space-before-function-paren removes comments when fixing

[zaygraveyard]

Tell us about your environment

• ESLint Version: v6.3.0
• Node Version: NA (using https://eslint.org/demo)
• npm Version: NA (using https://eslint.org/demo)

What parser (default, Babel-ESLint, etc.) are you using?
default

Please show your full configuration:

Configuration

{
    "parserOptions": {
        "ecmaVersion": 10,
        "sourceType": "module",
        "ecmaFeatures": {}
    },
    "rules": {
        "space-before-function-paren": ["error", "never"]
    },
    "env": {}
}

What did you do? Please include the actual source code causing the issue, as well as the command that you used to run ESLint.

Tried to fix the following code

function delay /*:: <T>*/() {}

https://eslint.org/demo#eyJ0ZXh0IjoiLyplc2xpbnQgc3BhY2UtYmVmb3JlLWZ1bmN0aW9uLXBhcmVuOiBbJ2Vycm9yJywgJ25ldmVyJ10qL1xuZnVuY3Rpb24gZGVsYXkgLyo6OiA8VD4qLygpIHt9Iiwib3B0aW9ucyI6eyJwYXJzZXJPcHRpb25zIjp7ImVjbWFWZXJzaW9uIjoxMSwic291cmNlVHlwZSI6Im1vZHVsZSIsImVjbWFGZWF0dXJlcyI6e319LCJydWxlcyI6e30sImVudiI6e319fQ==

What did you expect to happen?
The space after delay to be removed while preserving the comment.

What actually happened? Please include the actual, raw output from ESLint.
The space and the comment after delay got removed.

Are you willing to submit a pull request to fix this bug?
No

Cause

eslint/lib/rules/space-before-function-paren.js

Line 127 in 460c5ad

fix: fixer => fixer.removeRange([leftToken.range[1], rightToken.range[0]])

The fixing is done by removing everything between the identifier and the opening parenthesis (without taking comments into consideration)

[mdjermanovic]

Hi @zaygraveyard, thanks for the report! I can reproduce this bug.

[mdjermanovic]

Perhaps we could implement here the logic from template-tag-spacing?

Demo

It concatenates all block comments. If there is a line comment, just reports without the autofix.

[zaygraveyard]

@mdjermanovic yes, this would indeed fix this issue since it would preserve the comments

[mdjermanovic]

I'm working on this