Re: [PATCH v2 07/14] pull: display default warning only when non-ff

[Felipe Contreras <felipe.contreras@gmail.com>]

On Fri, Dec 4, 2020 at 5:24 PM Elijah Newren <newren@gmail.com> wrote:
>
> On Thu, Dec 3, 2020 at 10:16 PM Felipe Contreras
> <felipe.contreras@gmail.com> wrote:
> >
> > There's no need to display the annoying warning on every pull... only
> > the ones that are not fast-forward.
>
> I like this.  :-)
>
> > This requires the tests to pick another base, so the merge is not
> > fast-forward.
> >
> > Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
> > ---
> >  Documentation/git-pull.txt   |  3 +++
> >  builtin/pull.c               |  2 +-
> >  t/t7601-merge-pull-config.sh | 28 +++++++++++++++++-----------
> >  3 files changed, 21 insertions(+), 12 deletions(-)
> >
> > diff --git a/Documentation/git-pull.txt b/Documentation/git-pull.txt
> > index dc812139f4..ad33d2472c 100644
> > --- a/Documentation/git-pull.txt
> > +++ b/Documentation/git-pull.txt
> > @@ -60,6 +60,9 @@ However, a non-fast-foward case looks very different.
> >         origin/master in your repository
> >  ------------
> >
> > +By default `git pull` will warn about these situations, however, most likely
> > +you would want to force a merge, which you can do with `git pull --no-rebase`.
> > +
>
> Everything in this sentence after the first comma seems dangerous to
> me for a number of workflows.

And this is precisely the reason why the default of "git pull" must be
changed to --ff-only (or similar).

But today "git pull" by default is the equivalent of "git pull
--merge". We need to explain to users why the warning is there, and
that "git pull" is doing an implicit "git pull --merge", and if they
do it explicitly they can get rid of the warning.

Later on when the default is changed to --ff-only this text can be
updated to something less dangerous.

But not explaining what "git pull" is doing today by default will not
make it any less dangerous.

> >  Then "`git pull`" will fetch and replay the changes from the remote
> >  `master` branch since it diverged from the local `master` (i.e., `E`)
> >  until its current commit (`C`) on top of `master` and record the
> > diff --git a/builtin/pull.c b/builtin/pull.c
> > index f82e214fc8..f0b1c6bfea 100644
> > --- a/builtin/pull.c
> > +++ b/builtin/pull.c
> > @@ -1013,7 +1013,7 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
> >
> >         can_ff = get_can_ff(&orig_head, &merge_heads.oid[0]);
> >
> > -       if (default_mode && opt_verbosity >= 0 && !opt_ff) {
> > +       if (default_mode && !can_ff && opt_verbosity >= 0 && !opt_ff) {
> >                 advise(_("Pulling without specifying how to reconcile divergent branches is\n"
> >                         "discouraged; you need to specify if you want a merge, or a rebase.\n"
> >                         "You can squelch this message by running one of the following commands:\n"
> > diff --git a/t/t7601-merge-pull-config.sh b/t/t7601-merge-pull-config.sh
> > index 6774e9d86f..6b4adab8b1 100755
> > --- a/t/t7601-merge-pull-config.sh
> > +++ b/t/t7601-merge-pull-config.sh
> > @@ -28,7 +28,7 @@ test_expect_success 'setup' '
> >  '
> >
> >  test_expect_success 'pull.rebase not set' '
> > -       git reset --hard c0 &&
> > +       git reset --hard c2 &&
> >         git -c color.advice=always pull . c1 2>err &&
> >         test_decode_color <err >decoded &&
> >         test_i18ngrep "<YELLOW>hint: " decoded &&
> > @@ -36,54 +36,60 @@ test_expect_success 'pull.rebase not set' '
> >
> >  '
> >
> > -test_expect_success 'pull.rebase not set and pull.ff=true' '
> > +test_expect_success 'pull.rebase not set (fast-forward)' '
> >         git reset --hard c0 &&
> > +       git pull . c1 2>err &&
> > +       test_i18ngrep ! "Pulling without specifying how to reconcile" err
> > +'
> > +
> > +test_expect_success 'pull.rebase not set and pull.ff=true' '
> > +       git reset --hard c2 &&
> >         test_config pull.ff true &&
> >         git pull . c1 2>err &&
> >         test_i18ngrep ! "Pulling without specifying how to reconcile" err
> >  '
> >
> >  test_expect_success 'pull.rebase not set and pull.ff=false' '
> > -       git reset --hard c0 &&
> > +       git reset --hard c2 &&
> >         test_config pull.ff false &&
> >         git pull . c1 2>err &&
> >         test_i18ngrep ! "Pulling without specifying how to reconcile" err
> >  '
> >
> >  test_expect_success 'pull.rebase not set and pull.ff=only' '
> > -       git reset --hard c0 &&
> > +       git reset --hard c2 &&
> >         test_config pull.ff only &&
> > -       git pull . c1 2>err &&
> > +       test_must_fail git pull . c1 2>err &&
>
> It makes sense to me that you'd need test_must_fail here...but why
> wasn't it needed before??  How did this test pass without it before
> this series?

Because before it was a fast-forward (from c0), not so anymore (from
c2); "pull.ff=only" fails if it's not a fast-forward.

Cheers.

-- 
Felipe Contreras