With Boost 1.35.0 packages from Debian unstable, I can no longer use with today GCC trunk version. The shortest way to reproduce the problem is: % echo '#include ' > w.cc % g++ -E w.cc > /dev/null In file included from /usr/include/boost/mpl/apply.hpp:23, from w.cc:1: /usr/include/boost/mpl/apply_wrap.hpp:81:31: error: missing binary operator before token "(" /usr/include/boost/mpl/apply_wrap.hpp:173:31: error: missing binary operator before token "(" In file included from /usr/include/boost/mpl/bind.hpp:27, from /usr/include/boost/mpl/lambda.hpp:18, from /usr/include/boost/mpl/apply.hpp:25, from w.cc:1: /usr/include/boost/mpl/apply_wrap.hpp:81:31: error: missing binary operator before token "(" /usr/include/boost/mpl/apply_wrap.hpp:173:31: error: missing binary operator before token "(" In file included from /usr/include/boost/mpl/lambda.hpp:18, from /usr/include/boost/mpl/apply.hpp:25, from w.cc:1: /usr/include/boost/mpl/bind.hpp:364:31: error: missing binary operator before token "(" /usr/include/boost/mpl/bind.hpp:531:31: error: missing binary operator before token "(" In file included from /usr/include/boost/mpl/lambda.hpp:22, from /usr/include/boost/mpl/apply.hpp:25, from w.cc:1: /usr/include/boost/mpl/aux_/full_lambda.hpp:230:31: error: missing binary operator before token "(" In file included from w.cc:1: /usr/include/boost/mpl/apply.hpp:138:31: error: missing binary operator before token "(" It worked fine a few weeks ago, I do not know whether this is a boost bug uncovered by recent GCC changes or if this is a GCC bug. Sam