"""Check type_set_bases declares old_bases in its opening declaration block."""
from pathlib import Path
import re
import sys

source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/typeobject.c").read_text()
match = re.search(
    r"\nstatic int\ntype_set_bases\(PyTypeObject \*type, PyObject \*new_bases, void \*context\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "type_set_bases definition missing"
body = match.group(1)
assert re.search(
    r"\A\n\s*Py_ssize_t n;\n\s*Py_ssize_t i;\n\s*PyTypeObject \*new_base;\n\s*PyObject \*old_bases;",
    body,
), "type_set_bases: old_bases must be declared with the opening locals"
assert body.count("PyObject *old_bases;") == 1, "old_bases declaration must occur once"
assert re.search(r"\n\s*old_bases = type->tp_bases;\n\s*assert\(old_bases != NULL\);", body), (
    "type_set_bases: preserve old_bases assignment and assertion order"
)