error: duplicate diagnostic item in crate `p2`: `Foo`.
   |
   = note: the diagnostic item is first defined in crate `p1`.

error: duplicate diagnostic item in crate `duplicate_diagnostic`: `Foo`.
  --> $DIR/duplicate-diagnostic.rs:12:1
   |
LL | pub struct Foo {}
   | ^^^^^^^^^^^^^^
   |
   = note: the diagnostic item is first defined in crate `p2`.

error: aborting due to 2 previous errors