In various places within the generated Python/Python-ast.c, error handling generates a repr() and raises exceptions accordingly.

Currently in py3k the generated code uses PyBytes_AS_STRING() on the repr.  My understanding is that repr() should be a PyUnicodeObject, not a PyBytesObject.  This seems to be unchanged from r63682, which was a mass-change of PyString to PyBytes from 2 years ago.

This leads to a python crashing with an assertion failure:
test_compile_ast (__main__.TestSpecifics) ... python: Python/Python-ast.c:5835: obj2ast_expr: Assertion `((((((PyObject*)(tmp))->ob_type))->tp_flags & ((1L<<27))) != 0)' failed.

when invoking compile() on certain (malformed) trees of ast objects.