Re: [PATCH v2 3/4] builtin/pack-objects.c: ensure included `--stdin-packs` exist

[Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>]

On Tue, May 24 2022, Taylor Blau wrote:

> -	struct rev_info *revs = _data;
> -	struct object_info oi = OBJECT_INFO_INIT;
>  	off_t ofs;
> -	enum object_type type;
> +	enum object_type type = OBJ_NONE;
>  
>  	display_progress(progress_state, ++nr_seen);
>  
> @@ -3215,20 +3213,25 @@ static int add_object_entry_from_pack(const struct object_id *oid,
>  	if (!want_object_in_pack(oid, 0, &p, &ofs))
>  		return 0;
>  
> -	oi.typep = &type;
> -	if (packed_object_info(the_repository, p, ofs, &oi) < 0)
> -		die(_("could not get type of object %s in pack %s"),
> -		    oid_to_hex(oid), p->pack_name);
> -	else if (type == OBJ_COMMIT) {
> -		/*
> -		 * commits in included packs are used as starting points for the
> -		 * subsequent revision walk
> -		 */
> -		add_pending_oid(revs, NULL, oid, 0);
> +	if (p) {
> +		struct rev_info *revs = _data;
> +		struct object_info oi = OBJECT_INFO_INIT;
> +
> +		oi.typep = &type;
> +		if (packed_object_info(the_repository, p, ofs, &oi) < 0) {
> +			die(_("could not get type of object %s in pack %s"),
> +			    oid_to_hex(oid), p->pack_name);
> +		} else if (type == OBJ_COMMIT) {
> +			/*
> +			 * commits in included packs are used as starting points for the
> +			 * subsequent revision walk
> +			 */
> +			add_pending_oid(revs, NULL, oid, 0);
> +		}
> +
> +		stdin_packs_found_nr++;
>  	}
>  
> -	stdin_packs_found_nr++;
> -
>  	create_object_entry(oid, type, 0, 0, 0, p, ofs);

Not rhetorical, since I have no idea: Is the behavior change here to
make create_object_entry with type=OBJ_NONE desired? I.e. do we actually
want to create object entries for OBJ_NONE?

If that is the case I for one would find this a bit easier to follow
like this, even if it has some minor duplication, i.e. the intent is
clearer:
	
	diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
	index ffeaecd1d84..a447f6d5164 100644
	--- a/builtin/pack-objects.c
	+++ b/builtin/pack-objects.c
	@@ -3202,7 +3202,6 @@ static int add_object_entry_from_pack(const struct object_id *oid,
	 				      void *_data)
	 {
	 	off_t ofs;
	-	enum object_type type = OBJ_NONE;
	 
	 	display_progress(progress_state, ++nr_seen);
	 
	@@ -3216,6 +3215,7 @@ static int add_object_entry_from_pack(const struct object_id *oid,
	 	if (p) {
	 		struct rev_info *revs = _data;
	 		struct object_info oi = OBJECT_INFO_INIT;
	+		enum object_type type;
	 
	 		oi.typep = &type;
	 		if (packed_object_info(the_repository, p, ofs, &oi) < 0) {
	@@ -3230,9 +3230,11 @@ static int add_object_entry_from_pack(const struct object_id *oid,
	 		}
	 
	 		stdin_packs_found_nr++;
	-	}
	 
	-	create_object_entry(oid, type, 0, 0, 0, p, ofs);
	+		create_object_entry(oid, type, 0, 0, 0, p, ofs);
	+	} else  {
	+		create_object_entry(oid, OBJ_NONE, 0, 0, 0, p, ofs);
	+	}
	 
	 	return 0;
	 }

Or the same with adding "type = OBJ_NONE" to the "else" branch, leaving
the initial "type" uninitialized"?

Or perhaps this is a bug? I see some OBJ_NONE mentions in the code, but
do packfiles really have "none" objects in some fashion as far as
add_object_entry_from_pack() is concerned? (I'm not familiar enough with
this part of the codebase to know).