On Wed, 24 Jan 2024, Patrick Palka wrote:
> On Wed, 24 Jan 2024, Patrick Palka wrote:
>
> > On Wed, 24 Jan 2024, Jonathan Wakely wrote:
> >
> > > On Wed, 24 Jan 2024 at 15:24, Patrick Palka <ppa...@redhat.com> wrote:
> > > >
> > > > On Wed, 24 Jan 2024, Jonathan Wakely wrote:
> > > >
> > > > > On Tue, 23 Jan 2024 at 23:54, Patrick Palka wrote:
> > > > > > diff --git a/libstdc++-v3/include/bits/stl_pair.h
> > > > > > b/libstdc++-v3/include/bits/stl_pair.h
> > > > > > index b81b479ad43..a9b20fbe7ca 100644
> > > > > > --- a/libstdc++-v3/include/bits/stl_pair.h
> > > > > > +++ b/libstdc++-v3/include/bits/stl_pair.h
> > > > > > @@ -85,12 +85,70 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > /// @cond undocumented
> > > > > >
> > > > > > // Forward declarations.
> > > > > > + template<typename, typename>
> > > > > > + struct pair;
> > > > >
> > > > > We have a compiler bug where a forward declaration without template
> > > > > parameter names causes bad diagnostics later. The compiler seems to
> > > > > try to use the parameter names from the first decl it sees, so we end
> > > > > up with things like <template-argument-1-1> even when there's a name
> > > > > available at the site of the actual error. So I think we should name
> > > > > these _T1 and _T2 here.
> > > >
> > > > Will fix.
> > > >
> > > > >
> > > > > > +
> > > > > > template<typename...>
> > > > > > class tuple;
> > > > > >
> > > > > > + // Declarations of std::array and its std::get overloads, so that
> > > > > > + // std::tuple_cat can use them if <tuple> is included before
> > > > > > <array>.
> > > > > > + // We also declare the other std::get overloads here so that
> > > > > > they're
> > > > > > + // visible to the P2165R4 tuple-like constructors of pair and
> > > > > > tuple.
> > > > > > + template<typename _Tp, size_t _Nm>
> > > > > > + struct array;
> > > > > > +
> > > > > > template<size_t...>
> > > > > > struct _Index_tuple;
> > > > > >
> > > > > > + template<size_t _Int, class _Tp1, class _Tp2>
> > > > > > + constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
> > > > > > + get(pair<_Tp1, _Tp2>& __in) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, class _Tp1, class _Tp2>
> > > > > > + constexpr typename tuple_element<_Int, pair<_Tp1,
> > > > > > _Tp2>>::type&&
> > > > > > + get(pair<_Tp1, _Tp2>&& __in) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, class _Tp1, class _Tp2>
> > > > > > + constexpr const typename tuple_element<_Int, pair<_Tp1,
> > > > > > _Tp2>>::type&
> > > > > > + get(const pair<_Tp1, _Tp2>& __in) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, class _Tp1, class _Tp2>
> > > > > > + constexpr const typename tuple_element<_Int, pair<_Tp1,
> > > > > > _Tp2>>::type&&
> > > > > > + get(const pair<_Tp1, _Tp2>&& __in) noexcept;
> > > > > > +
> > > > > > + template<size_t __i, typename... _Elements>
> > > > > > + constexpr __tuple_element_t<__i, tuple<_Elements...>>&
> > > > > > + get(tuple<_Elements...>& __t) noexcept;
> > > > > > +
> > > > > > + template<size_t __i, typename... _Elements>
> > > > > > + constexpr const __tuple_element_t<__i, tuple<_Elements...>>&
> > > > > > + get(const tuple<_Elements...>& __t) noexcept;
> > > > > > +
> > > > > > + template<size_t __i, typename... _Elements>
> > > > > > + constexpr __tuple_element_t<__i, tuple<_Elements...>>&&
> > > > > > + get(tuple<_Elements...>&& __t) noexcept;
> > > > > > +
> > > > > > + template<size_t __i, typename... _Elements>
> > > > > > + constexpr const __tuple_element_t<__i, tuple<_Elements...>>&&
> > > > > > + get(const tuple<_Elements...>&& __t) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, typename _Tp, size_t _Nm>
> > > > > > + constexpr _Tp&
> > > > > > + get(array<_Tp, _Nm>&) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, typename _Tp, size_t _Nm>
> > > > > > + constexpr _Tp&&
> > > > > > + get(array<_Tp, _Nm>&&) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, typename _Tp, size_t _Nm>
> > > > > > + constexpr const _Tp&
> > > > > > + get(const array<_Tp, _Nm>&) noexcept;
> > > > > > +
> > > > > > + template<size_t _Int, typename _Tp, size_t _Nm>
> > > > > > + constexpr const _Tp&&
> > > > > > + get(const array<_Tp, _Nm>&&) noexcept;
> > > > > > +
> > > > > > #if ! __cpp_lib_concepts
> > > > > > // Concept utility functions, reused in conditionally-explicit
> > > > > > // constructors.
> > > > > > @@ -159,6 +217,46 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > #endif // lib concepts
> > > > > > #endif // C++11
> > > > > >
> > > > > > +#if __glibcxx_tuple_like // >= C++23
> > > > > > + template<typename _Tp>
> > > > > > + inline constexpr bool __is_tuple_v = false;
> > > > > > +
> > > > > > + template<typename... _Ts>
> > > > > > + inline constexpr bool __is_tuple_v<tuple<_Ts...>> = true;
> > > > > > +
> > > > > > + // TODO: Reuse __is_tuple_like from <type_traits>?
> > > > > > + template<typename _Tp>
> > > > > > + inline constexpr bool __is_tuple_like_v = false;
> > > > > > +
> > > > > > + template<typename... _Elements>
> > > > > > + inline constexpr bool __is_tuple_like_v<tuple<_Elements...>> =
> > > > > > true;
> > > > > > +
> > > > > > + template<typename _T1, typename _T2>
> > > > > > + inline constexpr bool __is_tuple_like_v<pair<_T1, _T2>> = true;
> > > > > > +
> > > > > > + template<typename _Tp, size_t _Nm>
> > > > > > + inline constexpr bool __is_tuple_like_v<array<_Tp, _Nm>> =
> > > > > > true;
> > > > > > +
> > > > > > + // __is_tuple_like_v<subrange> is defined in
> > > > > > <bits/ranges_util.h>.
> > > > > > +
> > > > > > + template<typename _Tp>
> > > > > > + concept __tuple_like = __is_tuple_like_v<remove_cvref_t<_Tp>>;
> > > > > > +
> > > > > > + template<typename _Tp>
> > > > > > + concept __pair_like = __tuple_like<_Tp> &&
> > > > > > tuple_size_v<remove_cvref_t<_Tp>> == 2;
> > > > > > +
> > > > > > + template<typename _Tp, typename _Tuple>
> > > > > > + concept __eligible_tuple_like
> > > > > > + = __detail::__different_from<_Tp, _Tuple> &&
> > > > > > __tuple_like<_Tp>
> > > > > > + && (tuple_size_v<remove_cvref_t<_Tp>> ==
> > > > > > tuple_size_v<_Tuple>)
> > > > > > + && !ranges::__detail::__is_subrange<remove_cvref_t<_Tp>>;
> > > > > > +
> > > > > > + template<typename _Tp, typename _Pair>
> > > > > > + concept __eligible_pair_like
> > > > > > + = __detail::__different_from<_Tp, _Pair> && __pair_like<_Tp>
> > > > > > + && !ranges::__detail::__is_subrange<remove_cvref_t<_Tp>>;
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > template<typename _U1, typename _U2> class __pair_base
> > > > > > {
> > > > > > #if __cplusplus >= 201103L && ! __cpp_lib_concepts
> > > > > > @@ -295,6 +393,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > return false;
> > > > > > #endif
> > > > > > }
> > > > > > +
> > > > > > +#if __glibcxx_tuple_like // >= C++23
> > > > > > + template<typename _UPair>
> > > > > > + static constexpr bool
> > > > > > + _S_constructible_from_pair_like()
> > > > > > + {
> > > > > > + return
> > > > > > _S_constructible<decltype(std::get<0>(std::declval<_UPair>())),
> > > > > > +
> > > > > > decltype(std::get<1>(std::declval<_UPair>()))>();
> > > > > > + }
> > > > > > +
> > > > > > + template<typename _UPair>
> > > > > > + static constexpr bool
> > > > > > + _S_convertible_from_pair_like()
> > > > > > + {
> > > > > > + return
> > > > > > _S_convertible<decltype(std::get<0>(std::declval<_UPair>())),
> > > > > > +
> > > > > > decltype(std::get<1>(std::declval<_UPair>()))>();
> > > > > > + }
> > > > > > +#endif // C++23
> > > > > > /// @endcond
> > > > > >
> > > > > > public:
> > > > > > @@ -393,6 +509,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > pair(const pair<_U1, _U2>&&) = delete;
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __glibcxx_tuple_like // >= C++23
> > > > > > + template<__eligible_pair_like<pair> _UPair>
> > > > > > + requires (_S_constructible_from_pair_like<_UPair>())
> > > > > > + constexpr explicit(!_S_convertible_from_pair_like<_UPair>())
> > > > > > + pair(_UPair&& __p)
> > > > > > + : first(std::get<0>(std::forward<_UPair>(__p))),
> > > > > > + second(std::get<1>(std::forward<_UPair>(__p)))
> > > > > > + { }
> > > > > > +#endif // C++23
> > > > >
> > > > > I think this needs to be constrained with !_S_dangles<...>() and we
> > > > > need a deleted overload with the same constraints, except for
> > > > > _S_dangles being true.
> > > > >
> > > > > And that should be covered by a test.
> > > >
> > > > Oops, will fix. Should the deleted overloads carry over the
> > > > conditionally explicit specifier? I noticed pair's deleted overloads
> > > > do, but tuple's overloads don't.
> > >
> > > Huh, oops. Does an explicit ctor participate in overload resolution
> > > and then get checked if it's usable, or is it remove from overload
> > > resolution earlier?
> > > It looks like I decided the answer was the latter for pair and the
> > > former for tuple.
> >
> > AFAICT if we know the explicitness of the ctor early (either because the
> > ctor is a non-template or it has a non-dependent explicit-spec), then we
> > remove it from the overload set early, in which case it'd be useful to
> > give the deleted ctor the right explicit-spec to avoid unecessary
> > constraint checking etc.
> >
> > Otherwise, for ctor templates with a dependent explicit-spec such as
> > these tuple/pair ones, we must wait until after deduction to check
> > explicitness which means constraints are checked first. And by then
> > we already know that __dangles is true, so we presumably want overload
> > resolution to fail regardless. Whether that's due to selecting a
> > (viable) deleted non-explicit ctor (if we omit the explicit-spec) or due
> > to there being no viable non-explicit ctor (if we carry over the
> > explicit-spec) shouldn't make a difference, I think?
> >
> > So it seems unnecessary to give these deleted overloads an
> > explicit-spec; it wouldn't be considered unless overload resolution
> > is destined to fail anyway.
> >
> > I'm not totally confident about this assessment though so I'll
> > just carry over the explicit-spec for now.
>
> I ended up hedging my bets and including the explicit-spec in the
> deleted ctors of pair and omitting it in those of tuple, so that
> we continue to be locally consistent.
