From 220f3ab825d135c82243fc83ebf6286d94cdab96 Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Tue, 21 May 2024 15:12:50 +1000
Subject: [PATCH] Add a useful comment.

For something that wasn't obvious to me.
---
 compiler/rustc_span/src/lib.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/compiler/rustc_span/src/lib.rs b/compiler/rustc_span/src/lib.rs
index f83bacdcebe..62209e3795f 100644
--- a/compiler/rustc_span/src/lib.rs
+++ b/compiler/rustc_span/src/lib.rs
@@ -33,6 +33,9 @@
 #![feature(rustdoc_internals)]
 // tidy-alphabetical-end
 
+// The code produced by the `Encodable`/`Decodable` derive macros refer to
+// `rustc_span::Span{Encoder,Decoder}`. That's fine outside this crate, but doesn't work inside
+// this crate without this line making `rustc_span` available.
 extern crate self as rustc_span;
 
 #[macro_use]