From f07203fb42ee1f25868b3fc18623ed5cfd1c5b66 Mon Sep 17 00:00:00 2001
From: Moritz Bunkus <moritz@bunkus.org>
Date: Tue, 24 Jan 2017 22:44:58 +0100
Subject: [PATCH] configure: add -stdc++ flag during check for nlohmann-jsoncpp

See #1858.
---
 ac/nlohmann_jsoncpp.m4 | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/ac/nlohmann_jsoncpp.m4 b/ac/nlohmann_jsoncpp.m4
index 24fe5357f..f6ed108dc 100644
--- a/ac/nlohmann_jsoncpp.m4
+++ b/ac/nlohmann_jsoncpp.m4
@@ -6,6 +6,9 @@ dnl
 AC_CACHE_CHECK([nlohmann's json-cpp],[ac_cv_nlohmann_jsoncpp],[
   AC_LANG_PUSH(C++)
 
+  ac_save_CXXFLAGS="$CXXFLAGS"
+  CXXFLAGS="$STD_CXX $CXXFLAGS"
+
   AC_TRY_COMPILE([
     #include <cstdint>
     #include <iostream>
@@ -21,6 +24,8 @@ AC_CACHE_CHECK([nlohmann's json-cpp],[ac_cv_nlohmann_jsoncpp],[
     std::cout << json.dump();
   ],[ac_cv_nlohmann_jsoncpp=yes],[ac_cv_nlohmann_jsoncpp=no])
 
+  CXXFLAGS="$ac_save_CXXFLAGS"
+
   AC_LANG_POP
 ])