diff --git a/compiler/rustc_feature/src/accepted.rs b/compiler/rustc_feature/src/accepted.rs
index 0c5fe6e8d8b76..534458046945c 100644
--- a/compiler/rustc_feature/src/accepted.rs
+++ b/compiler/rustc_feature/src/accepted.rs
@@ -353,6 +353,9 @@ declare_features! (
(accepted, repr_packed, "1.33.0", Some(33158)),
/// Allows `#[repr(transparent)]` attribute on newtype structs.
(accepted, repr_transparent, "1.28.0", Some(43036)),
+ /// Allows enums like Result<T, E> to be used across FFI, if T's niche value can
+ /// be used to describe E or vice-versa.
+ (accepted, result_ffi_guarantees, "CURRENT_RUSTC_VERSION", Some(110503)),
/// Allows return-position `impl Trait` in traits.
(accepted, return_position_impl_trait_in_trait, "1.75.0", Some(91611)),
/// Allows code like `let x: &'static u32 = &42` to work (RFC 1414).
diff --git a/compiler/rustc_feature/src/unstable.rs b/compiler/rustc_feature/src/unstable.rs
index 1067156958dc1..fc3696c402265 100644
--- a/compiler/rustc_feature/src/unstable.rs
+++ b/compiler/rustc_feature/src/unstable.rs
@@ -580,9 +580,6 @@ declare_features! (
(incomplete, repr128, "1.16.0", Some(56071)),
/// Allows `repr(simd)` and importing the various simd intrinsics.
(unstable, repr_simd, "1.4.0", Some(27731)),
- /// Allows enums like Result<T, E> to be used across FFI, if T's niche value can
- /// be used to describe E or vise-versa.
- (unstable, result_ffi_guarantees, "1.80.0", Some(110503)),
/// Allows bounding the return type of AFIT/RPITIT.
(unstable, return_type_notation, "1.70.0", Some(109417)),
/// Allows `extern "rust-cold"`.
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index db4413149a49f..ce65ce2b6be66 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -728,7 +728,6 @@ fn is_niche_optimization_candidate<'tcx>(
/// can, return the type that `ty` can be safely converted to, otherwise return `None`.
/// Currently restricted to function pointers, boxes, references, `core::num::NonZero`,
/// `core::ptr::NonNull`, and `#[repr(transparent)]` newtypes.
-/// FIXME: This duplicates code in codegen.
pub(crate) fn repr_nullable_ptr<'tcx>(
tcx: TyCtxt<'tcx>,
param_env: ty::ParamEnv<'tcx>,
@@ -741,10 +740,6 @@ pub(crate) fn repr_nullable_ptr<'tcx>(
[var_one, var_two] => match (&var_one.fields.raw[..], &var_two.fields.raw[..]) {
([], [field]) | ([field], []) => field.ty(tcx, args),
([field1], [field2]) => {
- if !tcx.features().result_ffi_guarantees {
- return None;
- }
-
let ty1 = field1.ty(tcx, args);
let ty2 = field2.ty(tcx, args);
diff --git a/src/doc/unstable-book/src/language-features/result-ffi-guarantees.md b/src/doc/unstable-book/src/language-features/result-ffi-guarantees.md
deleted file mode 100644
index dc9c196524ed4..0000000000000
--- a/src/doc/unstable-book/src/language-features/result-ffi-guarantees.md
+++ /dev/null
@@ -1,14 +0,0 @@
-# `result_ffi_guarantees`
-
-The tracking issue for this feature is: [#110503]
-
-[#110503]: https://github.com/rust-lang/rust/issues/110503
-
-------------------------
-
-This feature adds the possibility of using `Result<T, E>` in FFI if T's niche
-value can be used to describe E or vise-versa.
-
-See [RFC 3391] for more information.
