Introduce KotlinVersion API

#KT-14789

js/js.libraries/src/core/annotationsJVM.kt

@@ -31,3 +31,8 @@ internal annotation class JvmName(public val name: String)
 @Retention(AnnotationRetention.SOURCE)
 @MustBeDocumented
 internal annotation class JvmMultifileClass
+
+@Target(AnnotationTarget.FIELD)
+@Retention(AnnotationRetention.SOURCE)
+@MustBeDocumented
+internal annotation class JvmField

libraries/stdlib/src/kotlin/util/KotlinVersion.kt

@@ -0,0 +1,65 @@
+package kotlin
+
+/**
+ * Represents a version of the Kotlin standard library
+ */
+public class KotlinVersion(val major: Int, val minor: Int, val patch: Int) : Comparable<KotlinVersion> {
+    public constructor(major: Int, minor: Int) : this(major, minor, 0)
+
+    private val version = versionOf(major, minor, patch)
+
+    private fun versionOf(major: Int, minor: Int, patch: Int): Int {
+        require(major in 0..99 && minor in 0..99 && patch in 0..99) { "Version components are out of range: $major.$minor.$patch" }
+        return major * 100 * 100 + minor * 100 + patch
+    }
+
+    /**
+     * Returns the integer representation of this version.
+     *
+     * Integer representations of two [KotlinVersion] instances can be compared,
+     * so that if `v1.toInt() > v2.toInt()` then `v1 > v2`.
+     *
+     * This value should not be persisted, as it can change between program runs.
+     */
+    public fun toInt(): Int = version
+
+    /**
+     * Returns the string representation of this version
+     */
+    override fun toString(): String = "$major.$minor.$patch"
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        val otherVersion = (other as? KotlinVersion) ?: return false
+        return this.version == otherVersion.version
+    }
+
+    override fun hashCode(): Int = version
+
+    override fun compareTo(other: KotlinVersion): Int = version - other.version
+
+    public fun isAtLeast(major: Int, minor: Int): Boolean =
+            // or this.version >= versionOf(major, minor, 0)
+            this.major > major || (this.major == major &&
+                    this.minor >= minor)
+
+    public fun isAtLeast(major: Int, minor: Int, patch: Int): Boolean =
+            // or this.version >= versionOf(major, minor, patch)
+            this.major > major || (this.major == major &&
+                    (this.minor > minor || this.minor == minor &&
+                            this.patch >= patch))
+
+    public fun isAtLeast(version: KotlinVersion): Boolean = this >= version
+
+    companion object {
+        /**
+         * Returns the current version of the Kotlin standard library
+         */
+        // TODO: get from metadata or hardcode automatically during build
+        @kotlin.jvm.JvmField
+        public val CURRENT: KotlinVersion = KotlinVersion(1, 1, 0)
+
+        // should we have 'parse'?
+
+    }
+}

libraries/tools/binary-compatibility-validator/reference-public-api/kotlin-stdlib.txt

@@ -2,6 +2,28 @@ public final class kotlin/ExceptionsKt {
 	public static final fun getStackTrace (Ljava/lang/Throwable;)[Ljava/lang/StackTraceElement;
 }
 
+public final class kotlin/KotlinVersion : java/lang/Comparable {
+	public static final field CURRENT Lkotlin/KotlinVersion;
+	public static final field Companion Lkotlin/KotlinVersion$Companion;
+	public fun <init> (II)V
+	public fun <init> (III)V
+	public synthetic fun compareTo (Ljava/lang/Object;)I
+	public fun compareTo (Lkotlin/KotlinVersion;)I
+	public fun equals (Ljava/lang/Object;)Z
+	public final fun getMajor ()I
+	public final fun getMinor ()I
+	public final fun getPatch ()I
+	public fun hashCode ()I
+	public final fun isAtLeast (II)Z
+	public final fun isAtLeast (III)Z
+	public final fun isAtLeast (Lkotlin/KotlinVersion;)Z
+	public final fun toInt ()I
+	public fun toString ()Ljava/lang/String;
+}
+
+public final class kotlin/KotlinVersion$Companion {
+}
+
 public abstract interface class kotlin/Lazy {
 	public abstract fun getValue ()Ljava/lang/Object;
 	public abstract fun isInitialized ()Z