Bug: Advanced records as members of a static array are not initialised
lazarus / 64-FPC development

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Nitorami · 2025-10-09 10:08

FPC seems to have problems with managed records within static
structures. I reported a similar issue two years ago, advanced records
within old style objects not being initialised,
https://gitlab.com/freepascal.org/fpc/source/-/issues/40199.

Now I experienced the same for advanced records as members of a global
static array. They are finalised, but not initialised. Can someone
please check and confirm, then I'll issue a bug report. Tested with
fpc 3.2.2. and 3.2.4-rc1 for 32 bit under windows 10.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i {$APPTYPE
CONSOLE}{$MODE OBJFPC}{$MODESWITCH ADVANCEDRECORDS} type  TFoo=
record        state: word;        procedure SetState (n: word);      
class operator Initialize (var R: TFoo);        class operator
Finalize (var R: TFoo);      end; class operator TFoo.Initialize (var
R: TFoo);begin  R.state := 0;  writeln ('TFoo initialized at address
',ptruint (@R.state));end; class operator TFoo.Finalize (var R:
TFoo);begin  writeln ('TFoo finalized, address ',ptruint
(@R.state));end; procedure TFoo.SetState (n: word);begin  state :=
n;end; var Foo1: TFoo;    AllFoo: array[0..5] of TFoo;    i:
integer; begin  Foo1.SetState(i);  //Foo1 is initialised and finalised
correctly  for i := 0 to 5 do AllFoo[i].SetState(i); //these are only
finalised but never initialised !!!!end.

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Zvoni · 2025-10-09 12:51

Cannot confirm.
FPC/Lazarus Fixes 64-Bit on Win10 64Bit
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i program
Project1;{$APPTYPE CONSOLE}{$MODE OBJFPC}{$MODESWITCH
ADVANCEDRECORDS} type  TFoo= record        state: word;       
procedure SetState (n: word);        class operator Initialize (var R:
TFoo);        class operator Finalize (var R: TFoo);      end; class
operator TFoo.Initialize (var R: TFoo);begin  R.state := 0;  writeln
('TFoo initialized at address ',ptruint (@R.state));end; class
operator TFoo.Finalize (var R: TFoo);begin  writeln ('TFoo finalized,
address ',ptruint (@R.state));end; procedure TFoo.SetState (n:
word);begin  state := n;end; Procedure TestMe;var Foo1: TFoo;   
AllFoo: array[0..5] of TFoo;    i: integer;begin  Foo1.SetState(i); 
for i := 0 to 5 do AllFoo[i].SetState(i); end; Begin  TestMe; 
Readln;End.
Returns
QuoteTFoo initialized at address 20971052
TFoo initialized at address 20971040
TFoo initialized at address 20971042
TFoo initialized at address 20971044
TFoo initialized at address 20971046
TFoo initialized at address 20971048
TFoo initialized at address 20971050
TFoo finalized, address 20971052
TFoo finalized, address 20971040
TFoo finalized, address 20971042
TFoo finalized, address 20971044
TFoo finalized, address 20971046
TFoo finalized, address 20971048
TFoo finalized, address 209710507 x Initialize, 7 x Finalize

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Thaddy · 2025-10-09 13:18

I can reproduce it in trunk from today win11/64 and Ubuntu 24/64
Code: Text  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i TFoo
initialized at address 4416784TFoo finalized, address 4416784TFoo
finalized, address 4416800TFoo finalized, address 4416802TFoo
finalized, address 4416804TFoo finalized, address 4416806TFoo
finalized, address 4416808TFoo finalized, address 4416810
(This may well be the cause that one of my own projects failed too)

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Nitorami · 2025-10-09 13:22

Thank you. May we conclude that this is fixed in the fixes branch but
not in trunk ? Shall I issue a bug report then ?

O wait - Zvoni, you have modified the test program and packed the
array into a procedure. That works correctly, but NOT if the array is
global. Please repeat test with the original code.

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Thaddy · 2025-10-09 13:23

This is certainly not fixed in fixes. Just tested.(not RC1, fixes)
Also: globals also need initialization so it is definitely a bug (for
global containers like a fixed array)
And the bug is platform and OS independent . Same on AARCH64/linux

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Thaddy · 2025-10-09 14:42

Wait with the report: there is a commit in trunk from 4 hours ago that
is related.
Now building.
Related, but did not help.

What did help: the compiler warns that allfoo is not initialized.
When I did that manually:   initialize(allfoo); it works, but should
not be necessary.