diff --check: minor fixups

There is no reason --exit-code and --check-diff must be mutually
exclusive, so assign different bits to different results and allow them
to be returned from the command.  Introduce diff_result_code() to factor
out the common code to decide final status code based on diffopt
settings and use it everywhere.

Update tests to match the above fix.

Turning pager off when "diff --check" is used is a regression.

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

1 files changed, 2 insertions, 4 deletions

diff --git a/builtin-diff-tree.c b/builtin-diff-tree.c
index 9ab90cb4c5..ebc50efbd2 100644
--- a/builtin-diff-tree.c
+++ b/builtin-diff-tree.c
@@ -132,8 +132,6 @@ int cmd_diff_tree(int argc, const char **argv, const char *prefix)
 				diff_tree_stdin(line);
 		}
 	}
-	if (opt->diffopt.output_format & DIFF_FORMAT_CHECKDIFF)
-		return DIFF_OPT_TST(&opt->diffopt, CHECK_FAILED) != 0;
-	return DIFF_OPT_TST(&opt->diffopt, EXIT_WITH_STATUS)
-		&& DIFF_OPT_TST(&opt->diffopt, HAS_CHANGES);
+
+	return diff_result_code(&opt->diffopt, 0);
 }