git-commit: squelch needless message during an empty merge

When recording a merge that conflicted and ends up in no changes after
manual resolution, commit callchain looked like this:

	cmd_commit() ->
            prepare_log_message() ->
                run_status() ->
		    wt_status_print()

This invocation of run_status() is asked to find out if there is a
committable change, but it unconditionally gave instructions such as
"use git-add" at the same time.  When in merge, we do allow an empty
change to be recorded, so after showing this message the code still went
ahead and made a commit.

This introduces "nowarn" parameter to run_status() to avoid these
useless messages.  If we are not allowed to create an empty commit, we
already call run_status() again in the original codepath, and the
message will be shown from that call anyway.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-commit.c

@@ -280,7 +280,7 @@ static char *prepare_index(int argc, const char **argv, const char *prefix)
 	return false_lock.filename;
 }
 
-static int run_status(FILE *fp, const char *index_file, const char *prefix)
+static int run_status(FILE *fp, const char *index_file, const char *prefix, int nowarn)
 {
 	struct wt_status s;
 
@@ -296,6 +296,7 @@ static int run_status(FILE *fp, const char *index_file, const char *prefix)
 	s.untracked = untracked_files;
 	s.index_file = index_file;
 	s.fp = fp;
+	s.nowarn = nowarn;
 
 	wt_status_print(&s);
 
@@ -412,7 +413,7 @@ static int prepare_log_message(const char *index_file, const char *prefix)
 
 	saved_color_setting = wt_status_use_color;
 	wt_status_use_color = 0;
-	commitable = run_status(fp, index_file, prefix);
+	commitable = run_status(fp, index_file, prefix, 1);
 	wt_status_use_color = saved_color_setting;
 
 	fclose(fp);
@@ -606,7 +607,7 @@ int cmd_status(int argc, const char **argv, const char *prefix)
 
 	index_file = prepare_index(argc, argv, prefix);
 
-	commitable = run_status(stdout, index_file, prefix);
+	commitable = run_status(stdout, index_file, prefix, 0);
 
 	rollback_index_files();
 
@@ -717,7 +718,7 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
 
 	if (!prepare_log_message(index_file, prefix) && !in_merge &&
 	    !allow_empty && !(amend && is_a_merge(head_sha1))) {
-		run_status(stdout, index_file, prefix);
+		run_status(stdout, index_file, prefix, 0);
 		rollback_index_files();
 		unlink(commit_editmsg);
 		return 1;

wt-status.c

@@ -381,6 +381,8 @@ void wt_status_print(struct wt_status *s)
 	if (!s->commitable) {
 		if (s->amend)
 			fprintf(s->fp, "# No changes\n");
+		else if (s->nowarn)
+			; /* nothing */
 		else if (s->workdir_dirty)
 			printf("no changes added to commit (use \"git add\" and/or \"git commit -a\")\n");
 		else if (s->workdir_untracked)

wt-status.h

@@ -17,6 +17,7 @@ struct wt_status {
 	int verbose;
 	int amend;
 	int untracked;
+	int nowarn;
 	/* These are computed during processing of the individual sections */
 	int commitable;
 	int workdir_dirty;