[fpc-pascal] problem with interface (OOP not widget)

[Bee]

Hi all,

I got problem with the code below.

--->8--- begin code --->8---

program test_intf_query;

{$IFDEF FPC}
   {$MODE OBJFPC}{$H+}
{$ENDIF}

uses
   Classes;

type
   TPLFieldType = (plftUnknown, plftString, plftSmallint, plftInteger,
     plftWord, plftBoolean, plftFloat, plftCurrency, plftBCD, plftDate,
     plftTime, plftDateTime, plftBytes, plftVarBytes, plftAutoInc,
     plftBlob, plftMemo, plftGraphic, plftFmtMemo, plftParadoxOle,
     plftDBaseOle, plftTypedBinary, plftCursor, plftFixedChar,
     plftWideString, plftLargeint, plftADT, plftArray, plftReference,
     plftDataSet, plftOraBlob, plftOraClob, plftVariant, plftInterface,
     plftIDispatch, plftGuid, plftTimeStamp, plftFMTBcd,
     plftFixedWideChar, plftWideMemo, plftOraTimeStamp, plftOraInterval);

   ISimple = interface
   ['{24811FF3-4F01-4601-AC5C-22A5B5D46928}']
     function ShowSomething: Integer; cdecl;
     function GetIsBlob: Boolean; cdecl;
   end;

   TSimple = class(TInterfacedObject, ISimple)
   private
     FDataType: TPLFieldType;
   protected
     { ISimple implementation }
     function ShowSomething: Integer; cdecl;
     function GetIsBlob: Boolean; cdecl;
   end;

{ query ISimple }
function QuerySimple(const OnChange: TNotifyEvent = nil): ISimple;
   cdecl;
begin
   Result := TSimple.Create;
end;

{*** TSimple ***}

function TSimple.ShowSomething: Integer; cdecl;
begin
   Writeln('Message from ISimple');
   Result := 0;
end;

function TSimple.GetIsBlob: Boolean; cdecl;
begin
   Result := FDataType in [
             plftBytes, plftVarBytes, plftBlob, plftMemo, plftGraphic,
             plftFmtMemo, plftParadoxOle, plftDBaseOle, plftTypedBinary,
             plftOraClob, plftOraClob, plftWideMemo
             ];
end;

{*** main program ***}

var
   FSimple: ISimple;

begin
   FSimple := QuerySimple(nil);
   //FSimple := TSimple.Create;

   FSimple.ShowSomething;
end.

--->8--- end code --->8---

FPC failed to compile it. The compiler complained with this message:

test_intf_query.pas(56,26) Error: range check error in set constructor 
or duplicate set element

With wonder, I commented line 56. Then the compiler complained with this 
message:

test_intf_query.pas(66,14) Fatal: Internal error 200408162

Weird. So, I commented line 66 and uncommented line 67 (just to make it 
compilable). It compiled fine. But when it's executed, it ended up with 
AV. Here's the output:

bee at simba:~/Programs$ ./test_intf_query
Message from ISimple
An unhandled exception occurred at $0804816C :
EAccessViolation : Access violation
   $0804816C

I'm using FPC 2.2.0, 2.2.1, and 2.3.1 on Ubuntu Gutsy i386. I thought it 
was the problem with FPC for Linux, so I tried it with FPC 2.2.0 on 
Windows (on exact machine). But, same errors persist on all FPC versions. :(

IMHO, the above code (before modifications to make it compilable) should 
be fine. I can't see nothing wrong with it. To make sure, I compiled the 
code using Delphi 7 and Turbo Delphi Explorer. Both Delphi compiled fine 
and the executable output run without problem.

The actual program actually much bigger than the above, it's a part of a 
big framework I've been working on. I cut it and made much simpler to 
isolate the problem. FYI, the framework itself initially written using 
Delphi 7 and works well. Now, I'm trying to port it to FPC.

Hints? TIA.

-Bee-

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http://beeography.wordpress.com