Emit the correct diagnostics when we constant fold an array size to a negative value.

llvm-svn: 65023
diff --git a/clang/test/Sema/const-eval.c b/clang/test/Sema/const-eval.c
index 4fd2a55..af785e4 100644
--- a/clang/test/Sema/const-eval.c
+++ b/clang/test/Sema/const-eval.c
@@ -34,3 +34,7 @@
 int g17[(3?:1) - 2]; 
 
 EVAL_EXPR(18, ((int)((void*)10 + 10)) == 20 ? 1 : -1);
+
+struct s {
+  int a[(int)-1.0f]; // expected-error {{array size is negative}}
+};