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callable_traits/example/is_constexpr_function_pointer.cpp
2016-04-15 21:41:42 -05:00

44 lines
1.1 KiB
C++

/*!<-
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 <callable_traits/is_constexpr.hpp>
#ifdef CALLABLE_TRAITS_DISABLE_CONSTEXPR_CHECKS
int main(){ return 0; }
#else
//[ is_constexpr_function_pointer
#include <type_traits>
#include <callable_traits/is_constexpr.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() {}
//]
#endif