From 387f2d622d525f6f05f9990c0e7e9d343f174fb8 Mon Sep 17 00:00:00 2001
From: Peter van Dijk <peter.van.dijk@powerdns.com>
Date: Tue, 14 Nov 2017 10:17:58 +0100
Subject: [PATCH] Backport #5955: recent Apple Xcode headers need this

reference: https://github.com/arvidn/libtorrent/issues/2364#issuecomment-336175406
(cherry picked from commit e201675a3aa63712f8d08c27f2cedc10873b8f4c)
---
 m4/pdns_check_os.m4 | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/m4/pdns_check_os.m4 b/m4/pdns_check_os.m4
index ba6546dfa..860f9aa0e 100644
--- a/m4/pdns_check_os.m4
+++ b/m4/pdns_check_os.m4
@@ -19,7 +19,7 @@ AC_DEFUN([PDNS_CHECK_OS],[
     have_linux="yes"
     ;;
   darwin*)
-    CXXFLAGS="-D__APPLE_USE_RFC_3542 -D_XOPEN_SOURCE $CXXFLAGS"
+    CXXFLAGS="-D__APPLE_USE_RFC_3542 -D_XOPEN_SOURCE -D_DARWIN_C_SOURCE $CXXFLAGS"
     ;;
   freebsd*)
     THREADFLAGS="-pthread"
-- 
2.40.0