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111
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1 // { dg-options "-std=c++17 -fconcepts" }
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2
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3 template<typename T>
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4 concept bool C1()
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5 {
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6 return requires (T t) { t.f(); };
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7 }
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8
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9 template<typename T>
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10 concept bool C2()
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11 {
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12 return requires { typename T::type; };
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13 }
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14
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15 template<typename T>
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16 requires C1<T>()
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17 void f1(T x) { }
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18
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19 template<typename T>
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20 requires C2<T>()
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21 void f2(T x) { }
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22
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23 // Note that these declarations are private and therefore
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24 // cannot satisify the constraints.
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25 class S
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26 {
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27 using type = int;
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28 void f() { }
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29 } s;
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30
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31 int main()
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32 {
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33 f1(s); // { dg-error "cannot call" }
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34 f2(s); // { dg-error "" }
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35
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36 // When used in non-SFINAE contexts, make sure that we fail
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37 // the constraint check before emitting the access check
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38 // failures. The context is being presented constistently
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39 // in both cases.
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40 static_assert(C1<S>(), ""); // { dg-error "failed" }
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41 static_assert(C2<S>(), ""); // { dg-error "" }
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42 }
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