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LWG-3974 mdspan::operator[] should not copy OtherIndexTypes #4166

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StephanTLavavej opened this issue Nov 12, 2023 · 0 comments · Fixed by #4214
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LWG-3974 mdspan::operator[] should not copy OtherIndexTypes #4166

StephanTLavavej opened this issue Nov 12, 2023 · 0 comments · Fixed by #4214
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fixed Something works now, yay! LWG Library Working Group issue mdspan C++23 mdspan

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@StephanTLavavej
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LWG-3974 mdspan::operator[] should not copy OtherIndexTypes

The accepted resolution says extents_type::index-cast while we use static_cast<index_type>:

STL/stl/inc/mdspan

Lines 1286 to 1291 in 46843b3

template <class _OtherIndexType, size_t... _Seq>
_NODISCARD constexpr reference _Multidimensional_subscript(
span<_OtherIndexType, rank()> _Indices, index_sequence<_Seq...>) const
noexcept(noexcept(_Access_impl(static_cast<index_type>(_STD as_const(_Indices[_Seq]))...))) {
return _Access_impl(static_cast<index_type>(_STD as_const(_Indices[_Seq]))...);
}

I'm 80% sure this is unobservable, but I'm filing this issue to double-check.
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fixed Something works now, yay! LWG Library Working Group issue mdspan C++23 mdspan
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<mdspan>: Check preconditions of mdspan::operator[] clarified by LWG-3974 frederick-vs-ja/STL
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@StephanTLavavej