weakref.WeakMethod equality behaves differently than weakref.ref (always False after garbage collection)

Bug report

Equality comparison of weakref.ref objects succeeds both before and after object deletion. Equality of two weakref.WeakMethod objects, however, is always false if the underlying object has been deleted:

>>> from weakref import WeakMethod, ref
>>> class T:
...   def x(self): ...
...
>>> t = T()
>>> r1 = ref(t)
>>> r2 = ref(t)
>>> m1 = WeakMethod(t.x)
>>> m2 = WeakMethod(t.x)
>>> r1 == r2
True
>>> m1 == m2
True
>>> del t
>>> r1 == r2
True
>>> m1 == m2
False

Is this a bug? or perhaps desirable behavior or a fundamental limitation of bound method weak references?

Your environment

• Python 3.11.0 | packaged by conda-forge | (main, Jan 15 2023, 05:44:48) [Clang 14.0.6 ] on darwin
• macos x86_64, v12.6.1 (21G217)

まず、提供されている Python REPL の例を実行し、ガベージコレクションの前後で weakref.ref と weakref.WeakMethod を比較します。次に、WeakMethod と ref の実装、および存在する場合はそれらの等価性に関するテストを調べます。削除後に意図されている等価性のセマンティクスを確立し、動作がバグであると確認された場合にカバレッジを追加するか、的を絞った修正を行えば完了です。