warning: this expression creates a reference which is immediately dereferenced by the compiler
   --> halo2_proofs/src/plonk/prover.rs:371:29
    |
371 | ...                   &domain,
    |                       ^^^^^^^ help: change this to: `domain`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow
    = note: `-W clippy::needless-borrow` implied by `-W clippy::all`

warning: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
   --> halo2_proofs/src/plonk/prover.rs:350:22
    |
350 |         let advice = std::mem::replace(&mut self.advice, Vec::new());
    |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut self.advice)`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#mem_replace_with_default

warning: replacing a value of type `T` with `T::default()` is better expressed using `std::mem::take`
   --> halo2_proofs/src/plonk/prover.rs:349:24
    |
349 |         let instance = std::mem::replace(&mut self.instance, Vec::new());
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using: `std::mem::take(&mut self.instance)`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#mem_replace_with_default
    = note: `-W clippy::mem-replace-with-default` implied by `-W clippy::all`

warning: this `if` has identical blocks
   --> halo2_proofs/src/plonk/prover.rs:249:55
    |
249 |               if column_indices.contains(&column_index) {
    |  _______________________________________________________^
250 | |                 // TODO: Check that column_index in witness is Some
251 | |                 // TODO: Check that the column length is `params.n()`
252 | |             } else {
    | |_____________^
    |
note: same as this
   --> halo2_proofs/src/plonk/prover.rs:252:20
    |
252 |               } else {
    |  ____________________^
253 | |                 // TODO: Check that column_index in witness is None
254 | |             };
    | |_____________^
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#if_same_then_else
    = note: `-W clippy::if-same-then-else` implied by `-W clippy::all`

warning: useless use of `format!`
   --> halo2_proofs/src/plonk/prover.rs:239:37
    |
239 |             return Err(Error::Other(format!("witness.len() != instance.len()")));
    |                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: consider using `.to_string()`: `"witness.len() != instance.len()".to_string()`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#useless_format
    = note: `-W clippy::useless-format` implied by `-W clippy::all`

warning: very complex type used. Consider factoring parts into `type` definitions
   --> halo2_proofs/src/plonk/prover.rs:199:18
    |
199 |         witness: Vec<Vec<Option<Polynomial<Assigned<Scheme::Scalar>, LagrangeCoeff>>>>,
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#type_complexity
    = note: `-W clippy::type-complexity` implied by `-W clippy::all`

warning: casting to the same type is unnecessary (`usize` -> `usize`)
    --> halo2_proofs/src/plonk/circuit.rs:1703:25
     |
1703 |         usable_rows: 0..n as usize - (cs.blinding_factors() + 1),
     |                         ^^^^^^^^^^ help: try: `n`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast

warning: casting to the same type is unnecessary (`usize` -> `usize`)
    --> halo2_proofs/src/plonk/circuit.rs:1702:37
     |
1702 |         selectors: vec![vec![false; n as usize]; cs.num_selectors],
     |                                     ^^^^^^^^^^ help: try: `n`
     |
     = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#unnecessary_cast
     = note: `-W clippy::unnecessary-cast` implied by `-W clippy::all`

warning: fields `num_fixed_columns` and `general_column_annotations` are never read
    --> halo2_proofs/src/plonk/circuit.rs:1637:16
     |
1636 | pub struct ConstraintSystemV2Backend<F: Field> {
     |            ------------------------- fields in this struct
1637 |     pub(crate) num_fixed_columns: usize,
     |                ^^^^^^^^^^^^^^^^^
...
1672 |     pub(crate) general_column_annotations: HashMap<metadata::Column, String>,
     |                ^^^^^^^^^^^^^^^^^^^^^^^^^^
     |
     = note: `ConstraintSystemV2Backend` has derived impls for the traits `Clone` and `Debug`, but these are intentionally ignored during dead code analysis
     = note: `#[warn(dead_code)]` on by default

warning: unused variable: `advice_column`
   --> halo2_proofs/src/plonk/prover.rs:248:28
    |
248 |         for (column_index, advice_column) in witness.iter().enumerate() {
    |                            ^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_advice_column`
    |
    = note: `#[warn(unused_variables)]` on by default

warning: unused `std::result::Result` that must be used
   --> halo2_proofs/tests/frontend_backend_split.rs:234:17
    |
234 |                 config.s_instance.enable(&mut region, offset);
    |                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: this `Result` may be an `Err` variant, which should be handled
    = note: `#[warn(unused_must_use)]` on by default

