http://bugs.gentoo.org/247067 --- m4/ACX_PTHREAD.m4 +++ m4/ACX_PTHREAD.m4 @@ -266,6 +266,117 @@ else PTHREAD_CC=$CC fi + + # The next part tries to detect GCC inconsistency with -shared on some + # architectures and systems. The problem is that in certain + # configurations, when -shared is specified, GCC "forgets" to + # internally use various flags which are still necessary. + + # + # Prepare the flags + # + save_LDFLAGS="$LDFLAGS" + save_CFLAGS="$CFLAGS" + save_LIBS="$LIBS" + save_CC="$CC" + + # Try with the flags determined by the earlier checks. + # + # -Wl,-z,defs forces link-time symbol resolution, so that the + # linking checks with -shared actually have any value + # + # FIXME: -fPIC is required for -shared on many architectures, + # so we specify it here, but the right way would probably be to + # properly detect whether it is actually required. + CFLAGS="-shared -fPIC -Wl,-z,defs $CFLAGS $PTHREAD_CFLAGS" + LIBS="$PTHREAD_LIBS $LIBS" + CC="$PTHREAD_CC" + + # In order not to create several levels of indentation, we test + # the value of "$done" until we find the cure or run out of ideas. + done="no" + + # First, make sure the CFLAGS we added are actually accepted by our + # compiler. If not (and OS X's ld, for instance, does not accept -z), + # then we can't do this test. + if test x"$done" = xno; then + AC_MSG_CHECKING([whether to check for GCC pthread/shared inconsistencies]) + AC_TRY_LINK(,, , [done=yes]) + + if test "x$done" = xyes ; then + AC_MSG_RESULT([no]) + else + AC_MSG_RESULT([yes]) + fi + fi + + if test x"$done" = xyes; then + done="no" + AC_MSG_CHECKING([whether -pthread is sufficient with -shared]) + AC_TRY_LINK([#include ], + [pthread_t th; pthread_join(th, 0); + pthread_attr_init(0); pthread_cleanup_push(0, 0); + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], + [done=yes]) + + if test "x$done" = xyes; then + AC_MSG_RESULT([yes]) + else + AC_MSG_RESULT([no]) + fi + fi + + # + # Linux gcc on some architectures such as mips/mipsel forgets + # about -lpthread + # + if test x"$done" = xno; then + AC_MSG_CHECKING([whether -lpthread fixes that]) + LIBS="-lpthread $PTHREAD_LIBS $save_LIBS" + AC_TRY_LINK([#include ], + [pthread_t th; pthread_join(th, 0); + pthread_attr_init(0); pthread_cleanup_push(0, 0); + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], + [done=yes]) + + if test "x$done" = xyes; then + AC_MSG_RESULT([yes]) + PTHREAD_LIBS="-lpthread $PTHREAD_LIBS" + else + AC_MSG_RESULT([no]) + fi + fi + # + # FreeBSD 4.10 gcc forgets to use -lc_r instead of -lc + # + if test x"$done" = xno; then + AC_MSG_CHECKING([whether -lc_r fixes that]) + LIBS="-lc_r $PTHREAD_LIBS $save_LIBS" + AC_TRY_LINK([#include ], + [pthread_t th; pthread_join(th, 0); + pthread_attr_init(0); pthread_cleanup_push(0, 0); + pthread_create(0,0,0,0); pthread_cleanup_pop(0); ], + [done=yes]) + + if test "x$done" = xyes; then + AC_MSG_RESULT([yes]) + PTHREAD_LIBS="-lc_r $PTHREAD_LIBS" + else + AC_MSG_RESULT([no]) + fi + fi + if test x"$done" = xno; then + # OK, we have run out of ideas + AC_MSG_WARN([Impossible to determine how to use pthreads with shared libraries]) + + # so it's not safe to assume that we may use pthreads + acx_pthread_ok=no + fi + + CFLAGS="$save_CFLAGS" + LIBS="$save_LIBS" + CC="$save_CC" + else PTHREAD_CC="$CC" fi