I decided to build a Kotlin Plugin compiler to learn more about bytecode. I planned to build a plugin that adds a

serialVersionUID

(example below) to Kotlin classes that implement (or inherit from)

java.io.Serializable

. I know the compiler already creates those, but I wanted to simulate that (and maybe change the value to experiment with it). I got the Gradle plugin and subplugin finished, alongside the

CommandLineProcessor

and

ComponentRegistrar

. The only part left is to figure out how to: - Detect/find if the class already has a

serialVersionUID

variable declared - Add the

serialVersionUID

exactly as it is below to the declaration of the class And this last task is the one I can't figure out how to do. Should I use a

ClassBuilderInterceptorExtension

, a

ExpressionCodegenExtension

, or something else entire (because I saw there are bunchs of IR-somethings extensions to do a lot of things), what of those would be more appropriate for this purpose? And second, how to actually add fields to a class using these extensions?

private static final long serialVersionUID = 1L;

Can I test for

when

exhaustiveness without assigning the result to a variable?

val x: Unit =

feels a bit silly.

Hi all, I am just wondering what causes the issue below

"Class ... is compiled by a pre-release version of Kotlin and cannot be loaded by this version of the compiler

How can I read annotation default values in ir? I have

@Foo(val foo: Bool = true)

. I tried with

annotation.symbol.owner.valueParameters[0].defaultValue!!.expression as IrConst<Bool>

, but the expression is actually an IrErrorExpression saying

"Stub expression for default value of foo"

.

My compiler plugin has a companion runtime library. Some functions there have complex logic used by the plugin just because it would be hard to write it in IR. Is there a way to hide these functions from the end user though? For example, I scoped them inside an object to reduce their discoverability, but I’m thinking there must be some better solution.

Hey folks, if anyone is looking for a simple compiler plugin, I created this one that essentially fires a callback at runtime, every time annotated function is called. Could be useful for debugging, analytics, compose etc.

Anyone seen issues with incremental compilation in 1.7.x where KotlinCompileDaemon never finishes call to LookupSymbolKeyDescriptor.read? https://youtrack.jetbrains.com/issue/IDEA-299961

When I use Evaluate Expression while debugging, Intellij doesn't take into account any enabled compiler plugins. Is this a misconfiguration on my end, or is there simply no way to use compiler plugins in Evaluate Expression?

I'd like to check if reified generic T is implementing an interface.

interface Destination {}
interface Dialog : Destination {}

inline fun <reified T : Destination> add() {
   val isDialog1 = T is Dialog // does not compile
   val isDialog2 = Dialog::class.java.isAssignableFrom(T::class.java) // works, but uses Java reflection
   val isDialog3 = (typeOf<T>().classifier as KClass<T>).isSubclassOf(Dialog::class) // works, but uses Kotlin full reflection, doesn't it?
}

Isn't there any compiler optimized way to do this? But THB, I'm not including kotlin full reflection to my dependencies, so maybe the third way IS optimized?

Compiler plugin question - what does this error mean?

e: java.lang.UnsupportedOperationException: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:my.sample.ProblematicCallbackImpl
        at org.jetbrains.kotlin.backend.konan.llvm.CodeGeneratorVisitor$TopLevelCodeContext.unsupported(IrToBitcode.kt:253)

I identified the offending code (

irGet(thisClass.thisReceiver!!)

) but not a solution. I’m using the receiver to call a superclass function. I tried using

superClass.thisReceiver!!

instead, but that creates a different error.

When is the legacy JVM backend slated to be removed?

Hi, everyone. I have a couple of questions about compiler plugins. 1. Is there any way to uniquely identify function calls so that the identifier is not changeable until the place of the function call changes? 2. Is it possible to get information about previous compilations during incremental compilation?

