NotNull pointers

[Walter Bright]

On 8/31/2011 4:46 AM, Steven Schveighoffer wrote:
> Seg faults are not as useful as asserts. It's a fact.

You might be surprised, then, that I'll often temporarily replace an assert with 
a HLT instruction so I can use a debugger on it :-)


> If you have a seg fault,
> you must reproduce the error while in a debugger, or generate a core dump.
> Reproducing not be possible, or might take considerable time. Any argument
> against this is revisionist history. Yes, if I go back in time and run it in a
> debugger for that execution, it would be useful. Yes, if I go back in time and
> change my shell options to generate a core dump, it would be useful. If you have
> an assert, you get a stack trace, no need to reproduce the assert in a debugger,
> or enable non-default settings in your shell. It just gives you the information
> you need.


It's also possible for the program to have its own seg fault handler that reads 
its own symbolic debug info and generates a line number and stack trace. There 
was a patch to Phobos that did this a while back.

Optlink's register dump on a seg fault is not Windows' doing, it installs a seg 
fault handler which does this.


 > So 4 instructions per assert of a class reference (which is arguably not 
common) is a lot of bloat?

15 bytes. And yes, this stuff adds up surprisingly quickly, especially if you're 
the type that wants to leave the asserts on even in release mode.