getAsTemplate();
+  TemplateDecl *Template = Name.getAsTemplateDecl();
+  if (!Template) {
+    // Any dependent template name is fine.
+    assert(Name.isDependent() && "Non-dependent template isn't a declaration?");
+    return false;
+  }
+
+  // C++ [temp.arg.template]p1:
+  //   A template-argument for a template template-parameter shall be
+  //   the name of a class template, expressed as id-expression. Only
+  //   primary class templates are considered when matching the
+  //   template template argument with the corresponding parameter;
+  //   partial specializations are not considered even if their
+  //   parameter lists match that of the template template parameter.
+  //
+  // Note that we also allow template template parameters here, which
+  // will happen when we are dealing with, e.g., class template
+  // partial specializations.
+  if (!isa<ClassTemplateDecl>(Template) &&
+      !isa<TemplateTemplateParmDecl>(Template)) {
+    assert(isa<FunctionTemplateDecl>(Template) &&
+           "Only function templates are possible here");
+    Diag(Arg.getLocation(), diag::err_template_arg_not_class_template);
+    Diag(Template->getLocation(), diag::note_template_arg_refers_here_func)
+      << Template;
+  }
+
+  return !TemplateParameterListsAreEqual(Template->getTemplateParameters(),
+                                         Param->getTemplateParameters(),
+                                         true, 
+                                         TPL_TemplateTemplateArgumentMatch,
+                                         Arg.getLocation());
+}
+
+/// \brief Determine whether the given template parameter lists are
+/// equivalent.
+///
+/// \param New  The new template parameter list, typically written in the
+/// source code as part of a new template declaration.
+///
+/// \param Old  The old template parameter list, typically found via
+/// name lookup of the template declared with this template parameter
+/// list.
+///
+/// \param Complain  If true, this routine will produce a diagnostic if
+/// the template parameter lists are not equivalent.
+///
+/// \param Kind describes how we are to match the template parameter lists.
+///
+/// \param TemplateArgLoc If this source location is valid, then we
+/// are actually checking the template parameter list of a template
+/// argument (New) against the template parameter list of its
+/// corresponding template template parameter (Old). We produce
+/// slightly different diagnostics in this scenario.
+///
+/// \returns True if the template parameter lists are equal, false
+/// otherwise.
+bool
+Sema::TemplateParameterListsAreEqual(TemplateParameterList *New,
+                                     TemplateParameterList *Old,
+                                     bool Complain,
+                                     TemplateParameterListEqualKind Kind,
+                                     SourceLocation TemplateArgLoc) {
+  if (Old->size() != New->size()) {
+    if (Complain) {
+      unsigned NextDiag = diag::err_template_param_list_different_arity;
+      if (TemplateArgLoc.isValid()) {
+        Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
+        NextDiag = diag::note_template_param_list_different_arity;
+      }
+      Diag(New->getTemplateLoc(), NextDiag)
+          << (New->size() > Old->size())
+          << (Kind != TPL_TemplateMatch)
+          << SourceRange(New->getTemplateLoc(), New->getRAngleLoc());
+      Diag(Old->getTemplateLoc(), diag::note_template_prev_declaration)
+        << (Kind != TPL_TemplateMatch)
+        << SourceRange(Old->getTemplateLoc(), Old->getRAngleLoc());
+    }
+
+    return false;
+  }
+
+  for (TemplateParameterList::iterator OldParm = Old->begin(),
+         OldParmEnd = Old->end(), NewParm = New->begin();
+       OldParm != OldParmEnd; ++OldParm, ++NewParm) {
+    if ((*OldParm)->getKind() != (*NewParm)->getKind()) {
+      if (Complain) {
+        unsigned NextDiag = diag::err_template_param_different_kind;
+        if (TemplateArgLoc.isValid()) {
+          Diag(TemplateArgLoc, diag::err_template_arg_template_params_mismatch);
+          NextDiag = diag::note_template_param_different_kind;
+        }
+        Diag((*NewParm)->getLocation(), NextDiag)
+          << (Kind != TPL_TemplateMatch);
+        Diag((*OldParm)->getLocation(), diag::note_template_prev_declaration)
+          << (Kind != TPL_TemplateMatch);
+      }
+      return false;
+    }
+
+    if (isa<TemplateTypeParmDecl>(*OldParm)) {
+      // Okay; all template type parameters are equivalent (since we
+      // know we're at the same index).
+    } else if (NonTypeTemplateParmDecl *OldNTTP
+                 = dyn_cast<NonTypeTemplateParmDecl>(*OldParm)) {
+      // The types of non-type template parameters must agree.
+      NonTypeTemplateParmDecl *NewNTTP
+        = cast<NonTypeTemplateParmDecl>(*NewParm);
+      
+      // If we are matching a template template argument to a template
+      // template parameter and one of the non-type template parameter types
+      // is dependent, then we must wait until template instantiation time
+      // to actually compare the arguments.
+      if (Kind == TPL_TemplateTemplateArgumentMatch &&
+          (OldNTTP->getType()->isDependentType() ||
+           NewNTTP->getType()->isDependentType()))
+        continue;
+      
+      if (Context.getCanonicalType(OldNTTP->getType()) !=
+            Context.getCanonicalType(NewNTTP->getType())) {
+        if (Complain) {
+          unsigned NextDiag = diag::err_template_nontype_parm_different_type;
+          if (TemplateArgLoc.isValid()) {
+            Diag(TemplateArgLoc,
+                 diag::err_template_arg_template_params_mismatch);
+            NextDiag = diag::note_template_nontype_parm_different_type;
+          }
+          Diag(NewNTTP->getLocation(), NextDiag)
+            << NewNTTP->getType()
+            << (Kind != TPL_TemplateMatch);
+          Diag(OldNTTP->getLocation(),
+               diag::note_template_nontype_parm_prev_declaration)
+            << OldNTTP->getType();
+        }
+        return false;
+      }
+    } else {
+      // The template parameter lists of template template
+      // parameters must agree.
+      assert(isa<TemplateTemplateParmDecl>(*OldParm) &&
+             "Only template template parameters handled here");
+      TemplateTemplateParmDecl *OldTTP
+        = cast<TemplateTemplateParmDecl>(*OldParm);
+      TemplateTemplateParmDecl *NewTTP
+        = cast<TemplateTemplateParmDecl>(*NewParm);
+      if (!TemplateParameterListsAreEqual(NewTTP->getTemplateParameters(),
+                                          OldTTP->getTemplateParameters(),
+                                          Complain,
+              (Kind == TPL_TemplateMatch? TPL_TemplateTemplateParmMatch : Kind),
+                                          TemplateArgLoc))
+        return false;
+    }
+  }
+
+  return true;
+}
+
+/// \brief Check whether a template can be declared within this scope.
+///
+/// If the template declaration is valid in this scope, returns
+/// false. Otherwise, issues a diagnostic and returns true.
+bool
+Sema::CheckTemplateDeclScope(Scope *S, TemplateParameterList *TemplateParams) {
+  // Find the nearest enclosing declaration scope.
+  while ((S->getFlags() & Scope::DeclScope) == 0 ||
+         (S->getFlags() & Scope::TemplateParamScope) != 0)
+    S = S->getParent();
+
+  // C++ [temp]p2:
+  //   A template-declaration can appear only as a namespace scope or
+  //   class scope declaration.
+  DeclContext *Ctx = static_cast<DeclContext *>(S->getEntity());
+  if (Ctx && isa<LinkageSpecDecl>(Ctx) &&
+      cast<LinkageSpecDecl>(Ctx)->getLanguage() != LinkageSpecDecl::lang_cxx)
+    return Diag(TemplateParams->getTemplateLoc(), diag::err_template_linkage)
+             << TemplateParams->getSourceRange();
+
+  while (Ctx && isa<LinkageSpecDecl>(Ctx))
+    Ctx = Ctx->getParent();
+
+  if (Ctx && (Ctx->isFileContext() || Ctx->isRecord()))
+    return false;
+
+  return Diag(TemplateParams->getTemplateLoc(),
+              diag::err_template_outside_namespace_or_class_scope)
+    << TemplateParams->getSourceRange();
+}
+
+/// \brief Determine what kind of template specialization the given declaration
+/// is.
+static TemplateSpecializationKind getTemplateSpecializationKind(NamedDecl *D) {
+  if (!D)
+    return TSK_Undeclared;
+  
+  if (CXXRecordDecl *Record = dyn_cast<CXXRecordDecl>(D))
+    return Record->getTemplateSpecializationKind();
+  if (FunctionDecl *Function = dyn_cast<FunctionDecl>(D))
+    return Function->getTemplateSpecializationKind();
+  if (VarDecl *Var = dyn_cast<VarDecl>(D))
+    return Var->getTemplateSpecializationKind();
+  
+  return TSK_Undeclared;
+}
+
+/// \brief Check whether a specialization is well-formed in the current 
+/// context.
+///
+/// This routine determines whether a template specialization can be declared
+/// in the current context (C++ [temp.expl.spec]p2).
+///
+/// \param S the semantic analysis object for which this check is being
+/// performed.
+///
+/// \param Specialized the entity being specialized or instantiated, which
+/// may be a kind of template (class template, function template, etc.) or
+/// a member of a class template (member function, static data member, 
+/// member class).
+///
+/// \param PrevDecl the previous declaration of this entity, if any.
+///
+/// \param Loc the location of the explicit specialization or instantiation of
+/// this entity.
+///
+/// \param IsPartialSpecialization whether this is a partial specialization of
+/// a class template.
+///
+/// \returns true if there was an error that we cannot recover from, false
+/// otherwise.
+static bool CheckTemplateSpecializationScope(Sema &S,
+                                             NamedDecl *Specialized,
+                                             NamedDecl *PrevDecl,
+                                             SourceLocation Loc,
+                                             bool IsPartialSpecialization) {
+  // Keep these "kind" numbers in sync with the %select statements in the
+  // various diagnostics emitted by this routine.
+  int EntityKind = 0;
+  bool isTemplateSpecialization = false;
+  if (isa<ClassTemplateDecl>(Specialized)) {
+    EntityKind = IsPartialSpecialization? 1 : 0;
+    isTemplateSpecialization = true;
+  } else if (isa<FunctionTemplateDecl>(Specialized)) {
+    EntityKind = 2;
+    isTemplateSpecialization = true;
+  } else if (isa<CXXMethodDecl>(Specialized))
+    EntityKind = 3;
+  else if (isa<VarDecl>(Specialized))
+    EntityKind = 4;
+  else if (isa<RecordDecl>(Specialized))
+    EntityKind = 5;
+  else {
+    S.Diag(Loc, diag::err_template_spec_unknown_kind);
+    S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
+    return true;
+  }
+
+  // C++ [temp.expl.spec]p2:
+  //   An explicit specialization shall be declared in the namespace
+  //   of which the template is a member, or, for member templates, in
+  //   the namespace of which the enclosing class or enclosing class
+  //   template is a member. An explicit specialization of a member
+  //   function, member class or static data member of a class
+  //   template shall be declared in the namespace of which the class
+  //   template is a member. Such a declaration may also be a
+  //   definition. If the declaration is not a definition, the
+  //   specialization may be defined later in the name- space in which
+  //   the explicit specialization was declared, or in a namespace
+  //   that encloses the one in which the explicit specialization was
+  //   declared.
+  if (S.CurContext->getLookupContext()->isFunctionOrMethod()) {
+    S.Diag(Loc, diag::err_template_spec_decl_function_scope)
+      << Specialized;
+    return true;
+  }
+
+  if (S.CurContext->isRecord() && !IsPartialSpecialization) {
+    S.Diag(Loc, diag::err_template_spec_decl_class_scope)
+      << Specialized;
+    return true;
+  }
+  
+  // C++ [temp.class.spec]p6:
+  //   A class template partial specialization may be declared or redeclared
+  //   in any namespace scope in which its definition may be defined (14.5.1 
+  //   and 14.5.2).  
