chore: improve codebase with some clippy suggestions (#867)

* chore: improve codebase with some clippy suggestions

* Update ec/src/hashing/tests.rs

* Update ec/src/hashing/tests.rs

* Update ec/src/hashing/tests.rs

* Update ff/src/biginteger/tests.rs

* Update ec/src/hashing/curve_maps/wb.rs

* fix comments

* Update ff/src/biginteger/tests.rs

Co-authored-by: Pratyush Mishra <[email protected]>

* Update ff/src/biginteger/tests.rs

Co-authored-by: Pratyush Mishra <[email protected]>

* Update ff/src/biginteger/tests.rs

Co-authored-by: Pratyush Mishra <[email protected]>

* Update ff/src/biginteger/tests.rs

Co-authored-by: Pratyush Mishra <[email protected]>

---------

Co-authored-by: Pratyush Mishra <[email protected]>

Cargo.toml

@@ -23,13 +23,20 @@ authors = [ "arkworks contributors" ]
 homepage = "https://arkworks.rs"
 repository = "https://github.com/arkworks-rs/algebra"
 categories = ["cryptography"]
-include = ["Cargo.toml", "src", "README.md", "LICENSE-APACHE", "LICENSE-MIT", "doc/katex-header.html"]
+include = [
+    "Cargo.toml",
+    "src",
+    "README.md",
+    "LICENSE-APACHE",
+    "LICENSE-MIT",
+    "doc/katex-header.html",
+]
 license = "MIT OR Apache-2.0"
 edition = "2021"
 rust-version = "1.75"
 
 [workspace.metadata.docs.rs]
-rustdoc-args = [ "--html-in-header katex-header.html" ]
+rustdoc-args = ["--html-in-header katex-header.html"]
 
 [workspace.metadata.release]
 dependent-version = "fix"
@@ -56,7 +63,10 @@ arrayvec = { version = "0.7", default-features = false }
 criterion = "0.5.0"
 educe = "0.6.0"
 digest = { version = "0.10", default-features = false }
-hashbrown = { version = "0.15", default-features = false, features = ["inline-more", "allocator-api2"] }
+hashbrown = { version = "0.15", default-features = false, features = [
+    "inline-more",
+    "allocator-api2",
+] }
 hex = "0.4"
 itertools = { version = "0.13", default-features = false }
 libtest-mimic = "0.8.1"

ec/src/hashing/curve_maps/mod.rs

@@ -3,8 +3,8 @@ pub mod elligator2;
 pub mod swu;
 pub mod wb;
 
-//// parity method on the Field elements based on [\[1\]] Section 4.1
-//// which is used by multiple curve maps including Elligator2 and SWU
+/// parity method on the Field elements based on [\[1\]] Section 4.1
+/// which is used by multiple curve maps including Elligator2 and SWU
 /// - [\[1\]] <https://datatracker.ietf.org/doc/html/rfc9380/>
 pub fn parity<F: Field>(element: &F) -> bool {
     element

ec/src/hashing/curve_maps/wb.rs

@@ -15,6 +15,7 @@ type BaseField<MP> = <MP as CurveConfig>::BaseField;
 
 /// [`IsogenyMap`] defines an isogeny between curves of
 /// form `Phi(x, y) := (a(x), b(x)*y).
+///
 /// The `x` coordinate of the codomain point only depends on the
 /// `x`-coordinate of the domain point, and the
 /// `y`-coordinate of the codomain point is a multiple of the `y`-coordinate of the domain point.
@@ -39,7 +40,7 @@ pub struct IsogenyMap<
     pub y_map_denominator: &'a [BaseField<Codomain>],
 }
 
-impl<'a, Domain, Codomain> IsogenyMap<'a, Domain, Codomain>
+impl<Domain, Codomain> IsogenyMap<'_, Domain, Codomain>
 where
     Domain: SWCurveConfig,
     Codomain: SWCurveConfig<BaseField = BaseField<Domain>>,
@@ -64,10 +65,14 @@ where
     }
 }
 
