apache · emilk · Sep 1, 2026 · Sep 1, 2026 · Sep 1, 2026
diff --git a/Cargo.toml b/Cargo.toml
@@ -283,12 +283,10 @@ explicit_iter_loop = "allow"                 # 189 hits
 float_cmp = "allow"                          # 8 hits; exact float comparisons are often intentional here
 from_iter_instead_of_collect = "allow"       # 51 hits
 if_not_else = "allow"                        # 133 hits
-ignored_unit_patterns = "allow"              # 52 hits
 implicit_clone = "allow"                     # 198 hits
 implicit_hasher = "allow"                    # 17 hits; some sites feed arrow APIs that require the default hasher
 inline_always = "allow"                      # 45 hits
 items_after_statements = "allow"             # 171 hits
-manual_string_new = "allow"                  # 84 hits
 many_single_char_names = "allow"             # 12 hits; short names are idiomatic in the numeric kernels
 map_unwrap_or = "allow"                      # 198 hits
 match_bool = "allow"                         # 46 hits
@@ -300,7 +298,6 @@ missing_panics_doc = "allow"                 # 244 hits
 must_use_candidate = "allow"                 # 2726 hits
 needless_raw_string_hashes = "allow"         # 540 hits
 redundant_closure_for_method_calls = "allow" # 686 hits
-redundant_else = "allow"                     # 48 hits
 return_self_not_must_use = "allow"           # 644 hits
 semicolon_if_nothing_returned = "allow"      # 1353 hits
 similar_names = "allow"                      # 228 hits; too many false positives, e.g. `expr`/`exprs`

diff --git a/benchmarks/src/cancellation.rs b/benchmarks/src/cancellation.rs
@@ -127,12 +127,12 @@ fn run_test(wait_time: u64, store: Arc<dyn ObjectStore>) -> Result<Duration> {
                 let store = Arc::clone(&store);
                 tokio::select! {
                     biased;
-                    _ = async move {
+                    () = async move {
                         datafusion(store).await.unwrap();
                     } => {
                         println!("matched case doing work");
                     },
-                    _ = captured_token.cancelled() => {
+                    () = captured_token.cancelled() => {
                         println!("Received shutdown request");
                         return;
                     },

diff --git a/benchmarks/src/sql_benchmark.rs b/benchmarks/src/sql_benchmark.rs
@@ -509,7 +509,7 @@ impl SqlBenchmark {
 
         while let Some(result) = reader_result {
             match result {
-                Ok(_) => {
+                Ok(()) => {
                     if !is_blank_or_comment_line(&line) {
                         // boxing required because of recursion
                         Box::pin(self.process_line(ctx, &mut reader, &mut line)).await?;
@@ -824,7 +824,7 @@ impl BenchmarkDirective {
 
         loop {
             match reader_result {
-                Some(Ok(_)) => {
+                Some(Ok(())) => {
                     if is_comment_line(line) {
                         // comment, ignore
                     } else if is_blank_line(line) {
@@ -956,7 +956,7 @@ impl BenchmarkDirective {
 
         loop {
             match reader_result {
-                Some(Ok(_)) => {
+                Some(Ok(())) => {
                     if line.trim() == "----" {
                         found_break = true;
                         break;
@@ -1045,7 +1045,7 @@ impl BenchmarkDirective {
 
         loop {
             match reader_result {
-                Some(Ok(_)) => {
+                Some(Ok(())) => {
                     if line.trim() == "----" {
                         found_break = true;
                         break;
@@ -1108,7 +1108,7 @@ impl BenchmarkDirective {
 
         loop {
             match reader_result {
-                Some(Ok(_)) => {
+                Some(Ok(())) => {
                     if is_comment_line(line) {
                         // Clear the line buffer for the next iteration.
                         line.clear();
@@ -1449,7 +1449,7 @@ fn read_query_from_reader(
 
