[JS_IR] Invoke companion init block while instantiating a class

KT-40740, squashed rr/shagen/KT-40740-static-init-js-ir

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/JsLoweringPhases.kt

@@ -272,7 +272,6 @@ private val enumClassConstructorBodyLoweringPhase = makeBodyLoweringPhase(
     description = "Transform Enum Class into regular Class"
 )
 
-
 private val enumEntryInstancesLoweringPhase = makeDeclarationTransformerPhase(
     ::EnumEntryInstancesLowering,
     name = "EnumEntryInstancesLowering",
@@ -647,6 +646,13 @@ private val objectDeclarationLoweringPhase = makeDeclarationTransformerPhase(
     description = "Create lazy object instance generator functions"
 )
 
+private val invokeStaticInitializersPhase = makeBodyLoweringPhase(
+    ::InvokeStaticInitializersLowering,
+    name = "IntroduceStaticInitializersLowering",
+    description = "Invoke companion object's initializers from companion object in object constructor",
+    prerequisite = setOf(objectDeclarationLoweringPhase)
+)
+
 private val objectUsageLoweringPhase = makeBodyLoweringPhase(
     ::ObjectUsageLowering,
     name = "ObjectUsageLowering",
@@ -742,6 +748,7 @@ val loweringList = listOf<Lowering>(
     blockDecomposerLoweringPhase,
     constLoweringPhase,
     objectDeclarationLoweringPhase,
+    invokeStaticInitializersPhase,
     objectUsageLoweringPhase,
     captureStackTraceInThrowablesPhase,
     callsLoweringPhase,

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

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2010-2020 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.ir.backend.js.lower
+
+import org.jetbrains.kotlin.backend.common.BodyLoweringPass
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.declarations.IrConstructor
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.expressions.IrBody
+import org.jetbrains.kotlin.ir.expressions.IrStatementContainer
+import org.jetbrains.kotlin.ir.expressions.impl.IrCallImpl
+import org.jetbrains.kotlin.ir.util.companionObject
+import org.jetbrains.kotlin.ir.util.constructedClass
+import org.jetbrains.kotlin.ir.util.isEffectivelyExternal
+
+class InvokeStaticInitializersLowering(val context: JsIrBackendContext) : BodyLoweringPass {
+    override fun lower(irBody: IrBody, container: IrDeclaration) {
+        if (container !is IrConstructor) return
+
+        val irClass = container.constructedClass
+        if (irClass.isEffectivelyExternal()) {
+            return
+        }
+
+        val companionObject = irClass.companionObject() ?: return
+
+        val instance = context.mapping.objectToGetInstanceFunction[companionObject] ?: return
+
+        val getInstanceCall = IrCallImpl(irClass.startOffset, irClass.endOffset, context.irBuiltIns.unitType, instance.symbol, 0, 0)
+
+        (irBody as IrStatementContainer).statements.add(0, getInstanceCall)
+    }
+}

compiler/ir/ir.psi2ir/src/org/jetbrains/kotlin/psi2ir/generators/AnonymousInitializerGenerator.kt

@@ -16,8 +16,8 @@
 
 package org.jetbrains.kotlin.psi2ir.generators
 
+import org.jetbrains.kotlin.ir.declarations.IrAnonymousInitializer
 import org.jetbrains.kotlin.ir.declarations.IrClass
-import org.jetbrains.kotlin.ir.declarations.IrDeclaration
 import org.jetbrains.kotlin.ir.declarations.IrDeclarationOrigin
 import org.jetbrains.kotlin.psi.KtAnonymousInitializer
 import org.jetbrains.kotlin.psi.KtBlockExpression
@@ -31,7 +31,7 @@ class AnonymousInitializerGenerator(
     fun generateAnonymousInitializerDeclaration(
         ktAnonymousInitializer: KtAnonymousInitializer,
         irClass: IrClass
-    ): IrDeclaration =
+    ): IrAnonymousInitializer =
         context.symbolTable.declareAnonymousInitializer(
             ktAnonymousInitializer.startOffsetSkippingComments, ktAnonymousInitializer.endOffset,
             IrDeclarationOrigin.DEFINED, irClass.descriptor

compiler/testData/codegen/box/classes/classObjectAsStaticInitializer.kt

@@ -1,22 +1,28 @@
 // IGNORE_BACKEND: NATIVE
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-var global = 0;
+var global = "A"
 
 class C {
+  init {
+      global += "D"
+  }
+
   companion object {
       init {
-        global = 1;
+        global += "B"
+      }
+
+      init {
+          global += "C"
       }
   }
 }
 
 fun box(): String {
-  if (global != 0) {
+  if (global != "A") {
     return "fail1: global = $global"
   }
 
   val c = C()
-  if (global == 1) return "OK" else return "fail2: global = $global"
+  if (global == "ABCD") return "OK" else return "fail2: global = $global"
 }