Merge pull request github#11244 from github/python/support-grouped-exceptions

Python: support grouped exceptions

Author: yoff

python/downgrades/47e552c4357a04c5735355fad818630daee4a5ac/old.dbscheme

@@ -0,0 +1,31 @@
+// First we need to wrap some database types
+class Stmt_ extends @py_stmt {
+  string toString() { result = "Stmt" }
+}
+
+class StmtList_ extends @py_stmt_list {
+  string toString() { result = "StmtList" }
+}
+
+/**
+ * New kinds have been inserted such that
+ * `@py_Exec` which used to have index 7 now has index 8.
+ * Entries with lower indices are unchanged.
+ */
+bindingset[new_index]
+int old_index(int new_index) {
+  not new_index = 7 and
+  if new_index < 7 then result = new_index else result + (8 - 7) = new_index
+}
+
+// The schema for py_stmts is:
+//
+// py_stmts(unique int id : @py_stmt,
+//   int kind: int ref,
+//   int parent : @py_stmt_list ref,
+//   int idx : int ref);
+from Stmt_ expr, int new_kind, StmtList_ parent, int idx, int old_kind
+where
+  py_stmts(expr, new_kind, parent, idx) and
+  old_kind = old_index(new_kind)
+select expr, old_kind, parent, idx