From 2bba98b1216e21fcb18e2242c491ae7205af8308 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jon=C3=A1=C5=A1=20Fiala?= <jonas.fiala@inf.ethz.ch>
Date: Mon, 16 Oct 2023 14:29:36 +0200
Subject: [PATCH] Avoid unnecessary renumbering

---
 compiler/rustc_borrowck/src/renumber.rs | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/compiler/rustc_borrowck/src/renumber.rs b/compiler/rustc_borrowck/src/renumber.rs
index 5d6f5cc896782..ec0131c5349a1 100644
--- a/compiler/rustc_borrowck/src/renumber.rs
+++ b/compiler/rustc_borrowck/src/renumber.rs
@@ -81,6 +81,10 @@ impl<'a, 'tcx> MutVisitor<'tcx> for RegionRenumberer<'a, 'tcx> {
 
     #[instrument(skip(self), level = "debug")]
     fn visit_ty(&mut self, ty: &mut Ty<'tcx>, ty_context: TyContext) {
+        if matches!(ty_context, TyContext::ReturnTy(_)) {
+            // We will renumber the return ty when called again with `TyContext::LocalDecl`
+            return;
+        }
         *ty = self.renumber_regions(*ty, || RegionCtxt::TyContext(ty_context));
 
         debug!(?ty);