Fix false positives for SCSS variables in function-calc-no-unspaced-operator

[peter-neumann-dev]

What steps are needed to reproduce the bug?

textarea {
  min-height: calc(#{$line-height} * 5);
}

What Stylelint configuration is needed to reproduce the bug?

module.exports = {
  plugins: [
    'stylelint-scss',
  ],
  extends: ['stylelint-config-standard-scss'],
  rules: { },
}

How did you run Stylelint?

CLI with stylelint 'css/**/*.scss'

Which version of Stylelint are you using?

14.8.1

What did you expect to happen?

Behavior like in previous versions <= 14.8.0

What actually happened?

css/components/_forms.scss
 213:27  ✖  Expected single space before "-" operator  function-calc-no-unspaced-operator
 213:28  ✖  Expected single space after "-" operator   function-calc-no-unspaced-operator

Does the bug relate to non-standard syntax?

Yes it happens with SCSS variables inside calc()

Proposal to fix the bug

This happens only in the newest version 14.8.1 with this fixed: #6045

[jeddy3]

@peter-neumann-dev Thanks for the report and for using the template.

I can reproduce with the demo.

I've labelled the issue as ready to implement. Please consider contributing if you have time.

There are steps on how to fix a bug in a rule in the Developer guide.

It should just be the case of using the isStandardSyntaxMathFunction util on Line 310:

stylelint/lib/rules/function-calc-no-unspaced-operator/index.js

Lines 309 to 311 in e017583

	if (node.type !== 'function' || node.value.toLowerCase() !== 'calc') return;
	const { nodes } = node;

And then updating the tests to reflect that the rule will now outright ignore any calc functions that contain non-standard syntax.

[ybiquitous]

@peter-neumann-dev Thanks for the report and sorry for the inconvenience.
I've opened PR #6053 to fix the regression. I expect the next version will include the fix.