From aac43687fd5759026dc5c731867e4df163c79502 Mon Sep 17 00:00:00 2001
From: Tobias Koppers <tobias.koppers@googlemail.com>
Date: Thu, 26 Jul 2018 16:51:02 +0200
Subject: [PATCH] fix case where empty chunkgroups cause nested chunkgroups to
 vanish

---
 lib/Compilation.js                         |  8 ++++++++
 test/cases/chunks/nested-in-empty/a.js     |  0
 test/cases/chunks/nested-in-empty/b.js     |  1 +
 test/cases/chunks/nested-in-empty/index.js | 13 +++++++++++++
 4 files changed, 22 insertions(+)
 create mode 100644 test/cases/chunks/nested-in-empty/a.js
 create mode 100644 test/cases/chunks/nested-in-empty/b.js
 create mode 100644 test/cases/chunks/nested-in-empty/index.js

diff --git a/lib/Compilation.js b/lib/Compilation.js
index 4171e60a920..03f62b6e057 100644
--- a/lib/Compilation.js
+++ b/lib/Compilation.js
@@ -1572,6 +1572,9 @@ class Compilation extends Tapable {
 		/** @type {Map<DependenciesBlock, ChunkGroup>} */
 		const blockChunkGroups = new Map();
 
+		/** @type {Set<DependenciesBlock>} */
+		const blocksWithNestedBlocks = new Set();
+
 		const ADD_AND_ENTER_MODULE = 0;
 		const ENTER_MODULE = 1;
 		const PROCESS_BLOCK = 2;
@@ -1731,6 +1734,10 @@ class Compilation extends Tapable {
 
 						// Traverse all Blocks
 						iterationOfArrayCallback(blockInfo.blocks, iteratorBlock);
+
+						if (blockInfo.blocks.length > 0 && module !== block) {
+							blocksWithNestedBlocks.add(block);
+						}
 						break;
 					}
 					case LEAVE_MODULE: {
@@ -1792,6 +1799,7 @@ class Compilation extends Tapable {
 		 */
 		const filterFn = dep => {
 			const depChunkGroup = dep.chunkGroup;
+			if (blocksWithNestedBlocks.has(dep.block)) return true;
 			if (areModulesAvailable(depChunkGroup, newAvailableModules)) return false; // break all modules are already available
 			return true;
 		};
diff --git a/test/cases/chunks/nested-in-empty/a.js b/test/cases/chunks/nested-in-empty/a.js
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/test/cases/chunks/nested-in-empty/b.js b/test/cases/chunks/nested-in-empty/b.js
new file mode 100644
index 00000000000..888cae37af9
--- /dev/null
+++ b/test/cases/chunks/nested-in-empty/b.js
@@ -0,0 +1 @@
+module.exports = 42;
diff --git a/test/cases/chunks/nested-in-empty/index.js b/test/cases/chunks/nested-in-empty/index.js
new file mode 100644
index 00000000000..968e02795ca
--- /dev/null
+++ b/test/cases/chunks/nested-in-empty/index.js
@@ -0,0 +1,13 @@
+it("should include a chunk nested in an empty chunk", (done) => {
+	require.ensure(["./a"], () => {
+		require.ensure([], () => {
+			require.ensure(["./a"], () => {
+				require.ensure([], () => {
+					const b = require("./b");
+					expect(b).toBe(42);
+					done();
+				});
+			});
+		});
+	});
+});