src/test/ui/feature-gates/feature-gate-trait-alias.stderr

   1 error[E0658]: trait aliases are experimental
   2   --> $DIR/feature-gate-trait-alias.rs:1:1
   3    |
   4 LL | trait Foo = Default;
   5    | ^^^^^^^^^^^^^^^^^^^^
   6    |
   7    = note: for more information, see https://github.com/rust-lang/rust/issues/41517
   8    = help: add `#![feature(trait_alias)]` to the crate attributes to enable
   9
  10 error: aborting due to previous error
  11
  12 For more information about this error, try `rustc --explain E0658`.