The attached preprocessed source when compiled with -D_GLIBCXX_DEBUG encounters
a runtime assert at the final call to splice.  According to
http://www.sgi.com/tech/stl/List.html, all iterators remain valid after a merge
operation.  I believe that libstdc++ is not updating the _M_sequence members of
the safe iterators merged into list1.

I've also attached unpreprocessed source with comments indicating the problem.

To reproduce the problem:

% g++ -D_GLIBCXX_DEBUG list.ii
% ./a.out
/usr/include/c++/4.2/debug/list:350:error: attempt to splice an iterator
    from a different container.

Objects involved in the operation:
iterator "__i" @ 0x0xbfd5ea30 {
type =
N11__gnu_debug14_Safe_iteratorINSt6__norm14_List_iteratorIiEENSt7__debug4listIiSaIiEEEEE
(mutable iterator);
  state = dereferenceable;
  references sequence with type `NSt7__debug4listIiSaIiEEE' @ 0x0xbfd5ea30
}
sequence "__x" @ 0x0xbfd5e9c4 {
  type = NSt7__debug4listIiSaIiEEE;
}
Aborted


-- 
           Summary: GLIBCXX_DEBUG: list::merge triggers bad assert
           Product: gcc
           Version: 4.2.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: greened at obbligato dot org
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35969

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