[PATCH v5 0/4] Beginning of new merge strategy: New API, empty implementation

In this series, I show the new merge API I have developed in merge-ort, and show how it differs from that provided by merge-recursive. I do this in four steps, each corresponding to a patch.

Changes since v4:

 * Fix a bug where 'cherry-pick --continue' would report 'fatal:
   cherry-pick: --strategy cannot be used with --continue' when pull.twohead
   was set to ort (found by user of internal deployment at $DAYJOB)

Elijah Newren (4):
  merge-ort: barebones API of new merge strategy with empty
    implementation
  merge-ort-wrappers: new convience wrappers to mimic the old merge API
  fast-rebase: demonstrate merge-ort's API via new test-tool command
  merge,rebase,revert: select ort or recursive by config or environment

 Makefile                    |   3 +
 builtin/merge.c             |  26 ++++-
 builtin/rebase.c            |  13 ++-
 builtin/revert.c            |   7 ++
 merge-ort-wrappers.c        |  62 +++++++++++
 merge-ort-wrappers.h        |  25 +++++
 merge-ort.c                 |  52 +++++++++
 merge-ort.h                 |  58 ++++++++++
 sequencer.c                 |  72 ++++++++++--
 sequencer.h                 |   1 +
 t/helper/test-fast-rebase.c | 211 ++++++++++++++++++++++++++++++++++++
 t/helper/test-tool.c        |   1 +
 t/helper/test-tool.h        |   1 +
 13 files changed, 517 insertions(+), 15 deletions(-)
 create mode 100644 merge-ort-wrappers.c
 create mode 100644 merge-ort-wrappers.h
 create mode 100644 merge-ort.c
 create mode 100644 merge-ort.h
 create mode 100644 t/helper/test-fast-rebase.c

base-commit: 69986e19ffcfb9af674ae5180689ab7bbf92ed28
Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-895%2Fnewren%2Fort-api-with-empty-implementation-v5
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-895/newren/ort-api-with-empty-implementation-v5
Pull-Request: https://github.com/git/git/pull/895

Range-diff vs v4:

 1:  3357ea415e = 1:  3357ea415e merge-ort: barebones API of new merge strategy with empty implementation
 2:  d7f6a834ab = 2:  d7f6a834ab merge-ort-wrappers: new convience wrappers to mimic the old merge API
 3:  fce0db8778 = 3:  fce0db8778 fast-rebase: demonstrate merge-ort's API via new test-tool command
 4:  75d19804bd ! 4:  61217a83bd merge,rebase,revert: select ort or recursive by config or environment
     @@ builtin/rebase.c: static struct replay_opts get_replay_opts(const struct rebase_
      -	replay.strategy = opts->strategy;
      +	if (opts->strategy)
      +		replay.strategy = opts->strategy;
     ++	else if (!replay.strategy && replay.default_strategy) {
     ++		replay.strategy = replay.default_strategy;
     ++		replay.default_strategy = NULL;
     ++	}
       
       	if (opts->strategy_opts)
       		parse_strategy_opts(&replay, opts->strategy_opts);
     @@ builtin/rebase.c: int cmd_rebase(int argc, const char **argv, const char *prefix
       	case REBASE_PRESERVE_MERGES:
      
       ## builtin/revert.c ##
     +@@ builtin/revert.c: static int run_sequencer(int argc, const char **argv, struct replay_opts *opts)
     + 				NULL);
     + 	}
     + 
     ++	if (!opts->strategy && opts->default_strategy) {
     ++		opts->strategy = opts->default_strategy;
     ++		opts->default_strategy = NULL;
     ++	}
     ++
     + 	if (opts->allow_ff)
     + 		verify_opt_compatible(me, "--ff",
     + 				"--signoff", opts->signoff,
      @@ builtin/revert.c: static int run_sequencer(int argc, const char **argv, struct replay_opts *opts)
       	/* These option values will be free()d */
       	opts->gpg_sign = xstrdup_or_null(opts->gpg_sign);
     @@ sequencer.c: static int git_sequencer_config(const char *k, const char *v, void
       		return 0;
       	}
       
     -+	if (!opts->strategy && !strcmp(k, "pull.twohead")) {
     -+		int ret = git_config_string((const char**)&opts->strategy, k, v);
     ++	if (!opts->default_strategy && !strcmp(k, "pull.twohead")) {
     ++		int ret = git_config_string((const char**)&opts->default_strategy, k, v);
      +		if (ret == 0) {
      +			/*
      +			 * pull.twohead is allowed to be multi-valued; we only
      +			 * care about the first value.
      +			 */
     -+			char *tmp = strchr(opts->strategy, ' ');
     ++			char *tmp = strchr(opts->default_strategy, ' ');
      +			if (tmp)
      +				*tmp = '\0';
      +		}
     @@ sequencer.c: static int git_sequencer_config(const char *k, const char *v, void
       	status = git_gpg_config(k, v, NULL);
       	if (status)
       		return status;
     +@@ sequencer.c: int sequencer_remove_state(struct replay_opts *opts)
     + 	free(opts->committer_name);
     + 	free(opts->committer_email);
     + 	free(opts->gpg_sign);
     ++	free(opts->default_strategy);
     + 	free(opts->strategy);
     + 	for (i = 0; i < opts->xopts_nr; i++)
     + 		free(opts->xopts[i]);
      @@ sequencer.c: static int do_recursive_merge(struct repository *r,
       			      struct replay_opts *opts)
       {
     @@ sequencer.c: static int do_merge(struct repository *r,
       	if (ret <= 0)
       		fputs(o.obuf.buf, stdout);
       	strbuf_release(&o.obuf);
     +
     + ## sequencer.h ##
     +@@ sequencer.h: struct replay_opts {
     + 	int explicit_cleanup;
     + 
     + 	/* Merge strategy */
     ++	char *default_strategy;  /* from config options */
     + 	char *strategy;
     + 	char **xopts;
     + 	size_t xopts_nr, xopts_alloc;