[PATCH v2 0/4] fix `git replace --graft` tag related issues

[PATCH v2 0/4] fix `git replace --graft` tag related issues

[Christian Couder]

This is version 2 of a small patch series to fix tag related issues in
`git replace --graft` that Andreas Schwab reported in:

https://public-inbox.org/git/mvmd0mcsjkf.fsf@suse.de/

The first version of this patch series was:

https://public-inbox.org/git/20190328171722.9753-1-chriscool@tuxfamily.org/

Changes compared to the previous version are the following:

  - patch 4/4 has been added to fix issues when a tag is passed first

  - in patch 2/4 the error message is redirected to a file instead of
    /dev/null as suggested by Ævar after a comment by Eric

  - title of patch 3/4 has been extended with "as parent" to make it
    different from title of patch 4/4

I saw that t6050 has existing 4-space-instead-of-tabs issues, but it
can perhaps be dealt with if some bigger changes are made to this test
script.

Thanks Taylor for the review, and Eric and Ævar for the
comments/suggestions!

Christian Couder (4):
  t6050: use test_line_count instead of wc -l
  t6050: redirect expected error output to a file
  replace: fix --graft when passing a tag as parent
  replace: fix --graft when passing a tag first

 builtin/replace.c  | 20 +++++++++++++-------
 t/t6050-replace.sh | 31 ++++++++++++++++++++++++++++---
 2 files changed, 41 insertions(+), 10 deletions(-)

-- 
2.21.0.69.g2d86a08d09

[PATCH v2 1/4] t6050: use test_line_count instead of wc -l

[Christian Couder]

This modernizes a test and makes it more portable.

Reviewed-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 t/t6050-replace.sh | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index d638119750..41b177936e 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -393,9 +393,11 @@ test_expect_success 'replace ref cleanup' '
 '
 
 test_expect_success '--graft with and without already replaced object' '
-	test $(git log --oneline | wc -l) = 7 &&
+	git log --oneline >log &&
+	test_line_count = 7 log &&
 	git replace --graft $HASH5 &&
-	test $(git log --oneline | wc -l) = 3 &&
+	git log --oneline >log &&
+	test_line_count = 3 log &&
 	commit_has_parents $HASH5 &&
 	test_must_fail git replace --graft $HASH5 $HASH4 $HASH3 &&
 	git replace --force -g $HASH5 $HASH4 $HASH3 &&
-- 
2.21.0.69.g2d86a08d09

[PATCH v2 2/4] t6050: redirect expected error output to a file

[Christian Couder]

Otherwise the error from `git rev-parse` is uselessly
polluting the debug output.

Redirecting to a file, instead of /dev/null, makes it
possible to check that we got the error we expected, so
let's check that too.

Reviewed-by: Taylor Blau <me@ttaylorr.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Helped-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Christian Couder <chriscool@tuxfamily.org>
---
 t/t6050-replace.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/t/t6050-replace.sh b/t/t6050-replace.sh
index 41b177936e..948d278482 100755
--- a/t/t6050-replace.sh
+++ b/t/t6050-replace.sh
@@ -40,7 +40,8 @@ commit_peeling_shows_parents ()
 	test "$_found" = "$_parent" || return 1
 	_parent_number=$(( $_parent_number + 1 ))
     done &&
-    test_must_fail git rev-parse --verify $_commit^$_parent_number
+    test_must_fail git rev-parse --verify $_commit^$_parent_number 2>err &&
+    test_i18ngrep "Needed a single revision" err
 }
 
 commit_has_parents ()
-- 
2.21.0.69.g2d86a08d09

[PATCH v2 3/4] replace: fix --graft when passing a tag as parent

[Christian Couder]

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>
---
 builtin/replace.c  |  9 ++++++---
 t/t6050-replace.sh | 11 +++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)

diff --git a/builtin/replace.c b/builtin/replace.c
index f5701629a8..b0a9227f9a 100644
--- a/builtin/replace.c
+++ b/builtin/replace.c
@@ -370,16 +370,19 @@ 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 948d278482..2385a60f68 100755
--- 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 &&
-- 
2.21.0.69.g2d86a08d09

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

[Christian Couder]

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 <chriscool@tuxfamily.org>
---
 builtin/replace.c  | 11 +++++++----
 t/t6050-replace.sh | 11 +++++++++++
 2 files changed, 18 insertions(+), 4 deletions(-)

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 &&
-- 
2.21.0.69.g2d86a08d09

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

[Junio C Hamano]

Christian Couder <christian.couder@gmail.com> 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.