Auto merge of #63991 - Centril:unique-improper-ctype, r=rkruppe

`improper_ctypes`: guard against accidental change to `Unique<T>`

r? @eddyb

src/test/ui/lint/lint-ctypes-enum.rs

@@ -1,4 +1,5 @@
 #![feature(transparent_enums, transparent_unions)]
+#![feature(ptr_internals)]
 #![deny(improper_ctypes)]
 #![allow(dead_code)]
 
@@ -44,6 +45,7 @@ extern {
    fn option_ref(x: Option<&'static u8>);
    fn option_fn(x: Option<extern "C" fn()>);
    fn nonnull(x: Option<std::ptr::NonNull<u8>>);
+   fn unique(x: Option<std::ptr::Unique<u8>>); //~ ERROR enum has no representation hint
    fn nonzero_u8(x: Option<num::NonZeroU8>);
    fn nonzero_u16(x: Option<num::NonZeroU16>);
    fn nonzero_u32(x: Option<num::NonZeroU32>);

src/test/ui/lint/lint-ctypes-enum.stderr

@@ -1,82 +1,90 @@
 error: `extern` block uses type `U` which is not FFI-safe: enum has no representation hint
-  --> $DIR/lint-ctypes-enum.rs:38:13
+  --> $DIR/lint-ctypes-enum.rs:39:13
    |
 LL |    fn uf(x: U);
    |             ^
    |
 note: lint level defined here
-  --> $DIR/lint-ctypes-enum.rs:2:9
+  --> $DIR/lint-ctypes-enum.rs:3:9
    |
 LL | #![deny(improper_ctypes)]
    |         ^^^^^^^^^^^^^^^
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
 note: type defined here
-  --> $DIR/lint-ctypes-enum.rs:8:1
+  --> $DIR/lint-ctypes-enum.rs:9:1
    |
 LL | enum U { A }
    | ^^^^^^^^^^^^
 
 error: `extern` block uses type `B` which is not FFI-safe: enum has no representation hint
-  --> $DIR/lint-ctypes-enum.rs:39:13
+  --> $DIR/lint-ctypes-enum.rs:40:13
    |
 LL |    fn bf(x: B);
    |             ^
    |
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
 note: type defined here
-  --> $DIR/lint-ctypes-enum.rs:9:1
+  --> $DIR/lint-ctypes-enum.rs:10:1
    |
 LL | enum B { C, D }
    | ^^^^^^^^^^^^^^^
 
 error: `extern` block uses type `T` which is not FFI-safe: enum has no representation hint
-  --> $DIR/lint-ctypes-enum.rs:40:13
+  --> $DIR/lint-ctypes-enum.rs:41:13
    |
 LL |    fn tf(x: T);
    |             ^
    |
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
 note: type defined here
-  --> $DIR/lint-ctypes-enum.rs:10:1
+  --> $DIR/lint-ctypes-enum.rs:11:1
    |
 LL | enum T { E, F, G }
    | ^^^^^^^^^^^^^^^^^^
 
+error: `extern` block uses type `std::option::Option<std::ptr::Unique<u8>>` which is not FFI-safe: enum has no representation hint
+  --> $DIR/lint-ctypes-enum.rs:48:17
+   |
+LL |    fn unique(x: Option<std::ptr::Unique<u8>>);
+   |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
+
 error: `extern` block uses type `u128` which is not FFI-safe: 128-bit integers don't currently have a known stable ABI
-  --> $DIR/lint-ctypes-enum.rs:51:23
+  --> $DIR/lint-ctypes-enum.rs:53:23
    |
 LL |    fn nonzero_u128(x: Option<num::NonZeroU128>);
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `extern` block uses type `i128` which is not FFI-safe: 128-bit integers don't currently have a known stable ABI
-  --> $DIR/lint-ctypes-enum.rs:58:23
+  --> $DIR/lint-ctypes-enum.rs:60:23
    |
 LL |    fn nonzero_i128(x: Option<num::NonZeroI128>);
    |                       ^^^^^^^^^^^^^^^^^^^^^^^^
 
 error: `extern` block uses type `std::option::Option<TransparentUnion<std::num::NonZeroU8>>` which is not FFI-safe: enum has no representation hint
-  --> $DIR/lint-ctypes-enum.rs:63:28
+  --> $DIR/lint-ctypes-enum.rs:65:28
    |
 LL |    fn transparent_union(x: Option<TransparentUnion<num::NonZeroU8>>);
    |                            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
 
 error: `extern` block uses type `std::option::Option<Rust<std::num::NonZeroU8>>` which is not FFI-safe: enum has no representation hint
-  --> $DIR/lint-ctypes-enum.rs:65:20
+  --> $DIR/lint-ctypes-enum.rs:67:20
    |
 LL |    fn repr_rust(x: Option<Rust<num::NonZeroU8>>);
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
 
 error: `extern` block uses type `std::result::Result<(), std::num::NonZeroI32>` which is not FFI-safe: enum has no representation hint
-  --> $DIR/lint-ctypes-enum.rs:66:20
+  --> $DIR/lint-ctypes-enum.rs:68:20
    |
 LL |    fn no_result(x: Result<(), num::NonZeroI32>);
    |                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
 
-error: aborting due to 8 previous errors
+error: aborting due to 9 previous errors