-
-[RFC 3391]: https://github.com/rust-lang/rfcs/blob/master/text/3391-result_ffi_guarantees.md
diff --git a/tests/ui/feature-gates/feature-gate-result_ffi_guarantees.rs b/tests/ui/feature-gates/feature-gate-result_ffi_guarantees.rs
deleted file mode 100644
index dda317aecc3c3..0000000000000
--- a/tests/ui/feature-gates/feature-gate-result_ffi_guarantees.rs
+++ /dev/null
@@ -1,99 +0,0 @@
-#![allow(dead_code)]
-#![deny(improper_ctypes)]
-#![feature(ptr_internals)]
-
-use std::num;
-
-enum Z {}
-
-#[repr(transparent)]
-struct TransparentStruct<T>(T, std::marker::PhantomData<Z>);
-
-#[repr(transparent)]
-enum TransparentEnum<T> {
- Variant(T, std::marker::PhantomData<Z>),
-}
-
-struct NoField;
-
-extern "C" {
- fn result_ref_t(x: Result<&'static u8, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_fn_t(x: Result<extern "C" fn(), ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonnull_t(x: Result<std::ptr::NonNull<u8>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_unique_t(x: Result<std::ptr::Unique<u8>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u8_t(x: Result<num::NonZero<u8>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u16_t(x: Result<num::NonZero<u16>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u32_t(x: Result<num::NonZero<u32>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u64_t(x: Result<num::NonZero<u64>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_usize_t(x: Result<num::NonZero<usize>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i8_t(x: Result<num::NonZero<i8>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i16_t(x: Result<num::NonZero<i16>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i32_t(x: Result<num::NonZero<i32>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i64_t(x: Result<num::NonZero<i64>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_isize_t(x: Result<num::NonZero<isize>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_transparent_struct_t(x: Result<TransparentStruct<num::NonZero<u8>>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_transparent_enum_t(x: Result<TransparentEnum<num::NonZero<u8>>, ()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_phantom_t(x: Result<num::NonZero<u8>, std::marker::PhantomData<()>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_1zst_exhaustive_no_variant_t(x: Result<num::NonZero<u8>, Z>);
- //~^ ERROR `extern` block uses type `Result
- fn result_1zst_exhaustive_no_field_t(x: Result<num::NonZero<u8>, NoField>);
- //~^ ERROR `extern` block uses type `Result
-
- fn result_ref_e(x: Result<(), &'static u8>);
- //~^ ERROR `extern` block uses type `Result
- fn result_fn_e(x: Result<(), extern "C" fn()>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonnull_e(x: Result<(), std::ptr::NonNull<u8>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_unique_e(x: Result<(), std::ptr::Unique<u8>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u8_e(x: Result<(), num::NonZero<u8>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u16_e(x: Result<(), num::NonZero<u16>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u32_e(x: Result<(), num::NonZero<u32>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_u64_e(x: Result<(), num::NonZero<u64>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_usize_e(x: Result<(), num::NonZero<usize>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i8_e(x: Result<(), num::NonZero<i8>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i16_e(x: Result<(), num::NonZero<i16>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i32_e(x: Result<(), num::NonZero<i32>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_i64_e(x: Result<(), num::NonZero<i64>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_nonzero_isize_e(x: Result<(), num::NonZero<isize>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_transparent_struct_e(x: Result<(), TransparentStruct<num::NonZero<u8>>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_transparent_enum_e(x: Result<(), TransparentEnum<num::NonZero<u8>>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_phantom_e(x: Result<num::NonZero<u8>, std::marker::PhantomData<()>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_1zst_exhaustive_no_variant_e(x: Result<Z, num::NonZero<u8>>);
- //~^ ERROR `extern` block uses type `Result
- fn result_1zst_exhaustive_no_field_e(x: Result<NoField, num::NonZero<u8>>);
- //~^ ERROR `extern` block uses type `Result
-}
-
-pub fn main() {}
diff --git a/tests/ui/feature-gates/feature-gate-result_ffi_guarantees.stderr b/tests/ui/feature-gates/feature-gate-result_ffi_guarantees.stderr
deleted file mode 100644
index 94416eb99c878..0000000000000
--- a/tests/ui/feature-gates/feature-gate-result_ffi_guarantees.stderr
+++ /dev/null
@@ -1,349 +0,0 @@
-error: `extern` block uses type `Result<&u8, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:20:24
- |
