Am 03.06.22 um 20:37 schrieb Ævar Arnfjörð Bjarmason:
> Adjust code added in 2775d8724d7 (packed_ref_store: implement
> reference transactions, 2017-09-08) to BUG() out in a case there GCC
> v12's -fanalyzer flagged that the "iter->oid" seen in the context was
> reachable where iter was NULL.
>
> Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx>
> ---
> refs/packed-backend.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/refs/packed-backend.c b/refs/packed-backend.c
> index 97b68377673..65991bbcaf5 100644
> --- a/refs/packed-backend.c
> +++ b/refs/packed-backend.c
> @@ -1226,6 +1226,8 @@ static int write_with_updates(struct packed_ref_store *refs,
> struct object_id peeled;
> int peel_error = ref_iterator_peel(iter, &peeled);
Some peel backends dereference iter, e.g. packed_ref_iterator_peel() from
the same file.
>
> + if (!iter)
> + BUG("must have iter if cmp < 0");
So if iter can be NULL at this point, then it must be checked before the
ref_iterator_peel() call above, no?
*Can* it be NULL, though? The code in question is a bit complicated and
it's late around here, but I cannot see how cmp < 0 and !iter can both
be true at this place in the code. An optimizing compiler will probably
optimize out the added check and string. Mine does (clang 13); you can
check if yours does the same using:
$ make refs/packed-backend.o && grep "must have" refs/packed-backend.o
> if (write_packed_entry(out, iter->refname,
> iter->oid,
> peel_error ? NULL : &peeled))
