Rename buckets to layers, handle copying layer information to responsive variants

src/lib/purgeUnusedStyles.js

@@ -5,6 +5,40 @@ import chalk from 'chalk'
 import { log } from '../cli/utils'
 import * as emoji from '../cli/emoji'
 
+function convertLayersToControlComments(css) {
+  css.walkAtRules('layer', atRule => {
+    const layer = atRule.params
+    atRule.before(postcss.comment({ text: `tailwind start ${layer}` }))
+    atRule.before(atRule.nodes)
+    atRule.before(postcss.comment({ text: `tailwind end ${layer}` }))
+    atRule.remove()
+  })
+}
+
+function convertControlCommentsToPurgeIgnoreComments(config) {
+  return function(css) {
+    const mode = _.get(config, 'purge.mode', 'conservative')
+
+    if (mode === 'conservative') {
+      css.prepend(postcss.comment({ text: 'purgecss start ignore' }))
+      css.append(postcss.comment({ text: 'purgecss end ignore' }))
+
+      css.walkComments(comment => {
+        switch (comment.text.trim()) {
+          case 'tailwind start utilities':
+            comment.text = 'purgecss end ignore'
+            break
+          case 'tailwind end utilities':
+            comment.text = 'purgecss start ignore'
+            break
+          default:
+            break
+        }
+      })
+    }
+  }
+}
+
 function removeTailwindComments(css) {
   css.walkComments(comment => {
     switch (comment.text.trim()) {
@@ -28,7 +62,7 @@ export default function purgeUnusedUtilities(config) {
   )
 
   if (!purgeEnabled) {
-    return removeTailwindComments
+    return postcss([convertLayersToControlComments, removeTailwindComments])
   }
 
   // Skip if `purge: []` since that's part of the default config
@@ -52,29 +86,9 @@ export default function purgeUnusedUtilities(config) {
   }
 
   return postcss([
-    function(css) {
-      const mode = _.get(config, 'purge.mode', 'conservative')
-
-      if (mode === 'conservative') {
-        css.prepend(postcss.comment({ text: 'purgecss start ignore' }))
-        css.append(postcss.comment({ text: 'purgecss end ignore' }))
-
-        css.walkComments(comment => {
-          switch (comment.text.trim()) {
-            case 'tailwind start utilities':
-              comment.text = 'purgecss end ignore'
-              break
-            case 'tailwind end utilities':
-              comment.text = 'purgecss start ignore'
-              break
-            default:
-              break
-          }
-        })
-      }
-
-      removeTailwindComments(css)
-    },
+    convertLayersToControlComments,
+    convertControlCommentsToPurgeIgnoreComments(config),
+    removeTailwindComments,
     purgecss({
       content: Array.isArray(config.purge) ? config.purge : config.purge.content,
       defaultExtractor: content => {

src/lib/substituteResponsiveAtRules.js

@@ -4,8 +4,51 @@ import cloneNodes from '../util/cloneNodes'
 import buildMediaQuery from '../util/buildMediaQuery'
 import buildSelectorVariant from '../util/buildSelectorVariant'
 
+function isLayer(node) {
+  if (Array.isArray(node)) {
+    return node.length === 1 && isLayer(node[0])
+  }
+  return node.type === 'atrule' && node.name === 'layer'
+}
+
+function layerNodes(nodes) {
+  return isLayer(nodes) ? nodes[0].nodes : nodes
+}
+
 export default function(config) {
   return function(css) {
+    // Wrap any `responsive` rules with a copy of their parent `layer` to
+    // ensure the layer isn't lost when copying to the `screens` location.
+    css.walkAtRules('layer', layerAtRule => {
+      const layer = layerAtRule.params
+      layerAtRule.walkAtRules('responsive', responsiveAtRule => {
+        const nestedlayerAtRule = postcss.atRule({
+          name: 'layer',
+          params: layer,
+        })
+        nestedlayerAtRule.prepend(responsiveAtRule.nodes)
+        responsiveAtRule.removeAll()
+        responsiveAtRule.prepend(nestedlayerAtRule)
+      })
+    })
+
+    // Find any `responsive` rules with no parent `layer` (these only come
+    // from the user's CSS, Tailwind never generates things this way itself)
+    // and wrap them with a default `layer` of `utilities`.
+    css.walkAtRules('responsive', responsiveAtRule => {
+      const [node] = responsiveAtRule.nodes
+      if (node.type === 'atrule' && node.name === 'layer') {
+        return
+      }
+      const nestedlayerAtRule = postcss.atRule({
+        name: 'layer',
+        params: 'utilities',
+      })
+      nestedlayerAtRule.prepend(responsiveAtRule.nodes)
+      responsiveAtRule.removeAll()
+      responsiveAtRule.prepend(nestedlayerAtRule)
+    })
+
     const {
       theme: { screens },
       separator,
@@ -16,7 +59,16 @@ export default function(config) {
     css.walkAtRules('responsive', atRule => {
       const nodes = atRule.nodes
       responsiveRules.append(...cloneNodes(nodes))
-      atRule.before(nodes)
+
+      // If the parent is already a `layer` (this is true for anything coming from
+      // a plugin, including core plugins) we don't want to create a double nested
+      // layer, so only insert the layer children. If there is no parent layer,
+      // preserve the layer information when inserting the nodes.
+      if (isLayer(atRule.parent)) {
+        atRule.before(layerNodes(nodes))
+      } else {
+        atRule.before(nodes)
+      }
       atRule.remove()
     })
 

src/processTailwindFeatures.js

@@ -24,15 +24,6 @@ export default function(getConfig) {
       substituteResponsiveAtRules(config),
       substituteScreenAtRules(config),
       substituteClassApplyAtRules(config, processedPlugins.utilities),
-      function(css) {
-        css.walkAtRules('bucket', atRule => {
-          const bucket = atRule.params
-          atRule.before(postcss.comment({ text: `tailwind start ${bucket}` }))
-          atRule.before(atRule.nodes)
-          atRule.before(postcss.comment({ text: `tailwind end ${bucket}` }))
-          atRule.remove()
-        })
-      },
       purgeUnusedStyles(config),
     ]).process(css, { from: _.get(css, 'source.input.file') })
   }

src/util/processPlugins.js

@@ -28,11 +28,11 @@ function containsClass(value) {
   }).transformSync(value)
 }
 
-function wrapWithBucket(rules, bucket) {
+function wrapWithLayer(rules, layer) {
   return postcss
     .atRule({
-      name: 'bucket',
-      params: bucket,
+      name: 'layer',
+      params: layer,
     })
     .append(cloneNodes(Array.isArray(rules) ? rules : [rules]))
 }
@@ -119,7 +119,7 @@ export default function(plugins, config) {
         })
 
         pluginUtilities.push(
-          wrapWithVariants(wrapWithBucket(styles.nodes, 'utilities'), options.variants)
+          wrapWithLayer(wrapWithVariants(styles.nodes, options.variants), 'utilities')
         )
       },
       addComponents: (components, options) => {
@@ -138,7 +138,7 @@ export default function(plugins, config) {
         })
 
         pluginComponents.push(
-          wrapWithVariants(wrapWithBucket(styles.nodes, 'components'), options.variants)
+          wrapWithLayer(wrapWithVariants(styles.nodes, options.variants), 'components')
         )
       },
       addBase: baseStyles => {