Merge pull request #15266 from webpack/bugfix/throwing-in-async-modules

fix handling of errors thrown in async modules

lib/async-modules/AwaitDependenciesInitFragment.js

@@ -30,8 +30,8 @@ class AwaitDependenciesInitFragment extends InitFragment {
 	}
 
 	merge(other) {
-		const promises = new Set(this.promises);
-		for (const p of other.promises) {
+		const promises = new Set(other.promises);
+		for (const p of this.promises) {
 			promises.add(p);
 		}
 		return new AwaitDependenciesInitFragment(promises);
@@ -51,7 +51,7 @@ class AwaitDependenciesInitFragment extends InitFragment {
 			for (const p of promises) {
 				return Template.asString([
 					`var __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${p}]);`,
-					`${p} = (__webpack_async_dependencies__.then ? await __webpack_async_dependencies__ : __webpack_async_dependencies__)[0];`,
+					`${p} = (__webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__)[0];`,
 					""
 				]);
 			}
@@ -60,7 +60,7 @@ class AwaitDependenciesInitFragment extends InitFragment {
 		// TODO check if destructuring is supported
 		return Template.asString([
 			`var __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${sepPromises}]);`,
-			`([${sepPromises}] = __webpack_async_dependencies__.then ? await __webpack_async_dependencies__ : __webpack_async_dependencies__);`,
+			`([${sepPromises}] = __webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__);`,
 			""
 		]);
 	}

lib/dependencies/HarmonyCompatibilityDependency.js

@@ -74,14 +74,14 @@ HarmonyCompatibilityDependency.Template = class HarmonyExportDependencyTemplate
 			initFragments.push(
 				new InitFragment(
 					runtimeTemplate.supportsArrowFunction()
-						? `${RuntimeGlobals.asyncModule}(${module.moduleArgument}, async (__webpack_handle_async_dependencies__) => {\n`
-						: `${RuntimeGlobals.asyncModule}(${module.moduleArgument}, async function (__webpack_handle_async_dependencies__) {\n`,
+						? `${RuntimeGlobals.asyncModule}(${module.moduleArgument}, async (__webpack_handle_async_dependencies__, __webpack_async_result__) => { try {\n`
+						: `${RuntimeGlobals.asyncModule}(${module.moduleArgument}, async function (__webpack_handle_async_dependencies__, __webpack_async_result__) { try {\n`,
 					InitFragment.STAGE_ASYNC_BOUNDARY,
 					0,
 					undefined,
-					module.buildMeta.async
-						? `\n__webpack_handle_async_dependencies__();\n}, 1);`
-						: "\n});"
+					`\n__webpack_async_result__();\n} catch(e) { __webpack_async_result__(e); } }${
+						module.buildMeta.async ? ", 1" : ""
+					});`
 				)
 			);
 		}

