fix(_umount,feh,sbopkg): check diretory name for _comp_compgen -C

[akinomyoga]

Fixes #1260

This is an alternative fix to #1290. The fix suggested in #1290 was just to remove the error message, which I believe is not the right fix. This PR fixes it by checking the arguments at the caller side.

This includes an additional fix e9e665e for feh. In the current main branch, an error message is printed on the TAB completion with the following command line:

$ set -u
$ feh --font x[TAB] --fontpath
bash: words[i + 1]: unbound variable

[akinomyoga]

Unrelated to the present topic, but I'm wondering about the reasoning for using -f -X "!globpat" instead of simply -G "globpat". In the codebase, we only have two uses of -G globpat:

./completions/mdtool:35:                _comp_compgen -- -o filenames -G"*.mds"
./completions/rcs:24:    _comp_compgen -aR -- -G "$dir/$file*,v"

while we have many for -f -X "!globpat":

./completions/explodepkg:3:complete -o plusdirs -f -X '!*.t[bglx]z' explodepkg
./completions/feh:32:            # _comp_compgen -C "$font_path" -- -f -X "!*.@([tT][tT][fF])" -S /
./completions/feh:38:                            -f -X "!*.@([tT][tT][fF])" -S /
./completions/gdb:41:        _comp_compgen -a -- -f -X '!?(*/)core?(.?*)' -o plusdirs
./completions/java:87:            _comp_compgen -av tmp -c "$i/$cur" -- -f -X '!*.class'
./completions/lzip:47:    _comp_compgen -- -f -X "*.lz" -o plusdirs
./completions/sbopkg:67:        _comp_compgen -aC "$QUEUEDIR" -- -f -X "!*.sqf"
./completions/_slackpkg:68:                _comp_compgen -C "$confdir/templates" -- -f -X \
                    "!?*.template" && COMPREPLY=("${COMPREPLY[@]%.template}")
./completions/upgradepkg:18:        _comp_compgen -- -P "$prev%" -f -X "!*.@(t[bgxl]z)" || nofiles=set

edit: One possibile explanation is that they derived from the pattern -f -X "$_xspec" used in _comp_compgen_filedir. In that case, we can probably use -G.

edit: I also checked the history of the support for -G by the compgen builtin, but the option -G seems to have existed from the beginning when compgen was introduced in Bash 2.04 (1999).

[akinomyoga]

They were introduced in the following commits, where I don't find any discussions about using -f -X over -G.

• explodepkg, upgradepkg c340b7d
• feh c7b9d08
• gdb f815736
• java 920b1f9
• lzip f09ced6
• sbopkg b346174
• _slackpkg b346174

[akinomyoga]

I also think the following @(...) are not needed (where ... does not contain |):

./completions/feh:32:            # _comp_compgen -C "$font_path" -- -f -X "!*.@([tT][tT][fF])" -S /
./completions/feh:38:                            -f -X "!*.@([tT][tT][fF])" -S /
./completions/upgradepkg:18:        _comp_compgen -- -P "$prev%" -f -X "!*.@(t[bgxl]z)" || nofiles=set
./completions/valgrind:10:        if [[ ${words[i]} != @([-=])* ]]; then

[yedayak]

I also think the following @(...) are not needed (where ... does not contain |):

./completions/feh:32:            # _comp_compgen -C "$font_path" -- -f -X "!*.@([tT][tT][fF])" -S /
./completions/feh:38:                            -f -X "!*.@([tT][tT][fF])" -S /
./completions/upgradepkg:18:        _comp_compgen -- -P "$prev%" -f -X "!*.@(t[bgxl]z)" || nofiles=set
./completions/valgrind:10:        if [[ ${words[i]} != @([-=])* ]]; then

Yeah, it would be nicer like that

About -f -X vs -G, I don't really have a strong opinion, but seems fine to change where possible to -G (note the lzip example you showed doesn't have a !)

[akinomyoga]

Thank you! I'll submit the fixes later.

[scop]

Re the redundant @(...), filed mvdan/sh#1137

[akinomyoga]

As for -f -X '!pat' vs -G 'pat', there does seem to be a difference. Although they are consistent when it generates the filename in the current directory:

$ compgen -G '*.md'
CHANGELOG.md
CONTRIBUTING.md
README.md
style.md
$ compgen -f -X '!*.md'
README.md
CONTRIBUTING.md
CHANGELOG.md
style.md

they produce different results when they are used to generate completions in a subdirectory:

$ compgen -G '*.md' -- doc/
CHANGELOG.md
CONTRIBUTING.md
README.md
style.md
$ compgen -f -X '!*.md' -- doc/
doc/api-and-naming.md
doc/styleguide.md
doc/testing.md
doc/configuration.md

(This hidden part was my misunderstanding)

We may still write it as

$ cur=doc/
$ compgen -G '*.md' -P "${cur%%+([^/])}" -- "$cur"
doc/CHANGELOG.md
doc/CONTRIBUTING.md
doc/README.md
doc/style.md

but it is even more non-trivial than -f -X '!pat'.

edit: The -G option only generates the filenames in the current directory even when we try to generate the filenames in a subdirectory. In addition, the filtering by cur does not seem to be applied to the completions generated by -X.