On 09/08/16 02:22 +0300, Ville Voutilainen wrote:
Implement the latest proposed resolution of LWG 2756. * include/std/optional (Optional_base(const _Tp&)) (Optional_base(_Tp&&), using _Base::_Base): Remove. (optional(nullopt_t)): New. (optional(_Up&&)): Invoke base directly with in_place rather than creating a temporary, add default template argument, change constraints. (optional(const optional<_Up>&)): Invoke base directly with in_place, remove unnecessary constraints. (optional(optional<_Up>&& __t)): Likewise. (optional(in_place_t, _Args&&...)): New. (optional(in_place_t, initializer_list<_Up>, _Args&&...)): Likewise. (operator=(_Up&&)): Add default template argument, change constraints. (operator=(const optional<_Up>&)): Put is_same first in the constraints. (operator=(optional<_Up>&&)): Likewise. * testsuite/20_util/optional/assignment/5.cc: Add a test to verify assignment from something that can't be perfect-forwarded. * testsuite/20_util/optional/cons/value.cc: Add tests to verify that a nested optional is disengaged when constructed from a disengaged element type, and to verify that assignments from an engaged element type engage the optional.
OK for trunk.
