Clippy gave different result depend on the version of compiler and clippy

[chiro-hiro]

cargo clippy --all-targets -- -D warnings this check on CI/CD and my computer are giving different result. Are there any work around to keep other people in the same page?.

rustc 1.70.0 (90c541806 2023-05-31)
clippy 0.1.70 (90c54180 2023-05-31)

Here is my result:

442 |     let mut acc = p.clone();
    |                    ^^^^^^^^ help: remove this
    |
note: cloned value is neither consumed nor mutated
   --> src/gadgets/ecc.rs:442:19
    |
442 |     let mut acc = p.clone();
    |                   ^^^^^^^^^
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone
note: the lint level is defined here
   --> src/lib.rs:3:3
    |
3   |   warnings,
    |   ^^^^^^^^
    = note: `#[deny(clippy::redundant_clone)]` implied by `#[deny(warnings)]`

error: could not compile `nova-snark` (lib) due to previous error
warning: build failed, waiting for other jobs to finish...
error: redundant clone
    --> src/gadgets/ecc.rs:1070:18
     |
1070 |     let mut b = a.clone();
     |                  ^^^^^^^^ help: remove this
     |
note: cloned value is neither consumed nor mutated
    --> src/gadgets/ecc.rs:1070:17
     |
1070 |     let mut b = a.clone();
     |                 ^^^^^^^^^
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone

error: could not compile `nova-snark` (lib test) due to 2 previous errors

[huitseeker]

It's normal for clippy to give different results on different versions of the compiler, and CI is currently testing on the latest stable, which changed 5 days ago: https://releases.rs/docs/1.70.0/
The solution would be to add a toolchain file to this repo and update it regularly:
https://rust-lang.github.io/rustup/overrides.html#the-toolchain-file

[huitseeker]

Also, in this case, clippy seems to be wrong, see:
https://gist.github.com/huitseeker/91ceb640943a5cf221552766f24d1c76
(i.e. there's a couple of undetected borrow-after-moves that prevent the straightforward fix)