Don't suggest to move type to separate file for sealed classes

So #KT-23321 Fixed

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

@@ -24,6 +24,10 @@ import com.intellij.openapi.fileEditor.FileEditorManager
 import com.intellij.openapi.util.TextRange
 import com.intellij.refactoring.move.MoveCallback
 import com.intellij.refactoring.util.CommonRefactoringUtil
+import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.Modality
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
+import org.jetbrains.kotlin.idea.caches.resolve.resolveToDescriptorIfAny
 import org.jetbrains.kotlin.idea.intentions.SelfTargetingRangeIntention
 import org.jetbrains.kotlin.idea.core.moveCaret
 import org.jetbrains.kotlin.idea.refactoring.createKotlinFile
@@ -35,16 +39,24 @@ import org.jetbrains.kotlin.psi.KtFile
 import org.jetbrains.kotlin.psi.KtObjectDeclaration
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import org.jetbrains.kotlin.resolve.BindingContext
+import org.jetbrains.kotlin.resolve.lazy.BodyResolveMode
 
 class MoveDeclarationToSeparateFileIntention :
-        SelfTargetingRangeIntention<KtClassOrObject>(KtClassOrObject::class.java, "Move declaration to separate file"),
-        LowPriorityAction {
+    SelfTargetingRangeIntention<KtClassOrObject>(KtClassOrObject::class.java, "Move declaration to separate file"),
+    LowPriorityAction {
     override fun applicabilityRange(element: KtClassOrObject): TextRange? {
         if (element.name == null) return null
         if (element.parent !is KtFile) return null
         if (element.hasModifier(KtTokens.PRIVATE_KEYWORD)) return null
         if (element.containingKtFile.declarations.size == 1) return null
 
+        if (element.resolveToDescriptorIfAny()?.sealedSubclasses?.isNotEmpty() == true) return null
+        if (element.superTypeListEntries.any {
+                val superType = it.analyze(BodyResolveMode.PARTIAL)[BindingContext.TYPE, it.typeReference]
+                (superType?.constructor?.declarationDescriptor as? ClassDescriptor)?.modality == Modality.SEALED
+            }) return null
+
         val keyword = when (element) {
             is KtClass -> element.getClassOrInterfaceKeyword()
             is KtObjectDeclaration -> element.getObjectKeyword()
@@ -76,15 +88,17 @@ class MoveDeclarationToSeparateFileIntention :
 
             // If automatic move is not possible, fall back to full-fledged Move Declarations refactoring
             ApplicationManager.getApplication().invokeLater {
-                MoveKotlinTopLevelDeclarationsDialog(project,
-                                                     setOf(element),
-                                                     packageName.asString(),
-                                                     directory,
-                                                     targetFile as? KtFile,
-                                                     true,
-                                                     true,
-                                                     true,
-                                                     null).show()
+                MoveKotlinTopLevelDeclarationsDialog(
+                    project,
+                    setOf(element),
+                    packageName.asString(),
+                    directory,
+                    targetFile as? KtFile,
+                    true,
+                    true,
+                    true,
+                    null
+                ).show()
             }
             return
         }
@@ -92,18 +106,18 @@ class MoveDeclarationToSeparateFileIntention :
             createKotlinFile(targetFileName, directory, packageName.asString())
         }
         val descriptor = MoveDeclarationsDescriptor(
-                project = project,
-                elementsToMove = listOf(element),
-                moveTarget = moveTarget,
-                delegate = MoveDeclarationsDelegate.TopLevel,
-                searchInCommentsAndStrings = false,
-                searchInNonCode = false,
-                moveCallback = MoveCallback {
-                    val newFile = directory.findFile(targetFileName) as KtFile
-                    val newDeclaration = newFile.declarations.first()
-                    NavigationUtil.activateFileWithPsiElement(newFile)
-                    FileEditorManager.getInstance(project).selectedTextEditor?.moveCaret(newDeclaration.startOffset + originalOffset)
-                }
+            project = project,
+            elementsToMove = listOf(element),
+            moveTarget = moveTarget,
+            delegate = MoveDeclarationsDelegate.TopLevel,
+            searchInCommentsAndStrings = false,
+            searchInNonCode = false,
+            moveCallback = MoveCallback {
+                val newFile = directory.findFile(targetFileName) as KtFile
+                val newDeclaration = newFile.declarations.first()
+                NavigationUtil.activateFileWithPsiElement(newFile)
+                FileEditorManager.getInstance(project).selectedTextEditor?.moveCaret(newDeclaration.startOffset + originalOffset)
+            }
         )
 
         MoveKotlinDeclarationsProcessor(descriptor).run()

idea/testData/intentions/moveDeclarationToSeparateFile/.intention

@@ -0,0 +1 @@
+org.jetbrains.kotlin.idea.refactoring.move.moveDeclarations.MoveDeclarationToSeparateFileIntention

idea/testData/intentions/moveDeclarationToSeparateFile/extendSealed.kt

@@ -0,0 +1,3 @@
+// IS_APPLICABLE: false
+sealed class A
+class B<caret> : A()

idea/testData/intentions/moveDeclarationToSeparateFile/sealed.kt

@@ -0,0 +1,3 @@
+// IS_APPLICABLE: false
+sealed class A<caret>
+class B : A()

idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java

@@ -11824,6 +11824,27 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
         }
     }
 
+    @TestMetadata("idea/testData/intentions/moveDeclarationToSeparateFile")
+    @TestDataPath("$PROJECT_ROOT")
+    @RunWith(JUnit3RunnerWithInners.class)
+    public static class MoveDeclarationToSeparateFile extends AbstractIntentionTest {
+        public void testAllFilesPresentInMoveDeclarationToSeparateFile() throws Exception {
+            KotlinTestUtils.assertAllTestsPresentByMetadata(this.getClass(), new File("idea/testData/intentions/moveDeclarationToSeparateFile"), Pattern.compile("^([\\w\\-_]+)\\.(kt|kts)$"), TargetBackend.ANY, true);
+        }
+
+        @TestMetadata("extendSealed.kt")
+        public void testExtendSealed() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/moveDeclarationToSeparateFile/extendSealed.kt");
+            doTest(fileName);
+        }
+
+        @TestMetadata("sealed.kt")
+        public void testSealed() throws Exception {
+            String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/moveDeclarationToSeparateFile/sealed.kt");
+            doTest(fileName);
+        }
+    }
+
     @TestMetadata("idea/testData/intentions/moveLambdaInsideParentheses")
     @TestDataPath("$PROJECT_ROOT")
     @RunWith(JUnit3RunnerWithInners.class)