It looks like CodeWarrior 9.3 on the Mac could use some extra type-casts to quiet it down, e.g., Warning : implicit arithmetic conversion from 'int' to 'bool' (included from: /Users/stephencarson/Development/boost/boost/boost/spirit/core/scanner/ skipper.hpp:16 /Users/stephencarson/Development/boost/boost/boost/spirit/core/ composite/impl/directives.ipp:16 /Users/stephencarson/Development/boost/boost/boost/spirit/core/ primitives/primitives.hpp:16 /Users/stephencarson/Development/boost/boost/boost/spirit/core.hpp:33 /Users/stephencarson/Development/boost/boost/boost/graph/detail/ read_graphviz_spirit.hpp:32 /Users/stephencarson/Development/boost/boost/boost/graph/graphviz.hpp: 754 /Users/stephencarson/Development/boost/boost/libs/graph/src/ read_graphviz_spirit.cpp:26) ../boost/spirit/core/primitives/impl/primitives.ipp line 181? return isalnum(to_int_type(c)); Here is one example failure: http://tinyurl.com/3t2er Anyone willing to tackle this? Doug