diff --git a/src/aggregation/bucket/range.rs b/src/aggregation/bucket/range.rs
index 08fd6e5cf..465022171 100644
--- a/src/aggregation/bucket/range.rs
+++ b/src/aggregation/bucket/range.rs
@@ -240,17 +240,15 @@ impl SegmentRangeCollector {
 /// more computational expensive when many documents are hit.
 fn to_u64_range(range: &RangeAggregationRange, field_type: &Type) -> crate::Result<Range<u64>> {
     let start = if let Some(from) = range.from {
-        f64_to_fastfield_u64(from, field_type).ok_or::<TantivyError>(
-            TantivyError::InvalidArgument("invalid field type".to_string()),
-        )?
+        f64_to_fastfield_u64(from, field_type)
+            .ok_or_else(|| TantivyError::InvalidArgument("invalid field type".to_string()))?
     } else {
         u64::MIN
     };
 
     let end = if let Some(to) = range.to {
-        f64_to_fastfield_u64(to, field_type).ok_or::<TantivyError>(
-            TantivyError::InvalidArgument("invalid field type".to_string()),
-        )?
+        f64_to_fastfield_u64(to, field_type)
+            .ok_or_else(|| TantivyError::InvalidArgument("invalid field type".to_string()))?
     } else {
         u64::MAX
     };
diff --git a/src/aggregation/collector.rs b/src/aggregation/collector.rs
index 11f898423..ec581d6a7 100644
--- a/src/aggregation/collector.rs
+++ b/src/aggregation/collector.rs
@@ -124,7 +124,7 @@ impl AggregationSegmentCollector {
         agg: &Aggregations,
         reader: &SegmentReader,
     ) -> crate::Result<Self> {
-        let aggs_with_accessor = get_aggs_with_accessor_and_validate(&agg, reader)?;
+        let aggs_with_accessor = get_aggs_with_accessor_and_validate(agg, reader)?;
         let result =
             SegmentAggregationResultsCollector::from_req_and_validate(&aggs_with_accessor)?;
         Ok(AggregationSegmentCollector {
diff --git a/src/aggregation/metric/stats.rs b/src/aggregation/metric/stats.rs
index 02003e415..b596cd7a5 100644
--- a/src/aggregation/metric/stats.rs
+++ b/src/aggregation/metric/stats.rs
@@ -87,11 +87,8 @@ impl IntermediateStats {
     }
 
     pub(crate) fn standard_deviation(&self) -> Option<f64> {
-        if let Some(average) = self.avg() {
-            Some((self.square_mean() - average * average).sqrt())
-        } else {
-            None
-        }
+        self.avg()
+            .map(|average| (self.square_mean() - average * average).sqrt())
     }
 
     /// Merge data from other stats into this instance.
diff --git a/src/aggregation/mod.rs b/src/aggregation/mod.rs
index 26ff8b090..d4f77fa94 100644
--- a/src/aggregation/mod.rs
+++ b/src/aggregation/mod.rs
@@ -918,8 +918,8 @@ mod tests {
             let collector = AggregationCollector::from_aggs(agg_req_1);
 
             let searcher = reader.searcher();
-            let agg_res = searcher.search(&AllQuery, &collector).unwrap_err();
-            agg_res
+
+            searcher.search(&AllQuery, &collector).unwrap_err()
         };
 
         let agg_res = avg_on_field("text");
diff --git a/src/query/boolean_query/block_wand.rs b/src/query/boolean_query/block_wand.rs
index ed97e8cfc..92bb2e8b1 100644
--- a/src/query/boolean_query/block_wand.rs
+++ b/src/query/boolean_query/block_wand.rs
@@ -47,7 +47,7 @@ fn find_pivot_doc(
 /// scorer in scorers[..pivot_len] and `scorer.doc()` for scorer in scorers[pivot_len..].
 /// Note: before and after calling this method, scorers need to be sorted by their `.doc()`.
 fn block_max_was_too_low_advance_one_scorer(
-    scorers: &mut Vec<TermScorerWithMaxScore>,
+    scorers: &mut [TermScorerWithMaxScore],
     pivot_len: usize,
 ) {
     debug_assert!(is_sorted(scorers.iter().map(|scorer| scorer.doc())));
@@ -82,7 +82,7 @@ fn block_max_was_too_low_advance_one_scorer(
 // Given a list of term_scorers and a `ord` and assuming that `term_scorers[ord]` is sorted
 // except term_scorers[ord] that might be in advance compared to its ranks,
 // bubble up term_scorers[ord] in order to restore the ordering.
-fn restore_ordering(term_scorers: &mut Vec<TermScorerWithMaxScore>, ord: usize) {
+fn restore_ordering(term_scorers: &mut [TermScorerWithMaxScore], ord: usize) {
     let doc = term_scorers[ord].doc();
     for i in ord + 1..term_scorers.len() {
         if term_scorers[i].doc() >= doc {
diff --git a/src/tokenizer/ascii_folding_filter.rs b/src/tokenizer/ascii_folding_filter.rs
index 542519e12..3e800971b 100644
--- a/src/tokenizer/ascii_folding_filter.rs
+++ b/src/tokenizer/ascii_folding_filter.rs
@@ -1527,7 +1527,7 @@ fn fold_non_ascii_char(c: char) -> Option<&'static str> {
 }
 
 // https://github.com/apache/lucene-solr/blob/master/lucene/analysis/common/src/java/org/apache/lucene/analysis/miscellaneous/ASCIIFoldingFilter.java#L187
-fn to_ascii(text: &mut String, output: &mut String) {
+fn to_ascii(text: &str, output: &mut String) {
     output.clear();
 
     for c in text.chars() {
diff --git a/src/tokenizer/lower_caser.rs b/src/tokenizer/lower_caser.rs
index 3373948e3..2136b0063 100644
--- a/src/tokenizer/lower_caser.rs
+++ b/src/tokenizer/lower_caser.rs
@@ -22,7 +22,7 @@ pub struct LowerCaserTokenStream<'a> {
 }
 
 // writes a lowercased version of text into output.
-fn to_lowercase_unicode(text: &mut String, output: &mut String) {
+fn to_lowercase_unicode(text: &str, output: &mut String) {
     output.clear();
     for c in text.chars() {
         // Contrary to the std, we do not take care of sigma special case.