C is not only better for performance, but also because you simply can not do some things in most other languages. Rust lacks bitfields, for one. But the bigger thing are pointers. AFAIK you can not do type punning in rust, and i don't know if you can do other pointer plays. (note that pointers are barely even mentioned in this blog post)

IMO rust is a replacement for C++, not for C. C is much closer to assembly then most all other languages, especially those that deal with memory allocation natively.

https://crates.io/crates/bitflags

Rust's raw pointers have equivalent power to C's pointers.

>https://crates.io/crates/bitflags

Not native, see C.

>Rust's raw pointers have equivalent power to C's pointers.

Again, AFAIK you can't do type punning.

That wasn't even my point, that was that C gives you almost everything a cpu does and not much more.

What does "native" mean, built into the language? Why does it matter?

I suspect it's the same with type punning (though also, to some degree because we're still working out the details of what exactly the semantics of unsafe are.) In the end, you can always cast stuff to bytes and then cast those bytes to something else.

I don't take (too much) objection to that, and little with "not much more", but that doesn't mean that C has some secret stuff that only C can do, which it feels like you're implying.

>What does "native" mean, built into the language? Why does it matter?

I don't know how that macro works, but in kernel C bitfields are used in structs that map to device registers (that are mapped to memory).

>I suspect it's the same with type punning (though also, to some degree because we're still working out the details of what exactly the semantics of unsafe are.) In the end, you can always cast stuff to bytes and then cast those bytes to something else.

So if i want to store a series of things with random (length) types in a single array, i can ? Sounds like i can, even though you explained the simpler case.

>I don't take (too much) objection to that, and little with "not much more", but that doesn't mean that C has some secret stuff that only C can do, which it feels like you're implying.

And for the third (edit:second) time, that is not my point. Thing is that C does not have "secret stuff" and rust does. In C you get what you wrote, and not much more. There is no need for telling the compiler to not do some checking or to not make a copy of something. (edit2: granted, bitfields are not native to cpus as type punning is)

Rust, IMO, is more for the C++ crowd then C. And those two are very different.

In C you get what you wrote, and not much more

This is really not the case, not with modern C compilers. You may find calls to functions from the standard library to be converted in surprising ways, while touching undefined behaviour can eliminate evaluations, branches, function calls and more. Your mental model might have a close resemblance to assembly; but compilers don't see it like that any more.

>You may find calls to functions from the standard library to be converted in surprising ways, while touching undefined behavior can eliminate evaluations, branches, function calls and more.

Yes, things like memcpy and printf are (in most cases) built-in in compilers. Not surprising really.

Undefined behavioral is bad programming, if your ask me. Almost all examples of it, that i ran across, are in really ugly code that only a "smart" programmer would write.

Clangs static analyzer points out undefined behavior, and gcc is close to getting a "-Wundefined" flag that points that out at compile time.

A optimizing C compiler can change the resulting code even more then just doing dead code elimination. But the point still stands, that C maps well to assembly and that languages that do things like their own memory allocation are not even comparable to what the cpu provides (only automatic memory allocation that a cpu somewhat provides is the stack, and C exposes even that).

Deterministically locating all undefined behavior is undecidable. Static analyzers can only locate a subset of it.

Commonly-used type punning techniques frequently exhibit undefined behavior due to strict aliasing: https://blog.regehr.org/archives/1307 .

It might be true but barely matters when we have tools like KCC. It's built on an executable semantics of C that runs in a framework on top of Maude rewrite engine.

http://www.kframework.org/index.php/Main_Page

https://github.com/kframework/c-semantics

http://fsl.cs.illinois.edu/FSL/papers/2015/hathhorn-ellison-...