error[E0277]: the trait bound `X: Ord` is not satisfied
  --> $DIR/issue-20162.rs:5:7
   |
LL |     b.sort();
   |       ^^^^ the trait `Ord` is not implemented for `X`
   |
note: required by a bound in `slice::<impl [T]>::sort`
  --> $SRC_DIR/alloc/src/slice.rs:LL:COL
help: consider annotating `X` with `#[derive(Ord)]`
   |
LL + #[derive(Ord)]
LL | struct X { x: i32 }
   |

error: aborting due to 1 previous error

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