[Bug]: weakref.ref() and weakref.proxy() with a callback accept objects that do not support weak references #1256

Describe the bug

weakref.ref(obj, callback) and weakref.proxy(obj, callback) succeed for dict, list, int, str, None and other types without weak reference support. Without a callback, or with None, both raise TypeError as CPython does.

Operating system

macOS

CPU architecture

ARM64

GraalPy version

master a3009f9 (Python 3.13.14); also reproduced on 25.0.2 (Python 3.12.8) and 25.4.4.1.1 (Python 3.13.14)

JDK version

No response

Context configuration

No response

Steps to reproduce

import weakref

def callback(ref):
    pass

for obj in ({}, None):
    try:
        print(type(weakref.proxy(obj, callback)).__name__)
    except TypeError as e:
        print(type(e).__name__, e)

GraalPy master a3009f9:

ProxyType
ProxyType

Expected behavior

CPython 3.13.14 (same on 3.12.13):

TypeError cannot create weak reference to 'dict' object
TypeError cannot create weak reference to 'NoneType' object

Stack trace

Additional context

The proxy of None raises ReferenceError: weakly-referenced object no longer exists on first use, because a referent of None reads as a dead reference.

Root Cause

ReferenceTypeNode.refType rejects a builtin class whose getWeaklistoffset() is 0 (ReferenceTypeBuiltins.java#L140-L148), but it only matches a None callback. refTypeWithCallback, which weakref.proxy() reaches through NewProxyTypeNode, creates the reference without that check (#L160-L167). CPython's PyWeakref_NewRef and PyWeakref_NewProxy both go through get_or_create_weakref, which checks _PyType_SUPPORTS_WEAKREFS before it looks at the callback (weakrefobject.c#L405-L415).

Fix Suggestion

Add the same getWeaklistoffset() == 0 check to refTypeWithCallback. getBuiltinTypeWeaklistoffset (WeakRefModuleBuiltins.java#L93-L137) needs entries for collections.deque, array.array, mmap.mmap, _contextvars.Context, _queue.SimpleQueue, _struct.Struct and the typing.TypeVar family first, since these support weak references in CPython and today work on GraalPy only when a callback is given.