Smart completion: no duplicates among static members

idea/testData/completion/handlers/smart/MergeTail3.kt

@@ -0,0 +1,16 @@
+class C {
+    class object {
+        fun f1(): C = C()
+        fun f2(): C = C()
+        fun f3(): C? = C()
+    }
+}
+
+fun foo(c: C){}
+fun foo(c: C?, i: Int){}
+
+fun foo() {
+    foo(<caret>
+}
+
+// ELEMENT: C.f1

idea/testData/completion/handlers/smart/MergeTail3.kt.after

@@ -0,0 +1,16 @@
+class C {
+    class object {
+        fun f1(): C = C()
+        fun f2(): C = C()
+        fun f3(): C? = C()
+    }
+}
+
+fun foo(c: C){}
+fun foo(c: C?, i: Int){}
+
+fun foo() {
+    foo(C.f1()<caret>
+}
+
+// ELEMENT: C.f1

idea/testData/completion/handlers/smart/MergeTail4.kt

@@ -0,0 +1,16 @@
+class C {
+    class object {
+        fun f1(): C = C()
+        fun f2(): C = C()
+        fun f3(): C? = C()
+    }
+}
+
+fun foo(c: C){}
+fun foo(c: C?, i: Int){}
+
+fun foo() {
+    foo(<caret>
+}
+
+// ELEMENT: C.f3

idea/testData/completion/handlers/smart/MergeTail4.kt.after

@@ -0,0 +1,16 @@
+class C {
+    class object {
+        fun f1(): C = C()
+        fun f2(): C = C()
+        fun f3(): C? = C()
+    }
+}
+
+fun foo(c: C){}
+fun foo(c: C?, i: Int){}
+
+fun foo() {
+    foo(C.f3(), <caret>
+}
+
+// ELEMENT: C.f3