CARGO-CHECK(1)

📦 version 1.78.0, in ubuntu jammy, ubuntu noble

👑 cargo-check(1) — General Commands Manual 👑

okay bestie, this is the cargo-check(1) page from the General Commands Manual, and it's literally about checking your current package without doing the whole final codegen thing. slay 💅

✨ NAME ✨

cargo-check — check the current package 🎀

📜 SYNOPSIS 📜

cargo check [options]

💖 DESCRIPTION 💖

okay so cargo check checks a local package and all of its dependencies for errors. It's basically compiling the packages without doing the final step of code generation, which is faster than running cargo build. The compiler will save metadata files to disk so future runs reuse them if the source hasn't been modified. Heads up though: some diagnostics and errors are only emitted during code generation, so they inherently won't be reported with cargo check. not me finding out the hard way 😭

⚙️ 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 workspace's 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 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. quote it, bestie, or the shell will eat it 💅
  • --workspace — Check all members in the workspace. the whole squad 👑
  • --all — Deprecated alias for --workspace. it's giving legacy 😬
  • --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. same quoting rules, no cap

🎯 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. so if a binary needs a feature you didn't turn on, it gets left on read 💀

Passing target selection flags will check 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. say it with me: quote your globs 🗣️

  • --lib — Check the package's library. the lib 📚
  • --bin name… — Check the specified binary. This flag may be specified multiple times and supports common Unix glob patterns. binaries go brrr
  • --bins — Check all binary targets. all the bins ✨
  • --example name… — Check the specified example. This flag may be specified multiple times and supports common Unix glob patterns. examples are cute 🎀
  • --examples — Check all example targets. every single example 🌸
  • --test name… — Check the specified integration test. This flag may be specified multiple times and supports common Unix glob patterns. integration test vibes
  • --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. yes, the lib can get built twice, it's not a glitch, it's just Cargo being thorough 😭
  • --bench name… — Check the specified benchmark. This flag may be specified multiple times and supports common Unix glob patterns. benchmark time ⏱️
  • --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. again with the double build, it's a whole thing 🫠
  • --all-targets — Check all targets. This is equivalent to specifying --lib --bins --tests --benches --examples. the everything bagel 🥯

🌈 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. defaults are doing their default thing

See the features documentation at 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. stack 'em up ✨
  • --all-features — Activate all available features of all selected packages. no feature left behind 💖
  • --no-default-features — Do not activate the default feature of the selected packages. turning off the defaults, bold move 👀

🔨 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 flag may be specified multiple times.

This may also be specified with the build.target config value at 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 documentation at https://doc.rust-lang.org/cargo/guide/build-cache.html for more details. different mode, different directory, different vibe

  • -r, --release — Check optimized artifacts with the release profile. See also the --profile option for choosing a specific profile by name. release mode, she's fancy 👑
  • --profile name — Check 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 at https://doc.rust-lang.org/rustc/tests/index.html for more detail.

See the reference at https://doc.rust-lang.org/cargo/reference/profiles.html for more details on profiles. profiles are the moment

  • --ignore-rust-version — Check the target even if the selected Rust compiler is older than the required Rust version as configured in the project's rust-version field. ignoring the rust-version, living dangerously 😳
  • --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. pretty report for the girlies 📊
    • json (unstable, requires -Zunstable-options): Emit machine-readable JSON information about timing information. for the machines 🤖

📁 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 at https://doc.rust-lang.org/cargo/reference/config.html. Defaults to target in the root of the workspace. your build stuff goes here 🗂️

🖥️ 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 at https://doc.rust-lang.org/cargo/reference/config.html. tell me everything 🗣️
  • -q, --quiet — Do not print cargo log messages. May also be specified with the term.quiet config value at https://doc.rust-lang.org/cargo/reference/config.html. shhh, no logs 🤫
  • --color when — Control when colored output is used. Valid values:
    • auto (default): Automatically detect if color support is available on the terminal. smart colors
    • always: Always display colors. rainbow mode activated
    • never: Never display colors. monochrome moment

