diff --git a/src/lib/diff/tree-mutator-collection-binding.hpp b/src/lib/diff/tree-mutator-collection-binding.hpp
index 50da11331..a0476eade 100644
--- a/src/lib/diff/tree-mutator-collection-binding.hpp
+++ b/src/lib/diff/tree-mutator-collection-binding.hpp
@@ -174,6 +174,7 @@
         using Iter = typename BIN::iterator;
         
         BIN binding_;
+      public: ///////////////TODO: diagnostics
         Iter pos_;
         
         
@@ -184,8 +185,19 @@
           , pos_(binding_.initMutation())
           { }
         
+        ChildCollectionMutator (ChildCollectionMutator&&)       =default;
+        ChildCollectionMutator (ChildCollectionMutator const&)  =delete;
+        ChildCollectionMutator& operator= (ChildCollectionMutator const&) =delete;
         
         
+        /////////////////TODO : diagnostics
+        typename BIN::const_iterator
+        exposeSrcBuffer()  const
+          {
+            return eachElm (binding_.contentBuffer);
+          }
+        /////////////////TODO : diagnostics
+        
         /* ==== re-Implementation of the operation API ==== */
         
         /** skip next pending src element,
diff --git a/src/lib/diff/tree-mutator.hpp b/src/lib/diff/tree-mutator.hpp
index 57fa6ebed..5f0bd4e86 100644
--- a/src/lib/diff/tree-mutator.hpp
+++ b/src/lib/diff/tree-mutator.hpp
@@ -333,8 +333,8 @@ namespace diff{
     struct Builder
       : PAR
       {
-        Builder(PAR par)
-          : PAR(par)
+        Builder(PAR&& par)
+          : PAR(std::forward<PAR>(par))
           { }
         
         template<class CLO>
diff --git a/tests/library/diff/tree-manipulation-binding-test.cpp b/tests/library/diff/tree-manipulation-binding-test.cpp
index 213d3e6b4..09d045eb2 100644
--- a/tests/library/diff/tree-manipulation-binding-test.cpp
+++ b/tests/library/diff/tree-manipulation-binding-test.cpp
@@ -354,6 +354,7 @@ namespace test{
           CHECK (isnil (contents));
           
           cout << "injected......" << join(target) <<endl;
+          cout << "exhausted....." << join(mutator.exposeSrcBuffer()) <<endl;;
           
           
           // --- second round: reorder the collection ---
@@ -376,6 +377,9 @@ namespace test{
                           }));
           
           CHECK (isnil (target));                   // the "visible" new content is still void
+          cout << "target......" << join(target) <<endl;;
+          cout << "srcBuff....." << join(mutator2.exposeSrcBuffer()) <<endl;;
+          cout << "pos_........" << *mutator2.pos_ <<endl;;
           
           CHECK (mutator2.matchSrc (ATTRIB1));      // current head element of src "matches" the given spec
           CHECK (isnil (target));                   // the match didn't change anything