[MPI3 Fortran] Results of recent J3 Fortran meeting

[N.M. Maclaren]

On Oct 21 2010, Bill Long wrote:
>>>
>>> As noted earlier, this is currently an academic issue since the only 
>>> interoperable character is char. ...
>> 
>> You have completely missed the point.  I am not assuming any type other
>> than Fortran default CHARACTER.  There are compilers where you have a
>> options like -ASCII and -UNICODE, which control which character code
>> Fortran uses for its default characters.  I can't offhand remember which,
>> as I wasn't very interested, but I have seen more than one.
>> 
>> So a new type code in the Interoperability specification doesn't help,
>> because the interface type is default CHARACTER in both cases.
>
>We currently interoperate only with C's char type. On the Fortran side, 
>the interoperable declaration is character(kind=c_char).  Fortran's 
>default character kind is irrelevant.  And sizeof(char) is 1. So there 
>is no issue here.

Except for the last sentence, that is true.  But one of MPI's major
requirements is that it should be able to handle Fortran default types,
and NOT force every program to use the C-interoperability KINDs to
call MPI!  Sorry, but there IS an issue.

Regards,
Nick Maclaren.