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User library tests have been reporting numerous failures due to internal compiler errors that occur when perfect forwarding is unsupported. Setting BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY to zero eliminates these failures. By doing this in Boost.Parameter, we relieve user code of the burden of doing this in their end. The trade-off is that our own tests need to define BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY explicitly in order to take advantage of the benefits of not having to wrap boost::ref() or std::ref() around non-const lvalues. As this was always a C++03 workaround, the change should be worth the trade-off. On an unrelated note, Travis Cl just deprecated "sudo: false". See <https://blog.travis-ci.com/2018-10-04-combining-linux-infrastructures>.
84 lines
2.0 KiB
C++
84 lines
2.0 KiB
C++
// Copyright Daniel Wallin 2006.
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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#include <boost/parameter/config.hpp>
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#if !defined(BOOST_PARAMETER_HAS_PERFECT_FORWARDING)
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#if (BOOST_PARAMETER_MAX_ARITY < 2)
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#error Define BOOST_PARAMETER_MAX_ARITY as 2 or greater.
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#endif
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#if (BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY < 2)
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#error Define BOOST_PARAMETER_EXPONENTIAL_OVERLOAD_THRESHOLD_ARITY \
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as 2 or greater.
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#endif
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#endif
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#include <boost/parameter/preprocessor.hpp>
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#include <boost/parameter/name.hpp>
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#include <boost/tuple/tuple.hpp>
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#include <boost/mpl/bool.hpp>
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#include <boost/mpl/if.hpp>
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#include <boost/tti/detail/dnullptr.hpp>
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#include <boost/core/enable_if.hpp>
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#include <boost/type_traits/is_convertible.hpp>
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#include <string>
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namespace test {
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BOOST_PARAMETER_NAME(x)
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struct predicate
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{
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template <typename T, typename Args>
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struct apply
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: boost::mpl::if_<
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boost::is_convertible<T,char const*>
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, boost::mpl::true_
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, boost::mpl::false_
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>
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{
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};
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};
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BOOST_PARAMETER_FUNCTION((int), sfinae, test::tag,
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(deduced
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(optional
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(x
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, *(test::predicate)
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, static_cast<char const*>(BOOST_TTI_DETAIL_NULLPTR)
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)
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)
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)
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)
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{
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return 1;
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}
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template <typename A0>
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typename boost::enable_if<
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typename boost::mpl::if_<
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boost::is_same<int,A0>
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, boost::mpl::true_
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, boost::mpl::false_
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>::type
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, int
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>::type
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sfinae(A0 const& a0)
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{
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return 0;
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}
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} // namespace test
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#include <boost/core/lightweight_test.hpp>
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int main()
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{
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BOOST_TEST_EQ(1, test::sfinae());
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BOOST_TEST_EQ(1, test::sfinae("foo"));
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BOOST_TEST_EQ(0, test::sfinae(1));
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return boost::report_errors();
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}
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