bpo-35766 follow-up: Add an error check to new_type_comment() (#11766)

If PyUnicode_DecodeUTF8() returns NULL, PyArena_AddPyObject() would crash.
Found by @msullivan for https://github.com/python/typed_ast/pull/93.

diff --git a/Python/ast.c b/Python/ast.c
index 76588c345f27ca23515acbd627deba4ca72951e2..5cef3fdadc9ae97e7a22906003ad5dc47cb150cb 100644 (file)
--- a/Python/ast.c
+++ b/Python/ast.c
@@ -702,6 +702,8 @@ static string
 new_type_comment(const char *s, struct compiling *c)
 {
     PyObject *res = PyUnicode_DecodeUTF8(s, strlen(s), NULL);
+    if (res == NULL)
+        return NULL;
     if (PyArena_AddPyObject(c->c_arena, res) < 0) {
         Py_DECREF(res);
         return NULL;