arrow-parens ("as-needed") doesn't take async into account

[jlsjonas]

Tell us about your environment

• ESLint Version: 3.19.0 (with the latest babel-eslint)
• Node Version: 7.9.0
• npm Version: 4.2.0

What parser (default, Babel-ESLint, etc.) are you using? babel-eslint (as eslint doesn't support async

Please show your full configuration:

final test with the following, still breaks:

{
  "root": true,
  "parser": "babel-eslint",
  "parserOptions": {
    "ecmaVersion": 7,
    "sourceType": "module",
    "ecmaFeatures": {
      "jsx": true,
      "impliedStrict": true,
      "experimentalObjectRestSpread": true
    }
  },
  "env": {
    "browser": true,
    "mocha": true,
    "node": true,
    "es6": true
  },
  "globals": {
    "describe": false,
    "it": false
  },
  "rules": {
    "arrow-parens": [
      2,
      "as-needed"
    ]
  }
}

What did you do? Please include the actual source code causing the issue.

const foo = async(bar) => {
//...
}

What did you expect to happen?
fix to

const foo = async bar => {
//...
}```
(or just skip the line, would be fine too)

**What actually happened? Please include the actual, raw output from ESLint.**
```js
const foo = asyncbar => {
//...
}

as the async was no longer async (but asyncbar), causing the function to no longer be an async function

/path/to/foo.js
  24:25  error  Parsing error: await is a reserved word

[soda0289]

Thanks for the report.

I can confirm this broken behavior. It should add a space.