in membership test short-circuits evaluation for list literals

[charles-cooper]

Version Information

• vyper Version (output of vyper --version): v0.4.0

What's your issue about?

as an optimization, vyper currently expands array membership like x in [a, b, c] to x == a or x == b or x == c. however, this short circuits, which can lead to not evaluating side effects. for example,

def increment_counter() -> uint256:
    self.count += 1
    return self.count

def foo() -> uint256:
    if 1 in [self.increment_counter(), self.increment_counter()]:
        return self.counter  # returns 1
    return 0

How can it be fixed?

Fill this in if you know how to fix it.

[charles-cooper]

this was reported by @montyly and @0xalpharush