Implement C++0x scoped enumerations, from Daniel Wallin! (and tweaked a

bit by me). 


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@116122 91177308-0d34-0410-b5e6-96231b3b80d8

28 files changed, 512 insertions, 69 deletions

diff --git a/docs/LanguageExtensions.html b/docs/LanguageExtensions.html
index 8faa555f5c..27d90c5cd3 100644
--- a/docs/LanguageExtensions.html
+++ b/docs/LanguageExtensions.html
@@ -42,6 +42,7 @@ td {
   <li><a href="#cxx_auto_type">C++0x type inference</a></li>
   <li><a href="#cxx_variadic_templates">C++0x variadic templates</a></li>
   <li><a href="#cxx_inline_namespaces">C++0x inline namespaces</a></li>
+  <li><a href="#cxx_strong_enums">C++0x strongly-typed enumerations</a></li>
   <li><a href="#cxx_trailing_return">C++0x trailing return type</a></li>
   </ul>
 <li><a href="#blocks">Blocks</a></li>
@@ -368,6 +369,11 @@ inline namespaces is enabled.</p>
 <p>Use <tt>__has_feature(cxx_trailing_return)</tt> to determine if support for
 the alternate function declaration syntax with trailing return type is enabled.</p>
 
+<h3 id="cxx_strong_enums">C++0x strongly typed enumerations</h3>
+
+<p>Use <tt>__has_feature(cxx_strong_enums)</tt> to determine if support for
+strongly typed, scoped enumerations is enabled.</p>
+
 <!-- ======================================================================= -->
 <h2 id="blocks">Blocks</h2>
 <!-- ======================================================================= -->
diff --git a/include/clang/AST/Decl.h b/include/clang/AST/Decl.h
index d4c6600292..1e7b0cd0d4 100644
--- a/include/clang/AST/Decl.h
+++ b/include/clang/AST/Decl.h
@@ -1825,6 +1825,14 @@ protected:
   unsigned NumPositiveBits : 8;
   unsigned NumNegativeBits : 8;
 
+  /// IsScoped - True if this is tag declaration is a scoped enumeration. Only
+  /// possible in C++0x mode.
+  bool IsScoped : 1;
+
+  /// IsFixed - True if this is an enumeration with fixed underlying type. Only
+  /// possible in C++0x mode.
+  bool IsFixed : 1;
+
 private:
   SourceLocation TagKeywordLoc;
   SourceLocation RBraceLoc;
@@ -2008,7 +2016,19 @@ class EnumDecl : public TagDecl {
   /// IntegerType - This represent the integer type that the enum corresponds
   /// to for code generation purposes.  Note that the enumerator constants may
   /// have a different type than this does.
-  QualType IntegerType;
+  ///
+  /// If the underlying integer type was explicitly stated in the source
+  /// code, this is a TypeSourceInfo* for that type. Otherwise this type
+  /// was automatically deduced somehow, and this is a Type*.
+  ///
+  /// Normally if IsFixed(), this would contain a TypeSourceInfo*, but in
+  /// some cases it won't.
+  ///
+  /// The underlying type of an enumeration never has any qualifiers, so
+  /// we can get away with just storing a raw Type*, and thus save an
+  /// extra pointer when TypeSourceInfo is needed.
+
+  llvm::PointerUnion<const Type*, TypeSourceInfo*> IntegerType;
 
   /// PromotionType - The integer type that values of this type should
   /// promote to.  In C, enumerators are generally of an integer type
@@ -2029,11 +2049,14 @@ class EnumDecl : public TagDecl {
   };
 
