rmw won't move files across bind mounts (even if they share the same underlying filesystem)

[durable-vest]

If the file to be trashed (some_file) is on a bindmount and the trash folder (trash_folder) isn't, then rmwrc will fail even if some_file and trash_folder share the same underlying filesystem.
The use case for such a setup is on a NixOS system running impermanence, not sure if this is something that's supported.

One idea to work around this is to add a --move-across-filesystems flag that falls back to mv when the files are across filesystems (i.e. cp some_file trash_folder && rm some_file).

Reproduction steps

Tested on Arch Linux using an ext4 filesystem mounted to /mnt, rmw built from source at 6a78b31

# create bindmounted folder and file
mkdir folder_original
mount --mkdir --bind folder_original folder_bindmounted
touch folder_bindmounted/some_file

# attempt to trash some_file
echo "WASTE = $PWD/trash_folder" > rmwrc
rmw --conf rmwrc folder_bindmounted/some_file

Expected Behavior

The file moves across bind mounts

Actual Behavior

  :error: folder_bindmounted/some_file -> /mnt/trash_folder/files/some_file
rename: Invalid cross-device link

[andy5995]

@durable-vest What I do in that case is add a separate trash folder (a path at the top level of the bound filesystem) to my .rmwrc to handle that.

I'm not sure yet if implementing something like --move-across-filesystems would be worth it. I'll leave this open for discussion.