On Thu, Jan 17 2019, Nguyễn Thái Ngọc Duy wrote:

This series converts diff option parsing to using parse-options. There
are a couple benefits of using parse-options, including "git <cmd> -h"
output, completion and less duplicate work.

This is the first half. The second one would be converting the option
parser in revision.c.  After that, the end game is, any command can
take a 'struct option[]' somewhere from diff/rev code, remove the
options they are not interested, then merge with their own options and
do parse_options() just once. There will be no separate parse phase
for revision/diff anymore.

I sent a sneak peek [1] last year and got two good comments. I take it
people at least did not oppose to this. The most interesting parts are
at the top and bottom. The middle is just boring conversion, usually
one option per patch.

I'm very much for this, and have skimmed it (but not stress tested) and
it looks good to me. I have some WIP patches to --abbrev that conflict,
but which will be simpler as a result of this.