message: Delete the unused branch in to_ast_trait
  Summary: Unused, now we no longer do weird box things.
diff: @@ -50,14 +50,6 @@ pub(crate) trait ToAst<T> {
  }
  macro_rules! to_ast_trait {
  - ($t1:ty, $t2:ty, $t3:ident) => {
  - impl ToAst<$t2> for $t1 {
  - fn to_ast(self, span: Span) -> $t2 {
  - #[cfg_attr(feature = "custom_linter", allow(gazebo_use_box))]
  - $t3::new(Spanned { span, node: self })
  - }
  - }
  - };
  ($t1:ty, $t2:ty) => {
  impl ToAst<$t2> for $t1 {
  fn to_ast(self, span: Span) -> $t2 {
  