-LL | fn result_ref_t(x: Result<&'static u8, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
- |
- = help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
- = note: enum has no representation hint
-note: the lint level is defined here
- --> $DIR/feature-gate-result_ffi_guarantees.rs:2:9
- |
-LL | #![deny(improper_ctypes)]
- | ^^^^^^^^^^^^^^^
-
-error: `extern` block uses type `Result<extern "C" fn(), ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:22:23
- |
-LL | fn result_fn_t(x: Result<extern "C" fn(), ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonNull<u8>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:24:28
- |
-LL | fn result_nonnull_t(x: Result<std::ptr::NonNull<u8>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<Unique<u8>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:26:27
- |
-LL | fn result_unique_t(x: Result<std::ptr::Unique<u8>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u8>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:28:31
- |
-LL | fn result_nonzero_u8_t(x: Result<num::NonZero<u8>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u16>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:30:32
- |
-LL | fn result_nonzero_u16_t(x: Result<num::NonZero<u16>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u32>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:32:32
- |
-LL | fn result_nonzero_u32_t(x: Result<num::NonZero<u32>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u64>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:34:32
- |
-LL | fn result_nonzero_u64_t(x: Result<num::NonZero<u64>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<usize>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:36:34
- |
-LL | fn result_nonzero_usize_t(x: Result<num::NonZero<usize>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<i8>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:38:31
- |
-LL | fn result_nonzero_i8_t(x: Result<num::NonZero<i8>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<i16>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:40:32
- |
-LL | fn result_nonzero_i16_t(x: Result<num::NonZero<i16>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<i32>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:42:32
- |
-LL | fn result_nonzero_i32_t(x: Result<num::NonZero<i32>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<i64>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:44:32
- |
-LL | fn result_nonzero_i64_t(x: Result<num::NonZero<i64>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<isize>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:46:34
- |
-LL | fn result_nonzero_isize_t(x: Result<num::NonZero<isize>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<TransparentStruct<NonZero<u8>>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:48:39
- |
-LL | fn result_transparent_struct_t(x: Result<TransparentStruct<num::NonZero<u8>>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<TransparentEnum<NonZero<u8>>, ()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:50:37
- |
-LL | fn result_transparent_enum_t(x: Result<TransparentEnum<num::NonZero<u8>>, ()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u8>, PhantomData<()>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:52:28
- |
-LL | fn result_phantom_t(x: Result<num::NonZero<u8>, std::marker::PhantomData<()>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u8>, Z>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:54:47
- |
-LL | fn result_1zst_exhaustive_no_variant_t(x: Result<num::NonZero<u8>, Z>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u8>, NoField>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:56:45
- |
-LL | fn result_1zst_exhaustive_no_field_t(x: Result<num::NonZero<u8>, NoField>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), &u8>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:59:24
- |
-LL | fn result_ref_e(x: Result<(), &'static u8>);
- | ^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), extern "C" fn()>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:61:23
- |
-LL | fn result_fn_e(x: Result<(), extern "C" fn()>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonNull<u8>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:63:28
- |
-LL | fn result_nonnull_e(x: Result<(), std::ptr::NonNull<u8>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), Unique<u8>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:65:27
- |
-LL | fn result_unique_e(x: Result<(), std::ptr::Unique<u8>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<u8>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:67:31
- |
-LL | fn result_nonzero_u8_e(x: Result<(), num::NonZero<u8>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<u16>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:69:32
- |
