(j3.2006) Can initial-data-target be coindexed?

[John Reid]

Steve,

I agree with you, except that I think the fix could be applied within C461.

Cheers,

John.

Lionel, Steve wrote:
> In pointer assignment, the standard is quite clear that data-target
> cannot be coindexed:
>
> C725 (R737) A data-target shall not be a coindexed object.
>
> And there are a couple of notes related to this (citations from 12-007 ?
> I note that the numbering is a bit different in 10-007r1):
>
> NOTE 7.45
>
> A data pointer and its target are always on the same image. A coarray
> may be of a derived type with pointer
>
> or allocatable subcomponents. For example, if PTR is a pointer
> component, Z[P]%PTR is a reference to the
>
> target of component PTR of Z on image P. This target is on image P and
> its association with Z[P]%PTR
>
> must have been established by the execution of an ALLOCATE statement or
> a pointer assignment on image
>
> P.
>
> NOTE 7.46
>
> A pointer assignment statement is not permitted to involve a coindexed
> pointer or target, see C723 and
>
> C725. This prevents a pointer assignment statement from associating a
> pointer with a target on another
>
> image. If such an association would otherwise be implied, the
> association status of the pointer becomes
>
> undefined. For example, a derived-type intrinsic assignment where the
> variable and expr are on different
>
> images and the variable has an ultimate pointer component.
>
> Ok so far. F2008 added the ability to specify an initial-data-target in
> pointer initialization:
>
> 19 R505 initialization is = constant-expr
>
> 20 or => null-init
>
> 21 or => initial-data-target
>
> 22 R506 null-init is function-reference
>
> 23 C510 (R503) If => appears in initialization, the entity shall have
> the POINTER attribute. If = appears in
>
> 24 initialization, the entity shall not have the POINTER attribute.
>
> 25 C511 (R503) If initial-data-target appears, object-name shall be
> data-pointer-initialization compatible with it
>
> 26 (4.5.4.6).
>
> Initial-data-target is defined in 4.5.4.6 and the only constraints for
> it are:
>
> 1 C460 (R442) If initial-data-target appears, component-name shall be
> data-pointer-initialization compatible
>
> 2 with it.
>
> 3 C461 (R443) The designator shall designate a nonallocatable variable
> that has the TARGET and SAVE attrib-
>
> 4 utes and does not have a vector subscript. Every subscript, section
> subscript, substring starting point,
>
> 5 and substring ending point in designator shall be a constant expression.
>
> 18 2 A pointer variable or component is data-pointer-initialization
> compatible with a target if the pointer is type
>
> 19 compatible with the target, they have the same rank, all nondeferred
> type parameters of the pointer have the
>
> 20 same values as the corresponding type parameters of the target, and
> the target is contiguous if the pointer has
>
> 21 the CONTIGUOUS attribute.
>
> So
 what in the standard disallows the following?
>
> program test
>
> integer, save, target :: C[*]
>
> integer, pointer :: P => C[3]
>
> end
>
> Shouldn?t there be a constraint ?An initial-data-target shall not be a
> coindexed object??
>
> I looked through interpretations and saw no discussion of this. Interp
> fodder?
>
> Steve Lionel
>
> Intel Developer Support
>
> Merrimack, NH
>
>
>
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