(j3.2006) (SC22WG5.4225) RE: What shall we do with the broken feature?

[Craig Dedo]

Hi Everyone,
	FWIW, I agree with Bill and Dan.  Given the schedule for Fortran
2008 and the complexity of this particular issue, I would STRONGLY argue for
fixing via the Interpretations process for all of the mentioned reasons.  I
would argue strongly AGAINST any kind of quick fix.

	That said, I would encourage WG5 and PL22.3 to open up the Fortran
2008 Interpretations list immediately and make this issue Fortran 2008
Interpretation #000001.  One of the people who discovered or analyzed this
issue in depth should write it up and submit it at their earliest
convenience.

Sincerely,
Craig T. Dedo
17130 W. Burleigh Place
P. O. Box 423                  Mobile Phone:  (414) 412-5869
Brookfield, WI   53008-0423    E-mail:  <craig at ctdedo.com>
USA
Linked-In:  http://www.linkedin.com/in/craigdedo

-----Original Message-----
From: j3-bounces at j3-fortran.org [mailto:j3-bounces at j3-fortran.org] On Behalf
Of Dan Nagle
Sent: Wednesday, March 17, 2010 08:49
To: fortran standards email list for J3
Subject: Re: (j3.2006) (SC22WG5.4222) What shall we do with the broken
feature?

Hi,

I vote with Bill.

Quick fixes chance errors, processing an Interp allows
time for more in-depth thought.

No one is implementing this today,
we can take the time to do it right.

On Mar 17, 2010, at 4:19 AM, Malcolm Cohen wrote:

> The facility of being able to pass a null pointer or unallocated  
> allocatable to an optional nonpointer nonallocatable dummy argument  
> and have that treated as being an absent dummy argument is broken as  
> follows.
>
> (i) All of the optional DIM arguments to the intrinsic functions  
> that change the rank are qualified with "The corresponding actual  
> argument shall not be an optional dummy argument.".  Previously it  
> was not permitted to pass a null pointer here, now it is permitted  
> and gives a runtime-varying rank depending on the association status  
> of the pointer.  E.g. PRODUCT(matrix,pointer_to_dim) is rank 1 if  
> pointer_to_dim is associated and rank 0 if it is not.  20 functions  
> have a prohibition against optional dummy arguments, but in several  
> of those it is an unnecessary prohibition so fewer than 20 would be  
> necessarily affected.
>
> (ii) This feature appears to change the results of ASSOCIATED when  
> TARGET is a null pointer.  This does not appear on the surface to be  
> fixable other than by specifying that the feature does not apply to  
> this particular intrinsic function, which might be confusing.
>
> (iii) Minor: The performance of a few intrinsic functions such as  
> MAX when some arguments are pointers is adversely affected.
>
> (iv) Nitpick: the description in the Introduction omits the  
> unallocated allocatable case.
>
> How should we address the problem?
> (1) fix the DIS by deleting the feature (I don't think we have a  
> mandate for that though);
> (2) fix the DIS by changing the wording;
> (2) leave it to be fixed later via interpretation processing (other  
> than the nitpick which should be done anyway).
>
> Comments?
>
> Cheers,
> -- 
> ................................Malcolm Cohen, Nihon NAG, Tokyo.
>
> _______________________________________________
> J3 mailing list
> J3 at j3-fortran.org
> http://j3-fortran.org/mailman/listinfo/j3

-- 
Cheers!

Dan Nagle




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