r271166 - in /trunk/libstdc++-v3: ChangeLog inc...

[redi@gcc.gnu.org]

Author: redi
Date: Tue May 14 12:01:15 2019
New Revision: 271166

URL: https://gcc.gnu.org/viewcvs?rev=271166&root=gcc&view=rev
Log:
PR libstdc++/69724 avoid temporary in std::thread construction

The std::thread constructor creates (and then moves) an unnecessary
temporary copy of each argument. Optimize it to only make the one copy
that is required.

	PR libstdc++/69724
	* include/std/thread (thread::_State_impl, thread::_S_make_state):
	Replace single _Callable parameter with variadic _Args pack, to
	forward them directly to the tuple of decayed copies.
	* testsuite/30_threads/thread/cons/69724.cc: New test.

Added:
    trunk/libstdc++-v3/testsuite/30_threads/thread/cons/69724.cc
Modified:
    trunk/libstdc++-v3/ChangeLog
    trunk/libstdc++-v3/include/std/thread