58 lines
1.4 KiB
C++
58 lines
1.4 KiB
C++
// Copyright (c) 2018 Andrey Semashev
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//
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// Use, modification, and distribution is subject to the Boost Software
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// License, Version 1.0. (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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// The test verifies that Boost.Optional copy constructors do not attempt to invoke
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// the element type initializing constructors from templated arguments
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#include <boost/optional/optional.hpp>
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#include <boost/core/enable_if.hpp>
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struct no_type
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{
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char data;
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};
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struct yes_type
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{
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char data[2];
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};
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template< unsigned int Size >
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struct size_tag {};
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template< typename T, typename U >
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struct is_constructible
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{
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template< typename T1, typename U1 >
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static yes_type check_helper(size_tag< sizeof(static_cast< T1 >(U1())) >*);
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template< typename T1, typename U1 >
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static no_type check_helper(...);
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static const bool value = sizeof(check_helper< T, U >(0)) == sizeof(yes_type);
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};
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template< typename T >
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class wrapper
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{
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public:
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wrapper() {}
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wrapper(wrapper const&) {}
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template< typename U >
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wrapper(U const&, typename boost::enable_if_c< is_constructible< T, U >::value, int >::type = 0) {}
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};
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inline boost::optional< wrapper< int > > foo()
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{
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return boost::optional< wrapper< int > >();
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}
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int main()
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{
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// Invokes boost::optional copy constructor. Should not invoke wrapper constructor from U.
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boost::optional< wrapper< int > > res = foo();
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return 0;
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}
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