[Bug libstdc++/58625] std::signbit always converts to double

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58625

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Paolo Carlini from comment #1)
> Weird that nobody noticed for so much time. Are there actual testcases for
> this? Or in practice it's just an optimization issue, not a correctness
> issue?

In some cases there could be a correctness issue with some rounding modes
though not that many.