surprising error message in parse_opt_with_commit

surprising error message in parse_opt_with_commit

[Tim Harper]

When I typed 'git branch --contains efabdfb' on a machine today, I was
surprised to receive this error message: "error: malformed object name
efabdfb"

I would have expected instead to receive the message: "no such commit: efabdfb".

I went hunting through the source code and found the origination point
of the error:

/parse-options.c
 610 int parse_opt_with_commit(const struct option *opt, const char
*arg, int unset)
 611 {
 612 	unsigned char sha1[20];
 613 	struct commit *commit;
 614
 615 	if (!arg)
 616 		return -1;
 617 	if (get_sha1(arg, sha1))
 618 		return error("malformed object name %s", arg);
 619 	commit = lookup_commit_reference(sha1);
 620 	if (!commit)
 621 		return error("no such commit %s", arg);
 622 	commit_list_insert(commit, opt->value);
 623 	return 0;
 624 }

It appears the get_sha1 call is returning true, causing the 'malformed
object name' error to be returned.  However, it seems that ideally
since efabdfb is not malformed (it would be a valid ref if it
existed), the execution path should continue to line 619, receive no
commit, and fail on 621.

Am I off base here?

Re: surprising error message in parse_opt_with_commit

[Shawn O. Pearce]

Tim Harper <timcharper@gmail.com> wrote:
>  610 int parse_opt_with_commit(const struct option *opt, const char
> *arg, int unset)
>  611 {
>  612 	unsigned char sha1[20];
>  613 	struct commit *commit;
>  614
>  615 	if (!arg)
>  616 		return -1;
>  617 	if (get_sha1(arg, sha1))
>  618 		return error("malformed object name %s", arg);
>  619 	commit = lookup_commit_reference(sha1);
>  620 	if (!commit)
>  621 		return error("no such commit %s", arg);
>  622 	commit_list_insert(commit, opt->value);
>  623 	return 0;
>  624 }
> 
> It appears the get_sha1 call is returning true, causing the 'malformed
> object name' error to be returned.  However, it seems that ideally
> since efabdfb is not malformed (it would be a valid ref if it
> existed), the execution path should continue to line 619, receive no
> commit, and fail on 621.

get_sha1 is responsible for expanding an abbreviated ID to the
full ID.  If it can't do the expansion, it errors out.  The code
is correct as-is, though the error message on 618 is a bit odd.

-- 
Shawn.

Re: surprising error message in parse_opt_with_commit

[Tim Harper]

On Thu, Aug 6, 2009 at 1:34 PM, Shawn O. Pearce<spearce@spearce.org> wrote:
> Tim Harper <timcharper@gmail.com> wrote:
>>  610 int parse_opt_with_commit(const struct option *opt, const char
>> *arg, int unset)
>>  611 {
>>  612  unsigned char sha1[20];
>>  613  struct commit *commit;
>>  614
>>  615  if (!arg)
>>  616          return -1;
>>  617  if (get_sha1(arg, sha1))
>>  618          return error("malformed object name %s", arg);
>>  619  commit = lookup_commit_reference(sha1);
>>  620  if (!commit)
>>  621          return error("no such commit %s", arg);
>>  622  commit_list_insert(commit, opt->value);
>>  623  return 0;
>>  624 }
>>
>> It appears the get_sha1 call is returning true, causing the 'malformed
>> object name' error to be returned.  However, it seems that ideally
>> since efabdfb is not malformed (it would be a valid ref if it
>> existed), the execution path should continue to line 619, receive no
>> commit, and fail on 621.
>
> get_sha1 is responsible for expanding an abbreviated ID to the
> full ID.  If it can't do the expansion, it errors out.  The code
> is correct as-is, though the error message on 618 is a bit odd.
>
> --
> Shawn.
>

ok, that makes more sense.  I notice if I pass a full, mutated
40-character sha1 commit, I get the error message I expect.