Exclude non-relevant selectors when generating rules with the important modifier. Fixes tailwindlabs#9677.

Author: cjpearson

CHANGELOG.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Escape special characters in resolved content base paths ([#9650](https://github.com/tailwindlabs/tailwindcss/pull/9650))
 - Don't reuse container for array returning variant functions ([#9644](https://github.com/tailwindlabs/tailwindcss/pull/9644))
+- Exclude non-relevant selectors when generating rules with the important modifier ([#9677](https://github.com/tailwindlabs/tailwindcss/issues/9677))
 
 ## [3.2.1] - 2022-10-21
 

src/lib/generateRules.js

@@ -3,7 +3,7 @@ import selectorParser from 'postcss-selector-parser'
 import parseObjectStyles from '../util/parseObjectStyles'
 import isPlainObject from '../util/isPlainObject'
 import prefixSelector from '../util/prefixSelector'
-import { updateAllClasses, getMatchingTypes } from '../util/pluginUtils'
+import { updateAllClasses, filterSelectorsForClass, getMatchingTypes } from '../util/pluginUtils'
 import log from '../util/log'
 import * as sharedState from './sharedState'
 import { formatVariantSelector, finalizeSelector } from '../util/formatVariantSelector'
@@ -116,12 +116,15 @@ function applyImportant(matches, classCandidate) {
   for (let [meta, rule] of matches) {
     let container = postcss.root({ nodes: [rule.clone()] })
     container.walkRules((r) => {
-      r.selector = updateAllClasses(r.selector, (className) => {
-        if (className === classCandidate) {
-          return `!${className}`
+      r.selector = updateAllClasses(
+        filterSelectorsForClass(r.selector, classCandidate),
+        (className) => {
+          if (className === classCandidate) {
+            return `!${className}`
+          }
+          return className
         }
-        return className
-      })
+      )
       r.walkDecls((d) => (d.important = true))
     })
     result.push([{ ...meta, important: true }, container.nodes[0]])

src/util/pluginUtils.js

@@ -37,6 +37,23 @@ export function updateAllClasses(selectors, updateClass) {
   return result
 }
 
+export function filterSelectorsForClass(selectors, classCandidate) {
+  let parser = selectorParser((selectors) => {
+    selectors.each((sel) => {
+      const containsClass = sel.nodes.some(
+        (node) => node.type === 'class' && node.value === classCandidate
+      )
+      if (!containsClass) {
+        sel.remove()
+      }
+    })
+  })
+
+  let result = parser.processSync(selectors)
+
+  return result
+}
+
 function resolveArbitraryValue(modifier, validate) {
   if (!isArbitraryValue(modifier)) {
     return undefined

tests/important-modifier.test.js

@@ -13,12 +13,13 @@ test('important modifier', () => {
           <div class="lg:!opacity-50"></div>
           <div class="xl:focus:disabled:!float-right"></div>
           <div class="!custom-parent-5"></div>
+          <div class="btn !disabled"></div>
         `,
       },
     ],
     corePlugins: { preflight: false },
     plugins: [
-      function ({ theme, matchUtilities }) {
+      function ({ theme, matchUtilities, addComponents }) {
         matchUtilities(
           {
             'custom-parent': (value) => {
@@ -31,6 +32,13 @@ test('important modifier', () => {
           },
           { values: theme('spacing') }
         )
+        addComponents({
+          '.btn': {
+            '&.disabled, &:disabled': {
+              color: 'gray',
+            },
+          },
+        })
       },
     ],
   }
@@ -70,6 +78,13 @@ test('important modifier', () => {
           max-width: 1536px !important;
         }
       }
+      .btn.disabled,
+      .btn:disabled {
+        color: gray;
+      }
+      .btn.\!disabled {
+        color: gray !important;
+      }
       .\!font-bold {
         font-weight: 700 !important;
       }