$ clang++ --version
Apple clang version 3.0 (tags/Apple/clang-211.10.1) (based on LLVM 3.0svn)
Target: x86_64-apple-darwin11.1.0
Thread model: posix

$ llvm-g++-4.2 --version
i686-apple-darwin11-llvm-g++-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.1.00)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++ --version
i686-apple-darwin11-llvm-g++-4.2 (GCC) 4.2.1 (Based on Apple Inc. build 5658) (LLVM build 2336.1.00)
Copyright (C) 2007 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

$ g++ sample.cpp -I/opt/local/include -L/opt/local/lib -lboost_system-mt -lboost_regex-mt -licudata -licui18n -licuuc

takanori@hermit$ clang++ sample.cpp -I/opt/local/include -L/opt/local/lib -lboost_system-mt -lboost_regex-mt -licudata -licui18n -licuuc
In file included from sample.cpp:2:
In file included from /opt/local/include/boost/regex.hpp:31:
In file included from /opt/local/include/boost/regex/v4/regex.hpp:70:
/opt/local/include/boost/regex/v4/basic_regex_creator.hpp:1027:34: warning: equality comparison with extraneous
      parentheses [-Wparentheses]
            else if((state->type == syntax_element_long_set_rep)) 
                     ~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/opt/local/include/boost/regex/v4/basic_regex_creator.hpp:1027:34: note: remove extraneous parentheses around the
      comparison to silence this warning
            else if((state->type == syntax_element_long_set_rep)) 
                    ~            ^                             ~
/opt/local/include/boost/regex/v4/basic_regex_creator.hpp:1027:34: note: use '=' to turn this equality comparison
      into an assignment
            else if((state->type == syntax_element_long_set_rep)) 
                                 ^~
                                 =
/opt/local/include/boost/regex/v4/basic_regex_creator.hpp:1328:28: warning: equality comparison with extraneous
      parentheses [-Wparentheses]
               if((p->type == syntax_element_recurse))
                   ~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/opt/local/include/boost/regex/v4/basic_regex_creator.hpp:1328:28: note: remove extraneous parentheses around the
      comparison to silence this warning
               if((p->type == syntax_element_recurse))
                  ~        ^                        ~
/opt/local/include/boost/regex/v4/basic_regex_creator.hpp:1328:28: note: use '=' to turn this equality comparison
      into an assignment
               if((p->type == syntax_element_recurse))
                           ^~
                           =
2 warnings generated.

$ ./a.out 
な
に
か
書
く