Fix Can't rename implicit lambda parameter 'it' when caret is placed right after the last character

 #KT-14401 Fixed

Author: cypressious

idea/src/org/jetbrains/kotlin/idea/refactoring/rename/RenameKotlinImplicitLambdaParameter.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,17 +21,15 @@ import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.project.Project
 import com.intellij.psi.PsiElement
 import com.intellij.psi.PsiFile
-import com.intellij.psi.util.PsiTreeUtil
 import com.intellij.refactoring.rename.inplace.VariableInplaceRenameHandler
 import org.jetbrains.kotlin.idea.intentions.ReplaceItWithExplicitFunctionLiteralParamIntention
 import org.jetbrains.kotlin.idea.intentions.isAutoCreatedItUsage
 import org.jetbrains.kotlin.idea.util.application.executeWriteCommand
 import org.jetbrains.kotlin.psi.KtNameReferenceExpression
 
-class RenameKotlinImplicitLambdaParameter: VariableInplaceRenameHandler() {
+class RenameKotlinImplicitLambdaParameter : VariableInplaceRenameHandler() {
     override fun isAvailable(element: PsiElement?, editor: Editor, file: PsiFile): Boolean {
-        val nameExpression = PsiTreeUtil.findElementOfClassAtOffset(
-                file, editor.caretModel.offset, KtNameReferenceExpression::class.java, false)
+        val nameExpression = file.findElementForRename<KtNameReferenceExpression>(editor.caretModel.offset)
 
         return nameExpression != null && isAutoCreatedItUsage(nameExpression)
     }

idea/src/org/jetbrains/kotlin/idea/refactoring/rename/renameUtil.kt

@@ -1,5 +1,5 @@
 /*
- * Copyright 2010-2015 JetBrains s.r.o.
+ * Copyright 2010-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -17,6 +17,8 @@
 package org.jetbrains.kotlin.idea.refactoring.rename
 
 import com.intellij.psi.PsiElement
+import com.intellij.psi.PsiFile
+import com.intellij.psi.util.PsiTreeUtil
 import com.intellij.refactoring.rename.ResolvableCollisionUsageInfo
 import com.intellij.refactoring.rename.UnresolvableCollisionUsageInfo
 import com.intellij.refactoring.util.MoveRenameUsageInfo
@@ -79,4 +81,9 @@ class LostDefaultValuesInOverridingFunctionUsageInfo(
             subParam.addRange(superParam.equalsToken, defaultValue)
         }
     }
+}
+
+inline fun <reified T : PsiElement> PsiFile.findElementForRename(offset: Int): T? {
+    return PsiTreeUtil.findElementOfClassAtOffset(this, offset, T::class.java, false)
+           ?: PsiTreeUtil.findElementOfClassAtOffset(this, (offset - 1).coerceAtLeast(0), T::class.java, false)
 }

idea/testData/refactoring/rename/inplace/FunctionLiteralItEndCaret.kt

@@ -0,0 +1,3 @@
+fun f() {
+    val f: (Int) -> Int = { it<caret> + it }
+}

idea/testData/refactoring/rename/inplace/FunctionLiteralItEndCaret.kt.after

@@ -0,0 +1,3 @@
+fun f() {
+    val f: (Int) -> Int = { y -> y + y }
+}

idea/tests/org/jetbrains/kotlin/idea/refactoring/InplaceRenameTest.kt

@@ -28,6 +28,8 @@ import org.jetbrains.kotlin.idea.refactoring.rename.RenameKotlinImplicitLambdaPa
 import com.intellij.codeInsight.template.impl.TemplateManagerImpl
 import com.intellij.codeInsight.template.TemplateManager
 import com.intellij.openapi.command.WriteCommandAction
+import org.jetbrains.kotlin.idea.refactoring.rename.findElementForRename
+import org.jetbrains.kotlin.psi.KtNameReferenceExpression
 
 class InplaceRenameTest : LightPlatformCodeInsightTestCase() {
     override fun isRunInWriteAction(): Boolean = false
@@ -50,19 +52,58 @@ class InplaceRenameTest : LightPlatformCodeInsightTestCase() {
     }
 
     fun testFunctionLiteralIt() {
+        doTestImplicitLambdaParameter("y")
+    }
+
+    fun testFunctionLiteralItEndCaret() {
+        doTestImplicitLambdaParameter("y")
+    }
+
+    fun testFunctionLiteralParenthesis() {
+        doTestInplaceRename("y")
+    }
+
+    fun testLocalFunction() {
+        doTestInplaceRename("bar")
+    }
+
+    fun testFunctionParameterNotInplace() {
+        doTestInplaceRename(null)
+    }
+
+    fun testGlobalFunctionNotInplace() {
+        doTestInplaceRename(null)
+    }
+
+    fun testTopLevelValNotInplace() {
+        doTestInplaceRename(null)
+    }
+
+    fun testLabelFromFunction() {
+        doTestInplaceRename("foo")
+    }
+
+    fun testMultiDeclaration() {
+        doTestInplaceRename("foo")
+    }
+
+    fun testLocalVarShadowingMemberProperty() {
+        doTestInplaceRename("name1")
+    }
+
+    private fun doTestImplicitLambdaParameter(newName: String) {
         configureByFile(getTestName(false) + ".kt")
-        val newName = "y"
 
         // This code is copy-pasted from CodeInsightTestUtil.doInlineRename() and slightly modified.
         // Original method was not suitable because it expects renamed element to be reference to other or referrable
 
-        val file = LightPlatformCodeInsightTestCase.getFile()!!
-        val editor = LightPlatformCodeInsightTestCase.getEditor()!!
-        val element = file.findReferenceAt(editor.caretModel.offset)!!.element
+        val file = getFile()!!
+        val editor = getEditor()!!
+        val element = file.findElementForRename<KtNameReferenceExpression>(editor.caretModel.offset)!!
         assertNotNull(element)
 
         val dataContext = SimpleDataContext.getSimpleContext(CommonDataKeys.PSI_ELEMENT.name, element!!,
-                                                             LightPlatformCodeInsightTestCase.getCurrentEditorDataContext())
+                                                             getCurrentEditorDataContext())
         val handler = RenameKotlinImplicitLambdaParameter()
 
         assertTrue(handler.isRenaming(dataContext), "In-place rename not allowed for " + element)
@@ -100,38 +141,6 @@ class InplaceRenameTest : LightPlatformCodeInsightTestCase() {
         checkResultByFile(getTestName(false) + ".kt.after")
     }
 
-    fun testFunctionLiteralParenthesis() {
-        doTestInplaceRename("y")
-    }
-
-    fun testLocalFunction() {
-        doTestInplaceRename("bar")
-    }
-
-    fun testFunctionParameterNotInplace() {
-        doTestInplaceRename(null)
-    }
-
-    fun testGlobalFunctionNotInplace() {
-        doTestInplaceRename(null)
-    }
-
-    fun testTopLevelValNotInplace() {
-        doTestInplaceRename(null)
-    }
-
-    fun testLabelFromFunction() {
-        doTestInplaceRename("foo")
-    }
-
-    fun testMultiDeclaration() {
-        doTestInplaceRename("foo")
-    }
-
-    fun testLocalVarShadowingMemberProperty() {
-        doTestInplaceRename("name1")
-    }
-
     private fun doTestInplaceRename(newName: String?) {
         configureByFile(getTestName(false) + ".kt")
         val element = TargetElementUtilBase.findTargetElement(