Ubuntu Manpage: cargo-rustc — Compile the current package, and pass extra options to the compiler

Provided by: cargo-1.76_1.76.0+dfsg0ubuntu1-0ubuntu0.24.04_amd64

NAME

       cargo-rustc — Compile the current package, and pass extra options to the compiler

SYNOPSIS

       cargo rustc [options] [-- args]

DESCRIPTION

       The specified target for the current package (or package specified by -p if provided) will be compiled
       along with all of its dependencies. The specified args will all be passed to the final compiler
       invocation, not any of the dependencies. Note that the compiler will still unconditionally receive
       arguments such as -L, --extern, and --crate-type, and the specified args will simply be added to the
       compiler invocation.

       See <https://doc.rust-lang.org/rustc/index.html> for documentation on rustc flags.

       This command requires that only one target is being compiled when additional arguments are provided. If
       more than one target is available for the current package the filters of --lib, --bin, etc, must be used
       to select which target is compiled.

       To pass flags to all compiler processes spawned by Cargo, use the RUSTFLAGS environment variable
       <https://doc.rust-lang.org/cargo/reference/environment-variables.html> or the build.rustflags config
       value <https://doc.rust-lang.org/cargo/reference/config.html>.

OPTIONS

Package Selection
By default, the package in the current working directory is selected. The -p flag can be used to choose a
different package in a workspace.

-p spec, --package spec
The package to build. See cargo-pkgid(1) for the SPEC format.

Target Selection
When no target selection options are given, cargo rustc will build all binary and library targets of the
selected package.

Binary targets are automatically built if there is an integration test or benchmark being selected to
build. This allows an integration test to execute the binary to exercise and test its behavior. The
CARGO_BIN_EXE_<name> environment variable
<https://doc.rust-lang.org/cargo/reference/environment-variables.html#environment-variables-cargo-sets-for-crates>
is set when the integration test is built so that it can use the env macro
<https://doc.rust-lang.org/std/macro.env.html> to locate the executable.

Passing target selection flags will build 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
Build the package’s library.

--bin name…
Build the specified binary. This flag may be specified multiple times and supports common Unix glob
patterns.

--bins
Build all binary targets.

--example name…
Build the specified example. This flag may be specified multiple times and supports common Unix glob
patterns.

--examples
Build all example targets.

--test name…
Build the specified integration test. This flag may be specified multiple times and supports common
Unix glob patterns.

--tests
Build 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…
Build the specified benchmark. This flag may be specified multiple times and supports common Unix
glob patterns.

--benches
Build 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
Build 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
Build 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
Build optimized artifacts with the release profile. See also the --profile option for choosing a
specific profile by name.

--profile name
Build with the given profile.

The rustc subcommand will treat the following named profiles with special behaviors:

• check — Builds in the same way as the cargo-check(1) command with the dev profile.

• test — Builds in the same way as the cargo-test(1) command, enabling building in test mode which
will enable tests and enable the test cfg option. See rustc tests
<https://doc.rust-lang.org/rustc/tests/index.html> for more detail.

• bench — Builds in the same was as the cargo-bench(1) command, similar to the test profile.

See the reference <https://doc.rust-lang.org/cargo/reference/profiles.html> for more details on
profiles.

--ignore-rust-version
Build 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.

--crate-type crate-type
Build for the given crate type. This flag accepts a comma-separated list of 1 or more crate types, of
which the allowed values are the same as crate-type field in the manifest for configuring a Cargo
target. See crate-type field
<https://doc.rust-lang.org/cargo/reference/cargo-targets.html#the-crate-type-field> for possible
values.

If the manifest contains a list, and --crate-type is provided, the command-line argument value will
override what is in the manifest.

This flag only works when building a lib or example library target.

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 rustc -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 rustc -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.

EXIT STATUS

       •  0: Cargo succeeded.

       •  101: Cargo failed to complete.

EXAMPLES

        1. Check if your package (not including dependencies) uses unsafe code:

               cargo rustc --lib -- -D unsafe-code

        2. Try an experimental flag on the nightly compiler, such as this which prints the size of every type:

               cargo rustc --lib -- -Z print-type-sizes

        3. Override crate-type field in Cargo.toml with command-line option:

               cargo rustc --lib --crate-type lib,cdylib