fix: match harmony accept dependencies by module reference (#21303)

alexander-akait · web-flow · commit 99286e22b9ca · 2026-06-29T23:43:21.000+03:00
The HMR accept template related dependencies via chunkGraph.getModuleId.
An unresolved import (ignored/failed, or a deferred lazy-barrel re-export)
has no module, and a module not in any chunk has a null id, so comparing
ids could crash ("Invalid value used as weak map key") or miss real
matches. Compare modules by reference and skip dependencies without a
module instead.
diff --git a/.changeset/harmony-accept-unresolved-module.md b/.changeset/harmony-accept-unresolved-module.md
@@ -0,0 +1,5 @@
+---
+"webpack": patch
+---
+
+Match harmony accept dependencies by module reference so HMR codegen handles imports without a module or chunk id.
diff --git a/lib/dependencies/HarmonyAcceptDependency.js b/lib/dependencies/HarmonyAcceptDependency.js
@@ -19,8 +19,6 @@ const NullDependency = require("./NullDependency");
 /** @typedef {import("./HarmonyAcceptImportDependency")} HarmonyAcceptImportDependency */
 /** @typedef {import("../serialization/ObjectMiddleware").ObjectDeserializerContext<[Range, HarmonyAcceptImportDependency[], boolean]>} ObjectDeserializerContext */
 /** @typedef {import("../serialization/ObjectMiddleware").ObjectSerializerContext<[Range, HarmonyAcceptImportDependency[], boolean]>} ObjectSerializerContext */
-/** @typedef {import("../Module")} Module */
-/** @typedef {import("../Module").ModuleId} ModuleId */
 
 class HarmonyAcceptDependency extends NullDependency {
 	/**
@@ -91,17 +89,6 @@ HarmonyAcceptDependency.Template = class HarmonyAcceptDependencyTemplate extends
 			chunkGraph
 		} = templateContext;
 
-		/**
-		 * Gets dependency module id.
-		 * @param {Dependency} dependency the dependency to get module id for
-		 * @returns {ModuleId | null} the module id or null if not found
-		 */
-		const getDependencyModuleId = (dependency) => {
-			const mod = moduleGraph.getModule(dependency);
-			if (!mod) return null;
-			return chunkGraph.getModuleId(mod);
-		};
-
 		/**
 		 * Checks whether this harmony accept dependency is related harmony import dependency.
 		 * @param {Dependency} a the first dependency
@@ -110,8 +97,11 @@ HarmonyAcceptDependency.Template = class HarmonyAcceptDependencyTemplate extends
 		 */
 		const isRelatedHarmonyImportDependency = (a, b) => {
 			if (a === b || !(b instanceof HarmonyImportDependency)) return false;
-			const idA = getDependencyModuleId(a);
-			return idA !== null && idA === getDependencyModuleId(b);
+			// Compare modules by reference: an unresolved import (ignored/failed, or a
+			// deferred lazy-barrel re-export) has no module, and a module not in any
+			// chunk has a null id — so comparing ids would crash or miss real matches.
+			const moduleA = moduleGraph.getModule(a);
+			return moduleA !== null && moduleA === moduleGraph.getModule(b);
 		};
 
 		/**
diff --git a/test/hotCases/harmony/accept-import-without-module/broken.js b/test/hotCases/harmony/accept-import-without-module/broken.js
@@ -0,0 +1,7 @@
+import { value } from "./file";
+
+// "./ignored" is dropped by IgnorePlugin, so its accept dependency resolves to
+// no module. Generating this accept must not crash (issue #21300). This entry
+// is compiled but never executed by the runner, so the missing-module runtime
+// stub is never reached.
+if (value) module.hot.accept(["./file", "./ignored"], function () {});
diff --git a/test/hotCases/harmony/accept-import-without-module/file.js b/test/hotCases/harmony/accept-import-without-module/file.js
@@ -0,0 +1,3 @@
+export var value = 1;
+---
+export var value = 2;
diff --git a/test/hotCases/harmony/accept-import-without-module/index.js b/test/hotCases/harmony/accept-import-without-module/index.js
@@ -0,0 +1,10 @@
+import { value } from "./file";
+
+it("should compile HMR accept code for a module whose accept references a dependency without a module", function (done) {
+	expect(value).toBe(1);
+	module.hot.accept("./file", function () {
+		expect(value).toBe(2);
+		done();
+	});
+	NEXT(require("../../update")(done));
+});
diff --git a/test/hotCases/harmony/accept-import-without-module/webpack.config.js b/test/hotCases/harmony/accept-import-without-module/webpack.config.js
@@ -0,0 +1,16 @@
+"use strict";
+
+const webpack = require("../../../../");
+
+/** @type {import("../../../../").Configuration} */
+module.exports = {
+	// `broken` reproduces the codegen crash; the runner only executes `main`.
+	entry: {
+		main: "./index.js",
+		broken: "./broken.js"
+	},
+	output: {
+		filename: "[name].js"
+	},
+	plugins: [new webpack.IgnorePlugin({ resourceRegExp: /ignored/ })]
+};

-Original file line number
+Diff line change
@@ @@ -0,0 +1,5 @@ @@
 +---
 +"webpack": patch
 +---
++
 +Match harmony accept dependencies by module reference so HMR codegen handles imports without a module or chunk id.
Original file line number	Diff line number	Diff line change
`@@ -0,0 +1,3 @@`
	`1`	`+export var value = 1;`
	`2`	`+---`
	`3`	`+export var value = 2;`