Re: [PATCH v2 0/7] making log --first-parent imply -m

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> You might also consider whether "combined" is actually mutually
> exclusive with parent selection. We have focused on which parents you'd
> want to "-m" against. But in the most general case, you could ask for a
> combined-diff between parents 1 and 3 of an octopus merge.

Yeah, we want to specify a possibly empty set of integers
(1..<num-parents>) to combine the diff; if it is empty set, we won't
see any diff.  If it is full set, we'd get the current c/cc behavior.
Anything in between we cannot currently express.  Fun ;-)

> That's just coming from the angle of "what is the most general and
> orthogonal set of features". I think the vast majority of what anyone
> would want to do would be covered by doing a diff against only a single
> parent, and then it would almost always be the first parent. And
> certainly you'd need to add a bunch of code to the combined diff
> machinery to make it support arbitrary sets of parents. So this probably
> isn't that interesting a direction to go, at least for now. 

Yeah, it is mostly for fun--I do not see an immediate practical use
case, either.

> I'm just
> raising the issue now because we'll be locked into the semantics of this
> option, which may not be able to express the full set of what's possible
> (so we'd be stuck adding another option later).

Yeah, but a good thing is that we won't have to worry about this
until much later, as long as we would just be introducing "diff
against no parents" and nothing else (or together with "diff against
all parents", which would make it easier to explain "-m").