Fix missing environment in sync_wait (#108)

* Fix missing environment in sync_wait

* sync_wait: add tests for its environment

* fixed a problem with env in sync_wait (and fixed the tests)

---------

Co-authored-by: Dietmar Kühl <[email protected]>

Author: maikel

include/beman/execution26/detail/sync_wait.hpp

@@ -32,7 +32,7 @@ struct sync_wait_env {
     auto query(::beman::execution26::get_delegation_scheduler_t) const noexcept { return this->loop->get_scheduler(); }
 };
 
-template <::beman::execution26::sender_in Sender>
+template <::beman::execution26::sender_in<::beman::execution26::detail::sync_wait_env> Sender>
 using sync_wait_result_type =
     ::std::optional<::beman::execution26::value_types_of_t<Sender,
                                                            ::beman::execution26::detail::sync_wait_env,
@@ -68,6 +68,9 @@ struct sync_wait_receiver {
         }
         this->state->loop.finish();
     }
+    auto get_env() const noexcept -> ::beman::execution26::detail::sync_wait_env {
+        return ::beman::execution26::detail::sync_wait_env{&this->state->loop};
+    }
 };
 
 struct sync_wait_t {

tests/beman/execution26/exec-sync-wait.test.cpp

@@ -13,6 +13,9 @@
 #include <beman/execution26/detail/sender.hpp>
 #include <beman/execution26/detail/sender_in.hpp>
 #include <beman/execution26/detail/just.hpp>
+#include <beman/execution26/detail/read_env.hpp>
+#include <beman/execution26/detail/get_delegation_scheduler.hpp>
+#include <beman/execution26/detail/then.hpp>
 #include <test/execution.hpp>
 
 #include <exception>
@@ -223,6 +226,15 @@ auto test_sync_wait() -> void {
         // NOLINTEND(cert-dcl03-c,hicpp-static-assert,misc-static-assert)
     }
 }
+
+auto test_provides_scheduler() -> void {
+    ASSERT(test_std::sync_wait(test_std::then(test_std::read_env(test_std::get_scheduler), [](auto&&) noexcept {})));
+}
+
+auto test_provides_delegation_scheduler() -> void {
+    ASSERT(test_std::sync_wait(
+        test_std::then(test_std::read_env(test_std::get_delegation_scheduler), [](auto&&) noexcept {})));
+}
 } // namespace
 
 TEST(exec_sync_wait) {
@@ -236,4 +248,6 @@ TEST(exec_sync_wait) {
     test_sync_wait_state();
     test_sync_wait_receiver();
     test_sync_wait();
+    test_provides_scheduler();
+    test_provides_delegation_scheduler();
 }