Support listOfNotNull in SimplifiableCallChainInspection #KT-20410 Fixed

idea/src/org/jetbrains/kotlin/idea/inspections/collections/SimplifiableCallChainInspection.kt

@@ -23,6 +23,7 @@ import org.jetbrains.kotlin.idea.inspections.AbstractKotlinInspection
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.calls.callUtil.getResolvedCall
 import org.jetbrains.kotlin.resolve.calls.model.DefaultValueArgument
 import org.jetbrains.kotlin.resolve.descriptorUtil.fqNameOrNull
@@ -37,8 +38,9 @@ class SimplifiableCallChainInspection : AbstractKotlinInspection() {
                 override fun visitQualifiedExpression(expression: KtQualifiedExpression) {
                     super.visitQualifiedExpression(expression)
 
-                    val firstQualifiedExpression = expression.receiverExpression as? KtQualifiedExpression ?: return
-                    val firstCallExpression = firstQualifiedExpression.selectorExpression as? KtCallExpression ?: return
+                    val firstExpression = expression.receiverExpression
+                    val firstCallExpression = getCallExpression(firstExpression) ?: return
+
                     val secondCallExpression = expression.selectorExpression as? KtCallExpression ?: return
 
                     val firstCalleeExpression = firstCallExpression.calleeExpression ?: return
@@ -48,15 +50,20 @@ class SimplifiableCallChainInspection : AbstractKotlinInspection() {
                             ] ?: return
 
                     val context = expression.analyze()
-                    val firstResolvedCall = firstQualifiedExpression.getResolvedCall(context) ?: return
+                    val firstResolvedCall = firstExpression.getResolvedCall(context) ?: return
                     val conversion = actualConversions.firstOrNull {
                         firstResolvedCall.resultingDescriptor.fqNameOrNull()?.asString() == it.firstFqName
                     } ?: return
+
+                    val builtIns = context[BindingContext.EXPRESSION_TYPE_INFO, expression]?.type?.builtIns ?: return
+
                     // Do not apply on maps due to lack of relevant stdlib functions
-                    val firstReceiverType = firstResolvedCall.extensionReceiver?.type ?: return
-                    val builtIns = firstReceiverType.builtIns
-                    val mapType = builtIns.map.defaultType
-                    if (firstReceiverType.isSubtypeOf(mapType)) return
+                    val firstReceiverType = firstResolvedCall.extensionReceiver?.type
+                    if (firstReceiverType != null) {
+                        val mapType = builtIns.map.defaultType
+                        if (firstReceiverType.isSubtypeOf(mapType)) return
+                    }
+
                     // Do not apply for lambdas with return inside
                     val lambdaArgument = firstCallExpression.lambdaArguments.firstOrNull()
                     if (lambdaArgument?.anyDescendantOfType<KtReturnExpression>() == true) return
@@ -111,7 +118,9 @@ class SimplifiableCallChainInspection : AbstractKotlinInspection() {
 
                 Conversion("kotlin.collections.map", "kotlin.collections.joinTo", "joinTo"),
                 Conversion("kotlin.collections.map", "kotlin.collections.joinToString", "joinToString"),
-                Conversion("kotlin.collections.map", "kotlin.collections.filterNotNull", "mapNotNull")
+                Conversion("kotlin.collections.map", "kotlin.collections.filterNotNull", "mapNotNull"),
+
+                Conversion("kotlin.collections.listOf", "kotlin.collections.filterNotNull", "listOfNotNull")
         )
 
         private val conversionGroups = conversions.groupBy { it.firstName to it.secondName }
@@ -124,5 +133,9 @@ class SimplifiableCallChainInspection : AbstractKotlinInspection() {
             val secondName = secondFqName.convertToShort()
         }
 
+        fun getCallExpression(firstExpression: KtExpression) =
+                ((firstExpression as? KtQualifiedExpression)?.selectorExpression as? KtCallExpression
+                 ?: firstExpression as? KtCallExpression)
+
     }
 }

idea/src/org/jetbrains/kotlin/idea/inspections/collections/SimplifyCallChainFix.kt

@@ -31,20 +31,28 @@ class SimplifyCallChainFix(val newName: String) : LocalQuickFix {
     override fun applyFix(project: Project, descriptor: ProblemDescriptor) {
         (descriptor.psiElement as? KtQualifiedExpression)?.let { secondQualifiedExpression ->
             val factory = KtPsiFactory(secondQualifiedExpression)
-            val firstQualifiedExpression = secondQualifiedExpression.receiverExpression as? KtQualifiedExpression ?: return
-            val operationSign = if (firstQualifiedExpression is KtSafeQualifiedExpression) "?." else "."
-            val firstCallExpression = firstQualifiedExpression.selectorExpression as? KtCallExpression ?: return
+            val firstExpression = secondQualifiedExpression.receiverExpression
+
+            val operationSign = when (firstExpression) {
+                is KtSafeQualifiedExpression -> "?."
+                is KtQualifiedExpression -> "."
+                else -> ""
+            }
+
+            val receiverExpression = (firstExpression as? KtQualifiedExpression)?.receiverExpression
+
+            val firstCallExpression = SimplifiableCallChainInspection.getCallExpression(firstExpression) ?: return
             val secondCallExpression = secondQualifiedExpression.selectorExpression as? KtCallExpression ?: return
 
             val lastArgumentPrefix = if (newName.startsWith("joinTo")) "transform = " else ""
             val arguments = secondCallExpression.valueArgumentList?.arguments.orEmpty().map { it.text } +
-                            firstCallExpression.valueArgumentList?.arguments.orEmpty().map { "$lastArgumentPrefix${it.text}"}
+                            firstCallExpression.valueArgumentList?.arguments.orEmpty().map { "$lastArgumentPrefix${it.text}" }
             val lambdaArgument = firstCallExpression.lambdaArguments.singleOrNull()
 
             val argumentsText = arguments.ifNotEmpty { joinToString(prefix = "(", postfix = ")") } ?: ""
             val newQualifiedExpression = if (lambdaArgument != null) factory.createExpressionByPattern(
                     "$0$1$2 $3 $4",
-                    firstQualifiedExpression.receiverExpression,
+                    receiverExpression ?: "",
                     operationSign,
                     newName,
                     argumentsText,
@@ -52,7 +60,7 @@ class SimplifyCallChainFix(val newName: String) : LocalQuickFix {
             )
             else factory.createExpressionByPattern(
                     "$0$1$2 $3",
-                    firstQualifiedExpression.receiverExpression,
+                    receiverExpression ?: "",
                     operationSign,
                     newName,
                     argumentsText

idea/testData/inspectionsLocal/collections/simplifiableCallChain/listOfNotNull.kt

@@ -0,0 +1,4 @@
+// WITH_RUNTIME
+
+val s: String? = null
+val x = <caret>listOf(s).filterNotNull()

idea/testData/inspectionsLocal/collections/simplifiableCallChain/listOfNotNull.kt.after

@@ -0,0 +1,4 @@
+// WITH_RUNTIME
+
+val s: String? = null
+val x = <caret>listOfNotNull(s)

idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java

@@ -250,6 +250,12 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
                 doTest(fileName);
             }
 
+            @TestMetadata("listOfNotNull.kt")
+            public void testListOfNotNull() throws Exception {
+                String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/collections/simplifiableCallChain/listOfNotNull.kt");
+                doTest(fileName);
+            }
+
             @TestMetadata("mapNotNull.kt")
             public void testMapNotNull() throws Exception {
                 String fileName = KotlinTestUtils.navigationMetadata("idea/testData/inspectionsLocal/collections/simplifiableCallChain/mapNotNull.kt");