Re: [PATCH] merge: allow using --no-ff and --ff-only at the same time

On Mon, Jul 01, 2013 at 08:38:21AM -0700, Junio C Hamano [off-list ref] wrote:

As to "--no-ff" vs "--ff-only", "--ff-only" has always meant "only
fast-forward updates are allowed.  We do not want to create a merge
commit with this operation."  I do agree with you that the proposed
patch changes the established semantis and may be too disruptive a
thing to do at this point.

Hmm, one way around this may be to add a new option that is basically
the same as --no-ff --ff-only (with the patch), except it has a
different name, so it's not confusing. 'git merge --rebase' could be
used for this, but such a name is misleading as well. Anyone has a
better naming idea? :-)

If one were designing Git merge from scratch today, however, I could
see one may have designed these as two orthogonal switches.

 - Precondition on the shape of histories being merged ("fail unless
   fast forward" does not have to be the only criteria);

 - How the update is done ("fast forward to the other head", "always
   create a merge", "fast forward if possible, otherwise merge" do
   not have to be the only three choices).

I do not fundamentally oppose to such a new feature, but they have
to interact sanely with the current "--ff={only,only,never}".

OK, so if I get it right, the problem is that users got used to that
the --ff-only not only means a precondition for the merge, but also
means "either don't create a merge commit or fail", while my patch would
change this second behaviour.

I could imagine then new switches, like 'git merge --pre=ff
--update=no-ff" could provide these, though I'm not sure if it makes
sense to add such generic switches till the only user is "ff".