> Date: Mon, 26 Jul 2010 16:55:20 +0100 > From: Daniel Stone <dan...@fooishbar.org> > > On Mon, Jul 26, 2010 at 05:48:10PM +0200, Mark Kettenis wrote: > > > From: Daniel Stone <dan...@fooishbar.org> > > > Date: Mon, 26 Jul 2010 16:31:15 +0100 > > >=20 > > > sqrt and cbrt are only defined in math.h, so we have to include that > > > when checking for them, lest we miss it, and then some other header > > > pulling in math.h causes build failures due to multiple definitions. > >=20 > > Eh, why? AC_CHECK_LIB is supposed to check whether these symbols are > > available in the given library in a way that doesn't depend on a > > prototype for them being in scope. So I don't see what you diff > > achieves, other than adding more clutter to the configure scripts. > > Well, it does depend on a prototype for them being in scope. It > constructs a basic int main(...) { foo(); } bit of source with > AC_LANG_CALL and then attempts to link it: > > AC_DEFUN([AC_CHECK_LIB], > [m4_ifval([$3], , [AH_CHECK_LIB([$1])])dnl > AS_LITERAL_IF([$1], > [AS_VAR_PUSHDEF([ac_Lib], [ac_cv_lib_$1_$2])], > [AS_VAR_PUSHDEF([ac_Lib], [ac_cv_lib_$1''_$2])])dnl > AC_CACHE_CHECK([for $2 in -l$1], [ac_Lib], > [ac_check_lib_save_LIBS=3D$LIBS > LIBS=3D"-l$1 $5 $LIBS" > AC_LINK_IFELSE([AC_LANG_CALL([], [$2])], > [AS_VAR_SET([ac_Lib], [yes])], > [AS_VAR_SET([ac_Lib], [no])]) > LIBS=3D$ac_check_lib_save_LIBS]) > AS_VAR_IF([ac_Lib], [yes], > [m4_default([$3], [AC_DEFINE_UNQUOTED(AS_TR_CPP(HAVE_LIB$1)) > LIBS=3D"-l$1 $LIBS" > ])], > [$4]) > AS_VAR_POPDEF([ac_Lib])dnl > ])# AC_CHECK_LIB
Well, that fragment is supposed to compile fine even without a prototype for foo(), so there must be something else going on. _______________________________________________ xorg-devel@lists.x.org: X.Org development Archives: http://lists.x.org/archives/xorg-devel Info: http://lists.x.org/mailman/listinfo/xorg-devel