diff --git a/js/js.libraries/src/core/kotlin_special.kt b/js/js.libraries/src/core/kotlin_special.kt
index 897655626a6..a8e8ea898eb 100644
--- a/js/js.libraries/src/core/kotlin_special.kt
+++ b/js/js.libraries/src/core/kotlin_special.kt
@@ -286,7 +286,7 @@ public inline fun ShortArray.copyOfRange(from: Int, to: Int): ShortArray {
  * Returns an array containing all elements of the original array and then all elements of the given [array].
  */
 suppress("NOTHING_TO_INLINE")
-public inline fun <T> Array<out T>.plus(array: Array<out T>): Array<out T> {
+public inline fun <T> Array<out T>.plus(array: Array<out T>): Array<T> {
     return (this: dynamic).concat(array)
 }
 
@@ -357,7 +357,7 @@ public inline fun ShortArray.plus(array: ShortArray): ShortArray {
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
-public fun <T> Array<out T>.plus(collection: Collection<T>): Array<out T> {
+public fun <T> Array<out T>.plus(collection: Collection<T>): Array<T> {
     return arrayPlusCollection(this, collection)
 }
 
@@ -420,81 +420,72 @@ public fun ShortArray.plus(collection: Collection<Short>): ShortArray {
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun <T> Array<out T>.plus(element: T): Array<out T> {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as Array<out T>
+suppress("NOTHING_TO_INLINE")
+public inline fun <T> Array<out T>.plus(element: T): Array<T> {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun BooleanArray.plus(element: Boolean): BooleanArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as BooleanArray
+suppress("NOTHING_TO_INLINE")
+public inline fun BooleanArray.plus(element: Boolean): BooleanArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun ByteArray.plus(element: Byte): ByteArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as ByteArray
+suppress("NOTHING_TO_INLINE")
+public inline fun ByteArray.plus(element: Byte): ByteArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun CharArray.plus(element: Char): CharArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as CharArray
+suppress("NOTHING_TO_INLINE")
+public inline fun CharArray.plus(element: Char): CharArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun DoubleArray.plus(element: Double): DoubleArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as DoubleArray
+suppress("NOTHING_TO_INLINE")
+public inline fun DoubleArray.plus(element: Double): DoubleArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun FloatArray.plus(element: Float): FloatArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as FloatArray
+suppress("NOTHING_TO_INLINE")
+public inline fun FloatArray.plus(element: Float): FloatArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun IntArray.plus(element: Int): IntArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as IntArray
+suppress("NOTHING_TO_INLINE")
+public inline fun IntArray.plus(element: Int): IntArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun LongArray.plus(element: Long): LongArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as LongArray
+suppress("NOTHING_TO_INLINE")
+public inline fun LongArray.plus(element: Long): LongArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
-public fun ShortArray.plus(element: Short): ShortArray {
-    val result = this.copyOf()
-    (result: dynamic).push(element)
-    return result as ShortArray
+suppress("NOTHING_TO_INLINE")
+public inline fun ShortArray.plus(element: Short): ShortArray {
+    return (this: dynamic).concat(arrayOf(element))
 }
 
diff --git a/libraries/stdlib/src/generated/_SpecialJVM.kt b/libraries/stdlib/src/generated/_SpecialJVM.kt
index 9aa542ba942..004e2e79538 100644
--- a/libraries/stdlib/src/generated/_SpecialJVM.kt
+++ b/libraries/stdlib/src/generated/_SpecialJVM.kt
@@ -196,8 +196,8 @@ public fun ShortArray.binarySearch(element: Short, fromIndex: Int = 0, toIndex:
 /**
  * Returns new array which is a copy of the original array.
  */
-public fun <T> Array<out T>.copyOf(): Array<T> {
-    return Arrays.copyOf(this, size()) as Array<T>
+public fun <T> Array<out T>.copyOf(): Array<out T> {
+    return Arrays.copyOf(this, size())
 }
 
 /**
@@ -259,8 +259,16 @@ public fun ShortArray.copyOf(): ShortArray {
 /**
  * Returns new array which is a copy of the original array.
  */
-public fun <T> Array<out T>.copyOf(newSize: Int): Array<T?> {
-    return Arrays.copyOf(this, newSize) as Array<T?>
+platformName("mutableCopyOf")
+public fun <T> Array<T>.copyOf(): Array<T> {
+    return Arrays.copyOf(this, size())
+}
+
+/**
+ * Returns new array which is a copy of the original array.
+ */
+public fun <T> Array<out T>.copyOf(newSize: Int): Array<out T?> {
+    return Arrays.copyOf(this, newSize)
 }
 