-LL | fn result_nonzero_u16_e(x: Result<(), num::NonZero<u16>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<u32>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:71:32
- |
-LL | fn result_nonzero_u32_e(x: Result<(), num::NonZero<u32>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<u64>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:73:32
- |
-LL | fn result_nonzero_u64_e(x: Result<(), num::NonZero<u64>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<usize>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:75:34
- |
-LL | fn result_nonzero_usize_e(x: Result<(), num::NonZero<usize>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<i8>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:77:31
- |
-LL | fn result_nonzero_i8_e(x: Result<(), num::NonZero<i8>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<i16>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:79:32
- |
-LL | fn result_nonzero_i16_e(x: Result<(), num::NonZero<i16>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<i32>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:81:32
- |
-LL | fn result_nonzero_i32_e(x: Result<(), num::NonZero<i32>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<i64>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:83:32
- |
-LL | fn result_nonzero_i64_e(x: Result<(), num::NonZero<i64>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), NonZero<isize>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:85:34
- |
-LL | fn result_nonzero_isize_e(x: Result<(), num::NonZero<isize>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), TransparentStruct<NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:87:39
- |
-LL | fn result_transparent_struct_e(x: Result<(), TransparentStruct<num::NonZero<u8>>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<(), TransparentEnum<NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:89:37
- |
-LL | fn result_transparent_enum_e(x: Result<(), TransparentEnum<num::NonZero<u8>>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NonZero<u8>, PhantomData<()>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:91:28
- |
-LL | fn result_phantom_e(x: Result<num::NonZero<u8>, std::marker::PhantomData<()>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<Z, NonZero<u8>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:93:47
- |
-LL | fn result_1zst_exhaustive_no_variant_e(x: Result<Z, num::NonZero<u8>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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` block uses type `Result<NoField, NonZero<u8>>`, which is not FFI-safe
- --> $DIR/feature-gate-result_ffi_guarantees.rs:95:45
- |
-LL | fn result_1zst_exhaustive_no_field_e(x: Result<NoField, num::NonZero<u8>>);
- | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 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: aborting due to 38 previous errors
-
diff --git a/tests/ui/lint/lint-ctypes-enum.rs b/tests/ui/lint/lint-ctypes-enum.rs
index cb8e9e8067513..19af1de95760b 100644
--- a/tests/ui/lint/lint-ctypes-enum.rs
+++ b/tests/ui/lint/lint-ctypes-enum.rs
@@ -2,7 +2,6 @@
#![deny(improper_ctypes)]
#![feature(ptr_internals)]
#![feature(transparent_unions)]
-#![feature(result_ffi_guarantees)]
use std::num;
diff --git a/tests/ui/lint/lint-ctypes-enum.stderr b/tests/ui/lint/lint-ctypes-enum.stderr
index bba5b09b69cc9..8e92e7e694627 100644
--- a/tests/ui/lint/lint-ctypes-enum.stderr
+++ b/tests/ui/lint/lint-ctypes-enum.stderr
@@ -1,5 +1,5 @@
error: `extern` block uses type `U`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:69:14
+ --> $DIR/lint-ctypes-enum.rs:68:14
|
LL | fn uf(x: U);
| ^ not FFI-safe
@@ -7,7 +7,7 @@ LL | fn uf(x: U);
= help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
= note: enum has no representation hint
note: the type is defined here
- --> $DIR/lint-ctypes-enum.rs:10:1
+ --> $DIR/lint-ctypes-enum.rs:9:1
|
LL | enum U {
| ^^^^^^
@@ -18,7 +18,7 @@ LL | #![deny(improper_ctypes)]
| ^^^^^^^^^^^^^^^
error: `extern` block uses type `B`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:70:14
+ --> $DIR/lint-ctypes-enum.rs:69:14
|
LL | fn bf(x: B);
| ^ not FFI-safe
@@ -26,13 +26,13 @@ LL | fn bf(x: B);
= help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
= note: enum has no representation hint
note: the type is defined here
- --> $DIR/lint-ctypes-enum.rs:13:1
+ --> $DIR/lint-ctypes-enum.rs:12:1
|
LL | enum B {
| ^^^^^^
error: `extern` block uses type `T`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:71:14
+ --> $DIR/lint-ctypes-enum.rs:70:14
|
LL | fn tf(x: T);
| ^ not FFI-safe
@@ -40,13 +40,13 @@ LL | fn tf(x: T);
= help: consider adding a `#[repr(C)]`, `#[repr(transparent)]`, or integer `#[repr(...)]` attribute to this enum
= note: enum has no representation hint
note: the type is defined here
- --> $DIR/lint-ctypes-enum.rs:17:1
+ --> $DIR/lint-ctypes-enum.rs:16:1
|
LL | enum T {
| ^^^^^^
error: `extern` block uses type `u128`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:83:31
