This use case seems really common and I was surprised it gave me problems. I assume that nullptr_t in C++11 fixes this but then I was wondering if the cases were basic and common enough it would make sense to have a BOOST_CHECK_NULL / BOOST_CHECK_NOT_NULL and the assorted variants. james --- #define BOOST_TEST_DYN_LINK #define BOOST_TEST_MODULE Hello #include // main() etc... is defined by the headers BOOST_AUTO_TEST_CASE( null_compare ) { const char *ptr = NULL; // // Equality comparisons with NULL Fail to compile using boost 1.46 // and g++-4.6 // // /usr/include/boost/test/test_tools.hpp:536:20: // error: ISO C++ forbids comparison between pointer and // integer [-fpermissive] // // Which seems to be flagging this // // template // predicate_result equal_impl( Left const& left, Right const& right ) // { // return left == right; // } // // Where Left is of type "const char *" and Right is of type "long int". // BOOST_CHECK_EQUAL(ptr, NULL); // // these tests compile and pass // BOOST_CHECK(ptr == NULL); BOOST_CHECK_EQUAL(ptr, ptr); BOOST_CHECK_EQUAL(ptr, (void *)ptr); BOOST_CHECK_EQUAL(ptr, (void *)NULL); } ... example.cc:33:1: error: passing NULL to non-pointer argument 9 of ‘bool boost::test_tools::tt_detail::check_frwd(Pred, const boost::unit_test::lazy_ostream&, boost::test_tools::const_string, std::size_t, boost::test_tools::tt_detail::tool_level, boost::test_tools::tt_detail::check_type, const Arg0&, const char*, const Arg1&, const char*) [with Pred = boost::test_tools::tt_detail::equal_impl_frwd, Arg0 = const char*, Arg1 = long int, boost::test_tools::const_string = boost::unit_test::basic_cstring<const char>, std::size_t = long unsigned int]’ [-Werror=conversion-null] example.cc:33:1: error: passing NULL to non-pointer argument 9 of ‘bool boost::test_tools::tt_detail::check_frwd(Pred, const boost::unit_test::lazy_ostream&, boost::test_tools::const_string, std::size_t, boost::test_tools::tt_detail::tool_level, boost::test_tools::tt_detail::check_type, const Arg0&, const char*, const Arg1&, const char*) [with Pred = boost::test_tools::tt_detail::equal_impl_frwd, Arg0 = const char*, Arg1 = long int, boost::test_tools::const_string = boost::unit_test::basic_cstring<const char>, std::size_t = long unsigned int]’ [-Werror=conversion-null] In file included from /usr/include/boost/test/unit_test.hpp:19:0, from example.cc:7: /usr/include/boost/test/test_tools.hpp: In function ‘boost::test_tools::predicate_result boost::test_tools::tt_detail::equal_impl(const Left&, const Right&) [with Left = const char*, Right = long int]’: /usr/include/boost/test/test_tools.hpp:560:40: instantiated from ‘boost::test_tools::predicate_result boost::test_tools::tt_detail::equal_impl_frwd::call_impl(const Left&, const Right&, mpl_::false_) const [with Left = const char*, Right = long int, mpl_::false_ = mpl_::bool_<false>]’ /usr/include/boost/test/test_tools.hpp:575:56: instantiated from ‘boost::test_tools::predicate_result boost::test_tools::tt_detail::equal_impl_frwd::operator()(const Left&, const Right&) const [with Left = const char*, Right = long int]’ /usr/include/boost/test/test_tools.hpp:523:1: instantiated from ‘bool boost::test_tools::tt_detail::check_frwd(Pred, const boost::unit_test::lazy_ostream&, boost::test_tools::const_string, std::size_t, boost::test_tools::tt_detail::tool_level, boost::test_tools::tt_detail::check_type, const Arg0&, const char*, const Arg1&, const char*) [with Pred = boost::test_tools::tt_detail::equal_impl_frwd, Arg0 = const char*, Arg1 = long int, boost::test_tools::const_string = boost::unit_test::basic_cstring<const char>, std::size_t = long unsigned int]’ example.cc:33:1: instantiated from here /usr/include/boost/test/test_tools.hpp:536:20: error: ISO C++ forbids comparison between pointer and integer [-fpermissive]