Java compatibility with inline value classes

[LVMVRQUXL]

🤔 The problem

When declaring an inline value class in Kotlin, the functions receiving it as a parameter are mangled by adding a stable hash code to the function name.

@JvmInline
value class UInt(val x: Int)

// Represented as 'public final void compute(int x)' on the JVM.
fun compute(x: Int) { }

// Represented as 'public final void compute-<hashcode>(int x)' on the JVM.
fun compute(x: UInt) { }

This solution provided by the language makes these functions incompatible with Java: their identifier is invalid because of the - character.

💡 The idea

The idea is to disable mangling by marking them with the JvmName annotation and bringing back their compatibility with Java.

@JvmInline
value class UInt(val x: Int)

// Represented as 'public final void compute(int x)' on the JVM.
fun compute(x: Int) { }

// Represented as 'public final void computeUInt(int x)' on the JVM.
@JvmName("computeUInt")
fun compute(x: UInt) { }

✅ Checklist

• Identify types declared as inline value class and there usages.
• Create an issue for each types identified and track them below.
• Java compatibility with API of NotBlankString #154
• Java compatibility with API of StrictlyPositiveInt #160
• Java compatibility with API of StrictlyNegativeInt #161
• Java compatibility with API of StrictlyPositiveDouble #162
• Java compatibility with API of NotEmptyList #157
• Java compatibility with API of NotEmptySet #158
• Java compatibility with API of NotEmptyMap #159

🙏 Help needed

Please give this post a reaction if you are interested in this change and comment below your thoughts on it.
We would love to have your feedback!

[LVMVRQUXL]

Because we want to focus our effort on improving the API for Kotlin users, we will not implement this idea.