Array<Subtype> can be now cast to Array<Supertype(?)> without CAST_NEVER_SUCCEEDS #KT-6391 Fixed

(cherry picked from commit 2629d55)

compiler/frontend/src/org/jetbrains/kotlin/types/CastDiagnosticsUtil.kt

@@ -25,6 +25,7 @@ import org.jetbrains.kotlin.descriptors.ClassKind
 import org.jetbrains.kotlin.types.checker.KotlinTypeChecker
 import org.jetbrains.kotlin.types.checker.TypeCheckingProcedure
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
+import org.jetbrains.kotlin.types.typeUtil.isPrimitiveNumberType
 
 object CastDiagnosticsUtil {
 
@@ -46,8 +47,11 @@ object CastDiagnosticsUtil {
             if (KotlinBuiltIns.isArray(lhsType)) {
                 val lhsArgument = lhsType.arguments.firstOrNull()
                 val rhsArgument = rhsType.arguments.firstOrNull()
-                if (lhsArgument != null && rhsArgument != null && lhsArgument.type.constructor == rhsArgument.type.constructor) {
+                if (lhsArgument != null && rhsArgument != null) {
-                    return true
+                    if (lhsArgument.type.constructor == rhsArgument.type.constructor) return true
+                    if (KotlinTypeChecker.DEFAULT.isSubtypeOf(TypeUtils.makeNotNullable(lhsArgument.type), rhsArgument.type)) {
+                        return true
+                    }
                 }
             }
         }

compiler/testData/diagnostics/tests/cast/AsWithOtherParameter.kt

@@ -23,5 +23,12 @@ fun checkArrays2(): Array<Wrapper<String>> {
     return <!UNCHECKED_CAST!>someArray as Array<Wrapper<String>><!>
 }
 
+fun checkArrays3() {
+    val someArray = arrayOfNulls<String>(1)
+    <!UNCHECKED_CAST!>someArray as Array<Any><!>
+    val intArray = arrayOfNulls<Int>(1)
+    <!UNCHECKED_CAST!>intArray as Array<Any><!>
+}
+
 fun println(s: String) = s
 

compiler/testData/diagnostics/tests/cast/AsWithOtherParameter.txt

@@ -2,6 +2,7 @@ package
 
 public fun checkArrays(): kotlin.Array<kotlin.Any>
 public fun checkArrays2(): kotlin.Array<Wrapper<kotlin.String>>
+public fun checkArrays3(): kotlin.Unit
 public fun println(/*0*/ s: kotlin.String): kotlin.String
 public fun </*0*/ T> test(/*0*/ clazz: Class<T>): kotlin.Unit
 public fun use(): kotlin.Unit