Auto merge of #44380 - Mark-Simulacrum:rollup, r=Mark-Simulacrum

Rollup of 23 pull requests

- Successful merges: #44097, #44206, #44218, #44276, #44277, #44296, #44303, #44313, #44315, #44317, #44319, #44321, #44325, #44326, #44327, #44328, #44330, #44351, #44353, #44354, #44361, #44362, #44377
- Failed merges:

1 files changed, 11 insertions, 0 deletions

diff --git a/src/libstd/time/mod.rs b/src/libstd/time/mod.rs
index 5b893505b34..e0dd8cfe62e 100644
--- a/src/libstd/time/mod.rs
+++ b/src/libstd/time/mod.rs
@@ -382,6 +382,17 @@ impl fmt::Debug for SystemTime {
 /// [`SystemTime`] instance to represent another fixed point in time.
 ///
 /// [`SystemTime`]: ../../std/time/struct.SystemTime.html
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::time::{SystemTime, UNIX_EPOCH};
+///
+/// match SystemTime::now().duration_since(UNIX_EPOCH) {
+///     Ok(n) => println!("1970-01-01 00:00:00 UTC was {} seconds ago!", n.as_secs()),
+///     Err(_) => panic!("SystemTime before UNIX EPOCH!"),
+/// }
+/// ```
 #[stable(feature = "time2", since = "1.8.0")]
 pub const UNIX_EPOCH: SystemTime = SystemTime(time::UNIX_EPOCH);