From 09c169c2d983714ec875fa3013123a4566b15ecd Mon Sep 17 00:00:00 2001
From: fpeng1985 <fpeng1985@gmail.com>
Date: Thu, 19 Sep 2019 02:24:24 +0800
Subject: [PATCH] refine the implementation of has_find type_traits (#319)

* refine the implementation of has_find type_traits

* Format fix
---
 include/CLI/Validators.hpp | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/include/CLI/Validators.hpp b/include/CLI/Validators.hpp
index e3736845..b4586ed1 100644
--- a/include/CLI/Validators.hpp
+++ b/include/CLI/Validators.hpp
@@ -501,14 +501,14 @@ template <typename T> std::string generate_map(const T &map, bool key_only = fal
     return out;
 }
 
-template <typename> struct sfinae_true : std::true_type {};
-/// Function to check for the existence of a member find function which presumably is more efficient than looping over
-/// everything
-template <typename T, typename V>
-static auto test_find(int) -> sfinae_true<decltype(std::declval<T>().find(std::declval<V>()))>;
-template <typename, typename V> static auto test_find(long) -> std::false_type;
+template <typename C, typename V> struct has_find {
+    template <typename CC, typename VV>
+    static auto test(int) -> decltype(std::declval<CC>().find(std::declval<VV>()), std::true_type());
+    template <typename, typename> static auto test(...) -> decltype(std::false_type());
 
-template <typename T, typename V> struct has_find : decltype(test_find<T, V>(0)) {};
+    static const auto value = decltype(test<C, V>(0))::value;
+    using type = std::integral_constant<bool, value>;
+};
 
 /// A search function
 template <typename T, typename V, enable_if_t<!has_find<T, V>::value, detail::enabler> = detail::dummy>