6 files changed, 71 insertions, 3 deletions

diff --git a/clang/include/clang/AST/ExprCXX.h b/clang/include/clang/AST/ExprCXX.h
index eea15effac3..bd7d3f09c38 100644
--- a/clang/include/clang/AST/ExprCXX.h
+++ b/clang/include/clang/AST/ExprCXX.h
@@ -2571,6 +2571,61 @@ public:
   virtual child_iterator child_end();
 };
 
+/// \brief Represents a C++0x pack expansion that produces a sequence of 
+/// expressions.
+///
+/// A pack expansion expression contains a pattern (which itself is an
+/// expression) followed by an ellipsis. For example:
+///
+/// \code
+/// template<typename F, typename ...Types>
+/// void forward(F f, Types &&...args) {
+///   f(static_cast<Types&&>(args)...);
+/// }
+/// \endcode
+///
+/// Here, the argument to the function object \c f is a pack expansion whose
+/// pattern is \c static_cast<Types&&>(args). When the \c forward function 
+/// template is instantiated, the pack expansion will instantiate to zero or
+/// or more function arguments to the function object \c f.
+class PackExpansionExpr : public Expr {
+  SourceLocation EllipsisLoc;
+  Stmt *Pattern;
+  
+  friend class ASTStmtReader;
+  
+public:
+  PackExpansionExpr(QualType T, Expr *Pattern, SourceLocation EllipsisLoc)
+    : Expr(PackExpansionExprClass, T, Pattern->getValueKind(), 
+           Pattern->getObjectKind(), /*TypeDependent=*/true, 
+           /*ValueDependent=*/true, /*ContainsUnexpandedParameterPack=*/false),
+      EllipsisLoc(EllipsisLoc),
+      Pattern(Pattern) { }
+
+  PackExpansionExpr(EmptyShell Empty) : Expr(PackExpansionExprClass, Empty) { }
+  
+  /// \brief Retrieve the pattern of the pack expansion.
+  Expr *getPattern() { return reinterpret_cast<Expr *>(Pattern); }
+
+  /// \brief Retrieve the pattern of the pack expansion.
+  const Expr *getPattern() const { return reinterpret_cast<Expr *>(Pattern); }
+
+  /// \brief Retrieve the location of the ellipsis that describes this pack
+  /// expansion.
+  SourceLocation getEllipsisLoc() const { return EllipsisLoc; }
+  
+  virtual SourceRange getSourceRange() const;
+
+  static bool classof(const Stmt *T) {
+    return T->getStmtClass() == PackExpansionExprClass;
+  }
+  static bool classof(const PackExpansionExpr *) { return true; }
+  
+  // Iterators
+  virtual child_iterator child_begin();
+  virtual child_iterator child_end();
+};
+  
 inline ExplicitTemplateArgumentList &OverloadExpr::getExplicitTemplateArgs() {
   if (isa<UnresolvedLookupExpr>(this))
     return cast<UnresolvedLookupExpr>(this)->getExplicitTemplateArgs();
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index 435ebc65ea4..258e186b7ac 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -1820,6 +1820,7 @@ DEF_TRAVERSE_STMT(UnaryOperator, { })
 DEF_TRAVERSE_STMT(BinaryOperator, { })
 DEF_TRAVERSE_STMT(CompoundAssignOperator, { })
 DEF_TRAVERSE_STMT(CXXNoexceptExpr, { })
+DEF_TRAVERSE_STMT(PackExpansionExpr, { })
 
 // These literals (all of them) do not need any action.
 DEF_TRAVERSE_STMT(IntegerLiteral, { })
diff --git a/clang/include/clang/Basic/DiagnosticSemaKinds.td b/clang/include/clang/Basic/DiagnosticSemaKinds.td
index f2d3c0085cd..eb123b9fe9f 100644
--- a/clang/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/clang/include/clang/Basic/DiagnosticSemaKinds.td
@@ -1871,7 +1871,7 @@ def err_ellipsis_in_declarator_not_parameter : Error<
 
 // Unsupported variadic templates features
 def err_pack_expansion_unsupported : Error<
-  "clang does not yet support %select{non-type|template}0 pack expansions">;
+  "clang does not yet support template pack expansions">;
 def err_pack_expansion_instantiation_unsupported : Error<
   "clang cannot yet instantiate pack expansions">;
 def err_pack_expansion_mismatch_unsupported : Error<
diff --git a/clang/include/clang/Basic/StmtNodes.td b/clang/include/clang/Basic/StmtNodes.td
index 0e2fb575e64..890f02b75d3 100644
--- a/clang/include/clang/Basic/StmtNodes.td
+++ b/clang/include/clang/Basic/StmtNodes.td
@@ -111,6 +111,7 @@ def OverloadExpr : DStmt<Expr, 1>;
 def UnresolvedLookupExpr : DStmt<OverloadExpr>;
 def UnresolvedMemberExpr : DStmt<OverloadExpr>;
 def CXXNoexceptExpr : DStmt<Expr>;
+def PackExpansionExpr : DStmt<Expr>;
 
 // Obj-C Expressions.
 def ObjCStringLiteral : DStmt<Expr>;
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 57f480f95df..05bb1258c1b 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -3279,7 +3279,7 @@ public:
   ParsedTemplateArgument ActOnPackExpansion(const ParsedTemplateArgument &Arg,
                                             SourceLocation EllipsisLoc);
 
-  /// \brief Invoked when parsing a type follows by an ellipsis, which
+  /// \brief Invoked when parsing a type followed by an ellipsis, which
   /// creates a pack expansion.
   ///
   /// \param Type The type preceding the ellipsis, which will become
@@ -3293,6 +3293,15 @@ public:
   TypeSourceInfo *CheckPackExpansion(TypeSourceInfo *Pattern,
                                      SourceLocation EllipsisLoc);
   
+  /// \brief Invoked when parsing an expression followed by an ellipsis, which
+  /// creates a pack expansion.
+  ///
+  /// \param Pattern The expression preceding the ellipsis, which will become
+  /// the pattern of the pack expansion.
+  ///
+  /// \param EllipsisLoc The location of the ellipsis.
+  ExprResult ActOnPackExpansion(Expr *Pattern, SourceLocation EllipsisLoc);
+  
   /// \brief Determine whether we could expand a pack expansion with the
   /// given set of parameter packs into separate arguments by repeatedly
   /// transforming the pattern.
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index 8665fb64656..fcc8d53d42b 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -929,7 +929,9 @@ namespace clang {
       EXPR_CXX_NOEXCEPT,          // CXXNoexceptExpr
 
       EXPR_OPAQUE_VALUE,          // OpaqueValueExpr
-      EXPR_BINARY_TYPE_TRAIT      // BinaryTypeTraitExpr
+      EXPR_BINARY_TYPE_TRAIT,     // BinaryTypeTraitExpr
+      
+      EXPR_PACK_EXPANSION         // PackExpansionExpr
     };
 
     /// \brief The kinds of designators that can occur in a