-/// Trait defining the necessary parameters for the WB hash-to-curve method
-/// for the curves of Weierstrass form of:
-/// of y^2 = x^3 + a*x + b where b != 0 but `a` can be zero like BLS-381 curve.
-/// From [\[WB2019\]]
+/// Trait defining the necessary parameters for the WB hash-to-curve method.
+///
+/// This method is used for curves in Weierstrass form defined by:
+///
+/// `y^2 = x^3 + a*x + b` where `b != 0`, but `a` can be zero,
+/// as seen in curves like BLS-381.
+///
+/// For more information, refer to [WB2019].
 ///
 /// - [\[WB2019\]] <http://dx.doi.org/10.46586/tches.v2019.i4.154-179>
 pub trait WBConfig: SWCurveConfig + Sized {

ec/src/hashing/map_to_curve_hasher.rs

@@ -14,9 +14,14 @@ pub trait MapToCurve<T: CurveGroup>: Sized {
     fn map_to_curve(point: T::BaseField) -> Result<T::Affine, HashToCurveError>;
 }
 
-/// Helper struct that can be used to construct elements on the elliptic curve
-/// from arbitrary messages, by first hashing the message onto a field element
-/// and then mapping it to the elliptic curve defined over that field.
+/// A helper struct used to construct elements on an elliptic curve
+/// from arbitrary messages.
+///
+/// The process works in two stages:
+///
+/// 1. First, the message is hashed into a field element.
+/// 2. Then, the resulting field element is mapped to the elliptic curve
+///    defined over that field.
 pub struct MapToCurveBasedHasher<T, H2F, M2C>
 where
     T: CurveGroup,

ec/src/models/bw6/mod.rs

@@ -65,7 +65,7 @@ pub trait BW6Config: 'static + Eq + Sized {
 
     // Computes the exponent of an element of the cyclotomic subgroup by the curve seed
     fn exp_by_x(f: &Fp6<Self::Fp6Config>) -> Fp6<Self::Fp6Config> {
-        Self::cyclotomic_exp_signed(f, &Self::X, Self::X_IS_NEGATIVE)
+        Self::cyclotomic_exp_signed(f, Self::X, Self::X_IS_NEGATIVE)
     }
 
     fn final_exponentiation_hard_part(f: &Fp6<Self::Fp6Config>) -> Fp6<Self::Fp6Config> {
@@ -74,7 +74,9 @@ pub trait BW6Config: 'static + Eq + Sized {
 
     fn final_exponentiation(f: MillerLoopOutput<BW6<Self>>) -> Option<PairingOutput<BW6<Self>>> {
         let easy_part = BW6::<Self>::final_exponentiation_easy_part(f.0);
-        Some(Self::final_exponentiation_hard_part(&easy_part)).map(PairingOutput)
+        Some(PairingOutput(Self::final_exponentiation_hard_part(
+            &easy_part,
+        )))
     }
 
     fn multi_miller_loop(
@@ -219,7 +221,7 @@ impl<P: BW6Config> BW6<P> {
     }
 
     fn exp_by_x_minus_1_div_3(f: &Fp6<P::Fp6Config>) -> Fp6<P::Fp6Config> {
-        P::cyclotomic_exp_signed(f, &P::X_MINUS_1_DIV_3, P::X_IS_NEGATIVE)
+        P::cyclotomic_exp_signed(f, P::X_MINUS_1_DIV_3, P::X_IS_NEGATIVE)
     }
 
     // f^[(p^3-1)(p+1)]
@@ -285,9 +287,9 @@ impl<P: BW6Config> BW6<P> {
             // d1 = (ht-hy)//2
             let d1 = (P::H_T - P::H_Y) / 2;
             // H = F**d1 * E
-            let h = P::cyclotomic_exp_signed(&f, &[d1 as u64], d1 < 0) * &e;
+            let h = P::cyclotomic_exp_signed(&f, [d1 as u64], d1 < 0) * &e;
             // H = H**2 * H * B * G**d2
-            let h = h.square() * &h * &b * g.cyclotomic_exp(&[d2]);
+            let h = h.square() * &h * &b * g.cyclotomic_exp([d2]);
             // return A * H
             a * &h
         } else {
@@ -325,9 +327,9 @@ impl<P: BW6Config> BW6<P> {
             // d1 = (ht+hy)//2
             let d1 = (P::H_T + P::H_Y) / 2;
             // J = H**d1 * E
-            let j = P::cyclotomic_exp_signed(&h, &[d1 as u64], d1 < 0) * &e;
+            let j = P::cyclotomic_exp_signed(&h, [d1 as u64], d1 < 0) * &e;
             // K = J**2 * J * B * I**d2
-            let k = j.square() * &j * &b * i.cyclotomic_exp(&[d2]);
+            let k = j.square() * &j * &b * i.cyclotomic_exp([d2]);
             // return A * K
             a * &k
         }

ec/src/models/mod.rs

@@ -11,6 +11,7 @@ pub mod twisted_edwards;
 
