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| -rw-r--r-- | src/libstd/keyword_docs.rs | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs index b5593e44f8b..db447c1b363 100644 --- a/src/libstd/keyword_docs.rs +++ b/src/libstd/keyword_docs.rs @@ -8,6 +8,33 @@ // option. This file may not be copied, modified, or distributed // except according to those terms. +#[doc(keyword = "as")] +// +/// The type coercion keyword +/// +/// `as` is most commonly used to turn primitive types into other primitive types, but it has other +/// uses that include turning pointers into addresses, addresses into pointers, and pointers into +/// other pointers. +/// +/// ```rust +/// let thing1: u8 = 89.0 as u8; +/// assert_eq!('B' as u32, 66); +/// assert_eq!(thing1 as char, 'Y'); +/// let thing2: f32 = thing1 as f32 + 10.5; +/// assert_eq!(true as u8 + thing2 as u8, 100); +/// ``` +/// +/// In general, any coercion that can be performed via writing out type hints can also be done +/// using `as`, so instead of writing `let x: u32 = 123`, you can write `let x = 123 as u32` (Note: +/// `let x = 123u32` would be best in that situation). The same is not true in the other direction, +/// however, explicitly using `as` allows a few more coercions that aren't allowed implicitly, such +/// as changing the type of a raw pointer or turning closures into raw pointers. +/// +/// For more information on what `as` is capable of, see the [Reference] +/// +/// [Reference]: https://doc.rust-lang.org/reference/expressions/operator-expr.html#type-cast-expressions +mod as_keyword { } + #[doc(keyword = "fn")] // /// The `fn` keyword. |