Fix consecutive builds with at apply producing different CSS (#6999)

* Partition at rules before building context

* remove unnecessary logic

* Update changelog

Co-authored-by: Robin Malfait <malfait.robin@gmail.com>

Author: thecrypticace

CHANGELOG.md

@@ -7,7 +7,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
-- Nothing yet!
+### Fixed
+
+- Fix consecutive builds with at apply producing different CSS ([#6999](https://github.com/tailwindlabs/tailwindcss/pull/6999))
 
 ## [3.0.12] - 2022-01-07
 

src/lib/partitionApplyAtRules.js

@@ -0,0 +1,52 @@
+function partitionRules(root) {
+  if (!root.walkAtRules) return
+
+  let applyParents = new Set()
+
+  root.walkAtRules('apply', (rule) => {
+    applyParents.add(rule.parent)
+  })
+
+  if (applyParents.size === 0) {
+    return
+  }
+
+  for (let rule of applyParents) {
+    let nodeGroups = []
+    let lastGroup = []
+
+    for (let node of rule.nodes) {
+      if (node.type === 'atrule' && node.name === 'apply') {
+        if (lastGroup.length > 0) {
+          nodeGroups.push(lastGroup)
+          lastGroup = []
+        }
+        nodeGroups.push([node])
+      } else {
+        lastGroup.push(node)
+      }
+    }
+
+    if (lastGroup.length > 0) {
+      nodeGroups.push(lastGroup)
+    }
+
+    if (nodeGroups.length === 1) {
+      continue
+    }
+
+    for (let group of [...nodeGroups].reverse()) {
+      let clone = rule.clone({ nodes: [] })
+      clone.append(group)
+      rule.after(clone)
+    }
+
+    rule.remove()
+  }
+}
+
+export default function expandApplyAtRules() {
+  return (root) => {
+    partitionRules(root)
+  }
+}

src/lib/setupContextUtils.js

@@ -20,58 +20,6 @@ import log from '../util/log'
 import negateValue from '../util/negateValue'
 import isValidArbitraryValue from '../util/isValidArbitraryValue'
 
-function partitionRules(root) {
-  if (!root.walkAtRules) return [root]
-
-  let applyParents = new Set()
-  let rules = []
-
-  root.walkAtRules('apply', (rule) => {
-    applyParents.add(rule.parent)
-  })
-
-  if (applyParents.size === 0) {
-    rules.push(root)
-  }
-
-  for (let rule of applyParents) {
-    let nodeGroups = []
-    let lastGroup = []
-
-    for (let node of rule.nodes) {
-      if (node.type === 'atrule' && node.name === 'apply') {
-        if (lastGroup.length > 0) {
-          nodeGroups.push(lastGroup)
-          lastGroup = []
-        }
-        nodeGroups.push([node])
-      } else {
-        lastGroup.push(node)
-      }
-    }
-
-    if (lastGroup.length > 0) {
-      nodeGroups.push(lastGroup)
-    }
-
-    if (nodeGroups.length === 1) {
-      rules.push(rule)
-      continue
-    }
-
-    for (let group of [...nodeGroups].reverse()) {
-      let clone = rule.clone({ nodes: [] })
-      clone.append(group)
-      rules.unshift(clone)
-      rule.after(clone)
-    }
-
-    rule.remove()
-  }
-
-  return rules
-}
-
 function parseVariantFormatString(input) {
   if (input.includes('{')) {
     if (!isBalanced(input)) throw new Error(`Your { and } are unbalanced.`)
@@ -284,9 +232,7 @@ function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offs
           context.candidateRuleMap.set(identifier, [])
         }
 
