Re: [fpc-pascal] Corba ABI change ?
Well, the good news is that you have a proof that the TObject layout change is the cause of your problem. The bad news is that you either have to live with a non-standard build of the compiler/rtl or update your code. On 19/02/2026 17:52, Adriaan van Os via fpc-pascal wrote: Marc Weustink via fpc-pascal wrote: In our case advanced records are not an option since a large part of the codebase is still used by that old delphi. That will mean that we need to stick to 3.2 With a few changes, I built 3.3.1 trunk without Monitor support (on MacOS), so without the TObject ABI change. It worked fine. Regards, Adriaan van Os ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
Marc Weustink via fpc-pascal wrote: In our case advanced records are not an option since a large part of the codebase is still used by that old delphi. That will mean that we need to stick to 3.2 With a few changes, I built 3.3.1 trunk without Monitor support (on MacOS), so without the TObject ABI change. It worked fine. Regards, Adriaan van Os ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
On 19/02/2026 14:15, Michael Van Canneyt via fpc-pascal wrote: On Thu, 19 Feb 2026, Marc Weustink via fpc-pascal wrote: Pfew.. when you initially wrote your "observations" I didn't realize this issue. In our product, based on old delphi code, an object is used as "record with methods" to interface with various IP based systems. if you are referring to old TP style objects, your code is unaffected. It only applies to Delphi-style objects. sorry for the noise, misread "class" (and I never expected that someone would use class style objects laid over external data) Marc ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
On Thu, 19 Feb 2026, Marc Weustink via fpc-pascal wrote:
On 18/02/2026 10:34, Tony Whyman via fpc-pascal wrote:
Supplementing my point below, I went back and checked my notes. The
TObject layout post 3.2 (in my copy of trunk) is now
TObject = class
{$IFDEF SYSTEM_HAS_FEATURE_MONITOR}
strict private
_MonitorData : Pointer;
private
function SetMonitorData(aData,aCheckOld : Pointer) : Pointer;
inline;
function GetMonitorData: Pointer; inline;
{$ENDIF}
protected
function GetDisposed : Boolean; inline;
Property Disposed : Boolean Read GetDisposed;
public
with everything before "public" having been added. The big change is the
addition of "_MonitorData". This bumps the offset of all later fields up
by sizeof(pointer). If you have code that makes assumptions about the
object layout - and this very much applies to code that tries to import
an object from C++ then your previous assumptions are invalid.
Pfew.. when you initially wrote your "observations" I didn't realize
this issue.
In our product, based on old delphi code, an object is used as "record
with methods" to interface with various IP based systems.
if you are referring to old TP style objects, your code is unaffected.
It only applies to Delphi-style objects.
Michael.___
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Re: [fpc-pascal] Corba ABI change ?
On 18/02/2026 10:34, Tony Whyman via fpc-pascal wrote:
Supplementing my point below, I went back and checked my notes. The
TObject layout post 3.2 (in my copy of trunk) is now
TObject = class
{$IFDEF SYSTEM_HAS_FEATURE_MONITOR}
strict private
_MonitorData : Pointer;
private
function SetMonitorData(aData,aCheckOld : Pointer) : Pointer;
inline;
function GetMonitorData: Pointer; inline;
{$ENDIF}
protected
function GetDisposed : Boolean; inline;
Property Disposed : Boolean Read GetDisposed;
public
with everything before "public" having been added. The big change is the
addition of "_MonitorData". This bumps the offset of all later fields up
by sizeof(pointer). If you have code that makes assumptions about the
object layout - and this very much applies to code that tries to import
an object from C++ then your previous assumptions are invalid.
Pfew.. when you initially wrote your "observations" I didn't realize
this issue.
In our product, based on old delphi code, an object is used as "record
with methods" to interface with various IP based systems. The methods
are used for dissecting packets, endianes conversions, bit fiddling,
flag handling etc.
As long as no virtuals were used, an object hadn't any memory overhead.
The advice I got was that for external interfaces, only the "record"
layout is immutable between versions. In the end, I had to remove all
the Firebird interface code that relied on the assumption that the
Pascal object layout was the same as the C++ and replaced it with
extended records in order to mimimise the impact on code that used the API.
