[PATCH] D53414: Add instructions for migrating branches from one git repository to another.

[David Greene via Phabricator via llvm-commits]

greened added inline comments.


================
Comment at: llvm/docs/Proposals/GitHubMove.rst:938-943
+Multirepo to Monorepo, With Merges
+----------------------------------
+
+If you have a branch on an old *multirepo* and have merges, you'll want to
+follow the steps above but pass `-s subtree` to do a subtree-merge, see
+https://git-scm.com/book/en/v1/Git-Tools-Subtree-Merging.
----------------
bogner wrote:
> I expect this is the common case for anyone with any significant out of tree changes. We probably need to pay a bit more attention to it.
Agreed.  It is definitely the situation for us.  I suspect the vast majority of cases will be people using the existing project repositories, with their own long-lived branches that have periodic merges from master.  Essentially, downstream looks like a "downstream master" branches that periodically merge from the "upstream master" branches to sync up.

In our situation we have multiple such "downstream master" branches, one for each project repository we're using (llvm, compiler-rt, etc.).  It's not at all clear to me how we will transition those multiple branches to a single "downstream master" branch on the monorepo.

In the worst case we'll replay all of our downstream commits on top of the monorepo master, but I am hoping there is a better way.


https://reviews.llvm.org/D53414