From 7d212fd67dc3f580fc9a0cd5ce77a14519bda31b Mon Sep 17 00:00:00 2001
From: badair <badair@harding.edu>
Date: Thu, 31 Mar 2016 01:59:08 -0500
Subject: [PATCH] adding function example for is_constexpr

---
 example/is_constexpr/function.cpp          | 36 ++++++++++++++++++++
 include/callable_traits/detail/any_arg.hpp |  4 ---
 qtcreator/main/main.cpp                    | 38 +++++++++++++++-------
 3 files changed, 62 insertions(+), 16 deletions(-)
 create mode 100644 example/is_constexpr/function.cpp

diff --git a/example/is_constexpr/function.cpp b/example/is_constexpr/function.cpp
new file mode 100644
index 0000000..d8cdef0
--- /dev/null
+++ b/example/is_constexpr/function.cpp
@@ -0,0 +1,36 @@
+
+/*!
+Copyright (c) 2016 Barrett Adair
+
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+*/
+
+#include <type_traits>
+#include <callable_traits/callable_traits.hpp>
+
+// NOTE: Due to non-compliance in MSVC, is_constexpr always
+// returns std::false_type on that compiler, which causes
+// the static asserts below to fail.
+
+namespace ct = callable_traits;
+
+constexpr int foo(const int&) {
+    return 1;
+}
+
+int bar(const int&) {
+    return 1;
+}
+
+// for is_constexpr calls, function pointers must
+// be passed as std::integral_constants
+using F = std::integral_constant<decltype(&foo), &foo>;
+using B = std::integral_constant<decltype(&bar), &bar>;
+
+static_assert(ct::is_constexpr(F{}), "");
+static_assert(ct::is_constexpr<F>(), "");
+static_assert(!ct::is_constexpr(B{}), "");
+static_assert(!ct::is_constexpr<B>(), "");
+
+int main() { return 0; }
diff --git a/include/callable_traits/detail/any_arg.hpp b/include/callable_traits/detail/any_arg.hpp
index b279c3f..fff1338 100644
--- a/include/callable_traits/detail/any_arg.hpp
+++ b/include/callable_traits/detail/any_arg.hpp
@@ -65,10 +65,6 @@ namespace callable_traits {
         template<std::size_t I>
         const any_arg_evaluated<I> any_arg_evaluated<I>::value = {};
 
-#undef CALLABLE_TRAITS_CONCAT_
-#undef CALLABLE_TRAITS_CONCAT
-#undef CALLABLE_TRAITS_INITIALIZE_ANY_ARG_VALUE
-
         //any_arg is only used in unevaluated contexts
         template<std::size_t I = 0>
         struct any_arg : any_arg_evaluated<I> {
diff --git a/qtcreator/main/main.cpp b/qtcreator/main/main.cpp
index 4b3e211..d8cdef0 100644
--- a/qtcreator/main/main.cpp
+++ b/qtcreator/main/main.cpp
@@ -1,22 +1,36 @@
-/*
-Copyright Barrett Adair 2016
+
+/*!
+Copyright (c) 2016 Barrett Adair
+
 Distributed under the Boost Software License, Version 1.0.
-(See accompanying file LICENSE.md or copy at http ://boost.org/LICENSE_1_0.txt)
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
 */
 
 #include <type_traits>
 #include <callable_traits/callable_traits.hpp>
 
-struct foo{};
+// NOTE: Due to non-compliance in MSVC, is_constexpr always
+// returns std::false_type on that compiler, which causes
+// the static asserts below to fail.
 
 namespace ct = callable_traits;
 
-using pmf = void(foo::*)();
-using test = ct::add_const_qualifier<pmf>;
-using expect = void(foo::*)() const;
-
-static_assert(std::is_same<test, expect>{}, "");
-
-int main() {
-    return 0;
+constexpr int foo(const int&) {
+    return 1;
 }
+
+int bar(const int&) {
+    return 1;
+}
+
+// for is_constexpr calls, function pointers must
+// be passed as std::integral_constants
+using F = std::integral_constant<decltype(&foo), &foo>;
+using B = std::integral_constant<decltype(&bar), &bar>;
+
+static_assert(ct::is_constexpr(F{}), "");
+static_assert(ct::is_constexpr<F>(), "");
+static_assert(!ct::is_constexpr(B{}), "");
+static_assert(!ct::is_constexpr<B>(), "");
+
+int main() { return 0; }