[Bug libstdc++/101510] std::filesystem::create_directory on an existing symlink to a directory

["enometh at meer dot net" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101510

--- Comment #9 from Madhu <enometh at meer dot net> ---
*  "redi at gcc dot gnu.org" 
<bug-101510-34102-aFAnZEywsl@http.gcc.gnu.org/bugzilla/>
Wrote on Tue, 20 Jul 2021 16:25:44 +0000

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101510
>
> --- Comment #8 from Jonathan Wakely <redi at gcc dot gnu.org> ---
> I think you are still confused between the bool that crate_directory returns,
> and the bool that you get from !ec
>
> The bool that is returned tells you if a new directory was created.
>
> The bool you get from !ec tells you if the directory exists (whether it was
> created or already existed).

I'm afraid I'm still confused. From what you suggest I should be able to write

// return true if p resolves to an existing directory
int
ensure_directories(p)
{
 std::error_code ec;
 std::filesystem::create_directories("p", ec);
 return !ec;
}


But this does not work

$ mkdir xxx
$ ln -sv fff asdf
$ ls asdf
asdf -> xxx

std::filesystem::create_directories("asdf", ec);
ec.value() = 20, !ec = 0

ensure_directories would return false but it shouldn't because asdf
resolves to an existing directory.