diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs index a4996d9eee810..b2658529e57cf 100644 --- a/src/libstd/keyword_docs.rs +++ b/src/libstd/keyword_docs.rs @@ -1000,9 +1000,55 @@ mod ref_keyword {} // /// Return a value from a function. /// -/// The documentation for this keyword is [not yet complete]. Pull requests welcome! +/// A `return` marks the end of an execution path in a function: /// -/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601 +/// ``` +/// fn foo() -> i32 { +/// return 3; +/// } +/// assert_eq!(foo(), 3); +/// ``` +/// +/// `return` is not needed when the returned value is the last expression in the +/// function. In this case the `;` is omitted: +/// +/// ``` +/// fn foo() -> i32 { +/// 3 +/// } +/// assert_eq!(foo(), 3); +/// ``` +/// +/// `return` returns from the function immediately (an "early return"): +/// +/// ```no_run +/// use std::fs::File; +/// use std::io::{Error, ErrorKind, Read, Result}; +/// +/// fn main() -> Result<()> { +/// let mut file = match File::open("foo.txt") { +/// Ok(f) => f, +/// Err(e) => return Err(e), +/// }; +/// +/// let mut contents = String::new(); +/// let size = match file.read_to_string(&mut contents) { +/// Ok(s) => s, +/// Err(e) => return Err(e), +/// }; +/// +/// if contents.contains("impossible!") { +/// return Err(Error::new(ErrorKind::Other, "oh no!")); +/// } +/// +/// if size > 9000 { +/// return Err(Error::new(ErrorKind::Other, "over 9000!")); +/// } +/// +/// assert_eq!(contents, "Hello, world!"); +/// Ok(()) +/// } +/// ``` mod return_keyword {} #[doc(keyword = "self")]