[Bug c++/22513] New: [4.0 regression] Miscompilation of std::list code in Boost.

["redi at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>]

A Boost regression test has been failing for some time with GCC 4.0.x although
it works with GCC 3.4, mainline and several other compilers that run the Boost
tests.

The problem seems to be that a std::list element is not removed correctly,
causing it to be removed twice and crashing on the second attempt.  I think a
list node might have a dangling pointer but haven't figured it out yet.

Creating pre-processed source with mainline and compiling with 4.0 still causes
the bug, pre-processing with 4.0 and compiling with 4.1 doesn't, so it's not a
libstdc++ problem.

The attached .ii file was produced by gcc version 4.0.2 20050716 (prerelease)
from the following code, using the latest ptr_list from Boost's CVS.  Sorry
about the size of the .ii, the ptr_list brings in a lot of code.

#include <iterator>
#include <cassert>
#include <boost/ptr_container/ptr_list.hpp>

struct B { virtual ~B() {} };
struct T : public B {};

int main()
{
    typedef boost::ptr_list<B> C;

    C  c;
    assert( c.size() == 0 );
    c.push_back( new T );
    assert( c.size() == 1 );

    C  c3( c.begin(), c.end() );
    assert( c.size() == c3.size() );

    c.assign( c3.begin(), c3.end() );
    assert( c.size() == c3.size() );

    c.erase( c.begin() );
    assert( c.size() != c3.size() );
    c.clear();
}

This segfaults on the final line when clearing the container.
(Or if mainline is used to produce a .ii which is then compiled with 4.0, then
the assertion on the previous line fails instead.)

-- 
           Summary: [4.0 regression] Miscompilation of std::list code in
                    Boost.
           Product: gcc
           Version: 4.0.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: redi at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22513