[fpc-pascal]Memory leak in freepascal, FreeAndNil not working properly?

[Andreas Gros]

Hi folks,

please check out this code (unit). Certainly there is something very strange 
going on in handling memory in freepascal. I'm using Free Pascal Compiler 
version 1.9.4 [2004/05/30] for i386.

Thanks in advance for replying.

Andreas

{ snip%<************************************************************************
   Pascal unit: testObject
   Author: Andreas Gros <andreas.gros at biozentrum dot uni-wuerzburg dot de>
}

unit testObject;

interface
uses
  SysUtils, Types, Classes, Variants;
	
procedure test();

type 	TTestObj = class(TObject)
				public
				Findex : Integer;
				constructor Create(_index : Integer); 
			end;

implementation

constructor TTestObj.Create(_index : Integer); 
	begin
	Findex := _index;
	end;
	
	
procedure test();
	var list : TList;
			i : Integer;
			t : TTestObj;
	begin
	list := TList.Create();
	//create 6 TTestObj-ects with ascending indices
	for i := 0 to 5 do
		begin
		list.add(TTestObj.Create(i));
		end;
	
	t := TTestObj(list.first());
	//writes 0 to stdout
	writeln(t.Findex);
	FreeAndNil(t);
	list.pack();
	t := TTestObj(list.first());
	{the next line should write 1 to stdout, because the first object was freed, 		
	 but the result is 0!!!
	 it is still the old index, the object is still existing and FreeAndNil as 
	well as TList.pack have no effect}
	writeln(t.Findex);
	
	{ but now the crux: you can't say free again:
	   an access violation error message turns up}
	FreeAndNil(t);
	
	end;

end.

{ snip%<************************************************************************}
testobj.pp:
{ snip%<************************************************************************}
program main;
uses testObject in 'testObject.pas';

begin
 test();    

end.
{ snip%<************************************************************************}

-- 
Andreas Gros
Forschungsstation Fabrikschleichach
Uni Wuerzburg
Glashuettenstr. 5
96181 Rauhenebrach