   EnumDecl(DeclContext *DC, SourceLocation L,
-           IdentifierInfo *Id, EnumDecl *PrevDecl, SourceLocation TKL)
+           IdentifierInfo *Id, EnumDecl *PrevDecl, SourceLocation TKL,
+           bool Scoped, bool Fixed)
     : TagDecl(Enum, TTK_Enum, DC, L, Id, PrevDecl, TKL), InstantiatedFrom(0) {
-      IntegerType = QualType();
+      IntegerType = (const Type*)0;
       NumNegativeBits = 0;
       NumPositiveBits = 0;
+      IsScoped = Scoped;
+      IsFixed = Fixed;
     }
 public:
   EnumDecl *getCanonicalDecl() {
@@ -2052,7 +2075,8 @@ public:
 
   static EnumDecl *Create(ASTContext &C, DeclContext *DC,
                           SourceLocation L, IdentifierInfo *Id,
-                          SourceLocation TKL, EnumDecl *PrevDecl);
+                          SourceLocation TKL, EnumDecl *PrevDecl,
+                          bool IsScoped, bool IsFixed);
   static EnumDecl *Create(ASTContext &C, EmptyShell Empty);
 
   /// completeDefinition - When created, the EnumDecl corresponds to a
@@ -2092,10 +2116,25 @@ public:
 
   /// getIntegerType - Return the integer type this enum decl corresponds to.
   /// This returns a null qualtype for an enum forward definition.
-  QualType getIntegerType() const { return IntegerType; }
+  QualType getIntegerType() const {
+    if (!IntegerType)
+      return QualType();
+    if (const Type* T = IntegerType.dyn_cast<const Type*>())
+      return QualType(T, 0);
+    return IntegerType.get<TypeSourceInfo*>()->getType();
+  }
 
   /// \brief Set the underlying integer type.
-  void setIntegerType(QualType T) { IntegerType = T; }
+  void setIntegerType(QualType T) { IntegerType = T.getTypePtr(); }
+
+  /// \brief Set the underlying integer type source info.
+  void setIntegerTypeSourceInfo(TypeSourceInfo* TInfo) { IntegerType = TInfo; }
+
+  /// \brief Return the type source info for the underlying integer type,
+  /// if no type source info exists, return 0.
+  TypeSourceInfo* getIntegerTypeSourceInfo() const {
+    return IntegerType.dyn_cast<TypeSourceInfo*>();
+  }
 
   /// \brief Returns the width in bits requred to store all the
   /// non-negative enumerators of this enum.
@@ -2123,6 +2162,22 @@ public:
     NumNegativeBits = Num;
   }
 
+  /// \brief Returns true if this is a C++0x scoped enumeration.
+  bool isScoped() const {
+    return IsScoped;
+  }
+
+  /// \brief Returns true if this is a C++0x enumeration with fixed underlying
+  /// type.
+  bool isFixed() const {
+    return IsFixed;
+  }
+
+  /// \brief Returns true if this can be considered a complete type.
+  bool isComplete() const {
+    return isDefinition() || isFixed();
+  }
+
   /// \brief Returns the enumeration (declared within the template)
   /// from which this enumeration type was instantiated, or NULL if
   /// this enumeration was not instantiated from any template.
@@ -2135,6 +2190,8 @@ public:
   static bool classof(const Decl *D) { return classofKind(D->getKind()); }
   static bool classof(const EnumDecl *D) { return true; }
   static bool classofKind(Kind K) { return K == Enum; }
+
+  friend class ASTDeclReader;
 };
 
 
diff --git a/include/clang/AST/Type.h b/include/clang/AST/Type.h
index 3cd60d3021..fdd1d165a8 100644
--- a/include/clang/AST/Type.h
+++ b/include/clang/AST/Type.h
@@ -879,6 +879,9 @@ public:
   
   /// \brief Determine whether this type is an integral or enumeration type.
   bool isIntegralOrEnumerationType() const;
+  /// \brief Determine whether this type is an integral or unscoped enumeration
+  /// type.
+  bool isIntegralOrUnscopedEnumerationType() const;
                                    
   /// Floating point categories.
   bool isRealFloatingType() const; // C99 6.2.5p10 (float, double, long double)
diff --git a/include/clang/Basic/DiagnosticParseKinds.td b/include/clang/Basic/DiagnosticParseKinds.td
index 430ed9f011..273abe1183 100644
--- a/include/clang/Basic/DiagnosticParseKinds.td
+++ b/include/clang/Basic/DiagnosticParseKinds.td
@@ -384,6 +384,9 @@ def err_friend_decl_defines_class : Error<
 def warn_deleted_function_accepted_as_extension: ExtWarn<
   "deleted function definition accepted as a C++0x extension">, InGroup<CXX0x>;
 
