add test (see #2396)

tests/unit/issues/Issue2396.hx

@@ -0,0 +1,57 @@
+package unit.issues;
+
+private class AA
+{
+    public var x:Float;
+    public var y:Float;
+
+    inline public function new(x:Float, y:Float)
+    {
+        this.x = x;
+        this.y = y;
+    }
+}
+
+private abstract BB(AA)
+{
+    public var x(get, set):Float;
+    public var y(get, set):Float;
+
+
+    inline public function get_x():Float return this.x;
+    inline public function get_y():Float return this.y;
+
+    inline public function set_x(v:Float):Float return this.x = v;
+    inline public function set_y(v:Float):Float return this.y = v;
+
+    public inline function new(x:Float = 0, y:Float = 0)
+    {
+        this = new AA(x, y);
+    }
+
+    @:commutative @:op(A*B) inline public static function opMulSF(a:BB, s:Float):BB
+    {
+        return new BB(a.x * s, a.y * s);
+    }
+}
+
+
+class Issue2396 extends Test {
+	function test() {
+        var a = new BB(10, 20);
+
+        var t1 = 1.0;
+        var t2 = 2.0;
+
+        // !!! fails here
+        var fail = a * (t1 + t2);
+		feq(30, fail.x);
+		feq(60, fail.y);
+
+        // ok here
+        var cacheSum = (t1 + t2);
+        var ok = a * cacheSum;
+		feq(30, ok.x);
+		feq(60, ok.y);
+	}
+}