Memory safe in D

[Walter Bright]

On 3/11/2024 4:01 AM, Alex wrote:
> Yes, I got it about compiler, static analyzer can't detect such potential issue 
> for now.

It cannot do it in the general case, that would be the halting problem.

> The instance of class `A` is initialized by default initializer - correct?.

`A a;` will default initialize `a` to `null`.

`A a = new A();` will allocate an instance of `A` where each field is default 
initialized, and assign the result to `a`.

> But what about variable `a`?

`a` is default initialized to `null`.

> Is it initialized by null or contains reference to the instance initialized by 
> default initializer?

`null`

> What happend when I tried to call method `run()` of `a` in runtime?

`a` is passed as the `this` pointer to the method `run()`. Hence, in this case, 
`this` will be null. If you attempt to dereference `this`, it will seg fault.

> I see that application was abnormal termination because `writeln("Hello, 
> world!");` was not called.
> But I don't see any information in console about it (backtrace or something else).

To get a backtrace on Windows, run it in the VC debugger.

> Is it uncatched excpetion? But I have tried to catch it - not work.

D's exception catchers do not catch Windows system exceptions for 64 bit code. 
Microsoft has not seen fit to document their 64 bit EH system.