impossible-comparison / R1739

Message emitted:

This comparison always evaluates to False

Description:

Emitted when a boolean condition contains a chain of comparisons that is logically contradictory and can never be true (e.g. ``a > b and b > a``).

Problematic code:

def has_more_apples_than_bananas(apples, bananas):
    # The two checks contradict each other: if there are more apples than
    # bananas, there cannot also be more bananas than apples.
    return apples > bananas and bananas > apples  # [impossible-comparison]

Correct code:

def has_more_apples_than_bananas(apples, bananas):
    return apples > bananas

Created by the refactoring checker.