Re: [PATCH] revisions: add @{default} shorthand for default branch

[Junio C Hamano <gitster@pobox.com>]

Harald Nordgren <haraldnordgren@gmail.com> writes:

>> After cloning an upstream project, those who dislike the local
>> branch name 'master' often rename it to something else, like 
>> 
>>     $ git branch -m master main
>
> I have never heard about anyone doing that. Isn't it more expected that
> people keep whatever branch is on the remote? But regardless, I hope
> there is a way to still make @{default} map to whatever your renamed your
> default branch to.

But then that is what "default" is, isn't it?  The "default" branch
is what "git init" would create unless it is told otherwise.  The
'main' branch that the above example user renamed to to use because
they did not like the name 'master' is their primary branch that is
not the "default".

In a sense, I think what you are after _is_ "what the user considers
the primary branch in this repository".  How init.defaultBranch is
configured in their global (i.e., per-user) configuration file may
be a good hint to help answering the question, but not necessarily.

For those who follow the naming the upstream decided to use in
cloned repositories, init.defaultBranch is probably the last thing
you want to take as a hint, as these people decided to _ignore_ the
preference of their own and instead to follow what upstream uses.
For that, refs/remotes/origin/HEAD would be a lot more stronger
hint.  If they call their primary branch 'trunk', these people would
want to call theirs 'trunk'.  And for that, these people would not
do anything with init.defaultBranch.

>     git checkout $(git symbolic-ref refs/remotes/origin/HEAD | sed 's@^refs/remotes/origin/@@')
>
> That's uneccessary overhead, that could now be replaced with:
>
>     git checkout @{default}

That mirrors what I wrote in the previous paragraph.  Those who
follow the naming the upstream uses, refs/remotes/$remote/HEAD
(here, "origin" may not be the default remote) would be a better
hint than init.defaultBranch so calling it @{default} is misleading.

I am not good at naming things, so instead of calling it @{primary}
let's call it @{dumbo}.  With the realization that what branch
refs/remotes/$remote/HEAD points at is a good source of hint, I
actually think $branch@{dumbo} does make sense, and @{dumbo} should
be a short-hand for $branch@{dumbo} where the name of the current
branch is substituted for $branch (i.e. similar to @{push}, I
suppose).  As you may be interacting with two sets of branches that
go to two different remotes.

In any case, it is very different from what you implemented as the
@{default} in your patch.

Thanks.