 /// Elliptic curves can be represented via different "models" with varying
 /// efficiency properties.
+///
 /// `CurveConfig` bundles together the types that are common
 /// to all models of the given curve, namely the `BaseField` over which the
 /// curve is defined, and the `ScalarField` defined by the appropriate

ec/src/models/short_weierstrass/affine.rs

@@ -201,7 +201,7 @@ impl<P: SWCurveConfig> AffineRepr for Affine<P> {
     type Group = Projective<P>;
 
     fn xy(&self) -> Option<(Self::BaseField, Self::BaseField)> {
-        (!self.infinity).then(|| (self.x, self.y))
+        (!self.infinity).then_some((self.x, self.y))
     }
 
     #[inline]

ec/src/models/short_weierstrass/mod.rs

@@ -24,8 +24,9 @@ mod serialization_flags;
 pub use serialization_flags::*;
 
 /// Constants and convenience functions that collectively define the [Short Weierstrass model](https://www.hyperelliptic.org/EFD/g1p/auto-shortw.html)
-/// of the curve. In this model, the curve equation is `y² = x³ + a * x + b`,
-/// for constants `a` and `b`.
+/// of the curve.
+///
+/// In this model, the curve equation is `y² = x³ + a * x + b`, for constants `a` and `b`.
 pub trait SWCurveConfig: super::CurveConfig {
     /// Coefficient `a` of the curve equation.
     const COEFF_A: Self::BaseField;

ec/src/models/twisted_edwards/affine.rs

@@ -162,7 +162,7 @@ impl<P: TECurveConfig> AffineRepr for Affine<P> {
     type Group = Projective<P>;
 
     fn xy(&self) -> Option<(Self::BaseField, Self::BaseField)> {
-        (!self.is_zero()).then(|| (self.x, self.y))
+        (!self.is_zero()).then_some((self.x, self.y))
     }
 
     fn generator() -> Self {

ec/src/models/twisted_edwards/mod.rs

@@ -19,8 +19,9 @@ mod serialization_flags;
 pub use serialization_flags::*;
 
 /// Constants and convenience functions that collectively define the [Twisted Edwards model](https://www.hyperelliptic.org/EFD/g1p/auto-twisted.html)
-/// of the curve. In this model, the curve equation is
-/// `a * x² + y² = 1 + d * x² * y²`, for constants `a` and `d`.
+/// of the curve.
+///
+/// In this model, the curve equation is `a * x² + y² = 1 + d * x² * y²`, for constants `a` and `d`.
 pub trait TECurveConfig: super::CurveConfig {
     /// Coefficient `a` of the curve equation.
     const COEFF_A: Self::BaseField;
@@ -159,8 +160,9 @@ pub trait TECurveConfig: super::CurveConfig {
 }
 
 /// Constants and convenience functions that collectively define the [Montgomery model](https://www.hyperelliptic.org/EFD/g1p/auto-montgom.html)
-/// of the curve. In this model, the curve equation is
-/// `b * y² = x³ + a * x² + x`, for constants `a` and `b`.
+/// of the curve.
+///
+/// In this model, the curve equation is `b * y² = x³ + a * x² + x`, for constants `a` and `b`.
 pub trait MontCurveConfig: super::CurveConfig {
     /// Coefficient `a` of the curve equation.
     const COEFF_A: Self::BaseField;

ec/src/scalar_mul/glv.rs

@@ -10,11 +10,13 @@ use num_traits::{One, Signed};
 
 /// The GLV parameters for computing the endomorphism and scalar decomposition.
 pub trait GLVConfig: Send + Sync + 'static + SWCurveConfig {
-    /// Constants that are used to calculate `phi(G) := lambda*G`.
-
+    /// Constant used to calculate `phi(G) := lambda*G`.
+    ///
     /// The coefficients of the endomorphism
     const ENDO_COEFFS: &'static [Self::BaseField];
 
