#!/usr/bin/env python3
"""Check structseq_traverse's C89 declarations and visit/size lookup order."""
import re
import sys
from pathlib import Path

source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/structseq.c")
match = re.search(
    r"static int\nstructseq_traverse\(PyStructSequence \*obj, visitproc visit, void \*arg\)"
    r"\n\{(.*?)\n\}",
    source.read_text(),
    re.S,
)
assert match, "structseq_traverse definition not found"
body = match.group(1)
assert re.match(r"\s*Py_ssize_t i, size;", body), (
    "structseq_traverse: i and size must be declared before the heap-type check; "
    "declaration after statement is not C89 compatible"
)
expected = """
    Py_ssize_t i, size;
    if (Py_TYPE(obj)->tp_flags & Py_TPFLAGS_HEAPTYPE) {
        Py_VISIT(Py_TYPE(obj));
    }
    size = REAL_SIZE(obj);
    for (i = 0; i < size; ++i) {
        Py_VISIT(obj->ob_item[i]);
    }
    return 0;
"""
assert re.sub(r"\s+", "", body) == re.sub(r"\s+", "", expected), (
    "preserve heap-type visit and its early return before the single real-size "
    "lookup, item visit order, loop initialization, and return behavior"
)
print("structseq_traverse C89 declarations and visit/size lookup order: PASS")