Change function signature: add/change receiver type

#KT-21799 Fixed

idea/src/org/jetbrains/kotlin/idea/quickfix/ChangeMemberFunctionSignatureFix.kt

@@ -338,8 +338,15 @@ class ChangeMemberFunctionSignatureFix private constructor(
                 } as KtParameterList
                 ShortenReferences.DEFAULT.process(newParameterList)
 
-                if (patternFunction.receiverTypeReference == null && function.receiverTypeReference != null) {
-                    function.setReceiverTypeReference(null)
+                val patternFunctionReceiver = patternFunction.receiverTypeReference
+                if (patternFunctionReceiver == null) {
+                    if (function.receiverTypeReference != null) {
+                        function.setReceiverTypeReference(null)
+                    }
+                } else {
+                    function.setReceiverTypeReference(patternFunction.receiverTypeReference)?.let {
+                        ShortenReferences.DEFAULT.process(it)
+                    }
                 }
 
                 val patternTypeParameterList = patternFunction.typeParameterList

idea/testData/quickfix/override/nothingToOverride/addFunctionReciever.kt

@@ -0,0 +1,8 @@
+// "Change function signature to 'fun Int.foo(a: String)'" "true"
+abstract class C {
+    abstract fun Int.foo(a: String)
+}
+
+class B : C() {
+    <caret>override fun foo(a: Int) {}
+}

idea/testData/quickfix/override/nothingToOverride/addFunctionReciever.kt.after

@@ -0,0 +1,8 @@
+// "Change function signature to 'fun Int.foo(a: String)'" "true"
+abstract class C {
+    abstract fun Int.foo(a: String)
+}
+
+class B : C() {
+    override fun Int.foo(a: String) {}
+}

idea/testData/quickfix/override/nothingToOverride/changeFunctionReciever.kt

@@ -0,0 +1,8 @@
+// "Change function signature to 'fun Int.foo(a: String)'" "true"
+abstract class C {
+    abstract fun Int.foo(a: String)
+}
+
+class B : C() {
+    <caret>override fun String.foo(a: Int) {}
+}

idea/testData/quickfix/override/nothingToOverride/changeFunctionReciever.kt.after

@@ -0,0 +1,8 @@
+// "Change function signature to 'fun Int.foo(a: String)'" "true"
+abstract class C {
+    abstract fun Int.foo(a: String)
+}
+
+class B : C() {
+    override fun Int.foo(a: String) {}
+}

idea/tests/org/jetbrains/kotlin/idea/quickfix/QuickFixTestGenerated.java

@@ -10162,6 +10162,11 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
                 runTest("idea/testData/quickfix/override/nothingToOverride/addFunctionNonUnitReturnType.kt");
             }
 
+            @TestMetadata("addFunctionReciever.kt")
+            public void testAddFunctionReciever() throws Exception {
+                runTest("idea/testData/quickfix/override/nothingToOverride/addFunctionReciever.kt");
+            }
+
             @TestMetadata("addFunctionSealedClass.kt")
             public void testAddFunctionSealedClass() throws Exception {
                 runTest("idea/testData/quickfix/override/nothingToOverride/addFunctionSealedClass.kt");
@@ -10226,6 +10231,11 @@ public class QuickFixTestGenerated extends AbstractQuickFixTest {
                 KotlinTestUtils.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("idea/testData/quickfix/override/nothingToOverride"), Pattern.compile("^([\\w\\-_]+)\\.kt$"), null, true);
             }
 
+            @TestMetadata("changeFunctionReciever.kt")
+            public void testChangeFunctionReciever() throws Exception {
+                runTest("idea/testData/quickfix/override/nothingToOverride/changeFunctionReciever.kt");
+            }
+
             @TestMetadata("changeParameterType.kt")
             public void testChangeParameterType() throws Exception {
                 runTest("idea/testData/quickfix/override/nothingToOverride/changeParameterType.kt");