fix PR3459: improve compatibility with gcc when checking for constant exprs

llvm-svn: 63517
diff --git a/clang/test/Sema/struct-decl.c b/clang/test/Sema/struct-decl.c
new file mode 100644
index 0000000..cacd847
--- /dev/null
+++ b/clang/test/Sema/struct-decl.c
@@ -0,0 +1,10 @@
+// RUN: clang -fsyntax-only -verify %s
+
+// PR3459
+struct bar {
+	char n[1];
+};
+
+struct foo {
+	char name[(int)&((struct bar *)0)->n];
+};