Add and fix Clippy lints

Cargo.toml

@@ -3,7 +3,7 @@ name = "lenskit"
 version = "2026.3.0-beta1"
 edition = "2024"
 license = "MIT"
-rust-version = "1.87"
+rust-version = "1.89"
 
 [lib]
 name = "lenskit_accel"

hk.pkl

@@ -11,6 +11,7 @@ local linters = new Mapping<String, Step> {
   ["trailing-whitespace"] = Builtins.trailing_whitespace
   // ["check-merge-conflict"] = Builtins.check_merge_conflict
   ["check-toml"] = Builtins.taplo
+  ["clippy"] = Builtins.cargo_clippy
   ["ruff"] = Builtins.ruff
 }
 

rust-toolchain.toml

@@ -1,3 +1,3 @@
 [toolchain]
 channel = "stable"
-components = ["rustfmt", "cargo", "rustc", "llvm-tools"]
+components = ["rustfmt", "cargo", "rustc", "llvm-tools", "clippy"]

src/accel/als/explicit.rs

@@ -12,7 +12,6 @@ use ndarray::{Array1, ArrayBase, ArrayView2, Axis, ViewRepr};
 use numpy::{Ix1, PyArray2, PyArrayMethods};
 use pyo3::{IntoPyObjectExt, exceptions::PyRuntimeError, prelude::*};
 use rayon::prelude::*;
-use thiserror::Error;
 
 use rayon_cancel::CancelAdapter;
 
@@ -89,13 +88,13 @@ fn train_row_solve(
     let cols = matrix.row_cols(row_num);
     let vals = matrix.row_vals(row_num);
 
-    if cols.len() == 0 {
+    if cols.is_empty() {
         row_data.fill(0.0);
         return Ok(0.0);
     }
 
     let cols: Vec<_> = cols.iter().map(|c| *c as usize).collect();
-    let vals: Array1<_> = vals.iter().map(|f| *f).collect();
+    let vals: Array1<_> = vals.iter().copied().collect();
 
     let nd = row_data.len();
 

src/accel/als/implicit.rs

@@ -95,13 +95,13 @@ fn train_row_solve(
     let cols = matrix.row_cols(row_num);
     let vals = matrix.row_vals(row_num);
 
-    if cols.len() == 0 {
+    if cols.is_empty() {
         row_data.fill(0.0);
         return Ok(0.0);
     }
 
     let cols: Vec<_> = cols.iter().map(|c| *c as usize).collect();
-    let mut vals: Array1<_> = vals.iter().map(|f| *f).collect();
+    let mut vals: Array1<_> = vals.iter().copied().collect();
 
     let nd = row_data.len();
 

src/accel/als/solve.rs

@@ -38,6 +38,7 @@ pub enum SolveError {
 
 /// Wrapper for LAPACK solver functions.
 #[derive(Clone, Copy)]
+#[allow(clippy::upper_case_acronyms)]
 pub struct POSV {
     lapack_fn: LapackSPOSV,
 }
@@ -105,8 +106,8 @@ impl POSV {
     }
 }
 
-impl Into<PyErr> for SolveError {
-    fn into(self) -> PyErr {
-        PyRuntimeError::new_err(format!("LAPACK error: {}", self))
+impl From<SolveError> for PyErr {
+    fn from(val: SolveError) -> Self {
+        PyRuntimeError::new_err(format!("LAPACK error: {}", val))
     }
 }

src/accel/arrow/lists.rs

@@ -47,6 +47,6 @@ impl ExtractListArray for LargeListArray {
 
 impl ExtractListArray for ListArray {
     fn extract_list_array(array: &dyn Array) -> Option<Self> {
-        array.as_any().downcast_ref::<Self>().map(Clone::clone)
+        array.as_any().downcast_ref::<Self>().cloned()
     }
 }

src/accel/arrow/mod.rs

@@ -45,9 +45,9 @@ pub fn checked_array_ref<'array, T: Array + 'static>(
     )
 }
 
