On 25/08/2017 06:25, Gavin Lambert via Boost wrote:
On 25/08/2017 17:42, Antony Polukhin wrote:
FreeBSD has the required function definition here: https://github.com/lattera/freebsd/blob/master/include/unwind.h#L137 It is available if _GNU_SOURCE or _BSD_SOURCE macro is defined.
I have no idea why _BSD_SOURCE is not defined on FreeBSD. If there's some file that defines those macro, please send me the file name and path, and I'll include it in the Stacktrace library before the inclusion of unwind.h,
_GNU_SOURCE and _BSD_SOURCE (among others) are never defined in the library headers -- they are application/project-level settings to indicate that the application author is willing to sacrifice portability in order to have access to additional features, and which of the (sometimes incompatible) extensions they prefer.
Library authors don't get to choose (except when building private translation units); they have to adapt to whatever the application picked.
ie. you should probably be testing those macros and either selecting alternate functionality or emitting a more comprehensible warning/error if not defined, rather than let it generate a regular missing symbol error.
It's within a source file rather than a header, so it's entirely appropriate to define _GNU_SOURCE or _BSD_SOURCE before including any headers, isn't it? A quick grep through the Boost sources shows multiple examples of this type of usage. % grep -R _GNU_SOURCE * tools/build/src/engine/jamgram.c:# if defined __GLIBC__ && defined _STRING_H && defined _GNU_SOURCE tools/build/src/engine/boehm_gc/dyn_load.c: && !defined(_GNU_SOURCE) tools/build/src/engine/boehm_gc/dyn_load.c:# define _GNU_SOURCE Jamroot: <toolset>como-linux:<define>_GNU_SOURCE=1 libs/asio/test/Jamfile.v2: <os>LINUX:<define>_GNU_SOURCE=1 libs/program_options/src/parsers.cpp:// and in case they came from glibc and _GNU_SOURCE was defined.) libs/config/test/config_info.cpp: PRINT_MACRO(_GNU_SOURCE); libs/container/src/dlmalloc_2_8_6.c:#define _GNU_SOURCE /* Turns on mremap() definition */ boost/python/detail/python22_fixed.h:#ifndef _GNU_SOURCE boost/python/detail/python22_fixed.h:# define _GNU_SOURCE 1 Note a work in progress fix here does just this; the error it's making is undefing it after the includes: https://reviews.freebsd.org/differential/changeset/?ref=313538&whitespace=ignore-most Though I'm not sure why Boost's build system wouldn't set _GNU_SOURCE or _BSD_SOURCE when building all cpp source files on GNU/BSD systems. Regards, Roger