@stylistic/stylelint-plugin/lib/utils/isStandardSyntaxAtRule/index.js

A collection of stylistic/formatting Stylelint rules

/**
 * Check whether a at-rule is standard
 *
 * @param {import('postcss').AtRule | import('postcss-less').AtRule} atRule postcss at-rule node
 * @return {boolean} If `true`, the declaration is standard
 */
export function isStandardSyntaxAtRule (atRule) {
	// Ignore scss `@content` inside mixins
	if (!atRule.nodes && atRule.params === ``) {
		return false
	}

	// Ignore Less mixins
	if (`mixin` in atRule && atRule.mixin) {
		return false
	}

	// Ignore Less detached ruleset `@detached-ruleset: { background: red; }; .top { @detached-ruleset(); }`
	if ((`variable` in atRule && atRule.variable) || (!atRule.nodes && atRule.raws.afterName === `` && atRule.params[0] === `(`)) {
		return false
	}

	return true
}