Rust fixes for some clippy warnings

Clippy lints with instances in the project but NOT applied here, since they seem consistently at odds with the projects' style:
- [unreadable literal](https://rust-lang.github.io/rust-clippy/master/#unreadable_literal)
- [cast lossless](https://rust-lang.github.io/rust-clippy/master/#cast_lossless)
- [assign op pattern](https://rust-lang.github.io/rust-clippy/master/#assign_op_pattern)

benches/dalek_benchmarks.rs

@@ -20,7 +20,7 @@ static MULTISCALAR_SIZES: [usize; 13] = [1, 2, 4, 8, 16, 32, 64, 128, 256, 384,
 
 mod edwards_benches {
     use super::*;
-    use curve25519_dalek::edwards;
+
     use curve25519_dalek::edwards::EdwardsPoint;
 
     fn compress(c: &mut Criterion) {
@@ -47,7 +47,7 @@ mod edwards_benches {
         let B = &constants::ED25519_BASEPOINT_POINT;
         let s = Scalar::from(897987897u64).invert();
         c.bench_function("Constant-time variable-base scalar mul", move |b| {
-            b.iter(|| B * &s)
+            b.iter(|| B * s)
         });
     }
 
@@ -77,7 +77,7 @@ mod edwards_benches {
 
 mod multiscalar_benches {
     use super::*;
-    use curve25519_dalek::edwards;
+
     use curve25519_dalek::edwards::EdwardsPoint;
     use curve25519_dalek::edwards::VartimeEdwardsPrecomputation;
     use curve25519_dalek::traits::MultiscalarMul;

src/backend/serial/scalar_mul/pippenger.rs

@@ -94,7 +94,6 @@ impl VartimeMultiscalarMul for Pippenger {
         // Collect optimized scalars and points in buffers for repeated access
         // (scanning the whole set per digit position).
         let scalars = scalars
-            .into_iter()
             .map(|s| s.borrow().to_radix_2w(w));
 
         let points = points
@@ -158,8 +157,7 @@ impl VartimeMultiscalarMul for Pippenger {
 
         Some(
             columns
-                .fold(hi_column, |total, p| total.mul_by_pow_2(w as u32) + p)
+                .fold(hi_column, |total, p| total.mul_by_pow_2(w as u32) + p),
-                .into(),
         )
     }
 }

src/edwards.rs

@@ -195,7 +195,7 @@ impl CompressedEdwardsY {
         let compressed_sign_bit = Choice::from(self.as_bytes()[31] >> 7);
         X.conditional_negate(compressed_sign_bit);
 
-        Some(EdwardsPoint{ X: X, Y: Y, Z: Z, T: &X * &Y })
+        Some(EdwardsPoint{ X, Y, Z, T: &X * &Y })
     }
 }
 
@@ -449,7 +449,7 @@ impl EdwardsPoint {
         AffineNielsPoint{
             y_plus_x:  &y + &x,
             y_minus_x: &y - &x,
-            xy2d:      xy2d
+            xy2d
         }
     }
 
@@ -810,7 +810,7 @@ impl<'a, 'b> Mul<&'a EdwardsBasepointTable> for &'b Scalar {
     /// Construct an `EdwardsPoint` from a `Scalar` \\(a\\) by
     /// computing the multiple \\(aB\\) of this basepoint \\(B\\).
     fn mul(self, basepoint_table: &'a EdwardsBasepointTable) -> EdwardsPoint {
-        basepoint_table * &self
+        basepoint_table * self
     }
 }
 
@@ -908,7 +908,7 @@ impl EdwardsPoint {
     /// assert_eq!((P+Q).is_torsion_free(), false);
     /// ```
     pub fn is_torsion_free(&self) -> bool {
-        (self * &constants::BASEPOINT_ORDER).is_identity()
+        (self * constants::BASEPOINT_ORDER).is_identity()
     }
 }
 
@@ -1181,7 +1181,7 @@ mod test {
 
         // Test that sum works on owning iterators
         let s = Scalar::from(2u64);
-        let mapped = vec.iter().map(|x| x * &s);
+        let mapped = vec.iter().map(|x| x * s);
         let sum: EdwardsPoint = mapped.sum();
 
         assert_eq!(sum, &P1 * &s + &P2 * &s);
@@ -1204,10 +1204,10 @@ mod test {
     #[test]
     fn is_small_order() {
         // The basepoint has large prime order
-        assert!(constants::ED25519_BASEPOINT_POINT.is_small_order() == false);
+        assert!(!constants::ED25519_BASEPOINT_POINT.is_small_order());
         // constants::EIGHT_TORSION has all points of small order.
         for torsion_point in &constants::EIGHT_TORSION {
-            assert!(torsion_point.is_small_order() == true);
+            assert!(torsion_point.is_small_order());
         }
     }
 
@@ -1219,8 +1219,8 @@ mod test {
 
     #[test]
     fn is_identity() {
-        assert!(   EdwardsPoint::identity().is_identity() == true);
+        assert!(   EdwardsPoint::identity().is_identity());
-        assert!(constants::ED25519_BASEPOINT_POINT.is_identity() == false);
+        assert!(!constants::ED25519_BASEPOINT_POINT.is_identity());
     }
 
