emit correct code for reexport unused exports

lib/dependencies/HarmonyExportImportedSpecifierDependency.js

@@ -602,10 +602,10 @@ HarmonyExportImportedSpecifierDependency.Template = class HarmonyExportImportedS
 
 	getReexportStatement(module, key, name, valueKey) {
 		const exportsName = module.exportsArgument;
-		const returnValue = this.getReturnValue(valueKey);
+		const returnValue = this.getReturnValue(name, valueKey);
 		return `__webpack_require__.d(${exportsName}, ${JSON.stringify(
 			key
-		)}, function() { return ${name}${returnValue}; });\n`;
+		)}, function() { return ${returnValue}; });\n`;
 	}
 
 	getReexportFakeNamespaceObjectStatement(module, key, name) {
@@ -617,19 +617,25 @@ HarmonyExportImportedSpecifierDependency.Template = class HarmonyExportImportedS
 
 	getConditionalReexportStatement(module, key, name, valueKey) {
 		const exportsName = module.exportsArgument;
-		const returnValue = this.getReturnValue(valueKey);
+		const returnValue = this.getReturnValue(name, valueKey);
 		return `if(__webpack_require__.o(${name}, ${JSON.stringify(
 			valueKey
 		)})) __webpack_require__.d(${exportsName}, ${JSON.stringify(
 			key
-		)}, function() { return ${name}${returnValue}; });\n`;
+		)}, function() { return ${returnValue}; });\n`;
 	}
 
-	getReturnValue(valueKey) {
+	getReturnValue(name, valueKey) {
 		if (valueKey === null) {
-			return "_default.a";
+			return `${name}_default.a`;
+		}
+		if (valueKey === "") {
+			return name;
+		}
+		if (valueKey === false) {
+			return "/* unused export */ undefined";
 		}
 
-		return valueKey && "[" + JSON.stringify(valueKey) + "]";
+		return `${name}[${JSON.stringify(valueKey)}]`;
 	}
 };

lib/optimize/ConcatenatedModule.js

@@ -133,6 +133,9 @@ const getFinalName = (
 						strictHarmonyModule
 					);
 				}
+				if (!info.module.isUsed(directExport)) {
+					return "/* unused export */ undefined";
+				}
 				const name = info.internalNames.get(directExport);
 				if (!name) {
 					throw new Error(

test/configCases/deep-scope-analysis/remove-export-scope-hoisting/index.js

@@ -0,0 +1,9 @@
+import { test, unused } from "./module";
+
+it("should run the test", () => {
+	expect(test()).toEqual({
+		used: "used",
+		unused: undefined
+	});
+	expect(unused).toEqual(undefined);
+});

test/configCases/deep-scope-analysis/remove-export-scope-hoisting/module.js

@@ -0,0 +1,10 @@
+import { used, unused } from "./reference";
+
+export function test() {
+	return {
+		used,
+		unused
+	};
+}
+
+export { unused }

test/configCases/deep-scope-analysis/remove-export-scope-hoisting/reference.js

@@ -0,0 +1,3 @@
+export var used = "used";
+
+export var unused = "unused";

test/configCases/deep-scope-analysis/remove-export-scope-hoisting/webpack.config.js

@@ -0,0 +1,34 @@
+const DependencyReference = require("../../../../").dependencies
+	.DependencyReference;
+module.exports = {
+	optimization: {
+		usedExports: true,
+		concatenateModules: true
+	},
+	plugins: [
+		function() {
+			this.hooks.compilation.tap("Test", compilation => {
+				compilation.hooks.dependencyReference.tap(
+					"Test",
+					(ref, dep, module) => {
+						if (
+							module.identifier().endsWith("module.js") &&
+							ref.module &&
+							ref.module.identifier().endsWith("reference.js") &&
+							Array.isArray(ref.importedNames) &&
+							ref.importedNames.includes("unused")
+						) {
+							return new DependencyReference(
+								ref.module,
+								ref.importedNames.filter(item => item !== "unused"),
+								ref.weak,
+								ref.order
+							);
+						}
+						return ref;
+					}
+				);
+			});
+		}
+	]
+};

test/configCases/deep-scope-analysis/remove-export/index.js

@@ -1,8 +1,9 @@
-import { test } from "./module";
+import { test, unused } from "./module";
 
 it("should run the test", () => {
 	expect(test()).toEqual({
 		used: "used",
 		unused: undefined
-	})
+	});
+	expect(unused).toEqual(undefined);
 });

test/configCases/deep-scope-analysis/remove-export/module.js

@@ -6,3 +6,5 @@ export function test() {
 		unused
 	};
 }
+
+export { unused }