lib/runtime/AsyncModuleRuntimeModule.js

@@ -22,6 +22,7 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 		return Template.asString([
 			'var webpackThen = typeof Symbol === "function" ? Symbol("webpack then") : "__webpack_then__";',
 			'var webpackExports = typeof Symbol === "function" ? Symbol("webpack exports") : "__webpack_exports__";',
+			'var webpackError = typeof Symbol === "function" ? Symbol("webpack error") : "__webpack_error__";',
 			`var completeQueue = ${runtimeTemplate.basicFunction("queue", [
 				"if(queue) {",
 				Template.indent([
@@ -56,9 +57,13 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 								"obj[webpackExports] = r;",
 								"completeQueue(queue);",
 								"queue = 0;"
+							])}, ${runtimeTemplate.basicFunction("e", [
+								"obj[webpackError] = e;",
+								"completeQueue(queue);",
+								"queue = 0;"
 							])});`,
-							`var obj = {};
-							obj[webpackThen] = ${runtimeTemplate.expressionFunction(
+							"var obj = {};",
+							`obj[webpackThen] = ${runtimeTemplate.expressionFunction(
 								"queueFunction(queue, fn), dep['catch'](reject)",
 								"fn, reject"
 							)};`,
@@ -67,13 +72,13 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 						"}"
 					]),
 					"}",
-					`var ret = {};
-					ret[webpackThen] = ${runtimeTemplate.expressionFunction(
+					"var ret = {};",
+					`ret[webpackThen] = ${runtimeTemplate.expressionFunction(
 						"completeFunction(fn)",
 						"fn"
-					)};
-					ret[webpackExports] = dep;
-					return ret;`
+					)};`,
+					"ret[webpackExports] = dep;",
+					"return ret;"
 				])})`,
 				"deps"
 			)};`,
@@ -119,24 +124,29 @@ class AsyncModuleRuntimeModule extends HelperRuntimeModule {
 				)};`,
 				"module.exports = promise;",
 				`body(${runtimeTemplate.basicFunction("deps", [
-					"if(!deps) return outerResolve();",
 					"currentDeps = wrapDeps(deps);",
-					"var fn, result;",
+					"var fn;",
+					`var getResult = ${runtimeTemplate.returningFunction(
+						`currentDeps.map(${runtimeTemplate.basicFunction("d", [
+							"if(d[webpackError]) throw d[webpackError];",
+							"return d[webpackExports];"
+						])})`
+					)}`,
 					`var promise = new Promise(${runtimeTemplate.basicFunction(
 						"resolve, reject",
 						[
 							`fn = ${runtimeTemplate.expressionFunction(
-								`resolve(result = currentDeps.map(${runtimeTemplate.returningFunction(
-									"d[webpackExports]",
-									"d"
-								)}))`
+								"resolve(getResult)"
 							)};`,
 							"fn.r = 0;",
 							"whenAll(currentDeps, fn, reject);"
 						]
 					)});`,
-					"return fn.r ? promise : result;"
-				])}).then(outerResolve, reject);`,
+					"return fn.r ? promise : getResult();"
+				])}, ${runtimeTemplate.expressionFunction(
+					"err && reject(promise[webpackError] = err), outerResolve()",
+					"err"
+				)});`,
 				"isEvaluating = false;"
 			])};`
 		]);

lib/wasm-async/AsyncWebAssemblyJavascriptGenerator.js

@@ -167,14 +167,20 @@ class AsyncWebAssemblyJavascriptGenerator extends Generator {
 						)}`,
 						`${RuntimeGlobals.asyncModule}(${
 							module.moduleArgument
-						}, ${runtimeTemplate.basicFunction(
-							"__webpack_handle_async_dependencies__",
+						}, async ${runtimeTemplate.basicFunction(
+							"__webpack_handle_async_dependencies__, __webpack_async_result__",
 							[
+								"try {",
 								importsCode,
 								`var __webpack_async_dependencies__ = __webpack_handle_async_dependencies__([${promises.join(
 									", "
 								)}]);`,
-								"return __webpack_async_dependencies__.then ? __webpack_async_dependencies__.then(__webpack_instantiate__) : __webpack_instantiate__(__webpack_async_dependencies__);"
+								`var [${promises.join(
+									", "
+								)}] = __webpack_async_dependencies__.then ? (await __webpack_async_dependencies__)() : __webpack_async_dependencies__;`,
+								`${importsCompatCode}await ${instantiateCall};`,
+								"__webpack_async_result__();",
+								"} catch(e) { __webpack_async_result__(e); }"
 							]
 						)}, 1);`
 				  ])

test/__snapshots__/StatsTestCases.basictest.js.snap

@@ -4554,9 +4554,9 @@ webpack x.x.x compiled with 1 warning in X ms"
 `;
 
