Lift: take self by value

9 files changed, 127 insertions, 141 deletions

diff --git a/compiler/rustc_middle/src/macros.rs b/compiler/rustc_middle/src/macros.rs
index a5482b7bdcf..6ff0a94ebf3 100644
--- a/compiler/rustc_middle/src/macros.rs
+++ b/compiler/rustc_middle/src/macros.rs
@@ -29,8 +29,8 @@ macro_rules! CloneLiftImpls {
         $(
             impl<$tcx> $crate::ty::Lift<$tcx> for $ty {
                 type Lifted = Self;
-                fn lift_to_tcx(&self, _: $crate::ty::TyCtxt<$tcx>) -> Option<Self> {
-                    Some(Clone::clone(self))
+                fn lift_to_tcx(self, _: $crate::ty::TyCtxt<$tcx>) -> Option<Self> {
+                    Some(self)
                 }
             }
         )+
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index fa40995407f..05bcf2ba0ce 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -2210,7 +2210,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
 
                         let name = ty::tls::with(|tcx| {
                             let mut name = String::new();
-                            let substs = tcx.lift(&substs).expect("could not lift for printing");
+                            let substs = tcx.lift(substs).expect("could not lift for printing");
                             FmtPrinter::new(tcx, &mut name, Namespace::ValueNS)
                                 .print_def_path(variant_def.def_id, substs)?;
                             Ok(name)
@@ -2233,7 +2233,7 @@ impl<'tcx> Debug for Rvalue<'tcx> {
                         if let Some(def_id) = def_id.as_local() {
                             let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
                             let name = if tcx.sess.opts.debugging_opts.span_free_formats {
-                                let substs = tcx.lift(&substs).unwrap();
+                                let substs = tcx.lift(substs).unwrap();
                                 format!(
                                     "[closure@{}]",
                                     tcx.def_path_str_with_substs(def_id.to_def_id(), substs),
@@ -2527,7 +2527,7 @@ fn pretty_print_const(
 ) -> fmt::Result {
     use crate::ty::print::PrettyPrinter;
     ty::tls::with(|tcx| {
-        let literal = tcx.lift(&c).unwrap();
+        let literal = tcx.lift(c).unwrap();
         let mut cx = FmtPrinter::new(tcx, fmt, Namespace::ValueNS);
         cx.print_alloc_ids = true;
         cx.pretty_print_const(literal, print_types)?;
diff --git a/compiler/rustc_middle/src/mir/terminator.rs b/compiler/rustc_middle/src/mir/terminator.rs
index e1071454e65..c9493c67987 100644
--- a/compiler/rustc_middle/src/mir/terminator.rs
+++ b/compiler/rustc_middle/src/mir/terminator.rs
@@ -535,7 +535,7 @@ impl<'tcx> TerminatorKind<'tcx> {
             Goto { .. } => vec!["".into()],
             SwitchInt { ref targets, switch_ty, .. } => ty::tls::with(|tcx| {
                 let param_env = ty::ParamEnv::empty();
-                let switch_ty = tcx.lift(&switch_ty).unwrap();
+                let switch_ty = tcx.lift(switch_ty).unwrap();
                 let size = tcx.layout_of(param_env.and(switch_ty)).unwrap().size;
                 targets
                     .values
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 99c8300661d..29eccc4eae1 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -1057,7 +1057,7 @@ impl<'tcx> TyCtxt<'tcx> {
         )
     }
 
-    pub fn lift<T: ?Sized + Lift<'tcx>>(self, value: &T) -> Option<T::Lifted> {
+    pub fn lift<T: Lift<'tcx>>(self, value: T) -> Option<T::Lifted> {
         value.lift_to_tcx(self)
     }
 
