[Bug libstdc++/56677] [ratio] : ratio_multiply, ratio_divide, etc results doesnt verify as __is_ratio

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56677

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> 2013-03-21 15:35:46 UTC ---
That wouldn't help. The requirement is that the Period template argument is a
ratio. In GCC 4.7 ratio_divide is not a ratio.  Whether ratio_divide::type is a
ratio or not doesn't change the fact that ratio_divide is not a ratio and
therefore not a suitable template argument for duration.

To make it work we'd also need to make duration::period a typedef for either
_Period or _Period::type and alter the two static assertions to use period not
_Period, which is doable but I'm not convinced it's worth fixing in the stable
release branch.  I might look into it later.