Add clippy to CI, address some non-default lints

.github/workflows/ci.yml

@@ -37,3 +37,12 @@ jobs:
           components: rustfmt
       - name: cargo fmt --check
         run: cargo fmt --all -- --check
+
+  clippy:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy
+      - run: cargo clippy --all --all-targets -- --deny warnings

src/fnv.rs

@@ -14,7 +14,7 @@ pub struct Hasher {
 
 impl Default for Hasher {
     fn default() -> Self {
-        Hasher { state: BASIS }
+        Self { state: BASIS }
     }
 }
 

src/lib.rs

@@ -26,8 +26,8 @@
 //!
 //! This crate provides implementations of the following 32-bit hashing algorithms:
 //!
-//! - [Fowler-Noll-Vo](struct.FnvHasher.html)
-//! - [MurmurHash3](struct.Murmur3Hasher.html)
+//! - [`FnvHasher`] Fowler-Noll-Vo 1a
+//! - [`Murmur3Hasher`] `MurmurHash3`
 //!
 //! # Generic code
 //!
@@ -48,6 +48,12 @@
 
 #![deny(missing_docs)]
 #![deny(warnings)]
+#![warn(
+    clippy::use_self,
+    clippy::doc_markdown,
+    clippy::ptr_as_ptr,
+    clippy::trivially_copy_pass_by_ref
+)]
 #![no_std]
 
 use core::fmt;
@@ -72,20 +78,20 @@ pub struct BuildHasherDefault<H> {
 
 impl<H> Default for BuildHasherDefault<H> {
     fn default() -> Self {
-        BuildHasherDefault {
+        Self {
             _marker: PhantomData,
         }
     }
 }
 
 impl<H> Clone for BuildHasherDefault<H> {
     fn clone(&self) -> Self {
-        BuildHasherDefault::default()
+        Self::default()
     }
 }
 
 impl<H> PartialEq for BuildHasherDefault<H> {
-    fn eq(&self, _other: &BuildHasherDefault<H>) -> bool {
+    fn eq(&self, _other: &Self) -> bool {
         true
     }
 }
@@ -101,7 +107,7 @@ impl<H> fmt::Debug for BuildHasherDefault<H> {
 impl<H> BuildHasherDefault<H> {
     /// `const` constructor
     pub const fn new() -> Self {
-        BuildHasherDefault {
+        Self {
             _marker: PhantomData,
         }
     }

src/murmur3.rs

@@ -3,7 +3,7 @@ use core::slice;
 
 use crate::Hasher as _;
 
-/// 32-bit MurmurHash3 hasher
+/// 32-bit `MurmurHash3` hasher
 pub struct Hasher {
     buf: Buffer,
     index: Index,
@@ -28,23 +28,23 @@ enum Index {
 }
 
 impl Index {
-    fn usize(&self) -> usize {
-        match *self {
-            Index::_0 => 0,
-            Index::_1 => 1,
-            Index::_2 => 2,
-            Index::_3 => 3,
+    fn usize(self) -> usize {
+        match self {
+            Self::_0 => 0,
+            Self::_1 => 1,
+            Self::_2 => 2,
+            Self::_3 => 3,
         }
     }
 }
 
 impl From<usize> for Index {
     fn from(x: usize) -> Self {
         match x % 4 {
-            0 => Index::_0,
-            1 => Index::_1,
-            2 => Index::_2,
-            3 => Index::_3,
+            0 => Self::_0,
+            1 => Self::_1,
+            2 => Self::_2,
+            3 => Self::_3,
             _ => unreachable!(),
         }
     }
@@ -75,7 +75,7 @@ impl Hasher {
 impl Default for Hasher {
     #[allow(deprecated)]
     fn default() -> Self {
-        Hasher {
+        Self {
             buf: Buffer {
                 bytes: MaybeUninit::uninit(),
             },
@@ -176,7 +176,7 @@ impl core::hash::Hasher for Hasher {
         for block in body.chunks(4) {
             if block.len() == 4 {
                 self.state
-                    .process_block(unsafe { &*(block.as_ptr() as *const _) });
+                    .process_block(unsafe { &*(block.as_ptr().cast()) });
             } else {
                 // NOTE(unsafe) In this branch, `block.len() < 4`. For CASE 1 and CASE 2 above,
                 // `self.index.usize()` will be 0 here, so `self.index.usize() + block.len() < 4`.
@@ -209,6 +209,7 @@ const C2: u32 = 0x1b873593;
 const R1: u32 = 15;
 
 impl State {
+    #[allow(clippy::trivially_copy_pass_by_ref)]
     fn process_block(&mut self, block: &MaybeUninit<[u8; 4]>) {
         self.0 ^= pre_mix(u32::from_le_bytes(unsafe { *block.assume_init_ref() }));
         self.0 = self.0.rotate_left(13);