commit: drop duplicated parents

The scripted version of git-commit internally used git-commit-tree which
omitted duplicated parents given from the command line.  This prevented a
nonsensical octopus merge from getting created even when you said "git
merge A B" while you are already on branch A.

However, when git-commit was rewritten in C, this sanity check was lost.
This resurrects it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin-commit.c b/builtin-commit.c
index b294c1f88c1eecde8d96d265c72376c789f24899..90200ed643bcf21f28a66396f0d15db920a5d4c8 100644 (file)
--- a/builtin-commit.c
+++ b/builtin-commit.c
@@ -883,10 +883,19 @@ static void add_parent(struct strbuf *sb, const unsigned char *sha1)
 {
        struct object *obj = parse_object(sha1);
        const char *parent = sha1_to_hex(sha1);
+       const char *cp;
+
        if (!obj)
                die("Unable to find commit parent %s", parent);
        if (obj->type != OBJ_COMMIT)
                die("Parent %s isn't a proper commit", parent);
+
+       for (cp = sb->buf; cp && (cp = strstr(cp, "\nparent ")); cp += 8) {
+               if (!memcmp(cp + 8, parent, 40) && cp[48] == '\n') {
+                       error("duplicate parent %s ignored", parent);
+                       return;
+               }
+       }
        strbuf_addf(sb, "parent %s\n", parent);
 }
 

diff --git a/t/t7502-commit.sh b/t/t7502-commit.sh
index 46ec1ce8aaa0305f6b4569664de041137db137d7..22a13f7aababf43fac0a02b6e9310f74cc6b4f9f 100755 (executable)
--- a/t/t7502-commit.sh
+++ b/t/t7502-commit.sh
@@ -226,4 +226,18 @@ test_expect_success 'a SIGTERM should break locks' '
        ! test -f .git/index.lock
 '
 
+rm -f .git/MERGE_MSG .git/COMMIT_EDITMSG
+git reset -q --hard
+
+test_expect_success 'Hand committing of a redundant merge removes dups' '
+
+       git rev-parse second master >expect &&
+       test_must_fail git merge second master &&
+       git checkout master g &&
+       EDITOR=: git commit -a &&
+       git cat-file commit HEAD | sed -n -e "s/^parent //p" -e "/^$/q" >actual &&
+       test_cmp expect actual
+
+'
+
 test_done