From 060f3e0c657d7556e51a19a6290cca050b29dc57 Mon Sep 17 00:00:00 2001
From: lcnr <rust@lcnr.de>
Date: Mon, 4 Jul 2022 15:35:21 +0200
Subject: [PATCH] generalize: no need to cache errors

---
 compiler/rustc_infer/src/infer/combine.rs | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index d4350aa5734..644c92ed0e5 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -486,7 +486,7 @@ struct Generalizer<'cx, 'tcx> {
 
     param_env: ty::ParamEnv<'tcx>,
 
-    cache: SsoHashMap<Ty<'tcx>, RelateResult<'tcx, Ty<'tcx>>>,
+    cache: SsoHashMap<Ty<'tcx>, Ty<'tcx>>,
 }
 
 /// Result from a generalization operation. This includes
@@ -593,8 +593,8 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
     fn tys(&mut self, t: Ty<'tcx>, t2: Ty<'tcx>) -> RelateResult<'tcx, Ty<'tcx>> {
         assert_eq!(t, t2); // we are abusing TypeRelation here; both LHS and RHS ought to be ==
 
-        if let Some(result) = self.cache.get(&t) {
-            return result.clone();
+        if let Some(&result) = self.cache.get(&t) {
+            return Ok(result);
         }
         debug!("generalize: t={:?}", t);
 
@@ -664,10 +664,10 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                 Ok(t)
             }
             _ => relate::super_relate_tys(self, t, t),
-        };
+        }?;
 
-        self.cache.insert(t, result.clone());
-        return result;
+        self.cache.insert(t, result);
+        Ok(result)
     }
 
     fn regions(