[davemp]

> IMHO the zig footgun story with respect to UB behavior is largely unchanged relative to C/C++

The only major UB from C that zig doesn’t address is use after free afaik. How is that largely unchanged???

Just having an actual strong type system w/o the “billion dollar mistake” is a large change.

[vlovich123]

Depends how you compile it. If you’re compiling ReleaseFast/ReleaseSmall, it’s not very different from C (modulo as you said it has some language features to make it less likely you do it):

* Double free

* Out of bounds array access

* Dereferencing null pointers

* Misaligned pointer dereference

* Accessing uninitialized memory

* Signed integer overflow

* Accessing a union field for which the active tag is something else.

[dnautics]

wow, what a list! all of these are statically analyzable using a slightly hacked zig compiler and a library!

https://github.com/ityonemo/clr

(Btw: you can't null pointer dereference in zig without using the navigation operator which will panic on null; you can't misalign a pointer unless you use @alignCast which will also create a panic)

[vlovich123]

Neat. Why isn’t this in the main compiler / will it be? I’m happy to retract my statement if this becomes actually how zig compiles but it’s not a serious thing as it’s more a PoC of what’s possible today and may break later

[dnautics]

It will never be in the main compiler, since it was written by Claude. I think that's ok. The general concept is sound and won't break (modulo names of instructions changing etc). In fact it will get better. With the new io, concurrency checks will be possible

But also, there is no reason why it should have to be in the main compiler. I've architected it as a dlload plugin. It's even crazier! The output is a zig program which you must compile and run to get the final result.

[pjmlp]

I can also analyse C and C++ code for such issues, while keeping using a mature languages ecosystem.

[dnautics]

If you can statically analyze c for memory safety, why did pazlo bother building fil-C?

[pjmlp]

Where did I wrote that static analysis was enough on its own?

[dnautics]

Can you phrase that as a direct answer to my question? Trying to learn something here. Appreciate it!

[davemp]

This is pretty close to saying Rust is not very different than C because it has the unsafe keyword. That is, either an ignorant (of Zig) or disingenuous statement.

[vlovich123]

To me the zig position is akin to saying that because Asan, TSAn and ubsan exist, c++ is safe because you’re just running optimized for performance.

If you believe I mischaracterized zig, please enlighten me what I got wrong specifically rather than attacking my ad hominem

[davemp]

I’m not going to write a detailed response to something that’s extremely close to what an LLM responds to “what UB does zig have?”

Arguing about whether certain static analysis should be opt in or opt out is just extremely uninteresting. It’s not like folks are auditing the unsafe blocks in their dependencies anyways.

If you want to talk about actual type system issues that’s more interesting.

[vlovich123]

So the Fermat defense? “I have the proof but the margin is too small”.

The proof is in the pudding. TigerBeetle despite having a quite opinionated style still almost hit by UB and basically got lucky it wasn’t a worse failure. By contrast, even though unsafe isn’t audited for all dependencies, it does in practice seem to make UB extremely unlikely. And there’s work ongoing in the ecosystem to create safe abstractions to remove existing unsafe into well tested and centralized things

[pjmlp]

It is worse, because Asan, TSAn and ubsan already have several years of production experience, in a mature ecosystem.

There is no point throwing it all away to get back to the starting line.