From 9febbf827088cc8e94b2799e6c5976997bb88c65 Mon Sep 17 00:00:00 2001
From: Christopher Berner <me@cberner.com>
Date: Tue, 6 May 2025 20:18:06 -0700
Subject: [PATCH] Remove unnecessary handling of ERROR_IO_PENDING

try_lock() and try_lock_shared() do not need to handle these per the discussion in https://github.com/rust-lang/rust/pull/140718#discussion_r2076678485
---
 library/std/src/fs/tests.rs       | 22 ++++++++++++++++++++++
 library/std/src/sys/fs/windows.rs | 10 ++--------
 2 files changed, 24 insertions(+), 8 deletions(-)

diff --git a/library/std/src/fs/tests.rs b/library/std/src/fs/tests.rs
index 46b0d832fec4..49f99351c8aa 100644
--- a/library/std/src/fs/tests.rs
+++ b/library/std/src/fs/tests.rs
@@ -366,6 +366,28 @@ fn file_lock_blocking_async() {
     t.join().unwrap();
 }
 
+#[test]
+#[cfg(windows)]
+fn file_try_lock_async() {
+    const FILE_FLAG_OVERLAPPED: u32 = 0x40000000;
+
+    let tmpdir = tmpdir();
+    let filename = &tmpdir.join("file_try_lock_async.txt");
+    let f1 = check!(File::create(filename));
+    let f2 =
+        check!(OpenOptions::new().custom_flags(FILE_FLAG_OVERLAPPED).write(true).open(filename));
+
+    // Check that shared locks block exclusive locks
+    check!(f1.lock_shared());
+    assert_matches!(f2.try_lock(), Err(TryLockError::WouldBlock));
+    check!(f1.unlock());
+
+    // Check that exclusive locks block all locks
+    check!(f1.lock());
+    assert_matches!(f2.try_lock(), Err(TryLockError::WouldBlock));
+    assert_matches!(f2.try_lock_shared(), Err(TryLockError::WouldBlock));
+}
+
 #[test]
 fn file_test_io_seek_shakedown() {
     //                   01234567890123
diff --git a/library/std/src/sys/fs/windows.rs b/library/std/src/sys/fs/windows.rs
index 9039fd00f5d6..d01a572ac733 100644
--- a/library/std/src/sys/fs/windows.rs
+++ b/library/std/src/sys/fs/windows.rs
@@ -415,10 +415,7 @@ impl File {
 
         match result {
             Ok(_) => Ok(()),
-            Err(err)
-                if err.raw_os_error() == Some(c::ERROR_IO_PENDING as i32)
-                    || err.raw_os_error() == Some(c::ERROR_LOCK_VIOLATION as i32) =>
-            {
+            Err(err) if err.raw_os_error() == Some(c::ERROR_LOCK_VIOLATION as i32) => {
                 Err(TryLockError::WouldBlock)
             }
             Err(err) => Err(TryLockError::Error(err)),
@@ -440,10 +437,7 @@ impl File {
 
         match result {
             Ok(_) => Ok(()),
-            Err(err)
-                if err.raw_os_error() == Some(c::ERROR_IO_PENDING as i32)
-                    || err.raw_os_error() == Some(c::ERROR_LOCK_VIOLATION as i32) =>
-            {
+            Err(err) if err.raw_os_error() == Some(c::ERROR_LOCK_VIOLATION as i32) => {
                 Err(TryLockError::WouldBlock)
             }
             Err(err) => Err(TryLockError::Error(err)),