When you compile with -L/SUBSYSTEM:WINDOWS you're essentially building an app without a console, so if you want to print out messages you'd have to log them to a file. For example:

-----
import core.sys.windows.windows;
import std.stdio;

extern(Windows) HWND GetConsoleWindow();

void main()
{
    if (!GetConsoleWindow())
    {
        stdout.open(r".\stdout.log", "w");
        stderr.open(r".\stderr.log", "w");
    }

    try
    {
        realMain();
    }
    catch (Throwable thr)
    {
        stderr.writeln(thr.msg);
        throw thr;
    }
}

void realMain()
{
    assert(0);
}
-----

Compilable and runnable with:

dmd -g -L/SUBSYSTEM:WINDOWS:5.01 -run test.d

This will write the exception message to a log file, however I'd also like to retrieve the stack trace to log that as well. For example here's the output in a regular console app (without the windows subsystem):

core.exception.AssertError@test(29): Assertion failure
----------------
0x0041D93B in onAssertError
0x004020DD in void test.realMain() at C:\dev\code\d_code\test.d(30)
0x0040208B in _Dmain at C:\dev\code\d_code\test.d(18)
0x00417BE8 in extern (C) int rt.dmain2._d_run_main(int, char**, extern (C
) int function(char[][])*).void runMain()
0x00417C78 in extern (C) int rt.dmain2._d_run_main(int, char**, extern (C
) int function(char[][])*).void runAll()
0x00417555 in _d_run_main
0x00408690 in main
0x0042DD29 in mainCRTStartup
0x774F33CA in BaseThreadInitThunk
0x77D09ED2 in RtlInitializeExceptionChain
0x77D09EA5 in RtlInitializeExceptionChain

I'd like to log this out when building with a windows subsystem. Is there any way to do that?

On Sun, 18 Aug 2013 16:07:20 +0200
Andrej Mitrovic <andrej.mitrovich@gmail.com> wrote:
>
>     catch (Throwable thr)
>     {
>         stderr.writeln(thr.msg);

stderr.writeln(thr.msg); // No trace
stderr.writeln(thr);     // Includes trace

However, I'm guessing it probably doesn't solve the other problem:

> The
> 'info' field of a Throwable can be converted to a string, so I can
> output this into a log file.
> 
> But, the info field is always null in a module constructor: