[Bug libstdc++/106932] Incorrect behavior of std::filesystem::copy() with overwrite_existing or update_existing options

["redi at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106932

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
I think this is the correct behaviour according to the standard.

Where f is status("source") and t is status("dest").

Effects are then as follows:

- If f.type() or t.type() is an implementation-defined file type ...

[they're not]

- Otherwise, an error is reported as specified in 31.12.5 if:

[list of conditions that are not true]

- Otherwise, if is_symlink(f), then:

[it's not]

- Otherwise, if is_regular_file(f), then:

[it's not]

- Otherwise, if
  is_directory(f) &&
  (options & copy_options::create_symlinks) != copy_options::none

[create_symlinks is not set in the options]

- Otherwise, if
  is_directory(f) &&
  ((options & copy_options::recursive) != copy_options::none ||
    options == copy_options::none)

[this is the case we want to hit, but the condition is false because recursive
is not set and options != none]

- Otherwise, for the signature with argument ec, ec.clear().

[You didn't pass an erroc_code]

- Otherwise, no effects.

[Bingo]

So you need to use copy_options::recursive to get the effects you want.