syntax_data: {"ast_node_type":"function","tokens":[{"end":69,"kind":"keyword","start":0,"text":"fn"}]}
source_snippet:     fn fold_const(&mut self, c: ty::Const<'tcx>) -> ty::Const<'tcx> {
context_after:         self.normalize_generic_arg_after_erasing_regions(c.into()).expect_const()