:kotlin_emoji::kotlin_emoji: <https://blog.jetbrai...

# announcements

[Alina Dolgikh [JB]]

KK Introducing Kotlin 2.0! KK

With the release of Kotlin 2.0, which features the stable K2 compiler, we are now entering a new era of Kotlin. This update isn’t just about speed; it’s a comprehensive upgrade to improve your development experience across all platforms. Here’s what you can look forward to:

• Twice as fast compilations
• Enhanced code analysis
• Improved IDE performance
• First-party support for multiplatform projects
• Seamless migration
Explore how Kotlin 2.0 can elevate your projects and get started with it today. Check out our latest blog post for more details.

➡️ Learn more about Kotlin 2.0 ⬅️

[Manuel Bogner]

Very nice. Thanks a lot. The gradle plugin also already exists -> https://plugins.gradle.org/plugin/org.jetbrains.kotlin.jvm

See you at #KotlinConf

[Matt Robertson]

Congrats to the team, and well done! Such a significant accomplishment.

[Stephan Schröder]

👍

[Manuel Bogner]

First Spring Boot app already migrated without any findings/problems. kodee happy

[Ahsan Ullah Rasel]

I have a question. In your K2 compiler migration guide, is the below code correct? I think this is wrong.
Here, Tau interface doesn't implements any other interfaces, then how this if block executes?

interface Rho {
    operator fun inc(): Sigma = TODO()
}

interface Sigma : Rho {
    fun sigma() = Unit
}

interface Tau {
    fun tau() = Unit
}

fun main(input: Rho) {
    var unknownObject: Rho = input

    // Check if unknownObject inherits from the Tau interface
    if (unknownObject is Tau) {

        // Use the overloaded inc() operator from interface Rho,
        // which smart-casts the type of unknownObject to Sigma.
        ++unknownObject

        // In Kotlin 2.0.0, the compiler knows unknownObject has type
        // Sigma, so the sigma() function can be called successfully.
        unknownObject.sigma()

        // In Kotlin 1.9.20, the compiler thinks unknownObject has type
        // Tau, so calling the sigma() function throws an error.

        // In Kotlin 2.0.0, the compiler knows unknownObject has type
        // Sigma, so calling the tau() function throws an error.
        unknownObject.tau()
        // Unresolved reference 'tau'

        // In Kotlin 1.9.20, the compiler mistakenly thinks that 
        // unknownObject has type Tau, so the tau() function can be
        // called successfully.
    }
}

[Sunil Kumar]

Hi team, why we have not added all the changes in official docs link of whats new in kotlin 2.0, like union type for errors, backing field etc, Or may be more but i came across these two as i got to know about them from twitter and some other places but didnt found them in official docs.

[Andrey Polyakov [JB]]

Hey @Ahsan Ullah Rasel
The code is 100% correct. The question was raised before, so we added a note about it.
Refer to this PR for details: https://github.com/JetBrains/kotlin-web-site/pull/4224

[Ahsan Ullah Rasel]

Hello @Andrey Polyakov [JB]
Thank you for adding the note, as this now clears up the confusion.

[Andrey Polyakov [JB]]

> Hi team, why we have not added all the changes in official docs link of whats new in kotlin 2.0, like union type for errors, backing field etc, Or may be more but i came across these two as i got to know about them from twitter and some other places but didnt found them in official docs.
Hey @Sunil Kumar
Could you add some details about features you are talking about?

Backing fields update is still in progress (it is still a prototype, not even Experimental status) https://youtrack.jetbrains.com/issue/KT-14663
Union types for errors are not implemented yet.

[Sunil Kumar]

Ok Got it, thanks @Andrey Polyakov [JB] for clarification, that was my confusion if they are released or not as i missed the KotlinKonf online so i was not aware.