Add lang items for AsyncFn's associated types

Author: compiler-errors

core/src/ops/async_function.rs

@@ -26,6 +26,7 @@ pub trait AsyncFn<Args: Tuple>: AsyncFnMut<Args> {
 pub trait AsyncFnMut<Args: Tuple>: AsyncFnOnce<Args> {
     /// Future returned by [`AsyncFnMut::async_call_mut`] and [`AsyncFn::async_call`].
     #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(not(bootstrap), lang = "call_ref_future")]
     type CallRefFuture<'a>: Future<Output = Self::Output>
     where
         Self: 'a;
@@ -46,10 +47,12 @@ pub trait AsyncFnMut<Args: Tuple>: AsyncFnOnce<Args> {
 pub trait AsyncFnOnce<Args: Tuple> {
     /// Future returned by [`AsyncFnOnce::async_call_once`].
     #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(not(bootstrap), lang = "call_once_future")]
     type CallOnceFuture: Future<Output = Self::Output>;
 
     /// Output type of the called closure's future.
     #[unstable(feature = "async_fn_traits", issue = "none")]
+    #[cfg_attr(not(bootstrap), lang = "async_fn_once_output")]
     type Output;
 
     /// Call the [`AsyncFnOnce`], returning a future which may move out of the called closure.