explicit error message

...turns out that inclusion of format-string.hpp
is almost irrelevant, since diff/record.hpp already
includes even format-util.hpp

src/lib/diff/gen-node.hpp

@@ -96,16 +96,13 @@
 #include "lib/error.hpp"
 #include "lib/idi/entry-id.hpp"
 #include "lib/time/timevalue.hpp"
-//#include "lib/format-util.hpp"        ///////////////////////////////TICKET #973 : investigate the impact of this inclusion on code size
 #include "lib/diff/record.hpp"
 #include "lib/variant.hpp"
 #include "lib/util.hpp"
 
-//#include <vector>
 #include <utility>
 #include <string>
 #include <deque>
-//#include <map>
 
 
 namespace lib {

src/lib/diff/record.hpp

@@ -90,7 +90,7 @@
 #include "lib/iter-adapter.hpp"
 #include "lib/iter-adapter-stl.hpp"
 #include "lib/itertools.hpp"
-#include "lib/format-util.hpp"
+#include "lib/format-util.hpp"        ///////////////////////////////TICKET #973 : investigate the impact of this inclusion on code size
 #include "lib/util.hpp"
 
 #include "lib/diff/record-content-mutator.hpp"

src/lib/diff/tree-mutator-attribute-binding.hpp

@@ -174,7 +174,10 @@
         findSrc (GenNode const& refSpec)  override
           {
             if (isApplicable(refSpec))
-              throw error::Logic ("attempt to re-order attributes bound to object fields");  //////TODO can we include _Fmt and give a precise message including the key?
+              throw error::Logic (_Fmt{"attempt to re-order attribute '%s', "
+                                       "which is bound to an object field and "
+                                       "thus does not respond to ordering."}
+                                      % refSpec.idi.getSym());
             else
               return PAR::findSrc (refSpec);
           }

src/lib/diff/tree-mutator.hpp

@@ -97,6 +97,7 @@
 #include "lib/diff/gen-node.hpp"
 #include "lib/opaque-holder.hpp"
 #include "lib/iter-adapter-stl.hpp"
+#include "lib/format-string.hpp"
 
 #include <utility>
 #include <string>
@@ -158,6 +159,7 @@ namespace diff{
   
   using lib::Literal; /////TODO placeholder ....consider to build an EntryID
   using std::string;
+  using util::_Fmt;