kotlinlang #kotlin-native

Is there a file IO library for Kotlin Native that supports Linux and maybe macOS or Windows? I’m writing a CLI program and Kotlin Native may help with improving experience. Should I just stick to JVM for CLI?

napperley

07/11/2021, 11:31 PM

Is it possible to swap the linker (GCC Gold) that Kotlin Native (with Kotlin 1.5.0 onwards) uses for a newer version (also GCC Gold), and if so where is the linker located on a Linux host? Is gold the linker that Kotlin Native uses ( https://stackoverflow.com/questions/3476093/replacing-ld-with-gold-any-experience )? I'm wondering if the new linker used by Kotlin 1.5.0 makes linking significantly faster than Kotlin 1.4.31; are there any benchmarks available? From experience linking takes up about two thirds of the build time (painfully SLOW!) for a Kotlin Native program.

martmists

07/12/2021, 9:04 AM

Is it possible to have an AtomicReference to a list? I'm getting this error:

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Uncaught Kotlin exception: kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen kotlin.collections.ArrayList@1aa3f68
    at kfun:kotlin.Throwable#<init>(kotlin.String?){} (0x4169a9)
    at kfun:kotlin.Exception#<init>(kotlin.String?){} (0x410c87)
    at kfun:kotlin.RuntimeException#<init>(kotlin.String?){} (0x410d97)
    at kfun:kotlin.native.concurrent.InvalidMutabilityException#<init>(kotlin.String){} (0x433557)
    at ThrowInvalidMutabilityException (0x434a76)
    at Kotlin_AtomicReference_checkIfFrozen (0x523c71)
    at kfun:kotlin.native.concurrent.AtomicReference#<init>(1:0){} (0x4328ae)
    at ...

MJegorovas

07/12/2021, 9:30 AM

Anybody could help me converting this obj-c code to kotlin (in thread):

y9san9

07/12/2021, 2:20 PM

Hello mates, while using Kotlin Multiplatform I came across a following issue in Swift. In kotlin we have awesome feature like

Nothing

type, I was trynna use it with generics in entity like

Either

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sealed interface Either<out TLeft, out TRight> {
    class Failure<T>(...) : Either<T, Nothing>
    class Success<T>(...) : Result<Nothing, T>
    
}

This is cool approach in Kotlin and everything works fine:

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val result: Either<Entity, Error> = result as Success<Entity>

BUT in swift I can't do stuff like this:

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guard let result: Either<Entity, Error> = result as? Success<Entity> else { return }

This will break at runtime, since swift generics aren't erased, and it won't pass type check (

Nothing

Error

). Any ideas how to workaround it? cc @alex009

👍 1

👀 1

napperley

07/12/2021, 11:22 PM

In a Kotlin Multiplatform project that is targeting linuxArm32Hfp if Kotlin 1.5.0 or later is used then a boatload of undefined reference errors appear (at the linking stage), eg:

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/home/napperley/.konan/dependencies/arm-unknown-linux-gnueabihf-gcc-8.3.0-glibc-2.19-kernel-4.9-2/arm-unknown-linux-gnueabihf/bin/ld.bfd: /mnt/pi_image/usr/lib/arm-linux-gnueabihf/libgdk-3.so: undefined reference to `wl_display_dispatch_pending'

However if Kotlin 1.4.31 is used then none of the errors appear, and the build is successful. In the build output there are a boatload of warnings about missing libraries (at the linking stage) if Kotlin 1.5.0 or later is used, eg:

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/home/napperley/.konan/dependencies/arm-unknown-linux-gnueabihf-gcc-8.3.0-glibc-2.19-kernel-4.9-2/arm-unknown-linux-gnueabihf/bin/ld.bfd: warning: libpcre.so.3, needed by /mnt/pi_image/usr/lib/arm-linux-gnueabihf/libglib-2.0.so, not found (try using -rpath or -rpath-link)

Are there some additional linking options that need to be passed to the linker to resolve the errors, and if so which ones?

napperley

07/12/2021, 11:37 PM

There is a lack of documentation on the linking process when developing a Kotlin Native program. No information is present on the linker used in Kotlin 1.5.0 onwards for example. What would happen if someone wants to use a newer linker to resolve GLIBC version issues?

Matthias Geisler

07/14/2021, 7:56 AM

Does anybody has experience with SwiftCrypto usage with Kotlin? I am asking since I am in need of crypto and to do it with objective-c interop looks super error prone.

