Hello, I'm a new user to boost and have a question about a compiler warning I'm seeing. I'm currently using just the boost::any type and on HPUX v11.00 PA with aCC: HP ANSI C++ B3910B A.03.56 I'm seeing the following warning: Warning (anachronism) 823: "/Components/dev/Boost/v1.33.1/boost/type_traits/is_reference.hpp", line 38 # Redundant preprocessing concatenation operation results in two valid preprocessing tokens. Depending on this implementation defined behavior will result in non-portable code. BOOST_TT_AUX_BOOL_TRAIT_DEF1(is_reference,T,false) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Here's the compile line that generated the warning: aCC -AA -DACE_HAS_STANDARD_CPP_LIBRARY=1 -D_RWSTD_MULTI_THREAD -D_REENTRANT -U_INCLUDE__STDC_A1_SOURCE -DACE_HAS_THREADS -D_POSIX_C_SOURCE=199506L -DHPUX_VERS=1100 -DACE_LACKS_PRAGMA_ONCE +W302 +W930 +W849 -mt +DAportable +Z -D_LARGEFILE64_SOURCE=1 +O3 +Osize -DACE_NDEBUG -DACE_USE_RCSID=0 -DACE_HAS_EXCEPTIONS -D__ACE_INLINE__ -D__UNIX -c -o .objects/HP-UX.B.11.00_RISC_aCC.A.03.37/release//LicAgentSvc.o LicAgentSvc.cpp Because the boost::any header is included in one of my headers, I see this warning hundreds of times. While I could just suppress it I prefer to first try to figure out what the issue is. I dislike suppressing warnings I don't understand. Does anyone know what this warning means and/or have any suggestions for what to do about it? Thanks, Richard J. Ward Symantec Corp.