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// PR c++/91911 // { dg-do compile { target c++17 } } template<class T> struct span { using value_type = T; span(T); }; template<class T> using SpanType = decltype(span{T()}); template<class T> using ConstSpanType = span<const typename SpanType<T>::value_type>; using type = ConstSpanType<int>; using type = span<const int>;