Extract Function: Fix 'this' label (extension case)

#KT-5456 Fixed

idea/src/org/jetbrains/kotlin/idea/refactoring/extractFunction/extractableAnalysisUtil.kt

@@ -622,8 +622,10 @@ private fun ExtractionData.inferParametersInfo(
 
                 val parameter = extractedDescriptorToParameter.getOrPut(descriptorToExtract) {
                     val argumentText =
-                            if (hasThisReceiver && extractThis)
-                                "this@${parameterType.getConstructor().getDeclarationDescriptor()!!.getName().asString()}"
+                            if (hasThisReceiver && extractThis) {
+                                val label = if (descriptorToExtract is ClassDescriptor) "@${descriptorToExtract.getName().asString()}" else ""
+                                "this$label"
+                            }
                             else
                                 (thisExpr ?: ref).getText() ?: throw AssertionError("'this' reference shouldn't be empty: code fragment = ${getCodeFragmentText()}")
 

idea/testData/refactoring/extractFunction/parameters/extractThis/qualifiedThisAsArgument.kt

@@ -0,0 +1,14 @@
+// PARAM_TYPES: A
+// PARAM_TYPES: B
+// PARAM_DESCRIPTOR: internal final class A defined in root package
+// PARAM_DESCRIPTOR: internal final fun B.foo(): Int defined in A
+// SIBLING:
+class A {
+    val a = 1
+
+    fun B.foo() = <selection>a + b</selection>
+}
+
+class B {
+    val b = 1
+}

idea/testData/refactoring/extractFunction/parameters/extractThis/qualifiedThisAsArgument.kt.after

@@ -0,0 +1,18 @@
+// PARAM_TYPES: A
+// PARAM_TYPES: B
+// PARAM_DESCRIPTOR: internal final class A defined in root package
+// PARAM_DESCRIPTOR: internal final fun B.foo(): Int defined in A
+// SIBLING:
+class A {
+    val a = 1
+
+    fun B.foo() = i(this@A, this)
+}
+
+private fun i(a1: A, b: B): Int {
+    return a1.a + b.b
+}
+
+class B {
+    val b = 1
+}

idea/tests/org/jetbrains/kotlin/idea/refactoring/introduce/introduceVariable/JetExtractionTestGenerated.java

@@ -1639,6 +1639,12 @@ public class JetExtractionTestGenerated extends AbstractJetExtractionTest {
                     String fileName = JetTestUtils.navigationMetadata("idea/testData/refactoring/extractFunction/parameters/extractThis/implicitThisInMember.kt");
                     doExtractFunctionTest(fileName);
                 }
+
+                @TestMetadata("qualifiedThisAsArgument.kt")
+                public void testQualifiedThisAsArgument() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("idea/testData/refactoring/extractFunction/parameters/extractThis/qualifiedThisAsArgument.kt");
+                    doExtractFunctionTest(fileName);
+                }
             }
 
             @TestMetadata("idea/testData/refactoring/extractFunction/parameters/it")