Looking at the regressions for 1.33.1 stl_concept_covering.cpp seems not to compile with any compiler at present. Looking at the source there is one obvious error: out = std::fill_n(out, n, value); But fill_n returns void ! Then there are lots of preprocessor sections along the lines of: #if defined(__GNUC__) typedef less_than_op_first_archetype<> FT; typedef less_than_op_second_archetype<> T; #elif defined(__KCC) // The KAI version of this uses a one-argument less-than function // object. typedef less_than_comparable_archetype<> T; typedef convertible_to_archetype<T> FT; #endif forward_iterator_archetype<FT> fi; T value(dummy_cons); fi = std::lower_bound(fi, fi, value); Which can clearly never compiler on any compiler other than GCC or KCC. However, fixing these issues still doesn't get the code compiling on any platform I have access to. Some of these will be std lib conceptual errors, but *something* should compile this source, otherwise what's the point? Regards, John.