Proposed resolution:

This wording is relative to N5014.

1. Modify [simd.syn] as indicated:

   namespace std::simd {
     […]
     template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
       requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
       constexpr void
         unchecked_scatter_to(const V& v, R&& out,
                              const I& indices, flags<Flags...> f = {});
     template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
       requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
       constexpr void
         unchecked_scatter_to(const V& v, R&& out, const typename I::mask_type& mask,
                              const I& indices, flags<Flags...> f = {});
   
     template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
       requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
       constexpr void
         partial_scatter_to(const V& v, R&& out,
                            const I& indices, flags<Flags...> f = {});
     template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
       requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
       constexpr void
         partial_scatter_to(const V& v, R&& out, const typename I::mask_type& mask,
                            const I& indices, flags<Flags...> f = {});
     […]
   }
   

2. Modify [simd.permute.memory] as indicated:

   template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
     requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
     constexpr void unchecked_scatter_to(const V& v, R&& out, const I& indices,
                                         flags<Flags...> f = {});
   template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
     requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
     constexpr void unchecked_scatter_to(const V& v, R&& out, const typename I::mask_type& mask,
                                         const I& indices, flags<Flags...> f = {});
   

   -10- Let `mask` be `typename I::mask_type(true)` for the overload with no `mask` parameter.

   […]

   template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
     requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
     constexpr void
     partial_scatter_to(const V& v, R&& out, const I& indices, flags<Flags...> f = {});
   template<simd-vec-type V, ranges::contiguous_range R, simd-integral I, class... Flags>
     requires ranges::sized_range<R> && ranges::output_range<R, typename V::value_type>
     constexpr void partial_scatter_to(const V& v, R&& out, const typename I::mask_type& mask,
                                       const I& indices, flags<Flags...> f = {});
   

   -13- Let `mask` be `typename I::mask_type(true)` for the overload with no `mask` parameter.

   […]

[ 2025-11-28; Resolved by LWG 4420, approved in Kona. Status changed: New → Resolved. ]

[ 2025-10-22; Reflector poll. ]

Set priority to 2 after reflector poll.

This issue is related to LWG 4420. The Constrains needs to be updated to handle conversions between float and float16_t and similar cases.

Both `simd::unchecked_scatter_to` and `simd::partial_scatter_to` are used to write a `simd::vec` into a range `R`.

However, they only require `R` to be `contiguous_range` and `sized_range`. Requiring `R` to be `output_range` is also necessary; otherwise, the `constant_range` cannot be written.