From cdef811c55a8aa441b36791fca7d5d44e2457a7c Mon Sep 17 00:00:00 2001
From: Mikhail Glukhikh <mikhail.glukhikh@jetbrains.com>
Date: Thu, 27 Dec 2018 14:16:36 +0300
Subject: [PATCH] Do not report "redundant arrow" with parameters without
 expected type

#KT-29049 Fixed
Part of KT-29005
---
 .../idea/inspections/RedundantLambdaArrowInspection.kt     | 7 +++++++
 .../redundantLambdaArrow/noExpectedType.kt                 | 5 +++++
 .../idea/inspections/LocalInspectionTestGenerated.java     | 5 +++++
 3 files changed, 17 insertions(+)
 create mode 100644 idea/testData/inspectionsLocal/redundantLambdaArrow/noExpectedType.kt

diff --git a/idea/src/org/jetbrains/kotlin/idea/inspections/RedundantLambdaArrowInspection.kt b/idea/src/org/jetbrains/kotlin/idea/inspections/RedundantLambdaArrowInspection.kt
index 5cf793380c5..7d89a0336f7 100644
--- a/idea/src/org/jetbrains/kotlin/idea/inspections/RedundantLambdaArrowInspection.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/inspections/RedundantLambdaArrowInspection.kt
@@ -14,10 +14,12 @@ import com.intellij.openapi.project.Project
 import com.intellij.openapi.util.TextRange
 import com.intellij.psi.PsiElementVisitor
 import org.jetbrains.kotlin.KtNodeTypes
+import org.jetbrains.kotlin.idea.caches.resolve.analyze
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.getStrictParentOfType
 import org.jetbrains.kotlin.psi.psiUtil.startOffset
+import org.jetbrains.kotlin.resolve.BindingContext
 import org.jetbrains.kotlin.resolve.calls.util.isSingleUnderscore
 
 class RedundantLambdaArrowInspection : AbstractKotlinInspection() {
@@ -42,6 +44,11 @@ class RedundantLambdaArrowInspection : AbstractKotlinInspection() {
                 if (callee != null && callee.getReferencedName() == "forEach" && singleParameter?.name != "it") return
             }
 
+            if (parameters.isNotEmpty()) {
+                val context = lambdaExpression.analyze()
+                if (context[BindingContext.EXPECTED_EXPRESSION_TYPE, lambdaExpression] == null) return
+            }
+
             val startOffset = functionLiteral.startOffset
             holder.registerProblem(
                 holder.manager.createProblemDescriptor(
diff --git a/idea/testData/inspectionsLocal/redundantLambdaArrow/noExpectedType.kt b/idea/testData/inspectionsLocal/redundantLambdaArrow/noExpectedType.kt
new file mode 100644
index 00000000000..6680c139887
--- /dev/null
+++ b/idea/testData/inspectionsLocal/redundantLambdaArrow/noExpectedType.kt
@@ -0,0 +1,5 @@
+// PROBLEM: none
+
+fun foo(x: Int) = x
+
+val x = { it: Int <caret>-> foo(it) }
\ No newline at end of file
diff --git a/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java b/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java
index b7bc4bcd650..c078a5d06c5 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java
+++ b/idea/tests/org/jetbrains/kotlin/idea/inspections/LocalInspectionTestGenerated.java
@@ -4938,6 +4938,11 @@ public class LocalInspectionTestGenerated extends AbstractLocalInspectionTest {
             runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/it.kt");
         }
 
+        @TestMetadata("noExpectedType.kt")
+        public void testNoExpectedType() throws Exception {
+            runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/noExpectedType.kt");
+        }
+
         @TestMetadata("simple.kt")
         public void testSimple() throws Exception {
             runTest("idea/testData/inspectionsLocal/redundantLambdaArrow/simple.kt");