CARGO-FIX(1) General Commands Manual CARGO-FIX(1)

cargo-fix - Automatically fix lint warnings reported by rustc

cargo fix [options]

This Cargo subcommand will automatically take rustc's suggestions from diagnostics like warnings and apply them to your source code. This is intended to help automate tasks that rustc itself already knows how to tell you to fix!

Executing cargo fix will under the hood execute cargo-check(1). Any warnings applicable to your crate will be automatically fixed (if possible) and all remaining warnings will be displayed when the check process is finished. For example if you'd like to 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 will 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 encounter any problems with cargo fix or otherwise have any questions or feature requests please don't hesitate to file an issue at https://github.com/rust-lang/cargo.

The cargo fix subcommand can also be used to 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 of the caveats mentioned above that 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.

--broken-code
Fix 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.

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 workspaces 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.

--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.

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.

The feature flags allow you to 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.

--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.

--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 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.

--release

Fix optimized artifacts with the release profile. See the PROFILES section for details on how this affects profile selection.

--profile name

Changes fix behavior. Currently only test is supported, which will fix with the #[cfg(test)] attribute enabled. This is useful to have it fix unit tests which are usually excluded via the cfg attribute. This does not change the actual profile used.

--target-dir directory
Directory for all generated artifacts and intermediate files. May also be specified with the CARGO_TARGET_DIR environment variable, or the build.target-dir config value https://doc.rust-lang.org/cargo/reference/config.html. Defaults to target in the root of the workspace.

-v, --verbose
Use verbose output. May be specified twice for "very verbose" output which includes extra output such as dependency warnings and build script output. May also be specified with the term.verbose config value https://doc.rust-lang.org/cargo/reference/config.html.

-q, --quiet

No output printed to stdout.

--color when

Control when colored output is used. Valid values:
auto (default): Automatically detect if color support is available on the terminal.
always: Always display colors.
never: Never display colors.

May also be specified with the term.color config value https://doc.rust-lang.org/cargo/reference/config.html.

--message-format fmt

The output format for diagnostic messages. Can be specified multiple times and consists of comma-separated values. Valid values:
human (default): Display in a human-readable text format. Conflicts with short and json.
short: Emit shorter, human-readable text messages. Conflicts with human and json.
json: Emit JSON messages to stdout. See the reference https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages for more details. Conflicts with human and short.
json-diagnostic-short: Ensure the rendered field of JSON messages contains the "short" rendering from rustc. Cannot be used with human or short.
json-diagnostic-rendered-ansi: Ensure the rendered field of JSON messages contains embedded ANSI color codes for respecting rustc's default color scheme. Cannot be used with human or short.
json-render-diagnostics: Instruct Cargo to not include rustc diagnostics in in JSON messages printed, but instead Cargo itself should render the JSON diagnostics coming from rustc. Cargo's own JSON diagnostics and others coming from rustc are still emitted. Cannot be used with human or short.

--manifest-path path
Path to the Cargo.toml file. By default, Cargo searches for the Cargo.toml file in the current directory or any parent directory.

--frozen, --locked

Either of these flags requires that the Cargo.lock file is up-to-date. If the lock file is missing, or it needs to be updated, Cargo will exit with an error. The --frozen flag also prevents Cargo from attempting to access the network to determine if it is out-of-date.

These may be used in environments where you want to assert that the Cargo.lock file is up-to-date (such as a CI build) or want to avoid network access.

--offline

Prevents Cargo from accessing the network for any reason. Without this flag, Cargo will stop with an error if it needs to access the network and the network is not available. With this flag, Cargo will attempt to proceed without the network if possible.

Beware that this may result in different dependency resolution than online mode. Cargo will restrict itself to crates that are downloaded locally, even if there might be a newer version as indicated in the local copy of the index. See the cargo-fetch(1) command to download dependencies before going offline.

May also be specified with the net.offline config value https://doc.rust-lang.org/cargo/reference/config.html.

+toolchain
If Cargo has been installed with rustup, and the first argument to cargo begins with +, it will be interpreted as a rustup toolchain name (such as +stable or +nightly). See the rustup documentation https://rust-lang.github.io/rustup/overrides.html for more information about how toolchain overrides work.

-h, --help

Prints help information.

-Z flag

Unstable (nightly-only) flags to Cargo. Run cargo -Z help for details.

-j N, --jobs N
Number of parallel jobs to run. May also be specified with the build.jobs config value https://doc.rust-lang.org/cargo/reference/config.html. Defaults to the number of CPUs.

Profiles may be used to configure compiler options such as optimization levels and debug settings. See the reference https://doc.rust-lang.org/cargo/reference/profiles.html for more details.

Profile selection depends on the target and crate being built. By default the dev or test profiles are used. If the --release flag is given, then the release or bench profiles are used.

Target Default Profile --release Profile
lib, bin, example dev release
test, bench, or any target in "test" or "bench" mode test bench

Dependencies use the dev/release profiles.

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

0: Cargo succeeded.
101: Cargo failed to complete.

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

cargo(1), cargo-check(1)