Re: bug? round-trip through fast-import/fast-export loses files

From: Jeff King <peff@peff.net>
Date: Mar 21, 2023, 18:31 UTC
Message-ID: <20230321183138.GL3119834@coredump.intra.peff.net>
In-Reply-To: <CABPp-BEG+vp-UcpVfcZecPBnfcuTjO6JYCo7wEU5ZrDUHBUd9g@mail.gmail.com>

On Mon, Mar 20, 2023 at 06:57:21PM -0700, Elijah Newren wrote:

Show 9 quoted lines

> Honestly, looking back at those two patches of mine, I think both were
> rather suboptimal.  A better solution that would handle both F->D and
> D->F would be having fast-export sort the diff_filepairs such that it
> processes the deletes before the modifies.  Another improved solution
> would be having fast-import sort the files given to it and handling
> deletes first.  Either should fix this.
> 
> Might be a good task for a new contributor.  Any takers?  (Tagging as
> #leftoverbits.)

There was a patch a while ago, but it didn't get applied:

  https://lore.kernel.org/git/1493079137-1838-1-git-send-email-miguel.torroja@gmail.com/

It got hung up on the fact that fast-export can also generate renames, and ordering there is tricky. I stand by the sentiment from back then that it is still worth it to order things to make the no-rename case work, even if there are still corner cases with renames (since you can have a cycle of renames, you should not use them if you want to be robust against this kind of ordering dependency).

-Peff