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From: "zed.three at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug fortran/105658] New: Passing array component to unlimited
 polymorphic routine passes wrong slice
Date: Thu, 19 May 2022 09:28:10 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D105658

            Bug ID: 105658
           Summary: Passing array component to unlimited polymorphic
                    routine passes wrong slice
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zed.three at gmail dot com
  Target Milestone: ---

The following program:

    program f
    implicit none

    type :: foo
        integer :: member1
        integer :: member2
    end type foo

    type(foo), dimension(3) :: thing =3D [foo(1, 2), foo(3, 4), foo(5, 6)]

    call print_poly(thing%member1)
    call print_int(thing%member1)

    contains
        subroutine print_poly(array)
            class(*), dimension(:), intent(in) :: array

            select type(array)
            type is (integer)
                print*, array
            end select
        end subroutine

        subroutine print_int(array)
            integer, dimension(:), intent(in) :: array

            print*, array
        end subroutine
    end program f

prints:

           1           2           3
           1           3           5

when we would expect:

           1           3           5
           1           3           5

Adding `-fcheck=3Dall`, we get the warning "Fortran runtime warning: An arr=
ay
temporary was created" _only_ for the call to `print_int`.

Adding an extra set of parentheses to the `print_poly` call (`call
print_poly((thing%member1))` gives the expected behaviour, I guess because =
it's
forcing an array temporary?

This behaviour is present in 4.9.4 through to the trunk currently available=
 on
Compiler Explorer
((Compiler-Explorer-Build-gcc-7da9a089608b0ca09683332ce014fb6184842724-binu=
tils-2.38)
13.0.0 20220518 (experimental))=