Make unsigned types experimental (with warning if not opted-in)

libraries/stdlib/unsigned/src/kotlin/annotations/Unsigned.kt

@@ -0,0 +1,23 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+@file:Suppress("INVISIBLE_REFERENCE", "INVISIBLE_MEMBER")
+package kotlin
+
+import kotlin.annotation.AnnotationTarget.*
+import kotlin.internal.RequireKotlin
+import kotlin.internal.RequireKotlinVersionKind
+
+/**
+ * Marks the API that is dependent on the experimental unsigned types, including those types themselves.
+ *
+ * Usages of such API will be reported as warnings unless an explicit opt-in with the [UseExperimental] annotation
+ * or the `-Xuse-experimental=kotlin.ExperimentalUnsignedTypes` compiler option is done.
+ */
+@Experimental(level = Experimental.Level.WARNING)
+@Target(CLASS, ANNOTATION_CLASS, PROPERTY, FIELD, LOCAL_VARIABLE, VALUE_PARAMETER, CONSTRUCTOR, FUNCTION, PROPERTY_GETTER, PROPERTY_SETTER, TYPEALIAS)
+@Retention(AnnotationRetention.BINARY)
+@RequireKotlin("1.2.50", versionKind = RequireKotlinVersionKind.COMPILER_VERSION)
+public annotation class ExperimentalUnsignedTypes