Re: [PATCH 3/5] interpret-trailers: add an option to show only existing trailers

[Jeff King <peff@peff.net>]

On Wed, Aug 09, 2017 at 11:38:20AM -0700, Jonathan Tan wrote:

> > diff --git a/t/t7513-interpret-trailers.sh b/t/t7513-interpret-trailers.sh
> > index e5b0718ef6..525fd53e5b 100755
> > --- a/t/t7513-interpret-trailers.sh
> > +++ b/t/t7513-interpret-trailers.sh
> > @@ -1312,4 +1312,19 @@ test_expect_success 'only-trailers omits non-trailer in middle of block' '
> >  	test_cmp expected actual
> >  '
> >  
> > +test_expect_success 'only existing' '
> > +	cat >expected <<-\EOF &&
> > +		existing: existing-value
> > +	EOF
> > +	git interpret-trailers \
> > +		--only-trailers --only-existing >actual <<-\EOF &&
> > +		my subject
> > +
> > +		my body
> > +
> > +		existing: existing-value
> > +	EOF
> > +	test_cmp expected actual
> 
> Would it be worth asserting that the "sign" trailer is configured here
> and would normally appear? Maybe through a grep on the output of "git
> config".

I'd much rather re-add it than assert it with grep hackery. Note that
its presence is implied in all of the follow-on tests, too (so I had
sort of assumed that its presence in the --only-trailers test would
imply that it was carried through to the others). We can be more
explicit, though, I guess.

> > diff --git a/trailer.c b/trailer.c
> > index a4ff99f98a..88f6efe523 100644
> > --- a/trailer.c
> > +++ b/trailer.c
> > @@ -991,9 +991,10 @@ void process_trailers(const char *file, struct process_trailer_options *opts,
> >  	trailer_end = process_input_file(opts->only_trailers ? NULL : outfile,
> >  					 sb.buf, &head);
> >  
> > -	process_command_line_args(&arg_head, trailers);
> > -
> > -	process_trailers_lists(&head, &arg_head);
> > +	if (!opts->only_existing) {
> > +		process_command_line_args(&arg_head, trailers);
> > +		process_trailers_lists(&head, &arg_head);
> > +	}
> 
> This is a bit confusing, but it is correct, since
> process_command_line_args() processes both configured trailers and
> command-line trailers.

Yes, it confused me, too. That combination is why "--trailer" is
disallowed with --only-existing (which otherwise could work together). I
didn't think it was worth refactoring for a case that I don't think
anybody would care about.

> Having said that, it might be worth declaring LIST_HEAD(arg_head) inside
> the if block now.

Agreed.

-Peff