commit 77f0ed7a42606d03ebfe48ab152caf0d796d6540
author Guido van Rossum <guido@python.org> Tue May 28 16:44:58 2019 -0700
committer GitHub <noreply@github.com> Tue May 28 16:44:58 2019 -0700
tree 1aab5bc929a5d50b3a4820ce7fdb2c05aafd6a73
parent 44bfff2ec220f2e0291150a776d4d77af7c821ef

bpo-37072: Fix crash in PyAST_FromNodeObject() when flags is NULL (#13634)

I'm confident that this fixes the reported crash. flags=NULL is treated as using the latest minor version.

https://bugs.python.org/issue37072

Python/ast.c

diff --git a/Python/ast.c b/Python/ast.c
index 7ffdf4a..12a45f9 100644
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -786,7 +786,7 @@
     /* borrowed reference */
     c.c_filename = filename;
     c.c_normalize = NULL;
-    c.c_feature_version = flags->cf_feature_version;
+    c.c_feature_version = flags ? flags->cf_feature_version : PY_MINOR_VERSION;
 
     if (TYPE(n) == encoding_decl)
         n = CHILD(n, 0);