Fix assertion in constant expression evaluation. The LHS of a floating-point
binary operator isn't an rvalue if it's an assignment operator.

llvm-svn: 143250
diff --git a/clang/test/Sema/const-eval.c b/clang/test/Sema/const-eval.c
index bdb40ae..6dcc6db 100644
--- a/clang/test/Sema/const-eval.c
+++ b/clang/test/Sema/const-eval.c
@@ -86,3 +86,5 @@
   double _Complex  P;
   float _Complex  P2 = 3.3f + P;
 }
+
+double d = (d = 0.0); // expected-error {{not a compile-time constant}}