error[E0277]: `Superset` cannot be safely transmuted into `Subset` in the defining scope of `assert::Context`.
  --> $DIR/should_reject_contraction.rs:35:41
   |
LL |     assert::is_transmutable::<Superset, Subset>();
   |                                         ^^^^^^ `Superset` cannot be safely transmuted into `Subset` in the defining scope of `assert::Context`.
   |
   = help: the trait `BikeshedIntrinsicFrom<Superset, assert::Context, Assume { alignment: false, lifetimes: false, safety: true, validity: false }>` is not implemented for `Subset`
note: required by a bound in `is_transmutable`
  --> $DIR/should_reject_contraction.rs:13:14
   |
LL |     pub fn is_transmutable<Src, Dst>()
   |            --------------- required by a bound in this
LL |     where
LL |         Dst: BikeshedIntrinsicFrom<Src, Context, { Assume::SAFETY }>
   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ required by this bound in `is_transmutable`

error: aborting due to previous error

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