+ --> $DIR/lint-ctypes-enum.rs:82:31
|
LL | fn option_nonzero_u128(x: Option<num::NonZero<u128>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -54,7 +54,7 @@ LL | fn option_nonzero_u128(x: Option<num::NonZero<u128>>);
= note: 128-bit integers don't currently have a known stable ABI
error: `extern` block uses type `i128`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:90:31
+ --> $DIR/lint-ctypes-enum.rs:89:31
|
LL | fn option_nonzero_i128(x: Option<num::NonZero<i128>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -62,7 +62,7 @@ LL | fn option_nonzero_i128(x: Option<num::NonZero<i128>>);
= note: 128-bit integers don't currently have a known stable ABI
error: `extern` block uses type `Option<TransparentUnion<NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:95:36
+ --> $DIR/lint-ctypes-enum.rs:94:36
|
LL | fn option_transparent_union(x: Option<TransparentUnion<num::NonZero<u8>>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -71,7 +71,7 @@ LL | fn option_transparent_union(x: Option<TransparentUnion<num::NonZero<u8>
= note: enum has no representation hint
error: `extern` block uses type `Option<Rust<NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:97:28
+ --> $DIR/lint-ctypes-enum.rs:96:28
|
LL | fn option_repr_rust(x: Option<Rust<num::NonZero<u8>>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -80,7 +80,7 @@ LL | fn option_repr_rust(x: Option<Rust<num::NonZero<u8>>>);
= note: enum has no representation hint
error: `extern` block uses type `u128`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:107:33
+ --> $DIR/lint-ctypes-enum.rs:106:33
|
LL | fn result_nonzero_u128_t(x: Result<num::NonZero<u128>, ()>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -88,7 +88,7 @@ LL | fn result_nonzero_u128_t(x: Result<num::NonZero<u128>, ()>);
= note: 128-bit integers don't currently have a known stable ABI
error: `extern` block uses type `i128`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:114:33
+ --> $DIR/lint-ctypes-enum.rs:113:33
|
LL | fn result_nonzero_i128_t(x: Result<num::NonZero<i128>, ()>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -96,7 +96,7 @@ LL | fn result_nonzero_i128_t(x: Result<num::NonZero<i128>, ()>);
= note: 128-bit integers don't currently have a known stable ABI
error: `extern` block uses type `Result<TransparentUnion<NonZero<u8>>, ()>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:119:38
+ --> $DIR/lint-ctypes-enum.rs:118:38
|
LL | fn result_transparent_union_t(x: Result<TransparentUnion<num::NonZero<u8>>, ()>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -105,7 +105,7 @@ LL | fn result_transparent_union_t(x: Result<TransparentUnion<num::NonZero<u
= note: enum has no representation hint
error: `extern` block uses type `Result<Rust<NonZero<u8>>, ()>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:121:30
+ --> $DIR/lint-ctypes-enum.rs:120:30
|
LL | fn result_repr_rust_t(x: Result<Rust<num::NonZero<u8>>, ()>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -114,7 +114,7 @@ LL | fn result_repr_rust_t(x: Result<Rust<num::NonZero<u8>>, ()>);
= note: enum has no representation hint
error: `extern` block uses type `Result<NonZero<u8>, U>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:125:51
+ --> $DIR/lint-ctypes-enum.rs:124:51
|
LL | fn result_1zst_exhaustive_single_variant_t(x: Result<num::NonZero<u8>, U>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -123,7 +123,7 @@ LL | fn result_1zst_exhaustive_single_variant_t(x: Result<num::NonZero<u8>,
= note: enum has no representation hint
error: `extern` block uses type `Result<NonZero<u8>, B>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:127:53
+ --> $DIR/lint-ctypes-enum.rs:126:53
|
LL | fn result_1zst_exhaustive_multiple_variant_t(x: Result<num::NonZero<u8>, B>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -132,7 +132,7 @@ LL | fn result_1zst_exhaustive_multiple_variant_t(x: Result<num::NonZero<u8>
= note: enum has no representation hint
error: `extern` block uses type `Result<NonZero<u8>, NonExhaustive>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:129:51
+ --> $DIR/lint-ctypes-enum.rs:128:51
|
LL | fn result_1zst_non_exhaustive_no_variant_t(x: Result<num::NonZero<u8>, NonExhaustive>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -141,7 +141,7 @@ LL | fn result_1zst_non_exhaustive_no_variant_t(x: Result<num::NonZero<u8>,
= note: enum has no representation hint
error: `extern` block uses type `Result<NonZero<u8>, Field>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:132:49
+ --> $DIR/lint-ctypes-enum.rs:131:49
|
LL | fn result_1zst_exhaustive_single_field_t(x: Result<num::NonZero<u8>, Field>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -150,7 +150,7 @@ LL | fn result_1zst_exhaustive_single_field_t(x: Result<num::NonZero<u8>, Fi
= note: enum has no representation hint
