Expand the scope of clippy checks

[alexandruag]

The current way of invoking clippy as part of the CI pipeline (cargo clippy --all -- -D warnings) does not check some parts of the code. It looks like the exhaustive list of relevant arguments is something along the lines of cargo clippy --workspace --bins --examples --tests --benches --all-targets --all-features -- -D warnings, with the caveat that --all-features might not make sense for all crates.

[andreeaflorescu]

Shouldn't all-features be a nop in case the crate doesn't have any features?

[alexandruag]

I was mainly thinking about crates where some features are contradictory and/or not meant to be enabled at the same time. Dunno exactly what could happen (with clippy at least) in that case :-s

[andreeaflorescu]

Right.

[alxiord]

We already cargo test --all-features, so the same concern applies there and I have no idea how to address it without dedicated buildkite pipelines, which I'd rather avoid. For now, we don't have any contradicting features in any crate.
Is --bins necessary? No crate produces a binary yet, and besides --workspace should cover it.

[alexandruag]

Sure, just raising the issue, and that we should be careful with crates where features are not orthogonal. For example, kvm-bindings has some additional steps in its pipeline for the different features (or so it seems); in the kvm-bindings case --all-features effectively selects just some of the features, due to our #cfg annotations.

--bins doesn't seem necessary for now; just added it to the list for good measure.

[alexandruag]

Ok so after a bit of digging around, it seems we get the most potential complaining out of clippy by running it with something like cargo clippy --bins --examples --tests --benches --release --all-targets --all-features --workspace -- -W clippy::all -W clippy::pedantic -W clippy::restriction -W clippy::nursery -W clippy::cargo. I guess we have to decide how strict we want to be (especially when it comes to the pedantic and restriction things), but either way it seems we've been missing some useful lints by running clippy the way we did before.

[andreeaflorescu]

I ran some experiments with clippy as well. We're now missing the most basic of them all (--all-features) which is already causing problems.

First, I propose we use the ones that are non-debatable:

• examples
• bin
• all-features
• workspace

The tests and benches can be too restrictive for all rust-vmm repos, as in tests you can do some of the things that clippy "disagrees" with on purpose. I'll submit a PR for the first part, and we can leave this issue open for further debates.