in include/unifex/let_done.hpp [218:229]
explicit type(Source&& source, Done2&& done, Receiver2&& dest)
noexcept(std::is_nothrow_move_constructible_v<Receiver> &&
std::is_nothrow_move_constructible_v<Done> &&
is_nothrow_connectable_v<Source, source_receiver>)
: done_((Done2&&)done)
, receiver_((Receiver2&&)dest)
{
unifex::activate_union_member_with(sourceOp_, [&] {
return unifex::connect((Source&&)source, source_receiver{this});
});
startedOp_ = 0 + 1;
}