Re: git log -S or -G

>
> On Tue, Oct 09, 2018 at 08:09:32AM +0900, Junio C Hamano wrote:
>
> > Julia Lawall <julia.lawall@lip6.fr> writes:
> >
> > >> Doing the same for -S is much harder at the machinery level, as it
> > >> performs its thing without internally running "diff" twice, but just
> > >> counts the number of occurrences of 'foo'---that is sufficient for
> > >> its intended use, and more efficient.
> > >
> > > There is still the question of whether the number of occurrences of foo
> > > decreases or increases.
> >
> > Hmph, taking the changes that makes the number of hits decrease
> > would catch a subset of "changes that removes 'foo' only---I am not
> > interested in the ones that adds 'foo'".  It will avoid getting
> > confused by a change that moves an existing 'foo' to another place
> > in the same file (as the number of hits does not change), but at the
> > same time, it will miss a change that genuinely removes an existing
> > 'foo' and happens to add a 'foo' at a different place in the same
> > file that is unrelated to the original 'foo'.  Depending on the
> > definition of "I am only interested in removed ones", that may or
> > may not be acceptable.
>
> I think that is the best we could do for "-S", though, which is
> inherently about counting hits.
>
> For "-G", we are literally grepping the diff. It does not seem
> unreasonable to add the ability to grep only "-" or "+" lines, and the
> interface for that should be pretty straightforward (a tri-state flag to
> look in remove, added, or both lines).
>
> -Peff