>
> >
> > >
> > > >
> > > > >
> > > > >
> > > > >
> > > > > > diff --git a/libstdc++-v3/include/std/tuple
> > > > > > b/libstdc++-v3/include/std/tuple
> > > > > > index be92f1eb973..182f3cc5e6a 100644
> > > > > > --- a/libstdc++-v3/include/std/tuple
> > > > > > +++ b/libstdc++-v3/include/std/tuple
> > > > > > @@ -50,6 +50,7 @@
> > > > > > #define __glibcxx_want_apply
> > > > > > #define __glibcxx_want_make_from_tuple
> > > > > > #define __glibcxx_want_ranges_zip
> > > > > > +#define __glibcxx_want_tuple_like
> > > > > > #include <bits/version.h>
> > > > > >
> > > > > > namespace std _GLIBCXX_VISIBILITY(default)
> > > > > > @@ -246,6 +247,21 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > _Head _M_head_impl;
> > > > > > };
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + struct __tuple_like_tag_t { explicit __tuple_like_tag_t() =
> > > > > > default; };
> > > > > > +
> > > > > > + // Forward declared for use by the operator<=> overload for
> > > > > > tuple-like types.
> > > > > > + template<typename _Cat, typename _Tp, typename _Up>
> > > > > > + constexpr _Cat
> > > > > > + __tuple_cmp(const _Tp&, const _Up&, index_sequence<>);
> > > > > > +
> > > > > > + template<typename _Cat, typename _Tp, typename _Up,
> > > > > > + size_t _Idx0, size_t... _Idxs>
> > > > > > + constexpr _Cat
> > > > > > + __tuple_cmp(const _Tp& __t, const _Up& __u,
> > > > > > + index_sequence<_Idx0, _Idxs...>);
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > /**
> > > > > > * Contains the actual implementation of the @c tuple template,
> > > > > > stored
> > > > > > * as a recursive inheritance hierarchy from the first element
> > > > > > (most
> > > > > > @@ -342,6 +358,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > { }
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _UTuple, size_t... _Is>
> > > > > > + constexpr
> > > > > > + _Tuple_impl(__tuple_like_tag_t, _UTuple&& __u,
> > > > > > index_sequence<_Is...>)
> > > > > > + : _Tuple_impl(std::get<_Is>(std::forward<_UTuple>(__u))...)
> > > > > > + { }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > template<typename _Alloc>
> > > > > > _GLIBCXX20_CONSTEXPR
> > > > > > _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
> > > > > > @@ -428,6 +452,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > { }
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _Alloc, typename _UTuple, size_t... _Is>
> > > > > > + constexpr
> > > > > > + _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag,
> > > > > > const _Alloc& __a,
> > > > > > + _UTuple&& __u, index_sequence<_Is...>)
> > > > > > + : _Tuple_impl(__tag, __a,
> > > > > > std::get<_Is>(std::forward<_UTuple>(__u))...)
> > > > > > + { }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > template<typename... _UElements>
> > > > > > _GLIBCXX20_CONSTEXPR
> > > > > > void
> > > > > > @@ -470,6 +503,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > }
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _UTuple>
> > > > > > + constexpr void
> > > > > > + _M_assign(__tuple_like_tag_t __tag, _UTuple&& __u)
> > > > > > + {
> > > > > > + _M_head(*this) =
> > > > > > std::get<_Idx>(std::forward<_UTuple>(__u));
> > > > > > + _M_tail(*this)._M_assign(__tag,
> > > > > > std::forward<_UTuple>(__u));
> > > > > > + }
> > > > > > +
> > > > > > + template<typename _UTuple>
> > > > > > + constexpr void
> > > > > > + _M_assign(__tuple_like_tag_t __tag, _UTuple&& __u) const
> > > > > > + {
> > > > > > + _M_head(*this) =
> > > > > > std::get<_Idx>(std::forward<_UTuple>(__u));
> > > > > > + _M_tail(*this)._M_assign(__tag,
> > > > > > std::forward<_UTuple>(__u));
> > > > > > + }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > protected:
> > > > > > _GLIBCXX20_CONSTEXPR
> > > > > > void
> > > > > > @@ -563,6 +614,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > { }
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _UTuple>
> > > > > > + constexpr
> > > > > > + _Tuple_impl(__tuple_like_tag_t, _UTuple&& __u,
> > > > > > index_sequence<0>)
> > > > > > + : _Tuple_impl(std::get<0>(std::forward<_UTuple>(__u)))
> > > > > > + { }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > template<typename _Alloc>
> > > > > > _GLIBCXX20_CONSTEXPR
> > > > > > _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
> > > > > > @@ -633,6 +692,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > { }
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _Alloc, typename _UTuple>
> > > > > > + constexpr
> > > > > > + _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag,
> > > > > > const _Alloc& __a,
> > > > > > + _UTuple&& __u, index_sequence<0>)
> > > > > > + : _Tuple_impl(__tag, __a,
> > > > > > std::get<0>(std::forward<_UTuple>(__u)))
> > > > > > + { }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > template<typename _UHead>
> > > > > > _GLIBCXX20_CONSTEXPR
> > > > > > void
> > > > > > @@ -667,6 +735,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > }
> > > > > > #endif // C++23
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _UTuple>
> > > > > > + constexpr void
> > > > > > + _M_assign(__tuple_like_tag_t, _UTuple&& __u)
> > > > > > + { _M_head(*this) =
> > > > > > std::get<_Idx>(std::forward<_UTuple>(__u)); }
> > > > > > +
> > > > > > + template<typename _UTuple>
> > > > > > + constexpr void
> > > > > > + _M_assign(__tuple_like_tag_t, _UTuple&& __u) const
> > > > > > + { _M_head(*this) =
> > > > > > std::get<_Idx>(std::forward<_UTuple>(__u)); }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > protected:
> > > > > > _GLIBCXX20_CONSTEXPR
> > > > > > void
> > > > > > @@ -846,6 +926,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > #endif
> > > > > > }
> > > > > >
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _UTuple>
> > > > > > + static consteval bool
> > > > > > + __constructible_from_tuple_like()
> > > > > > + {
> > > > > > + return []<size_t... _Is>(index_sequence<_Is...>) {
> > > > > > + return
> > > > > > __constructible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> > > > > > + }(make_index_sequence<sizeof...(_Elements)>{});
> > > > > > + }
> > > > > > +
> > > > > > + template<typename _UTuple>
> > > > > > + static consteval bool
> > > > > > + __convertible_from_tuple_like()
> > > > > > + {
> > > > > > + return []<size_t... _Is>(index_sequence<_Is...>) {
> > > > > > + return
> > > > > > __convertible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> > > > > > + }(make_index_sequence<sizeof...(_Elements)>{});
> > > > >
> > > > > These new functions can use index_sequence_for<_Elements...>{} here,
> > > > > so you don't need the sizeof....
> > > > > That applies several times below as well.
> > > > >
> > > > > I think it's semantically identical, just a little shorter. I don't
> > > > > know if there's any compilation speed benefit either way. Maybe
> > > > > sizeof...(_Elements) is cheaper than expanding the pack into the
> > > > > index_sequence_for alias template?
>
> It probably a little cheaper to use make_index_sequence directly, but I
> just didn't know about index_sequence_for :) Consider that changed.
>
> > > > >
> > > > >
> > > > > > + }
> > > > > > +#endif // C++23
> > > > > > +
> > > > > > public:
> > > > > > constexpr
> > > > > >
> > > > > > explicit(!(__is_implicitly_default_constructible_v<_Elements> &&
> > > > > > ...))
> > > > > > @@ -1016,10 +1116,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > tuple(const pair<_U1, _U2>&&) = delete;
> > > > > > #endif // C++23
> > > > > >
> > > > > > -#if 0 && __cpp_lib_tuple_like // >= C++23
> > > > > > - template<__tuple_like _UTuple>
> > > > > > - constexpr explicit(...)
> > > > > > - tuple(_UTuple&& __u);
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<__eligible_tuple_like<tuple> _UTuple>
> > > > > > + requires (__constructible_from_tuple_like<_UTuple>())
> > > > > > + && (!__use_other_ctor<_UTuple>())
> > > > > > + constexpr
> > > > > > explicit(!__convertible_from_tuple_like<_UTuple>())
> > > > > > + tuple(_UTuple&& __u)
> > > > > > + : _Inherited(__tuple_like_tag_t{},
> > > > > > + std::forward<_UTuple>(__u),
> > > > > > + make_index_sequence<sizeof...(_Elements)>{})
> > > > > > + { }
> > > > > > #endif // C++23
> > > > > >
> > > > > > // Allocator-extended constructors.
> > > > > > @@ -1202,10 +1308,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> > > > > > tuple(allocator_arg_t, const _Alloc&, const pair<_U1,
> > > > > > _U2>&&) = delete;
> > > > > > #endif // C++23
> > > > > >
> > > > > > -#if 0 && __cpp_lib_tuple_like // >= C++23
> > > > > > - template<typename _Alloc, __tuple_like _UTuple>
> > > > > > - constexpr explicit(...)
> > > > > > - tuple(allocator_arg_t __tag, const _Alloc& __a, _UTuple&&
> > > > > > __u);
> > > > > > +#if __cpp_lib_tuple_like // >= C++23
> > > > > > + template<typename _Alloc, __eligible_tuple_like<tuple>
> > > > > > _UTuple>
> > > > > > + requires (__constructible_from_tuple_like<_UTuple>())
> > > > > > + && (!__use_other_ctor<_UTuple>())
> > > > > > + constexpr
> > > > > > explicit(!__convertible_from_tuple_like<_UTuple>())
> > > > > > + tuple(allocator_arg_t __tag, const _Alloc& __a, _UTuple&&
> > > > > > __u)
> > > > > > + : _Inherited(__tuple_like_tag_t{},
> > > > > > + __tag, __a, std::forward<_UTuple>(__u),
> > > > > > + make_index_sequence<sizeof...(_Elements)>{})
> > > > > > + { }
> > > > > > #endif // C++23
> > > > >
> > > > > For some reason these two new constructors aren't deleted if they
> > > > > create dangling refs. I don't know why.
> > > >
> > > > Hmm, seems like an oversight. Shall we proactively implement them?
> > >
> > > Yes, I think so. I can't see why we would want to permit a dangling
> > > reference there.
> > >
> > > e.g.
> > > std::array<long, 1> a{};
> > > std::tuple<const int&> t(a);
> >
> > Sounds good.
>
> In v2:
>
> * Named the template parameters of the forward declaration of pair.
> * Added dangling checks for the new tuple and pair constructors
> and corresponding tests.
> * Replaced make_index_sequence with index_sequence_for where applicable.
Ping.
>
> -- >8 --
>
> Subject: [PATCH 2/2] libstdc++: Implement P2165R4 changes to
> std::pair/tuple/etc
>
> libstdc++-v3/ChangeLog:
>
> * include/bits/ranges_util.h (__detail::__pair_like): Don't
> define in C++23 mode.
> (__detail::__pair_like_convertible_from): Adjust as per P2165R4.
> (__detail::__is_subrange<subrange>): Moved from <ranges>.
> (__detail::__is_tuple_like_v<subrange>): Likewise.
> * include/bits/stl_iterator.h: Include <bits/utility.h> for
> C++23.
> (__different_from): Move to <concepts>.
> (__iter_key_t): Adjust for C++23 as per P2165R4.
> (__iter_val_t): Likewise.
> * include/bits/stl_pair.h (pair, array): Forward declare.
> (get): Forward declare all overloads relevant to P2165R4
> tuple-like constructors.
> (__is_tuple_v): Define for C++23.
> (__is_tuple_like_v): Define for C++23.
> (__tuple_like): Define for C++23 as per P2165R4.
> (__pair_like): Define for C++23 as per P2165R4.
> (__eligibile_tuple_like): Define for C++23.
> (__eligibile_pair_like): Define for C++23.
> (pair::_S_constructible_from_pair_like): Define for C++23.
> (pair::_S_convertible_from_pair_like): Define for C++23.
> (pair::_S_dangles_from_pair_like): Define for C++23.
> (pair::pair): Define overloads taking a tuple-like type for
> C++23 as per P2165R4.
> (pair::_S_assignable_from_tuple_like): Define for C++23.
> (pair::_S_const_assignable_from_tuple_like): Define for C++23.
> (pair::operator=): Define overloads taking a tuple-like type for
> C++23 as per P2165R4.
