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comparison gcc/testsuite/g++.dg/cpp2a/constexpr-new5.C @ 145:1830386684a0

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gcc-9.2.0
author anatofuz
date Thu, 13 Feb 2020 11:34:05 +0900
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131:84e7813d76e9 145:1830386684a0
1 // P0784R7
2 // { dg-do compile { target c++2a } }
3
4 namespace std
5 {
6 typedef __SIZE_TYPE__ size_t;
7
8 template <typename T>
9 struct allocator
10 {
11 constexpr allocator () noexcept {}
12
13 constexpr T *allocate (size_t n)
14 { return static_cast<T *> (::operator new (n * sizeof(T))); }
15
16 constexpr void
17 deallocate (T *p, size_t n)
18 { ::operator delete (p); }
19 };
20
21 template <typename T, typename U = T &&>
22 U __declval (int);
23 template <typename T>
24 T __declval (long);
25 template <typename T>
26 auto declval () noexcept -> decltype (__declval<T> (0));
27
28 template <typename T>
29 struct remove_reference
30 { typedef T type; };
31 template <typename T>
32 struct remove_reference<T &>
33 { typedef T type; };
34 template <typename T>
35 struct remove_reference<T &&>
36 { typedef T type; };
37
38 template <typename T>
39 constexpr T &&
40 forward (typename std::remove_reference<T>::type &t) noexcept
41 { return static_cast<T&&> (t); }
42
43 template<typename T>
44 constexpr T &&
45 forward (typename std::remove_reference<T>::type &&t) noexcept
46 { return static_cast<T&&> (t); }
47
48 template <typename T, typename... A>
49 constexpr auto
50 construct_at (T *l, A &&... a)
51 noexcept (noexcept (::new ((void *) 0) T (std::declval<A> ()...)))
52 -> decltype (::new ((void *) 0) T (std::declval<A> ()...))
53 { return ::new ((void *) l) T (std::forward<A> (a)...); }
54
55 template <typename T>
56 constexpr inline void
57 destroy_at (T *l)
58 { l->~T (); }
59 }
60
61 inline void *operator new (std::size_t, void *p) noexcept
62 { return p; }
63
64 constexpr bool
65 foo ()
66 {
67 std::allocator<int> a;
68 auto p = a.allocate (2);
69 std::construct_at (p, 1);
70 std::construct_at (p + 1, 2);
71 if (p[0] != 1 || p[1] != 2)
72 throw 1;
73 std::destroy_at (p);
74 std::destroy_at (p + 1);
75 a.deallocate (p, 2);
76 return true;
77 }
78
79 static_assert (foo ());