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

error[E0379]: functions in trait impls cannot be declared const
  --> $DIR/trait-fn-const.rs:10:5
   |
LL |     const fn fun() {}
   |     ^^^^^ functions in trait impls cannot be const

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0379`.