[PATCH 5/8] revert: Catch incompatible command-line options early

[Ramkumar Ramachandra <artagnon@gmail.com>]

Earlier, incompatible command-line options used to be caught in
pick_commits after parse_args has parsed the options and populated the
options structure; a lot of unncessary work has already been done, and
significant amount of cleanup is required to die at this stage.
Instead, hand over this responsibility to parse_args so that the
program can die early.  Also write a die_opt_incompabile function to
handle incompatible options in a general manner; it will be used more
extensively as more command-line options are introduced later in the
series.

Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 I think we _should_ die when an error in command-line parsing occurs,
 since it should always be the toplevel caller.  Thanks to Junio for
 redesigning die_opt_incompatible in a sane manner.

 builtin/revert.c |   37 ++++++++++++++++++++++++++-----------
 1 files changed, 26 insertions(+), 11 deletions(-)

diff --git a/builtin/revert.c b/builtin/revert.c
index 288c898..0fe87e8 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -80,10 +80,29 @@ static int option_parse_x(const struct option *opt,
 	return 0;
 }
 
+static void die_opt_incompatible(const char *me, const char *base_opt, ...)
+{
+	const char *this_opt;
+	int this_opt_set;
+	va_list ap;
+
+	va_start(ap, base_opt);
+	while (1) {
+		if (!(this_opt = va_arg(ap, const char *)))
+			break;
+		if ((this_opt_set = va_arg(ap, int)))
+			die(_("%s: %s cannot be used with %s"),
+				me, this_opt, base_opt);
+	}
+	va_end(ap);
+}
+
 static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 {
 	const char *const *usage_str = revert_or_cherry_pick_usage(opts);
+	const char *me = (opts->action == REVERT ? "revert" : "cherry-pick");
 	int noop;
+
 	struct option options[] = {
 		OPT_BOOLEAN('n', "no-commit", &(opts->no_commit), "don't automatically commit"),
 		OPT_BOOLEAN('e', "edit", &(opts->edit), "edit the commit message"),
@@ -121,6 +140,13 @@ static void parse_args(int argc, const char **argv, struct replay_opts *opts)
 	if (opts->commit_argc < 2)
 		usage_with_options(usage_str, options);
 
+	if (opts->allow_ff)
+		die_opt_incompatible(me, "--ff",
+				"--signoff", opts->signoff,
+				"--no-commit", opts->no_commit,
+				"-x", opts->no_replay,
+				"--edit", opts->edit,
+				NULL);
 	opts->commit_argv = argv;
 }
 
@@ -609,17 +635,6 @@ static int pick_commits(struct replay_opts *opts)
 	struct commit *commit;
 	int res;
 
-	if (opts->allow_ff) {
-		if (opts->signoff)
-			die(_("cherry-pick --ff cannot be used with --signoff"));
-		if (opts->no_commit)
-			die(_("cherry-pick --ff cannot be used with --no-commit"));
-		if (opts->no_replay)
-			die(_("cherry-pick --ff cannot be used with -x"));
-		if (opts->edit)
-			die(_("cherry-pick --ff cannot be used with --edit"));
-	}
-
 	if ((res = read_and_refresh_cache(opts)) ||
 		(res = prepare_revs(&revs, opts)))
 		return res;
-- 
1.7.5.GIT