clang-tests/gcc-4_2-testsuite/src/g++.dg/ext/visibility/redecl1.C

 // Test that we complain about redeclaration with different visibility

struct __attribute((visibility("hidden"))) B;    // { dg-warning "previous" }
struct __attribute((visibility("default"))) B;   // { dg-warning "visibility" }

__attribute ((visibility ("hidden"))) void f();  // { dg-warning "previous" }
__attribute ((visibility ("default"))) void f(); // { dg-warning "visibility" }