| // { dg-do compile { target c++20 } } |
| |
| // Test deduction requirements. |
| |
| // req12.C |
| |
| template <typename T, typename U> |
| concept SameAs = __is_same_as(T, U); |
| |
| template <typename T> |
| concept C1 = requires(T t) { // { dg-message "in requirements" } |
| { t } -> SameAs<T>; // NOTE: t deduced as decltype((t)) |
| // { dg-message "does not satisfy" "" { target *-*-* } .-1 } |
| }; |
| |
| template <typename T> |
| requires C1<T> |
| constexpr bool f1() { return true; } |
| |
| static_assert(f1<char>()); // { dg-error "" } |
| static_assert(f1<int>()); // { dg-error "" } |
| static_assert(f1<double>()); // { dg-error "" } |
| |
| |
| template <typename T> |
| concept C2 = requires(T t) { |
| { t } -> SameAs<T&>; // NOTE: t deduced as decltype((t)) |
| }; |
| |
| template <typename T> |
| requires C2<T> |
| constexpr bool f2() { return true; } |
| |
| static_assert(f2<int>()); // OK |
