fix: ESM library generation (#19386)

lib/config/normalization.js

@@ -346,6 +346,7 @@ const getNormalizedWebpackOptions = config => ({
 			importFunctionName: output.importFunctionName,
 			importMetaName: output.importMetaName,
 			scriptType: output.scriptType,
+			// TODO webpack6 remove `libraryTarget`/`auxiliaryComment`/`amdContainer`/etc in favor of the `library` option
 			library: libraryBase && {
 				type:
 					output.libraryTarget !== undefined

lib/library/EnableLibraryPlugin.js

@@ -80,7 +80,8 @@ class EnableLibraryPlugin {
 				new ExportPropertyTemplatePlugin({
 					type,
 					nsObjectUsed: !["module", "modern-module"].includes(type),
-					runtimeExportsUsed: type !== "modern-module"
+					runtimeExportsUsed: !["module", "modern-module"].includes(type),
+					renderStartupUsed: !["module", "modern-module"].includes(type)
 				}).apply(compiler);
 			};
 			switch (type) {
@@ -252,7 +253,8 @@ class EnableLibraryPlugin {
 					}).apply(compiler);
 					break;
 				}
-				case "module": {
+				case "module":
+				case "modern-module": {
 					enableExportProperty();
 					const ModuleLibraryPlugin = require("./ModuleLibraryPlugin");
 					new ModuleLibraryPlugin({
@@ -260,14 +262,6 @@ class EnableLibraryPlugin {
 					}).apply(compiler);
 					break;
 				}
-				case "modern-module": {
-					enableExportProperty();
-					const ModernModuleLibraryPlugin = require("./ModernModuleLibraryPlugin");
-					new ModernModuleLibraryPlugin({
-						type
-					}).apply(compiler);
-					break;
-				}
 				default:
 					throw new Error(`Unsupported library type ${type}.
 Plugins which provide custom library types must call EnableLibraryPlugin.setEnabled(compiler, type) to disable this error.`);

lib/library/ExportPropertyLibraryPlugin.js

@@ -31,6 +31,7 @@ const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");
  * @property {LibraryType} type
  * @property {boolean} nsObjectUsed the namespace object is used
  * @property {boolean} runtimeExportsUsed runtime exports are used
+ * @property {boolean} renderStartupUsed render startup is used
  */
 /**
  * @typedef {ExportPropertyLibraryPluginParsed} T
@@ -40,13 +41,14 @@ class ExportPropertyLibraryPlugin extends AbstractLibraryPlugin {
 	/**
 	 * @param {ExportPropertyLibraryPluginOptions} options options
 	 */
-	constructor({ type, nsObjectUsed, runtimeExportsUsed }) {
+	constructor({ type, nsObjectUsed, runtimeExportsUsed, renderStartupUsed }) {
 		super({
 			pluginName: "ExportPropertyLibraryPlugin",
 			type
 		});
 		this.nsObjectUsed = nsObjectUsed;
 		this.runtimeExportsUsed = runtimeExportsUsed;
+		this.renderStartupUsed = renderStartupUsed;
 	}
 
 	/**
@@ -109,6 +111,7 @@ class ExportPropertyLibraryPlugin extends AbstractLibraryPlugin {
 	 * @returns {Source} source with library export
 	 */
 	renderStartup(source, module, renderContext, { options }) {
+		if (!this.renderStartupUsed) return source;
 		if (!options.export) return source;
 		const postfix = `${RuntimeGlobals.exports} = ${
 			RuntimeGlobals.exports

