C++: Support attribute arguments that are expressions

Author: jketema

cpp/downgrades/d8149ca90e695fe26f9a0c5a7fa0edd6d4ea3f5d/attribute_args.ql

@@ -0,0 +1,17 @@
+class AttributeArg extends @attribute_arg {
+  string toString() { none() }
+}
+
+class Attribute extends @attribute {
+  string toString() { none() }
+}
+
+class Location extends @location_default {
+  string toString() { none() }
+}
+
+from AttributeArg arg, int kind, int kind_new, Attribute attr, int index, Location location
+where
+  attribute_args(arg, kind, attr, index, location) and
+  if arg instanceof @attribute_arg_expr then kind_new = 0 else kind_new = kind
+select arg, kind_new, attr, index, location