[Bug libstdc++/78870] Support std::filesystem on Windows

[jhasse at bixense dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78870

--- Comment #6 from Jan Niklas Hasse <jhasse at bixense dot com> ---
> Yes.

Okay thanks, I'll look into it.

> You can't copy any code, that would be a copyright violation. It's OK to see
> which Windows API functions Boost uses for a particular filesystem
> operation, but if you're not sure what is covered by copyright law then it's
> safer not to use another project at all.

According to https://www.gnu.org/licenses/license-list.html the Boost License
is GPL compatible. So when I mark the code I copied with the source, it should
work, shouldn't it?

> I was hoping that somebody who actually knows the Windows API would
> contribute the code, so they already know what the appropriate functions are.

I know the Windows API, but the details are hard to get right. Especially
getting everything to be bug-free. Many man hours have already been spend on
boost::filesystem and the API is similar to std::filesystem. Why should I
re-invent the wheel?