Your comment and the comment you are replying to are both correct.

Rocket's current released version is 0.4.5, and that version builds with a stable Rust toolchain.

It looks to me like 0.4.5 still requires nightly:

  error: failed to run custom build command for `rocket_codegen v0.4.5`
  
  Caused by:
    process didn't exit successfully: `/home/vlad/code/test-rocket/target/debug/build/rocket_codegen-f5b5d853ac3ddd89/build-script-build` (exit code: 101)
    --- stderr
    Error: Rocket (codegen) requires a 'dev' or 'nightly' version of rustc.
    Installed version: 1.47.0 (2020-10-07)
    Minimum required:  1.33.0-nightly (2019-01-13)

Edit: formatting

Indeed. Apparently the support for stable Rust was merged onto master months ago, but there hasn't been a release since then. 0.5 should be the first version that builds on stable Rust according to this thread: https://github.com/SergioBenitez/Rocket/issues/19

You can use 0.5.0-dev if you want stable rust.

I want to caveat this by first saying I’m a fan of Rust in general, but does one not see the irony in the article’s claim to the effect “yes, it’s ready as a Rails replacement”, yet requires you to use an unreleased dev version of a library to even build from a stable release of the language?

Yeah, and I don't know how anyone could claim its a Rails replacement. Diesel, warp, rocket et al are great but the DX and feature completeness aren't there yet.

That said, with Cargo using the unreleased version is as simple as changing `rocket = "0.4.5"` to `rocket = { git = "https://github.com/SergioBenitez/Rocket" }` so it's not like you even have to clone it manually. You can even specify branches if you urgently need a PR and patch entire workspaces with forked versions and so on.