No way to (easily) get specific nightly version

[cab404]

First of all, thanks for the project!
It's a lot nicer to use with flakes than mozilla-overlay, and saved me a lot of time!

I want a specific nightly version (for MIRAI), and the only way I can get it is via searching entire git history.
Adding tags would help, and should be easy enough to integrate into gh actions.

[cab404]

Other way would be storing every nightly release json. That would allow using consistent (and new) fenix versions.
@figsoda do you have any ideas about that? I would like to work on a PR.

[figsoda]

I personally disagree on storing every nightly release because this would make the repository a lot heavier. I would prefer something like

channelOf = { channel, date, sha256 }: {
  rustc = [...],
  cargo = [...],
  [...]
  withComponents = [...],
  toolchain = [...],
  minimalToolchain = [...],
  defaultToolchain = [...],
  completeToolchain = [...],
};

[cab404]

I personally disagree on storing every nightly release because this would make the repository a lot heavier. I would prefer something like

channelOf = { channel, date, sha256 }: {
  rustc = [...],
  cargo = [...],
  [...]
  withComponents = [...],
  toolchain = [...],
  minimalToolchain = [...],
  defaultToolchain = [...],
  completeToolchain = [...],
};

Looks fine to me as well, will work on a PR this weekend.

[mschwaig]

For those wondering why the date that

rustc --version

reports is consistently off by one, that's an upstream issue:
rust-lang/rust#51533

If you request a specific nightly from rustup, nixpkgs-mozilla or fenix rustc will confusingly report the day before as the build date.