After this change, optional expected annotations will be compiled to
physical class files on JVM, and stored to metadata on other platforms,
to allow their usages from dependent platform modules. For example:
@OptionalExpectation
expect annotation class A
When compiling this code on JVM, A.class will be produced as if the
class A did neither have the 'expect' modifier, nor had it been
annotated with OptionalExpectation. Note that if there's no actual
annotation class for A, then usages (which can only be usages as
annotation entries) are simply skipped.
Class A will be public from Kotlin's point of view (since it should
be possible to use it in Kotlin sources), but _package-private_ in Java
to disallow its usages outside of the declaring module.
#KT-18882 Fixed
#KT-24617 Fixed
This commits adds a new annotation OptionalExpectation to the standard
library, which is experimental. To enable its usage, either pass
'-Xuse-experimental=kotlin.ExperimentalMultiplatform' as a compiler
argument, or '-Xuse-experimental=kotlin.Experimental' and also annotate
each usage with `@UseExperimental(ExperimentalMultiplatform::class)`
#KT-18882 Fixed
