Remove text opacity CSS variables from ::marker (#8622)

* Refactor

* Allow parallel variant fns to mutate the container

* Remove text color variable from marker pseudo class

wip

* Update changelog

CHANGELOG.md

@@ -15,6 +15,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fix missing spaces around arithmetic operators ([#8615](https://github.com/tailwindlabs/tailwindcss/pull/8615))
 - Detect alpha value in CSS `theme()` function when using quotes ([#8625](https://github.com/tailwindlabs/tailwindcss/pull/8625))
 - Fix "Maximum call stack size exceeded" bug ([#8636](https://github.com/tailwindlabs/tailwindcss/pull/8636))
+- Allow functions returning parallel variants to mutate the container ([#8622](https://github.com/tailwindlabs/tailwindcss/pull/8622))
+- Remove text opacity CSS variables from `::marker` ([#8622](https://github.com/tailwindlabs/tailwindcss/pull/8622))
 
 ## [3.1.2] - 2022-06-10
 

src/corePlugins.js

@@ -14,14 +14,27 @@ import { version as tailwindVersion } from '../package.json'
 import log from './util/log'
 import { normalizeScreens } from './util/normalizeScreens'
 import { formatBoxShadowValue, parseBoxShadowValue } from './util/parseBoxShadowValue'
+import { removeAlphaVariables } from './util/removeAlphaVariables'
 import { flagEnabled } from './featureFlags'
 
 export let variantPlugins = {
   pseudoElementVariants: ({ addVariant }) => {
     addVariant('first-letter', '&::first-letter')
     addVariant('first-line', '&::first-line')
 
-    addVariant('marker', ['& *::marker', '&::marker'])
+    addVariant('marker', [
+      ({ container }) => {
+        removeAlphaVariables(container, ['--tw-text-opacity'])
+
+        return '& *::marker'
+      },
+      ({ container }) => {
+        removeAlphaVariables(container, ['--tw-text-opacity'])
+
+        return '&::marker'
+      },
+    ])
+
     addVariant('selection', ['& *::selection', '&::selection'])
 
     addVariant('file', '&::file-selector-button')
@@ -77,21 +90,11 @@ export let variantPlugins = {
       [
         'visited',
         ({ container }) => {
-          let toRemove = ['--tw-text-opacity', '--tw-border-opacity', '--tw-bg-opacity']
-
-          container.walkDecls((decl) => {
-            if (toRemove.includes(decl.prop)) {
-              decl.remove()
-
-              return
-            }
-
-            for (const varName of toRemove) {
-              if (decl.value.includes(`/ var(${varName})`)) {
-                decl.value = decl.value.replace(`/ var(${varName})`, '')
-              }
-            }
-          })
+          removeAlphaVariables(container, [
+            '--tw-text-opacity',
+            '--tw-border-opacity',
+            '--tw-bg-opacity',
+          ])
 
           return '&:visited'
         },

src/lib/generateRules.js

@@ -163,15 +163,17 @@ function applyVariant(variant, matches, context) {
 
       let container = postcss.root({ nodes: [rule.clone()] })
 
-      for (let [variantSort, variantFunction] of variantFunctionTuples) {
-        let clone = container.clone()
+      for (let [variantSort, variantFunction, containerFromArray] of variantFunctionTuples) {
+        let clone = containerFromArray ?? container.clone()
         let collectedFormats = []
 
-        let originals = new Map()
-
         function prepareBackup() {
-          if (originals.size > 0) return // Already prepared, chicken out
-          clone.walkRules((rule) => originals.set(rule, rule.selector))
+          // Already prepared, chicken out
+          if (clone.raws.neededBackup) {
+            return
+          }
+          clone.raws.neededBackup = true
+          clone.walkRules((rule) => (rule.raws.originalSelector = rule.selector))
         }
 
         function modifySelectors(modifierFunction) {
@@ -231,6 +233,10 @@ function applyVariant(variant, matches, context) {
               // reserving additional X places for these 'unknown' variants in between.
               variantSort | BigInt(idx << ruleWithVariant.length),
               variantFunction,
+
+              // If the clone has been modified we have to pass that back
+              // though so each rule can use the modified container
+              clone.clone(),
             ])
           }
           continue
@@ -244,13 +250,15 @@ function applyVariant(variant, matches, context) {
           continue
         }
 