> * include/bits/utility.h (ranges::__detail::__is_subrange):
> Moved from <ranges>.
> * include/bits/version.def (tuple_like): Define for C++23.
> * include/bits/version.h: Regenerate.
> * include/std/concepts (__different_from): Moved from
> <bits/stl_iterator.h>.
> (ranges::__swap::__adl_swap): Clarify which __detail namespace.
> * include/std/map (__cpp_lib_tuple_like): Define C++23.
> * include/std/ranges (__detail::__is_subrange): Moved to
> <bits/utility.h>.
> (__detail::__is_subrange<subrange>): Moved to <bits/ranges_util.h>
> (__detail::__has_tuple_element): Adjust for C++23 as per P2165R4.
> (__detail::__tuple_or_pair): Remove as per P2165R4. Replace all
> uses with plain tuple as per P2165R4.
> * include/std/tuple (__cpp_lib_tuple_like): Define for C++23.
> (__tuple_like_tag_t): Define for C++23.
> (__tuple_cmp): Forward declare for C++23.
> (_Tuple_impl::_Tuple_impl): Define overloads taking
> __tuple_like_tag_t and a tuple-like type for C++23.
> (_Tuple_impl::_M_assign): Likewise.
> (tuple::__constructible_from_tuple_like): Define for C++23.
> (tuple::__convertible_from_tuple_like): Define for C++23.
> (tuple::__dangles_from_tuple_like): Define for C++23.
> (tuple::tuple): Define overloads taking a tuple-like type for
> C++23 as per P2165R4.
> (tuple::__assignable_from_tuple_like): Define for C++23.
> (tuple::__const_assignable_from_tuple_like): Define for C++23.
> (tuple::operator=): Define overloads taking a tuple-like type
> for C++23 as per P2165R4.
> (tuple::__tuple_like_common_comparison_category): Define for C++23.
> (tuple::operator<=>): Define overload taking a tuple-like type
> for C++23 as per P2165R4.
> (array, get): Forward declarations moved to <bits/stl_pair.h>.
> (tuple_cat): Constrain with __tuple_like for C++23 as per P2165R4.
> (apply): Likewise.
> (make_from_tuple): Likewise.
> (__tuple_like_common_reference): Define for C++23.
> (basic_common_reference): Adjust as per P2165R4.
> (__tuple_like_common_type): Define for C++23.
> (common_type): Adjust as per P2165R4.
> * include/std/unordered_map (__cpp_lib_tuple_like): Define for
> C++23.
> * include/std/utility (__cpp_lib_tuple_like): Define for C++23.
> * testsuite/std/ranges/zip/1.cc (test01): Adjust to handle pair
> and 2-tuple interchangeably.
> * testsuite/20_util/pair/p2165r4.cc: New test.
> * testsuite/20_util/tuple/p2165r4.cc: New test.
> ---
> libstdc++-v3/include/bits/ranges_util.h | 17 +-
> libstdc++-v3/include/bits/stl_iterator.h | 16 +-
> libstdc++-v3/include/bits/stl_pair.h | 182 ++++++++++
> libstdc++-v3/include/bits/utility.h | 8 +
> libstdc++-v3/include/bits/version.def | 8 +
> libstdc++-v3/include/bits/version.h | 11 +
> libstdc++-v3/include/std/concepts | 11 +-
> libstdc++-v3/include/std/map | 1 +
> libstdc++-v3/include/std/ranges | 48 +--
> libstdc++-v3/include/std/tuple | 323 ++++++++++++++---
> libstdc++-v3/include/std/unordered_map | 1 +
> libstdc++-v3/include/std/utility | 1 +
> .../testsuite/20_util/pair/p2165r4.cc | 173 +++++++++
> .../testsuite/20_util/tuple/p2165r4.cc | 335 ++++++++++++++++++
> libstdc++-v3/testsuite/std/ranges/zip/1.cc | 4 +-
> 15 files changed, 1056 insertions(+), 83 deletions(-)
> create mode 100644 libstdc++-v3/testsuite/20_util/pair/p2165r4.cc
> create mode 100644 libstdc++-v3/testsuite/20_util/tuple/p2165r4.cc
>
> diff --git a/libstdc++-v3/include/bits/ranges_util.h
> b/libstdc++-v3/include/bits/ranges_util.h
> index bb04c49f044..9b79c3a229d 100644
> --- a/libstdc++-v3/include/bits/ranges_util.h
> +++ b/libstdc++-v3/include/bits/ranges_util.h
> @@ -224,6 +224,10 @@ namespace ranges
> && !__uses_nonqualification_pointer_conversion<decay_t<_From>,
> decay_t<_To>>;
>
> +#if __glibcxx_tuple_like // >= C++23
> + // P2165R4 version of __pair_like is defined in <bits/stl_pair.h>.
> +#else
> + // C++20 version of __pair_like from P2321R2.
> template<typename _Tp>
> concept __pair_like
> = !is_reference_v<_Tp> && requires(_Tp __t)
> @@ -235,10 +239,11 @@ namespace ranges
> { get<0>(__t) } -> convertible_to<const tuple_element_t<0, _Tp>&>;
> { get<1>(__t) } -> convertible_to<const tuple_element_t<1, _Tp>&>;
> };
> +#endif
>
> template<typename _Tp, typename _Up, typename _Vp>
> concept __pair_like_convertible_from
> - = !range<_Tp> && __pair_like<_Tp>
> + = !range<_Tp> && !is_reference_v<_Vp> && __pair_like<_Tp>
> && constructible_from<_Tp, _Up, _Vp>
> && __convertible_to_non_slicing<_Up, tuple_element_t<0, _Tp>>
> && convertible_to<_Vp, tuple_element_t<1, _Tp>>;
> @@ -463,8 +468,18 @@ namespace ranges
> using borrowed_subrange_t = __conditional_t<borrowed_range<_Range>,
> subrange<iterator_t<_Range>>,
> dangling>;
> +
> + // __is_subrange is defined in <bits/utility.h>.
> + template<typename _Iter, typename _Sent, subrange_kind _Kind>
> + inline constexpr bool __detail::__is_subrange<subrange<_Iter, _Sent,
> _Kind>> = true;
> } // namespace ranges
>
> +#if __glibcxx_tuple_like // >= C++23
> + // __is_tuple_like_v is defined in <bits/stl_pair.h>.
> + template<typename _It, typename _Sent, ranges::subrange_kind _Kind>
> + inline constexpr bool __is_tuple_like_v<ranges::subrange<_It, _Sent,
> _Kind>> = true;
> +#endif
> +
> // The following ranges algorithms are used by <ranges>, and are defined here
> // so that <ranges> can avoid including all of <bits/ranges_algo.h>.
> namespace ranges
> diff --git a/libstdc++-v3/include/bits/stl_iterator.h
> b/libstdc++-v3/include/bits/stl_iterator.h
> index d71a793e10d..560a10a7abe 100644
> --- a/libstdc++-v3/include/bits/stl_iterator.h
> +++ b/libstdc++-v3/include/bits/stl_iterator.h
> @@ -78,6 +78,10 @@
> # include <bits/stl_construct.h>
> #endif
>
> +#if __glibcxx_tuple_like // >= C++23
> +# include <bits/utility.h> // for tuple_element_t
> +#endif
> +
> namespace std _GLIBCXX_VISIBILITY(default)
> {
> _GLIBCXX_BEGIN_NAMESPACE_VERSION
> @@ -95,10 +99,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> template<typename _Cat, typename _Limit, typename _Otherwise = _Cat>
> using __clamp_iter_cat
> = __conditional_t<derived_from<_Cat, _Limit>, _Limit, _Otherwise>;
> -
> - template<typename _Tp, typename _Up>
> - concept __different_from
> - = !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>;
> }
> #endif
>
> @@ -2983,11 +2983,19 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> // of associative containers.
> template<typename _InputIterator>
> using __iter_key_t = remove_const_t<
> +#if __glibcxx_tuple_like // >= C++23
> + tuple_element_t<0, typename
> iterator_traits<_InputIterator>::value_type>>;
> +#else
> typename iterator_traits<_InputIterator>::value_type::first_type>;
> +#endif
>
> template<typename _InputIterator>
> using __iter_val_t
> +#if __glibcxx_tuple_like // >= C++23
> + = tuple_element_t<1, typename
> iterator_traits<_InputIterator>::value_type>;
> +#else
> = typename iterator_traits<_InputIterator>::value_type::second_type;
> +#endif
>
> template<typename _T1, typename _T2>
> struct pair;
> diff --git a/libstdc++-v3/include/bits/stl_pair.h
> b/libstdc++-v3/include/bits/stl_pair.h
> index b81b479ad43..00ec53ebc33 100644
> --- a/libstdc++-v3/include/bits/stl_pair.h
> +++ b/libstdc++-v3/include/bits/stl_pair.h
> @@ -85,12 +85,70 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// @cond undocumented
>
> // Forward declarations.
> + template<typename _T1, typename _T2>
> + struct pair;
> +
> template<typename...>
> class tuple;
>
> + // Declarations of std::array and its std::get overloads, so that
> + // std::tuple_cat can use them if <tuple> is included before <array>.
> + // We also declare the other std::get overloads here so that they're
> + // visible to the P2165R4 tuple-like constructors of pair and tuple.
> + template<typename _Tp, size_t _Nm>
> + struct array;
> +
> template<size_t...>
> struct _Index_tuple;
>
> + template<size_t _Int, class _Tp1, class _Tp2>
> + constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
> + get(pair<_Tp1, _Tp2>& __in) noexcept;
> +
> + template<size_t _Int, class _Tp1, class _Tp2>
> + constexpr typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
> + get(pair<_Tp1, _Tp2>&& __in) noexcept;
> +
> + template<size_t _Int, class _Tp1, class _Tp2>
> + constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&
> + get(const pair<_Tp1, _Tp2>& __in) noexcept;
> +
> + template<size_t _Int, class _Tp1, class _Tp2>
> + constexpr const typename tuple_element<_Int, pair<_Tp1, _Tp2>>::type&&
> + get(const pair<_Tp1, _Tp2>&& __in) noexcept;
> +
> + template<size_t __i, typename... _Elements>
> + constexpr __tuple_element_t<__i, tuple<_Elements...>>&
> + get(tuple<_Elements...>& __t) noexcept;
> +
> + template<size_t __i, typename... _Elements>
> + constexpr const __tuple_element_t<__i, tuple<_Elements...>>&
> + get(const tuple<_Elements...>& __t) noexcept;
> +
> + template<size_t __i, typename... _Elements>
> + constexpr __tuple_element_t<__i, tuple<_Elements...>>&&
> + get(tuple<_Elements...>&& __t) noexcept;
> +
> + template<size_t __i, typename... _Elements>
> + constexpr const __tuple_element_t<__i, tuple<_Elements...>>&&
> + get(const tuple<_Elements...>&& __t) noexcept;
> +
> + template<size_t _Int, typename _Tp, size_t _Nm>
> + constexpr _Tp&
> + get(array<_Tp, _Nm>&) noexcept;
> +
> + template<size_t _Int, typename _Tp, size_t _Nm>
> + constexpr _Tp&&
> + get(array<_Tp, _Nm>&&) noexcept;
> +
> + template<size_t _Int, typename _Tp, size_t _Nm>
> + constexpr const _Tp&
> + get(const array<_Tp, _Nm>&) noexcept;
> +
> + template<size_t _Int, typename _Tp, size_t _Nm>
> + constexpr const _Tp&&
> + get(const array<_Tp, _Nm>&&) noexcept;
> +
> #if ! __cpp_lib_concepts
> // Concept utility functions, reused in conditionally-explicit
> // constructors.
