Teach "diff --check" about new blank lines at end

When a patch adds new blank lines at the end, "git apply --whitespace"
warns.  This teaches "diff --check" to do the same.

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

1 files changed, 15 insertions, 0 deletions

diff --git a/ws.c b/ws.c
index 24d3e3de07..7a7ff130a3 100644
--- a/ws.c
+++ b/ws.c
@@ -225,6 +225,21 @@ unsigned ws_check(const char *line, int len, unsigned ws_rule)
 	return ws_check_emit_1(line, len, ws_rule, NULL, NULL, NULL, NULL);
 }
 
+int ws_blank_line(const char *line, int len, unsigned ws_rule)
+{
+	/*
+	 * We _might_ want to treat CR differently from other
+	 * whitespace characters when ws_rule has WS_CR_AT_EOL, but
+	 * for now we just use this stupid definition.
+	 */
+	while (len-- > 0) {
+		if (!isspace(*line))
+			return 0;
+		line++;
+	}
+	return 1;
+}
+
 /* Copy the line to the buffer while fixing whitespaces */
 int ws_fix_copy(char *dst, const char *src, int len, unsigned ws_rule, int *error_count)
 {