merge: make some conflicts less conflicting.

If a 'conflict' has an empty 'before' section, then it is probably
to separate things - and insertion in the original (unmatched) and
and insertion in the result.
So split it into those two, but leave the result marked as a Conflict
as the order of the insertions is not clear.

For now this mostly affects -B which can display the conflict
more effectively.

Signed-off-by: NeilBrown <neilb@suse.de>

diff --git a/merge2.c b/merge2.c
index 96768fb401273580771262cd6ce1db994da4960d..145ae24dee8720f4e8e72acdfc717b6db0a8d5fa 100644 (file)
--- a/merge2.c
+++ b/merge2.c
@@ -422,6 +422,20 @@ struct ci make_merger(struct file af, struct file bf, struct file cf,
                        if (ignore_already &&
                            check_alreadyapplied(af, cf, &rv.merger[i]))
                                rv.ignored++;
+                       else if (rv.merger[i].bl == 0 &&
+                                rv.merger[i].cl > 0)
+                               /* As the 'before' stream is empty, this
+                                * could look like Unmatched in the
+                                * original, and an insertion in the
+                                * diff.  Reporting it like that is
+                                * probably more useful that as a full
+                                * conflict.
+                                * Leave the type for the insertion as
+                                * Conflict (not Changed) as there is some
+                                * real uncertainty here, but allow the
+                                * original to become Unmatched.
+                                */
+                               rv.merger[i].al = 0;
                }
                a += rv.merger[i].al;
                b += rv.merger[i].bl;