     loop {
         match reader_result {
-            Some(Ok(_)) => {
+            Some(Ok(())) => {
                 if is_comment_line(&line) {
                     // comment, ignore
                 } else if is_blank_line(&line) {

diff --git a/datafusion-cli/src/exec.rs b/datafusion-cli/src/exec.rs
@@ -69,7 +69,7 @@ pub async fn exec_from_lines(
     reader: &mut BufReader<File>,
     print_options: &PrintOptions,
 ) -> Result<()> {
-    let mut query = "".to_owned();
+    let mut query = String::new();
 
     for line in reader.lines() {
         match line {
@@ -79,10 +79,10 @@ pub async fn exec_from_lines(
                 query.push_str(line);
                 if line.ends_with(';') {
                     match exec_and_print(ctx, print_options, query).await {
-                        Ok(_) => {}
+                        Ok(()) => {}
                         Err(err) => eprintln!("{err}"),
                     }
-                    query = "".to_string();
+                    query = String::new();
                 } else {
                     query.push('\n');
                 }
@@ -175,7 +175,7 @@ pub async fn exec_from_repl(
                     rl.add_history_entry(line.trim_end())?;
                     tokio::select! {
                         res = exec_and_print(ctx, print_options, line) => match res {
-                            Ok(_) => {}
+                            Ok(()) => {}
                             Err(err) => eprintln!("{err}"),
                         },
                         _ = signal::ctrl_c() => {

diff --git a/datafusion-cli/src/functions.rs b/datafusion-cli/src/functions.rs
@@ -665,8 +665,7 @@ impl TableFunctionImpl for StatisticsCacheFunc {
         {
             for (path, entry) in file_statistics_cache.list_entries() {
                 path_arr.push(path.path.to_string());
-                table_arr
-                    .push(path.table.map_or_else(|| "".to_string(), |t| t.to_string()));
+                table_arr.push(path.table.map_or_else(String::new, |t| t.to_string()));
                 file_modified_arr
                     .push(Some(entry.value.meta.last_modified.timestamp_millis()));
                 file_size_bytes_arr.push(entry.value.meta.size);

diff --git a/datafusion-cli/src/print_format.rs b/datafusion-cli/src/print_format.rs
@@ -128,10 +128,9 @@ fn format_batches_with_maxrows<W: std::io::Write>(
                     filtered_batches.push(sliced_batch);
                     over_limit = true;
                     break;
-                } else {
-                    filtered_batches.push(batch.clone());
-                    row_count += batch.num_rows();
                 }
+                filtered_batches.push(batch.clone());
+                row_count += batch.num_rows();
             }
 
             let formatted =

diff --git a/datafusion-examples/examples/data_io/parquet_encrypted_with_kms.rs b/datafusion-examples/examples/data_io/parquet_encrypted_with_kms.rs
@@ -200,7 +200,7 @@ async fn read_encrypted_with_sql(ctx: &SessionContext, table_path: &str) -> Resu
 extensions_options! {
     struct EncryptionConfig {
         /// Comma-separated list of columns to encrypt
-        pub encrypted_columns: String, default = "".to_owned()
+        pub encrypted_columns: String, default = String::new()
     }
 }
 

diff --git a/datafusion-examples/examples/udf/simple_udtf.rs b/datafusion-examples/examples/udf/simple_udtf.rs
@@ -110,10 +110,9 @@ impl TableProvider for LocalCsvTable {
                     let batch_lines = max_return_lines - lines;
                     batches.push(batch.slice(0, batch_lines));
                     break;
-                } else {
-                    batches.push(batch.clone());
-                    lines += batch_lines;
                 }
+                batches.push(batch.clone());
+                lines += batch_lines;
             }
             batches
         } else {

