check - The Cargo Book

# cargo check

## NAME

cargo-check - Check the current package

## SYNOPSIS

`cargo check [OPTIONS]`

## DESCRIPTION

Check a local package and all of its dependencies for errors. This will essentially compile the packages without performing the final step of code generation, which is faster than running `cargo build`. The compiler will save metadata files to disk so that future runs will reuse them if the source has not been modified.

## OPTIONS

### 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…​

  Check only the specified packages. See cargo-pkgid(1) for the SPEC format. This flag may be specified multiple times.

--workspace

  Check 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 check` will check all binary and library targets of the selected packages. Binaries are skipped if they have `required-features` that are missing.

Passing target selection flags will check only the specified targets.

--lib

  Check the package’s library.

--bin NAME…​

  Check the specified binary. This flag may be specified multiple times.

--bins

  Check all binary targets.

--example NAME…​

  Check the specified example. This flag may be specified multiple times.

--examples

  Check all example targets.

--test NAME…​

  Check the specified integration test. This flag may be specified multiple times.

--tests

  Check 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…​

  Check the specified benchmark. This flag may be specified multiple times.

--benches

  Check 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

  Check all targets. This is equivalent to specifying `--lib --bins --tests --benches --examples`.

### Feature Selection

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.

--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

  Check 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.

--release

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

--profile NAME

  Changes check behavior. Currently only `test` is supported, which will check with the `#[cfg(test)]` attribute enabled. This is useful to have it check 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.

  - `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

-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

1. Check the local package for errors:

       cargo check

2. Check all targets, including unit tests:

       cargo check --all-targets --profile=test

## SEE ALSO

cargo(1), cargo-build(1)