Merging upstream version 1.66.0+dfsg1.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 8 insertions, 1 deletions

diff --git a/library/core/src/fmt/mod.rs b/library/core/src/fmt/mod.rs
index 905212eb3..c8d285505 100644
--- a/library/core/src/fmt/mod.rs
+++ b/library/core/src/fmt/mod.rs
@@ -709,12 +709,19 @@ pub use macros::Debug;
 
 /// Format trait for an empty format, `{}`.
 ///
+/// Implementing this trait for a type will automatically implement the
+/// [`ToString`][tostring] trait for the type, allowing the usage
+/// of the [`.to_string()`][tostring_function] method. Prefer implementing
+/// the `Display` trait for a type, rather than [`ToString`][tostring].
+///
 /// `Display` is similar to [`Debug`], but `Display` is for user-facing
 /// output, and so cannot be derived.
 ///
 /// For more information on formatters, see [the module-level documentation][module].
 ///
 /// [module]: ../../std/fmt/index.html
+/// [tostring]: ../../std/string/trait.ToString.html
+/// [tostring_function]: ../../std/string/trait.ToString.html#tymethod.to_string
 ///
 /// # Examples
 ///
@@ -2603,7 +2610,7 @@ impl Debug for () {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> Debug for PhantomData<T> {
     fn fmt(&self, f: &mut Formatter<'_>) -> Result {
-        f.debug_struct("PhantomData").finish()
+        write!(f, "PhantomData<{}>", crate::any::type_name::<T>())
     }
 }