Temporarily disabled optimization for faster non-imported extensions completion because it causes duplicated items, added test for this problem

idea/src/org/jetbrains/jet/plugin/caches/KotlinIndicesHelper.kt

@@ -199,12 +199,13 @@ public class KotlinIndicesHelper(private val project: Project,
                                        module: ModuleDescriptor,
                                        bindingContext: BindingContext): Collection<CallableDescriptor> {
         val fqnString = callableFQN.asString()
-        val descriptors = if (index != null) {
+        val descriptors = /* this code is temporarily disabled because taking descriptors from another resolve session causes duplicates and potentially other problems*/
+        /*if (index != null) {
             index.get(fqnString, project, scope)
                     .filter { it.getReceiverTypeReference() != null }
                     .map { it.getLazyResolveSession().resolveToDescriptor(it) as CallableDescriptor }
         }
-        else {
+        else*/ run {
             val importDirective = JetPsiFactory(project).createImportDirective(fqnString)
             analyzeImportReference(importDirective, resolutionScope, BindingTraceContext(), module)
                     .filterIsInstance(javaClass<CallableDescriptor>())

idea/testData/completion/basic/multifile/NoExtensionMethodDuplication/NoExtensionMethodDuplication.dependency.kt

@@ -0,0 +1,6 @@
+package ppp
+
+class C
+
+fun C.extFun1(){}
+fun C.extFun2(){}

idea/testData/completion/basic/multifile/NoExtensionMethodDuplication/NoExtensionMethodDuplication.kt

@@ -0,0 +1,9 @@
+package ppp
+
+fun f() {
+    C().ext<caret>
+}
+
+// EXIST: extFun1
+// EXIST: extFun2
+// NUMBER: 2

idea/tests/org/jetbrains/jet/completion/MultiFileJvmBasicCompletionTestGenerated.java

@@ -19,7 +19,6 @@ package org.jetbrains.jet.completion;
 import com.intellij.testFramework.TestDataPath;
 import org.jetbrains.jet.JUnit3RunnerWithInners;
 import org.jetbrains.jet.JetTestUtils;
-import org.jetbrains.jet.test.InnerTestClasses;
 import org.jetbrains.jet.test.TestMetadata;
 import org.junit.runner.RunWith;
 
@@ -120,6 +119,12 @@ public class MultiFileJvmBasicCompletionTestGenerated extends AbstractMultiFileJ
         doTest(fileName);
     }
 
+    @TestMetadata("NoExtensionMethodDuplication")
+    public void testNoExtensionMethodDuplication() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/multifile/NoExtensionMethodDuplication/");
+        doTest(fileName);
+    }
+
     @TestMetadata("NotImportedExtensionForImplicitReceiver")
     public void testNotImportedExtensionForImplicitReceiver() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/basic/multifile/NotImportedExtensionForImplicitReceiver/");