 exports[`StatsTestCases should print correct stats for wasm-explorer-examples-sync 1`] = `
-"assets by path *.js 21.8 KiB
-  asset bundle.js 16.4 KiB [emitted] (name: main)
-  asset 325.bundle.js 3.79 KiB [emitted]
+"assets by path *.js 22.2 KiB
+  asset bundle.js 16.7 KiB [emitted] (name: main)
+  asset 325.bundle.js 3.9 KiB [emitted]
   asset 795.bundle.js 557 bytes [emitted]
   asset 526.bundle.js 366 bytes [emitted] (id hint: vendors)
   asset 189.bundle.js 243 bytes [emitted]
@@ -4571,8 +4571,8 @@ assets by path *.wasm 1.37 KiB
   asset 0301cb3f9f4151b567f5.module.wasm 120 bytes [emitted] [immutable]
 chunk (runtime: main) 20.bundle.js 50 bytes (javascript) 531 bytes (webassembly) [rendered]
   ./duff.wasm 50 bytes (javascript) 531 bytes (webassembly) [built] [code generated]
-chunk (runtime: main) bundle.js (main) 586 bytes (javascript) 9.25 KiB (runtime) [entry] [rendered]
-  runtime modules 9.25 KiB 11 modules
+chunk (runtime: main) bundle.js (main) 586 bytes (javascript) 9.49 KiB (runtime) [entry] [rendered]
+  runtime modules 9.49 KiB 11 modules
   ./index.js 586 bytes [built] [code generated]
 chunk (runtime: main) 189.bundle.js 50 bytes (javascript) 156 bytes (webassembly) [rendered]
   ./Q_rsqrt.wasm 50 bytes (javascript) 156 bytes (webassembly) [built] [code generated]
@@ -4586,7 +4586,7 @@ chunk (runtime: main) 526.bundle.js (id hint: vendors) 34 bytes [rendered] split
 chunk (runtime: main) 795.bundle.js 110 bytes (javascript) 444 bytes (webassembly) [rendered]
   ./fact.wasm 50 bytes (javascript) 154 bytes (webassembly) [built] [code generated]
   ./fast-math.wasm 60 bytes (javascript) 290 bytes (webassembly) [built] [code generated]
-runtime modules 9.25 KiB 11 modules
+runtime modules 9.49 KiB 11 modules
 cacheable modules 2.31 KiB (javascript) 1.37 KiB (webassembly)
   webassembly modules 310 bytes (javascript) 1.37 KiB (webassembly)
     ./Q_rsqrt.wasm 50 bytes (javascript) 156 bytes (webassembly) [built] [code generated]

test/cases/async-modules/double-import/a.js

@@ -0,0 +1,3 @@
+import x from "./shared";
+
+export default x + " world";

test/cases/async-modules/double-import/b.js

@@ -0,0 +1,3 @@
+import x from "./shared";
+
+export default x + " world";

test/cases/async-modules/double-import/index.js

@@ -0,0 +1,4 @@
+it("should allow to import an async module twice", async () => {
+	const result = await require("./main");
+	expect(result.default).toBe("hello world, hello world");
+});

test/cases/async-modules/double-import/main.js

@@ -0,0 +1,4 @@
+import a from "./a";
+import b from "./b";
+
+export default a + ", " + b;

test/cases/async-modules/double-import/shared.js

@@ -0,0 +1,3 @@
+await 1;
+await 1;
+export default "hello";

test/cases/async-modules/top-level-error/counter.js

@@ -0,0 +1,6 @@
+await 1;
+let value = 0;
+export const count = () => {
+	value++;
+	return value;
+};

test/cases/async-modules/top-level-error/index.js

@@ -0,0 +1,39 @@
+it("should allow to import an rejected async module again", async () => {
+	await expect(require("./main")).rejects.toEqual(
+		expect.objectContaining({
+			message: expect.stringContaining("expected rejection 1")
+		})
+	);
+	await expect(require("./module")).rejects.toEqual(
+		expect.objectContaining({
+			message: expect.stringContaining("expected rejection 1")
+		})
+	);
+	await expect(require("./module?2")).rejects.toEqual(
+		expect.objectContaining({
+			message: expect.stringContaining("expected rejection 2")
+		})
+	);
+	await expect(require("./reexport?2")).rejects.toEqual(
+		expect.objectContaining({
+			message: expect.stringContaining("expected rejection 1")
+		})
+	);
+	await Promise.all([
+		expect(require("./module?3")).rejects.toEqual(
+			expect.objectContaining({
+				message: expect.stringContaining("expected rejection 3")
+			})
+		),
+		expect(require("./module?4")).rejects.toEqual(
+			expect.objectContaining({
+				message: expect.stringContaining("expected rejection 4")
+			})
+		),
+		expect(require("./module?5")).rejects.toEqual(
+			expect.objectContaining({
+				message: expect.stringContaining("expected rejection 5")
+			})
+		)
+	]);
+});

test/cases/async-modules/top-level-error/main.js

@@ -0,0 +1,2 @@
+export { default as a } from "./reexport";
+export { default as b } from "./module?2";

test/cases/async-modules/top-level-error/module.js

@@ -0,0 +1,6 @@
+import { count } from "./counter";
+
+const c = count();
+throw new Error("expected rejection " + c);
+
+export default "ok";

test/cases/async-modules/top-level-error/reexport.js

@@ -0,0 +1 @@
+export { default as default } from "./module";