--- /dev/null
+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`.