kotlinlang #kotlin-native

w: Linking two modules of different data layouts: '/var/folders/8j/m605_xwx6s93xxf3tjfbkqlm0000gn/T/native4890200288988106563/cstubs.bc' is 'e-m:o-p:32:32-Fi8-i64:64-a:0:32-n32-S128' whereas 'out' is 'e-m:o-p:32:32-i64:64-i128:128-n32:64-S128'

w: Linking two modules of different target triples: /var/folders/8j/m605_xwx6s93xxf3tjfbkqlm0000gn/T/native4890200288988106563/cstubs.bc' is 'thumbv7k-apple-watchos5.0.0' whereas 'out' is 'aarch64_32-apple-watchos5.0.0'

Kotlin 1.7.20-Beta with macOS 13 (22A5331f) and Xcode 14.0 beta 6 (14A5294g)

darkmoon_uk

09/07/2022, 12:49 PM

What's the most efficient way to convert a platform

float

representation to a Kotlin

ByteArray

darkmoon_uk

09/07/2022, 12:50 PM

I would prefer to mutate the same allocated

ByteArray

since I need to do this very often (preparing data for a shader).

Adam Cooper

09/07/2022, 9:30 PM

Can someone please describe to me, or link to some detailed documentation, about how

usePinned

works in terms of C code? I am wondering why it is necessary, or perhaps if I am misusing it. If I am misusing it, then I would like to know what situations it should be used in. The way I have used it is similar to this:

// declare a 256 byte array to pass to a C function as an output parameter
UByteArray(SHA256_DIGEST_LENGTH).usePinned { signatureBuf ->
    c_func(signatureBuf.addressOf(0))
}

My understanding of the equivalent of this in C:

unsigned char signatureBuf[SHA256_DIGEST_LENGTH];
c_func(signatureBuf);

c_func

computes some value and stores it in the address provided by its parameter. This is a simplistic example and obv not good code. Just want to show my understanding of it.

Adam Cooper

09/08/2022, 12:28 AM

When I attempt to run a test (CTRL+Shift+F10 in the test file), it runs just fine. But if I try to run with the debugger using the same configuration, the debugging window says "Test events were not received." Any advice on creating debuggable test configurations?

09/09/2022, 3:38 AM

I'm getting

e: Could not find 'main' in '<root>' package.

when trying to build either of the modules in my project. I've set up the gradle config like this

linuxX64("native") {
    binaries {
        executable("prism")
    }
}

Paddy O'Brien

09/14/2022, 8:11 PM

Is there a way to disallow certain values used for the

swift_name

attribute when generating the Objective-C header? Upgrading to Apollo 3 and Codegen is now resulting in a scalar whose name is

URL

which of course is resulting in name conflicts when importing the framework into swift, Been bitten by this before, just wondering if theres a way that doesn’t involve changing swift code to accommodate changes in the Kotlin env

Paddy O'Brien

09/14/2022, 8:15 PM

Alternatively, if there is a way to change the generated scalar name created during apollo code gen that’d also work

kevin.cianfarini

09/16/2022, 8:36 PM

Do Kotlin value types get “packed” when used in arrays? One of the main goals of Valhalla on the JVM is the following.

Arrays of value types should be packed, without indirections, as arrays of primitives are now.

Since Kotlin has separate, specialized, types for each primitive value how does this bode for value classes on Native? I imagine that

Array<MyValueClass>

would be boxed unless the compiler/runtime were doing some magic I’m unaware of.

Adam Cooper

09/17/2022, 6:23 AM

I'm having trouble getting a native program to link on certain distros. On my host machine, I'm running Manjaro, which keeps system libs in

/usr/lib

and

/usr/include

. My program is able to build just fine on this distro. I'm trying to build on Ubuntu, which uses

{/usr/lib,/usr/include}/x86_64-linux-gnu

. I have my compiler options defined in a .def:

compilerOpts.linux = -I/usr/include -I/usr/include/x86_64-linux-gnu
linkerOpts.linux = -L /usr/lib -L/usr/lib/x86_64-linux-gnu -lpthread -lssl -lcrypto

