Run bare rust CLI binary, no node

[alexeagle]

It's slow to start a NodeJS process for every spawn of swc, and it's extra weight to send to remote execution service.

SWC has a binary codenamed "swcx" which is the bare Rust binary without the node binding. This should be suitable for use in Bazel.

#57 has some longstanding WIP for this, but it needs a sponsor to fund the rest of the work.

[alexeagle]

Note, https://github.com/swc-project/swc/releases/tag/v1.3.25 contains all of @realtimetodie fixes so we should be unblocked now.

[alexeagle]

#57 has landed, thanks @realtimetodie

[binoche9]

Hi, I noticed that this changed removed the @aspect_rules_swc//swc:cli target even though it's still referenced in the documentation for using rules_swc in a custom rule

Is using rules_swc in a custom rule no longer supported, or is there some other cli tool exposed through rules_swc that I can use for a custom ctx.actions.run()?

update: I think I'm able to get it working with ctx.toolchains["@aspect_rules_swc//swc:toolchain_type"].swcinfo.swc_binary but probably worth updating the documentation

[realtimetodie]

@binoche9 I'm sorry. This is only a documentation error. The Bazel target was renamed to -> @aspect_rules_swc//swc:swc_compile.

rules_swc/swc/defs.bzl

Lines 18 to 20 in ee7ca02

	swc_compile = rule(
	doc = """Underlying rule for the `swc` macro.

The reason is, that the Bazel rule implementation only uses the compile command of the SWC cli. I think this is more sound.

In the future, there will also be a Bazel @aspect_rules_swc//swc:swc_bundle target and a Bazel @aspect_rules_swc//swc:swc_minify target, but these features are not yet implemented in the Rust-based SWC cli.

https://github.com/swc-project/swc/blob/61397267bbd672fabd83baba0f9980e3d1d84ccf/bindings/swc_cli/src/commands/bundle.rs#L10

https://github.com/swc-project/swc/blob/61397267bbd672fabd83baba0f9980e3d1d84ccf/bindings/swc_cli/src/commands/minify.rs#L10

[binoche9]

Yeah I believe that should give me enough to work with for now. Thanks for the quick response!

[alexeagle]

reopened since I think the doc fix wasn't right.

[binoche9]

Actually I'm still seeing no such target '@aspect_rules_swc//swc:swc_compile': target 'swc_compile' not declared in package 'swc' - it seems that swc_compile (in swc/defs.bzl) isn't exposed in swc/BUILD.bazel?

[alexeagle]

swc_compile is a rule, not a binary target.
Like the doc says "mimic swc/private/swc.bzl" - so you were right earlier, you need to lookup the swc toolchain and then get the swcinfo.swc_binary which will be a binary target in some external repo for the resolved platform.
https://github.com/aspect-build/rules_swc/blob/main/swc/private/swc.bzl#L202-L212

It does look like we should maybe expose the _swc_action function in the swc struct declared at the end of that file.