Hi - just read this article about the need to add `@JvmSynthetic` to `internal` members to properly ...

# compiler

[Rob Elliot]

Hi - just read this article about the need to add @JvmSynthetic to internal members to properly hide them from Java:
https://medium.com/scalereal/hide-internal-members-of-kotlin-module-from-jvm-c7730507fb17

which informed me of @JvmSynthetic https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.jvm/-jvm-synthetic/

which in turn led me to ACC_SYNTHETIC
https://docs.oracle.com/javase/specs/jvms/se15/html/jvms-4.html

Is there a reason why the compiler with the JVM backend doesn’t just add the ACC_SYNTHETIC access_flag to internal methods without needing to add the noise of an extra annotation?

[Rob Elliot]

I suppose if you were writing a mixed Java/Kotlin module you might want to call an internal Kotlin member from Java… though I’ve always thought that a pretty odd thing to do.

[Ilmir Usmanov [JB]]

The reason is simple: synthetic is for synthetic declarations and some tools, most notably IntelliJ debugger usually skip them.

There is another way to hide Kotlin internal functions from Java, which does not affect tools so much - @JvmName with a dash in new name.

[Rob Elliot]

I was really hoping to avoid extra annotations. But perhaps it’s simpler to just say that anyone calling a method with $library at the end of the name from Java is responsible for their own pain when I rename / delete it!