I'm interfacing with a legacy C++ code which sets `EIGEN_DEFAULT_TO_ROW_MAJOR` ([well known to break compatibility](https://gitlab.com/libeigen/eigen/-/issues/422)) but, basic searching and playing with defining the macro doesn't seem to help at all in R, matrices are still in column order and have to be manually reshaped (say `matrix(byrow=T, ncol=3)`). I could wrap this thing in an R class and deal with this there every-time but was hoping I might have missed a way of setting the flag. Things I tried: ```cpp #define EIGEN_DEFAULT_TO_ROW_MAJOR #include <RcppEigen.h> // [[Rcpp::depends(RcppEigen)]] ``` And moving it after the `#include` or the comment also does not help.