MyPy gives error “Missing return statement” even when all cases are tested #4223
Description
I haven't received any answers to the following StackOverflow post, so I thought I'd also post it here. I'm not sure if it's an actual bug or if it's just considered good practice to always have something like else: raise Exception at the end of if / elif block.
I am getting a MyPy error "Missing return statement", even when I check for all possible cases inside a function.
For example, in the following code, MyPy is still giving me an error "9: error: Missing return statement", even though color can only be Color.RED, Color.GREEN, or Color.BLUE, and I test all those cases!
class Color(enum.IntEnum):
RED: int = 1
GREEN: int = 2
BLUE: int = 3
def test_enum(color: Color) -> str:
if color == Color.RED:
return "red"
elif color == Color.GREEN:
return "green"
elif color == Color.BLUE:
return "blue"