From: René Scharfe <rene.scharfe@lsrfire.ath.cx>
Date: Thu, 10 Feb 2011 18:50:35 GMT
Subject: Re: Can't find the revelant commit with git-log
Message-ID: <4D54337B.6040307@lsrfire.ath.cx>
In-Reply-To: <7vk4hbsbjr.fsf@alter.siamese.dyndns.org>

Am 07.02.2011 23:51, schrieb Junio C Hamano:
> René Scharfe<rene.scharfe@lsrfire.ath.cx>  writes:
>
>> diff --git a/t/t6016-rev-list-graph-simplify-history.sh b/t/t6016-rev-list-graph-simplify-history.sh
>> index f7181d1..50ffcf4 100755
>> --- a/t/t6016-rev-list-graph-simplify-history.sh
>> +++ b/t/t6016-rev-list-graph-simplify-history.sh
>> @@ -168,6 +168,7 @@ test_expect_success '--graph --full-history --simplify-merges -- bar.txt' '
>>   	echo "|\\  ">>  expected&&
>>   	echo "| * $C4">>  expected&&
>>   	echo "* | $A5">>  expected&&
>> +	echo "* | $A4">>  expected&&
>>   	echo "* | $A3">>  expected&&
>>   	echo "|/  ">>  expected&&
>>   	echo "* $A2">>  expected&&
>
> Thanks for a patch with a test; I am not sure if this is quite correct,
> though.
>
> A4 has three parents, C2, A3 and B2, and does not introduce any change
> with respect to bar.txt.  A6 has bar.txt identical to that of A5, but we
> cannot omit it because we are showing its two parents (A5 and C4), and
> that is why we show it.  A4 isn't even gets shown as a merge, so I don't
> understand why we need to show it?

Yes, this looks a bit silly on closer look.  I thought that it matches 
Francis' use case, but that's wrong -- having --simplify-merges instead 
of -Sstring makes a difference, obviously.

After looking at the case again, I think I have a simpler solution: no 
code change, just add --sparse (include all walked commits).  This gives 
the same results as the patched version:

	$ git log --oneline -m --sparse --full-history \
		-Sblacklist_iommu v2.6.26..v2.6.29 -- \
		drivers/pci/intel-iommu.c | wc -l
	    160

Sorry for the noise.

So, the lesson would be: If you want to find commits that removed a 
certain string in a certain set of files, add --full-history, -m and 
--sparse to your "git log -Sstring -- files" command.  This allows you 
to catch merges that reverted those files to a state before the string 
was introduced in the first place, otherwise history simplification can 
hide them.

I'm not sure if there's a way to make the flags and their interactions 
more intituitive.

René