Rust Bindgen

rust_bindgen_library
rust_bindgen
rust_bindgen_toolchain
rust_bindgen_dependencies
rust_bindgen_register_toolchains

Overview

These rules are for using Bindgen to generate Rust bindings to C (and some C++) libraries.

See the bindgen example for a more complete example of use.

Setup

To use the Rust bindgen rules, add the following to your WORKSPACE file to add the external repositories for the Rust bindgen toolchain (in addition to the rust rules setup):

load("@rules_rust//bindgen:repositories.bzl", "rust_bindgen_dependencies", "rust_bindgen_register_toolchains")

rust_bindgen_dependencies()

rust_bindgen_register_toolchains()

load("@rules_rust//bindgen:transitive_repositories.bzl", "rust_bindgen_transitive_dependencies")

rust_bindgen_transitive_dependencies()

Bindgen aims to be as hermetic as possible so will end up building libclang from llvm-project from source. If this is found to be undesirable then no Bindgen related calls should be added to your WORKSPACE and instead users should define their own repositories using something akin to crate_universe and define their own toolchains following the instructions for rust_bindgen_toolchain.

rust_bindgen

rust_bindgen(name, bindgen_flags, cc_lib, clang_flags, header, merge_cc_lib_objects_into_rlib,
             wrap_static_fns)

Generates a rust source file from a cc_library and a header.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
bindgen_flags	Flags to pass directly to the bindgen executable. See https://rust-lang.github.io/rust-bindgen/ for details.	List of strings	optional	`[]`
cc_lib	The cc_library that contains the `.h` file. This is used to find the transitive includes.	Label	required
clang_flags	Flags to pass directly to the clang executable.	List of strings	optional	`[]`
header	The `.h` file to generate bindings for.	Label	required
merge_cc_lib_objects_into_rlib	When True, objects from `cc_lib` will be copied into the `rlib` archive produced by the rust_library that depends on this `rust_bindgen` rule (using `BuildInfo` provider)	Boolean	optional	`True`
wrap_static_fns	Whether to create a separate .c file for static fns. Requires nightly toolchain, and a header that actually needs this feature (otherwise bindgen won't generate the file and Bazel complains).	Boolean	optional	`False`

rust_bindgen_toolchain

rust_bindgen_toolchain(name, bindgen, clang, default_rustfmt, libclang, libstdcxx)

The tools required for the rust_bindgen rule.

This rule depends on the bindgen binary crate, and it in turn depends on both a clang binary and the clang library. To obtain these dependencies, rust_bindgen_dependencies imports bindgen and its dependencies.

load("@rules_rust//bindgen:defs.bzl", "rust_bindgen_toolchain")

rust_bindgen_toolchain(
    name = "bindgen_toolchain_impl",
    bindgen = "//my/rust:bindgen",
    clang = "//my/clang:clang",
    libclang = "//my/clang:libclang.so",
    libstdcxx = "//my/cpp:libstdc++",
)

toolchain(
    name = "bindgen_toolchain",
    toolchain = "bindgen_toolchain_impl",
    toolchain_type = "@rules_rust//bindgen:toolchain_type",
)

This toolchain will then need to be registered in the current WORKSPACE. For additional information, see the Bazel toolchains documentation.

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
bindgen	The label of a `bindgen` executable.	Label	optional	`None`
clang	The label of a `clang` executable.	Label	optional	`None`
default_rustfmt	If set, `rust_bindgen` targets will always format generated sources with `rustfmt`.	Boolean	optional	`True`
libclang	A cc_library that provides bindgen's runtime dependency on libclang.	Label	optional	`None`
libstdcxx	A cc_library that satisfies libclang's libstdc++ dependency. This is used to make the execution of clang hermetic. If None, system libraries will be used instead.	Label	optional	`None`

rust_bindgen_dependencies

rust_bindgen_dependencies()

Declare dependencies needed for bindgen.

RETURNS

list[struct(repo=str, is_dev_dep=bool)]: A list of the repositories defined by this macro.

rust_bindgen_library

rust_bindgen_library(name, header, cc_lib, bindgen_flags, bindgen_features, clang_flags,
                     wrap_static_fns, kwargs)

Generates a rust source file for header, and builds a rust_library.

Arguments are the same as rust_bindgen, and kwargs are passed directly to rust_library.

PARAMETERS

Name	Description	Default Value
name	A unique name for this target.	none
header	The label of the .h file to generate bindings for.	none
cc_lib	The label of the cc_library that contains the .h file. This is used to find the transitive includes.	none
bindgen_flags	Flags to pass directly to the bindgen executable. See https://rust-lang.github.io/rust-bindgen/ for details.	`None`
bindgen_features	The `features` attribute for the `rust_bindgen` target.	`None`
clang_flags	Flags to pass directly to the clang executable.	`None`
wrap_static_fns	Whether to create a separate .c file for static fns. Requires nightly toolchain, and a header that actually needs this feature (otherwise bindgen won't generate the file and Bazel complains",	`False`
kwargs	Arguments to forward to the underlying `rust_library` rule.	none

rust_bindgen_register_toolchains

rust_bindgen_register_toolchains(register_toolchains)

Registers the default toolchains for the rules_rust bindgen rules.

PARAMETERS

Name	Description	Default Value
register_toolchains	Whether or not to register toolchains.	`True`