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111
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1 // { dg-do compile { target c++11 } }
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2
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3 namespace std { template <class T> T&& declval(); }
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4
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5 template<typename _Tp, typename... _Args>
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6 class is_constructible_mini
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7 {
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8 typedef char __one;
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9 typedef struct { char __arr[2]; } __two;
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10
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11 template<typename _Tp1, typename... _Args1>
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12 static decltype(::new _Tp1(std::declval<_Args1>()...), __one())
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13 __test(int);
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14
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15 template<typename, typename...>
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16 static __two __test(...);
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17
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18 public:
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19 static const bool value = sizeof(__test<_Tp, _Args...>(0)) == 1;
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20 };
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21
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22 /*
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23 template<typename _Tp>
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24 class is_constructible_mini<_Tp>
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25 {
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26 typedef char __one;
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27 typedef struct { char __arr[2]; } __two;
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28
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29 template<typename _Tp1>
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30 static decltype(::new _Tp1, __one()) __test(int);
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31
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32 template<typename>
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33 static __two __test(...);
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34
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35 public:
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36 static const bool value
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37 = sizeof(__test<typename std::remove_cv<_Tp>::type>(0)) == 1;
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38 };
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39 */
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40
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41 struct A
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42 {
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43 A(int);
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44 };
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45
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46 struct B { };
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47
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48 static_assert( is_constructible_mini<A, int>::value, "");
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49 static_assert( is_constructible_mini<A, A>::value, "");
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50 static_assert( !is_constructible_mini<A, int, double>::value, "");
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51
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52 static_assert( !is_constructible_mini<A>::value, ""); // doesn't compile without the
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53 // partial specialization
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54
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55 static_assert( is_constructible_mini<B>::value, "");
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56 static_assert( is_constructible_mini<const B>::value, "");
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