for_darwin_to_detect_compiler_flag.patch

--- a/configure.ac	2019-04-19 16:27:52.000000000 +0900
+++ b/configure.ac	2019-04-19 16:26:06.000000000 +0900
@@ -39,6 +39,20 @@ AC_PROG_LN_S
 dnl Compiling with per-target flags requires AM_PROG_CC_C_O.
 AC_PROG_CC
 AM_PROG_CC_C_O
+
+# Check if a compiler supports "-Wno-error=address-of-packed-member"
+# If it supports the option, we add it to CFLAGS.
+ac_save_CFLAGS="$CFLAGS"
+AC_LANG_PUSH([C])
+CFLAGS="-Wno-error=address-of-packed-member"
+AC_COMPILE_IFELSE([AC_LANG_PROGRAM([],[[]])],
+[ac_c_recognize_address_of_packed_member=1],
+[ac_c_recognize_address_of_packed_member=0])
+AC_LANG_POP([C])
+AS_IF([test $ac_c_recognize_address_of_packed_member -eq 1],
+[CFLAGS="$ac_save_CFLAGS -Wno-error=address-of-packed-member"],
+[CFLAGS="$ac_save_CFLAGS"])
+
 AC_PROG_LIBTOOL
 AC_PROG_CXX
 AC_PROG_INSTALL