Re: [PATCH 1/2] diff: Fix modified lines stats with --stat and --numstat

From: Junio C Hamano <gitster@pobox.com>
Date: Sep 18, 2020, 18:06 UTC
Message-ID: <xmqq363fm02a.fsf@gitster.c.googlers.com>
In-Reply-To: <CALqVohcZrBcjmonw-peVxUNM1kgEheCr3nAk9ZvajGpbpXsNaQ@mail.gmail.com>

Thomas Guyot-Sionnest <tguyot@gmail.com> writes:

Show 15 quoted lines

>> > -     same_contents = oideq(&one->oid, &two->oid);
>> > +     if (one->is_stdin && two->is_stdin)
>> > +             same_contents = !strcmp(one->data, two->data);
>> > +     else
>> > +             same_contents = oideq(&one->oid, &two->oid);
>>
>> ...should this actually be checking the oid_valid flag in each filespec?
>> That would presumably cover the is_stdin case, too. I also wonder
>> whether range-diff ought to be using that flag instead of is_stdin.
>
> I considered that, but IIRC when run under a debugger oid_valid was
> set to 0 - it seemed to be used for something different that i'm not
> familiar with, maybe it's an indication the object is in git datastore
> (whereas with --no-index outside files will only be hashed for
> comparison).

If it says !oid_valid, I think you are getting what you do want. The contents from the outside world, be it what was read from the standard input or a pipe, a regular file that is not up-to-date with the index, may not have a usable oid computed for it, and oid_valid being false signals you that you need byte-for-byte comparison. As suggested by Peff in another message, you can take that signal and compare the size and then the contents with memcmp() to see if they are the same.