Help with kotlin-js

[ericvergnaud]

Hi @KvanTTT @bashor

I'm experimenting with Kotlin/Wasm and facing an issue you might be able to help with...

I've downloaded kotlinc 2.0.0-Beta3, and kotlinc-js -version shows the correct version.

When I run:

kotlinc-js src/main/kotlin/Test.kt -Xwasm -Xwasm-target=wasm -ir-output-name test.js -ir-output-dir out/wasm -kotlin-home /Users/ericvergnaud/Development/kotlinc

I get:

exception: java.lang.IllegalStateException: Class not found: kotlin/Float

How do I tell kotlin-js where to find builtins (I thought -kotlin-home was about that) ?
Btw where are they actually located ?

[lppedd]

IIRC you also need to provide the compiler the stdlib, e.g.:

-libraries={path-to}/kotlin-stdlib-wasm-js-{version}.jar (or .klib)

[bashor]

@lppedd is right, -libraries should be what you need.

[lppedd]

This is the command that will work:

kotlinc-js -ir-output-dir C:\Users\edoardo.luppi\wasm\out -ir-output-name test -Xir-produce-js -libraries kotlin-stdlib-wasm-js-2.0.0-Beta3.klib -Xwasm -Xwasm-target=wasm-js Test.kt

It's not mentioned anywhere and it's what made me rethink my life in the last hour (joking, almost), but -ir-output-dir must be absolute. God's know where my hundreds of attempts had their files outputted.

[ericvergnaud]

I can't seem to find that kotlin-stdlib-wasm-js-2.0.0-Beta3.klib file anywhere...

[lppedd]

@ericvergnaud Maven Central is the quickest solution, or locally under Gradle's cached files.

[ericvergnaud]

Aaahhh... I had to import it using:

        <dependency>
            <groupId>org.jetbrains.kotlin</groupId>
            <artifactId>kotlin-stdlib-wasm-js</artifactId>
            <type>klib</type>
            <version>${kotlin.version}</version>
        </dependency>

[ericvergnaud]

That resolves the cmd line errors, that said, despite using full paths, it doesn't seem to be generating anything...
Here is my cmd line:
kotlinc-js src/main/kotlin/Test.kt -Xwasm -Xwasm-target=wasm-js -ir-output-name stupid-name -ir-output-dir /Users/ericvergnaud/Development/out/wasm -kotlin-home /Users/ericvergnaud/Development/kotlinc -libraries /Users/ericvergnaud/.m2/repository/org/jetbrains/kotlin/kotlin-stdlib-wasm-js/2.0.0-Beta3/kotlin-stdlib-wasm-js-2.0.0-Beta3.klib

[lppedd]

@ericvergnaud try to use the same option positioning as mine. And you don't need -kotlin-home.

[KvanTTT]

I've also tried a first attempt but got the following exception:

exception: kotlin.UninitializedPropertyAccessException: lateinit property jsFrontEndResult has not been initialized
        at org.jetbrains.kotlin.ir.backend.js.ModulesStructure.getJsFrontEndResult(klib.kt:503)
        at org.jetbrains.kotlin.ir.backend.js.KlibKt.preparePsi2Ir(klib.kt:380)
        at org.jetbrains.kotlin.ir.backend.js.KlibKt.loadIr(klib.kt:199)
        at org.jetbrains.kotlin.ir.backend.js.KlibKt.loadIr$default(klib.kt:178)
        at org.jetbrains.kotlin.backend.wasm.CompilerKt.compileToLoweredIr(compiler.kt:61)
        at org.jetbrains.kotlin.cli.js.K2JsIrCompiler.doExecute(K2JsIrCompiler.kt:356)
        at org.jetbrains.kotlin.cli.js.K2JSCompiler.doExecute(K2JSCompiler.java:181)
        at org.jetbrains.kotlin.cli.js.K2JSCompiler.doExecute(K2JSCompiler.java:72)
        at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:104)
        at org.jetbrains.kotlin.cli.common.CLICompiler.execImpl(CLICompiler.kt:48)
        at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:101)
        at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:79)
        at org.jetbrains.kotlin.cli.common.CLITool.exec(CLITool.kt:43)
        at org.jetbrains.kotlin.cli.common.CLITool$Companion.doMainNoExit(CLITool.kt:180)
        at org.jetbrains.kotlin.cli.common.CLITool$Companion.doMainNoExit$default(CLITool.kt:173)
        at org.jetbrains.kotlin.cli.common.CLITool$Companion.doMain(CLITool.kt:167)
        at org.jetbrains.kotlin.cli.common.CLITool.doMain(CLITool.kt)
        at org.jetbrains.kotlin.cli.js.K2JSCompiler.main(K2JSCompiler.java:101)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:77)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:568)
        at org.jetbrains.kotlin.preloading.Preloader.run(Preloader.java:87)
        at org.jetbrains.kotlin.preloading.Preloader.main(Preloader.java:44)

I'm trying to figure out what the problem is.

