Notes from October 2002 meeting:

Yes, this example is valid. See 9.12 [dcl.link] paragraph 6, which contains a similar example with the definition in the global namespace instead. There is only one f, so the question of whether the definition is in the global namespace or the namespace N is not meaningful. The same function is found by name lookup whether it is found from the declaration in namespace N or the declaration in the global namespace, or both (9.9.4 [namespace.udir] paragraph 4) .

Is this code valid:

  extern "C" void f();

  namespace N
  {
    int var;
    extern "C" void f(){ var = 10; }
  }

The two declarations of f refer to the same external function, but is this a valid way to declare and define f?

And is the definition of f considered to be in namespace N or in the global namespace?