 /**
@@ -319,10 +327,18 @@ public fun ShortArray.copyOf(newSize: Int): ShortArray {
     return Arrays.copyOf(this, newSize)
 }
 
+/**
+ * Returns new array which is a copy of the original array.
+ */
+platformName("mutableCopyOf")
+public fun <T> Array<T>.copyOf(newSize: Int): Array<T?> {
+    return Arrays.copyOf(this, newSize)
+}
+
 /**
  * Returns new array which is a copy of range of original array.
  */
-public fun <T> Array<out T>.copyOfRange(from: Int, to: Int): Array<T> {
+public fun <T> Array<out T>.copyOfRange(from: Int, to: Int): Array<out T> {
     return Arrays.copyOfRange(this, from, to)
 }
 
@@ -383,11 +399,11 @@ public fun ShortArray.copyOfRange(from: Int, to: Int): ShortArray {
 }
 
 /**
- * Fills original array with the provided value.
+ * Returns new array which is a copy of range of original array.
  */
-public fun <T> Array<out T>.fill(element: T): Array<out T> {
-    Arrays.fill(this, element)
-    return this
+platformName("mutableCopyOfRange")
+public fun <T> Array<T>.copyOfRange(from: Int, to: Int): Array<T> {
+    return Arrays.copyOfRange(this, from, to)
 }
 
 /**
@@ -454,6 +470,14 @@ public fun ShortArray.fill(element: Short): ShortArray {
     return this
 }
 
+/**
+ * Fills original array with the provided value.
+ */
+public fun <T> Array<T>.fill(element: T): Array<T> {
+    Arrays.fill(this, element)
+    return this
+}
+
 /**
  * Returns a list containing all elements that are instances of specified type parameter R.
  */
@@ -544,26 +568,15 @@ public fun <C : MutableCollection<in R>, R> Sequence<*>.filterIsInstanceTo(desti
     return destination
 }
 
-/**
- * Returns an array containing all elements of the original array and then all elements of the given [array].
- */
-public fun <T> Array<out T>.plus(array: Array<out T>): Array<out T> {
-    val thisSize = size()
-    val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
-    System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as Array<out T>
-}
-
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [array].
  */
 public fun BooleanArray.plus(array: BooleanArray): BooleanArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as BooleanArray
+    return result
 }
 
 /**
@@ -572,9 +585,9 @@ public fun BooleanArray.plus(array: BooleanArray): BooleanArray {
 public fun ByteArray.plus(array: ByteArray): ByteArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as ByteArray
+    return result
 }
 
 /**
@@ -583,9 +596,9 @@ public fun ByteArray.plus(array: ByteArray): ByteArray {
 public fun CharArray.plus(array: CharArray): CharArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as CharArray
+    return result
 }
 
 /**
@@ -594,9 +607,9 @@ public fun CharArray.plus(array: CharArray): CharArray {
 public fun DoubleArray.plus(array: DoubleArray): DoubleArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as DoubleArray
+    return result
 }
 
 /**
@@ -605,9 +618,9 @@ public fun DoubleArray.plus(array: DoubleArray): DoubleArray {
 public fun FloatArray.plus(array: FloatArray): FloatArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as FloatArray
+    return result
 }
 
 /**
@@ -616,9 +629,9 @@ public fun FloatArray.plus(array: FloatArray): FloatArray {
 public fun IntArray.plus(array: IntArray): IntArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as IntArray
+    return result
 }
 
 /**
@@ -627,9 +640,9 @@ public fun IntArray.plus(array: IntArray): IntArray {
 public fun LongArray.plus(array: LongArray): LongArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as LongArray
+    return result
 }
 
 /**
@@ -638,198 +651,200 @@ public fun LongArray.plus(array: LongArray): LongArray {
 public fun ShortArray.plus(array: ShortArray): ShortArray {
     val thisSize = size()
     val arraySize = array.size()
-    val result = this.copyOf(thisSize + arraySize)
+    val result = Arrays.copyOf(this, thisSize + arraySize)
     System.arraycopy(array, 0, result, thisSize, arraySize)
-    return result as ShortArray
+    return result
 }
 
