+ dnl First, check whether -Werror can be added to the command line, or
+ dnl whether it leads to an error because of some other option that the
+ dnl user has put into $CC $CFLAGS $CPPFLAGS.
+ AC_MSG_CHECKING([whether the -Werror option is usable])
+ AC_CACHE_VAL([gl_cv_cc_vis_werror], [
+ gl_save_CFLAGS="$CFLAGS"
+ CFLAGS="$CFLAGS -Werror"
+ AC_COMPILE_IFELSE(
+ [AC_LANG_PROGRAM([[]], [[]])],
+ [gl_cv_cc_vis_werror=yes],
+ [gl_cv_cc_vis_werror=no])
+ CFLAGS="$gl_save_CFLAGS"])
+ AC_MSG_RESULT([$gl_cv_cc_vis_werror])
+ dnl Now check whether visibility declarations are supported.