+def err_scoped_enum_missing_identifier : Error<
+  "scoped enumeration requires a name">;
+
 // Language specific pragmas
 // - Generic warnings
 def warn_pragma_expected_lparen : Warning<
diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 2d2ed63762..7eb5453fa8 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -826,6 +826,20 @@ def err_final_function_overridden : Error<
   "declaration of %0 overrides a 'final' function">;
 def err_final_base : Error<
   "derivation from 'final' %0">;
+
+// C++0x scoped enumerations
+def err_enum_invalid_underlying : Error<
+  "non-integral type %0 is an invalid underlying type">;
+def err_enumerator_too_large : Error<
+  "enumerator value is not representable in the underlying type %0">;
+def err_enumerator_wrapped : Error<
+  "enumerator value %0 is not representable in the underlying type %1">;
+def err_enum_redeclare_type_mismatch : Error<
+  "enumeration redeclared with different underlying type">;
+def err_enum_redeclare_fixed_mismatch : Error<
+  "enumeration previously declared with %select{non|}0fixed underlying type">;
+def err_enum_redeclare_scoped_mismatch : Error<
+  "enumeration previously declared as %select{un|}0scoped">;
   
 // Objective-C++
 def err_objc_decls_may_only_appear_in_global_scope : Error<
diff --git a/include/clang/Sema/Sema.h b/include/clang/Sema/Sema.h
index 3ef942b2e8..b5a092e756 100644
--- a/include/clang/Sema/Sema.h
+++ b/include/clang/Sema/Sema.h
@@ -785,7 +785,8 @@ public:
                  IdentifierInfo *Name, SourceLocation NameLoc,
                  AttributeList *Attr, AccessSpecifier AS,
                  MultiTemplateParamsArg TemplateParameterLists,
-                 bool &OwnedDecl, bool &IsDependent);
+                 bool &OwnedDecl, bool &IsDependent, bool ScopedEnum,
+                 TypeResult UnderlyingType);
 
   TypeResult ActOnDependentTag(Scope *S,
                                unsigned TagSpec,
diff --git a/lib/AST/ASTContext.cpp b/lib/AST/ASTContext.cpp
index 1fddd3256f..72d7f600f0 100644
--- a/lib/AST/ASTContext.cpp
+++ b/lib/AST/ASTContext.cpp
@@ -5154,10 +5154,10 @@ QualType ASTContext::mergeObjCGCQualifiers(QualType LHS, QualType RHS) {
 //===----------------------------------------------------------------------===//
 
 unsigned ASTContext::getIntWidth(QualType T) {
-  if (T->isBooleanType())
-    return 1;
   if (EnumType *ET = dyn_cast<EnumType>(T))
     T = ET->getDecl()->getIntegerType();
+  if (T->isBooleanType())
+    return 1;
   // For builtin types, just use the standard type sizing method
   return (unsigned)getTypeSize(T);
 }
diff --git a/lib/AST/ASTImporter.cpp b/lib/AST/ASTImporter.cpp
index 78cb536550..d2a3788956 100644
--- a/lib/AST/ASTImporter.cpp
+++ b/lib/AST/ASTImporter.cpp
@@ -1622,7 +1622,7 @@ Decl *ASTNodeImporter::VisitEnumDecl(EnumDecl *D) {
   EnumDecl *D2 = EnumDecl::Create(Importer.getToContext(), DC, Loc,
                                       Name.getAsIdentifierInfo(),
                                       Importer.Import(D->getTagKeywordLoc()),
-                                      0);
+                                      0, D->isScoped(), D->isFixed());
   // Import the qualifier, if any.
   if (D->getQualifier()) {
     NestedNameSpecifier *NNS = Importer.Import(D->getQualifier());
diff --git a/lib/AST/Decl.cpp b/lib/AST/Decl.cpp
index 081e5ee6ad..f455473059 100644
--- a/lib/AST/Decl.cpp
+++ b/lib/AST/Decl.cpp
@@ -1615,14 +1615,16 @@ void TagDecl::setQualifierInfo(NestedNameSpecifier *Qualifier,
 
