id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4809	deserialization with xml_iarchive fails when attributes of top level element are reordered	Kolja Nowak <kolja@…>	Bryce Adelstein Lelbach	"Citing from [http://www.w3.org/TR/2008/REC-xml-20081126/ W3C XML spec], section 3.1: ""Note that the order of attribute specifications in a start-tag or empty-element tag is not significant.""

The parser used by xml_iarchive doesn't conform to this, because it fails on XML input which is logically equivalent to the output of xml_oarchive, just because the attribute order of the top level element 'boost_serialization' was changed. In contrast, the parser seems to be robust against reordering attributes in other elements.

The following program demonstrates the issue:
{{{

#include <iostream>
#include <sstream>
#include <string>
#include <boost/archive/xml_iarchive.hpp>

void f(const std::string& xml)
{
  try
  {
    std::string str;
    boost::archive::xml_iarchive(std::istringstream(xml)) 
      >> boost::serialization::make_nvp(""str"", str);
    std::cout << str << std::endl;
  }
  catch(boost::archive::archive_exception& e)
  {
    std::cout << e.what() << std::endl;
  }
}

int main()
{
  // deserialize some xml, which was created using xml_oarchive

  f(""<?xml version=\""1.0\"" encoding=\""UTF-8\"" standalone=\""yes\"" ?>""
    ""<!DOCTYPE boost_serialization>""
    ""<boost_serialization signature=\""serialization::archive\"" version=\""7\"">""
    ""<str>deserialize successfull</str>""
    ""</boost_serialization>"");

  // the same xml, but attributes of <boost_serialization> reorderd

  f(""<?xml version=\""1.0\"" encoding=\""UTF-8\"" standalone=\""yes\"" ?>""
    ""<!DOCTYPE boost_serialization>""
    ""<boost_serialization version=\""7\"" signature=\""serialization::archive\"">""
    ""<str>deserialize successfull</str>""
    ""</boost_serialization>"");

  return 0;
}
}}}

The following patch to basic_xml_grammar.ipp modifies the rule 'SerializationWrapper' to accept both possible combinations:

{{{
Index: libs/serialization/src/basic_xml_grammar.ipp
===================================================================
--- libs/serialization/src/basic_xml_grammar.ipp    (revision 66354)
+++ libs/serialization/src/basic_xml_grammar.ipp    (working copy)
@@ -271,9 +271,9 @@
       =  -S
       >> ""<boost_serialization""
       >> S
-      >> SignatureAttribute
-      >> S
-      >> VersionAttribute
+      >> ( (SignatureAttribute >> S >> VersionAttribute)
+         | (VersionAttribute >> S >> SignatureAttribute)
+         )
       >> !S
       >> '>'
     ;
}}}
"	Bugs	closed	To Be Determined	serialization	Boost 1.44.0	Problem	fixed	serialization xml attribute order