I am trying to use a preview JDK in my Kotlin compiler confi

Question

I am trying to use a preview JDK in my Kotlin compiler config but I am getting a strange error Has anyone seen this before ```val JDK 21 PATH = home user sdkman candidates java 21 ea 6 open tasks withType lt org jetbrains kotlin gradle tasks UsesKotlinJavaToolchain gt configureEach kotlinJavaToolchain jdk use JDK 21 PATH JavaVersion VERSION 21 ``` ```Execution failed for task app compileKotlin gt Error while evaluating property compilerOptions jvmTarget of task app compileKotlin gt Failed to calculate the value of property jvmTarget gt Unknown Kotlin JVM target 21```

Gavin Ray · Answer

Specifically I am trying to build around the changes present in the `Foreign Function amp Memory API` since it s significantly changed since JDK19 LTS

Gavin Ray · Answer

Otherwise I would just use JDK19

tapchicoma · Answer

`JavaVersion VERSION 21` was added in Gradle 7 6

Gavin Ray · Answer

I m using Gradle 8 0

Gavin Ray · Answer

```distributionUrl=https services gradle org distributions gradle 8 0 rc 1 bin zip```

tapchicoma · Answer

sorry it is about Kotlin JVM Target Kotlin does not yet have jvm target 21 in it Probably better for now to use `JavaTarget VERSION 19` as task input but still point to JDK 21 location

Gavin Ray · Answer

Ohh I didn t know you could do that face palm

Gavin Ray · Answer

Ty that makes sense since the bytecode version does not need to be 21 just the JDK API right

tapchicoma · Answer

it is only in this specific case KGP does not check that JDK version is the same as provided one

Gavin Ray · Answer

This is a great trick to know

Gavin Ray · Answer

Oh wait hmm it still seems to fail with that thinking face ``` val JDK 21 PATH = home user sdkman candidates java 21 ea 6 open tasks withType lt org jetbrains kotlin gradle tasks UsesKotlinJavaToolchain gt configureEach kotlinJavaToolchain jdk use JDK 21 PATH JavaVersion VERSION 19 ```

Gavin Ray · Answer

I think maybe you just cannot use preview JDK s with kotlin + gradle

Gavin Ray · Answer

I think Maven too I remember trying once

tapchicoma · Answer

what is the failure

Gavin Ray · Answer

Same as before = ``` user MSI bustub kotlin $ gradlew compileKotlin gt Task app compileKotlin FAILED FAILURE Build failed with an exception What went wrong Execution failed for task app compileKotlin gt Error while evaluating property compilerOptions jvmTarget of task app compileKotlin gt Failed to calculate the value of property jvmTarget gt Unknown Kotlin JVM target 21```

Gavin Ray · Answer

```Caused by java lang IllegalArgumentException Unknown Kotlin JVM target 21 at org jetbrains kotlin gradle dsl JvmTarget$Companion fromTarget JvmTarget kt 26 at org jetbrains kotlin gradle tasks DefaultKotlinJavaToolchain$wireJvmTargetToToolchain$1$1 invoke DefaultKotlinJavaToolchain kt 78 at org jetbrains kotlin gradle tasks DefaultKotlinJavaToolchain$wireJvmTargetToToolchain$1$1 invoke DefaultKotlinJavaToolchain kt 70 at org jetbrains kotlin gradle tasks DefaultKotlinJavaToolchain$sam$org gradle api Transformer$0 transform DefaultKotlinJavaToolchain kt ```

tapchicoma · Answer

strange it should pickup `JavaVersion VERSION 19` for Jvm Target

tapchicoma · Answer

do you have a repro

Gavin Ray · Answer

Gavin Ray · Answer

Sure I can make a repro one moment

Gavin Ray · Answer

bustub kotlin zip

Gavin Ray · Answer

You will have to install Java 21ea build 6 with `sdk install java 21 ea 6 open` and replace the path constant

tapchicoma · Answer

hm I only see this error ```Execution failed for task app compileKotlin gt compileJava task current target is 11 and compileKotlin task current target is 19 jvm target compatibility should be set to the same Java version Consider using JVM toolchain <https kotl in gradle jvm toolchain>``` but it is possible to disable via `kotlin jvm target validation mode=ignore`

tapchicoma · Answer

after it I see just a normal compilation errors

Gavin Ray · Answer

That s so strange something must be up on my system

Gavin Ray · Answer

Thanks for looking into it

Gavin Ray · Answer

Out of curiosity does setting the JDK toolchain to Java 21 also work for you thinking face

Gavin Ray · Answer

```java toolchain languageVersion set JavaLanguageVersion of 21 ```

tapchicoma · Answer

yes I ve used the same JDK from SDKMAN as in example

Gavin Ray · Answer

Does it compile with just that as well

tapchicoma · Answer

nope ```App kt 12 26 Unresolved reference MemorySession```

tapchicoma · Answer

and so on with the same error

Gavin Ray · Answer

ahh okay so that means it does work those were removed

Gavin Ray · Answer

since it s not gradle error

Gavin Ray · Answer

man something is VERY broke with my gradle

Gavin Ray · Answer

maybe something strange with Gradle Windows WSL2

Gavin Ray · Answer

Thank you so much for looking into it I very much appreciate your time pray