Found the following significant warnings:
  marginal.d.cpp:156:80: warning: 'static out_eT arma::conv_to<out_eT>::from(const arma::Base<eT2, expr>&, const typename arma::arma_not_cx<in_eT>::result*) [with in_eT = double; T1 = arma::Glue<arma::Glue<arma::subview_row<double>, arma::Op<arma::Mat<double>, arma::op_inv_spd_default>, arma::glue_times>, arma::Col<double>, arma::glue_times>; out_eT = double; typename arma::arma_not_cx<in_eT>::result = double]' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  marginal.d.cpp:169:78: warning: 'static out_eT arma::conv_to<out_eT>::from(const arma::Base<eT2, expr>&, const typename arma::arma_not_cx<in_eT>::result*) [with in_eT = double; T1 = arma::Glue<arma::Glue<arma::subview_row<double>, arma::Op<arma::Mat<double>, arma::op_inv_spd_default>, arma::glue_times>, arma::Col<double>, arma::glue_times>; out_eT = double; typename arma::arma_not_cx<in_eT>::result = double]' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  marginal.d.cpp:190:125: warning: 'static out_eT arma::conv_to<out_eT>::from(const arma::Base<eT2, expr>&, const typename arma::arma_not_cx<in_eT>::result*) [with in_eT = double; T1 = arma::Glue<arma::Glue<arma::Op<arma::eGlue<arma::Col<double>, arma::Col<double>, arma::eglue_minus>, arma::op_htrans>, arma::Op<arma::Mat<double>, arma::op_pinv_default>, arma::glue_times>, arma::eGlue<arma::Col<double>, arma::Col<double>, arma::eglue_minus>, arma::glue_times>; out_eT = double; typename arma::arma_not_cx<in_eT>::result = double]' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  sigma2.simulation.cpp:30:63: warning: 'static out_eT arma::conv_to<out_eT>::from(const arma::Base<eT2, expr>&, const typename arma::arma_not_cx<in_eT>::result*) [with in_eT = double; T1 = arma::Glue<arma::subview_row<double>, arma::Col<double>, arma::glue_times>; out_eT = double; typename arma::arma_not_cx<in_eT>::result = double]' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  tau.simulation.cpp:34:59: warning: 'static out_eT arma::conv_to<out_eT>::from(const arma::Base<eT2, expr>&, const typename arma::arma_not_cx<in_eT>::result*) [with in_eT = double; T1 = arma::Glue<arma::Glue<arma::Row<double>, arma::Mat<double>, arma::glue_times>, arma::Col<double>, arma::glue_times>; out_eT = double; typename arma::arma_not_cx<in_eT>::result = double]' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
See 'd:/Rcompile/CRANpkg/local/4.6/DIFM.Rcheck/00install.out' for details.
* used C++ compiler: 'g++.exe (GCC) 14.3.0'