From b53eb516030c45d551640a1c0af871458eafa123 Mon Sep 17 00:00:00 2001
From: Henry Fredrick Schreiner <henry.fredrick.schreiner@cern.ch>
Date: Mon, 3 Sep 2018 20:24:30 +0200
Subject: [PATCH] Fix for experimental optional with optional #158

---
 include/CLI/Optional.hpp | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/include/CLI/Optional.hpp b/include/CLI/Optional.hpp
index faaee366..b1084657 100644
--- a/include/CLI/Optional.hpp
+++ b/include/CLI/Optional.hpp
@@ -10,13 +10,16 @@
 // [CLI11:verbatim]
 #ifdef __has_include
 
+// You can explicitly enable or disable support
+// by defining these to 1 or 0.
 #if defined(CLI11_CPP17) && __has_include(<optional>) && \
      !defined(CLI11_STD_OPTIONAL)
 #define CLI11_STD_OPTIONAL 1
 #endif
 
 #if defined(CLI11_CPP14) && __has_include(<experimental/optional>) && \
-    !defined(CLI11_EXPERIMENTAL_OPTIONAL)
+    !defined(CLI11_EXPERIMENTAL_OPTIONAL) \
+    && (!defined(CLI11_STD_OPTIONAL) || CLI11_STD_OPTIONAL != 0)
 #define CLI11_EXPERIMENTAL_OPTIONAL 1
 #endif