clang-tests/gcc-4_2-testsuite/src/g++.dg/ext/visibility/visibility-6.C

/* Test visibility attribute on definition of global variable that has
   already had a forward declaration. */
/* { dg-require-visibility "" }
/* { dg-final { scan-hidden "xyzzy" } } */

extern int xyzzy;

int 
__attribute__((visibility ("hidden")))
xyzzy = 5;