Extract property: do not suggest duplicate property name

#KT-36504 Fixed

idea/src/org/jetbrains/kotlin/idea/refactoring/introduce/extractionEngine/extractorUtil.kt

@@ -16,6 +16,7 @@ import com.intellij.refactoring.BaseRefactoringProcessor
 import org.jetbrains.kotlin.builtins.KotlinBuiltIns
 import org.jetbrains.kotlin.builtins.isFunctionType
 import org.jetbrains.kotlin.descriptors.ClassDescriptor
+import org.jetbrains.kotlin.descriptors.PropertyDescriptor
 import org.jetbrains.kotlin.descriptors.Visibilities
 import org.jetbrains.kotlin.idea.core.*
 import org.jetbrains.kotlin.idea.core.util.isMultiLine
@@ -29,11 +30,15 @@ import org.jetbrains.kotlin.idea.refactoring.introduce.*
 import org.jetbrains.kotlin.idea.refactoring.introduce.extractionEngine.OutputValue.*
 import org.jetbrains.kotlin.idea.refactoring.introduce.extractionEngine.OutputValueBoxer.AsTuple
 import org.jetbrains.kotlin.idea.refactoring.removeTemplateEntryBracesIfPossible
+import org.jetbrains.kotlin.idea.search.usagesSearch.descriptor
 import org.jetbrains.kotlin.idea.util.IdeDescriptorRenderers
+import org.jetbrains.kotlin.idea.util.getAllAccessibleVariables
+import org.jetbrains.kotlin.idea.util.getResolutionScope
 import org.jetbrains.kotlin.idea.util.psi.patternMatching.*
 import org.jetbrains.kotlin.idea.util.psi.patternMatching.UnificationResult.StronglyMatched
 import org.jetbrains.kotlin.idea.util.psi.patternMatching.UnificationResult.WeaklyMatched
 import org.jetbrains.kotlin.lexer.KtTokens
+import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.psi.*
 import org.jetbrains.kotlin.psi.KtPsiFactory.CallableBuilder
 import org.jetbrains.kotlin.psi.psiUtil.*
@@ -681,10 +686,19 @@ fun ExtractionGeneratorConfiguration.generateDeclaration(
         }
     }
 
-    if (declaration is KtProperty && declaration.isExtensionDeclaration() && !declaration.isTopLevel) {
-        val receiverTypeReference = (declaration as? KtCallableDeclaration)?.receiverTypeReference
-        receiverTypeReference?.siblings(withItself = false)?.firstOrNull { it.node.elementType == KtTokens.DOT }?.delete()
-        receiverTypeReference?.delete()
+    if (declaration is KtProperty) {
+        if (declaration.isExtensionDeclaration() && !declaration.isTopLevel) {
+            val receiverTypeReference = (declaration as? KtCallableDeclaration)?.receiverTypeReference
+            receiverTypeReference?.siblings(withItself = false)?.firstOrNull { it.node.elementType == KtTokens.DOT }?.delete()
+            receiverTypeReference?.delete()
+        }
+        if ((declaration.descriptor as? PropertyDescriptor)?.let { DescriptorUtils.isOverride(it) } == true) {
+            val scope = declaration.getResolutionScope()
+            val newName = KotlinNameSuggester.suggestNameByName(descriptor.name) {
+                it != descriptor.name && scope.getAllAccessibleVariables(Name.identifier(it)).isEmpty()
+            }
+            declaration.setName(newName)
+        }
     }
 
     CodeStyleManager.getInstance(descriptor.extractionData.project).reformat(declaration)

idea/testData/refactoring/introduceProperty/conflictWithParentClass.kt

@@ -0,0 +1,8 @@
+// EXTRACTION_TARGET: property with initializer
+open class Base(protected val i: Int)
+
+class Impl(z: Int) : Base(z) {
+    fun foo(): Int {
+        return <selection>2 + 3 + i</selection>
+    }
+}

idea/testData/refactoring/introduceProperty/conflictWithParentClass.kt.after

@@ -0,0 +1,10 @@
+// EXTRACTION_TARGET: property with initializer
+open class Base(protected val i: Int)
+
+class Impl(z: Int) : Base(z) {
+    private val i1 = 2 + 3 + i
+
+    fun foo(): Int {
+        return i1
+    }
+}

idea/testData/refactoring/introduceProperty/kt24615.kt.after

@@ -3,10 +3,10 @@
 open class Base(protected val i: Int)
 
 class Impl(i: Int) : Base(i) {
-    private val i: Int
+    private val i1: Int
         get() = 2 + 3 + i
 
     fun foo(): Int {
-        return i
+        return i1
     }
 }

idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/ExtractionTestGenerated.java

@@ -2787,6 +2787,11 @@ public class ExtractionTestGenerated extends AbstractExtractionTest {
             KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/refactoring/introduceProperty"), Pattern.compile("^(.+)\\.(kt|kts)$"), null, true);
         }
 
+        @TestMetadata("conflictWithParentClass.kt")
+        public void testConflictWithParentClass() throws Exception {
+            runTest("idea/testData/refactoring/introduceProperty/conflictWithParentClass.kt");
+        }
+
         @TestMetadata("extractExtensionWithInitializer.kt")
         public void testExtractExtensionWithInitializer() throws Exception {
             runTest("idea/testData/refactoring/introduceProperty/extractExtensionWithInitializer.kt");