diff --git a/datafusion/catalog-listing/src/table.rs b/datafusion/catalog-listing/src/table.rs
@@ -425,12 +425,11 @@ fn derive_common_ordering_from_files(file_groups: &[FileGroup]) -> Option<LexOrd
                             "Cannot derive common ordering: no common prefix between orderings {current:?} and {ordering:?}"
                         );
                         return None;
-                    } else {
-                        let ordering =
-                            LexOrdering::new(current.as_ref()[..prefix_len].to_vec())
-                                .expect("prefix_len > 0, so ordering must be valid");
-                        CurrentOrderingState::SomeOrdering(ordering)
                     }
+                    let ordering =
+                        LexOrdering::new(current.as_ref()[..prefix_len].to_vec())
+                            .expect("prefix_len > 0, so ordering must be valid");
+                    CurrentOrderingState::SomeOrdering(ordering)
                 }
                 // If one file has ordering and another doesn't, no common ordering
                 // Return None and log a trace message explaining why

diff --git a/datafusion/common/src/config.rs b/datafusion/common/src/config.rs
@@ -2000,7 +2000,7 @@ config_namespace! {
         /// instead of being converted into a [`std::fmt::Error`]
         pub safe: bool, default = true
         /// Format string for nulls
-        pub null: String, default = "".into()
+        pub null: String, default = String::new()
         /// Date format for date arrays
         pub date_format: Option<String>, default = Some("%Y-%m-%d".to_string())
         /// Format for DateTime arrays
@@ -3399,7 +3399,7 @@ impl Default for ConfigFileEncryptionProperties {
 config_namespace_with_hashmap! {
     pub struct ColumnEncryptionProperties {
         /// Per column encryption key
-        pub column_key_as_hex: String, default = "".to_string()
+        pub column_key_as_hex: String, default = String::new()
         /// Per column encryption key metadata
         pub column_metadata_as_hex: Option<String>, default = None
     }
@@ -3578,7 +3578,7 @@ pub struct ConfigFileDecryptionProperties {
 config_namespace_with_hashmap! {
     pub struct ColumnDecryptionProperties {
         /// Per column encryption key
-        pub column_key_as_hex: String, default = "".to_string()
+        pub column_key_as_hex: String, default = String::new()
     }
 }
 
@@ -4548,7 +4548,7 @@ mod tests {
 
         let parsed_metadata = table_config.parquet.key_value_metadata.clone();
         assert_eq!(parsed_metadata.get("should not exist1"), None);
-        assert_eq!(parsed_metadata.get("key1"), Some(&Some("".into())));
+        assert_eq!(parsed_metadata.get("key1"), Some(&Some(String::new())));
         assert_eq!(parsed_metadata.get("key2"), Some(&Some("value2".into())));
         assert_eq!(
             parsed_metadata.get("key3"),

diff --git a/datafusion/common/src/error.rs b/datafusion/common/src/error.rs
@@ -555,11 +555,11 @@ impl DataFusionError {
                 return format!("{}{}", Self::BACK_TRACE_SEP, back_trace);
             }
 
-            "".to_owned()
+            String::new()
         }
 
         #[cfg(not(feature = "backtrace"))]
-        "".to_owned()
+        String::new()
     }
 
