LWG 2097 says that the templated std::thread(Callable&&, Args&&...) constructor should not participate in overload resolution when decay_t<Callable> is std::thread. Rather than removing it from the overload set we just ensure that there are better matches, but we fail to do so for const rvalues. This fixes it.
PR libstdc++/78956 * include/std/thread (thread(const thread&&)): Add deleted constructor. * testsuite/30_threads/thread/cons/lwg2097.cc: New test. Tested powerpc64le-linux, committed to trunk.
commit a8b2bad2dda80054e3b8cc5a4d1c2c39226070d5 Author: Jonathan Wakely <jwak...@redhat.com> Date: Tue Jan 3 12:09:59 2017 +0000 Add deleted std::thread(const thread&&) constructor PR libstdc++/78956 * include/std/thread (thread(const thread&&)): Add deleted constructor. * testsuite/30_threads/thread/cons/lwg2097.cc: New test. diff --git a/libstdc++-v3/include/std/thread b/libstdc++-v3/include/std/thread index f725bdb..8e2cb68 100644 --- a/libstdc++-v3/include/std/thread +++ b/libstdc++-v3/include/std/thread @@ -108,6 +108,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION // 2097. packaged_task constructors should be constrained thread(thread&) = delete; thread(const thread&) = delete; + thread(const thread&&) = delete; thread(thread&& __t) noexcept { swap(__t); } diff --git a/libstdc++-v3/testsuite/30_threads/thread/cons/lwg2097.cc b/libstdc++-v3/testsuite/30_threads/thread/cons/lwg2097.cc new file mode 100644 index 0000000..165c649 --- /dev/null +++ b/libstdc++-v3/testsuite/30_threads/thread/cons/lwg2097.cc @@ -0,0 +1,29 @@ +// { dg-do compile { target c++11 } } +// { dg-require-cstdint "" } +// { dg-require-gthreads "" } + +// Copyright (C) 2017 Free Software Foundation, Inc. +// +// This file is part of the GNU ISO C++ Library. This library is free +// software; you can redistribute it and/or modify it under the +// terms of the GNU General Public License as published by the +// Free Software Foundation; either version 3, or (at your option) +// any later version. + +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +// GNU General Public License for more details. + +// You should have received a copy of the GNU General Public License along +// with this library; see the file COPYING3. If not see +// <http://www.gnu.org/licenses/>. + +#include <thread> + +using std::thread; +using std::is_constructible; + +static_assert( !is_constructible<thread, thread&>::value, "" ); +static_assert( !is_constructible<thread, const thread&>::value, "" ); +static_assert( !is_constructible<thread, const thread>::value, "" );