diff --git a/ballista/rust/executor/src/executor.rs b/ballista/rust/executor/src/executor.rs
index a7cd8ebe5e922..ff2f08faafd48 100644
--- a/ballista/rust/executor/src/executor.rs
+++ b/ballista/rust/executor/src/executor.rs
@@ -83,9 +83,7 @@ impl Executor {
             job_id,
             stage_id,
             part,
-            DisplayableExecutionPlan::with_metrics(&exec)
-                .indent()
-                .to_string()
+            DisplayableExecutionPlan::with_metrics(&exec).indent()
         );
 
         Ok(partitions)
diff --git a/ballista/rust/scheduler/src/planner.rs b/ballista/rust/scheduler/src/planner.rs
index 3d3884fd5021d..fdd143500b5f4 100644
--- a/ballista/rust/scheduler/src/planner.rs
+++ b/ballista/rust/scheduler/src/planner.rs
@@ -293,7 +293,7 @@ mod test {
             .plan_query_stages(&job_uuid.to_string(), plan)
             .await?;
         for stage in &stages {
-            println!("{}", displayable(stage.as_ref()).indent().to_string());
+            println!("{}", displayable(stage.as_ref()).indent());
         }
 
         /* Expected result:
@@ -407,7 +407,7 @@ order by
             .plan_query_stages(&job_uuid.to_string(), plan)
             .await?;
         for stage in &stages {
-            println!("{}", displayable(stage.as_ref()).indent().to_string());
+            println!("{}", displayable(stage.as_ref()).indent());
         }
 
         /* Expected result:
diff --git a/benchmarks/src/bin/tpch.rs b/benchmarks/src/bin/tpch.rs
index b676253eab2d2..9563434601b01 100644
--- a/benchmarks/src/bin/tpch.rs
+++ b/benchmarks/src/bin/tpch.rs
@@ -546,7 +546,7 @@ async fn execute_query(
     if debug {
         println!(
             "=== Physical plan ===\n{}\n",
-            displayable(physical_plan.as_ref()).indent().to_string()
+            displayable(physical_plan.as_ref()).indent()
         );
     }
     let runtime = ctx.state.lock().unwrap().runtime_env.clone();
@@ -554,9 +554,7 @@ async fn execute_query(
     if debug {
         println!(
             "=== Physical plan with metrics ===\n{}\n",
-            DisplayableExecutionPlan::with_metrics(physical_plan.as_ref())
-                .indent()
-                .to_string()
+            DisplayableExecutionPlan::with_metrics(physical_plan.as_ref()).indent()
         );
         pretty::print_batches(&result)?;
     }
diff --git a/datafusion/src/physical_plan/expressions/rank.rs b/datafusion/src/physical_plan/expressions/rank.rs
index b82e9009d8e52..c555d8826948f 100644
--- a/datafusion/src/physical_plan/expressions/rank.rs
+++ b/datafusion/src/physical_plan/expressions/rank.rs
@@ -38,6 +38,7 @@ pub struct Rank {
 }
 
 #[derive(Debug, Copy, Clone)]
+#[allow(clippy::enum_variant_names)]
 pub(crate) enum RankType {
     Rank,
     DenseRank,
diff --git a/datafusion/src/physical_plan/file_format/parquet.rs b/datafusion/src/physical_plan/file_format/parquet.rs
index 78c9428e39dbf..0e2d0c37be57c 100644
--- a/datafusion/src/physical_plan/file_format/parquet.rs
+++ b/datafusion/src/physical_plan/file_format/parquet.rs
@@ -312,20 +312,10 @@ macro_rules! get_statistic {
 // Extract the min or max value calling `func` or `bytes_func` on the ParquetStatistics as appropriate
 macro_rules! get_min_max_values {
     ($self:expr, $column:expr, $func:ident, $bytes_func:ident) => {{
-        let (column_index, field) = if let Some((v, f)) = $self.parquet_schema.column_with_name(&$column.name) {
-            (v, f)
-        } else {
-            // Named column was not present
-            return None
-        };
+        let (column_index, field) = $self.parquet_schema.column_with_name(&$column.name)?;
 