     /// Return a [`DataFusionErrorBuilder`] to build a [`DataFusionError`]
@@ -606,16 +606,15 @@ impl DataFusionError {
     pub fn message(&self) -> Cow<'_, str> {
         match *self {
             DataFusionError::ArrowError(ref desc, ref backtrace) => {
-                let backtrace = backtrace.clone().unwrap_or_else(|| "".to_owned());
+                let backtrace = backtrace.clone().unwrap_or_else(String::new);
                 Cow::Owned(format!("{desc}{backtrace}"))
             }
             #[cfg(feature = "parquet")]
             DataFusionError::ParquetError(ref desc) => Cow::Owned(desc.to_string()),
             DataFusionError::IoError(ref desc) => Cow::Owned(desc.to_string()),
             #[cfg(feature = "sql")]
             DataFusionError::SQL(ref desc, ref backtrace) => {
-                let backtrace: String =
-                    backtrace.clone().unwrap_or_else(|| "".to_owned());
+                let backtrace: String = backtrace.clone().unwrap_or_else(String::new);
                 Cow::Owned(format!("{desc:?}{backtrace}"))
             }
             DataFusionError::Configuration(ref desc) => Cow::Owned(desc.to_string()),
@@ -628,7 +627,7 @@ impl DataFusionError {
             DataFusionError::Plan(ref desc) => Cow::Owned(desc.to_string()),
             DataFusionError::SchemaError(ref desc, ref backtrace) => {
                 let backtrace: &str =
-                    &backtrace.as_ref().clone().unwrap_or_else(|| "".to_owned());
+                    &backtrace.as_ref().clone().unwrap_or_else(String::new);
                 Cow::Owned(format!("{desc}{backtrace}"))
             }
             DataFusionError::Execution(ref desc) => Cow::Owned(desc.to_string()),

diff --git a/datafusion/common/src/scalar/mod.rs b/datafusion/common/src/scalar/mod.rs
@@ -1703,9 +1703,9 @@ impl ScalarValue {
             | DataType::Date64 => ScalarValue::new_zero(datatype),
 
             // String types
-            DataType::Utf8 => Ok(ScalarValue::Utf8(Some("".to_string()))),
-            DataType::LargeUtf8 => Ok(ScalarValue::LargeUtf8(Some("".to_string()))),
-            DataType::Utf8View => Ok(ScalarValue::Utf8View(Some("".to_string()))),
+            DataType::Utf8 => Ok(ScalarValue::Utf8(Some(String::new()))),
+            DataType::LargeUtf8 => Ok(ScalarValue::LargeUtf8(Some(String::new()))),
+            DataType::Utf8View => Ok(ScalarValue::Utf8View(Some(String::new()))),
 
             // Binary types
             DataType::Binary => Ok(ScalarValue::Binary(Some(vec![]))),
@@ -5650,7 +5650,7 @@ impl fmt::Display for ScalarValue {
                     match epoch.checked_add_signed(Duration::try_days(v as i64).unwrap())
                     {
                         Some(date) => date.to_string(),
-                        None => "".to_string(),
+                        None => String::new(),
                     }
                 })
             )?,
@@ -5661,7 +5661,7 @@ impl fmt::Display for ScalarValue {
                     match epoch.checked_add_signed(Duration::try_milliseconds(v).unwrap())
                     {
                         Some(date) => date.to_string(),
-                        None => "".to_string(),
+                        None => String::new(),
                     }
                 })
             )?,
@@ -10640,11 +10640,11 @@ mod tests {
         // Test string types
         assert_eq!(
             ScalarValue::new_default(&DataType::Utf8).unwrap(),
-            ScalarValue::Utf8(Some("".to_string()))
+            ScalarValue::Utf8(Some(String::new()))
         );
         assert_eq!(
             ScalarValue::new_default(&DataType::LargeUtf8).unwrap(),
-            ScalarValue::LargeUtf8(Some("".to_string()))
+            ScalarValue::LargeUtf8(Some(String::new()))
         );
 
         // Test binary types

diff --git a/datafusion/common/src/test_util.rs b/datafusion/common/src/test_util.rs
@@ -285,16 +285,16 @@ pub fn get_data_dir(
         let trimmed = dir.trim().to_string();
         if !trimmed.is_empty() {
             let pb = PathBuf::from(trimmed);
-            if pb.is_dir() {
-                return Ok(pb);
+            return if pb.is_dir() {
+                Ok(pb)
             } else {
-                return Err(format!(
+                Err(format!(
                     "the data dir `{}` defined by env {} not found",
                     pb.display(),
                     udf_env
                 )
-                .into());
-            }
+                .into())
+            };
         }
     }
 

diff --git a/datafusion/core/src/bin/print_functions_docs.rs b/datafusion/core/src/bin/print_functions_docs.rs
@@ -93,7 +93,7 @@ fn print_docs(
     providers: Vec<Box<dyn DocProvider>>,
     doc_sections: Vec<DocSection>,
 ) -> Result<String> {
-    let mut docs = "".to_string();
+    let mut docs = String::new();
 