-        // We filled the `originals`, therefore we assume that somebody touched
+        // We had to backup selectors, therefore we assume that somebody touched
         // `container` or `modifySelectors`. Let's see if they did, so that we
         // can restore the selectors, and collect the format strings.
-        if (originals.size > 0) {
+        if (clone.raws.neededBackup) {
+          delete clone.raws.neededBackup
           clone.walkRules((rule) => {
-            if (!originals.has(rule)) return
-            let before = originals.get(rule)
+            let before = rule.raws.originalSelector
+            if (!before) return
+            delete rule.raws.originalSelector
             if (before === rule.selector) return // No mutation happened
 
             let modified = rule.selector

src/util/removeAlphaVariables.js

@@ -0,0 +1,24 @@
+/**
+ * This function removes any uses of CSS variables used as an alpha channel
+ *
+ * This is required for selectors like `:visited` which do not allow
+ * changes in opacity or external control using CSS variables.
+ *
+ * @param {import('postcss').Container} container
+ * @param {string[]} toRemove
+ */
+export function removeAlphaVariables(container, toRemove) {
+  container.walkDecls((decl) => {
+    if (toRemove.includes(decl.prop)) {
+      decl.remove()
+
+      return
+    }
+
+    for (let varName of toRemove) {
+      if (decl.value.includes(`/ var(${varName})`)) {
+        decl.value = decl.value.replace(`/ var(${varName})`, '')
+      }
+    }
+  })
+}

tests/parallel-variants.test.js

@@ -85,3 +85,52 @@ test('parallel variants can be generated using a function that returns parallel
     `)
   })
 })
+
+test('a function that returns parallel variants can modify the container', async () => {
+  let config = {
+    content: [
+      {
+        raw: html`<div
+          class="hover:test:font-black test:font-bold test:font-medium font-normal"
+        ></div>`,
+      },
+    ],
+    plugins: [
+      function test({ addVariant }) {
+        addVariant('test', ({ container }) => {
+          container.walkDecls((decl) => {
+            decl.value = `calc(0 + ${decl.value})`
+          })
+
+          return ['& *::test', '&::test']
+        })
+      },
+    ],
+  }
+
+  return run('@tailwind utilities', config).then((result) => {
+    expect(result.css).toMatchFormattedCss(css`
+      .font-normal {
+        font-weight: 400;
+      }
+      .test\:font-bold *::test {
+        font-weight: calc(0 + 700);
+      }
+      .test\:font-medium *::test {
+        font-weight: calc(0 + 500);
+      }
+      .test\:font-bold::test {
+        font-weight: calc(0 + 700);
+      }
+      .test\:font-medium::test {
+        font-weight: calc(0 + 500);
+      }
+      .hover\:test\:font-black *:hover::test {
+        font-weight: calc(0 + 900);
+      }
+      .hover\:test\:font-black:hover::test {
+        font-weight: calc(0 + 900);
+      }
+    `)
+  })
+})

tests/variants.test.css

@@ -112,16 +112,14 @@
   line-height: 1.75rem;
 }
 .marker\:text-red-500 *::marker {
-  --tw-text-opacity: 1;
-  color: rgb(239 68 68 / var(--tw-text-opacity));
+  color: rgb(239 68 68);
 }
 .marker\:text-lg::marker {
   font-size: 1.125rem;
   line-height: 1.75rem;
 }
 .marker\:text-red-500::marker {
-  --tw-text-opacity: 1;
-  color: rgb(239 68 68 / var(--tw-text-opacity));
+  color: rgb(239 68 68);
 }
 .selection\:bg-blue-500 *::selection {
   --tw-bg-opacity: 1;

tests/variants.test.js

@@ -485,8 +485,7 @@ test('returning non-strings and non-selectors in addVariant', () => {
 
         addVariant('peer-aria-expanded-2', ({ modifySelectors, separator }) => {
           let nodes = modifySelectors(
-            ({ className }) =>
-              `.peer[aria-expanded="false"] ~ .${e(`peer-aria-expanded${separator}${className}`)}`
+            ({ className }) => `.${e(`peer-aria-expanded-2${separator}${className}`)}`
           )
 
           return [