bug#53355: bug#51466: bug#53355: guix shell --check: confusing error message

[Bengt Richter <bokr@bokr.com>]

Sorry to reply to myself, but forgot to illustrate.

On +2022-06-20 12:12:10 +0200, bokr@bokr.com wrote:
> Hi Chris,
[...]
> 
> I have had some mystery bash parsing errors, and I noticed
>     set|less
> shows a heck of a lot of functions defined that I don't
> remember seeing in the past. 
> Anyway, shouldn't stuff like that have better hygiene than just prefixed
> _underscore ? Or maybe set|less doesn't show all that on your system?
>

There are a couple functions without prefixed underscore too,
which invoke some underscore-prefixed ones that look too trusting
of their arguments if you ask me: can someone declare these safe?

    I think I can grok quote () ...
(escape single quotes and enclose result in single quotes, trusting bash state)
But what if I want to define my own function quote?? How would I know I was
overriding this? I really don't like my programming space occupied by unknowns :-(

--8<---------------cut here---------------start------------->8---
quote () 
{ 
    local quoted=${1//\'/\'\\\'\'};
    printf "'%s'" "$quoted"
}
--8<---------------cut here---------------end--------------->8---

    but this one below will take more time than I want to spend on code
I'm not intentionally going to use, and which invites name clashes
in my command name space :-(

--8<---------------cut here---------------start------------->8---
quote_readline () 
{ 
    local quoted;
    _quote_readline_by_ref "$1" ret;
    printf %s "$ret"
}
--8<---------------cut here---------------end--------------->8---

    where the above calls this:

--8<---------------cut here---------------start------------->8---
_quote_readline_by_ref () 
{ 
    if [ -z "$1" ]; then
        printf -v $2 %s "$1";
    else
        if [[ $1 == \'* ]]; then
            printf -v $2 %s "${1:1}";
        else
            if [[ $1 == ~* ]]; then
                printf -v $2 ~%q "${1:1}";
            else
                printf -v $2 %q "$1";
            fi;
        fi;
    fi;
    [[ ${!2} == \$* ]] && eval $2=${!2}
}
--8<---------------cut here---------------end--------------->8---

HTH somehow.
--
Regards,
Bengt Richter