error[E0658]: the `#[force_target_feature]` attribute is an experimental feature
  --> $DIR/feature-gate-effective-target-features.rs:13:5
   |
LL |     #[unsafe(force_target_feature(enable = "avx2"))]
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #143352 <https://github.com/rust-lang/rust/issues/143352> for more information
   = help: add `#![feature(effective_target_features)]` to the crate attributes to enable
   = note: this compiler was built on YYYY-MM-DD; consider upgrading it if it is out of date

error: `#[target_feature(..)]` cannot be applied to safe trait method
  --> $DIR/feature-gate-effective-target-features.rs:21:5
   |
LL |     #[target_feature(enable = "avx2")]
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ cannot be applied to safe trait method
LL |
LL |     fn foo(&self) {}
   |     ------------- not an `unsafe` function

error[E0053]: method `foo` has an incompatible type for trait
  --> $DIR/feature-gate-effective-target-features.rs:23:5
   |
LL |     fn foo(&self) {}
   |     ^^^^^^^^^^^^^ expected safe fn, found unsafe fn
   |
note: type in trait
  --> $DIR/feature-gate-effective-target-features.rs:7:5
   |
LL |     fn foo(&self);
   |     ^^^^^^^^^^^^^^
   = note: expected signature `fn(&Bar2)`
              found signature `#[target_features] fn(&Bar2)`

error: aborting due to 3 previous errors

Some errors have detailed explanations: E0053, E0658.
For more information about an error, try `rustc --explain E0053`.