Hello everyone，I want to add a new property to a class named "mjd", I can see the property after using dump() function (in the bottom of the following result).But when I test this compiler plugin, it can not find this new property. Does anyone know the reason? CLASS CLASS name:A modality:FINAL visibility:public superTypes:[kotlin.Any] annotations: DebugLog $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.A CONSTRUCTOR visibility:public <> () returnType:<root>.A [primary] BLOCK_BODY DELEGATING_CONSTRUCTOR_CALL 'public constructor <init> () [primary] declared in kotlin.Any' INSTANCE_INITIALIZER_CALL classDescriptor='CLASS CLASS name:A modality:FINAL visibility:public superTypes:[kotlin.Any]' FUN FAKE_OVERRIDE name:equals visibility:public modality:OPEN <> ($this:kotlin.Any, other:kotlin.Any?) returnType:kotlin.Boolean [fake_override,operator] overridden: public open fun equals (other: kotlin.Any?): kotlin.Boolean [operator] declared in kotlin.Any $this: VALUE_PARAMETER name:<this> type:kotlin.Any VALUE_PARAMETER name:other index:0 type:kotlin.Any? FUN FAKE_OVERRIDE name:hashCode visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.Int [fake_override] overridden: public open fun hashCode (): kotlin.Int declared in kotlin.Any $this: VALUE_PARAMETER name:<this> type:kotlin.Any FUN FAKE_OVERRIDE name:toString visibility:public modality:OPEN <> ($this:kotlin.Any) returnType:kotlin.String [fake_override] overridden: public open fun toString (): kotlin.String declared in kotlin.Any $this: VALUE_PARAMETER name:<this> type:kotlin.Any FUN name:track visibility:public modality:OPEN <> ($this:<root>.A) returnType:kotlin.String $this: VALUE_PARAMETER name:<this> type:<root>.A PROPERTY name:mjd visibility:public modality:FINAL [val] FIELD PROPERTY_BACKING_FIELD name:mjd type:kotlin.Long? visibility:private EXPRESSION_BODY CONST Long type=kotlin.Long value=1 FUN DEFAULT_PROPERTY_ACCESSOR name:<get-mjd> visibility:public modality:FINAL <> ($this:<root>.A) returnType:kotlin.Long? correspondingProperty: PROPERTY name:mjd visibility:public modality:FINAL [val] $this: VALUE_PARAMETER INSTANCE_RECEIVER name:<this> type:<root>.A BLOCK_BODY RETURN type=kotlin.Nothing from='public final fun <get-mjd> (): kotlin.Long? declared in <root>.A' GET_FIELD 'FIELD PROPERTY_BACKING_FIELD name:mjd type:kotlin.Long? visibility:private' type=kotlin.Long? origin=null receiver: GET_VAR '<this>: <root>.A declared in <root>.A.<get-mjd>' type=<root>.A origin=null

Hi, when creating an inherited class within a function that refers to properties of the parent scope, it creates a constructor which is somehow reported to be-zero arg, but when creating an instance, it turns out it is not:

import kotlin.reflect.KClass


open class Provider {

    open fun computeSmthg() = 42
}

class ConfigBuilder(val other: Int = 32) {

    fun asProvider(): KClass<*> {

        class CustomProvider : Provider() {

            override fun computeSmthg(): Int {
                return other
            }
        }

        return CustomProvider::class
    }
}

fun main() {

    val providerClass = ConfigBuilder().asProvider()

    require(providerClass.constructors.first().parameters.isEmpty())

    val constructor = providerClass.constructors.first()
    println(constructor.parameters)
    println(constructor)

    println(constructor.call())
}

which fails with

fun <init>(): com.systema.nexperia.epi.solver.`ConfigBuilder$asProvider$CustomProvider`
Exception in thread "main" java.lang.IllegalArgumentException: Callable expects 1 arguments, but 0 were provided.

Could I rewrite the code from above to actually create CustomProvider with a zero-arg constructor while referring to

òther

property?