     // Ensure that all providers have documentation
     let mut providers_with_no_docs = HashSet::new();

diff --git a/datafusion/core/src/datasource/file_format/avro.rs b/datafusion/core/src/datasource/file_format/avro.rs
@@ -60,7 +60,7 @@ mod tests {
                 assert_eq!(11, batch.num_columns());
                 assert_eq!(2, batch.num_rows());
             })
-            .fold(0, |acc, _| async move { acc + 1i32 })
+            .fold(0, |acc, ()| async move { acc + 1i32 })
             .await;
 
         assert_eq!(tt_batches, 4 /* 8/2 */);

diff --git a/datafusion/core/src/datasource/file_format/csv.rs b/datafusion/core/src/datasource/file_format/csv.rs
@@ -210,7 +210,7 @@ mod tests {
                 assert_eq!(12, batch.num_columns());
                 assert_eq!(2, batch.num_rows());
             })
-            .fold(0, |acc, _| async move { acc + 1i32 })
+            .fold(0, |acc, ()| async move { acc + 1i32 })
             .await;
 
         assert_eq!(tt_batches, 50 /* 100/2 */);

diff --git a/datafusion/core/src/datasource/file_format/json.rs b/datafusion/core/src/datasource/file_format/json.rs
@@ -112,7 +112,7 @@ mod tests {
                 assert_eq!(4, batch.num_columns());
                 assert_eq!(2, batch.num_rows());
             })
-            .fold(0, |acc, _| async move { acc + 1i32 })
+            .fold(0, |acc, ()| async move { acc + 1i32 })
             .await;
 
         assert_eq!(tt_batches, 6 /* 12/2 */);

diff --git a/datafusion/core/src/datasource/file_format/parquet.rs b/datafusion/core/src/datasource/file_format/parquet.rs
@@ -709,7 +709,7 @@ mod tests {
                 assert_eq!(11, batch.num_columns());
                 assert_eq!(2, batch.num_rows());
             })
-            .fold(0, |acc, _| async move { acc + 1i32 })
+            .fold(0, |acc, ()| async move { acc + 1i32 })
             .await;
 
         assert_eq!(tt_batches, 4 /* 8/2 */);

diff --git a/datafusion/core/src/datasource/listing_table_factory.rs b/datafusion/core/src/datasource/listing_table_factory.rs
@@ -332,7 +332,7 @@ fn get_extension(path: &str) -> String {
     let res = Path::new(path).extension().and_then(|ext| ext.to_str());
     match res {
         Some(ext) => format!(".{ext}"),
-        None => "".to_string(),
+        None => String::new(),
     }
 }
 

diff --git a/datafusion/core/src/datasource/physical_plan/csv.rs b/datafusion/core/src/datasource/physical_plan/csv.rs
@@ -764,7 +764,7 @@ mod tests {
 
         // get name of first part
         let paths = fs::read_dir(&out_dir).unwrap();
-        let mut part_0_name: String = "".to_owned();
+        let mut part_0_name: String = String::new();
         for path in paths {
             let path = path.unwrap();
             let name = path

diff --git a/datafusion/core/src/datasource/physical_plan/json.rs b/datafusion/core/src/datasource/physical_plan/json.rs
@@ -410,7 +410,7 @@ mod tests {
 
         // get name of first part
         let paths = fs::read_dir(&out_dir).unwrap();
-        let mut part_0_name: String = "".to_owned();
+        let mut part_0_name: String = String::new();
         for path in paths {
             let name = path
                 .unwrap()