-pub fn checked_array<'array, E: ArrowPrimitiveType + 'static>(
+pub fn checked_array<E: ArrowPrimitiveType + 'static>(
     name: &str,
-    array: &'array dyn Array,
+    array: &dyn Array,
 ) -> PyResult<PrimitiveArray<E>> {
     if array.data_type().equals_datatype(&E::DATA_TYPE) {
         Ok(downcast_array(array))

src/accel/arrow/types/index_list.rs

@@ -49,7 +49,7 @@ impl TryFrom<&DataType> for SparseIndexListType {
     type Error = ArrowError;
 
     fn try_from(value: &DataType) -> Result<Self, Self::Error> {
-        Self::try_new(&value, ())
+        Self::try_new(value, ())
     }
 }
 

src/accel/arrow/types/row.rs

@@ -52,7 +52,7 @@ impl TryFrom<&DataType> for SparseRowType {
     type Error = ArrowError;
 
     fn try_from(value: &DataType) -> Result<Self, Self::Error> {
-        Self::try_new(&value, ())
+        Self::try_new(value, ())
     }
 }
 
@@ -126,7 +126,7 @@ impl ExtensionType for SparseRowType {
             )));
         }
 
-        let idx_f = fields.get(0).unwrap();
+        let idx_f = fields.first().unwrap();
         let idx_name = idx_f.name();
         let idx_t: SparseIndexType = idx_f.try_extension_type()?;
 

src/accel/data/cooc.rs

@@ -201,10 +201,9 @@ fn count_cooc_parallel<PC: ConcurrentPairCounter>(
         let n = items.len();
 
         for i in 0..n {
-            let ri = items[i as usize];
-            for j in i..n {
-                let ci = items[j as usize];
-                counts.crecord(ri, ci);
+            let ri = items[i];
+            for ci in &items[i..n] {
+                counts.crecord(ri, *ci);
             }
         }
         cancel.advance(items.len());
@@ -239,12 +238,9 @@ fn compute_group_pointers(n_groups: usize, gvals: &[i32]) -> PyResult<Vec<usize>
 fn count_items<PC: PairCounter>(counts: &mut PC, items: &[i32]) {
     let n = items.len();
     for i in 0..n {
-        let ri = items[i as usize];
-        for j in (i + 1)..n {
-            if i != j {
-                let ci = items[j as usize];
-                counts.record(ri, ci);
-            }
+        let ri = items[i];
+        for ci in &items[(i + 1)..n] {
+            counts.record(ri, *ci);
         }
     }
 }

src/accel/data/coordinates.rs

@@ -231,7 +231,7 @@ impl ChunkIndex {
 
 fn hash_entry(chunks: &[Vec<Int32Array>], ix: &ChunkIndex) -> u64 {
     let chunk = &chunks[ix.chunk_index()];
-    hash_chunk_entry(&chunk, ix.item)
+    hash_chunk_entry(chunk, ix.item)
 }
 
 fn hash_chunk_entry(chunk: &[Int32Array], ri: u32) -> u64 {

src/accel/data/index.rs

@@ -62,7 +62,7 @@ impl IDIndex {
     fn from_data(data: PyArrowType<ArrayData>) -> PyResult<Self> {
         let ids = make_array(data.0);
         let index: Box<dyn PositionLookup + Sync + Send> = match ids.data_type() {
-            DataType::Null if ids.len() == 0 => return Ok(Self::empty()),
+            DataType::Null if ids.is_empty() => return Ok(Self::empty()),
             DataType::Int16 => prim_tbl::<Int16Type>(&ids)?,
             DataType::UInt16 => prim_tbl::<UInt16Type>(&ids)?,
             DataType::Int32 => prim_tbl::<Int32Type>(&ids)?,

src/accel/data/mod.rs

@@ -74,5 +74,5 @@ fn hash_array(arr: PyArrowType<ArrayData>) -> PyResult<String> {
         start += bsize;
     }
 