lib/library/ModernModuleLibraryPlugin.js

@@ -1,157 +0,0 @@
-/*
-	MIT License http://www.opensource.org/licenses/mit-license.php
-	Author Tobias Koppers @sokra
-*/
-
-"use strict";
-
-const { ConcatSource } = require("webpack-sources");
-const ConcatenatedModule = require("../optimize/ConcatenatedModule");
-const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");
-
-/** @typedef {import("webpack-sources").Source} Source */
-/** @typedef {import("../../declarations/WebpackOptions").LibraryOptions} LibraryOptions */
-/** @typedef {import("../../declarations/WebpackOptions").LibraryType} LibraryType */
-/** @typedef {import("../Chunk")} Chunk */
-/** @typedef {import("../Compilation").ChunkHashContext} ChunkHashContext */
-/** @typedef {import("../Compiler")} Compiler */
-/** @typedef {import("../Module")} Module */
-/** @typedef {import("../Module").BuildMeta} BuildMeta */
-/** @typedef {import("../javascript/JavascriptModulesPlugin").StartupRenderContext} StartupRenderContext */
-/** @typedef {import("../util/Hash")} Hash */
-/** @template T @typedef {import("./AbstractLibraryPlugin").LibraryContext<T>} LibraryContext<T> */
-
-/**
- * @typedef {object} ModernModuleLibraryPluginOptions
- * @property {LibraryType} type
- */
-
-/**
- * @typedef {object} ModernModuleLibraryPluginParsed
- * @property {string} name
- */
-
-/**
- * @typedef {ModernModuleLibraryPluginParsed} T
- * @extends {AbstractLibraryPlugin<ModernModuleLibraryPluginParsed>}
- */
-class ModernModuleLibraryPlugin extends AbstractLibraryPlugin {
-	/**
-	 * Apply the plugin
-	 * @param {Compiler} compiler the compiler instance
-	 * @returns {void}
-	 */
-	apply(compiler) {
-		super.apply(compiler);
-
-		compiler.hooks.compilation.tap("ModernModuleLibraryPlugin", compilation => {
-			const { exportsDefinitions } =
-				ConcatenatedModule.getCompilationHooks(compilation);
-			exportsDefinitions.tap("ModernModuleLibraryPlugin", () => true);
-		});
-	}
-
-	/**
-	 * @param {ModernModuleLibraryPluginOptions} options the plugin options
-	 */
-	constructor(options) {
-		super({
-			pluginName: "ModernModuleLibraryPlugin",
-			type: options.type
-		});
-	}
-
-	/**
-	 * @param {LibraryOptions} library normalized library option
-	 * @returns {T | false} preprocess as needed by overriding
-	 */
-	parseOptions(library) {
-		const { name } = library;
-		if (name) {
-			throw new Error(
-				`Library name must be unset. ${AbstractLibraryPlugin.COMMON_LIBRARY_NAME_MESSAGE}`
-			);
-		}
-		const _name = /** @type {string} */ (name);
-		return {
-			name: _name
-		};
-	}
-
-	/**
-	 * @param {Source} source source
-	 * @param {Module} module module
-	 * @param {StartupRenderContext} renderContext render context
-	 * @param {LibraryContext<T>} libraryContext context
-	 * @returns {Source} source with library export
-	 */
-	renderStartup(
-		source,
-		module,
-		{ moduleGraph, chunk },
-		{ options, compilation }
-	) {
-		const result = new ConcatSource(source);
-		const exportsInfo = moduleGraph.getExportsInfo(module);
-		const definitions =
-			/** @type {BuildMeta} */
-			(module.buildMeta).exportsFinalName;
-		const shortHandedExports = [];
-		const exports = [];
-
-		for (const exportInfo of exportsInfo.orderedExports) {
-			let shouldContinue = false;
-			const reexport = exportInfo.findTarget(moduleGraph, _m => true);
-
-			if (reexport) {
-				const exp = moduleGraph.getExportsInfo(reexport.module);
-
-				for (const reexportInfo of exp.orderedExports) {
-					if (
-						reexportInfo.provided === false &&
-						reexportInfo.name === /** @type {string[]} */ (reexport.export)[0]
-					) {
-						shouldContinue = true;
-					}
-				}
-			}
-
-			if (shouldContinue) continue;
-
-			const webpackExportsProperty = exportInfo.getUsedName(
-				exportInfo.name,
-				chunk.runtime
-			);
-			const finalName =
-				definitions &&
-				definitions[
-					/** @type {string} */
-					(webpackExportsProperty)
-				];
-
-			if (finalName && (finalName.includes(".") || finalName.includes("["))) {
-				exports.push([exportInfo.name, finalName]);
-			} else {
-				shortHandedExports.push(
-					finalName === exportInfo.name
-						? finalName
-						: `${finalName} as ${exportInfo.name}`
-				);
-			}
-		}
-
-		if (shortHandedExports.length > 0) {
-			result.add(`export { ${shortHandedExports.join(", ")} };\n`);
-		}
-
-		for (const [exportName, final] of exports) {
-			result.add(
-				`export ${compilation.outputOptions.environment.const ? "const" : "var"} ${exportName} = ${final};\n`
-			);
-		}
-
-		return result;
-	}
-}
-
-module.exports = ModernModuleLibraryPlugin;

