Smart completion of inheritors: correct filtering of duplicates

idea/src/org/jetbrains/jet/plugin/completion/smart/TypeInstantiationItems.kt

@@ -204,7 +204,8 @@ class TypeInstantiationItems(
             lookupElement = lookupElement.assignSmartCompletionPriority(SmartCompletionItemPriority.INSTANTIATION)
         }
 
-        lookupElement = object: LookupElementDecorator<LookupElement>(lookupElement) {
+        //TODO: cannot use lookupElement from context due to KT-6344
+        class InstantiationLookupElement(lookupElement: LookupElement) : LookupElementDecorator<LookupElement>(lookupElement) {
             override fun getLookupString() = lookupString
 
             override fun getAllLookupStrings() = allLookupStrings
@@ -223,9 +224,20 @@ class TypeInstantiationItems(
             override fun handleInsert(context: InsertionContext) {
                 insertHandler.handleInsert(context, getDelegate())
             }
+
+            override fun equals(other: Any?): Boolean {
+                if (other === this) return true
+                if (other !is InstantiationLookupElement) return false
+                if (getLookupString() != other.getLookupString()) return false
+                val presentation1 = LookupElementPresentation()
+                val presentation2 = LookupElementPresentation()
+                renderElement(presentation1)
+                other.renderElement(presentation2)
+                return presentation1.getItemText() == presentation2.getItemText() && presentation1.getTailText() == presentation2.getTailText()
+            }
         }
 
-        return lookupElement.addTail(tail)
+        return InstantiationLookupElement(lookupElement).addTail(tail)
     }
 
     private fun addSamConstructorItem(collection: MutableCollection<LookupElement>, `class`: ClassDescriptor, tail: Tail?) {

idea/testData/completion/smartMultiFile/InheritorsAndMultipleExpectedTypes/Declarations.kt

@@ -0,0 +1,16 @@
+class X
+class Y
+
+trait T1
+trait T2<T>
+trait T3<T>
+
+class C1 : T1
+class C2<T> : T2<T>, T3<T>
+class C3 : T1, T2<X>
+
+fun foo(p: T1){}
+fun foo(p: T2<X>){}
+fun foo(p: T3<Y>){}
+
+// ALLOW_AST_ACCESS

idea/testData/completion/smartMultiFile/InheritorsAndMultipleExpectedTypes/InheritorsAndMultipleExpectedTypes.kt

@@ -0,0 +1,12 @@
+fun bar() {
+    foo(<caret>)
+}
+
+// EXIST: { lookupString: "object", itemText: "object: T1{...}" }
+// EXIST: { lookupString: "object", itemText: "object: T2<X>{...}" }
+// EXIST: { lookupString: "object", itemText: "object: T3<Y>{...}" }
+// EXIST: { lookupString: "C1", itemText: "C1" }
+// EXIST: { lookupString: "C2", itemText: "C2<X>" }
+// EXIST: { lookupString: "C2", itemText: "C2<Y>" }
+// EXIST: { lookupString: "C3", itemText: "C3" }
+// NUMBER: 7

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

@@ -19,6 +19,7 @@ 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;
 

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

@@ -72,6 +72,12 @@ public class MultiFileSmartCompletionTestGenerated extends AbstractMultiFileSmar
         doTest(fileName);
     }
 
+    @TestMetadata("InheritorsAndMultipleExpectedTypes")
+    public void testInheritorsAndMultipleExpectedTypes() throws Exception {
+        String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/smartMultiFile/InheritorsAndMultipleExpectedTypes/");
+        doTest(fileName);
+    }
+
     @TestMetadata("JavaStaticMethodArgument")
     public void testJavaStaticMethodArgument() throws Exception {
         String fileName = JetTestUtils.navigationMetadata("idea/testData/completion/smartMultiFile/JavaStaticMethodArgument/");