rollup merge of #23598: brson/gate

Conflicts:
	src/compiletest/compiletest.rs
	src/libcollections/lib.rs
	src/librustc_back/lib.rs
	src/libserialize/lib.rs
	src/libstd/lib.rs
	src/libtest/lib.rs
	src/test/run-make/rustdoc-default-impl/foo.rs
	src/test/run-pass/env-home-dir.rs

src/libstd/macros.rs

@@ -111,6 +111,7 @@ macro_rules! try {
 /// # Examples
 ///
 /// ```
+/// # #![feature(std_misc)]
 /// use std::thread;
 /// use std::sync::mpsc;
 ///