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131
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1 // P0595R1
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145
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2 // { dg-do run { target c++14 } }
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131
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3
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4 template<int N> struct X { int v = N; };
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5 X<__builtin_is_constant_evaluated ()> x; // type X<true>
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6 int y = 4;
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7 int a = __builtin_is_constant_evaluated () ? y : 1; // initializes a to 1
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8 int b = __builtin_is_constant_evaluated () ? 2 : y; // initializes b to 2
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9 int c = y + (__builtin_is_constant_evaluated () ? 2 : y); // initializes c to 2*y
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10 int d = __builtin_is_constant_evaluated (); // initializes d to 1
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145
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11 int e = d + __builtin_is_constant_evaluated (); // initializes e to 1 + 0
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131
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12
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13 struct false_type { static constexpr bool value = false; };
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14 struct true_type { static constexpr bool value = true; };
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15 template<class T, class U>
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16 struct is_same : false_type {};
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17 template<class T>
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18 struct is_same<T, T> : true_type {};
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19
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20 constexpr int
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21 foo (int x)
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22 {
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23 const int n = __builtin_is_constant_evaluated () ? 13 : 17; // n == 13
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24 int m = __builtin_is_constant_evaluated () ? 13 : 17; // m might be 13 or 17 (see below)
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25 char arr[n] = {}; // char[13]
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26 return m + sizeof (arr) + x;
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27 }
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28
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29 constexpr int
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30 bar ()
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31 {
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32 const int n = __builtin_is_constant_evaluated() ? 13 : 17;
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33 X<n> x1;
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34 X<__builtin_is_constant_evaluated() ? 13 : 17> x2;
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35 static_assert (is_same<decltype (x1), decltype (x2)>::value, "x1/x2's type");
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36 return x1.v + x2.v;
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37 }
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38
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39 int p = foo (0); // m == 13; initialized to 26
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40 int q = p + foo (0); // m == 17 for this call; initialized to 56
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41 static_assert (bar () == 26, "bar");
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42
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43 struct S { int a, b; };
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44
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45 S s = { __builtin_is_constant_evaluated () ? 2 : 3, y };
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46 S t = { __builtin_is_constant_evaluated () ? 2 : 3, 4 };
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47
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48 static_assert (is_same<decltype (x), X<true> >::value, "x's type");
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49
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50 int
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51 main ()
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52 {
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145
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53 if (a != 1 || b != 2 || c != 8 || d != 1 || e != 1 || p != 26 || q != 56)
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54 __builtin_abort ();
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55 if (s.a != 3 || s.b != 4 || t.a != 2 || t.b != 4)
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56 __builtin_abort ();
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57 if (foo (y) != 34)
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58 __builtin_abort ();
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59 #if __cplusplus >= 201703L
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60 if constexpr (foo (0) != 26)
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61 __builtin_abort ();
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62 #endif
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63 constexpr int w = foo (0);
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64 if (w != 26)
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65 __builtin_abort ();
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66 }
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