From 9cf26fc3cdc8595ff004e990f40ef6392cfc5b36 Mon Sep 17 00:00:00 2001
From: Alexander Markov <alexmarkov@google.com>
Date: Wed, 19 Apr 2023 13:50:19 +0000
Subject: [PATCH] [vm] Fix handling of exceptions thrown from Iterable.iterator
 during yield*

TEST=language/sync_star/sync_star_exception_iterator_test
Fixes https://github.com/dart-lang/sdk/issues/52083

Change-Id: I6f26189b5d5df1c1804cd6cd7a64f72bdbe55f94
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/295922
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Martin Kustermann <kustermann@google.com>
---
 sdk/lib/_internal/vm/lib/async_patch.dart | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/sdk/lib/_internal/vm/lib/async_patch.dart b/sdk/lib/_internal/vm/lib/async_patch.dart
index 4c71903977e..b4ebd933b12 100644
--- a/sdk/lib/_internal/vm/lib/async_patch.dart
+++ b/sdk/lib/_internal/vm/lib/async_patch.dart
@@ -572,6 +572,8 @@ class _SyncStarIterator<T> implements Iterator<T> {
       // Case: yield* some_iterator.
       final iterable = _yieldStarIterable;
       if (iterable != null) {
+        _yieldStarIterable = null;
+        _current = null;
         if (iterable is _SyncStarIterable) {
           // We got a recursive yield* of sync* function. Instead of creating
           // a new iterator we replace our current _state (remembering the
@@ -583,11 +585,14 @@ class _SyncStarIterator<T> implements Iterator<T> {
           nestedState._functionData = this;
           _state = nestedState;
         } else {
-          _yieldStarIterator = iterable.iterator;
+          try {
+            _yieldStarIterator = iterable.iterator;
+          } catch (exception, stackTrace) {
+            pendingException = exception;
+            pendingStackTrace = stackTrace;
+          }
         }
-        _yieldStarIterable = null;
-        _current = null;
-        // Fetch the next item.
+        // Fetch the next item or continue with exception.
         continue;
       }