False positives for parameterless functions in function-parentheses-space-inside

[PhilippSoehnlein]

Describe the issue. Is it a bug or a feature request (new rule, new option, etc.)?

A bug where the function-parentheses-space-inside rule set to always-single-line reports a warning for functions with no params.
IMO this shouldn't be flagged or even if, an except-option for functions with no params should be possible.

Which rule, if any, is this issue related to?

function-parentheses-space-inside

What CSS is needed to reproduce this issue?

@function someFunction() {
    @return 'someUrl';
}
.foo {
    background-image: someFunction();
}

What stylelint configuration is needed to reproduce this issue?

e.g.

{
  "rules": {
    "function-parentheses-space-inside": "always-single-line"
  }
}

Which version of stylelint are you using?

7.10.1

How are you running stylelint: CLI, PostCSS plugin, Node API?

CLI

Does your issue relate to non-standard syntax (e.g. SCSS, nesting, etc.)?

Yes, it's related to SCSS.

What did you expect to happen?

No warnings to be flagged.

What actually happened (e.g. what warnings or errors you are getting)?

Expected single space before ")" in a single-line function

[jeddy3]

@PhilippSoehnlein Thank you for the report and for using the issue template.

IMO this shouldn't be flagged

Yes, you're right. It's should not flag a violation.

I believe there are two possible fixes, depending on whether parameterless functions are valid construct in CSS. Do you know if they are?

If not, we should ignore them in isStandardSyntaxFunction.

Otherwise, we should bake an early return into function-parentheses-space-inside directly.

[hudochenkov]

@jeddy3 I did a research. url() is valid. Also some filter functions could have no parameters.

[jeddy3]

Thanks for doing the research!

[hudochenkov]

@PhilippSoehnlein thank you for reporting!

Fixed by #2587.