…en in pure C

At this stage on the journey to a fully built-in git add, we already have
everything we need, including the --interactive and --patch options, as long
as the add.interactive.useBuiltin setting is set to true. This config
setting is kind of a feature flag that is currently turned off by default,
and will be for a while, until we get confident enough that the built-in
version does the job, and retire the Perl script.

However, the internal add--interactive helper is also used to back the
--patch option of git stash, git reset, git checkout and git worktree.

This patch series (based on js/add-p-in-c) brings them "online".

Changes since v1:

 * Renamed patch_mode_stage to patch_mode_add (and ADD_P_STAGE to ADD_P_ADD
   ).
 * Renamed the fields diff, apply and apply_check (that were inherited from
   the Perl script) to diff_cmd, apply_args and apply_check_args,
   respectively.
 * Clarified the magic array size 4 of diff_cmd and friends.
 * Introduced pseudo value PROMPT_MODE_MAX to make the array size of
   prompt_mode more obvious.
 * Got rid of the unneeded = 0 initializers for is_reverse.

Johannes Schindelin (7):
  built-in add -p: prepare for patch modes other than "stage"
  built-in add -p: implement the "stash" and "reset" patch modes
  legacy stash -p: respect the add.interactive.usebuiltin setting
  built-in stash: use the built-in `git add -p` if so configured
  built-in add -p: implement the "checkout" patch modes
  built-in add -p: implement the "worktree" patch modes
  commit --interactive: make it work with the built-in `add -i`

 add-interactive.c   |   2 +-
 add-interactive.h   |  12 +-
 add-patch.c         | 356 ++++++++++++++++++++++++++++++++++++++++----
 builtin/add.c       |  35 ++++-
 builtin/commit.c    |   8 +-
 builtin/stash.c     |  25 ++--
 git-legacy-stash.sh |   2 +-
 7 files changed, 390 insertions(+), 50 deletions(-)

base-commit: 2e4083198d1508206488af4c82093ceb6cf20f4e

Submitted-As: https://lore.kernel.org/git/pull.174.v2.git.1576965436.gitgitgadget@gmail.com
In-Reply-To: https://lore.kernel.org/git/pull.174.git.1576579264.gitgitgadget@gmail.com