Fix clippy warnings (#1385)

## Issue Addressed

NA

## Proposed Changes

Fixes most clippy warnings and ignores the rest of them, see issue #1388.

crypto/bls/src/signature_set.rs

@@ -60,7 +60,7 @@ type VerifySet<'a> = (
 );
 
 #[cfg(not(feature = "fake_crypto"))]
-pub fn verify_signature_sets<'a>(sets: Vec<SignatureSet>) -> bool {
+pub fn verify_signature_sets(sets: Vec<SignatureSet>) -> bool {
     let rng = &mut rand::thread_rng();
     let verify_set: Vec<VerifySet> = sets
         .iter()

crypto/eth2_key_derivation/src/derived_key.rs

@@ -81,7 +81,7 @@ fn derive_child_sk(parent_sk: &[u8], index: u32) -> SecretHash {
 ///
 /// Equivalent to `HKDF_mod_r` in EIP-2333.
 fn hkdf_mod_r(ikm: &[u8]) -> SecretHash {
-    let prk = hkdf_extract("BLS-SIG-KEYGEN-SALT-".as_bytes(), ikm);
+    let prk = hkdf_extract(b"BLS-SIG-KEYGEN-SALT-", ikm);
     let okm = &hkdf_expand(prk, MOD_R_L);
     mod_r(okm.as_bytes())
 }

crypto/eth2_key_derivation/src/plain_text.rs

@@ -16,6 +16,11 @@ impl PlainText {
         self.0.len()
     }
 
+    /// Checks whether `self` is empty
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
+
     /// Returns a reference to the underlying bytes.
     pub fn as_bytes(&self) -> &[u8] {
         &self.0

crypto/eth2_keystore/src/json_keystore/hex_bytes.rs

@@ -14,6 +14,10 @@ impl HexBytes {
     pub fn len(&self) -> usize {
         self.0.len()
     }
+
+    pub fn is_empty(&self) -> bool {
+        self.0.is_empty()
+    }
 }
 
 impl From<Vec<u8>> for HexBytes {

crypto/eth2_keystore/src/json_keystore/kdf_module.rs

@@ -66,7 +66,7 @@ pub enum Prf {
 impl Prf {
     pub fn mac(&self, password: &[u8]) -> impl Mac {
         match &self {
-            _hmac_sha256 => {
+            Prf::HmacSha256 => {
                 Hmac::<Sha256>::new_varkey(password).expect("Could not derive HMAC using SHA256.")
             }
         }

crypto/eth2_keystore/src/keystore.rs

@@ -409,10 +409,10 @@ fn derive_key(password: &[u8], kdf: &Kdf) -> Result<DerivedKey, Error> {
                 password,
                 params.salt.as_bytes(),
                 &ScryptParams::new(log2_int(params.n) as u8, params.r, params.p)
-                    .map_err(|e| Error::ScryptInvalidParams(e))?,
+                    .map_err(Error::ScryptInvalidParams)?,
                 dk.as_mut_bytes(),
             )
-            .map_err(|e| Error::ScryptInvaidOutputLen(e))?;
+            .map_err(Error::ScryptInvaidOutputLen)?;
         }
     }