lib/library/ModuleLibraryPlugin.js

@@ -8,6 +8,7 @@
 const { ConcatSource } = require("webpack-sources");
 const RuntimeGlobals = require("../RuntimeGlobals");
 const Template = require("../Template");
+const ConcatenatedModule = require("../optimize/ConcatenatedModule");
 const propertyAccess = require("../util/propertyAccess");
 const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");
 
@@ -18,9 +19,14 @@ const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");
 /** @typedef {import("../Compilation").ChunkHashContext} ChunkHashContext */
 /** @typedef {import("../Compiler")} Compiler */
 /** @typedef {import("../Module")} Module */
+/** @typedef {import("../Module").BuildMeta} BuildMeta */
 /** @typedef {import("../javascript/JavascriptModulesPlugin").StartupRenderContext} StartupRenderContext */
 /** @typedef {import("../util/Hash")} Hash */
-/** @template T @typedef {import("./AbstractLibraryPlugin").LibraryContext<T>} LibraryContext<T> */
+
+/**
+ * @template T
+ * @typedef {import("./AbstractLibraryPlugin").LibraryContext<T>} LibraryContext<T>
+ */
 
 /**
  * @typedef {object} ModuleLibraryPluginOptions
@@ -30,6 +36,7 @@ const AbstractLibraryPlugin = require("./AbstractLibraryPlugin");
 /**
  * @typedef {object} ModuleLibraryPluginParsed
  * @property {string} name
+ * @property {string | string[]=} export
  */
 
 /**
@@ -47,6 +54,45 @@ class ModuleLibraryPlugin extends AbstractLibraryPlugin {
 		});
 	}
 
+	/**
+	 * Apply the plugin
+	 * @param {Compiler} compiler the compiler instance
+	 * @returns {void}
+	 */
+	apply(compiler) {
+		super.apply(compiler);
+
+		compiler.hooks.compilation.tap("ModernModuleLibraryPlugin", compilation => {
+			const { exportsDefinitions } =
+				ConcatenatedModule.getCompilationHooks(compilation);
+			exportsDefinitions.tap(
+				"ModernModuleLibraryPlugin",
+				(definitions, module) => {
+					// If we have connections not all modules were concatenated, so we need the wrapper
+					const connections =
+						compilation.moduleGraph.getIncomingConnections(module);
+
+					for (const connection of connections) {
+						if (connection.originModule) {
+							return false;
+						}
+					}
+
+					// Runtime and splitting chunks now requires the wrapper too
+					for (const chunk of compilation.chunkGraph.getModuleChunksIterable(
+						module
+					)) {
+						if (!chunk.hasRuntime()) {
+							return false;
+						}
+					}
+
+					return true;
+				}
+			);
+		});
+	}
+
 	/**
 	 * @param {LibraryOptions} library normalized library option
 	 * @returns {T | false} preprocess as needed by overriding
@@ -60,7 +106,8 @@ class ModuleLibraryPlugin extends AbstractLibraryPlugin {
 		}
 		const _name = /** @type {string} */ (name);
 		return {
-			name: _name
+			name: _name,
+			export: library.export
 		};
 	}
 
