fix(rust, python): don't panic in wildcard apply

crates/polars-plan/src/utils.rs

@@ -1,5 +1,5 @@
 use std::fmt::Formatter;
-use std::iter::{FlatMap, Map};
+use std::iter::FlatMap;
 use std::sync::Arc;
 use std::vec::IntoIter;
 
@@ -202,10 +202,12 @@ pub(crate) fn get_single_leaf(expr: &Expr) -> PolarsResult<Arc<str>> {
 }
 
 #[allow(clippy::type_complexity)]
-pub fn expr_to_leaf_column_names_iter(expr: &Expr) -> Map<IntoIter<Expr>, fn(Expr) -> Arc<str>> {
+pub fn expr_to_leaf_column_names_iter(
+    expr: &Expr,
+) -> FlatMap<IntoIter<Expr>, Option<Arc<str>>, fn(Expr) -> Option<Arc<str>>> {
     expr_to_root_column_exprs(expr)
         .into_iter()
-        .map(|e| expr_to_leaf_column_name(&e).unwrap())
+        .flat_map(|e| expr_to_leaf_column_name(&e).ok())
 }
 
 /// This should gradually replace expr_to_root_column as this will get all names in the tree.

py-polars/polars/expr/expr.py

@@ -36,7 +36,7 @@
 )
 from polars.dependencies import _check_for_numpy
 from polars.dependencies import numpy as np
-from polars.exceptions import PolarsInefficientApplyWarning, PolarsPanicError
+from polars.exceptions import PolarsInefficientApplyWarning
 from polars.expr.array import ExprArrayNameSpace
 from polars.expr.binary import ExprBinaryNameSpace
 from polars.expr.categorical import ExprCatNameSpace
@@ -3806,16 +3806,9 @@ def apply(
         # input x: Series of type list containing the group values
         from polars.utils.udfs import warn_on_inefficient_apply
 
-        try:
-            root_names = self.meta.root_names()
-        except PolarsPanicError:
-            # no root names for pl.col('*')
-            pass
-        else:
-            if root_names:
-                warn_on_inefficient_apply(
-                    function, columns=root_names, apply_target="expr"
-                )
+        root_names = self.meta.root_names()
+        if len(root_names) > 0:
+            warn_on_inefficient_apply(function, columns=root_names, apply_target="expr")
 
         if pass_name:
 

py-polars/tests/unit/operations/test_apply.py

@@ -386,3 +386,8 @@ def test_apply_shifted_chunks() -> None:
 def test_apply_dict_order_10128() -> None:
     df = pl.select(pl.lit("").apply(lambda x: {"c": 1, "b": 2, "a": 3}))
     assert df.to_dict(False) == {"literal": [{"c": 1, "b": 2, "a": 3}]}
+
+
+def test_apply_10237() -> None:
+    df = pl.DataFrame({"a": [1, 2, 3]})
+    assert df.select(pl.all().apply(lambda x: x > 50))["a"].to_list() == [False] * 3