Re: [PATCH 2/2] hex: drop sha1_to_hex()

[Jeff King <peff@peff.net>]

On Tue, Nov 12, 2019 at 01:13:58PM +0900, Junio C Hamano wrote:

> >> We can't use oid_to_hex() because we don't have a 'struct object_id'
> >> in the first place, as sha1dc only ever deals with 20 unsigned chars.
> >
> > Ah, you're right. I admit I am still getting up to speed on all of the
> > new hash-agnostic versions of the various functions.
> 
> Thanks.  I've amended this one and the range diff since the pushout
> yesterday looks like this.

Thanks. This first hunk is what I would have done:

> 1:  8a030f1796 ! 1:  02d21d4117 hex: drop sha1_to_hex()
>     @@ Commit message
>          hex: drop sha1_to_hex()
>      
>          There's only a single caller left of sha1_to_hex(), since everybody now
>     -    uses oid_to_hex() instead. This case is in the sha1dc wrapper, where we
>     +    uses hash_to_hex() instead. This case is in the sha1dc wrapper, where we
>          print a hex sha1 when we find a collision. This one will always be sha1,
>     -    regardless of the current hash algorithm, so we can't use oid_to_hex()
>     +    regardless of the current hash algorithm, so we can't use hash_to_hex()
>          here. In practice we'd probably not be running sha1 at all if it isn't
>          the current algorithm, but it's possible we might still occasionally
>          need to compute a sha1 in a post-sha256 world.

This second one is OK, but not entirely necessary:

>     @@ cache.h: int hex_to_bytes(unsigned char *binary, const char *hex, size_t len);
>        * buffers, making it safe to make multiple calls for a single statement, like:
>        *
>      - *   printf("%s -> %s", sha1_to_hex(one), sha1_to_hex(two));
>     -+ *   printf("%s -> %s", oid_to_hex(one), oid_to_hex(two));
>     ++ *   printf("%s -> %s", hash_to_hex(one), hash_to_hex(two));
>        */
>       char *hash_to_hex_algop_r(char *buffer, const unsigned char *hash, const struct git_hash_algo *);
>       char *oid_to_hex_r(char *out, const struct object_id *oid);

This one-liner leaves the types of "one" and "two" unspecified. :) So
it's not wrong to use hash_to_hex(), but maybe it's better to be pushing
people towards oid_to_hex() as their first choice? It probably doesn't
matter too much either way.

-Peff