In our case advanced records are not an option since a large part of the
codebase is still used by that old delphi.
That will mean that we need to stick to 3.2
Thanks for warning.
Marc
___
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Re: [fpc-pascal] Corba ABI change ?
SYSTEM_HAS_FEATURE_MONITOR seems to be on by default - I never
explicitly turned it on, so it probably is the default.
Turning SYSTEM_HAS_FEATURE_MONITOR off may be a good way to show that
this is the problem and a short term workaround, but if you are
providing source code that you expect to be widely used then you
probably need to fix the issue with SYSTEM_HAS_FEATURE_MONITOR turned on.
On 18/02/2026 16:25, Adriaan van Os via fpc-pascal wrote:
Tony Whyman via fpc-pascal wrote:
Supplementing my point below, I went back and checked my notes. The
TObject layout post 3.2 (in my copy of trunk) is now
TObject = class
{$IFDEF SYSTEM_HAS_FEATURE_MONITOR}
strict private
_MonitorData : Pointer;
private
function SetMonitorData(aData,aCheckOld : Pointer) :
Pointer; inline;
function GetMonitorData: Pointer; inline;
{$ENDIF}
protected
function GetDisposed : Boolean; inline;
Property Disposed : Boolean Read GetDisposed;
public
with everything before "public" having been added. The big change is
the addition of "_MonitorData". This bumps the offset of all later
fields up by sizeof(pointer). If you have code that makes assumptions
about the object layout - and this very much applies to code that
tries to import an object from C++ then your previous assumptions are
invalid.
Is SYSTEM_HAS_FEATURE_MONITOR defined by default in the build process
? I assume, the compiler can be built without it ?
Regards,
Adriaan van Os ___
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Re: [fpc-pascal] Corba ABI change ?
Tony Whyman via fpc-pascal wrote:
Supplementing my point below, I went back and checked my notes. The
TObject layout post 3.2 (in my copy of trunk) is now
TObject = class
{$IFDEF SYSTEM_HAS_FEATURE_MONITOR}
strict private
_MonitorData : Pointer;
private
function SetMonitorData(aData,aCheckOld : Pointer) : Pointer;
inline;
function GetMonitorData: Pointer; inline;
{$ENDIF}
protected
function GetDisposed : Boolean; inline;
Property Disposed : Boolean Read GetDisposed;
public
with everything before "public" having been added. The big change is the
addition of "_MonitorData". This bumps the offset of all later fields up
by sizeof(pointer). If you have code that makes assumptions about the
object layout - and this very much applies to code that tries to import
an object from C++ then your previous assumptions are invalid.
Is SYSTEM_HAS_FEATURE_MONITOR defined by default in the build process ? I assume, the compiler can
be built without it ?
Regards,
Adriaan van Os
___
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Re: [fpc-pascal] Corba ABI change ?
Tony Whyman via fpc-pascal wrote: Supplementing my point below, I went back and checked my notes. The TObject layout post 3.2 (in my copy of trunk) is now Thanks, this is quite useful. Regards, Adriaan van Os ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
Supplementing my point below, I went back and checked my notes. The
TObject layout post 3.2 (in my copy of trunk) is now
TObject = class
{$IFDEF SYSTEM_HAS_FEATURE_MONITOR}
strict private
_MonitorData : Pointer;
private
function SetMonitorData(aData,aCheckOld : Pointer) : Pointer;
inline;
function GetMonitorData: Pointer; inline;
{$ENDIF}
protected
function GetDisposed : Boolean; inline;
Property Disposed : Boolean Read GetDisposed;
public
with everything before "public" having been added. The big change is the
addition of "_MonitorData". This bumps the offset of all later fields up
by sizeof(pointer). If you have code that makes assumptions about the
object layout - and this very much applies to code that tries to import
an object from C++ then your previous assumptions are invalid.
The advice I got was that for external interfaces, only the "record"
layout is immutable between versions. In the end, I had to remove all
the Firebird interface code that relied on the assumption that the
Pascal object layout was the same as the C++ and replaced it with
extended records in order to mimimise the impact on code that used the API.
