rustdoc asks for dyn_trait feature in stage0

Author: pvdrz

src/librustdoc/lib.rs

@@ -13,6 +13,8 @@
        html_root_url = "https://doc.rust-lang.org/nightly/",
        html_playground_url = "https://play.rust-lang.org/")]
 
+#![cfg_attr(stage0, feature(dyn_trait))]
+
 #![feature(ascii_ctype)]
 #![feature(rustc_private)]
 #![feature(box_patterns)]