test(exec): fork_join with empty value channel

[romintomasetti]

This was working 2 days ago.

I'll try to find the culprit commit later today.

• 68bcedc 🔴
• 6ddedb4 🔴
• e726de2 ✔️

It seems it stopped working with:

• 6ddedb4 (merged in make almost everything constexpr that can be #1772 by @ericniebler )

The compile error looks like:

[  0%] Building CXX object test/exec/CMakeFiles/test.exec.dir/test_fork.cpp.o
In file included from /workspaces/stdexec/test/exec/test_fork.cpp:17:
In file included from /workspaces/stdexec/include/exec/fork_join.hpp:18:
/workspaces/stdexec/include/exec/../stdexec/__detail/__receiver_ref.hpp:55:9: error: 
      static assertion failed: get_env() must return the same type as env_of_t<_Rcvr>
   55 |         __same_as<_Env, env_of_t<_Rcvr>>, "get_env() must return the same type as env_of_t<_Rcvr>");
      |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/workspaces/stdexec/include/exec/../stdexec/__detail/__env.hpp:318:31: note: in
      instantiation of member function
      'std::execution::__rcvr_ref<exec::fork_join_t::_opstate_t<std::execution::(anonymous
      namespace)::__sexpr<std::execution::(lambda at
      /workspaces/stdexec/include/exec/../stdexec/__detail/__basic_sender.hpp:59:53){}>,
      std::execution::__tup::__tuple<std::execution::__clsur::__closure<std::execution::__then::then_t,
      (lambda at /workspaces/stdexec/test/exec/test_fork.cpp:79:35)>,
      std::execution::__clsur::__closure<std::execution::__then::then_t, (lambda at
      /workspaces/stdexec/test/exec/test_fork.cpp:80:35)>>,
      std::execution::__sync_wait::__receiver<>::__t>,
      std::execution::__env::__fwd<std::execution::__sync_wait::__env>::__t>::get_env' requested here
  318 |         return __env_provider.get_env();

I'm not sure if the fix I'm doing is the right thing to do.

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[ericniebler]

/ok to test 3bbf3fe

[ericniebler]

i think #1789 will fix this issue.

[romintomasetti]

@ericniebler Indeed, it will fix it. I'll rebase this one when #1789 is merged.