+  bool ComplainedAboutScope = false;
+  DeclContext *SpecializedContext 
+    = Specialized->getDeclContext()->getEnclosingNamespaceContext();
+  DeclContext *DC = S.CurContext->getEnclosingNamespaceContext();
+  if ((!PrevDecl || 
+       getTemplateSpecializationKind(PrevDecl) == TSK_Undeclared ||
+       getTemplateSpecializationKind(PrevDecl) == TSK_ImplicitInstantiation)){
+    // There is no prior declaration of this entity, so this
+    // specialization must be in the same context as the template
+    // itself.
+    if (!DC->Equals(SpecializedContext)) {
+      if (isa<TranslationUnitDecl>(SpecializedContext))
+        S.Diag(Loc, diag::err_template_spec_decl_out_of_scope_global)
+        << EntityKind << Specialized;
+      else if (isa<NamespaceDecl>(SpecializedContext))
+        S.Diag(Loc, diag::err_template_spec_decl_out_of_scope)
+        << EntityKind << Specialized
+        << cast<NamedDecl>(SpecializedContext);
+      
+      S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
+      ComplainedAboutScope = true;
+    }
+  }
+  
+  // Make sure that this redeclaration (or definition) occurs in an enclosing 
+  // namespace.
+  // Note that HandleDeclarator() performs this check for explicit 
+  // specializations of function templates, static data members, and member
+  // functions, so we skip the check here for those kinds of entities.
+  // FIXME: HandleDeclarator's diagnostics aren't quite as good, though.
+  // Should we refactor that check, so that it occurs later?
+  if (!ComplainedAboutScope && !DC->Encloses(SpecializedContext) &&
+      !(isa<FunctionTemplateDecl>(Specialized) || isa<VarDecl>(Specialized) ||
+        isa<FunctionDecl>(Specialized))) {
+    if (isa<TranslationUnitDecl>(SpecializedContext))
+      S.Diag(Loc, diag::err_template_spec_redecl_global_scope)
+        << EntityKind << Specialized;
+    else if (isa<NamespaceDecl>(SpecializedContext))
+      S.Diag(Loc, diag::err_template_spec_redecl_out_of_scope)
+        << EntityKind << Specialized
+        << cast<NamedDecl>(SpecializedContext);
+  
+    S.Diag(Specialized->getLocation(), diag::note_specialized_entity);
+  }
+  
+  // FIXME: check for specialization-after-instantiation errors and such.
+  
+  return false;
+}
+                                             
+/// \brief Check the non-type template arguments of a class template
+/// partial specialization according to C++ [temp.class.spec]p9.
+///
+/// \param TemplateParams the template parameters of the primary class
+/// template.
+///
+/// \param TemplateArg the template arguments of the class template
+/// partial specialization.
+///
+/// \param MirrorsPrimaryTemplate will be set true if the class
+/// template partial specialization arguments are identical to the
+/// implicit template arguments of the primary template. This is not
+/// necessarily an error (C++0x), and it is left to the caller to diagnose
+/// this condition when it is an error.
+///
+/// \returns true if there was an error, false otherwise.
+bool Sema::CheckClassTemplatePartialSpecializationArgs(
+                                        TemplateParameterList *TemplateParams,
+                             const TemplateArgumentListBuilder &TemplateArgs,
+                                        bool &MirrorsPrimaryTemplate) {
+  // FIXME: the interface to this function will have to change to
+  // accommodate variadic templates.
+  MirrorsPrimaryTemplate = true;
+
+  const TemplateArgument *ArgList = TemplateArgs.getFlatArguments();
+
+  for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
+    // Determine whether the template argument list of the partial
+    // specialization is identical to the implicit argument list of
+    // the primary template. The caller may need to diagnostic this as
+    // an error per C++ [temp.class.spec]p9b3.
+    if (MirrorsPrimaryTemplate) {
+      if (TemplateTypeParmDecl *TTP
+            = dyn_cast<TemplateTypeParmDecl>(TemplateParams->getParam(I))) {
+        if (Context.getCanonicalType(Context.getTypeDeclType(TTP)) !=
+              Context.getCanonicalType(ArgList[I].getAsType()))
+          MirrorsPrimaryTemplate = false;
+      } else if (TemplateTemplateParmDecl *TTP
+                   = dyn_cast<TemplateTemplateParmDecl>(
+                                                 TemplateParams->getParam(I))) {
+        TemplateName Name = ArgList[I].getAsTemplate();
+        TemplateTemplateParmDecl *ArgDecl
+          = dyn_cast_or_null<TemplateTemplateParmDecl>(Name.getAsTemplateDecl());
+        if (!ArgDecl ||
+            ArgDecl->getIndex() != TTP->getIndex() ||
+            ArgDecl->getDepth() != TTP->getDepth())
+          MirrorsPrimaryTemplate = false;
+      }
+    }
+
+    NonTypeTemplateParmDecl *Param
+      = dyn_cast<NonTypeTemplateParmDecl>(TemplateParams->getParam(I));
+    if (!Param) {
+      continue;
+    }
+
+    Expr *ArgExpr = ArgList[I].getAsExpr();
+    if (!ArgExpr) {
+      MirrorsPrimaryTemplate = false;
+      continue;
+    }
+
+    // C++ [temp.class.spec]p8:
+    //   A non-type argument is non-specialized if it is the name of a
+    //   non-type parameter. All other non-type arguments are
+    //   specialized.
+    //
+    // Below, we check the two conditions that only apply to
+    // specialized non-type arguments, so skip any non-specialized
+    // arguments.
+    if (DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(ArgExpr))
+      if (NonTypeTemplateParmDecl *NTTP
+            = dyn_cast<NonTypeTemplateParmDecl>(DRE->getDecl())) {
+        if (MirrorsPrimaryTemplate &&
+            (Param->getIndex() != NTTP->getIndex() ||
+             Param->getDepth() != NTTP->getDepth()))
+          MirrorsPrimaryTemplate = false;
+
+        continue;
+      }
+
+    // C++ [temp.class.spec]p9:
+    //   Within the argument list of a class template partial
+    //   specialization, the following restrictions apply:
+    //     -- A partially specialized non-type argument expression
+    //        shall not involve a template parameter of the partial
+    //        specialization except when the argument expression is a
+    //        simple identifier.
+    if (ArgExpr->isTypeDependent() || ArgExpr->isValueDependent()) {
+      Diag(ArgExpr->getLocStart(),
+           diag::err_dependent_non_type_arg_in_partial_spec)
+        << ArgExpr->getSourceRange();
+      return true;
+    }
+
+    //     -- The type of a template parameter corresponding to a
+    //        specialized non-type argument shall not be dependent on a
+    //        parameter of the specialization.
+    if (Param->getType()->isDependentType()) {
+      Diag(ArgExpr->getLocStart(),
+           diag::err_dependent_typed_non_type_arg_in_partial_spec)
+        << Param->getType()
+        << ArgExpr->getSourceRange();
+      Diag(Param->getLocation(), diag::note_template_param_here);
+      return true;
+    }
+
+    MirrorsPrimaryTemplate = false;
+  }
+
+  return false;
+}
+
+Sema::DeclResult
+Sema::ActOnClassTemplateSpecialization(Scope *S, unsigned TagSpec,
+                                       TagUseKind TUK,
+                                       SourceLocation KWLoc,
+                                       const CXXScopeSpec &SS,
+                                       TemplateTy TemplateD,
+                                       SourceLocation TemplateNameLoc,
+                                       SourceLocation LAngleLoc,
+                                       ASTTemplateArgsPtr TemplateArgsIn,
+                                       SourceLocation RAngleLoc,
+                                       AttributeList *Attr,
+                               MultiTemplateParamsArg TemplateParameterLists) {
+  assert(TUK != TUK_Reference && "References are not specializations");
+
+  // Find the class template we're specializing
+  TemplateName Name = TemplateD.getAsVal<TemplateName>();
+  ClassTemplateDecl *ClassTemplate
+    = dyn_cast_or_null<ClassTemplateDecl>(Name.getAsTemplateDecl());
+
+  if (!ClassTemplate) {
+    Diag(TemplateNameLoc, diag::err_not_class_template_specialization)
+      << (Name.getAsTemplateDecl() && 
+          isa<TemplateTemplateParmDecl>(Name.getAsTemplateDecl()));
+    return true;
+  }
+
+  bool isExplicitSpecialization = false;
+  bool isPartialSpecialization = false;
+
+  // Check the validity of the template headers that introduce this
+  // template.
+  // FIXME: We probably shouldn't complain about these headers for
+  // friend declarations.
+  TemplateParameterList *TemplateParams
+    = MatchTemplateParametersToScopeSpecifier(TemplateNameLoc, SS,
+                        (TemplateParameterList**)TemplateParameterLists.get(),
+                                              TemplateParameterLists.size(),
+                                              isExplicitSpecialization);
+  if (TemplateParams && TemplateParams->size() > 0) {
+    isPartialSpecialization = true;
+
+    // C++ [temp.class.spec]p10:
+    //   The template parameter list of a specialization shall not
+    //   contain default template argument values.
+    for (unsigned I = 0, N = TemplateParams->size(); I != N; ++I) {
+      Decl *Param = TemplateParams->getParam(I);
+      if (TemplateTypeParmDecl *TTP = dyn_cast<TemplateTypeParmDecl>(Param)) {
+        if (TTP->hasDefaultArgument()) {
+          Diag(TTP->getDefaultArgumentLoc(),
+               diag::err_default_arg_in_partial_spec);
+          TTP->removeDefaultArgument();
+        }
+      } else if (NonTypeTemplateParmDecl *NTTP
+                   = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
+        if (Expr *DefArg = NTTP->getDefaultArgument()) {
+          Diag(NTTP->getDefaultArgumentLoc(),
+               diag::err_default_arg_in_partial_spec)
+            << DefArg->getSourceRange();
+          NTTP->setDefaultArgument(0);
+          DefArg->Destroy(Context);
+        }
+      } else {
+        TemplateTemplateParmDecl *TTP = cast<TemplateTemplateParmDecl>(Param);
+        if (TTP->hasDefaultArgument()) {
+          Diag(TTP->getDefaultArgument().getLocation(),
+               diag::err_default_arg_in_partial_spec)
+            << TTP->getDefaultArgument().getSourceRange();
+          TTP->setDefaultArgument(TemplateArgumentLoc());
+        }
+      }
+    }
+  } else if (TemplateParams) {
+    if (TUK == TUK_Friend)
+      Diag(KWLoc, diag::err_template_spec_friend)
+        << CodeModificationHint::CreateRemoval(
+                                SourceRange(TemplateParams->getTemplateLoc(),
+                                            TemplateParams->getRAngleLoc()))
+        << SourceRange(LAngleLoc, RAngleLoc);
+    else
+      isExplicitSpecialization = true;
+  } else if (TUK != TUK_Friend) {
+    Diag(KWLoc, diag::err_template_spec_needs_header)
+      << CodeModificationHint::CreateInsertion(KWLoc, "template<> ");
+    isExplicitSpecialization = true;
+  }
+
+  // Check that the specialization uses the same tag kind as the
+  // original template.
+  TagDecl::TagKind Kind;
+  switch (TagSpec) {
+  default: assert(0 && "Unknown tag type!");
+  case DeclSpec::TST_struct: Kind = TagDecl::TK_struct; break;
+  case DeclSpec::TST_union:  Kind = TagDecl::TK_union; break;
+  case DeclSpec::TST_class:  Kind = TagDecl::TK_class; break;
+  }
+  if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(),
+                                    Kind, KWLoc,
+                                    *ClassTemplate->getIdentifier())) {
+    Diag(KWLoc, diag::err_use_with_wrong_tag)
+      << ClassTemplate
+      << CodeModificationHint::CreateReplacement(KWLoc,
+                            ClassTemplate->getTemplatedDecl()->getKindName());
+    Diag(ClassTemplate->getTemplatedDecl()->getLocation(),
+         diag::note_previous_use);
+    Kind = ClassTemplate->getTemplatedDecl()->getTagKind();
+  }
+
+  // Translate the parser's template argument list in our AST format.
