Re: [PATCH 2/3] builtin/fetch: parse recurse-submodules-default at default options parsing

[Stefan Beller <sbeller@google.com>]

On Fri, Jun 23, 2017 at 3:36 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Stefan Beller <sbeller@google.com> writes:
>
>> @@ -1333,10 +1336,8 @@ int cmd_fetch(int argc, const char **argv, const char *prefix)
>>               deepen = 1;
>>
>>       if (recurse_submodules != RECURSE_SUBMODULES_OFF) {
>> -             if (recurse_submodules_default) {
>> -                     int arg = parse_fetch_recurse_submodules_arg("--recurse-submodules-default", recurse_submodules_default);
>> -                     set_config_fetch_recurse_submodules(arg);
>> -             }
>> +             if (recurse_submodules_default != RECURSE_SUBMODULES_DEFAULT)
>> +                     set_config_fetch_recurse_submodules(recurse_submodules_default);
>
> This is not a new thing, and it may not even be a problem, but I
> have to wonder why this needs to be done conditionally.  "The
> command line did not explicitly say --no-recurse-submodules, so we
> would set what came from --recurse-submodule-default if and only if
> that is given---otherwise we leave it as a compiled-in default" is
> what the code before or after this patch tells me.  But if we drop
> the "if (default is not DEFAULT)", the resulting code becomes "The
> command line did not explicitly say --no-recurse-submodules, so we
> would set whatever is the default (which may not have been given
> from the command line, but came built-in to the binary)".  Aren't
> they saying the same thing?

I assumed so as well, yes. But the test suite pointed out there
is another subtlety going on, which I have not dug into, yet.

>
> It's not like there is a configuration knob that further interferes
> the interaction between these two.  I am puzzled.

As far as I suspect, the original author considered
evaluating the additional config too expensive.

    gitmodules_config(); // <- this specifically?
    git_config(submodule_config, NULL);

And that is why we only react if any switch is
given to recurse. Before be254a0ea9 (Add the
'fetch.recurseSubmodules' config setting, 2010-11-11)
we would not load the config unless the user
asked for submodule action.

Then with the config switch we *had* to load the config
(both .gitmodules as well as .git/config), so at that commit
it would have made sense to inline this into the regular config
and command line argument parsing.