Code cleanup: x as? Type ?: return -> if (x !is Type) return

idea/idea-analysis/src/org/jetbrains/kotlin/idea/framework/LibraryKinds.kt

@@ -52,7 +52,7 @@ val PersistentLibraryKind<*>?.platform: TargetPlatform
     }
 
 fun getLibraryPlatform(project: Project, library: Library): TargetPlatform {
-    library as? LibraryEx ?: return JvmPlatform
+    if (library !is LibraryEx) return JvmPlatform
     if (library.isDisposed) return JvmPlatform
 
     return library.effectiveKind(project).platform

idea/src/org/jetbrains/kotlin/idea/inspections/UnusedSymbolInspection.kt

@@ -351,7 +351,7 @@ class UnusedSymbolInspection : AbstractKotlinInspection() {
     private fun hasPlatformImplementations(declaration: KtNamedDeclaration, descriptor: DeclarationDescriptor?): Boolean {
         if (!declaration.hasExpectModifier()) return false
 
-        descriptor as? MemberDescriptor ?: return false
+        if (descriptor !is MemberDescriptor) return false
         val commonModuleDescriptor = declaration.containingKtFile.findModuleDescriptor()
 
         return commonModuleDescriptor.implementingDescriptors.any { it.hasActualsFor(descriptor) } ||

idea/src/org/jetbrains/kotlin/idea/inspections/UseExpressionBodyInspection.kt

@@ -60,7 +60,7 @@ class UseExpressionBodyInspection(private val convertEmptyToUnit: Boolean) : Abs
 
     override fun buildVisitor(holder: ProblemsHolder, isOnTheFly: Boolean) =
         declarationVisitor(fun(declaration) {
-            declaration as? KtDeclarationWithBody ?: return
+            if (declaration !is KtDeclarationWithBody) return
             val (toHighlightElement, suffix, highlightType) = statusFor(declaration) ?: return
             // Change range to start with left brace
             val hasHighlighting = highlightType != INFORMATION

idea/src/org/jetbrains/kotlin/idea/inspections/migration/ObsoleteExperimentalCoroutinesInspection.kt

@@ -44,7 +44,7 @@ class ObsoleteExperimentalCoroutinesInspection : AbstractKotlinInspection(), Cle
 
             when (simpleNameExpression.text) {
                 RESUME_MARKER, RESUME_WITH_EXCEPTION_MARKER -> {
-                    simpleNameExpression.parent as? KtCallExpression ?: return
+                    if (simpleNameExpression.parent !is KtCallExpression) return
 
                     val descriptor = simpleNameExpression.resolveMainReferenceToDescriptors().firstOrNull() ?: return
                     val callableDescriptor = descriptor as? CallableDescriptor ?: return
@@ -174,7 +174,7 @@ class ObsoleteExperimentalCoroutinesInspection : AbstractKotlinInspection(), Cle
 
                 override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
                     val element = descriptor.psiElement
-                    element as? KtSimpleNameExpression ?: return
+                    if (element !is KtSimpleNameExpression) return
 
                     val importFun =
                         KotlinTopLevelFunctionFqnNameIndex.getInstance()

idea/src/org/jetbrains/kotlin/idea/intentions/MoveMemberToTopLevelIntention.kt

@@ -60,7 +60,7 @@ class MoveMemberToTopLevelIntention : MoveMemberOutOfObjectIntention("Move to to
 
     override fun applicabilityRange(element: KtNamedDeclaration): TextRange? {
         if (element !is KtNamedFunction && element !is KtProperty) return null
-        element.containingClassOrObject as? KtObjectDeclaration ?: return null
+        if (element.containingClassOrObject !is KtObjectDeclaration) return null
         return element.nameIdentifier?.textRange
     }
 

idea/src/org/jetbrains/kotlin/idea/intentions/RemoveEmptyParenthesesFromLambdaCallIntention.kt

@@ -44,7 +44,7 @@ class RemoveEmptyParenthesesFromLambdaCallIntention : SelfTargetingRangeIntentio
         val parent = element.parent as? KtCallExpression ?: return null
         val singleLambdaArgument = parent.lambdaArguments.singleOrNull() ?: return null
         if (element.getLineNumber(start = false) != singleLambdaArgument.getLineNumber(start = true)) return null
-        element.getPrevSiblingIgnoringWhitespaceAndComments() as? KtCallExpression ?: return element.range
+        if (element.getPrevSiblingIgnoringWhitespaceAndComments() !is KtCallExpression) return element.range
         return null
     }
 

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

@@ -88,7 +88,7 @@ class ReplaceWithSafeCallFix(
                 return ReplaceWithSafeCallFix(qualifiedExpression, qualifiedExpression.shouldHaveNotNullType())
             }
             else {
-                psiElement as? KtNameReferenceExpression ?: return null
+                if (psiElement !is KtNameReferenceExpression) return null
                 if (psiElement.getResolvedCall(psiElement.analyze())?.getImplicitReceiverValue() != null) {
                     val expressionToReplace: KtExpression = psiElement.parent as? KtCallExpression ?: psiElement
                     return ReplaceImplicitReceiverCallFix(expressionToReplace, expressionToReplace.shouldHaveNotNullType())