Index: cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h
===================================================================
--- cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h
+++ cfe/trunk/include/clang/AST/EvaluatedExprVisitor.h
@@ -26,29 +26,31 @@
   
 /// \brief 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;
-  
+template<template <typename> class Ptr, typename ImplClass>
+class EvaluatedExprVisitorBase : public StmtVisitorBase<Ptr, ImplClass, void> {
+  const ASTContext &Context;
+
 public:
-  explicit EvaluatedExprVisitor(ASTContext &Context) : Context(Context) { }
-  
+#define PTR(CLASS) typename Ptr<CLASS>::type
+
+  explicit EvaluatedExprVisitorBase(const 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 VisitUnaryExprOrTypeTraitExpr(UnaryExprOrTypeTraitExpr *E) { }
-  void VisitExpressionTraitExpr(ExpressionTraitExpr *E) { }
-  void VisitBlockExpr(BlockExpr *E) { }
-  void VisitCXXUuidofExpr(CXXUuidofExpr *E) { }  
-  void VisitCXXNoexceptExpr(CXXNoexceptExpr *E) { }
-  
-  void VisitMemberExpr(MemberExpr *E) {
+  void VisitDeclRefExpr(PTR(DeclRefExpr) E) { }
+  void VisitOffsetOfExpr(PTR(OffsetOfExpr) E) { }
+  void VisitUnaryExprOrTypeTraitExpr(PTR(UnaryExprOrTypeTraitExpr) E) { }
+  void VisitExpressionTraitExpr(PTR(ExpressionTraitExpr) E) { }
+  void VisitBlockExpr(PTR(BlockExpr) E) { }
+  void VisitCXXUuidofExpr(PTR(CXXUuidofExpr) E) { }
+  void VisitCXXNoexceptExpr(PTR(CXXNoexceptExpr) E) { }
+
+  void VisitMemberExpr(PTR(MemberExpr) E) {
     // Only the base matters.
     return this->Visit(E->getBase());
   }
-  
-  void VisitChooseExpr(ChooseExpr *E) {
+
+  void VisitChooseExpr(PTR(ChooseExpr) E) {
     // Don't visit either child expression if the condition is dependent.
     if (E->getCond()->isValueDependent())
       return;
@@ -56,7 +58,7 @@
     return this->Visit(E->getChosenSubExpr());
   }
 
-  void VisitGenericSelectionExpr(GenericSelectionExpr *E) {
+  void VisitGenericSelectionExpr(PTR(GenericSelectionExpr) E) {
     // The controlling expression of a generic selection is not evaluated.
 
     // Don't visit either child expression if the condition is type-dependent.
@@ -67,23 +69,23 @@
     return this->Visit(E->getResultExpr());
   }
 
-  void VisitDesignatedInitExpr(DesignatedInitExpr *E) {
+  void VisitDesignatedInitExpr(PTR(DesignatedInitExpr) E) {
     // Only the actual initializer matters; the designators are all constant
     // expressions.
     return this->Visit(E->getInit());
   }
 
-  void VisitCXXTypeidExpr(CXXTypeidExpr *E) {
+  void VisitCXXTypeidExpr(PTR(CXXTypeidExpr) E) {
     if (E->isPotentiallyEvaluated())
       return this->Visit(E->getExprOperand());
   }
 
-  void VisitCallExpr(CallExpr *CE) {
+  void VisitCallExpr(PTR(CallExpr) CE) {
     if (!CE->isUnevaluatedBuiltinCall(Context))
       return static_cast<ImplClass*>(this)->VisitExpr(CE);
   }
 
-  void VisitLambdaExpr(LambdaExpr *LE) {
+  void VisitLambdaExpr(PTR(LambdaExpr) LE) {
     // Only visit the capture initializers, and not the body.
     for (LambdaExpr::capture_init_iterator I = LE->capture_init_begin(),
                                            E = LE->capture_init_end();
@@ -94,11 +96,31 @@
 
   /// \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)
+  void VisitStmt(PTR(Stmt) S) {
+    for (auto C = S->children(); C; ++C)
       if (*C)
         this->Visit(*C);
   }
+
+#undef PTR
+};
+
+/// EvaluatedExprVisitor - This class visits 'Expr *'s
+template<typename ImplClass>
+class EvaluatedExprVisitor
+ : public EvaluatedExprVisitorBase<make_ptr, ImplClass> {
+public:
+  explicit EvaluatedExprVisitor(const ASTContext &Context) :
+    EvaluatedExprVisitorBase<make_ptr, ImplClass>(Context) { }
+};
+
+/// ConstEvaluatedExprVisitor - This class visits 'const Expr *'s.
+template<typename ImplClass>
+class ConstEvaluatedExprVisitor
+ : public EvaluatedExprVisitorBase<make_const_ptr, ImplClass> {
+public:
+  explicit ConstEvaluatedExprVisitor(const ASTContext &Context) :
+    EvaluatedExprVisitorBase<make_const_ptr, ImplClass>(Context) { }
 };
 
