Remove unnecessary handling of ERROR_IO_PENDING

try_lock() and try_lock_shared() do not need to handle these per the discussion in rust-lang#140718 (comment)

Author: cberner

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().unwrap_err().kind(), ErrorKind::WouldBlock);
+    check!(f1.unlock());
+
+    // Check that exclusive locks block all locks
+    check!(f1.lock());
+    assert_matches!(f2.try_lock().unwrap_err().kind(), ErrorKind::WouldBlock);
+    assert_matches!(f2.try_lock_shared().unwrap_err().kind(), ErrorKind::WouldBlock);
+}
+
 #[test]
 fn file_test_io_seek_shakedown() {
     //                   01234567890123

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)),