[JS IR] Generate suspend function as invoke

[JS IR] Fix type check utils to work with array of arities

[JS IR] Store multiple arities for suspend functional interface implementers

^KT-46204 fixed

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

@@ -65,6 +65,8 @@ class JsIrBackendContext(
     val fileToInitializationFuns: MutableMap<IrFile, IrSimpleFunction?> = mutableMapOf()
     val fileToInitializerPureness: MutableMap<IrFile, Boolean> = mutableMapOf()
 
+    val suspendArityStore: MutableMap<IrDeclaration, Set<Int>> = mutableMapOf()
+
     val extractedLocalClasses: MutableSet<IrClass> = hashSetOf()
 
     override val builtIns = module.builtIns

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

@@ -19,6 +19,7 @@ import org.jetbrains.kotlin.ir.IrElement
 import org.jetbrains.kotlin.ir.backend.js.lower.*
 import org.jetbrains.kotlin.ir.backend.js.lower.calls.CallsLowering
 import org.jetbrains.kotlin.ir.backend.js.lower.cleanup.CleanupLowering
+import org.jetbrains.kotlin.ir.backend.js.lower.coroutines.JsSuspendArityStoreLowering
 import org.jetbrains.kotlin.ir.backend.js.lower.coroutines.JsSuspendFunctionsLowering
 import org.jetbrains.kotlin.ir.backend.js.lower.inline.CopyInlineFunctionBodyLowering
 import org.jetbrains.kotlin.ir.backend.js.lower.inline.RemoveInlineDeclarationsWithReifiedTypeParametersLowering
@@ -728,6 +729,12 @@ private val cleanupLoweringPhase = makeBodyLoweringPhase(
     description = "Clean up IR before codegen"
 )
 
+private val jsSuspendArityStorePhase = makeDeclarationTransformerPhase(
+    ::JsSuspendArityStoreLowering,
+    name = "JsSuspendArityStoreLowering",
+    description = "Store arity for suspend functions to not remove it during DCE"
+)
+
 private val loweringList = listOf<Lowering>(
     scriptRemoveReceiverLowering,
     validateIrBeforeLowering,
@@ -818,7 +825,8 @@ private val loweringList = listOf<Lowering>(
     captureStackTraceInThrowablesPhase,
     callsLoweringPhase,
     cleanupLoweringPhase,
-    validateIrAfterLowering
+    validateIrAfterLowering,
+    jsSuspendArityStorePhase
 )
 
 // TODO comment? Eliminate ModuleLowering's? Don't filter them here?

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

@@ -0,0 +1,29 @@
+/*
+ * Copyright 2010-2019 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.coroutines
+
+import org.jetbrains.kotlin.backend.common.DeclarationTransformer
+import org.jetbrains.kotlin.ir.backend.js.JsIrBackendContext
+import org.jetbrains.kotlin.ir.declarations.IrClass
+import org.jetbrains.kotlin.ir.declarations.IrDeclaration
+import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
+import kotlin.collections.set
+
+class JsSuspendArityStoreLowering(private val context: JsIrBackendContext) : DeclarationTransformer {
+    override fun transformFlat(declaration: IrDeclaration): List<IrDeclaration>? {
+        if (declaration !is IrClass) return null
+
+        declaration.declarations
+            .filterIsInstance<IrSimpleFunction>()
+            .filter { it.isSuspend }
+            .map { it.valueParameters.size }
+            .let {
+                context.suspendArityStore[declaration] = it.toSet()
+            }
+
+        return null
+    }
+}

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/JsClassGenerator.kt

@@ -165,7 +165,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
             declaration.realOverrideTarget.let {
                 val implClassDeclaration = it.parent as IrClass
 
-                if (implClassDeclaration.shouldCopyFrom()) {
+                if (implClassDeclaration.shouldCopyFrom() && !implClassDeclaration.defaultType.isFunctionType()) {
                     val implMethodName = context.getNameForMemberFunction(it)
                     val implClassName = context.getNameForClass(implClassDeclaration)
 
@@ -234,9 +234,12 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
 
     private fun isCoroutineClass(): Boolean = irClass.superTypes.any { it.isSuspendFunctionTypeOrSubtype() }
 
-    private fun generateSuspendArity(): JsPropertyInitializer {
-        val arity = irClass.declarations.filterIsInstance<IrSimpleFunction>().first { it.isSuspend }.valueParameters.size
-        return JsPropertyInitializer(JsNameRef(Namer.METADATA_SUSPEND_ARITY), JsIntLiteral(arity))
+    private fun generateSuspendArity(): JsPropertyInitializer? {
+        val arity = context.staticContext.backendContext.suspendArityStore
+            .getValue(irClass)
+            .map { JsIntLiteral(it) }
+
+        return JsPropertyInitializer(JsNameRef(Namer.METADATA_SUSPEND_ARITY), JsArrayLiteral(arity))
     }
 
     private fun generateSuperClasses(): JsPropertyInitializer {
@@ -245,7 +248,7 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
             JsArrayLiteral(
                 irClass.superTypes.mapNotNull {
                     val symbol = it.classifierOrFail as IrClassSymbol
-                    val isFunctionType = it.run { isFunctionOrKFunction() || isSuspendFunctionOrKFunction() }
+                    val isFunctionType = it.isFunctionType()
                     // TODO: make sure that there is a test which breaks when isExternal is used here instead of isEffectivelyExternal
                     val requireInMetadata = if (context.staticContext.backendContext.baseClassIntoMetadata)
                         !it.isAny()
@@ -260,6 +263,8 @@ class JsClassGenerator(private val irClass: IrClass, val context: JsGenerationCo
         )
     }
 
+    private fun IrType.isFunctionType() = isFunctionOrKFunction() || isSuspendFunctionOrKFunction()
+
     private fun generateAssociatedKeyProperties(): List<JsPropertyInitializer> {
         var result = emptyList<JsPropertyInitializer>()
 

compiler/ir/backend.js/src/org/jetbrains/kotlin/ir/backend/js/transformers/irToJs/jsAstUtils.kt

@@ -90,7 +90,8 @@ private fun isFunctionTypeInvoke(receiver: JsExpression?, call: IrCall): Boolean
 
     if (call.origin === JsStatementOrigins.EXPLICIT_INVOKE) return false
 
-    return simpleFunction.name == OperatorNameConventions.INVOKE && receiverType.isFunctionTypeOrSubtype()
+    return simpleFunction.name == OperatorNameConventions.INVOKE
+            && receiverType.isFunctionTypeOrSubtype()
 }
 
 fun translateCall(