xo-alloc2 xo-gc: assorted utest-guided cleanup ++ coverage

include/xo/alloc2/ArenaIterator.hpp

@@ -0,0 +1,15 @@
+/** @file ArenaIterator.hpp
+ *
+ *  @author Roland Conybeare, May 2026
+ **/
+
+#pragma once
+
+// reminder: we can't put this AAllocIterator support in xo-arena
+// because xo-arena is a dependency of xo-facet, which we're relying
+// on here
+
+#include <xo/arena/DArenaIterator.hpp>
+#include "arena/IAllocIterator_DArenaIterator.hpp"
+
+/* end ArenaIterator.hpp */

include/xo/alloc2/arena/IAllocator_DArena.hpp

@@ -72,8 +72,6 @@ namespace xo {
              *  @p complete_flag to true.
              **/
             static value_type sub_alloc(DArena &, size_type z, bool complete_flag);
-            /** allocate copy of @p src in arena @p d. **/
-            static value_type alloc_copy(DArena & d, value_type src);
             static void clear(DArena &);
             /** perform assignment {*lhs_iface, *lhs_data} = {*rhs_iface, rhs_data} **/
             static void barrier_assign_aux(DArena &,

include/xo/alloc2/role.hpp

@@ -30,6 +30,8 @@ namespace xo {
 
             operator value_type() const { return role_; }
 
+            Role next() const { return Role(role_ + 1); }
+
             value_type role_ = 0;
         };
     } /*namespace mm*/