src/test/ui/issues/issue-16250.stderr

   1 error: `extern` block uses type `Foo` which is not FFI-safe: this struct has unspecified layout
   2   --> $DIR/issue-16250.rs:6:20
   3    |
   4 LL |     pub fn foo(x: (Foo));
   5    |                    ^^^
   6    |
   7 note: lint level defined here
   8   --> $DIR/issue-16250.rs:1:9
   9    |
  10 LL | #![deny(warnings)]
  11    |         ^^^^^^^^
  12    = note: #[deny(improper_ctypes)] implied by #[deny(warnings)]
  13    = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
  14 note: type defined here
  15   --> $DIR/issue-16250.rs:3:1
  16    |
  17 LL | pub struct Foo;
  18    | ^^^^^^^^^^^^^^^
  19
  20 error: aborting due to previous error
  21