2 files changed, 11 insertions, 16 deletions
diff --git a/library/core/src/fmt/builders.rs b/library/core/src/fmt/builders.rs
index 32d1a4e55..7da49b04a 100644
--- a/library/core/src/fmt/builders.rs
+++ b/library/core/src/fmt/builders.rs
@@ -28,24 +28,14 @@ impl<'buf, 'state> PadAdapter<'buf, 'state> {
 }
 
 impl fmt::Write for PadAdapter<'_, '_> {
-    fn write_str(&mut self, mut s: &str) -> fmt::Result {
-        while !s.is_empty() {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for s in s.split_inclusive('\n') {
             if self.state.on_newline {
                 self.buf.write_str("    ")?;
             }
 
-            let split = match s.find('\n') {
-                Some(pos) => {
-                    self.state.on_newline = true;
-                    pos + 1
-                }
-                None => {
-                    self.state.on_newline = false;
-                    s.len()
-                }
-            };
-            self.buf.write_str(&s[..split])?;
-            s = &s[split..];
+            self.state.on_newline = s.ends_with('\n');
+            self.buf.write_str(s)?;
         }
 
         Ok(())
diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 372141e09..905212eb3 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -119,6 +119,10 @@ pub trait Write {
     ///
     /// This function will return an instance of [`Error`] on error.
     ///
+    /// The purpose of std::fmt::Error is to abort the formatting operation when the underlying
+    /// destination encounters some error preventing it from accepting more text; it should
+    /// generally be propagated rather than handled, at least when implementing formatting traits.
+    ///
     /// # Examples
     ///
     /// ```
@@ -1815,7 +1819,7 @@ impl<'a> Formatter<'a> {
     ///             write!(formatter,
     ///                    "Foo({}{})",
     ///                    if self.0 < 0 { '-' } else { '+' },
-    ///                    self.0)
+    ///                    self.0.abs())
     ///         } else {
     ///             write!(formatter, "Foo({})", self.0)
     ///         }
@@ -1823,6 +1827,7 @@ impl<'a> Formatter<'a> {
     /// }
     ///
     /// assert_eq!(&format!("{:+}", Foo(23)), "Foo(+23)");
+    /// assert_eq!(&format!("{:+}", Foo(-23)), "Foo(-23)");
     /// assert_eq!(&format!("{}", Foo(23)), "Foo(23)");
     /// ```
     #[must_use]
@@ -2562,7 +2567,7 @@ macro_rules! tuple {
 
 macro_rules! maybe_tuple_doc {
     ($a:ident @ #[$meta:meta] $item:item) => {
-        #[cfg_attr(not(bootstrap), doc(fake_variadic))]
+        #[doc(fake_variadic)]
         #[doc = "This trait is implemented for tuples up to twelve items long."]
         #[$meta]
         $item