[Bug c++/92951] New: extern variable declaration doesn't behave properly for me

[fportera2 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92951

            Bug ID: 92951
           Summary: extern variable declaration doesn't behave properly
                    for me
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: fportera2 at gmail dot com
  Target Milestone: ---

I have a global variable 'traindata' declared in cnn.cpp:

arma::mat traindata;

, I'm importing this varible in mean_squared_error.hpp:

#include <mlpack/core.hpp>

extern arma::mat traindata;

and I'm trying to exploit this variable in mean_squared_error_impl.hpp (that
includes 'mean_squared_error.hpp'), for example:

printf("n_rows = %d, n_cols = %d\n", traindata.n_rows, traindata.n_cols);

but it gives me that the dimensions are 0's (while in the cnn.cpp' main() they
are positive).

thanks