libstdc++: Assigning to a joinable std::jthread calls std::terminate
Move assigning to a std::jthread that represents a thread of execution
needs to send a stop request and join that running thread. Otherwise the
std::thread data member will terminate in its assignment operator.
Co-authored-by: Jonathan Wakely <jwakely@redhat.com>
libstdc++-v3/ChangeLog:
* include/std/thread (jthread::operator=(jthread&&)): Transfer
any existing state to a temporary that will request a stop and
then join.
* testsuite/30_threads/jthread/jthread.cc: Test move assignment.
(cherry picked from commit
0ebaea3b6677ef8edfa5638800304db1a4f7c2f8)