My executable is defined in

build.gradle.kts

as follows:

binaries {
            executable {
                // Use system C libraries
                val sysRoot = "/"
                val libgccRoot = File("/lib/gcc/x86_64-linux-gnu/").takeIf { it.exists() }
                    ?: File("/lib/gcc/x86_64-pc-linux-gnu/")
                // Use the most recent GCC available on the host
                val libgccPath = file("${libgccRoot.absolutePath}/${libgccRoot.list()!!.last()}")
                val overriddenProperties =
                    "targetSysRoot.linux_x64=$sysRoot;libGcc.linux_x64=$libgccPath"
                val compilerArgs = "-Xoverride-konan-properties=$overriddenProperties"
                this.freeCompilerArgs += listOf(compilerArgs)
                this.entryPoint = "opstopus.deploptopus.main"
                this@binaries.findTest("debug")?.let { it.freeCompilerArgs += listOf(compilerArgs) }
            }
        }

On Ubuntu, I consistently get this error:

/root/.konan/dependencies/x86_64-unknown-linux-gnu-gcc-8.3.0-glibc-2.19-kernel-4.9-2/x86_64-unknown-linux-gnu/bin/ld.gold: error: cannot open //usr/lib/crt1.o: No such file or directory
/root/.konan/dependencies/x86_64-unknown-linux-gnu-gcc-8.3.0-glibc-2.19-kernel-4.9-2/x86_64-unknown-linux-gnu/bin/ld.gold: error: cannot open //usr/lib/crti.o: No such file or directory
/root/.konan/dependencies/x86_64-unknown-linux-gnu-gcc-8.3.0-glibc-2.19-kernel-4.9-2/x86_64-unknown-linux-gnu/bin/ld.gold: error: cannot open //usr/lib/crtn.o: No such file or directory

I confirmed that all 3 of these object files are in

/usr/lib/x86_64-linux-gnu

on Ubuntu. Why is it only searching in

/usr/lib

Jonas TM

09/17/2022, 10:28 AM

[Are context-receivers available in Kotlin/Native?] 🧵

Jeff Lockhart

09/18/2022, 12:37 AM

The docs say about converting Kotlin strings to C strings:

To get the pointer,
.cstr
should be allocated in native memory, e.g.

val cString = kotlinString.cstr.getPointer(nativeHeap)

But

getPointer()

accepts an

AutofreeScope

parameter, which

nativeHeap

doesn't fulfill. Seems like it should be accepting a

NativePlacement

instead. (Maybe it used to?) Is there a more concise/idiomatic way to copy a Kotlin string to the native heap than something like this?

val string = "my kotlin string"
val bytes = string.encodeToByteArray()
val cPtr = nativeHeap.allocArray<ByteVar>(bytes.size + 1)
bytes.usePinned {
    memcpy(cPtr, it.addressOf(0), bytes.size.convert())
}

napperley

09/19/2022, 1:35 AM

Are the linking times going to be shorter with the Kotlin 1.7.20 release?

Jeff Lockhart

09/21/2022, 1:26 AM

Is it possible to get a reference to a lambda as a C pointer (

CValuesRef<*>

)? My API requires passing an arbitrary Kotlin lambda to a C library as a C function pointer. My understanding is that

staticCFunction()

would not be able to capture the lambda to call inside it:

staticCFunction { ~lambda()~ }

. I am able to have a context passed to the C Function as a

COpaquePointer

though. I could have the lambda passed as this context parameter, if there would be a way to get a reference to it as a C pointer.

martmists

09/21/2022, 3:11 PM

I noticed in the docs that threads aren't supported in kotlin/native; Is there an example on background tasks that can be started once and stopped once, and keep updating an array for the entire duration they're active for?

Jeff Lockhart

09/22/2022, 9:03 PM

Is array index access

[]

only available for

CPointer<ByteVar>

? The docs seem to imply it should be possible for any

CPointer<T>

, but I only see the extension available for

CPointer<ByteVar>

(the docs show

CPointer<BytePtr>

in the example code). Do I have to

reinterpret<ByteVar>()

in order to iterate an array of a different pointer type?

Phạm Nhật

09/23/2022, 6:55 AM

Hi everyone. About this discussed thread for building multi-pods in multi-module projects world, is this limitation currently resolved or any workarounds available? https://kotlinlang.slack.com/archives/C3SGXARS6/p1631617605196000

Rihards

09/26/2022, 10:37 AM

Hi! Some help would be much appreciated on working with recycler view. I need to display data that I receive from the API in the horizontal recycler view. Each adapter item contains two TextViews and one ImageView, so the size of the view can vary for each data item. The issue is that I need to adjust all adapter item heights to the item that has the biggest height, but I can’t really find a way to do that since the item is not displayed in the screen till I scroll to it. Also, when I check some heights in

onBindViewHolder

they are zero.

