[Support][Windows] Prevent 2s delay when renaming a file that does not exist

[amccarth]

rnk is on leave, so I'll jump in.

This is correct, but I have a small suggestion inline to make it more robust against future changes.

llvm/lib/Support/Windows/Path.inc

562

I would probably just return the error here rather than break.

When you break, you end up calling GetLastError() again. While that's probably safe, a small future change could end perturb that last error code.

[bd1976llvm]

Addressed review comments.

[bd1976llvm]

llvm/lib/Support/Windows/Path.inc

562

Clearly better. Thanks.

[amccarth]

LGTM. Thanks!

llvm/lib/Support/Windows/Path.inc

for (unsigned Retry = 0; Retry != 200; ++Retry) {
     if (Retry != 0)
       ::Sleep(10);
     FromHandle =
         ::CreateFileW(WideFrom.begin(), GENERIC_READ | DELETE,
                       FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                       NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);
     if (FromHandle)
       break;
+
+    // We don't want to loop if the file doesn't exist.
+    auto EC = mapWindowsError(GetLastError());
+    if (EC == errc::no_such_file_or_directory)
+      return EC;
   }
   if (!FromHandle)
     return mapWindowsError(GetLastError());
 
   return rename_handle(FromHandle, To);
 }
 
 std::error_code resize_file(int FD, uint64_t Size) {