> @@ -159,6 +217,46 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif // lib concepts
> #endif // C++11
>
> +#if __glibcxx_tuple_like // >= C++23
> + template<typename _Tp>
> + inline constexpr bool __is_tuple_v = false;
> +
> + template<typename... _Ts>
> + inline constexpr bool __is_tuple_v<tuple<_Ts...>> = true;
> +
> + // TODO: Reuse __is_tuple_like from <type_traits>?
> + template<typename _Tp>
> + inline constexpr bool __is_tuple_like_v = false;
> +
> + template<typename... _Elements>
> + inline constexpr bool __is_tuple_like_v<tuple<_Elements...>> = true;
> +
> + template<typename _T1, typename _T2>
> + inline constexpr bool __is_tuple_like_v<pair<_T1, _T2>> = true;
> +
> + template<typename _Tp, size_t _Nm>
> + inline constexpr bool __is_tuple_like_v<array<_Tp, _Nm>> = true;
> +
> + // __is_tuple_like_v<subrange> is defined in <bits/ranges_util.h>.
> +
> + template<typename _Tp>
> + concept __tuple_like = __is_tuple_like_v<remove_cvref_t<_Tp>>;
> +
> + template<typename _Tp>
> + concept __pair_like = __tuple_like<_Tp> &&
> tuple_size_v<remove_cvref_t<_Tp>> == 2;
> +
> + template<typename _Tp, typename _Tuple>
> + concept __eligible_tuple_like
> + = __detail::__different_from<_Tp, _Tuple> && __tuple_like<_Tp>
> + && (tuple_size_v<remove_cvref_t<_Tp>> == tuple_size_v<_Tuple>)
> + && !ranges::__detail::__is_subrange<remove_cvref_t<_Tp>>;
> +
> + template<typename _Tp, typename _Pair>
> + concept __eligible_pair_like
> + = __detail::__different_from<_Tp, _Pair> && __pair_like<_Tp>
> + && !ranges::__detail::__is_subrange<remove_cvref_t<_Tp>>;
> +#endif // C++23
> +
> template<typename _U1, typename _U2> class __pair_base
> {
> #if __cplusplus >= 201103L && ! __cpp_lib_concepts
> @@ -295,6 +393,32 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> return false;
> #endif
> }
> +
> +#if __glibcxx_tuple_like // >= C++23
> + template<typename _UPair>
> + static constexpr bool
> + _S_constructible_from_pair_like()
> + {
> + return _S_constructible<decltype(std::get<0>(std::declval<_UPair>())),
> +
> decltype(std::get<1>(std::declval<_UPair>()))>();
> + }
> +
> + template<typename _UPair>
> + static constexpr bool
> + _S_convertible_from_pair_like()
> + {
> + return _S_convertible<decltype(std::get<0>(std::declval<_UPair>())),
> +
> decltype(std::get<1>(std::declval<_UPair>()))>();
> + }
> +
> + template<typename _UPair>
> + static constexpr bool
> + _S_dangles_from_pair_like()
> + {
> + return _S_dangles<decltype(std::get<0>(std::declval<_UPair>())),
> + decltype(std::get<1>(std::declval<_UPair>()))>();
> + }
> +#endif // C++23
> /// @endcond
>
> public:
> @@ -393,6 +517,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> pair(const pair<_U1, _U2>&&) = delete;
> #endif // C++23
>
> +#if __glibcxx_tuple_like // >= C++23
> + template<__eligible_pair_like<pair> _UPair>
> + requires (_S_constructible_from_pair_like<_UPair>())
> + && (!_S_dangles_from_pair_like<_UPair>())
> + constexpr explicit(!_S_convertible_from_pair_like<_UPair>())
> + pair(_UPair&& __p)
> + : first(std::get<0>(std::forward<_UPair>(__p))),
> + second(std::get<1>(std::forward<_UPair>(__p)))
> + { }
> +
> + template<__eligible_pair_like<pair> _UPair>
> + requires (_S_constructible_from_pair_like<_UPair>())
> + && (_S_dangles_from_pair_like<_UPair>())
> + constexpr explicit(!_S_convertible_from_pair_like<_UPair>())
> + pair(_UPair&&) = delete;
> +#endif // C++23
> +
> private:
> /// @cond undocumented
> template<typename _U1, typename _U2>
> @@ -421,6 +562,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> return is_nothrow_assignable_v<_T2&, _U2>;
> return false;
> }
> +
> +#if __glibcxx_tuple_like // >= C++23
> + template<typename _UPair>
> + static constexpr bool
> + _S_assignable_from_tuple_like()
> + {
> + return _S_assignable<decltype(std::get<0>(std::declval<_UPair>())),
> + decltype(std::get<1>(std::declval<_UPair>()))>();
> + }
> +
> + template<typename _UPair>
> + static constexpr bool
> + _S_const_assignable_from_tuple_like()
> + {
> + return
> _S_const_assignable<decltype(std::get<0>(std::declval<_UPair>())),
> +
> decltype(std::get<1>(std::declval<_UPair>()))>();
> + }
> +#endif // C++23
> /// @endcond
>
> public:
> @@ -516,6 +675,29 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> return *this;
> }
> #endif // C++23
> +
> +#if __glibcxx_tuple_like // >= C++23
> + template<__eligible_pair_like<pair> _UPair>
> + requires (_S_assignable_from_tuple_like<_UPair>())
> + constexpr pair&
> + operator=(_UPair&& __p)
> + {
> + first = std::get<0>(std::forward<_UPair>(__p));
> + second = std::get<1>(std::forward<_UPair>(__p));
> + return *this;
> + }
> +
> + template<__eligible_pair_like<pair> _UPair>
> + requires (_S_const_assignable_from_tuple_like<_UPair>())
> + constexpr const pair&
> + operator=(_UPair&& __p) const
> + {
> + first = std::get<0>(std::forward<_UPair>(__p));
> + second = std::get<1>(std::forward<_UPair>(__p));
> + return *this;
> + }
> +#endif // C++23
> +
> #else // !__cpp_lib_concepts
> // C++11/14/17 implementation using enable_if, partially constexpr.
>
> diff --git a/libstdc++-v3/include/bits/utility.h
> b/libstdc++-v3/include/bits/utility.h
> index d8a5fb960fe..2a741bf7000 100644
> --- a/libstdc++-v3/include/bits/utility.h
> +++ b/libstdc++-v3/include/bits/utility.h
> @@ -266,6 +266,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif
> #endif
>
> +#if __glibcxx_ranges
> + namespace ranges::__detail
> + {
> + template<typename _Range>
> + inline constexpr bool __is_subrange = false;
> + } // namespace __detail
> +#endif
> +
> _GLIBCXX_END_NAMESPACE_VERSION
> } // namespace
>
> diff --git a/libstdc++-v3/include/bits/version.def
> b/libstdc++-v3/include/bits/version.def
> index 8fb8a2877ee..502961eb269 100644
> --- a/libstdc++-v3/include/bits/version.def
> +++ b/libstdc++-v3/include/bits/version.def
> @@ -1780,6 +1780,14 @@ ftms = {
> };
> };
>
> +ftms = {
> + name = tuple_like;
> + values = {
> + v = 202207;
> + cxxmin = 23;
> + };
> +};
> +
> // Standard test specifications.
> stds[97] = ">= 199711L";
> stds[03] = ">= 199711L";
> diff --git a/libstdc++-v3/include/bits/version.h
> b/libstdc++-v3/include/bits/version.h
> index 9ba99deeda6..511030bde47 100644
> --- a/libstdc++-v3/include/bits/version.h
> +++ b/libstdc++-v3/include/bits/version.h
> @@ -2169,4 +2169,15 @@
> #endif /* !defined(__cpp_lib_generator) && defined(__glibcxx_want_generator)
> */
> #undef __glibcxx_want_generator
>
> +// from version.def line 1774
> +#if !defined(__cpp_lib_tuple_like)
> +# if (__cplusplus >= 202100L)
> +# define __glibcxx_tuple_like 202207L
> +# if defined(__glibcxx_want_all) || defined(__glibcxx_want_tuple_like)
> +# define __cpp_lib_tuple_like 202207L
> +# endif
> +# endif
> +#endif /* !defined(__cpp_lib_tuple_like) &&
> defined(__glibcxx_want_tuple_like) */
> +#undef __glibcxx_want_tuple_like
> +
> #undef __glibcxx_want_all
> diff --git a/libstdc++-v3/include/std/concepts
> b/libstdc++-v3/include/std/concepts
> index 66ed3714b25..4f3e059b051 100644
> --- a/libstdc++-v3/include/std/concepts
> +++ b/libstdc++-v3/include/std/concepts
> @@ -62,6 +62,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> concept same_as
> = __detail::__same_as<_Tp, _Up> && __detail::__same_as<_Up, _Tp>;
>
> + namespace __detail
> + {
> + template<typename _Tp, typename _Up>
> + concept __different_from
> + = !same_as<remove_cvref_t<_Tp>, remove_cvref_t<_Up>>;
> + } // namespace __detail
> +
> /// [concept.derived], concept derived_from
> template<typename _Derived, typename _Base>
> concept derived_from = __is_base_of(_Base, _Derived)
> @@ -185,8 +192,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>
> template<typename _Tp, typename _Up>
> concept __adl_swap
> - = (__detail::__class_or_enum<remove_reference_t<_Tp>>
> - || __detail::__class_or_enum<remove_reference_t<_Up>>)
> + = (std::__detail::__class_or_enum<remove_reference_t<_Tp>>
> + || std::__detail::__class_or_enum<remove_reference_t<_Up>>)
> && requires(_Tp&& __t, _Up&& __u) {
> swap(static_cast<_Tp&&>(__t), static_cast<_Up&&>(__u));
> };
> diff --git a/libstdc++-v3/include/std/map b/libstdc++-v3/include/std/map
> index dcfd222d173..4a96e59a5bc 100644
> --- a/libstdc++-v3/include/std/map
> +++ b/libstdc++-v3/include/std/map
> @@ -74,6 +74,7 @@
> #define __glibcxx_want_map_try_emplace
> #define __glibcxx_want_node_extract
> #define __glibcxx_want_nonmember_container_access
> +#define __glibcxx_want_tuple_like
> #include <bits/version.h>
>
> #if __cplusplus >= 201703L
> diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
> index f2413badd9c..7d739852677 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -2389,11 +2389,7 @@ namespace views::__adaptor
> inline constexpr bool __is_basic_string_view<basic_string_view<_CharT,
> _Traits>>
> = true;
>
> - template<typename _Range>
> - inline constexpr bool __is_subrange = false;
> -
> - template<typename _Iter, typename _Sent, subrange_kind _Kind>
> - inline constexpr bool __is_subrange<subrange<_Iter, _Sent, _Kind>> =
> true;
> + using ranges::__detail::__is_subrange;
>
> template<typename _Range>
> inline constexpr bool __is_iota_view = false;
> @@ -4166,6 +4162,10 @@ namespace views::__adaptor
>
> namespace __detail
> {
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _Tp, size_t _Nm>
> + concept __has_tuple_element = __tuple_like<_Tp> && _Nm <
> tuple_size_v<_Tp>;
> +#else
> template<typename _Tp, size_t _Nm>
> concept __has_tuple_element = requires(_Tp __t)
> {
> @@ -4175,6 +4175,7 @@ namespace views::__adaptor
> { std::get<_Nm>(__t) }
> -> convertible_to<const tuple_element_t<_Nm, _Tp>&>;
> };
> +#endif
>
> template<typename _Tp, size_t _Nm>
> concept __returnable_element
> @@ -4559,23 +4560,12 @@ namespace views::__adaptor
> || (!(bidirectional_range<_Rs> && ...) && (common_range<_Rs> && ...))
