item_strfunc.cc:

  Unnesessary code was removed. Comment was added.

sql/item_strfunc.cc

@@ -975,8 +975,13 @@ String *Item_func_right::val_str(String *str)
   if (res->length() <= (uint) length)
     return res; /* purecov: inspected */
 
+  /*
+    As far "res" contains at least "length" bytes
+    (according to the above condition and return),
+    the below statement is safe. res->numchars() can 
+    never return a value less than "length".
+  */
   uint start=res->numchars()-(uint) length;
-  if (start<=0) return res;
   start=res->charpos(start);
   tmp_value.set(*res,start,res->length()-start);
   return &tmp_value;