Re: [PATCH v5 0/4] history: add squash subcommand to fold a range

> Phillip Wood <phillip.wood123@gmail.com> writes:
> 
>> We should sanitize what the user passes though - we do not want to
>> accept arbitrary rev-list options. Off the top of my head "--left-only"
>> and "--right-only" would allow the use of "A...B" and allowing "--not"
>> seems reasonable.
> 
> I would not recommend guessing what these rev-list "expressions"
> would produce and blacklist some of the operations and notations.
> It would be a more robust approach to let the machinery do its thing
> to determine the set of commits, *and* inspect the shape of the
> history these commits represent.  Are they connected?  Do they have
> a single "bottom" that is just outside and below the range so that
> we can replace it with the result of squashing everything together?
> Do they have a single "top" whose children can be rewritten to have
> the resulting single commit as one of their parents?  Starting from
> the acceptable shape of the history we want to deal with, rather
> than trying to enumerate rev-list operations and notations that
> would prevent the resulting set of commits to fall outside the
> acceptable shape of the history (and I am reasonably sure anybody
> who attempts to do so would either end up with unusablly narrow
> subset of what we can reasonably handle, or miss some cases that we
> do not want to handle), would be a better approach.