Enabled klib abi version compatibility

compiler/util-klib/src/org/jetbrains/kotlin/library/KotlinAbiVersion.kt

@@ -26,13 +26,38 @@ fun String.parseKotlinAbiVersion(): KotlinAbiVersion {
     }
 }
 
-// For 1.4 compiler we switch klib abi_version to a triple,
-// but we don't break if we still encounter a single digit from 1.3.
+// TODO: it would be nice to inherit this one from BinaryVersion,
+// but that requires a module structure refactoring.
 data class KotlinAbiVersion(val major: Int, val minor: Int, val patch: Int) {
+    // For 1.4 compiler we switched klib abi_version to a triple,
+    // but we don't break if we still encounter a single digit from 1.3.
     constructor(single: Int) : this(0, single, 0)
-    companion object {
-        val CURRENT = KotlinAbiVersion(1, 4, 1)
+
+    fun isCompatible(): Boolean = isCompatibleTo(CURRENT)
+
+    private fun isCompatibleTo(ourVersion: KotlinAbiVersion): Boolean {
+        return if (this.isAtLeast(1, 4, 1))
+            major == ourVersion.major && minor <= ourVersion.minor
+        else
+            this == ourVersion
+    }
+
+    fun isAtLeast(version: KotlinAbiVersion): Boolean =
+        isAtLeast(version.major, version.minor, version.patch)
+
+    fun isAtLeast(major: Int, minor: Int, patch: Int): Boolean {
+        if (this.major > major) return true
+        if (this.major < major) return false
+
+        if (this.minor > minor) return true
+        if (this.minor < minor) return false
+
+        return this.patch >= patch
     }
 
     override fun toString() = "$major.$minor.$patch"
+
+    companion object {
+        val CURRENT = KotlinAbiVersion(1, 4, 1)
+    }
 }