qcell VS rust

An unsoundness issue in TCell and TLCell was discovered and fixed by GitHub user steffahn. This is due to Rust TypeId taking into account the lifetime, i.e. you get a different type-id for the same type with different lifetimes, and Rust will automatically cast between them. The solution is to force invariance with some type voodoo. This is a weird corner of Rust I'd never understood before. Ideally std::any::TypeId docs should be improved. (This bug does not affect the safety of correct use of the crate, but fixing it blocks a malicious coder from getting potential unsoundness through a code review.)

This is slightly unrelated, but this thread made me dig up my own code that I was writing which was going to be essentially the same as the QCell crate, until I discovered that the QCell crate exists, at which point I stopped working on it and contributed to QCell instead (this PR).

> There are online Rust compilers and interpreters already if you just want to rapid prototype and develop ideas in Rust

You are responding to one of the key developers of Rust early on[1], who's been working with the language for 14 years at that point.

[1] https://github.com/rust-lang/rust/graphs/contributors?from=2... and he's still #16 in commits overall today, despite almost no activity on the rust compiler since 2014.

If you haven't dipped your touch-typing fingers into Rust yet, you really owe it to yourself. Rust is a modern programming language with features that make it suitable not only for systems programming -- its original purpose, but just about any other environment, too; there are frameworks that let your build web services, web applications including user interfaces, software for embedded devices, machine learning solutions, and of course, command-line tools. Since a custom GitHub Action is essentially a command-line tool that interacts with the system through files and environment variables, Rust is perfectly suited for that as well.

Here's an example of someone citing a disagreement between CRT and shell32:

https://github.com/rust-lang/rust/issues/44650

This in addition to the Rust CVE mentioned elsewhere in the thread which was rooted in this issue:

https://blog.rust-lang.org/2024/04/09/cve-2024-24576.html

Here are some quick programs to test contrasting approaches. I don't have examples of inputs where they parse differently on hand right now, but I know they exist. This was also a problem that was frequently discussed internally when I worked at MSFT.

    #include 

> instead of choosing a certain numbered version of the random library (if I remember correctly) I let cargo download the latest version which had a completely different API.

Yeah, they didn't follow the instructions and got burned. I still think that multiple things went wrong simultaneously for that experience. I wonder if more prevalent uses of `#[doc(alias = "name")]` being leveraged by https://github.com/rust-lang/rust/pull/120730 (which now that I check only accounts for methods and not functions, I should get on that!) so that when changing APIs around people at least get a slightly better experience.

Almost fixed the compiler: https://github.com/rust-lang/rust/pull/123325

Rust: A secure, efficient, and modern programming language (omitting ten thousand words). You can simply follow the installation instructions provided on the official website.

Recently did something similar in Rust but for generating SVGs. We've adopted it for snapshot testing of cargo and rustc's output. Don't have a good PR handy for showing Github's rendering of changes in the SVG (text, side-by-side, swiping) but https://github.com/rust-lang/rust/pull/121877/files has newly added SVGs.

To see what is supported, see the screenshot in the docs: https://docs.rs/anstyle-svg/latest/anstyle_svg/

We strongly believe in Rust as a powerful language for building production-grade software, especially for systems like ours that run alongside Kubernetes.