Minor clean up (#5284)

This PR performs minor code cleanup to reduce verbosity. Since the
compiler has already optimized out indirect calls in the existing code,
these changes improve readability but do not affect performance.

---------

Co-authored-by: Bastian Köcher <git@kchr.de>

prdoc/pr_5284.prdoc

@@ -0,0 +1,7 @@
+title: Minor clean up
+author: conr2d
+topic: runtime
+
+crates:
+  - name: sp-runtime
+    bump: none

substrate/primitives/runtime/src/lib.rs

@@ -438,34 +438,25 @@ impl TryFrom<MultiSigner> for ecdsa::Public {
 #[cfg(feature = "std")]
 impl std::fmt::Display for MultiSigner {
 	fn fmt(&self, fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
-		match *self {
-			Self::Ed25519(ref who) => write!(fmt, "ed25519: {}", who),
-			Self::Sr25519(ref who) => write!(fmt, "sr25519: {}", who),
-			Self::Ecdsa(ref who) => write!(fmt, "ecdsa: {}", who),
+		match self {
+			Self::Ed25519(who) => write!(fmt, "ed25519: {}", who),
+			Self::Sr25519(who) => write!(fmt, "sr25519: {}", who),
+			Self::Ecdsa(who) => write!(fmt, "ecdsa: {}", who),
 		}
 	}
 }
 
 impl Verify for MultiSignature {
 	type Signer = MultiSigner;
 	fn verify<L: Lazy<[u8]>>(&self, mut msg: L, signer: &AccountId32) -> bool {
-		match (self, signer) {
-			(Self::Ed25519(ref sig), who) => match ed25519::Public::from_slice(who.as_ref()) {
-				Ok(signer) => sig.verify(msg, &signer),
-				Err(()) => false,
-			},
-			(Self::Sr25519(ref sig), who) => match sr25519::Public::from_slice(who.as_ref()) {
-				Ok(signer) => sig.verify(msg, &signer),
-				Err(()) => false,
-			},
-			(Self::Ecdsa(ref sig), who) => {
+		let who: [u8; 32] = *signer.as_ref();
+		match self {
+			Self::Ed25519(sig) => sig.verify(msg, &who.into()),
+			Self::Sr25519(sig) => sig.verify(msg, &who.into()),
+			Self::Ecdsa(sig) => {
 				let m = sp_io::hashing::blake2_256(msg.get());
-				match sp_io::crypto::secp256k1_ecdsa_recover_compressed(sig.as_ref(), &m) {
-					Ok(pubkey) =>
-						&sp_io::hashing::blake2_256(pubkey.as_ref()) ==
-							<dyn AsRef<[u8; 32]>>::as_ref(who),
-					_ => false,
-				}
+				sp_io::crypto::secp256k1_ecdsa_recover_compressed(sig.as_ref(), &m)
+					.map_or(false, |pubkey| sp_io::hashing::blake2_256(&pubkey) == who)
 			},
 		}
 	}