Re: [RFC][StGit PATCH] Add support for merge-friendly branches

> 2009/5/28 Karl Hasselström <kha@treskal.com>:
>
> > On 2009-05-28 12:12:42 +0100, Catalin Marinas wrote:
> >
> > > The patch proposes a new StGit command called "publish". This
> > > command allows one to develop patches normally on a StGit branch
> > > but publish the stack changes to a separate, merge-friendly
> > > branch whose history is not re-writable.
> >
> > Hmm, interesting. I don't think I'd want to use a command like
> > this myself, but I can see how it might be useful.
>
> For me it is useful. I publish a kernel tree with over 100 patches.
> Later I find that one patch is buggy. The current merge-friendly
> solution is to add another patch but I may want to just update the
> buggy patch as it's easier when time comes to submit upstream. This,
> however, rewrites the history. So with the "publish" command I just
> generate another commit on top of the public branch and I always end
> up with the same tree as on my stack.

> > Hmm. Couldn't the merge base conceivably be higher up in the
> > stack? Like, right at the beginning, don't we have public_head ==
> > stack.head? That would be caught by the "same tree" check" a bit
> > earlier, but after adding another patch, don't we have public_head
> > == stack.head^ ? Which would give merge_base == public_head.
>
> We could have public_head == stack.head^... but that's not an issue.
> The merge_base above is checked against the base of the stack rather
> than the top as we assume that the base isn't volatile. So even if
> public_head is the same as some patch commit, the merge_base above
> would always be the base of the stack. Only if the stack base was
> updated, we get a different merge_base (equal to the previous stack
> base).