Code cleanup: replace chained null-checks with safe-calls

compiler/frontend/src/org/jetbrains/kotlin/resolve/OverrideResolver.kt

@@ -809,7 +809,7 @@ class OverrideResolver(
 
         private fun findDataModifierForDataClass(dataClass: DeclarationDescriptor): PsiElement {
             val classDeclaration = DescriptorToSourceUtils.getSourceFromDescriptor(dataClass) as KtClassOrObject?
-            if (classDeclaration != null && classDeclaration.modifierList != null) {
+            if (classDeclaration?.modifierList != null) {
                 val modifier = classDeclaration.modifierList!!.getModifier(KtTokens.DATA_KEYWORD)
                 if (modifier != null) {
                     return modifier

core/descriptors/src/org/jetbrains/kotlin/types/VarianceChecker.kt

@@ -55,7 +55,7 @@ fun <D : TypeHolder<D>> D.checkTypePosition(
 
     var noError = true
     for (argument in arguments) {
-        if (argument == null || argument.typeParameter == null || argument.projection.isStarProjection) continue
+        if (argument?.typeParameter == null || argument.projection.isStarProjection) continue
 
         val projectionKind = TypeCheckingProcedure.getEffectiveProjectionKind(argument.typeParameter!!, argument.projection)!!
         val newPosition = when (projectionKind) {

idea/formatter/src/org/jetbrains/kotlin/idea/formatter/KotlinCommonBlock.kt

@@ -116,7 +116,7 @@ abstract class KotlinCommonBlock(
         val childParent = child.treeParent
         val childType = child.elementType
 
-        if (childParent != null && childParent.treeParent != null) {
+        if (childParent?.treeParent != null) {
             if (childParent.elementType === KtNodeTypes.BLOCK && childParent.treeParent.elementType === KtNodeTypes.SCRIPT) {
                 return Indent.getNoneIndent()
             }

idea/idea-completion/src/org/jetbrains/kotlin/idea/completion/KotlinCompletionCharFilter.kt

@@ -71,7 +71,7 @@ class KotlinCompletionCharFilter() : CharFilter() {
             }
 
             '{' -> {
-                if (currentItem != null && currentItem.getUserData(ACCEPT_OPENING_BRACE) != null)
+                if (currentItem?.getUserData(ACCEPT_OPENING_BRACE) != null)
                     Result.SELECT_ITEM_AND_FINISH_LOOKUP
                 else
                     Result.HIDE_LOOKUP

idea/idea-core/src/org/jetbrains/kotlin/idea/core/ExpectedInfos.kt

@@ -590,7 +590,7 @@ class ExpectedInfos(
         if (expressionWithType != forExpression.loopRange) return null
 
         val loopVar = forExpression.loopParameter
-        val loopVarType = if (loopVar != null && loopVar.typeReference != null)
+        val loopVarType = if (loopVar?.typeReference != null)
             (bindingContext[BindingContext.DECLARATION_TO_DESCRIPTOR, loopVar] as VariableDescriptor).type.takeUnless { it.isError }
         else
             null

idea/src/org/jetbrains/kotlin/idea/codeInliner/CodeInliner.kt

@@ -373,7 +373,7 @@ class CodeInliner<TCallElement : KtElement>(
             is VarargValueArgument -> {
                 val arguments = resolvedArgument.arguments
                 val single = arguments.singleOrNull()
-                if (single != null && single.getSpreadElement() != null) {
+                if (single?.getSpreadElement() != null) {
                     val expression = single.getArgumentExpression()!!.marked(USER_CODE_KEY)
                     return Argument(expression, bindingContext.getType(expression), isNamed = single.isNamed())
                 }

idea/src/org/jetbrains/kotlin/idea/quickfix/QuickFixFactoryForTypeMismatchError.kt

@@ -211,8 +211,7 @@ class QuickFixFactoryForTypeMismatchError : KotlinIntentionActionsFactory() {
                         val typeToInsert = valueArgumentType.approximateWithResolvableType(scope, true)
                         actions.add(ChangeParameterTypeFix(correspondingParameter, typeToInsert))
                     }
-                    if (correspondingParameterDescriptor != null
-                        && correspondingParameterDescriptor.varargElementType != null
+                    if (correspondingParameterDescriptor?.varargElementType != null
                         && KotlinBuiltIns.isArray(valueArgumentType)
                         && expressionType.arguments.isNotEmpty()
                         && expressionType.arguments[0].type.constructor == expectedType.constructor) {

idea/src/org/jetbrains/kotlin/idea/quickfix/RemoveNullableFix.kt

@@ -48,7 +48,7 @@ class RemoveNullableFix(element: KtNullableType,
     class Factory(private val typeOfError: NullableKind) : KotlinSingleIntentionActionFactory() {
         override fun createAction(diagnostic: Diagnostic): KotlinQuickFixAction<KtNullableType>? {
             val nullType = diagnostic.psiElement.getNonStrictParentOfType<KtNullableType>()
-            if (nullType == null || nullType.innerType == null) return null
+            if (nullType?.innerType == null) return null
             return RemoveNullableFix(nullType, typeOfError)
         }
     }

idea/src/org/jetbrains/kotlin/idea/quickfix/replaceWith/DeprecatedSymbolUsageFixBase.kt

@@ -53,7 +53,7 @@ abstract class DeprecatedSymbolUsageFixBase(
         val element = element ?: return false
         if (!super.isAvailable(project, editor, file)) return false
         val strategy = buildUsageReplacementStrategy(element, replaceWith, recheckAnnotation = true)
-        return strategy != null && strategy.createReplacer(element) != null
+        return strategy?.createReplacer(element) != null
     }
 
     final override fun invoke(project: Project, editor: Editor?, file: KtFile) {

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/introduceParameter/KotlinInplaceParameterIntroducer.kt

@@ -108,7 +108,7 @@ class KotlinInplaceParameterIntroducer(
 
         init {
             val templateState = TemplateManagerImpl.getTemplateState(myEditor)
-            val currentType = if (templateState != null && templateState.template != null) {
+            val currentType = if (templateState?.template != null) {
                 templateState
                         .getVariableValue(KotlinInplaceVariableIntroducer.TYPE_REFERENCE_VARIABLE_NAME)
                         ?.text

j2k/src/org/jetbrains/kotlin/j2k/StatementConverter.kt

@@ -98,7 +98,7 @@ class DefaultStatementConverter : JavaElementVisitor(), StatementConverter {
 
     override fun visitDoWhileStatement(statement: PsiDoWhileStatement) {
         val condition = statement.condition
-        val expression = if (condition != null && condition.type != null)
+        val expression = if (condition?.type != null)
             codeConverter.convertExpression(condition, condition.type)
         else
             codeConverter.convertExpression(condition)

plugins/android-extensions/android-extensions-compiler/src/org/jetbrains/kotlin/android/synthetic/res/AndroidLayoutXmlFileManager.kt

@@ -73,7 +73,7 @@ abstract class AndroidLayoutXmlFileManager(val project: Project) {
         val allLayoutFiles = allChildren.filter { it.parent.name.startsWith("layout") && it.name.toLowerCase().endsWith(".xml") }
         val allLayoutPsiFiles = allLayoutFiles.fold(ArrayList<PsiFile>(allLayoutFiles.size)) { list, file ->
             val psiFile = psiManager.findFile(file)
-            if (psiFile != null && psiFile.parent != null) {
+            if (psiFile?.parent != null) {
                 list += psiFile
             }
             list