-        context.candidateRuleMap
-          .get(identifier)
-          .push(...partitionRules(rule).map((rule) => [{ sort: offset, layer: 'user' }, rule]))
+        context.candidateRuleMap.get(identifier).push([{ sort: offset, layer: 'user' }, rule])
       }
     },
     addBase(base) {
@@ -300,7 +246,7 @@ function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offs
 
         context.candidateRuleMap
           .get(prefixedIdentifier)
-          .push(...partitionRules(rule).map((rule) => [{ sort: offset, layer: 'base' }, rule]))
+          .push([{ sort: offset, layer: 'base' }, rule])
       }
     },
     /**
@@ -321,12 +267,7 @@ function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offs
 
         context.candidateRuleMap
           .get(prefixedIdentifier)
-          .push(
-            ...partitionRules(rule).map((rule) => [
-              { sort: offsets.base++, layer: 'defaults' },
-              rule,
-            ])
-          )
+          .push([{ sort: offsets.base++, layer: 'defaults' }, rule])
       }
     },
     addComponents(components, options) {
@@ -348,12 +289,7 @@ function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offs
 
         context.candidateRuleMap
           .get(prefixedIdentifier)
-          .push(
-            ...partitionRules(rule).map((rule) => [
-              { sort: offsets.components++, layer: 'components', options },
-              rule,
-            ])
-          )
+          .push([{ sort: offsets.components++, layer: 'components', options }, rule])
       }
     },
     addUtilities(utilities, options) {
@@ -375,12 +311,7 @@ function buildPluginApi(tailwindConfig, context, { variantList, variantMap, offs
 
         context.candidateRuleMap
           .get(prefixedIdentifier)
-          .push(
-            ...partitionRules(rule).map((rule) => [
-              { sort: offsets.utilities++, layer: 'utilities', options },
-              rule,
-            ])
-          )
+          .push([{ sort: offsets.utilities++, layer: 'utilities', options }, rule])
       }
     },
     matchUtilities: function (utilities, options) {

src/processTailwindFeatures.js

@@ -6,6 +6,7 @@ import substituteScreenAtRules from './lib/substituteScreenAtRules'
 import resolveDefaultsAtRules from './lib/resolveDefaultsAtRules'
 import collapseAdjacentRules from './lib/collapseAdjacentRules'
 import collapseDuplicateDeclarations from './lib/collapseDuplicateDeclarations'
+import partitionApplyAtRules from './lib/partitionApplyAtRules'
 import detectNesting from './lib/detectNesting'
 import { createContext } from './lib/setupContextUtils'
 import { issueFlagNotices } from './featureFlags'
@@ -15,6 +16,7 @@ export default function processTailwindFeatures(setupContext) {
     let { tailwindDirectives, applyDirectives } = normalizeTailwindDirectives(root)
 
     detectNesting()(root, result)
+    partitionApplyAtRules()(root, result)
 
     let context = setupContext({
       tailwindDirectives,

tests/apply.test.js

@@ -1139,3 +1139,66 @@ it('apply does not emit defaults in isolated environments without optimizeUniver
     `)
   })
 })
+
+it('should work outside of layer', async () => {
+  let config = {
+    content: [{ raw: html`<div class="input-text"></div>` }],
+    corePlugins: { preflight: false },
+  }
+
+  let input = css`
+    .input-text {
+      @apply bg-white;
+      background-color: red;
+    }
+  `
+
+  let result
+  result = await run(input, config)
+
+  expect(result.css).toMatchFormattedCss(css`
+    .input-text {
+      --tw-bg-opacity: 1;
+      background-color: rgb(255 255 255 / var(--tw-bg-opacity));
+      background-color: red;
+    }
+  `)
+
+  result = await run(input, config)
+
+  expect(result.css).toMatchFormattedCss(css`
+    .input-text {
+      --tw-bg-opacity: 1;
+      background-color: rgb(255 255 255 / var(--tw-bg-opacity));
+      background-color: red;
+    }
+  `)
+})
+
+it('should work in layer', async () => {
+  let config = {
+    content: [{ raw: html`<div class="input-text"></div>` }],
+    corePlugins: { preflight: false },
+  }
+
+  let input = css`
+    @tailwind components;
+    @layer components {
+      .input-text {
+        @apply bg-white;
+        background-color: red;
+      }
+    }
+  `
+
+  await run(input, config)
+  const result = await run(input, config)
+
+  expect(result.css).toMatchFormattedCss(css`
+    .input-text {
+      --tw-bg-opacity: 1;
+      background-color: rgb(255 255 255 / var(--tw-bg-opacity));
+      background-color: red;
+    }
+  `)
+})