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 <[email protected]>
Date: 17/02/2026 17:05 (GMT+00:00)
To: FPC-Pascal users discussions <[email protected]>
Cc: Adriaan van Os <[email protected]>
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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