Add upgrade and downgrade scripts for latest dbscheme

java/downgrades/dee651b58d1e5455ca2d07eca37775a21d772fcc/exprs.ql

@@ -0,0 +1,41 @@
+class Expr extends @expr { string toString() { result = "expr" } }
+class LocalVariableDeclExpr extends @localvariabledeclexpr, Expr { }
+class InstanceOfExpr extends @instanceofexpr, Expr { }
+class SimplePatternInstanceOfExpr extends InstanceOfExpr { SimplePatternInstanceOfExpr() { getNthChild(this, 2) instanceof LocalVariableDeclExpr } }
+class Type extends @type { string toString() { result = "type" } }
+class ExprParent extends @exprparent { string toString() { result = "exprparent" } }
+
+Expr getNthChild(ExprParent parent, int i) { exprs(result, _, _, parent, i) }
+
+// Where an InstanceOfExpr has a 2nd child that is a LocalVariableDeclExpr, that expression should becomes its 0th child and the existing 0th child should become its initialiser.
+// Any RecordPatternExpr should be replaced with an error expression, as it can't be represented in the downgraded dbscheme.
+
+// This reverts a reorganisation of the representation of "o instanceof String s", which used to be InstanceOfExpr -0-> LocalVariableDeclExpr --init-> o
+//                                                                                                                                               \-name-> s
+// It is now InstanceOfExpr --0-> o
+//                          \-2-> LocalVariableDeclExpr -name-> s
+//
+// Other children are unaffected.
+
+
+predicate hasNewParent(Expr e, ExprParent newParent, int newIndex) {
+
+  exists(SimplePatternInstanceOfExpr oldParent, int oldIndex |
+    e = getNthChild(oldParent, oldIndex) |
+    oldIndex = 0 and newParent = getNthChild(oldParent, 2) and newIndex = 0
+    or
+    oldIndex = 1 and newParent = oldParent and newIndex = oldIndex
+    or
+    oldIndex = 2 and newParent = oldParent and newIndex = 0
+  )
+  or
+  not exists(SimplePatternInstanceOfExpr oldParent | e = getNthChild(oldParent, _)) and
+  exprs(e, _, _, newParent, newIndex)
+
+}
+
+from Expr e, int oldKind, int newKind, Type typeid, ExprParent parent, int index
+where exprs(e, kind, typeid, _, _) and
+hasNewParent(e, parent, index) and
+(if oldKind = 89 /* record pattern */ then newKind = 74 /* error expression */ else oldKind = newKind)
+select e, newKind, typeid, parent, index

java/downgrades/dee651b58d1e5455ca2d07eca37775a21d772fcc/upgrade.properties

@@ -0,0 +1,5 @@
+description: Remove tables for canonical constructors and `case null, default`, and the expression kind for record patterns. Also revert the representation for instanceof with a binding pattern.
+compatibility: backwards
+exprs.rel: run exprs.qlo
+isCanonicalConstr.rel: delete
+isNullDefaultCase.rel: delete