Make a more correct implementation of unsigned arrays copyInto

Return the destination array instead of the destination storage array
wrapped in a new unsigned array. The difference should be
indistinguishable, however in JS, where inline classes are not inlined yet,
it had resulted in an extra wrapper.

libraries/stdlib/common/src/generated/_UArrays.kt

@@ -346,7 +346,8 @@ public fun UShortArray.contentToString(): String {
 @ExperimentalUnsignedTypes
 @kotlin.internal.InlineOnly
 public inline fun UIntArray.copyInto(destination: UIntArray, destinationOffset: Int = 0, startIndex: Int = 0, endIndex: Int = size): UIntArray {
-    return UIntArray(storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex))
+    storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex)
+    return destination
 }
 
 /**
@@ -369,7 +370,8 @@ public inline fun UIntArray.copyInto(destination: UIntArray, destinationOffset:
 @ExperimentalUnsignedTypes
 @kotlin.internal.InlineOnly
 public inline fun ULongArray.copyInto(destination: ULongArray, destinationOffset: Int = 0, startIndex: Int = 0, endIndex: Int = size): ULongArray {
-    return ULongArray(storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex))
+    storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex)
+    return destination
 }
 
 /**
@@ -392,7 +394,8 @@ public inline fun ULongArray.copyInto(destination: ULongArray, destinationOffset
 @ExperimentalUnsignedTypes
 @kotlin.internal.InlineOnly
 public inline fun UByteArray.copyInto(destination: UByteArray, destinationOffset: Int = 0, startIndex: Int = 0, endIndex: Int = size): UByteArray {
-    return UByteArray(storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex))
+    storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex)
+    return destination
 }
 
 /**
@@ -415,7 +418,8 @@ public inline fun UByteArray.copyInto(destination: UByteArray, destinationOffset
 @ExperimentalUnsignedTypes
 @kotlin.internal.InlineOnly
 public inline fun UShortArray.copyInto(destination: UShortArray, destinationOffset: Int = 0, startIndex: Int = 0, endIndex: Int = size): UShortArray {
-    return UShortArray(storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex))
+    storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex)
+    return destination
 }
 
 /**

libraries/tools/kotlin-stdlib-gen/src/templates/Arrays.kt

@@ -517,7 +517,10 @@ object ArrayOps : TemplateGroupBase() {
         specialFor(ArraysOfUnsigned) {
             inlineOnly()
             body {
-                "return SELF(storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex))"
+                """
+                storage.copyInto(destination.storage, destinationOffset, startIndex, endIndex)
+                return destination
+                """
             }
         }
         specialFor(ArraysOfPrimitives, InvariantArraysOfObjects) {