warning: redundant clone
   --> halo2_proofs/tests/frontend_backend_split.rs:490:33
    |
490 |         keygen_pk_v2(&params, vk.clone(), &compiled_circuit).expect("keygen_pk should not fail");
    |                                 ^^^^^^^^ help: remove this
    |
note: this value is dropped without further use
   --> halo2_proofs/tests/frontend_backend_split.rs:490:31
    |
490 |         keygen_pk_v2(&params, vk.clone(), &compiled_circuit).expect("keygen_pk should not fail");
    |                               ^^
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone

warning: this expression creates a reference which is immediately dereferenced by the compiler
   --> halo2_proofs/tests/frontend_backend_split.rs:466:40
    |
466 |     let strategy = SingleStrategy::new(&verifier_params);
    |                                        ^^^^^^^^^^^^^^^^ help: change this to: `verifier_params`
    |
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#needless_borrow
    = note: `-W clippy::needless-borrow` implied by `-W clippy::all`

warning: redundant clone
   --> halo2_proofs/tests/frontend_backend_split.rs:455:18
    |
455 |         &[circuit.clone()],
    |                  ^^^^^^^^ help: remove this
    |
note: this value is dropped without further use
   --> halo2_proofs/tests/frontend_backend_split.rs:455:11
    |
455 |         &[circuit.clone()],
    |           ^^^^^^^
    = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#redundant_clone
    = note: `-W clippy::redundant-clone` implied by `-W clippy::all`

warning: very complex type used. Consider factoring parts into `type` definitions
  --> halo2_proofs/tests/frontend_backend_split.rs:64:10
   |
64 |     ) -> Result<(AssignedCell<F, F>, [AssignedCell<F, F>; 4]), Error> {
   |          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = help: for further information visit https://rust-lang.github.io/rust-clippy/master/index.html#type_complexity
   = note: `-W clippy::type-complexity` implied by `-W clippy::all`

warning: unused variable: `pk`
   --> halo2_proofs/tests/frontend_backend_split.rs:489:9
    |
489 |     let pk =
    |         ^^ help: if this is intentional, prefix it with an underscore: `_pk`

warning: unused variable: `verifier_params`
   --> halo2_proofs/tests/frontend_backend_split.rs:487:9
    |
487 |     let verifier_params = params.verifier_params();
    |         ^^^^^^^^^^^^^^^ help: if this is intentional, prefix it with an underscore: `_verifier_params`
    |
    = note: `#[warn(unused_variables)]` on by default

warning: unused import: `EncodedChallenge`
  --> halo2_proofs/tests/frontend_backend_split.rs:19:46
   |
19 |     Blake2bRead, Blake2bWrite, Challenge255, EncodedChallenge, TranscriptReadBuffer,
   |                                              ^^^^^^^^^^^^^^^^

warning: unused import: `halo2_proofs::poly::VerificationStrategy`
  --> halo2_proofs/tests/frontend_backend_split.rs:17:5
   |
17 | use halo2_proofs::poly::VerificationStrategy;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

warning: unused import: `Verifier`
  --> halo2_proofs/tests/frontend_backend_split.rs:15:78
   |
15 | use halo2_proofs::poly::commitment::{CommitmentScheme, ParamsProver, Prover, Verifier};
   |                                                                              ^^^^^^^^

warning: unused import: `Prover`
  --> halo2_proofs/tests/frontend_backend_split.rs:15:70
   |
15 | use halo2_proofs::poly::commitment::{CommitmentScheme, ParamsProver, Prover, Verifier};
   |                                                                      ^^^^^^

warning: unused import: `ParamsVerifierKZG`
   --> halo2_proofs/tests/frontend_backend_split.rs:400:75
    |
400 | use halo2_proofs::poly::kzg::commitment::{KZGCommitmentScheme, ParamsKZG, ParamsVerifierKZG};
    |                                                                           ^^^^^^^^^^^^^^^^^

warning: unused import: `std::marker::PhantomData`
  --> halo2_proofs/tests/frontend_backend_split.rs:23:5
   |
23 | use std::marker::PhantomData;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^

warning: unused imports: `OsRng`, `RngCore`
  --> halo2_proofs/tests/frontend_backend_split.rs:22:17
   |
22 | use rand_core::{OsRng, RngCore};
   |                 ^^^^^  ^^^^^^^

warning: unused import: `CommitmentScheme`
  --> halo2_proofs/tests/frontend_backend_split.rs:15:38
   |
15 | use halo2_proofs::poly::commitment::{CommitmentScheme, ParamsProver, Prover, Verifier};
   |                                      ^^^^^^^^^^^^^^^^