Re: "git add -p ." raises an unexpected "warning: empty strings as pathspecs will be made invalid in upcoming releases. please use . instead if you meant to match all paths"

> Junio C Hamano <gitster@pobox.com> forgot to Cc: the author of the
> most relevant change to the issue, d426430e6e ("pathspec: warn on
> empty strings as pathspec", 2016-06-22).
> 
> > Kevin Daudt <me@ikke.info> writes:
> >
> >> On Wed, Nov 30, 2016 at 12:31:49PM -0800, Peter Urda wrote:
> >>> After upgrading to version 2.11.0 I am getting a warning about empty
> >>> strings as pathspecs while using 'patch'
> >>> 
> >>> - Ran 'git add -p .' from the root of my git repository.
> >>> 
> >>> - I was able to normally stage my changes, but was presented with a
> >>> "warning: empty strings as pathspecs will be made invalid in upcoming
> >>> releases. please use . instead if you meant to match all paths"
> >>> message.
> >>> 
> >>> - I expected no warning message since I included a "." with my original command.
> >>> 
> >>> I believe that I should not be seeing this warning message as I
> >>> included the requested "." pathspec.
> >
> > Yes, this seems to be caused by pathspec.c::prefix_pathspec()
> > overwriting the original pathspec "." into "".  The callchain
> > looks like this:
> >
> >     builtin/add.c::interactive_add()
> >      -> parse_pathspec()
> >         passes argv[] that has "." to the caller,
> >         receives pathspec whose pathspec->items[].original
> > 	is supposed to point at the unmolested original,
> >         but prefix_pathspec() munges "." into ""
> >      -> run_add_interactive()
> >         which runs "git add--interactive" with
> > 	pathspec->items[].original as pathspecs
> >
> >
> > Perhaps this would work it around, but there should be a better way
> > to fix it (like, making sure that what we call "original" indeed
> > stays "original").
> >
> >  builtin/add.c | 13 +++++++++++--
> >  1 file changed, 11 insertions(+), 2 deletions(-)
> >
> > diff --git a/builtin/add.c b/builtin/add.c
> > index e8fb80b36e..137097192d 100644
> > --- a/builtin/add.c
> > +++ b/builtin/add.c
> > @@ -167,9 +167,18 @@ int run_add_interactive(const char *revision, const char *patch_mode,
> >  	if (revision)
> >  		argv_array_push(&argv, revision);
> >  	argv_array_push(&argv, "--");
> > -	for (i = 0; i < pathspec->nr; i++)
> > +	for (i = 0; i < pathspec->nr; i++) {
> >  		/* pass original pathspec, to be re-parsed */
> > +		if (!*pathspec->items[i].original) {
> > +			/*
> > +			 * work around a misfeature in parse_pathspecs()
> > +			 * that munges "." into "".
> > +			 */
> > +			argv_array_push(&argv, ".");
> > +			continue;
> > +		}
> >  		argv_array_push(&argv, pathspec->items[i].original);
> > +	}
> >  
> >  	status = run_command_v_opt(argv.argv, RUN_GIT_CMD);
> >  	argv_array_clear(&argv);
> > @@ -180,7 +189,7 @@ int interactive_add(int argc, const char **argv, const char *prefix, int patch)
> >  {
> >  	struct pathspec pathspec;
> >  
> > -	parse_pathspec(&pathspec, 0,
> > +	parse_pathspec(&pathspec, 0,
> >  		       PATHSPEC_PREFER_FULL |
> >  		       PATHSPEC_SYMLINK_LEADING_PATH |
> >  		       PATHSPEC_PREFIX_ORIGIN,