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131
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1 // { dg-do compile { target c++17 } }
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2 // { dg-options "-fconcepts" }
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111
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3
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4 template<typename T>
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5 concept bool C()
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6 {
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7 return requires (T t) { t.mf(); };
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8 }
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9
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10 template<typename T>
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11 concept bool CA1()
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12 {
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13 return C<typename T::ca1_type>();
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14 }
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15
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16 template<typename T>
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17 concept bool CA2()
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18 {
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19 return CA1<T>() && requires () { typename T::ca2_type; };
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20 }
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21
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22 template<typename T>
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23 concept bool CA3()
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24 {
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25 return CA2<T>() && requires () { typename T::ca3_type; };
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26 }
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27
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28 template<typename T>
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29 concept bool CB1()
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30 {
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31 return requires () { typename T::cb1_type; };
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32 }
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33
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34 template<typename T>
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35 concept bool CB2()
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36 {
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37 return CB1<T>() && requires () { typename T::cb2_type; };
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38 }
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39
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40 template<typename T>
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41 concept bool CB3()
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42 {
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43 return CB2<T>() && requires () { typename T::cb3_type; };
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44 }
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45
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46
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47 struct MC { void mf(); };
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48 static_assert(C<MC>(), "");
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49
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50
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51 struct MA1 { using ca1_type = MC; };
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52 struct MA2 : MA1 { using ca2_type = int; };
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53 struct MA3 : MA2 { using ca3_type = int; };
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54 static_assert(CA1<MA1>(), "");
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55 static_assert(CA2<MA2>(), "");
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56 static_assert(CA3<MA3>(), "");
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57
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58 struct MB1 { using cb1_type = int; };
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59 struct MB2 : MB1 { using cb2_type = int; };
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60 struct MB3 : MB2 { using cb3_type = int; };
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61 static_assert(CB1<MB1>(), "");
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62 static_assert(CB2<MB2>(), "");
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63 static_assert(CB3<MB3>(), "");
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64
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65
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66 template<typename T1, typename T2>
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67 struct S;
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68
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69 template<CA1 T1, CB1 T2>
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70 struct S<T1, T2> // Specialization #1
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71 {
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72 static constexpr int value = 1;
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73 };
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74
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75 template<CA1 T1, CB2 T2>
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76 requires !CA2<T1>()
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77 struct S<T1, T2> // Specialization #2
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78 {
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79 static constexpr int value = 2;
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80 };
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81
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82 template<CA2 T1, CB3 T2>
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83 requires !CA3<T1>()
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84 struct S<T1, T2> // Specialization #3
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85 {
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86 static constexpr int value = 3;
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87 };
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88
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89 S<MA1,MB1> s11;
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90 S<MA1,MB2> s12;
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91 S<MA1,MB3> s13;
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92 S<MA2,MB1> s21;
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93 S<MA2,MB2> s22;
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94 S<MA2,MB3> s23;
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95 S<MA3,MB1> s31;
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96 S<MA3,MB2> s32;
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97 S<MA3,MB3> s33;
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98
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99 static_assert(S<MA1,MB1>::value == 1, "");
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100 static_assert(S<MA1,MB2>::value == 2, "");
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101 static_assert(S<MA1,MB3>::value == 2, "");
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102 static_assert(S<MA2,MB1>::value == 1, "");
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103 static_assert(S<MA2,MB2>::value == 1, "");
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104 static_assert(S<MA2,MB3>::value == 3, "");
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105 static_assert(S<MA3,MB1>::value == 1, "");
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106 static_assert(S<MA3,MB2>::value == 1, "");
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107 static_assert(S<MA3,MB3>::value == 1, "");
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