From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andreas Schwab <schwab@linux-m68k.org>
Subject: Re: Specifying revisions in the future
Date: Sun, 05 Feb 2012 23:15:40 +0100
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Cc: Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>, jpaugh@gmx.us,
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To: Jakub Narebski <jnareb@gmail.com>
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Jakub Narebski <jnareb@gmail.com> writes:

> Andreas Schwab <schwab@linux-m68k.org> writes:
>> Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> writes:
>> 
>> > "the successor of <commit>", OTOH, is not well defined, since there can
>> > be several successors, and one can't order them reliably (you can't
>> > really know the set of successors, because they can exist in different
>> > repositories).
>> 
>> Yet it would be nice to have a concise notation for "the nth successor
>> of <commit> towards <commit>" (using --first-parent ordering when
>> ambiguous).
>
> First, "the nth successor"... from which refs?

>>From the first given commit towards the other given commit (the latter
defaulting to HEAD).

> Second, `--first-parent' won't help here.  Take for example the
> following situation:
>
>    ---X<---*<---.<---A
>             \
>              \--.<---B
>
> X+3 is A or B?

If "towards A" then it is A, if "towards B", it is B.  In other words,
to get the "nth successor of C1 towards C2" take the leftmost possible
parent when walking from C2 to C1, then walk back n commits along this
path.  This way you should have an unambigous definition.

Andreas.

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."