Enable drain_filter

ecstatic-morse · ecstatic-morse · commit 22a0856641de · 2019-10-16T18:01:01.000-07:00
diff --git a/src/librustc_mir/lib.rs b/src/librustc_mir/lib.rs
@@ -14,6 +14,7 @@ Rust MIR: a lowered representation of Rust. Also: an experiment!
 #![feature(core_intrinsics)]
 #![feature(const_fn)]
 #![feature(decl_macro)]
+#![feature(drain_filter)]
 #![feature(exhaustive_patterns)]
 #![feature(never_type)]
 #![feature(specialization)]
