On 2/26/13 5:10 PM, Craig Rasmussen wrote:

For some reason Jeff deleted me from this email list :-) (or perhaps I removed myself one day when the mood moved me) so I haven't seen this thread until today.

Basically I agree with Tobias that there is a problem (from a standards perspective) and with Nick that MPI-3 made the right choice with default logical (following past standards as to not break existing code). I also agree with Nick that an implementation of the MPI-3 standard can finesse the issue a bit.

I would note that this problem only exists for these call-back routines where only an interface is specified. For the routines that are actually called and supplied as part of the library, all of these 'type/kind conversion' issues can be resolved with wrappers that could be inlined away.

I don't know what Bill will think of this but I think the problem should be resolved in the Fortran standard in the end so that

LOGICAL(C_INT)

I have a feeling this is not what Nick had in mind. Visually jarring, at a minimum. There is no standard requirement that this is legal, even though in most cases it would as a practical matter. Most implementations will work since C_INT is just a KIND value (often = 4) that is probably legal for LOGICAL since vendors tend to use the same KIND values for LOGICAL and INTEGER of the same storage size. If C_INT is not a legal KIND value for INTEGER in your implementation, you are going to have more problems than just this issue. For an implementation that has C_INT > 0, I would be interested to know if there were ANY for which LOGICAL(C_INT) was not a legal declaration. Default LOGICAL and default INTEGER normally have the same storage size, and since MPI seems to like the idea of default INTEGER being the same as C int (even though that is not always true), it would seem to make just as much sense to leave it as default LOGICAL.

is a legal type. This would allow mapping Fortran logical variables to C integers which is the type most C programmers use for logical variables anyway.

Hence my earlier comment that this might have better been INTEGER in the first place. Too late now.

Does anyone know what size a default logical is in existing compilers?

Usually 32 bits, sometimes 64.

I assume it is the same size as a default integer.

That is a requirement for variables in a "storage association context". Default integer, logical, and real all occupy a "numeric storage unit". Having the storage size for default integer and logical different would be extremely unusual. Cheers, Bill

Craig Rasmussen CAS Scientific Programmer [email protected] <mailto:[email protected]>

On Feb 26, 2013, at 2:05 PM, Rolf Rabenseifner wrote:

...

Is TS 29113 changing something in this case? I.e., does TS 29113 allow LOGICAL dummy arguments in BIND(C) subroutines?

Rolf

----- Original Message -----

...

From: "Jeff Squyres (jsquyres)" <[email protected] <mailto:[email protected]>> To: "<[email protected] <mailto:[email protected]>>" <[email protected] <mailto:[email protected]>>, "MPI-3 Fortran working group" <[email protected] <mailto:[email protected]>> Sent: Tuesday, February 26, 2013 7:04:09 PM Subject: Re: [MPI3 Fortran] [Mpi-comments] MPI 3.0: Fortran 2008 interface - issue with the LOGICAL kind On Feb 26, 2013, at 11:27 AM, Bill Long <[email protected] <mailto:[email protected]>> wrote:

...

In particular, the C function is not using _Bool. It would seem to be more consistent for the Fortran interface to specify the argument as

INTEGER :: FLAG

or, better

INTEGER(c_int) :: FLAG.

FWIW, the MPI Fortran interfaces have always used LOGICAL for boolean values, not INTEGER. It would be weird to change them now.

-- Jeff Squyres [email protected] <mailto:[email protected]> For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/

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