Re: [PATCH 2/2] diff-merges: introduce '-d' option

Sergey Organov [off-list ref] writes:

quoted

Sounds very straight-forward.

Given that "--first-parent" in "git log --first-parent -p" already
defeats "-m" and shows the diff against the first parent only,
people may find it confusing if "git log -d" does not act as a
shorthand for that.

It doesn't, and I believe it's a good thing, as primary function of
--first-parent is to change history traversal rules, and if -d did that,
it would be extremely confusing.

I am not sure about that.

Also, --first-parent is correctly documented as implying
--diff-merges=first-parent, not as defeating -m.

Yes, exactly.  That makes me even more convinced that the intuitive
behaviour, when we say "we have this great short-hand option that
lets your 'git log' to do the first-parent thing with patch output",
is to do the first-parent traversal _and_ show first-parent patches.

"-d" is documented as a short-hand for "--diff-merges=first-parent
--patch" and not for "--first-parent --patch", so the behaviour may
correctly match documentation, but that does not make the documented
behaviour an intuitive one.  And a behaviour that is not intuitive
is confusing.

If we read resulting documentation with a fresh eye, -d is similar to
--cc, and -c, just producing yet another kind of output, so I think all
this fits together quite nicely and shouldn't cause confusion.

Another thing is that showing first-parent patch for merges while
letting the traversal also visit the second-parent chain is not as
useful an option as it could be, even though it is not so bad as the
original "-m -p" that also showed second-parent patch for merges as
well.  People would have to say "log --first-parent -p" to get the
first-parent traversal with first-parent patch output, and they
would not behefit from having "-d".