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// (C) Copyright Kohei Takahashi 2014,2016
// Use, modification and distribution are subject to the
// Boost Software License, Version 1.0. (See accompanying file
// LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
// See http://www.boost.org/libs/config for more information.
// MACRO: BOOST_NO_CXX14_CONSTEXPR
// TITLE: C++14 relaxed constexpr unavailable
// DESCRIPTION: The compiler does not support C++14 relaxed constexpr
namespace boost_no_cxx14_constexpr
{
namespace detail
{
template <class> struct void_ { typedef void type; };
struct non_tmpl
{
constexpr int foo() const { return 1; }
constexpr int foo() { return 0; }
};
template <typename T>
struct tmpl : non_tmpl { };
}
// Test relaxed constexpr with dependent type; for more details, see comment of
// BOOST_CXX14_CONSTEXPR definition in boost/config/compiler/clang.hpp .
template <class T>
constexpr typename detail::void_<T>::type decrement(T &value)
{
--value;
}
constexpr int non_cv_member(detail::non_tmpl x)
{
return x.foo();
}
template <typename T>
constexpr int non_cv_member(detail::tmpl<T> x)
{
return x.foo();
}
constexpr int zero()
{
int ret = 1;
decrement(ret);
return ret;
}
template <int v> struct compile_time_value
{
static constexpr int value = v;
};
int test()
{
return compile_time_value<
zero()
+ non_cv_member(detail::non_tmpl())
+ non_cv_member(detail::tmpl<int>())
>::value;
}
}
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