(j3.2006) question about multiple duplicate local identifiers in Fortran 2003

[Bill Long]

Michael Ingrassia wrote:
> The program
>
> INTERFACE T
>   FUNCTION F(J)
>   END FUNCTION
> END INTERFACE
>
> TYPE T
>   INTEGER :: I
> END TYPE T
>
> EXTERNAL F
> PRINT *, F(T(17))
> END
>   

Two errors will might prevent this from compiling independent of the 
question below. The EXTERNAL F should not be there since F is already 
defined in an explicit interface above.  Also, the reference F(T(17)) 
has the wrong type argument, independent of which interpretation of 
T(17) you prefer (either type REAL in the function case, or TYPE(T) in 
the constructor case - neither is integer which is the argument type for F).

> uses the name T as both a generic name and as the name of a derived type.
> Constraint C489 [04-007:63:39] rules out the syntax T(17) as a valid
> structure constructor.  

One could argue that T(17) directly violates C489.  However, if that's 
the case, then what is the point of Note 4.56 which says, basically, 
that if the reference appears to be ambiguous, then the function 
reference wins.  Based on user feedback on OOPS stuff, users really want 
the capability to "override" a structure constructor with their own 
function, and hence want the capability implied by the Note.

So, to be specific, (after fixing the interface), if this definition of 
F is added:

integer function f(k)
f = k*2
end

then would the program print out 68?   I think that's what the users want.

Cheers,
Bill


> But I don't see a prohibition against the syntax
> T(17) as a generic function reference, in which case the PRINT statement has an
> unambiguous interpretation.   Was it intended that the program be
> standard-conforming?
>
> 	--Michael I.
>
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-- 
Bill Long                                   longb at cray.com
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