+  TemplateArgumentListInfo TemplateArgs;
+  TemplateArgs.setLAngleLoc(LAngleLoc);
+  TemplateArgs.setRAngleLoc(RAngleLoc);
+  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
+
+  // Check that the template argument list is well-formed for this
+  // template.
+  TemplateArgumentListBuilder Converted(ClassTemplate->getTemplateParameters(),
+                                        TemplateArgs.size());
+  if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc,
+                                TemplateArgs, false, Converted))
+    return true;
+
+  assert((Converted.structuredSize() ==
+            ClassTemplate->getTemplateParameters()->size()) &&
+         "Converted template argument list is too short!");
+
+  // Find the class template (partial) specialization declaration that
+  // corresponds to these arguments.
+  llvm::FoldingSetNodeID ID;
+  if (isPartialSpecialization) {
+    bool MirrorsPrimaryTemplate;
+    if (CheckClassTemplatePartialSpecializationArgs(
+                                         ClassTemplate->getTemplateParameters(),
+                                         Converted, MirrorsPrimaryTemplate))
+      return true;
+
+    if (MirrorsPrimaryTemplate) {
+      // C++ [temp.class.spec]p9b3:
+      //
+      //   -- The argument list of the specialization shall not be identical
+      //      to the implicit argument list of the primary template.
+      Diag(TemplateNameLoc, diag::err_partial_spec_args_match_primary_template)
+        << (TUK == TUK_Definition)
+        << CodeModificationHint::CreateRemoval(SourceRange(LAngleLoc,
+                                                           RAngleLoc));
+      return CheckClassTemplate(S, TagSpec, TUK, KWLoc, SS,
+                                ClassTemplate->getIdentifier(),
+                                TemplateNameLoc,
+                                Attr,
+                                TemplateParams,
+                                AS_none);
+    }
+
+    // FIXME: Diagnose friend partial specializations
+
+    if (!Name.isDependent() && 
+        !TemplateSpecializationType::anyDependentTemplateArguments(
+                                             TemplateArgs.getArgumentArray(), 
+                                                         TemplateArgs.size())) {
+      Diag(TemplateNameLoc, diag::err_partial_spec_fully_specialized)
+        << ClassTemplate->getDeclName();
+      isPartialSpecialization = false;
+    } else {
+      // FIXME: Template parameter list matters, too
+      ClassTemplatePartialSpecializationDecl::Profile(ID,
+                                                  Converted.getFlatArguments(),
+                                                      Converted.flatSize(),
+                                                      Context);
+    }
+  }
+  
+  if (!isPartialSpecialization)
+    ClassTemplateSpecializationDecl::Profile(ID,
+                                             Converted.getFlatArguments(),
+                                             Converted.flatSize(),
+                                             Context);
+  void *InsertPos = 0;
+  ClassTemplateSpecializationDecl *PrevDecl = 0;
+
+  if (isPartialSpecialization)
+    PrevDecl
+      = ClassTemplate->getPartialSpecializations().FindNodeOrInsertPos(ID,
+                                                                    InsertPos);
+  else
+    PrevDecl
+      = ClassTemplate->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
+
+  ClassTemplateSpecializationDecl *Specialization = 0;
+
+  // Check whether we can declare a class template specialization in
+  // the current scope.
+  if (TUK != TUK_Friend &&
+      CheckTemplateSpecializationScope(*this, ClassTemplate, PrevDecl, 
+                                       TemplateNameLoc, 
+                                       isPartialSpecialization))
+    return true;
+  
+  // The canonical type
+  QualType CanonType;
+  if (PrevDecl && 
+      (PrevDecl->getSpecializationKind() == TSK_Undeclared ||
+               TUK == TUK_Friend)) {
+    // Since the only prior class template specialization with these
+    // arguments was referenced but not declared, or we're only
+    // referencing this specialization as a friend, reuse that
+    // declaration node as our own, updating its source location to
+    // reflect our new declaration.
+    Specialization = PrevDecl;
+    Specialization->setLocation(TemplateNameLoc);
+    PrevDecl = 0;
+    CanonType = Context.getTypeDeclType(Specialization);
+  } else if (isPartialSpecialization) {
+    // Build the canonical type that describes the converted template
+    // arguments of the class template partial specialization.
+    TemplateName CanonTemplate = Context.getCanonicalTemplateName(Name);
+    CanonType = Context.getTemplateSpecializationType(CanonTemplate,
+                                                  Converted.getFlatArguments(),
+                                                  Converted.flatSize());
+
+    // Create a new class template partial specialization declaration node.
+    ClassTemplatePartialSpecializationDecl *PrevPartial
+      = cast_or_null<ClassTemplatePartialSpecializationDecl>(PrevDecl);
+    ClassTemplatePartialSpecializationDecl *Partial
+      = ClassTemplatePartialSpecializationDecl::Create(Context,
+                                             ClassTemplate->getDeclContext(),
+                                                       TemplateNameLoc,
+                                                       TemplateParams,
+                                                       ClassTemplate,
+                                                       Converted,
+                                                       TemplateArgs,
+                                                       PrevPartial);
+
+    if (PrevPartial) {
+      ClassTemplate->getPartialSpecializations().RemoveNode(PrevPartial);
+      ClassTemplate->getPartialSpecializations().GetOrInsertNode(Partial);
+    } else {
+      ClassTemplate->getPartialSpecializations().InsertNode(Partial, InsertPos);
+    }
+    Specialization = Partial;
+
+    // If we are providing an explicit specialization of a member class 
+    // template specialization, make a note of that.
+    if (PrevPartial && PrevPartial->getInstantiatedFromMember())
+      PrevPartial->setMemberSpecialization();
+    
+    // Check that all of the template parameters of the class template
+    // partial specialization are deducible from the template
+    // arguments. If not, this class template partial specialization
+    // will never be used.
+    llvm::SmallVector<bool, 8> DeducibleParams;
+    DeducibleParams.resize(TemplateParams->size());
+    MarkUsedTemplateParameters(Partial->getTemplateArgs(), true, 
+                               TemplateParams->getDepth(),
+                               DeducibleParams);
+    unsigned NumNonDeducible = 0;
+    for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I)
+      if (!DeducibleParams[I])
+        ++NumNonDeducible;
+
+    if (NumNonDeducible) {
+      Diag(TemplateNameLoc, diag::warn_partial_specs_not_deducible)
+        << (NumNonDeducible > 1)
+        << SourceRange(TemplateNameLoc, RAngleLoc);
+      for (unsigned I = 0, N = DeducibleParams.size(); I != N; ++I) {
+        if (!DeducibleParams[I]) {
+          NamedDecl *Param = cast<NamedDecl>(TemplateParams->getParam(I));
+          if (Param->getDeclName())
+            Diag(Param->getLocation(),
+                 diag::note_partial_spec_unused_parameter)
+              << Param->getDeclName();
+          else
+            Diag(Param->getLocation(),
+                 diag::note_partial_spec_unused_parameter)
+              << std::string("<anonymous>");
+        }
+      }
+    }
+  } else {
+    // Create a new class template specialization declaration node for
+    // this explicit specialization or friend declaration.
+    Specialization
+      = ClassTemplateSpecializationDecl::Create(Context,
+                                             ClassTemplate->getDeclContext(),
+                                                TemplateNameLoc,
+                                                ClassTemplate,
+                                                Converted,
+                                                PrevDecl);
+
+    if (PrevDecl) {
+      ClassTemplate->getSpecializations().RemoveNode(PrevDecl);
+      ClassTemplate->getSpecializations().GetOrInsertNode(Specialization);
+    } else {
+      ClassTemplate->getSpecializations().InsertNode(Specialization,
+                                                     InsertPos);
+    }
+
+    CanonType = Context.getTypeDeclType(Specialization);
+  }
+
+  // C++ [temp.expl.spec]p6:
+  //   If a template, a member template or the member of a class template is
+  //   explicitly specialized then that specialization shall be declared 
+  //   before the first use of that specialization that would cause an implicit
+  //   instantiation to take place, in every translation unit in which such a 
+  //   use occurs; no diagnostic is required.
+  if (PrevDecl && PrevDecl->getPointOfInstantiation().isValid()) {
+    SourceRange Range(TemplateNameLoc, RAngleLoc);
+    Diag(TemplateNameLoc, diag::err_specialization_after_instantiation)
+      << Context.getTypeDeclType(Specialization) << Range;
+
+    Diag(PrevDecl->getPointOfInstantiation(), 
+         diag::note_instantiation_required_here)
+      << (PrevDecl->getTemplateSpecializationKind() 
+                                                != TSK_ImplicitInstantiation);
+    return true;
+  }
+  
+  // If this is not a friend, note that this is an explicit specialization.
+  if (TUK != TUK_Friend)
+    Specialization->setSpecializationKind(TSK_ExplicitSpecialization);
+
+  // Check that this isn't a redefinition of this specialization.
+  if (TUK == TUK_Definition) {
+    if (RecordDecl *Def = Specialization->getDefinition(Context)) {
+      SourceRange Range(TemplateNameLoc, RAngleLoc);
+      Diag(TemplateNameLoc, diag::err_redefinition)
+        << Context.getTypeDeclType(Specialization) << Range;
+      Diag(Def->getLocation(), diag::note_previous_definition);
+      Specialization->setInvalidDecl();
+      return true;
+    }
+  }
+
+  // Build the fully-sugared type for this class template
+  // specialization as the user wrote in the specialization
+  // itself. This means that we'll pretty-print the type retrieved
+  // from the specialization's declaration the way that the user
+  // actually wrote the specialization, rather than formatting the
+  // name based on the "canonical" representation used to store the
+  // template arguments in the specialization.
+  QualType WrittenTy
+    = Context.getTemplateSpecializationType(Name, TemplateArgs, CanonType);
+  if (TUK != TUK_Friend)
+    Specialization->setTypeAsWritten(WrittenTy);
+  TemplateArgsIn.release();
+
+  // C++ [temp.expl.spec]p9:
+  //   A template explicit specialization is in the scope of the
+  //   namespace in which the template was defined.
+  //
+  // We actually implement this paragraph where we set the semantic
+  // context (in the creation of the ClassTemplateSpecializationDecl),
+  // but we also maintain the lexical context where the actual
+  // definition occurs.
+  Specialization->setLexicalDeclContext(CurContext);
+
+  // We may be starting the definition of this specialization.
+  if (TUK == TUK_Definition)
+    Specialization->startDefinition();
+
+  if (TUK == TUK_Friend) {
+    FriendDecl *Friend = FriendDecl::Create(Context, CurContext,
+                                            TemplateNameLoc,
+                                            WrittenTy.getTypePtr(),
+                                            /*FIXME:*/KWLoc);
+    Friend->setAccess(AS_public);
+    CurContext->addDecl(Friend);
+  } else {
+    // Add the specialization into its lexical context, so that it can
+    // be seen when iterating through the list of declarations in that
+    // context. However, specializations are not found by name lookup.
+    CurContext->addDecl(Specialization);
+  }
+  return DeclPtrTy::make(Specialization);
+}
+
+Sema::DeclPtrTy
+Sema::ActOnTemplateDeclarator(Scope *S,
+                              MultiTemplateParamsArg TemplateParameterLists,
+                              Declarator &D) {
+  return HandleDeclarator(S, D, move(TemplateParameterLists), false);
+}
+
+Sema::DeclPtrTy
+Sema::ActOnStartOfFunctionTemplateDef(Scope *FnBodyScope,
+                               MultiTemplateParamsArg TemplateParameterLists,
+                                      Declarator &D) {
+  assert(getCurFunctionDecl() == 0 && "Function parsing confused");
+  assert(D.getTypeObject(0).Kind == DeclaratorChunk::Function &&
+         "Not a function declarator!");
+  DeclaratorChunk::FunctionTypeInfo &FTI = D.getTypeObject(0).Fun;
+
+  if (FTI.hasPrototype) {
+    // FIXME: Diagnose arguments without names in C.