 EnumDecl *EnumDecl::Create(ASTContext &C, DeclContext *DC, SourceLocation L,
                            IdentifierInfo *Id, SourceLocation TKL,
-                           EnumDecl *PrevDecl) {
-  EnumDecl *Enum = new (C) EnumDecl(DC, L, Id, PrevDecl, TKL);
+                           EnumDecl *PrevDecl, bool IsScoped, bool IsFixed) {
+  EnumDecl *Enum = new (C) EnumDecl(DC, L, Id, PrevDecl, TKL,
+                                    IsScoped, IsFixed);
   C.getTypeDeclType(Enum, PrevDecl);
   return Enum;
 }
 
 EnumDecl *EnumDecl::Create(ASTContext &C, EmptyShell Empty) {
-  return new (C) EnumDecl(0, SourceLocation(), 0, 0, SourceLocation());
+  return new (C) EnumDecl(0, SourceLocation(), 0, 0, SourceLocation(),
+                          false, false);
 }
 
 void EnumDecl::completeDefinition(QualType NewType,
@@ -1630,7 +1632,8 @@ void EnumDecl::completeDefinition(QualType NewType,
                                   unsigned NumPositiveBits,
                                   unsigned NumNegativeBits) {
   assert(!isDefinition() && "Cannot redefine enums!");
-  IntegerType = NewType;
+  if (!IntegerType)
+    IntegerType = NewType.getTypePtr();
   PromotionType = NewPromotionType;
   setNumPositiveBits(NumPositiveBits);
   setNumNegativeBits(NumNegativeBits);
diff --git a/lib/AST/DeclBase.cpp b/lib/AST/DeclBase.cpp
index 26ab9250d7..ece9945390 100644
--- a/lib/AST/DeclBase.cpp
+++ b/lib/AST/DeclBase.cpp
@@ -516,7 +516,7 @@ bool DeclContext::isDependentContext() const {
 
 bool DeclContext::isTransparentContext() const {
   if (DeclKind == Decl::Enum)
-    return true; // FIXME: Check for C++0x scoped enums
+    return !cast<EnumDecl>(this)->isScoped();
   else if (DeclKind == Decl::LinkageSpec)
     return true;
   else if (DeclKind >= Decl::firstRecord && DeclKind <= Decl::lastRecord)
diff --git a/lib/AST/Type.cpp b/lib/AST/Type.cpp
index 61390c8539..11afea0446 100644
--- a/lib/AST/Type.cpp
+++ b/lib/AST/Type.cpp
@@ -409,11 +409,10 @@ bool Type::isIntegerType() const {
   if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::Int128;
-  if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
+  if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
     // Incomplete enum types are not treated as integer types.
     // FIXME: In C++, enum types are never integer types.
-    if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
-      return true;
+    return ET->getDecl()->isComplete();
   return false;
 }
 
@@ -449,9 +448,8 @@ bool Type::isIntegralType(ASTContext &Ctx) const {
     BT->getKind() <= BuiltinType::Int128;
   
   if (!Ctx.getLangOptions().CPlusPlus)
-    if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
-      if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
-        return true;  // Complete enum types are integral in C.
+    if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
+      return ET->getDecl()->isComplete(); // Complete enum types are integral in C.
   
   return false;
 }
@@ -463,13 +461,28 @@ bool Type::isIntegralOrEnumerationType() const {
 
