Proposal: Use & Fix pedantic and nursery lints across the codebase

[theodorebje]

Hello! I've looked into how difficult it would be to add the pedantic and nursery lints to the Cargo.toml, and then fix all the resulting warnings. Personally, I believe this could greatly improve readability and maintainability of the project. I've made significant progress, but before I continue further, I would like to ask a few questions:

• Would you be open to a contribution fixing these pedantic and nursery warnings?
• Do you have any preferences on how the work should be submitted (one big PR or multiple smaller PRs)?
• Currently, each lint has its own commit. Would you like me to group them together in some other way?
• Are there any specific (pedantic or nursery) lints that I should leave untouched?
• Are there any other (non-pedantic/nursery) lints you'd like me to try to address while I'm at it?
• What's your view on lints that can break API compatibility?

Some lints (e.g. missing_const_for_fn) only break API compatibility if the lint changes are removed later. From the documentation:

If you are marking a public function with const, removing it again will break API compatibility.

Others (e.g. fn_params_excessive_bools) immediately break API compatibility if applied to public items.

Are these OK even though they can break API compatibility? Should I leave them in a separate PR?

Thank you for maintaining Axum! Would love to hear your feedback on this.

[jplatte]

I'm open to enabling more specific clippy lints, but definitely not the whole pedantic or nursery group. Feel free to open a (draft) PR and we can discuss the merit of individual changes there.

[mladedav]

And just to expand on a few questions:

Currently, each lint has its own commit. Would you like me to group them together in some other way?

That's best I think, if we decide the lint isn't worth it, it's easier to remove it that way and it's clearer in review, what's happening and why.

What's your view on lints that can break API compatibility?

We have already breaking changes merged in main, but I'd be cautious with this. I think separate PR for breaking changes would be best.

[theodorebje]

I've made a draft PR: #3394. Should we move the discussion there (and close this one)?

[theodorebje]

Closing this since the discussion has moved to the individual PRs' discussions.