reduced_test.cpp

extern "C" int pthread_once(int *, void());
int a(int *c, void __func()) { return pthread_once(c, __func); }
namespace b {
struct A {
  int e;
};
extern "C" void __once_proxy();
template < typename f > void d(A &c, f ) { a(&c.e, __once_proxy); }
}
void h();
main() {
  b::A g;
  d(g, h);
}