error in the generator-star-spacing rule

[romeovs]

What version of ESLint are you using?

$ node_modules/.bin/eslint -v                                                                                                                                     
v2.13.1

What parser (default, Babel-ESLint, etc.) are you using?
babel-eslint
Please show your full configuration:

parser: babel-eslint
extends: standard
plugins:
  - flowtype

env:
  node: true
  mocha: true

rules:
  # allow dangling comma
  no-comma-dangle: off
  comma-dangle:
    - error
    - always-multiline

  flowtype/space-after-type-colon:
    - error
    - always

  flowtype/space-before-type-colon:
    - error
    - always

  no-var:
    - error

  no-console:
    - error

What did you do? Please include the actual source code causing the issue.
$ eslint src/
What did you expect to happen?
No error to happen, just lint.

What actually happened? Please include the actual, raw output from ESLint.

Got the error

/Users/romeo/code/go/foo/node_modules/eslint/lib/rules/generator-star-spacing.js:69
            while (token.value !== "*") {
                        ^

TypeError: Cannot read property 'value' of undefined
    at getStarToken (/Users/romeo/code/go/foo/node_modules/eslint/lib/rules/generator-star-spacing.js:69:25)
    at EventEmitter.checkFunction (/Users/romeo/code/go/foo/node_modules/eslint/lib/rules/generator-star-spacing.js:125:29)
    at emitOne (events.js:82:20)
    at EventEmitter.emit (events.js:169:7)
    at NodeEventGenerator.enterNode (/Users/romeo/code/go/foo/node_modules/eslint/lib/util/node-event-generator.js:40:22)
    at CodePathAnalyzer.enterNode (/Users/romeo/code/go/foo/node_modules/eslint/lib/code-path-analysis/code-path-analyzer.js:607:23)
    at CommentEventGenerator.enterNode (/Users/romeo/code/go/foo/node_modules/eslint/lib/util/comment-event-generator.js:97:23)
    at Controller.traverser.traverse.enter (/Users/romeo/code/go/foo/node_modules/eslint/lib/eslint.js:905:36)
    at Controller.__execute (/Users/romeo/code/go/foo/node_modules/eslint/node_modules/estraverse/estraverse.js:397:31)
    at Controller.traverse (/Users/romeo/code/go/foo/node_modules/eslint/node_modules/estraverse/estraverse.js:501:28)

[vitorbal]

Thanks, @romeovs! ESLint core rules don't support experimental features (async function is still stage 3). You should use the generator-star-spacing that is provided by the eslint-plugin-babel.

Let me know if that fixes the problem, and If you have any other questions feel free to drop by our Gitter chatroom and we will be happy to help with anything!

[romeovs]

that fixes it!

[vitorbal]

Glad to hear! :)

[michaelficarra]

@vitorbal What made you think @romeovs was using an async function?

@romeovs Please post the actual source code, as requested in the template that you partially filled out.

[romeovs]

I was using async functions to be clear.
The actual codebase I'm running this on so it's hard to tell where the problem originates from.

I can reproduce the bug on this snippet:

async function derp () {
  console.log('never gonna give you up')
}

but it does not occur on this one:

function derp () {
  console.log('never gonna let you down')
}

[vitorbal]

@michaelficarra you're totally right, I just assumed it was since we've had a couple of similar issues these past weeks. Thanks for double-checking!

[ljharb]

Since async/await is now stage 4, should this be reopened?

[ilyavolodin]

@ljharb It's still not implemented in Acorn/Espree, so I think we should hold off till we can actually implant this change.

[ljharb]

Sounds good! Linking to acornjs/acorn#441 and eslint/espree#287