Is there a good [formal] way for me to compare a reference to a declaration?

what are the values in those and how do you want to compare them?. I’d need some code to see what you are trying to achieve here.

data class Window<T>(
        val size: Int,
        val elements: MutableList<T>) {
    init {
        watch(elements).then {
            while (elements.size > size) elements.removeAt(0)
        }
    }
}

I crawl through the code (example above) and record all of the declarations. Then I search for any watch methods and see what is declared as dependencies. I'd like to associate that reference with the correct declaration (I have a list of registered elements)

So in your case:

KtProperty : val elements: MutableList<T>

yeah

where elements appears inside

watch(elements)

figured as much

let me take a look at the compiler docs one sec

am I paying a higher cost in compilation

yes, you are analyzing twice but if you know exactly where to and your gened files to analyze are small it may not be significant

ah sure

if you are passing it to the Kotlin Core Environment try with

org.jetbrains.kotlin.config.CompilerConfiguration#EMPTY