fix compilation issue with gcc < 10 and -std=c++2a

This commit is contained in:
Jörg Buchwald 2022-01-13 01:24:20 +01:00
parent a30ecb7221
commit d1bf056394

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@ -223,7 +223,7 @@ template<typename T, std::size_t N> struct array_size<std::array<T,N> > {
*
* For C++20, this function just forwards to `std::ssize`, or any ADL discoverable `ssize` function.
*/
#if EIGEN_COMP_CXXVER < 20
#if EIGEN_COMP_CXXVER < 20 || EIGEN_GNUC_AT_MOST(9,4)
template <typename T>
EIGEN_CONSTEXPR auto index_list_size(const T& x) {
using R = std::common_type_t<std::ptrdiff_t, std::make_signed_t<decltype(x.size())>>;