f542909d1c
Add `#[loop_match]` for improved DFA codegen tracking issue: https://github.com/rust-lang/rust/issues/132306 project goal: https://github.com/rust-lang/rust-project-goals/issues/258 This PR adds the `#[loop_match]` attribute, which aims to improve code generation for state machines. For some (very exciting) benchmarks, see https://github.com/rust-lang/rust-project-goals/issues/258#issuecomment-2732965199 Currently, a very restricted syntax pattern is accepted. We'd like to get feedback and merge this now before we go too far in a direction that others have concerns with. ## current state We accept code that looks like this ```rust #[loop_match] loop { state = 'blk: { match state { State::A => { #[const_continue] break 'blk State::B } State::B => { /* ... */ } /* ... */ } } } ``` - a loop should have the same semantics with and without `#[loop_match]`: normal `continue` and `break` continue to work - `#[const_continue]` is only allowed in loops annotated with `#[loop_match]` - the loop body needs to have this particular shape (a single assignment to the match scrutinee, with the body a labelled block containing just a match) ## future work - perform const evaluation on the `break` value - support more state/scrutinee types ## maybe future work - allow `continue 'label value` syntax, which `#[const_continue]` could then use. - allow the match to be on an arbitrary expression (e.g. `State::Initial`) - attempt to also optimize `break`/`continue` expressions that are not marked with `#[const_continue]` r? ``@traviscross`` |
||
|---|---|---|
| .github | ||
| compiler | ||
| library | ||
| LICENSES | ||
| src | ||
| tests | ||
| .clang-format | ||
| .editorconfig | ||
| .git-blame-ignore-revs | ||
| .gitattributes | ||
| .gitignore | ||
| .gitmodules | ||
| .ignore | ||
| .mailmap | ||
| bootstrap.example.toml | ||
| Cargo.lock | ||
| Cargo.toml | ||
| CODE_OF_CONDUCT.md | ||
| configure | ||
| CONTRIBUTING.md | ||
| COPYRIGHT | ||
| INSTALL.md | ||
| LICENSE-APACHE | ||
| license-metadata.json | ||
| LICENSE-MIT | ||
| README.md | ||
| RELEASES.md | ||
| REUSE.toml | ||
| 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 integrated 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 Rust language trademark policy.
Third-party logos may be subject to third-party copyrights and trademarks. See Licenses for details.