(j3.2006) EXTERNAL statement in an INTERFACE body

[Bill Long]

So, you are saying that the function statement in the interface body does not confer the EXTERNAL attribute on EXT1 in the interface body?

For a point of reference, 

> ifort test.f90
test.f90(6): error #6406: Conflicting attributes or multiple declaration of name.   [EXT1]
external ext1
---------^
compilation aborted for test.f90 (code 1)

Cheers,
Bill


On Apr 13, 2016, at 4:07 PM, Van Snyder <Van.Snyder at jpl.nasa.gov> wrote:

> The problem with this analysis is that the EXTERNAL statement is inside
> the interface body, which is a different scoping unit from the one in
> which it is contained.  The interface body confers the EXTERNAL
> attribute within the containing scoping unit, and the EXTERNAL statement
> confers the EXTERNAL attribute within the interface body.  C514 doesn't
> apply.
> 
> I think this needs attention.
> 
> On Wed, 2016-04-13 at 21:02 +0000, Bill Long wrote:
>> We also have this constraint:
>> 
>> 	? C514  An entity shall not be explicitly given any attribute more than once in a scoping unit.
>> 
>> So it is not so clear why the EXTERNAL statement is allowed here, since the interface explicitly gives EXT1 the EXTERNAl attribute. 
>> 
>> "An interface body in a generic or specific interface block specifies the EXTERNAL attribute??
>> 
>> Note 5.13 lists the was to give a name the EXTERNAL attribute:
>> 
>> "The EXTERNAL attribute can be specified in a type declaration statement, by an interface body (12.4.3.2), by an EXTERNAL statement (12.4.3.6), or by a procedure declaration statement (12.4.3.7)."
>> 
>> Cheers,
>> Bill
>> 
>> 
>> On Apr 13, 2016, at 1:53 PM, Daniel C Chen <cdchen at ca.ibm.com> wrote:
>> 
>>> Hello all,
>>> 
>>> Is the following code valid?
>>> 
>>> program main
>>> real ext, inval
>>> interface
>>> function ext1 (y)
>>> real ext1, y
>>> external ext1
>>> end function ext1 ! Duplicate EXTERNAL attribute
>>> end interface
>>> inval = 1.0
>>> print *, ext1(inval)
>>> end program main
>>> 
>>> The EXTERNAL statement is allowed inside an interface body. However, we have a constraint as:
>>> 
>>> [16-007: p118] C542 In an external subprogram, the EXTERNAL attribute shall not be specified for a procedure defined by the subprogram.
>>> 
>>> It only mentions 'external subprogram'. Should it also include interface body to be consistent?
>>> 
>>> Thanks,
>>> 
>>> Daniel
>>> 
>>> XL Fortran Development - IBM Toronto Software Lab
>>> Phone: 905-413-3056 
>>> Tie: 969-3056 
>>> Email: cdchen at ca.ibm.com
>>> http://www.ibm.com/software/awdtools/fortran/xlfortran
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>> 
>> Bill Long                                                                       longb at cray.com
>> Fortran Technical Support  &                                  voice:  651-605-9024
>> Bioinformatics Software Development                     fax:  651-605-9142
>> Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101
>> 
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> 
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Bill Long                                                                       longb at cray.com
Fortran Technical Support  &                                  voice:  651-605-9024
Bioinformatics Software Development                     fax:  651-605-9142
Cray Inc./ Cray Plaza, Suite 210/ 380 Jackson St./ St. Paul, MN 55101