Swift: add database migration scripts

swift/downgrades/147e087e57e51b2eb41e75c9c97380d0e6c20ecb/downgrade.ql

@@ -0,0 +1,36 @@
+class Element extends @element {
+  string toString() { none() }
+}
+
+newtype TAddedUnspecifiedElement =
+  TNonExplicitClosureExprClosureBody(Element list, Element body) {
+    capture_list_exprs(list, body) and not explicit_closure_exprs(body)
+  }
+
+module Fresh = QlBuiltins::NewEntity<TAddedUnspecifiedElement>;
+
+class TNewElement = @element or Fresh::EntityId;
+
+class NewElement extends TNewElement {
+  string toString() { none() }
+}
+
+query predicate new_unspecified_elements(NewElement u, string property, string error) {
+  unspecified_elements(u, property, error)
+  or
+  u = Fresh::map(TNonExplicitClosureExprClosureBody(_, _)) and
+  property = "closure_body" and
+  error = "while downgrading: closure_body not an @explicit_closure_expr"
+}
+
+query predicate new_unspecified_element_parents(NewElement u, Element parent) {
+  unspecified_element_parents(u, parent)
+  or
+  u = Fresh::map(TNonExplicitClosureExprClosureBody(parent, _))
+}
+
+query predicate new_capture_list_exprs(Element list, NewElement body) {
+  capture_list_exprs(list, body) and explicit_closure_exprs(body)
+  or
+  body = Fresh::map(TNonExplicitClosureExprClosureBody(list, _))
+}

swift/downgrades/147e087e57e51b2eb41e75c9c97380d0e6c20ecb/upgrade.properties

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+description: Revert making closure_body have type @abstract_closure_expr
+compatibility: backwards
+unspecified_elements.rel: run downgrade.qlo new_unspecified_elements
+unspecified_element_parents.rel: run downgrade.qlo new_unspecified_element_parents
+capture_list_exprs.rel: run downgrade.qlo new_capture_list_exprs

swift/ql/lib/upgrades/44e36e15e90bc1535964d9b86b3cd06a8b0d26e3/upgrade.properties

@@ -0,0 +1,2 @@
+description: New entities added
+compatibility: full