error: the struct `#[repr(align(u16))]` attribute is experimental (see issue #33626)
  --> $DIR/gated-features-attr-spans.rs:13:1
   |
13 | #[repr(align(16))]
   | ^^^^^^^^^^^^^^^^^^
   |
   = help: add #![feature(repr_align)] to the crate attributes to enable

error: SIMD types are experimental and possibly buggy (see issue #27731)
  --> $DIR/gated-features-attr-spans.rs:20:1
   |
20 | #[repr(simd)]
   | ^^^^^^^^^^^^^
   |
   = help: add #![feature(repr_simd)] to the crate attributes to enable

warning: `#[must_use]` on methods is experimental (see issue #43302)
  --> $DIR/gated-features-attr-spans.rs:27:5
   |
27 |     #[must_use] fn summon_weapon(&self) -> Weapon { self.weapon }
   |     ^^^^^^^^^^^
   |
   = help: add #![feature(fn_must_use)] to the crate attributes to enable

warning: `#[must_use]` on functions is experimental (see issue #43302)
  --> $DIR/gated-features-attr-spans.rs:30:1
   |
30 | #[must_use]
   | ^^^^^^^^^^^
   |
   = help: add #![feature(fn_must_use)] to the crate attributes to enable

error: aborting due to 2 previous errors