Extract Function: Use intersection type to compute candidate types for parameters

#KT-8103 Fixed

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

@@ -75,6 +75,7 @@ import org.jetbrains.kotlin.resolve.scopes.receivers.ExpressionReceiver
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
 import org.jetbrains.kotlin.resolve.scopes.receivers.ThisReceiver
 import org.jetbrains.kotlin.types.*
+import org.jetbrains.kotlin.types.checker.JetTypeChecker
 import org.jetbrains.kotlin.utils.DFS
 import org.jetbrains.kotlin.utils.DFS.CollectingNodeHandler
 import org.jetbrains.kotlin.utils.DFS.Neighbors
@@ -512,7 +513,7 @@ private class MutableParameter(
 
     private val defaultType: JetType by Delegates.lazy {
         writable = false
-        CommonSupertypes.commonSupertype(defaultTypes)
+        TypeUtils.intersect(JetTypeChecker.DEFAULT, defaultTypes)
     }
 
     private val parameterTypeCandidates: List<JetType> by Delegates.lazy {

idea/testData/refactoring/extractFunction/parameters/candidateTypes/multipleTypes.kt

@@ -0,0 +1,12 @@
+// PARAM_TYPES: kotlin.String
+// PARAM_DESCRIPTOR: value-parameter val p: kotlin.Any defined in foo
+
+fun foo(p: Any) {
+    if (p is String) {
+        <selection>f(p)
+        g(p)</selection>
+    }
+}
+
+fun f(s: String){}
+fun g(o: Any){}

idea/testData/refactoring/extractFunction/parameters/candidateTypes/multipleTypes.kt.after

@@ -0,0 +1,16 @@
+// PARAM_TYPES: kotlin.String
+// PARAM_DESCRIPTOR: value-parameter val p: kotlin.Any defined in foo
+
+fun foo(p: Any) {
+    if (p is String) {
+        __dummyTestFun__(p)
+    }
+}
+
+private fun __dummyTestFun__(p: String) {
+    f(p)
+    g(p)
+}
+
+fun f(s: String){}
+fun g(o: Any){}

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

@@ -1622,6 +1622,12 @@ public class JetExtractionTestGenerated extends AbstractJetExtractionTest {
                     doExtractFunctionTest(fileName);
                 }
 
+                @TestMetadata("multipleTypes.kt")
+                public void testMultipleTypes() throws Exception {
+                    String fileName = JetTestUtils.navigationMetadata("idea/testData/refactoring/extractFunction/parameters/candidateTypes/multipleTypes.kt");
+                    doExtractFunctionTest(fileName);
+                }
+
                 @TestMetadata("nonNullableTypes.kt")
                 public void testNonNullableTypes() throws Exception {
                     String fileName = JetTestUtils.navigationMetadata("idea/testData/refactoring/extractFunction/parameters/candidateTypes/nonNullableTypes.kt");