error[E0277]: the trait bound `B: Clone` is not satisfied
  --> $DIR/issue-79224.rs:18:1
   |
LL | / impl<B: ?Sized> Display for Cow<'_, B> {
LL | |     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
LL | |         write!(f, "foo")
LL | |     }
LL | | }
   | |_^ the trait `Clone` is not implemented for `B`
   |
   = note: required for `B` to implement `ToOwned`
help: consider further restricting this bound
   |
LL | impl<B: ?Sized + std::clone::Clone> Display for Cow<'_, B> {
   |                +++++++++++++++++++

error[E0277]: the trait bound `B: Clone` is not satisfied
  --> $DIR/issue-79224.rs:19:5
   |
LL | /     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
LL | |         write!(f, "foo")
LL | |     }
   | |_____^ the trait `Clone` is not implemented for `B`
   |
   = note: required for `B` to implement `ToOwned`
help: consider further restricting this bound
   |
LL | impl<B: ?Sized + std::clone::Clone> Display for Cow<'_, B> {
   |                +++++++++++++++++++

error: aborting due to 2 previous errors

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