{"ast_node_type":"other","tokens":[{"end":60,"kind":"keyword","start":0,"text":"if"}]}
        if self.builtin_macros.insert(name, ext).is_some() {
    fn register_builtin_macro(&mut self, name: Symbol, ext: SyntaxExtensionKind) {
            self.dcx().bug(format!("built-in macro `{name}` was already registered"));