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kotlinlang

<@U0ZFBBUBU> I think what's proposed in KEEP-87 <https://github.com/Kotlin/KEEP/pull/87> is a solution to this issue. The problem you describe is not fixed to `Serializable` but to any other undesirable upper bound such as `Any` in which you loose type information.
With a type class `Intersect` one could constrain which instances of `A` and `B` are valid to be intersected. The compiler would bail if you try to intersect two types for which an instance is not found in the imported scope.