FIR: introduce not implemented checker

core/compiler.common.jvm/src/org/jetbrains/kotlin/descriptors/java/JavaVisibilities.kt

@@ -8,6 +8,7 @@ package org.jetbrains.kotlin.descriptors.java
 import org.jetbrains.kotlin.descriptors.EffectiveVisibility
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.descriptors.Visibility
+import org.jetbrains.kotlin.name.FqName
 
 object JavaVisibilities {
     object PackageVisibility : Visibility("package", isPublicAPI = false) {
@@ -32,6 +33,10 @@ object JavaVisibilities {
         override fun customEffectiveVisibility(): EffectiveVisibility? {
             return EffectiveVisibility.PackagePrivate
         }
+
+        override fun visibleFromPackage(fromPackage: FqName, myPackage: FqName): Boolean {
+            return fromPackage == myPackage
+        }
     }
 
     object ProtectedStaticVisibility : Visibility("protected_static", isPublicAPI = true) {

core/compiler.common/src/org/jetbrains/kotlin/descriptors/Visibility.kt

@@ -5,6 +5,8 @@
 
 package org.jetbrains.kotlin.descriptors
 
+import org.jetbrains.kotlin.name.FqName
+
 abstract class Visibility protected constructor(
     val name: String,
     val isPublicAPI: Boolean
@@ -27,4 +29,6 @@ abstract class Visibility protected constructor(
 
     // Should be overloaded in Java visibilities
     open fun customEffectiveVisibility(): EffectiveVisibility? = null
+
+    open fun visibleFromPackage(fromPackage: FqName, myPackage: FqName): Boolean = true
 }