[OT] - C++ exceptions are becoming more and more problematic

[Paulo Pinto]

On Wednesday, 23 February 2022 at 18:27:45 UTC, deadalnix wrote:
> On Wednesday, 23 February 2022 at 14:26:41 UTC, matheus wrote:
>> Just saw this today:
>>
>> http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2544r0.html
>>
>> Seems relevant to any System Language like D that features 
>> Exceptions.
>>
>> Matheus.
>
> This is an interesting paper, but I'm not sure where they are 
> going with it.
>
> Exception are expensive. They need to be used to handle 
> unexpected things. That's kind of in the name. Things that 
> happen often are not exceptional.
>
> Pretty much all workaround they look at incur some performance 
> penalty on the happy path, but this is not a bug, this is a 
> feature. Exceptions are very cheap when not thrown, very 
> expensive when thrown. This is what you want when handling a 
> situation that is exceptional.
>
> The perf they measure for std::expect would be worth 
> investigating. Why is it slow?

They aren't going anywhere, most of Herb's latest papers seem 
like ideas how the language could be improved upon, but beyond 
the original paper, presentation at CppCon and eventually some 
prototype available on Compiler Explorer, little more has 
happened.

I might be wrong here, but from C++ mailings it is clear nothing 
is happening with those papers.

Also in regards to exceptions, Bjarne has a paper where he 
criticizes the current compiler implementations for leaving 
performance improvements on the table by not wanting to break 
existing ABIs, while arguing against Herb's approach.

"C++ exceptions and alternatives"

http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1947r0.pdf