         let data_type = field.data_type();
-        let null_scalar: ScalarValue = if let Ok(v) = data_type.try_into() {
-            v
-        } else {
-            // DataFusion doesn't have support for ScalarValues of the column type
-            return None
-        };
+        let null_scalar: ScalarValue = data_type.try_into().ok()?;
 
         let scalar_values : Vec<ScalarValue> = $self.row_group_metadata
             .iter()
@@ -441,11 +431,8 @@ fn read_partition(
                     break;
                 }
                 Some(Err(e)) => {
-                    let err_msg = format!(
-                        "Error reading batch from {}: {}",
-                        partitioned_file,
-                        e.to_string()
-                    );
+                    let err_msg =
+                        format!("Error reading batch from {}: {}", partitioned_file, e);
                     // send error to operator
                     send_result(
                         &response_tx,
diff --git a/datafusion/src/physical_plan/planner.rs b/datafusion/src/physical_plan/planner.rs
index 1ab78b24a4821..fa0c101da3ac7 100644
--- a/datafusion/src/physical_plan/planner.rs
+++ b/datafusion/src/physical_plan/planner.rs
@@ -1627,7 +1627,7 @@ mod tests {
             Err(e) => assert!(
                 e.to_string().contains(expected_error),
                 "Error '{}' did not contain expected error '{}'",
-                e.to_string(),
+                e,
                 expected_error
             ),
         }
@@ -1674,7 +1674,7 @@ mod tests {
             Err(e) => assert!(
                 e.to_string().contains(expected_error),
                 "Error '{}' did not contain expected error '{}'",
-                e.to_string(),
+                e,
                 expected_error
             ),
         }
@@ -1733,7 +1733,7 @@ mod tests {
             Err(e) => assert!(
                 e.to_string().contains(expected_error),
                 "Error '{}' did not contain expected error '{}'",
-                e.to_string(),
+                e,
                 expected_error
             ),
         }
diff --git a/datafusion/src/scalar.rs b/datafusion/src/scalar.rs
index a3f893f55eb89..e7c7db5217ea9 100644
--- a/datafusion/src/scalar.rs
+++ b/datafusion/src/scalar.rs
@@ -1739,7 +1739,7 @@ impl fmt::Display for ScalarValue {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
         match self {
             ScalarValue::Decimal128(v, p, s) => {
-                write!(f, "{}", format!("{:?},{:?},{:?}", v, p, s))?;
+                write!(f, "{:?},{:?},{:?}", v, p, s)?;
             }
             ScalarValue::Boolean(e) => format_option!(f, e)?,
             ScalarValue::Float32(e) => format_option!(f, e)?,
diff --git a/datafusion/src/test/variable.rs b/datafusion/src/test/variable.rs
index fcde0e90404b0..ff0f108ff260a 100644
--- a/datafusion/src/test/variable.rs
+++ b/datafusion/src/test/variable.rs
@@ -35,7 +35,7 @@ impl SystemVar {
 impl VarProvider for SystemVar {
     /// get system variable value
     fn get_value(&self, var_names: Vec<String>) -> Result<ScalarValue> {
-        let s = format!("{}-{}", "system-var".to_string(), var_names.concat());
+        let s = format!("system-var-{}", var_names.concat());
         Ok(ScalarValue::Utf8(Some(s)))
     }
 }
@@ -54,7 +54,7 @@ impl UserDefinedVar {
 impl VarProvider for UserDefinedVar {
     /// Get user defined variable value
     fn get_value(&self, var_names: Vec<String>) -> Result<ScalarValue> {
-        let s = format!("{}-{}", "user-defined-var".to_string(), var_names.concat());
+        let s = format!("user-defined-var-{}", var_names.concat());
         Ok(ScalarValue::Utf8(Some(s)))
     }
 }