On Fri, Jun 11, 2021 at 10:57 AM Felipe Contreras <felipe.contreras@xxxxxxxxx> wrote:
> Elijah Newren wrote:
> > On Fri, Jun 11, 2021 at 8:32 AM Felipe Contreras <felipe.contreras@xxxxxxxxx>
> > wrote:
...
> > The alternative to the above two options was the
> > make-a-virtual-merge-base-by-merging-merge-bases strategy. It apparently
> > was very successful.
>
> OK. That makes sense.
>
> > But it does mean that merge bases can have conflict markers in them.
>
> But why? And even if they do, why do they have to be diff3 conflict
> markers?
This could be changed; I suspect it just was a natural consequence of how
the code was built. (Recursive means there's not a separate code-path for
merging the merge-bases, so they get the same merge style by default.)
> This would be more human-friendly:
>
> <<<<<<< HEAD
> D
> ||||||| merged common ancestors
> <<<<<<<<< Temporary merge branch 1
> B
> =========
> A
> >>>>>>>>> Temporary merge branch 2
> =======
> C
> >>>>>>> C
I suspect that would be as easy as this (not compiled or tested):
diff --git a/ll-merge.c b/ll-merge.c
index 095a4d820e..bdd129cbd6 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -131,7 +131,7 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
xmp.level = XDL_MERGE_ZEALOUS;
xmp.favor = opts->variant;
xmp.xpp.flags = opts->xdl_opts;
- if (git_xmerge_style >= 0)
+ if (git_xmerge_style >= 0 && !opts->virtual_ancestor)
xmp.style = git_xmerge_style;
if (marker_size > 0)
xmp.marker_size = marker_size;
> Or just put a stub conflict marker:
>
> <<<<<<< HEAD
> D
> ||||||| merged common ancestors
> <<<<<<<<< Temporary merge >>>>>>>>>
> =======
> C
> >>>>>>> C
I don't know what would be involved to do this one; I think it wouldn't
be too hard, but I don't think we'd want to pursue this option.
> Or just use the base of the virtual merge:
>
> <<<<<<< HEAD
> D
> ||||||| merged common ancestors
> 1
> =======
> C
> >>>>>>> C
I think that implementing this choice would look like this (again, not
compiled or tested and I'm not familiar with xdiff so take it with a
big grain of salt):
diff --git a/ll-merge.c b/ll-merge.c
index 095a4d820e..dbc7f76951 100644
--- a/ll-merge.c
+++ b/ll-merge.c
@@ -130,6 +130,8 @@ static int ll_xdl_merge(const struct ll_merge_driver *drv_unused,
memset(&xmp, 0, sizeof(xmp));
xmp.level = XDL_MERGE_ZEALOUS;
xmp.favor = opts->variant;
+ if (git_xmerge_style >= 0 && opts->virtual_ancestor)
+ xmp.favor = XDL_MERGE_FAVOR_BASE;
xmp.xpp.flags = opts->xdl_opts;
if (git_xmerge_style >= 0)
xmp.style = git_xmerge_style;
diff --git a/xdiff/xdiff.h b/xdiff/xdiff.h
index 8629ae287c..b8d1a536c2 100644
--- a/xdiff/xdiff.h
+++ b/xdiff/xdiff.h
@@ -62,6 +62,7 @@ extern "C" {
#define XDL_MERGE_FAVOR_OURS 1
#define XDL_MERGE_FAVOR_THEIRS 2
#define XDL_MERGE_FAVOR_UNION 3
+#define XDL_MERGE_FAVOR_BASE 4
/* merge output styles */
#define XDL_MERGE_DIFF3 1
diff --git a/xdiff/xmerge.c b/xdiff/xmerge.c
index 95871a0b6e..a8dc42595a 100644
--- a/xdiff/xmerge.c
+++ b/xdiff/xmerge.c
@@ -313,6 +313,9 @@ static int xdl_fill_merge_buffer(xdfenv_t *xe1, const char *name1,
if (m->mode & 2)
size += xdl_recs_copy(xe2, m->i2, m->chg2, 0, 0,
dest ? dest + size : NULL);
+ } else if (m->mode == 4) {
+ size += xdl_orig_copy(xe1, m->i0, m->chg0, needs_cr, 0,
+ dest ? dest + size : NULL);
} else
continue;
i = m->i1 + m->chg1;
> We don't have to use diff3 all the way.
Right, thus my mention in the other email to consider adding a
XDL_MERGE_FAVOR_BASE -- which you then also mention here in your third
option, and which I've now given at least a partial patch for. Not
sure if it's a crazy idea or a great idea, since I don't do very many
criss-cross merges myself.
Hope that helps,
Elijah
