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COMP-FORTRAN-90  May 2011

COMP-FORTRAN-90 May 2011

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Subject:

Re: polymorphic pointer dummy and Note 12.27

From:

Malcolm Cohen <[log in to unmask]>

Reply-To:

Fortran 90 List <[log in to unmask]>

Date:

Mon, 2 May 2011 08:44:56 +0900

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (33 lines)

On 4/28/11 8:24 AM, Neil Carlson wrote:
> On Wed, Apr 27, 2011 at 9:03 PM, Jim Xia<[log in to unmask]>  wrote:
>> I don't see how 12.5.2.7p2 contradicts 12.5.2.5.  12.5.2.5 states the rules
>> applied to both POINTER and ALLOCATABLE dummies, and 12.5.2.7 lists further
>> restrictions on POINTER dummies.  So you should combine them together to get
>> a full picture.
>>
>> 12.5.2.7p2 states that an actual associated with a poly-pointer dummy could
>> be a target if the dummy has INTENT(IN).  That doesn't say the actual could
>> be a non-poly-target (because 12.5.2.5 says you couldn't).  The actual arg,
>> in this case, could be a poly dummy arg with TARGET attribute or a poly
>> allocatable with a TARGET attribute.
>
> I have to defer to you compiler people whose job it is to deal with this stuff
> day in and day out.   But to me 12.5.2.7p2 is unambiguous in stating that an
> INTENT(IN) polymorphic dummy pointer can be associated with a non-pointer
> actual if it would be a valid target of the pointer.  There's no indication or

Bill Long replied:
>Standards use strict meanings for words like "shall" and "can".  "Can" 
>indicates a capability, and that is the meaning you are using in the above 
>argument.  But the cited part of the standard does not use "can". "Shall" 
>indicates a requirement that has to be satisfied for the program to be 
>standard-conforming.   Obeying all of the "shall" statements is necessary, even 
>if they are not in the same paragraph. So, in fact, Jim's analysis is correct.

I agree that that is what the words in the standard say, but I am sure it is not 
what we intended.  The polymorphism-matching requirement is pointless in the 
pointer/target case.  This certainly bears further investigation.

Cheers,
-- 
................................Malcolm Cohen, Nihon NAG, Tokyo. 

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