chacha20_poly1305: add clippy::use_self lint

diff --git a/chacha20_poly1305/Cargo.toml b/chacha20_poly1305/Cargo.toml
index 57b19bd2..5b1f15cf 100644
--- a/chacha20_poly1305/Cargo.toml
+++ b/chacha20_poly1305/Cargo.toml
@@ -26,3 +26,6 @@ rustdoc-args = ["--cfg", "docsrs"]
 
 [lints.rust]
 unexpected_cfgs = { level = "deny", check-cfg = ['cfg(bench)'] }
+
+[lints.clippy]
+use_self = "warn"
diff --git a/chacha20_poly1305/src/chacha20.rs b/chacha20_poly1305/src/chacha20.rs
index 16664f70..13c4f5f4 100644
--- a/chacha20_poly1305/src/chacha20.rs
+++ b/chacha20_poly1305/src/chacha20.rs
@@ -19,7 +19,7 @@ pub struct Key([u8; 32]);
 
 impl Key {
     /// Constructs a new key.
-    pub const fn new(key: [u8; 32]) -> Self { Key(key) }
+    pub const fn new(key: [u8; 32]) -> Self { Self(key) }
 }
 
 /// A 96-bit initialization vector (IV), or nonce.
@@ -28,7 +28,7 @@ pub struct Nonce([u8; 12]);
 
 impl Nonce {
     /// Constructs a new nonce.
-    pub const fn new(nonce: [u8; 12]) -> Self { Nonce(nonce) }
+    pub const fn new(nonce: [u8; 12]) -> Self { Self(nonce) }
 }
 
 // Const validation trait for compile time check with max of 3.
@@ -74,7 +74,7 @@ impl U32x4 {
         (0..4).for_each(|i| {
             result[i] = self.0[i].wrapping_add(rhs.0[i]);
         });
-        U32x4(result)
+        Self(result)
     }
 
     #[inline(always)]
@@ -83,7 +83,7 @@ impl U32x4 {
         (0..4).for_each(|i| {
             result[i] = self.0[i].rotate_left(n);
         });
-        U32x4(result)
+        Self(result)
     }
 
     #[inline(always)]
@@ -92,9 +92,9 @@ impl U32x4 {
         (): UpTo3<N>,
     {
         match N {
-            1 => U32x4([self.0[1], self.0[2], self.0[3], self.0[0]]),
-            2 => U32x4([self.0[2], self.0[3], self.0[0], self.0[1]]),
-            3 => U32x4([self.0[3], self.0[0], self.0[1], self.0[2]]),
+            1 => Self([self.0[1], self.0[2], self.0[3], self.0[0]]),
+            2 => Self([self.0[2], self.0[3], self.0[0], self.0[1]]),
+            3 => Self([self.0[3], self.0[0], self.0[1], self.0[2]]),
             _ => self, // Rotate by 0 is a no-op.
         }
     }
@@ -105,9 +105,9 @@ impl U32x4 {
         (): UpTo3<N>,
     {
         match N {
-            1 => U32x4([self.0[3], self.0[0], self.0[1], self.0[2]]),
-            2 => U32x4([self.0[2], self.0[3], self.0[0], self.0[1]]),
-            3 => U32x4([self.0[1], self.0[2], self.0[3], self.0[0]]),
+            1 => Self([self.0[3], self.0[0], self.0[1], self.0[2]]),
+            2 => Self([self.0[2], self.0[3], self.0[0], self.0[1]]),
+            3 => Self([self.0[1], self.0[2], self.0[3], self.0[0]]),
             _ => self, // Rotate by 0 is a no-op.
         }
     }
@@ -131,7 +131,7 @@ impl BitXor for U32x4 {
         (0..4).for_each(|i| {
             result[i] = self.0[i] ^ rhs.0[i];
         });
-        U32x4(result)
+        Self(result)
     }
 }
 
@@ -165,7 +165,7 @@ impl State {
         let n1 = u32::from_le_bytes([nonce.0[4], nonce.0[5], nonce.0[6], nonce.0[7]]);
         let n2 = u32::from_le_bytes([nonce.0[8], nonce.0[9], nonce.0[10], nonce.0[11]]);
 
-        State {
+        Self {
             matrix: [
                 U32x4([WORD_1, WORD_2, WORD_3, WORD_4]),
                 U32x4([k0, k1, k2, k3]),
@@ -268,12 +268,12 @@ impl ChaCha20 {
     pub const fn new(key: Key, nonce: Nonce, seek: u32) -> Self {
         let block_count = seek / 64;
         let seek_offset_bytes = (seek % 64) as usize;
-        ChaCha20 { key, nonce, block_count, seek_offset_bytes }
+        Self { key, nonce, block_count, seek_offset_bytes }
     }
 
     /// Make a new instance of ChaCha20 from a block in the keystream.
     pub const fn new_from_block(key: Key, nonce: Nonce, block: u32) -> Self {
-        ChaCha20 { key, nonce, block_count: block, seek_offset_bytes: 0 }
+        Self { key, nonce, block_count: block, seek_offset_bytes: 0 }
     }
 
     /// Gets the keystream for a specific block.
diff --git a/chacha20_poly1305/src/lib.rs b/chacha20_poly1305/src/lib.rs
index cb887a36..88283d4b 100644
--- a/chacha20_poly1305/src/lib.rs
+++ b/chacha20_poly1305/src/lib.rs
@@ -43,7 +43,7 @@ pub enum Error {
 impl fmt::Display for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Error::UnauthenticatedAdditionalData => write!(f, "Unauthenticated aad."),
+            Self::UnauthenticatedAdditionalData => write!(f, "Unauthenticated aad."),
         }
     }
 }
@@ -52,7 +52,7 @@ impl fmt::Display for Error {
 impl std::error::Error for Error {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match self {
-            Error::UnauthenticatedAdditionalData => None,
+            Self::UnauthenticatedAdditionalData => None,
         }
     }
 }
@@ -65,7 +65,7 @@ pub struct ChaCha20Poly1305 {
 
 impl ChaCha20Poly1305 {
     /// Make a new instance of a ChaCha20Poly1305 AEAD.
-    pub const fn new(key: Key, nonce: Nonce) -> Self { ChaCha20Poly1305 { key, nonce } }
+    pub const fn new(key: Key, nonce: Nonce) -> Self { Self { key, nonce } }
 
     /// Encrypt content in place and return the Poly1305 16-byte authentication tag.
     ///
diff --git a/chacha20_poly1305/src/poly1305.rs b/chacha20_poly1305/src/poly1305.rs
index c34ba3f8..cf560bd0 100644
--- a/chacha20_poly1305/src/poly1305.rs
+++ b/chacha20_poly1305/src/poly1305.rs
@@ -41,7 +41,7 @@ impl Poly1305 {
         let s2 = u32::from_le_bytes([key[24], key[25], key[26], key[27]]);
         let s3 = u32::from_le_bytes([key[28], key[29], key[30], key[31]]);
 
-        Poly1305 {
+        Self {
             r: [r0, r1, r2, r3, r4],
             s: [s0, s1, s2, s3],
             acc: [0; 5],