[display] add test

closes #6740

tests/display/src/cases/Issue6740.hx

@@ -0,0 +1,26 @@
+package cases;
+
+class Issue6740 extends DisplayTestCase {
+	/**
+	class A {
+		function new(v:Array<String>) {
+		}
+	}
+
+	class Main extends A {
+
+		function new(v) {
+			super(v);
+			v.{-1-}
+		}
+
+		static function main() {
+			new Main();
+		}
+
+	}
+	**/
+	function test() {
+		eq(true, hasField(fields(pos(1)), "concat", "a : Array<String> -> Array<String>"));
+	}
+}