Adjust Behaviour of read_dir and ReadDir in Windows Implementation: Check Whether Path to Search In Exists

library/std/src/sys/pal/windows/fs.rs

@@ -1068,14 +1068,35 @@ pub fn readdir(p: &Path) -> io::Result<ReadDir> {
     unsafe {
         let mut wfd = mem::zeroed();
         let find_handle = c::FindFirstFileW(path.as_ptr(), &mut wfd);
+
+        // The status `ERROR_FILE_NOT_FOUND` is returned by the `FindFirstFileW` function
+        // if no matching files can be found, but not necessarily that the path to find the
+        // files in does not exist.
+        //
+        // Hence, a check for whether the path to search in exists is added when the last
+        // os error returned by Windows is `ERROR_FILE_NOT_FOUND` to handle this scenario.
+        // If that is the case, an empty `ReadDir` iterator is returned as it returns `None`
+        // in the initial `.next()` invocation because `ERROR_NO_MORE_FILES` would have been
+        // returned by the `FindNextFileW` function.
+        //
+        // See issue #120040: https://github.com/rust-lang/rust/issues/120040.
+        let last_error = Error::last_os_error();
+        if last_error.raw_os_error().unwrap() == c::ERROR_FILE_NOT_FOUND as i32 && p.exists() {
+            return Ok(ReadDir {
+                handle: FindNextFileHandle(find_handle),
+                root: Arc::new(root),
+                first: None,
+            });
+        }
+
         if find_handle != c::INVALID_HANDLE_VALUE {
             Ok(ReadDir {
                 handle: FindNextFileHandle(find_handle),
                 root: Arc::new(root),
                 first: Some(wfd),
             })
         } else {
-            Err(Error::last_os_error())
+            Err(last_error)
         }
     }
 }