[sv-bc] Ambiguity in function prototype parsing

There appears to be a true ambiguity in SV regarding how
to parse function prototypes.  Consider:

   typedef int T;
   module top;
     import "DPI-C" function void test(input T[1:0]);
   endmodule

   class C;
     extern function int test(T[1:0]);
   endclass


I think that per the LRM both of these should be legal.  Note
that for a function prototype, the name of the formal is not
required.  In addition, the type is not required (implicitly
logic).  So, what does "T[1:0]" mean?  Does it define a
formal named "T" with type of unpacked array of logic or does it
define an unnamed formal of type unpacked array of T?

There are several ways to deal with this:
   1) if the identifier is a visible type, require a full type
      and name declaration for the formal
   2) if the identifier is a visible type, treat the declaration
      as an explicitly typed unnamed formal
   3) always treat this as an implicitly typed named formal

I think that I'd like to require either 1 or 2.

There are some parallels to this issue in the port declaration
space, but I believe that they can all be disambiguously
interpreted (although they aren't LALR(1)).  If we do go with
(1), I'd probably like to take another look at the port
declaration rules in order to require full declarations in
any cases that might be surprising to the user.

Gord
-- 
--------------------------------------------------------------------
Gordon Vreugdenhil                                503-685-0808
Model Technology (Mentor Graphics)                gordonv@model.com