From e8d16fdf9f95e4110df53650779be842b6749f60 Mon Sep 17 00:00:00 2001
From: Bastian Kauschke <bastian_kauschke@hotmail.de>
Date: Sat, 18 Jul 2020 19:22:12 +0200
Subject: [PATCH] add note to `opt_const_param_of`

---
 src/librustc_middle/query/mod.rs | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/librustc_middle/query/mod.rs b/src/librustc_middle/query/mod.rs
index 40ff25cf3b134..06136a82e7b46 100644
--- a/src/librustc_middle/query/mod.rs
+++ b/src/librustc_middle/query/mod.rs
@@ -103,9 +103,13 @@ rustc_queries! {
         /// // ^ While calling `opt_const_param_of` for other bodies returns `None`.
         /// }
         /// ```
+        // It looks like caching this query on disk actually slightly
+        // worsened performance in #74376.
+        //
+        // Once const generics are more prevalently used, we might want to
+        // consider only caching calls returning `Some`.
         query opt_const_param_of(key: LocalDefId) -> Option<DefId> {
             desc { |tcx| "computing the optional const parameter of `{}`", tcx.def_path_str(key.to_def_id()) }
-            // FIXME(#74113): consider storing this query on disk.
         }
 
         /// Records the type of every item.