     /// Rust's debug builds have overflow and underflow trapping,

src/ristretto.rs

@@ -297,9 +297,9 @@ impl CompressedRistretto {
         let t = &x * &y;
 
         if ok.unwrap_u8() == 0u8 || t.is_negative().unwrap_u8() == 1u8 || y.is_zero().unwrap_u8() == 1u8 {
-            return None;
+            None
         } else {
-            return Some(RistrettoPoint(EdwardsPoint{X: x, Y: y, Z: one, T: t}));
+            Some(RistrettoPoint(EdwardsPoint{X: x, Y: y, Z: one, T: t}))
         }
     }
 }
@@ -529,11 +529,11 @@ impl RistrettoPoint {
                 let eg = &e * &g;
                 let fh = &f * &h;
 
-                BatchCompressState{ e: e, f: f, g: g, h: h, eg: eg, fh: fh }
+                BatchCompressState{ e, f, g, h, eg, fh }
             }
         }
 
-        let states: Vec<BatchCompressState> = points.into_iter().map(|P| BatchCompressState::from(P)).collect();
+        let states: Vec<BatchCompressState> = points.into_iter().map(BatchCompressState::from).collect();
 
         let mut invs: Vec<FieldElement> = states.iter().map(|state| state.efgh()).collect();
 
@@ -847,7 +847,7 @@ impl<'a, 'b> Mul<&'b Scalar> for &'a RistrettoPoint {
     type Output = RistrettoPoint;
     /// Scalar multiplication: compute `scalar * self`.
     fn mul(self, scalar: &'b Scalar) -> RistrettoPoint {
-        RistrettoPoint(&self.0 * scalar)
+        RistrettoPoint(self.0 * scalar)
     }
 }
 
@@ -856,7 +856,7 @@ impl<'a, 'b> Mul<&'b RistrettoPoint> for &'a Scalar {
 
     /// Scalar multiplication: compute `self * scalar`.
     fn mul(self, point: &'b RistrettoPoint) -> RistrettoPoint {
-        RistrettoPoint(self * &point.0)
+        RistrettoPoint(self * point.0)
     }
 }
 
@@ -902,7 +902,7 @@ impl VartimeMultiscalarMul for RistrettoPoint {
     {
         let extended_points = points.into_iter().map(|opt_P| opt_P.map(|P| P.borrow().0));
 
-        EdwardsPoint::optional_multiscalar_mul(scalars, extended_points).map(|P| RistrettoPoint(P))
+        EdwardsPoint::optional_multiscalar_mul(scalars, extended_points).map(RistrettoPoint)
     }
 }
 
@@ -948,7 +948,7 @@ impl VartimePrecomputedMultiscalarMul for VartimeRistrettoPrecomputation {
                 dynamic_scalars,
                 dynamic_points.into_iter().map(|P_opt| P_opt.map(|P| P.0)),
             )
-            .map(|P_ed| RistrettoPoint(P_ed))
+            .map(RistrettoPoint)
     }
 }
 
@@ -1081,7 +1081,7 @@ mod test {
     use scalar::Scalar;
     use constants;
     use edwards::CompressedEdwardsY;
-    use traits::{Identity, ValidityCheck};
+    use traits::{Identity};
     use super::*;
 
     #[test]
@@ -1136,7 +1136,7 @@ mod test {
 
         // Test that sum works on owning iterators
         let s = Scalar::from(2u64);
-        let mapped = vec.iter().map(|x| x * &s);
+        let mapped = vec.iter().map(|x| x * s);
         let sum: RistrettoPoint = mapped.sum();
 
         assert_eq!(sum, &P1 * &s + &P2 * &s);

src/scalar.rs

@@ -202,7 +202,7 @@ impl Scalar {
     /// modulo the group order \\( \ell \\).
     pub fn from_bytes_mod_order(bytes: [u8; 32]) -> Scalar {
         // Temporarily allow s_unreduced.bytes > 2^255 ...
-        let s_unreduced = Scalar{bytes: bytes};
+        let s_unreduced = Scalar{bytes};
 
         // Then reduce mod the group order and return the reduced representative.
         let s = s_unreduced.reduce();
@@ -242,7 +242,7 @@ impl Scalar {
     /// require specific bit-patterns when performing scalar
     /// multiplication.
     pub fn from_bits(bytes: [u8; 32]) -> Scalar {
-        let mut s = Scalar{bytes: bytes};
+        let mut s = Scalar{bytes};
         // Ensure that s < 2^255 by masking the high bit
         s.bytes[31] &= 0b0111_1111;
 
@@ -799,7 +799,7 @@ impl Scalar {
 
         // Pass through the vector backwards to compute the inverses
         // in place
-        for (input, scratch) in inputs.iter_mut().rev().zip(scratch.into_iter().rev()) {
+        for (input, scratch) in inputs.iter_mut().rev().zip(scratch.iter().rev()) {
             let tmp = UnpackedScalar::montgomery_mul(&acc, &input.unpack());
             *input = UnpackedScalar::montgomery_mul(&acc, &scratch).pack();
             acc = tmp;