Move: Check if sealed class is moved with its subclasses

#KT-22769 Fixed

idea/src/org/jetbrains/kotlin/idea/refactoring/move/moveDeclarations/moveConflictUtils.kt

@@ -59,6 +59,7 @@ import org.jetbrains.kotlin.renderer.ParameterNameRenderingPolicy
 import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.DescriptorUtils
 import org.jetbrains.kotlin.resolve.descriptorUtil.getImportableDescriptor
+import org.jetbrains.kotlin.resolve.descriptorUtil.getSuperClassNotAny
 import org.jetbrains.kotlin.resolve.descriptorUtil.isSubclassOf
 import org.jetbrains.kotlin.resolve.jvm.platform.JvmPlatform
 import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
@@ -451,6 +452,38 @@ class MoveConflictChecker(
         }
     }
 
+    private fun checkSealedClassMove(conflicts: MultiMap<PsiElement, String>) {
+        val visited = HashSet<PsiElement>()
+        for (elementToMove in elementsToMove) {
+            if (!visited.add(elementToMove)) continue
+            if (elementToMove !is KtClassOrObject) continue
+
+            val rootClass: KtClass
+            val rootClassDescriptor: ClassDescriptor
+            if (elementToMove is KtClass && elementToMove.isSealed()) {
+                rootClass = elementToMove
+                rootClassDescriptor = rootClass.resolveToDescriptorIfAny() as? ClassDescriptor ?: return
+            }
+            else {
+                val classDescriptor = elementToMove.resolveToDescriptorIfAny() as? ClassDescriptor ?: return
+                val superClassDescriptor = classDescriptor.getSuperClassNotAny() ?: return
+                if (superClassDescriptor.modality != Modality.SEALED) return
+                rootClassDescriptor = superClassDescriptor
+                rootClass = rootClassDescriptor.source.getPsi() as? KtClass ?: return
+            }
+
+            val subclasses = rootClassDescriptor.sealedSubclasses.mapNotNull { it.source.getPsi() }
+            if (subclasses.isEmpty()) continue
+
+            visited.add(rootClass)
+            visited.addAll(subclasses)
+
+            if (isToBeMoved(rootClass) && subclasses.all { isToBeMoved(it) }) continue
+
+            conflicts.putValue(rootClass, "Sealed class '${rootClass.name}' must be moved with all its subclasses")
+        }
+    }
+
     fun checkAllConflicts(
             externalUsages: MutableSet<UsageInfo>,
             internalUsages: MutableSet<UsageInfo>,
@@ -461,6 +494,7 @@ class MoveConflictChecker(
         checkVisibilityInUsages(externalUsages, conflicts)
         checkVisibilityInDeclarations(conflicts)
         checkInternalMemberUsages(conflicts)
+        checkSealedClassMove(conflicts)
     }
 }