[stable][IO] - Use try/catch in lookupAddresses instead of Future error.

Applying patch from @aam for using try/catch in lookupAddresses instead
of Future error.

This cherry pick into the stable branch is to ensure we
address the expedient issue in #53334

TEST=new test added.

Bug: #53334
Change-Id: Ia5375cbd118d8d6437cf6869383f173cab48aa3f
Cherry-pick: https://dart-review.googlesource.com/c/sdk/+/323684
Cherry-pick-request: #53450
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/324569
Reviewed-by: Alexander Aprelev <[email protected]>
Commit-Queue: Siva Annamalai <[email protected]>

CHANGELOG.md

@@ -7,7 +7,16 @@ This is a patch release that:
   For example `final x = { for (var (int a,) in someList) a: a };`
   (issue [#53358])
 
+- Fixes an expedient issue of users seeing an unhandled
+  exception pause in the debugger, please see
+  https://github.com/dart-lang/sdk/issues/53450 for more
+  details.
+  The fix uses try/catch in lookupAddresses instead of
+  Future error so that we don't see an unhandled exception
+  pause in the debugger (issue [#53334])
+
 [#53358]: https://github.com/dart-lang/sdk/issues/53358
+[#53334]: https://github.com/dart-lang/sdk/issues/53334
 
 ## 3.1.1 - 2023-09-07
 

pkg/vm_service/test/break_on_unhandled_exception_test.dart

@@ -0,0 +1,68 @@
+// Copyright (c) 2023, 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.
+// VMOptions=--verbose_debug
+
+// Test checks to make sure we don't encounter any unhandled exceptions
+// in the URL lookup code.
+// (please see https://github.com/dart-lang/sdk/issues/53334 for more details).
+
+import 'dart:developer';
+import 'dart:io';
+
+import 'package:expect/expect.dart';
+
+import 'common/service_test_common.dart';
+import 'common/test_helper.dart';
+
+// AUTOGENERATED START
+//
+// Update these constants by running:
+//
+// dart runtime/observatory/tests/service/update_line_numbers.dart <test.dart>
+//
+const int LINE_0 = 46;
+// AUTOGENERATED END
+const String file = "break_on_unhandled_exception_test.dart";
+
+Future<int> testFunction() async {
+  try {
+    var client = new HttpClient();
+    final urlstr = 'https://www.bbc.co.uk/';
+    final uri = Uri.parse(urlstr);
+    var response = await client.getUrl(uri);
+    Expect.equals(urlstr, response.uri.toString());
+    return 0;
+  } catch (e) {
+    print(e.toString());
+    return 1;
+  }
+}
+
+void testMain() async {
+  debugger();
+  final ret = await testFunction();
+  Expect.equals(ret, 0);
+  print("Done"); // LINE_0
+}
+
+final tests = <IsolateTest>[
+  hasStoppedAtBreakpoint,
+
+  // Add breakpoint
+  setBreakpointAtUriAndLine(file, LINE_0),
+
+  resumeIsolate,
+
+  hasStoppedAtBreakpoint,
+  stoppedAtLine(LINE_0),
+  resumeIsolate,
+];
+
+void main(args) => runIsolateTests(
+      args,
+      tests,
+      'break_on_unhandled_exception_test.dart',
+      pause_on_unhandled_exceptions: true,
+      testeeConcurrent: testMain,
+    );

sdk/lib/_internal/vm/bin/socket_patch.dart

@@ -627,8 +627,10 @@ base class _NativeSocket extends _NativeSocketNativeWrapper
       // Only report an error if no address lookups were sucessful.
       var anySuccess = false;
 
-      void lookupAddresses(InternetAddressType type, Completer<void> done) {
-        lookup(host, type: type).then((addresses) {
+      void lookupAddresses(
+          InternetAddressType type, Completer<void> done) async {
+        try {
+          final addresses = await lookup(host, type: type);
           anySuccess = true;
           if (done.isCompleted) {
             // By the time lookup is done, [connectNext] might have
@@ -637,14 +639,14 @@ base class _NativeSocket extends _NativeSocketNativeWrapper
           }
           controller.add(addresses);
           done.complete();
-        }, onError: (e, st) {
+        } catch (e, st) {
           if (done.isCompleted) {
             // By the time lookup is done, [connectNext] might have
             // been able to connect to one of the resolved addresses.
             return;
           }
           done.completeError(e, st);
-        });
+        }
       }
 
       const concurrentLookupDelay = Duration(milliseconds: 10);