1 files changed, 28 insertions, 1 deletions

diff --git a/diff.c b/diff.c
index 3d37b56778..2d0b5e33f9 100644
--- a/diff.c
+++ b/diff.c
@@ -3532,13 +3532,40 @@ static int parse_diff_filter_opt(const char *optarg, struct diff_options *opt)
 	int i, optch;
 
 	prepare_filter_bits();
+
+	/*
+	 * If there is a negation e.g. 'd' in the input, and we haven't
+	 * initialized the filter field with another --diff-filter, start
+	 * from full set of bits, except for AON.
+	 */
+	if (!opt->filter) {
+		for (i = 0; (optch = optarg[i]) != '\0'; i++) {
+			if (optch < 'a' || 'z' < optch)
+				continue;
+			opt->filter = (1 << (ARRAY_SIZE(diff_status_letters) - 1)) - 1;
+			opt->filter &= ~filter_bit[DIFF_STATUS_FILTER_AON];
+			break;
+		}
+	}
+
 	for (i = 0; (optch = optarg[i]) != '\0'; i++) {
 		unsigned int bit;
+		int negate;
+
+		if ('a' <= optch && optch <= 'z') {
+			negate = 1;
+			optch = toupper(optch);
+		} else {
+			negate = 0;
+		}
 
 		bit = (0 <= optch && optch <= 'Z') ? filter_bit[optch] : 0;
 		if (!bit)
 			return optarg[i];
-		opt->filter |= bit;
+		if (negate)
+			opt->filter &= ~bit;
+		else
+			opt->filter |= bit;
 	}
 	return 0;
 }