replace: peel tag when passing a tag as parent to --graft

When passing a tag as a parent argument to `git replace --graft`,
it can be useful to accept it and use the underlying commit as a
parent.

This already works for lightweight tags, but unfortunately
for annotated tags we have been using the hash of the tag object
instead of the hash of the underlying commit as a parent in the
replacement object we create.

This created invalid objects, but the replace succeeded even if
it showed an error like:

error: object A is a tag, not a commit

This patch fixes that by using the hash of the underlying commit
when an annotated tag is passed.

While at it, let's also update an error message to make it
clearer.

Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/replace.c b/builtin/replace.c
index 5b80b7f21141d6f85d8444d669dffe289f3a60f5..730a6448ae9bfdb8836d8ea704fb6cb48b4962d7 100644 (file)
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -366,16 +366,19 @@ static int replace_parents(struct strbuf *buf, int argc, const char **argv)
        /* prepare new parents */
        for (i = 0; i < argc; i++) {
                struct object_id oid;
+               struct commit *commit;
+
                if (get_oid(argv[i], &oid) < 0) {
                        strbuf_release(&new_parents);
                        return error(_("not a valid object name: '%s'"),
                                     argv[i]);
                }
-               if (!lookup_commit_reference(the_repository, &oid)) {
+               commit = lookup_commit_reference(the_repository, &oid);
+               if (!commit) {
                        strbuf_release(&new_parents);
-                       return error(_("could not parse %s"), argv[i]);
+                       return error(_("could not parse %s as a commit"), argv[i]);
                }
-               strbuf_addf(&new_parents, "parent %s\n", oid_to_hex(&oid));
+               strbuf_addf(&new_parents, "parent %s\n", oid_to_hex(&commit->object.oid));
        }
 
        /* replace existing parents with new ones */

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index 948d2784824e6274201390a3b66bffd30d005c7b..2385a60f680e4539930837d404ddfa598d2c6d4c 100755 (executable)
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -406,6 +406,17 @@ test_expect_success '--graft with and without already replaced object' '
        git replace -d $HASH5
 '
 
+test_expect_success '--graft using a tag as the new parent' '
+       git tag new_parent $HASH5 &&
+       git replace --graft $HASH7 new_parent &&
+       commit_has_parents $HASH7 $HASH5 &&
+       git replace -d $HASH7 &&
+       git tag -a -m "annotated new parent tag" annotated_new_parent $HASH5 &&
+       git replace --graft $HASH7 annotated_new_parent &&
+       commit_has_parents $HASH7 $HASH5 &&
+       git replace -d $HASH7
+'
+
 test_expect_success GPG 'set up a signed commit' '
        echo "line 17" >>hello &&
        echo "line 18" >>hello &&