Circular dependency of refactored library on monolithic model code

[ivanpribec]

Is the circular dependency an implementation dependency or an interface dependency? How does the circular dependency manifest?

Is it a circular module dependency (interface dependency) ?

! mo_feature.f90
module feature
  use grid
! ...
end module

! mo_grid.f90
module grid
#ifdef LIBFEATURE
   use feature, only: foo
#endif
! ...
end module

Edit: you can find some previous discussion of circular dependencies,

• Ways to suppress Circularity
• Class array with different types at each index - #4 by ivanpribec; shows use of the surrogate pattern introduced in Scientific Software Design by @rouson, Xia and Xu as a way of circumventing circular dependencies