Re: [q] git-diff --reverse 7def2be1..7def2be1^

[Junio C Hamano <gitster@pobox.com>]

Dmitry Potapov <dpotapov@gmail.com> writes:

> On Sun, Jul 06, 2008 at 01:04:18PM -0700, Junio C Hamano wrote:
>>     Two other shorthands for naming a set that is formed by a commit
>>     and its parent commits exists.  `r1{caret}@` notation means all
>>     parents of `r1`.  `r1{caret}!` includes commit `r1` but excludes
>>     its all parents.
>
> So, I would say that rev^! is shorthand for rev^@..rev, but it does not
> actually work:
>
> git rev-list 7ac749c^@..7ac749c
> fatal: ambiguous argument '7ac749c^@..7ac749c': unknown revision or path
> not in the working tree.
>
> yet "^rev^@ rev" syntax does:
>
> git rev-list ^7ac749c^@ 7ac749c
> 7ac749c96d143ba4f76723959892cbaddbe8ed07
>
> Is it a bug or feature?
>
> Puzzled...

After reading these paragraphs from "SPECIFYING RANGES":

        History traversing commands such as 'git-log' operate on a set
        of commits, not just a single commit.  To these commands,
        specifying a single revision with the notation described in the
        previous section means the set of commits reachable from that
        commit, following the commit ancestry chain.

        To exclude commits reachable from a commit, a prefix `{caret}`
        notation is used.  E.g. "`{caret}r1 r2`" means commits reachable
        from `r2` but exclude the ones reachable from `r1`.

        This set operation appears so often that there is a shorthand
        for it.  "`r1..r2`" is equivalent to "`{caret}r1 r2`".  It is
        the difference of two sets (subtract the set of commits
        reachable from `r1` from the set of commits reachable from
        `r2`).

it is obvious to me that the third paragraph talks about r1 that is a
single rev (refer to SPECIFYING REVISIONS section, which does _NOT_ talk
about rev^@ nor rev^!)  and r2 that similarly is another single rev.  So I
think it is fairly clear that your "r^@..r" example is nonsense.

But perhaps these paragraphs need to be further reworded to avoid the
confusion.  I dunno.