Fix DList.opAssign not changing tail

source/tanya/container/list.d

@@ -174,6 +174,12 @@ struct SList(T)
         assert(l.front == 3);
     }
 
+    private @safe @nogc unittest
+    {
+        auto l = SList!int(0, 0);
+        assert(l.empty);
+    }
+
     /// Ditto.
     this(const size_t len, shared Allocator allocator = defaultAllocator)
     {
@@ -610,9 +616,7 @@ struct SList(T)
     }
 
     /**
-     * Returns the first element and moves to the next one.
+     * Removes the front element.
-     *
-     * Returns: The first element.
      *
      * Precondition: $(D_INLINECODE !empty)
      */
@@ -763,6 +767,23 @@ struct SList(T)
         return this;
     }
 
+    ///
+    @safe @nogc unittest
+    {
+        {
+            auto l1 = SList!int([5, 4, 9]);
+            auto l2 = SList!int([9, 4]);
+            l1 = l2;
+            assert(l1 == l2);
+        }
+        {
+            auto l1 = SList!int([5, 4, 9]);
+            auto l2 = SList!int([9, 4]);
+            l1 = SList!int([9, 4]);
+            assert(l1 == l2);
+        }
+    }
+
     /**
      * Assigns an input range.
      *
@@ -805,12 +826,20 @@ struct SList(T)
         assert(l1 == l2);
     }
 
+    private @safe @nogc unittest
+    {
+        auto l1 = SList!int();
+        auto l2 = SList!int([9, 4]);
+        l1 = l2[];
+        assert(l1 == l2);
+    }
+
     /**
      * Assigns a static array.
      *
      * Params:
      *  R    = Static array size.
-     *  that = Values to initialize the vector with.
+     *  that = Values to initialize the list with.
      *
      * Returns: $(D_KEYWORD this).
      */
@@ -1063,6 +1092,12 @@ struct DList(T)
         assert(l.back == 3);
     }
 
+    private @safe @nogc unittest
+    {
+        auto l = DList!int(0, 0);
+        assert(l.empty);
+    }
+
     /// Ditto.
     this(const size_t len, shared Allocator allocator = defaultAllocator)
     {
@@ -1356,16 +1391,20 @@ struct DList(T)
 
         assert(l1.insertFront(8) == 1);
         assert(l1.front == 8);
+        assert(l1.back == 8);
         assert(l1.insertFront(9) == 1);
         assert(l1.front == 9);
+        assert(l1.back == 8);
 
         DList!int l2;
         assert(l2.insertFront([25, 30, 15]) == 3);
         assert(l2.front == 25);
+        assert(l2.back == 15);
 
         l2.insertFront(l1[]);
         assert(l2.length == 5);
         assert(l2.front == 9);
+        assert(l2.back == 15);
     }
 
     /**
@@ -1655,9 +1694,7 @@ struct DList(T)
     }
 
     /**
-     * Returns the first element and moves to the next one.
+     * Removes the front element.
-     *
-     * Returns: The first element.
      *
      * Precondition: $(D_INLINECODE !empty)
      */
@@ -1838,20 +1875,20 @@ struct DList(T)
     {
         Entry** next = &this.head;
 
-        foreach (ref e; that)
+        while (!that.empty && *next !is null)
         {
-            if (*next is null)
+            (*next).content = that.front;
+            next = &(*next).next;
+            that.popFront();
+        }
+        if (that.empty)
         {
-                *next = allocator.make!Entry(e);
+            remove(DRange!T(*next, this.tail));
         }
         else
         {
-                (*next).content = e;
+            insertBack(that);
         }
-            next = &(*next).next;
-        }
-        remove(DRange!T(*next, this.tail));
-
         return this;
     }
 
@@ -1864,12 +1901,20 @@ struct DList(T)
         assert(l1 == l2);
     }
 
+    private @safe @nogc unittest
+    {
+        auto l1 = DList!int();
+        auto l2 = DList!int([9, 4]);
+        l1 = l2[];
+        assert(l1 == l2);
+    }
+
     /**
      * Assigns a static array.
      *
      * Params:
      *  R    = Static array size.
-     *  that = Values to initialize the vector with.
+     *  that = Values to initialize the list with.
      *
      * Returns: $(D_KEYWORD this).
      */