D - Unsafe and doomed

[alex burton]

On Tuesday, 7 January 2014 at 11:36:50 UTC, Ola Fosheim Grøstad 
wrote:
> On Tuesday, 7 January 2014 at 11:29:18 UTC, alex burton wrote:
>>>
>>> Hardware exceptions allow for the same thing.
>>
>> I am not sure what you mean by the above.
>
> You can trap the segfault and access a OS-specific data 
> structure which tells you where it happened, then recover if 
> the runtime supports it.

Thanks for this.

I tested the same code on Windows and it appears that you can 
catch exceptions of unknown type using catch with no exception 
variable. The stack is unwound properly and scope(exit) calls 
work as expected etc.

After reading about signal handling in unix and structured 
exception handling on Windows, it sounds possible though 
difficult to implement a similar system on unix to introduce an 
exception by trapping the seg fault signal, reading the data 
structure you mention and then using assembler jump instructions 
to jump into the exception mechanism.

So I take Walters statement to mean that :
hardware exceptions (AKA non software exceptions / SEH on 
windows) fix the problem - where programmers have put catch 
unknown exception statements after their normal catch statements 
in the appropriate places.
And that a seg fault exception should result on linux it just 
happens that it is not yet implmented, which is why we just get 
the signal and crash.