https://gcc.gnu.org/g:87c994095b17892922bfcd3c154c51526ece2260
commit r16-4428-g87c994095b17892922bfcd3c154c51526ece2260 Author: Mike Crowe <[email protected]> Date: Sun Sep 14 21:21:30 2025 +0100 libstdc++: Add std::condition_variable tests for negative timeouts [PR116586] Add tests to show that std::condition_variable::wait_until and std::condition_variable::wait_for correctly handle negative timeouts. libstdc++-v3/ChangeLog: PR libstdc++/116586 * testsuite/30_threads/condition_variable/members/116586.cc: New test. Signed-off-by: Mike Crowe <[email protected]> Diff: --- .../condition_variable/members/116586.cc | 60 ++++++++++++++++++++++ 1 file changed, 60 insertions(+) diff --git a/libstdc++-v3/testsuite/30_threads/condition_variable/members/116586.cc b/libstdc++-v3/testsuite/30_threads/condition_variable/members/116586.cc new file mode 100644 index 000000000000..71140078d418 --- /dev/null +++ b/libstdc++-v3/testsuite/30_threads/condition_variable/members/116586.cc @@ -0,0 +1,60 @@ +// { dg-do run { target c++11 } } + +#include <condition_variable> +#include <chrono> +#include <mutex> +#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::mutex mtx; + std::condition_variable cv; + chrono::time_point<Clock> tp(offset); + std::unique_lock<std::mutex> lock(mtx); + // Doesn't cope with spurious wakeup + VERIFY(cv.wait_until(lock, tp) == std::cv_status::timeout); +} + +// The type of clock used for the actual wait depends on whether +// _GLIBCXX_USE_PTHREAD_MUTEX_CLOCKLOCK is defined. We might as well just test +// both steady_clock and system_clock. +template <typename Clock> +void +test_relative(chrono::nanoseconds offset) +{ + std::mutex mtx; + std::condition_variable cv; + const auto d = -Clock::now().time_since_epoch() + offset; + std::unique_lock<std::mutex> lock(mtx); + // Doesn't cope with spurious wakeup + VERIFY(cv.wait_for(lock, d) == std::cv_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); + } +}
