Introduce PureReifiable annotation

It prevents reporting unsafe substitution warning on expressions
like 'arrayOf(arrayOf(""))'

core/builtins/native/kotlin/Library.kt

@@ -16,6 +16,8 @@
 
 package kotlin
 
+import kotlin.internal.PureReifiable
+
 /**
  * Returns a string representation of the object. Can be called with a null receiver, in which case
  * it returns the string "null".
@@ -31,4 +33,4 @@ public operator fun String?.plus(other: Any?): String
 /**
  * Returns an array of objects of the given type with the given [size], initialized with null values.
  */
-public fun arrayOfNulls<reified T>(size: Int): Array<T?>
+public fun <reified @PureReifiable T> arrayOfNulls(size: Int): Array<T?>

core/builtins/src/kotlin/ArrayIntrinsics.kt

@@ -16,11 +16,13 @@
 
 package kotlin
 
+import kotlin.internal.PureReifiable
+
 /**
  * Returns an array with the specified [size], where each element is calculated by calling the specified
  * [init] function. The `init` function returns an array element given its index.
  */
-public inline fun <reified T> Array(size: Int, init: (Int) -> T): Array<T> {
+public inline fun <reified @PureReifiable T> Array(size: Int, init: (Int) -> T): Array<T> {
     val result = arrayOfNulls<T>(size)
     for (i in 0..size - 1)
         result[i] = init(i)
@@ -126,14 +128,14 @@ public inline fun BooleanArray(size: Int, init: (Int) -> Boolean): BooleanArray
 /**
  * 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 @PureReifiable T> emptyArray(): Array<T> = arrayOfNulls<T>(0) as Array<T>
 
 
 // Array "constructor"
 /**
  * Returns an array containing the specified elements.
  */
-public inline fun <reified T> arrayOf(vararg elements: T) : Array<T> = elements as Array<T>
+public inline fun <reified @PureReifiable T> arrayOf(vararg elements: T) : Array<T> = elements as Array<T>
 
 // "constructors" for primitive types array
 /**

core/builtins/src/kotlin/internal/InternalAnnotations.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package kotlin.internal
+
+/**
+ * Specifies that the corresponding type parameter is not used for unsafe operations such as casts or 'is' checks
+ * That means it's completely safe to use generic types as argument for such parameter.
+ */
+@Target(AnnotationTarget.TYPE_PARAMETER)
+@Retention(AnnotationRetention.BINARY)
+internal annotation class PureReifiable

core/descriptors/src/org/jetbrains/kotlin/builtins/KotlinBuiltIns.java

@@ -58,7 +58,8 @@ public abstract class KotlinBuiltIns {
             COLLECTIONS_PACKAGE_FQ_NAME,
             RANGES_PACKAGE_FQ_NAME,
             ANNOTATION_PACKAGE_FQ_NAME,
-            ReflectionTypesKt.getKOTLIN_REFLECT_FQ_NAME()
+            ReflectionTypesKt.getKOTLIN_REFLECT_FQ_NAME(),
+            BUILT_INS_PACKAGE_FQ_NAME.child(Name.identifier("internal"))
     );
 
     protected final ModuleDescriptorImpl builtInsModule;