 /**
- * Returns an array containing all elements of the original array and then all elements of the given [collection].
+ * Returns an array containing all elements of the original array and then all elements of the given [array].
  */
-public fun <T> Array<out T>.plus(collection: Collection<T>): Array<out T> {
+public fun <T> Array<T>.plus(array: Array<out T>): Array<T> {
     val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as Array<out T>
+    val arraySize = array.size()
+    val result = Arrays.copyOf(this, thisSize + arraySize)
+    System.arraycopy(array, 0, result, thisSize, arraySize)
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun BooleanArray.plus(collection: Collection<Boolean>): BooleanArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as BooleanArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun ByteArray.plus(collection: Collection<Byte>): ByteArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as ByteArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun CharArray.plus(collection: Collection<Char>): CharArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as CharArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun DoubleArray.plus(collection: Collection<Double>): DoubleArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as DoubleArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun FloatArray.plus(collection: Collection<Float>): FloatArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as FloatArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun IntArray.plus(collection: Collection<Int>): IntArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as IntArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun LongArray.plus(collection: Collection<Long>): LongArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as LongArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
 public fun ShortArray.plus(collection: Collection<Short>): ShortArray {
-    val thisSize = size()
-    val result = this.copyOf(thisSize + collection.size())
-    collection.forEachIndexed { i, element ->
-        result[thisSize + i] = element
-    }
-    return result as ShortArray
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
- * Returns an array containing all elements of the original array and then the given [element].
+ * Returns an array containing all elements of the original array and then all elements of the given [collection].
  */
-public fun <T> Array<out T>.plus(element: T): Array<out T> {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as Array<out T>
+public fun <T> Array<T>.plus(collection: Collection<T>): Array<T> {
+    var index = size()
+    val result = Arrays.copyOf(this, index + collection.size())
+    for (element in collection) result[index++] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun BooleanArray.plus(element: Boolean): BooleanArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as BooleanArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun ByteArray.plus(element: Byte): ByteArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as ByteArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun CharArray.plus(element: Char): CharArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as CharArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun DoubleArray.plus(element: Double): DoubleArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as DoubleArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun FloatArray.plus(element: Float): FloatArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as FloatArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun IntArray.plus(element: Int): IntArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as IntArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun LongArray.plus(element: Long): LongArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as LongArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
  * Returns an array containing all elements of the original array and then the given [element].
  */
 public fun ShortArray.plus(element: Short): ShortArray {
-    val result = this.copyOf(size() + 1)
-    result[size()] = element
-    return result as ShortArray
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
+}
+
+/**
+ * Returns an array containing all elements of the original array and then the given [element].
+ */
+public fun <T> Array<T>.plus(element: T): Array<T> {
+    val index = size()
+    val result = Arrays.copyOf(this, index + 1)
+    result[index] = element
+    return result
 }
 
 /**
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJS.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJS.kt
index 18bd82d9717..829ec53a024 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJS.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJS.kt
@@ -77,12 +77,13 @@ fun specialJS(): List<GenericFunction> {
     templates add f("plus(element: T)") {
         only(ArraysOfObjects, ArraysOfPrimitives)
         returns("SELF")
+        returns(ArraysOfObjects) { "Array<T>" }
+        inline(true)
+        annotations("""suppress("NOTHING_TO_INLINE")""")
         doc { "Returns an array containing all elements of the original array and then the given [element]." }
-        body(ArraysOfObjects, ArraysOfPrimitives) {
+        body() {
             """
-            val result = this.copyOf()
-            (result: dynamic).push(element)
-            return result as SELF
+            return (this: dynamic).concat(arrayOf(element))
             """
         }
     }
@@ -90,6 +91,7 @@ fun specialJS(): List<GenericFunction> {
     templates add f("plus(collection: Collection<T>)") {
         only(ArraysOfObjects, ArraysOfPrimitives)
         returns("SELF")
+        returns(ArraysOfObjects) { "Array<T>" }
         doc { "Returns an array containing all elements of the original array and then all elements of the given [collection]." }
         body {
             """
@@ -105,6 +107,7 @@ fun specialJS(): List<GenericFunction> {
         inline(true)
         annotations("""suppress("NOTHING_TO_INLINE")""")
         returns("SELF")
+        returns(ArraysOfObjects) { "Array<T>" }
         body {
             """
             return (this: dynamic).concat(array)
diff --git a/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJVM.kt b/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJVM.kt
index 7a17e3a7bcd..fc7c95dfe33 100644
--- a/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJVM.kt
+++ b/libraries/tools/kotlin-stdlib-gen/src/templates/SpecialJVM.kt
@@ -6,92 +6,87 @@ fun specialJVM(): List<GenericFunction> {
     val templates = arrayListOf<GenericFunction>()
 
