Smart completion does not need SAM-constructor in declarations from scope + it's present even when not imported

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

@@ -34,6 +34,7 @@ import org.jetbrains.jet.plugin.caches.resolve.getLazyResolveSession
 import org.jetbrains.jet.renderer.DescriptorRenderer
 import org.jetbrains.jet.lang.psi.psiUtil.getReceiverExpression
 import org.jetbrains.jet.plugin.util.IdeDescriptorRenderers
+import org.jetbrains.jet.lang.resolve.java.descriptor.SamConstructorDescriptor
 
 class SmartCompletion(val expression: JetSimpleNameExpression,
                       val resolveSession: ResolveSessionForBodies,
@@ -106,7 +107,8 @@ class SmartCompletion(val expression: JetSimpleNameExpression,
 
         fun filterDeclaration(descriptor: DeclarationDescriptor): Collection<LookupElement> {
             val result = ArrayList<LookupElement>()
-            if (!itemsToSkip.contains(descriptor)) {
+            if (!itemsToSkip.contains(descriptor)
+                    && descriptor !is SamConstructorDescriptor /* SAM-constructor is added explicitly and is not needed here */) {
                 val types = typesWithSmartCasts(descriptor)
                 val nonNullTypes = types.map { it.makeNotNullable() }
                 val classifier = { (expectedInfo: ExpectedInfo) ->

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

@@ -37,6 +37,8 @@ import org.jetbrains.jet.lang.descriptors.Visibilities
 import org.jetbrains.jet.plugin.util.makeNotNullable
 import org.jetbrains.jet.plugin.util.IdeDescriptorRenderers
 import org.jetbrains.jet.lang.resolve.BindingContext
+import org.jetbrains.jet.lang.descriptors.PackageFragmentDescriptor
+import org.jetbrains.jet.lang.resolve.java.descriptor.SamConstructorDescriptor
 
 class TypeInstantiationItems(val resolveSession: ResolveSessionForBodies, val bindingContext: BindingContext, val visibilityFilter: (DeclarationDescriptor) -> Boolean) {
     public fun addToCollection(collection: MutableCollection<LookupElement>, expectedInfos: Collection<ExpectedInfo>) {
@@ -53,6 +55,8 @@ class TypeInstantiationItems(val resolveSession: ResolveSessionForBodies, val bi
         val classifier = jetType.getConstructor().getDeclarationDescriptor()
         if (classifier !is ClassDescriptor) return
 
+        addSamConstructorItem(collection, classifier, tail)
+
         val isAbstract = classifier.getModality() == Modality.ABSTRACT
         val allConstructors = classifier.getConstructors()
         val visibleConstructors = allConstructors.filter {
@@ -135,4 +139,22 @@ class TypeInstantiationItems(val resolveSession: ResolveSessionForBodies, val bi
 
         collection.add(lookupElement.addTail(tail))
     }
+
+    private fun addSamConstructorItem(collection: MutableCollection<LookupElement>, `class`: ClassDescriptor, tail: Tail?) {
+        if (`class`.getKind() == ClassKind.TRAIT) {
+            val container = `class`.getContainingDeclaration()
+            val scope = when (container) {
+                is PackageFragmentDescriptor -> container.getMemberScope()
+                is ClassDescriptor -> container.getStaticScope()
+                else -> return
+            }
+            val samConstructor = scope.getFunctions(`class`.getName())
+                                         .filterIsInstance(javaClass<SamConstructorDescriptor>())
+                                         .singleOrNull() ?: return
+            val lookupElement = createLookupElement(samConstructor, resolveSession, bindingContext)
+                    .assignSmartCompletionPriority(SmartCompletionItemPriority.INSTANTIATION)
+                    .addTail(tail)
+            collection.add(lookupElement)
+        }
+    }
 }