Side-step rustc attr warning

Author: compiler-errors

compiler/rustc_macros/src/lib.rs

@@ -45,7 +45,8 @@ pub fn symbols(input: TokenStream) -> TokenStream {
 /// goes into the parenthesized args of the macro, for greppability.
 /// For example:
 /// ```
-/// #[rustc_macros::extension(pub trait Foo)]
+/// use rustc_macros::extension;
+/// #[extension(pub trait Foo)]
 /// impl i32 { fn hello() {} }
 /// ```
 ///