Comment by maxdamantus

They have effectively done this (since the linked issue was raised), by just converting Windows filenames to WTF-8.

I think this is sensible, because the fact that Windows still uses UTF-16 (or more precisely "Unicode 16-bit strings") in some places shouldn't need to complicate the API on other platforms that didn't make the UCS-2/UTF-16 mistake.

It's possible that the WTF-8 strings might not concatenate the way they do in UTF-16 or properly enforced WTF-8 (which has special behaviour on concatenation), but they'll still round-trip to the intended 16-bit string, even after concatenation.