warning: the feature `async_fn_in_trait` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/dont-project-to-specializable-projection.rs:4:12
   |
LL | #![feature(async_fn_in_trait)]
   |            ^^^^^^^^^^^^^^^^^
   |
   = note: see issue #91611 <https://github.com/rust-lang/rust/issues/91611> for more information
   = note: `#[warn(incomplete_features)]` on by default

error: async associated function in trait cannot be specialized
  --> $DIR/dont-project-to-specializable-projection.rs:14:5
   |
LL |     default async fn foo(_: T) -> &'static str {
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: specialization behaves in inconsistent and surprising ways with `#![feature(async_fn_in_trait)]`, and for now is disallowed

error: aborting due to previous error; 1 warning emitted