rebase/update for PlSmallStr

crates/polars-plan/src/dsl/name.rs

@@ -1,8 +1,8 @@
-#[cfg(feature = "regex")]
-use regex::Regex;
 use polars_utils::format_pl_smallstr;
 #[cfg(feature = "dtype-struct")]
 use polars_utils::pl_str::PlSmallStr;
+#[cfg(feature = "regex")]
+use regex::Regex;
 
 use super::*;
 
@@ -57,10 +57,14 @@ impl ExprNameNameSpace {
         let value = value.to_string();
         let pattern = pattern.to_string();
         if literal {
-            self.map(move |name| Ok(name.replace(&pattern, &value)))
+            self.map(move |name| Ok(PlSmallStr::from_string(name.replace(&pattern, &value))))
         } else {
             let rx = Regex::new(&pattern);
-            self.map(move |name| Ok(rx.clone()?.replace_all(name, &value).to_string()))
+            self.map(move |name| {
+                Ok(PlSmallStr::from_string(
+                    rx.clone()?.replace_all(name, &value).to_string(),
+                ))
+            })
         }
     }