Auto merge of rust-lang#86875 - JohnTitor:rollup-fuefamw, r=JohnTitor

Rollup of 8 pull requests

Successful merges:

 - rust-lang#86477 (E0716: clarify that equivalent code example is erroneous)
 - rust-lang#86623 (Add check to ensure error code explanations are not removed anymore even if not emitted)
 - rust-lang#86856 (Make x.py less verbose on failures)
 - rust-lang#86858 (Stabilize `string_drain_as_str`)
 - rust-lang#86859 (Add a regression test for issue-69323)
 - rust-lang#86862 (re-export SwitchIntEdgeEffects)
 - rust-lang#86864 (Add missing code example for Write::write_vectored)
 - rust-lang#86874 (Bump deps)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

alloc/src/string.rs

@@ -2769,33 +2769,31 @@ impl<'a> Drain<'a> {
     /// # Examples
     ///
     /// ```
-    /// #![feature(string_drain_as_str)]
     /// let mut s = String::from("abc");
     /// let mut drain = s.drain(..);
     /// assert_eq!(drain.as_str(), "abc");
     /// let _ = drain.next().unwrap();
     /// assert_eq!(drain.as_str(), "bc");
     /// ```
-    #[unstable(feature = "string_drain_as_str", issue = "76905")] // Note: uncomment AsRef impls below when stabilizing.
+    #[stable(feature = "string_drain_as_str", since = "1.55.0")]
     pub fn as_str(&self) -> &str {
         self.iter.as_str()
     }
 }
 
-// Uncomment when stabilizing `string_drain_as_str`.
-// #[unstable(feature = "string_drain_as_str", issue = "76905")]
-// impl<'a> AsRef<str> for Drain<'a> {
-//     fn as_ref(&self) -> &str {
-//         self.as_str()
-//     }
-// }
-//
-// #[unstable(feature = "string_drain_as_str", issue = "76905")]
-// impl<'a> AsRef<[u8]> for Drain<'a> {
-//     fn as_ref(&self) -> &[u8] {
-//         self.as_str().as_bytes()
-//     }
-// }
+#[stable(feature = "string_drain_as_str", since = "1.55.0")]
+impl<'a> AsRef<str> for Drain<'a> {
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+#[stable(feature = "string_drain_as_str", since = "1.55.0")]
+impl<'a> AsRef<[u8]> for Drain<'a> {
+    fn as_ref(&self) -> &[u8] {
+        self.as_str().as_bytes()
+    }
+}
 
 #[stable(feature = "drain", since = "1.6.0")]
 impl Iterator for Drain<'_> {

std/src/io/mod.rs

@@ -1418,6 +1418,27 @@ pub trait Write {
     /// The default implementation calls [`write`] with either the first nonempty
     /// buffer provided, or an empty one if none exists.
     ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use std::io::IoSlice;
+    /// use std::io::prelude::*;
+    /// use std::fs::File;
+    ///
+    /// fn main() -> std::io::Result<()> {
+    ///     let mut data1 = [1; 8];
+    ///     let mut data2 = [15; 8];
+    ///     let io_slice1 = IoSlice::new(&mut data1);
+    ///     let io_slice2 = IoSlice::new(&mut data2);
+    ///
+    ///     let mut buffer = File::create("foo.txt")?;
+    ///
+    ///     // Writes some prefix of the byte string, not necessarily all of it.
+    ///     buffer.write_vectored(&[io_slice1, io_slice2])?;
+    ///     Ok(())
+    /// }
+    /// ```
+    ///
     /// [`write`]: Write::write
     #[stable(feature = "iovec", since = "1.36.0")]
     fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize> {