Re: [PATCH v2] var: add GIT_DEFAULT_BRANCH variable

> On 2021-11-02 17:53+0100, Ævar Arnfjörð Bjarmason wrote:
>> On Tue, Nov 02 2021, Thomas Weißschuh wrote:
>> 
>> > Introduce the builtin variable GIT_DEFAULT_BRANCH which represents the
>> > the default branch name that will be used by git-init.
>> >
>> > Currently this variable is equivalent to
>> >     git config init.defaultbranch || 'master'
>> >
>> > This however will break if at one point the default branch is changed as
>> > indicated by `default_branch_name_advice` in `refs.c`.
>> >
>> > By providing this command ahead of time users of git can make their
>> > code forward-compatible.
>> >
>> > Co-developed-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
>> > Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
>> > ---
>> >
>> > Changes from v1 ( https://lore.kernel.org/git/20211030140112.834650-1-thomas@t-8ch.de/ ):
>> > * Replaced the custom subcommand with an internal variable
>> > * Cleaned up the tests
>> >
>> > @Johannes: I replaced BUG() with die() from your example because that seems to be
>> > nicer for user facing messages.
>> >
>> >  Documentation/git-var.txt |  3 +++
>> >  builtin/var.c             | 13 +++++++++++++
>> >  t/t0007-git-var.sh        | 19 +++++++++++++++++++
>> >  3 files changed, 35 insertions(+)
>> >
>> >  
>> > +static const char *default_branch(int flag)
>> > +{
>> > +	const char *name = repo_default_branch_name(the_repository, 1);
>> > +
>> > +	if (!name)
>> > +		die("could not determine the default branch name");
>> 
>> Isn't this die() unrechable given the similar logic in
>> repo_default_branch_name()? Hence the previous BUG(...)?
>
> Ok. Good point.
>
>> I really don't see how it makes sense to add this to "git var", we have
>> that to correspond to environment variables we use.
>> 
>> *Maybe* if we renamed GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME to
>> GIT_INITIAL_BRANCH_NAME and made it a non-test thing like
>> GIT_TEMPLATE_DIR, but even then shouldn't we be adding
>> "GIT_TEMPLATE_DIR" and any number of other things to this as well?
>> 
>> I'm not saying that your patch needs to do that, but we really should
>> think about the interface & future implications if we're going in this
>> direction.
>> 
>> The reason I suggested extending "git config" in [1] is because it seems
>> like a natural thing for "git config" to learn to spew out our idea of
>> default hardcoded config values to the user.
>> 
>> But creating a variable form of that existing config just so we can have
>> "git var" spew it out just seems weird.
>> 
>> We don't have or need such a variable now for anything else, so why go
>> through that indirection, instead of something that closes the feature
>> gap of asking what a config variable default is?
>> 
>> In any case whatever we do here this really should be updating the
>> documentation of init.defaultbranch & the relevant bits in the "git
>> init" manpage to add cross-references, similar to how we discuss
>> GIT_TEMPLATE_DIR now.
>>
>> 1. https://lore.kernel.org/git/211030.86ilxe4edm.gmgdl@evledraar.gmail.com/
>
> I'll then wait for a consensus of the git devs. The actual implementation
> shouldn't be the issue afterwards.
>
> Thanks for looking into this!