Minor: remove clone in exprlist_to_fields (#9657)

* remove clone

Signed-off-by: jayzhan211 <jayzhan211@gmail.com>

* remove lifetime

Signed-off-by: jayzhan211 <jayzhan211@gmail.com>

* fmt

Signed-off-by: jayzhan211 <jayzhan211@gmail.com>

---------

Signed-off-by: jayzhan211 <jayzhan211@gmail.com>

datafusion/expr/src/logical_plan/plan.rs

@@ -2031,7 +2031,8 @@ impl Window {
         let fields = input.schema().fields();
         let input_len = fields.len();
         let mut window_fields = fields.clone();
-        window_fields.extend_from_slice(&exprlist_to_fields(window_expr.iter(), &input)?);
+        let expr_fields = exprlist_to_fields(window_expr.as_slice(), &input)?;
+        window_fields.extend_from_slice(expr_fields.as_slice());
         let metadata = input.schema().metadata().clone();
 
         // Update functional dependencies for window:
@@ -2357,7 +2358,7 @@ impl DistinctOn {
         let on_expr = normalize_cols(on_expr, input.as_ref())?;
 
         let schema = DFSchema::new_with_metadata(
-            exprlist_to_fields(&select_expr, &input)?,
+            exprlist_to_fields(select_expr.as_slice(), &input)?,
             input.schema().metadata().clone(),
         )?;
 
@@ -2436,7 +2437,7 @@ impl Aggregate {
 
         let grouping_expr: Vec<Expr> = grouping_set_to_exprlist(group_expr.as_slice())?;
 
-        let mut fields = exprlist_to_fields(grouping_expr.iter(), &input)?;
+        let mut fields = exprlist_to_fields(grouping_expr.as_slice(), &input)?;
 
         // Even columns that cannot be null will become nullable when used in a grouping set.
         if is_grouping_set {
@@ -2446,7 +2447,7 @@ impl Aggregate {
                 .collect::<Vec<_>>();
         }
 
-        fields.extend(exprlist_to_fields(aggr_expr.iter(), &input)?);
+        fields.extend(exprlist_to_fields(aggr_expr.as_slice(), &input)?);
 
         let schema =
             DFSchema::new_with_metadata(fields, input.schema().metadata().clone())?;

datafusion/expr/src/utils.rs

@@ -753,17 +753,13 @@ fn exprlist_to_fields_aggregate(exprs: &[Expr], agg: &Aggregate) -> Result<Vec<D
 }
 
 /// Create field meta-data from an expression, for use in a result set schema
-pub fn exprlist_to_fields<'a>(
-    expr: impl IntoIterator<Item = &'a Expr>,
-    plan: &LogicalPlan,
-) -> Result<Vec<DFField>> {
-    let exprs: Vec<Expr> = expr.into_iter().cloned().collect();
+pub fn exprlist_to_fields(exprs: &[Expr], plan: &LogicalPlan) -> Result<Vec<DFField>> {
     // when dealing with aggregate plans we cannot simply look in the aggregate output schema
     // because it will contain columns representing complex expressions (such a column named
     // `GROUPING(person.state)` so in order to resolve `person.state` in this case we need to
     // look at the input to the aggregate instead.
     let fields = match plan {
-        LogicalPlan::Aggregate(agg) => Some(exprlist_to_fields_aggregate(&exprs, agg)),
+        LogicalPlan::Aggregate(agg) => Some(exprlist_to_fields_aggregate(exprs, agg)),
         _ => None,
     };
     if let Some(fields) = fields {