error: `extern` block uses type `Result<Result<(), NonZero<u8>>, ()>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:134:30
+ --> $DIR/lint-ctypes-enum.rs:133:30
|
LL | fn result_cascading_t(x: Result<Result<(), num::NonZero<u8>>, ()>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -159,7 +159,7 @@ LL | fn result_cascading_t(x: Result<Result<(), num::NonZero<u8>>, ()>);
= note: enum has no representation hint
error: `extern` block uses type `u128`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:145:33
+ --> $DIR/lint-ctypes-enum.rs:144:33
|
LL | fn result_nonzero_u128_e(x: Result<(), num::NonZero<u128>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -167,7 +167,7 @@ LL | fn result_nonzero_u128_e(x: Result<(), num::NonZero<u128>>);
= note: 128-bit integers don't currently have a known stable ABI
error: `extern` block uses type `i128`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:152:33
+ --> $DIR/lint-ctypes-enum.rs:151:33
|
LL | fn result_nonzero_i128_e(x: Result<(), num::NonZero<i128>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -175,7 +175,7 @@ LL | fn result_nonzero_i128_e(x: Result<(), num::NonZero<i128>>);
= note: 128-bit integers don't currently have a known stable ABI
error: `extern` block uses type `Result<(), TransparentUnion<NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:157:38
+ --> $DIR/lint-ctypes-enum.rs:156:38
|
LL | fn result_transparent_union_e(x: Result<(), TransparentUnion<num::NonZero<u8>>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -184,7 +184,7 @@ LL | fn result_transparent_union_e(x: Result<(), TransparentUnion<num::NonZe
= note: enum has no representation hint
error: `extern` block uses type `Result<(), Rust<NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:159:30
+ --> $DIR/lint-ctypes-enum.rs:158:30
|
LL | fn result_repr_rust_e(x: Result<(), Rust<num::NonZero<u8>>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -193,7 +193,7 @@ LL | fn result_repr_rust_e(x: Result<(), Rust<num::NonZero<u8>>>);
= note: enum has no representation hint
error: `extern` block uses type `Result<U, NonZero<u8>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:163:51
+ --> $DIR/lint-ctypes-enum.rs:162:51
|
LL | fn result_1zst_exhaustive_single_variant_e(x: Result<U, num::NonZero<u8>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -202,7 +202,7 @@ LL | fn result_1zst_exhaustive_single_variant_e(x: Result<U, num::NonZero<u8
= note: enum has no representation hint
error: `extern` block uses type `Result<B, NonZero<u8>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:165:53
+ --> $DIR/lint-ctypes-enum.rs:164:53
|
LL | fn result_1zst_exhaustive_multiple_variant_e(x: Result<B, num::NonZero<u8>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -211,7 +211,7 @@ LL | fn result_1zst_exhaustive_multiple_variant_e(x: Result<B, num::NonZero<
= note: enum has no representation hint
error: `extern` block uses type `Result<NonExhaustive, NonZero<u8>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:167:51
+ --> $DIR/lint-ctypes-enum.rs:166:51
|
LL | fn result_1zst_non_exhaustive_no_variant_e(x: Result<NonExhaustive, num::NonZero<u8>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -220,7 +220,7 @@ LL | fn result_1zst_non_exhaustive_no_variant_e(x: Result<NonExhaustive, num
= note: enum has no representation hint
error: `extern` block uses type `Result<Field, NonZero<u8>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:170:49
+ --> $DIR/lint-ctypes-enum.rs:169:49
|
LL | fn result_1zst_exhaustive_single_field_e(x: Result<Field, num::NonZero<u8>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -229,7 +229,7 @@ LL | fn result_1zst_exhaustive_single_field_e(x: Result<Field, num::NonZero<
= note: enum has no representation hint
error: `extern` block uses type `Result<(), Result<(), NonZero<u8>>>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:172:30
+ --> $DIR/lint-ctypes-enum.rs:171:30
|
LL | fn result_cascading_e(x: Result<(), Result<(), num::NonZero<u8>>>);
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ not FFI-safe
@@ -238,7 +238,7 @@ LL | fn result_cascading_e(x: Result<(), Result<(), num::NonZero<u8>>>);
= note: enum has no representation hint
error: `extern` block uses type `Result<(), ()>`, which is not FFI-safe
- --> $DIR/lint-ctypes-enum.rs:174:27
+ --> $DIR/lint-ctypes-enum.rs:173:27
|
LL | fn result_unit_t_e(x: Result<(), ()>);
| ^^^^^^^^^^^^^^ not FFI-safe
diff --git a/tests/ui/rfcs/rfc-3391-result-ffi-guarantees.rs b/tests/ui/rfcs/rfc-3391-result-ffi-guarantees.rs
new file mode 100644
index 0000000000000..9b8092526b950
--- /dev/null
+++ b/tests/ui/rfcs/rfc-3391-result-ffi-guarantees.rs
@@ -0,0 +1,133 @@
+//@ build-pass
+/*!
+
+The guarantees in RFC 3391 were strengthened as a result of the 2024 Oct 09 T-lang meeting[^1]
+following the precedent of T-lang's guaranteeing[^2] ABI compatibility for "Option-like" enums[^2].
