Re: [PATCH 0/2] fixing parse_object() check for type mismatch

[Jeff King <peff@peff.net>]

On Fri, Nov 18, 2022 at 02:05:04PM -0500, Taylor Blau wrote:

> On Thu, Nov 17, 2022 at 05:37:29PM -0500, Jeff King wrote:
> > I'm adding Taylor to the cc as the author of t6102, when we were
> > tracking down all of these "oops, it's not really a blob" cases. This
> > fixes one of the lingering cases from that test script.
> >
> >   [1/2]: parse_object(): drop extra "has" check before checking object type
> >   [2/2]: parse_object(): check on-disk type of suspected blob
> >
> >  object.c                               | 5 ++---
> >  t/t6102-rev-list-unexpected-objects.sh | 4 ++--
> >  2 files changed, 4 insertions(+), 5 deletions(-)
> 
> A blast from the past :-).
> 
> I took a careful look at both of these patches and they looked good to
> me, so let's start merging them down.

I saw this hit 'next', but I think Ævar's simplification suggestion is
worth taking. So here is a patch on top to do so (the original branch is
jk/parse-object-type-mismatch for the benefit of any newly-returned
maintainers).

I was going to do a "helped-by", but since the only thing in the patch
is the suggested change, I just handed over authorship. :)

I didn't forge a signoff, and I think mine is sufficient under DCO's
part (b), but Ævar please indicate if that's OK.

-- >8 --
From: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Subject: [PATCH] parse_object(): simplify blob conditional

Commit 8db2dad7a0 (parse_object(): check on-disk type of suspected blob,
2022-11-17) simplified the conditional for checking if we might have a
blob. But we can simplify it further. In:

  !obj || (obj && obj->type == OBJ_BLOB)

the short-circuit "OR" means "obj" will always be true on the right-hand
side. The compiler almost certainly optimized that out anyway, but
dropping it makes the conditional easier to understand for humans.

Signed-off-by: Jeff King <peff@peff.net>
---
 object.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/object.c b/object.c
index fad1a5af4a..682b852a46 100644
--- a/object.c
+++ b/object.c
@@ -286,7 +286,7 @@ struct object *parse_object_with_flags(struct repository *r,
 			return &commit->object;
 	}
 
-	if ((!obj || (obj && obj->type == OBJ_BLOB)) &&
+	if ((!obj || obj->type == OBJ_BLOB) &&
 	    oid_object_info(r, oid, NULL) == OBJ_BLOB) {
 		if (!skip_hash && stream_object_signature(r, repl) < 0) {
 			error(_("hash mismatch %s"), oid_to_hex(oid));
-- 
2.38.1.950.g65ed8c1df8