1 error: `extern` block uses type `A`, which is not FFI-safe
2 --> $DIR/opaque-ty-ffi-unsafe.rs:11:17
7 = note: opaque types have no C equivalent
8 note: the lint level is defined here
9 --> $DIR/opaque-ty-ffi-unsafe.rs:2:9
11 LL | #![deny(improper_ctypes)]
14 error: aborting due to previous error