I would like to create a new top level class in FIR whenever I see an interface that extends another...

# compiler

[Tóth István Zoltán]

I would like to create a new top level class in FIR whenever I see an interface that extends another interface. Like this:

interface Test : Service

And the class I would like to generate:

class Test$Impl : Test { }

I tried to figure out how to use FirDeclarationGenerationExtension for this but I couldn't. getTopLevelClassIds is called very early, and I don't know how to figure out which interfaces should I process.

Any pointers? Thanks in advance.

[Javier]

I think you need to use annotations for this.

[Javier]

If nothing has changed, everything around the generation extension needs annotations

[Tóth István Zoltán]

Thanks, I was afraid that's the case. I'll change to annotations. I really don't like them, they make the code hard to read and move information to the wrong place, but this is how it is.

[Tóth István Zoltán]

On the other hand I really don't see what's the difference between an annotation and an interface at this point. I guess I could just figure out how the compiler checks the annotations and do the same for the interfaces. Maybe it's too much work...

[dmitriy.novozhilov]

I recently described the reasoning behind this design

[Tóth István Zoltán]

Thanks, the description of phases in that description is very useful.

The problem is that getTopLevelClassIds is called very early and I can't figure out how to collect the classes I want to process.

In ExternalClassGenerator of the fir plugin prototype a predicate is used but when I tried it I got an empty result. I also checked the cache it uses with debugger and it was empty.

From FirDeclarationGenerationExtension:

• the getTopLevelClassIds method is called AFTER the SUPERTYPES phase
• the generateTopLevelClassLikeDeclaration method is called ON the SUPERTYPES phase
I don't understand how would this work.

[dmitriy.novozhilov]

From `FirDeclarationGenerationExtension`:

• the getTopLevelClassIds method is called AFTER the SUPERTYPES phase

• the generateTopLevelClassLikeDeclaration method is called ON the SUPERTYPES phase

It's a problem in the documentation. This comment about "after supertypes" is about methods about callables
getTopLevelClassIds will be called on the supertypes stage

[dmitriy.novozhilov]

The problem is that getTopLevelClassIds is called very early and I can't figure out how to collect the classes I want to process.

Only using predicates

In ExternalClassGenerator of the fir plugin prototype a predicate is used but when I tried it I got an empty result. I also checked the cache it uses with debugger and it was empty.

That's strange
Did you register your predicates in the extension itself?

[Tóth István Zoltán]

Yes, I think:

override fun FirDeclarationPredicateRegistrar.registerPredicates() {
        register(PREDICATE)
    }

[dmitriy.novozhilov]

Are your annotations listed here during debugging?

[Tóth István Zoltán]

Yes:

[Tóth István Zoltán]

As I see it calls FirPredicateBasedProviderImpl.kt but the cache is empty. I'm using the standard plugin test framework btw.