https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97045
Bug ID: 97045
Summary: A wrong column is selected when addressing individual
elements of unlimited polymorphic dummy argument
Product: gcc
Version: 10.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: fortran
Assignee: unassigned at gcc dot gnu.org
Reporter: igor.gayday at mu dot edu
Target Milestone: ---
Consider the following Fortran program:
program test_prg
implicit none
integer :: i
integer, allocatable :: arr(:, :)
arr = reshape([(i, i = 1, 100)], [10, 10])
do i = 1, 3
print *, 'Column', i
call write_array(arr(1:2, i))
end do
contains
subroutine write_array(array)
class(*), intent(in) :: array(:)
integer :: i
do i = 1, size(array)
select type (elem => array(i))
type is (integer)
print '(I0)', elem
end select
end do
end subroutine
subroutine write_array_alt(array)
class(*), intent(in) :: array(:)
integer :: i
select type (array)
type is (integer)
print '(I0)', array
end select
end subroutine
end program
Compiled with gfortran 9.3.0 (and 10.2), the program prints:
Column 1
1
2
Column 2
21
22
Column 3
41
42
As you can see, it skips every other column. If I replace the call to
write_array with the call to write_array_alt, where I select type of the whole
array and not individual elements, then every column is printed, as expected.
This issue was originally reported here:
https://stackoverflow.com/questions/63841012/a-wrong-column-is-selected-when-addressing-individual-elements-of-unlimited-poly
