[PATCH v2] blame: allow --contents to work with bare repo

[Han Young <hanyang.tony@bytedance.com>]

The --contents option can be used with git blame to blame the file as if
it had the contents from the specified file. Since 1a3119ed06c8fbb1c00a6aa3615299252575abab ("blame: allow --contents to work with non-HEAD commit"), the --contents option can work with non-HEAD commit. However, if you try to use --contents in a bare repository, you get the following error:

    fatal: this operation must be run in a work tree

This is because before trying to generate a fake working tree commit, we always call setup_work_tree. But in a bare repo, work tree is not available. The call to setup_work_tree is used to prepare the reading of the blamed file in the work tree, which isn't necessary if we are reading the contents from the specific file instead of the file in the work tree.

Add a check in setup_scoreboard to skip setup_work_tree if we are reading from the file specified in --contents.

This enables us to use --contents in a bare repo. This is a nice addition on top of 1a3119ed06c8fbb1c00a6aa3615299252575abab, having a working tree to use --contents is optional.

Add test for the --contents option with bare repo to the annotate-tests.sh test script.

Signed-off-by: Han Young <hanyang.tony@bytedance.com>
---
Changes since v1:
* Removed unwanted {braces} around a single statement
* Sent the email properly with git-send-email so the tabs are preserved
* Corrected typos in commit message

Before commit 1a3119ed06c8fbb1c00a6aa3615299252575abab using --contents in a bare repo will lead to

	fatal: cannot use --contents with final commit object name

even without specify a revision, this is because in a bare repo, HEAD is seem as a passed revision. After 1a3119ed06c8fbb1c00a6aa3615299252575abab, git will try to setup_work_tree as long as --contents is passed. So we still cannot use --contents on a bare repo.

I was comparing files between a bare repo on the server and my local partial cloned repo. It is convenient for me to be able to use --contents option on a bare repo, because the project is very large and would occupy a lot of disk space if fully cloned on local machine.

With this change I can upload my local file to the server and get the blame result without keeping a full clone of the repo on my local machine.

 blame.c             | 4 +++-
 t/annotate-tests.sh | 9 +++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/blame.c b/blame.c
index d12bd9f97..141756975 100644
--- a/blame.c
+++ b/blame.c
@@ -2806,7 +2806,9 @@ void setup_scoreboard(struct blame_scoreboard *sb,
 			parent_oid = &head_oid;
 		}
 
-		setup_work_tree();
+		if (!sb->contents_from)
+			setup_work_tree();
+
 		sb->final = fake_working_tree_commit(sb->repo,
 						     &sb->revs->diffopt,
 						     sb->path, sb->contents_from,
diff --git a/t/annotate-tests.sh b/t/annotate-tests.sh
index 2ef70235b..5e21e84f3 100644
--- a/t/annotate-tests.sh
+++ b/t/annotate-tests.sh
@@ -83,6 +83,15 @@ test_expect_success 'blame with --contents' '
 	check_count --contents=file A 2
 '
 
+test_expect_success 'blame with --contents in a bare repo' '
+	git clone --bare . bare-contents.git &&
+	(
+		cd bare-contents.git &&
+		echo "1A quick brown fox jumps over the" >contents &&
+		check_count --contents=contents A 1
+	)
+'
+
 test_expect_success 'blame with --contents changed' '
 	echo "1A quick brown fox jumps over the" >contents &&
 	echo "another lazy dog" >>contents &&
-- 
2.40.0