Address macros

Author: joshtriplett

text/3373-avoid-nonlocal-definitions-in-fns.md

@@ -34,6 +34,9 @@ Starting in the Rust 2024 edition:
 - An item nested inside a function or closure (through any level of nesting)
   may not define an `impl Trait for Type` unless either the `Trait` or the
   `Type` is also nested inside the same function or closure.
+- An item nested inside a function or closure (through any level of nesting)
+  may not define an exported macro visible outside the function or closure
+  (e.g. using `#[macro_export]`).
 
 Rust 2015, 2018, and 2021 continue to permit this, but will produce a
 warn-by-default lint.