+We now guarantee ABI compatibility for enums that conform to these rules described by scottmcm:
+
+* The enum `E` has exactly two variants.
+* One variant has exactly one field, of type `T`.
+* `T` is a `rustc_nonnull_optimization_guaranteed` type.
+* All fields of the other variant are 1-ZSTs.
+
+Where "all" fields includes "there aren't any fields, so they're vacuously all 1-ZSTs".
+
+Note: "1-ZST" means a type of size 0 and alignment 1.
+
+The reason alignment of the zero-sized type matters is it can affect the alignment of the enum,
+which also will affect its size if the enum has a non-zero size.
+
+[^1]: <https://github.com/rust-lang/rust/pull/130628#issuecomment-2402761599>
+[^2]: <https://github.com/rust-lang/rust/pull/60300#issuecomment-487000474>
+
+*/
+
+#![allow(dead_code)]
+#![deny(improper_ctypes)]
+#![feature(ptr_internals)]
+
+use std::num;
+
+enum Z {}
+
+#[repr(transparent)]
+struct TransparentStruct<T>(T, std::marker::PhantomData<Z>);
+
+#[repr(transparent)]
+enum TransparentEnum<T> {
+ Variant(T, std::marker::PhantomData<Z>),
+}
+
+struct NoField;
+
+extern "C" {
+ fn result_ref_t(x: Result<&'static u8, ()>);
+ fn result_fn_t(x: Result<extern "C" fn(), ()>);
+ fn result_nonnull_t(x: Result<std::ptr::NonNull<u8>, ()>);
+ fn result_unique_t(x: Result<std::ptr::Unique<u8>, ()>);
+ fn result_nonzero_u8_t(x: Result<num::NonZero<u8>, ()>);
+ fn result_nonzero_u16_t(x: Result<num::NonZero<u16>, ()>);
+ fn result_nonzero_u32_t(x: Result<num::NonZero<u32>, ()>);
+ fn result_nonzero_u64_t(x: Result<num::NonZero<u64>, ()>);
+ fn result_nonzero_usize_t(x: Result<num::NonZero<usize>, ()>);
+ fn result_nonzero_i8_t(x: Result<num::NonZero<i8>, ()>);
+ fn result_nonzero_i16_t(x: Result<num::NonZero<i16>, ()>);
+ fn result_nonzero_i32_t(x: Result<num::NonZero<i32>, ()>);
+ fn result_nonzero_i64_t(x: Result<num::NonZero<i64>, ()>);
+ fn result_nonzero_isize_t(x: Result<num::NonZero<isize>, ()>);
+ fn result_transparent_struct_t(x: Result<TransparentStruct<num::NonZero<u8>>, ()>);
+ fn result_transparent_enum_t(x: Result<TransparentEnum<num::NonZero<u8>>, ()>);
+ fn result_phantom_t(x: Result<num::NonZero<u8>, std::marker::PhantomData<()>>);
+ fn result_1zst_exhaustive_no_variant_t(x: Result<num::NonZero<u8>, Z>);
+ fn result_1zst_exhaustive_no_field_t(x: Result<num::NonZero<u8>, NoField>);
+
+ fn result_ref_e(x: Result<(), &'static u8>);
+ fn result_fn_e(x: Result<(), extern "C" fn()>);
+ fn result_nonnull_e(x: Result<(), std::ptr::NonNull<u8>>);
+ fn result_unique_e(x: Result<(), std::ptr::Unique<u8>>);
+ fn result_nonzero_u8_e(x: Result<(), num::NonZero<u8>>);
+ fn result_nonzero_u16_e(x: Result<(), num::NonZero<u16>>);
+ fn result_nonzero_u32_e(x: Result<(), num::NonZero<u32>>);
+ fn result_nonzero_u64_e(x: Result<(), num::NonZero<u64>>);
+ fn result_nonzero_usize_e(x: Result<(), num::NonZero<usize>>);
+ fn result_nonzero_i8_e(x: Result<(), num::NonZero<i8>>);
+ fn result_nonzero_i16_e(x: Result<(), num::NonZero<i16>>);
+ fn result_nonzero_i32_e(x: Result<(), num::NonZero<i32>>);
+ fn result_nonzero_i64_e(x: Result<(), num::NonZero<i64>>);