> || ((random_access_range<_Rs> && ...) && (sized_range<_Rs> && ...));
>
> - template<typename... _Ts>
> - struct __tuple_or_pair
> - { using type = std::tuple<_Ts...>; };
> -
> - template<typename _Tp, typename _Up>
> - struct __tuple_or_pair<_Tp, _Up>
> - { using type = pair<_Tp, _Up>; };
> -
> - template<typename... _Ts>
> - using __tuple_or_pair_t = typename __tuple_or_pair<_Ts...>::type;
> -
> template<typename _Fp, typename _Tuple>
> constexpr auto
> __tuple_transform(_Fp&& __f, _Tuple&& __tuple)
> {
> return std::apply([&]<typename... _Ts>(_Ts&&... __elts) {
> - return __tuple_or_pair_t<invoke_result_t<_Fp&, _Ts>...>
> + return tuple<invoke_result_t<_Fp&, _Ts>...>
> (std::__invoke(__f, std::forward<_Ts>(__elts))...);
> }, std::forward<_Tuple>(__tuple));
> }
> @@ -4696,7 +4686,7 @@ namespace views::__adaptor
> #ifdef __clang__ // LLVM-61763 workaround
> public:
> #endif
> - __detail::__tuple_or_pair_t<iterator_t<__detail::__maybe_const_t<_Const,
> _Vs>>...> _M_current;
> + tuple<iterator_t<__detail::__maybe_const_t<_Const, _Vs>>...> _M_current;
>
> constexpr explicit
> _Iterator(decltype(_M_current) __current)
> @@ -4728,7 +4718,7 @@ namespace views::__adaptor
> // iterator_category defined in __zip_view_iter_cat
> using iterator_concept = decltype(_S_iter_concept());
> using value_type
> - =
> __detail::__tuple_or_pair_t<range_value_t<__detail::__maybe_const_t<_Const,
> _Vs>>...>;
> + = tuple<range_value_t<__detail::__maybe_const_t<_Const, _Vs>>...>;
> using difference_type
> = common_type_t<range_difference_t<__detail::__maybe_const_t<_Const,
> _Vs>>...>;
>
> @@ -4900,7 +4890,7 @@ namespace views::__adaptor
> template<bool _Const>
> class zip_view<_Vs...>::_Sentinel
> {
> - __detail::__tuple_or_pair_t<sentinel_t<__detail::__maybe_const_t<_Const,
> _Vs>>...> _M_end;
> + tuple<sentinel_t<__detail::__maybe_const_t<_Const, _Vs>>...> _M_end;
>
> constexpr explicit
> _Sentinel(decltype(_M_end) __end)
> @@ -8325,8 +8315,7 @@ namespace views::__adaptor
> && __detail::__cartesian_product_is_common<_First, _Vs...>)
> {
> auto __its = [this]<size_t... _Is>(index_sequence<_Is...>) {
> - using _Ret = __detail::__tuple_or_pair_t<iterator_t<_First>,
> - iterator_t<_Vs>...>;
> + using _Ret = tuple<iterator_t<_First>, iterator_t<_Vs>...>;
> bool __empty_tail = (ranges::empty(std::get<1 + _Is>(_M_bases)) || ...);
> auto& __first = std::get<0>(_M_bases);
> return _Ret{(__empty_tail
> @@ -8342,8 +8331,7 @@ namespace views::__adaptor
> end() const requires __detail::__cartesian_product_is_common<const
> _First, const _Vs...>
> {
> auto __its = [this]<size_t... _Is>(index_sequence<_Is...>) {
> - using _Ret = __detail::__tuple_or_pair_t<iterator_t<const _First>,
> - iterator_t<const _Vs>...>;
> + using _Ret = tuple<iterator_t<const _First>, iterator_t<const _Vs>...>;
> bool __empty_tail = (ranges::empty(std::get<1 + _Is>(_M_bases)) || ...);
> auto& __first = std::get<0>(_M_bases);
> return _Ret{(__empty_tail
> @@ -8416,8 +8404,8 @@ namespace views::__adaptor
> {
> using _Parent = __maybe_const_t<_Const, cartesian_product_view>;
> _Parent* _M_parent = nullptr;
> - __detail::__tuple_or_pair_t<iterator_t<__maybe_const_t<_Const, _First>>,
> - iterator_t<__maybe_const_t<_Const, _Vs>>...>
> _M_current;
> + tuple<iterator_t<__maybe_const_t<_Const, _First>>,
> + iterator_t<__maybe_const_t<_Const, _Vs>>...> _M_current;
>
> constexpr
> _Iterator(_Parent& __parent, decltype(_M_current) __current)
> @@ -8444,11 +8432,11 @@ namespace views::__adaptor
> using iterator_category = input_iterator_tag;
> using iterator_concept = decltype(_S_iter_concept());
> using value_type
> - = __detail::__tuple_or_pair_t<range_value_t<__maybe_const_t<_Const,
> _First>>,
> - range_value_t<__maybe_const_t<_Const,
> _Vs>>...>;
> + = tuple<range_value_t<__maybe_const_t<_Const, _First>>,
> + range_value_t<__maybe_const_t<_Const, _Vs>>...>;
> using reference
> - =
> __detail::__tuple_or_pair_t<range_reference_t<__maybe_const_t<_Const,
> _First>>,
> - range_reference_t<__maybe_const_t<_Const,
> _Vs>>...>;
> + = tuple<range_reference_t<__maybe_const_t<_Const, _First>>,
> + range_reference_t<__maybe_const_t<_Const, _Vs>>...>;
> using difference_type =
> decltype(cartesian_product_view::_S_difference_type());
>
> _Iterator() = default;
> diff --git a/libstdc++-v3/include/std/tuple b/libstdc++-v3/include/std/tuple
> index be92f1eb973..ba364d6a4f8 100644
> --- a/libstdc++-v3/include/std/tuple
> +++ b/libstdc++-v3/include/std/tuple
> @@ -50,6 +50,7 @@
> #define __glibcxx_want_apply
> #define __glibcxx_want_make_from_tuple
> #define __glibcxx_want_ranges_zip
> +#define __glibcxx_want_tuple_like
> #include <bits/version.h>
>
> namespace std _GLIBCXX_VISIBILITY(default)
> @@ -246,6 +247,22 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> _Head _M_head_impl;
> };
>
> +#if __cpp_lib_tuple_like // >= C++23
> + struct __tuple_like_tag_t { explicit __tuple_like_tag_t() = default; };
> +
> + // These forward declarations are used by the operator<=> overload for
> + // tuple-like types.
> + template<typename _Cat, typename _Tp, typename _Up>
> + constexpr _Cat
> + __tuple_cmp(const _Tp&, const _Up&, index_sequence<>);
> +
> + template<typename _Cat, typename _Tp, typename _Up,
> + size_t _Idx0, size_t... _Idxs>
> + constexpr _Cat
> + __tuple_cmp(const _Tp& __t, const _Up& __u,
> + index_sequence<_Idx0, _Idxs...>);
> +#endif // C++23
> +
> /**
> * Contains the actual implementation of the @c tuple template, stored
> * as a recursive inheritance hierarchy from the first element (most
> @@ -342,6 +359,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> { }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _UTuple, size_t... _Is>
> + constexpr
> + _Tuple_impl(__tuple_like_tag_t, _UTuple&& __u, index_sequence<_Is...>)
> + : _Tuple_impl(std::get<_Is>(std::forward<_UTuple>(__u))...)
> + { }
> +#endif // C++23
> +
> template<typename _Alloc>
> _GLIBCXX20_CONSTEXPR
> _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
> @@ -428,6 +453,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> { }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _Alloc, typename _UTuple, size_t... _Is>
> + constexpr
> + _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag, const _Alloc&
> __a,
> + _UTuple&& __u, index_sequence<_Is...>)
> + : _Tuple_impl(__tag, __a, std::get<_Is>(std::forward<_UTuple>(__u))...)
> + { }
> +#endif // C++23
> +
> template<typename... _UElements>
> _GLIBCXX20_CONSTEXPR
> void
> @@ -470,6 +504,24 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _UTuple>
> + constexpr void
> + _M_assign(__tuple_like_tag_t __tag, _UTuple&& __u)
> + {
> + _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
> + _M_tail(*this)._M_assign(__tag, std::forward<_UTuple>(__u));
> + }
> +
> + template<typename _UTuple>
> + constexpr void
> + _M_assign(__tuple_like_tag_t __tag, _UTuple&& __u) const
> + {
> + _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u));
> + _M_tail(*this)._M_assign(__tag, std::forward<_UTuple>(__u));
> + }
> +#endif // C++23
> +
> protected:
> _GLIBCXX20_CONSTEXPR
> void
> @@ -563,6 +615,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> { }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _UTuple>
> + constexpr
> + _Tuple_impl(__tuple_like_tag_t, _UTuple&& __u, index_sequence<0>)
> + : _Tuple_impl(std::get<0>(std::forward<_UTuple>(__u)))
> + { }
> +#endif // C++23
> +
> template<typename _Alloc>
> _GLIBCXX20_CONSTEXPR
> _Tuple_impl(allocator_arg_t __tag, const _Alloc& __a)
> @@ -633,6 +693,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> { }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _Alloc, typename _UTuple>
> + constexpr
> + _Tuple_impl(__tuple_like_tag_t, allocator_arg_t __tag, const _Alloc&
> __a,
> + _UTuple&& __u, index_sequence<0>)
> + : _Tuple_impl(__tag, __a, std::get<0>(std::forward<_UTuple>(__u)))
> + { }
> +#endif // C++23
> +
> template<typename _UHead>
> _GLIBCXX20_CONSTEXPR
> void
> @@ -667,6 +736,18 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _UTuple>
> + constexpr void
> + _M_assign(__tuple_like_tag_t, _UTuple&& __u)
> + { _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u)); }
> +
> + template<typename _UTuple>
> + constexpr void
> + _M_assign(__tuple_like_tag_t, _UTuple&& __u) const
> + { _M_head(*this) = std::get<_Idx>(std::forward<_UTuple>(__u)); }
> +#endif // C++23
> +
> protected:
> _GLIBCXX20_CONSTEXPR
> void
> @@ -846,6 +927,35 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> #endif
> }
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _UTuple>
> + static consteval bool
> + __dangles_from_tuple_like()
> + {
> + return []<size_t... _Is>(index_sequence<_Is...>) {
> + return
> __dangles<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> + }(index_sequence_for<_Elements...>{});
> + }
> +
> + template<typename _UTuple>
> + static consteval bool
> + __constructible_from_tuple_like()
> + {
> + return []<size_t... _Is>(index_sequence<_Is...>) {
> + return
> __constructible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> + }(index_sequence_for<_Elements...>{});
> + }
> +
> + template<typename _UTuple>
> + static consteval bool
> + __convertible_from_tuple_like()
> + {
> + return []<size_t... _Is>(index_sequence<_Is...>) {
> + return
> __convertible<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> + }(index_sequence_for<_Elements...>{});
> + }
> +#endif // C++23
> +
> public:
> constexpr
> explicit(!(__is_implicitly_default_constructible_v<_Elements> && ...))
> @@ -1016,10 +1126,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> tuple(const pair<_U1, _U2>&&) = delete;
> #endif // C++23
>
> -#if 0 && __cpp_lib_tuple_like // >= C++23
> - template<__tuple_like _UTuple>
> - constexpr explicit(...)
> - tuple(_UTuple&& __u);
> +#if __cpp_lib_tuple_like // >= C++23
> + template<__eligible_tuple_like<tuple> _UTuple>
> + requires (__constructible_from_tuple_like<_UTuple>())
> + && (!__use_other_ctor<_UTuple>())
> + && (!__dangles_from_tuple_like<_UTuple>())
> + constexpr explicit(!__convertible_from_tuple_like<_UTuple>())
> + tuple(_UTuple&& __u)
> + : _Inherited(__tuple_like_tag_t{},
> + std::forward<_UTuple>(__u),
> + index_sequence_for<_Elements...>{})
> + { }
> +
> + template<__eligible_tuple_like<tuple> _UTuple>
> + requires (__constructible_from_tuple_like<_UTuple>())
> + && (!__use_other_ctor<_UTuple>())
> + && (__dangles_from_tuple_like<_UTuple>())
> + tuple(_UTuple&&) = delete;
> #endif // C++23
>
> // Allocator-extended constructors.
