progcomp_alias bash option does not work due to 'complete -F _completion_loader -D'

[bubbleguuum]

Programmable completion on expanded aliases (shopt +s progcomp_alias) does not work when there is a 'complete -D' rule. I would be nice to have this working. this would for example allow this scenario to work:

shopt +s progcomp_alias
alias ss='systemctl start'
ss <TAB>
<shows completion for 'systemctl start'  (that is: a list of services), instead of regular file completion>

Also see: https://lists.gnu.org/archive/html/bug-bash/2019-01/msg00101.html

[scop]

If you prefer to work without dynamic completion loading, I suppose you could do a complete -r -D after bash_completion has been loaded to get rid of it. Then perhaps load the desired completions you want to be available by manually/explicitly sourcing them from the completions dir.

Even though it's of less importance nowadays with disks being a lot faster than they used to be, I still think that dynamic loading is a pretty essential thing to have, and don't think it would be time to let go of that in the default project config here.

Can you think of a way we could make things better for the mentioned use case without sacrificing dynamic loading?

[bubbleguuum]

I'm not familiar with _completion_loader and how it works but I wondered if would be possible to have an operating mode where all the dynamic completions would be preemptively loaded, thus not needing the complete -D rule ?

[scop]

I'd rather not encourage that way or spend time on it. And on the other hand, I don't think we can make it much more compact for users to use than what's currently already possible (I presume, untested):

complete -r -D
for f in $(pkg-config --variable=completionsdir bash-completion); do . $f; done
# or use direct hardcoded path if you like, or cat everything and source /dev/stdin or ...

[bubbleguuum]

Confirming that it works, though it takes around 1.5s loading about 950 completions (files) on a fast machine. So inefficient and not really a good idea. A more realistic solution is to complete -r -D then selectively load completions that I actually use.