error[E0379]: functions in traits cannot be declared const
  --> $DIR/feature-gate-const_fn.rs:6:5
   |
LL |     const fn foo() -> u32;
   |     ^^^^^ functions in traits cannot be const

error[E0379]: functions in traits cannot be declared const
  --> $DIR/feature-gate-const_fn.rs:8:5
   |
LL |     const fn bar() -> u32 { 0 }
   |     ^^^^^ functions in traits cannot be const

error[E0379]: functions in traits cannot be declared const
  --> $DIR/feature-gate-const_fn.rs:13:5
   |
LL |     const fn foo() -> u32 { 0 }
   |     ^^^^^ functions in traits cannot be const

error[E0658]: const fn is unstable
  --> $DIR/feature-gate-const_fn.rs:6:5
   |
LL |     const fn foo() -> u32;
   |     ^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
   = help: add `#![feature(const_fn)]` to the crate attributes to enable

error[E0658]: const fn is unstable
  --> $DIR/feature-gate-const_fn.rs:8:5
   |
LL |     const fn bar() -> u32 { 0 }
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: see issue #57563 <https://github.com/rust-lang/rust/issues/57563> for more information
   = help: add `#![feature(const_fn)]` to the crate attributes to enable

error: aborting due to 5 previous errors

Some errors have detailed explanations: E0379, E0658.
For more information about an error, try `rustc --explain E0379`.