+  }
+
+  Scope *ParentScope = FnBodyScope->getParent();
+
+  DeclPtrTy DP = HandleDeclarator(ParentScope, D,
+                                  move(TemplateParameterLists),
+                                  /*IsFunctionDefinition=*/true);
+  if (FunctionTemplateDecl *FunctionTemplate
+        = dyn_cast_or_null<FunctionTemplateDecl>(DP.getAs<Decl>()))
+    return ActOnStartOfFunctionDef(FnBodyScope,
+                      DeclPtrTy::make(FunctionTemplate->getTemplatedDecl()));
+  if (FunctionDecl *Function = dyn_cast_or_null<FunctionDecl>(DP.getAs<Decl>()))
+    return ActOnStartOfFunctionDef(FnBodyScope, DeclPtrTy::make(Function));
+  return DeclPtrTy();
+}
+
+/// \brief Diagnose cases where we have an explicit template specialization 
+/// before/after an explicit template instantiation, producing diagnostics
+/// for those cases where they are required and determining whether the 
+/// new specialization/instantiation will have any effect.
+///
+/// \param NewLoc the location of the new explicit specialization or 
+/// instantiation.
+///
+/// \param NewTSK the kind of the new explicit specialization or instantiation.
+///
+/// \param PrevDecl the previous declaration of the entity.
+///
+/// \param PrevTSK the kind of the old explicit specialization or instantiatin.
+///
+/// \param PrevPointOfInstantiation if valid, indicates where the previus 
+/// declaration was instantiated (either implicitly or explicitly).
+///
+/// \param SuppressNew will be set to true to indicate that the new 
+/// specialization or instantiation has no effect and should be ignored.
+///
+/// \returns true if there was an error that should prevent the introduction of
+/// the new declaration into the AST, false otherwise.
+bool
+Sema::CheckSpecializationInstantiationRedecl(SourceLocation NewLoc,
+                                             TemplateSpecializationKind NewTSK,
+                                             NamedDecl *PrevDecl,
+                                             TemplateSpecializationKind PrevTSK,
+                                        SourceLocation PrevPointOfInstantiation,
+                                             bool &SuppressNew) {
+  SuppressNew = false;
+  
+  switch (NewTSK) {
+  case TSK_Undeclared:
+  case TSK_ImplicitInstantiation:
+    assert(false && "Don't check implicit instantiations here");
+    return false;
+    
+  case TSK_ExplicitSpecialization:
+    switch (PrevTSK) {
+    case TSK_Undeclared:
+    case TSK_ExplicitSpecialization:
+      // Okay, we're just specializing something that is either already 
+      // explicitly specialized or has merely been mentioned without any
+      // instantiation.
+      return false;
+
+    case TSK_ImplicitInstantiation:
+      if (PrevPointOfInstantiation.isInvalid()) {
+        // The declaration itself has not actually been instantiated, so it is
+        // still okay to specialize it.
+        return false;
+      }
+      // Fall through
+        
+    case TSK_ExplicitInstantiationDeclaration:
+    case TSK_ExplicitInstantiationDefinition:
+      assert((PrevTSK == TSK_ImplicitInstantiation || 
+              PrevPointOfInstantiation.isValid()) && 
+             "Explicit instantiation without point of instantiation?");
+        
+      // C++ [temp.expl.spec]p6:
+      //   If a template, a member template or the member of a class template 
+      //   is explicitly specialized then that specialization shall be declared
+      //   before the first use of that specialization that would cause an 
+      //   implicit instantiation to take place, in every translation unit in
+      //   which such a use occurs; no diagnostic is required.
+      Diag(NewLoc, diag::err_specialization_after_instantiation)
+        << PrevDecl;
+      Diag(PrevPointOfInstantiation, diag::note_instantiation_required_here)
+        << (PrevTSK != TSK_ImplicitInstantiation);
+      
+      return true;
+    }
+    break;
+      
+  case TSK_ExplicitInstantiationDeclaration:
+    switch (PrevTSK) {
+    case TSK_ExplicitInstantiationDeclaration:
+      // This explicit instantiation declaration is redundant (that's okay).
+      SuppressNew = true;
+      return false;
+        
+    case TSK_Undeclared:
+    case TSK_ImplicitInstantiation:
+      // We're explicitly instantiating something that may have already been
+      // implicitly instantiated; that's fine.
+      return false;
+        
+    case TSK_ExplicitSpecialization:
+      // C++0x [temp.explicit]p4:
+      //   For a given set of template parameters, if an explicit instantiation
+      //   of a template appears after a declaration of an explicit 
+      //   specialization for that template, the explicit instantiation has no
+      //   effect.
+      return false;
+        
+    case TSK_ExplicitInstantiationDefinition:
+      // C++0x [temp.explicit]p10:
+      //   If an entity is the subject of both an explicit instantiation 
+      //   declaration and an explicit instantiation definition in the same 
+      //   translation unit, the definition shall follow the declaration.
+      Diag(NewLoc, 
+           diag::err_explicit_instantiation_declaration_after_definition);
+      Diag(PrevPointOfInstantiation, 
+           diag::note_explicit_instantiation_definition_here);
+      assert(PrevPointOfInstantiation.isValid() &&
+             "Explicit instantiation without point of instantiation?");
+      SuppressNew = true;
+      return false;
+    }
+    break;
+      
+  case TSK_ExplicitInstantiationDefinition:
+    switch (PrevTSK) {
+    case TSK_Undeclared:
+    case TSK_ImplicitInstantiation:
+      // We're explicitly instantiating something that may have already been
+      // implicitly instantiated; that's fine.
+      return false;
+        
+    case TSK_ExplicitSpecialization:
+      // C++ DR 259, C++0x [temp.explicit]p4:
+      //   For a given set of template parameters, if an explicit
+      //   instantiation of a template appears after a declaration of
+      //   an explicit specialization for that template, the explicit
+      //   instantiation has no effect.
+      //
+      // In C++98/03 mode, we only give an extension warning here, because it 
+      // is not not harmful to try to explicitly instantiate something that
+      // has been explicitly specialized.
+      if (!getLangOptions().CPlusPlus0x) {
+        Diag(NewLoc, diag::ext_explicit_instantiation_after_specialization)
+          << PrevDecl;
+        Diag(PrevDecl->getLocation(),
+             diag::note_previous_template_specialization);
+      }
+      SuppressNew = true;
+      return false;
+        
+    case TSK_ExplicitInstantiationDeclaration:
+      // We're explicity instantiating a definition for something for which we
+      // were previously asked to suppress instantiations. That's fine. 
+      return false;
+        
+    case TSK_ExplicitInstantiationDefinition:
+      // C++0x [temp.spec]p5:
+      //   For a given template and a given set of template-arguments,
+      //     - an explicit instantiation definition shall appear at most once
+      //       in a program,
+      Diag(NewLoc, diag::err_explicit_instantiation_duplicate)
+        << PrevDecl;
+      Diag(PrevPointOfInstantiation, 
+           diag::note_previous_explicit_instantiation);
+      SuppressNew = true;
+      return false;        
+    }
+    break;
+  }
+  
+  assert(false && "Missing specialization/instantiation case?");
+         
+  return false;
+}
+
+/// \brief Perform semantic analysis for the given function template 
+/// specialization.
+///
+/// This routine performs all of the semantic analysis required for an 
+/// explicit function template specialization. On successful completion,
+/// the function declaration \p FD will become a function template
+/// specialization.
+///
+/// \param FD the function declaration, which will be updated to become a
+/// function template specialization.
+///
+/// \param HasExplicitTemplateArgs whether any template arguments were
+/// explicitly provided.
+///
+/// \param LAngleLoc the location of the left angle bracket ('<'), if
+/// template arguments were explicitly provided.
+///
+/// \param ExplicitTemplateArgs the explicitly-provided template arguments, 
+/// if any.
+///
+/// \param NumExplicitTemplateArgs the number of explicitly-provided template
+/// arguments. This number may be zero even when HasExplicitTemplateArgs is
+/// true as in, e.g., \c void sort<>(char*, char*);
+///
+/// \param RAngleLoc the location of the right angle bracket ('>'), if
+/// template arguments were explicitly provided.
+/// 
+/// \param PrevDecl the set of declarations that 
+bool 
+Sema::CheckFunctionTemplateSpecialization(FunctionDecl *FD,
+                        const TemplateArgumentListInfo *ExplicitTemplateArgs,
+                                          LookupResult &Previous) {
+  // The set of function template specializations that could match this
+  // explicit function template specialization.
+  UnresolvedSet<8> Candidates;
+  
+  DeclContext *FDLookupContext = FD->getDeclContext()->getLookupContext();
+  for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
+         I != E; ++I) {
+    NamedDecl *Ovl = (*I)->getUnderlyingDecl();
+    if (FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(Ovl)) {
+      // Only consider templates found within the same semantic lookup scope as 
+      // FD.
+      if (!FDLookupContext->Equals(Ovl->getDeclContext()->getLookupContext()))
+        continue;
+      
+      // C++ [temp.expl.spec]p11:
+      //   A trailing template-argument can be left unspecified in the 
+      //   template-id naming an explicit function template specialization 
+      //   provided it can be deduced from the function argument type.
+      // Perform template argument deduction to determine whether we may be
+      // specializing this template.
+      // FIXME: It is somewhat wasteful to build
+      TemplateDeductionInfo Info(Context, FD->getLocation());
+      FunctionDecl *Specialization = 0;
+      if (TemplateDeductionResult TDK
+            = DeduceTemplateArguments(FunTmpl, ExplicitTemplateArgs,
+                                      FD->getType(),
+                                      Specialization,
+                                      Info)) {
+        // FIXME: Template argument deduction failed; record why it failed, so
+        // that we can provide nifty diagnostics.
+        (void)TDK;
+        continue;
+      }
+      
+      // Record this candidate.
+      Candidates.addDecl(Specialization, I.getAccess());
+    }
+  }
+  
+  // Find the most specialized function template.
+  UnresolvedSetIterator Result
+    = getMostSpecialized(Candidates.begin(), Candidates.end(),
+                         TPOC_Other, FD->getLocation(),
+                  PartialDiagnostic(diag::err_function_template_spec_no_match) 
+                    << FD->getDeclName(),
+                  PartialDiagnostic(diag::err_function_template_spec_ambiguous)
+                    << FD->getDeclName() << (ExplicitTemplateArgs != 0),
+                  PartialDiagnostic(diag::note_function_template_spec_matched));
+  if (Result == Candidates.end())
+    return true;
+
+  // Ignore access information;  it doesn't figure into redeclaration checking.
+  FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
+  
+  // FIXME: Check if the prior specialization has a point of instantiation.
+  // If so, we have run afoul of .
+  
+  // Check the scope of this explicit specialization.
+  if (CheckTemplateSpecializationScope(*this, 
+                                       Specialization->getPrimaryTemplate(),
+                                       Specialization, FD->getLocation(), 
+                                       false))
+    return true;
+
+  // C++ [temp.expl.spec]p6:
+  //   If a template, a member template or the member of a class template is
+  //   explicitly specialized then that specialization shall be declared 
+  //   before the first use of that specialization that would cause an implicit
+  //   instantiation to take place, in every translation unit in which such a 
+  //   use occurs; no diagnostic is required.
+  FunctionTemplateSpecializationInfo *SpecInfo
+    = Specialization->getTemplateSpecializationInfo();
+  assert(SpecInfo && "Function template specialization info missing?");
+  if (SpecInfo->getPointOfInstantiation().isValid()) {
+    Diag(FD->getLocation(), diag::err_specialization_after_instantiation)
+      << FD;
+    Diag(SpecInfo->getPointOfInstantiation(), 
+         diag::note_instantiation_required_here)
+      << (Specialization->getTemplateSpecializationKind() 
+                                                != TSK_ImplicitInstantiation);
+    return true;
+  }
+  
+  // Mark the prior declaration as an explicit specialization, so that later
+  // clients know that this is an explicit specialization.
