Merge pull request #9724 from webpack/bugfix/serve-regression

HMR plugin should only affect the root compilation

lib/HotModuleReplacementPlugin.js

@@ -150,6 +150,10 @@ module.exports = class HotModuleReplacementPlugin {
 		compiler.hooks.compilation.tap(
 			"HotModuleReplacementPlugin",
 			(compilation, { normalModuleFactory }) => {
+				// This applies the HMR plugin only to the targeted compiler
+				// It should not affect child compilations
+				if (compilation.compiler !== compiler) return;
+
 				const hotUpdateChunkTemplate = compilation.hotUpdateChunkTemplate;
 				if (!hotUpdateChunkTemplate) return;
 

test/hotCases/child-compiler/issue-9706/file.js

@@ -0,0 +1,3 @@
+export default 1;
+---
+export default 2;

test/hotCases/child-compiler/issue-9706/index.js

@@ -0,0 +1,12 @@
+import value, { assets } from "./report-child-assets-loader!./file";
+
+it("should not emit hot updates from child compilers", done => {
+	expect(value).toBe(1);
+	expect(assets).toEqual(["test.js"]);
+	module.hot.accept("./report-child-assets-loader!./file", () => {
+		expect(value).toBe(2);
+		expect(assets).toEqual(["test.js"]);
+		done();
+	});
+	NEXT(require("../../update")(done));
+});

test/hotCases/child-compiler/issue-9706/report-child-assets-loader.js

@@ -0,0 +1,32 @@
+const NodeTemplatePlugin = require("../../../../lib/node/NodeTemplatePlugin");
+const FunctionModulePlugin = require("../../../../lib/FunctionModulePlugin");
+const SingleEntryPlugin = require("../../../../lib/SingleEntryPlugin");
+
+const compilerCache = new WeakMap();
+
+module.exports = function(source) {
+	let childCompiler = compilerCache.get(this._compiler);
+	if (childCompiler === undefined) {
+		childCompiler = this._compilation.createChildCompiler(
+			"my-compiler|" + this.request,
+			{
+				filename: "test.js"
+			},
+			[
+				new NodeTemplatePlugin(),
+				new FunctionModulePlugin(),
+				new SingleEntryPlugin(this.context, this.resource)
+			]
+		);
+		compilerCache.set(this._compiler, childCompiler);
+	}
+	const callback = this.async();
+	childCompiler.runAsChild((err, entries, compilation) => {
+		if (err) return callback(err);
+
+		const result = `export const assets = ${JSON.stringify(
+			compilation.getAssets().map(a => a.name)
+		)};\n${source}`;
+		callback(null, result);
+	});
+};