Iaroslav Postovalov

07/15/2021, 3:13 PM

Hello! I'm experiencing a very bizarre error with Kotlin/Native with

mingwX64

. My test process fails with

-1073741515

exit code and no output. When I've opened the

test.exe

binary with Dependency Walker, it gave out that binary can't be linked with some Microsoft binaries.

👀 2

Iaroslav Postovalov

07/15/2021, 5:10 PM

OK, now my problem is that

ld

successfully links against

.lib

file, but as the result

.dll

is lost, and the executable can't find it

Iaroslav Postovalov

07/16/2021, 7:59 AM

How to disable compilation of Native target but still have it in metadata?

itnoles

07/17/2021, 2:45 PM

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suspend fun fetch() : HttpResponse = suspendCoroutine {
    val semaphore = dispatch_semaphore_create(0)
    val nativeRequest = NSMutableURLRequest(uRL = NSURL.URLWithString("<https://api.spacexdata.com/v4/launches>")!!)
    nativeRequest.setHTTPMethod("GET")
    val result = AtomicReference(HttpResponse().freeze())
    val completionHandler = { nsData: NSData?, nsURLResponse: NSURLResponse?, nsError: NSError? ->
        if (nsError != null) {
            val message =
                "The response is: " + nsURLResponse?.description() + ", error is: " + nsError.description()
            println(message)
        }
        val response = nsURLResponse as NSHTTPURLResponse
        val httpResponse = HttpResponse().apply {
            statusCode = response.statusCode.toInt()
            body = nsData?.bytes?.reinterpret<ByteVar>()?.toKString()
        }.freeze()
        result.value = httpResponse
        dispatch_semaphore_signal(semaphore)
        Unit
    }.freeze()
    val task =
        NSURLSession.sharedSession.dataTaskWithRequest(nativeRequest, completionHandler)
    task.resume()
    dispatch_semaphore_wait(semaphore, DISPATCH_TIME_FOREVER)
    it.resume(result.value)
}

I really want to simplified this code. Can anyone help me with it?

Big Chungus

07/17/2021, 10:43 PM

If i build target C lib for cinterops on windows with Visual Studio CMAKE, is it expected to work? Or must i build target C libs on MSYS2/CYGWIN to make them "consumable" by K/N? Currently I'm getting this error when compiling kotlin executable on windows, while it works fine on OSX and Ubuntu

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Type mismatch: inferred type is bool /* = Byte */ but Boolean was expected

Big Chungus

07/18/2021, 5:07 PM

Trying to run a simple test on mingwX64 and getting this weird error

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Cause: cannot assign instance of java.util.Collections$EmptyList to field java.lang.StackTraceElement.moduleVersion of type java.lang.String in instance of java.lang.StackTraceElement

The test

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import kotlin.test.Test
import kotlin.test.assertEquals

class TestMe {
   @Test
   fun shouldTest(){
      assertEquals("test", "test");
   }
}

Any pointers?

吴少滨

07/21/2021, 3:51 AM

I need to pass the data model to C++ from Kotlin Native. My current solution is serialization and deserialization through protocol, but as the level of model data increases, it takes more time to transfer the proto method. So I want to find a better solution to replace it. There are some questions about it. 1.Any better suggestions? 2.Now my idea is to create a data model directly in C++. But Kotlin/Native doesn't support C++Interop; Is there any way for Kotlin/Native to get/set the C++ model?

coolcat

07/21/2021, 8:47 PM

Has anyone had any success with the

native.cocoapods

plugin recently? I am trying to write a KMM library whose iOS code depends on a cocoapod, which I import using

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cocoapods {
  pod("AFNetworking")
}

However

cinterop

gives me

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fatal error: module 'AFNetworking' not found

as in this issue. But I don’t think it’s the same problem. Anyone had similar?

napperley

07/22/2021, 12:54 AM

What does the early version of Kotlin 1.5.30 support in terms of platform code sharing with the C libraries (eg C pointers)?

AJ Alt

07/23/2021, 3:47 PM

With support for Apple Silicon being added in 1.5.30, will you be able to cross compile for the M1 chips from an Intel Mac?

Julius Hannink

07/26/2021, 8:14 AM

Same here, no idea what causes this 😐

@ankushg

any progress on your side?

