Re: [PATCH v2 00/10] improve reporting of unexpected objects

> Ævar Arnfjörð Bjarmason (10):
>   object.c: stop supporting len == -1 in type_from_string_gently()
>   object.c: refactor type_from_string_gently()
>   object.c: make type_from_string() return "enum object_type"
>   object-file.c: make oid_object_info() return "enum object_type"
>   object-name.c: make dependency on object_type order more obvious
>   tree.c: fix misindentation in parse_tree_gently()
>   object.c: add a utility function for "expected type X, got Y"
>   object.c: add and use oid_is_type_or_die_msg() function
>   object tests: add test for unexpected objects in tags
>   tag: don't misreport type of tagged objects in errors

> Because when we call, say, lookup_blob() and find that the object is
> already in memory as a non-blob, we don't know who the culprit is.
> Perhaps an earlier part of the code called parse_object(), found that it
> really is a blob on disk, and used that type. But it may equally have
> been the case that we saw a reference to the object as a commit, called
> lookup_commit() on it, and now our lookup_blob() call is unhappy,
> thinking it is really a commit. In that case, one of those references is
> wrong, but we don't know which.
>
> I think a robust solution would be one of:
>
>   - make the message more precise: "saw object X as a commit, but
>     previously it was referred to as a blob". Or vice versa.
>
>   - when we see such a mismatch, go to the object database to say "aha,
>     on disk it is really a blob". That's expensive, but this is an error
>     case, so we can afford to be slow. But it does produce unsatisfying
>     results when it was the earlier lookup_commit() call that was wrong.
>     Because we have to say "object X is really a blob, but some object
>     earlier referred to it as a commit. No idea who did that, though!".