Re: [PATCH, v2] Fortran: fix invalid rank error in ASSOCIATED when rank is remapped [PR77652]

[Toon Moene <toon@moene.org>]

Looks good to me.

Thanks !

Toon.

On 7/30/22 12:03, Mikael Morin wrote:

> Le 28/07/2022 à 22:19, Mikael Morin a écrit :
>> I propose to prepare something tomorrow.
>>
> 
> Here you go.  I haven’t found a procedure, a template or guidelines on 
> wg5-fortran.org, so I’m just asking questions as free text.
> I have not put every combination of cases to limit the number of 
> examples, but an answer for each example should give a good picture.
> Anything to correct or change?  Anything to add?
> 
> Mikael
> 
> 
> Hello,
> 
> we are contributors to gfortran.  We have been discussing the 
> restrictions a processor is required to put on ASSOCIATED functions 
> calls with regards to rank mismatch in the thread at:
>> https://gcc.gnu.org/pipermail/fortran/2022-July/058012.html
> The following discussions are on the same topic as well:
>> https://groups.google.com/g/comp.lang.fortran/c/BQfpeDZxX3Q
>> https://community.intel.com/t5/Intel-Fortran-Compiler/Intel-rejects-ASSOCIATED-pointer-target-for-non-equal-ranks/m-p/1402799/highlight/true#M162159 
>>
> 
> The position from Steve Lionel in the latter threads is that a processor 
> is required to reject an ASSOCIATED function call with arguments of 
> mismatching ranks as there is no bounds-remapping list.
> Our understanding is that a processor shall accept it as long as it may 
> accept a corresponding pointer association statement with additional 
> bounds-remapping list.
> 
> Our poll of existing compilers shows the same disagreement, with two 
> accepting mismatching ranks (cray 14.0, nvidia 22.5) and two rejecting 
> them (NAG 7.0 & 7.1, Intel).
> 
> So we would like an official interpretation on this topic.
> More specifically, for each program below, is a processor (at compile 
> time) required to reject it, allowed to reject it but not required to, 
> or required to accept it?
> 
> Harald Anlauf, Mikael Morin
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 1
> ! matrix pointer vs array target
> program p
>    real, dimension(100),  target  :: array
>    real, dimension(:,:),  pointer :: pmatrix => null()
>    print *, associated(pmatrix, array)
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 2
> ! array pointer vs matrix target
> program p
>    real, dimension(20,5), target  :: matrix
>    real, dimension(:),    pointer :: parray => null()
>    print *, associated(parray, matrix)
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 3
> ! array pointer vs rank 2 non-contiguous target
> program p
>    real, dimension(20,5), target  :: matrix
>    real, dimension(:),    pointer :: parray => null()
>    print *, associated(parray, matrix(1:20:3, 1:5:2))
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 4
> ! array pointer vs scalar target
> program p
>    real, target :: scalar
>    real, dimension(:), pointer :: parray => null()
>    print *, associated(parray, scalar)
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 5
> ! scalar pointer vs array target
> program p
>    real, dimension(100), target :: array
>    real, pointer :: pscalar => null()
>    print *, associated(pscalar, array)
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 6
> ! assumed rank (array) pointer vs matrix target
> program p
>    real, dimension(20,5), target  :: matrix
>    real, dimension(:),    pointer :: parray => null()
>    call sub(parray)
> contains
>    subroutine sub(ptr)
>      real, pointer :: ptr(..)
>      print *, associated(ptr, matrix)
>    end subroutine sub
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 7
> ! assumed rank (scalar) pointer vs array target
> program p
>    real, dimension(100), target :: array
>    real, pointer :: pscalar => null()
>    call sub(pscalar)
> contains
>    subroutine sub(ptr)
>      real, pointer :: ptr(..)
>      print *, associated(ptr, array)
>    end subroutine sub
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
> 
> ! Example 8
> ! assumed rank (array) pointer vs scalar target
> program p
>    real, target :: scalar
>    real, dimension(:), pointer :: parray => null()
>    call sub(parray)
> contains
>    subroutine sub(ptr)
>      real, pointer :: ptr(..)
>      print *, associated(ptr, scalar)
>    end subroutine sub
> end
> 
> !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!


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