Re: [PATCH] submodule update: run custom update script for initial populating as well

[Stefan Beller <sbeller@google.com>]

On Fri, Jan 13, 2017 at 3:42 PM, Junio C Hamano <gitster@pobox.com> wrote:
> Stefan Beller <sbeller@google.com> writes:
>
>> In 1b4735d9f3 (submodule: no [--merge|--rebase] when newly cloned,
>> 2011-02-17), all actions were defaulted to checkout for populating
>> a submodule initially, because merging or rebasing makes no sense
>> in that situation.
>>
>> Other commands however do make sense, such as the custom command
>> that was added later (6cb5728c43, submodule update: allow custom
>> command to update submodule working tree, 2013-07-03).
>
> Makes sense.
>
>> I am unsure about the "none" command, as I can see an initial
>> checkout there as a useful thing. On the other hand going strictly
>> by our own documentation, we should do nothing in case of "none"
>> as well, because the user asked for it.
>
> I think "none" is "I'll decide which revision of the submodule
> should be there---do not decide it for me".  If the user is
> explicitly saying with "git submodule init" to have "some" version,
> and if the user did not have any (because the user didn't show
> interest in any checkout of the submodule before), then I think it
> probably makes more sense to checkout the version bound to the
> superproject, than leaving the directory empty.
>
>> Reported-by: Han-Wen Nienhuys <hanwen@google.com>
>> Signed-off-by: Stefan Beller <sbeller@google.com>
>> ---
>>  git-submodule.sh            |  7 ++++++-
>>  t/t7406-submodule-update.sh | 15 +++++++++++++++
>>  2 files changed, 21 insertions(+), 1 deletion(-)
>>
>> diff --git a/git-submodule.sh b/git-submodule.sh
>> index 554bd1c494..aeb721ab7e 100755
>> --- a/git-submodule.sh
>> +++ b/git-submodule.sh
>> @@ -606,7 +606,12 @@ cmd_update()
>>               if test $just_cloned -eq 1
>>               then
>>                       subsha1=
>> -                     update_module=checkout
>> +                     if test "$update_module" = "merge" ||
>> +                        test "$update_module" = "rebase" ||
>> +                        test "$update_module" = "none"
>> +                     then
>> +                             update_module=checkout
>> +                     fi
>
> ... which seems to be what you did.  Do we need a documentation
> update, or does this just make the behaviour of this corner case
> consistent with what is already documented?

I think we do not need to update the documentation, because the
documentation doesn't call out the first/initial call to update to be special.
So for a non existing submodule we can do:

    git submodule update --init --[rebase|merge]

and that falls back to checkout, which *looks* like it was a rebase/merge.
The original bug report was that

    $ git config submodule.<name>.update !echo-script.sh
    $ git submodule update <submodule>
    Submodule path '<submodule>': 'echo-script.sh'
    $ rm -rf <submodule>
    $ git submodule update <submodule>
    .. checked out ..

So while I usually think more verbose documentation is a good idea,
this time it's different, as it merely aligns current documented
behavior with reality.

Thanks,
Stefan