rules_rust_wasm_bindgen

Bazel rules for generating wasm modules for Javascript using wasm-bindgen.

Rules

rust_wasm_bindgen
rust_wasm_bindgen_toolchain

Setup

To begin using the wasm-bindgen rules, users can load the necessary dependencies in their workspace by adding the following to their WORKSPACE.bazel file.

load("@rules_rust_wasm_bindgen//:repositories.bzl", "rust_wasm_bindgen_dependencies", "rust_wasm_bindgen_register_toolchains")

rust_wasm_bindgen_dependencies()

rust_wasm_bindgen_register_toolchains()

This should enable users to start using the rust_wasm_bindgen rule. However, it's common to want to control the version of wasm-bindgen in the workspace instead of relying on the one provided by rules_rust. In this case, users should avoid calling rust_wasm_bindgen_register_toolchains and instead use the rust_wasm_bindgen_toolchain rule to define their own toolchains to register in the workspace.

Interfacing with Javascript rules

While it's recommended for users to mantain their own , in the @rules_rust_wasm_bindgen package there exists interface sub-packages for various Javascript Bazel rules. E.g. aspect_rules_js. The rules defined there are a more convenient way to use rust_wasm_bindgen with the associated javascript rules due to the inclusion of additional providers. Each directory contains a defs.bzl file that defines the different variants of rust_wasm_bindgen. (e.g. js_rust_wasm_bindgen for the rules_js submodule).

rust_wasm_bindgen

Generates javascript and typescript bindings for a webassembly module using wasm-bindgen.

An example of this rule in use can be seen at @rules_rust//examples/wasm

ATTRIBUTES

Name	Description	Type	Mandatory	Default
name	A unique name for this target.	Name	required
bindgen_flags	Flags to pass directly to the wasm-bindgen executable. See https://github.com/rustwasm/wasm-bindgen/ for details.	List of strings	optional	`[]`
out_name	Set a custom output filename (Without extension. Defaults to target name).	String	optional	`""`
target	The type of output to generate. See https://rustwasm.github.io/wasm-bindgen/reference/deployment.html for details.	String	optional	`"bundler"`
target_arch	The target architecture to use for the wasm-bindgen command line option.	String	optional	`"wasm32"`
wasm_file	The `.wasm` file or crate to generate bindings for.	Label	required

rust_wasm_bindgen_toolchain

The tools required for the rust_wasm_bindgen rule.

In cases where users want to control or change the version of wasm-bindgen used by rust_wasm_bindgen, a unique toolchain can be created as in the example below:

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

rust_bindgen_toolchain(
    bindgen = "//3rdparty/crates:wasm_bindgen_cli__bin",
)

toolchain(
    name = "wasm_bindgen_toolchain",
    toolchain = "wasm_bindgen_toolchain_impl",
    toolchain_type = "@rules_rust_wasm_bindgen//:toolchain_type",
)

Now that you have your own toolchain, you need to register it by inserting the following statement in your WORKSPACE file:

register_toolchains("//my/toolchains:wasm_bindgen_toolchain")

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 `wasm-bindgen-cli` executable.	Label	optional	`None`

RustWasmBindgenInfo

Info about wasm-bindgen outputs.

FIELDS

Name	Description
js	Depset[File]: The Javascript files produced by `wasm-bindgen`.
root	str: The path to the root of the `wasm-bindgen --out-dir` directory.
snippets	File: The snippets directory produced by `wasm-bindgen`.
ts	Depset[File]: The Typescript files produced by `wasm-bindgen`.
wasm	File: The `.wasm` file generated by `wasm-bindgen`.