[v3 PATCH] PR libstdc++/77288 and the newest proposed resolution for LWG 2756

[Ville Voutilainen]

On 21 September 2016 at 12:31, Jonathan Wakely <jwakely@redhat.com> wrote:
> On 06/09/16 09:00 +0300, Ville Voutilainen wrote:
>>
>>    PR libstdc++/77288
>>    * include/std/optional (__is_optional_impl, __is_optional): Remove.
>>    (__converts_from_optional, __assigns_from_optional): New.
>>    (optional(_Up&&)): Use is_same instead of __is_optional.
>>    (optional(const optional<_Up>&)): Constrain with
>>    __converts_from_optional.
>>    (optional(optional<_Up>&&)): Likewise.
>>    (operator=(_Up&&)): Use is_same instead of __is_optional, check
>>    is_same and is_scalar.
>>    (operator=(const optional<_Up>&)): Constrain with
>>    __converts_from_optional and __assigns_from_optional.
>>    (operator=(optional<_Up>&&)): Likewise.
>>    * testsuite/20_util/optional/77288.cc: New.
>>    * testsuite/20_util/optional/cons/value.cc: Adjust.
>
>
> OK for trunk, thanks.

Thanks, applied - I will cook up a separate patch for making the same
fix for experimental::optional.
The plan is to then backport that one to the gcc-6 branch.