Atomicfu plugin (JS IR): fix for private delegated properties

Fixes https://github.com/Kotlin/kotlinx-atomicfu/issues/260

plugins/atomicfu/atomicfu-compiler/src/org/jetbrains/kotlinx/atomicfu/compiler/backend/js/AtomicfuJsIrTransformer.kt

@@ -125,13 +125,13 @@ class AtomicfuJsIrTransformer(private val context: IrPluginContext) {
                                 // fun <get-a>() = a$delegate.value -> _a.value
                                 // fun <set-a>(value: Int) = { a$delegate.value = value } -> { _a.value = value }
                                 val originalField = initializer.getBackingField()
-                                declaration.transform(DelegatePropertyTransformer(originalField, initializer.dispatchReceiver, false), null)
+                                declaration.transform(DelegatePropertyTransformer(originalField), null)
                             }
                             initializer.isAtomicFactory() -> {
                                 // var a by atomic(77) -> var a: Int = 77
                                 it.expression = initializer.eraseAtomicFactory()
                                     ?: error("Atomic factory was expected but found ${initializer.render()}")
-                                declaration.transform(DelegatePropertyTransformer(delegateBackingField, initializer.dispatchReceiver, true), null)
+                                declaration.transform(DelegatePropertyTransformer(delegateBackingField), null)
                             }
                             else -> error("Unexpected initializer of the delegated property: $initializer")
                         }
@@ -275,9 +275,7 @@ class AtomicfuJsIrTransformer(private val context: IrPluginContext) {
         }
 
         private inner class DelegatePropertyTransformer(
-            val originalField: IrField,
-            val receiver: IrExpression?,
-            val isInitializedWithAtomicFactory: Boolean
+            val originalField: IrField
         ): IrElementTransformerVoid() {
             override fun visitCall(expression: IrCall): IrExpression {
                 // Accessors of the delegated property have following signatures:
@@ -291,11 +289,14 @@ class AtomicfuJsIrTransformer(private val context: IrPluginContext) {
                     val type = originalField.type.atomicToValueType()
                     val isSetter = name == SET_VALUE
                     val runtimeFunction = getRuntimeFunctionSymbol(name, type)
-                    val dispatchReceiver = if (isInitializedWithAtomicFactory) {
-                        val thisRef = expression.getValueArgument(0)!!
-                        if (thisRef.isConstNull()) null else thisRef
-                    } else {
-                        receiver
+                    // val _a = atomic(77)
+                    // var a: Int by _a
+                    // This is the delegate getValue operator of property `a`, which should be transformed to getting the value of the original atomic `_a`
+                    // operator fun getValue(thisRef: Any?, property: kotlin.reflect.KProperty<*>) {
+                    //  return thisRef._a
+                    // }
+                    val dispatchReceiver = expression.getValueArgument(0)?.let {
+                        if (it.isConstNull()) null else it
                     }
                     val fieldAccessors = listOf(
                         context.buildFieldAccessor(originalField, dispatchReceiver, false),

plugins/atomicfu/atomicfu-compiler/testData/box/DelegatedPropertiesTest.kt

@@ -7,37 +7,47 @@ var topLevelInt: Int by _topLevelInt
 private var topLevelVolatile by atomic(56)
 
 class DelegatedProperties {
+    // Delegated properties should be declared in the same scope as the original atomic values
     private val _a = atomic(42)
     var a: Int by _a
+    private var privateA: Int by _a
 
     private val _l = atomic(55555555555)
-    var l: Long by _l
+    private var l: Long by _l
 
     private val _b = atomic(false)
-    var b: Boolean by _b
+    private var b: Boolean by _b
 
     private val _ref = atomic(A(B(77)))
-    var ref: A by _ref
+    private var ref: A by _ref
 
-    var vInt by atomic(77)
+    private var vInt by atomic(77)
 
-    var vLong by atomic(777777777)
+    private var vLong by atomic(777777777)
 
-    var vBoolean by atomic(false)
+    private var vBoolean by atomic(false)
 
-    var vRef by atomic(A(B(77)))
+    private var vRef by atomic(A(B(77)))
 
     class A (val b: B)
     class B (val n: Int)
 
    fun testDelegatedAtomicInt() {
         assertEquals(42, a)
+        assertEquals(42, privateA)
         _a.compareAndSet(42, 56)
         assertEquals(56, a)
+        assertEquals(56, privateA)
         a = 77
         _a.compareAndSet(77,  66)
+        privateA = 88
+        _a.compareAndSet(88,  66)
         assertEquals(66, _a.value)
         assertEquals(66, a)
+        assertEquals(66, privateA)
+
+        val aValue = a + privateA
+        assertEquals(132, aValue)
     }
 
     fun testDelegatedAtomicLong() {
@@ -95,25 +105,23 @@ class DelegatedProperties {
     }
 
     inner class D {
-        var b: Int by _a
         var c by atomic("aaa")
     }
 
-    fun testScopedDelegatedProperties() {
+    fun testScopedVolatileProperties() {
         val clazz = D()
-        clazz.b = 42
-        _a.compareAndSet(42, 56)
-        assertEquals(56, clazz.b)
-        clazz.b = 77
-        _a.compareAndSet(77, 66)
-        assertEquals(66, _a.value)
-        assertEquals(66, clazz.b)
-
         assertEquals("aaa", clazz.c)
         clazz.c = "bbb"
         assertEquals("bbb", clazz.c)
     }
 
+    fun testDelegatedVariablesFlow() {
+        _a.lazySet(55)
+        assertEquals(55, _a.value)
+        assertEquals(55, a)
+        var aValue = a
+    }
+
     fun test() {
         testDelegatedAtomicInt()
         testDelegatedAtomicLong()
@@ -123,7 +131,8 @@ class DelegatedProperties {
         testVolatileBoolean()
         testVolatileLong()
         testVolatileRef()
-        testScopedDelegatedProperties()
+        testScopedVolatileProperties()
+        testDelegatedVariablesFlow()
     }
 }