sanity check of dimensions in the front end about trexio

[q-posev]

The best solution is to check that the total number of elements in user-provided array is consistent with the size of array in the file

[scemama]

You can't do it without passing the size of the array as a parameter to the function. I agree that it would be good to do it, but I am sure that the users will complain that it is redundant because we already have set nucleus_num.
Maybe we should provide both variants : one safe where you pass the dimensions as an additional parameter (an array of dimensions), and an unsafe variant which is what we have now.

[scemama]

In the Fortran interface it should be possible to do that:

  interface                                                                                                                                                                                   
     integer function trexio_write_nucleus_coord_s (trex_file, dset, dim) bind(C)                                                                                                             
       use, intrinsic :: iso_c_binding                                                                                                                                                        
       integer(8), intent(in), value :: trex_file                                                                                                                                             
       real(8), intent(in) :: dset(*)                                                                                                                                                         
       integer(4), intent(in) :: dim(2)                                                                                                                                                       
     end function trexio_write_nucleus_coord_s                                                                                                                                                
  end interface                                                                                                                                                                               
                                                                                                                                                                                              
  integer function trexio_write_nucleus_coord (trex_file, dset)                                                                                                                               
    use, intrinsic :: iso_c_binding                                                                                                                                                           
    integer(8), intent(in), value :: trex_file                                                                                                                                                
    real(8), intent(in) :: dset(:,:)                                                                                                                                                          
                                                                                                                                                                                              
    call trexio_write_nucleus_coord_s(trex_file, dset, shape(dset))                                                                                                                           
  end function trexio_write_nucleus_coord 

So that the fortran has only the "unsafe" API, but it calls the safe C routines. The real unsafe nature will only be present in C.

[q-posev]

@scemama I agree that this is not really user-friendly and unfortunately we cannot evaluate the number of elements when a pointer to an array is passed to a C function. For the Fortran and Python interfaces it is doable.