Re: [Boost-bugs] [Boost C++ Libraries] #6126: Signed integer members of Boost.Fusion adapted ADTs are not output correctly with Boost.Spirit.Karma rules

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #6126: Signed integer members of Boost.Fusion adapted ADTs are not output correctly with Boost.Spirit.Karma rules
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2012-01-31 14:36:53

#6126: Signed integer members of Boost.Fusion adapted ADTs are not output
correctly with Boost.Spirit.Karma rules
-------------------------------+--------------------------------------------
  Reporter:  t0rt1e@…          |       Owner:  hkaiser                                                                                                             
      Type:  Bugs              |      Status:  new                                                                                                                 
 Milestone:  To Be Determined  |   Component:  spirit                                                                                                              
   Version:  Boost 1.48.0      |    Severity:  Regression                                                                                                          
Resolution:                    |    Keywords:  patch proposed, Boost.Spirit.Karma, Boost.Fusion, BOOST_FUSION_ADAPT_CLASS, BOOST_FUSION_ADAPT_ADT, short, int, long
-------------------------------+--------------------------------------------

Comment (by t0rt1e@…):

 I tried to dig further into the problem by following Seth Heren's debug
 into the {{{any_integer_iterator::insert_int()}}} member function at
 {{{boost/spirit/home/karma/numeric/int.hpp:210}}} when executing the
 compiled {{{test_short_output_with_karma.cpp}}}. I could further narrow
 down the moment, when the {{{*attr}}} value becomes zero by serializing
 the statements and inlining the {{{sign_inserter::call}}} (see attached
 diagnostic patch
 {{{boost_spirit_home_karma_numeric_int_diagnostic.patch}}} against Boost
 trunk 76795). The {{{*attr}}} value becomes zero after a character is put
 into the {{{sink}}}, which happens in our case in line
 {{{boost/spirit/home/karma/numeric/int.hpp:221}}}. Why??? Has anyone an
 idea? Before everything is OK. I tested it by copying the Attribute via a
 dummy function into another variable. Here's the relevant code snippet
 with some comments:
 {{{
         template <typename OutputIterator, typename Attribute>
         static bool insert_int(OutputIterator& sink, Attribute const&
 attr)
         {
           // I have serialized the calls to better follow with the
 debugger what's going on.
           bool is_zero = traits::test_zero(attr);
           bool is_neg = traits::test_negative(attr);
           // Until here everything seems OK, *attr still has its value.
           // I can use, e.g., the attribute in a function call.
           Attribute attr_copy = dummy_function(attr);
 //          bool r1 = sign_inserter::call(sink, is_zero
 //                      , is_neg, force_sign);
           // After the sign_inserter call, *attr becomes surprisingly
 zero.
           // Therefore, I inlined the important code parts to output the
 sign.
           if (is_neg) {
             *sink = '-';
             // After putting the character into the sink, the *attr
 becomes zero.
             // Why??? This happens consistently unimportant whether it's
             // compiled using g++ or clang++ on Linux or Mac OS X. Is the
 sink
             // not correctly constructed and leaks memory?
             ++sink;
           } else if (force_sign) {
             if (is_zero) {
               *sink = ' ';
             } else {
               *sink = '+';
             }
             ++sink;
           }
           bool r1 = true;
           bool r2 = int_inserter<Radix, CharEncoding, Tag>::call(sink
                       , traits::get_absolute_value(attr));
           return r1 && r2;
 //            return sign_inserter::call(sink, traits::test_zero(attr)
 //                      , traits::test_negative(attr), force_sign) &&
 //                   int_inserter<Radix, CharEncoding, Tag>::call(sink
 //                      , traits::get_absolute_value(attr));
         }

       // Dummy function for pure diagnostic reasons. It just returns a
 copy of the attribute.
       template<typename Attribute>
       static Attribute dummy_function(Attribute const& attr) {
         return attr;
       };
 }}}
 I'm not anymore sure that we are facing a compiler bug. Maybe the
 {{{sink}}} is for some reason not correctly initialized?

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/6126#comment:11>
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