     templates add f("plus(element: T)") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(InvariantArraysOfObjects, ArraysOfPrimitives)
         returns("SELF")
         doc { "Returns an array containing all elements of the original array and then the given [element]." }
-        body(ArraysOfObjects, ArraysOfPrimitives) {
+        body() {
             """
-            val result = this.copyOf(size() + 1)
-            result[size()] = element
-            return result as SELF
+            val index = size()
+            val result = Arrays.copyOf(this, index + 1)
+            result[index] = element
+            return result
             """
         }
     }
 
     templates add f("plus(collection: Collection<T>)") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(InvariantArraysOfObjects, ArraysOfPrimitives)
         returns("SELF")
         doc { "Returns an array containing all elements of the original array and then all elements of the given [collection]." }
         body {
             """
-            val thisSize = size()
-            val result = this.copyOf(thisSize + collection.size())
-            collection.forEachIndexed { i, element ->
-                result[thisSize + i] = element
-            }
-            return result as SELF
+            var index = size()
+            val result = Arrays.copyOf(this, index + collection.size())
+            for (element in collection) result[index++] = element
+            return result
             """
         }
     }
 
     templates add f("plus(array: SELF)") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(InvariantArraysOfObjects, ArraysOfPrimitives)
+        customSignature(InvariantArraysOfObjects) { "plus(array: Array<out T>)" }
         doc { "Returns an array containing all elements of the original array and then all elements of the given [array]." }
         returns("SELF")
         body {
             """
             val thisSize = size()
             val arraySize = array.size()
-            val result = this.copyOf(thisSize + arraySize)
+            val result = Arrays.copyOf(this, thisSize + arraySize)
             System.arraycopy(array, 0, result, thisSize, arraySize)
-            return result as SELF
+            return result
             """
         }
     }
 
 
     templates add f("copyOfRange(from: Int, to: Int)") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(ArraysOfObjects, InvariantArraysOfObjects, ArraysOfPrimitives)
         doc { "Returns new array which is a copy of range of original array." }
         returns("SELF")
-        returns(ArraysOfObjects) { "Array<T>" }
+        annotations(InvariantArraysOfObjects) { """platformName("mutableCopyOfRange")"""}
         body {
             "return Arrays.copyOfRange(this, from, to)"
         }
     }
 
     templates add f("copyOf()") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(ArraysOfObjects, InvariantArraysOfObjects, ArraysOfPrimitives)
         doc { "Returns new array which is a copy of the original array." }
         returns("SELF")
-        returns(ArraysOfObjects) { "Array<T>" }
+        annotations(InvariantArraysOfObjects) { """platformName("mutableCopyOf")"""}
         body {
             "return Arrays.copyOf(this, size())"
         }
-        body(ArraysOfObjects) {
-            "return Arrays.copyOf(this, size()) as Array<T>"
-        }
     }
 
     // This overload can cause nulls if array size is expanding, hence different return overload
     templates add f("copyOf(newSize: Int)") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(ArraysOfObjects, InvariantArraysOfObjects, ArraysOfPrimitives)
         doc { "Returns new array which is a copy of the original array." }
         returns("SELF")
         body {
             "return Arrays.copyOf(this, newSize)"
         }
-        returns(ArraysOfObjects) { "Array<T?>" }
-        body(ArraysOfObjects) {
-            "return Arrays.copyOf(this, newSize) as Array<T?>"
-        }
+        returns(ArraysOfObjects) { "Array<out T?>" }
+        returns(InvariantArraysOfObjects) { "Array<T?>" }
+        annotations(InvariantArraysOfObjects) { """platformName("mutableCopyOf")"""}
     }
 
     templates add f("fill(element: T)") {
-        only(ArraysOfObjects, ArraysOfPrimitives)
+        only(InvariantArraysOfObjects, ArraysOfPrimitives)
         doc { "Fills original array with the provided value." }
         returns { "SELF" }
-        returns(ArraysOfObjects) { "Array<out T>" }
         body {
             """
             Arrays.fill(this, element)