error[E0277]: the trait bound `[i32]: Index<u32>` is not satisfied
  --> $DIR/on-impl.rs:22:47
   |
LL |     Index::<u32>::index(&[1, 2, 3] as &[i32], 2u32);
   |     -------------------                       ^^^^ a usize is required to index into a slice
   |     |
   |     required by a bound introduced by this call
   |
   = help: the trait `Index<u32>` is not implemented for `[i32]`
           but trait `Index<usize>` is implemented for it
   = help: for that trait implementation, expected `usize`, found `u32`

error[E0277]: the trait bound `[i32]: Index<u32>` is not satisfied
  --> $DIR/on-impl.rs:22:5
   |
LL |     Index::<u32>::index(&[1, 2, 3] as &[i32], 2u32);
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ a usize is required to index into a slice
   |
   = help: the trait `Index<u32>` is not implemented for `[i32]`
           but trait `Index<usize>` is implemented for it
   = help: for that trait implementation, expected `usize`, found `u32`

error: aborting due to 2 previous errors

For more information about this error, try `rustc --explain E0277`.