[FE] Prohibit inheritance of sealed classes in different module

KT-20423

compiler/testData/diagnostics/tests/sealed/interfaces/inheritorInDifferentModule.fir.kt

@@ -0,0 +1,17 @@
+// ISSUE: KT-20423
+// !LANGUAGE: +SealedInterfaces +FreedomForSealedClasses
+
+// MODULE: m1
+// FILE: a.kt
+package a
+
+sealed interface Base
+
+interface A : Base
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+package a
+
+interface B : Base

compiler/testData/diagnostics/tests/sealed/interfaces/inheritorInDifferentModule.kt

@@ -0,0 +1,17 @@
+// ISSUE: KT-20423
+// !LANGUAGE: +SealedInterfaces +FreedomForSealedClasses
+
+// MODULE: m1
+// FILE: a.kt
+package a
+
+sealed interface Base
+
+interface A : Base
+
+// MODULE: m2(m1)
+// FILE: b.kt
+
+package a
+
+interface B : <!SEALED_INHERITOR_IN_DIFFERENT_MODULE!>Base<!>

compiler/testData/diagnostics/tests/sealed/interfaces/inheritorInDifferentModule.txt

@@ -0,0 +1,30 @@
+// -- Module: <m1> --
+package
+
+package a {
+
+    public interface A : a.Base {
+        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 interface Base {
+        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
+    }
+}
+
+
+// -- Module: <m2> --
+package
+
+package a {
+
+    public interface B : a.Base {
+        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
+    }
+}