[K/JS, K/Wasm] Optimize simple objects declaration and usage ^Fixed KT-58797

js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/ClassPostProcessor.kt

@@ -0,0 +1,34 @@
+/*
+ * Copyright 2010-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.jetbrains.kotlin.js.inline.clean
+
+import org.jetbrains.kotlin.js.backend.ast.JsClass
+
+class ClassPostProcessor(val root: JsClass) {
+    val optimizations = listOf(
+        { EmptyConstructorRemoval(root).apply() }
+    )
+
+    fun apply() {
+        do {
+            var hasChanges = false
+            for (opt in optimizations) {
+                hasChanges = hasChanges or opt()
+            }
+        } while (hasChanges)
+    }
+}

js/js.inliner/src/org/jetbrains/kotlin/js/inline/clean/EmptyConstructorRemoval.kt

@@ -0,0 +1,16 @@
+/*
+ * Copyright 2010-2023 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.js.inline.clean
+
+import org.jetbrains.kotlin.js.backend.ast.JsClass
+
+class EmptyConstructorRemoval(private val klass: JsClass) {
+    fun apply(): Boolean {
+        if (klass.constructor?.body?.statements?.isEmpty() != true) return false
+        klass.constructor = null
+        return true
+    }
+}

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/BoxJsTestGenerated.java

@@ -328,6 +328,12 @@ public class BoxJsTestGenerated extends AbstractBoxJsTest {
             runTest("js/js.translator/testData/box/classObject/objectInCompanionObject.kt");
         }
 
+        @Test
+        @TestMetadata("objectLazyInitialized.kt")
+        public void testObjectLazyInitialized() throws Exception {
+            runTest("js/js.translator/testData/box/classObject/objectLazyInitialized.kt");
+        }
+
         @Test
         @TestMetadata("setVar.kt")
         public void testSetVar() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/fir/FirJsBoxTestGenerated.java

@@ -328,6 +328,12 @@ public class FirJsBoxTestGenerated extends AbstractFirJsBoxTest {
             runTest("js/js.translator/testData/box/classObject/objectInCompanionObject.kt");
         }
 
+        @Test
+        @TestMetadata("objectLazyInitialized.kt")
+        public void testObjectLazyInitialized() throws Exception {
+            runTest("js/js.translator/testData/box/classObject/objectLazyInitialized.kt");
+        }
+
         @Test
         @TestMetadata("setVar.kt")
         public void testSetVar() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsES6TestGenerated.java

@@ -328,6 +328,12 @@ public class IrBoxJsES6TestGenerated extends AbstractIrBoxJsES6Test {
             runTest("js/js.translator/testData/box/classObject/objectInCompanionObject.kt");
         }
 
+        @Test
+        @TestMetadata("objectLazyInitialized.kt")
+        public void testObjectLazyInitialized() throws Exception {
+            runTest("js/js.translator/testData/box/classObject/objectLazyInitialized.kt");
+        }
+
         @Test
         @TestMetadata("setVar.kt")
         public void testSetVar() throws Exception {

js/js.tests/tests-gen/org/jetbrains/kotlin/js/test/ir/IrBoxJsTestGenerated.java

@@ -328,6 +328,12 @@ public class IrBoxJsTestGenerated extends AbstractIrBoxJsTest {
             runTest("js/js.translator/testData/box/classObject/objectInCompanionObject.kt");
         }
 
+        @Test
+        @TestMetadata("objectLazyInitialized.kt")
+        public void testObjectLazyInitialized() throws Exception {
+            runTest("js/js.translator/testData/box/classObject/objectLazyInitialized.kt");
+        }
+
         @Test
         @TestMetadata("setVar.kt")
         public void testSetVar() throws Exception {

js/js.translator/testData/box/classObject/objectLazyInitialized.kt

@@ -0,0 +1,55 @@
+// EXPECTED_REACHABLE_NODES: 1291
+// See KT-6201
+package foo
+
+import kotlin.reflect.KProperty
+
+var log = ""
+
+open class Mixin {
+    init {
+        log = "mixin"
+    }
+}
+
+fun initCall(): Number {
+    log = "initCall"
+    return 2
+}
+
+object O1 {
+    init {
+        log = "O1 init"
+    }
+}
+
+object O2 {
+    init {
+        initCall()
+    }
+}
+
+object O3 : Mixin()
+
+object O4 {
+    val someValue = initCall()
+}
+
+object O5 {
+    val someValue = O3.also { log = "O5 also" }
+}
+
+fun box(): String {
+    if (log != "") return "Fail: something was initialized before any object was used"
+    O1
+    if (log != "O1 init") return "Fail: O1 didn't initialized lazy"
+    O2
+    if (log != "initCall") return "Fail: O2 didn't initialized lazy"
+    O3
+    if (log != "mixin") return "Fail: O3 didn't initialized lazy"
+    O4
+    if (log != "initCall") return "Fail: O4 didn't initialized lazy"
+    O5
+    if (log != "O5 also") return "Fail: O5 didn't initialized lazy"
+    return "OK"
+}