Static method arrow function does not name anonymous function

[reggi]

I'd expect M.blue.name to be blue, but for some reason arrow functions don't have a name. Is this a bug or intentional?

class M {
static green () { return 'green' }
static blue = () => 'green'
}
module.exports = M

var M = function () {
  function M() {
    _classCallCheck(this, M);
  }

  _createClass(M, null, [{
    key: 'green',
    value: function green() {
      return 'green';
    }
  }]);

  return M;
}();

M.blue = function () {
    'green'
};

Guess I'd love it to be like this instead:

M.blue = function blue () {
    'green'
};

[babel-bot]

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[thymikee]

Can you provide a repro? What are the plugins/presets you're using?
I can only verify that with

"plugins": [
  "@babel/plugin-proposal-class-properties"
]

produces this output

class M {
  static green() {
    return 'green';
  }

}

Object.defineProperty(M, "blue", {
  configurable: true,
  enumerable: true,
  writable: true,
  value: () => 'green'
});
module.exports = M;

and M.blue.name === 'value', so it looks like a bug.

Babel & plugin version: 7.0.0.beta.40

[Andarist]

@thymikee I guess he is using loose mode which doesn't use defineProperty for static methods, just a simple assignments.

Also defineProperty usage is related to what you can see - value inferred as name of this function because it's used as value (:<) of the descriptor's property called value

And it definitely could be polished, I'm not sure if function naming is centralized any where (this would mean that it's probably a bug) or is it scattered around the codebase and dependant on some helper usage (this would mean that we should detect the call site - where those functions are inserted and use helper on the inserted node)

[thymikee]

Oh, that's unfortunate. Looks like that arrow should be eventually replaced with a named function in both cases, right?

[Andarist]

Ain't sure if class properties (static or not) have inferred names - I think spec says they can, but I'm not the best ecma spec reader :/

[thymikee]

I'm not an expert either, but looking at https://tc39.github.io/proposal-class-public-fields/#initialize-public-instance-fields I could tell the spec says .name should be derived from the field name:

[Andarist]

Yeah, I suspect this is right reasoning. I guess the only way to 'fix' it is to transform directly to named functions, because at later point any other transform won't have enough info to infer the name correctly (just like in the value example).

[vivek12345]

Does this still need help? Can I pick this up?