fix some lints

[danieleades]

fixes a bunch of clippy lints. There's a couple of potentially controversial commits in there, particularly the elimination of unused 'self' arguments

[hannobraun]

Thank you for this pull request, @danieleades!

I like all these changes, with the exception of the Clippy MSRV. I've left a comment there. I'm going to drop that commit and merge this pull request immediately, as it isn't going to age well. If left unmerged, it would have conflicts very soon.

If you disagree with my comment on the MSRV, feel free to submit that again in a new pull request. I don't want to kill any discussion, I just want to get the rest of this merged as soon as possible.

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Since the code already builds without Clippy warnings (as verified by the CI build), I assume you used a non-default Clippy configuration. Would you mind submitting that configuration too, so the code doesn't regress?

[hannobraun]

Isn't that redundant with rust-toolchain.toml, since that already defines which Clippy version we're running with? I'd rather not have another place which I need to remember to update, unless there is a clear benefit.

[danieleades]

no, clippy doesn't parse the rust-toolchain.toml file. The benefit is that you can run the nightly clippy, but avoid any clippy suggestions that would violate the msrv.

For example, inline format args were added in 1.58, but the clippy suggestion to update the syntax didn't arrive until 1.65. Specifying the clippy MSRV in the config file allows you to use the nightly clippy and get the up-to-date suggestions right away

[hannobraun]

I didn't mean to say that Clippy parses the rust-toolchain.toml. What I meant was that the contents of the rust-toolchain.toml define what version of Clippy is going to run.

But I understand why we need this now. You can still run cargo +nightly clippy to override the specified toolchain, and then this configuration would be useful.

Thanks for explaining!