[Bug fortran/64921] [4.9/5/6 Regression] FAIL: gfortran.dg/class_allocate_18.f90

["mathewc at nag dot co.uk" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64921

--- Comment #14 from Mat Cross <mathewc at nag dot co.uk> ---
For the record, perhaps it is of interest for me to note that we are running
into this (cf. PR64230 comment 9) on code like

Program test
  Implicit None
  Type :: t1
    Integer, Allocatable :: i
  End Type
  Type :: t2
    Integer, Allocatable :: i
  End Type
  Type, Extends (t1) :: t3
    Type (t2) :: j
  End Type
  Type, Extends (t3) :: t4
    Integer, Allocatable :: k
  End Type
  Call s
  Print *, 'ok'
Contains
  Subroutine s
    Class (t1), Allocatable :: x
    Allocate (t4 :: x)
  End Subroutine
End Program

Since the crash is in bad compiler-generated finalization code (since 4.9), and
given that (if I recall correctly) gfortran is using the Fortran 2008 semantics
for entities declared in a main program being implicitly saved, this is why
removing the Deallocate (in the comment 12 example) works - the finalizer is
never called then.

In the interim, does anyone have any bright ideas for a reasonable (few-line)
workaround?

Thanks.