error[E0658]: the attribute `repr(no_niche)` is currently unstable
  --> $DIR/feature-gate-no-niche.rs:4:8
   |
LL | #[repr(no_niche)]
   |        ^^^^^^^^
   |
   = help: add `#![feature(no_niche)]` to the crate attributes to enable

error[E0658]: the attribute `repr(no_niche)` is currently unstable
  --> $DIR/feature-gate-no-niche.rs:8:21
   |
LL | #[repr(transparent, no_niche)]
   |                     ^^^^^^^^
   |
   = help: add `#![feature(no_niche)]` to the crate attributes to enable

error[E0658]: the attribute `repr(no_niche)` is currently unstable
  --> $DIR/feature-gate-no-niche.rs:12:8
   |
LL | #[repr(no_niche)]
   |        ^^^^^^^^
   |
   = help: add `#![feature(no_niche)]` to the crate attributes to enable

error[E0658]: the attribute `repr(no_niche)` is currently unstable
  --> $DIR/feature-gate-no-niche.rs:16:8
   |
LL | #[repr(no_niche)]
   |        ^^^^^^^^
   |
   = help: add `#![feature(no_niche)]` to the crate attributes to enable

error: aborting due to 4 previous errors

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