[bashor]

It's not mentioned anywhere and it's what made me rethink my life in the last hour (joking, almost), but -ir-output-dir must be absolute. God's know where my hundreds of attempts had their files outputted.

🫣 Sorry for that. It's really wasn't intended/designed to be used from CLI, so no shortcuts and no user documentation.

[bashor]

It looks like a one-step compilation for K/Wasm is broken in K2.

You can for compiler work as K1 like below and it should work:

kotlinc-js -language-version 1.9 -Xir-produce-js -Xwasm -Xwasm-target=wasm-js -no-stdlib -libraries kotlin-stdlib-wasm-js-2.0.0-Beta3.klib -ir-output-dir out -ir-output-name=mymodule Simple.kt

[bashor]

For K2 you need to do two steps:

1: Produce a klib for sources

kotlinc-js -Xwasm -Xwasm-target=wasm-js -Xir-produce-klib-dir -no-stdlib -libraries kotlin-stdlib-wasm-js-2.0.0-Beta3.klib -ir-output-name mymodule -ir-output-dir mymodule-klib -Xir-per-module-output-name=mymodule Simple.kt

2: Generate an executable

kotlinc-js -Xwasm -Xwasm-target=wasm-js -Xir-produce-js -no-stdlib -libraries kotlin-stdlib-wasm-js-2.0.0-Beta3.klib -Xinclude=mymodule-klib -ir-output-dir out -ir-output-name=mymodule

[KvanTTT]

You can for compiler work as K1 like below and it should work:

Thanks, it really works with -language-version 1.9.

For K2 you need to do two steps:

It also works on my side.

[ericvergnaud]

Thanks @bashor ! Works here too !

The intermediate output is somewhat puzzling...:

Notice there is no test-klib and no test-module being generated by the first pass...

Also note that I had to specify full paths for -libraries and -ir-output-dir.

After changing suffixes to .ts and a few tweaks, I was able to run the generated wasm in Deno (attaching the file that works for me): test-module.uninstantiated.ts.zip

Leads me to a few questions:

• is the plan for K2 to generate a wasm in 1 pass ?
• will this be supported by kotlin-maven-plugin ? (we need this not for us but for our users)
• any plan (or interest) for generating typescript instead of javascript (or .d.ts files on top of the js) ?
• any plan (or interest) for supporting Deno (see working example attached) ?

[bashor]

Notice there is no test-klib and no test-module being generated by the first pass...

What is test-klib and test-module?
That you see on the picture is an unpacked klib file.

Also note that I had to specify full paths for -libraries and -ir-output-dir.

Might be OS specific bug, please file an issue.

After changing suffixes to .ts and a few tweaks, I was able to run the generated wasm in Deno

What kind of tweaks?
I think Deno should be able to run js, no need to rename.

is the plan for K2 to generate a wasm in 1 pass ?

No specific plan so far about CLI in general. Could you please provide more about your case.
Also, here is a related issue, feel free to vote and follow.

will this be supported by kotlin-maven-plugin ? (we need this not for us but for our users)

Do you ask about Kotlin Multiplatform or Kotlin/Wasm specifically? Anyway, feel free to file an issue.

any plan (or interest) for generating typescript instead of javascript (or .d.ts files on top of the js) ?

No plan for generating TS, but recently we added d.ts generation for exported declarations. It will be available in the upcoming 2.0.0-Beta4
What kind of benefit do you expect from TS instead of JS?

any plan (or interest) for supporting Deno (see working example attached)?

No specific plans for Deno support in Gradle plugin as we have for Node.js now, but if there is any issue with running generated code inside Deno we would happy to look into it. Please file an issue.

BTW, we have adhoc Deno setup in https://github.com/Kotlin/kotlin-wasm-examples/tree/main/wasi-example