cargo-leptos VS rustc_codegen_cranelift

> separate-front-target-dir = true

This is now enabled unconditionally and the Cargo.toml option is deprecated since cargo-leptos 0.2.3, it is going to be removed in 0.3

https://github.com/leptos-rs/cargo-leptos/pull/216

https://github.com/leptos-rs/cargo-leptos/issues/217

https://github.com/leptos-rs/cargo-leptos/commit/b0c19a87cff...

Leptos is a SolidJS-like framework with excellent performance. It has a great server-side story as well with server-side rendering & client-side hydration as well as what they call "server functions"; essentially define a function server-side and it can be called client-side without having to deal with http and API design. Also great tooling story with cargo-leptos, leptosfmt (as well as leptos-language-server)

Leptos got it working a couple weeks ago as well: https://github.com/leptos-rs/cargo-leptos

Future opportunities - This one's tougher to speak to since leptos is new on the block. I think it's worth exploring leptos (or sycamore?) just to learn about fine-grained reactivity, and comparing how it works compared to a traditional react model. But to me the ecosystem around leptos is promising, with tools like cargo-letpos, leptosfmt, and more, it seems the community is stepping up to help fill some gaps.

Windows is supported. See https://github.com/rust-lang/rustc_codegen_cranelift/issues/....

> When this happens, it seems like it'll be possible to get the LLVM bits out of the bootstrap process and lead to a fully self-hosted Rust.

What do you mean by "when this happens"? GP's point is that this has already happened: the Cranelift backend is feature-complete from the perspective of the language [0], except for inline assembly and unwinding on panic. It was merged into the upstream compiler in 2020 [1], and a compiler built with only the Cranelift backend is perfectly capable of building another compiler. LLVM hasn't been a necessary component of the Rust compiler for quite some time.

[0] https://github.com/bjorn3/rustc_codegen_cranelift

[1] https://github.com/rust-lang/rust/pull/77975

Note that the Cranelift codegen will eventually become standard for debug builds to speed them up.

Maybe one day we'll have rustc b3 backend like what they did with Cranelift

Additionally, there is gcc codegen for rustc (https://github.com/rust-lang/rustc_codegen_gcc), which is not a compiler per se, but an alternative code generator, with more architectures supported and other nice things. It's also coming along, but there's still a lot of work to do there too. There's also Cranelift codegen (https://github.com/bjorn3/rustc_codegen_cranelift), which is designed to make debug builds faster, but this is not as exciting/useful as the other 2.

For the instant reloading, that's in Sycamore, so you should speak to its devs, but as for the alternative compiler backend, it's not my project, but it uses Cranelift and works pretty well! See https://github.com/bjorn3/rustc_codegen_cranelift for details.

The more immediate goal of "distribute the cranelift backend as a rustup component" has been making good progress and seems like it might happen relatively soon https://github.com/bjorn3/rustc_codegen_cranelift/milestone/...