@@ -78,30 +125,89 @@ class ModuleLibraryPlugin extends AbstractLibraryPlugin {
 		{ options, compilation }
 	) {
 		const result = new ConcatSource(source);
-		const exportsInfo = moduleGraph.getExportsInfo(module);
+		const exportsInfos = options.export
+			? [
+					moduleGraph.getExportInfo(
+						module,
+						Array.isArray(options.export) ? options.export[0] : options.export
+					)
+				]
+			: moduleGraph.getExportsInfo(module).orderedExports;
+		const definitions =
+			/** @type {BuildMeta} */
+			(module.buildMeta).exportsFinalName || {};
+		const shortHandedExports = [];
 		const exports = [];
 		const isAsync = moduleGraph.isAsync(module);
+
 		if (isAsync) {
 			result.add(
 				`${RuntimeGlobals.exports} = await ${RuntimeGlobals.exports};\n`
 			);
 		}
-		for (const exportInfo of exportsInfo.orderedExports) {
+
+		for (const exportInfo of exportsInfos) {
 			if (!exportInfo.provided) continue;
-			const varName = `${RuntimeGlobals.exports}${Template.toIdentifier(
-				exportInfo.name
-			)}`;
+
+			let shouldContinue = false;
+
+			const reexport = exportInfo.findTarget(moduleGraph, _m => true);
+
+			if (reexport) {
+				const exp = moduleGraph.getExportsInfo(reexport.module);
+
+				for (const reexportInfo of exp.orderedExports) {
+					if (
+						reexportInfo.provided === false &&
+						reexportInfo.name === /** @type {string[]} */ (reexport.export)[0]
+					) {
+						shouldContinue = true;
+					}
+				}
+			}
+
+			if (shouldContinue) continue;
+
+			const webpackExportsProperty = exportInfo.getUsedName(
+				exportInfo.name,
+				chunk.runtime
+			);
+			const definition =
+				definitions[/** @type {string} */ (webpackExportsProperty)];
+			const finalName =
+				definition ||
+				`${RuntimeGlobals.exports}${Template.toIdentifier(exportInfo.name)}`;
+
+			if (!definition) {
 				result.add(
-				`var ${varName} = ${RuntimeGlobals.exports}${propertyAccess([
+					`var ${finalName} = ${RuntimeGlobals.exports}${propertyAccess([
 						/** @type {string} */
 						(exportInfo.getUsedName(exportInfo.name, chunk.runtime))
-				])};\n`
+					])}\n`
 				);
-			exports.push(`${varName} as ${exportInfo.name}`);
 			}
-		if (exports.length > 0) {
-			result.add(`export { ${exports.join(", ")} };\n`);
+
+			if (finalName && (finalName.includes(".") || finalName.includes("["))) {
+				exports.push([exportInfo.name, finalName]);
+			} else {
+				shortHandedExports.push(
+					definition && finalName === exportInfo.name
+						? finalName
+						: `${finalName} as ${exportInfo.name}`
+				);
 			}
+		}
+
+		if (shortHandedExports.length > 0) {
+			result.add(`export { ${shortHandedExports.join(", ")} };\n`);
+		}
+
+		for (const [exportName, final] of exports) {
+			result.add(
+				`export ${compilation.outputOptions.environment.const ? "const" : "var"} ${exportName} = ${final};\n`
+			);
+		}
+
 		return result;
 	}
 }

lib/optimize/ConcatenatedModule.js

@@ -603,7 +603,7 @@ const getFinalName = (
 
 /**
  * @typedef {object} ConcatenateModuleHooks
- * @property {SyncBailHook<[Record<string, string>], boolean | void>} exportsDefinitions
+ * @property {SyncBailHook<[Record<string, string>, ConcatenatedModule], boolean | void>} exportsDefinitions
  */
 
