CARGO-FIX(1)

📦 version 1.76.0, in ubuntu jammy, ubuntu noble

🎀 cargo-fix(1) 🎀 — General Commands Manual

🌸 NAME 🌸

cargo-fix — automatically fix lint warnings reported by rustc 💖

📜 SYNOPSIS 📜

cargo fix [options]

💖 DESCRIPTION 💖

okay so bestie, this Cargo subcommand literally takes rustc’s suggestions from diagnostics like warnings and applies them to your source code. The whole goal? Automating the tasks that rustc itself already knows how to tell you to fix. It's giving helpful compiler energy ✨

Running cargo fix will, under the hood, execute cargo-check(1). Any warnings that apply to your crate get automatically fixed (if possible), and all the remaining warnings show up when the check process is done. So if you wanna apply all fixes to the current package, you can run:

cargo fix

which behaves the same as cargo check --all-targets.

cargo fix is only capable of fixing code that is normally compiled with cargo check. If code is conditionally enabled with optional features, you’ll need to enable those features for that code to be analyzed:

cargo fix --features foo

Similarly, other cfg expressions like platform-specific code will need to pass --target to fix code for the given target.

cargo fix --target x86_64-pc-windows-gnu

If you run into any problems with cargo fix, or you have questions or feature requests, please don’t hesitate to file an issue at https://github.com/rust-lang/cargo. No gatekeeping, bestie 🫶

🦋 Edition migration 🦋

The cargo fix subcommand can also migrate a package from one edition https://doc.rust-lang.org/edition-guide/editions/transitioning-an-existing-project-to-a-new-edition.html to the next. The general procedure is:

  1. Run cargo fix --edition. Consider also using the --all-features flag if your project has multiple features. You may also want to run cargo fix --edition multiple times with different --target flags if your project has platform-specific code gated by cfg attributes.
  2. Modify Cargo.toml to set the edition field https://doc.rust-lang.org/cargo/reference/manifest.html#the-edition-field to the new edition.
  3. Run your project tests to verify that everything still works. If new warnings are issued, you may want to consider running cargo fix again (without the --edition flag) to apply any suggestions given by the compiler.

And hopefully that’s it! Just keep in mind the caveats mentioned above: cargo fix cannot update code for inactive features or cfg expressions. Also, in some rare cases the compiler is unable to automatically migrate all code to the new edition, and this may require manual changes after building with the new edition. iykyk ⚠️

✨ OPTIONS ✨

💅 Fix options 💅

  • --broken-code — fixes code even if it already has compiler errors 💀. This is useful if cargo fix fails to apply the changes. It will apply the changes and leave the broken code in the working directory for you to inspect and manually fix.
  • --edition — apply changes that will update the code to the next edition. This will not update the edition in the Cargo.toml manifest, which must be updated manually after cargo fix --edition has finished.
  • --edition-idioms — apply suggestions that will update code to the preferred style for the current edition.
  • --allow-no-vcs — fix code even if a VCS was not detected.
  • --allow-dirty — fix code even if the working directory has changes.
  • --allow-staged — fix code even if the working directory has staged changes.

📦 Package Selection 📦

By default, when no package selection options are given, the packages selected depend on the selected manifest file (based on the current working directory if --manifest-path is not given). If the manifest is the root of a workspace, then the workspace’s default members are selected; otherwise only the package defined by the manifest will be selected.

The default members of a workspace can be set explicitly with the workspace.default-members key in the root manifest. If this is not set, a virtual workspace will include all workspace members (equivalent to passing --workspace), and a non-virtual workspace will include only the root crate itself.

  • -p *spec*…, --package *spec*… — fix only the specified packages. See cargo-pkgid(1) for the SPEC format. This flag may be specified multiple times and supports common Unix glob patterns like *, ? and []. However, to avoid your shell accidentally expanding glob patterns before Cargo handles them, you must use single quotes or double quotes around each pattern.
  • --workspace — fix all members in the workspace.
  • --all — deprecated alias for --workspace. it's giving legacy vibes 👑
  • --exclude *SPEC*… — exclude the specified packages. Must be used in conjunction with the --workspace flag. This flag may be specified multiple times and supports common Unix glob patterns like *, ? and []. However, to avoid your shell accidentally expanding glob patterns before Cargo handles them, you must use single quotes or double quotes around each pattern.

🎯 Target Selection 🎯

When no target selection options are given, cargo fix will fix all targets (--all-targets implied). Binaries are skipped if they have required-features that are missing.

Passing target selection flags will fix only the specified targets.

Note that --bin, --example, --test and --bench flags also support common Unix glob patterns like *, ? and []. However, to avoid your shell accidentally expanding glob patterns before Cargo handles them, you must use single quotes or double quotes around each glob pattern.

