Re: [PATCH v2] checkout & worktree: introduce checkout.implicitRemote

On Thu, May 3, 2018 at 3:18 PM, Ævar Arnfjörð Bjarmason
[off-list ref] wrote:

Introduce a checkout.implicitRemote setting which can be used to
designate a remote to prefer (via checkout.implicitRemote=origin) when
running e.g. "git checkout master" to mean origin/master, even though
there's other remotes that have the "master" branch.

I want this because it's very handy to use this workflow to checkout a
repository and create a topic branch, then get back to a "master" as
retrieved from upstream:

    (
        rm -rf /tmp/tbdiff &&
        git clone git@github.com:trast/tbdiff.git &&
        cd tbdiff &&
        git branch -m topic &&
        git checkout master
    )

That will output:

    Branch 'master' set up to track remote branch 'master' from 'origin'.
    Switched to a new branch 'master'

But as soon as a new remote is added (e.g. just to inspect something
from someone else) the DWIMery goes away:

    (
        rm -rf /tmp/tbdiff &&
        git clone git@github.com:trast/tbdiff.git &&
        cd tbdiff &&
        git branch -m topic &&
        git remote add avar git@github.com:avar/tbdiff.git &&
        git fetch avar &&
        git checkout master
    )

Will output:

    error: pathspec 'master' did not match any file(s) known to git.

The new checkout.implicitRemote config allows me to say that whenever
that ambiguity comes up I'd like to prefer "origin", and it'll still
work as though the only remote I had was "origin".

I considered splitting this into checkout.implicitRemote and
worktree.implicitRemote, but it's probably less confusing to break our
own rules that anything shared between config should live in core.*
than have two config settings, and I couldn't come up with a short
name under core.* that made sense (core.implicitRemoteForCheckout?).

I wonder if it's difficult to add a dwim hook that allows us to
replace the entire dwim logic with a hook? Doing this "preferring
origin" in a shell script should be easy and it lets us play more with
tweaking dwim logic. (Yeah sorry I'm getting off topic again)
-- 
Duy