Discuss: Should we implement custom lints?

[HaoYang670]

Is your feature request related to a problem or challenge? Please describe what you are trying to do.

While working on #5640, we find that Datafusion provides many helpers to make the code simpler (#5640 (comment)). It is better for contributors to use them, instead of implement them own version or repeat themselves.

Currently, we find the room of improvement when reviewing the PR (for example #5640 (comment), and #4561 (comment)). It is ideal that we can implement lints for them so that the CI/CD can find them automatically.

Describe the solution you'd like
Implement custom lints for the project.
It is ideal if we can implement a plugin for cargo clippy.

Describe alternatives you've considered
We could not do this if it is not cost-effective.

Additional context
A discussion 2 years ago: https://users.rust-lang.org/t/custom-lints-for-my-crates/54897

[HaoYang670]

cc @iajoiner @alamb.

[alamb]

I worry if we require a non standard rust tool (like some clippy plugin) that would make it harder for people to contribute to datafusion as it would raise the barrier to entry

Tuning the existing standard tools to make the codebase more consistent, is a great idea, in my opinion

For example, we might consider enabling more clippy lints:
https://github.com/influxdata/influxdb_iox/blob/c0a53ae5a99c12dd50c9eb2772afefc8430d622c/querier/src/lib.rs#L2-L11

#![warn(
    missing_copy_implementations,
    missing_docs,
    clippy::explicit_iter_loop,
    clippy::future_not_send,
    clippy::use_self,
    clippy::clone_on_ref_ptr,
    clippy::todo,
    clippy::dbg_macro
)]

[HaoYang670]

Here is a blog: https://blog.trailofbits.com/2021/11/09/write-rust-lints-without-forking-clippy/ which introduced a crate for addling personal lints. It doesn't depend on cargo clippy, so that it won't affect the standard rust tool.

[alamb]

I think our current lints with clippy have served us well and we have used custom lints where appriate

Let's open new issues if we have specific ideas for new lints