[OT] OT: Null checks.

[Timon Gehr]

On 5/7/25 01:34, Walter Bright wrote:
> On 5/5/2025 8:38 PM, Timon Gehr wrote:
>> On 5/6/25 05:31, Timon Gehr wrote:
>>>
>>> I just wish everyone would refrain from actively putting invalid 
>>> instructions and segfaults into druntime in the future. They are not 
>>> _that_ useful and there are vastly more useful alternatives. x)
>>
>> And the same is true for segfault-on-null. I don't want this. If a 
>> standard null check can be implemented taking advantage of CPU 
>> features, fine. But semantics should be the same as if the compiler 
>> inserted a branch that throws an error every time a nullable pointer 
>> is dereferenced.
> 
> That's an awful lot of test and branch code being unnecessarily

I don't really care if it is necessary, it is sufficient. If there is a 
better way to get the same result I am fine with that, but for now it 
would be good to simply have a way to stop the bleeding.

> inserted 
> to test-and-throw instead of segfault-and-throw, because that's what a 
> segfault is - a thrown exception.
> ...

Clearly something distinct is happening that skips the scope cleanup.

> 
>> Even better would be the type system just ensuring nullable pointers 
>> are never dereferenced, the OP's experience report notwithstanding. 
>> But I guess this part is a pipe dream for now.
> 
> Have you tried using a template to achieve that?

No.

a) it's impossible due `.init` being forced on you even if you disable 
default construction

b) I am not going to chase down every pointer in every dependency and 
maintain my custom forks of everything including druntime and Phobos

c) build times would likely skyrocket