> @@ -1202,10 +1325,23 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> tuple(allocator_arg_t, const _Alloc&, const pair<_U1, _U2>&&) = delete;
> #endif // C++23
>
> -#if 0 && __cpp_lib_tuple_like // >= C++23
> - template<typename _Alloc, __tuple_like _UTuple>
> - constexpr explicit(...)
> - tuple(allocator_arg_t __tag, const _Alloc& __a, _UTuple&& __u);
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _Alloc, __eligible_tuple_like<tuple> _UTuple>
> + requires (__constructible_from_tuple_like<_UTuple>())
> + && (!__use_other_ctor<_UTuple>())
> + && (!__dangles_from_tuple_like<_UTuple>())
> + constexpr explicit(!__convertible_from_tuple_like<_UTuple>())
> + tuple(allocator_arg_t __tag, const _Alloc& __a, _UTuple&& __u)
> + : _Inherited(__tuple_like_tag_t{},
> + __tag, __a, std::forward<_UTuple>(__u),
> + index_sequence_for<_Elements...>{})
> + { }
> +
> + template<typename _Alloc, __eligible_tuple_like<tuple> _UTuple>
> + requires (__constructible_from_tuple_like<_UTuple>())
> + && (!__use_other_ctor<_UTuple>())
> + && (__dangles_from_tuple_like<_UTuple>())
> + tuple(allocator_arg_t, const _Alloc&, _UTuple&&) = delete;
> #endif // C++23
>
> #else // !(concepts && conditional_explicit)
> @@ -1539,6 +1675,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> #endif // C++23
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<typename _UTuple>
> + static consteval bool
> + __assignable_from_tuple_like()
> + {
> + return []<size_t... _Is>(index_sequence<_Is...>) {
> + return
> __assignable<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> + }(index_sequence_for<_Elements...>{});
> + }
> +
> + template<typename _UTuple>
> + static consteval bool
> + __const_assignable_from_tuple_like()
> + {
> + return []<size_t... _Is>(index_sequence<_Is...>) {
> + return
> __const_assignable<decltype(std::get<_Is>(std::declval<_UTuple>()))...>();
> + }(index_sequence_for<_Elements...>{});
> + }
> +#endif // C++23
> +
> public:
>
> tuple& operator=(const tuple& __u) = delete;
> @@ -1661,14 +1817,59 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> #endif // C++23
>
> -#if 0 && __cpp_lib_tuple_like // >= C++23
> - template<__tuple_like _UTuple>
> +#if __cpp_lib_tuple_like // >= C++23
> + template<__eligible_tuple_like<tuple> _UTuple>
> + requires (__assignable_from_tuple_like<_UTuple>())
> constexpr tuple&
> - operator=(_UTuple&& __u);
> + operator=(_UTuple&& __u)
> + {
> + this->_M_assign(__tuple_like_tag_t{}, std::forward<_UTuple>(__u));
> + return *this;
> + }
> +
> + template<__eligible_tuple_like<tuple> _UTuple>
> + requires (__const_assignable_from_tuple_like<_UTuple>())
> + constexpr const tuple&
> + operator=(_UTuple&& __u) const
> + {
> + this->_M_assign(__tuple_like_tag_t{}, std::forward<_UTuple>(__u));
> + return *this;
> + }
>
> template<__tuple_like _UTuple>
> - constexpr tuple&
> - operator=(_UTuple&& __u) const;
> + requires (!__is_tuple_v<_UTuple>)
> + friend constexpr bool
> + operator==(const tuple& __t, const _UTuple& __u)
> + {
> + static_assert(sizeof...(_Elements) == tuple_size_v<_UTuple>,
> + "tuple objects can only be compared if they have equal sizes.");
> + return [&]<size_t... _Is>(index_sequence<_Is...>) {
> + return (bool(std::get<_Is>(__t) == std::get<_Is>(__u))
> + && ...);
> + }(index_sequence_for<_Elements...>{});
> + }
> +
> + template<__tuple_like _UTuple,
> + typename = make_index_sequence<tuple_size_v<_UTuple>>>
> + struct __tuple_like_common_comparison_category;
> +
> + template<__tuple_like _UTuple, size_t... _Is>
> + requires requires
> + { typename void_t<__detail::__synth3way_t<_Elements,
> tuple_element_t<_Is, _UTuple>>...>; }
> + struct __tuple_like_common_comparison_category<_UTuple,
> index_sequence<_Is...>>
> + {
> + using type = common_comparison_category_t
> + <__detail::__synth3way_t<_Elements, tuple_element_t<_Is,
> _UTuple>>...>;
> + };
> +
> + template<__tuple_like _UTuple>
> + requires (!__is_tuple_v<_UTuple>)
> + friend constexpr typename
> __tuple_like_common_comparison_category<_UTuple>::type
> + operator<=>(const tuple& __t, const _UTuple& __u)
> + {
> + using _Cat = typename
> __tuple_like_common_comparison_category<_UTuple>::type;
> + return std::__tuple_cmp<_Cat>(__t, __u,
> index_sequence_for<_Elements...>());
> + }
> #endif // C++23
>
> #else // ! (concepts && consteval)
> @@ -2433,27 +2634,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> forward_as_tuple(_Elements&&... __args) noexcept
> { return tuple<_Elements&&...>(std::forward<_Elements>(__args)...); }
>
> - // Declarations of std::array and its std::get overloads, so that
> - // std::tuple_cat can use them if <tuple> is included before <array>.
> -
> - template<typename _Tp, size_t _Nm> struct array;
> -
> - template<size_t _Int, typename _Tp, size_t _Nm>
> - constexpr _Tp&
> - get(array<_Tp, _Nm>&) noexcept;
> -
> - template<size_t _Int, typename _Tp, size_t _Nm>
> - constexpr _Tp&&
> - get(array<_Tp, _Nm>&&) noexcept;
> -
> - template<size_t _Int, typename _Tp, size_t _Nm>
> - constexpr const _Tp&
> - get(const array<_Tp, _Nm>&) noexcept;
> -
> - template<size_t _Int, typename _Tp, size_t _Nm>
> - constexpr const _Tp&&
> - get(const array<_Tp, _Nm>&&) noexcept;
> -
> /// @cond undocumented
> template<size_t, typename, typename, size_t>
> struct __make_tuple_impl;
> @@ -2569,8 +2749,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> /// @endcond
>
> /// Create a `tuple` containing all elements from multiple tuple-like
> objects
> +#if __cpp_lib_tuple_like // >= C++23
> + template<__tuple_like... _Tpls>
> +#else
> template<typename... _Tpls, typename = typename
> enable_if<__and_<__is_tuple_like<_Tpls>...>::value>::type>
> +#endif
> constexpr auto
> tuple_cat(_Tpls&&... __tpls)
> -> typename __tuple_cat_result<_Tpls...>::__type
> @@ -2722,7 +2906,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> std::get<_Idx>(std::forward<_Tuple>(__t))...);
> }
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template <typename _Fn, __tuple_like _Tuple>
> +#else
> template <typename _Fn, typename _Tuple>
> +#endif
> constexpr decltype(auto)
> apply(_Fn&& __f, _Tuple&& __t)
> noexcept(__unpack_std_tuple<is_nothrow_invocable, _Fn, _Tuple>)
> @@ -2741,7 +2929,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> __make_from_tuple_impl(_Tuple&& __t, index_sequence<_Idx...>)
> { return _Tp(std::get<_Idx>(std::forward<_Tuple>(__t))...); }
>
> +#if __cpp_lib_tuple_like // >= C++23
> + template <typename _Tp, __tuple_like _Tuple>
> +#else
> template <typename _Tp, typename _Tuple>
> +#endif
> constexpr _Tp
> make_from_tuple(_Tuple&& __t)
> noexcept(__unpack_std_tuple<is_nothrow_constructible, _Tp, _Tuple>)
> @@ -2759,17 +2951,60 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> }
> #endif
>
> -#if __cpp_lib_ranges_zip // >= C++23
> - template<typename... _TTypes, typename... _UTypes,
> +#if __cpp_lib_tuple_like // >= C++23
> + template<__tuple_like _TTuple, __tuple_like _UTuple,
> + template<typename> class _TQual, template<typename> class _UQual,
> + typename = make_index_sequence<tuple_size_v<_TTuple>>>
> + struct __tuple_like_common_reference;
> +
> + template<__tuple_like _TTuple, __tuple_like _UTuple,
> + template<typename> class _TQual, template<typename> class _UQual,
> + size_t... _Is>
> + requires requires
> + { typename tuple<common_reference_t<_TQual<tuple_element_t<_Is,
> _TTuple>>,
> + _UQual<tuple_element_t<_Is,
> _UTuple>>>...>; }
> + struct __tuple_like_common_reference<_TTuple, _UTuple, _TQual, _UQual,
> index_sequence<_Is...>>
> + {
> + using type = tuple<common_reference_t<_TQual<tuple_element_t<_Is,
> _TTuple>>,
> + _UQual<tuple_element_t<_Is,
> _UTuple>>>...>;
> + };
> +
> + template<__tuple_like _TTuple, __tuple_like _UTuple,
> template<typename> class _TQual, template<typename> class _UQual>
> - requires requires { typename tuple<common_reference_t<_TQual<_TTypes>,
> _UQual<_UTypes>>...>; }
> - struct basic_common_reference<tuple<_TTypes...>, tuple<_UTypes...>,
> _TQual, _UQual>
> - { using type = tuple<common_reference_t<_TQual<_TTypes>,
> _UQual<_UTypes>>...>; };
> -
> - template<typename... _TTypes, typename... _UTypes>
> - requires requires { typename tuple<common_type_t<_TTypes, _UTypes>...>; }
> - struct common_type<tuple<_TTypes...>, tuple<_UTypes...>>
> - { using type = tuple<common_type_t<_TTypes, _UTypes>...>; };
> + requires (__is_tuple_v<_TTuple> || __is_tuple_v<_UTuple>)
> + && is_same_v<_TTuple, decay_t<_TTuple>>
> + && is_same_v<_UTuple, decay_t<_UTuple>>
> + && (tuple_size_v<_TTuple> == tuple_size_v<_UTuple>)
> + && requires { typename __tuple_like_common_reference<_TTuple, _UTuple,
> _TQual, _UQual>::type; }
> + struct basic_common_reference<_TTuple, _UTuple, _TQual, _UQual>
> + {
> + using type = typename __tuple_like_common_reference<_TTuple, _UTuple,
> _TQual, _UQual>::type;
> + };
> +
> + template<__tuple_like _TTuple, __tuple_like _UTuple,
> + typename = make_index_sequence<tuple_size_v<_TTuple>>>
> + struct __tuple_like_common_type;
> +
> + template<__tuple_like _TTuple, __tuple_like _UTuple, size_t... _Is>
> + requires requires
> + { typename tuple<common_type_t<tuple_element_t<_Is, _TTuple>,
> + tuple_element_t<_Is, _UTuple>>...>; }
> + struct __tuple_like_common_type<_TTuple, _UTuple, index_sequence<_Is...>>
> + {
> + using type = tuple<common_type_t<tuple_element_t<_Is, _TTuple>,
> + tuple_element_t<_Is, _UTuple>>...>;
> + };
> +
> + template<__tuple_like _TTuple, __tuple_like _UTuple>
> + requires (__is_tuple_v<_TTuple> || __is_tuple_v<_UTuple>)
> + && is_same_v<_TTuple, decay_t<_TTuple>>
> + && is_same_v<_UTuple, decay_t<_UTuple>>
> + && (tuple_size_v<_TTuple> == tuple_size_v<_UTuple>)
> + && requires { typename __tuple_like_common_type<_TTuple,
> _UTuple>::type; }
> + struct common_type<_TTuple, _UTuple>
> + {
> + using type = typename __tuple_like_common_type<_TTuple, _UTuple>::type;
> + };
> #endif // C++23
>
> /// @}
> diff --git a/libstdc++-v3/include/std/unordered_map
> b/libstdc++-v3/include/std/unordered_map
> index efad0cef584..ea6129d6494 100644
> --- a/libstdc++-v3/include/std/unordered_map
> +++ b/libstdc++-v3/include/std/unordered_map
> @@ -51,6 +51,7 @@
> #define __glibcxx_want_node_extract
> #define __glibcxx_want_nonmember_container_access
> #define __glibcxx_want_unordered_map_try_emplace
> +#define __glibcxx_want_tuple_like
> #include <bits/version.h>
>
> #if __cplusplus >= 201703L
> diff --git a/libstdc++-v3/include/std/utility
> b/libstdc++-v3/include/std/utility
> index f113d572e59..212513f6f48 100644
> --- a/libstdc++-v3/include/std/utility
> +++ b/libstdc++-v3/include/std/utility
> @@ -92,6 +92,7 @@
> #define __glibcxx_want_tuple_element_t
> #define __glibcxx_want_tuples_by_type
> #define __glibcxx_want_unreachable
> +#define __glibcxx_want_tuple_like
> #include <bits/version.h>
>
> namespace std _GLIBCXX_VISIBILITY(default)
> diff --git a/libstdc++-v3/testsuite/20_util/pair/p2165r4.cc
> b/libstdc++-v3/testsuite/20_util/pair/p2165r4.cc
> new file mode 100644
> index 00000000000..ef06df1c53f
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/20_util/pair/p2165r4.cc
> @@ -0,0 +1,173 @@
> +// Verify P2165R4 enhancements to std::pair.