   // Check for a complete enum type; incomplete enum types are not properly an
   // enumeration type in the sense required here.
-  if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
-    if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
-      return true;
+  if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
+    return ET->getDecl()->isComplete();
 
   return false;  
 }
 
+bool Type::isIntegralOrUnscopedEnumerationType() const {
+  if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
+    return BT->getKind() >= BuiltinType::Bool &&
+           BT->getKind() <= BuiltinType::Int128;
+
+  // Check for a complete enum type; incomplete enum types are not properly an
+  // enumeration type in the sense required here.
+  // C++0x: However, if the underlying type of the enum is fixed, it is
+  // considered complete.
+  if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
+    return ET->getDecl()->isComplete() && !ET->getDecl()->isScoped();
+
+  return false;
+}
+
+
 bool Type::isBooleanType() const {
   if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() == BuiltinType::Bool;
@@ -573,8 +586,8 @@ bool Type::isRealType() const {
   if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() >= BuiltinType::Bool &&
            BT->getKind() <= BuiltinType::LongDouble;
-  if (const TagType *TT = dyn_cast<TagType>(CanonicalType))
-    return TT->getDecl()->isEnum() && TT->getDecl()->isDefinition();
+  if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
+      return ET->getDecl()->isComplete() && !ET->getDecl()->isScoped();
   return false;
 }
 
@@ -585,20 +598,21 @@ bool Type::isArithmeticType() const {
   if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
     // GCC allows forward declaration of enum types (forbid by C99 6.7.2.3p2).
     // If a body isn't seen by the time we get here, return false.
-    return ET->getDecl()->isDefinition();
+    //
+    // C++0x: Enumerations are not arithmetic types. For now, just return
+    // false for scoped enumerations since that will disable any
+    // unwanted implicit conversions.
+    return !ET->getDecl()->isScoped() && ET->getDecl()->isComplete();
   return isa<ComplexType>(CanonicalType);
 }
 
 bool Type::isScalarType() const {
   if (const BuiltinType *BT = dyn_cast<BuiltinType>(CanonicalType))
     return BT->getKind() != BuiltinType::Void;
-  if (const TagType *TT = dyn_cast<TagType>(CanonicalType)) {
+  if (const EnumType *ET = dyn_cast<EnumType>(CanonicalType))
     // Enums are scalar types, but only if they are defined.  Incomplete enums
     // are not treated as scalar types.
-    if (TT->getDecl()->isEnum() && TT->getDecl()->isDefinition())
-      return true;
-    return false;
-  }
+    return ET->getDecl()->isComplete();
   return isa<PointerType>(CanonicalType) ||
          isa<BlockPointerType>(CanonicalType) ||
          isa<MemberPointerType>(CanonicalType) ||
@@ -646,8 +660,12 @@ bool Type::isIncompleteType() const {
     // Void is the only incomplete builtin type.  Per C99 6.2.5p19, it can never
     // be completed.
     return isVoidType();
-  case Record:
   case Enum:
+    // An enumeration with fixed underlying type is complete (C++0x 7.2p3).
+    if (cast<EnumType>(CanonicalType)->getDecl()->isFixed())
+        return false;
+    // Fall through.
+  case Record:
     // A tagged type (struct/union/enum/class) is incomplete if the decl is a
     // forward declaration, but not a full definition (C99 6.2.5p22).
     return !cast<TagType>(CanonicalType)->getDecl()->isDefinition();
@@ -763,7 +781,8 @@ bool Type::isPromotableIntegerType() const {
   // Enumerated types are promotable to their compatible integer types
   // (C99 6.3.1.1) a.k.a. its underlying type (C++ [conv.prom]p2).
   if (const EnumType *ET = getAs<EnumType>()){
-    if (this->isDependentType() || ET->getDecl()->getPromotionType().isNull())
+    if (this->isDependentType() || ET->getDecl()->getPromotionType().isNull()
+        || ET->getDecl()->isScoped())
       return false;
     
     const BuiltinType *BT
diff --git a/lib/CodeGen/CGExpr.cpp b/lib/CodeGen/CGExpr.cpp
index 78c1da5060..e4ed5d64d9 100644
--- a/lib/CodeGen/CGExpr.cpp
+++ b/lib/CodeGen/CGExpr.cpp
@@ -599,11 +599,17 @@ llvm::Value *CodeGenFunction::EmitLoadOfScalar(llvm::Value *Addr, bool Volatile,
   return V;
 }
 
