I am adding a kotlin multiplatform module to our Java-Spring monolith. It compiles just fine, I can ...

# multiplatform

[audax]

I am adding a kotlin multiplatform module to our Java-Spring monolith. It compiles just fine, I can use code from the commonMain source root.
However: IntelliJ Idea doesn't like this stuff at all. I've attached the build file for the shared module. I've added the module in the main module with implementation project(":shared") and I've also added the 2 libraries.

implementation("org.jetbrains.kotlinx:kotlinx-datetime:${project.kotlinxDatetime}")
implementation("com.ionspin.kotlin:bignum:${project.bignum}")

I've also tried to export the kotlin-mpp libraries by using the "api"-configuration instead of "implementation" in the shared module.

The monolith is Java only.

The error message in the IDE is:
Incompatible types. Found: 'kotlinx.datetime.LocalDate', required: 'kotlinx.datetime.LocalDate'

build.gradle.kts

[audax]

When I add the kotlin plugin and add the same code (converted to kotlin of course) to a kotlin file, it works out just fine.

[audax]

I only get the error in a java file, and only in the IDE. The IDE is set to use gradle for building the project and the test is green.

[CLOVIS]

If you want downstream modules to access the dependencies, they should be declared with api .

If this exception happened in real code, I would point to classloader magic, maybe you have a framework that does weird things with it?

However, if it only happens in the IDE, there's a chance reindexing everything will solve it

[audax]

I've switched back to api and reindexing, even removing .idea didn't help. 😞
The error is just in IntelliJ Idea, not when I run the test.

[CLOVIS]

If you can share the project or create a reproducer, create an issue

[audax]

I guess I'll have to build a minimal example and hope that I can reproduce the issue.

[audax]

I've made the example: https://github.com/audax/kotlin-mpp-java-type-error
I have also isolated the error: As soon as I add any JS target, the IDE shows an error in JavaStuff.java.

[audax]

https://youtrack.jetbrains.com/issue/KTIJ-30633/Incompatible-types-error-when-using-kotlin-multiplatform-module-in-Java