 }
Index: cfe/trunk/include/clang/AST/Expr.h
===================================================================
--- cfe/trunk/include/clang/AST/Expr.h
+++ cfe/trunk/include/clang/AST/Expr.h
@@ -598,7 +598,7 @@
 
   /// \brief Determine whether this expression involves a call to any function
   /// that is not trivial.
-  bool hasNonTrivialCall(ASTContext &Ctx);
+  bool hasNonTrivialCall(const ASTContext &Ctx) const;
 
   /// EvaluateKnownConstInt - Call EvaluateAsRValue and return the folded
   /// integer. This must be called on an expression that constant folds to an
@@ -2273,7 +2273,7 @@
 
   /// \brief Returns \c true if this is a call to a builtin which does not
   /// evaluate side-effects within its arguments.
-  bool isUnevaluatedBuiltinCall(ASTContext &Ctx) const;
+  bool isUnevaluatedBuiltinCall(const ASTContext &Ctx) const;
 
   /// getCallReturnType - Get the return type of the call expr. This is not
   /// always the type of the expr itself, if the return type is a reference
Index: cfe/trunk/lib/AST/Expr.cpp
===================================================================
--- cfe/trunk/lib/AST/Expr.cpp
+++ cfe/trunk/lib/AST/Expr.cpp
@@ -1238,7 +1238,7 @@
   return FDecl->getBuiltinID();
 }
 
-bool CallExpr::isUnevaluatedBuiltinCall(ASTContext &Ctx) const {
+bool CallExpr::isUnevaluatedBuiltinCall(const ASTContext &Ctx) const {
   if (unsigned BI = getBuiltinCallee())
     return Ctx.BuiltinInfo.isUnevaluated(BI);
   return false;
@@ -3136,21 +3136,21 @@
 
 namespace {
   /// \brief Look for a call to a non-trivial function within an expression.
-  class NonTrivialCallFinder : public EvaluatedExprVisitor<NonTrivialCallFinder>
+  class NonTrivialCallFinder : public ConstEvaluatedExprVisitor<NonTrivialCallFinder>
   {
-    typedef EvaluatedExprVisitor<NonTrivialCallFinder> Inherited;
-    
+    typedef ConstEvaluatedExprVisitor<NonTrivialCallFinder> Inherited;
+
     bool NonTrivial;
     
   public:
-    explicit NonTrivialCallFinder(ASTContext &Context) 
+    explicit NonTrivialCallFinder(const ASTContext &Context)
       : Inherited(Context), NonTrivial(false) { }
     
     bool hasNonTrivialCall() const { return NonTrivial; }
-    
-    void VisitCallExpr(CallExpr *E) {
-      if (CXXMethodDecl *Method
-          = dyn_cast_or_null<CXXMethodDecl>(E->getCalleeDecl())) {
+
+    void VisitCallExpr(const CallExpr *E) {
+      if (const CXXMethodDecl *Method
+          = dyn_cast_or_null<const CXXMethodDecl>(E->getCalleeDecl())) {
         if (Method->isTrivial()) {
           // Recurse to children of the call.
           Inherited::VisitStmt(E);
@@ -3160,8 +3160,8 @@
       
       NonTrivial = true;
     }
-    
-    void VisitCXXConstructExpr(CXXConstructExpr *E) {
+
+    void VisitCXXConstructExpr(const CXXConstructExpr *E) {
       if (E->getConstructor()->isTrivial()) {
         // Recurse to children of the call.
         Inherited::VisitStmt(E);
@@ -3170,8 +3170,8 @@
       
       NonTrivial = true;
     }
-    
-    void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
+
+    void VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) {
       if (E->getTemporary()->getDestructor()->isTrivial()) {
         Inherited::VisitStmt(E);
         return;
@@ -3182,7 +3182,7 @@
   };
 }
 
