他言語からCのライブラリのラッパーを実装するときに、構造体の大きさを知りたいということは、ちょくちょくあるとおもう。
configure.ac
AC_PREREQ(2.59) AC_INIT([oreore], [0.1], [info@example.com]) AC_CONFIG_HEADERS([config.h]) AC_CHECK_SIZEOF([pthread_mutex_t], [], [#include <pthread.h>]) AC_SUBST([HOGE], [$ac_cv_sizeof_pthread_mutex_t]) AC_CONFIG_FILES([boke.txt]) AC_OUTPUT
config.h.in
#undef SIZEOF_PTHREAD_MUTEX_T
boke.txt.in
sizeof pthread_mutex_t is @HOGE@.
実行例
% autoconf % ./configure checking for gcc... no checking for cc... cc checking whether the C compiler works... yes checking for C compiler default output file name... a.out checking for suffix of executables... checking whether we are cross compiling... no checking for suffix of object files... o checking whether we are using the GNU C compiler... yes checking whether cc accepts -g... yes checking for cc option to accept ISO C89... none needed checking size of pthread_mutex_t... 8 configure: creating ./config.status config.status: creating boke.txt config.status: creating config.h % cat config.h /* config.h. Generated from config.h.in by configure. */ #define SIZEOF_PTHREAD_MUTEX_T 8 % cat boke.txt sizeof pthread_mutex_t is 8. %
