[fpc-pascal] Incompatible type for generics?

[Xiangrong Fang]

Hi All,

I wrote a TTree generic class, the code is here:

https://github.com/xrfang/fpcollection/blob/master/src/units/tree.pas

While using this class, I encountered the following problem:

program project1;
{$mode objfpc}{$H+}
uses tree;
type
  TIntTree = class(specialize TTree<Integer>)
  end;
var
  ti : TIntTree;
begin
  ti := TIntTree.Create(1, nil);
  ti := ti.Next;  <-- error here
end.

The error message is:

Error: Incompatible types: got "TIntTree.TTree$LongInt" expected "TIntTree"

If I do not inherit TTree but just specialize it, there is no error.

How can I solve this problem so that I don' t have to use typecast
everywhere?

Thanks,
Xiangrong
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