Things you can’t do in Rust (and what to do instead)

• rust

  2,682 92,831 10.0 Rust

  Empowering everyone to build reliable and efficient software.

  

Overall this is a great blog post that highlights many of the things newcomers to Rust try out or are surprised why they are so hard and discouraged. One nit:

> Luckily there are some crates that take the solution and present a safe interface, such as the rental and once_self_cell crates.

Please don't link to the rental crate any more, as it's out of maintenance. The github repo is archived [0] and the maintainer explicitly stated they don't want to hand over maintenance to someone else. Thankfully the maintainer was still available to implement one tiny patch recently to make it not fire a future compat lint [1], but given this announcement by the maintainer, generally I'd recommend people to move to maintained alternatives. Especially new projects should build on something else. Instead of rental, the blog post could mention ouroboros. Also as a nit, the once_self_cell crate has been renamed to self_cell. There is also selfstack but I haven't used it so don't know how good it is.

[0]: https://github.com/jpernst/rental/commit/213671ab3aab3452efd...

[1]: https://github.com/rust-lang/rust/issues/84428

• rental

  3 211 1.2 Rust

  Discontinued Rust macro to generate self-referential structs

Overall this is a great blog post that highlights many of the things newcomers to Rust try out or are surprised why they are so hard and discouraged. One nit:

> Luckily there are some crates that take the solution and present a safe interface, such as the rental and once_self_cell crates.

Please don't link to the rental crate any more, as it's out of maintenance. The github repo is archived [0] and the maintainer explicitly stated they don't want to hand over maintenance to someone else. Thankfully the maintainer was still available to implement one tiny patch recently to make it not fire a future compat lint [1], but given this announcement by the maintainer, generally I'd recommend people to move to maintained alternatives. Especially new projects should build on something else. Instead of rental, the blog post could mention ouroboros. Also as a nit, the once_self_cell crate has been renamed to self_cell. There is also selfstack but I haven't used it so don't know how good it is.

[0]: https://github.com/jpernst/rental/commit/213671ab3aab3452efd...

[1]: https://github.com/rust-lang/rust/issues/84428

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• sccache

  70 5,347 9.4 Rust

  Sccache is a ccache-like tool. It is used as a compiler wrapper and avoids compilation when possible. Sccache has the capability to utilize caching in remote storage environments, including various cloud storage options, or alternatively, in local storage.

  

I find if you're aware about how you define your modules, incremental compiles are usually pretty quick. Yes a complete build can take a while but tools like sccache[0] can help with that in CI pipelines and when getting a new dev environment up.

[0]: https://github.com/mozilla/sccache

• cargo-expand

  16 2,427 8.6 Rust

  Subcommand to show result of macro expansion

Ignore the first line, it's how the macro vec! expands. The second line shows the difference in what the versions generate. The first takes a borrow of the result of parse, the second takes a Cow::Owned of it. (Cow stands for copy on write, but it's more generally useful for anything where you want to be generic over either the borrowed or owned version of something.).

So the short answer is the macro used to expand to something that wasn't owned, and not it does. As for why it worked without a separate assignment, that's because Rust automatically created a temporary variable for you.

> When using a value expression in most place expression contexts, a temporary unnamed memory location is created initialized to that value and the expression evaluates to that location instead, except if promoted to a static

https://doc.rust-lang.org/reference/expressions.html#tempora...

I took a look at the git blame[2] for the element! macro in lol_html, and they made the change because someone opened an issue with essentially your problem. So I'd say this is a bug in a leaky abstraction, not an issue with your understanding of rust.

[1]: https://github.com/dtolnay/cargo-expand

• lol-html

  8 1,390 5.7 Rust

  Low output latency streaming HTML parser/rewriter with CSS selector-based API

  

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