syntax_data: {"ast_node_type":"other","tokens":[{"end":39,"kind":"keyword","start":0,"text":"ty::FnDef(..)"}]}
source_snippet:         ty::FnDef(..) => Some(user_ty),
context_before:         }
context_after:         _ => bug!("ty: {:?} should not have user provided type {:?} recorded ", ty, user_ty),