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Rework unsize documentation

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This commit is contained in:
Michael Goulet 2023-11-01 20:16:24 +00:00
parent 6af30ec720
commit 1221b7b652
1 changed files with 12 additions and 5 deletions
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17
library/core/src/marker.rs
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@ -155,11 +155,18 @@ pub trait Sized {
/// Those implementations are:
///
/// - Arrays `[T; N]` implement `Unsize<[T]>`.
/// - Types implementing a trait `Trait` also implement `Unsize<dyn Trait>`.
/// - Structs `Foo<..., T, ...>` implement `Unsize<Foo<..., U, ...>>` if all of these conditions
/// are met:
/// - Only the last field of `Foo` has a type involving `T`.
/// - `Bar<T>: Unsize<Bar<U>>`, where `Bar<T>` stands for the actual type of that last field.
/// - A type implements `Unsize<dyn Trait + 'a>` if all of these conditions are met:
/// - The type implements `Trait`.
/// - `Trait` is object safe.
/// - The type is sized.
/// - The type outlives `'a`.
/// - Structs `Foo<..., T1, ..., Tn, ...>` implement `Unsize<Foo<..., U1, ..., Un, ...>>`
/// where any number of (type and const) parameters may be changed if all of these conditions
/// are met:
/// - Only the last field of `Foo` has a type involving the parameters `T1`, ..., `Tn`.
/// - All other parameters of the struct are equal.
/// - `Field<T1, ..., Tn>: Unsize<Field<U1, ..., Un>>`, where `Field<...>` stands for the actual
/// type of the struct's last field.
///
/// `Unsize` is used along with [`ops::CoerceUnsized`] to allow
/// "user-defined" containers such as [`Rc`] to contain dynamically-sized