Ignore No-op casts when evaluating lvalue expressions. Fixes PR5122.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@83267 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprConstant.cpp b/lib/AST/ExprConstant.cpp
index 2aefae6..94d2299 100644
--- a/lib/AST/ExprConstant.cpp
+++ b/lib/AST/ExprConstant.cpp
@@ -180,6 +180,16 @@
     { return Visit(E->getSubExpr()); }
   APValue VisitChooseExpr(const ChooseExpr *E)
     { return Visit(E->getChosenSubExpr(Info.Ctx)); }
+
+  APValue VisitCastExpr(CastExpr *E) {
+    switch (E->getCastKind()) {
+    default:
+      return APValue();
+
+    case CastExpr::CK_NoOp:
+      return Visit(E->getSubExpr());
+    }
+  }
   // FIXME: Missing: __real__, __imag__
 };
 } // end anonymous namespace