Just to confirm, I check with `cargo +nightly clippy` but it doesn't
complain about this case. Should I switch to another version of clippy
when I do such check? (currently I'm using v0.1.63 clippy as well, to
match rustc.)
I don't remember exactly how I noticed it—I am pretty sure it broke in CI though. Maybe the change to add rust_version hid it.
To answer your question, generally the idea is that we use the latest version of the developer tools (cargo, rustfmt, clippy). In particular old versions of cargo don't support retrieving clippy settings from Cargo.toml.
Paolo