Aw: Re: [PATCH, v2] Fortran: reject procedures and procedure pointers as IO element [PR107074]

[Harald Anlauf <anlauf@gmx.de>]

Hi Mikael,

I definitely agree that we need a temporary for the result of
MERGE(a,a,.true.), I just haven't found out how to do that.

The reason for the bad one-liner was that in gfc_simplify_merge

	result = gfc_get_parentheses (result);

actually does have issues, in that the subsequent

      gfc_simplify_expr (result, 1);

seems to fail in interesting cases (as in PR105371).

So that is something to look into...

Cheers,
Harald

> Gesendet: Donnerstag, 06. Oktober 2022 um 22:32 Uhr
> Von: "Mikael Morin" <morin-mikael@orange.fr>
> An: "Harald Anlauf" <anlauf@gmx.de>
> Cc: "gcc-patches" <gcc-patches@gcc.gnu.org>, "fortran" <fortran@gcc.gnu.org>
> Betreff: Re: [PATCH, v2] Fortran: reject procedures and procedure pointers as IO element [PR107074]
>
> Le 06/10/2022 à 10:37, Mikael Morin a écrit :
> > Le 05/10/2022 à 22:40, Harald Anlauf a écrit :
> >> Hi Mikael,
> >>
> >>> Gesendet: Mittwoch, 05. Oktober 2022 um 12:34 Uhr
> >>> Von: "Mikael Morin" <morin-mikael@orange.fr>
> >>> Please move the check to resolve_transfer in resolve.cc.
> >>
> >> I have done this, see attached updated patch.
> >>
> >> Regtests cleanly on x86_64-pc-linux-gnu.
> >>
> >>> Strangely, the patch doesn't seem to fix the problem on the testcase
> >>> here.  There is an outer parenthese expression preventing the condition
> >>> you added from triggering.  Can you double check?
> >>
> >> You are right: I had a one-liner in my worktree from PR105371 that
> >> fixes an issue with gfc_simplify_merge and that seems to help here.
> >> It is now included.
> >>
> > The rest looks good, but I'm not sure about your one-liner.
> > I will try to come with a real test later, but in principle, if you have 
> > a call to FOO(MERGE(A,A,.TRUE.)) you can't simplify it to FOO(A) as 
> > writes to the argument in FOO should not overwrite the content of A. The 
> > dummy should be associated with a temporary value, not to A.
> > 
> Here is a test that your patch breaks.
> Admittedly it's rejected if A has the INTENT(INOUT) attribute, but 
> without it, I think it's allowed.
> 
> program p
>    integer :: b
>    b = 1
>    call foo(merge(b,b,.true.))
>    if (b /= 1) stop 1
> contains
>    subroutine foo(a)
>      integer :: a
>      if (a == 1) a = 42
>    end subroutine foo
> end program p
> 
>