shouldVisitChild: Check parent and child node previously deferred separately (#7043)

Author: Will Binns-Smith

packages/core/core/src/AssetGraph.js

@@ -301,17 +301,21 @@ export default class AssetGraph extends ContentGraph<AssetGraphNode> {
     ) {
       return true;
     }
-
-    let {sideEffects, canDefer = true} = childNode.value;
-    let dependency = node.value;
-    let previouslyDeferred = node.hasDeferred;
+    // Node types are proved above
+    let dependencyNode = node;
+    let assetGroupNode = childNode;
+
+    let {sideEffects, canDefer = true} = assetGroupNode.value;
+    let dependency = dependencyNode.value;
+    let dependencyPreviouslyDeferred = dependencyNode.hasDeferred;
+    let assetGroupPreviouslyDeferred = assetGroupNode.deferred;
     let defer = this.shouldDeferDependency(dependency, sideEffects, canDefer);
-    node.hasDeferred = defer;
-    childNode.deferred = defer;
+    dependencyNode.hasDeferred = defer;
+    assetGroupNode.deferred = defer;
 
-    if (!previouslyDeferred && defer) {
+    if (!dependencyPreviouslyDeferred && defer) {
       this.markParentsWithHasDeferred(nodeId);
-    } else if (previouslyDeferred && !defer) {
+    } else if (assetGroupPreviouslyDeferred && !defer) {
       this.unmarkParentsWithHasDeferred(childNodeId);
     }
 

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/index1.js

@@ -0,0 +1,3 @@
+import { barer } from './package';
+
+output = barer;

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/index2.js

@@ -0,0 +1,3 @@
+import { barer, foo } from './package';
+
+output = `${barer} ${foo}`;

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/index3.js

@@ -0,0 +1,3 @@
+import { barer, foo, bar } from './package';
+
+output = `${barer} ${foo} ${bar}`;

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/package/bar.js

@@ -0,0 +1 @@
+export const bar = 'bar';

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/package/barer.js

@@ -0,0 +1 @@
+export {bar as barer} from "./bar";

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/package/foo.js

@@ -0,0 +1 @@
+export const foo = 'foo';

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/package/index.js

@@ -0,0 +1,5 @@
+export {foo} from './foo';
+export {bar} from './bar';
+export {barer} from './barer';
+
+sideEffectNoop(module);

packages/core/integration-tests/test/integration/scope-hoisting/es6/unmarks-defer-for-assetgroup/package/package.json

@@ -0,0 +1,3 @@
+{
+  "sideEffects": ["index.js"]
+}

packages/core/integration-tests/test/scope-hoisting.js

@@ -6034,4 +6034,52 @@ describe('scope hoisting', function() {
       shouldDisableCache: false,
     });
   });
+
+  it('unmark an asset group as deferred when it becomes used', async function() {
+    let testDir = path.join(
+      __dirname,
+      'integration/scope-hoisting/es6/unmarks-defer-for-assetgroup',
+    );
+
+    await overlayFS.mkdirp(testDir);
+    await overlayFS.copyFile(
+      path.join(testDir, 'index1.js'),
+      path.join(testDir, 'index.js'),
+    );
+
+    let b = await bundle(path.join(testDir, 'index.js'), {
+      inputFS: overlayFS,
+      outputFS: overlayFS,
+      shouldDisableCache: true,
+    });
+
+    await run(b);
+
+    await overlayFS.copyFile(
+      path.join(testDir, 'index2.js'),
+      path.join(testDir, 'index.js'),
+    );
+
+    b = await bundle(path.join(testDir, 'index.js'), {
+      inputFS: overlayFS,
+      outputFS: overlayFS,
+      shouldDisableCache: false,
+    });
+
+    await run(b);
+
+    await overlayFS.copyFile(
+      path.join(testDir, 'index3.js'),
+      path.join(testDir, 'index.js'),
+    );
+
+    b = await bundle(path.join(testDir, 'index.js'), {
+      inputFS: overlayFS,
+      outputFS: overlayFS,
+      shouldDisableCache: false,
+    });
+
+    let output = await run(b);
+    assert.strictEqual(output, 'bar foo bar');
+  });
 });