Complete stdin "-" in file locations, add more options that allow it

[yedayak]

Every option that reads files using @ allow also - for stdin

[scop]

No strong opinions, but I suppose we could simplify/optimize this to the following unless we see downsides to doing that? WDYT, and @akinomyoga too?

Suggested change

	_comp_compgen -a -c "${cur:1}" -- -W '-'
	[[ $cur == @?(-) ]] && COMPREPLY+=(-)

[akinomyoga]

Hmm, although it is functionally equivalent, I prefer using _comp_compgen which is more idiomatic.

It takes time for me to understand that [[ $cur == @?(-) ]] && COMPREPLY+=(-) is functionally equivalent to _comp_compgen -ac "${cur:1}" -- -W '-' and doesn't have a bug nor an extra intentional effect.

[akinomyoga]

There seem to be both types of existing cases:

./completions/7z:59:            _comp_compgen -c "${cur:4}" -- -P"${cur:0:4}" -W '-'
./completions/curl:144:            _comp_compgen -- -W '-'
./completions/gpgv:35:                _comp_compgen -- -W '-'
./completions/iperf:55:            _comp_compgen -- -W 'C'
./completions/pack200:35:            _comp_compgen -- -W '-'
./completions/pdftotext:32:            _comp_compgen -- -W '-'
./completions/puppet:160:                    _comp_compgen -- -W '-'
./completions/tshark:97:            _comp_compgen -- -W 'n'
./completions/unpack200:19:            _comp_compgen -- -W '-'

./completions/cppcheck:38:            [[ ! $cur || $cur == - ]] && COMPREPLY+=(-)
./completions/mr:46:                    COMPREPLY+=(-)
./completions/nslookup:59:        [[ $REPLY -eq 1 && $cur == @(|-) ]] && COMPREPLY+=(-)
./completions/patch:24:            [[ ! $cur || $cur == - ]] && COMPREPLY=(-)
./completions/tshark:67:            [[ $cur == @(|-) ]] && COMPREPLY+=(-)
./completions/wget:78:            _comp_compgen_filedir && [[ $cur == - || ! $cur ]] && COMPREPLY+=(-)

[scop]

For me it's the opposite, I'm far from being "natural" with the stuff we've added over the few last releases and have to look up stuff a lot, almost certainly because I haven't been writing all that much code in this project lately, whereas straight bash is much easier for me. But I'm fine with those who are doing most of the actual work these days getting to decide the flavor. Would not hurt to be consistent with it though through the whole tree.

Pre-approved either way you guys decide.

[yedayak]

I don't really mind either, I think the second option is easier to read without context, but the first one makes more sense here since it follows the same pattern as the line before it.

[akinomyoga]

I again thought about it, but I think it is still better to generate completions through _comp_compgen even in simple cases because it would be easier to apply changes later in a consistent way (by modifying the behavior of _comp_compgen or by grep'ping the calls of _comp_compgen).