From 848d7f4122826f4d26ee09404fe57ac9b9295b00 Mon Sep 17 00:00:00 2001
From: Rezvan Mahdavi Hezaveh <[email protected]>
Date: Mon, 11 Aug 2025 19:01:45 +0000
Subject: [PATCH] [explicit-resource-management] Fix parsing in c-style for

Based on spec text, we should have only one await when exiting
c-style for loop with `await using` declaration and not one
await per iteration.

Bug: 436181695
Change-Id: I853219ff6ad5f98c0619de891bb4ce916e3eb999
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/6830541
Reviewed-by: Olivier Flückiger <[email protected]>
Reviewed-by: Leszek Swirski <[email protected]>
Commit-Queue: Rezvan Mahdavi Hezaveh <[email protected]>
Cr-Commit-Position: refs/heads/main@{#101859}
---

diff --git a/src/parsing/parser.cc b/src/parsing/parser.cc
index 610eeb0..2789e34 100644
--- a/src/parsing/parser.cc
+++ b/src/parsing/parser.cc
@@ -2438,7 +2438,10 @@
     //    make statement: let/const x = temp_x.
     for (int i = 0; i < for_info.bound_names.length(); i++) {
       VariableProxy* proxy = DeclareBoundVariable(
-          for_info.bound_names[i], for_info.parsing_result.descriptor.mode,
+          for_info.bound_names[i],
+          for_info.parsing_result.descriptor.mode == VariableMode::kAwaitUsing
+              ? VariableMode::kConst
+              : for_info.parsing_result.descriptor.mode,
           kNoSourcePosition);
       inner_vars.Add(proxy->var());
       VariableProxy* temp_proxy = factory()->NewVariableProxy(temps.at(i));
diff --git a/test/mjsunit/harmony/regress/regress-436181695.js b/test/mjsunit/harmony/regress/regress-436181695.js
new file mode 100644
index 0000000..e1ff927
--- /dev/null
+++ b/test/mjsunit/harmony/regress/regress-436181695.js
@@ -0,0 +1,34 @@
+// Copyright 2025 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var v = [];
+
+(async () => {
+  for (let i = 0; i < 6; ++i) {
+    v.push(i);
+    await 0;
+  }
+})();
+
+async function TestCStyleForCountTicks() {
+  for (await using x = {
+         value: 42,
+         [Symbol.asyncDispose]() {
+           v.push(`asyncDispose`);
+         }  // One tick is expected after calling asyncDispose to allow it to be
+            // asynchronous. It will be called after exiting the for-loop.
+       };
+       x.value < 44; x.value++) {
+    // These pushes are expected to be synchronous.
+    v.push(x.value);
+  }
+  v.push(`afterForLoop`);
+}
+
+async function RunTest() {
+  await TestCStyleForCountTicks();
+  assertArrayEquals([0, 42, 43, `asyncDispose`, 1, `afterForLoop`, 2], v);
+}
+
+RunTest();

diff --git a/test/mjsunit/harmony/regress/regress-436181695.js b/test/mjsunit/harmony/regress/regress-436181695.js
new file mode 100644
index 0000000..e1ff927
--- /dev/null
+++ b/test/mjsunit/harmony/regress/regress-436181695.js
@@ -0,0 +1,34 @@
+// Copyright 2025 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+var v = [];
+
+(async () => {
+  for (let i = 0; i < 6; ++i) {
+    v.push(i);
+    await 0;
+  }
+})();
+
+async function TestCStyleForCountTicks() {
+  for (await using x = {
+         value: 42,
+         [Symbol.asyncDispose]() {
+           v.push(`asyncDispose`);
+         }  // One tick is expected after calling asyncDispose to allow it to be
+            // asynchronous. It will be called after exiting the for-loop.
+       };
+       x.value < 44; x.value++) {
+    // These pushes are expected to be synchronous.
+    v.push(x.value);
+  }
+  v.push(`afterForLoop`);
+}
+
+async function RunTest() {
+  await TestCStyleForCountTicks();
+  assertArrayEquals([0, 42, 43, `asyncDispose`, 1, `afterForLoop`, 2], v);
+}
+
+RunTest();