吴少滨

07/26/2021, 12:07 PM

Is there any documents or demo about Kotlin/Native CInterop for first learning?The official documents can't make me understand. I just touched it not long ago.But CValue、CPointer、CValueVar、CValues and so on that confuses me.I need a simple or detail demo about that.😭

kpgalligan

07/27/2021, 11:59 PM

Curious about "encoding" in

@ObjCMethod

annotation. We've been doing some experiments with cinterop and can successfully link and call to objc methods. As a concrete example, on iOS the objc class for Crashlytics is

FIRCrashlytics

. We only care about getting the global instance and logging a string, so after seeing what cinterop does, we just made this Kotlin class. It'll successfully link to the objc, and calls the methods as we expect.

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@ExternalObjCClass
open class FIRCrashlytics : NSObject() {
    @ExternalObjCClass
    companion object : NSObjectMeta(), ObjCClassOf<FIRCrashlytics> {
        @ObjCMethod("crashlytics", "@16@0:8")
        external fun crashlytics(): FIRCrashlytics
    }
    @ObjCMethod(selector = "log:", encoding = "v24@0:8@16")
    open external fun log(msg: String)
}

👀 2

Kartik Prakash

07/28/2021, 1:27 AM

Does anyone have a good example a KMP library being published for iOS (Kotlin-Native)? Ideally we want to build a KMP library publish it and consume it in a pure iOS project Obj-C or Swift.

benkuly

07/28/2021, 10:23 AM

Hi, what's the difference between

someByteArray.refTo(0)

and

someByteArray.pinned{it.addressOf(0)}

? Which of them should I use, when I call a native function? And what shoud I do, when the function wants

CValuesRef<uint8_tVar /* = UByteVarOf<uint8_t /* = UByte */> */>

? Is it enough to do

someByteArray.asUByteArray().refTo(0)

👋 1

❓ 1

Landry Norris

07/28/2021, 2:45 PM

I noticed that I can't find SwiftUI in the platform package. Is there a timeline on when SwiftUI will be available in iosMain? I'm trying to get an expect/actual for state to use for SwiftUI/Compose. I'd like to be able to use the expect/actual to create the state variables in shared code. This works for Compose, but I can't get the iOS side working without a platform.SwiftUI

Matthias Geisler

07/29/2021, 6:12 PM

Are there any special moves besides obvious things to make the linker faster for iOS?

napperley

07/30/2021, 3:13 AM

I am trying to use the

cairo_region_create_rectangles

function ( https://www.cairographics.org/manual/cairo-Regions.html#cairo-region-create-rectangles ) from the Cairo library, but the function is after

CValuesRef<cairo_rectangle_int_t>?

as the first parameter and I don't know how to provide a

CValuesRef

that contains multiple struct pointers. Below is the code that fails to compile (the values variable doesn't match what the

cairo_region_create_rectangles function

is expecting):

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// ...
fun createWithMultipleRectangles(vararg rectangles: IntRectangle): Region {
            val tmpArr = rectangles.map { it.cairoRect.ptr }.toTypedArray()
            val values = cValuesOf(*tmpArr)
            return Region(cairo_region_create_rectangles(values, rectangles.size))
        }
// ...

Tristan

07/30/2021, 8:31 PM

Hello, I have a class in Kotlin with methods such as

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class MyClass {
    private val arrayQueue = ArrayQueue<String>()

    fun save(item: String) {
        arrayQueue.add(item);
    }

    val last: String
        get() = arrayQueue.last()
}

I use it in objective C

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+ (instancetype)sharedInstance {
    static NativeClass *nativeClass = nil;
    static dispatch_once_t onceToken;

    dispatch_once(&onceToken, ^{
        nativeClass = [[NativeClass alloc] init];
        nativeClass.myClass = [[MyClass alloc] init];
    });

    return nativeClass;
}

First of all, accessing it was an issue just to get

.last

, so I created a wrapper to get a frozen version.

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fun getMyClass() = MyClass().freeze()

But by doing this, I cannot mutate it anymore kotlin.native.concurrent.InvalidMutabilityException: mutation attempt of frozen
How can I overcome this kind of issue?

iamsteveholmes

07/30/2021, 8:40 PM

Does anyone know how to upgrade to the latest App structure instead of AppDelegate and SceneDelegate? Asked this on #multiplatform https://kotlinlang.slack.com/archives/C3PQML5NU/p1627586038107100

Landry Norris

08/02/2021, 3:28 PM

Is there anywhere to track the progress of the new GC system? Freezing tends to interfere with other thread-safe methodologies (as the original article on freezing suggests), so the fact that the K/N team suggested that the new GC will not require freezing is helpful. In May, they estimated a dev preview would be available by end of Summer, which is getting close.