Huh, I see that function references generate one class per use site for JVM. Is this something unavoidable? The reference has to store the receiver, so I guess a new instance creation is unavoidable, but I guessed it will be one general class, not one per use site.

class E {
    fun b1() = Unit
    val b = B(this::b1)
    val c = B(this::b1)
}

class B(
    val func: () -> Unit
)

Results in 4 classes: • B.class • E.class • E$b$1.class • E$c$1.class In my specific use case I have a number of compiler plugin generated functions I pass, like in the example below. I could write a workaround by generating one function that gets the instance of E and an integer index and uses a

when

to select the appropriate function. But that feels like a bit forced.

class E {
   fun a1() = Unit
   fun a2() = Unit
   init {
      B(this::a1)
      B(this::a2)
   }
}

I was just wondering if it would be worth the effort creating a interoperability layer between intellisense and compiler. So that while you code the knowledge the intellisense gains, can directly be used by the compiler. And vice versa, the intellisense can hot start upon the last cache of the compiler. So that all the information doesn't need to be cached twice. Maybe you could also start compiling small changes in the background so that when you just make a little change the compiler only needs to pack the executable together and is ready to go. With optimizations to gradle this could also improve developer experience with Kotlin/JS and continous development. Personally i find it a bit annoying that it takes so long to apply the changes, maybe you can kill multiple birds with one stone there.

Hello! How to deep copy IrElement with remaping some symbols?

Hello 👋 I have some doubts about expect/actual support in IR plugins. For functions, for example: • I can see

IrFunction.isExpect

, but how to retrieve the actual (assuming they are compiled together)? Do I need a full module lookup, looking for a function with the same fq name? • Given an IrFunction, how to implement

IrFunction.isActual

?

Hello everyone, I want to change the modality of property from final to abstract. Does anybody how to do this? many thanks!

Hi, how should I use the command-line compiler to perform incremental compilation?

Hello, I'm thinking about writing a compiler plugin to transpile kotlin to another language, but most tutorials and videos I find around that are several years old. Is there a more recent documentation, maybe more specifically around the code generation step, i.e. converting IR into a custom language?

Huh, no forward knot tying or whatever it's called with mutually recursive functions inside a body?

setContent {
  ...
  suspend fun func1() {
    func2()
  }
  suspend fun func2() {
    func1()
  }
}

Tells me

func2

isn't defined in

func1

Hi friends. I am working with Kotlin embedded compiler and I have a

org.jetbrains.kotlin.psi.KtNamedFunction

. Anyone know how I can get the line number in which the function resides. I can get the location with

startOffsetSkippingComments

and I assume I could calculate it myself by reading the file, but I was wondering, if there might be a different way.

Are the new Kotlin compilers multi-platform? In other words, can I compile the compiler to JS (or web-assembly in the future) so I can run the compiler itself in a browser. Perhaps already documented somewhere but couldn’t find it.

in ktor-server-html-builder-jvm, there’s an interesting Kotlin detail that I’m wondering if anyone here knows more about:

respondHtml(status) { with(template) { apply() } }

. The use of

with

here seems to be used to make sure that

apply()

refers to the method that’s defined as a method on

HTML<T>

that

template

implements. If you write

template.apply()

it resolves to the built in scope function

apply

. What is it about the use of

with

that makes Kotlin invoke the

apply

method on

HTML<T>

rather than the scope function?

Hi here. If i compile kotlin source that depends on java source (not compiled yet), are there any restrictions on the java source? I know that if it uses lombok, i must use lombok plugin, but things like java language version? Also, would i be significantly down on a compile time if the most files in the maven module are java and only a few kotlin? Is it ok to have such a mixed module? Thanks a lot.

Is it expected that a sealed interface can be implemented from any package (and any module I suspect) by using delegation? E.g.

Bar : Foo by FooImpl()

. Here Bar is a Foo without being a FooImpl, so it feels like it is a new direct implementation.

random thought of the day: it would be cool if Kotlin had a feature where annotations could apply super powers to a scope so that the file would compile even if the code in that scope doesn’t compile. Use case: tests annotated with

@Test

, if it doesn’t compile, the test fails, but the other tests still run

Hello! How can i change IrField from val to var during transformation by compiler plugin? isFinal property of IrField is readonly.