7bb4f0889e
Stabilise inline_const # Stabilisation Report ## Summary This PR will stabilise `inline_const` feature in expression position. `inline_const_pat` is still unstable and will *not* be stabilised. The feature will allow code like this: ```rust foo(const { 1 + 1 }) ``` which is roughly desugared into ```rust struct Foo; impl Foo { const FOO: i32 = 1 + 1; } foo(Foo::FOO) ``` This feature is from https://github.com/rust-lang/rfcs/pull/2920 and is tracked in #76001 (the tracking issue should *not* be closed as it needs to track inline const in pattern position). The initial implementation is done in #77124. ## Difference from RFC There are two major differences (enhancements) as implemented from the RFC. First thing is that the RFC says that the type of an inline const block inferred from the content *within* it, but we currently can infer the type using the information from outside the const block as well. This is a frequently requested feature to the initial implementation (e.g. #89964). The inference is implemented in #89561 and is done by treating inline const similar to a closure and therefore share inference context with its parent body. This allows code like: ```rust let v: Vec<i32> = const { Vec::new() }; ``` Another enhancement that differs from the RFC is that we currently allow inline consts to reference generic parameters. This is implemented in #96557. This allows code like: ```rust fn create_none_array<T, const N: usize>() -> [Option<T>; N] { [const { None::<T> }; N] } ``` This enhancement also makes inline const usable as static asserts: ```rust fn require_zst<T>() { const { assert!(std::mem::size_of::<T>() == 0) } } ``` ## Documentation Reference: rust-lang/reference#1295 ## Unresolved issues We still have a few issues that are not resolved, but I don't think it necessarily has to block stabilisation: * expr fragment specifier issue: #86730 * ~~`const {}` behaves similar to `async {}` but not to `{}` and `unsafe {}` (they are treated as `ExpressionWithoutBlock` rather than `ExpressionWithBlock`): https://rust-lang.zulipchat.com/#narrow/stream/213817-t-lang/topic/const.20blocks.20differ.20from.20normal.20and.20from.20unsafe.20blocks/near/290229453~~ ## Tests There are a few tests in https://github.com/rust-lang/rust/tree/master/src/test/ui/inline-const |
||
---|---|---|
.github | ||
.reuse | ||
compiler | ||
library | ||
LICENSES | ||
src | ||
tests | ||
.editorconfig | ||
.git-blame-ignore-revs | ||
.gitattributes | ||
.gitignore | ||
.gitmodules | ||
.mailmap | ||
Cargo.lock | ||
Cargo.toml | ||
CODE_OF_CONDUCT.md | ||
config.example.toml | ||
configure | ||
CONTRIBUTING.md | ||
COPYRIGHT | ||
INSTALL.md | ||
LICENSE-APACHE | ||
LICENSE-MIT | ||
README.md | ||
RELEASES.md | ||
rust-bors.toml | ||
rustfmt.toml | ||
triagebot.toml | ||
x | ||
x.ps1 | ||
x.py |
This is the main source code repository for Rust. It contains the compiler, standard library, and documentation.
Why Rust?
-
Performance: Fast and memory-efficient, suitable for critical services, embedded devices, and easily integrate with other languages.
-
Reliability: Our rich type system and ownership model ensure memory and thread safety, reducing bugs at compile-time.
-
Productivity: Comprehensive documentation, a compiler committed to providing great diagnostics, and advanced tooling including package manager and build tool (Cargo), auto-formatter (rustfmt), linter (Clippy) and editor support (rust-analyzer).
Quick Start
Read "Installation" from The Book.
Installing from Source
If you really want to install from source (though this is not recommended), see INSTALL.md.
Getting Help
See https://www.rust-lang.org/community for a list of chat platforms and forums.
Contributing
See CONTRIBUTING.md.
License
Rust is primarily distributed under the terms of both the MIT license and the Apache License (Version 2.0), with portions covered by various BSD-like licenses.
See LICENSE-APACHE, LICENSE-MIT, and COPYRIGHT for details.
Trademark
The Rust Foundation owns and protects the Rust and Cargo trademarks and logos (the "Rust Trademarks").
If you want to use these names or brands, please read the media guide.
Third-party logos may be subject to third-party copyrights and trademarks. See Licenses for details.