Merge branch 'jc/diff-merge-base-multi'

* jc/diff-merge-base-multi:
  diff A...B: give one possible diff when there are more than one merge-base

diff --git a/builtin/diff.c b/builtin/diff.c
index ffcdd055ca0b9b30bec2ce1f22e348ec15d58c81..bb128631a919aa93bea31d7d6cb5e811427844f3 100644 (file)
--- a/builtin/diff.c
+++ b/builtin/diff.c
@@ -407,17 +407,32 @@ int cmd_diff(int argc, const char **argv, const char *prefix)
                result = builtin_diff_index(&rev, argc, argv);
        else if (ents == 2)
                result = builtin_diff_tree(&rev, argc, argv, ent);
-       else if ((ents == 3) && (ent[0].item->flags & UNINTERESTING)) {
-               /* diff A...B where there is one sane merge base between
-                * A and B.  We have ent[0] == merge-base, ent[1] == A,
-                * and ent[2] == B.  Show diff between the base and B.
+       else if (ent[0].item->flags & UNINTERESTING) {
+               /*
+                * Perhaps the user gave us A...B, which expands
+                * to a list of negative merge bases followed by
+                * A (symmetric-left) and B?  Let's make sure...
                 */
-               ent[1] = ent[2];
+               for (i = 1; i < ents; i++)
+                       if (!(ent[i].item->flags & UNINTERESTING))
+                               break;
+               if (ents != i + 2 ||
+                   (ent[i+1].item->flags & UNINTERESTING) ||
+                   (!(ent[i].item->flags & SYMMETRIC_LEFT)) ||
+                   (ent[i+1].item->flags & SYMMETRIC_LEFT))
+                       die("what do you mean by that?");
+               /*
+                * diff A...B where there is at least one merge base
+                * between A and B.  We have ent[0] == merge-base,
+                * ent[ents-2] == A, and ent[ents-1] == B.  Show diff
+                * between the base and B.  Note that we pick one
+                * merge base at random if there are more than one.
+                */
+               ent[1] = ent[ents-1];
                result = builtin_diff_tree(&rev, argc, argv, ent);
-       }
-       else
+       } else
                result = builtin_diff_combined(&rev, argc, argv,
-                                            ent, ents);
+                                              ent, ents);
        result = diff_result_code(&rev.diffopt, result);
        if (1 < rev.diffopt.skip_stat_unmatch)
                refresh_index_quietly();