Re: [RFC PATCH 0/2] Introduce new merge-tree-ort command

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Elijah,

On Tue, 11 Jan 2022, Elijah Newren wrote:

> On Mon, Jan 10, 2022 at 9:59 AM Elijah Newren <newren@gmail.com> wrote:
> >
> > On Mon, Jan 10, 2022 at 5:49 AM Johannes Schindelin
> > <Johannes.Schindelin@gmx.de> wrote:
> > >
> ...
> > >, therefore it expects the resolved conflicts to
> > > be in _files_. I don't think that there is a way to reasonably handle
> > > symlink target conflicts or directory/file/symlink conflicts, but there
> > > might be.
> >
> > You really need (mode,oid) pairs to be provided by the user.  That
> > fixes the executable issue I mentioned above, and makes it clear how
> > to handle symlinks and file/symlink conflicts.
> >
> > directory/file are still handled by providing individual files, but
> > ordering traversal becomes really tricky.  The directory/file case
> > might even require the pre_resolved_conflicts to be pulled out of that
> > loop somehow.  It'd take some investigative work, or some deep
> > thought, or both.
>
> I think I came up with a solution to this during my run yesterday,
> though I haven't tried or tested it.  Instead of modifying the loop
> over plist.items, you instead add a preliminary loop over
> pre_resolved_conflicts that modifies opt->priv->paths (and add this
> preliminary loop just before the items from opt->priv->paths are added
> to plist.items).  In that preliminary loop, you need to make sure that
> (a) any files in pre_resolved_conflicts corresponding to existing
> _files_ in opt->priv->path result in updating that item's clean &
> is_null & mode & oid state, (b) any files in pre_resolved_conflicts
> that correspond to existing _directories_ in opt->priv->path need the
> value to be expanded to be a conflict_info instead of just a
> merged_info, you need to set the df_conflict bit, and don't update the
> merge_info fields but do update the extended conflict_info ones, (c)
> any new files in pre_resolved_conflicts result in new entries
> opt->priv->paths, (d) any leading directories of new files in
> pre_resolved_conflicts are appropriately handled, meaning: (d1) new
> opt->priv->paths are created if the directory path wasn't in
> opt->priv->paths before, (d2) a tweak to df_conflict for the directory
> item if it previously existed in opt->priv->paths but only as a file
> (possibly also necessitating expanding from a merged_info to a
> conflict_info), (d3) no-op if the directory already existed in
> opt->priv->paths and was just a directory (and in this case, you can
> stop walking the parent directories to the toplevel).
>
> Then, after this preliminary loop that modifies opt->priv->paths, the
> rest can just proceed as-is.
>
> That should handle new files, new directories, and all directory/file
> conflicts.  Yeah, it's a bunch to look at, but directory/file
> conflicts are always a bear.

Indeed.

What's even worse is the question how to represent that in a web UI, and I
think I'll wait for that to happen (if ever) to give that part of the
design more thought.

Ciao,
Dscho