I've discovered a bug of Borland's compiler (version 5.6.4 for Win32) standard library implementation - the errno is not a macro (as it should be according to The Standard - 17.4.1.2. p. 5), furthermore it's only in the std namespace (17.4.1.2. p. 4). Because of the second problem I'd suggest to add using std::errno line to the boost/config/compiler/borland.hpp file to make errno global as it should be, or maybe a macro BOOST_ERRNO which would evaluate to std::errno for Borland and just errno for other implementations. Am I right and how to do this/who's responsible for that?

You're almost right: the actual error you get depends on which run time library option you select, if you build with -tWM it actually complains about __errno not errno. I think the obvious fix is to just include <errno.h> and #define the symbol if it's not already like this: Index: boost/config/compiler/borland.hpp =================================================================== RCS file: /cvsroot/boost/boost/boost/config/compiler/borland.hpp,v retrieving revision 1.34 diff -r1.34 borland.hpp 59a60,64

// fix broken errno declaration: # include <errno.h> # ifndef errno # define errno errno # endif

If no-one objects that's what I propose to commit to cvs. John.