From e12101c4db03b1cd35fcc288f8e6568f552ee51c Mon Sep 17 00:00:00 2001
From: Nadrieril <nadrieril+git@gmail.com>
Date: Tue, 16 Jan 2024 21:14:39 +0100
Subject: [PATCH] Fix `rustc_abi` build on stable

---
 compiler/rustc_abi/src/lib.rs | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_abi/src/lib.rs b/compiler/rustc_abi/src/lib.rs
index ea194e10defd6..c45a4a410f964 100644
--- a/compiler/rustc_abi/src/lib.rs
+++ b/compiler/rustc_abi/src/lib.rs
@@ -49,7 +49,14 @@ bitflags! {
                                  | ReprFlags::IS_LINEAR.bits();
     }
 }
-rustc_data_structures::external_bitflags_debug! { ReprFlags }
+
+// This is the same as `rustc_data_structures::external_bitflags_debug` but without the
+// `rustc_data_structures` to make it build on stable.
+impl std::fmt::Debug for ReprFlags {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        bitflags::parser::to_writer(self, f)
+    }
+}
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 #[cfg_attr(feature = "nightly", derive(Encodable_Generic, Decodable_Generic, HashStable_Generic))]