[Bug libstdc++/69301] std::atomic::load() won't compile if T doesn't have a default constructor

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69301

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Author: redi
Date: Tue Feb 14 21:17:29 2017
New Revision: 245457

URL: https://gcc.gnu.org/viewcvs?rev=245457&root=gcc&view=rev
Log:
PR69301 don't assume atomic<T> can default construct T

Backport from mainline
2017-01-18  Jonathan Wakely  <jwak...@redhat.com>

        PR libstdc++/69301
        * include/std/atomic (atomic<T>::load, atomic<T>::exchange): Use
        aligned buffer instead of default-initialized variable.
        * testsuite/29_atomics/atomic/69301.cc: New test.
        * include/ext/pointer.h (_Pointer_adapter::operator++(int))
        (_Pointer_adapter::operator--(int)): Likewise.

Added:
    branches/gcc-5-branch/libstdc++-v3/testsuite/29_atomics/atomic/69301.cc
Modified:
    branches/gcc-5-branch/libstdc++-v3/ChangeLog
    branches/gcc-5-branch/libstdc++-v3/include/ext/pointer.h
    branches/gcc-5-branch/libstdc++-v3/include/std/atomic