+    /// Constant used to calculate `phi(G) := lambda*G`.
+    ///
     /// The eigenvalue corresponding to the endomorphism.
     const LAMBDA: Self::ScalarField;
 
@@ -30,7 +32,8 @@ pub trait GLVConfig: Send + Sync + 'static + SWCurveConfig {
         let scalar: BigInt = k.into_bigint().into().into();
 
         let coeff_bigints: [BigInt; 4] = Self::SCALAR_DECOMP_COEFFS.map(|x| {
-            BigInt::from_biguint(x.0.then_some(Sign::Plus).unwrap_or(Sign::Minus), x.1.into())
+            let sign = if x.0 { Sign::Plus } else { Sign::Minus };
+            BigInt::from_biguint(sign, x.1.into())
         });
 
         let [n11, n12, n21, n22] = coeff_bigints;

ec/src/scalar_mul/mod.rs

@@ -182,7 +182,7 @@ impl<T: ScalarMul> BatchMulPreprocessing<T> {
     ) -> Self {
         let window = Self::compute_window_size(num_scalars);
         let in_window = 1 << window;
-        let outerc = (max_scalar_size + window - 1) / window;
+        let outerc = max_scalar_size.div_ceil(window);
         let last_in_window = 1 << (max_scalar_size - (outerc - 1) * window);
 
         let mut multiples_of_g = vec![vec![T::zero(); in_window]; outerc];
@@ -236,7 +236,7 @@ impl<T: ScalarMul> BatchMulPreprocessing<T> {
     }
 
     fn windowed_mul(&self, scalar: &T::ScalarField) -> T {
-        let outerc = (self.max_scalar_size + self.window - 1) / self.window;
+        let outerc = self.max_scalar_size.div_ceil(self.window);
         let modulus_size = T::ScalarField::MODULUS_BIT_SIZE as usize;
         let scalar_val = scalar.into_bigint().to_bits_le();
 

ec/src/scalar_mul/variable_base/mod.rs

@@ -69,9 +69,9 @@ pub trait VariableBaseMSM: ScalarMul {
 
     /// Streaming multi-scalar multiplication algorithm with hard-coded chunk
     /// size.
-    fn msm_chunks<I: ?Sized, J>(bases_stream: &J, scalars_stream: &I) -> Self
+    fn msm_chunks<I, J>(bases_stream: &J, scalars_stream: &I) -> Self
     where
-        I: Iterable,
+        I: Iterable + ?Sized,
         I::Item: Borrow<Self::ScalarField>,
         J: Iterable,
         J::Item: Borrow<Self::MulBase>,
@@ -88,7 +88,7 @@ pub trait VariableBaseMSM: ScalarMul {
         let mut bases = bases_init.skip(bases_stream.len() - scalars_stream.len());
         let step: usize = 1 << 20;
         let mut result = Self::zero();
-        for _ in 0..(scalars_stream.len() + step - 1) / step {
+        for _ in 0..scalars_stream.len().div_ceil(step) {
             let bases_step = (&mut bases)
                 .take(step)
                 .map(|b| *b.borrow())
@@ -119,7 +119,7 @@ fn msm_bigint_wnaf<V: VariableBaseMSM>(
     };
 
     let num_bits = V::ScalarField::MODULUS_BIT_SIZE as usize;
-    let digits_count = (num_bits + c - 1) / c;
+    let digits_count = num_bits.div_ceil(c);
     #[cfg(feature = "parallel")]
     let scalar_digits = scalars
         .into_par_iter()
@@ -281,9 +281,9 @@ fn make_digits(a: &impl BigInteger, w: usize, num_bits: usize) -> impl Iterator<
     } else {
         num_bits
     };
-    let digits_count = (num_bits + w - 1) / w;
+    let digits_count = num_bits.div_ceil(w);
 
