test(exec): fork_join with empty value channel

Signed-off-by: romintomasetti <[email protected]>

Author: romintomasetti

include/exec/fork_join.hpp

@@ -137,7 +137,7 @@ namespace exec {
       using _when_all_sndr_t =
         fork_join_t::_when_all_sndr_t<_child_completions_t, Closures, _domain_t>;
       using _child_opstate_t =
-        STDEXEC::connect_result_t<Sndr, STDEXEC::__rcvr_ref_t<_opstate_t, _env_t>>;
+        STDEXEC::connect_result_t<Sndr, STDEXEC::__rcvr_ref_t<_opstate_t>>;
       using _fork_opstate_t =
         STDEXEC::connect_result_t<_when_all_sndr_t, STDEXEC::__rcvr_ref_t<Rcvr>>;
       using _cache_sndr_t = fork_join_t::_cache_sndr_t<_variant_t<_child_completions_t>, _domain_t>;

test/exec/test_fork.cpp

@@ -72,4 +72,13 @@ namespace {
     CHECK(i1 == 42);
     CHECK(i2 == 42);
   }
+
+  TEST_CASE("fork_join with empty value channel", "[adaptors][fork_join]") {
+    auto sndr = ::STDEXEC::just() | ::STDEXEC::then([]() noexcept -> void { })
+              | exec::fork_join(
+                  ::STDEXEC::then([]() noexcept -> void { }),
+                  ::STDEXEC::then([]() noexcept -> void { }));
+
+    ::STDEXEC::sync_wait(std::move(sndr));
+  }
 } // namespace