(j3.2006) Change from Fortran 2003 to Fortran 2008

[Bill Long]

On 5/18/12 3:14 AM, Robert Corbett wrote:
> The change in the definition of variables in Fortran 2008
> appears to cause a semantic difference. Consider the
> program
>
> FUNCTION F(P)
> POINTER F, P
> F => P
> END
>
> PROGRAM ASSOC
> TARGET X
> POINTER P
> INTERFACE
> FUNCTION F(P)
> POINTER F, P
> END FUNCTION
> END INTERFACE
> X = 1.0
> ASSOCIATE(Y => F(P))
> X = 2.0
> PRINT *, X, Y
> END ASSOCIATE
> END

I'm not seeing the connection between X and either Y or P.  It looks 
like Y is a pointer with undefined association status at the beginning 
of the associate construct, and nothing later changes that fact. 
Printing it is dodgy at best.  Did you mean to have

P => X

before the ASSOCIATE construct? If I add that in, I see

2.0  2.0

as the output.  Since Y is pointer associated with X, is that not what 
you expect?

Cheers,
Bill

>
> In Fortran 2003, the selector in the ASSOCIATE statement is
> not a variable, and so the assignment to X does not affect
> the value of Y. In Fortran 2008, the selector is a variable,
> and so the assignment to X should change the value of Y.
>
> Robert Corbett
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> J3 at j3-fortran.org
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-- 
Bill Long                                           longb at cray.com
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