#!/usr/bin/env python3
"""Check mro_check's C89 base declaration and validation/cast order."""
import re
from pathlib import Path

source = Path("cpython/Objects/typeobject.c").read_text()
match = re.search(
    r"\nstatic int\nmro_check\(PyTypeObject \*type, PyObject \*mro\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "mro_check definition missing"
body = match.group(1)
loop = body[body.index("    for (i = 0; i < n; i++) {"):]
opening = loop.split("if (!PyType_Check(obj))", 1)[0]
assert re.search(r"\bPyTypeObject \*base;", opening), (
    "mro_check: PyTypeObject *base; must precede loop statements (C89)"
)
expected = """
    for (i = 0; i < n; i++) {
        PyObject *obj = PyTuple_GET_ITEM(mro, i);
        PyTypeObject *base;
        if (!PyType_Check(obj)) {
            PyErr_Format(
                PyExc_TypeError,
                "mro() returned a non-class ('%.500s')",
                Py_TYPE(obj)->tp_name);
            return -1;
        }
        base = (PyTypeObject*)obj;

        if (!PyType_IsSubtype(solid, solid_base(base))) {
            PyErr_Format(
                PyExc_TypeError,
                "mro() returned base with unsuitable layout ('%.500s')",
                base->tp_name);
            return -1;
        }
    }

    return 0;
"""
assert loop.split() == expected.split(), (
    "preserve item lookup, non-class rejection before cast, layout validation, and returns"
)
print("mro_check C89 base declaration and unchanged validation/cast order: PASS")