2012-09-17.org

gdb and gfortran

gdb seems not to be able to reason about dynamically allocated fortran arrays. Here an example

program test
  implicit none
  double precision, dimension(3) :: sa
  double precision, dimension(:), pointer :: da
  integer :: i

  allocate(da(size(sa)))
  do i= 1, size(sa)
    sa(i) = i
    da(i) = i
  end do
  print *, da
end program test

Compiled via

/tmp $ gfortran --version
GNU Fortran (GCC) 4.7.1 20120721 (prerelease)
...
/tmp $ gfortran -g -O0 test.f90 -o test

/tmp $ gdb test
Reading symbols from /tmp/test...done.
(gdb) b 13
Breakpoint 1 at 0x4009c7: test.f90:13. (2 locations)
(gdb) run
Starting program: /tmp/test 
warning: Could not load shared library symbols for linux-vdso.so.1.
Do you need "set solib-search-path" or "set sysroot"?

Breakpoint 1, main (argc=1, argv=0x7fffffffcd5f) at test.f90:13
13      end program test
(gdb) c
Continuing.
   1.0000000000000000        2.0000000000000000        3.0000000000000000     

Breakpoint 1, test () at test.f90:13
13      end program test
(gdb) p sa
$1 = (1, 2, 3)
(gdb) p da
$2 = (0)
(gdb) ptype sa
type = real(kind=8) (3)
(gdb) ptype da
type = real(kind=8) (*)