[Commonizer] Don't write protecteds of final classes into the metadata

They are inaccessible and provoke an error.

See: `ClassifierCommonizationFromSourcesTest#testConstructors`.

^KT-28850

Author: lunakoly

native/commonizer/src/org/jetbrains/kotlin/commonizer/metadata/CirTreeSerializer.kt

@@ -161,23 +161,35 @@ private class CirTreeSerializationVisitor(
             nestedClass
         }
 
+        // `protected` members are prohibited inside final expect classes, as they can't be accessed.
+        fun <T> T.takeIfNeeded(visibility: Visibility): T? = when {
+            cirClass.modality == org.jetbrains.kotlin.descriptors.Modality.FINAL && visibility == Visibility.PROTECTED -> null
+            else -> this
+        }
+
         val nestedConstructors: Collection<KmConstructor> = node.constructors.mapNotNull { (constructorKey, constructorNode) ->
             val constructorContext = classContext.callableMemberContext(DEFAULT_CONSTRUCTOR_NAME, classTypeParametersCount)
-            val constructor: KmConstructor = constructorNode.accept(this, constructorContext)?.cast() ?: return@mapNotNull null
+            val constructor: KmConstructor = (constructorNode.accept(this, constructorContext) as? KmConstructor)
+                ?.let { it.takeIfNeeded(it.visibility) }
+                ?: return@mapNotNull null
             statsCollector?.logClassConstructor(constructor, constructorContext, constructorKey)
             constructor
         }
 
         val nestedFunctions: Collection<KmFunction> = node.functions.mapNotNull { (functionKey, functionNode) ->
             val functionContext = classContext.callableMemberContext(functionKey.name, classTypeParametersCount)
-            val function: KmFunction = functionNode.accept(this, functionContext)?.cast() ?: return@mapNotNull null
+            val function: KmFunction = (functionNode.accept(this, functionContext) as? KmFunction)
+                ?.let { it.takeIfNeeded(it.visibility) }
+                ?: return@mapNotNull null
             statsCollector?.logFunction(function, functionContext, functionKey)
             function
         }
 
         val nestedProperties: Collection<KmProperty> = node.properties.mapNotNull { (propertyKey, propertyNode) ->
             val propertyContext = classContext.callableMemberContext(propertyKey.name, classTypeParametersCount)
-            val property: KmProperty = propertyNode.accept(this, propertyContext)?.cast() ?: return@mapNotNull null
+            val property: KmProperty = (propertyNode.accept(this, propertyContext) as? KmProperty)
+                ?.let { it.takeIfNeeded(it.visibility) }
+                ?: return@mapNotNull null
             statsCollector?.logProperty(propertyContext, propertyKey, propertyNode)
             property
         }

native/commonizer/testData/classifierCommonization/constructors/commonized/common/package_root.kt

@@ -10,9 +10,7 @@ expect class A3
 expect class A4
 expect class A5
 
-expect class B1 protected constructor(text: String) {
-    protected constructor(number: Int)
-}
+expect class B1
 
 expect class B2
 expect class B3