Re: [PATCH v4 9/9] checkout & worktree: introduce checkout.defaultRemote

Hi Ævar,

Sorry for chiming in late. I have a couple of thoughts:

    (
        cd /tmp &&
        rm -rf 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'

I thought master is already there after the clone operation and
you'd merely switch back to the local branch that was created at
clone time?

    $ git clone git@github.com:trast/tbdiff.git && cd tbdiff
    $ git branch
    * master
    $ cat .git/config
...
[branch "master"]
    remote = origin
    merge = refs/heads/master

But the observation is right, we get that message. When do we
do the setup for the master branch specifically?

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

    (
        cd /tmp &&
        rm -rf 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 (without the advice output added earlier in this series):

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

The new checkout.defaultRemote 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".

Also adjust the advice.checkoutAmbiguousRemoteBranchName message to
mention this new config setting to the user, the full output on my
git.git is now (the last paragraph is new):

    $ ./git --exec-path=$PWD checkout master
    error: pathspec 'master' did not match any file(s) known to git.
    hint: The argument 'master' matched more than one remote tracking branch.
    hint: We found 26 remotes with a reference that matched. So we fell back
    hint: on trying to resolve the argument as a path, but failed there too!
    hint:
    hint: Perhaps you meant fully qualify the branch name? E.g. origin/<name>

s/meant fully/meant to fully/
s/? E.g./?\nFor example/

    hint: instead of <name>?

In builtin/submodule--helper.c there is get_default_remote() which also
hardcodes "origin". I think that is a safe thing to do.

    hint:
    hint: If you'd like to always have checkouts of 'master' prefer one remote,
    hint: e.g. the 'origin' remote, consider setting checkout.defaultRemote=origin
    hint: in your config. See the 'git-config' manual page for details.

his new setting elevates one remote over all others, which may
be enough for most setups and not confusing, too.
Consider the following:

    git clone https://kernel.googlesource.com/pub/scm/git/git && cd git
    git remote add gitster https://github.com/gitster/git
    git remote add interesting-patches https://github.com/avar/git
    git remote add my-github https://github.com/stefanbeller/git

    git checkout master

This probably means I want to have origin/master (from kernel.org)

    git checkout ab/checkout-implicit-remote

This probably wants to have it from gitster/ (as it is not found on kernel.org);
I am not sure if it would want to look at interesting-patches/ that mirrors
github, but probably if it were not to be found at gitster.

So maybe we rather want a setup to give a defined priority for
the search order:

  git config dwim.remoteSearchOrder origin gitster avar

Stepping back a bit, there is already an order in the config file
for the remotes, and that order is used for example for 'fetch --all'.

I wonder if we want to take that order? (Or are the days of hand
editing the config over and this is too arcane? We would need a
config command to re order remotes). Then we could just have a
boolean switch to use the config order on ambiguity.
Although you might want to have a different order for fetching
and looking for the right checkout.

I considered splitting this into checkout.defaultRemote and
worktree.defaultRemote, 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.defaultRemoteForCheckout?).

  core.dwimRemote ? It's a bit cryptic, though.

See also 70c9ac2f19 ("DWIM "git checkout frotz" to "git checkout -b
frotz origin/frotz"", 2009-10-18) which introduced this DWIM feature
to begin with, and 4e85333197 ("worktree: make add <path> <branch>
dwim", 2017-11-26) which added it to git-worktree.

Stefan