Extract Function: Treat multi declarations as local variables

#KT-5054 Fixed

idea/src/org/jetbrains/jet/plugin/refactoring/extractFunction/extractFunctionUtils.kt

@@ -343,7 +343,9 @@ private fun ExtractionData.inferParametersInfo(
         else {
             val extractThis = hasThisReceiver || thisExpr != null
             val extractLocalVar =
-                    (originalDeclaration is JetProperty && originalDeclaration.isLocal()) || originalDeclaration is JetParameter
+                    originalDeclaration is JetMultiDeclarationEntry ||
+                            (originalDeclaration is JetProperty && originalDeclaration.isLocal()) ||
+                            originalDeclaration is JetParameter
 
             val descriptorToExtract = (if (extractThis) thisDescriptor else null) ?: originalDescriptor
 

idea/testData/refactoring/extractFunction/parameters/misc/multiDeclaration.kt

@@ -0,0 +1,7 @@
+// SIBLING:
+fun main(args: Array<String>) {
+    val (a, b) = Data(1, 2)
+    <selection>a</selection>
+}
+
+data class Data(val a: Int, val b: Int)

idea/testData/refactoring/extractFunction/parameters/misc/multiDeclaration.kt.after

@@ -0,0 +1,11 @@
+// SIBLING:
+fun main(args: Array<String>) {
+    val (a, b) = Data(1, 2)
+    unit(a)
+}
+
+fun unit(a: Int) {
+    a
+}
+
+data class Data(val a: Int, val b: Int)

idea/tests/org/jetbrains/jet/plugin/refactoring/introduce/introduceVariable/JetExtractionTestGenerated.java

@@ -724,6 +724,11 @@ public class JetExtractionTestGenerated extends AbstractJetExtractionTest {
                     doExtractFunctionTest("idea/testData/refactoring/extractFunction/parameters/misc/innerClassObject.kt");
                 }
                 
+                @TestMetadata("multiDeclaration.kt")
+                public void testMultiDeclaration() throws Exception {
+                    doExtractFunctionTest("idea/testData/refactoring/extractFunction/parameters/misc/multiDeclaration.kt");
+                }
+                
                 @TestMetadata("multipleOccurrences.kt")
                 public void testMultipleOccurrences() throws Exception {
                     doExtractFunctionTest("idea/testData/refactoring/extractFunction/parameters/misc/multipleOccurrences.kt");