From 021c0520e3ec4ddecac425f99db5749942785e65 Mon Sep 17 00:00:00 2001
From: Michael Woerister <michaelwoerister@posteo>
Date: Wed, 21 Jul 2021 13:38:29 +0200
Subject: [PATCH] Fix up comment about OnDiskCache::foreign_expn_data.

---
 compiler/rustc_query_impl/src/on_disk_cache.rs | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/compiler/rustc_query_impl/src/on_disk_cache.rs b/compiler/rustc_query_impl/src/on_disk_cache.rs
index f9456a6f2cd..cb50c851e9a 100644
--- a/compiler/rustc_query_impl/src/on_disk_cache.rs
+++ b/compiler/rustc_query_impl/src/on_disk_cache.rs
@@ -86,8 +86,10 @@ pub struct OnDiskCache<'sess> {
     expn_data: UnhashMap<ExpnHash, AbsoluteBytePos>,
     // Additional information used when decoding hygiene data.
     hygiene_context: HygieneDecodeContext,
-    // FIXME(mw): Update this comment:
-    // Likewise for ExpnId.
+    // Maps `ExpnHash`es to their raw value from the *previous*
+    // compilation session. This is used as an initial 'guess' when
+    // we try to map an `ExpnHash` to its value in the current
+    // compilation session.
     foreign_expn_data: UnhashMap<ExpnHash, u32>,
 }