Fix lazy {} memory leak regression caused by #3862

backend.native/tests/build.gradle

@@ -1040,6 +1040,10 @@ standaloneTest("lazy2") {
     source = "runtime/workers/lazy2.kt"
 }
 
+standaloneTest("lazy3") {
+    source = "runtime/workers/lazy3.kt"
+}
+
 task enumIdentity(type: KonanLocalTest) {
     enabled = (project.testTarget != 'wasm32') // Workers need pthreads.
     goldValue = "true\n"

backend.native/tests/runtime/workers/lazy3.kt

@@ -0,0 +1,54 @@
+import kotlin.native.concurrent.*
+import kotlin.native.ref.*
+import kotlin.test.*
+
+fun main() {
+    test1()
+    test2()
+}
+
+fun test1() {
+    ensureGetsCollectedFrozenAndNotFrozen { LazyCapturesThis() }
+    ensureGetsCollectedFrozenAndNotFrozen {
+        val l = LazyCapturesThis()
+        l.bar
+        l
+    }
+    ensureGetsCollected {
+        val l = LazyCapturesThis().freeze()
+        l.bar
+        l
+    }
+}
+
+class LazyCapturesThis {
+    fun foo() = 42
+    val bar by lazy { foo() }
+}
+
+fun test2() {
+    ensureGetsCollectedFrozenAndNotFrozen { Throwable() }
+    ensureGetsCollectedFrozenAndNotFrozen {
+        val throwable = Throwable()
+        throwable.getStackTrace()
+        throwable
+    }
+    ensureGetsCollected {
+        val throwable = Throwable().freeze()
+        throwable.getStackTrace()
+        throwable
+    }
+}
+
+fun ensureGetsCollectedFrozenAndNotFrozen(create: () -> Any) {
+    ensureGetsCollected { create().freeze() }
+    ensureGetsCollected(create)
+}
+
+fun ensureGetsCollected(create: () -> Any) {
+    val ref = makeWeakRef(create)
+    kotlin.native.internal.GC.collect()
+    assertNull(ref.get())
+}
+
+fun makeWeakRef(create: () -> Any) = WeakReference(create())

runtime/src/main/kotlin/kotlin/native/concurrent/Lazy.kt

@@ -9,7 +9,7 @@ import kotlin.native.internal.Frozen
 
 internal class FreezeAwareLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
     private val value_ = FreezableAtomicReference<Any?>(UNINITIALIZED)
-    private val initializer_ = FreezableAtomicReference<(() -> T)?>(initializer)
+    private var initializer_: (() -> T)? = initializer
     private val lock_ = Lock()
 
     private fun getOrInit(doFreeze: Boolean): T {
@@ -25,20 +25,22 @@ internal class FreezeAwareLazyImpl<out T>(initializer: () -> T) : Lazy<T> {
         // Set value_ to INITIALIZING.
         value_.value = INITIALIZING
         try {
-            result = initializer_.value!!()
+            result = initializer_!!()
             if (doFreeze) result.freeze()
         } catch (throwable: Throwable) {
             value_.value = UNINITIALIZED
             throw throwable
         }
-        if (!doFreeze && this.isFrozen) {
-            value_.value = UNINITIALIZED
-            throw InvalidMutabilityException("Frozen during lazy computation")
+        if (!doFreeze) {
+            if (this.isFrozen) {
+                value_.value = UNINITIALIZED
+                throw InvalidMutabilityException("Frozen during lazy computation")
+            }
+            // Clear initializer.
+            initializer_ = null
         }
         // Set value_ to actual one.
         value_.value = result
-        // Clear initializer.
-        initializer_.value = null
         @Suppress("UNCHECKED_CAST")
         return result as T
     }