error: `extern` block uses type `AliasB`, which is not FFI-safe
  --> $DIR/opaque-ty-ffi-normalization-cycle.rs:37:21
   |
LL |     fn lint_me() -> <AliasB as TraitB>::Assoc;
   |                     ^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = note: opaque types have no C equivalent
note: the lint level is defined here
  --> $DIR/opaque-ty-ffi-normalization-cycle.rs:3:9
   |
LL | #![deny(improper_ctypes)]
   |         ^^^^^^^^^^^^^^^

error: aborting due to 1 previous error