docs/cargo_build_script.md

<!-- Generated with Stardoc: http://skydoc.bazel.build -->
# Cargo Build Script

* [cargo_build_script](#cargo_build_script)

<a id="#cargo_build_script"></a>

## cargo_build_script

<pre>
cargo_build_script(<a href="#cargo_build_script-name">name</a>, <a href="#cargo_build_script-crate_features">crate_features</a>, <a href="#cargo_build_script-version">version</a>, <a href="#cargo_build_script-deps">deps</a>, <a href="#cargo_build_script-build_script_env">build_script_env</a>, <a href="#cargo_build_script-data">data</a>, <a href="#cargo_build_script-links">links</a>, <a href="#cargo_build_script-rustc_env">rustc_env</a>,
                   <a href="#cargo_build_script-kwargs">kwargs</a>)
</pre>

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`:

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

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

`hello_lib/BUILD`:
```python
package(default_visibility = ["//visibility:public"])

load("@rules_rust//rust:rust.bzl", "rust_binary", "rust_library")
load("@rules_rust//cargo:cargo_build_script.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 |
| :------------- | :------------- | :------------- |
| <a id="cargo_build_script-name"></a>name |  The name for the underlying rule. This should be the name of the package being compiled, optionally with a suffix of _build_script.   |  none |
| <a id="cargo_build_script-crate_features"></a>crate_features |  A list of features to enable for the build script.   |  <code>[]</code> |
| <a id="cargo_build_script-version"></a>version |  The semantic version (semver) of the crate.   |  <code>None</code> |
| <a id="cargo_build_script-deps"></a>deps |  The dependencies of the crate.   |  <code>[]</code> |
| <a id="cargo_build_script-build_script_env"></a>build_script_env |  Environment variables for build scripts.   |  <code>{}</code> |
| <a id="cargo_build_script-data"></a>data |  Files or tools needed by the build script.   |  <code>[]</code> |
| <a id="cargo_build_script-links"></a>links |  Name of the native library this crate links against.   |  <code>None</code> |
| <a id="cargo_build_script-rustc_env"></a>rustc_env |  Environment variables to set in rustc when compiling the build script.   |  <code>{}</code> |
| <a id="cargo_build_script-kwargs"></a>kwargs |  Forwards to the underlying <code>rust_binary</code> rule.   |  none |