Found the following significant warnings:
  basic_functions.cpp:178:47: warning: 'from<double, arma::eGlue<arma::Glue<arma::Row<double>, arma::Col<double>, arma::glue_times>, arma::Glue<arma::Row<double>, arma::Op<arma::Row<double>, arma::op_htrans>, arma::glue_times>, arma::eglue_minus>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1459:45: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1462:45: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1549:53: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1550:49: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1551:55: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1768:45: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
  mcmc_functions.cpp:1771:45: warning: 'from<double, arma::Glue<arma::Op<arma::Col<double>, arma::op_htrans>, arma::Col<double>, arma::glue_times>>' is deprecated: replace conv_to<...>::from(X) with as_scalar(X) [-Wdeprecated-declarations]
See ‘/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/hmcdm.Rcheck/00install.out’ for details.
* used C++ compiler: ‘Debian clang version 19.1.7 (3+b2)’