Dear list,
I'm trying to write a program that can use custom stdio streams on both
Linux/glibc and FreeBSD, and to that end, I'm trying to modify to autoconf
script to properly detect these and turn on the necessary compiler flags
to support them.
On glibc, I need to define `_GNU_SOURCE' in order to gain access to
fopencookie() and cookie_io_functions_t. Autoconf neatly supports turning
this on with `AC_USE_SYSTEM_EXTENSIONS(_GNU_SOURCE)', but I can't quite
seem to figure out how to only do this when necessary. Currently, I'm
trying to do it like this:
HAS_FOPENCOOKIE=yes
AC_CHECK_FUNC(fopencookie, [AC_USE_SYSTEM_EXTENSIONS(_GNU_SOURCE)], [HAS_FOPENCOOKIE=no])
AC_CHECK_MEMBER([cookie_io_functions_t.read], [], [HAS_FOPENCOOKIE=no])
This /works/, per se, but autoconf complains loudly when I try to generate
the configure script, several times, that `AC_COMPILE_IFELSE was called
before AC_USE_SYSTEM_EXTENSIONS'. Apparently, it thinks it is really bad
practice to actually do any tests before turning on system extensions.
What should I do about this? Just ignore the warnings? Do the necessary
AC_DEFINE manually instead? (This seems ugly, since I'd need to define an
`AH_TEMPLATE` as well and all that.) Just turn on all extensions that I
may or may not use, unconditionally at the top of the file? Something
completely different?
Thanks for reading!
--
Fredrik Tolf
_______________________________________________
Autoconf mailing list
Autoconf@xxxxxxx
https://lists.gnu.org/mailman/listinfo/autoconf
