From: Junio C Hamano <gitster@pobox.com>
Date: Mon, 04 May 2026 01:13:01 GMT
Subject: Re: [PATCH] name-rev: fix an 'may be used uninitialized' error
Message-ID: <xmqqv7d4ou3m.fsf@gitster.g>
In-Reply-To: <e74a8fd8-0617-46a8-8bef-a454d51a99c1@ramsayjones.plus.com>

Ramsay Jones <ramsay@ramsayjones.plus.com> writes:

> Today's seen branch fails to build (with DEVELOPER=1), like so:
>
>       CC builtin/name-rev.o
>   builtin/name-rev.c: In function ‘cmd_format_rev’:
>   builtin/name-rev.c:885:28: error: ‘commit’ may be used uninitialized [-Werror=maybe-uninitialized]
>     885 |                         if (!commit) {
>         |                            ^
>   builtin/name-rev.c:867:40: note: ‘commit’ was declared here
>     867 |                         struct commit *commit;
>         |                                        ^~~~~~
>   cc1: all warnings being treated as errors
>   make: *** [Makefile:2932: builtin/name-rev.o] Error 1
> ...
> diff --git a/builtin/name-rev.c b/builtin/name-rev.c
> index b941e93834..5b7f7a00e5 100644
> --- a/builtin/name-rev.c
> +++ b/builtin/name-rev.c
> @@ -882,6 +882,8 @@ int cmd_format_rev(int argc,
>  			peeled = deref_tag(the_repository, object, scratch_buf.buf, 0);
>  			if (peeled && peeled->type == OBJ_COMMIT)
>  				commit = (struct commit *)peeled;
> +			else
> +				commit = NULL;
>  			if (!commit) {
>  				fprintf(stderr, "Could not get commit for %s. Skipping.\n",
>  					*argv);

Why not

			if (peeled && peeled->type == OBJ_COMMIT) {
				commit = (struct commit *)peeled;
			} else {
				fprintf(stderr, "... skipping ...");
				continue;
			}

			get_format_rev(commit, &format_pp, &scratch);

or even

			if (!peeled || peeled->type != OBJ_COMMIT) {
				fprintf(stderr, "... skipping ...");
				continue;
			}

			get_format_rev((struct commit *)peeled->type,
					&format_pp, &scratch);

and dropping the variable "struct commit *commit" altogether?