[FIR] Allow actualization of expect classes by classes with wider visibility

^KT-59355 Fixed

compiler/testData/codegen/box/multiplatform/k2/basic/widerVisibilityInActualClassifier.kt

@@ -0,0 +1,49 @@
+// IGNORE_BACKEND_K1: ANY
+//   IGNORE_REASON: KT-59355 is fixed only in K2
+// IGNORE_BACKEND_K2: JS_IR
+//   IGNORE_REASON: `JsName` in js.translator/testData/_commonFiles/testUtils.kt is invisible for some reason
+// IGNORE_BACKEND: WASM
+//   IGNORE_REASON: wasm tests don't support IGNORE_BACKEND_K1 directive
+// LANGUAGE: +MultiPlatformProjects
+// ISSUE: KT-59355
+
+// MODULE: common
+// FILE: common.kt
+internal expect open class Some() {
+    protected class ProtectedNested() {
+        fun foo(): String
+    }
+}
+
+internal class SomeInheritor : Some() {
+    fun callFoo(): String {
+        return ProtectedNested().foo()
+    }
+}
+
+internal expect open class Other() {
+    fun bar(): String
+}
+
+fun commonBox(): String {
+    val x = SomeInheritor().callFoo()
+    val y = Other().bar()
+    return x + y
+}
+
+// MODULE: platform-jvm()()(common)
+// FILE: main.kt
+public actual open class Some actual constructor() {
+    public actual class ProtectedNested actual constructor() {
+        actual fun foo(): String = "O"
+    }
+}
+
+public open class PlatformOther {
+    fun bar(): String = "K"
+}
+
+internal actual typealias Other = PlatformOther
+
+fun box(): String = commonBox()
+

compiler/testData/diagnostics/tests/multiplatform/widerVisibilityInActualClassifier.fir.kt

@@ -0,0 +1,34 @@
+// ISSUE: KT-59355
+
+// MODULE: common
+internal expect open class Some {
+    protected class ProtectedNested
+    internal class InternalNested
+
+    public fun publicFun()
+    internal fun internalFun()
+    protected fun protectedFun()
+}
+
+internal expect open class Other {
+    protected class ProtectedNested
+    internal class InternalNested
+}
+
+// MODULE: platform-jvm()()(common)
+public actual open class Some { // should be allowed
+    public class ProtectedNested  // should be allowed
+    public class InternalNested // should be allowed
+
+    public actual fun publicFun() {} // should be allowed
+    public actual fun internalFun() {} // should be allowed
+    public actual fun protectedFun() {} // should be allowed
+}
+
+public open class PlatformOther { // should be allowed
+    public class ProtectedNested  // should be allowed
+    public class InternalNested // should be allowed
+}
+
+internal actual typealias Other = PlatformOther // should be allowed
+

compiler/testData/diagnostics/tests/multiplatform/widerVisibilityInActualClassifier.kt

@@ -0,0 +1,34 @@
+// ISSUE: KT-59355
+
+// MODULE: common
+internal expect open class <!NO_ACTUAL_FOR_EXPECT!>Some<!> {
+    protected class ProtectedNested
+    internal class InternalNested
+
+    public fun publicFun()
+    internal fun internalFun()
+    protected fun protectedFun()
+}
+
+internal expect open class <!NO_ACTUAL_FOR_EXPECT!>Other<!> {
+    protected class ProtectedNested
+    internal class InternalNested
+}
+
+// MODULE: platform-jvm()()(common)
+<!ACTUAL_WITHOUT_EXPECT!>public<!> actual open class Some { // should be allowed
+    <!ACTUAL_WITHOUT_EXPECT!>public<!> class <!ACTUAL_MISSING!>ProtectedNested<!>  // should be allowed
+    <!ACTUAL_WITHOUT_EXPECT!>public<!> class <!ACTUAL_MISSING!>InternalNested<!> // should be allowed
+
+    public actual fun publicFun() {} // should be allowed
+    public actual fun internalFun() {} // should be allowed
+    public actual fun protectedFun() {} // should be allowed
+}
+
+public open class PlatformOther { // should be allowed
+    public class ProtectedNested  // should be allowed
+    public class InternalNested // should be allowed
+}
+
+<!ACTUAL_WITHOUT_EXPECT!>internal<!> actual typealias Other = PlatformOther // should be allowed
+