+ fn result_nonzero_isize_e(x: Result<(), num::NonZero<isize>>);
+ fn result_transparent_struct_e(x: Result<(), TransparentStruct<num::NonZero<u8>>>);
+ fn result_transparent_enum_e(x: Result<(), TransparentEnum<num::NonZero<u8>>>);
+ fn result_phantom_e(x: Result<num::NonZero<u8>, std::marker::PhantomData<()>>);
+ fn result_1zst_exhaustive_no_variant_e(x: Result<Z, num::NonZero<u8>>);
+ fn result_1zst_exhaustive_no_field_e(x: Result<NoField, num::NonZero<u8>>);
+}
+
+// Custom "Result-like" enum for testing custom "Option-like" types are also accepted
+enum Either<L, R> {
+ Left(L),
+ Right(R),
+}
+
+extern "C" {
+ fn either_ref_t(x: Either<&'static u8, ()>);
+ fn either_fn_t(x: Either<extern "C" fn(), ()>);
+ fn either_nonnull_t(x: Either<std::ptr::NonNull<u8>, ()>);
+ fn either_unique_t(x: Either<std::ptr::Unique<u8>, ()>);
+ fn either_nonzero_u8_t(x: Either<num::NonZero<u8>, ()>);
+ fn either_nonzero_u16_t(x: Either<num::NonZero<u16>, ()>);
+ fn either_nonzero_u32_t(x: Either<num::NonZero<u32>, ()>);
+ fn either_nonzero_u64_t(x: Either<num::NonZero<u64>, ()>);
+ fn either_nonzero_usize_t(x: Either<num::NonZero<usize>, ()>);
+ fn either_nonzero_i8_t(x: Either<num::NonZero<i8>, ()>);
+ fn either_nonzero_i16_t(x: Either<num::NonZero<i16>, ()>);
+ fn either_nonzero_i32_t(x: Either<num::NonZero<i32>, ()>);
+ fn either_nonzero_i64_t(x: Either<num::NonZero<i64>, ()>);
+ fn either_nonzero_isize_t(x: Either<num::NonZero<isize>, ()>);
+ fn either_transparent_struct_t(x: Either<TransparentStruct<num::NonZero<u8>>, ()>);
+ fn either_transparent_enum_t(x: Either<TransparentEnum<num::NonZero<u8>>, ()>);
+ fn either_phantom_t(x: Either<num::NonZero<u8>, std::marker::PhantomData<()>>);
+ fn either_1zst_exhaustive_no_variant_t(x: Either<num::NonZero<u8>, Z>);
+ fn either_1zst_exhaustive_no_field_t(x: Either<num::NonZero<u8>, NoField>);
+
+ fn either_ref_e(x: Either<(), &'static u8>);
+ fn either_fn_e(x: Either<(), extern "C" fn()>);
+ fn either_nonnull_e(x: Either<(), std::ptr::NonNull<u8>>);
+ fn either_unique_e(x: Either<(), std::ptr::Unique<u8>>);
+ fn either_nonzero_u8_e(x: Either<(), num::NonZero<u8>>);
+ fn either_nonzero_u16_e(x: Either<(), num::NonZero<u16>>);
+ fn either_nonzero_u32_e(x: Either<(), num::NonZero<u32>>);
+ fn either_nonzero_u64_e(x: Either<(), num::NonZero<u64>>);
+ fn either_nonzero_usize_e(x: Either<(), num::NonZero<usize>>);
+ fn either_nonzero_i8_e(x: Either<(), num::NonZero<i8>>);
+ fn either_nonzero_i16_e(x: Either<(), num::NonZero<i16>>);
+ fn either_nonzero_i32_e(x: Either<(), num::NonZero<i32>>);
+ fn either_nonzero_i64_e(x: Either<(), num::NonZero<i64>>);
+ fn either_nonzero_isize_e(x: Either<(), num::NonZero<isize>>);
+ fn either_transparent_struct_e(x: Either<(), TransparentStruct<num::NonZero<u8>>>);
+ fn either_transparent_enum_e(x: Either<(), TransparentEnum<num::NonZero<u8>>>);
+ fn either_phantom_e(x: Either<num::NonZero<u8>, std::marker::PhantomData<()>>);
+ fn either_1zst_exhaustive_no_variant_e(x: Either<Z, num::NonZero<u8>>);
+ fn either_1zst_exhaustive_no_field_e(x: Either<NoField, num::NonZero<u8>>);
+}
+
+pub fn main() {}