Ubuntu Manpage: cargo-fix — Automatically fix lint warnings reported by rustc

Provided by: cargo-1.78_1.78.0+dfsg1ubuntu1~bpo0-0ubuntu0.20.04_amd64

NAME

       cargo-fix — Automatically fix lint warnings reported by rustc

SYNOPSIS

       cargo fix [options]

DESCRIPTION

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>.

Edition migration
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.

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 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 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.

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 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.

-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 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
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.

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 <https://doc.rust-lang.org/cargo/reference/config.html>.

-q, --quiet
Do not print cargo log messages. May also be specified with the term.quiet config value
<https://doc.rust-lang.org/cargo/reference/config.html>.

--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 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 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
<https://doc.rust-lang.org/cargo/reference/config.html>.

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
<https://rust-lang.github.io/rustup/overrides.html> for more information about 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
provided 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 information.

-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), as well as the directories
searched for discovering .cargo/config.toml, for example. 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.

-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
<https://doc.rust-lang.org/cargo/reference/config.html>. Defaults to the number of logical CPUs. If
negative, it sets the maximum number of parallel jobs to the number of logical CPUs plus provided
value. 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, rather than aborting the build on the first
one that fails to build.

For example if the current package depends on dependencies fails and works, one of which fails to
build, cargo fix -j1 may or may not build the one that succeeds (depending on which one of the two
builds Cargo picked to run first), whereas 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.

       •  101: Cargo failed to complete.

EXAMPLES

        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