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// { dg-do compile { target c++20 } }
// { dg-additional-options "-fconcepts -fconcepts-diagnostics-depth=2" }
// req9.C
template<class T, class U> concept same_as = __is_same(T, U);
template<typename T>
struct S1 { };
template<typename T>
concept C = requires(T x) { { x.fn() } -> same_as<S1<T>>; };
template<typename U>
requires C<U>
void fn(U x)
{
x.fn();
}
struct S2
{
auto fn() const { return S1<S2>(); }
};
int driver_1()
{
fn(S2{});
return 0;
}
// req10.C
// Test implicit conversion requirements
template<typename T, typename U>
concept ConvertibleTo = requires(T& t) { {t} -> U&; }; // { dg-error "inaccessible|return-type-requirement" }
struct B { };
class D : /*private*/ B { };
void driver_2()
{
static_assert(ConvertibleTo<D, B>()); // { dg-error "cannot call" }
static_assert(ConvertibleTo<D, B>); // { dg-error "static assertion failed" }
}
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