Swift: Add upgrade and downgrade scripts

Author: jketema

swift/downgrades/4dd3d5ca8a89952485b3e3b2141b6bb8c22cf945/macro_role_conformances.ql

@@ -0,0 +1,21 @@
+class MacroRole extends @macro_role {
+  string toString() { none() }
+}
+
+class ExprOrNone extends @expr_or_none {
+  string toString() { none() }
+}
+
+class TypeExpr extends @type_expr {
+  string toString() { none() }
+}
+
+class UnspecifiedElement extends @unspecified_element {
+  string toString() { none() }
+}
+
+from MacroRole role, int index, ExprOrNone conformance
+where
+  macro_role_conformances(role, index, conformance) and
+  (conformance instanceof TypeExpr or conformance instanceof UnspecifiedElement)
+select role, index, conformance