Debugging fortran codes

[Tobias Burnus]

  Hello Salvatore,

Salvatore Filippone wrote:
> I have a general question: I often work in Linux under DDD/GDB  to debug
> programs. However the two tools do not seem to understand Fortran
> derived types (let alone CLASS variables).
>
> So: is this something that requires more hooks on gfortran's side, or is
> it just the other packages not interfacing?

For CLASS, no idea, but otherwise, debugging TYPE should mostly work. 
However, you should use the GDB which contains the patches of Jan 
Kratochvil - that's the gdb's from Red Hat / Fedora, but also the ones 
from (open)SUSE. Alternatively, you find them in git in the 
archer-jankratochvil-fedora14 branch:  
http://sourceware.org/gdb/wiki/ArcherBranchManagement

Example: For

type t
   integer :: x
   real :: y(5)
   logical, allocatable :: z(:)
end type t

one gets:

(gdb) pt mt
type = Type t
     integer(kind=4) :: x
     real(kind=4) :: y(5)
     logical(kind=4) :: z
End Type t

(gdb) pt mt%x
type = integer(kind=4)

(gdb) pt mt%y
type = real(kind=4) (5)

(Well, allocatable components it does not like:
   (gdb) pt mt%z
   type = Cannot resolve DW_OP_push_object_address for a missing object
Cf. https://bugzilla.redhat.com/show_bug.cgi?id=628175 )


Another possibility is to try Intel's IDB, which should also work with 
GCC binaries - or also Totalview.

Tobias

PS: Jan's patches are mostly needed to support Fortran 90 style arrays 
(allocatables, pointers, assumed-shape) - and C's VLA.