May also be specified with the term.color config value at 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. for the humans 💖
    • short: Emit shorter, human-readable text messages. Conflicts with human and json. short and sweet
    • json: Emit JSON messages to stdout. See the reference at https://doc.rust-lang.org/cargo/reference/external-tools.html#json-messages for more details. Conflicts with human and short. JSON girlies rise
    • json-diagnostic-short: Ensure the rendered field of JSON messages contains the "short" rendering from rustc. Cannot be used with human or short. short but in JSON
    • 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. ANSI colors in your JSON, iconic
    • 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. Cargo takes the wheel on rendering

📜 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. where's the manifest? Cargo will find it 🔍
  • --frozen, --locked — either of these is you telling Cargo "bestie, the Cargo.lock file is up-to-date, I promise". If the lock file is missing, or it needs to be updated, Cargo exits with an error, no discussion, no negotiation 💀 The --frozen flag goes one step further: it also stops Cargo from even attempting to access the network to determine if it's out-of-date.

So when do you use these? Whenever you want to assert that Cargo.lock is up-to-date (like in a CI build, where "it worked on my machine" is not a lockfile strategy) or whenever you want zero network access. Periodt.

  • --offline — Cargo is not touching the network for any reason. Iconic hermit behaviour 🧚

Without this flag, if Cargo needs the network and the network isn't there, it just stops with an error. With this flag, Cargo will attempt to proceed without the network if possible.

⚠️ But beware bestie — this can give you different dependency resolution than online mode. Cargo restricts itself to crates that are downloaded locally, even if there might be a newer version as indicated in the local copy of the index. It's giving "I only know what I know".

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 gets interpreted as a rustup toolchain name (like +stable or +nightly). See the rustup documentation (https://rust-lang.github.io/rustup/overrides.html) for more info on how toolchain overrides work. Lowkey magic ✨
  • --config KEY=VALUE or PATH — overrides a Cargo configuration value. The argument should be in TOML syntax of KEY=VALUE, or handed over as a path to an extra configuration file. You can specify this flag multiple times, she's flexible 💅 See the command-line overrides section (https://doc.rust-lang.org/cargo/reference/config.html#command-line-overrides) for more info.
  • -C PATH — changes the current working directory before executing any specified operations. This affects stuff like where cargo looks by default for the project manifest (Cargo.toml), and the directories searched for discovering .cargo/config.toml, for example. Heads up: this option must appear before the command name, like 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. The classic 🫶
  • -Z flag — unstable (nightly-only) flags to Cargo. Run cargo -Z help for the details.

🌈 Miscellaneous Options 🌈

If it's negative, it sets the maximum number of parallel jobs to the number of logical CPUs plus the provided value. If a string default is provided, it sets the value back to defaults.

🚫 Should not be 0. Like, genuinely, don't.
  • --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. She's resilient, she's persistent, she's not letting one flop ruin the whole rollout 💖

For example: if the current package depends on dependencies fails and works, one of which fails to build, cargo check -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 check -j1 --keep-going would definitely run both builds, even if the one run first fails.

  • --future-incompat-report — displays a future-incompat report for any future-incompatible warnings produced during execution of this command.

See cargo-report(1).

🌍 ENVIRONMENT 🌍

See the reference (https://doc.rust-lang.org/cargo/reference/environment-variables.html) for details on environment variables that Cargo reads. She reads them, she respects them, she's a good listener 🎀

💀 EXIT STATUS 💀

  • 0: Cargo succeeded. Slay. 👑
  • 101: Cargo failed to complete. Not slay. 😭

🦋 EXAMPLES 🦋

  1. Check the local package for errors:
cargo check
  1. Check all targets, including unit tests:
cargo check --all-targets --profile=test

🌸 SEE ALSO 🌸

cargo(1), cargo-build(1)

And that's a wrap on the whole cargo-check(1) situation bestie ✨ this was the cargo-check(1) man page, from the Cargo docs, stamped with whatever version and date your distro happened to ship it with. Go check some code, you're doing amazing 🫶💜

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