-    Ok(hex::encode(&hash.finalize()))
+    Ok(hex::encode(hash.finalize()))
 }

src/accel/data/pairs/dense.rs

@@ -22,6 +22,7 @@ pub struct DensePairCounter {
 }
 
 impl DensePairCounter {
+    #[allow(clippy::missing_transmute_annotations)]
     pub fn with_diagonal(n: usize, diagonal: bool) -> Self {
         DensePairCounter {
             n_items: n,
@@ -67,10 +68,9 @@ impl PairCounter for DensePairCounter {
         let data: Vec<f32> = unsafe { transmute(data) };
 
         let arr = Array1::from_vec(data);
-        let mat = arr
-            .into_shape_with_order((self.n_items, self.n_items))
-            .expect("array reshape failed");
-        mat
+
+        arr.into_shape_with_order((self.n_items, self.n_items))
+            .expect("array reshape failed")
     }
 }
 

src/accel/data/pairs/symmetric.rs

@@ -26,6 +26,7 @@ pub struct SymmetricPairCounter {
 }
 
 impl SymmetricPairCounter {
+    #[allow(clippy::missing_transmute_annotations)]
     pub fn with_diagonal(n: usize, diagonal: bool) -> Self {
         let cap = arith_tot(n);
         SymmetricPairCounter {

src/accel/data/sampling.rs

@@ -16,6 +16,7 @@ use crate::data::CoordinateTable;
 /// Sample negative columns for given rows from a coordinate table.
 #[pyfunction]
 #[pyo3(signature=(coords, rows, n_cols, *, n=1, max_attempts=10, pop_weighted=false, seed))]
+#[allow(clippy::too_many_arguments)]
 pub fn sample_negatives<'py>(
     py: Python<'py>,
     coords: &CoordinateTable,

src/accel/data/scatter.rs

@@ -86,8 +86,8 @@ fn scatter_empty_stype<T: ArrowPrimitiveType>(
 }
 
 fn scatter_impl<Ix, T>(
-    dst: &mut Vec<T::Native>,
-    dst_valid: &mut Vec<bool>,
+    dst: &mut [T::Native],
+    dst_valid: &mut [bool],
     idx: &PrimitiveArray<Ix>,
     src: &PrimitiveArray<T>,
 ) where

src/accel/data/sorting.rs

@@ -51,11 +51,11 @@ pub(super) fn is_sorted_coo<'py>(
             let v1 = col1.value(i);
             let v2 = col2.value(i);
             let k = (v1, v2);
-            if let Some(lk) = last {
-                if k <= lk {
-                    // found a key out-of-order, we're done
-                    return Ok(false);
-                }
+            if let Some(lk) = last
+                && k <= lk
+            {
+                // found a key out-of-order, we're done
+                return Ok(false);
             }
             last = Some(k);
         }
@@ -90,10 +90,10 @@ where
 
     let mut indices = Vec::with_capacity(scores.len());
     for (i, v) in scores.iter().enumerate() {
-        if let Some(v) = v {
-            if !v.is_nan() {
-                indices.push(i as i32);
-            }
+        if let Some(v) = v
+            && !v.is_nan()
+        {
+            indices.push(i as i32);
         }
     }
 

src/accel/data/transpose.rs

@@ -17,6 +17,7 @@ use crate::sparse::{CSR, CSRStructure, IxVar, csr_structure};
 
 /// Transpose the structure of a CSR matrix.
 #[pyfunction]
+#[allow(clippy::type_complexity)]
 pub fn transpose_csr(
     arr: PyArrowType<ArrayData>,
     permute: bool,
@@ -55,8 +56,7 @@ where
     let nnz = csr.nnz();
     let mut row_ptrs = Vec::with_capacity(csr.n_cols + 1);
     row_ptrs.resize(csr.n_cols + 1, It::Native::from(0));
-    let mut col_inds = Vec::with_capacity(nnz);
-    col_inds.resize(nnz, 0);
+    let mut col_inds = vec![0; nnz];
     let mut permutation = if permute {
         let mut p = Vec::with_capacity(nnz);
         p.resize(nnz, It::Native::from(0));

src/accel/indirect/hashing/table.rs

@@ -101,7 +101,7 @@ impl<C: IndirectHashContent> PositionLookup for IndirectHashTable<C> {
         let res = self
             .table
             .find(hash, |jr| search.compare_with_entry(0, *jr));
-        Ok(res.map(|ir| *ir))
+        Ok(res.copied())
     }
 
     fn lookup_array<'py>(&self, py: Python<'py>, val: Bound<'py, PyAny>) -> PyResult<Int32Array> {