Re: [RFC/PATCH] patch-ids: check modified paths before calculating diff

From: Junio C Hamano <gitster@pobox.com>
Date: May 29, 2013, 18:48 UTC
Message-ID: <7vy5axsju2.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20130529183658.GA15616@sigill.intra.peff.net>

Jeff King <peff@peff.net> writes:

Show 17 quoted lines

> On Wed, May 29, 2013 at 11:08:46AM -0700, Junio C Hamano wrote:
>
>> This has rather interesting ramifications on cherry-pick and rebase,
>> though.  Both command can handle changes that come from an old tree
>> before some paths were renamed, but strict patch-id would not spot
>> equivalent changes we already have in our history if our change
>> happened after a rename, i.e.
>> 
>>    Z
>>   /
>>  O---R---X---Y
>> 
>> where Z updates path F, R moves F to G and X changes G the same way
>> as Z changes F, and we are trying to cherry-pick Z on top of Y.  The
>> cherry-pick filter will see different patch-id for Z and X.
>
> True. That is a problem with the current patch-id system, no?

Correct. That is why I suggested not to change the external interface (i.e. what is shown from patch-id command) as people may have kept them, but wondered if a possible improvement may be to exclude the name from ids when we internally generate two sets of Ids and intersect them, i.e. log --cherry.