Hello, I am trying to write a compiler plugin which generates a new class. So far I have written a c...

# compiler

[Karim Houari]

Hello, I am trying to write a compiler plugin which generates a new class. So far I have written a class extending IrGenerationExtension and can see the generated .class file as a result. I then created a .kt file which references that class, but when trying to compile with kotlinc (the .class file is on the classpath with -cp) I get unresolved reference. I opened the .class file in a decompiler and when comparing it to a .class file that was created from a .kt file, I see my generated .class file has missing d1 and d2 metadata properties, plus k = 3, whereas the other class has k = 1 . Does this matter? Is there any other reason why this might not be working?

[Big Chungus]

Not the answer you're looking for, but if you're only generating new code, I'd strongly recommend going with #ksp rather than direct compiler plugin. It does a lot of heavy lifting for you.

[Karim Houari]

Thank you for your reply, I'm certainly open to using ksp if it helps. Would it allow me to do the following?
Start with this class

class Foo {
    val abc = "abc"

    fun hello() = "Hello World"
}

and generate a new class with just the hello function?

class Bar {
    fun hello(name: String) = "Hello World"
}

My understanding was ksp does not have the details of function bodies

[Big Chungus]

Ah, no. Ksp only has access to the api, not the bodies

[Big Chungus]

But can't you somehow delegate the implementation to initial method?

[Karim Houari]

Can I change the function signature in ksp? I don't need to modify the function body but I need to add parameters or change their types

[Big Chungus]

No, ksp has 2 main limitations:
• Existing sources are read-only so you can only generete new stuff
• It can only see the API, but not the implementation bodies

[Big Chungus]

You might want to look at #arrow-meta as well. That one is a lot closer to being actual compiler plugin.

[dmitriy.novozhilov]

https://kotlinlang.slack.com/archives/CJ699L62W/p1669725866579599?thread_ts=1669719907.683379&cid=CJ699L62W

[Big Chungus]

Sorry for pushing you sideways. It's just that compiler API is so unstable now that I always try to avoid interracting with it directly.

[Karim Houari]

Yep that's understandable and no problem, I appreciate your advice.

[Johannes Barop]

@Karim Houari: I think you need to move the declaration of the class and its methods into an implementation of SyntheticResolveExtension. The IrGenerationExtension implementation then only adds the bodies.

BTW: You can reference the SyntheticResolveExtension implementation in an IntelliJ plugin and then Inntelij will also know about the generated classes.