Hello,
On Tue, Feb 28, 2023 at 12:14:41PM -0700, Jonathan Corbet wrote:
> Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx> writes:
>
> > From: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>
> >
> > The "^0" doesn't have the described effect to only do fast-forward merges.
> > For example
> >
> > git checkout 055efab3120b
> > git merge v5.2-rc1^0
> >
> > creates a normal merge commit. In fact "v5.2-rc1^0" only refers to the
> > commit the tag v5.2-rc1 points to.
>
> So that pattern came straight from Linus, and it still works fine for me
> - just tried it and got the expected fast-forward.
Yes, git merge v5.2-rc1^0 creates a ff when done on a branch that is
fully merged into v5.2-rc1. But then so does
git merge v5.2-rc1
, the "^0" has no influence there. In the example from my commit log
(that doesn't result in a ff) the only difference is the generated
commit log for the non-ff merge. At least for me I get
Merge commit 'v5.2-rc1^0' into HEAD
with the ^0, and if I drop the ^0 I get:
Merge tag 'v5.2-rc1' into HEAD
Linux 5.2-rc1
and a valid signature. (So I'd say the variant without ^0 is better.)
> Maybe you have something in your git configuration that makes things
> behave differently?
I think the behaviour for me is the same as for you. "git merge
v5.2-rc1^0" isn't wrong per se, it does the right thing in the described
situation. But that's not because of the ^0.
> > Fixes: d95ea1a4e1fb ("docs: Add a document on repository management")
> > Signed-off-by: Uwe Kleine-König <uwe@xxxxxxxxxxxxxxxxx>
> > ---
> > Documentation/maintainer/rebasing-and-merging.rst | 6 +-----
> > 1 file changed, 1 insertion(+), 5 deletions(-)
> >
> > diff --git a/Documentation/maintainer/rebasing-and-merging.rst b/Documentation/maintainer/rebasing-and-merging.rst
> > index 09f988e7fa71..85800ce95ae5 100644
> > --- a/Documentation/maintainer/rebasing-and-merging.rst
> > +++ b/Documentation/maintainer/rebasing-and-merging.rst
> > @@ -213,11 +213,7 @@ point rather than some random spot. If your upstream-bound branch has
> > emptied entirely into the mainline during the merge window, you can pull it
> > forward with a command like::
> >
> > - git merge v5.2-rc1^0
> > -
> > -The "^0" will cause Git to do a fast-forward merge (which should be
> > -possible in this situation), thus avoiding the addition of a spurious merge
> > -commit.
> > + git merge --ff-only v5.2-rc1
> >
>
> Git was fixed a couple of years or so ago to do the fast-forward by
> default when it can, so the original advice in this file is unnecessary
> - as is --ff-only (most of the time). So the patch is worth applying,
> but I may tweak the changelog some.
I think mentioning --ff-only is good, because then git merge does the
right thing independant of the configuration. And it errors out if a ff
merge is not possible.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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