#!/usr/bin/env python3
"""Keep only non-GC subtype_dealloc's type_needs_decref C89-safe."""
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 void\nsubtype_dealloc\(PyObject \*self\)\n\{(.*?)\n\}",
    source,
    re.S,
)
assert match, "subtype_dealloc definition missing"
body = match.group(1)
start = body.index("    if (!_PyType_IS_GC(type)) {")
end = body.index("    /* We get here only if the type has GC */", start)
branch = re.sub(r"/\*.*?\*/|//[^\n]*", "", body[start:end], flags=re.S)
assert re.match(r"\s*if \(!_PyType_IS_GC\(type\)\) \{\s*int type_needs_decref;", branch), (
    "non-GC subtype_dealloc: type_needs_decref must be declared at block entry (C89)"
)
expected = """
    if (!_PyType_IS_GC(type)) {
        int type_needs_decref;
        if (type->tp_finalize) {
            if (PyObject_CallFinalizerFromDealloc(self) < 0)
                return;
        }
        if (type->tp_del) {
            type->tp_del(self);
            if (Py_REFCNT(self) > 0) {
                return;
            }
        }
        base = type;
        while ((basedealloc = base->tp_dealloc) == subtype_dealloc) {
            base = base->tp_base;
            assert(base);
        }
        type = Py_TYPE(self);
        type_needs_decref = (type->tp_flags & Py_TPFLAGS_HEAPTYPE
                                 && !(base->tp_flags & Py_TPFLAGS_HEAPTYPE));
        assert((type->tp_flags & Py_TPFLAGS_MANAGED_DICT) == 0);
        assert(basedealloc);
        basedealloc(self);
        if (type_needs_decref) {
            Py_DECREF(type);
        }
        return;
    }
"""
assert branch.split() == expected.split(), (
    "non-GC subtype_dealloc: preserve assignment evaluation point and all control flow"
)
print("non-GC subtype_dealloc type_needs_decref C89 declaration and unchanged control flow: PASS")