From a61a85eb24ba6b65d48de1392d7021d15886223f Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Fri, 13 May 2022 10:07:45 +1000
Subject: [PATCH] Add some comments.

---
 library/proc_macro/src/bridge/handle.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/library/proc_macro/src/bridge/handle.rs b/library/proc_macro/src/bridge/handle.rs
index bcbb8681247..7d6adda48ec 100644
--- a/library/proc_macro/src/bridge/handle.rs
+++ b/library/proc_macro/src/bridge/handle.rs
@@ -8,6 +8,8 @@ use std::sync::atomic::{AtomicUsize, Ordering};
 
 pub(super) type Handle = NonZeroU32;
 
+/// A store that associates values of type `T` with numeric handles. A value can
+/// be looked up using its handle.
 pub(super) struct OwnedStore<T: 'static> {
     counter: &'static AtomicUsize,
     data: BTreeMap<Handle, T>,
@@ -49,6 +51,7 @@ impl<T> IndexMut<Handle> for OwnedStore<T> {
     }
 }
 
+/// Like `OwnedStore`, but avoids storing any value more than once.
 pub(super) struct InternedStore<T: 'static> {
     owned: OwnedStore<T>,
     interner: HashMap<T, Handle>,