There's more information about the changes to my code on github
https://github.com/MWASoftware/fbintf/tree/main/client/3.0/firebird
On 18/02/2026 08:39, Tony Whyman via fpc-pascal wrote:
The object layout has changed post 3.2 with the addition of an
extra field. This breaks any code that makes assumptions about
this. I had a problem with the Firebird OO API due to this change
(also interfacing to C++), and had to rewrite the Firebird/IBX
interface moving away from OO to extended records.
Original message
From: Adriaan van Os via fpc-pascal
Date: 17/02/2026 17:05 (GMT+00:00)
To: FPC-Pascal users discussions
Cc: Adriaan van Os
Subject: [fpc-pascal] Corba ABI change ?
Has there been an ABI change in the trunk compiler (compared to
fpc-3.2.4-rc1) for CORBA interfaces
? Maybe related to "Unicode"-strings ? I have some C++ interfacing
code that works fine with
fpc-3.2.4-rc1 but crashes with the trunk compiler.
Any hints are appreciated.
Regards,
Adriaan van Os
___
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Re: [fpc-pascal] Corba ABI change ?
The object layout has changed post 3.2 with the addition of an extra field. This breaks any code that makes assumptions about this. I had a problem with the Firebird OO API due to this change (also interfacing to C++), and had to rewrite the Firebird/IBX interface moving away from OO to extended records. Original message From: Adriaan van Os via fpc-pascal Date: 17/02/2026 17:05 (GMT+00:00) To: FPC-Pascal users discussions Cc: Adriaan van Os Subject: [fpc-pascal] Corba ABI change ? Has there been an ABI change in the trunk compiler (compared to fpc-3.2.4-rc1) for CORBA interfaces ? Maybe related to "Unicode"-strings ? I have some C++ interfacing code that works fine with fpc-3.2.4-rc1 but crashes with the trunk compiler.Any hints are appreciated.Regards,Adriaan van Os___fpc-pascal maillist - [email protected]://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
On Wed, 18 Feb 2026, Adriaan van Os via fpc-pascal wrote: Marco van de Voort via fpc-pascal wrote: Op 17-2-2026 om 17:56 schreef Adriaan van Os via fpc-pascal: Has there been an ABI change in the trunk compiler (compared to fpc-3.2.4-rc1) for CORBA interfaces ? Maybe related to "Unicode"-strings ? I have some C++ interfacing code that works fine with fpc-3.2.4-rc1 but crashes with the trunk compiler. Please explain what you mean by "C++ interfacing code" ? Michael. ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
Marco van de Voort via fpc-pascal wrote: Op 17-2-2026 om 17:56 schreef Adriaan van Os via fpc-pascal: Has there been an ABI change in the trunk compiler (compared to fpc-3.2.4-rc1) for CORBA interfaces ? Maybe related to "Unicode"-strings ? I have some C++ interfacing code that works fine with fpc-3.2.4-rc1 but crashes with the trunk compiler. Any hints are appreciated. Do you really only use the interface, or do you implicitely also use TObject methods or datastructures other than the pure interface? Afaik Tobject got some methods added for D2009+ compatibility. I see two new inline procedures, TObject.DisposeOf and TObject.CheckDisposed. I wouldn't expect them to change the size of the vmt, or do they ? Regards, Adriaan van Os ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
Re: [fpc-pascal] Corba ABI change ?
Op 17-2-2026 om 17:56 schreef Adriaan van Os via fpc-pascal: Has there been an ABI change in the trunk compiler (compared to fpc-3.2.4-rc1) for CORBA interfaces ? Maybe related to "Unicode"-strings ? I have some C++ interfacing code that works fine with fpc-3.2.4-rc1 but crashes with the trunk compiler. Any hints are appreciated. Do you really only use the interface, or do you implicitely also use TObject methods or datastructures other than the pure interface? Afaik Tobject got some methods added for D2009+ compatibility. ___ fpc-pascal maillist - [email protected] https://lists.freepascal.org/cgi-bin/mailman/listinfo/fpc-pascal
