3 Welcome to the Unstable Book! This book consists of a number of chapters,
4 each one organized by a "feature flag." That is, when using an unstable
5 feature of Rust, you must use a flag, like this:
8 #![feature(box_syntax)]
15 The `box_syntax` feature [has a chapter][box] describing how to use it.
17 [box]: language-features/box-syntax.md
19 Because this documentation relates to unstable features, we make no guarantees
20 that what is contained here is accurate or up to date. It's developed on a
21 best-effort basis. Each page will have a link to its tracking issue with the
22 latest developments; you might want to check those as well.