#![feature(drain_filter)]
#![feature(in_band_lifetimes)]
#![feature(nll)]
+#![feature(once_cell)]
#![feature(or_patterns)]
#![feature(proc_macro_internals)]
#![feature(min_specialization)]
extern crate proc_macro;
+#[macro_use]
+extern crate rustc_macros;
#[macro_use]
extern crate rustc_middle;
#[macro_use]