Path with spaces in _canonical_paths

[<thomas@coldfix.de>]

Hi all,

I'm trying to use `_canonical_paths` (on zsh 5.9) to let the user autocomplete
a fixed list of files. I hope I'm not using it incorrectly. Otherwise: It
seems to not escape spaces in paths appropriately. Short example:

compdef '_canonical_paths -N files files /tmp/My\ File' cmd
cmd <Tab>

Shows the following completions:

/tmp/My File    (appears twice)
/tmp/My\ File

i.e. I get in total 3 entries for the same path, and notably, the first option
is without escaping the space, i.e. it will result in a command line:

cmd /tmp/My File

which is obviously not as intended.

I tried scanning the code in /usr/share/zsh/functions/Completion/Unix/
_canonical_paths for the problem, but it is quite confusing to me. I was able
to gather that by removing the `-Q` from the line

   _wanted "$tag" expl "$desc" compadd $__gopts -Q -U -a matches && ret=0

it adds escapes to all the entries, i.e. the new completions are:

  /tmp/My\ File   (twice)
  /tmp/My\\\ File

which is still not as desired.

Much appreciated if anyone can help.

Best, Thomas