Redundant lambda arrow: do not report on nested lambda

#KT-29093 Fixed

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

@@ -16,7 +16,9 @@ import com.intellij.psi.PsiElementVisitor
 import org.jetbrains.kotlin.KtNodeTypes
 import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.idea.caches.resolve.resolveToCall
+import org.jetbrains.kotlin.idea.search.usagesSearch.descriptor
 import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.psiUtil.anyDescendantOfType
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
@@ -59,6 +61,13 @@ class RedundantLambdaArrowInspection : AbstractKotlinInspection() {
                 if (argumentMatch?.valueParameter?.original?.type?.isTypeParameter() == true) return
             }
 
+            val functionLiteralDescriptor = functionLiteral.descriptor
+            if (functionLiteralDescriptor != null) {
+                if (functionLiteral.anyDescendantOfType<KtNameReferenceExpression> {
+                        it.text == "it" && it.resolveToCall()?.resultingDescriptor?.containingDeclaration != functionLiteralDescriptor
+                    }) return
+            }
+
             val startOffset = functionLiteral.startOffset
             holder.registerProblem(
                 holder.manager.createProblemDescriptor(

idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda.kt

@@ -0,0 +1,7 @@
+// PROBLEM: none
+// WITH_RUNTIME
+fun test() {
+    listOf("A").forEach {
+        setOf(1).map { <caret>_ -> it.length }
+    }
+}

idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda2.kt

@@ -0,0 +1,9 @@
+// PROBLEM: none
+// WITH_RUNTIME
+fun test() {
+    listOf("A").forEach {
+        listOf("B").forEach { _ ->
+            setOf(1).map { <caret>_ -> it.length }
+        }
+    }
+}

idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda3.kt

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+fun test() {
+    listOf("A").forEach {
+        setOf(1).map { <caret>_ ->
+            val it = "B"
+            it.length
+        }
+    }
+}

idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda3.kt.after

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+fun test() {
+    listOf("A").forEach {
+        setOf(1).map {
+            val it = "B"
+            it.length
+        }
+    }
+}

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

@@ -5009,6 +5009,21 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/it.kt");
         }
 
+        @TestMetadata("nestedLambda.kt")
+        public void testNestedLambda() throws Exception {
+            runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda.kt");
+        }
+
+        @TestMetadata("nestedLambda2.kt")
+        public void testNestedLambda2() throws Exception {
+            runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda2.kt");
+        }
+
+        @TestMetadata("nestedLambda3.kt")
+        public void testNestedLambda3() throws Exception {
+            runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/nestedLambda3.kt");
+        }
+
         @TestMetadata("noExpectedType.kt")
         public void testNoExpectedType() throws Exception {
             runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/noExpectedType.kt");