fn derive_variant_fields_expr(
bindings: &[BindingInfo<'_>],
where_clause: &mut Option<WhereClause>,
separator: &str,
) -> TokenStreamfn derive_variant_fields_expr(
bindings: &[BindingInfo<'_>],
where_clause: &mut Option<WhereClause>,
separator: &str,
) -> TokenStream