warning: the feature `type_alias_impl_trait` is incomplete and may not be safe to use and/or cause compiler crashes
  --> $DIR/issue-75053.rs:5:32
   |
LL | #![cfg_attr(full_tait, feature(type_alias_impl_trait))]
   |                                ^^^^^^^^^^^^^^^^^^^^^
   |
   = note: `#[warn(incomplete_features)]` on by default
   = note: see issue #63063 <https://github.com/rust-lang/rust/issues/63063> for more information

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; 1 warning emitted

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