Re: diff-index --cc no longer permitted, gitk is now broken (slightly)

Sergey Organov [off-list ref] writes:

I'm afraid this issue is left up in the air after application of the
fix-up patch, as usage of --cc in the diff-index is still undocumented.

Yeah, I do think documentation update is needed, but being buried by
other topics I haven't had a chance to revisit the way how --cc is
described in the wider context in order to make an intellgent
suggestion on how to present it in the context of "diff-index".

I.e., the fix-up just restores the historical status quo that has a
problem by itself.

I do agree "show -p" on merge is an oddball that trips new people,
because it does not imply the "do present the changes for merges"
bit unlike "show -c/--cc" do, and from that point of view, the
generalization --diff-merges tried to bring us was a good thing.

But "-c/--cc" are explicit enough in what they want to do.  It does
want to present the changes to compare a single end state with
possibly more than one starting state (e.g. a merge) and not
requiring an explicit "-m" is quite natural.  Even more, when it
compares the end state with only one starting state (e.g. showing a
single parent commit), there is only one pairwise result to
"combine", so it is also natural that it ends up showing the same
output as "-p".  So I do not quite see the behaviour of "diff*/show
--cc" as a problem, though.  IOW, the use pattern in gitk is more
than just "historical status quo", but is quite sensible, I would
have to say.

Thanks.