> +// { dg-do run { target c++23 } }
> +
> +#include <array>
> +#include <tuple>
> +#include <utility>
> +#include <testsuite_hooks.h>
> +
> +using std::array;
> +using std::pair;
> +using std::tuple;
> +
> +struct A { };
> +
> +template<template<typename> class pair_like_t>
> +constexpr bool
> +test01()
> +{
> + struct B {
> + int m;
> + constexpr B(A&) : m(0) { }
> + constexpr B(A&&) : m(1) { }
> + constexpr B(const A&) : m(2) { }
> + constexpr B(const A&&) : m(3) { }
> + };
> +
> + // template<pair-like UPair>
> + // constexpr explicit(false) pair(UPair&&);
> +
> + pair_like_t<A> pair_like;
> +
> + [&] {
> + pair<B, B> p2b = pair_like;
> + VERIFY( p2b.first.m == 0 && p2b.second.m == 0 );
> + }();
> + [&] {
> + pair<B, B> p2b = std::move(pair_like);
> + VERIFY( p2b.first.m == 1 && p2b.second.m == 1 );
> + }();
> + [&] {
> + pair<B, B> p2b = std::as_const(pair_like);
> + VERIFY( p2b.first.m == 2 && p2b.second.m == 2 );
> + }();
> + [&] {
> + pair<B, B> p2b = std::move(std::as_const(pair_like));
> + VERIFY( p2b.first.m == 3 && p2b.second.m == 3 );
> + }();
> +
> + // Verify dangling checks.
> + static_assert( !std::is_constructible_v<pair<const int&, int>,
> pair_like_t<long>> );
> + static_assert( !std::is_constructible_v<pair<int, const int&>,
> pair_like_t<long>> );
> +
> + return true;
> +}
> +
> +template<template<typename> class pair_like_t>
> +constexpr bool
> +test02()
> +{
> + struct B {
> + int m;
> + constexpr explicit B(A&) : m(0) { }
> + constexpr explicit B(A&&) : m(1) { }
> + constexpr explicit B(const A&) : m(2) { }
> + constexpr explicit B(const A&&) : m(3) { }
> + };
> +
> + // template<pair-like UPair>
> + // constexpr explicit(true) pair(UPair&&);
> +
> + static_assert( !std::is_convertible_v<pair_like_t<A>, pair<B, B>> );
> +
> + pair_like_t<A> pair_like;
> +
> + [&] {
> + pair<B, B> p2b{pair_like};
> + VERIFY( p2b.first.m == 0 && p2b.second.m == 0 );
> + }();
> + [&] {
> + pair<B, B> p2b{std::move(pair_like)};
> + VERIFY( p2b.first.m == 1 && p2b.second.m == 1 );
> + }();
> + [&] {
> + pair<B, B> p2b{std::as_const(pair_like)};
> + VERIFY( p2b.first.m == 2 && p2b.second.m == 2 );
> + }();
> + [&] {
> + pair<B, B> p2b{std::move(std::as_const(pair_like))};
> + VERIFY( p2b.first.m == 3 && p2b.second.m == 3 );
> + }();
> +
> + return true;
> +}
> +
> +template<template<typename> class pair_like_t>
> +constexpr bool
> +test03()
> +{
> + struct B {
> + int m;
> + constexpr B& operator=(A&) { m = 0; return *this; }
> + constexpr B& operator=(A&&) { m = 1; return *this; }
> + constexpr B& operator=(const A&) { m = 2; return *this; }
> + constexpr B& operator=(const A&&) { m = 3; return *this; }
> + };
> +
> + // template<pair-like UPair>
> + // constexpr pair& operator=(UPair&&);
> +
> + pair_like_t<A> pair_like;
> +
> + pair<B, B> p2b;
> + p2b = pair_like;
> + VERIFY( p2b.first.m == 0 && p2b.second.m == 0 );
> + p2b = std::move(pair_like);
> + VERIFY( p2b.first.m == 1 && p2b.second.m == 1 );
> + p2b = std::as_const(pair_like);
> + VERIFY( p2b.first.m == 2 && p2b.second.m == 2 );
> + p2b = std::move(std::as_const(pair_like));
> + VERIFY( p2b.first.m == 3 && p2b.second.m == 3 );
> +
> + return true;
> +}
> +
> +template<template<typename> class pair_like_t>
> +constexpr bool
> +test04()
> +{
> + struct B {
> + mutable int m;
> + constexpr const B& operator=(A&) const { m = 0; return *this; }
> + constexpr const B& operator=(A&&) const { m = 1; return *this; }
> + constexpr const B& operator=(const A&) const { m = 2; return *this; }
> + constexpr const B& operator=(const A&&) const { m = 3; return *this; }
> + };
> +
> + // template<pair-like UPair>
> + // constexpr const pair& operator=(UPair&&) const;
> +
> + pair_like_t<A> pair_like;
> +
> + const pair<B, B> p2b;
> + p2b = pair_like;
> + VERIFY( p2b.first.m == 0 && p2b.second.m == 0 );
> + p2b = std::move(pair_like);
> + VERIFY( p2b.first.m == 1 && p2b.second.m == 1 );
> + p2b = std::as_const(pair_like);
> + VERIFY( p2b.first.m == 2 && p2b.second.m == 2 );
> + p2b = std::move(std::as_const(pair_like));
> + VERIFY( p2b.first.m == 3 && p2b.second.m == 3 );
> +
> + return true;
> +}
> +
> +template<typename T>
> +using pair_like_array = array<T, 2>;
> +
> +template<typename T>
> +using pair_like_tuple = tuple<T, T>;
> +
> +int
> +main()
> +{
> + static_assert( test01<pair_like_array>() );
> + static_assert( test02<pair_like_array>() );
> + static_assert( test03<pair_like_array>() );
> + static_assert( test04<pair_like_array>() );
> +
> + static_assert( test01<pair_like_tuple>() );
> + static_assert( test02<pair_like_tuple>() );
> + static_assert( test03<pair_like_tuple>() );
> + static_assert( test04<pair_like_tuple>() );
> +}
> diff --git a/libstdc++-v3/testsuite/20_util/tuple/p2165r4.cc
> b/libstdc++-v3/testsuite/20_util/tuple/p2165r4.cc
> new file mode 100644
> index 00000000000..e2437c469b6
> --- /dev/null
> +++ b/libstdc++-v3/testsuite/20_util/tuple/p2165r4.cc
> @@ -0,0 +1,335 @@
> +// Verify P2165R4 enhancements to std::tuple.
> +// { dg-do run { target c++23 } }
> +
> +#include <array>
> +#include <tuple>
> +#include <utility>
> +#include <memory>
> +#include <testsuite_hooks.h>
> +
> +using std::array;
> +using std::pair;
> +using std::tuple;
> +using std::allocator;
> +using std::allocator_arg_t;
> +using std::allocator_arg;
> +
> +namespace alloc {
> + struct B01;
> + struct B02;
> +}
> +
> +template<> struct std::uses_allocator<alloc::B01, allocator<int>> :
> std::true_type { };
> +template<> struct std::uses_allocator<alloc::B02, allocator<int>> :
> std::true_type { };
> +
> +struct A { };
> +
> +template<template<typename> class tuple_like_t>
> +constexpr bool
> +test01()
> +{
> + struct B {
> + int m;
> + constexpr B(A&) : m(0) { }
> + constexpr B(A&&) : m(1) { }
> + constexpr B(const A&) : m(2) { }
> + constexpr B(const A&&) : m(3) { }
> + };
> +
> + // template<tuple-like UTuple>
> + // constexpr explicit(false) tuple(UTuple&&);
> +
> + tuple_like_t<A> tuple_like;
> +
> + [&] {
> + tuple<B, B, B> t3b = tuple_like;
> + VERIFY( std::get<0>(t3b).m == 0 && std::get<1>(t3b).m == 0 &&
> std::get<2>(t3b).m == 0 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b = std::move(tuple_like);
> + VERIFY( std::get<0>(t3b).m == 1 && std::get<1>(t3b).m == 1 &&
> std::get<2>(t3b).m == 1 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b = std::as_const(tuple_like);
> + VERIFY( std::get<0>(t3b).m == 2 && std::get<1>(t3b).m == 2 &&
> std::get<2>(t3b).m == 2 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b = std::move(std::as_const(tuple_like));
> + VERIFY( std::get<0>(t3b).m == 3 && std::get<1>(t3b).m == 3 &&
> std::get<2>(t3b).m == 3 );
> + }();
> +
> + // Verify dangling checks.
> + static_assert( !std::is_constructible_v<tuple<const int&, int, int>,
> tuple_like_t<long>> );
> + static_assert( !std::is_constructible_v<tuple<int, const int&, int>,
> tuple_like_t<long>> );
> + static_assert( !std::is_constructible_v<tuple<int, int, const int&>,
> tuple_like_t<long>> );
> +
> + return true;
> +}
> +
> +namespace alloc
> +{
> + struct B01 {
> + int m;
> + B01(A&);
> + B01(A&&);
> + B01(const A&);
> + B01(const A&&);
> + constexpr B01(allocator_arg_t, allocator<int>, A&) : m(0) { }
> + constexpr B01(allocator_arg_t, allocator<int>, A&&) : m(1) { }
> + constexpr B01(allocator_arg_t, allocator<int>, const A&) : m(2) { }
> + constexpr B01(allocator_arg_t, allocator<int>, const A&&) : m(3) { }
> + };
> +
> + template<template<typename> class tuple_like_t>
> + constexpr bool
> + test01()
> + {
> + using B = B01;
> +
> + // template<tuple-like UTuple>
> + // constexpr explicit(false) tuple(allocator_arg_t, const Alloc&,
> UTuple&&);
> +
> + tuple_like_t<A> tuple_like;
> +
> + [&] {
> + tuple<B, B, B> t3b = {allocator_arg, allocator<int>{}, tuple_like};
> + VERIFY( std::get<0>(t3b).m == 0 && std::get<1>(t3b).m == 0 &&
> std::get<2>(t3b).m == 0 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b = {allocator_arg, allocator<int>{},
> std::move(tuple_like)};
> + VERIFY( std::get<0>(t3b).m == 1 && std::get<1>(t3b).m == 1 &&
> std::get<2>(t3b).m == 1 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b = {allocator_arg, allocator<int>{},
> std::as_const(tuple_like)};
> + VERIFY( std::get<0>(t3b).m == 2 && std::get<1>(t3b).m == 2 &&
> std::get<2>(t3b).m == 2 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b = {allocator_arg, allocator<int>{},
> std::move(std::as_const(tuple_like))};
> + VERIFY( std::get<0>(t3b).m == 3 && std::get<1>(t3b).m == 3 &&
> std::get<2>(t3b).m == 3 );
> + }();
> +
> + // Verify dangling checks.