+  SpecInfo->setTemplateSpecializationKind(TSK_ExplicitSpecialization);
+  
+  // Turn the given function declaration into a function template
+  // specialization, with the template arguments from the previous
+  // specialization.
+  FD->setFunctionTemplateSpecialization(Context, 
+                                        Specialization->getPrimaryTemplate(),
+                         new (Context) TemplateArgumentList(
+                             *Specialization->getTemplateSpecializationArgs()), 
+                                        /*InsertPos=*/0, 
+                                        TSK_ExplicitSpecialization);
+  
+  // The "previous declaration" for this function template specialization is
+  // the prior function template specialization.
+  Previous.clear();
+  Previous.addDecl(Specialization);
+  return false;
+}
+
+/// \brief Perform semantic analysis for the given non-template member
+/// specialization.
+///
+/// This routine performs all of the semantic analysis required for an 
+/// explicit member function specialization. On successful completion,
+/// the function declaration \p FD will become a member function
+/// specialization.
+///
+/// \param Member the member declaration, which will be updated to become a
+/// specialization.
+///
+/// \param Previous the set of declarations, one of which may be specialized
+/// by this function specialization;  the set will be modified to contain the
+/// redeclared member.
+bool 
+Sema::CheckMemberSpecialization(NamedDecl *Member, LookupResult &Previous) {
+  assert(!isa<TemplateDecl>(Member) && "Only for non-template members");
+         
+  // Try to find the member we are instantiating.
+  NamedDecl *Instantiation = 0;
+  NamedDecl *InstantiatedFrom = 0;
+  MemberSpecializationInfo *MSInfo = 0;
+
+  if (Previous.empty()) {
+    // Nowhere to look anyway.
+  } else if (FunctionDecl *Function = dyn_cast<FunctionDecl>(Member)) {
+    for (LookupResult::iterator I = Previous.begin(), E = Previous.end();
+           I != E; ++I) {
+      NamedDecl *D = (*I)->getUnderlyingDecl();
+      if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(D)) {
+        if (Context.hasSameType(Function->getType(), Method->getType())) {
+          Instantiation = Method;
+          InstantiatedFrom = Method->getInstantiatedFromMemberFunction();
+          MSInfo = Method->getMemberSpecializationInfo();
+          break;
+        }
+      }
+    }
+  } else if (isa<VarDecl>(Member)) {
+    VarDecl *PrevVar;
+    if (Previous.isSingleResult() &&
+        (PrevVar = dyn_cast<VarDecl>(Previous.getFoundDecl())))
+      if (PrevVar->isStaticDataMember()) {
+        Instantiation = PrevVar;
+        InstantiatedFrom = PrevVar->getInstantiatedFromStaticDataMember();
+        MSInfo = PrevVar->getMemberSpecializationInfo();
+      }
+  } else if (isa<RecordDecl>(Member)) {
+    CXXRecordDecl *PrevRecord;
+    if (Previous.isSingleResult() &&
+        (PrevRecord = dyn_cast<CXXRecordDecl>(Previous.getFoundDecl()))) {
+      Instantiation = PrevRecord;
+      InstantiatedFrom = PrevRecord->getInstantiatedFromMemberClass();
+      MSInfo = PrevRecord->getMemberSpecializationInfo();
+    }
+  }
+  
+  if (!Instantiation) {
+    // There is no previous declaration that matches. Since member
+    // specializations are always out-of-line, the caller will complain about
+    // this mismatch later.
+    return false;
+  }
+  
+  // Make sure that this is a specialization of a member.
+  if (!InstantiatedFrom) {
+    Diag(Member->getLocation(), diag::err_spec_member_not_instantiated)
+      << Member;
+    Diag(Instantiation->getLocation(), diag::note_specialized_decl);
+    return true;
+  }
+  
+  // C++ [temp.expl.spec]p6:
+  //   If a template, a member template or the member of a class template is
+  //   explicitly specialized then that spe- cialization shall be declared 
+  //   before the first use of that specialization that would cause an implicit
+  //   instantiation to take place, in every translation unit in which such a 
+  //   use occurs; no diagnostic is required.
+  assert(MSInfo && "Member specialization info missing?");
+  if (MSInfo->getPointOfInstantiation().isValid()) {
+    Diag(Member->getLocation(), diag::err_specialization_after_instantiation)
+      << Member;
+    Diag(MSInfo->getPointOfInstantiation(), 
+         diag::note_instantiation_required_here)
+      << (MSInfo->getTemplateSpecializationKind() != TSK_ImplicitInstantiation);
+    return true;
+  }
+  
+  // Check the scope of this explicit specialization.
+  if (CheckTemplateSpecializationScope(*this, 
+                                       InstantiatedFrom,
+                                       Instantiation, Member->getLocation(), 
+                                       false))
+    return true;
+
+  // Note that this is an explicit instantiation of a member.
+  // the original declaration to note that it is an explicit specialization
+  // (if it was previously an implicit instantiation). This latter step
+  // makes bookkeeping easier.
+  if (isa<FunctionDecl>(Member)) {
+    FunctionDecl *InstantiationFunction = cast<FunctionDecl>(Instantiation);
+    if (InstantiationFunction->getTemplateSpecializationKind() ==
+          TSK_ImplicitInstantiation) {
+      InstantiationFunction->setTemplateSpecializationKind(
+                                                  TSK_ExplicitSpecialization);
+      InstantiationFunction->setLocation(Member->getLocation());
+    }
+    
+    cast<FunctionDecl>(Member)->setInstantiationOfMemberFunction(
+                                        cast<CXXMethodDecl>(InstantiatedFrom),
+                                                  TSK_ExplicitSpecialization);
+  } else if (isa<VarDecl>(Member)) {
+    VarDecl *InstantiationVar = cast<VarDecl>(Instantiation);
+    if (InstantiationVar->getTemplateSpecializationKind() ==
+          TSK_ImplicitInstantiation) {
+      InstantiationVar->setTemplateSpecializationKind(
+                                                  TSK_ExplicitSpecialization);
+      InstantiationVar->setLocation(Member->getLocation());
+    }
+    
+    Context.setInstantiatedFromStaticDataMember(cast<VarDecl>(Member),
+                                                cast<VarDecl>(InstantiatedFrom),
+                                                TSK_ExplicitSpecialization);
+  } else {
+    assert(isa<CXXRecordDecl>(Member) && "Only member classes remain");
+    CXXRecordDecl *InstantiationClass = cast<CXXRecordDecl>(Instantiation);
+    if (InstantiationClass->getTemplateSpecializationKind() ==
+          TSK_ImplicitInstantiation) {
+      InstantiationClass->setTemplateSpecializationKind(
+                                                   TSK_ExplicitSpecialization);
+      InstantiationClass->setLocation(Member->getLocation());
+    }
+    
+    cast<CXXRecordDecl>(Member)->setInstantiationOfMemberClass(
+                                        cast<CXXRecordDecl>(InstantiatedFrom),
+                                                   TSK_ExplicitSpecialization);
+  }
+             
+  // Save the caller the trouble of having to figure out which declaration
+  // this specialization matches.
+  Previous.clear();
+  Previous.addDecl(Instantiation);
+  return false;
+}
+
+/// \brief Check the scope of an explicit instantiation.
+static void CheckExplicitInstantiationScope(Sema &S, NamedDecl *D,
+                                            SourceLocation InstLoc,
+                                            bool WasQualifiedName) {
+  DeclContext *ExpectedContext
+    = D->getDeclContext()->getEnclosingNamespaceContext()->getLookupContext();
+  DeclContext *CurContext = S.CurContext->getLookupContext();
+  
+  // C++0x [temp.explicit]p2:
+  //   An explicit instantiation shall appear in an enclosing namespace of its 
+  //   template.
+  //
+  // This is DR275, which we do not retroactively apply to C++98/03.
+  if (S.getLangOptions().CPlusPlus0x && 
+      !CurContext->Encloses(ExpectedContext)) {
+    if (NamespaceDecl *NS = dyn_cast<NamespaceDecl>(ExpectedContext))
+      S.Diag(InstLoc, diag::err_explicit_instantiation_out_of_scope)
+        << D << NS;
+    else
+      S.Diag(InstLoc, diag::err_explicit_instantiation_must_be_global)
+        << D;
+    S.Diag(D->getLocation(), diag::note_explicit_instantiation_here);
+    return;
+  }
+  
+  // C++0x [temp.explicit]p2:
+  //   If the name declared in the explicit instantiation is an unqualified 
+  //   name, the explicit instantiation shall appear in the namespace where 
+  //   its template is declared or, if that namespace is inline (7.3.1), any
+  //   namespace from its enclosing namespace set.
+  if (WasQualifiedName)
+    return;
+  
+  if (CurContext->Equals(ExpectedContext))
+    return;
+  
+  S.Diag(InstLoc, diag::err_explicit_instantiation_unqualified_wrong_namespace)
+    << D << ExpectedContext;
+  S.Diag(D->getLocation(), diag::note_explicit_instantiation_here);
+}
+
+/// \brief Determine whether the given scope specifier has a template-id in it.
+static bool ScopeSpecifierHasTemplateId(const CXXScopeSpec &SS) {
+  if (!SS.isSet())
+    return false;
+  
+  // C++0x [temp.explicit]p2:
+  //   If the explicit instantiation is for a member function, a member class 
+  //   or a static data member of a class template specialization, the name of
+  //   the class template specialization in the qualified-id for the member
+  //   name shall be a simple-template-id.
+  //
+  // C++98 has the same restriction, just worded differently.
+  for (NestedNameSpecifier *NNS = (NestedNameSpecifier *)SS.getScopeRep();
+       NNS; NNS = NNS->getPrefix())
+    if (Type *T = NNS->getAsType())
+      if (isa<TemplateSpecializationType>(T))
+        return true;
+
+  return false;
+}
+
+// Explicit instantiation of a class template specialization
+// FIXME: Implement extern template semantics
+Sema::DeclResult
+Sema::ActOnExplicitInstantiation(Scope *S,
+                                 SourceLocation ExternLoc,
+                                 SourceLocation TemplateLoc,
+                                 unsigned TagSpec,
+                                 SourceLocation KWLoc,
+                                 const CXXScopeSpec &SS,
+                                 TemplateTy TemplateD,
+                                 SourceLocation TemplateNameLoc,
+                                 SourceLocation LAngleLoc,
+                                 ASTTemplateArgsPtr TemplateArgsIn,
+                                 SourceLocation RAngleLoc,
+                                 AttributeList *Attr) {
+  // Find the class template we're specializing
+  TemplateName Name = TemplateD.getAsVal<TemplateName>();
+  ClassTemplateDecl *ClassTemplate
+    = cast<ClassTemplateDecl>(Name.getAsTemplateDecl());
+
+  // Check that the specialization uses the same tag kind as the
+  // original template.
+  TagDecl::TagKind Kind;
+  switch (TagSpec) {
+  default: assert(0 && "Unknown tag type!");
+  case DeclSpec::TST_struct: Kind = TagDecl::TK_struct; break;
+  case DeclSpec::TST_union:  Kind = TagDecl::TK_union; break;
+  case DeclSpec::TST_class:  Kind = TagDecl::TK_class; break;
+  }
+  if (!isAcceptableTagRedeclaration(ClassTemplate->getTemplatedDecl(),
+                                    Kind, KWLoc,
+                                    *ClassTemplate->getIdentifier())) {
+    Diag(KWLoc, diag::err_use_with_wrong_tag)
+      << ClassTemplate
+      << CodeModificationHint::CreateReplacement(KWLoc,
+                            ClassTemplate->getTemplatedDecl()->getKindName());
+    Diag(ClassTemplate->getTemplatedDecl()->getLocation(),
+         diag::note_previous_use);
+    Kind = ClassTemplate->getTemplatedDecl()->getTagKind();
+  }
+
+  // C++0x [temp.explicit]p2:
+  //   There are two forms of explicit instantiation: an explicit instantiation
+  //   definition and an explicit instantiation declaration. An explicit 
+  //   instantiation declaration begins with the extern keyword. [...]  
