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have Result docs match ABI docs

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Ralf Jung
2025-09-13 21:05:30 +02:00
committed by Travis Cross
parent 781432e355
commit 058f08dd78
1 changed files with 4 additions and 8 deletions
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library/core/src/result.rs
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@@ -232,20 +232,16 @@
//! //!
//! In some cases, [`Result<T, E>`] comes with size, alignment, and ABI guarantees. //! In some cases, [`Result<T, E>`] comes with size, alignment, and ABI guarantees.
//! Specifically, one of either the `T` or `E` type must be a type that qualifies for the `Option` //! Specifically, one of either the `T` or `E` type must be a type that qualifies for the `Option`
//! [representation guarantees][opt-rep] (let's call that type `I`), and the *other* type must meet //! [representation guarantees][opt-rep] (let's call that type `I`), and the *other* type
//! all of the following conditions: //! is a zero-sized type with alignment 1 (a "1-ZST").
//! * Is a zero-sized type with alignment 1 (a "1-ZST").
//! * Is either a struct/tuple with no fields, or an enum with no variants.
//! * Does not have the `#[non_exhaustive]` attribute.
//! //!
//! If that is the case, then `Result<T, E>` has the same size, alignment, and [function call ABI] //! If that is the case, then `Result<T, E>` has the same size, alignment, and [function call ABI]
//! as `I` (and therefore, as `Option<I>`). If `I` is `T`, it is therefore sound to transmute `t: I` //! as `I` (and therefore, as `Option<I>`). If `I` is `T`, it is therefore sound to transmute `t: I`
//! to `Result<T, E>` (which will produce `Ok(t)`), and to transmute `Ok(t): Result<T, E>` to `I` //! to `Result<T, E>` (which will produce `Ok(t)`), and to transmute `Ok(t): Result<T, E>` to `I`
//! (which will produce `t`). If `I` is `E`, the same applies with `Ok` replaced by `Err`. //! (which will produce `t`). If `I` is `E`, the same applies with `Ok` replaced by `Err`.
//! //!
//! For example, `NonZeroI32` qualifies for the `Option` representation //! For example, `NonZeroI32` qualifies for the `Option` representation guarantees, and `()` is a
//! guarantees, and `()` is a zero-sized type with alignment 1, no fields, and //! zero-sized type with alignment 1. This means that both `Result<NonZeroI32, ()>` and
//! it isn't `non_exhaustive`. This means that both `Result<NonZeroI32, ()>` and
//! `Result<(), NonZeroI32>` have the same size, alignment, and ABI //! `Result<(), NonZeroI32>` have the same size, alignment, and ABI
//! as `NonZeroI32` (and `Option<NonZeroI32>`). The only difference is the implied semantics: //! as `NonZeroI32` (and `Option<NonZeroI32>`). The only difference is the implied semantics:
//! * `Option<NonZeroI32>` is "a non-zero i32 might be present" //! * `Option<NonZeroI32>` is "a non-zero i32 might be present"