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mypy cannot determine Enum members from static or Final values

Open straz opened this issue 9 months ago • 0 comments

Bug Report To Reproduce

Here are 3 variations on creating IntEnum or StrEnum using functional API syntax.

testing1.py: (Success)

UpperSeat = IntEnum("UpperSeat", {"Seat1": 1, "Seat2": 2, "Seat3": 3})

testing2.py: (Error)

UPPER_CODES: Final[dict[str, int]] = {"Seat1": 1, "Seat2": 2, "Seat3": 3}
UpperSeat = IntEnum("UpperSeat", UPPER_CODES)

testing3.py: (Error)

UPPER_CODES: Final[dict[str, int]] = {f"Seat{code}": code for code in range(1, 3)}
UpperSeat = IntEnum("UpperSeat", UPPER_CODES)

Expected Behavior

All three of these produce valid Python code, but only one of these passes mypy type analysis. I would argue that UPPER_CODES in both testing2 and testing3 are static. In testing2.py, UPPER_CODES is a static constant. In testing3.py, UPPER_CODES is provably static. In both testing2 and testing3, Final values are used, so mypy should not be throwing this error.

Actual Behavior

testing1.py - Uses static values in-line: mypy yields Success testing2.py and testing3.py: mypy yields Error:

main.py:8: error: Second argument of IntEnum() must be string, tuple, list or dict literal for mypy to determine Enum members  [misc]
main.py:9: error: Second argument of StrEnum() must be string, tuple, list or dict literal for mypy to determine Enum members  [misc]
Found 2 errors in 1 file (checked 1 source file)

Your Environment

  • Mypy version used: 1.10.0
  • Mypy command-line flags: n/a
  • Mypy configuration options from mypy.ini (and other config files): n/a
  • Python version used: python 3.12

straz avatar Apr 29 '24 02:04 straz