[Bug fortran/99307] FAIL: gfortran.dg/class_assign_4.f90 -O0 execution test

["dominiq at lps dot ens.fr" <gcc-bugzilla@gcc.gnu.org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99307

Dominique d'Humieres <dominiq at lps dot ens.fr> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-02-27
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #1 from Dominique d'Humieres <dominiq at lps dot ens.fr> ---
Also seen on Darwin; the runtime error is

a.out(22702,0x10db51e00) malloc: Incorrect checksum for freed object
0x7ff344406fc0: probably modified after being freed.
Corrupt value: 0x41f0000000000007
a.out(22702,0x10db51e00) malloc: *** set a breakpoint in malloc_error_break to
debug

Program received signal SIGABRT: Process abort signal.

Reduced test

module m
  implicit none
  type :: t1
    integer :: i
  CONTAINS
  end type
  type, extends(t1) :: t2
    real :: r
  end type

  interface operator(+)
    module procedure add_t1
  end interface

contains
  function add_t1 (a, b) result (c)
    class(t1), intent(in) :: a(:), b(:)
    class(t1), allocatable :: c(:)
    allocate (c, source = a)
    c%i = a%i + b%i
    select type (c)
      type is (t2)
      select type (b)
        type is (t2)
          c%r = c%r + b%r
      end select
    end select
  end function add_t1

end module m

subroutine test_t1
  use m
  implicit none

  class(t1), dimension(:), allocatable :: x, y

  x = [t2(1,10.0),t2(2,20.0),t2(3,30.0)]
  y = x
  x = realloc_t1 (y)
  x = realloc_t1 (x)
  x = x(3:1:-1) + y
  x = [t2(1,10.0),t2(2,20.0),t2(3,30.0)]

contains

  function realloc_t1 (arg) result (res)
    class(t1), dimension(:), allocatable :: arg
    class(t1), dimension(:), allocatable :: res
    select type (arg)
      type is (t2)
        allocate (res, source = [t1 (arg(3)%i), t1 (arg(2)%i), t1 (arg(1)%i)])
      type is (t1)
        allocate (res, source = [t1 (arg(2)%i), t1 (arg(1)%i), t1 (arg(3)%i)])
    end select
  end function realloc_t1

end subroutine test_t1

  call test_t1
end