error[E0658]: type alias impl trait is not permitted here
  --> $DIR/issue-75053.rs:52:15
   |
LL |     let _pos: Phantom1<DummyT<()>> = Scope::new().my_index();
   |               ^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #63065 <https://github.com/rust-lang/rust/issues/63065> for more information
   = help: add `#![feature(impl_trait_in_bindings)]` to the crate attributes to enable

error: aborting due to previous error

For more information about this error, try `rustc --explain E0658`.