add tree-shaking to ProvidedDependency

lib/dependencies/ProvidedDependency.js

@@ -5,19 +5,23 @@
 
 "use strict";
 
+const Dependency = require("../Dependency");
 const InitFragment = require("../InitFragment");
 const makeSerializable = require("../util/makeSerializable");
 const ModuleDependency = require("./ModuleDependency");
 
 /** @typedef {import("webpack-sources").ReplaceSource} ReplaceSource */
 /** @typedef {import("../ChunkGraph")} ChunkGraph */
-/** @typedef {import("../Dependency")} Dependency */
+/** @typedef {import("../Dependency").ReferencedExport} ReferencedExport */
 /** @typedef {import("../Dependency").UpdateHashContext} UpdateHashContext */
 /** @typedef {import("../DependencyTemplate").DependencyTemplateContext} DependencyTemplateContext */
 /** @typedef {import("../DependencyTemplates")} DependencyTemplates */
 /** @typedef {import("../ModuleGraph")} ModuleGraph */
 /** @typedef {import("../RuntimeTemplate")} RuntimeTemplate */
 /** @typedef {import("../util/Hash")} Hash */
+/** @typedef {import("../util/runtime").RuntimeSpec} RuntimeSpec */
+
+const idsSymbol = Symbol("ProvidedDependency.ids");
 
 /**
  * @param {string[]|null} path the property path array
@@ -29,10 +33,16 @@ const pathToString = path =>
 		: "";
 
 class ProvidedDependency extends ModuleDependency {
-	constructor(request, identifier, path, range) {
+	/**
+	 * @param {string} request request
+	 * @param {string} identifier identifier
+	 * @param {string[]} ids ids
+	 * @param {[number, number]} range range
+	 */
+	constructor(request, identifier, ids, range) {
 		super(request);
 		this.identifier = identifier;
-		this.path = path;
+		this.ids = ids;
 		this.range = range;
 		this._hashUpdate = undefined;
 	}
@@ -45,6 +55,38 @@ class ProvidedDependency extends ModuleDependency {
 		return "esm";
 	}
 
+	/**
+	 * @param {ModuleGraph} moduleGraph the module graph
+	 * @returns {string[]} the imported ids
+	 */
+	getIds(moduleGraph) {
+		const meta = moduleGraph.getMetaIfExisting(this);
+		if (meta === undefined) return this.ids;
+		const ids = meta[idsSymbol];
+		return ids !== undefined ? ids : this.ids;
+	}
+
+	/**
+	 * @param {ModuleGraph} moduleGraph the module graph
+	 * @param {string[]} ids the imported ids
+	 * @returns {void}
+	 */
+	setIds(moduleGraph, ids) {
+		moduleGraph.getMeta(this)[idsSymbol] = ids;
+	}
+
+	/**
+	 * Returns list of exports referenced by this dependency
+	 * @param {ModuleGraph} moduleGraph module graph
+	 * @param {RuntimeSpec} runtime the runtime for which the module is analysed
+	 * @returns {(string[] | ReferencedExport)[]} referenced exports
+	 */
+	getReferencedExports(moduleGraph, runtime) {
+		let ids = this.getIds(moduleGraph);
+		if (ids.length === 0) return Dependency.EXPORTS_OBJECT_REFERENCED;
+		return [ids];
+	}
+
 	/**
 	 * Update the hash
 	 * @param {Hash} hash hash to be updated
@@ -54,22 +96,22 @@ class ProvidedDependency extends ModuleDependency {
 	updateHash(hash, context) {
 		if (this._hashUpdate === undefined) {
 			this._hashUpdate =
-				this.identifier + (this.path ? this.path.join(",") : "null");
+				this.identifier + (this.ids ? this.ids.join(",") : "null");
 		}
 		hash.update(this._hashUpdate);
 	}
 
 	serialize(context) {
 		const { write } = context;
 		write(this.identifier);
-		write(this.path);
+		write(this.ids);
 		super.serialize(context);
 	}
 
 	deserialize(context) {
 		const { read } = context;
 		this.identifier = read();
-		this.path = read();
+		this.ids = read();
 		super.deserialize(context);
 	}
 }
@@ -90,6 +132,7 @@ class ProvidedDependencyTemplate extends ModuleDependency.Template {
 		dependency,
 		source,
 		{
+			runtime,
 			runtimeTemplate,
 			moduleGraph,
 			chunkGraph,
@@ -98,6 +141,9 @@ class ProvidedDependencyTemplate extends ModuleDependency.Template {
 		}
 	) {
 		const dep = /** @type {ProvidedDependency} */ (dependency);
+		const connection = moduleGraph.getConnection(dep);
+		const exportsInfo = moduleGraph.getExportsInfo(connection.module);
+		const usedName = exportsInfo.getUsedName(dep.getIds(moduleGraph), runtime);
 		initFragments.push(
 			new InitFragment(
 				`/* provided dependency */ var ${
@@ -107,7 +153,7 @@ class ProvidedDependencyTemplate extends ModuleDependency.Template {
 					chunkGraph,
 					request: dep.request,
 					runtimeRequirements
-				})}${pathToString(dep.path)};\n`,
+				})}${pathToString(/** @type {string[]} */ (usedName))};\n`,
 				InitFragment.STAGE_PROVIDES,
 				1,
 				`provided ${dep.identifier}`

test/configCases/plugins/provide-plugin/a.js

@@ -0,0 +1,2 @@
+export * as c from "./b";
+export * as c2 from "./harmony2";

test/configCases/plugins/provide-plugin/b.js

@@ -0,0 +1,7 @@
+export function square(x) {
+	return x * x;
+}
+
+export function cube(x) {
+	return x * x * x;
+}

test/configCases/plugins/provide-plugin/harmony2.js

@@ -0,0 +1,2 @@
+export const a = 1;
+export const aUsed = __webpack_exports_info__.a.used;

test/configCases/plugins/provide-plugin/index.js

@@ -48,6 +48,11 @@ it("should provide a module for a property request", function() {
 	expect(x).toBe("fff");
 });
 
+it("should tree-shake unused exports", function() {
+	expect(aa1(2)).toBe(8);
+	expect(es2015_aUsed).toBe(false);
+});
+
 it("should provide ES2015 modules", function() {
 	expect((es2015.default)).toBe("ECMAScript 2015");
 	expect((es2015.alias)).toBe("ECMAScript Harmony");

test/configCases/plugins/provide-plugin/webpack.config.js

@@ -6,6 +6,8 @@ module.exports = {
 			aaa: "./aaa",
 			"bbb.ccc": "./bbbccc",
 			dddeeefff: ["./ddd", "eee", "3-f"],
+			aa1: ["./a", "c", "cube"],
+			es2015_aUsed: ["./harmony2", "aUsed"],
 			"process.env.NODE_ENV": "./env",
 			es2015: "./harmony",
 			es2015_name: ["./harmony", "default"],