(WIP) RFC-022: support swc plugin

[jerrykingxyz]

• Feature Name: swc_plugin
• Start Date: 2022/09/16

Summary

how to use swc plugin in rspack

Motivation

the swc cannot satisfy custom transform feature, we need load some custom swc plugin to extension swc feature.
the custom plugin can from rspack or third-party like swc plugin which shared with modernjs

Prior art

how to use swc plugin

there two way to use swc plugin

1. pack swc plugin to wasm file, use it in .swcrc jsc.experimental.plugins. more info
   this is official way to create swc plugin, it can dymantic install and use plugin. because of using wasm, the running speed is much better than js.
2. use swc plugin in rspack
   this is the fastest way to use swc plugin, but it will make rspack larger

because of performance, we decided to use swc plugin in rspack and expose configurable options to control it.

Guide-level explanation

rspack swc plugin

the rspack swc plugin is officially developed and maintained by us, and its switches are in the rspack configuration file

// rspack config
{
  // define plugin
  "define": { "NULL": "null" }
}

third-party swc plugins

the third-party plugin need change rspack code to support

// rspack config
{
  "builtins": {
    "remove_console": true
  }
}

Reference-level explanation

rspack swc plugin

1. the swc plugin should be in the visitors folder
2. all uses of visitor are in mod.rs, and it expose those functions

• before_pass
• after_pass
• scan_dependency

mod visitors;
// ...
ast.visit_with(visitors::xxx)

third-party swc plugins

1. the third-party plugin should add as dependency in rspack

[dependencies]
swc_plugin_remove_console = { git = "https://github.com/xx/xxx", package = "remove_console" }
# or in crates.io
swc_plugin_remove_console = "1.0.0"

4. use it in rspack and register builtins.xxx as config param

if compilation.options.builtins.xxx {
  ast.visit_with(swc_plugin_remove_console::xxx);
};

TODO

1. Optimize the use of visitors in current code, make it all in mod.rs
2. use modernjs swc plugin in rspack

Drawbacks

1. the third-party swc plugin if use git, we can not publish rspack to crates.io.(currently we have no plans to do this)
2. If the third party lib is private, we have no way to use it
3. packing all swc plugins into rspack will makes it bigger

[hardfist]

define also need to be put into builtins because webpack doesn't support this out of box

[hyf0]

How to deal with the conflict problem that the version of crate swc in rspack and third_plugin is inconsistent?