Fix #42531

Bad identifier for async closure generator body names in extension methods.

Fixed: 42531
Change-Id: Ice29bb5ac03c67b1024c0fd53ffdb9b9b1d2131f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153484
Commit-Queue: Stephen Adams <[email protected]>
Reviewed-by: Sigmund Cherem <[email protected]>
Reviewed-by: Nicholas Shahan <[email protected]>

Author: rakudrama

pkg/compiler/lib/src/js_backend/namer.dart

@@ -681,7 +681,8 @@ class Namer extends ModularNamer {
       String invocationName = operatorNameToIdentifier(function.name);
       // TODO(sra): If the generator is for a closure's 'call' method, we don't
       // need to incorporate the enclosing class.
-      String className = method.enclosingClass.name.replaceAll('&', '_');
+      String className =
+          method.enclosingClass.name.replaceAll(_nonIdentifierRE, '_');
       return '${invocationName}\$body\$${className}';
     });
   }

tests/dart2js/42531_test.dart

@@ -0,0 +1,46 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:expect/expect.dart';
+
+// Regression test for badly named generator body.
+
+Future<void> goo(Future Function() f) async {
+  Expect.equals(102, (await f()).keys.single);
+  Expect.equals(104, (await f()).keys.single);
+}
+
+Future<T> identity<T>(T x) async => x;
+
+extension Gloop<T> on Map<T, List<T>> {
+  // An async method using a 'complex' generator type `Map<T, List<T>>`.  This
+  // requires a separated entry and body, which requires a name, and the name
+  // must be legal JavaScript.
+  Future<Map<T, List<T>>> foo(int x) async {
+    var result = await identity({(x += this.length) as T: <T>[]});
+    return result;
+  }
+
+  Future<int> bar(int x) async {
+    // An async closure using a 'complex' generator type `Map<T, Set<T>>`.  This
+    // requires a separated entry and body, which requires a name, and the name
+    // must be legal JavaScript.
+    await goo(() async => {(x += this.length) as T: <T>{}});
+    return x;
+  }
+}
+
+main() async {
+  // Test method.
+  Map<int, List<int>> o1 = {1: [], 2: []};
+  var o2 = await o1.foo(100);
+  var o3 = await o2.foo(100);
+  Expect.equals('{102: []}', '$o2');
+  Expect.equals('{101: []}', '$o3');
+
+  // Test closure.
+  Map<int, List<int>> o = {1: [], 2: []};
+  int x = await o.bar(100);
+  Expect.equals(104, x);
+}

tests/dart2js_2/42531_test.dart

@@ -0,0 +1,46 @@
+// Copyright (c) 2020, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+import 'package:expect/expect.dart';
+
+// Regression test for badly named generator body.
+
+Future<void> goo(Future Function() f) async {
+  Expect.equals(102, (await f()).keys.single);
+  Expect.equals(104, (await f()).keys.single);
+}
+
+Future<T> identity<T>(T x) async => x;
+
+extension Gloop<T> on Map<T, List<T>> {
+  // An async method using a 'complex' generator type `Map<T, List<T>>`.  This
+  // requires a separated entry and body, which requires a name, and the name
+  // must be legal JavaScript.
+  Future<Map<T, List<T>>> foo(int x) async {
+    var result = await identity({(x += this.length) as T: <T>[]});
+    return result;
+  }
+
+  Future<int> bar(int x) async {
+    // An async closure using a 'complex' generator type `Map<T, Set<T>>`.  This
+    // requires a separated entry and body, which requires a name, and the name
+    // must be legal JavaScript.
+    await goo(() async => {(x += this.length) as T: <T>{}});
+    return x;
+  }
+}
+
+main() async {
+  // Test method.
+  Map<int, List<int>> o1 = {1: [], 2: []};
+  var o2 = await o1.foo(100);
+  var o3 = await o2.foo(100);
+  Expect.equals('{102: []}', '$o2');
+  Expect.equals('{101: []}', '$o3');
+
+  // Test closure.
+  Map<int, List<int>> o = {1: [], 2: []};
+  int x = await o.bar(100);
+  Expect.equals(104, x);
+}