From 53effa4566dc1493e1dc5be206105dd99e3192b5 Mon Sep 17 00:00:00 2001
From: Amanda Stjerna <amanda.stjerna@it.uu.se>
Date: Tue, 18 Feb 2025 13:01:01 +0100
Subject: [PATCH] eval_outlives: bail out early if both regions are in the same
 SCC

---
 compiler/rustc_borrowck/src/region_infer/mod.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/compiler/rustc_borrowck/src/region_infer/mod.rs b/compiler/rustc_borrowck/src/region_infer/mod.rs
index d2268c4779d6..e0e3e028c612 100644
--- a/compiler/rustc_borrowck/src/region_infer/mod.rs
+++ b/compiler/rustc_borrowck/src/region_infer/mod.rs
@@ -1267,6 +1267,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
         let sub_region_scc = self.constraint_sccs.scc(sub_region);
         let sup_region_scc = self.constraint_sccs.scc(sup_region);
 
+        if sub_region_scc == sup_region_scc {
+            debug!("{sup_region:?}: {sub_region:?} holds trivially; they are in the same SCC");
+            return true;
+        }
+
         // If we are checking that `'sup: 'sub`, and `'sub` contains
         // some placeholder that `'sup` cannot name, then this is only
         // true if `'sup` outlives static.