fix: add declaration for unused harmony import specifier (#20286)

hai-x · web-flow · commit fd5558768f85 · 2026-01-12T19:13:02.000+03:00
diff --git a/.changeset/sixty-elephants-poke.md b/.changeset/sixty-elephants-poke.md
@@ -0,0 +1,5 @@
+---
+"webpack": patch
+---
+
+Add declaration for unused harmony import specifier.
diff --git a/lib/dependencies/HarmonyImportSpecifierDependency.js b/lib/dependencies/HarmonyImportSpecifierDependency.js
@@ -6,6 +6,7 @@
 "use strict";
 
 const Dependency = require("../Dependency");
+const InitFragment = require("../InitFragment");
 const Template = require("../Template");
 const {
 	getDependencyUsedByExportsCondition
@@ -336,10 +337,22 @@ HarmonyImportSpecifierDependency.Template = class HarmonyImportSpecifierDependen
 	 */
 	apply(dependency, source, templateContext) {
 		const dep = /** @type {HarmonyImportSpecifierDependency} */ (dependency);
-		const { moduleGraph, runtime } = templateContext;
+		const { moduleGraph, runtime, initFragments } = templateContext;
 		const connection = moduleGraph.getConnection(dep);
-		// Skip rendering depending when dependency is conditional
-		if (connection && !connection.isTargetActive(runtime)) return;
+
+		// Only render declaration for import specifier when the dependency is conditional
+		if (connection && !connection.isTargetActive(runtime)) {
+			initFragments.push(
+				new InitFragment(
+					`/* unused harmony import specifier */ var ${dep.name};\n`,
+					InitFragment.STAGE_HARMONY_IMPORTS,
+					0,
+					`unused import specifier ${dep.name}`
+				)
+			);
+
+			return;
+		}
 
 		const ids = dep.getIds(moduleGraph);
 		const {
diff --git a/test/configCases/inner-graph/issue-20151/i18n.js b/test/configCases/inner-graph/issue-20151/i18n.js
@@ -0,0 +1,7 @@
+export function __( v ) {
+    console.log( v );
+}
+
+export default {
+    __,
+};
diff --git a/test/configCases/inner-graph/issue-20151/index.js b/test/configCases/inner-graph/issue-20151/index.js
@@ -0,0 +1,32 @@
+import i18n from "./i18n.js";
+import { used } from "./wtf.js";
+import { parse } from "acorn";
+import fs from "fs";
+
+const __ = i18n.__;
+
+function xyz() {
+	used();
+	__("abc");
+}
+xyz();
+
+it("Should keep top-level `__` variable name in the entry module", () => {
+	const bundle = fs.readFileSync(__filename, "utf-8");
+
+	const ast = parse(bundle, {
+		sourceType: "module",
+		ecmaVersion: "latest"
+	});
+
+	expect(
+		ast.body.some(
+			(node) =>
+				node.type === "VariableDeclaration" &&
+				node.declarations.some(
+					(declaration) =>
+						declaration.id.type === "Identifier" && declaration.id.name === "__"
+				)
+		)
+	).toBe(true);
+});
diff --git a/test/configCases/inner-graph/issue-20151/test.filter.js b/test/configCases/inner-graph/issue-20151/test.filter.js
@@ -0,0 +1,5 @@
+"use strict";
+
+const supportsRequireInModule = require("../../../helpers/supportsRequireInModule");
+
+module.exports = () => supportsRequireInModule();
diff --git a/test/configCases/inner-graph/issue-20151/webpack.config.js b/test/configCases/inner-graph/issue-20151/webpack.config.js
@@ -0,0 +1,20 @@
+"use strict";
+
+/** @type {import("../../../../").Configuration} */
+module.exports = {
+	mode: "production",
+	target: "node14",
+	optimization: {
+		minimize: false,
+		mangleExports: false,
+		concatenateModules: false,
+		emitOnErrors: true
+	},
+	output: {
+		module: true
+	},
+	experiments: {
+		outputModule: true
+	},
+	externals: ["acorn"]
+};
diff --git a/test/configCases/inner-graph/issue-20151/wtf.js b/test/configCases/inner-graph/issue-20151/wtf.js
@@ -0,0 +1,9 @@
+import { __ } from './i18n.js';
+
+export function unused() {
+    return __( "wtf" );
+}
+
+export function used() {
+    return __( "ok" );
+}

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"webpack": patch
 +---
++
 +Add declaration for unused harmony import specifier.