On Sat, Oct 18, 2025 at 11:04:38PM +0800, Hewill Kang wrote: > These appear to be noexcept-able.
Exactly, thanks, I just sent v3. Best regards, Osama > > Osama Abdelkader <[email protected]> 於 2025年10月18日 週六 下午10:50寫道： > > > This fixes the C++23 compliance issue where std::tuple<> cannot be compared > > with other empty tuple-like types such as std::array<T, 0>. > > > > The operators correctly allow comparison with array<T, 0> even when T is > > not > > comparable, because empty tuple-like types don't compare element values. > > > > libstdc++-v3/ChangeLog: > > > > PR libstdc++/119721 > > * include/std/tuple: Add tuple<> comparison operators for > > empty tuple-like types. > > > > Signed-off-by: Osama Abdelkader <[email protected]> > > --- > > v2: > > - Replaced explicit array<T, 0> operators with generic tuple-like operators > > - Only operator== and operator<=> are provided > > - Operators work with any empty tuple-like type > > - No need for reversed argument order > > --- > > libstdc++-v3/include/std/tuple | 19 +++++++++++++++++++ > > 1 file changed, 19 insertions(+) > > > > diff --git a/libstdc++-v3/include/std/tuple > > b/libstdc++-v3/include/std/tuple > > index 0ca616f1b..800f6e372 100644 > > --- a/libstdc++-v3/include/std/tuple > > +++ b/libstdc++-v3/include/std/tuple > > @@ -2001,6 +2001,25 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION > > tuple(allocator_arg_t, const _Alloc&, const tuple&) noexcept { } > > }; > > > > +#if __cpp_lib_tuple_like // >= C++23 > > + // Comparison operators for tuple<> with other empty tuple-like types > > + // Note: These operators allow comparison with any empty tuple-like > > type, > > + // including array<T, 0> and span<T, 0>, where T may not be comparable. > > + // This is correct because empty tuple-like types don't compare > > elements. > > + template<__tuple_like _UTuple> > > + requires (!__is_tuple_v<_UTuple> && tuple_size_v<_UTuple> == 0) > > + [[nodiscard]] > > + constexpr bool > > + operator==(const tuple<>&, const _UTuple&) > > + { return true; } > > + > > + template<__tuple_like _UTuple> > > + requires (!__is_tuple_v<_UTuple> && tuple_size_v<_UTuple> == 0) > > + constexpr strong_ordering > > + operator<=>(const tuple<>&, const _UTuple&) > > + { return strong_ordering::equal; } > > +#endif // C++23 > > + > > #if !(__cpp_concepts && __cpp_consteval && __cpp_conditional_explicit) // > > !C++20 > > /// Partial specialization, 2-element tuple. > > /// Includes construction and assignment from a pair. > > -- > > 2.43.0 > > > >
