Prepare for Python 3.13: replace classmethod(AutoConfig(...)) with a new dedicated AutoConfigClassMethod descriptor.

fiddle/_src/experimental/auto_config.py

@@ -61,6 +61,25 @@
 _GenericCallable = TypeVar('_GenericCallable', bound=Callable[..., Any])
 
 
+@dataclasses.dataclass(frozen=True)
+class AutoConfigClassMethod:
+  """A wrapper for auto_config'd class methods."""
+
+  func: Callable[..., Any]
+  always_inline: bool
+
+  def __get__(self, obj, objtype=None):
+    return AutoConfig(
+        func=types.MethodType(self.func, objtype),
+        buildable_func=types.MethodType(self.func, objtype),
+        always_inline=self.always_inline,
+    )
+
+  @property
+  def __wrapped__(self):
+    return self.func
+
+
 @dataclasses.dataclass(frozen=True)
 class AutoConfig:
   """A function wrapper for auto_config'd functions.

fiddle/_src/tagging.py

@@ -107,9 +107,9 @@ def new(cls, default: Any = NO_VALUE) -> Any:
     return TaggedValue(tags=(cls,), default=default)
 
   if not typing.TYPE_CHECKING:
-    new = classmethod(
-        auto_config.AutoConfig(
-            func=new.__func__, buildable_func=new.__func__, always_inline=True))
+    new = auto_config.AutoConfigClassMethod(
+        func=new.__func__, always_inline=True
+    )
 
 
 T = TypeVar('T')