From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 06 Oct 2026 15:46:42 GMT
Subject: Re: [PATCH v2 2/2] merge: remember conflict labels
Message-ID: <xmqqh5iyg7bx.fsf@gitster.g>
In-Reply-To: <18bdf7df49dde2c8e7f73f3b46c656abb6b26293.1791206658.git.phillip.wood@dunelm.org.uk>

Phillip Wood <phillip.wood123@gmail.com> writes:

> @@ -4969,6 +4973,13 @@ void merge_switch_to_result(struct merge_options *opt,
>  			return;
>  		}
>  		trace2_region_leave("merge", "write_auto_merge", opt->repo);
> +
> +		trace2_region_enter("merge", "write_merge_labels", opt->repo);
> +		opt->priv = result->priv;
> +		write_merge_labels(opt->repo, opt->priv->labels[0], opt->priv->labels[1],
> +				   opt->priv->labels[2]);
> +		opt->priv = NULL;
> +		trace2_region_leave("merge", "write_merge_labels", opt->repo);

A "if (result->clean >= 0 && update_worktree_and_index)" condition
guards this code path, so we unconditionall call
write_merge_labels(), whether the result is clean or with conflict.
Am I reading the code correctly?

> @@ -5234,6 +5245,14 @@ static void move_opt_priv_to_result_priv(struct merge_options *opt,
>  	 * to move it.
>  	 */
>  	assert(opt->priv && !result->priv);
> +	if (!result->clean) {
> +		opt->priv->labels[0] =
> +			mem_pool_strdup(&opt->priv->pool, opt->ancestor);
> +		opt->priv->labels[1] =
> +			mem_pool_strdup(&opt->priv->pool, opt->branch1);
> +		opt->priv->labels[2] =
> +			mem_pool_strdup(&opt->priv->pool, opt->branch2);
> +	}

But we only populate the labels[] when conflicted.  What would we
write when we do not have conflicts?

> +int write_merge_labels(struct repository *r, const char *base,
> +			  const char *ours, const char *theirs)
> +{
> +	FILE *f = fopen_or_warn(git_path_merge_labels(r), "w");
> +
> +	if (!f)
> +		return -1;
> +
> +	fprintf(f, "%s\n%s\n%s\n", base, ours, theirs);
> +	if (fclose(f))
> +		return error_errno("could not write '%s'",
> +				   git_path_merge_labels(r));
> +
> +	return 0;
> +}

Would the answer be "(null)\n(null)\n(null)\n"?