Rust: Add DB downgrade script

Author: hvitved

rust/downgrades/90861289dd4c4d9fc029ed0fc249c1e11c5aab01/downgrade.ql

@@ -0,0 +1,78 @@
+class Element extends @element {
+  string toString() { none() }
+}
+
+newtype TAddedElement =
+  TMacroBlockExpr(Element block) {
+    block_exprs(block) and macro_call_macro_call_expansions(_, block)
+  }
+
+module Fresh = QlBuiltins::NewEntity<TAddedElement>;
+
+class TNewElement = @element or Fresh::EntityId;
+
+class NewElement extends TNewElement {
+  string toString() { none() }
+}
+
+query predicate new_macro_block_exprs(NewElement id) { id = Fresh::map(TMacroBlockExpr(_)) }
+
+query predicate new_macro_block_expr_statements(NewElement id, int index, Element stmt) {
+  exists(Element block, Element list |
+    id = Fresh::map(TMacroBlockExpr(block)) and
+    block_expr_stmt_lists(block, list) and
+    stmt_list_statements(list, index, stmt)
+  )
+}
+
+query predicate new_macro_block_expr_tail_exprs(NewElement id, Element expr) {
+  exists(Element block, Element list |
+    id = Fresh::map(TMacroBlockExpr(block)) and
+    block_expr_stmt_lists(block, list) and
+    stmt_list_tail_exprs(list, expr)
+  )
+}
+
+query predicate new_block_exprs(Element id) {
+  block_exprs(id) and
+  not macro_call_macro_call_expansions(_, id)
+}
+
+query predicate new_stmt_lists(Element id) {
+  stmt_lists(id) and
+  not exists(Element block |
+    macro_call_macro_call_expansions(_, block) and
+    block_expr_stmt_lists(block, id)
+  )
+}
+
+query predicate new_block_expr_stmt_lists(Element id, Element list) {
+  block_expr_stmt_lists(id, list) and
+  not macro_call_macro_call_expansions(_, id)
+}
+
+query predicate new_stmt_list_statements(Element id, int index, Element stmt) {
+  stmt_list_statements(id, index, stmt) and
+  not exists(Element block |
+    macro_call_macro_call_expansions(_, block) and
+    block_expr_stmt_lists(block, id)
+  )
+}
+
+query predicate new_stmt_list_tail_exprs(Element id, Element expr) {
+  stmt_list_tail_exprs(id, expr) and
+  not exists(Element block |
+    macro_call_macro_call_expansions(_, block) and
+    block_expr_stmt_lists(block, id)
+  )
+}
+
+query predicate new_macro_call_macro_call_expansions(NewElement id, NewElement expansion) {
+  macro_call_macro_call_expansions(id, expansion) and
+  not block_exprs(expansion)
+  or
+  exists(Element block |
+    expansion = Fresh::map(TMacroBlockExpr(block)) and
+    macro_call_macro_call_expansions(id, block)
+  )
+}