Memory safe in D - cppfront/C++

[Nick Treleaven]

On Tuesday, 16 April 2024 at 18:25:29 UTC, Walter Bright wrote:
> ```
> @safe
> void foo()
> {
>     int* p;
>     {
> 	int x;
> 	p = &x;
>     }
> }
> ```
>
> The compiler gives:
>
> test.d(8): Error: address of variable `x` assigned to `p` with 
> longer lifetime

-dip1000 is good at detecting possible dangling pointers to scope 
data, but it does it when the pointer is assigned. The difference 
with the C++ paper is it only tells you *when you try to 
dereference* a pointer which may point to data which is now 
invalid because the dereference happens in a higher scope. There 
are cases where -dip1000 would give a false positive which are 
still useful that the paper would allow (e.g. involving loops or 
where the pointer is written to later before the dereference, 
overwriting the invalid pointer).

Anyway, I was just trying to describe what the C++ paper is 
supposed to do. My main point was about D detecting uninitialized 
variable use (which is a prerequisite for non-nullable types).