pure selectors mark all children pure

.github/workflows/nodejs.yml

@@ -23,7 +23,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        node-version: [lts/*]
+        node-version: ["lts/*"]
 
     runs-on: ${{ matrix.os }}
 
@@ -32,15 +32,17 @@ jobs:
       cancel-in-progress: true
 
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
         with:
           fetch-depth: 0
 
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v4
         with:
           node-version: ${{ matrix.node-version }}
+          architecture: "x64"
           cache: "yarn"
+          cache-dependency-path: "yarn.lock"
 
       - name: Install dependencies
         run: yarn --frozen-lockfile
@@ -54,7 +56,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest, windows-latest, macos-latest]
-        node-version: [10.x, 12.x, 14.x, 16.x, 18.x, 20.x]
+        node-version: ["10", "12", "14", "16", "18", "20"]
         webpack-version: [latest]
 
     runs-on: ${{ matrix.os }}
@@ -68,13 +70,15 @@ jobs:
         if: matrix.os == 'windows-latest'
         run: git config --global core.autocrlf input
 
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
 
       - name: Use Node.js ${{ matrix.node-version }}
-        uses: actions/setup-node@v3
+        uses: actions/setup-node@v4
         with:
-          node-version: ${{ matrix.node-version }}
+          node-version: "${{ matrix.node-version }}"
+          architecture: "x64"
           cache: "yarn"
+          cache-dependency-path: "yarn.lock"
 
       - name: Install dependencies
         run: yarn --frozen-lockfile

src/index.js

@@ -590,6 +590,7 @@ module.exports = (options = {}) => {
             }
           });
 
+          const localRules = new Set();
           root.walkRules((rule) => {
             if (
               rule.parent &&
@@ -605,13 +606,23 @@ module.exports = (options = {}) => {
             context.options = options;
             context.localAliasMap = localAliasMap;
 
-            if (pureMode && context.hasPureGlobals) {
+            if (
+              pureMode &&
+              context.hasPureGlobals &&
+              !localRules.has(rule.parent)
+            ) {
               throw rule.error(
                 'Selector "' +
                   rule.selector +
                   '" is not pure ' +
                   "(pure selectors must contain at least one local class or id)"
               );
+            } else {
+              // Once a parent is pure all children are also pure
+              // For example the span inside this .foo is also pure
+              // although it is not local itself:
+              // .foo { span { color: red; } }
+              localRules.add(rule);
             }
 
             rule.selector = context.selector;

test/index.test.js

@@ -868,6 +868,30 @@ const tests = [
     options: { mode: "pure" },
     error: /is not pure/,
   },
+  {
+    name: "consider nonlocal children of a pure parent as pure",
+    input: ".foo { span { a_value: some-value; } }",
+    options: { mode: "pure" },
+    expected: ":local(.foo) { span { a_value: some-value; } }",
+  },
+  {
+    name: "consider nested nonlocal children of a pure parent as pure",
+    input: ".foo { span { a { a_value: some-value; } } }",
+    options: { mode: "pure" },
+    expected: ":local(.foo) { span { a { a_value: some-value; } } }",
+  },
+  {
+    name: "throw on mixed parents",
+    input: ".foo, html { span { a_value: some-value; } }",
+    options: { mode: "pure" },
+    error: /is not pure/,
+  },
+  {
+    name: "throw on global styles with a local selector",
+    input: `html { a_value: some-value; .foo { a_value: some-value; } }`,
+    options: { mode: "pure" },
+    error: /is not pure/,
+  },
   {
     name: "css nesting",
     input: `