SEGV (stack-user-after-return) with simple exec::task in a stdexec::sync_wait (Linux 32-bit)

Bắt đầu với reproducer Godbolt được liên kết trên Linux Intel 32-bit và so sánh hành vi trước và sau PR 1974. Truy vết các đường đi của task và awaitable trong exec/task.hpp, __detail/__optional.hpp, __detail/__connect_awaitable.hpp và __detail/__as_awaitable.hpp, sau đó xác thực rằng sync_wait với exec::task không còn gây ra stack-use-after-return hoặc segmentation fault đã được báo cáo.

The following minimal code sample segfaults on Linux Intel 32-bit. The same cannot be reproduced on Intel 64-bit, aarch64, or armhf.

https://godbolt.org/z/1Yobafcz8

Was able to git-bisect it to the changes in the following PR: https://github.com/NVIDIA/stdexec/pull/1974.
Before it was working fine.

Sanitizers seems to indicate stack-user-after-return (stacktrace is intentionally incomplete, skips confidential parts). The exact backtrace might differ depending on context. Basically all parts of our code-base using stdexec::sync_wait and the exec::task type are affected.
The godbolt link above is just a minimal reproducing sample (sanitizer output might look different), unfortunately I was not able to do a 32-bit sanitizer build on godbolt (seems required static clang-rt libs are missing).

ASan/UBSan sample output (from one occurrence in our code-base):

