https://gcc.gnu.org/g:bb96099a8dc8cf69bb0d2e424c3b38e6365f90f6
commit r16-4429-gbb96099a8dc8cf69bb0d2e424c3b38e6365f90f6 Author: Mike Crowe <[email protected]> Date: Sun Sep 14 21:21:31 2025 +0100 libstdc++: Add std::future tests for negative timeouts [PR116586] Add tests to show that std::future::wait_until and std::future::wait_for correctly handle negative timeouts. libstdc++-v3/ChangeLog: PR libstdc++/116586 * testsuite/30_threads/future/members/116586.cc: New test. Signed-off-by: Mike Crowe <[email protected]> Diff: --- .../testsuite/30_threads/future/members/116586.cc | 55 ++++++++++++++++++++++ 1 file changed, 55 insertions(+) diff --git a/libstdc++-v3/testsuite/30_threads/future/members/116586.cc b/libstdc++-v3/testsuite/30_threads/future/members/116586.cc new file mode 100644 index 000000000000..b7cd12c6009c --- /dev/null +++ b/libstdc++-v3/testsuite/30_threads/future/members/116586.cc @@ -0,0 +1,55 @@ +// { dg-do run { target c++11 } } + +#include <future> +#include <chrono> +#include <initializer_list> +#include <testsuite_hooks.h> + +namespace chrono = std::chrono; + +// thread.timedmutex.requirements.general: +// If abs_time has already passed, the function attempts to obtain +// ownership without blocking (as if by calling try_lock()). + +template <typename Clock> +void +test_absolute(chrono::nanoseconds offset) +{ + std::promise<int> p; + std::future<int> f = p.get_future(); + const chrono::time_point<Clock> tp(offset); + VERIFY(f.wait_until(tp) == std::future_status::timeout); +} + +// The type of clock used for the actual wait depends on whether +// _GLIBCXX_HAVE_LINUX_FUTEX is defined. We might as well just test both +// steady_clock and system_clock. +template <typename Clock> +void +test_relative(chrono::nanoseconds offset) +{ + std::promise<int> p; + std::future<int> f = p.get_future(); + const auto d = -Clock::now().time_since_epoch() + offset; + VERIFY(f.wait_for(d) == std::future_status::timeout); +} + +int main() +{ + // It's not really possible to arrange for the relative calls to have tv_nsec + // == 0 due to time advancing. + for (const chrono::nanoseconds offset : { + // tv_sec == 0, tv_nsec == 0 + chrono::nanoseconds{0}, + // tv_sec == 0, tv_nsec < 0 + chrono::duration_cast<chrono::nanoseconds>(chrono::milliseconds{-10}), + // tv_sec < 0 + chrono::duration_cast<chrono::nanoseconds>(chrono::seconds{-10}) + }) { + test_absolute<chrono::system_clock>(offset); + test_relative<chrono::system_clock>(offset); + + test_absolute<chrono::steady_clock>(offset); + test_relative<chrono::steady_clock>(offset); + } +}
