Function rustc_infer::infer::error_reporting::need_type_info::closure_as_fn_str

fn closure_as_fn_str<'tcx>(infcx: &InferCtxt<'_, 'tcx>, ty: Ty<'tcx>) -> String

We don’t want to directly use ty_to_string for closures as their type isn’t really something users are familar with. Directly printing the fn_sig of closures also doesn’t work as they actually use the “rust-call” API.