#!/usr/bin/env python3
"""Check tuple_vectorcall's C89 nargs declaration and evaluation 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"static PyObject \*\ntuple_vectorcall\([^)]*\)\n\{(.*?)\n\}",
    source.read_text(),
    re.S,
)
assert match, "tuple_vectorcall definition not found"
body = match.group(1)
assert re.match(r"\s*Py_ssize_t nargs;", body), (
    "tuple_vectorcall: nargs must be declared in the initial declaration block "
    "before the keyword check for C89 compatibility"
)
expected = """
    Py_ssize_t nargs;
    if (!_PyArg_NoKwnames("tuple", kwnames)) {
        return NULL;
    }

    nargs = PyVectorcall_NARGS(nargsf);
    if (!_PyArg_CheckPositional("tuple", nargs, 0, 1)) {
        return NULL;
    }

    if (nargs) {
        return tuple_new_impl(_PyType_CAST(type), args[0]);
    }
    else {
        return tuple_get_empty();
    }
"""
assert re.sub(r"\s+", "", body) == re.sub(r"\s+", "", expected), (
    "preserve keyword rejection before the single nargs evaluation, positional "
    "validation, and nonempty/empty tuple return paths"
)
print("tuple_vectorcall C89 nargs declaration and evaluation order: PASS")