STL VS gcc

Again, they are barely functional.

MSVC chokes on many standard-defined constructs: https://github.com/microsoft/STL/issues/1694

clang does not claim to be "mostly usable" at all - most papers are not implemented: https://clang.llvm.org/cxx_status.html#cxx20

And gcc will only start ot be usable with CMake when version 14 is released - that has not happened yet.

And, as I mentioned before, IDE support is either buggy (Visual Studio) or non-existing (any other IDE/OS). So you're off to writing in a text editor and hoping your compiler works to a somewhat usable degree. Yes, at some point people should start using modules, I agree, but to advise library maintainers to ship modularized code... the tooling just isn't there yet.

I mean, the GitHub issue is Microsoft trying to ship their standard library modularized, they employ some of the most capable folks on the planet and pay them big money to get that done, while metaphorically sitting next to the Microsoft compiler devs, and they barely, barely get it done (with bugs, as they themselves mention). This is too much for most other library maintainers.

Notice that there are in practice three distinct implementations of the C++ standard library. They're all awful to read though, here's Microsoft's std::vector https://github.com/microsoft/STL/blob/main/stl/inc/vector

However you're being slightly unfair because Rust's Vec is just defined (opaquely) as a RawVec plus a length value, so let's link RawVec, https://doc.rust-lang.org/src/alloc/raw_vec.rs.html -- RawVec is the part responsible for the messy problem of how to actually implement the growable array type.

Still, the existence of three C++ libraries with slightly different (or sometimes hugely different) quality of implementation means good C++ code can't depend on much beyond what the ISO document promises, and yet it must guard against the nonsense inflicted by all three and by lacks of the larger language. In particular everything must use the reserved prefix so that it's not smashed inadvertently by a macro, and lots of weird C++ idioms that preserve performance by sacrificing clarity of implementation are needed, even where you'd ordinarily sacrifice to get the development throughput win of everybody know what's going on. For example you'll see a lot of "pair" types bought into existence which are there to squirrel away a ZST that in C++ can't exist, using the Empty Base Optimisation. In Rust the language has ZSTs so they can just write what they meant.

Here is Microsoft's implementation of map in the standard library. I think of myself as a competent programmer / computer scientist. I couldn't write this: https://github.com/microsoft/STL/blob/f392449fb72d1a387ac502...

Be careful on Windows, the MSVC STL implementation uses the system time, so it can be badly impacted by clock adjustments: https://github.com/microsoft/STL/issues/718

Can you provide a link? If it affects import std;, I'd like to add it to my tracking issue.

Do you have a list of the bugs you've filed and their current status, like the one I have for the STL? I saw you mentioned 3 bugs 7 months ago, 2 of which were fixed in 17.6 and the third of which was a duplicate of an active bug ("deducing this" is known to not yet work with modules, which is why we don't define the feature-test macro to claim full support).

Yep. And look at our implementation's name: https://github.com/microsoft/STL

> It's true, this was a CVE in Rust and not a CVE in C++, but only because C++ doesn't regard the issue as a problem at all. The problem definitely exists in C++, but it's not acknowledged as a problem, let alone fixed.

Can you find a link that substantiates your claim? You're throwing out some heavy accusations here that don't seem to match reality at all.

Case in point, this was fixed in both major C++ libraries:

https://github.com/gcc-mirror/gcc/commit/ebf6175464768983a2d...

https://github.com/llvm/llvm-project/commit/4f67a909902d8ab9...

So what C++ community refused to regard this as an issue and refused to fix it? Where is your supporting evidence for your claims?

Somewhat related: In 2020 gcc bumped the requirement for bootstrapping to be a C++11 compiler [0]. Would have been fun to see the kernel finally adopt C++14 as the author suggested.

I don't think that Linus will allow this since he just commented that he will allow rust in drivers and major subsystems [1].

I do found it pretty funny that even Linus is also not writing any rust code, but is reading rust code.

I would have hoped see more answers or see something in here from actual kernel developers.

0: https://github.com/gcc-mirror/gcc/commit/5329b59a2e13dabbe20...

> They’re saying that a lot of the restrictions makes things much harder than other languages. Hence the general problem rust has where a lot of trivial tasks in other languages are extremely challenging.

Like what? So far the discussion has revolved around rewriting a linked list, which people generally shouldn't ever need to do because it's included in the standard lib for most languages. And it's a decidedly nontrivial task to do as well as the standard lib when you don't sacrifice runtime overhead to be able to handwave object lifecycle management.

- C++: https://github.com/gcc-mirror/gcc/blob/master/libstdc%2B%2B-...

- Rust: https://doc.rust-lang.org/beta/src/alloc/collections/linked_...

> No need to get defensive, no one is arguing that rust doesn’t do a lot of things well.

That's literally what bsaul is arguing in another comment. :)

> You’re talking up getting a safe implementation in C, but what matters is “can I get the same level of safety with less complexity in any language”, and the answer is yes: Java and c# implementations of a thread safe linked list are trivial.

Less perceived complexity. In Java and C# you're delegating the responsibility of lifecycle management to garbage collectors. For small to medium scale web apps, the added complexity will be under the hood and you won't have to worry about it. For extreme use cases, the behavior and overhead of the garbage collector does became relevant.

If you factor in the code for the garbage collector that Java and C# depend on, the code complexity will tilt dramatically in favor of C++ or Rust.

However, it's going to be non-idiomatic to rewrite a garbage collector in Java or C# like it is to rewrite a linked list in Rust. If we consider the languages as they're actually used, rather than an academic scenario which mostly crops up when people expect the language to behave like C or Java, the comparison is a lot more favorable than you're framing it as.

> If I wanted I could do it in c++ though the complexity would be more than c# and Java it would be easier than rust.

You can certainly write a thread-safe linked list in C++, but then the enforcement of any assumptions you made about using it will be a manual burden on the user. This isn't just a design problem you can solve with more code - C++ is incapable of expressing the same restrictions as Rust, because doing so would break compatibility with C++ code and the language constructs needed to do so don't exist.

So it's somewhat apples and oranges here. Yes, you may have provided your team with a linked list, but it will either

GCC is also written in C++, and has had C++ deps since 2013:

https://github.com/gcc-mirror/gcc/blob/master/gcc/c/c-parser...

Compliers/Interpreters are also very commonly open source (here is the source code for a popular C compiler). That means you can even modify the compiler's code and change its behavior if you wanted to.

according to this commit, the story here seems to be much more interessting than I initially anticipated.

For a more detailed explanation, see [2]. (Also the inspiration for the above example,)

[1] https://en.m.wikipedia.org/wiki/Transitive_relation

[2] https://github.com/gcc-mirror/gcc/commit/50ddbd0282e06614b29...