[Bug fortran/91077] New: [8/9/10 Regression] Wrong indexing when using a pointer

[tkoenig at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91077

            Bug ID: 91077
           Summary: [8/9/10 Regression] Wrong indexing when using a
                    pointer
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: tkoenig at gcc dot gnu.org
  Target Milestone: ---

From a c.l.f. post by ygalklein@gmail.com (slightly modified):

program test
  implicit none
  integer, parameter :: length = 9
  real(8), dimension(2) :: a, b
  integer :: i
  type point
     real(8) :: x
  end type point

  type stored
     type(point), dimension(:), allocatable :: np
  end type stored
  type(stored), dimension(:), pointer :: std =>null()
  allocate(std(1))
  allocate(std(1)%np(length))
  std(1)%np(1)%x = 0.3d0
  std(1)%np(2)%x = 0.3555d0
  std(1)%np(3)%x = 0.26782d0
  std(1)%np(4)%x = 0d0
  std(1)%np(5)%x = 1.555d0
  std(1)%np(6)%x = 7.3d0
  std(1)%np(7)%x = 7.8d0
  std(1)%np(8)%x = 6.3d0
  std(1)%np(9)%x = 5.5d0
  do i = 1, 2
     write(*, "('std(1)%np(',i1,')%x = ',1e22.14)") i, std(1)%np(i)%x
  end do
  do i = 1, 2
     write(*, "('std(1)%np(1:',i1,') = ',9e22.14)") i, std(1)%np(1:i)%x
  end do
  a = std(1)%np(1:2)%x
  b = [std(1)%np(1)%x, std(1)%np(2)%x]
  print *,a
  print *,b
  if (norm2(a - b) .gt. 1d-3) then
     write(*,*) 'failure'
  else
     write(*, *) 'success'
  end if
end program test

yields

std(1)%np(1)%x =   0.30000000000000E+00
std(1)%np(2)%x =   0.35550000000000E+00
std(1)%np(1:1) =   0.30000000000000E+00
std(1)%np(1:2) =   0.30000000000000E+00  0.55000000000000E+01
  0.29999999999999999        5.5000000000000000     
  0.29999999999999999       0.35549999999999998     
 failure

with gcc-8, gcc-9 and current trunk.

Something is rotten in the state of Denmark here.