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From: "mikael at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug fortran/106817] New: clobber ordering problem when an actual
 intent(in) argument depends on the value of an intent(out) argument
Date: Fri, 02 Sep 2022 18:56:35 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106817

            Bug ID: 106817
           Summary: clobber ordering problem when an actual intent(in)
                    argument depends on the value of an intent(out)
                    argument
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: fortran
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mikael at gcc dot gnu.org
  Target Milestone: ---

module m
  implicit none
contains
  subroutine copy(in, out)
    integer, intent(in) :: in
    integer, intent(out) :: out
    out =3D in
  end subroutine copy
end module m

program p
  use m
  implicit none
  integer :: a
  a =3D 3
  call copy(a+1, a)
  if (a /=3D 4) stop 1
end program p


The in value (a+1) depends on the value of a, but a is clobbered at the
beginning of the call to copy, so we should make sure that we have evaluated
a+1 before generating the clobber.=