2 files changed, 63 insertions, 26 deletions

diff --git a/include/clang/Parse/Action.h b/include/clang/Parse/Action.h
index 5b57521..8c85ba6 100644
--- a/include/clang/Parse/Action.h
+++ b/include/clang/Parse/Action.h
@@ -637,18 +637,50 @@ public:
   // Expression Parsing Callbacks.
   //===--------------------------------------------------------------------===//
 
-  /// \brief Notifies the action when the parser is processing an unevaluated
-  /// operand.
+  /// \brief Describes how the expressions currently being parsed are
+  /// evaluated at run-time, if at all.
+  enum ExpressionEvaluationContext {
+    /// \brief The current expression and its subexpressions occur within an
+    /// unevaluated operand (C++0x [expr]p8), such as a constant expression
+    /// or the subexpression of \c sizeof, where the type or the value of the
+    /// expression may be significant but no code will be generated to evaluate 
+    /// the value of the expression at run time.
+    Unevaluated,
+    
+    /// \brief The current expression is potentially evaluated at run time, 
+    /// which means that code may be generated to evaluate the value of the 
+    /// expression at run time.
+    PotentiallyEvaluated,
+    
+    /// \brief The current expression may be potentially evaluated or it may
+    /// be unevaluated, but it is impossible to tell from the lexical context.
+    /// This evaluation context is used primary for the operand of the C++
+    /// \c typeid expression, whose argument is potentially evaluated only when
+    /// it is an lvalue of polymorphic class type (C++ [basic.def.odr]p2).
+    PotentiallyPotentiallyEvaluated
+  };
+  
+  /// \brief The parser is entering a new expression evaluation context.
   ///
-  /// \param UnevaluatedOperand true to indicate that the parser is processing
-  /// an unevaluated operand, or false otherwise.
+  /// \param NewContext is the new expression evaluation context.
   ///
-  /// \returns whether the the action module was previously in an unevaluated
-  /// operand.
-  virtual bool setUnevaluatedOperand(bool UnevaluatedOperand) { 
-    return false;
+  /// \returns the previous expression evaluation context.
+  virtual ExpressionEvaluationContext 
+  PushExpressionEvaluationContext(ExpressionEvaluationContext NewContext) {
+    return PotentiallyEvaluated;
   }
   
+  /// \brief The parser is existing an expression evaluation context.
+  ///
+  /// \param OldContext the expression evaluation context that the parser is
+  /// leaving.
+  ///
+  /// \param NewContext the expression evaluation context that the parser is
+  /// returning to.
+  virtual void 
+  PopExpressionEvaluationContext(ExpressionEvaluationContext OldContext,
+                                 ExpressionEvaluationContext NewContext) { }
+  
   // Primary Expressions.
 
   /// \brief Retrieve the source range that corresponds to the given
@@ -1891,6 +1923,29 @@ public:
   virtual void print(llvm::raw_ostream &OS) const;
 };  
   
+/// \brief RAII object that enters a new expression evaluation context.
+class EnterExpressionEvaluationContext {    
+  /// \brief The action object.
+  Action &Actions;
+  
+  /// \brief The previous expression evaluation context.
+  Action::ExpressionEvaluationContext PrevContext;
+
+  /// \brief The current expression evaluation context.
+  Action::ExpressionEvaluationContext CurContext;
+
+public:
+  EnterExpressionEvaluationContext(Action &Actions,
+                              Action::ExpressionEvaluationContext NewContext) 
+    : Actions(Actions), CurContext(NewContext) { 
+      PrevContext = Actions.PushExpressionEvaluationContext(NewContext);
+  }
+    
+  ~EnterExpressionEvaluationContext() {
+    Actions.PopExpressionEvaluationContext(CurContext, PrevContext);
+  }
+};
+  
 }  // end namespace clang
 
 #endif
diff --git a/include/clang/Parse/Parser.h b/include/clang/Parse/Parser.h
index 75458d8..7558793 100644
--- a/include/clang/Parse/Parser.h
+++ b/include/clang/Parse/Parser.h
@@ -104,24 +104,6 @@ class Parser {
       GreaterThanIsOperator = OldGreaterThanIsOperator;
     }
   };
-
-  /// \brief RAII object that enters an unevaluated operand.
-  class EnterUnevaluatedOperand {    
-    /// \brief The action object.
-    Action &Actions;
-    
-    /// \brief Whether we were previously within an unevaluated operand.
-    bool PreviouslyInUnevaluatedOperand;
-    
-  public:
-    explicit EnterUnevaluatedOperand(Action &Actions) : Actions(Actions) { 
-      PreviouslyInUnevaluatedOperand = Actions.setUnevaluatedOperand(true);
-    }
-    
-    ~EnterUnevaluatedOperand() {
-      Actions.setUnevaluatedOperand(PreviouslyInUnevaluatedOperand);
-    }
-  };
   
 public:
   Parser(Preprocessor &PP, Action &Actions);