Alexandre Brown

09/27/2022, 2:10 PM

Hello, I'm wonder how can I have something like Java JNI but for Kotlin? How do I generate a c/c++ header from Kotlin code? I have a JVM project (not multiplatform) where I would like to create a small Kotlin class to genenrate the c++ header then I will write C++ code to fulfill my needs. Is that doable?

Krystian

09/28/2022, 9:26 PM

Hi. I'm doing a binding to a C game framework library and I'm manually tweaking some of the funcs. One function requires: const void *value (value is a parameter) Would I just need a CPointer for this? The generated binding shows that for the value parameter it would accept CValuesRef<*>?

Pablo

09/29/2022, 11:48 AM

Hi, which is the best and recommended way to program user interfaces for kotlin native for windows/linux? I recently disscovered compose multiplatform, but it seems to require a JVM installed, so it's not what I'm searching for. I'm interested in learning how to develop native applications for windows/linux not dependant of a JVM.

spierce7

09/29/2022, 3:27 PM

Is there any way to easily access Kotlin native libraries via jni in a JVM application?

spierce7

09/29/2022, 3:27 PM

I feel like I remember reading about a bridge or something years ago

Jeff Lockhart

09/30/2022, 2:08 AM

Does anyone know if there's a way to link a cinterop dynamic .so library from a relative path within the project? This workaround seems to only work for static libraries.

ribesg

09/30/2022, 8:53 AM

VARIABLE_IN_SINGLETON_WITHOUT_THREAD_LOCAL

still meaningful with the NMM or not?

Krystian

10/01/2022, 6:00 PM

Is there a known issue with cinterop having problems converting macros with custom types? I'm trying to create a binding for C game framework library Raylib and it seems that custom defined colors of type struct Color holding unsigned char are not being converted over to Kotlin?

Trevor Stone

10/03/2022, 9:03 PM

But to avoid needing to do that, you need to sign the app as well as notarize it

Katarzyna

10/06/2022, 8:31 AM

Dear Kotlin-native lovers, I am the manager of the self-publishing house. We are connected mainly with Kotlin. Our expert on this topic is Marcin Moskała. You could probably know him from conferences, workshops, and books: Kotlin Coroutines, Effective Kotlin, and Android Development with Kotlin. https://leanpub.com/u/mmoskala He is currently working on the book series Kotlin for Developers. It will contain 3 books: 1. Kotlin Essentials (in reviewing process) 2. Functional Kotlin (finished) 3. Advanced Kotlin (in draft) In the previous book - Functional Kotlin, Marcin decided to add a special chapter concerning the Arrow topic. The cooperation was really awesome. You are the experts on Kotlin/Native during many conferences and publications that is why we would like to encourage you to write a special chapter that will be published in Advanced Kotlin book about January 2023. What do you think? If you are interested let me know, please here in DM or contact via kasia@kt.academy. Regards:)

Krystian

10/08/2022, 10:41 AM

I don't know if this fits this channel more or getting-started... I'm making a Raylib game framework binding to Kotlin Native and I'm trying to do a small Bunnymark benchmark to see how many bunnies (textures) can be spawned until the game hits 30FPS. Currently I'm hitting about 12.6k bunnies at 30/29fps (which is considerably lower than most languages e.g. Go hit 355500) and I'm unsure if there's anyway I can optimise the collections in native to squeeze all the juice possible? https://gist.github.com/Its-Kenta/5a42cb025281f252c87a987a184b69c7 any tips or code snippets on how to improve this would help me out a little.

Jeff Lockhart

10/11/2022, 6:19 PM

I've noticed a difference in behavior between Linux and Windows with throwing an exception in a

staticCFunction

called from C code. On Windows, the exception is propagated and I can catch it in Kotlin with a try/catch surrounding the call to the C code that calls the

staticCFunction

. But on Linux, this exception is instead caught by the underlying C code and returned in the error code from the C function as an "unknown C++ exception". I'm trying to determine if this difference in behavior is due to Kotlin/Native, the C library, or possibly the GCC/MinGW compilers. I'd like to have access to the original exception to keep the behavior consistent between the two platforms. Is there a difference between the way Kotlin/Native exceptions behave on Windows vs Linux?

Title

Jeff Lockhart

10/11/2022, 6:19 PM

I've noticed a difference in behavior between Linux and Windows with throwing an exception in a

staticCFunction

called from C code. On Windows, the exception is propagated and I can catch it in Kotlin with a try/catch surrounding the call to the C code that calls the

staticCFunction

I suppose as a workaround, I could perform the try/catch within the

staticCFunction

and save a global reference to a caught exception from within the

staticCFunction

to then access from outside the call if the "unknown C++ exception" error is encountered.

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