Re: [patch, openmp/openacc] Allow Fortran parameters in map/copy.

[Andrew Stubbs <ams at codesourcery dot com>]

On 05/07/2019 12:49, Jakub Jelinek wrote:
> On Fri, Jul 05, 2019 at 12:31:17PM +0100, Andrew Stubbs wrote:
> > This patch allows Fortran "parameter" named constants to be named in OpenMP
> > map and OpenACC copy directives.
> >
> > Right now, the compiler just says something like:
> >
> >       !$omp target data map(tofrom:N,x)
> >                                   1
> >    Error: Object 'n' is not a variable at (1)
> >
> > This is technically correct, but is surprising to the user and AFAICT the
> > OpenMP/OpenACC documents don't say you can't name parameters, so I'd like it
> > to be allowed.
>
> I don't think you can do it in OpenMP, I can discuss in the language
> committee, but the definition of variable is:
>
> "A named data storage block, for which the value can be defined and redefined during
> the execution of a program."
>
> so I don't believe Fortran parameters are OpenMP variables.
> Scalar Fortran parameters don't even have any data storage block associated
> with them at all.

Agreed, they are not variables (nor variable), and copying them about is 
entirely pointless (although, if you simply remove the error check GCC 
will happily create storage for 'N' and do the copies).

And yet, this issue has generated a support request from a blocked 
customer, and I'd like to improve their experience.

I could generate a warning, or add a note to the error message, but in 
the interests of portability I thought just doing the right thing would 
be nicer.

Any suggestions?

Andrew