(j3.2006) badly worded semantics for the IMPORT statement

[Robert Corbett]

Bill Long wrote:
> I think this is what was meant: If you have an entity that satisfies two 
> conditions:
> 
> 1) it is available in an interface by being imported, and
> 2) it is defined in the host scoping unit,
> 
> then it is also required to be explicitly declared prior to the 
> interface body.   This makes sense in the case of a named constant, 
> which is a common thing to be imported.  It does seem to be defective in 
> the case of a type name, which is the other common case,  A type is 
> defined, but never "declared", so I'd argue that the "declared" is the 
> faulty part of the sentence.  A less common case would be to import the 
> name of a variable which is not initialized.  It could be used as the 
> argument to a KIND() reference as part of a declaration in the 
> interface, for example. The current wording does not require that this 
> variable be declared before the interface (the sentence does not apply), 
> whereas your suggested change would impose this requirement.  It think 
> such a change would require an interp.
> 
> I'd note that essentially the same statement appears twice, at [260:4-5] 
> and [260:11-12], but with different sentence structure.  My wording 
> above follows more closely the second sentence in the standard.  Maybe 
> it would be clearer, and more consistent, to use the same sentence form 
> in both places.
> 
> Cheers,
> Bill
> 
> 
> Robert Corbett wrote:
> 
>>Someone here at Sun recently asked why it made a difference whether
>>a variable named in an IMPORT statement was assigned a value.  He
>>pointed out that Section 12.3.2.1 of the Fortran 2003 standard states
>>
>>      An entity that is imported in this manner and is defined
>>                                                       ^^^^^^^
>>      in the host scoping unit shall be explicitly declared
>>      prior to the interface body.
>>
>>Perhaps it would be better to say "declared" instead of "defined."
>>
>>Bob Corbett
>>_______________________________________________
>>J3 mailing list
>>J3 at j3-fortran.org
>>http://j3-fortran.org/mailman/listinfo/j3

Consider the module

       MODULE MOD
         INTERFACE
           SUBROUTINE SUBR(A)
             IMPORT
             DIMENSION A(N)
           END SUBROUTINE
         END INTERFACE
         INTEGER, PARAMETER :: I = BIT_SIZE(N)
       END MODULE

Applying the definition of "definition" given in Section 2.5.5
literally,  this module is standard conforming unless the module
variable N is assigned a value.  That is clearly not what was
intended, but it is what the standard says.  I would prefer for
the standard to say what it means and means what it says.

Bob Corbett