http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51936
--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> 2012-01-21 20:23:27 UTC --- The standard says in [expr.reinterpret.cast] "A function pointer can be explicitly converted to a function pointer of a different type. The effect of calling a function through a pointer to a function type (8.3.5) that is not the same as the type used in the definition of the function is undefined." So I think the program has undefined behaviour. Because you never call asd<int,0> as part of a valid expression it doesn't need to be instantiated. Clang++ fails in the same way as G++ 4.6, but it works with G++ 4.7
