Fix for issue 4942

std/container.d

@@ -2003,7 +2003,7 @@ Complexity: $(BIGOH log(n)).
         static if (is(T == struct))
         {
             // Destroy this guy
-            clear(_data._payload[$ - 1]);
+            .clear(_data._payload[$ - 1]);
         }
         _data._payload = _data._payload[0 .. $ - 1];
     }
@@ -2031,7 +2031,7 @@ Complexity: $(BIGOH howMany).
             // Destroy this guy
             foreach (ref e; _data._payload[$ - howMany .. $])
             {
-                clear(e);
+                .clear(e);
             }
         }
         _data._payload = _data._payload[0 .. $ - howMany];
@@ -4762,3 +4762,12 @@ unittest
     RedBlackTree!ubyte rt5;
     RedBlackTree!byte rt6;
 }
+
+version(unittest) struct UnittestMe {
+  int a;
+}
+
+unittest
+{
+    auto c = Array!UnittestMe();
+}

std/traits.d

@@ -1451,6 +1451,37 @@ unittest
     static assert(hasElaborateAssign!S3);
 }
 
+/**
+   True if $(D S) or any type directly embedded in the representation
+   of $(D S) defines an elaborate destructor. Elaborate destructors
+   are introduced by defining $(D ~this()) for a $(D
+   struct). (Non-struct types never have elaborate destructors, even
+   though classes may define $(D ~this()).)
+ */
+template hasElaborateDestructor(S)
+{
+    static if(!is(S == struct))
+    {
+        enum bool hasElaborateDestructor = false;
+    }
+    else
+    {
+        enum hasElaborateDestructor = is(typeof({S s; return &s.__dtor;}))
+            || anySatisfy!(.hasElaborateDestructor, typeof(S.tupleof));
+    }
+}
+
+unittest
+{
+    static assert(!hasElaborateDestructor!int);
+    static struct S1 { }
+    static assert(!hasElaborateDestructor!S1);
+    static struct S2 { ~this() {} }
+    static assert(hasElaborateDestructor!S2);
+    static struct S3 { S2 field; }
+    static assert(hasElaborateDestructor!S3);
+}
+
 /**
    Yields $(D true) if and only if $(D T) is a $(D struct) or a $(D
    class) that defines a symbol called $(D name).