KSTypeParameter#bounds returns <ERROR TYPE> when the bounds is another type parameter

[bcorso]

For example:

// MyClass.java
class MyClass {
  static <T1, T2 extends T1> T2 method(T1 input) {
    return null; 
  }
}

Now, say we try to inspect the bounds of the method return type, T2:

  val t2: KSType = method.returnType.resolve()
  val t2Declaration: KSTypeParameter = t2.declaration as KSTypeParameter
  val t2Bounds: List<KSType> = t2Declaration.bounds.map { it.resolve() }.toList()
  println("{DECLARATION: $t2Declaration, BOUNDS: $t2Bounds}")

This results in {DECLARATION: T2, BOUNDS: [<ERROR TYPE>]}

Interestingly, if we get the matching KSTypeParameter from the parent declaration's type parameters it contains the correct bounds, e.g.

  val t2: KSType = method.returnType.resolve()
  val t2Declaration: KSTypeParameter =
      t2.declaration.parentDeclaration.typeParameters
          .filter { it.name =(t2.declaration as KSTypeParameter).name }
          .single()
  val t2Bounds: List<KSType> = t2Declaration.bounds.map { it.resolve() }.toList()
  println("{DECLARATION: $t2Declaration, BOUNDS: $t2Bounds}")

This results in {DECLARATION: T2, BOUNDS: [(T1..T1?)]}