Subject: Re: [PATCH] revision: fix memory leak in prepare_show_merge()

From: Junio C Hamano <[email-masked]>
Date: Fri, 06 Jun 2025 09:47:18 -0700

lidongyan <[email-masked]> writes:

> I could add this test case into my patch. Though I don’t understand
>> + git rev-parse HEAD >.git/MERGE_HEAD &&

That was not about telling "show --merge" to work on any meaningful
data and to produce any useful output.  I knew the step to prepare
for "show --merge" was leaky, so I gave a very minimum that can tickle
that codepath.  I wasn't of course proud of the direct manipulation
of the filesystem (as recent "git update-ref MERGE_HEAD HEAD" would
not even allow us to do this, sheesh, not very convenient).

If you came up with a sequence that produces a situation to use the
"git show --merge" command in a more realistic way, like below, that
is wonderful.

> If HEAD is equal to MERGE_HEAD. Would git show —merge still
> works as usual? How about something like this
>
> diff --git a/t/t7007-show.sh b/t/t7007-show.sh
> index d6cc69e0f2..f693b6e24b 100755
> --- a/t/t7007-show.sh
> +++ b/t/t7007-show.sh
> @@ -167,4 +167,28 @@ test_expect_success 'show --graph is forbidden' '
>    test_must_fail git show --graph HEAD
>  '
>  
> +test_expect_success 'unmerged index' '
> +       git reset --hard &&
> +
> +       git switch -C base &&
> +       echo "base" > conflicting &&
> +       git add conflicting &&
> +       git commit -m "base" &&
> +
> +       git branch hello &&
> +       git branch goodbye &&
> +
> +       git switch hello &&
> +       echo "hello" > conflicting &&
> +       git commit -am "hello" &&
> +
> +       git switch goodbye &&
> +       echo "goodbye" > conflicting &&
> +       git commit -am "goodbye" &&
> +
> +       git switch hello &&
> +       test_must_fail git merge goodbye &&
> +       git show --merge HEAD
> +'
> +
>  test_done