un-catched segfault exception

[Hxal]

Christopher Wright Wrote:
> What you can do, though, is convert a signal to an exception. It's going 
> to be a lot slower than just checking a pointer to see if it's null, but 
> if you have traced exceptions, the debugging benefit is enormous. 
> Someone else probably has a cleaner version, but here's something that I 
> cooked up a couple weeks back. Tested on Linux, dmd1.023-ish; not 
> guaranteed to work for you. It might destroy your computer, kill your 
> firstborn, raise Cthulhu from the depths, overwrite your doctoral thesis 
> with dancing hamsters, et cetera.

I have played with throwing exceptions out of signal handlers and
it's not going to work in a reliable way at all, on Linux at least.
The compiler doesn't generate exception handling frames for blocks
of code it doesn't expect to throw an exception, and it doesn't
expect single instructions to do so. AFAIK this is true for both
dmd and gdc. When you throw an exception and the stack unwinding
procedure doesn't find an EH frame, it will abort your application.
gcc has two switches to remedy this: -fnon-call-exceptions that
expects exceptions to be thrown from dereferences and arithmetics;
and -fasynchronous-unwind-tables that generates EH frames
encompassing all instructions. Alas gdc doesn't support these.

I've played with this a bit in my own stacktracing module
(which you can find at http://zygfryd.net/jive/).
The same disclaimer applies.

PS. Throwing exceptions across C code aborts too, you can however
add one of the previously mentioned flags when compiling C code.