Hello,

I'm trying to turn off application exception capturing (so I can send exception traces via HTTP in bug reports):

1) In (the first loaded unit of) a console app, I did override ExceptProc (see code at bottom) - my own handler is called (as expected) on a EDivByZero exception.

2) In my Lazarus LCL app (SVN 23483M, LCL/Win32/i386, fpc 2.4.0), I did the same like in the console app - additionally, I did set Application.CaptureExceptions to 'false':

  Application.Initialize;
  Application.CreateForm(TForm1, Form1);
  application.CaptureExceptions:=false;
  Application.Run;

Now, when a EDivByZero is raised, my own handler is *not* called - instead the default TApplication.HandleException is called - To my surprise...
a) When raised before Application.Run, my own handler is called (as it should).
b) When I debug Application.Run, it correctly uses the case without exception handling(!) - that is, it correctly detects the CaptureExceptions change.
c) When I read ExceptProc right before the exception, it correctly has the value of my own handler(!)

Though, my own handler is never called within Application.Run - and I have no idea why...

Any help or ideas are welcome!

Thanks,
Alexander

---------------Console output------------------------

install
application.CaptureExceptions=0
TApplication.HandleException Division by zero
Stack trace:
$00420413 CRASHME, line 39 of unit1.pas
$0042047A TFORM1__BUTTONCRASHMECLICK, line 46 of unit1.pas $004C6234 TCONTROL__CLICK, line 2294 of ./include/control.inc $004FA26F TBUTTONCONTROL__CLICK, line 72 of ./include/buttoncontrol.inc $004FA745 TCUSTOMBUTTON__CLICK, line 164 of ./include/buttons.inc $004FACA1 TBUTTON__CLICK, line 331 of ./include/buttons.inc $004FA10A TBUTTONCONTROL__WMDEFAULTCLICKED, line 26 of ./include/buttoncontrol.inc
$0040A84A
$004BCE72 TWINCONTROL__WNDPROC, line 5102 of ./include/wincontrol.inc $0050FCC7 DELIVERMESSAGE, line 111 of lclmessageglue.pas $004DB6B0 WINDOWPROC, line 2621 of win32callback.inc $77D18709
$77D187EB
$77D1B743
$77D1B7AB
$773C6FF6
$773C70D8

-----------My exception handler---------------------

procedure MyExceptionHandler(
  Obj : TObject;       // ExceptObject
  Addr: Pointer;       // ExceptAddr
  FrameCount: Longint; // ExceptFrameCount
  Frames: PPointer     // ExceptFrames
);
begin
  writeln('MyExceptionHandler');
  ShowException(obj, addr);
end;
initialization
  writeln('install');
  exceptproc := @MyExceptionHandler;

I'm answering my own question since I got it solved now by setting an ExceptionHandler using Application.AddOnExceptionHandler:

    application.AddOnExceptionHandler(@MyExceptionHandler);

This will capture exceptions, however a stack trace with line numbers won't work yet because the default handler is still called and will output a stack trace with line info, but the 'lineinfo' procedure cannot generate a 2nd, 3rd etc. stack trace with line info (for some unknown reason).

The default handlers can be disabled setting a flag:

Application.Flags=[AppNoExceptionMessages]

That did the trick. Then the stack trace is available with line info for at least one time!

Cheers,
Alexander

Alexander Grau pisze:

Bug in lineinfo processing. I posted a patch long time ago but it seems nobody is interested.Now it would require also to fix dwarf lineinfo.

Boguslaw

2010/2/17 Bogus?aw Brandys :

Is there a mantis entry for this? If not please create it or send the patch again (so I create it).
Many thanks.

-Fl?vio

Fl?vio Etrusco pisze:

http://bugs.freepascal.org/view.php?id=13518

It maybe now obsolete though.I'm not conversant with current svn changes.

Boguslaw

So, there is no way to get debug information to handle by the app (self) ? Maybe some kind capture of the output