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From:   Junio C Hamano <gitster@pobox.com>
To:     "Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com>
Cc:     git@vger.kernel.org,
        =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason <avarab@gmail.com>,
        Elijah Newren <newren@gmail.com>
Subject: Re: [PATCH 2/2] merge: fix memory leaks in cmd_merge()
References: <pull.1200.git.git.1642664835.gitgitgadget@gmail.com>
        <c6522d6449f9323edbbd9329b2859368492aabd3.1642664835.git.gitgitgadget@gmail.com>
Date:   Fri, 21 Jan 2022 16:05:18 -0800
In-Reply-To: <c6522d6449f9323edbbd9329b2859368492aabd3.1642664835.git.gitgitgadget@gmail.com>
        (Elijah Newren via GitGitGadget's message of "Thu, 20 Jan 2022
        07:47:15 +0000")
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"Elijah Newren via GitGitGadget" <gitgitgadget@gmail.com> writes:

>  done:
> +	if (!automerge_was_ok) {
> +		free_commit_list(common);
> +		free_commit_list(remoteheads);
> +	}

I wondered what happens upon a successful automerge.

We call finish_automerge() and come here, and I do see a call to
free_commit_list(common) in finish_automerge(), but the way
remoteheads is used looked a bit iffy.

In finish_automerge(), we use a temporary variable parents to point
remoteheads at it, and conditionally prepend the current HEAD at the
beginning of the parents list.  This is passed to commit_tree(),
which does pop_commit() to consume all commits on the list.

So after commit_tree() returns, all commit_list instances on
remoteheads list, and possibly the one finish_automerge() prepended
for the current HEAD, are all consumed, and there is no need to
call, and it would be wrong to call, free_commit_list(), at this
point.

So, I agree that this conditional freeing is correct.  It was just
it was a bit hard to see.

Thanks.