 /** @type {WeakMap<Compilation, ConcatenateModuleHooks>} */
@@ -650,7 +650,7 @@ class ConcatenatedModule extends Module {
 		let hooks = compilationHooksMap.get(compilation);
 		if (hooks === undefined) {
 			hooks = {
-				exportsDefinitions: new SyncBailHook(["definitions"])
+				exportsDefinitions: new SyncBailHook(["definitions", "module"])
 			};
 			compilationHooksMap.set(compilation, hooks);
 		}
@@ -1488,7 +1488,8 @@ class ConcatenatedModule extends Module {
 		// define exports
 		if (exportsMap.size > 0) {
 			const { exportsDefinitions } = ConcatenatedModule.getCompilationHooks(
-				/** @type {Compilation} */ (this.compilation)
+				/** @type {Compilation} */
+				(this.compilation)
 			);
 
 			const definitions = [];
@@ -1499,8 +1500,11 @@ class ConcatenatedModule extends Module {
 					)}`
 				);
 			}
-			const shouldSkipRenderDefinitions =
-				exportsDefinitions.call(exportsFinalName);
+
+			const shouldSkipRenderDefinitions = exportsDefinitions.call(
+				exportsFinalName,
+				this
+			);
 
 			if (!shouldSkipRenderDefinitions) {
 				runtimeRequirements.add(RuntimeGlobals.exports);

test/configCases/library/0-create-library/index-async.js

@@ -0,0 +1,14 @@
+export * from "./a";
+export default "default-value";
+export var b = "b";
+export { default as external } from "external";
+export * from "external-named";
+
+const test = await 1;
+
+var module = "should not conflict",
+	define = "should not conflict",
+	require = "should not conflict",
+	exports = "should not conflict",
+	globalName = "should not conflict";
+console.log.bind(console, module, define, require, exports, globalName);

test/configCases/library/0-create-library/webpack.config.js

@@ -1,13 +1,16 @@
 const path = require("path");
 const webpack = require("../../../../");
+const supportsAsync = require("../../../helpers/supportsAsync");
 
