[RFC PATCH 0/4] Make std::future::wait_* use std::chrono::steady_clock when required

[Mike Crowe <mac at mcrowe dot com>]

This is a first attempt to make std::future::wait_until and
std::future::wait_for make correct use of
std::chrono::steady_clock/CLOCK_MONOTONIC. It also makes
std::future::wait_until react to changes to CLOCK_REALTIME during the
wait, but only when passed a std::chrono::system_clock time point.

Prior to these patches, the situation is similar to that described at
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41861 for
std::condition_variable, but with the benefit that this time the bug can be
fixed entirely within libstdc++.

(I've omitted the ChangeLog entries for now, since I don't believe that
this is ready to be accepted in its current form.)

Mike.

Mike Crowe (4):
  libstdc++ futex: Use FUTEX_CLOCK_REALTIME for wait
  libstdc++ futex: Support waiting on std::chrono::steady_clock directly
  libstdc++ atomic_futex: Use std::chrono::steady_clock as reference
    clock
  Extra async tests, not for merging

 libstdc++-v3/include/bits/atomic_futex.h         | 74 +++++++++++++++++++++--
 libstdc++-v3/src/c++11/futex.cc                  | 48 +++++++++++----
 libstdc++-v3/testsuite/30_threads/async/async.cc | 76 ++++++++++++++++++++++++
 3 files changed, 181 insertions(+), 17 deletions(-)

-- 
2.11.0