typon.hpp: Add optimized fork overloads

rt/include/typon/typon.hpp

@@ -7,6 +7,7 @@
 #include <typon/forked.hpp>
 #include <typon/future.hpp>
 #include <typon/join.hpp>
+#include <typon/meta.hpp>
 #include <typon/mutex.hpp>
 #include <typon/promise.hpp>
 #include <typon/root.hpp>
@@ -25,6 +26,25 @@ namespace typon
     co_return co_await std::move(local_task);
   }
 
+  template <typename Task>
+  Fork<void> fork(Task task, meta::Empty)
+  {
+    // Put the task in a local variable to ensure its destructor will
+    // be called on co_return instead of only on coroutine destruction.
+    Task local_task = std::move(task);
+    co_await std::move(local_task);
+  }
+
+  template <typename Task>
+  Fork<void> fork(Task task, typename Task::promise_type::value_type & into)
+  {
+    // Put the task in a local variable to ensure its destructor will
+    // be called on co_return instead of only on coroutine destruction.
+    Task local_task = std::move(task);
+    // The caller is responsible for garanteeing that the lifetime of
+    // referenced object will always encompass the lifetime of the fork.
+    into = co_await std::move(local_task);
+  }
 
   template <typename Task>
   Future<typename Task::promise_type::value_type> future(Task task)