feat(mangler): mangle private class names

[camc314]

$ cat test.js
class Foo {
  constructor(k) {
    this.#kasd = k;
  }

  getK() {
    return this.#kasd;
  }
}
class Foo2 {
  constructor(k) {
    this.#kasd = k;
  }

  getK() {
    return this.#kasd;
  }
}

export { Foo, Foo2 };
$ cargo run -p oxc_minifier --example minifier -- --mangle
   Compiling oxc_mangler v0.51.0 (/Users/cameron/github/Boshen/oxc/crates/oxc_mangler)
   Compiling oxc_minifier v0.51.0 (/Users/cameron/github/Boshen/oxc/crates/oxc_minifier)
    Finished `dev` profile [unoptimized] target(s) in 0.96s
     Running `target/debug/examples/minifier --mangle`
class Foo {
        constructor(e) {
                this.#e = e;
        }
        getK() {
                return this.#e;
        }
}
class Foo2 {
        constructor(e) {
                this.#e = e;
        }
        getK() {
                return this.#e;
        }
}
export { Foo, Foo2 };

No diff on cargo misize. looks like non of the test suite has classes with private class members

[camc314]

• #9279 👈 (View in Graphite)
• #9278
• main

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[codspeed-hq[bot]]

CodSpeed Performance Report

Merging #9279 will degrade performances by 88.4%

_{Comparing c/02-21-feat_mangler_mangle_private_class_names (9106d71) with main (4ad328b)}

Summary

❌ 3 regressions
✅ 30 untouched benchmarks

:warning: Please fix the performance issues or acknowledge them on CodSpeed.

Benchmarks breakdown

	Benchmark	BASE	HEAD	Change
❌	mangler[antd.js]	16.2 ms	139.3 ms	-88.4%
❌	mangler[react.development.js]	299.4 µs	1,766.4 µs	-83.05%
❌	mangler[typescript.js]	39.8 ms	280.4 ms	-85.79%

[Boshen]

This adds an additional AST pass, but how come it's not shown on the benchmark 🤔 ?

[camc314]

so i implemented this inside: https://github.com/oxc-project/oxc/blob/82c354a1c23d0581c5be94ed50317291f39102fd/crates/oxc_minifier/src/lib.rs#L48 minifier::build. but that fn doesn't run when doing the benches. we run the mangler/minifier explicitly.

i think i could either:

1. move this directly into the mangler
2. move this as a minifier pass probably 1 is better?

[Boshen]

• move this directly into the mangler

Yeah this seems better. We can also add a flag (turned off by default) to enable this.