From 2198faeee2a1e3abf30fa71a032aa76c2545c4e3 Mon Sep 17 00:00:00 2001
From: Obei Sideg <obei.sideg@gmail.com>
Date: Mon, 8 May 2023 23:38:54 +0300
Subject: [PATCH] Make `NonUseContext::AscribeUserTy` carry `ty::Variance`

---
 compiler/rustc_borrowck/src/def_use.rs        | 2 +-
 compiler/rustc_borrowck/src/type_check/mod.rs | 2 +-
 compiler/rustc_middle/src/mir/visit.rs        | 8 ++++----
 compiler/rustc_type_ir/src/lib.rs             | 2 +-
 4 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/compiler/rustc_borrowck/src/def_use.rs b/compiler/rustc_borrowck/src/def_use.rs
index 74e6ce37e971a..b775739fed2ae 100644
--- a/compiler/rustc_borrowck/src/def_use.rs
+++ b/compiler/rustc_borrowck/src/def_use.rs
@@ -55,7 +55,7 @@ pub fn categorize(context: PlaceContext) -> Option<DefUse> {
         // `PlaceMention` and `AscribeUserType` both evaluate the place, which must not
         // contain dangling references.
         PlaceContext::NonMutatingUse(NonMutatingUseContext::PlaceMention) |
-        PlaceContext::NonUse(NonUseContext::AscribeUserTy) |
+        PlaceContext::NonUse(NonUseContext::AscribeUserTy(_)) |
 
         PlaceContext::MutatingUse(MutatingUseContext::AddressOf) |
         PlaceContext::NonMutatingUse(NonMutatingUseContext::AddressOf) |
diff --git a/compiler/rustc_borrowck/src/type_check/mod.rs b/compiler/rustc_borrowck/src/type_check/mod.rs
index dcabeb792be3e..33b24b68f7cfc 100644
--- a/compiler/rustc_borrowck/src/type_check/mod.rs
+++ b/compiler/rustc_borrowck/src/type_check/mod.rs
@@ -777,7 +777,7 @@ impl<'a, 'b, 'tcx> TypeVerifier<'a, 'b, 'tcx> {
                 Inspect | Copy | Move | PlaceMention | SharedBorrow | ShallowBorrow | UniqueBorrow
                 | AddressOf | Projection,
             ) => ty::Covariant,
-            PlaceContext::NonUse(AscribeUserTy) => ty::Covariant,
+            PlaceContext::NonUse(AscribeUserTy(variance)) => variance,
         }
     }
 
diff --git a/compiler/rustc_middle/src/mir/visit.rs b/compiler/rustc_middle/src/mir/visit.rs
index 6718605ed0bc4..4b7014e31090b 100644
--- a/compiler/rustc_middle/src/mir/visit.rs
+++ b/compiler/rustc_middle/src/mir/visit.rs
@@ -64,7 +64,7 @@
 
 use crate::mir::*;
 use crate::ty::subst::SubstsRef;
-use crate::ty::{CanonicalUserTypeAnnotation, Ty};
+use crate::ty::{self, CanonicalUserTypeAnnotation, Ty};
 use rustc_span::Span;
 
 macro_rules! make_mir_visitor {
@@ -782,12 +782,12 @@ macro_rules! make_mir_visitor {
 
             fn super_ascribe_user_ty(&mut self,
                                      place: & $($mutability)? Place<'tcx>,
-                                     _variance: $(& $mutability)? ty::Variance,
+                                     variance: $(& $mutability)? ty::Variance,
                                      user_ty: & $($mutability)? UserTypeProjection,
                                      location: Location) {
                 self.visit_place(
                     place,
-                    PlaceContext::NonUse(NonUseContext::AscribeUserTy),
+                    PlaceContext::NonUse(NonUseContext::AscribeUserTy($(* &$mutability *)? variance)),
                     location
                 );
                 self.visit_user_type_projection(user_ty);
@@ -1320,7 +1320,7 @@ pub enum NonUseContext {
     /// Ending a storage live range.
     StorageDead,
     /// User type annotation assertions for NLL.
-    AscribeUserTy,
+    AscribeUserTy(ty::Variance),
     /// The data of a user variable, for debug info.
     VarDebugInfo,
 }
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index 1e91e26e2afe9..da043ba691c64 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -640,7 +640,7 @@ impl UnifyKey for FloatVid {
     }
 }
 
-#[derive(Copy, Clone, PartialEq, Decodable, Encodable, Hash, HashStable_Generic)]
+#[derive(Copy, Clone, PartialEq, Eq, Decodable, Encodable, Hash, HashStable_Generic)]
 #[rustc_pass_by_value]
 pub enum Variance {
     Covariant,     // T<A> <: T<B> iff A <: B -- e.g., function return type