Winboard Forum

Hi everyone,

I am trying to use an old trick of mine to catch a bug while running my chess engine under WinBoard 4.4.0. In the past, I have often put the following line of code in a debug build of a C++ program running under Windows, and it triggers a breakpoint on that line that allows me to bring up the debugger (Microsoft Visual Studio):

Code: Select all

__asm int 3;

I also tried this, to no avail...

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#include <assert.h>
// ... blah blah blah
assert(false);


Either of these works great if I run my chess engine directly in a command prompt, but when hosted inside WinBoard, the above line of code just causes my engine to hang and stop responding. When I close WinBoard after that, the dialog box I was expecting all along suddenly appears and just as quickly vanishes. It is like WinBoard is somehow suppressing the debugger interrupt.

All I am trying to do is trap a very rare special case with a breakpoint so I can see the stack trace if/when it happens. It would be fine however I do it, so long as I can run it under WinBoard and not have to type in the correct sequence of WinBoard protocol commands manually.

Any advice would be greatly appreciated. Thanks in advance!

- Don

Does Debug menu->Attach to process work?

Thanks, Teemu, that is exactly what I needed! I knew "Attach to Process" was in there, but had forgotten about it.

For others reading this, after I opened the Debug / Attach To Process dialog box in Microsoft Visual Studio 2008, I had to check the box that enabled debuging "Native" code, otherwise I got an error when I tried to do Debug / Break All that said it wasn't the right kind of executable. Now can use the debugger and set breakpoints while running my engine hosted by WinBoard.

It is only possible under 32-bit compile.
Besides, you have to try it that way:
_asm { int 3 }

intsead of:
__asm int 3;

Plus, you have to set your default debugger before that.