fix opEquals type

std/bitmanip.d

@@ -297,12 +297,12 @@ struct BitArray
     size_t len;
     uint* ptr;
 
-    size_t dim()
+    const size_t dim()
     {
         return (len + 31) / 32;
     }
 
-    size_t length()
+    const size_t length()
     {
         return len;
     }
@@ -578,7 +578,7 @@ struct BitArray
      * Support for operators == and != for bit arrays.
      */
 
-    bool opEquals(BitArray a2)
+    const bool opEquals(const ref BitArray a2)
     {   int i;
 
         if (this.length != a2.length)

std/boxer.d

@@ -208,7 +208,7 @@ struct Box
     }
     
     /** Return whether this value could be unboxed as the given type without throwing. */
-    bool unboxable(TypeInfo test)
+    bool unboxable(TypeInfo test) const
     {
         if (type is test)
             return true;
@@ -335,9 +335,14 @@ struct Box
      * Compare this box's value with another box. This implicitly casts if the
      * types are different, identical to the regular type system.    
      */
-    bool opEquals(Box other)
+    const bool opEquals(const ref Box other)
     {
-        return opEqualsInternal(other, false);
+        return (cast(Box)this).opEqualsInternal(cast(Box)other, false);
+    }
+    
+    const bool opEquals(Box other)
+    {
+        return (cast(Box)this).opEqualsInternal(other, false);
     }
     
     private float opCmpInternal(Box other, bool inverted)

std/random.d

@@ -242,7 +242,7 @@ Always $(D false) (random generators are infinite ranges).
 /**
    Compares against $(D_PARAM rhs) for equality.
  */
-    bool opEquals(LinearCongruentialEngine rhs) const
+    bool opEquals(ref const LinearCongruentialEngine rhs) const
     {
         return _x == rhs._x;
     }