@@ -60,6 +60,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp, typename = void>
struct __poison_hash
{
+ static constexpr bool __enable_hash_call = false;
private:
// Private rather than deleted to be non-trivially-copyable.
__poison_hash(__poison_hash&&);
@@ -69,6 +70,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
template<typename _Tp>
struct __poison_hash<_Tp, __void_t<decltype(hash<_Tp>()(declval<_Tp>()))>>
{
+ static constexpr bool __enable_hash_call = true;
};
// Helper struct for SFINAE-poisoning non-enum types.
@@ -951,12 +951,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{ return optional<_Tp> { in_place, __il, std::forward<_Args>(__args)... }; }
// Hash.
- template<typename _Tp>
- struct hash<optional<_Tp>> : private __poison_hash<remove_const_t<_Tp>>
- {
- using result_type = size_t;
- using argument_type = optional<_Tp>;
+ template<typename _Tp, bool
+ = __poison_hash<remove_const_t<_Tp>>::__enable_hash_call>
+ struct __optional_hash_call_base
+ {
size_t
operator()(const optional<_Tp>& __t) const
noexcept(noexcept(hash<_Tp> {}(*__t)))
@@ -968,6 +967,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
+ template<typename _Tp>
+ struct __optional_hash_call_base<_Tp, false> {};
+
+ template<typename _Tp>
+ struct hash<optional<_Tp>>
+ : private __poison_hash<remove_const_t<_Tp>>,
+ public __optional_hash_call_base<_Tp>
+ {
+ using result_type = size_t;
+ using argument_type = optional<_Tp>;
+ };
+
/// @}
_GLIBCXX_END_NAMESPACE_VERSION
@@ -1273,14 +1273,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
std::forward<_Variants>(__variants)...);
}
- template<typename... _Types>
- struct hash<variant<_Types...>>
- : private __detail::__variant::_Variant_hash_base<
- variant<_Types...>, std::index_sequence_for<_Types...>>
+ template<bool, typename... _Types>
+ struct __variant_hash_call_base_impl
{
- using result_type = size_t;
- using argument_type = variant<_Types...>;
-
size_t
operator()(const variant<_Types...>& __t) const
noexcept((is_nothrow_callable_v<hash<decay_t<_Types>>(_Types)> && ...))
@@ -1297,6 +1292,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
}
};
+ template<typename... _Types>
+ struct __variant_hash_call_base_impl<false, _Types...> {};
+
+ template<typename... _Types>
+ using __variant_hash_call_base =
+ __variant_hash_call_base_impl<(__poison_hash<remove_const_t<_Types>>::
+ __enable_hash_call &&...), _Types...>;
+
+ template<typename... _Types>
+ struct hash<variant<_Types...>>
+ : private __detail::__variant::_Variant_hash_base<
+ variant<_Types...>, std::index_sequence_for<_Types...>>,
+ public __variant_hash_call_base<_Types...>
+ {
+ using result_type = size_t;
+ using argument_type = variant<_Types...>;
+ };
+
template<>
struct hash<monostate>
{
@@ -29,6 +29,12 @@ template<class T>
auto f(...) -> decltype(std::false_type());
static_assert(!decltype(f<S>(0))::value, "");
+static_assert(!std::is_callable<
+ std::hash<std::optional<S>>&
+ (std::optional<S> const&)>::value, "");
+static_assert(std::is_callable<
+ std::hash<std::optional<int>>&
+ (std::optional<int> const&)>::value, "");
int main()
{
@@ -33,6 +33,17 @@ static_assert(!decltype(f<std::variant<S>>(0))::value, "");
static_assert(!decltype(f<std::variant<S, S>>(0))::value, "");
static_assert(decltype(f<std::variant<int>>(0))::value, "");
static_assert(decltype(f<std::variant<int, int>>(0))::value, "");
+static_assert(!std::is_callable<
+ std::hash<std::variant<S>>&(std::variant<S> const&)>::value, "");
+static_assert(!std::is_callable<
+ std::hash<std::variant<S, int>>&
+ (std::variant<S, int> const&)>::value, "");
+static_assert(std::is_callable<
+ std::hash<std::variant<int>>&
+ (std::variant<int> const&)>::value, "");
+static_assert(std::is_callable<
+ std::hash<std::variant<int, int>>&
+ (std::variant<int, int> const&)>::value, "");
int main()
{