#!/usr/bin/env python3
"""Check only mro_implementation's to_merge population loop index."""
import re
from pathlib import Path

source = Path("cpython/Objects/typeobject.c").read_text()
match = re.search(
    r"\nstatic PyObject \*\nmro_implementation\(PyTypeObject \*type\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "mro_implementation definition missing"
body = re.sub(r"/\*.*?\*/", "", match.group(1), flags=re.S)
assert re.match(
    r"\s*PyObject \*bases;\s*Py_ssize_t n;\s*Py_ssize_t i;"
    r"\s*PyObject \*\*to_merge;\s*PyObject \*result;\s*if\b", body
), "mro_implementation: reuse i from the opening declaration block"
population = body.split("to_merge = PyMem_New(PyObject *, n + 1);", 1)[1].split(
    "result = PyList_New(1);", 1
)[0]
assert not re.search(r"\bfor\s*\(\s*Py_ssize_t\s+i\b", population), (
    "mro_implementation: to_merge population loop must reuse function-scope i for C89"
)
expected = """
    if (to_merge == NULL) {
        PyErr_NoMemory();
        return NULL;
    }
    for (i = 0; i < n; i++) {
        PyTypeObject *base = _PyType_CAST(PyTuple_GET_ITEM(bases, i));
        to_merge[i] = base->tp_mro;
    }
    to_merge[n] = bases;
"""
assert population.split() == expected.split(), (
    "mro_implementation: preserve allocation error handling, loop initialization, "
    "bounds, increment, base MRO writes, and final bases entry"
)
print("mro_implementation to_merge loop index C89 declaration and unchanged semantics: PASS")