[nll] librustc_cratesio_shim: enable feature(nll) for bootstrap

Author: memoryruins

src/librustc_cratesio_shim/src/lib.rs

@@ -11,5 +11,7 @@
 // See Cargo.toml for a comment explaining this crate.
 #![allow(unused_extern_crates)]
 
+#![cfg_attr(not(stage0), feature(nll))]
+
 extern crate bitflags;
 extern crate log;