fix: pass package type to loader runner

declarations/LoaderContext.d.ts

@@ -187,6 +187,7 @@ export interface LoaderRunnerLoaderContext<OptionsType> {
 		data: object | undefined;
 		pitchExecuted: boolean;
 		normalExecuted: boolean;
+		type?: "commonjs" | "module" | undefined;
 	}[];
 
 	/**

lib/NormalModuleFactory.js

@@ -994,7 +994,7 @@ If changing the source code is not an option there is also a resolve options cal
 					context,
 					item.loader,
 					resolveContext,
-					(err, result) => {
+					(err, result, resolveRequest) => {
 						if (
 							err &&
 							/^[^/]*$/.test(item.loader) &&
@@ -1021,8 +1021,18 @@ If changing the source code is not an option there is also a resolve options cal
 						if (err) return callback(err);
 
 						const parsedResult = this._parseResourceWithoutFragment(result);
+
+						const type = /\.mjs$/i.test(parsedResult.path)
+							? "module"
+							: /\.cjs$/i.test(parsedResult.path)
+							? "commonjs"
+							: resolveRequest.descriptionFileData === undefined
+							? undefined
+							: resolveRequest.descriptionFileData.type;
+
 						const resolved = {
 							loader: parsedResult.path,
+							type,
 							options:
 								item.options === undefined
 									? parsedResult.query

test/cases/loaders/_esm-loader-type/index.js

@@ -0,0 +1,9 @@
+it("should pass package.json type to loader", function () {
+	expect(require("esm/loader.js!")).toBe("module");
+});
+
+it("should pass 'module' type to loader for .mjs", function () {
+	expect(require("cjs/loader.mjs!")).toBe("module");
+	expect(require("esm/loader.mjs!")).toBe("module");
+	expect(require("./loader.mjs!")).toBe("module");
+});

test/cases/loaders/_esm-loader-type/loader.mjs

@@ -0,0 +1,4 @@
+/** @type {import("../../../../").LoaderDefinition} */
+export default function loader() {
+	return `export default "${this.loaders[this.loaderIndex].type}";`;
+}

test/cases/loaders/_esm-loader-type/test.filter.js

@@ -0,0 +1,5 @@
+module.exports = function (config) {
+	// TODO need fix in v8 https://github.com/nodejs/node/issues/35889
+	// TODO otherwise this test case cause segment fault
+	return false;
+};

test/cases/loaders/cjs-loader-type/index.js

@@ -0,0 +1,12 @@
+it("should pass package.json type to loader", function () {
+	expect(require("cjs/loader.js!")).toBe("commonjs");
+	expect(require("./loader.js!")).toBe("undefined");
+});
+
+it("should pass 'commonjs' type to loader for .cjs", function () {
+	expect(require("cjs/loader.cjs!")).toBe("commonjs");
+	expect(require("./loader.cjs!")).toBe("commonjs");
+	// TODO need fix in v8 https://github.com/nodejs/node/issues/35889
+	// TODO otherwise this test case cause segment fault
+	// expect(require("esm/loader.cjs!")).toBe("commonjs");
+});

test/cases/loaders/cjs-loader-type/loader.cjs

@@ -0,0 +1,4 @@
+/** @type {import("../../../../").LoaderDefinition} */
+module.exports = function loader() {
+	return `module.exports = "${this.loaders[this.loaderIndex].type}";`;
+};

test/cases/loaders/cjs-loader-type/loader.js

@@ -0,0 +1,4 @@
+/** @type {import("../../../../").LoaderDefinition} */
+module.exports = function loader() {
+	return `module.exports = "${this.loaders[this.loaderIndex].type}";`;
+};

types.d.ts

@@ -6570,6 +6570,7 @@ declare interface LoaderRunnerLoaderContext<OptionsType> {
 		data?: object;
 		pitchExecuted: boolean;
 		normalExecuted: boolean;
+		type?: "module" | "commonjs";
 	}[];
 
 	/**