How can I get a backtrace when my WndProc throws?

[Markus via Digitalmars-d-learn]

Hi, I'm using core.sys.windows.windows to make a Windows GUI, and 
the WindowProc must be nothrow. My code does not provide me a 
stack backtrace when some exception is thrown in there. I would 
like to have at least the number of the line that caused a throw, 
has anyone an idea how to do this? Thanks for reading.

Below is the code for the Windows application. I guess I need to 
improve window_procedure_nothrow() somehow.

import std;
import core.sys.windows.windows;

HWND main_window;

LRESULT window_procedure(
    HWND hwnd,
    uint msg,
    WPARAM wparam,
    LPARAM lparam)
{
        if(msg == WM_CLOSE)
        {
                PostQuitMessage(0);
                return 0;
        }
        
        if(msg == WM_KEYDOWN)
        {
                format("%d", 0.5); // trigger an exception

                format("%d", 0.7);
        }
        
        return DefWindowProc(hwnd, msg, wparam, lparam);        
}

extern(Windows) LRESULT window_procedure_nothrow(
    HWND hwnd,
    uint msg,
    WPARAM wparam,
    LPARAM lparam) nothrow
{
        // this prints only a line number from within this function
	// and some stack backtrace of functions outside the window 
procedure
        if(0)
        {
		return assumeWontThrow(window_procedure(hwnd, msg, wparam, 
lparam));
        }

        // this prints no line number at all
	// can get only the exception message from 
collectException().msg	
        if(1)
        {
                LRESULT result;
                auto ce = collectException(
                        window_procedure(hwnd, msg, wparam, lparam),
                        result);
                if(ce !is null)
                {
                        assumeWontThrow(writeln(ce.msg));
                        TerminateProcess(GetCurrentProcess(), 0);
                }
                return result;
        }
}

void main()
{
        WNDCLASSEX wndclassex = {
                style: 0,
                lpfnWndProc: &window_procedure_nothrow,
                lpszClassName: "a",
                hInstance: GetModuleHandle(null),
                hIcon: LoadIcon(null, MAKEINTRESOURCE(32517)),
                hCursor: LoadCursor(null, MAKEINTRESOURCE(32512)) };

        ATOM windowclass = RegisterClassEx(&wndclassex);
        assert(windowclass != 0);

        main_window = CreateWindowEx(
                0,
                "a",
                "test",
                WS_OVERLAPPEDWINDOW | WS_VISIBLE,
                100,
                100,
                200,
                200,
                null,
                null,
                GetModuleHandle(null),
                null);
        assert(main_window != null);

        for(;;)
        {
                MSG msg;
                int ret = GetMessage(&msg, null, 0, 0);

                if(ret == 0) break;

                assert(ret != -1);

                TranslateMessage(&msg);
                DispatchMessage(&msg);
        }
}