From 4c7e866fc8e0d4025c3e9c97dde8688b4a0dd8f8 Mon Sep 17 00:00:00 2001 From: dianne Date: Fri, 18 Apr 2025 21:49:40 -0700 Subject: update unstable book to mention string/bytestring typing --- .../src/language-features/deref-patterns.md | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'src') diff --git a/src/doc/unstable-book/src/language-features/deref-patterns.md b/src/doc/unstable-book/src/language-features/deref-patterns.md index d0102a665b0..d0a64538e8c 100644 --- a/src/doc/unstable-book/src/language-features/deref-patterns.md +++ b/src/doc/unstable-book/src/language-features/deref-patterns.md @@ -54,4 +54,25 @@ if let [b] = &mut *v { assert_eq!(v, [Box::new(Some(2))]); ``` +Additionally, when `deref_patterns` is enabled, string literal patterns may be written where `str` +is expected. Likewise, byte string literal patterns may be written where `[u8]` or `[u8; _]` is +expected. This lets them be used in `deref!(_)` patterns: + +```rust +# #![feature(deref_patterns)] +# #![allow(incomplete_features)] +match ("test".to_string(), b"test".to_vec()) { + (deref!("test"), deref!(b"test")) => {} + _ => panic!(), +} + +// Matching on slices and arrays using literals is possible elsewhere as well: +match *"test" { + "test" => {} + _ => panic!(), +} +``` + +Implicit deref pattern syntax is not yet supported for string or byte string literals. + [smart pointers in the standard library]: https://doc.rust-lang.org/std/ops/trait.DerefPure.html#implementors -- cgit 1.4.1-3-g733a5