Subject: Re: [RFC PATCH] builtin/format-patch: print a warning for skipped merge commits?

From: Jeff King <[email-masked]>
Date: Fri, 2 Jan 2026 02:33:58 -0500

On Wed, Dec 31, 2025 at 12:42:17PM +0900, Dominique Martinet wrote:

> @@ -2274,6 +2273,11 @@ int cmd_format_patch(int argc,
>  		die(_("revision walk setup failed"));
>  	rev.boundary = 1;
>  	while ((commit = get_revision(&rev)) != NULL) {
> +		if (commit->parents->next) {
> +			warning(_("skipped merge commit %s"),
> +				oid_to_hex(&commit->object.oid));
> +			continue;
> +		}

I don't have any thoughts on whether the patch is overall a good
direction or not, but I suspect this line will segfault if we ever see a
root commit. You probably want:

  if (commit->parents && commit->parents->next)

here.

-Peff