Fix use-before-deduction in folly/experimental/pushmi/
Fix use-before-deduction in folly/experimental/pushmi/

Summary:
[Folly] Fix use-before-deduction in `folly/experimental/pushmi/` under gcc8.

```
folly/experimental/pushmi/test/FlowTest.cpp: In instantiation of 'ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens)::<lambda(auto:11)>::Data::Data(Stopper) [with auto:11 = folly::pushmi::flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >; MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; Stopper = <type error>]':
folly/experimental/pushmi/test/FlowTest.cpp:165:34:   required from 'ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)> [with auto:11 = folly::pushmi::flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >]'
folly/experimental/pushmi/detail/functional.h:34:33:   required by substitution of 'template<class F, class ... As> decltype ((F&&)(f)((As&(folly::pushmi::invoke_fn::operator()::as))...)) folly::pushmi::invoke_fn::operator()(F&&, As&& ...) const [with F = ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>&; As = {folly::pushmi::flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >}]'
folly/experimental/pushmi/detail/functional.h:49:228:   required by substitution of 'template<class C_> static constexpr decltype (folly::pushmi::concepts::detail::gcc_bugs((& C_::Requires_<<lambda(auto:11)>&, flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > > >))) folly::pushmi::InvocableConcept::Eval<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>&, folly::pushmi::flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > > >::impl<C_>(int) [with C_ = folly::pushmi::InvocableConcept]'
folly/experimental/pushmi/detail/functional.h:49:649:   required from 'constexpr folly::pushmi::InvocableConcept::Eval<F, Args>::operator bool() const [with F = ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>&; Args = {folly::pushmi::flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >}]'
folly/experimental/pushmi/detail/functional.h:49:1400:   required from 'constexpr const bool folly::pushmi::Invocable<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>&, folly::pushmi::flow_receiver<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > > >'
folly/experimental/pushmi/flow_single_sender.h:148:82:   [ skipping 10 instantiation contexts, use -ftemplate-backtrace-limit=0 to disable ]
folly/experimental/pushmi/detail/functional.h:34:33:   required by substitution of 'template<class F, class ... As> decltype ((F&&)(f)((As&(folly::pushmi::invoke_fn::operator()::as))...)) folly::pushmi::invoke_fn::operator()(F&&, As&& ...) const [with F = folly::pushmi::detail::submit_fn::fn<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >&; As = {folly::pushmi::flow_single_sender<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>, folly::pushmi::trampolineEXF>&}]'
folly/experimental/pushmi/detail/functional.h:49:228:   required by substitution of 'template<class C_> static constexpr decltype (folly::pushmi::concepts::detail::gcc_bugs((& C_::Requires_<fn<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >&, flow_single_sender<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>, folly::pushmi::trampolineEXF>&>))) folly::pushmi::InvocableConcept::Eval<folly::pushmi::detail::submit_fn::fn<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >&, folly::pushmi::flow_single_sender<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>, folly::pushmi::trampolineEXF>&>::impl<C_>(int) [with C_ = folly::pushmi::InvocableConcept]'
folly/experimental/pushmi/detail/functional.h:49:649:   required from 'constexpr folly::pushmi::InvocableConcept::Eval<F, Args>::operator bool() const [with F = folly::pushmi::detail::submit_fn::fn<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >&; Args = {folly::pushmi::flow_single_sender<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>, folly::pushmi::trampolineEXF>&}]'
folly/experimental/pushmi/detail/concept_def.h:485:12:   required by substitution of 'template<class In, class Op, int (* _pushmi_concept_unique_25)[128], typename std::enable_if<(_pushmi_concept_unique_25 || (bool)((Sender<typename std::decay<_Tp>::type> && Invocable<Op&, In>))), int>::type <anonymous> > decltype(auto) folly::pushmi::operator|(In&&, Op) [with In = folly::pushmi::flow_single_sender<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:11)>, folly::pushmi::trampolineEXF>&; Op = folly::pushmi::detail::submit_fn::fn<folly::pushmi::on_value_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(int)> >, folly::pushmi::on_error_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:18)> >, folly::pushmi::on_done_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda()> >, folly::pushmi::on_starting_fn<ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]::<lambda(auto:19)> > >; int (* _pushmi_concept_unique_25)[128] = 0; typename std::enable_if<(_pushmi_concept_unique_25 || (bool)((Sender<typename std::decay<_Tp>::type> && Invocable<Op&, In>))), int>::type <anonymous> = 0]'
folly/experimental/pushmi/test/FlowTest.cpp:208:7:   required from 'void ConcurrentFlowSingleSender::cancellation_test(std::chrono::_V2::system_clock::time_point, MakeTokens) [with MakeTokens = ConcurrentFlowSingleSender_EarlySharedCancellation_Test::TestBody()::<lambda(auto:21&, auto:22&)>; std::chrono::_V2::system_clock::time_point = std::chrono::time_point<std::chrono::_V2::system_clock, std::chrono::duration<long int, std::ratio<1, 1000000000> > >]'
folly/experimental/pushmi/test/FlowTest.cpp:249:4:   required from here
folly/experimental/pushmi/test/FlowTest.cpp:160:39: error: use of 'tokens' before deduction of 'auto'
```

Reviewed By: ericniebler

Differential Revision: D13648392

fbshipit-source-id: 6ad0b4f60704e6eb93417e347b4b081e2c230661

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly