Preview: replace apply with also where appropriate

compiler/backend/src/org/jetbrains/kotlin/codegen/inline/ObjectTransformer.kt

@@ -82,8 +82,8 @@ class WhenMappingTransformer(
             override fun visitMethod(
                     access: Int, name: String, desc: String, signature: String?, exceptions: Array<out String>?
             ): MethodVisitor? {
-                return MethodNode(access, name, desc, signature, exceptions).apply {
-                    methodNodes.add(this)
+                return MethodNode(access, name, desc, signature, exceptions).also {
+                    methodNodes.add(it)
                 }
             }
         }, ClassReader.SKIP_FRAMES)

compiler/backend/src/org/jetbrains/kotlin/codegen/optimization/boxing/RedundantCoercionToUnitTransformer.kt

@@ -220,7 +220,7 @@ class RedundantCoercionToUnitTransformer : MethodTransformer() {
                 REPLACE_WITH_NOP
 
         private fun createRemovableNopInsn() =
-                InsnNode(Opcodes.NOP).apply { removableNops.add(this) }
+                InsnNode(Opcodes.NOP).also { removableNops.add(it) }
 
         private fun getInputTop(insn: AbstractInsnNode): SourceValue {
             val i = insnList.indexOf(insn)

compiler/backend/src/org/jetbrains/kotlin/codegen/state/GenerationState.kt

@@ -176,7 +176,7 @@ class GenerationState @JvmOverloads constructor(
                     ::CoroutineTransformerClassBuilderFactory,
                     { BuilderFactoryForDuplicateSignatureDiagnostics(
                             it, this.bindingContext, diagnostics, fileClassesProvider, this.moduleName
-                      ).apply { duplicateSignatureFactory = this } },
+                      ).also { duplicateSignatureFactory = it } },
                     { BuilderFactoryForDuplicateClassNameDiagnostics(it, diagnostics) },
                     { configuration.get(JVMConfigurationKeys.DECLARATIONS_JSON_PATH)
                               ?.let { destination -> SignatureDumpingBuilderFactory(it, File(destination)) } ?: it }

compiler/builtins-serializer/src/org/jetbrains/kotlin/serialization/MetadataSerializer.kt

@@ -122,9 +122,9 @@ open class MetadataSerializer(private val dependOnOldBuiltIns: Boolean) {
         }
 
         val kotlinModuleFile = File(destDir, JvmCodegenUtil.getMappingFileName(JvmCodegenUtil.getModuleName(module)))
-        val packageTableBytes = JvmPackageTable.PackageTable.newBuilder().apply {
+        val packageTableBytes = JvmPackageTable.PackageTable.newBuilder().also {
             for (table in packageTable.values) {
-                table.addTo(this)
+                table.addTo(it)
             }
         }.serializeToByteArray()
 

compiler/cli/cli-common/src/org/jetbrains/kotlin/cli/common/arguments/argumentUtils.kt

@@ -50,9 +50,9 @@ private fun Any.copyValueIfNeeded(): Any {
         is DoubleArray -> Arrays.copyOf(this, size)
         is BooleanArray -> Arrays.copyOf(this, size)
 
-        is Array<*> -> java.lang.reflect.Array.newInstance(javaClass.componentType, size).apply {
-            this as Array<Any?>
-            (this@copyValueIfNeeded as Array<Any?>).forEachIndexed { i, value -> this[i] = value?.copyValueIfNeeded() }
+        is Array<*> -> java.lang.reflect.Array.newInstance(javaClass.componentType, size).also {
+            it as Array<Any?>
+            (this as Array<Any?>).forEachIndexed { i, value -> it[i] = value?.copyValueIfNeeded() }
         }
 
         is MutableCollection<*> -> (this as Collection<Any?>).mapTo(javaClass.newInstance() as MutableCollection<Any?>) { it?.copyValueIfNeeded() }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/ExpressionCodegen.kt

@@ -59,8 +59,8 @@ class BlockInfo private constructor(val parent: BlockInfo?) {
 
     private val infos = Stack<ExpressionInfo>()
 
-    fun create() = BlockInfo(this).apply {
-        this@apply.infos.addAll(this@BlockInfo.infos)
+    fun create() = BlockInfo(this).also {
+        it.infos.addAll(infos)
     }
 
     fun addInfo(loop: ExpressionInfo) {
@@ -210,8 +210,8 @@ class ExpressionCodegen(
                 gen(receiver, callable.dispatchReceiverType!!, data)
             }
 
-            expression.extensionReceiver?.apply {
-                gen(this, callable.extensionReceiverType!!, data)
+            expression.extensionReceiver?.also {
+                gen(it, callable.extensionReceiverType!!, data)
             }
 
             val args = expression.descriptor.valueParameters.mapIndexed { i, valueParameterDescriptor ->
@@ -266,8 +266,8 @@ class ExpressionCodegen(
         val varType = typeMapper.mapType(declaration.descriptor)
         val index = frame.enter(declaration.descriptor, varType)
 
-        declaration.initializer?.apply {
-            StackValue.local(index, varType).store(gen(this, varType, data), mv)
+        declaration.initializer?.also {
+            StackValue.local(index, varType).store(gen(it, varType, data), mv)
         }
 
         val info = VariableInfo(
@@ -323,8 +323,8 @@ class ExpressionCodegen(
     }
 
     private fun findLocalIndex(descriptor: CallableDescriptor): Int {
-        val index = frame.getIndex(descriptor).apply {
-            if (this < 0) throw AssertionError("Non-mapped local variable descriptor: $descriptor")
+        val index = frame.getIndex(descriptor).also {
+            if (it < 0) throw AssertionError("Non-mapped local variable descriptor: $descriptor")
         }
         return index
     }
@@ -464,12 +464,12 @@ class ExpressionCodegen(
 
 
     fun markNewLabel(): Label {
-        return Label().apply { mv.visitLabel(this) }
+        return Label().also { mv.visitLabel(it) }
     }
 
     override fun visitReturn(expression: IrReturn, data: BlockInfo): StackValue {
-        val value = expression.value.apply {
-            gen(this, returnType, data)
+        val value = expression.value.also {
+            gen(it, returnType, data)
         }
 
         val afterReturnLabel = Label()
@@ -502,8 +502,8 @@ class ExpressionCodegen(
 
         val end = Label()
 
-        thenBranch.apply {
-            gen(this, type, data)
+        thenBranch.also {
+            gen(it, type, data)
             //coerceNotToUnit(this.asmType, type)
         }
 
@@ -583,8 +583,8 @@ class ExpressionCodegen(
 
         with(LoopInfo(loop, continueLabel, endLabel)) {
             data.addInfo(this)
-            loop.body?.apply {
-                gen(this, data)
+            loop.body?.also {
+                gen(it, data)
             }
             data.removeInfo(this)
         }
@@ -641,8 +641,8 @@ class ExpressionCodegen(
 
         with(LoopInfo(loop, continueLabel, endLabel)) {
             data.addInfo(this)
-            loop.body?.apply {
-                gen(this, data)
+            loop.body?.also {
+                gen(it, data)
             }
             data.removeInfo(this)
         }

compiler/ir/backend.jvm/src/org/jetbrains/kotlin/backend/jvm/codegen/FunctionCodegen.kt

@@ -87,8 +87,7 @@ class FunctionCodegen(val irFunction: IrFunction, val classCodegen: ClassCodegen
         val directMember = JvmCodegenUtil.getDirectMember(descriptor)
         if (DescriptorUtils.isAnnotationClass(directMember.containingDeclaration)) {
             val source = directMember.source
-            (source.getPsi() as? KtParameter)?.defaultValue?.apply {
-                val defaultValue = this
+            (source.getPsi() as? KtParameter)?.defaultValue?.also { defaultValue ->
                 val constant = org.jetbrains.kotlin.codegen.ExpressionCodegen.getCompileTimeConstant(
                         defaultValue, state.bindingContext, true, state.shouldInlineConstVals)
                 assert(!state.classBuilderMode.generateBodies || constant != null) { "Default value for annotation parameter should be compile time value: " + defaultValue.getText() }

libraries/stdlib/src/kotlin/util/Standard.kt

@@ -48,13 +48,19 @@ public inline fun <T, R> with(receiver: T, block: T.() -> R): R = receiver.block
 @kotlin.internal.InlineOnly
 public inline fun <T> T.apply(block: T.() -> Unit): T { block(); return this }
 
+/**
+ * Calls the specified function [block] with `this` value as its argument and returns `this` value.
+ */
+@kotlin.internal.InlineOnly
+@SinceKotlin("1.1")
+public inline fun <T> T.also(block: (T) -> Unit): T { block(this); return this }
+
 /**
  * Calls the specified function [block] with `this` value as its argument and returns its result.
  */
 @kotlin.internal.InlineOnly
 public inline fun <T, R> T.let(block: (T) -> R): R = block(this)
 
-
 /**
  * Executes the given function [action] specified number of [times].
  *