[BUG] Resolution error with proofs plugin when using certain types from other packages.

[Sintrastes]

Describe the bug
When using @Given annotations with the arrow proofs compiler plugin, and using an @Given context that references certain classes in a different package from where the @Given annotations are being used, sometimes the generated code will have unresolved reference errors.

To Reproduce

Compile a project with the following two files:

// test.kt

package test
import arrow.Context
import test.mod.Functor

@Context
@Retention(AnnotationRetention.RUNTIME)
@Target(
  AnnotationTarget.CLASS,
  AnnotationTarget.FUNCTION,
  AnnotationTarget.PROPERTY,
  AnnotationTarget.VALUE_PARAMETER
)


@MustBeDocumented
annotation class Given
inline fun <A> given(@Given identity: A): A = identity

interface Hk<F,A>

object ForListK

data class ListK<A>(val list: List<A>): Hk<ForListK, A>

fun <A> Hk<ForListK, A>.fix() = this as ListK<A>

fun <A> List<A>.k() = ListK(this)

@Given
internal val listFunctor = object: Functor<ForListK> {
  override fun <A, B> Hk<ForListK, A>.fmap(f: (A) -> B): Hk<ForListK, B> {
    return ListK(fix().list.map(f))
  }
}

fun <F> fmapPlusTwo(xs: Hk<F,Int>, @Given functor: Functor<F>): Hk<F,Int> = with(functor) {
    xs.fmap { it + 2 }
}

fun main() {
  val res = fmapPlusTwo(listOf(1,2,3).k())
  println("$res")
}

// mod/functor.kt
import test.Hk

interface Functor<F> {
  fun <A, B> Hk<F, A>.fmap(f: (A) -> B): Hk<F, B>
}

After compiling a project with these two files, the generated code for the fmapPlusTwo method looks like this:

package test
@arrow.CompileTime
internal fun <F>   fmapPlusTwo(xs: Hk<F, Int>, @test.Given functor: Functor<F> = TODO("Compile time replaced"), unit: Unit = Unit): Hk<F, Int> = 
  fmapPlusTwo(xs, functor) 

with an unresolved reference error for Functor.

Expected behavior
The above examples should compile successfully.

Environment (please complete the following information):

• Kotlin version: 1.6.0
• Kotlin Intellij IDEA plugin version: Not sure
• Intellij IDEA version: 2021.3

Additional context
It's not entirely clear to me yet exactly when this issue occurs. This didn't seem to be an issue for another example where the type I imported from a different module was just a simple (i.e. not generic) type -- so perhaps the issue arises with generics.

I believe this issue could be solved by making sure to always use fully qualified names for all generated code.

[Sintrastes]

@raulraja I'd be happy to look at this one if you have some suggestion for where I might look.

[raulraja]

Hi @Sintrastes , I believe your proposed fix can be applied here https://github.com/arrow-kt/arrow-meta/blob/main/plugins/proofs/proofs-plugin/src/main/kotlin/arrow/meta/plugins/proofs/phases/quotes/GenerateGivenSupportingFunctions.kt#L76-L103

https://github.com/arrow-kt/arrow-meta/blob/main/plugins/proofs/proofs-plugin/src/main/kotlin/arrow/meta/plugins/proofs/phases/quotes/GenerateGivenSupportingFunctions.kt#L121

[Sintrastes]

@raulraja Thanks for the suggestion.

Unfortunately, it looks like this is not as easy of a fix as I thought. This may still be part of the problem, but it actually looks like when the plugin tries to look up given instances for a generic class that is not defined in the current package, it can't actually find those instances.

I have a fork here where I've added a test to try and catch this issue -- and there I am actually getting this error before the unresolved reference error I was getting before:

error found: /tmp/Kotlin-Compilation14835146631616204679/sources/Test.kt: (29, 27): 
    There is no Proof for this type [ERROR : Semigroup] to resolve this call. Either define 
      a corresponding GivenProof or provide an evidence explicitly at this call-site.

[Sintrastes]

Although, for what it's worth, whenever I try to use it.type.getJetTypeFqName(true) instead of it.type -- it looks like all of the given tests fail with a pretty hefty BackendException that I don't understand in the slightest.

[raulraja]

That second error [ERROR : Semigroup] indicates an error type and probably just means that Semigroup was not resolved so maybe also missing the import or fqname for it.