add a AST validator (closes #12575)
diff --git a/Python/bltinmodule.c b/Python/bltinmodule.c
index 152210b..94b2798 100644
--- a/Python/bltinmodule.c
+++ b/Python/bltinmodule.c
@@ -604,6 +604,10 @@
                 PyArena_Free(arena);
                 goto error;
             }
+            if (!PyAST_Validate(mod)) {
+                PyArena_Free(arena);
+                goto error;
+            }
             result = (PyObject*)PyAST_CompileEx(mod, filename,
                                                 &cf, optimize, arena);
             PyArena_Free(arena);