clang-tests/gcc-4_2-testsuite/src/g++.old-deja/g++.ns/lookup5.C

// { dg-do assemble  }
namespace A{
  void f();
}

namespace B{
  using namespace A;
  void f(int);			// { dg-error "" } referenced below
}

using namespace B;

void g()
{
  ::f();               // { dg-error "" } A::f is not found
}

using namespace A;

void g1()
{
  ::f();               // ok, it is found now
}