Re: [BUG?] --boundary inconsistent with path limiting

[Jeff King <peff@peff.net>]

On Thu, Aug 04, 2016 at 03:40:43PM -0400, Jeff King wrote:

> That makes sense to me. We omit "c" because it doesn't touch "b.t", and
> obviously include "b", which does. We _do_ include the boundary commit,
> even though it doesn't touch the path, which makes sense to me. It
> remains a boundary whether it touched the path or not, and without it,
> we get no boundary at all.
> 
> But now if I limit to "a.t", I get no output at all:
> 
>   $ git log --format='%m %s' --boundary a..c -- a.t
> 
> whereas I would have expected "- a" to show the boundary.
> 
> Is this a bug, or are my expectations wrong?

So I suppose it depends how you define "boundary" commits. In
get_revision_internal(), I see this comment:

        /*
         * boundary commits are the commits that are parents of the
         * ones we got from get_revision_1() but they themselves are
         * not returned from get_revision_1().  Before returning
         * 'c', we need to mark its parents that they could be boundaries.
         */

By that definition, obviously if we do not have any commits to show,
then we have no boundary commits. I don't think this definition is
anywhere in the user-facing documentation, though.

It still seems weird to me, and I wonder if we should show all
UNINTERESTING commits as boundaries in the case that we haven't produced
any positive commits at all. But perhaps there is a case where that
would not be desirable.

-Peff