Extra documentation for new formatting feature

High traffic macros should detail this helpful addition.

2 files changed, 4 insertions, 0 deletions

diff --git a/library/alloc/src/macros.rs b/library/alloc/src/macros.rs
index 88eb6aa7a83..5198bf297d9 100644
--- a/library/alloc/src/macros.rs
+++ b/library/alloc/src/macros.rs
@@ -107,6 +107,8 @@ macro_rules! vec {
 /// format!("test");
 /// format!("hello {}", "world!");
 /// format!("x = {}, y = {y}", 10, y = 30);
+/// let (x, y) = (1, 2);
+/// format!("{x} + {y} = 3");
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]
diff --git a/library/std/src/macros.rs b/library/std/src/macros.rs
index 0cb21ef53b1..ce2a979475c 100644
--- a/library/std/src/macros.rs
+++ b/library/std/src/macros.rs
@@ -93,6 +93,8 @@ macro_rules! print {
 /// println!(); // prints just a newline
 /// println!("hello there!");
 /// println!("format {} arguments", "some");
+/// let local_variable = "some";
+/// println!("format {local_variable} arguments");
 /// ```
 #[macro_export]
 #[stable(feature = "rust1", since = "1.0.0")]