http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57043
Jason Merrill <jason at gcc dot gnu.org> changed:
What |Removed |Added
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CC| |jason at gcc dot gnu.org
--- Comment #3 from Jason Merrill <jason at gcc dot gnu.org> ---
OK, this is puzzling.
The issue is that GCC can't tell that the first pow is more specialized than
the second; deduction happens fine, but when we substitute in Tp(1) for Tp(2)
and Up we still have complex<typename promote_2<Tp(1), Tp(1)>::type> for the
return type, which looks different from complex<Tp(1)>, so deduction fails and
we decide it isn't more specialized.
I can't figure out what interpretation of the standard clang/EDG are using to
make this work. Are they actually instantiating promote_2? That doesn't seem
to be it, as they also accept the following, which seems clearly unordered to
me:
template<typename D> struct complex { };
template <class T> struct promote_1 { typedef T type; };
template<typename T, typename U> struct promote_2 { typedef T type; };
template<typename Tp>
complex<typename promote_1<Tp>::type>
pow(const complex<Tp>& x, const complex<Tp>& y);
template<typename Tp, typename Up>
complex<typename promote_2<Tp, Up>::type>
pow(const complex<Tp>& x, const complex<Up>& y);
complex<double> (*powcc)(const complex<double>&, const complex<double>&) = pow;
