Fix syntax inference with processors

[yaymukund]

Clearly describe the bug

If your config contains a processor, stylelint no longer uses postcss-syntax to infer the syntax and defaults to the css parser. The change appeared in version 13.4.0. It's not clear to me if it was an oversight or an intended change in behavior, but here's the relevant line:

https://github.com/stylelint/stylelint/pull/4729/files#diff-5383a0a864da5a5ad24b4bae8f44c5574601bd4d145999b1ddc211d3900dd68bL89

I know that there's discussion of deprecating the processor option, but in the meantime I think this could be better documented. I'm happy to submit a docs PR if that sounds good.

Which rule, if any, is the bug related to?

Not related to a specific rule.

What code is needed to reproduce the bug?

// In an scss file, add double slash comments.

What stylelint configuration is needed to reproduce the bug?

{
  "processors": ["stylelint-processor-styled-components", {}]
}

Which version of stylelint are you using?

13.4.1

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

$ stylelint "**/*.scss" --config myconfig.json

Does the bug relate to non-standard syntax (e.g. SCSS, Less etc.)?

Yes, it's related to scss syntax in my case, but in theory would apply to any syntax that a CSS parser would reject.

What did you expect to happen?

Expected no warnings.

What actually happened (e.g. what warnings or errors did you get)?

Error: Unexpected '/'. Escaping special characters with \ may help.
  at ...styles.scss

Thank you for taking a look :)

[jeddy3]

@yaymukund Thanks for the clear report and for using the template.

I've dug into this and it looks like an oversight on my behalf in #4729.

It's only autofix that is incompatible with processors, not custom syntaxes outright. We already have a check for that:

stylelint/lib/getPostcssResult.js

Lines 86 to 97 in a9db12a

	if (options.codeProcessors && options.codeProcessors.length) {
	if (stylelint._options.fix) {
	console.warn(
	'Autofix is incompatible with processors and will be disabled. Are you sure you need a processor?',
	);
	stylelint._options.fix = false;
	}
	options.codeProcessors.forEach((codeProcessor) => {
	preProcessedCode = codeProcessor(preProcessedCode, source);
	});
	}

I've labelled the issue as a bug and ready to implement.

[eMerzh]

hello @jeddy3 ...i just notice this issue too while willing to upgrade to v15 ...

is there some work around ? or plan?

thanks a lot :)

[jeddy3]

@eMerzh You should use a custom syntax rather than processor. See the migration guide.

Thanks for drawing my attention to this issue. I'll close it as it's no longer relevant since we removed processors in 15.0.0.