CARGO-RUSTC(1) User Commands CARGO-RUSTC(1)

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/reference/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:

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

+o 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.

+o 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.

--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:

+o 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.

+o 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:

+o auto (default): Automatically detect if color support is
available on the terminal.

+o always: Always display colors.

+o 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:

+o human (default): Display in a human-readable text format.
Conflicts with short and json.

+o short: Emit shorter, human-readable text messages. Conflicts
with human and json.

+o 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.

+o json-diagnostic-short: Ensure the rendered field of JSON
messages contains the "short" rendering from rustc. Cannot be
used with human or short.

+o 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.

+o 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.

--ignore-rust-version
Ignore rust-version specification in packages.

--locked
Asserts that the exact same dependencies and versions are used as
when the existing Cargo.lock file was originally generated. Cargo
will exit with an error when either of the following scenarios
arises:

+o The lock file is missing.

+o Cargo attempted to change the lock file due to a different
dependency resolution.

It may be used in environments where deterministic builds are
desired, such as in CI pipelines.

--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>.

--frozen
Equivalent to specifying both --locked and --offline.

--lockfile-path PATH
Changes the path of the lockfile from the default
(<workspace_root>/Cargo.lock) to PATH. PATH must end with
Cargo.lock (e.g. --lockfile-path
/tmp/temporary-lockfile/Cargo.lock). Note that providing
--lockfile-path will ignore existing lockfile at the default
path, and instead will either use the lockfile from PATH, or
write a new lockfile into the provided PATH if it doesn't exist.
This flag can be used to run most commands in read-only
directories, writing lockfile into the provided PATH.

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 #14421
<https://github.com/rust-lang/cargo/issues/14421>).

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

+o 0: Cargo succeeded.

+o 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

SEE ALSO

cargo(1), cargo-build(1), rustc(1)

CARGO-RUSTC(1)