Extract function: avoid same parameter names

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

@@ -126,6 +126,7 @@ internal fun ExtractionData.inferParametersInfo(
             NewDeclarationNameValidator.Target.VARIABLES
     )
 
+    val existingParameterNames = hashSetOf<String>()
     for ((descriptorToExtract, parameter) in extractedDescriptorToParameter) {
         if (!parameter
                 .getParameterType(options.allowSpecialClassNames)
@@ -135,8 +136,20 @@ internal fun ExtractionData.inferParametersInfo(
             if (currentName == null) {
                 currentName = KotlinNameSuggester.suggestNamesByType(getParameterType(options.allowSpecialClassNames), varNameValidator, "p").first()
             }
+
+            require(currentName != null)
+
+            if ("$currentName" in existingParameterNames) {
+                var index = 0
+                while ("$currentName$index" in existingParameterNames) {
+                    index++
+                }
+                currentName = "$currentName$index"
+            }
+
             mirrorVarName = if (descriptorToExtract in modifiedVarDescriptors) KotlinNameSuggester.suggestNameByName(name, varNameValidator) else null
             info.parameters.add(this)
+            currentName?.let { existingParameterNames += it }
         }
     }
 

idea/testData/debugger/tinyApp/src/evaluate/multipleBreakpoints/thisLabels.kt

@@ -27,5 +27,5 @@ fun <T> T.inlineBlock(t: T, block: T.() -> Unit) {
 // EXPRESSION: this
 // RESULT: 2: I
 
-// EXPRESSION: this@c
-// RESULT: 3: I
+// EXPRESSION: this + this@a + this@b + this@c
+// RESULT: 12: I

idea/testData/refactoring/extractFunction/basic/sameParameterNames.kt

@@ -0,0 +1,20 @@
+// SUGGESTED_NAMES: s, getA
+// PARAM_TYPES: kotlin.String
+// PARAM_TYPES: kotlin.String, kotlin.Comparable<kotlin.String>, kotlin.CharSequence, java.io.Serializable, kotlin.Any
+// PARAM_TYPES: kotlin.String, kotlin.Comparable<kotlin.String>, kotlin.CharSequence, java.io.Serializable, kotlin.Any
+// PARAM_DESCRIPTOR: local final fun kotlin.String.<anonymous>(): kotlin.Unit defined in Foo.foo.<anonymous>.<anonymous>, local final fun kotlin.String.<anonymous>(): kotlin.Unit defined in Foo.foo.<anonymous>, local final fun kotlin.String.<anonymous>(): kotlin.Unit defined in Foo.foo
+class Foo {
+    fun foo() {
+        block("a") a@ {
+            block("b") b@ {
+                block("c") c@ {
+                    val a = <selection>this@c + this@b + this@a + this + this@Foo.toString()</selection>
+                }
+            }
+        }
+    }
+}
+
+private inline fun <T> block(t: T, block: T.() -> Unit) {
+    t.block()
+}

idea/testData/refactoring/extractFunction/basic/sameParameterNames.kt.after

@@ -0,0 +1,22 @@
+// SUGGESTED_NAMES: s, getA
+// PARAM_TYPES: kotlin.String
+// PARAM_TYPES: kotlin.String, kotlin.Comparable<kotlin.String>, kotlin.CharSequence, java.io.Serializable, kotlin.Any
+// PARAM_TYPES: kotlin.String, kotlin.Comparable<kotlin.String>, kotlin.CharSequence, java.io.Serializable, kotlin.Any
+// PARAM_DESCRIPTOR: local final fun kotlin.String.<anonymous>(): kotlin.Unit defined in Foo.foo.<anonymous>.<anonymous>, local final fun kotlin.String.<anonymous>(): kotlin.Unit defined in Foo.foo.<anonymous>, local final fun kotlin.String.<anonymous>(): kotlin.Unit defined in Foo.foo
+class Foo {
+    fun foo() {
+        block("a") a@ {
+            block("b") b@ {
+                block("c") c@ {
+                    val a = s(this@c, this@b, this@a)
+                }
+            }
+        }
+    }
+
+    private fun s(s: String, s0: String, s1: String) = s + s0 + s1 + s + this@Foo.toString()
+}
+
+private inline fun <T> block(t: T, block: T.() -> Unit) {
+    t.block()
+}

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

@@ -996,6 +996,11 @@ public class ExtractionTestGenerated extends AbstractExtractionTest {
                 runTest("idea/testData/refactoring/extractFunction/basic/refInReturn.kt");
             }
 
+            @TestMetadata("sameParameterNames.kt")
+            public void testSameParameterNames() throws Exception {
+                runTest("idea/testData/refactoring/extractFunction/basic/sameParameterNames.kt");
+            }
+
             @TestMetadata("selectedConstructor.kt")
             public void testSelectedConstructor() throws Exception {
                 runTest("idea/testData/refactoring/extractFunction/basic/selectedConstructor.kt");