Debugging and PR87352

[Jeremy Sanders <jeremy at jeremysanders dot net>]

Dear developers

As I've hit a number of gfortran bugs (PR87542 and probably PR56471 when 
I tried to workaround it), I thought I would dig into the source code of 
gfortran. It's quite difficult to debug given the complex structures 
which are passed around. Are there any functions to print some of the 
gfc_ structures, e.g. gfc_symbol, gfc_expr, gfc_namespace, gfc_code...?

For PR87542, if there is a declaration like this

module testmodule
  use iso_fortran_env
  implicit none
  public

  type :: evtlist_type
     real   (kind=real64), allocatable, dimension(:) :: p1
     real   (kind=real64), allocatable, dimension(:) :: p2
     ! add more entries here to observe N**2 behaviour
  end type evtlist_type

  type :: evtlistlist_type
     type(evtlist_type)  :: evtlist(1:1)
  end type evtlistlist_type

contains
end module testmodule

gfortran makes ~N**2 invocations of structure_alloc_comps, where N here 
is 2. If you add more of the allocatable arrays to evtlist_type then N 
increases. This leads to huge code and compile time bloat (scaling as 
N**2), where each member is checked whether it is allocated and then 
freed if it is not N times.

I'm guessing this is something to do with the logic in 
generate_finalization_wrapper and finalize_component. If I comment out 
the loop part of finalize_component, then the excess finalizers are not 
added. Unfortunately my understanding of the code isn't complete yet - 
hence my wondering whether it's possible to dump out some of the gfc 
data structures to the screen.

Thanks

Jeremy Sanders
(please CC me as I'm not on the list)