sequencer: allow to --skip current commitgb/cherry-pick-skip

If a sequencing gets interrupted (by a conflict or an empty commit or
whatever), the user can now opt to just skip it passing the `--skip`
command line option, which acts like a `--continue`, except that the
current commit gets skipped.

Signed-off-by: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

4 files changed, 43 insertions, 8 deletions

diff --git a/Documentation/sequencer.txt b/Documentation/sequencer.txt
index 5747f442f2..095d6cd732 100644
--- a/Documentation/sequencer.txt
+++ b/Documentation/sequencer.txt
@@ -1,7 +1,15 @@
 --continue::
 	Continue the operation in progress using the information in
 	'.git/sequencer'.  Can be used to continue after resolving
-	conflicts in a failed cherry-pick or revert.
+	conflicts in a failed cherry-pick or revert.  Use `--skip`
+	instead if the current commit should be ignored.
+
+--skip::
+	Skips the current commit, and then continues the operation
+	in progress using the information in '.git/sequencer'.i
+	Can be used to continue to a cherry-pick or rever that was
+	interrupted by an empty commit, or by a commit that conflicts
+	and for which the resolution is to discard the commit.
 
 --quit::
 	Forget about the current operation in progress.  Can be used
diff --git a/builtin/revert.c b/builtin/revert.c
index aca8a1d9d0..dece0bebf7 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -79,6 +79,7 @@ static int run_sequencer(int argc, const char **argv, struct replay_opts *opts)
 	struct option base_options[] = {
 		OPT_CMDMODE(0, "quit", &cmd, N_("end revert or cherry-pick sequence"), 'q'),
 		OPT_CMDMODE(0, "continue", &cmd, N_("resume revert or cherry-pick sequence"), 'c'),
+		OPT_CMDMODE(0, "skip", &cmd, N_("resume revert or cherry-pick sequence, skipping this commit"), 's'),
 		OPT_CMDMODE(0, "abort", &cmd, N_("cancel revert or cherry-pick sequence"), 'a'),
 		OPT_BOOL('n', "no-commit", &opts->no_commit, N_("don't automatically commit")),
 		OPT_BOOL('e', "edit", &opts->edit, N_("edit the commit message")),
@@ -127,6 +128,8 @@ static int run_sequencer(int argc, const char **argv, struct replay_opts *opts)
 			this_operation = "--quit";
 		else if (cmd == 'c')
 			this_operation = "--continue";
+		else if (cmd == 's')
+			this_operation = "--skip";
 		else {
 			assert(cmd == 'a');
 			this_operation = "--abort";
@@ -188,8 +191,8 @@ static int run_sequencer(int argc, const char **argv, struct replay_opts *opts)
 
 	if (cmd == 'q')
 		return sequencer_remove_state(opts);
-	if (cmd == 'c')
-		return sequencer_continue(opts);
+	if (cmd == 'c' || cmd == 's')
+		return sequencer_continue(opts, cmd);
 	if (cmd == 'a')
 		return sequencer_rollback(opts);
 	return sequencer_pick_revisions(opts);
diff --git a/sequencer.c b/sequencer.c
index d2d9aced19..684b341e14 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -1359,21 +1359,45 @@ static int continue_single_pick(void)
 	return run_command_v_opt(argv, RUN_GIT_CMD);
 }
 
-int sequencer_continue(struct replay_opts *opts)
+/*
+ * Continue the sequencing, after either committing
+ * (cmd == 'c') or skipping (cmd == 's') the current
+ * commit.
+ */
+int sequencer_continue(struct replay_opts *opts, char cmd)
 {
 	struct todo_list todo_list = TODO_LIST_INIT;
-	int res;
+	int single, res;
 
 	if (read_and_refresh_cache(opts))
 		return -1;
 
-	if (!file_exists(get_todo_path(opts)))
-		return continue_single_pick();
+	if (!file_exists(get_todo_path(opts))) {
+		if (cmd == 'c') {
+			return continue_single_pick();
+		} else {
+			assert(cmd == 's');
+			/* Skipping the only commit is equivalent to an abort */
+			return sequencer_rollback(opts);
+		}
+	}
 	if (read_populate_opts(opts))
 		return -1;
 	if ((res = read_populate_todo(&todo_list, opts)))
 		goto release_todo_list;
 
+	/* If we were asked to skip this commit, rollback
+	 * and continue with the next */
+	if (cmd == 's') {
+		if ((res = rollback_single_pick()))
+			goto release_todo_list;
+		discard_cache();
+		if ((res = read_cache()) < 0)
+			goto release_todo_list;
+		printf("index unchanged: %d\n", is_index_unchanged());
+		goto skip_this_commit;
+	}
+
 	/* check if there is something to commit */
 	res = is_index_unchanged();
 	if (res < 0)
diff --git a/sequencer.h b/sequencer.h
index f8b8bd0063..afc4bb4e6c 100644
--- a/sequencer.h
+++ b/sequencer.h
@@ -41,7 +41,7 @@ struct replay_opts {
 #define REPLAY_OPTS_INIT { -1 }
 
 int sequencer_pick_revisions(struct replay_opts *opts);
-int sequencer_continue(struct replay_opts *opts);
+int sequencer_continue(struct replay_opts *opts, char cmd);
 int sequencer_rollback(struct replay_opts *opts);
 int sequencer_remove_state(struct replay_opts *opts);