Remove syntax option

[jeddy3]

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

Closes #5289

Is there anything in the PR that needs further explanation?

A work-in-progress pull request showing the removal of the:

• syntax option in favour of customSyntax
• syntaxes that aren't compatible with PostCSS 8

The rule tests reliant on the syntax option will fail until the Jest preset is updated and the tests themselves moved to customSyntax. The color-function-notation rule is done, and we can do the rest once #5295 and #5296 are merged.

This would be the third pull request for the v14 branch.

[jeddy3]

I've:

• added a message when the syntax option is used
• moved all the rules over to customSyntax

I've commented out the PostCSS@8-incompatible syntax tests for each rule. We can reinstate them if the existing syntaxes are made compatible or move them to leaner and more specific syntaxes if they are written.

Once this pull request is merged, we can start work on all the other release issues including adding more messages to ease updating.

The tests will pass once stylelint/jest-preset-stylelint#32 is merged and released.

[jeddy3]

This pull request is now ready for review.

[ybiquitous]

[suggestion] It seems that we can remove this file: ⬇️

stylelint/types/global.d.ts

Lines 1 to 5 in b01ed25

	declare module '@stylelint/postcss-css-in-js';
	declare module '@stylelint/postcss-markdown';
	declare module 'postcss-html';
	declare module 'postcss-sass';
	declare module 'sugarss';

[ybiquitous]

Also for postcss-syntax:

stylelint/types/postcss-syntax/index.d.ts

Line 1 in b01ed25

declare module 'postcss-syntax' {

[jeddy3]

I've removed the redundant types.

[hudochenkov]

Hope we won't have problems, that this stylelint will be always behind. “Thanks”, npm 7.

[jeddy3]

Where's this entry coming from, is it the jest-preset? We can set the peer to 14 when it's out.

[hudochenkov]

Yes, peerDependency of jest-preset.

[jeddy3]

Shall we remove the peer dependency? It's odd having stylelint installed in stylelint automatically.

[jeddy3]

I can do it as a patch release of the preset. We probably don't want an old version of stylelint (and postcss) hanging around as we migrate to PostCSS 8 it adds a bit of an unknown variable into the mix.

[hudochenkov]

I don't think anyone uses jest-preset to test stylelint plugin without stylelint installed. So it's probably safe to remove peer dependency.

[ybiquitous]

@jeddy3 Thank you so much for your great work! 👏🏼

[jeddy3]

Changelog:

• Removed: syntax option (#5297).

@ybiquitous No worries. Thank you for your spot-on suggestions and reviews!