#!/usr/bin/env python3
"""Check PyTuple_Pack's C89 declaration and evaluation/refcount/error order."""
import re
import sys
from pathlib import Path

source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/tupleobject.c")
match = re.search(
    r"PyObject \*\nPyTuple_Pack\(Py_ssize_t n, \.\.\.\)\n\{(.*?)\n\}",
    source.read_text(),
    re.S,
)
assert match, "PyTuple_Pack definition not found"
body = match.group(1)
assert re.match(
    r"\s*Py_ssize_t i;\s*PyObject \*o;\s*PyObject \*\*items;"
    r"\s*va_list vargs;\s*PyTupleObject \*result;", body
), (
    "PyTuple_Pack: result must be declared without initializer before the empty "
    "tuple check; declaration after statement is not C89 compatible"
)
expected = """
    Py_ssize_t i;
    PyObject *o;
    PyObject **items;
    va_list vargs;
    PyTupleObject *result;

    if (n == 0) {
        return tuple_get_empty();
    }

    va_start(vargs, n);
    result = tuple_alloc(n);
    if (result == NULL) {
        va_end(vargs);
        return NULL;
    }
    items = result->ob_item;
    for (i = 0; i < n; i++) {
        o = va_arg(vargs, PyObject *);
        Py_INCREF(o);
        items[i] = o;
    }
    va_end(vargs);
    _PyObject_GC_TRACK(result);
    return (PyObject *)result;
"""
assert re.sub(r"\s+", "", body) == re.sub(r"\s+", "", expected), (
    "preserve empty-tuple return, va_start before single allocation, failure "
    "va_end/NULL return, item extraction/INCREF/store, final va_end, GC tracking, "
    "and return order"
)
print("PyTuple_Pack C89 declaration and evaluation/refcount/error order: PASS")