[fpc-pascal] Two possible generics bugs

[Ryan Joseph]

> On Nov 28, 2019, at 6:38 PM, Sven Barth via fpc-pascal <fpc-pascal at lists.freepascal.org> wrote:
> 
> TFPGObjectList has a constraint to class types, so you need to constrain your T as well using ": class". 
> 
> Please note however that you'll likely encounter another bug then once you move your function to a unit: https://bugs.freepascal.org/view.php?id=35943

A better error would be nice but I guess I can't do this anyways until the other bug is fixed.


> The "specialize" is part of the generic identifier, so it must be "FGL.specialize TFPGObjectList<T>". 
> 
> That said however an internal error should not happen (especially the one I just added some days ago ^^'). Please report this one. 
> 

That doesn't look right to my eyes but ok. I filed a report (https://bugs.freepascal.org/view.php?id=36377).


It looks like my plan was foiled so I made a non-generic attempt. Can you explain why I get the EListError at runtime? I checked the itemSize property and it's the same for both lists.

{$mode objfpc}

program test;
uses
  FGL;

type
  TNode = class (TInterfacedObject)
  end;
  TNodeObjectList = specialize TFPGInterfacedObjectList<TNode>;

function CopyList (source: TFPSList): TFPSList;
begin
  result := TFPSList(source.ClassType.Create);
  result.Assign(source);
end;

var
  a, b: TNodeObjectList;
begin
  a := TNodeObjectList.Create;
  // EListError: Incompatible item size in source list
  b := CopyList(a) as TNodeObjectList;
end.

Regards,
	Ryan Joseph