=================================================================
==732791==ERROR: AddressSanitizer: stack-use-after-return on address 0xe8b1d0e5 at pc 0x67a74cd1 bp 0xffe5d918 sp 0xffe5d910
READ of size 1 at 0xe8b1d0e5 thread T0
    #0 0x67a74cd0 in stdexec::__opt::__optional<experimental::execution::__task::__default_awaiter_context<stdexec::__connect_await::__promise<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__rcvr<stdexec::schedule_from_t, stdexec::__detail::__state<stdexec::__rcvr<stdexec::continues_on_t, stdexec::__trnsfr::__state<experimental::execution::__task::__any_scheduler, stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda14'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, 0u>, stdexec::__>, 0u>>>>::reset() /build/external/stdexec/include/exec/../stdexec/__detail/__optional.hpp:193:13
    #1 0x67a747c3 in experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__task_awaiter<stdexec::__connect_await::__promise<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__rcvr<stdexec::schedule_from_t, stdexec::__detail::__state<stdexec::__rcvr<stdexec::continues_on_t, stdexec::__trnsfr::__state<experimental::execution::__task::__any_scheduler, stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda14'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, 0u>, stdexec::__>, 0u>>>::await_resume() /build/external/stdexec/include/exec/task.hpp:682:22
    #2 0x67a74519 in stdexec::__connect_await::__awaitable_wrapper<stdexec::__connect_await::__awaitable_state<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__connect_await::__promise<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__rcvr<stdexec::schedule_from_t, stdexec::__detail::__state<stdexec::__rcvr<stdexec::continues_on_t, stdexec::__trnsfr::__state<experimental::execution::__task::__any_scheduler, stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda14'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, 0u>, stdexec::__>, 0u>>>::__state>::await_resume() /build/external/stdexec/include/exec/../stdexec/__detail/__connect_awaitable.hpp:141:28
    #3 0x67a7438a in stdexec::__connect_await::__awaitable_wrapper<stdexec::__connect_await::__awaitable_state<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__connect_await::__promise<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__rcvr<stdexec::schedule_from_t, stdexec::__detail::__state<stdexec::__rcvr<stdexec::continues_on_t, stdexec::__trnsfr::__state<experimental::execution::__task::__any_scheduler, stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda14'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, 0u>, stdexec::__>, 0u>>>>::await_resume() /build/external/stdexec/include/exec/../stdexec/__detail/__connect_awaitable.hpp:141:28
    #4 0x67a73ee1 in stdexec::__connect_await::__opstate<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__rcvr<stdexec::schedule_from_t, stdexec::__detail::__state<stdexec::__rcvr<stdexec::continues_on_t, stdexec::__trnsfr::__state<experimental::execution::__task::__any_scheduler, stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda14'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, 0u>, stdexec::__>, 0u>>::__on_resume() /build/external/stdexec/include/exec/../stdexec/__detail/__connect_awaitable.hpp:467:24
    #5 0x67a73ce7 in stdexec::__connect_await::__promise<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>, stdexec::__rcvr<stdexec::schedule_from_t, stdexec::__detail::__state<stdexec::__rcvr<stdexec::continues_on_t, stdexec::__trnsfr::__state<experimental::execution::__task::__any_scheduler, stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda14'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, 0u>, stdexec::__>, 0u>>::__resume(void*) /build/external/stdexec/include/exec/../stdexec/__detail/__connect_awaitable.hpp:103:15
    #6 0x67aba385 in stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>::__done() /build/external/stdexec/include/exec/../stdexec/__detail/__as_awaitable.hpp:294:9
    #7 0x67abbdad in void stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>::set_value<>() /build/external/stdexec/include/exec/../stdexec/__detail/__as_awaitable.hpp:249:9
    #8 0x67abbcac in void stdexec::__detail::__applier::operator()<stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>, stdexec::set_value_t>(stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>&, stdexec::set_value_t) /build/external/stdexec/include/exec/../stdexec/__detail/__storage.hpp:37:9
    #9 0x67abb8e2 in void stdexec::__detail::__visitor::operator()<stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>, stdexec::__tup::__tuple<stdexec::set_value_t>>(stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>&, stdexec::__tup::__tuple<stdexec::set_value_t>&&) /build/external/stdexec/include/exec/../stdexec/__detail/__storage.hpp:46:9
    #10 0x67a632a9 in void stdexec::__var::__visit_alt<0u, void, stdexec::__detail::__visitor, stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>&>(stdexec::__detail::__visitor&&, stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>&&, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>&) /build/external/stdexec/include/exec/../stdexec/__detail/__variant.hpp:93:14
    #11 0x67acf081 in decltype(auto) stdexec::__var::__variant<(stdexec::__iota<0u, 1u, 2u>*)0, stdexec::__tup::__tuple<stdexec::set_value_t>, stdexec::__tup::__tuple<stdexec::set_error_t, std::__exception_ptr::exception_ptr>, stdexec::__tup::__tuple<stdexec::set_stopped_t>>::__visit<stdexec::__detail::__visitor, stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>&>(stdexec::__detail::__visitor&&, stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>&&, T1&&...) /build/external/stdexec/include/exec/../stdexec/__detail/__variant.hpp:373:16
    #12 0x67aceb67 in void stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>::__static___complete<stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>(stdexec::__results_storage<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>&&, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>&) /build/external/stdexec/include/exec/../stdexec/__detail/__storage.hpp:75:7
    #13 0x67cd595d in stdexec::__trnsfr::__receiver2<stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda23'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>::set_value() /build/external/stdexec/include/exec/../stdexec/__detail/__continues_on.hpp:85:38
    #14 0x67ccdb58 in experimental::execution::_any::_ireceiver_memfn<stdexec::set_value_t ()>::_interface_<stdexec::__any::__reference_root<experimental::execution::_any::_ireceiver<stdexec::completion_signatures<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, experimental::execution::queries<>>::_isemi_receiver, experimental::execution::_any::_state<stdexec::__trnsfr::__receiver2<stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda23'(){}>, stdexec::__as_awaitable::__async_receiver<experimental::execution::__task::basic_task<void, experimental::execution::__task::__default_task_context_impl<(experimental::execution::__task::__scheduler_affinity)1>>::__promise, void>>, stdexec::never_stop_token>, experimental::execution::_any::_ireceiver<stdexec::completion_signatures<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, experimental::execution::queries<>>::_isemi_receiver<experimental::execution::_any::_ireceiver_memfn<stdexec::set_stopped_t ()>::_interface_<experimental::execution::_any::_ireceiver_memfn<stdexec::set_error_t (std::__exception_ptr::exception_ptr)>::_interface_<experimental::execution::_any::_ireceiver_memfn<stdexec::set_value_t ()>::_interface_<stdexec::__any::__iroot>>>>>>::set_value() && /build/external/stdexec/include/exec/any_sender_of.hpp:235:53
    #15 0x67aaf228 in experimental::execution::_any::_ireceiver_memfn<stdexec::set_value_t ()>::_interface_<stdexec::__any::__reference_proxy_root<experimental::execution::_any::_ireceiver<stdexec::completion_signatures<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, experimental::execution::queries<>>::_isemi_receiver>>::set_value() && /build/external/stdexec/include/exec/any_sender_of.hpp:235:53
    #16 0x67b4e2c3 in void stdexec::__pointer_receiver<stdexec::__any::__any_ptr<experimental::execution::_any::_ireceiver<stdexec::completion_signatures<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, experimental::execution::queries<>>::_isemi_receiver>, stdexec::env<>>::set_value<>() /build/external/stdexec/include/exec/../stdexec/__detail/__receiver_ref.hpp:59:7
    #17 0x67bead18 in stdexec::__run_loop::__run_loop_base::__opstate_t<stdexec::__pointer_receiver<stdexec::__any::__any_ptr<experimental::execution::_any::_ireceiver<stdexec::completion_signatures<stdexec::set_value_t (), stdexec::set_error_t (std::__exception_ptr::exception_ptr), stdexec::set_stopped_t ()>, experimental::execution::queries<>>::_isemi_receiver>, stdexec::env<>>>::__execute_impl(stdexec::__run_loop::__run_loop_base::__task*) /build/external/stdexec/include/exec/../stdexec/__detail/__run_loop.hpp:126:13
    #18 0x67bf5594 in stdexec::__run_loop::__run_loop_base::__task::__execute() /build/external/stdexec/include/exec/../stdexec/__detail/__run_loop.hpp:104:11
    #19 0x67bf3071 in stdexec::__run_loop::__run_loop_base::__execute_all() /build/external/stdexec/include/exec/../stdexec/__detail/__run_loop.hpp:177:22
    #20 0x67b64c43 in stdexec::__run_loop::__run_loop_base::run() /build/external/stdexec/include/exec/../stdexec/__detail/__run_loop.hpp:58:11
    #21 0x67b5d521 in std::optional<stdexec::__sync_wait::__value_tuple_for<stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda15'(){}>>::__t> stdexec::sync_wait_t::apply_sender<stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda15'(){}>>(stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda15'(){}>&&) const /build/external/stdexec/include/exec/../stdexec/__detail/__sync_wait.hpp:382:29
    #22 0x67b5c728 in auto stdexec::sync_wait_t::operator()<stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda15'(){}>>(stdexec::(anonymous namespace)::__sexpr<stdexec::'lambda15'(){}>&&) const /build/external/stdexec/include/exec/../stdexec/__detail/__sync_wait.hpp:317:48