Repro: ``` #define XTENSOR_ENABLE_ASSERT 1 #include <xtensor/xfixed.hpp> void test() { xt::xtensor_fixed<int, xt::xshape<3>> a = {1,2,3}; std::cout << xt::all(a <= 3) << std::endl; } ``` Compilation fails with: ``` xtensor/xiterator.hpp:1118:38: error: invalid operands to binary expression ('const xt::fixed_shape<3>' and 'const xt::fixed_shape<3>') XTENSOR_ASSERT(this->shape() == rhs.shape()); ``` The code works correctly when assertions are not enabled. Tested on 0.23.9