feat: update to rust edition 2021

[dignifiedquire]

bumps MSRV to 1.56.0

[newpavlov]

It's also worth to add rust-version = "1.56" field as well.

[dignifiedquire]

I wonder why nightly CI is unhappy now

[paolobarbolini]

Wih this MSRV bump it should now be possible to relax the zeroize version requirement

[tarcieri]

I wonder why nightly CI is unhappy now

The nightly feature of the subtle crate is using a feature which has been stabilized in 1.56:

error[E0557]: feature has been removed
  --> /Users/bascule/.cargo/registry/src/github.com-1ecc6299db9ec823/subtle-2.4.0/src/lib.rs:12:42
   |
12 | #![cfg_attr(feature = "nightly", feature(external_doc))]
   |                                          ^^^^^^^^^^^^ feature has been removed
   |
   = note: use #[doc = include_str!("filename")] instead, which handles macro invocations

Note that the nightly feature of subtle doesn't provide much value anymore, so it might be good not to activate it, particularly since it doesn't compile on recent nightlies anymore.

[tarcieri]

Wow that's really weird... almost feels like a nightly bug?

@dignifiedquire maybe try bumping num-bigint-dig to the 2021 edition first?

[poliorcetics]

CI gets the following error:

 error[E0599]: no function or associated item named `deserialize` found for struct `Vec<_, _>` in the current scope
Error:     --> /cargo/registry/src/github.com-1ecc6299db9ec823/num-bigint-dig-0.7.0/src/biguint.rs:2582:35
     |
2582 |         let data: Vec<u32> = Vec::deserialize(deserializer)?;
     |                                   ^^^^^^^^^^^ function or associated item not found in `Vec<_, _>`

I'm not managing to reproduce it on num-bigint, tag v0.7.0, with all the features used by cg +nightly build --features=i128,nightly,prime,rand,serde,u64_digit,zeroize but compiling this PR with cargo +nightly build --all-features does have the error.

Nightly version: cargo 1.60.0-nightly (358e79fe5 2022-01-04)

[poliorcetics]

Taking this PR and changing the edition to 2018 works, this is very probably a rustc bug due to num-bigint(-dig) not setting an edition in Cargo.toml (so defauting to 2015). This probably cannot be merged without num-bigint moving to 2018 or 2021 edition first.

[tarcieri]

I opened a PR to bump the edition for num-bigint-dig to 2021: dignifiedquire/num-bigint#34

[poliorcetics]

Asked for a 0.8 update for num-bigint-dig so it can be updated in this PR and complete it

[paolobarbolini]

num-bigint-dig 0.8 is out 🥳!
https://crates.io/crates/num-bigint-dig

[dignifiedquire]

unfortunately this did not fix the rustc bug :'(

[paolobarbolini]

I'm from my phone so I can't test now but could it be caused by the serde alloc feature not being enabled?

https://github.com/dignifiedquire/num-bigint/blob/9c7fbac52c48e05cff75104f3a1278bd577b3ee3/Cargo.toml#L57

https://github.com/RustCrypto/RSA/runs/5246995762?check_suite_focus=true#step:4:373

[paolobarbolini]

I can see it was enabled previously 👀. Must have been caused by resolver = 2

https://github.com/RustCrypto/RSA/runs/5036633905?check_suite_focus=true#step:4:274

[paolobarbolini]

Confirmed by running cargo check --no-default-features --features i128,u64_digit,prime,zeroize,serde and cargo tree --edges normal --format "{p} {f}" --no-default-features --features i128,u64_digit,prime,zeroize,serde on num-bigint-dig

[newpavlov]

It could be worth to add the minimal versions job to CI.

[newpavlov]

Argh, unfortunately, you can not use the shared workflow, since it targets multi-crate repos. You can use the following config instead:

  minimal-versions:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v2
      - uses: RustCrypto/actions/cargo-cache@master
      - uses: actions-rs/toolchain@v1
        with:
          toolchain: nightly
          override: true
          profile: minimal
      - uses: RustCrypto/actions/cargo-hack-install@master
      - run: cargo update -Z minimal-versions
      - run: cargo hack test --release --feature-powerset

Also while we are at it, it could be useful to add cargo cache to other RSA jobs to reduce CI run time. I can submit a separate PR, if you do not want to do it right now.

[poliorcetics]

CI improvement should be delayed to another MR, this is blocking a new release of RSA which in turn blocks the whole ecosystem that uses both RSA and another crate that has made the jump to a recent version of hashes.

I can take the commits except the last one and put them in another MR to move forward if needed.

[tarcieri]

I tried @newpavlov's minimal-versions config. It looks like num-bigint-dig v0.8.1 is not configured with the correct versions for that to work: https://github.com/RustCrypto/RSA/runs/5497433460?check_suite_focus=true

So I agree it would make sense to get this PR merged first then circle back on making num-bigint-dig minimal-versions correct and then following up on minimal-versions CI in a separate PR.

[newpavlov]

I am fine with leaving the CI changes for later, but I think the minimal versions build should be fixed before we release rsa v0.6.

[tarcieri]

FYI for anyone particularly blocked here: I just cut a v0.6.0-pre release with these changes

https://crates.io/crates/rsa/0.6.0-pre