[Bug]: set the syntax es6, rspack not match the API schema

[wChenonly]

Version

System:
OS: macOS 15.0.1
CPU: (8) arm64 Apple M1 Pro
Memory: 2.27 GB / 16.00 GB
Shell: 5.9 - /bin/zsh
Browsers:
Chrome: 130.0.6723.70
Safari: 18.0.1
npmPackages:
@rslib/core: ^0.0.13 => 0.0.13

Details

When I set the syntax es6, I get the error

ValidationError: Invalid configuration object. Rspack has been initialized using a configuration object that does not match the API schema.

Do we need to remove es6 to be consistent with rspack?

Keep it consistent with the official ECMAScript es2015, which is es6

Reproduce link

no

Reproduce Steps

1. rsbuild.config.ts set syntax es6

// rsbuild.config.ts
import { defineConfig } from '@rslib/core'

export default defineConfig({
  lib: [
    {
      format: 'esm',
      syntax: 'es6',
      dts: { bundle: false }
    }
  ]
})

2. executive npx rslib build

[Timeless0911]

May be we can add an alias es6 -> es2015.

[fi3ework]

Thank you for reporting the bug. We have retained "es6" because most builds support it, even though it is just an outdated alias for "es2015". This is an internal error, and we should map "es6" to "es2015" during the conversion. However, I believe we will still keep "es6". cc @chenjiahan