Re: [BUG] _describe -x adds same completion group header twice

[Marlon Richert <marlon.richert@xxxxxxxxx>]

On Thu, Sep 9, 2021 at 10:04 PM Bart Schaefer <schaefer@xxxxxxxxxxxxxxxx> wrote:
>
> On Thu, Sep 9, 2021 at 9:50 AM Marlon Richert <marlon.richert@xxxxxxxxx> wrote:
> >
> > When _describe is called with -x, it adds the same group header twice:
>
> I think this is probably the same thing as in the thread starting
> workers/48091 (Bug in compdescribe ...) that was partly addressed by
> workers/49211.

The problem still exists on master and it looks to me like it isn't in
compdescribe. Here's a diff on the trace output from _describe without
-x (a) and with -x (b):

% diff a b
8c8,14
< +_describe:36> shift 0
---
> +_describe:22> case x (o)
> +_describe:22> case x (O)
> +_describe:22> case x (t)
> +_describe:22> case x (1|2|J|V|x)
> +_describe:33> _jvx12+=( -x )
> +_describe:21> getopts oOt:12JVx _opt
> +_describe:36> shift 1
26c32
< +_describe:68> _next_label values _expl desc
---
> +_describe:68> _next_label -x values _expl desc
48c54
< +_describe:114> compadd -2 -o nosort -J values -X --desc-- -D _a_11 - foo bar
---
> +_describe:114> compadd -2 -o nosort -J values -x --desc-- -D _a_11 - foo bar
57c63
< +_describe:134> compadd -J values -X --desc-- -d _tmpd -a _tmpm
---
> +_describe:134> compadd -J values -x --desc-- -d _tmpd -a _tmpm
60c66
< +_describe:68> _next_label values _expl desc
---
> +_describe:68> _next_label -x values _expl desc
%

The problem here looks to me that compadd -x *always* adds a header,
even when used with -D, whereas compadd -X does *not* add a header
when used with -D (since the operation doesn't add any completions).
And because compadd treats -2 -o nosort -J values -x --desc-- as a
different namespace from -J values -x --desc--, the header ends up
being added twice.

Which of these two should we consider at fault: _describe or compadd?

It would be trivial to fix in _describe, but I feel like it would be
better to fix in compadd, so this problem cannot possibly occur again.
I find it hard to believe it is ever anyone's intention to add a
visible header when calling compadd -D (or -O or -A).