Should smart cast work in case of ```if (myNullable?.status in listOf(FOO, BAR)) { <myNullable no...

# announcements

[Jukka Siivonen]

Should smart cast work in case of

if (myNullable?.status in listOf(FOO, BAR)) { <myNullable not nullable here> }

[Joost Klitsie]

I guess not

[Joost Klitsie]

basically you check if something is in a list

[Joost Klitsie]

I do not think the compiler is smart enough to check the actual contents of the list

[Roukanken]

well, if the list is nullable, then definitely not

otherwise, maybe? I doubt it's working rn (as was mentioned, compiler is probs not smart enuf), but might be a suggestion for improvement

[Joost Klitsie]

well in runtime a list usually loses its type

[Joost Klitsie]

so not sure if that does anything

[Roukanken]

tho I feel like this is way too complicated for smartcast to be helpful - especially since you would need to think if the list is nullable or not (since they would have diff results), and imho it's better to just state it explicitly

@loosing type, isn't smartcast compile time feature? Loosing type in runtime shouldn't matter there

[dmitriy.novozhilov]

There are no smartcasts for such cases because compiler doesn't know semantics of contains method. And also there are no method to check that real list implementation that came to in doesn't break contains contract. Imagine that some custom List implementation has some dummy implementation like operator fun contains(element: Any): Boolean = true

[Jukka Siivonen]

Makes sense, thanks. I should have checked what "in" actually does..