Hello,

I'm trying to port a Delphi code to FPC, and it has a structure like:

  TType = class(TObject)
  end;
  TTest<T1; T2: TType> = class(TObject)
  end;
  TFoo = class(TType)
  end;
  TBar = class(TTest<string, TFoo>)
  end;

I.e., T1 accepts any type, but T2 accepts _only_ TType and/or their descendants.

I tried the following code in FPC:

  TType = class(TObject)
  end;
  generic TTest<T1; T2: TType> = class(TObject)
  end;
  TFoo = class(TType)
  end;
  TBar = class(specialize TTest<string, TFoo>)
  end;

But:

===
Compile Project, Target: project1.exe: Exit code 1, Errors: 2 Unit1.pas(30,34) Error: class type expected, but got "AnsiString" Unit1.pas(30,47) Error: class type expected, but got "<erroneous type>" ===

If I declare "T2" instead of "T2: TType", it compiles, but using this declaration, a programmer can use accidentally a non descendant type of TType.

Is there an issue about this in bugtracker?

Thank you!

Looks like a bug. Please report.

As a workaround you can move the constraint to the first type instead of the second and specialize with "<TFoo, string>".

Regards,
Sven

Done:

http://bugs.freepascal.org/view.php?id=27424

As a workaround you can move the constraint to the first type instead of the second and specialize with "<TFoo, string>".

I'll try it.

Thank you! (y)

Regards,

Sven