Add Expr::EvaluateAsLValue which will (believe it or not) try to evaluate an Expr as an LValue.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@68763 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 643e066..327fff0 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -1651,6 +1651,12 @@
   return true;
 }
 
+bool Expr::EvaluateAsLValue(EvalResult &Result, ASTContext &Ctx) const {
+  EvalInfo Info(Ctx, Result);
+
+  return EvaluateLValue(this, Result.Val, Info) && !Result.HasSideEffects;
+}
+
 /// isEvaluatable - Call Evaluate to see if this expression can be constant
 /// folded, but discard the result.
 bool Expr::isEvaluatable(ASTContext &Ctx) const {