Shouldn't this show some unchecked cast warning?

# announcements

[carlos cdmp]

Shouldn't this show some unchecked cast warning?

[Alowaniak]

Unchecked cast warnings are for generic casts (where it won't go wrong when casting but when accessing the type)
(Badly worded but something like that)

[robstoll]

Why do you think it should be an unchecked cast? B is a subtype of A so a could be a B and this check will be carried out at runtime

[carlos cdmp]

I mean a warning showing that this cast can have a ClassCastException because its not checked that a is B type, it can be A or C also

[Alowaniak]

Every cast can have a ClassCastException
If the compiler could guarantee the type then it wouldn't need the cast. So a cast is in theory always "dangerous"

[carlos cdmp]

Well you can check it before, like if(a is B){ a.sayHi()} right?

[robstoll]

I don't know if there is an inspection you can activate in Intellij warning you about unsafe casts

[robstoll]

I couldn't find one

[Alowaniak]

Maybe its a rule in some linters
I know in Java there's SonarLint that'll give you a warning when casting (without checking)

[karelpeeters]

@carlos cdmp If you check it before then the compiler smartcasts and you don't need it either.

[karelpeeters]

But the name "unchecked cast" specifically refers to a cast where even at runtime you can't be sure the cast is safe to do.

[Dico]

Yes, because when you cast to a generic type parameter, the code has to "assume" that the object is an instance of that type, because the type has been erased.