 /** @type {(env: any, options: any) => import("../../../../").Configuration[]} */
 module.exports = (env, { testPath }) => [
 	{
 		output: {
-			uniqueName: "esm",
-			filename: "esm.js",
-			libraryTarget: "module"
+			uniqueName: "modern-module",
+			filename: "modern-module.js",
+			library: {
+				type: "modern-module"
+			}
 		},
 		target: "node14",
 		resolve: {
@@ -22,9 +25,11 @@ module.exports = (env, { testPath }) => [
 	},
 	{
 		output: {
-			uniqueName: "modern-module",
-			filename: "modern-module.js",
-			libraryTarget: "modern-module"
+			uniqueName: "esm",
+			filename: "esm.js",
+			library: {
+				type: "module"
+			}
 		},
 		target: "node14",
 		resolve: {
@@ -37,11 +42,105 @@ module.exports = (env, { testPath }) => [
 			outputModule: true
 		}
 	},
+	{
+		output: {
+			uniqueName: "esm-export",
+			filename: "esm-export.js",
+			library: {
+				type: "module",
+				export: ["a"]
+			}
+		},
+		target: "node14",
+		resolve: {
+			alias: {
+				external: "./non-external",
+				"external-named": "./non-external-named"
+			}
+		},
+		experiments: {
+			outputModule: true
+		}
+	},
+	...(supportsAsync()
+		? [
+				{
+					entry: "./index-async.js",
+					output: {
+						uniqueName: "esm-async",
+						filename: "esm-async.js",
+						library: {
+							type: "module"
+						}
+					},
+					optimization: {
+						concatenateModules: true
+					},
+					target: "node14",
+					resolve: {
+						alias: {
+							external: "./non-external",
+							"external-named": "./non-external-named"
+						}
+					},
+					experiments: {
+						outputModule: true
+					}
+				},
+				{
+					entry: "./index-async.js",
+					output: {
+						uniqueName: "esm-async-no-concatenate-modules",
+						filename: "esm-async-no-concatenate-modules.js",
+						library: {
+							type: "module"
+						}
+					},
+					optimization: {
+						concatenateModules: false
+					},
+					resolve: {
+						alias: {
+							external: "./non-external",
+							"external-named": "./non-external-named"
+						}
+					},
+					experiments: {
+						outputModule: true
+					}
+				}
+			]
+		: []),
+	{
+		output: {
+			uniqueName: "esm-export-no-concatenate-modules",
+			filename: "esm-export-no-concatenate-modules.js",
+			library: {
+				type: "module",
+				export: ["a"]
+			}
+		},
+		target: "node14",
+		optimization: {
+			concatenateModules: false
+		},
+		resolve: {
+			alias: {
+				external: "./non-external",
+				"external-named": "./non-external-named"
+			}
+		},
+		experiments: {
+			outputModule: true
+		}
+	},
 	{
 		output: {
 			uniqueName: "esm-runtimeChunk",
 			filename: "esm-runtimeChunk/[name].js",
-			libraryTarget: "module"
+			library: {
+				type: "module"
+			}
 		},
 		target: "node14",
 		resolve: {
@@ -57,11 +156,92 @@ module.exports = (env, { testPath }) => [
 			outputModule: true
 		}
 	},
+	{
+		output: {
+			uniqueName: "esm-runtimeChunk-concatenateModules",
+			filename: "esm-runtimeChunk-concatenateModules/[name].js",
+			library: {
+				type: "module"
+			}
+		},
+		target: "node14",
+		resolve: {
+			alias: {
+				external: "./non-external",
+				"external-named": "./non-external-named"
+			}
+		},
+		optimization: {
+			runtimeChunk: "single",
+			concatenateModules: true
+		},
+		experiments: {
+			outputModule: true
+		}
+	},
+	{
+		output: {
+			uniqueName: "esm-runtimeChunk-no-concatenateModules",
+			filename: "esm-runtimeChunk-no-concatenateModules/[name].js",
+			library: {
+				type: "module"
+			}
+		},
+		target: "node14",
+		resolve: {
+			alias: {
+				external: "./non-external",
+				"external-named": "./non-external-named"
+			}
+		},
+		optimization: {
+			runtimeChunk: "single",
+			concatenateModules: false
+		},
+		experiments: {
+			outputModule: true
+		}
+	},
+	{
+		output: {
+			uniqueName: "esm-runtimeChunk-concatenateModules-splitChunks",
+			filename: "esm-runtimeChunk-concatenateModules-splitChunks/[name].js",
+			library: {
+				type: "module"
+			}
+		},
+		target: "node14",
+		resolve: {
+			alias: {
+				external: "./non-external",
+				"external-named": "./non-external-named"
+			}
+		},
+		optimization: {
+			runtimeChunk: "single",
+			concatenateModules: true,
+			splitChunks: {
+				cacheGroups: {
+					module: {
+						test: /a\.js$/,
+						chunks: "all",
+						enforce: true,
+						reuseExistingChunk: true
+					}
+				}
+			}
+		},
+		experiments: {
+			outputModule: true
+		}
+	},
 	{
 		output: {
 			uniqueName: "commonjs",
 			filename: "commonjs.js",
-			libraryTarget: "commonjs",
+			library: {
+				type: "commonjs"
+			},
 			iife: false
 		},
 		resolve: {
@@ -75,7 +255,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs-iife",
 			filename: "commonjs-iife.js",
-			libraryTarget: "commonjs",
+			library: {
+				type: "commonjs"
+			},
 			iife: true
 		},
 		resolve: {
