Atomic lazy getter. (#1769)

backend.native/tests/build.gradle

@@ -696,6 +696,12 @@ task atomic0(type: RunKonanTest) {
     source = "runtime/workers/atomic0.kt"
 }
 
+task lazy0(type: RunKonanTest) {
+    disabled = (project.testTarget == 'wasm32') // Workers need pthreads.
+    goldValue = "OK\n"
+    source = "runtime/workers/lazy0.kt"
+}
+
 task enumIdentity(type: RunKonanTest) {
     disabled = (project.testTarget == 'wasm32') // Workers need pthreads.
     goldValue = "true\n"

backend.native/tests/runtime/workers/lazy0.kt

@@ -0,0 +1,38 @@
+package runtime.workers.lazy0
+
+import kotlin.test.*
+
+import konan.worker.*
+
+data class Data(val x: Int, val y: String)
+
+object Immutable {
+    val x by atomicLazy {
+        42
+    }
+}
+
+object Immutable2 {
+    val y by atomicLazy {
+        Data(239, "Kotlin")
+    }
+}
+
+@Test fun runTest() {
+    assertEquals(42, Immutable.x)
+
+    val COUNT = 5
+    val workers = Array(COUNT, { _ -> startWorker()})
+
+    val set = mutableSetOf<Any?>()
+    for (attempt in 1 .. 3) {
+        val futures = Array(workers.size, { workerIndex ->
+            workers[workerIndex].schedule(TransferMode.CHECKED, { "" }) { _  -> Immutable2.y }
+        })
+        futures.forEach { set += it.result() }
+    }
+    assertEquals(set.size, 1)
+    assertEquals(set.single(), Immutable2.y)
+
+    println("OK")
+}