On Wed, 21 Jun 2017 10:22:38 -0700
Junio C Hamano <gits...@pobox.com> wrote:
> Jonathan Tan <jonathanta...@google.com> writes:
>
> > The LOOKUP_UNKNOWN_OBJECT flag was introduced in commit 46f0344
> > ("sha1_file: support reading from a loose object of unknown type",
> > 2015-05-03) in order to support a feature in cat-file subsequently
> > introduced in commit 39e4ae3 ("cat-file: teach cat-file a
> > '--allow-unknown-type' option", 2015-05-03). Despite its name and
> > location in cache.h, this flag is used neither in
> > read_sha1_file_extended() nor in any of the lookup functions, but used
> > only in sha1_object_info_extended().
> >
> > Therefore rename this flag to OBJECT_INFO_ALLOW_UNKNOWN_TYPE, taking the
> > name of the cat-file flag that invokes this feature, and move it closer
> > to the declaration of sha1_object_info_extended(). Also add
> > documentation for this flag.
>
> All of the above makes sense, but ...
>
> > diff --git a/cache.h b/cache.h
> > index 4d92aae0e..e2ec45dfe 100644
> > --- a/cache.h
> > +++ b/cache.h
> > @@ -1207,7 +1207,6 @@ extern char *xdg_cache_home(const char *filename);
> >
> > /* object replacement */
> > #define LOOKUP_REPLACE_OBJECT 1
> > -#define LOOKUP_UNKNOWN_OBJECT 2
> > extern void *read_sha1_file_extended(const unsigned char *sha1, enum
> > object_type *type, unsigned long *size, unsigned flag);
> > static inline void *read_sha1_file(const unsigned char *sha1, enum
> > object_type *type, unsigned long *size)
> > {
> > @@ -1866,6 +1865,8 @@ struct object_info {
> > */
> > #define OBJECT_INFO_INIT {NULL}
> >
> > +/* Allow reading from a loose object file of unknown/bogus type */
> > +#define OBJECT_INFO_ALLOW_UNKNOWN_TYPE 2
>
> ... this contradicts the analysis given, doesn't it?
>
> Does something break if we change this to 1 (perhaps because in some
> cases this bit reach read_sha1_file_extended())? I doubt it, but
> leaving this to still define the bit to 2 makes readers wonder why.
The issue is that LOOKUP_REPLACE_OBJECT (which is 1) is also used by
sha1_object_info_extended(). So yes, it will break if
OBJECT_INFO_ALLOW_UNKNOWN_TYPE is changed to 1. I'm resolving this in
the next patch by also renaming LOOKUP_REPLACE_OBJECT and making it only
used by sha1_object_info_extended().
I'll add a comment in the commit message locally, and will resend it out
tomorrow (in case more comments come).
