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Document PointerLike implementation restrictions.

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This commit is contained in:
Kevin Reid 2024-12-20 14:58:37 -08:00
parent 13170cd787
commit da6616c54f
1 changed files with 8 additions and 2 deletions
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10
library/core/src/marker.rs
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@ -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(