'sealed' is now not 'final' by default + related code changes #KT-10266 Fixed

compiler/testData/diagnostics/tests/sealed/NonExhaustiveWhenWithAdditionalCase.kt

@@ -15,7 +15,7 @@ sealed class Sealed(val x: Int) {
 fun foo(s: Sealed): Int {
     return <!NO_ELSE_IN_WHEN!>when<!>(s) {
         is Sealed.First -> 1
-        !is <!INCOMPATIBLE_TYPES!>Sealed.ITuple<!> -> 0
+        !is Sealed.ITuple -> 0
         // else required
     }
 }

compiler/testData/diagnostics/tests/sealed/WithInterface.kt

@@ -0,0 +1,10 @@
+interface Parent
+interface Child : Parent
+
+sealed class Page : Parent {
+  object One : Page(), Child
+  object Two : Page(), Child
+}
+
+// Ok: page is a Parent so it can be easily a Child
+fun test(page: Page): Boolean = page is Child

compiler/testData/diagnostics/tests/sealed/WithInterface.txt

@@ -0,0 +1,36 @@
+package
+
+public fun test(/*0*/ page: Page): kotlin.Boolean
+
+public interface Child : Parent {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}
+
+public sealed class Page : Parent {
+    private constructor Page()
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+
+    public object One : Page, Child {
+        private constructor One()
+        public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+
+    public object Two : Page, Child {
+        private constructor Two()
+        public open override /*2*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+        public open override /*2*/ /*fake_override*/ fun hashCode(): kotlin.Int
+        public open override /*2*/ /*fake_override*/ fun toString(): kotlin.String
+    }
+}
+
+public interface Parent {
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}

compiler/testData/diagnostics/tests/smartCasts/openInSealed.kt

@@ -0,0 +1,8 @@
+sealed class My(open val x: Int?) {
+    init {
+        if (x != null) {
+            // Should be error: property is open
+            <!SMARTCAST_IMPOSSIBLE!>x<!>.hashCode()
+        }
+    }
+}

compiler/testData/diagnostics/tests/smartCasts/openInSealed.txt

@@ -0,0 +1,9 @@
+package
+
+public sealed class My {
+    private constructor My(/*0*/ x: kotlin.Int?)
+    public open val x: kotlin.Int?
+    public open override /*1*/ /*fake_override*/ fun equals(/*0*/ other: kotlin.Any?): kotlin.Boolean
+    public open override /*1*/ /*fake_override*/ fun hashCode(): kotlin.Int
+    public open override /*1*/ /*fake_override*/ fun toString(): kotlin.String
+}