-- Common --
Exit code: OK
Output:
compiler/testData/multiplatform/weakIncompatibilityWithoutActualModifier/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 Foo
^

-- JVM --
Exit code: COMPILATION_ERROR
Output:
compiler/testData/multiplatform/weakIncompatibilityWithoutActualModifier/jvm.kt:1:11: error: declaration must be marked with 'actual'
interface Foo
          ^