F03 C interop..

[Tobias Schlüter]

Christopher D. Rickett wrote:
> I have followed this list for a few months now, and I have seen some talk 
> about implemented F03 features.  I am particularly interested in the C 
> interoperability section of F03.  Is there currently anyone working on 
> this?

I don't think so.

> If someone has already begun work on the C interop part of the F03 draft, 
> I would be willing to help them finish what's left.  If no one has 
> started, then I would be willing to start the work myself.

I think this would be very welcome.  Please be sure to read
<http://gcc.gnu.org/contribute.html> before you finish a patch which we then
can't accept due to silly reasons.

>  I am new to 
> making changes to gfortran, so any help someone could give me on where to 
> start, or material to look over to better familiarize myself with the 
> compiler implementation details, it would be greatly appreciated.

There are a number of places to look at, I don't know precisely what the C
interoperability spec encloses, but important information for this work may be
found in the following places:
 - gfc_init_kinds in trans-types.c which creates the mapping between types
available on the target system and Fortran types
 - the comment following line 705 in trans-types.c which details the format of
the array descriptors
 - the rules for mangling of external symbol names are explained in the
documentation, the mangling of module procedures is undocumented AFAIK
 - also, FX Coudert is working on a patch to support the full range of types
available on the target system, the corresponding mailing list thread which
might also be of interest to you, is "[gfortran,ping] support for large kinds
in front-end and library"

Cheers,
- Tobi