[Bug c++/18474] Unary plus/minus lvalueness not diagnosed in templates

[pinskia at gcc dot gnu.org via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=18474

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note this is only invalid as n (if declared correctly) was not depedent so the
operator lookup would be bound at definition time.

That is the following needs to be accepted still:
template <class T>
void g(void)
{
  T n;
  -n = 0;
  +n = 0;
}