Support for forward declarations of generic types

Original Reporter info from Mantis: trx

• Reporter name: Svetozar Belic

Description:

The compiler currently does not support forward declarations of generic types such as:
TTest&LtPos;T> = class; // <- Not allowed.

TTest&LtPos;T> = class
end;

The attached patch file adds support for such declarations.

Additional information:

When a type section is parsed and a forward declaration of a generic type is encountered, a symbol and a definition (with oo_is_forward) is created as usual. Because it has oo_is_forward, this definition is incomplete.
Types which use the incomplete definition will add them self to its used_by list.
At the end of the type section (when the generic type is now parsed), resolve_forward_generic_types is called which goes through all the incomplete forward declarations, generates a specialization and replaces the incomplete definitions (by going through the incomplete definition's used_by list).
After it has been replaced, the incomplete definition is deleted.

If this is a wrong way to go about it, I would be happy if someone could provide some pointers to help me implement this a better way.

Mantis conversion info:

• Mantis ID: 34128
• Monitored by: » Boris (Boris Popov), » Artem3213212 (Artem3213212), » soerensen3 (soerensen3), » projekter (Benjamin Desef), » daniel_sap (Daniel Sapoundjiev), » @avagames (George), » @sergy.larin (Sergey Larin)