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