  • --lib — fix the package’s library.
  • --bin *name*… — fix the specified binary. This flag may be specified multiple times and supports common Unix glob patterns.
  • --bins — fix all binary targets.
  • --example *name*… — fix the specified example. This flag may be specified multiple times and supports common Unix glob patterns.
  • --examples — fix all example targets.
  • --test *name*… — fix the specified integration test. This flag may be specified multiple times and supports common Unix glob patterns.
  • --tests — fix all targets in test mode that have the test = true manifest flag set. By default this includes the library and binaries built as unittests, and integration tests. Be aware that this will also build any required dependencies, so the lib target may be built twice (once as a unittest, and once as a dependency for binaries, integration tests, etc.). Targets may be enabled or disabled by setting the test flag in the manifest settings for the target.
  • --bench *name*… — fix the specified benchmark. This flag may be specified multiple times and supports common Unix glob patterns.
  • --benches — fix all targets in benchmark mode that have the bench = true manifest flag set. By default this includes the library and binaries built as benchmarks, and bench targets. Be aware that this will also build any required dependencies, so the lib target may be built twice (once as a benchmark, and once as a dependency for binaries, benchmarks, etc.). Targets may be enabled or disabled by setting the bench flag in the manifest settings for the target.
  • --all-targets — fix all targets. This is equivalent to specifying --lib --bins --tests --benches --examples.

🌈 Feature Selection 🌈

The feature flags let you control which features are enabled. When no feature options are given, the default feature is activated for every selected package.

See the features documentation https://doc.rust-lang.org/cargo/reference/features.html#command-line-feature-options for more details.

  • -F features, --features features — space or comma separated list of features to activate. Features of workspace members may be enabled with package-name/feature-name syntax. This flag may be specified multiple times, which enables all specified features.
  • --all-features — activate all available features of all selected packages.
  • --no-default-features — do not activate the default feature of the selected packages.

🔧 Compilation Options 🔧

  • --target triple — fix for the given architecture. The default is the host architecture. The general format of the triple is <arch><sub>-<vendor>-<sys>-<abi>. Run rustc --print target-list for a list of supported targets. This flag may be specified multiple times.

This may also be specified with the build.target config value https://doc.rust-lang.org/cargo/reference/config.html.

Note that specifying this flag makes Cargo run in a different mode where the target artifacts are placed in a separate directory. See the build cache https://doc.rust-lang.org/cargo/guide/build-cache.html documentation for more details.

  • -r, --release — fix optimized artifacts with the release profile. See also the --profile option for choosing a specific profile by name.
  • --profile name — fix with the given profile.

As a special case, specifying the test profile will also enable checking in test mode which will enable checking tests and enable the test cfg option. See rustc tests https://doc.rust-lang.org/rustc/tests/index.html for more detail.

See the reference https://doc.rust-lang.org/cargo/reference/profiles.html for more details on profiles.

  • --ignore-rust-version — fix the target even if the selected Rust compiler is older than the required Rust version as configured in the project’s rust-version field.
  • --timings=fmts — output information about how long each compilation takes, and track concurrency information over time. Accepts an optional comma-separated list of output formats; --timings without an argument will default to --timings=html. Specifying an output format (rather than the default) is unstable and requires -Zunstable-options. Valid output formats:
    • html (unstable, requires -Zunstable-options): write a human-readable file cargo-timing.html to the target/cargo-timings directory with a report of the compilation. Also write a report to the same directory with a timestamp in the filename if you want to look at older runs. HTML output is suitable for human consumption only, and does not provide machine-readable timing data.
    • json (unstable, requires -Zunstable-options): emit machine-readable JSON information about timing information.

✨ Output Options ✨

  • --target-dir directory — where all the generated artifacts and intermediate files go. You can also set this with the CARGO_TARGET_DIR environment variable, or the build.target-dir config value (https://doc.rust-lang.org/cargo/reference/config.html). If you don't say anything, it defaults to target in the root of the workspace. 💅

🎀 Display Options 🎀

  • -v, --verbose — verbose output, bestie. Say it twice and you get "very verbose" output, which throws in extra stuff like dependency warnings and build script output. Also settable via the term.verbose config value (https://doc.rust-lang.org/cargo/reference/config.html).
  • -q, --quiet — no cargo log messages at all, silence, peace, the vibe is calm 🧘. Also settable via the term.quiet config value (https://doc.rust-lang.org/cargo/reference/config.html).
  • --color when — controls when colored output happens. Valid values are:
    • auto (the default): it automatically detects whether your terminal supports color. ✨
    • always: colors, always, no matter what. 🌈
    • never: no colors, ever. 💀

Also settable via the term.color config value (https://doc.rust-lang.org/cargo/reference/config.html).

