Right, by “UTF-8 Win32” I mean the *A Win32 functions (as used by the non-wide functions in the Microsoft C runtime) when a UTF-8 code page is active. Rust uses

Right, by “UTF-8 Win32” I mean the *A Win32 functions (as used by the non-wide functions in the Microsoft C runtime) when a UTF-8 code page is active. Rust uses the *W ones instead. As being prepared for invalid UTF-8 on Unix, well, it depends. If you refuse to run with non-UTF-8 LC_CTYPE or to accept invalid UTF-8 in user-provided file names, I suppose that’s on you. (Though I sure hope you are not writing an implementation of rm or tar!) If you’re trying to erase or move everything in a directory, though, you’ll have to either deal with whatever’s there or at least recognize that the action may fail.