+static bool isBooleanUnderlyingType(QualType Ty) {
+  if (const EnumType *ET = dyn_cast<EnumType>(Ty))
+    return ET->getDecl()->getIntegerType()->isBooleanType();
+  return false;
+}
+
 void CodeGenFunction::EmitStoreOfScalar(llvm::Value *Value, llvm::Value *Addr,
                                         bool Volatile, unsigned Alignment,
                                         QualType Ty) {
 
-  if (Ty->isBooleanType()) {
+  if (Ty->isBooleanType() || isBooleanUnderlyingType(Ty)) {
     // Bool can have different representation in memory than in registers.
     const llvm::PointerType *DstPtr = cast<llvm::PointerType>(Addr->getType());
     Value = Builder.CreateIntCast(Value, DstPtr->getElementType(), false);
diff --git a/lib/CodeGen/CodeGenTypes.cpp b/lib/CodeGen/CodeGenTypes.cpp
index 5ab65c5779..87cab311d4 100644
--- a/lib/CodeGen/CodeGenTypes.cpp
+++ b/lib/CodeGen/CodeGenTypes.cpp
@@ -424,9 +424,13 @@ const llvm::Type *CodeGenTypes::ConvertTagDeclType(const TagDecl *TD) {
   if (TDTI != TagDeclTypes.end())
     return TDTI->second;
 
+  const EnumDecl *ED = dyn_cast<EnumDecl>(TD);
+
   // If this is still a forward declaration, just define an opaque
   // type to use for this tagged decl.
-  if (!TD->isDefinition()) {
+  // C++0x: If this is a enumeration type with fixed underlying type,
+  // consider it complete.
+  if (!TD->isDefinition() && !(ED && ED->isFixed())) {
     llvm::Type *ResultType = llvm::OpaqueType::get(getLLVMContext());
     TagDeclTypes.insert(std::make_pair(Key, ResultType));
     return ResultType;
@@ -434,8 +438,8 @@ const llvm::Type *CodeGenTypes::ConvertTagDeclType(const TagDecl *TD) {
 
   // Okay, this is a definition of a type.  Compile the implementation now.
 
-  if (TD->isEnum())  // Don't bother storing enums in TagDeclTypes.
-    return ConvertTypeRecursive(cast<EnumDecl>(TD)->getIntegerType());
+  if (ED)  // Don't bother storing enums in TagDeclTypes.
+    return ConvertTypeRecursive(ED->getIntegerType());
 
   // This decl could well be recursive.  In this case, insert an opaque
   // definition of this type, which the recursive uses will get.  We will then
diff --git a/lib/Lex/PPMacroExpansion.cpp b/lib/Lex/PPMacroExpansion.cpp
index ac69595227..24a0f39b05 100644
--- a/lib/Lex/PPMacroExpansion.cpp
+++ b/lib/Lex/PPMacroExpansion.cpp
@@ -517,6 +517,7 @@ static bool HasFeature(const Preprocessor &PP, const IdentifierInfo *II) {
            .Case("cxx_deleted_functions", true) // Accepted as an extension.
            .Case("cxx_exceptions", LangOpts.Exceptions)
            .Case("cxx_rtti", LangOpts.RTTI)
+           .Case("cxx_strong_enums", LangOpts.CPlusPlus0x)
            .Case("cxx_static_assert", LangOpts.CPlusPlus0x)
            .Case("cxx_trailing_return", LangOpts.CPlusPlus0x)
            .Case("objc_nonfragile_abi", LangOpts.ObjCNonFragileABI)
diff --git a/lib/Parse/ParseDecl.cpp b/lib/Parse/ParseDecl.cpp
index e6a4b91e2d..3d29e9e702 100644
--- a/lib/Parse/ParseDecl.cpp
+++ b/lib/Parse/ParseDecl.cpp
@@ -1958,6 +1958,21 @@ void Parser::ParseStructUnionBody(SourceLocation RecordLoc,
 ///         'enum' identifier
 /// [GNU]   'enum' attributes[opt] identifier
 ///
+/// [C++0x] enum-head '{' enumerator-list[opt] '}'
+/// [C++0x] enum-head '{' enumerator-list ','  '}'
+///
+///       enum-head: [C++0x]
+///         enum-key attributes[opt] identifier[opt] enum-base[opt]
+///         enum-key attributes[opt] nested-name-specifier identifier enum-base[opt]
+///
+///       enum-key: [C++0x]
+///         'enum'
+///         'enum' 'class'
+///         'enum' 'struct'
+///
+///       enum-base: [C++0x]
+///         ':' type-specifier-seq
+///
 /// [C++] elaborated-type-specifier:
 /// [C++]   'enum' '::'[opt] nested-name-specifier[opt] identifier
 ///
@@ -1992,6 +2007,14 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     }
   }
 
