rustfmt

rustfmt is a code formatter for Rust. It automatically formats Rust source files to conform to the standard Rust style, ensuring consistent indentation, line breaks, and spacing. By applying the same formatting rules across projects, it reduces diffs and code-review friction. rustfmt is an official part of the Rust project and is distributed with the Rust toolchain.

Usage: It is distributed as a tool component and can be installed via rustup; after installation you format code with cargo fmt for a crate or workspace, or with rustfmt on individual files. The common workflow is to run cargo fmt before committing or in continuous integration. To check formatting without changing files, use cargo fmt -- --check (or rustfmt --check for a single file).

Configuration: The formatter can be customized using a rustfmt.toml configuration file placed in the project root. Options may include max_width to control line length, tab_spaces to influence tab width, and use_small_heuristics to tune formatting decisions. The configuration can be overridden on the command line as well.

Integration and ecosystem: rustfmt is widely integrated into Rust tooling and editors, such as IDEs and editor plugins, and is commonly run as part of code style checks in continuous integration. It formats code consistently across crates, regardless of author or project conventions.

Development: rustfmt is maintained by the Rust community as an open-source project. It is designed to be deterministic and reproducible, given the same input and configuration, and continues to evolve with the Rust language and its formatting guidelines.