[fpc-pascal]Forward type declaration

[Michael.VanCanneyt at Wisa.be]

On 23 Apr 2003, Johann Glaser wrote:

> Hi!
>
> Currently I'm translating libusb for FPC. Therefore I used "h2pas".
>
> libusb has two types called usb_device and usb_bus. Both are records.
> Each of them has fields, which have ^usb_device and ^usb_bus as types.
> So there is a cross type reference between these two records.
>
> In C they simply build a forward type declaration ("struct usb_device;
> struct usb_bus;"). In FPC unfortunately this is not possible. Is this
> correct?
>
> Are there any plans to add forward type declarations?

You can simply solve this by declaring
  Pusb_device = ^usb_device;
  usb_device = record
    //...
  end;

In fact, using the -P option of h2pas will do this for you.

>
> BTW: h2pas crashes with runtime error 216 when it encounters incomplete
> type definitions like the above mentioned "struct"s. I'm using the
> Debian 1.0.6-1 package of fp-compiler and all other parts.

This is a known problem; h2pas is far from perfect, it is meant to help
people out when translating by doing most of the work. Some things, however
cannot be done.

Michael.