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| author | Kevin Reid <kpreid@switchb.org> | 2024-12-20 14:58:37 -0800 |
|---|---|---|
| committer | Kevin Reid <kpreid@switchb.org> | 2024-12-20 20:47:03 -0800 |
| commit | da6616c54fad4af6459feaebd48bedb2cc7fae08 (patch) | |
| tree | debc6a4658d71a6c6f323213d718da417aa1a18a | |
| parent | 13170cd787cb733ed24842ee825bcbd98dc01476 (diff) | |
| download | rust-da6616c54fad4af6459feaebd48bedb2cc7fae08.tar.gz rust-da6616c54fad4af6459feaebd48bedb2cc7fae08.zip | |
Document `PointerLike` implementation restrictions.
| -rw-r--r-- | library/core/src/marker.rs | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/library/core/src/marker.rs b/library/core/src/marker.rs index 3d79706f8ec..d0d8609f43f 100644 --- a/library/core/src/marker.rs +++ b/library/core/src/marker.rs @@ -982,8 +982,14 @@ pub trait Tuple {} /// A marker for pointer-like types. /// -/// This trait can only be implemented for types that have the same size and alignment -/// as a `usize` or `*const ()`. +/// This trait can only be implemented for types that are certain to have +/// the same size and alignment as a [`usize`] or [`*const ()`](pointer). +/// To ensure this, there are special requirements on implementations +/// of `PointerLike` (other than the already-provided implementations +/// for built-in types): +/// +/// * The type must have `#[repr(transparent)]`. +/// * The type’s sole non-zero-sized field must itself implement `PointerLike`. #[unstable(feature = "pointer_like_trait", issue = "none")] #[lang = "pointer_like"] #[diagnostic::on_unimplemented( |