+  TemplateSpecializationKind TSK
+    = ExternLoc.isInvalid()? TSK_ExplicitInstantiationDefinition
+                           : TSK_ExplicitInstantiationDeclaration;
+  
+  // Translate the parser's template argument list in our AST format.
+  TemplateArgumentListInfo TemplateArgs(LAngleLoc, RAngleLoc);
+  translateTemplateArguments(TemplateArgsIn, TemplateArgs);
+
+  // Check that the template argument list is well-formed for this
+  // template.
+  TemplateArgumentListBuilder Converted(ClassTemplate->getTemplateParameters(),
+                                        TemplateArgs.size());
+  if (CheckTemplateArgumentList(ClassTemplate, TemplateNameLoc,
+                                TemplateArgs, false, Converted))
+    return true;
+
+  assert((Converted.structuredSize() ==
+            ClassTemplate->getTemplateParameters()->size()) &&
+         "Converted template argument list is too short!");
+
+  // Find the class template specialization declaration that
+  // corresponds to these arguments.
+  llvm::FoldingSetNodeID ID;
+  ClassTemplateSpecializationDecl::Profile(ID,
+                                           Converted.getFlatArguments(),
+                                           Converted.flatSize(),
+                                           Context);
+  void *InsertPos = 0;
+  ClassTemplateSpecializationDecl *PrevDecl
+    = ClassTemplate->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
+
+  // C++0x [temp.explicit]p2:
+  //   [...] An explicit instantiation shall appear in an enclosing
+  //   namespace of its template. [...]
+  //
+  // This is C++ DR 275.
+  CheckExplicitInstantiationScope(*this, ClassTemplate, TemplateNameLoc,
+                                  SS.isSet());
+  
+  ClassTemplateSpecializationDecl *Specialization = 0;
+
+  bool ReusedDecl = false;
+  if (PrevDecl) {
+    bool SuppressNew = false;
+    if (CheckSpecializationInstantiationRedecl(TemplateNameLoc, TSK,
+                                               PrevDecl, 
+                                              PrevDecl->getSpecializationKind(), 
+                                            PrevDecl->getPointOfInstantiation(),
+                                               SuppressNew))
+      return DeclPtrTy::make(PrevDecl);
+
+    if (SuppressNew)
+      return DeclPtrTy::make(PrevDecl);
+    
+    if (PrevDecl->getSpecializationKind() == TSK_ImplicitInstantiation ||
+        PrevDecl->getSpecializationKind() == TSK_Undeclared) {
+      // Since the only prior class template specialization with these
+      // arguments was referenced but not declared, reuse that
+      // declaration node as our own, updating its source location to
+      // reflect our new declaration.
+      Specialization = PrevDecl;
+      Specialization->setLocation(TemplateNameLoc);
+      PrevDecl = 0;
+      ReusedDecl = true;
+    }
+  }
+  
+  if (!Specialization) {
+    // Create a new class template specialization declaration node for
+    // this explicit specialization.
+    Specialization
+      = ClassTemplateSpecializationDecl::Create(Context,
+                                             ClassTemplate->getDeclContext(),
+                                                TemplateNameLoc,
+                                                ClassTemplate,
+                                                Converted, PrevDecl);
+
+    if (PrevDecl) {
+      // Remove the previous declaration from the folding set, since we want
+      // to introduce a new declaration.
+      ClassTemplate->getSpecializations().RemoveNode(PrevDecl);
+      ClassTemplate->getSpecializations().FindNodeOrInsertPos(ID, InsertPos);
+    } 
+    
+    // Insert the new specialization.
+    ClassTemplate->getSpecializations().InsertNode(Specialization, InsertPos);
+  }
+
+  // Build the fully-sugared type for this explicit instantiation as
+  // the user wrote in the explicit instantiation itself. This means
+  // that we'll pretty-print the type retrieved from the
+  // specialization's declaration the way that the user actually wrote
+  // the explicit instantiation, rather than formatting the name based
+  // on the "canonical" representation used to store the template
+  // arguments in the specialization.
+  QualType WrittenTy
+    = Context.getTemplateSpecializationType(Name, TemplateArgs,
+                                  Context.getTypeDeclType(Specialization));
+  Specialization->setTypeAsWritten(WrittenTy);
+  TemplateArgsIn.release();
+
+  if (!ReusedDecl) {
+    // Add the explicit instantiation into its lexical context. However,
+    // since explicit instantiations are never found by name lookup, we
+    // just put it into the declaration context directly.
+    Specialization->setLexicalDeclContext(CurContext);
+    CurContext->addDecl(Specialization);
+  }
+
+  // C++ [temp.explicit]p3:
+  //   A definition of a class template or class member template
+  //   shall be in scope at the point of the explicit instantiation of
+  //   the class template or class member template.
+  //
+  // This check comes when we actually try to perform the
+  // instantiation.
+  ClassTemplateSpecializationDecl *Def
+    = cast_or_null<ClassTemplateSpecializationDecl>(
+                                        Specialization->getDefinition(Context));
+  if (!Def)
+    InstantiateClassTemplateSpecialization(TemplateNameLoc, Specialization, TSK);
+  
+  // Instantiate the members of this class template specialization.
+  Def = cast_or_null<ClassTemplateSpecializationDecl>(
+                                       Specialization->getDefinition(Context));
+  if (Def)
+    InstantiateClassTemplateSpecializationMembers(TemplateNameLoc, Def, TSK);
+
+  return DeclPtrTy::make(Specialization);
+}
+
+// Explicit instantiation of a member class of a class template.
+Sema::DeclResult
+Sema::ActOnExplicitInstantiation(Scope *S,
+                                 SourceLocation ExternLoc,
+                                 SourceLocation TemplateLoc,
+                                 unsigned TagSpec,
+                                 SourceLocation KWLoc,
+                                 const CXXScopeSpec &SS,
+                                 IdentifierInfo *Name,
+                                 SourceLocation NameLoc,
+                                 AttributeList *Attr) {
+
+  bool Owned = false;
+  bool IsDependent = false;
+  DeclPtrTy TagD = ActOnTag(S, TagSpec, Action::TUK_Reference,
+                            KWLoc, SS, Name, NameLoc, Attr, AS_none,
+                            MultiTemplateParamsArg(*this, 0, 0),
+                            Owned, IsDependent);
+  assert(!IsDependent && "explicit instantiation of dependent name not yet handled");
+
+  if (!TagD)
+    return true;
+
+  TagDecl *Tag = cast<TagDecl>(TagD.getAs<Decl>());
+  if (Tag->isEnum()) {
+    Diag(TemplateLoc, diag::err_explicit_instantiation_enum)
+      << Context.getTypeDeclType(Tag);
+    return true;
+  }
+
+  if (Tag->isInvalidDecl())
+    return true;
+    
+  CXXRecordDecl *Record = cast<CXXRecordDecl>(Tag);
+  CXXRecordDecl *Pattern = Record->getInstantiatedFromMemberClass();
+  if (!Pattern) {
+    Diag(TemplateLoc, diag::err_explicit_instantiation_nontemplate_type)
+      << Context.getTypeDeclType(Record);
+    Diag(Record->getLocation(), diag::note_nontemplate_decl_here);
+    return true;
+  }
+
+  // C++0x [temp.explicit]p2:
+  //   If the explicit instantiation is for a class or member class, the 
+  //   elaborated-type-specifier in the declaration shall include a 
+  //   simple-template-id.
+  //
+  // C++98 has the same restriction, just worded differently.
+  if (!ScopeSpecifierHasTemplateId(SS))
+    Diag(TemplateLoc, diag::err_explicit_instantiation_without_qualified_id)
+      << Record << SS.getRange();
+           
+  // C++0x [temp.explicit]p2:
+  //   There are two forms of explicit instantiation: an explicit instantiation
+  //   definition and an explicit instantiation declaration. An explicit 
+  //   instantiation declaration begins with the extern keyword. [...]
+  TemplateSpecializationKind TSK
+    = ExternLoc.isInvalid()? TSK_ExplicitInstantiationDefinition
+                           : TSK_ExplicitInstantiationDeclaration;
+  
+  // C++0x [temp.explicit]p2:
+  //   [...] An explicit instantiation shall appear in an enclosing
+  //   namespace of its template. [...]
+  //
+  // This is C++ DR 275.
+  CheckExplicitInstantiationScope(*this, Record, NameLoc, true);
+  
+  // Verify that it is okay to explicitly instantiate here.
+  CXXRecordDecl *PrevDecl 
+    = cast_or_null<CXXRecordDecl>(Record->getPreviousDeclaration());
+  if (!PrevDecl && Record->getDefinition(Context))
+    PrevDecl = Record;
+  if (PrevDecl) {
+    MemberSpecializationInfo *MSInfo = PrevDecl->getMemberSpecializationInfo();
+    bool SuppressNew = false;
+    assert(MSInfo && "No member specialization information?");
+    if (CheckSpecializationInstantiationRedecl(TemplateLoc, TSK, 
+                                               PrevDecl,
+                                        MSInfo->getTemplateSpecializationKind(),
+                                             MSInfo->getPointOfInstantiation(), 
+                                               SuppressNew))
+      return true;
+    if (SuppressNew)
+      return TagD;
+  }
+  
+  CXXRecordDecl *RecordDef
+    = cast_or_null<CXXRecordDecl>(Record->getDefinition(Context));
+  if (!RecordDef) {
+    // C++ [temp.explicit]p3:
+    //   A definition of a member class of a class template shall be in scope 
+    //   at the point of an explicit instantiation of the member class.
+    CXXRecordDecl *Def 
+      = cast_or_null<CXXRecordDecl>(Pattern->getDefinition(Context));
+    if (!Def) {
+      Diag(TemplateLoc, diag::err_explicit_instantiation_undefined_member)
+        << 0 << Record->getDeclName() << Record->getDeclContext();
+      Diag(Pattern->getLocation(), diag::note_forward_declaration)
+        << Pattern;
+      return true;
+    } else {
+      if (InstantiateClass(NameLoc, Record, Def,
+                           getTemplateInstantiationArgs(Record),
+                           TSK))
+        return true;
+
+      RecordDef = cast_or_null<CXXRecordDecl>(Record->getDefinition(Context));
+      if (!RecordDef)
+        return true;
+    }
+  } 
+  
+  // Instantiate all of the members of the class.
+  InstantiateClassMembers(NameLoc, RecordDef,
+                          getTemplateInstantiationArgs(Record), TSK);
+
+  // FIXME: We don't have any representation for explicit instantiations of
+  // member classes. Such a representation is not needed for compilation, but it
+  // should be available for clients that want to see all of the declarations in
+  // the source code.
+  return TagD;
+}
+
+Sema::DeclResult Sema::ActOnExplicitInstantiation(Scope *S,
+                                                  SourceLocation ExternLoc,
+                                                  SourceLocation TemplateLoc,
+                                                  Declarator &D) {
+  // Explicit instantiations always require a name.
+  DeclarationName Name = GetNameForDeclarator(D);
+  if (!Name) {
+    if (!D.isInvalidType())
+      Diag(D.getDeclSpec().getSourceRange().getBegin(),
+           diag::err_explicit_instantiation_requires_name)
+        << D.getDeclSpec().getSourceRange()
+        << D.getSourceRange();
+    
+    return true;
+  }
+
+  // The scope passed in may not be a decl scope.  Zip up the scope tree until
+  // we find one that is.
+  while ((S->getFlags() & Scope::DeclScope) == 0 ||
+         (S->getFlags() & Scope::TemplateParamScope) != 0)
+    S = S->getParent();
+
+  // Determine the type of the declaration.
