Re: Is finding definitions of explicitly specialized template functions compiler-defined?

Here is an example with 3 files, containing a template
structure and also a template function. The header A.h
declares a template structure A with a default (i.e. for any
template parameter), inlined constructor implementation, and
also declares a template function f. The file main.cpp
contains some test code and also the default implementation
for f(). The file spec.cpp contains some explicitly
specialized stuff:

==== A.h ====

#include <iostream>
using std::cout;
using std::endl;

template <int> struct A {
  A () { cout << "default" << endl; }
};

template <int> void f ();

==== main.cpp ====

#include "A.h"

template <int> void f () { cout << "default" << endl; }

int main () {
  A<0> x;
  A<1> y;
  f<0>();
  f<1>();
  return 0;
}

==== spec.cpp ====

#include "A.h"

template<> A<1>::A () { cout << "A 1!" << endl; }
template<> void f<1> () { cout << "f 1!" << endl; }

==== END EXAMPLE ====

When using GCC, if I only compile main.cpp:

g++ main.cpp

Running the program produces the output:

default
default
default
default

Which makes sense. The default A::A() and f() implementations
print the word "default". If I simply add spec.cpp:

g++ main.cpp spec.cpp

The linker seems to know that since explicit specializations
of certain functions are present in other object files, it
should use them instead of the default implementations, and
the output is:

default
A 1!
default
f 1!

I have not tried this with any other compilers besides GCC
4.1.2. My question is: Is the behavior of the linker here
specific to GCC's linker? Or is it always guaranteed that if
one object file contains definitions for explicit
specializations of template functions, and that object file is
linked, then they will be used everywhere? The biggest reason
that I'm unsure is the linker has to do a small amount of
magic to make this work; falling back on the default
implementation if no explicit specializations were found, so
I'm wondering if that magic is defined by C++ or is a GCC
implementation detail.