+  bool IsScopedEnum = false;
+
+  if (getLang().CPlusPlus0x && (Tok.is(tok::kw_class)
+                                || Tok.is(tok::kw_struct))) {
+    ConsumeToken();
+    IsScopedEnum = true;
+  }
+
   // Must have either 'enum name' or 'enum {...}'.
   if (Tok.isNot(tok::identifier) && Tok.isNot(tok::l_brace)) {
     Diag(Tok, diag::err_expected_ident_lbrace);
@@ -2009,6 +2032,21 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
     NameLoc = ConsumeToken();
   }
 
+  if (!Name && IsScopedEnum) {
+    // C++0x 7.2p2: The optional identifier shall not be omitted in the
+    // declaration of a scoped enumeration.
+    Diag(Tok, diag::err_scoped_enum_missing_identifier);
+    IsScopedEnum = false;
+  }
+
+  TypeResult BaseType;
+
+  if (getLang().CPlusPlus0x && Tok.is(tok::colon)) {
+    ConsumeToken();
+    SourceRange Range;
+    BaseType = ParseTypeName(&Range);
+  }
+
   // There are three options here.  If we have 'enum foo;', then this is a
   // forward declaration.  If we have 'enum foo {...' then this is a
   // definition. Otherwise we have something like 'enum foo xyz', a reference.
@@ -2045,7 +2083,9 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
                                    StartLoc, SS, Name, NameLoc, Attr.get(),
                                    AS,
                                    MultiTemplateParamsArg(Actions),
-                                   Owned, IsDependent);
+                                   Owned, IsDependent, IsScopedEnum,
+                                   BaseType);
+
   if (IsDependent) {
     // This enum has a dependent nested-name-specifier. Handle it as a 
     // dependent tag.
diff --git a/lib/Parse/ParseDeclCXX.cpp b/lib/Parse/ParseDeclCXX.cpp
index 59d4f9fad3..e1a97da9c2 100644
--- a/lib/Parse/ParseDeclCXX.cpp
+++ b/lib/Parse/ParseDeclCXX.cpp
@@ -955,7 +955,8 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
                                        MultiTemplateParamsArg(Actions,
                                     TemplateParams? &(*TemplateParams)[0] : 0,
                                     TemplateParams? TemplateParams->size() : 0),
-                                       Owned, IsDependent);
+                                       Owned, IsDependent, false,
+                                       clang::TypeResult());
 
     // If ActOnTag said the type was dependent, try again with the
     // less common call.
diff --git a/lib/Sema/SemaCXXCast.cpp b/lib/Sema/SemaCXXCast.cpp
index 21b1a73aa3..7b1e34a7c3 100644
--- a/lib/Sema/SemaCXXCast.cpp
+++ b/lib/Sema/SemaCXXCast.cpp
@@ -557,6 +557,15 @@ static TryCastResult TryStaticCast(Sema &Self, Expr *&SrcExpr,
 
   QualType SrcType = Self.Context.getCanonicalType(SrcExpr->getType());
 
