Change in semantics and much worse performance for enum members. #93910
Description
Given the enum:
class Colours(Enum):
RED = 1In Python 3.9 and 3.10:
>>> Colours.__dict__["RED"] is Colours.RED
True
>>> Colours.RED.RED
<Colours.RED: 1>In Python 3.11:
>>> Colours.__dict__["RED"] is Colours.RED
False
>>> Colours.RED.RED
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "/home/mark/repos/cpython/Lib/enum.py", line 198, in __get__
raise AttributeError(
^^^^^^^^^^^^^^^^^^^^^
AttributeError: <enum 'Colours'> member has no attribute 'RED'While these might seem like minor semantic changes, there is also a large performance impact.
Lookup of Colours.RED is simple and efficient in 3.10, but involves a lot of indirection and dispatching through the enum.property class in 3.11.
The performance impact is likely to get worse in 3.12, as we optimize more kinds of attributes.
Introduced in c314e60, I believe.