Introduce unsafeCast function. Provide more JS-idiomatic emptyArray() implementation.

#KT-14034 Fixed

js/js.libraries/src/core/collections.kt

@@ -26,7 +26,7 @@ internal fun <T> copyToArray(collection: Collection<T>): Array<T> {
     return if (collection.asDynamic().toArray !== undefined)
         collection.asDynamic().toArray()
     else
-        copyToArrayImpl(collection).asDynamic()
+        copyToArrayImpl(collection).unsafeCast<Array<T>>()
 }
 
 @JsName("copyToArrayImpl")

js/js.libraries/src/core/dynamic.kt

@@ -16,17 +16,22 @@
 
 package kotlin.js
 
-inline fun Any?.asDynamic(): dynamic = this
+public inline fun Any?.asDynamic(): dynamic = this
+
+/**
+ * Reinterprets this value as a value of the specified type [T] without any actual type checking.
+ */
+public inline fun <T> Any?.unsafeCast(): @kotlin.internal.NoInfer T = this.asDynamic()
 
 // TODO add the support ES6 iterators
-operator fun dynamic.iterator(): Iterator<dynamic> {
+public operator fun dynamic.iterator(): Iterator<dynamic> {
-    val r = this
+    val r: Any? = this
 
     return when {
         this["iterator"] != null ->
             this["iterator"]()
         js("Array.isArray(r)") ->
-            (this as Array<*>).iterator()
+            r.unsafeCast<Array<*>>().iterator()
 
         else ->
             (r as Iterable<*>).iterator()

js/js.libraries/src/core/generated/_ArraysJs.kt

@@ -14,119 +14,119 @@ import kotlin.comparisons.*
  * Returns a [List] that wraps the original array.
  */
 public fun <T> Array<out T>.asList(): List<T> {
-    return ArrayList<T>(this as Array<Any?>)
+    return ArrayList<T>(this.unsafeCast<Array<Any?>>())
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun ByteArray.asList(): List<Byte> {
-    return (this as Array<Byte>).asList()
+    return this.unsafeCast<Array<Byte>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun ShortArray.asList(): List<Short> {
-    return (this as Array<Short>).asList()
+    return this.unsafeCast<Array<Short>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun IntArray.asList(): List<Int> {
-    return (this as Array<Int>).asList()
+    return this.unsafeCast<Array<Int>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun LongArray.asList(): List<Long> {
-    return (this as Array<Long>).asList()
+    return this.unsafeCast<Array<Long>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun FloatArray.asList(): List<Float> {
-    return (this as Array<Float>).asList()
+    return this.unsafeCast<Array<Float>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun DoubleArray.asList(): List<Double> {
-    return (this as Array<Double>).asList()
+    return this.unsafeCast<Array<Double>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun BooleanArray.asList(): List<Boolean> {
-    return (this as Array<Boolean>).asList()
+    return this.unsafeCast<Array<Boolean>>().asList()
 }
 
 /**
  * Returns a [List] that wraps the original array.
  */
 public inline fun CharArray.asList(): List<Char> {
-    return (this as Array<Char>).asList()
+    return this.unsafeCast<Array<Char>>().asList()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun ByteArray.toTypedArray(): Array<Byte> {
-    return copyOf() as Array<Byte>
+    return copyOf().unsafeCast<Array<Byte>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun ShortArray.toTypedArray(): Array<Short> {
-    return copyOf() as Array<Short>
+    return copyOf().unsafeCast<Array<Short>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun IntArray.toTypedArray(): Array<Int> {
-    return copyOf() as Array<Int>
+    return copyOf().unsafeCast<Array<Int>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun LongArray.toTypedArray(): Array<Long> {
-    return copyOf() as Array<Long>
+    return copyOf().unsafeCast<Array<Long>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun FloatArray.toTypedArray(): Array<Float> {
-    return copyOf() as Array<Float>
+    return copyOf().unsafeCast<Array<Float>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun DoubleArray.toTypedArray(): Array<Double> {
-    return copyOf() as Array<Double>
+    return copyOf().unsafeCast<Array<Double>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun BooleanArray.toTypedArray(): Array<Boolean> {
-    return copyOf() as Array<Boolean>
+    return copyOf().unsafeCast<Array<Boolean>>()
 }
 
 /**
  * Returns a *typed* object array containing all of the elements of this primitive array.
  */
 public fun CharArray.toTypedArray(): Array<Char> {
-    return copyOf() as Array<Char>
+    return copyOf().unsafeCast<Array<Char>>()
 }
 
 /**

js/js.libraries/src/core/kotlin.kt

@@ -21,7 +21,7 @@ import java.util.*
 /**
  * Returns an empty array of the specified type [T].
  */
-public inline fun <reified T> emptyArray(): Array<T> = arrayOfNulls<T>(0) as Array<T>
+public inline fun <reified T> emptyArray(): Array<T> = js("[]")
 
 @library
 public fun <T> arrayOf(vararg elements: T): Array<T> = noImpl
@@ -70,7 +70,7 @@ public fun <T> lazy(lock: Any?, initializer: () -> T): Lazy<T> = UnsafeLazyImpl(
 
 
 internal fun <T> arrayOfNulls(reference: Array<out T>, size: Int): Array<T> {
-    return arrayOfNulls<Any>(size) as Array<T>
+    return arrayOfNulls<Any>(size).unsafeCast<Array<T>>()
 }
 
 internal fun arrayCopyResize(source: dynamic, newSize: Int, defaultValue: Any?): dynamic {

js/js.libraries/src/core/regexp.kt

@@ -50,4 +50,4 @@ public fun RegExp.reset() {
 }
 
 
-public inline fun RegExpMatch.asArray(): Array<out String?> = this.asDynamic()
+public inline fun RegExpMatch.asArray(): Array<out String?> = unsafeCast<Array<out String?>>()

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

@@ -27,12 +27,12 @@ fun specialJS(): List<GenericFunction> {
         returns("List<T>")
         body(ArraysOfObjects) {
             """
-            return ArrayList<T>(this as Array<Any?>)
+            return ArrayList<T>(this.unsafeCast<Array<Any?>>())
             """
         }
 
         inline(true, ArraysOfPrimitives)
-        body(ArraysOfPrimitives) {"""return (this as Array<T>).asList()"""}
+        body(ArraysOfPrimitives) {"""return this.unsafeCast<Array<T>>().asList()"""}
     }
 
 
@@ -46,7 +46,7 @@ fun specialJS(): List<GenericFunction> {
         }
         body {
             """
-            return copyOf() as Array<T>
+            return copyOf().unsafeCast<Array<T>>()
             """
         }
     }