+  // C++0x 5.2.9p9: A value of a scoped enumeration type can be explicitly
+  // converted to an integral type.
+  if (Self.getLangOptions().CPlusPlus0x && SrcType->isEnumeralType()) {
+    if (DestType->isIntegralType(Self.Context)) {
+      Kind = CK_IntegralCast;
+      return TC_Success;
+    }
+  }
+
   // Reverse integral promotion/conversion. All such conversions are themselves
   // again integral promotions or conversions and are thus already handled by
   // p2 (TryDirectInitialization above).
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 025f696e09..fa3a4047e5 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -5341,7 +5341,8 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
                      IdentifierInfo *Name, SourceLocation NameLoc,
                      AttributeList *Attr, AccessSpecifier AS,
                      MultiTemplateParamsArg TemplateParameterLists,
-                     bool &OwnedDecl, bool &IsDependent) {
+                     bool &OwnedDecl, bool &IsDependent, bool ScopedEnum,
+                     TypeResult UnderlyingType) {
   // If this is not a definition, it must have a name.
   assert((Name != 0 || TUK == TUK_Definition) &&
          "Nameless record must be a definition!");
@@ -5386,6 +5387,34 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
     }
   }
 
+  // Figure out the underlying type if this a enum declaration. We need to do
+  // this early, because it's needed to detect if this is an incompatible
+  // redeclaration.
+  llvm::PointerUnion<const Type*, TypeSourceInfo*> EnumUnderlying;
+
+  if (Kind == TTK_Enum) {
+    if (UnderlyingType.isInvalid() || (!UnderlyingType.get() && ScopedEnum))
+      // No underlying type explicitly specified, or we failed to parse the
+      // type, default to int.
+      EnumUnderlying = Context.IntTy.getTypePtr();
+    else if (UnderlyingType.get()) {
+      // C++0x 7.2p2: The type-specifier-seq of an enum-base shall name an
+      // integral type; any cv-qualification is ignored.
+      TypeSourceInfo *TI = 0;
+      QualType T = GetTypeFromParser(UnderlyingType.get(), &TI);
+      EnumUnderlying = TI;
+
+      SourceLocation UnderlyingLoc = TI->getTypeLoc().getBeginLoc();
+
+      if (!T->isDependentType() && !T->isIntegralType(Context)) {
+        Diag(UnderlyingLoc, diag::err_enum_invalid_underlying)
+          << T;
+        // Recover by falling back to int.
+        EnumUnderlying = Context.IntTy.getTypePtr();
+      }
+    }
+  }
+
   DeclContext *SearchDC = CurContext;
   DeclContext *DC = CurContext;
   bool isStdBadAlloc = false;
@@ -5622,6 +5651,38 @@ Decl *Sema::ActOnTag(Scope *S, unsigned TagSpec, TagUseKind TUK,
           }
         }
 
+        if (Kind == TTK_Enum && PrevTagDecl->getTagKind() == TTK_Enum) {
+          const EnumDecl *PrevEnum = cast<EnumDecl>(PrevTagDecl);
+
+          // All conflicts with previous declarations are recovered by
+          // returning the previous declaration.
+          if (ScopedEnum != PrevEnum->isScoped()) {
+            Diag(KWLoc, diag::err_enum_redeclare_scoped_mismatch)
+              << PrevEnum->isScoped();
+            Diag(PrevTagDecl->getLocation(), diag::note_previous_use);
+            return PrevTagDecl;
+          }
+          else if (EnumUnderlying && PrevEnum->isFixed()) {
+            QualType T;
+            if (TypeSourceInfo *TI = EnumUnderlying.dyn_cast<TypeSourceInfo*>())
+                T = TI->getType();
+            else
+                T = QualType(EnumUnderlying.get<const Type*>(), 0);
+
+            if (!Context.hasSameUnqualifiedType(T, PrevEnum->getIntegerType())) {
+              Diag(KWLoc, diag::err_enum_redeclare_type_mismatch);
+              Diag(PrevTagDecl->getLocation(), diag::note_previous_use);
+