@@ -89,7 +271,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "amd",
 			filename: "amd.js",
-			libraryTarget: "amd",
+			library: {
+				type: "amd"
+			},
 			iife: false
 		},
 		resolve: {
@@ -103,7 +287,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "amd-iife",
 			filename: "amd-iife.js",
-			libraryTarget: "amd",
+			library: {
+				type: "amd"
+			},
 			iife: true
 		},
 		resolve: {
@@ -117,7 +303,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "amd-runtimeChunk",
 			filename: "amd-runtimeChunk/[name].js",
-			libraryTarget: "amd",
+			library: {
+				type: "amd"
+			},
 			globalObject: "global",
 			iife: false
 		},
@@ -136,7 +324,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "amd-iife-runtimeChunk",
 			filename: "amd-iife-runtimeChunk/[name].js",
-			libraryTarget: "amd",
+			library: {
+				type: "amd"
+			},
 			globalObject: "global",
 			iife: true
 		},
@@ -155,7 +345,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "umd",
 			filename: "umd.js",
-			libraryTarget: "umd"
+			library: {
+				type: "umd"
+			}
 		},
 		resolve: {
 			alias: {
@@ -218,8 +410,10 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "umd-default",
 			filename: "umd-default.js",
-			libraryTarget: "umd",
-			libraryExport: "default"
+			library: {
+				type: "umd",
+				export: "default"
+			}
 		},
 		resolve: {
 			alias: {
@@ -232,7 +426,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "this",
 			filename: "this.js",
-			libraryTarget: "this",
+			library: {
+				type: "this"
+			},
 			iife: false
 		},
 		resolve: {
@@ -246,7 +442,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "this-iife",
 			filename: "this-iife.js",
-			libraryTarget: "this",
+			library: {
+				type: "this"
+			},
 			iife: true
 		},
 		resolve: {
@@ -301,8 +499,10 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs-nested",
 			filename: "commonjs-nested.js",
-			libraryTarget: "commonjs",
-			libraryExport: "NS",
+			library: {
+				type: "commonjs",
+				export: "NS"
+			},
 			iife: false
 		},
 		resolve: {
@@ -317,8 +517,10 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs-nested-iife",
 			filename: "commonjs-nested-iife.js",
-			libraryTarget: "commonjs",
-			libraryExport: "NS",
+			library: {
+				type: "commonjs",
+				export: "NS"
+			},
 			iife: true
 		},
 		resolve: {
@@ -332,7 +534,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-external",
 			filename: "commonjs2-external.js",
-			libraryTarget: "commonjs2",
+			library: {
+				type: "commonjs2"
+			},
 			iife: false
 		},
 		externals: ["external", "external-named"]
@@ -341,7 +545,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-external-no-concat",
 			filename: "commonjs2-external-no-concat.js",
-			libraryTarget: "commonjs2",
+			library: {
+				type: "commonjs2"
+			},
 			iife: false
 		},
 		optimization: {
@@ -353,7 +559,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-iife-external",
 			filename: "commonjs2-iife-external.js",
-			libraryTarget: "commonjs2",
+			library: {
+				type: "commonjs2"
+			},
 			iife: true
 		},
 		externals: ["external", "external-named"]
@@ -363,7 +571,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-external-eval",
 			filename: "commonjs2-external-eval.js",
-			libraryTarget: "commonjs2"
+			library: {
+				type: "commonjs2"
+			}
 		},
 		externals: ["external", "external-named"]
 	},
@@ -372,7 +582,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-external-eval-source-map",
 			filename: "commonjs2-external-eval-source-map.js",
-			libraryTarget: "commonjs2"
+			library: {
+				type: "commonjs2"
+			}
 		},
 		devtool: "eval-source-map",
 		externals: ["external", "external-named"]
@@ -381,7 +593,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs-static-external",
 			filename: "commonjs-static-external.js",
-			libraryTarget: "commonjs-static",
+			library: {
+				type: "commonjs-static"
+			},
 			iife: false
 		},
 		externals: ["external", "external-named"]
@@ -391,7 +605,9 @@ module.exports = (env, { testPath }) => [
 			uniqueName: "index",
 			filename: "index.js",
 			path: path.resolve(testPath, "commonjs2-split-chunks"),
-			libraryTarget: "commonjs2"
+			library: {
+				type: "commonjs2"
+			}
 		},
 		target: "node",
 		optimization: {
@@ -417,7 +633,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-runtimeChunk",
 			filename: "commonjs2-runtimeChunk/[name].js",
-			libraryTarget: "commonjs2",
+			library: {
+				type: "commonjs2"
+			},
 			iife: false
 		},
 		resolve: {
@@ -434,7 +652,9 @@ module.exports = (env, { testPath }) => [
 		output: {
 			uniqueName: "commonjs2-iife-runtimeChunk",
 			filename: "commonjs2-iife-runtimeChunk/[name].js",
-			libraryTarget: "commonjs2",
+			library: {
+				type: "commonjs2"
+			},
 			iife: true
 		},
 		resolve: {

