Rule suggestion: no negated condition in if-else

[adamsol]

Summary

See this ESLint rule for a detailed description.

There's already something similar in Ruff: https://docs.astral.sh/ruff/rules/if-expr-with-twisted-arms/, but much more narrow in scope - works only for b if not a else a, not for b if not a else c and not for if statements.

[ntBre]

Thanks for the suggestion! I was surprised I couldn't find a previous request for this. I think the analogous clippy rule is if_not_else.

It would flag code like this:

def foo(condition):
    if not condition:
        return 1
    else:
        return 2

and suggest:

def foo(condition):
    if condition:
        return 2
    else:
        return 1

if I understand correctly.

We actually disable the clippy version in our own config, but that's not necessarily a reason to avoid having the rule for those who do like it 😆

ruff/Cargo.toml

Lines 272 to 279 in 29bf84e

	# This lint sometimes flags code whose `if` and `else`
	# bodies could be flipped when a `!` operator is removed.
	# While perhaps sometimes a good idea, it is also often
	# not a good idea due to other factors impacting
	# readability. For example, if flipping the bodies results
	# in the `if` being an order of magnitude bigger than the
	# `else`, then some might consider that harder to read.
	if_not_else = "allow"

[adamsol]

Actually, this was kinda already requested as WPS504 in #3845. Not the easiest to find, but feel free to close this issue if it's considered a duplicate.