[JS IR] Eager initialisation for all pure properties

^KT-43222 fixed

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/lower/PropertyLazyInitLowering.kt

@@ -40,7 +40,14 @@ class PropertyLazyInitLowering(private val context: JsIrBackendContext) : FileLo
 
         val fieldToInitializer = calculateFieldToExpression(
             functions
-        ).onEach { it.key.initializer = null }
+        )
+
+        val allPropertyInitializersPure = fieldToInitializer
+            .all { it.value.isPure(anyVariable = true) }
+
+        if (allPropertyInitializersPure) return
+
+        fieldToInitializer.onEach { it.key.initializer = null }
 
         if (fieldToInitializer.isEmpty()) return
 

compiler/testData/codegen/box/properties/lazyInitializationPure.kt

@@ -0,0 +1,18 @@
+// TARGET_BACKEND: JS_IR
+
+// FILE: A.kt
+
+val a = "A"
+
+// FILE: B.kt
+val b = "B".apply {}
+
+val c = "C"
+
+// FILE: main.kt
+
+fun box(): String {
+    return if (js("a") == "A" && js("typeof b") == "undefined" && js("typeof c") == "undefined")
+        "OK"
+    else "fail"
+}

js/js.tests/test/org/jetbrains/kotlin/js/test/es6/semantics/IrJsCodegenBoxES6TestGenerated.java

@@ -17634,6 +17634,11 @@ public class IrJsCodegenBoxES6TestGenerated extends AbstractIrJsCodegenBoxES6Tes
             runTest("compiler/testData/codegen/box/properties/lazyInitialization.kt");
         }
 
+        @TestMetadata("lazyInitializationPure.kt")
+        public void testLazyInitializationPure() throws Exception {
+            runTest("compiler/testData/codegen/box/properties/lazyInitializationPure.kt");
+        }
+
         @TestMetadata("primitiveOverrideDefaultAccessor.kt")
         public void testPrimitiveOverrideDefaultAccessor() throws Exception {
             runTest("compiler/testData/codegen/box/properties/primitiveOverrideDefaultAccessor.kt");

js/js.tests/test/org/jetbrains/kotlin/js/test/ir/semantics/IrJsCodegenBoxTestGenerated.java

@@ -17634,6 +17634,11 @@ public class IrJsCodegenBoxTestGenerated extends AbstractIrJsCodegenBoxTest {
             runTest("compiler/testData/codegen/box/properties/lazyInitialization.kt");
         }
 
+        @TestMetadata("lazyInitializationPure.kt")
+        public void testLazyInitializationPure() throws Exception {
+            runTest("compiler/testData/codegen/box/properties/lazyInitializationPure.kt");
+        }
+
         @TestMetadata("primitiveOverrideDefaultAccessor.kt")
         public void testPrimitiveOverrideDefaultAccessor() throws Exception {
             runTest("compiler/testData/codegen/box/properties/primitiveOverrideDefaultAccessor.kt");