Merge branches 'jc/sb' and 'jc/mb'

diff --git a/merge-base.c b/merge-base.c
index 286bf0e..751c3c2 100644 (file)
--- a/merge-base.c
+++ b/merge-base.c
@@ -80,14 +80,95 @@ static struct commit *interesting(struct commit_list *list)
  * Now, list does not have any interesting commit.  So we find the newest
  * commit from the result list that is not marked uninteresting.  Which is
  * commit B.
+ *
+ *
+ * Another pathological example how this thing can fail to mark an ancestor
+ * of a merge base as UNINTERESTING without the postprocessing phase.
+ *
+ *               2
+ *               H
+ *         1    / \
+ *         G   A   \
+ *         |\ /     \ 
+ *         | B       \
+ *         |  \       \
+ *          \  C       F
+ *           \  \     / 
+ *            \  D   /   
+ *             \ |  /
+ *              \| /
+ *               E
+ *
+ *      list                   A B C D E F G H
+ *      G1 H2                  - - - - - - 1 2
+ *      H2 E1 B1               - 1 - - 1 - 1 2
+ *      F2 E1 B1 A2            2 1 - - 1 2 1 2
+ *      E3 B1 A2               2 1 - - 3 2 1 2
+ *      B1 A2                  2 1 - - 3 2 1 2
+ *      C1 A2                  2 1 1 - 3 2 1 2
+ *      D1 A2                  2 1 1 1 3 2 1 2
+ *      A2                     2 1 1 1 3 2 1 2
+ *      B3                     2 3 1 1 3 2 1 2
+ *      C7                     2 3 7 1 3 2 1 2
+ *
+ * At this point, unfortunately, everybody in the list is
+ * uninteresting, so we fail to complete the following two
+ * steps to fully marking uninteresting commits.
+ *
+ *      D7                     2 3 7 7 3 2 1 2
+ *      E7                     2 3 7 7 7 2 1 2
+ *
+ * and we end up showing E as an interesting merge base.
  */
 
 static int show_all = 0;
 
+static void mark_reachable_commits(struct commit_list *result,
+                                  struct commit_list *list)
+{
+       struct commit_list *tmp;
+
+       /*
+        * Postprocess to fully contaminate the well.
+        */
+       for (tmp = result; tmp; tmp = tmp->next) {
+               struct commit *c = tmp->item;
+               /* Reinject uninteresting ones to list,
+                * so we can scan their parents.
+                */
+               if (c->object.flags & UNINTERESTING)
+                       commit_list_insert(c, &list);
+       }
+       while (list) {
+               struct commit *c = list->item;
+               struct commit_list *parents;
+
+               tmp = list;
+               list = list->next;
+               free(tmp);
+
+               /* Anything taken out of the list is uninteresting, so
+                * mark all its parents uninteresting.  We do not
+                * parse new ones (we already parsed all the relevant
+                * ones).
+                */
+               parents = c->parents;
+               while (parents) {
+                       struct commit *p = parents->item;
+                       parents = parents->next;
+                       if (!(p->object.flags & UNINTERESTING)) {
+                               p->object.flags |= UNINTERESTING;
+                               commit_list_insert(p, &list);
+                       }
+               }
+       }
+}
+
 static int merge_base(struct commit *rev1, struct commit *rev2)
 {
        struct commit_list *list = NULL;
        struct commit_list *result = NULL;
+       struct commit_list *tmp = NULL;
 
        if (rev1 == rev2) {
                printf("%s\n", sha1_to_hex(rev1->object.sha1));
@@ -104,9 +185,10 @@ static int merge_base(struct commit *rev1, struct commit *rev2)
 
        while (interesting(list)) {
                struct commit *commit = list->item;
-               struct commit_list *tmp = list, *parents;
+               struct commit_list *parents;
                int flags = commit->object.flags & 7;
 
+               tmp = list;
                list = list->next;
                free(tmp);
                if (flags == 3) {
@@ -130,6 +212,9 @@ static int merge_base(struct commit *rev1, struct commit *rev2)
        if (!result)
                return 1;
 
+       if (result->next && list)
+               mark_reachable_commits(result, list);
+
        while (result) {
                struct commit *commit = result->item;
                result = result->next;

diff --git a/t/t6010-merge-base.sh b/t/t6010-merge-base.sh
new file mode 100755 (executable)
index 0000000..c3a9680
--- /dev/null
+++ b/t/t6010-merge-base.sh
@@ -0,0 +1,59 @@
+#!/bin/sh
+#
+# Copyright (c) 2005 Junio C Hamano
+#
+
+test_description='Merge base computation.
+'
+
+. ./test-lib.sh
+
+T=$(git-write-tree)
+
+M=1130000000
+Z=+0000
+
+export GIT_COMMITTER_EMAIL=git@comm.iter.xz
+export GIT_COMMITTER_NAME='C O Mmiter'
+export GIT_AUTHOR_NAME='A U Thor'
+export GIT_AUTHOR_EMAIL=git@au.thor.xz
+
+doit() {
+       OFFSET=$1; shift
+       NAME=$1; shift
+       PARENTS=
+       for P
+       do
+               PARENTS="${PARENTS}-p $P "
+       done
+       GIT_COMMITTER_DATE="$(($M + $OFFSET)) $Z"
+       GIT_AUTHOR_DATE=$GIT_COMMITTER_DATE
+       export GIT_COMMITTER_DATE GIT_AUTHOR_DATE
+       commit=$(echo $NAME | git-commit-tree $T $PARENTS)
+       echo $commit >.git/refs/tags/$NAME
+       echo $commit
+}
+
+# Setup...
+E=$(doit 5 E)
+D=$(doit 4 D $E)
+F=$(doit 6 F $E)
+C=$(doit 3 C $D)
+B=$(doit 2 B $C)
+A=$(doit 1 A $B)
+G=$(doit 7 G $B $E)
+H=$(doit 8 H $A $F)
+
+test_expect_success 'compute merge-base (single)' \
+    'MB=$(git-merge-base G H) &&
+     expr "$(git-name-rev "$MB")" : "[0-9a-f]* B"'
+
+test_expect_success 'compute merge-base (all)' \
+    'MB=$(git-merge-base --all G H) &&
+     expr "$(git-name-rev "$MB")" : "[0-9a-f]* B"'
+
+test_expect_success 'compute merge-base with show-branch' \
+    'MB=$(git-show-branch --merge-base G H) &&
+     expr "$(git-name-rev "$MB")" : "[0-9a-f]* B"'
+
+test_done