error[E0204]: the trait `Copy` cannot be implemented for this type
  --> $DIR/deep-bad-copy-reason.rs:38:24
   |
LL | pub struct List<'tcx, T>(Interned<'tcx, ListS<T>>);
   |                          ------------------------ this field does not implement `Copy`
...
LL | impl<'tcx, T> Copy for List<'tcx, T> {}
   |                        ^^^^^^^^^^^^^
   |
note: the `Copy` impl for `Interned<'tcx, ListS<T>>` requires that `OpaqueListContents: Sized`
  --> $DIR/deep-bad-copy-reason.rs:26:26
   |
LL | pub struct List<'tcx, T>(Interned<'tcx, ListS<T>>);
   |                          ^^^^^^^^^^^^^^^^^^^^^^^^

error[E0277]: the size for values of type `OpaqueListContents` cannot be known at compilation time
  --> $DIR/deep-bad-copy-reason.rs:26:26
   |
LL | pub struct List<'tcx, T>(Interned<'tcx, ListS<T>>);
   |                          ^^^^^^^^^^^^^^^^^^^^^^^^ doesn't have a size known at compile-time
   |
   = help: within `ListS<T>`, the trait `Sized` is not implemented for `OpaqueListContents`, which is required by `ListS<T>: Sized`
note: required because it appears within the type `ListS<T>`
  --> $DIR/deep-bad-copy-reason.rs:7:12
   |
LL | pub struct ListS<T> {
   |            ^^^^^
note: required by an implicit `Sized` bound in `Interned`
  --> $DIR/deep-bad-copy-reason.rs:14:25
   |
LL | pub struct Interned<'a, T>(&'a T);
   |                         ^ required by the implicit `Sized` requirement on this type parameter in `Interned`
help: consider relaxing the implicit `Sized` restriction
   |
LL | pub struct Interned<'a, T: ?Sized>(&'a T);
   |                          ++++++++

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0204, E0277.
For more information about an error, try `rustc --explain E0204`.