cargo-fix(1)

NAME

cargo-fix - Automatically fix lint warnings reported by rustc

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! The cargo fix subcommand is also being developed for the Rust 2018 edition to provide code the ability to easily opt-in to the new edition without having to worry about any breakage.

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 prepare for the 2018 edition, you can do so by executing:

cargo fix --edition

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 --edition --features foo

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

cargo fix --edition --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

OPTIONS

Fix options

--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 latest edition. This will not update the edition in the Cargo.toml manifest, which must be updated manually.
--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 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.
--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.

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.

--lib: Fix the package's library.
--bin name...: Fix the specified binary. This flag may be specified multiple times.
--bins: Fix all binary targets.
--example name...: Fix the specified example. This flag may be specified multiple times.
--examples: Fix all example targets.
--test name...: Fix the specified integration test. This flag may be specified multiple times.
--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.
--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 allow you to control the enabled features for the "current" package. The "current" package is the package in the current directory, or the one specified in --manifest-path. If running in the root of a virtual workspace, then the default features are selected for all workspace members, or all features if --all-features is specified.

When no feature options are given, the default feature is activated for every selected package.

--features features: Space or comma separated list of features to activate. These features only apply to the current directory's package. Features of direct dependencies may be enabled with <dep-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 current directory's package.

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 may also be specified with the build.target config value.

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 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.

Output Options

--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. Defaults to target in the root of the workspace.

Display Options

-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.

-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.

--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.
short: Emit shorter, human-readable text messages.
json: Emit JSON messages to stdout. See the reference for more details.
json-diagnostic-short: Ensure the rendered field of JSON messages contains the "short" rendering from rustc.
json-diagnostic-rendered-ansi: Ensure the rendered field of JSON messages contains embedded ANSI color codes for respecting rustc's default color scheme.
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.

Manifest Options

--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.

Common Options

+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 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.

Miscellaneous Options

-j N
--jobs N: Number of parallel jobs to run. May also be specified with the build.jobs config value. Defaults to the number of CPUs.

PROFILES

Profiles may be used to configure compiler options such as optimization levels and debug settings. See the reference 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.

ENVIRONMENT

See the reference for details on environment variables that Cargo reads.

EXIT STATUS

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

EXAMPLES

Apply compiler suggestions to the local package:
```
cargo fix
```
Convert a 2015 edition to 2018:
```
cargo fix --edition
```
Apply suggested idioms for the current edition:
```
cargo fix --edition-idioms
```

The Cargo Book