[llvm] [Support] Handle delete_pending case for Windows fs::status (PR #90655)

[Jeremy Day via llvm-commits]

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@@ -785,9 +785,20 @@ std::error_code status(const Twine &path, file_status &result, bool Follow) {
 
   DWORD Flags = FILE_FLAG_BACKUP_SEMANTICS;
   if (!Follow) {
-    DWORD attr = ::GetFileAttributesW(path_utf16.begin());
-    if (attr == INVALID_FILE_ATTRIBUTES)
-      return getStatus(INVALID_HANDLE_VALUE, result);
+    DWORD attr;
+
+    // If getting file attributes fails due to a pending deletion, try
+    // again in a loop to avoid returning a misleading permission denied
+    // error.
+    for (int Retry = 200; Retry >= 0; --Retry) {
+      attr = ::GetFileAttributesW(path_utf16.begin());
+      if (attr != INVALID_FILE_ATTRIBUTES)
+        break;
+      std::error_code code = getStatus(INVALID_HANDLE_VALUE, result);
+      if (code != llvm::errc::delete_pending || !Retry)
+        return code;
+      ::Sleep(15);
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z2oh wrote:

Yes, you are reading this right. The loop here is expected to succeed within a few iterations, and if doesn't complete within the 3 second window, that's a good indication that there's probably something else awry.

But, of course, callers may be able to handle this failure case and prefer to avoid a 3 second penalty.

I'll test to see how many iterations are reached under a normal workload.

https://github.com/llvm/llvm-project/pull/90655