[J3] Vector subscripts and INTENT(INOUT)

Malcolm Cohen malcolm at nag-j.co.jp
Tue May 15 20:08:53 EDT 2018

> I did go back and look at old standards.  F2008, in the “Vector 
> subscript” subclause of 6, has “An array section with a vector 
> subscript shall not be argument associated with a dummy array that 
> is defined or redefined.”.    That is the “shall not” rule that 
> supports the factual claim in the argument association clause that 
> the dummy is undefinable.  


Actually, the rule stating that the dummy is undefinable is correct and sufficient.  It is a rule.  Stating that the dummy is not definable ***MAKES IT NOT DEFINABLE***.  It is not an idle observation but normative text!


> I fully support putting the rule back in F2018 draft.


The correct rule is already there: the dummy is not definable.  XL Fortran is reporting a different rule violation, and that separate rule is also still there.


> (Or if there is good reason for dropping it, I would appreciate learning it.)

Yes, it depends on using a time machine.  That’s always a bad idea.


That is, the “shall not be argument associated” rule cannot be applied because its application is at argument association time, but the condition “dummy array is defined or redefined” occurs (or does not occur) in the future.


You won’t be getting any rules that require time travel reinserted into the standard.




..............Malcolm Cohen, NAG Oxford/Tokyo.


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