[Compiler Bug]: React compiler not working with babel 8 - throws (BuildHIR::lowerAssignment) Expected object property value to be an LVal, got: AssignmentPattern

What kind of issue is this?

• React Compiler core (the JS output is incorrect, or your app works incorrectly after optimization)
• babel-plugin-react-compiler (build issue installing or using the Babel plugin)
• eslint-plugin-react-hooks (build issue installing or using the eslint plugin)
• react-compiler-healthcheck (build issue installing or using the healthcheck script)

Link to repro

https://github.com/hariabinesh-l-4219/react-compiler-babel-8-issue

Repro steps

[Compiler] CompileError: /Users/hari-4219/Git/react-compiler-babel-8-issue/badge.jsx
_CompilerError [ReactCompilerError]: Found 1 error:

Todo: (BuildHIR::lowerAssignment) Expected object property value to be an LVal, got: AssignmentPattern

  1 | export const Badge = ({
> 2 |     variant = "primary",
    |     ^^^^^^^^^^^^^^^^^^^ (BuildHIR::lowerAssignment) Expected object property value to be an LVal, got: AssignmentPattern
  3 |     ...rest
  4 | }) => {
  5 |     const className = `badge badge-${variant}`;
    at new HIRBuilder (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:76126:19)
    at lower (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:78097:19)
    at runWithEnvironment (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:106368:15)
    at run (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:106361:10)
    at compileFn (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:106689:10)
    at tryCompileFunction (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:107289:19)
    at processFn (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:107226:25)
    at compileProgram (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:107107:22)
    at PluginPass.enter (/Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/babel-plugin-react-compiler/dist/index.js:108443:28)
    at newFn (file:///Users/hari-4219/Git/react-compiler-babel-8-issue/node_modules/@babel/traverse/lib/index.js:484:14) {
  details: [ CompilerErrorDetail { options: [Object] } ],
  disabledDetails: [],
  printedMessage: 'Found 1 error:\n' +
    '\n' +
    'Todo: (BuildHIR::lowerAssignment) Expected object property value to be an LVal, got: AssignmentPattern\n' +
    '\n' +
    '  1 | export const Badge = ({\n' +
    '> 2 |     variant = "primary",\n' +
    '    |     ^^^^^^^^^^^^^^^^^^^ (BuildHIR::lowerAssignment) Expected object property value to be an LVal, got: AssignmentPattern\n' +
    '  3 |     ...rest\n' +
    '  4 | }) => {\n' +
    '  5 |     const className = `badge badge-${variant}`;',
  code: 'BABEL_TRANSFORM_ERROR'
}

Possible solution: Lval check needs additional isPatternLike check as per babel docs. https://babeljs.io/docs/v8-migration-api

How often does this bug happen?

Every time

What version of React are you using?

19.2.4

What version of React Compiler are you using?

1.0.0