#!/usr/bin/env python3
"""Keep type_vectorcall's nargs declaration separate and evaluation first."""
import re
import sys
from pathlib import Path

source = Path(sys.argv[1] if len(sys.argv) > 1 else "cpython/Objects/typeobject.c").read_text()
match = re.search(
    r"\nstatic PyObject \*\ntype_vectorcall\(PyObject \*metatype, PyObject \*const \*args,\n"
    r"\s*size_t nargsf, PyObject \*kwnames\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "type_vectorcall definition missing"
body = match.group(1)
assert re.match(r"\s*Py_ssize_t nargs;\s*PyThreadState \*tstate;\s*nargs = PyVectorcall_NARGS\(nargsf\);", body), (
    "type_vectorcall: declare nargs at block entry and assign at the original first statement position"
)
assert len(re.findall(r"\bPy_ssize_t\s+nargs\b", body)) == 1, (
    "type_vectorcall: declare nargs exactly once"
)
assert re.findall(r"\bnargs\s*=(?!=)\s*([^;]+);", body) == ["PyVectorcall_NARGS(nargsf)"], (
    "type_vectorcall: evaluate nargs exactly once"
)
expected = """
    Py_ssize_t nargs;
    PyThreadState *tstate;

    nargs = PyVectorcall_NARGS(nargsf);
    if (nargs == 1 && metatype == (PyObject *)&PyType_Type){
        if (!_PyArg_NoKwnames("type", kwnames)) {
            return NULL;
        }
        return Py_NewRef(Py_TYPE(args[0]));
    }
    /* In other (much less common) cases, fall back to
       more flexible calling conventions. */
    tstate = _PyThreadState_GET();
    return _PyObject_MakeTpCall(tstate, metatype, args, nargs, kwnames);
"""
assert body.split() == expected.split(), (
    "type_vectorcall: preserve evaluation order, fast path, and fallback unchanged"
)
print("type_vectorcall nargs declaration and unchanged evaluation/control flow: PASS")