#!/usr/bin/env python3
"""Keep _PyType_GetSubclasses's index in opening C89 locals."""
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;\s*Py_ssize_t i;\s*"
    r"PyObject \*list = PyList_New\(0\);",
    body,
), "_PyType_GetSubclasses: i must be declared in the opening declaration block (C89)"
assert len(re.findall(r"\bPy_ssize_t\s+i\b", body)) == 1, (
    "_PyType_GetSubclasses: declare i exactly once"
)
expected = """
    PyObject *subclasses;
    Py_ssize_t i;
    PyObject *list = PyList_New(0);
    PyObject *ref;
    PyObject *obj;
    if (list == NULL) {
        return NULL;
    }

    subclasses = self->tp_subclasses;  
    if (subclasses == NULL) {
        return list;
    }
    assert(PyDict_CheckExact(subclasses));
    
    

    i = 0;
    while (PyDict_Next(subclasses, &i, NULL, &ref)) {
        assert(PyWeakref_CheckRef(ref));
        obj = PyWeakref_GET_OBJECT(ref);
        if (obj == Py_None) {
            continue;
        }
        assert(PyType_Check(obj));

        if (PyList_Append(list, obj) < 0) {
            Py_DECREF(list);
            return NULL;
        }
    }
    return list;
"""
assert body.split() == expected.split(), (
    "_PyType_GetSubclasses: preserve index initialization timing, guards, loop, "
    "and ref/obj uses"
)
print("_PyType_GetSubclasses C89 index declaration and preserved initialization timing: PASS")