#!/usr/bin/env python3
"""Keep _PyType_GetSubclasses's subclasses declaration C89-safe."""
import re
from pathlib import Path

source = Path("cpython/Objects/typeobject.c").read_text()
match = re.search(
    r"\nPyObject\*\n_PyType_GetSubclasses\(PyTypeObject \*self\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "_PyType_GetSubclasses definition missing"
body = re.sub(r"/\*.*?\*/|//[^\n]*", "", match.group(1), flags=re.S)
assert re.match(r"\s*PyObject \*subclasses;", body), (
    "_PyType_GetSubclasses: subclasses must be declared at function entry (C89)"
)
assert len(re.findall(r"\bPyObject\s*\*\s*subclasses\b", body)) == 1, (
    "_PyType_GetSubclasses: declare subclasses exactly once"
)
assert re.match(
    r"\s*PyObject \*subclasses;\s*"
    r"(?:Py_ssize_t i;\s*)?"
    r"PyObject \*list = PyList_New\(0\);\s*"
    r"PyObject \*ref;\s*"
    r"PyObject \*obj;\s*"
    r"if \(list == NULL\) \{\s*return NULL;\s*\}\s*"
    r"subclasses = self->tp_subclasses;\s*"
    r"if \(subclasses == NULL\) \{\s*return list;\s*\}\s*"
    r"assert\(PyDict_CheckExact\(subclasses\)\);",
    body,
), "_PyType_GetSubclasses: preserve allocation, guard, and tp_subclasses read timing"
assert body.count("self->tp_subclasses") == 1, (
    "_PyType_GetSubclasses: preserve the single tp_subclasses read"
)
print("_PyType_GetSubclasses subclasses C89 declaration and read timing: PASS")