Problems with ....hmm, linker perhaps

From: Patrick Kowalzick (Patrick.Kowalzick_at_cern.ch)
Date: 10/29/04 

Date: Fri, 29 Oct 2004 13:23:04 +0200

Dear all,

IMO the following program is legal and should compile.

//***** code start *********
// Definition of class A
template <typename T> struct A
{
 typedef T value_type;
};

// Definition of class B
template <typename> struct B {};

// Function foo
// returntype important !
template <typename T>
B<typename T::value_type> foo()
{
 return B<typename T::value_type>();
};

int main()
{
 typedef B< int >( * ptr )(); // Function pointer

 ptr foo_ptr = foo< A<int> >; // Initialization of function pointer

 return 0;
}
//***** code end *********

It builds fine with g++ and MSVC7.1, but the latter one fails linking:

unresolved external symbol "struct B<int> __cdecl foo<struct A<int> >(void)"
(??$foo@U?$A@H@@@@YA?AU?$B@H@@XZ) referenced in function _main

what I do not really understand. It is getting a lit more weird now. If I
change

ptr foo_ptr = foo< A<int> >;

to

ptr foo_ptr ;
foo_ptr = foo< A<int> >;

it compiles and links fine as well with MSVC 7.1.

Before I blame anyone, I want to ask if I overlooked something? IMO the code
is fine.

Regards,
Patrick

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