Function Calls vs ArrayAccessors vs Type Constructors

[sergisiso]

When we don't have the type of a symbol, it is ambiguous what the expression below is:

subroutine test()
   use other_module
   a = myimportedysymbol(1)
end subrotuine

Currently we often default to ArrayAccessor, but this is unsafe for GPU offloading as array accessors are pure/available on the device, but this is not the case for the other 2 cases where this needs to be checked. For this reason, we have a NEMO_FUNCTIONS in utils.py which is often outdated or broken for untested branches.

In such cases we should make "myimportedysymbol" a CodeBlock, or at least a Call. This will have a significant impact on the GPU offloading performance of NEMO but I think it is necessary for getting people going with correct results and we can get it back the performance by more precise use of the "resolve_imports" functionality.

There is a similar issue in stfc/fparser#384 , but it can be resolved there or in the Fparser2Reader.