libstdc++: Provide helpers to interoperate between __cmp_cat::_Ord and ordering types.

This patch adds two new internal helpers for ordering types:
* __cmp_cat::__ord to retrieve an internal _Ord value,
* __cmp_cat::__make<Ordering> to create an ordering from an _Ord value.

Conversions between ordering types are now handled by __cmp_cat::__make. As a
result, ordering types no longer need to befriend each other, only the new
helpers.

The __fp_weak_ordering implementation has also been simplified by:
* using the new helpers to convert partial_ordering to weak_ordering,
* using strong_ordering to weak_ordering conversion operator,
  for the __isnan_sign comparison,
* removing the unused __cat local variable.

Finally, the _Ncmp enum is removed, and the unordered enumerator is added
to the existing _Ord enum.

libstdc++-v3/ChangeLog:

	* libsupc++/compare (__cmp_cat::_Ord): Add unordered enumerator.
	(__cmp_cat::_Ncmp): Remove.
	(__cmp_cat::__ord, __cmp_cat::__make):  Define.
	(partial_ordering::partial_ordering(__cmp_cat::_Ncmp)): Remove.
	(operator<=>(__cmp_cat::__unspec, partial_ordering))
	(partial_ordering::unordered): Replace _Ncmp with _Ord.
	(std::partial_ordering, std::weak_ordering, std::strong_ordering):
	Befriend __ord and __make helpers, remove friend declartions for
	other orderings.
	(__compare::__fp_weak_ordering): Remove unused __cat variable.
	Simplify ordering conversions.

Reviewed-by: Jonathan Wakely <jwakely@redhat.com>
Signed-off-by: Tomasz Kamiński <tkaminsk@redhat.com>

0 files changed, 0 insertions, 0 deletions