setup-*.exe --help default explanation re -D/-L options [Was: [ANNOUNCEMENT] Updated: setup (2.917)]

[Adam Dinwoodie <adam@dinwoodie.org>]

On  Mon, 31 Jan 2022 12:56:13 -0700, Brian Inglis wrote:
> On 2022-01-31 08:46, Andrey Repin wrote:
> > Greetings, Jon Turney!
> > 
> > > Probably what's wanted is to remember the state of those checkboxes, if
> > > this isn't the first time setup has been run?
> > 
> > That's a feature silently longed for for a loong time. :) But this is such a
> > low priority, very few people actually mentioned it in the past years.
> 
> It could usefully be added similarly to last-action:
> 
> 	$ fgrep -A1 action /etc/setup/setup.rc
> 	last-action
> 		Download,Install
> 
> last-shortcut:
> 	Desktop|StartMenu|none,...

This reminded me of a bug report I've been meaning to properly
characterise and report for a while, and also pointed me at a
workaround...

Currently, running `setup-*.exe --help` produces output that includes
the following:

    -D --download       Download packages from internet only
    -L --local-install  Install packages from local directory only

    The default is to both download and install packages, unless either
    --download or --local-install is specified.

I think the descriptions for the `-D` and `-L` options are misleading,
at least in combination with that final line, which is definitely wrong.
As I understand it, the actual behaviour would be better described by
something like the below:

    -D --download       Download packages from internet only, unless -L
                        is also specified
    -L --local-install  Install packages from local directory only,
                        unless -D is also specified

    If neither --download nor --local-install is specified, the default
    is to repeat the same action as from the previous run.  If no
    previous run can be found, the default is to perform both actions,
    and both actions can be explicitly requested by specifying both
    --download and --local-install.

In particular, the fact that the two options currently say they will
"only" do their action, and that the default is to perform both, lead me
to believe (a) the options were mutually exclusive and one would
presumably override the other, (b) this was probably a legacy from
before setup.rc stored the previous action, and therefore (c) if I was
running setup with `-q` or `-M`, there was no way to get the supposedly
default "do both" behaviour; I'd instead need to go through the full
GUI.

Having now seen how this setting is stored, I've realised I can just
call setup with `-DL` and it'll perform both actions again.  But I think
my assumption that "default" was supposed to mean "default always" not
"default only on first run" wasn't *entirely* PEBCAK (even if it mostly
was), so that help text would definitely benefit from being made a bit
more explicit.

(I'm aware my suggestion above is decidedly wordy; it's not intended to
be exactly what I think is required, only a first pass at clarifying the
key details I think are missing.)