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From: Harald Anlauf <anlauf@gmx.de>
Subject: Re: [PATCH 09/10] fortran: Support clobbering of variable
 subreferences [PR88364]
Date: Sun, 18 Sep 2022 20:32:09 +0200
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On 18.09.22 12:23, Thomas Koenig via Gcc-patches wrote:
> 
> On 18.09.22 11:10, Mikael Morin wrote:
>> It is unfortunate as there is some desirable behavior within reach here. 
> 
> I think some of the desired behavior can still be salvaged.  For
> example, for
> 
>    subroutine foo(a,n)
>      integer :: n
>      integer, dimension(n), intent(in) :: n

     integer, dimension(n), intent(out) :: a  ! ?

> ...
> 
>    subroutine bar(a)
>      integer, intent(out) :: a
> 
> ...
> 
>    integer :: a(3)
> 
>    call foo(a,3)
>    call foo(a(1),3)
> 
> clobbers for the whole array can still be generated, but not for
> 
>    call foo(a(2),2)
> 
> so one would have to look at the lower bound.
> 
> For this case, it would be helpful to clobber a range a(2:), but that
> is a wishlist item for the future ;-)
> 
> What is unsafe, currently, is
> 
>    call bar(a(1))

We'll need a good coverage by testcases for the different handling
required for assumed shape / assumed size / explicit size dummies
to avoid new regressions.  Assumed shape will be on the easy side,
while assumed size likely needs to be excluded for clobbering.

Harald