cargo_build_script.bzl

cargo_build_script

load("@rules_rust//cargo:cargo_build_script.bzl", "cargo_build_script")

cargo_build_script(*, name, edition, crate_name, crate_root, srcs, crate_features, version, deps,
                   link_deps, proc_macro_deps, build_script_env, build_script_env_files,
                   emit_warnings, use_cc_toolchain, use_default_shell_env, data, compile_data, tools,
                   links, rundir, rustc_env, rustc_env_files, rustc_flags, visibility, tags, aliases,
                   pkg_name, **kwargs)

Compile and execute a rust build script to generate build attributes

This rules take the same arguments as rust_binary.

Example:

Suppose you have a crate with a cargo build script build.rs:

[workspace]/
    hello_lib/
        BUILD
        build.rs
        src/
            lib.rs

Then you want to use the build script in the following:

hello_lib/BUILD:

package(default_visibility = ["//visibility:public"])

load("@rules_rust//rust:defs.bzl", "rust_binary", "rust_library")
load("@rules_rust//cargo:defs.bzl", "cargo_build_script")

# This will run the build script from the root of the workspace, and
# collect the outputs.
cargo_build_script(
    name = "build_script",
    srcs = ["build.rs"],
    # Optional environment variables passed during build.rs compilation
    rustc_env = {
       "CARGO_PKG_VERSION": "0.1.2",
    },
    # Optional environment variables passed during build.rs execution.
    # Note that as the build script's working directory is not execroot,
    # execpath/location will return an absolute path, instead of a relative
    # one.
    build_script_env = {
        "SOME_TOOL_OR_FILE": "$(execpath @tool//:binary)"
    },
    # Optional data/tool dependencies
    data = ["@tool//:binary"],
)

rust_library(
    name = "hello_lib",
    srcs = [
        "src/lib.rs",
    ],
    deps = [":build_script"],
)

The hello_lib target will be build with the flags and the environment variables declared by the build script in addition to the file generated by it.

PARAMETERS

Name	Description	Default Value
name	The name for the underlying rule. This should be the name of the package being compiled, optionally with a suffix of `_bs`. Otherwise, you can set the package name via `pkg_name`.	none
edition	The rust edition to use for the internal binary crate.	`None`
crate_name	Crate name to use for build script.	`None`
crate_root	The file that will be passed to rustc to be used for building this crate.	`None`
srcs	Source files of the crate to build. Passing source files here can be used to trigger rebuilds when changes are made.	`[]`
crate_features	A list of features to enable for the build script.	`[]`
version	The semantic version (semver) of the crate.	`None`
deps	The build-dependencies of the crate.	`[]`
link_deps	The subset of the (normal) dependencies of the crate that have the links attribute and therefore provide environment variables to this build script.	`[]`
proc_macro_deps	List of rust_proc_macro targets used to build the script.	`[]`
build_script_env	Environment variables for build scripts.	`{}`
build_script_env_files	Files containing additional environment variables to set when running the build script.	`[]`
emit_warnings	Whether to forward `cargo::warning=` lines from the build script to stderr. Honored only when `@rules_rust//cargo/settings:emit_build_script_warnings` is `auto` (the default); set the flag to `on` or `off` to override every target.	`True`
use_cc_toolchain	Whether or not to pull in the resolved `cc_toolchain` when running the build script. When enabled, the resolved `cc_toolchain`'s `all_files` are added to the action inputs and the `CC`, `CXX`, `AR`, `CFLAGS`, `CXXFLAGS`, `LDFLAGS`, and `INCLUDE` environment variables are populated from that toolchain (matching Cargo's normal behavior). Disabling this can significantly shrink build script action input trees (particularly with hermetic sysroots) but breaks any build script that needs to compile C/C++ code. If unset the global setting `@rules_rust//cargo/settings:use_cc_toolchain` will be used to determine this value.	`None`
use_default_shell_env	Whether or not to include the default shell environment for the build script action. If unset the global setting `@rules_rust//cargo/settings:use_default_shell_env` will be used to determine this value.	`None`
data	Files needed by the build script.	`[]`
compile_data	Files needed for the compilation of the build script.	`[]`
tools	Tools (executables) needed by the build script.	`[]`
links	Name of the native library this crate links against.	`None`
rundir	A directory to `cd` to before the cargo_build_script is run. This should be a path relative to the exec root. The default behaviour (and the behaviour if rundir is set to the empty string) is to change to the relative path corresponding to the cargo manifest directory, which replicates the normal behaviour of cargo so it is easy to write compatible build scripts. If set to `.`, the cargo build script will run in the exec root.	`None`
rustc_env	Environment variables to set in rustc when compiling the build script.	`{}`
rustc_env_files	Files containing additional environment variables to set for rustc when building the build script.	`[]`
rustc_flags	List of compiler flags passed to `rustc`.	`[]`
visibility	Visibility to apply to the generated build script output.	`None`
tags	(list of str, optional): Tags to apply to the generated build script output.	`None`
aliases	Remap crates to a new name or moniker for linkage to this target. These are other `rust_library` targets and will be presented as the new name given.	`None`
pkg_name	Override the package name used for the build script. This is useful if the build target name gets too long otherwise.	`None`
kwargs	Forwards to the underlying `rust_binary` rule. An exception is the `compatible_with` attribute, which shouldn't be forwarded to the `rust_binary`, as the `rust_binary` is only built and used in `exec` mode. We propagate the `compatible_with` attribute to the `_build_script_run` target.	none