test/configCases/library/1-use-library/module-export-test.js

@@ -0,0 +1,5 @@
+import * as mod from "library";
+
+it("should tree-shake other exports from library (" + NAME + ") and export only 'a'", function() {
+	expect(mod).toMatchObject({ a: "a" });
+});

test/configCases/library/1-use-library/webpack.config.js

@@ -3,21 +3,10 @@
 
 const webpack = require("../../../../");
 const path = require("path");
+const supportsAsync = require("../../../helpers/supportsAsync");
 
 /** @type {(env: any, options: any) => import("../../../../").Configuration[]} */
 module.exports = (env, { testPath }) => [
-	{
-		resolve: {
-			alias: {
-				library: path.resolve(testPath, "../0-create-library/esm.js")
-			}
-		},
-		plugins: [
-			new webpack.DefinePlugin({
-				NAME: JSON.stringify("esm")
-			})
-		]
-	},
 	{
 		entry: "./default-test-modern-module.js",
 		optimization: {
@@ -57,6 +46,81 @@ module.exports = (env, { testPath }) => [
 			}
 		]
 	},
+	{
+		resolve: {
+			alias: {
+				library: path.resolve(testPath, "../0-create-library/esm.js")
+			}
+		},
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("esm")
+			})
+		]
+	},
+	{
+		entry: "./module-export-test.js",
+		resolve: {
+			alias: {
+				library: path.resolve(testPath, "../0-create-library/esm-export.js")
+			}
+		},
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("esm-export")
+			})
+		]
+	},
+	{
+		entry: "./module-export-test.js",
+		resolve: {
+			alias: {
+				library: path.resolve(
+					testPath,
+					"../0-create-library/esm-export-no-concatenate-modules.js"
+				)
+			}
+		},
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("esm-export-no-concatenate-modules.js")
+			})
+		]
+	},
+	...(supportsAsync()
+		? [
+				{
+					resolve: {
+						alias: {
+							library: path.resolve(
+								testPath,
+								"../0-create-library/esm-async.js"
+							)
+						}
+					},
+					plugins: [
+						new webpack.DefinePlugin({
+							NAME: JSON.stringify("esm-async")
+						})
+					]
+				},
+				{
+					resolve: {
+						alias: {
+							library: path.resolve(
+								testPath,
+								"../0-create-library/esm-async-no-concatenate-modules.js"
+							)
+						}
+					},
+					plugins: [
+						new webpack.DefinePlugin({
+							NAME: JSON.stringify("esm-async-no-concatenate-modules")
+						})
+					]
+				}
+			]
+		: []),
 	{
 		resolve: {
 			alias: {
@@ -72,6 +136,51 @@ module.exports = (env, { testPath }) => [
 			})
 		]
 	},
+	{
+		resolve: {
+			alias: {
+				library: path.resolve(
+					testPath,
+					"../0-create-library/esm-runtimeChunk-concatenateModules/main.js"
+				)
+			}
+		},
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("esm-runtimeChunk-concatenateModules")
+			})
+		]
+	},
+	{
+		resolve: {
+			alias: {
+				library: path.resolve(
+					testPath,
+					"../0-create-library/esm-runtimeChunk-no-concatenateModules/main.js"
+				)
+			}
+		},
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("esm-runtimeChunk-no-concatenateModules")
+			})
+		]
+	},
+	{
+		resolve: {
+			alias: {
+				library: path.resolve(
+					testPath,
+					"../0-create-library/esm-runtimeChunk-concatenateModules-splitChunks/main.js"
+				)
+			}
+		},
+		plugins: [
+			new webpack.DefinePlugin({
+				NAME: JSON.stringify("esm-runtimeChunk-concatenateModules-splitChunks")
+			})
+		]
+	},
 	{
 		resolve: {
 			alias: {

test/helpers/supportsAsync.js

@@ -0,0 +1,15 @@
+module.exports = function supportsAsync() {
+	// Node.js@10 has a bug with nested async/await
+	if (process.version.startsWith("v10.")) {
+		return false;
+	}
+
+	try {
+		eval("async () => {}");
+		return true;
+	} catch (_err) {
+		// Ignore
+	}
+
+	return false;
+};