{"ast_node_type":"other","tokens":[{"end":69,"kind":"keyword","start":0,"text":"debug_assert!(a.is_ty_var()"}]}
        debug_assert!(a.is_ty_var() && self.shallow_resolve(a) == a);
        debug!("coerce_from_inference_variable(a={:?}, b={:?})", a, b);
        debug_assert!(self.shallow_resolve(b) == b);