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kotlinlang

Today we encountered `Inheritance from an interface with ‘@JvmDefault’ members is only allowed with -Xjvm-default option`
I tried Googling and searching in this Slack, but came up short.
I understand why the interface compilation needs this flag. But why do the implementations need this flag too? Can't the compiler see that the interface is compiled on JVM target 8 and uses the `default` Java 8 in the method and simply compile as if you implemented in Java?
Here's a concrete incarnation of this problem: <https://ecosystem.atlassian.net/browse/JPERF-260>

As @JvmDefault is experimental feature everything could be changed, so if your code inherits @JvmDefault it also could be broken with upcoming changes (I mean binary compatibility problems)

uh oh, that's a surprise
the experimental nature of `@JvmDefault` is not documented in the docs, or in the annotation KDoc or as an IntelliJ warning
PS. despite the experimental status, do we know why the implementors need the compiler flag?

I think the compiler flag is the marker of its experimental status. `@JvmDefault` came in before the `@Experimental` annotation existed