error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:4:15
   |
LL | pub fn bad(f: extern "C" fn([u8])) {}
   |               ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent
note: the lint level is defined here
  --> $DIR/lint-ctypes-94223.rs:2:9
   |
LL | #![deny(improper_ctypes_definitions)]
   |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:7:28
   |
LL | pub fn bad_twice(f: Result<extern "C" fn([u8]), extern "C" fn([u8])>) {}
   |                            ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent

error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:7:49
   |
LL | pub fn bad_twice(f: Result<extern "C" fn([u8]), extern "C" fn([u8])>) {}
   |                                                 ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent

error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:11:18
   |
LL | struct BadStruct(extern "C" fn([u8]));
   |                  ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent

error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:15:7
   |
LL |     A(extern "C" fn([u8])),
   |       ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent

error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:20:7
   |
LL |     A(extern "C" fn([u8])),
   |       ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent

error: `extern` fn uses type `[u8]`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:24:12
   |
LL | type Foo = extern "C" fn([u8]);
   |            ^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider using a raw pointer instead
   = note: slices have no C equivalent

error: `extern` fn uses type `Option<&<T as FooTrait>::FooType>`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:31:20
   |
LL | pub type Foo2<T> = extern "C" fn(Option<&<T as FooTrait>::FooType>);
   |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
   = note: enum has no representation hint

error: `extern` fn uses type `FfiUnsafe`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:41:17
   |
LL | pub static BAD: extern "C" fn(FfiUnsafe) = f;
   |                 ^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
   = note: this struct has unspecified layout
note: the type is defined here
  --> $DIR/lint-ctypes-94223.rs:34:1
   |
LL | pub struct FfiUnsafe;
   | ^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `FfiUnsafe`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:44:30
   |
LL | pub static BAD_TWICE: Result<extern "C" fn(FfiUnsafe), extern "C" fn(FfiUnsafe)> = Ok(f);
   |                              ^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
   = note: this struct has unspecified layout
note: the type is defined here
  --> $DIR/lint-ctypes-94223.rs:34:1
   |
LL | pub struct FfiUnsafe;
   | ^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `FfiUnsafe`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:44:56
   |
LL | pub static BAD_TWICE: Result<extern "C" fn(FfiUnsafe), extern "C" fn(FfiUnsafe)> = Ok(f);
   |                                                        ^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
   = note: this struct has unspecified layout
note: the type is defined here
  --> $DIR/lint-ctypes-94223.rs:34:1
   |
LL | pub struct FfiUnsafe;
   | ^^^^^^^^^^^^^^^^^^^^

error: `extern` fn uses type `FfiUnsafe`, which is not FFI-safe
  --> $DIR/lint-ctypes-94223.rs:48:22
   |
LL | pub const BAD_CONST: extern "C" fn(FfiUnsafe) = f;
   |                      ^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
   |
   = help: consider adding a `#[repr(C)]` or `#[repr(transparent)]` attribute to this struct
   = note: this struct has unspecified layout
note: the type is defined here
  --> $DIR/lint-ctypes-94223.rs:34:1
   |
LL | pub struct FfiUnsafe;
   | ^^^^^^^^^^^^^^^^^^^^

error: aborting due to 12 previous errors