LWG4360 awaitable-sender concept should qualify use of awaitable-receiver type

Author: burblebee

source/exec.tex

@@ -6616,7 +6616,8 @@
   template<class Sndr, class Promise>
     concept @\defexposconcept{awaitable-sender}@ =
       @\exposconcept{single-sender}@<Sndr, env_of_t<Promise>> &&
-      @\libconcept{sender_to}@<Sndr, @\exposid{awaitable-receiver}@> &&    // \seebelow
+      @\libconcept{sender_to}@<Sndr,
+                typename @\exposid{sender-awaitable}@<Sndr, Promise>::@\exposid{awaitable-receiver}@> &&    // \seebelow
       requires (Promise& p) {
         { p.unhandled_stopped() } -> @\libconcept{convertible_to}@<coroutine_handle<>>;
       };