check - The Cargo Book

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 current working directory. In the root of a virtual workspace, all workspace members are selected (--all is implied). Otherwise, only the package in the current directory will be selected. The default packages may be overridden with the workspace.default-members key in the root Cargo.toml manifest.

-p SPEC…
--package SPEC…: Check only the specified packages. See cargo-pkgid(1) for the SPEC format. This flag may be specified multiple times.
--all: Check all members in the workspace.
--exclude SPEC…: Exclude the specified packages. Must be used in conjunction with the --all 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. Valid values:

human (default): Display in a human-readable text format.
json: Emit JSON messages to stdout.
short: Emit shorter, human-readable text messages.

Manifest Options

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

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

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

Check the local package for errors:
```
cargo check
```

Check all targets, including unit tests:

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

The Cargo Book

cargo check