Kotlin LayoutSpec files not found by the Processor

• I have searched existing issues and this is not a duplicate

Issues and Steps to Reproduce

I have a simple LayoutSpec that returns a single Text item. Defining it in Kotlin:

@LayoutSpec
class CurrentWeatherTopSpec {

    companion object {
        @JvmStatic
        @OnCreateLayout
        fun onCreateLayout(c: ComponentContext): ComponentLayout {
            return Column.create(c)
                    .child(Row.create(c)
                            .child(
                                    Text.create(c)
                                            .text("Current Weather")
                                            .build()
                            ).build())
                    .build()
        }
    }
}

Nothing gets generated. No CurrentWeatherTopLayout file created. If I create the same code in Java, it gets generated:

@LayoutSpec
class CurrentWeatherTopSpec {

    @OnCreateLayout
    static ComponentLayout onCreateLayout(ComponentContext context) {
        return Column.create(c)
                    .child(Row.create(c)
                            .child(
                                    Text.create(c)
                                            .text("Current Weather")
                                            .build()
                            ).build())
                    .build();
    }
}

Expected Behavior

I’d expect the corresponding generated component class.

Is this a bug or something I am doing wrong here? I guess my real question here is what does Litho use to determine if the class is a proper @LayoutSpec. Also FYI im using kapt and using it for java files works fine, but when in Kotlin the processor does not work.

[ubuntudroid]

Okay, got it working as well. I created a minimalistic project on Github pointing out Kotlin specific adaptions: https://github.com/ubuntudroid/litho-kotlin.

[grandstaish]

Legacy kapt used to convert kotlin code into stub class files, which in turn were run through the javac annotation processing tool. One of the (many) limitations of this idea is that class files don’t have any information about method parameter names, which this library depends on. Lots of information in this article: https://medium.com/@workingkills/pushing-the-limits-of-kotlin-annotation-processing-8611027b6711