C#: Downgrade script should convert list- and slice pattern to unknown expression kind.

csharp/downgrades/83aca6b3e4fa38dd2b97b9b51dfc199a2ba9c7f2/expressions.ql

@@ -0,0 +1,13 @@
+class Expression extends @expr {
+  string toString() { none() }
+}
+
+class TypeOrRef extends @type_or_ref {
+  string toString() { none() }
+}
+
+from Expression e, int k, int kind, TypeOrRef t
+where
+  expressions(e, k, t) and
+  if k = [131, 132] then kind = 106 else kind = k
+select e, kind, t

csharp/downgrades/83aca6b3e4fa38dd2b97b9b51dfc199a2ba9c7f2/upgrade.properties

@@ -1,2 +1,3 @@
 description: Remove list- and slice pattern expression kinds.
 compatibility: backwards
+expressions.rel: run expressions.qlo