[v2,4/4] replace: fix --graft when passing a tag first

Commit Message

Christian Couder March 31, 2019, 1:46 p.m. UTC

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

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.

Especially we would pass the hash of the tag object to
replace_object_oid() where we would likely fail with an error
like:

"error: Objects must be of the same type.
'annotated_replaced_object' points to a replaced object of type 'tag'
while 'replacement' points to a replacement object of type 'commit'."

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

Signed-off-by: Christian Couder <[e-mail]>
---
 builtin/replace.c  | 11 +++++++----
 t/t6050-replace.sh | 11 +++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

Comments

Junio C Hamano April 1, 2019, 8:48 a.m. UTC | #1

Christian Couder <[e-mail]> writes:

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

Yeah, another plausible fix would be to make it an error, but the
message for the error would most likely tell the user to peel the
tag, so peeling it ourselves would make sense.

Patch

diff --git a/builtin/replace.c b/builtin/replace.c
index b0a9227f9a..644b21ca8d 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -481,15 +481,18 @@  static int create_graft(int argc, const char **argv, int force, int gentle)
 
 	strbuf_release(&buf);
 
-	if (oideq(&old_oid, &new_oid)) {
+	if (oideq(&commit->object.oid, &new_oid)) {
 		if (gentle) {
-			warning(_("graft for '%s' unnecessary"), oid_to_hex(&old_oid));
+			warning(_("graft for '%s' unnecessary"),
+				oid_to_hex(&commit->object.oid));
 			return 0;
 		}
-		return error(_("new commit is the same as the old one: '%s'"), oid_to_hex(&old_oid));
+		return error(_("new commit is the same as the old one: '%s'"),
+			     oid_to_hex(&commit->object.oid));
 	}
 
-	return replace_object_oid(old_ref, &old_oid, "replacement", &new_oid, force);
+	return replace_object_oid(old_ref, &commit->object.oid,
+				  "replacement", &new_oid, force);
 }
 
 static int convert_graft_file(int force)
diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index 2385a60f68..e7e64e085d 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -417,6 +417,17 @@  test_expect_success '--graft using a tag as the new parent' '
 	git replace -d $HASH7
 '
 
+test_expect_success '--graft using a tag as the replaced object' '
+	git tag replaced_object $HASH7 &&
+	git replace --graft replaced_object $HASH5 &&
+	commit_has_parents $HASH7 $HASH5 &&
+	git replace -d $HASH7 &&
+	git tag -a -m "annotated replaced object tag" annotated_replaced_object $HASH7 &&
+	git replace --graft annotated_replaced_object $HASH5 &&
+	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 &&