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diff --git a/include/clang/AST/EvaluatedExprVisitor.h b/include/clang/AST/EvaluatedExprVisitor.h
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+//===--- EvaluatedExprVisitor.h - Evaluated expression visitor --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines the EvaluatedExprVisitor class template, which visits
+//  the potentially-evaluated subexpressions of a potentially-evaluated
+//  expression.
+//
+//===----------------------------------------------------------------------===//
+#ifndef LLVM_CLANG_AST_EVALUATEDEXPRVISITOR_H
+#define LLVM_CLANG_AST_EVALUATEDEXPRVISITOR_H
+
+#include "clang/AST/StmtVisitor.h"
+#include "clang/AST/DeclCXX.h"
+#include "clang/AST/Expr.h"
+#include "clang/AST/ExprCXX.h"
+
+namespace clang {
+  
+class ASTContext;
+  
+/// \begin Given a potentially-evaluated expression, this visitor visits all
+/// of its potentially-evaluated subexpressions, recursively.
+template<typename ImplClass>
+class EvaluatedExprVisitor : public StmtVisitor<ImplClass> {
+  ASTContext &Context;
+  
+public:
+  explicit EvaluatedExprVisitor(ASTContext &Context) : Context(Context) { }
+  
+  // Expressions that have no potentially-evaluated subexpressions (but may have
+  // other sub-expressions).
+  void VisitDeclRefExpr(DeclRefExpr *E) { }
+  void VisitOffsetOfExpr(OffsetOfExpr *E) { }
+  void VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr *E) { }
+  void VisitBlockExpr(BlockExpr *E) { }
+  void VisitCXXUuidofExpr(CXXUuidofExpr *E) { }  
+  void VisitCXXNoexceptExpr(CXXNoexceptExpr *E) { }
+  
+  void VisitMemberExpr(MemberExpr *E) {
+    // Only the base matters.
+    return this->Visit(E->getBase());
+  }
+  
+  void VisitChooseExpr(ChooseExpr *E) {
+    // Only the selected subexpression matters; the other one is not evaluated.
+    return this->Visit(E->getChosenSubExpr(Context));
+  }
+                 
+  void VisitDesignatedInitExpr(DesignatedInitExpr *E) {
+    // Only the actual initializer matters; the designators are all constant
+    // expressions.
+    return this->Visit(E->getInit());
+  }
+  
+  void VisitCXXTypeidExpr(CXXTypeidExpr *E) {
+    // typeid(expression) is potentially evaluated when the argument is
+    // a glvalue of polymorphic type. (C++ 5.2.8p2-3)
+    if (!E->isTypeOperand() && E->Classify(Context).isGLValue())
+      if (const RecordType *Record 
+                 = E->getExprOperand()->getType()->template getAs<RecordType>())
+        if (cast<CXXRecordDecl>(Record->getDecl())->isPolymorphic())
+          return this->Visit(E->getExprOperand());
+  }
+  
+  /// \brief The basis case walks all of the children of the statement or
+  /// expression, assuming they are all potentially evaluated.
+  void VisitStmt(Stmt *S) {
+    for (Stmt::child_range C = S->children(); C; ++C)
+      if (*C)
+        this->Visit(*C);
+  }
+};
+
+}
+
+#endif // LLVM_CLANG_AST_EVALUATEDEXPRVISITOR_H