bug#27820: guix package -u: order of argument is significant

[ludo@gnu.org (Ludovic Courtès)]

Ricardo Wurmus <rekado@elephly.net> skribis:

> Ludovic Courtès <ludo@gnu.org> writes:
>
>> Mark H Weaver <mhw@netris.org> skribis:
>>
>>> I agree that this is quite confusing.  Perhaps we should issue a warning
>>> if the regexp begins with "-".
>>>
>>> Also, perhaps we should *always* require an argument after "-u", even if
>>> "-u" is at the end of the command line, failing otherwise.  Users would
>>> then learn to always pass an argument to "-u", and thus would be less
>>> likely to fall into this trap when adding more options after the "-u".
>>
>> I’m in favor of the former:
>>
>> diff --git a/guix/scripts/package.scm b/guix/scripts/package.scm
>> index 8da7a3fd3..b6133b6af 100644
>> --- a/guix/scripts/package.scm
>> +++ b/guix/scripts/package.scm
>> @@ -486,6 +486,11 @@ Install, remove, or upgrade packages in a single transaction.\n"))
>>                               arg-handler))))
>>           (option '(#\u "upgrade") #f #t
>>                   (lambda (opt name arg result arg-handler)
>> +                   (when (string-prefix? "-" arg)
>> +                     (warning (G_ "upgrade regexp '~a' looks like a \
>> +command-line option~%")
>> +                              arg)
>> +                     (warning (G_ "is this intended?~%")))
>>                     (let arg-handler ((arg arg) (result result))
>>                       (values (alist-cons 'upgrade arg
>>                                           ;; Delete any prior "upgrade all"
>>
>> Thoughts?
>
> This seems good to me.  I just wonder if there are legitimate cases
> where a package regexp would look like a command line option.  If that’s
> not the case could we just “unread” the argument and parse it as the
> next option?

I thought about it but in theory “-” is perfectly legitimate, so I
thought we’d rather not try to be smart.  Thoughts?

Ludo’.