Completion doesn't work "properly" when it is aliased - bash

Question

I'm on Ubuntu 16.04 LTS with bash v4.3.46.
I set an alias "p" to "python3". By writing this in .bashrc
alias p='python3'
Problem:
Completion doesn't work properly when aliased. (It shows in-executable files for python, too)
$p <tab>
a.py a.txt b.py b.txt c.txt hoge/
Compared with normal command: (This only shows executable files)
$python3 <tab>
a.py b.py hoge/
What I tried:
When I checked the completion for python3,
$complete -p python3
complete -F _python python3
Therefore, I added the following in .bashrc
complete -F _python p
And now, I got:
$complete -p p
complete -F _python p
It seems to be working, however, I got the same result as the beginning.
------- Added --------
I found the definition of _python at /usr/share/bash-completion/completions/python3
# bash completion for python -*- shell-script -*-
_python_modules()
{
COMPREPLY+=( $( compgen -W "$( ${1:-python} -c 'import pkgutil
for mod in pkgutil.iter_modules(): print(mod[1])' )" 2>/dev/null -- "$cur" ) )
}
_python()
{
local cur prev words cword
_init_completion || return
case $prev in
-'?'|-h|--help|-V|--version|-c)
return 0
;;
-m)
_python_modules "$1"
return 0
;;
-Q)
COMPREPLY=( $( compgen -W "old new warn warnall" -- "$cur" ) )
return 0
;;
-W)
COMPREPLY=( $( compgen -W "ignore default all module once error" \
-- "$cur" ) )
return 0
;;
!(?(*/)python*([0-9.])|-?))
[[ $cword -lt 2 || ${words[cword-2]} != -#(Q|W) ]] \
&& _filedir
;;
esac
# if '-c' is already given, complete all kind of files.
local i
for (( i=0; i < ${#words[#]}-1; i++ )); do
if [[ ${words[i]} == -c ]]; then
_filedir
fi
done
if [[ "$cur" != -* ]]; then
_filedir 'py?([co])'
else
COMPREPLY=( $( compgen -W '$( _parse_help "$1" -h )' -- "$cur" ) )
fi
return 0
} &&
complete -F _python python python2 python3
# ex: ts=4 sw=4 et filetype=sh
editing this seems to be fine.
Could you tell me how shoud I edit this?
To edit this, I need sudo, is there any other way that doesn't use sudo?
Thank you.

Answer 1

The problem is that this case statement: !(?(*/)python*([0-9.])|-?)) is restricting the tab completion to only aliases/commands that have the word python in them.
If you change that case statement to be: !(*|-h)) or even !(p|-h)) then your autocomplete should work.
I would personally just add the modified code to my .bashrc... something like the following, just renaming the functions and doing the aliasing:
# bash completion for python -*- shell-script -*-
_python_modules_cust()
{
COMPREPLY+=( $( compgen -W "$( ${1:-python} -c 'import pkgutil
for mod in pkgutil.iter_modules(): print(mod[1])' )" 2>/dev/null -- "$cur" ) )
}
_python_cust()
{
local cur prev words cword
_init_completion || return
case $prev in
-'?'|-h|--help|-V|--version|-c)
return 0
;;
-m)
_python_modules_cust "$1"
return 0
;;
-Q)
COMPREPLY=( $( compgen -W "old new warn warnall" -- "$cur" ) )
return 0
;;
-W)
COMPREPLY=( $( compgen -W "ignore default all module once error" \
-- "$cur" ) )
return 0
;;
!(*|-?))
[[ $cword -lt 2 || ${words[cword-2]} != -#(Q|W) ]] \
&& _filedir
;;
esac
# if '-c' is already given, complete all kind of files.
local i
for (( i=0; i < ${#words[#]}-1; i++ )); do
if [[ ${words[i]} == -c ]]; then
_filedir
fi
done
if [[ "$cur" != -* ]]; then
_filedir 'py?([co])'
else
COMPREPLY=( $( compgen -W '$( _parse_help "$1" -h )' -- "$cur" ) )
fi
return 0
} &&
alias p='python3' &&
complete -F _python_cust p
# ex: ts=4 sw=4 et filetype=sh