https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86328
--- Comment #3 from janus at gcc dot gnu.org ---
The code in comment 0 seems to have a small error: a%ll is allocated with only
one element (1:1), which should probably be ten (1:10). So I wonder why it runs
with gfortran-7 at all?!?
In any case, here is a corrected and slightly reduced version:
program ptr_alloc
type :: t
class(*), allocatable :: val
end type
type :: list
type(t), dimension(:), pointer :: ll
end type
integer :: i
type(list) :: a
allocate(a%ll(1:2))
do i = 1,2
print *,i
allocate(a%ll(i)%val, source=i)
end do
call rrr(a)
contains
subroutine rrr(a)
type(list), intent(in) :: a
integer :: s, j
type(t), dimension(:), allocatable :: mm
s = ubound(a%ll,1)
allocate(mm(1:s))
do j = 1, s
print *," ",j
if (allocated(a%ll(j)%val)) then
allocate(mm(j)%val, source=a%ll(j)%val)
end if
end do
end subroutine
end
This shows basically the same behavior: It runs with gfortran-7 and earlier
(and also with ifort, pgi, flang), but segfaults with gfortran-8, where
valgrind shows:
==24028== Memcheck, a memory error detector
==24028== Copyright (C) 2002-2017, and GNU GPL'd, by Julian Seward et al.
==24028== Using Valgrind-3.13.0 and LibVEX; rerun with -h for copyright info
==24028== Command: ./a.out
==24028==
1
2
1
==24028== Use of uninitialised value of size 8
==24028== at 0x40170A: rrr.3800 (c3.f90:36)
==24028== by 0x4010CF: MAIN__ (c3.f90:20)
==24028== by 0x401EF2: main (c3.f90:20)
==24028==
==24028== Use of uninitialised value of size 8
==24028== at 0x4017E9: rrr.3800 (c3.f90:36)
==24028== by 0x4010CF: MAIN__ (c3.f90:20)
==24028== by 0x401EF2: main (c3.f90:20)
==24028==
==24028== Use of uninitialised value of size 8
==24028== at 0x4018BD: rrr.3800 (c3.f90:36)
==24028== by 0x4010CF: MAIN__ (c3.f90:20)
==24028== by 0x401EF2: main (c3.f90:20)
==24028==
2
==24028== Invalid read of size 8
==24028== at 0x4017E9: rrr.3800 (c3.f90:36)
==24028== by 0x4010CF: MAIN__ (c3.f90:20)
==24028== by 0x401EF2: main (c3.f90:20)
==24028== Address 0xb285ac0 is not stack'd, malloc'd or (recently) free'd
==24028==
Program received signal SIGSEGV: Segmentation fault - invalid memory reference.
