2019-05-14 Nina Dinka Ranns <dinka.ranns@gmail.com>
nonesuch is insufficiently useless (lwg2996)
* include/std/type_traits (struct __nonesuch): Added private base
class to make __nonesuch not an aggregate and removed deleted default
constructor.
* include/bits/stl_pair.h (struct __nonesuch_no_braces): Removed.
(operator=(const pair&)): Use __nonesuch instead of
__nonesuch_no_braces.
(operator=(pair&&)): Likewise
* include/std/tuple (operator=(const tuple&)): Use __nonesuch instead
of __nonesuch_no_braces.
(operator=(tuple&&)): Likewise
* include/experimental/type_traits (struct nonesuch): Added private
base class to make nonesuch not an aggregate and removed deleted
default constructor.
* testsuite/20_util/nonesuch/nonesuch.cc: New.
* testsuite/experimental/type_traits/nonesuch.cc: New.
From-SVN: r271175
