From : Beman Dawes
(defined(__linux) && (!defined(__USE_XOPEN2K) || defined(BOOST_SYSTEM_USE_STRERROR)))
Would autocnf be integrated into boost build process we could prevent such ugly Preprocessor defines. We could write: #ifdef HAS_STRERROR_R ... #else ... #endif The preprocessor define HAS_STRERROR_R could be avaluated by the m4 macro: AC_MSG_CHECKING([for strerror_r support]) AC_CACHE_VAL(ac_cv_strerror_r, AC_TRY_RUN([ # include <errno.h> # include <string.h> # include <stdlib.h> main() { strerror_r(EINTR, 0, 0); exit( 0); }], ac_cv_strerror_r=yes, ac_cv_strerror_r=no, ac_cv_strerror_r=no)) AC_MSG_RESULT($ac_cv_strerror_r) if test $ac_cv_strerror_r = yes; then AC_DEFINE([HAS_STRERROR_R],[1],[support of strerror_r]) Fi Created config.h will contain on LINUX on HP/UX it is defined as zero #ifndef HAS_STRERROR_R #define HAS_STRERROR_R 1 #endif Regards, Oliver