error[E0423]: expected function, found module `core::future::async_drop`
  --> $DIR/ex-ice1.rs:9:35
   |
LL |         let async_drop_fut = pin!(core::future::async_drop(async {}));
   |                                   ^^^^^^^^^^^^^^^^^^^^^^^^ not a function

error[E0603]: module `async_drop` is private
  --> $DIR/ex-ice1.rs:9:49
   |
LL |         let async_drop_fut = pin!(core::future::async_drop(async {}));
   |                                                 ^^^^^^^^^^ private module
   |
note: the module `async_drop` is defined here
  --> $SRC_DIR/core/src/future/mod.rs:LL:COL

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0423, E0603.
For more information about an error, try `rustc --explain E0423`.