1 files changed, 15 insertions, 2 deletions
diff --git a/git-diff.sh b/git-diff.sh
index e45f50ec22..b62e58341c 100755
--- a/git-diff.sh
+++ b/git-diff.sh
@@ -7,8 +7,6 @@ rev=$(git-rev-parse --revs-only --no-flags --sq "$@") || exit
 flags=$(git-rev-parse --no-revs --flags --sq "$@")
 files=$(git-rev-parse --no-revs --no-flags --sq "$@")
 
-: ${flags:="'-M' '-p'"}
-
 die () {
     echo >&2 "$*"
     exit 1
@@ -25,6 +23,21 @@ case "$rev" in
 	esac
 esac
 
+# If we do not have --name-status, --name-only nor -r, default to -p.
+# If we do not have -B nor -C, default to -M.
+case " $flags " in
+*" '--name-status' "* | *" '--name-only' "* | *" '-r' "* )
+	;;
+*)
+	flags="$flags'-p' " ;;
+esac
+case " $flags " in
+*" '-"[BCM]* | *" '--find-copies-harder' "*)
+	;; # something like -M50.
+*)
+	flags="$flags'-M' " ;;
+esac
+
 case "$rev" in
 ?*' '?*' '?*)
 	echo >&2 "I don't understand"