-    (0..digits_count).into_iter().map(move |i| {
+    (0..digits_count).map(move |i| {
         // Construct a buffer of bits of the scalar, starting at `bit_offset`.
         let bit_offset = i * w;
         let u64_idx = bit_offset / 64;

ff-asm/src/lib.rs

@@ -59,7 +59,7 @@ pub fn x86_64_asm_mul(input: TokenStream) -> TokenStream {
     } else {
         panic!("The number of limbs must be a literal");
     };
-    if num_limbs <= 6 && num_limbs <= 3 * MAX_REGS {
+    if num_limbs <= 6 {
         let impl_block = generate_impl(num_limbs, true);
 
         let inner_ts: Expr = syn::parse_str(&impl_block).unwrap();
@@ -110,7 +110,7 @@ pub fn x86_64_asm_square(input: TokenStream) -> TokenStream {
     } else {
         panic!("The number of limbs must be a literal");
     };
-    if num_limbs <= 6 && num_limbs <= 3 * MAX_REGS {
+    if num_limbs <= 6 {
         let impl_block = generate_impl(num_limbs, false);
 
         let inner_ts: Expr = syn::parse_str(&impl_block).unwrap();

ff-macros/src/lib.rs

@@ -88,10 +88,10 @@ pub fn unroll_for_loops(args: TokenStream, input: TokenStream) -> TokenStream {
 
     if let Item::Fn(item_fn) = item {
         let new_block = {
-            let &ItemFn {
+            let ItemFn {
                 block: ref box_block,
                 ..
-            } = &item_fn;
+            } = item_fn;
             unroll::unroll_in_block(box_block, unroll_by)
         };
         let new_item = Item::Fn(ItemFn {
@@ -138,7 +138,8 @@ fn test_str_to_limbs() {
             let number = 1i128 << i;
             let signed_number = match sign {
                 Minus => -number,
-                Plus | _ => number,
+                Plus => number,
+                _ => number,
             };
             for base in [2, 8, 16, 10] {
                 let mut string = match base {
@@ -151,10 +152,10 @@ fn test_str_to_limbs() {
                 if sign == Minus {
                     string.insert(0, '-');
                 }
-                let (is_positive, limbs) = utils::str_to_limbs(&format!("{}", string));
+                let (is_positive, limbs) = utils::str_to_limbs(&string.to_string());
                 assert_eq!(
                     limbs[0],
-                    format!("{}u64", signed_number.abs() as u64),
+                    format!("{}u64", signed_number.unsigned_abs() as u64),
                     "{signed_number}, {i}"
                 );
                 if i > 63 {

ff-macros/src/montgomery/mul.rs

@@ -94,8 +94,7 @@ pub(super) fn mul_assign_impl(
                 let mut carry = 0u64;
                 fa::mac(scratch[#i], tmp, #modulus_0, &mut carry);
             });
-            for j in 1..num_limbs {
-                let modulus_j = modulus_limbs[j];
+            for (j, modulus_j) in modulus_limbs.iter().enumerate().take(num_limbs).skip(1) {
                 let k = i + j;
                 body.extend(quote!(scratch[#k] = fa::mac_with_carry(scratch[#k], tmp, #modulus_j, &mut carry);));
             }

ff-macros/src/unroll.rs

@@ -60,7 +60,7 @@ use syn::{
 
 /// Routine to unroll for loops within a block
 pub(crate) fn unroll_in_block(block: &Block, unroll_by: usize) -> Block {
-    let &Block {
+    let Block {
         ref brace_token,
         ref stmts,
     } = block;

ff/src/biginteger/mod.rs

@@ -651,15 +651,11 @@ impl<const N: usize> TryFrom<BigUint> for BigInt<N> {
         } else {
             let mut limbs = [0u64; N];
 
-            bytes
-                .chunks(8)
-                .into_iter()
-                .enumerate()
-                .for_each(|(i, chunk)| {
-                    let mut chunk_padded = [0u8; 8];
-                    chunk_padded[..chunk.len()].copy_from_slice(chunk);
-                    limbs[i] = u64::from_le_bytes(chunk_padded)
-                });
+            bytes.chunks(8).enumerate().for_each(|(i, chunk)| {
+                let mut chunk_padded = [0u8; 8];
+                chunk_padded[..chunk.len()].copy_from_slice(chunk);
+                limbs[i] = u64::from_le_bytes(chunk_padded)
+            });
 
             Ok(Self(limbs))
         }