I'm trying to understand the difference between a Kotlin: - target - compilation - sourceSet Somethi...

# gradle

[mbonnin]

I'm trying to understand the difference between a Kotlin:
• target
• compilation
• sourceSet
Something that has bugged me for a while is that I would intuitively expect the dependencies to be set on "compilations" and not "sourceSets" but I've never really taken the time to dig into this. Does anyone have any pointers?

[hho]

It's the source code that has dependencies – therefore dependencies are defined on a source set. At least that's how I understood it, so far…
I haven't heard of "target" or "compilation" as named Gradle concepts yet, could you please explain a little bit more, what you mean?

[mbonnin]

Can't explain too much since I'm also making my way through this but you can do this:

// add JVM target
val jvmTarget = kotlin.jvm() 
// add a compilation to the JVM target
val myCompilation = jvmTarget.compilations.create("myCompilation")
// get the default source set for this comilation
myCompilation.defaultSourceSet

[mbonnin]

source code that has dependencies

At the end you need to pass those dependencies to the compiler and compile a "set" of "sourceSets" altogether? Or at least this is my mental model

[ephemient]

as far as I understand,
target = environment where the compiled code is expected to run
compilation = unit of work for the compiler
source set = 1 leaf per compilation, but with some number of parents

[mbonnin]

Ah, so a compilation takes only one leaf source set and then gets the parents through dependsOn and can get the dependencies as it goes 👍 Makes sense, thanks!

[mbonnin]

Can I create a compilation without creating a target? If I want to just run some tests but don't care about a framework or jar file

[ephemient]

no, but you can create additional compilations within a target

[tapchicoma]

since Kotlin 1.9.20 consider 1 compilation that will compile one defaultKotlinSourceSet via one compilation task.

Indeed it could include additional sources from shared KotlinSourceSet.

KotlinTarget may contain 1 or more KotlinCompilation. Usually it is two - production code and test code compilations.

[mbonnin]

Thanks! If I create a new compilation on the jvm target, will its default source set depend on commonMain by default or do I have to wire that myself?

[tapchicoma]

as far as I see - you need to do it manually

[mbonnin]

Thanks, I think it's better this way for my use case actually.

[tapchicoma]

btw what is your use-case for creating additional compilation?

[mbonnin]

Currently digging into this

[mbonnin]

We have some integration tests of the Apollo plugin where we want to substitute the Kotlin models for the equivalent Java models

[mbonnin]

So if the new default sourceSet was to depend on commonMain , we would end up with duplicate symbols because the Kotlin models are configured there already