  • --message-format fmt — the output format for diagnostic messages. You can pass this multiple times, and it's made of comma-separated values. Valid values:
    • human (the default): displays in a human-readable text format. Conflicts with short and json.
    • short: emits shorter, human-readable text messages. Conflicts with human and json.
    • json: emits JSON messages to stdout. Check the reference (https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages) for the details. Conflicts with human and short.
    • json-diagnostic-short: makes sure the rendered field of JSON messages contains the "short" rendering from rustc. Cannot be used with human or short.
    • json-diagnostic-rendered-ansi: makes sure the rendered field of JSON messages contains embedded ANSI color codes so it respects rustc's default color scheme. Cannot be used with human or short.
    • json-render-diagnostics: tells Cargo not to include rustc diagnostics in the JSON messages it prints, and instead have Cargo itself render the JSON diagnostics coming from rustc. Cargo's own JSON diagnostics — and the others coming from rustc — are still emitted. Cannot be used with human or short.

🦋 Manifest Options 🦋

  • --manifest-path path — the path to the Cargo.toml file. By default, Cargo goes looking for Cargo.toml in the current directory or any parent directory. 🔍
  • --frozen, --locked — either of these flags demands that the Cargo.lock file is up-to-date. If the lock file is missing, or it needs updating, Cargo exits with an error. The --frozen flag also stops Cargo from trying to reach the network to figure out if it's out-of-date.

These are for environments where you want to assert that Cargo.lock is up-to-date (like a CI build), or where you want to avoid network access entirely.

  • --offline — stops Cargo from accessing the network for literally any reason. Without this flag, Cargo stops with an error if it needs the network and the network isn't there. With this flag, Cargo will try to keep going without the network if it can.
Heads up bestie ⚠️ this can result in different dependency resolution than online mode. Cargo restricts itself to crates that are downloaded locally, even if there might be a newer version indicated in the local copy of the index. Peep cargo-fetch(1) to download dependencies before you go offline. 🫶

Also settable via the net.offline config value (https://doc.rust-lang.org/cargo/reference/config.html).

💜 Common Options 💜

  • +toolchain — if Cargo was installed with rustup, and the first argument to cargo begins with +, it gets interpreted as a rustup toolchain name (like +stable or +nightly). See the rustup documentation (https://rust-lang.github.io/rustup/overrides.html) for more on how toolchain overrides work. 👑
  • --config KEY=VALUE or PATH — overrides a Cargo configuration value. The argument should be in TOML syntax of KEY=VALUE, or given as a path to an extra configuration file. This flag may be specified multiple times. See the command-line overrides section (https://doc.rust-lang.org/cargo/reference/config.html#command-line-overrides) for more info.
  • -C PATH — changes the current working directory before executing any specified operations. This affects things like where cargo looks by default for the project manifest (Cargo.toml), and also the directories searched for discovering .cargo/config.toml. This option must appear before the command name, for example cargo -C path/to/my-project build.
This option is only available on the nightly channel (https://doc.rust-lang.org/book/appendix-07-nightly-rust.html) and requires the -Z unstable-options flag to enable (see #10098 https://github.com/rust-lang/cargo/issues/10098). 🌙
  • -h, --help — prints help information. the classic. 🙈
  • -Z flag — unstable (nightly-only) flags to Cargo. Run cargo -Z help for details.

🌸 Miscellaneous Options 🌸

  • -j N, --jobs N — number of parallel jobs to run. Also settable via the build.jobs config value (https://doc.rust-lang.org/cargo/reference/config.html). Defaults to the number of logical CPUs. If it's negative, it sets the maximum number of parallel jobs to the number of logical CPUs plus the value you provided. If a string default is provided, it sets the value back to defaults. Should not be 0. 🚫
  • --keep-going — build as many crates in the dependency graph as possible, instead of aborting the build the second one of them fails.

For example, if the current package depends on dependencies fails and works, and one of them fails to build, cargo fix -j1 may or may not build the one that succeeds (it depends on which of the two builds Cargo picked to run first). Meanwhile cargo fix -j1 --keep-going would definitely run both builds, even if the one run first fails. 💪

🌈 ENVIRONMENT 🌈

See the reference (https://doc.rust-lang.org/cargo/reference/environment-variables.html) for details on environment variables that Cargo reads. 👀

⭐ EXIT STATUS ⭐

  • 0: Cargo succeeded. slay 🎉
  • 101: Cargo failed to complete. 😭

✨ EXAMPLES ✨

  1. Apply compiler suggestions to the local package:
cargo fix
  1. Update a package to prepare it for the next edition:
cargo fix --edition
  1. Apply suggested idioms for the current edition:
cargo fix --edition-idioms

🫶 SEE ALSO 🫶

cargo(1), cargo-check(1)

and that's a wrap on the CARGO-FIX(1) page bestie 💖 this one comes from the Cargo source/version that ships with this manual, dated like any good classic — go forth and let the compiler fix ur code for u, no cap 👑

📦 where this page comes from