Fix #2353 - retain empty manual chunks (#2362)

* fixes #2353

* minor refactoring

src/Graph.ts

@@ -445,7 +445,7 @@ export default class Graph {
 				//       exposed as an unresolvable export * (to a graph external export *,
 				//       either as a namespace import reexported or top-level export *)
 				//       should be made to be its own entry point module before chunking
-				const chunkList: Chunk[] = [];
+				let chunkList: Chunk[] = [];
 				if (!preserveModules) {
 					const chunkModules: { [entryHashSum: string]: Module[] } = {};
 					for (const module of orderedModules) {
@@ -482,12 +482,9 @@ export default class Graph {
 				}
 
 				// filter out empty dependencies
-				for (let i = 0; i < chunkList.length; i++) {
-					const chunk = chunkList[i];
-					if (chunk.isEmpty && !chunk.entryModule) {
-						chunkList.splice(i--, 1);
-					}
-				}
+				chunkList = chunkList.filter(
+					chunk => !chunk.isEmpty || chunk.entryModule || chunk.isManualChunk
+				);
 
 				// then go over and ensure all entry chunks export their variables
 				for (const chunk of chunkList) {

test/chunking-form/samples/manual-chunks-dynamic/_config.js

@@ -0,0 +1,10 @@
+module.exports = {
+	description: 'manual chunks to an empty dynamic chunk',
+	_single: true,
+	options: {
+		input: ['main.js'],
+		manualChunks: {
+			'dynamic': ['dynamic.js']
+		}
+	}
+};

test/chunking-form/samples/manual-chunks-dynamic/_expected/amd/dynamic-10698fc3.js

@@ -0,0 +1,5 @@
+define(function () { 'use strict';
+
+
+
+});

test/chunking-form/samples/manual-chunks-dynamic/_expected/amd/main.js

@@ -0,0 +1,5 @@
+define(['require'], function (require) { 'use strict';
+
+	new Promise(function (resolve, reject) { require(["./dynamic-10698fc3.js"], resolve, reject) });
+
+});

test/chunking-form/samples/manual-chunks-dynamic/_expected/cjs/dynamic-5ab72169.js

@@ -0,0 +1,2 @@
+'use strict';
+

test/chunking-form/samples/manual-chunks-dynamic/_expected/cjs/main.js

@@ -0,0 +1,3 @@
+'use strict';
+
+Promise.resolve(require("./dynamic-5ab72169.js"));

test/chunking-form/samples/manual-chunks-dynamic/_expected/es/dynamic-12dc935a.js

@@ -0,0 +1 @@
+

test/chunking-form/samples/manual-chunks-dynamic/_expected/es/main.js

@@ -0,0 +1 @@
+import("./dynamic-12dc935a.js");

test/chunking-form/samples/manual-chunks-dynamic/_expected/system/dynamic-e8bd5876.js

@@ -0,0 +1,10 @@
+System.register([], function (exports, module) {
+	'use strict';
+	return {
+		execute: function () {
+
+
+
+		}
+	};
+});

test/chunking-form/samples/manual-chunks-dynamic/_expected/system/main.js

@@ -0,0 +1,10 @@
+System.register([], function (exports, module) {
+	'use strict';
+	return {
+		execute: function () {
+
+			module.import("./dynamic-e8bd5876.js");
+
+		}
+	};
+});

test/chunking-form/samples/manual-chunks-dynamic/dynamic.js

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

test/chunking-form/samples/manual-chunks-dynamic/main.js

@@ -0,0 +1 @@
+import('./dynamic.js');