Re: [PATCH] revision: --ancestry-path

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

Junio C Hamano <gitster@pobox.com> writes:

> I am reasonably sure that parents (specifically, "rewrite_parents") is
> broken.  The new function should cull parents that do not appear on the
> ancestry path from merges (that is what "NEEDSWORK" is about).  It may or
> may not break gitk, though---these off-path parents are shown as parents
> of an on-path merge but will be marked as UNINTERESTING.

Thinking about it a bit more, I think this is Ok, as all the ancestors on
a side branch that is off-path are marked uninteresting, and we do show
uninteresting parents in the output of an interesting commit.  In fact, if
you do "rev-list --parents HEAD^..HEAD -- .", on a non-merge non-empty
commit, you will see uninteresting HEAD^ shown as the parent of HEAD.

> This is not a new problem, but I strongly suspect that cherry-pick is
> broken the same way wrt "rewrite_parents".

This is a different and a real issue.  By marking ones that are duplicate
of commits from the other side as SHOWN, we will spit out a disconnected
history.  It should rewrite the parent list so that children of a commit
that is removed due to being a duplicate from the other side point at an
ancestor of that removed commit to keep the history connected.