Auto merge of #73115 - RalfJung:rollup-jecowhz, r=RalfJung

Rollup of 10 pull requests

Successful merges:

 - #72026 (Update annotate-snippets-rs to 0.8.0)
 - #72583 (impl AsRef<[T]> for vec::IntoIter<T>)
 - #72615 (Fix documentation example for gcov profiling)
 - #72761 (Added the documentation for the 'use' keyword)
 - #72799 (Add `-Z span-debug` to allow for easier debugging of proc macros)
 - #72811 (Liballoc impl)
 - #72963 (Cstring `from_raw` and `into_raw` safety precisions)
 - #73001 (Free `default()` forwarding to `Default::default()`)
 - #73075 (Add comments to `Resolve::get_module`)
 - #73092 (Clean up E0646)

Failed merges:

r? @ghost

1 files changed, 44 insertions, 0 deletions

diff --git a/src/libcore/default.rs b/src/libcore/default.rs
index 06402a05d26..9a8d65cd4e0 100644
--- a/src/libcore/default.rs
+++ b/src/libcore/default.rs
@@ -115,6 +115,50 @@ pub trait Default: Sized {
     fn default() -> Self;
 }
 
+/// Return the default value of a type according to the `Default` trait.
+///
+/// The type to return is inferred from context; this is equivalent to
+/// `Default::default()` but shorter to type.
+///
+/// For example:
+/// ```
+/// #![feature(default_free_fn)]
+///
+/// use std::default::default;
+///
+/// #[derive(Default)]
+/// struct AppConfig {
+///     foo: FooConfig,
+///     bar: BarConfig,
+/// }
+///
+/// #[derive(Default)]
+/// struct FooConfig {
+///     foo: i32,
+/// }
+///
+/// #[derive(Default)]
+/// struct BarConfig {
+///     bar: f32,
+///     baz: u8,
+/// }
+///
+/// fn main() {
+///     let options = AppConfig {
+///         foo: default(),
+///         bar: BarConfig {
+///             bar: 10.1,
+///             ..default()
+///         },
+///     };
+/// }
+/// ```
+#[unstable(feature = "default_free_fn", issue = "73014")]
+#[inline]
+pub fn default<T: Default>() -> T {
+    Default::default()
+}
+
 /// Derive macro generating an impl of the trait `Default`.
 #[rustc_builtin_macro]
 #[stable(feature = "builtin_macro_prelude", since = "1.38.0")]