[fpc-devel] how to get same pthreads code to compile between Linux and FreeBSD

[Sven Barth]

On 03.02.2013 11:51, Graeme Geldenhuys wrote:
> Hi,
>
> I initially posted this in the fpc-pascal list, but I think fpc-devel is
> maybe more appropriate, because the pthreads include files might need
> amendment.

I personally think that the fpc-pascal list was the more approbiate, but 
nevertheless: your problem comes down to this code (in principal):

=== code begin ===


program semtest;

type
   sem_t_rec = record
   end; // from rtl/freebsd/ptypes.inc
   sem_t = ^sem_t_rec; // from rtl/freebsd/ptypes.inc
   psem_t = ^sem_t; // from packages/pthreads/src/pthrbsd.inc

procedure sem_init(sem: psem_t);
begin

end;

procedure sem_init(var sem: sem_t);
begin

end;

var
   s: sem_t;
begin
   sem_init(@s);
end.

=== code end ===

Now the problem is the "@s". This returns type "Pointer" and now you 
have two pointer types: sem_t and psem_t. Thus the compiler can not 
resolve this.

Solution: Typed addresses. Change your call the following way:

=== solution begin ===

begin
   {$push}
   {$typedaddress on}
   sem_init(@s);
   {$pop}
end.

=== solution end ===

In this case the return type of "@s" will be "^sem_t" instead of 
"Pointer" and then the compiler will find the correct method.

Now one might nevertheless ask the question why the compiler considers 
the var variant with an "@s" valid at all? Maybe this is a bug indeed...

Regards,
Sven