From b88cb3dc114a04800c5361a8a6a826cd0c554b5b Mon Sep 17 00:00:00 2001
From: Eduard-Mihai Burtescu <edy.burt@gmail.com>
Date: Tue, 7 Apr 2020 14:59:07 +0300
Subject: [PATCH] bootstrap: work around "unused attribute" errors in
 incremental stdlib rebuilds.

---
 src/bootstrap/builder.rs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/bootstrap/builder.rs b/src/bootstrap/builder.rs
index b14352d7f4ba0..7fc089d18f113 100644
--- a/src/bootstrap/builder.rs
+++ b/src/bootstrap/builder.rs
@@ -1099,6 +1099,13 @@ impl<'a> Builder<'a> {
 
             if self.config.deny_warnings {
                 rustflags.arg("-Dwarnings");
+
+                // FIXME(#58633) hide "unused attribute" errors in incremental
+                // builds of the standard library, as the underlying checks are
+                // not yet properly integrated with incremental recompilation.
+                if mode == Mode::Std && compiler.stage == 0 && self.config.incremental {
+                    rustflags.arg("-Aunused-attributes");
+                }
             }
         }