From 758cc957638e4edcfd9985e9f32e46f1dbac1fc1 Mon Sep 17 00:00:00 2001
From: b-naber <b_naber@gmx.de>
Date: Wed, 15 Feb 2023 21:13:12 +0000
Subject: [PATCH] exhaustive matching in get_ambient_variance

---
 compiler/rustc_borrowck/src/type_check/mod.rs | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index 4244c76be13..c2d6e22d57b 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -767,9 +767,17 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
     }
 
     fn get_ambient_variance(&self, context: PlaceContext) -> ty::Variance {
+        use rustc_middle::mir::visit::NonMutatingUseContext::*;
+        use rustc_middle::mir::visit::NonUseContext::*;
+
         match context {
             PlaceContext::MutatingUse(_) => ty::Invariant,
-            PlaceContext::NonMutatingUse(_) | PlaceContext::NonUse(_) => ty::Covariant,
+            PlaceContext::NonUse(StorageDead | StorageLive | VarDebugInfo) => ty::Invariant,
+            PlaceContext::NonMutatingUse(
+                Inspect | Copy | Move | SharedBorrow | ShallowBorrow | UniqueBorrow | AddressOf
+                | Projection,
+            ) => ty::Covariant,
+            PlaceContext::NonUse(AscribeUserTy) => ty::Covariant,
         }
     }