KT-53465, KT-53677 Get rid of unnecessary checkcasts to array of reified type

compiler/testData/codegen/box/casts/arrayDowncastingContravariant.kt

@@ -0,0 +1,10 @@
+// TARGET_BACKEND: JVM
+
+inline fun <reified T : CharSequence> f(x: Array<in String>) = x as Array<T>
+
+fun box(): String = try {
+    f<String>(arrayOf<Any>(42))
+    "Fail"
+} catch (e: Exception) {
+    "OK"
+}

compiler/testData/codegen/box/casts/arrayDowncatingInvariant.kt

@@ -0,0 +1,10 @@
+// TARGET_BACKEND: JVM
+
+inline fun <reified T : CharSequence> f(x: Array<Any>) = x as Array<T>
+
+fun box(): String = try {
+    f<String>(arrayOf<Any>(42))
+    "Fail"
+} catch (e: Exception) {
+    "OK"
+}

compiler/testData/codegen/box/casts/arrayDownctingCovariant.kt

@@ -0,0 +1,10 @@
+// TARGET_BACKEND: JVM
+
+inline fun <reified T : CharSequence> f(x: Array<out Any>) = x as Array<T>
+
+fun box(): String = try {
+    f<String>(arrayOf<Int>(42))
+    "Fail"
+} catch (e: Exception) {
+    "OK"
+}

compiler/testData/codegen/box/casts/kt48927_privateMethodOnDerivedCastToBase.kt

@@ -2,8 +2,13 @@ abstract class Base {
     private fun test(): String = "OK"
 
     fun test(d: Derived): String = (d as Base).test()
+
+    fun test(d: Array<out Derived>) = (d as Array<out Base>)[0].test()
 }
 
 class Derived : Base()
 
-fun box(): String = Derived().test(Derived())
+fun box(): String {
+    Derived().test(arrayOf(Derived()))
+    return Derived().test(Derived())
+}

compiler/testData/codegen/box/casts/kt53677.kt

@@ -0,0 +1,29 @@
+// WITH_STDLIB
+// WITH_COROUTINES
+// DONT_TARGET_EXACT_BACKEND: JVM
+// DONT_TARGET_EXACT_BACKEND: JS
+
+import kotlin.coroutines.*
+
+public inline fun <reified T> myEmptyArray(): Array<T> = arrayOfNulls<T>(0) as Array<T>
+
+inline fun <reified T> Array<out T>?.myOrEmpty(): Array<out T> = this ?: myEmptyArray<T>()
+
+fun <T> runBlocking(c: suspend () -> T): T {
+    var res: T? = null
+    c.startCoroutine(Continuation(EmptyCoroutineContext) {
+        res = it.getOrThrow()
+    })
+    return res!!
+}
+
+suspend fun suspendHere(x: String) {}
+
+suspend fun main() {
+    arrayOf("1").myOrEmpty().forEach { suspendHere(it) }
+}
+
+fun box(): String {
+    runBlocking(::main)
+    return "OK"
+}