+  QualType R = GetTypeForDeclarator(D, S, 0);
+  if (R.isNull())
+    return true;
+  
+  if (D.getDeclSpec().getStorageClassSpec() == DeclSpec::SCS_typedef) {
+    // Cannot explicitly instantiate a typedef.
+    Diag(D.getIdentifierLoc(), diag::err_explicit_instantiation_of_typedef)
+      << Name;
+    return true;
+  }
+
+  // C++0x [temp.explicit]p1:
+  //   [...] An explicit instantiation of a function template shall not use the
+  //   inline or constexpr specifiers.
+  // Presumably, this also applies to member functions of class templates as
+  // well.
+  if (D.getDeclSpec().isInlineSpecified() && getLangOptions().CPlusPlus0x)
+    Diag(D.getDeclSpec().getInlineSpecLoc(), 
+         diag::err_explicit_instantiation_inline)
+      <<CodeModificationHint::CreateRemoval(D.getDeclSpec().getInlineSpecLoc());
+  
+  // FIXME: check for constexpr specifier.
+  
+  // C++0x [temp.explicit]p2:
+  //   There are two forms of explicit instantiation: an explicit instantiation
+  //   definition and an explicit instantiation declaration. An explicit 
+  //   instantiation declaration begins with the extern keyword. [...]  
+  TemplateSpecializationKind TSK
+    = ExternLoc.isInvalid()? TSK_ExplicitInstantiationDefinition
+                           : TSK_ExplicitInstantiationDeclaration;
+    
+  LookupResult Previous(*this, Name, D.getIdentifierLoc(), LookupOrdinaryName);
+  LookupParsedName(Previous, S, &D.getCXXScopeSpec());
+
+  if (!R->isFunctionType()) {
+    // C++ [temp.explicit]p1:
+    //   A [...] static data member of a class template can be explicitly 
+    //   instantiated from the member definition associated with its class 
+    //   template.
+    if (Previous.isAmbiguous())
+      return true;
+    
+    VarDecl *Prev = Previous.getAsSingle<VarDecl>();
+    if (!Prev || !Prev->isStaticDataMember()) {
+      // We expect to see a data data member here.
+      Diag(D.getIdentifierLoc(), diag::err_explicit_instantiation_not_known)
+        << Name;
+      for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
+           P != PEnd; ++P)
+        Diag((*P)->getLocation(), diag::note_explicit_instantiation_here);
+      return true;
+    }
+    
+    if (!Prev->getInstantiatedFromStaticDataMember()) {
+      // FIXME: Check for explicit specialization?
+      Diag(D.getIdentifierLoc(), 
+           diag::err_explicit_instantiation_data_member_not_instantiated)
+        << Prev;
+      Diag(Prev->getLocation(), diag::note_explicit_instantiation_here);
+      // FIXME: Can we provide a note showing where this was declared?
+      return true;
+    }
+    
+    // C++0x [temp.explicit]p2:
+    //   If the explicit instantiation is for a member function, a member class 
+    //   or a static data member of a class template specialization, the name of
+    //   the class template specialization in the qualified-id for the member
+    //   name shall be a simple-template-id.
+    //
+    // C++98 has the same restriction, just worded differently.
+    if (!ScopeSpecifierHasTemplateId(D.getCXXScopeSpec()))
+      Diag(D.getIdentifierLoc(), 
+           diag::err_explicit_instantiation_without_qualified_id)
+        << Prev << D.getCXXScopeSpec().getRange();
+    
+    // Check the scope of this explicit instantiation.
+    CheckExplicitInstantiationScope(*this, Prev, D.getIdentifierLoc(), true);
+    
+    // Verify that it is okay to explicitly instantiate here.
+    MemberSpecializationInfo *MSInfo = Prev->getMemberSpecializationInfo();
+    assert(MSInfo && "Missing static data member specialization info?");
+    bool SuppressNew = false;
+    if (CheckSpecializationInstantiationRedecl(D.getIdentifierLoc(), TSK, Prev,
+                                        MSInfo->getTemplateSpecializationKind(),
+                                              MSInfo->getPointOfInstantiation(), 
+                                               SuppressNew))
+      return true;
+    if (SuppressNew)
+      return DeclPtrTy();
+    
+    // Instantiate static data member.
+    Prev->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
+    if (TSK == TSK_ExplicitInstantiationDefinition)
+      InstantiateStaticDataMemberDefinition(D.getIdentifierLoc(), Prev, false,
+                                            /*DefinitionRequired=*/true);
+    
+    // FIXME: Create an ExplicitInstantiation node?
+    return DeclPtrTy();
+  }
+  
+  // If the declarator is a template-id, translate the parser's template 
+  // argument list into our AST format.
+  bool HasExplicitTemplateArgs = false;
+  TemplateArgumentListInfo TemplateArgs;
+  if (D.getName().getKind() == UnqualifiedId::IK_TemplateId) {
+    TemplateIdAnnotation *TemplateId = D.getName().TemplateId;
+    TemplateArgs.setLAngleLoc(TemplateId->LAngleLoc);
+    TemplateArgs.setRAngleLoc(TemplateId->RAngleLoc);
+    ASTTemplateArgsPtr TemplateArgsPtr(*this,
+                                       TemplateId->getTemplateArgs(),
+                                       TemplateId->NumArgs);
+    translateTemplateArguments(TemplateArgsPtr, TemplateArgs);
+    HasExplicitTemplateArgs = true;
+    TemplateArgsPtr.release();
+  }
+    
+  // C++ [temp.explicit]p1:
+  //   A [...] function [...] can be explicitly instantiated from its template. 
+  //   A member function [...] of a class template can be explicitly 
+  //  instantiated from the member definition associated with its class 
+  //  template.
+  UnresolvedSet<8> Matches;
+  for (LookupResult::iterator P = Previous.begin(), PEnd = Previous.end();
+       P != PEnd; ++P) {
+    NamedDecl *Prev = *P;
+    if (!HasExplicitTemplateArgs) {
+      if (CXXMethodDecl *Method = dyn_cast<CXXMethodDecl>(Prev)) {
+        if (Context.hasSameUnqualifiedType(Method->getType(), R)) {
+          Matches.clear();
+
+          Matches.addDecl(Method, P.getAccess());
+          if (Method->getTemplateSpecializationKind() == TSK_Undeclared)
+            break;
+        }
+      }
+    }
+    
+    FunctionTemplateDecl *FunTmpl = dyn_cast<FunctionTemplateDecl>(Prev);
+    if (!FunTmpl)
+      continue;
+
+    TemplateDeductionInfo Info(Context, D.getIdentifierLoc());
+    FunctionDecl *Specialization = 0;
+    if (TemplateDeductionResult TDK
+          = DeduceTemplateArguments(FunTmpl, 
+                               (HasExplicitTemplateArgs ? &TemplateArgs : 0),
+                                    R, Specialization, Info)) {
+      // FIXME: Keep track of almost-matches?
+      (void)TDK;
+      continue;
+    }
+    
+    Matches.addDecl(Specialization, P.getAccess());
+  }
+  
+  // Find the most specialized function template specialization.
+  UnresolvedSetIterator Result
+    = getMostSpecialized(Matches.begin(), Matches.end(), TPOC_Other, 
+                         D.getIdentifierLoc(), 
+          PartialDiagnostic(diag::err_explicit_instantiation_not_known) << Name,
+          PartialDiagnostic(diag::err_explicit_instantiation_ambiguous) << Name,
+                PartialDiagnostic(diag::note_explicit_instantiation_candidate));
+
+  if (Result == Matches.end())
+    return true;
+
+  // Ignore access control bits, we don't need them for redeclaration checking.
+  FunctionDecl *Specialization = cast<FunctionDecl>(*Result);
+  
+  if (Specialization->getTemplateSpecializationKind() == TSK_Undeclared) {
+    Diag(D.getIdentifierLoc(), 
+         diag::err_explicit_instantiation_member_function_not_instantiated)
+      << Specialization
+      << (Specialization->getTemplateSpecializationKind() ==
+          TSK_ExplicitSpecialization);
+    Diag(Specialization->getLocation(), diag::note_explicit_instantiation_here);
+    return true;
+  } 
+  
+  FunctionDecl *PrevDecl = Specialization->getPreviousDeclaration();
+  if (!PrevDecl && Specialization->isThisDeclarationADefinition())
+    PrevDecl = Specialization;
+
+  if (PrevDecl) {
+    bool SuppressNew = false;
+    if (CheckSpecializationInstantiationRedecl(D.getIdentifierLoc(), TSK,
+                                               PrevDecl, 
+                                     PrevDecl->getTemplateSpecializationKind(), 
+                                          PrevDecl->getPointOfInstantiation(),
+                                               SuppressNew))
+      return true;
+    
+    // FIXME: We may still want to build some representation of this
+    // explicit specialization.
+    if (SuppressNew)
+      return DeclPtrTy();
+  }
+
+  Specialization->setTemplateSpecializationKind(TSK, D.getIdentifierLoc());
+  
+  if (TSK == TSK_ExplicitInstantiationDefinition)
+    InstantiateFunctionDefinition(D.getIdentifierLoc(), Specialization, 
+                                  false, /*DefinitionRequired=*/true);
+ 
+  // C++0x [temp.explicit]p2:
+  //   If the explicit instantiation is for a member function, a member class 
+  //   or a static data member of a class template specialization, the name of
+  //   the class template specialization in the qualified-id for the member
+  //   name shall be a simple-template-id.
+  //
+  // C++98 has the same restriction, just worded differently.
+  FunctionTemplateDecl *FunTmpl = Specialization->getPrimaryTemplate();
+  if (D.getName().getKind() != UnqualifiedId::IK_TemplateId && !FunTmpl &&
+      D.getCXXScopeSpec().isSet() && 
+      !ScopeSpecifierHasTemplateId(D.getCXXScopeSpec()))
+    Diag(D.getIdentifierLoc(), 
+         diag::err_explicit_instantiation_without_qualified_id)
+    << Specialization << D.getCXXScopeSpec().getRange();
+  
+  CheckExplicitInstantiationScope(*this,
+                   FunTmpl? (NamedDecl *)FunTmpl 
+                          : Specialization->getInstantiatedFromMemberFunction(),
+                                  D.getIdentifierLoc(), 
+                                  D.getCXXScopeSpec().isSet());
+  
+  // FIXME: Create some kind of ExplicitInstantiationDecl here.
+  return DeclPtrTy();
+}
+
+Sema::TypeResult
+Sema::ActOnDependentTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
+                        const CXXScopeSpec &SS, IdentifierInfo *Name,
+                        SourceLocation TagLoc, SourceLocation NameLoc) {
+  // This has to hold, because SS is expected to be defined.
+  assert(Name && "Expected a name in a dependent tag");
+
+  NestedNameSpecifier *NNS
+    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
+  if (!NNS)
+    return true;
+
+  QualType T = CheckTypenameType(NNS, *Name, SourceRange(TagLoc, NameLoc));
+  if (T.isNull())
+    return true;
+
+  TagDecl::TagKind TagKind = TagDecl::getTagKindForTypeSpec(TagSpec);
+  QualType ElabType = Context.getElaboratedType(T, TagKind);
+
+  return ElabType.getAsOpaquePtr();
+}
+
+Sema::TypeResult
+Sema::ActOnTypenameType(SourceLocation TypenameLoc, const CXXScopeSpec &SS,
+                        const IdentifierInfo &II, SourceLocation IdLoc) {
+  NestedNameSpecifier *NNS
+    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
+  if (!NNS)
+    return true;
+
+  QualType T = CheckTypenameType(NNS, II, SourceRange(TypenameLoc, IdLoc));
+  if (T.isNull())
+    return true;
+  return T.getAsOpaquePtr();
+}
+
+Sema::TypeResult
+Sema::ActOnTypenameType(SourceLocation TypenameLoc, const CXXScopeSpec &SS,
+                        SourceLocation TemplateLoc, TypeTy *Ty) {
+  QualType T = GetTypeFromParser(Ty);
+  NestedNameSpecifier *NNS
+    = static_cast<NestedNameSpecifier *>(SS.getScopeRep());
+  const TemplateSpecializationType *TemplateId
+    = T->getAs<TemplateSpecializationType>();
+  assert(TemplateId && "Expected a template specialization type");
+
+  if (computeDeclContext(SS, false)) {
+    // If we can compute a declaration context, then the "typename"
+    // keyword was superfluous. Just build a QualifiedNameType to keep
+    // track of the nested-name-specifier.
