error[E0308]: mismatched types
  --> $DIR/extern-types-distinct-types.rs:9:5
   |
LL |     type A;
   |     ------ the found foreign type
LL |     type B;
   |     ------ the expected foreign type
...
LL | fn foo(r: &A) -> &B {
   |                  -- expected `&B` because of return type
LL |     r
   |     ^ expected `&B`, found `&A`
   |
   = note: expected reference `&B`
              found reference `&A`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.