> + static_assert( !std::is_constructible_v<tuple<const int&, int, int>,
> + allocator_arg_t, allocator<int>,
> + tuple_like_t<long>> );
> + static_assert( !std::is_constructible_v<tuple<int, const int&, int>,
> + allocator_arg_t, allocator<int>,
> + tuple_like_t<long>> );
> + static_assert( !std::is_constructible_v<tuple<int, int, const int&>,
> + allocator_arg_t, allocator<int>,
> + tuple_like_t<long>> );
> +
> + return true;
> + }
> +}
> +
> +template<template<typename> class tuple_like_t>
> +constexpr bool
> +test02()
> +{
> + struct B {
> + int m;
> + constexpr explicit B(A&) : m(0) { }
> + constexpr explicit B(A&&) : m(1) { }
> + constexpr explicit B(const A&) : m(2) { }
> + constexpr explicit B(const A&&) : m(3) { }
> + };
> +
> + // template<tuple-like UTuple>
> + // constexpr explicit(true) tuple(UTuple&&);
> +
> + static_assert( !std::is_convertible_v<tuple_like_t<A>, tuple<B, B, B>> );
> +
> + tuple_like_t<A> tuple_like;
> +
> + [&] {
> + tuple<B, B, B> t3b{tuple_like};
> + VERIFY( std::get<0>(t3b).m == 0 && std::get<1>(t3b).m == 0 &&
> std::get<2>(t3b).m == 0 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b{std::move(tuple_like)};
> + VERIFY( std::get<0>(t3b).m == 1 && std::get<1>(t3b).m == 1 &&
> std::get<2>(t3b).m == 1 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b{std::as_const(tuple_like)};
> + VERIFY( std::get<0>(t3b).m == 2 && std::get<1>(t3b).m == 2 &&
> std::get<2>(t3b).m == 2 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b{std::move(std::as_const(tuple_like))};
> + VERIFY( std::get<0>(t3b).m == 3 && std::get<1>(t3b).m == 3 &&
> std::get<2>(t3b).m == 3 );
> + }();
> +
> + return true;
> +}
> +
> +namespace alloc
> +{
> + struct B02 {
> + int m;
> + explicit B02(A&);
> + explicit B02(A&&);
> + explicit B02(const A&);
> + explicit B02(const A&&);
> + explicit constexpr B02(allocator_arg_t, allocator<int>, A&) : m(0) { }
> + explicit constexpr B02(allocator_arg_t, allocator<int>, A&&) : m(1) { }
> + explicit constexpr B02(allocator_arg_t, allocator<int>, const A&) : m(2)
> { }
> + explicit constexpr B02(allocator_arg_t, allocator<int>, const A&&) :
> m(3) { }
> + };
> +
> + template<template<typename> class tuple_like_t>
> + constexpr bool
> + test02()
> + {
> + using B = B02;
> +
> + // template<tuple-like UTuple>
> + // constexpr explicit(true) tuple(allocator_arg_t, const Alloc&,
> UTuple&&);
> +
> + static_assert( !std::is_convertible_v<tuple_like_t<A>, tuple<B, B, B>> );
> +
> + tuple_like_t<A> tuple_like;
> +
> + [&] {
> + tuple<B, B, B> t3b{allocator_arg, allocator<int>{}, tuple_like};
> + VERIFY( std::get<0>(t3b).m == 0 && std::get<1>(t3b).m == 0 &&
> std::get<2>(t3b).m == 0 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b{allocator_arg, allocator<int>{},
> std::move(tuple_like)};
> + VERIFY( std::get<0>(t3b).m == 1 && std::get<1>(t3b).m == 1 &&
> std::get<2>(t3b).m == 1 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b{allocator_arg, allocator<int>{},
> std::as_const(tuple_like)};
> + VERIFY( std::get<0>(t3b).m == 2 && std::get<1>(t3b).m == 2 &&
> std::get<2>(t3b).m == 2 );
> + }();
> + [&] {
> + tuple<B, B, B> t3b{allocator_arg, allocator<int>{},
> std::move(std::as_const(tuple_like))};
> + VERIFY( std::get<0>(t3b).m == 3 && std::get<1>(t3b).m == 3 &&
> std::get<2>(t3b).m == 3 );
> + }();
> +
> + return true;
> + }
> +}
> +
> +
> +template<template<typename> class tuple_like_t>
> +constexpr bool
> +test03()
> +{
> + struct B {
> + int m;
> + constexpr B& operator=(A&) { m = 0; return *this; }
> + constexpr B& operator=(A&&) { m = 1; return *this; }
> + constexpr B& operator=(const A&) { m = 2; return *this; }
> + constexpr B& operator=(const A&&) { m = 3; return *this; }
> + };
> +
> + // template<tuple-like UTuple>
> + // constexpr tuple& operator=(UTuple&&);
> +
> + tuple_like_t<A> tuple_like;
> +
> + tuple<B, B, B> t3b;
> + t3b = tuple_like;
> + VERIFY( std::get<0>(t3b).m == 0 && std::get<1>(t3b).m == 0 &&
> std::get<2>(t3b).m == 0 );
> + t3b = std::move(tuple_like);
> + VERIFY( std::get<0>(t3b).m == 1 && std::get<1>(t3b).m == 1 &&
> std::get<2>(t3b).m == 1 );
> + t3b = std::as_const(tuple_like);
> + VERIFY( std::get<0>(t3b).m == 2 && std::get<1>(t3b).m == 2 &&
> std::get<2>(t3b).m == 2 );
> + t3b = std::move(std::as_const(tuple_like));
> + VERIFY( std::get<0>(t3b).m == 3 && std::get<1>(t3b).m == 3 &&
> std::get<2>(t3b).m == 3 );
> +
> + return true;
> +}
> +
> +template<template<typename> class tuple_like_t>
> +constexpr bool
> +test04()
> +{
> + struct B {
> + mutable int m;
> + constexpr const B& operator=(A&) const { m = 0; return *this; }
> + constexpr const B& operator=(A&&) const { m = 1; return *this; }
> + constexpr const B& operator=(const A&) const { m = 2; return *this; }
> + constexpr const B& operator=(const A&&) const { m = 3; return *this; }
> + };
> +
> + // template<tuple-like UTuple>
> + // constexpr const tuple& operator=(UTuple&&) const;
> +
> + tuple_like_t<A> tuple_like;
> +
> + const tuple<B, B, B> t3b;
> + t3b = tuple_like;
> + VERIFY( std::get<0>(t3b).m == 0 && std::get<1>(t3b).m == 0 &&
> std::get<2>(t3b).m == 0 );
> + t3b = std::move(tuple_like);
> + VERIFY( std::get<0>(t3b).m == 1 && std::get<1>(t3b).m == 1 &&
> std::get<2>(t3b).m == 1 );
> + t3b = std::as_const(tuple_like);
> + VERIFY( std::get<0>(t3b).m == 2 && std::get<1>(t3b).m == 2 &&
> std::get<2>(t3b).m == 2 );
> + t3b = std::move(std::as_const(tuple_like));
> + VERIFY( std::get<0>(t3b).m == 3 && std::get<1>(t3b).m == 3 &&
> std::get<2>(t3b).m == 3 );
> +
> + return true;
> +}
> +
> +template<template<typename> class tuple_like_t>
> +constexpr bool
> +test05()
> +{
> + // template<tuple-like UTuple>
> + // constexpr bool operator==(const tuple&, const UTuple&);
> +
> + static_assert( tuple{1, 2, 3} == tuple_like_t{1, 2, 3} );
> + static_assert( tuple{1, 2, 4} != tuple_like_t{1, 2, 3} );
> + static_assert( tuple_like_t{1, 2, 3} == tuple{1, 2, 3} );
> + static_assert( tuple_like_t{1, 2, 3} != tuple{1, 2, 4} );
> +
> + // template<tuple-like UTuple>
> + // constexpr bool operator<=>const tuple&, const UTuple&);
> +
> + static_assert( (tuple{1, 2, 3} <=> tuple_like_t{1, 2, 3}) ==
> std::strong_ordering::equal );
> + static_assert( (tuple{1, 2, 4} <=> tuple_like_t{1, 2, 3}) ==
> std::strong_ordering::greater );
> + static_assert( (tuple_like_t{1, 2, 3} <=> tuple{1, 2, 3}) ==
> std::strong_ordering::equal );
> + static_assert( (tuple_like_t{1, 2, 3} <=> tuple{1, 2, 4}) ==
> std::strong_ordering::less );
> +
> + static_assert( tuple{1, 2, 4} > tuple_like_t{1, 2, 3} );
> + static_assert( tuple_like_t{1, 2, 3} < tuple{1, 2, 4} );
> +
> + // template<tuple-like TTuple, tuple-like UTuple, ...>
> + // struct basic_common_reference<TTuple, UTuple, ...>;
> +
> + static_assert( std::same_as<std::common_reference_t<tuple_like_t<int>,
> + tuple<int, long, int>>,
> + tuple<int, long, int>> );
> +
> + static_assert( std::same_as<std::common_reference_t<tuple<int, long, int>,
> + tuple_like_t<int>>,
> + tuple<int, long, int>> );
> +
> + // template<tuple-like TTuple, tuple-like UTuple>
> + // struct common_type<TTuple, UTuple>;
> +
> + static_assert( std::same_as<std::common_type_t<tuple_like_t<const int&>,
> + tuple<int, long, int>>,
> + tuple<int, long, int>> );
> +
> + static_assert( std::same_as<std::common_type_t<tuple<int, long, int>,
> + tuple_like_t<const int&>>,
> + tuple<int, long, int>> );
> +
> + return true;
> +}
> +
> +template<typename T>
> +using tuple_like_array = array<T, 3>;
> +
> +int
> +main()
> +{
> + static_assert( test01<tuple_like_array>() );
> + static_assert( alloc::test01<tuple_like_array>() );
> + static_assert( test02<tuple_like_array>() );
> + static_assert( alloc::test02<tuple_like_array>() );
> + static_assert( test03<tuple_like_array>() );
> + static_assert( test04<tuple_like_array>() );
> + static_assert( test05<tuple_like_array>() );
> +}
> diff --git a/libstdc++-v3/testsuite/std/ranges/zip/1.cc
> b/libstdc++-v3/testsuite/std/ranges/zip/1.cc
> index b7717aed92c..672a8c356d9 100644
> --- a/libstdc++-v3/testsuite/std/ranges/zip/1.cc
> +++ b/libstdc++-v3/testsuite/std/ranges/zip/1.cc
> @@ -41,8 +41,8 @@ test01()
> VERIFY( i2 == z2.end() );
> VERIFY( ranges::size(z2) == 2 );
> VERIFY( ranges::size(std::as_const(z2)) == 2 );
> - VERIFY( z2[0].first == 1 && z2[0].second == 3 );
> - VERIFY( z2[1].first == 2 && z2[1].second == 4 );
> + VERIFY( std::get<0>(z2[0]) == 1 && std::get<1>(z2[0]) == 3 );
> + VERIFY( std::get<0>(z2[1]) == 2 && std::get<1>(z2[1]) == 4 );
> for (const auto [x, y] : z2)
> {
> VERIFY( y - x == 2 );
> --
> 2.43.0.386.ge02ecfcc53
>
>