+
+    // FIXME: Note that the QualifiedNameType had the "typename" keyword!
+    return Context.getQualifiedNameType(NNS, T).getAsOpaquePtr();
+  }
+
+  return Context.getTypenameType(NNS, TemplateId).getAsOpaquePtr();
+}
+
+/// \brief Build the type that describes a C++ typename specifier,
+/// e.g., "typename T::type".
+QualType
+Sema::CheckTypenameType(NestedNameSpecifier *NNS, const IdentifierInfo &II,
+                        SourceRange Range) {
+  CXXRecordDecl *CurrentInstantiation = 0;
+  if (NNS->isDependent()) {
+    CurrentInstantiation = getCurrentInstantiationOf(NNS);
+
+    // If the nested-name-specifier does not refer to the current
+    // instantiation, then build a typename type.
+    if (!CurrentInstantiation)
+      return Context.getTypenameType(NNS, &II);
+
+    // The nested-name-specifier refers to the current instantiation, so the
+    // "typename" keyword itself is superfluous. In C++03, the program is
+    // actually ill-formed. However, DR 382 (in C++0x CD1) allows such
+    // extraneous "typename" keywords, and we retroactively apply this DR to
+    // C++03 code.
+  }
+
+  DeclContext *Ctx = 0;
+
+  if (CurrentInstantiation)
+    Ctx = CurrentInstantiation;
+  else {
+    CXXScopeSpec SS;
+    SS.setScopeRep(NNS);
+    SS.setRange(Range);
+    if (RequireCompleteDeclContext(SS))
+      return QualType();
+
+    Ctx = computeDeclContext(SS);
+  }
+  assert(Ctx && "No declaration context?");
+
+  DeclarationName Name(&II);
+  LookupResult Result(*this, Name, Range.getEnd(), LookupOrdinaryName);
+  LookupQualifiedName(Result, Ctx);
+  unsigned DiagID = 0;
+  Decl *Referenced = 0;
+  switch (Result.getResultKind()) {
+  case LookupResult::NotFound:
+    DiagID = diag::err_typename_nested_not_found;
+    break;
+      
+  case LookupResult::NotFoundInCurrentInstantiation:
+    // Okay, it's a member of an unknown instantiation.
+    return Context.getTypenameType(NNS, &II);
+
+  case LookupResult::Found:
+    if (TypeDecl *Type = dyn_cast<TypeDecl>(Result.getFoundDecl())) {
+      // We found a type. Build a QualifiedNameType, since the
+      // typename-specifier was just sugar. FIXME: Tell
+      // QualifiedNameType that it has a "typename" prefix.
+      return Context.getQualifiedNameType(NNS, Context.getTypeDeclType(Type));
+    }
+
+    DiagID = diag::err_typename_nested_not_type;
+    Referenced = Result.getFoundDecl();
+    break;
+
+  case LookupResult::FoundUnresolvedValue:
+    llvm_unreachable("unresolved using decl in non-dependent context");
+    return QualType();
+
+  case LookupResult::FoundOverloaded:
+    DiagID = diag::err_typename_nested_not_type;
+    Referenced = *Result.begin();
+    break;
+
+  case LookupResult::Ambiguous:
+    return QualType();
+  }
+
+  // If we get here, it's because name lookup did not find a
+  // type. Emit an appropriate diagnostic and return an error.
+  Diag(Range.getEnd(), DiagID) << Range << Name << Ctx;
+  if (Referenced)
+    Diag(Referenced->getLocation(), diag::note_typename_refers_here)
+      << Name;
+  return QualType();
+}
+
+namespace {
+  // See Sema::RebuildTypeInCurrentInstantiation
+  class CurrentInstantiationRebuilder
+    : public TreeTransform<CurrentInstantiationRebuilder> {
+    SourceLocation Loc;
+    DeclarationName Entity;
+
+  public:
+    CurrentInstantiationRebuilder(Sema &SemaRef,
+                                  SourceLocation Loc,
+                                  DeclarationName Entity)
+    : TreeTransform<CurrentInstantiationRebuilder>(SemaRef),
+      Loc(Loc), Entity(Entity) { }
+
+    /// \brief Determine whether the given type \p T has already been
+    /// transformed.
+    ///
+    /// For the purposes of type reconstruction, a type has already been
+    /// transformed if it is NULL or if it is not dependent.
+    bool AlreadyTransformed(QualType T) {
+      return T.isNull() || !T->isDependentType();
+    }
+
+    /// \brief Returns the location of the entity whose type is being
+    /// rebuilt.
+    SourceLocation getBaseLocation() { return Loc; }
+
+    /// \brief Returns the name of the entity whose type is being rebuilt.
+    DeclarationName getBaseEntity() { return Entity; }
+
+    /// \brief Sets the "base" location and entity when that
+    /// information is known based on another transformation.
+    void setBase(SourceLocation Loc, DeclarationName Entity) {
+      this->Loc = Loc;
+      this->Entity = Entity;
+    }
+      
+    /// \brief Transforms an expression by returning the expression itself
+    /// (an identity function).
+    ///
+    /// FIXME: This is completely unsafe; we will need to actually clone the
+    /// expressions.
+    Sema::OwningExprResult TransformExpr(Expr *E) {
+      return getSema().Owned(E);
+    }
+
+    /// \brief Transforms a typename type by determining whether the type now
+    /// refers to a member of the current instantiation, and then
+    /// type-checking and building a QualifiedNameType (when possible).
+    QualType TransformTypenameType(TypeLocBuilder &TLB, TypenameTypeLoc TL);
+  };
+}
+
+QualType
+CurrentInstantiationRebuilder::TransformTypenameType(TypeLocBuilder &TLB,
+                                                     TypenameTypeLoc TL) {
+  TypenameType *T = TL.getTypePtr();
+
+  NestedNameSpecifier *NNS
+    = TransformNestedNameSpecifier(T->getQualifier(),
+                              /*FIXME:*/SourceRange(getBaseLocation()));
+  if (!NNS)
+    return QualType();
+
+  // If the nested-name-specifier did not change, and we cannot compute the
+  // context corresponding to the nested-name-specifier, then this
+  // typename type will not change; exit early.
+  CXXScopeSpec SS;
+  SS.setRange(SourceRange(getBaseLocation()));
+  SS.setScopeRep(NNS);
+
+  QualType Result;
+  if (NNS == T->getQualifier() && getSema().computeDeclContext(SS) == 0)
+    Result = QualType(T, 0);
+
+  // Rebuild the typename type, which will probably turn into a
+  // QualifiedNameType.
+  else if (const TemplateSpecializationType *TemplateId = T->getTemplateId()) {
+    QualType NewTemplateId
+      = TransformType(QualType(TemplateId, 0));
+    if (NewTemplateId.isNull())
+      return QualType();
+
+    if (NNS == T->getQualifier() &&
+        NewTemplateId == QualType(TemplateId, 0))
+      Result = QualType(T, 0);
+    else
+      Result = getDerived().RebuildTypenameType(NNS, NewTemplateId);
+  } else
+    Result = getDerived().RebuildTypenameType(NNS, T->getIdentifier(),
+                                              SourceRange(TL.getNameLoc()));
+
+  TypenameTypeLoc NewTL = TLB.push<TypenameTypeLoc>(Result);
+  NewTL.setNameLoc(TL.getNameLoc());
+  return Result;
+}
+
+/// \brief Rebuilds a type within the context of the current instantiation.
+///
+/// The type \p T is part of the type of an out-of-line member definition of
+/// a class template (or class template partial specialization) that was parsed
+/// and constructed before we entered the scope of the class template (or
+/// partial specialization thereof). This routine will rebuild that type now
+/// that we have entered the declarator's scope, which may produce different
+/// canonical types, e.g.,
+///
+/// \code
+/// template<typename T>
+/// struct X {
+///   typedef T* pointer;
+///   pointer data();
+/// };
+///
+/// template<typename T>
+/// typename X<T>::pointer X<T>::data() { ... }
+/// \endcode
+///
+/// Here, the type "typename X<T>::pointer" will be created as a TypenameType,
+/// since we do not know that we can look into X<T> when we parsed the type.
+/// This function will rebuild the type, performing the lookup of "pointer"
+/// in X<T> and returning a QualifiedNameType whose canonical type is the same
+/// as the canonical type of T*, allowing the return types of the out-of-line
+/// definition and the declaration to match.
+QualType Sema::RebuildTypeInCurrentInstantiation(QualType T, SourceLocation Loc,
+                                                 DeclarationName Name) {
+  if (T.isNull() || !T->isDependentType())
+    return T;
+
+  CurrentInstantiationRebuilder Rebuilder(*this, Loc, Name);
+  return Rebuilder.TransformType(T);
+}
+
+/// \brief Produces a formatted string that describes the binding of
+/// template parameters to template arguments.
+std::string
+Sema::getTemplateArgumentBindingsText(const TemplateParameterList *Params,
+                                      const TemplateArgumentList &Args) {
+  // FIXME: For variadic templates, we'll need to get the structured list.
+  return getTemplateArgumentBindingsText(Params, Args.getFlatArgumentList(),
+                                         Args.flat_size());
+}
+
+std::string
+Sema::getTemplateArgumentBindingsText(const TemplateParameterList *Params,
+                                      const TemplateArgument *Args,
+                                      unsigned NumArgs) {
+  std::string Result;
+
+  if (!Params || Params->size() == 0 || NumArgs == 0)
+    return Result;
+  
+  for (unsigned I = 0, N = Params->size(); I != N; ++I) {
+    if (I >= NumArgs)
+      break;
+    
+    if (I == 0)
+      Result += "[with ";
+    else
+      Result += ", ";
+    
+    if (const IdentifierInfo *Id = Params->getParam(I)->getIdentifier()) {
+      Result += Id->getName();
+    } else {
+      Result += '$';
+      Result += llvm::utostr(I);
+    }
+    
+    Result += " = ";
+    
+    switch (Args[I].getKind()) {
+      case TemplateArgument::Null:
+        Result += "<no value>";
+        break;
+        
+      case TemplateArgument::Type: {
+        std::string TypeStr;
+        Args[I].getAsType().getAsStringInternal(TypeStr, 
+                                                Context.PrintingPolicy);
+        Result += TypeStr;
+        break;
+      }
+        
+      case TemplateArgument::Declaration: {
+        bool Unnamed = true;
+        if (NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Args[I].getAsDecl())) {
+          if (ND->getDeclName()) {
+            Unnamed = false;
+            Result += ND->getNameAsString();
+          }
+        }
+        
+        if (Unnamed) {
+          Result += "<anonymous>";
+        }
+        break;
+      }
+        
+      case TemplateArgument::Template: {
+        std::string Str;
+        llvm::raw_string_ostream OS(Str);
+        Args[I].getAsTemplate().print(OS, Context.PrintingPolicy);
+        Result += OS.str();
+        break;
+      }
+        
+      case TemplateArgument::Integral: {
+        Result += Args[I].getAsIntegral()->toString(10);
+        break;
+      }
+        
+      case TemplateArgument::Expression: {
+        assert(false && "No expressions in deduced template arguments!");
+        Result += "<expression>";
+        break;
+      }
+        
+      case TemplateArgument::Pack:
+        // FIXME: Format template argument packs
+        Result += "<template argument pack>";
+        break;        
+    }
+  }
+  
+  Result += ']';
+  return Result;
+}