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