Use receiver type of extension members as qualifier in Goto Symbol

#KT-17217 Fixed

idea/src/org/jetbrains/kotlin/idea/goto/gotoContributors.kt

@@ -1,22 +1,10 @@
 /*
- * Copyright 2010-2016 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
+ * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
  */
 
 package org.jetbrains.kotlin.idea.goto
 
-import com.intellij.navigation.ChooseByNameContributor
 import com.intellij.navigation.GotoClassContributor
 import com.intellij.navigation.NavigationItem
 import com.intellij.openapi.project.Project
@@ -25,8 +13,10 @@ import com.intellij.psi.stubs.StubIndex
 import org.jetbrains.kotlin.asJava.LightClassUtil
 import org.jetbrains.kotlin.idea.decompiler.builtIns.KotlinBuiltInFileType
 import org.jetbrains.kotlin.idea.stubindex.*
+import org.jetbrains.kotlin.psi.KtCallableDeclaration
 import org.jetbrains.kotlin.psi.KtEnumEntry
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
+import org.jetbrains.kotlin.psi.KtUserType
 import org.jetbrains.kotlin.psi.psiUtil.containingClass
 import java.util.*
 
@@ -61,7 +51,7 @@ class KotlinGotoClassContributor : GotoClassContributor {
 * For Kotlin classes it works using light class generation.
 * We have to process Kotlin builtIn classes separately since no light classes are built for them.
 * */
-class KotlinGotoSymbolContributor : ChooseByNameContributor {
+class KotlinGotoSymbolContributor : GotoClassContributor {
     override fun getNames(project: Project, includeNonProjectItems: Boolean): Array<String> {
         return listOf(
                 KotlinFunctionShortNameIndex.getInstance(),
@@ -93,4 +83,16 @@ class KotlinGotoSymbolContributor : ChooseByNameContributor {
 
         return result.toTypedArray()
     }
+
+    override fun getQualifiedName(item: NavigationItem): String? {
+        if (item is KtCallableDeclaration) {
+            val receiverType = (item.receiverTypeReference?.typeElement as? KtUserType)?.referencedName
+            if (receiverType != null) {
+                return "$receiverType.${item.name}"
+            }
+        }
+        return null
+    }
+
+    override fun getQualifiedNameSeparator(): String = "."
 }