[m-rev.] Upgrading Boehm GC, the git way.

[Peter Wang]

On Fri, 17 Oct 2014 17:29:03 +1100, Paul Bone <paul at bone.id.au> wrote:
> 
> Rather than presenting a diff for review, I'd like to present my goals and
> workflow for upgrading Boehm GC for review.  I'm looking for comments on
> whether this is how we should track Boehm GC, as well as a review of the
> process that I've used (attached).
> 
> Now that we use git to manage Mercury, I've attempted to upgrade Boehm GC
> "the git way".  This should be reviewed by someone with a solid
> understanding of git who might see a caveat that I havn't.
> 
> what I've attempted to do here is to import the git history of boehm GC into
> our repository.  Then upgrading git in the future is done by adding the
> boehm_gc repository as a remote, fetching changes, and merging them into our
> master branch.  This may be convenient but the drawback is that we will then
> store Boehm GC's history in our repository, which is not necessary and makes
> the repository larger (I use a local mirror (a bare repository) I wonder if
> other developers do).  I've attached an updated
> compiler/notes/upgrade_boehm_gc.html file that documents the process I
> followed, could someone review it please?
> 
> An alternative method to maintain Boehm GC would be to distribute an
> upstream tarball and store in git a set of patches that should be applied to
> the tarball after it is unpacked but before it is built.  This may be more
> difficult to maintain (we won't have git's help when patches conflict after
> upgrading boehm) but it means keeping our repository smaller.

Hi Paul,

I cloned both your repository (74.19 MiB) which has other stuff besides,
and the official repository (70.76 MiB).  The size difference should be
irrelevant.

It's a bit annoying that git log or gitk without any other arguments
will show commits that I'm not really interested in.  From that POV,
I'd rather see all of Boehm GC's commits squashed together.  Perhaps
there is some way to mitigate that problem?

BTW I noticed a couple of problems with the commit
"These are miscellaneous changes made by Fergus Henderson"
  - there is a conflict marker in misc.c.
  - README.debugging comes directly from Boehm GC upstream.

Peter