Using the latest xtensor stack I realised that using xt::linalg:eig() from xtensor-blas results in an error when trying to assign to the real part of the complex results vector. I am using xsimd as well.

.../build/_deps/xtensor-blas-src/include/xtensor-blas/xlinalg.hpp:328:32: required from ‘auto xt::linalg::eig(const xt::xexpression&) [with E = xt::xarray_container<xt::uvector<double, xsimd::aligned_allocator<double, 32> >, xt::layout_type::row_major, xt::svector<long unsigned int, 4, std::allocator, true>, xt::xtensor_expression_tag>; std::enable_if_t<((bool)(! xtl::is_complex::value))>* = 0]’
328 | xt::real(eig_vals) = wr;
| ~~~~~~~~~~~~~~~~~~~^~~~

.../build/_deps/xtensor-src/include/xtensor/chunk/../chunk/../core/../core/../core/xassign.hpp:717:83: error: ‘class xt::xfunctor_view<xt::detail::offset_forwarder<double, 0>, xt::xtensor_container<xt::uvector<std::complex, xsimd::aligned_allocator<std::complex, 32> >, 1, xt::layout_type::row_major, xt::xtensor_expression_tag>&>’ has no member named ‘data’; did you mean ‘at’?
717 | size_type align_begin = is_aligned ? 0 : xt_simd::get_alignment_offset(e1.data(), size, simd_size);
| ~~~^~~~
| at

Maybe an issue guiding to the proper assignment.