warning: language version 2.0 is experimental, there are no backwards compatibility guarantees for new language and library features compiler/testData/cli/jvm/k2SimpleMultiplatformGenericClass/common.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning. expect class AtomicRef { ^ compiler/testData/cli/jvm/k2SimpleMultiplatformGenericClass/jvm.kt:1:1: warning: the expect/actual classes (including interfaces, objects, annotations, enums, actual typealiases) are an experimental feature. You can use -Xexpect-actual-classes flag to suppress this warning. actual class AtomicRef constructor(value: T) { ^ OK