-bool Expr::hasNonTrivialCall(ASTContext &Ctx) {
+bool Expr::hasNonTrivialCall(const ASTContext &Ctx) const {
   NonTrivialCallFinder Finder(Ctx);
   Finder.Visit(this);
   return Finder.hasNonTrivialCall();  
Index: cfe/trunk/lib/CodeGen/CGClass.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGClass.cpp
+++ cfe/trunk/lib/CodeGen/CGClass.cpp
@@ -370,25 +370,25 @@
 
   /// A visitor which checks whether an initializer uses 'this' in a
   /// way which requires the vtable to be properly set.
-  struct DynamicThisUseChecker : EvaluatedExprVisitor<DynamicThisUseChecker> {
-    typedef EvaluatedExprVisitor<DynamicThisUseChecker> super;
+  struct DynamicThisUseChecker : ConstEvaluatedExprVisitor<DynamicThisUseChecker> {
+    typedef ConstEvaluatedExprVisitor<DynamicThisUseChecker> super;
 
     bool UsesThis;
 
-    DynamicThisUseChecker(ASTContext &C) : super(C), UsesThis(false) {}
+    DynamicThisUseChecker(const ASTContext &C) : super(C), UsesThis(false) {}
 
     // Black-list all explicit and implicit references to 'this'.
     //
     // Do we need to worry about external references to 'this' derived
     // from arbitrary code?  If so, then anything which runs arbitrary
     // external code might potentially access the vtable.
-    void VisitCXXThisExpr(CXXThisExpr *E) { UsesThis = true; }
+    void VisitCXXThisExpr(const CXXThisExpr *E) { UsesThis = true; }
   };
 }
 
 static bool BaseInitializerUsesThis(ASTContext &C, const Expr *Init) {
   DynamicThisUseChecker Checker(C);
-  Checker.Visit(const_cast<Expr*>(Init));
+  Checker.Visit(Init);
   return Checker.UsesThis;
 }
 
Index: cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
===================================================================
--- cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
+++ cfe/trunk/lib/Sema/AnalysisBasedWarnings.cpp
@@ -574,28 +574,29 @@
 /// ContainsReference - A visitor class to search for references to
 /// a particular declaration (the needle) within any evaluated component of an
 /// expression (recursively).
-class ContainsReference : public EvaluatedExprVisitor<ContainsReference> {
+class ContainsReference : public ConstEvaluatedExprVisitor<ContainsReference> {
   bool FoundReference;
   const DeclRefExpr *Needle;
 
 public:
+  typedef ConstEvaluatedExprVisitor<ContainsReference> Inherited;
+
   ContainsReference(ASTContext &Context, const DeclRefExpr *Needle)
-    : EvaluatedExprVisitor<ContainsReference>(Context),
-      FoundReference(false), Needle(Needle) {}
+    : Inherited(Context), FoundReference(false), Needle(Needle) {}
 
-  void VisitExpr(Expr *E) {
+  void VisitExpr(const Expr *E) {
     // Stop evaluating if we already have a reference.
     if (FoundReference)
       return;
 
-    EvaluatedExprVisitor<ContainsReference>::VisitExpr(E);
+    Inherited::VisitExpr(E);
   }
 
-  void VisitDeclRefExpr(DeclRefExpr *E) {
+  void VisitDeclRefExpr(const DeclRefExpr *E) {
     if (E == Needle)
       FoundReference = true;
     else
-      EvaluatedExprVisitor<ContainsReference>::VisitDeclRefExpr(E);
+      Inherited::VisitDeclRefExpr(E);
   }
 
   bool doesContainReference() const { return FoundReference; }
@@ -854,7 +855,7 @@
         return false;
 
       ContainsReference CR(S.Context, DRE);
-      CR.Visit(const_cast<Expr*>(Initializer));
+      CR.Visit(Initializer);
       if (CR.doesContainReference()) {
         S.Diag(DRE->getLocStart(),
                diag::warn_uninit_self_reference_in_init)
Index: cfe/trunk/lib/Sema/SemaExprCXX.cpp
===================================================================
--- cfe/trunk/lib/Sema/SemaExprCXX.cpp
+++ cfe/trunk/lib/Sema/SemaExprCXX.cpp
@@ -20,7 +20,6 @@
 #include "clang/AST/CXXInheritance.h"
 #include "clang/AST/CharUnits.h"
 #include "clang/AST/DeclObjC.h"
-#include "clang/AST/EvaluatedExprVisitor.h"
 #include "clang/AST/ExprCXX.h"
 #include "clang/AST/ExprObjC.h"
 #include "clang/AST/RecursiveASTVisitor.h"