System Info

System:
OS: Linux 6.8 Ubuntu 22.04.4 LTS 22.04.4 LTS (Jammy Jellyfish)
CPU: (4) x64 AMD EPYC 9R45
Memory: 9.60 GB / 30.74 GB
Container: Yes
Shell: 5.8.1 - /bin/zsh
Binaries:
Node: 22.13.0 - ~/.nvm/versions/node/v22.13.0/bin/node
Yarn: 1.22.22 - ~.nvm/versions/node/v22.13.0/bin/yarn
npm: 10.9.2 - ~/.nvm/versions/node/v22.13.0/bin/npm
pnpm: 8.15.9 - ~/.nvm/versions/node/v22.13.0/bin/pnpm
npmPackages:
@rspack/cli: 2.0.1 => 2.0.1
@rspack/core: 2.0.1 => 2.0.1
@rspack/dev-server: 2.0.1 => 2.0.1
@rspack/plugin-react-refresh: ^2.0.0 => 2.0.0

Details

SWC compress drops function call arguments inside inner generator

SwcJsMinimizerRspackPlugin drops call arguments from a function call inside an inner generator when the callee was destructured from an options object and conditionally reassigned.

Trigger

All three conditions are required:

1. var { match } = options — callee destructured from an object parameter
2. if (!match) { match = () => true; } — if-based conditional reassignment (logically equivalent expressions do not trigger it)
3. if (!match(a, b)) continue; — called with arguments inside a for...of loop in an inner generator

Changing any one (e.g. match = match || (() => true) for condition 2, or a direct parameter instead of destructuring for condition 1) prevents the bug.

Reproduce link

https://github.com/academia-edu/rspack-dropped-arguments-repro/tree/erik/dropped-arguments-repro

Reproduce Steps

Reproduce

pnpm install
pnpm run build

Open rspack-dist/index.html → shows FAIL (red)
Open webpack-dist/index.html → shows PASS (green)

Source (src/index.js)

function outer(options) {
  return function* () {
    var { match } = options;
    if (!match) {
      match = () => true;
    }
    for (var [a, b] of [[1, 2], [3, 4]]) {
      if (!match(a, b)) continue;   // ← BUG: compiled to match() by rspack
      yield [a, b];
    }
  };
}

Output diff

rspack (rspack-dist/main.js):

function*(){var{match:e}=t;for(var[o,d]of(e||(e=()=>!0),[[1,2],[3,4]]))e()&&(yield[o,d])
//                                                                      ^^
//                                            match(a, b) compiled to match() — args DROPPED

webpack (webpack-dist/main.js):

function*(){var{match:o}=t;for(var[e,c]of(o||(o=()=>!0),[[1,2],[3,4]]))o(e,c)&&(yield[e,c])
//                                                                      ^^^^
//                                                              match(a, b) preserved — correct

Real-world impact

This is the exact pattern in slate@0.124.1 Editor.nodes. When bundled with rspack in production mode, match(node, path) compiles to match(), so the match predicate receives undefined as the node and crashes with:

TypeError: Cannot read properties of undefined (reading 'text')