KT-5153 Smart completion should include objects from type

#KT-5153 Fixed

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

@@ -82,6 +82,11 @@ class StaticMembers(val bindingContext: BindingContext, val resolveSession: Reso
             else if (DescriptorUtils.isEnumEntry(descriptor) && !enumEntriesToSkip.contains(descriptor)) {
                 classifier = { ExpectedInfoClassification.MATCHES } /* we do not need to check type of enum entry because it's taken from proper enum */
             }
+            else if (descriptor is ClassDescriptor && DescriptorUtils.isObject(descriptor)) {
+                classifier = { expectedInfo ->
+                    if (descriptor.getDefaultType().isSubtypeOf(expectedInfo.`type`)) ExpectedInfoClassification.MATCHES else ExpectedInfoClassification.NOT_MATCHES
+                }
+            }
             else {
                 return
             }
@@ -101,9 +106,11 @@ class StaticMembers(val bindingContext: BindingContext, val resolveSession: Reso
             classObject.getDefaultType().getMemberScope().getAllDescriptors().forEach(::processMember)
         }
 
-        if (classDescriptor.getKind() == ClassKind.ENUM_CLASS) {
-            classDescriptor.getDefaultType().getMemberScope().getAllDescriptors().forEach(::processMember)
+        var members = classDescriptor.getDefaultType().getMemberScope().getAllDescriptors()
+        if (classDescriptor.getKind() != ClassKind.ENUM_CLASS) {
+            members = members.filter { DescriptorUtils.isObject(it) }
         }
+        members.forEach(::processMember)
     }
 
     private fun createLookupElement(memberDescriptor: DeclarationDescriptor, classDescriptor: ClassDescriptor): LookupElement {

idea/testData/completion/handlers/smart/ObjectFromType.kt

@@ -0,0 +1,13 @@
+package p
+
+class Outer {
+    trait T {
+        object Null : T { }
+    }
+}
+
+fun foo(): Outer.T {
+    return <caret>
+}
+
+// ELEMENT: "T.Null"

idea/testData/completion/handlers/smart/ObjectFromType.kt.after

@@ -0,0 +1,13 @@
+package p
+
+class Outer {
+    trait T {
+        object Null : T { }
+    }
+}
+
+fun foo(): Outer.T {
+    return Outer.T.Null<caret>
+}
+
+// ELEMENT: "T.Null"

idea/testData/completion/smart/ObjectsFromType.kt

@@ -0,0 +1,14 @@
+package p
+
+trait T {
+    object Null : T { }
+
+    object Other {}
+}
+
+fun foo(): T {
+    return <caret>
+}
+
+// EXIST: { lookupString:"T.Null", itemText:"T.Null", tailText:" (p)", typeText:"T" }
+// ABSENT: T.Other

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

@@ -416,6 +416,11 @@ public class JvmSmartCompletionTestGenerated extends AbstractJvmSmartCompletionT
         doTest("idea/testData/completion/smart/NullableThis.kt");
     }
     
+    @TestMetadata("ObjectsFromType.kt")
+    public void testObjectsFromType() throws Exception {
+        doTest("idea/testData/completion/smart/ObjectsFromType.kt");
+    }
+    
     @TestMetadata("OverloadedConstructorArgument.kt")
     public void testOverloadedConstructorArgument() throws Exception {
         doTest("idea/testData/completion/smart/OverloadedConstructorArgument.kt");

idea/tests/org/jetbrains/jet/completion/handlers/SmartCompletionHandlerTestGenerated.java

@@ -381,6 +381,11 @@ public class SmartCompletionHandlerTestGenerated extends AbstractSmartCompletion
         doTest("idea/testData/completion/handlers/smart/NullableValueKeepOldArguments.kt");
     }
     
+    @TestMetadata("ObjectFromType.kt")
+    public void testObjectFromType() throws Exception {
+        doTest("idea/testData/completion/handlers/smart/ObjectFromType.kt");
+    }
+    
     @TestMetadata("SAMExpected1.kt")
     public void testSAMExpected1() throws Exception {
         doTest("idea/testData/completion/handlers/smart/SAMExpected1.kt");