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Enum works in python 3.10 breaks in 3.11 #104271
Description
Bug report
I have this (simplified) code
from enum import Enum, auto, unique
@unique
class TokenType(Enum):
# // Single-character tokens.
LEFT_PAREN = '('
# // Literals.
IDENTIFIER = auto()
STRING = auto()
NUMBER = auto()
# // Keywords.
AND = 'and'
WHILE = 'while'
EOF = auto()I tested this (I developed it) using python 3.10.8.
My friend ran it in 3.11.3 and it breaks like this:
File ".../3.11.3/lib/python3.11/enum.py", line 1561, in unique
raise ValueError('duplicate values found in %r: %s' %
ValueError: duplicate values found in <enum 'TokenType'>: NUMBER -> STRING, EOF -> STRING
We can work around the problem using a StrEnum and it's all fine. But I think this is a regression bug. I don't think my code should break like this because the standard library changed.
Also, fyi, StrEnum is new in 3.11 so I cannot just adjust my own code (which works well).
Activity
pythongh-104271: Fix auto() fallback in case of mixed type Enum
itamaro commentedon May 7, 2023
I confirmed the issue and proposed a fix in gh-104279
I think iterating the list of
last_valuesin gh-91457 in sorted order (instead of reversed sorted order) was an oversightin any case, @naringas, it seems that this use of
auto()will be deprecated in 3.13.you should be able to fix this in your code by overriding
_generate_next_value_to get your desired behavior in a way that works with older python versions.naringas commentedon May 7, 2023
I think the issue came from how I use
Enumwith mixed values; I have values either as strings, or 'auto'.Now that I've had to think about this, I realize expect unique (hence the decorator to error out if this fails) numerical values. I think this is a valid expectation for a unique Enum type with mixed values.
question: this issue gets closed if/when the PR gets merged?
sunmy2019 commentedon May 8, 2023
@ethanfurman
itamaro commentedon May 8, 2023
I think so, although it's up to the codeowner (Ethan) to decide if and how this should be fixed
itamaro commentedon May 20, 2023
@ethanfurman what do you think about this issue and proposed fix?
ethanfurman commentedon May 22, 2023
Apologies for the delay, I'll try to get to this this week. In general I agree with the proposed solution.
Merge branch '3.12' into pythongh-104271
Merge branch '3.12' into pythongh-104271
[3.12] gh-104271: Fix auto() fallback in case of mixed type Enum (GH-…
[3.12] pythongh-104271: Fix auto() fallback in case of mixed type Enum (
[3.11] gh-104271: Fix auto() fallback in case of mixed type Enum (GH-…