(j3.2006) (SC22WG5.3585) OPTIONAL arguments and C interop

[Aleksandar Donev]

Van,

> The TR would specify
> functions or structs to access and create such arguments.
Yes, that is what we do for assumed-shape and other arrays passed by 
descriptors. However, even with that decision, there will be vendors that 
have to change their descriptors to include the required information: rank 
and type info need to be kept since there are functions to read/set those 
fields.

For OPTIONAL, I don't see how one can use a function or a struct to get around 
the fact that some vendor passes 2 arguments instead of 1. So even if we use 
some opaque way to specify what is present and what is not (instead of saying 
NULL is not present and all else is present), we still have to decide the 
number of arguments and their matching between Fortran interfaces and C 
prototypes.

Aleks