@@ -1565,16 +1565,16 @@ impl<'tcx> TyCtxt<'tcx> {
 /// e.g., `()` or `u8`, was interned in a different context.
 pub trait Lift<'tcx>: fmt::Debug {
     type Lifted: fmt::Debug + 'tcx;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>;
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted>;
 }
 
 macro_rules! nop_lift {
     ($set:ident; $ty:ty => $lifted:ty) => {
         impl<'a, 'tcx> Lift<'tcx> for $ty {
             type Lifted = $lifted;
-            fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-                if tcx.interners.$set.contains_pointer_to(&Interned(*self)) {
-                    Some(unsafe { mem::transmute(*self) })
+            fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+                if tcx.interners.$set.contains_pointer_to(&Interned(self)) {
+                    Some(unsafe { mem::transmute(self) })
                 } else {
                     None
                 }
@@ -1587,12 +1587,12 @@ macro_rules! nop_list_lift {
     ($set:ident; $ty:ty => $lifted:ty) => {
         impl<'a, 'tcx> Lift<'tcx> for &'a List<$ty> {
             type Lifted = &'tcx List<$lifted>;
-            fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+            fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
                 if self.is_empty() {
                     return Some(List::empty());
                 }
-                if tcx.interners.$set.contains_pointer_to(&Interned(*self)) {
-                    Some(unsafe { mem::transmute(*self) })
+                if tcx.interners.$set.contains_pointer_to(&Interned(self)) {
+                    Some(unsafe { mem::transmute(self) })
                 } else {
                     None
                 }
diff --git a/compiler/rustc_middle/src/ty/error.rs b/compiler/rustc_middle/src/ty/error.rs
index 82d698b37ab..235f8749cf9 100644
--- a/compiler/rustc_middle/src/ty/error.rs
+++ b/compiler/rustc_middle/src/ty/error.rs
@@ -229,7 +229,7 @@ impl<'tcx> ty::TyS<'tcx> {
             ty::Adt(def, _) => format!("{} `{}`", def.descr(), tcx.def_path_str(def.did)).into(),
             ty::Foreign(def_id) => format!("extern type `{}`", tcx.def_path_str(def_id)).into(),
             ty::Array(t, n) => {
-                let n = tcx.lift(&n).unwrap();
+                let n = tcx.lift(n).unwrap();
                 match n.try_eval_usize(tcx, ty::ParamEnv::empty()) {
                     _ if t.is_simple_ty() => format!("array `{}`", self).into(),
                     Some(n) => format!("array of {} element{}", n, pluralize!(n)).into(),
diff --git a/compiler/rustc_middle/src/ty/instance.rs b/compiler/rustc_middle/src/ty/instance.rs
index 4a2c97b4a40..8b3fb875070 100644
--- a/compiler/rustc_middle/src/ty/instance.rs
+++ b/compiler/rustc_middle/src/ty/instance.rs
@@ -258,7 +258,7 @@ impl<'tcx> InstanceDef<'tcx> {
 impl<'tcx> fmt::Display for Instance<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         ty::tls::with(|tcx| {
-            let substs = tcx.lift(&self.substs).expect("could not lift for printing");
+            let substs = tcx.lift(self.substs).expect("could not lift for printing");
             FmtPrinter::new(tcx, &mut *f, Namespace::ValueNS)
                 .print_def_path(self.def_id(), substs)?;
             Ok(())
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index acdf1f642ab..de24322e07d 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1848,7 +1848,7 @@ macro_rules! forward_display_to_print {
         $(impl fmt::Display for $ty {
             fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
                 ty::tls::with(|tcx| {
-                    tcx.lift(self)
+                    tcx.lift(*self)
                         .expect("could not lift for printing")
                         .print(FmtPrinter::new(tcx, f, Namespace::TypeNS))?;
                     Ok(())
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 15803dbd842..a82a8c895bb 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -332,24 +332,25 @@ CloneTypeFoldableAndLiftImpls! {
 // FIXME(eddyb) replace all the uses of `Option::map` with `?`.
 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>> Lift<'tcx> for (A, B) {
     type Lifted = (A::Lifted, B::Lifted);
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.0).and_then(|a| tcx.lift(&self.1).map(|b| (a, b)))
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        let (a, b) = self;
+        tcx.lift(a).and_then(|a| tcx.lift(b).map(|b| (a, b)))
     }
 }
 
 impl<'tcx, A: Lift<'tcx>, B: Lift<'tcx>, C: Lift<'tcx>> Lift<'tcx> for (A, B, C) {
     type Lifted = (A::Lifted, B::Lifted, C::Lifted);
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.0)
-            .and_then(|a| tcx.lift(&self.1).and_then(|b| tcx.lift(&self.2).map(|c| (a, b, c))))
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        let (a, b, c) = self;
+        tcx.lift(a).and_then(|a| tcx.lift(b).and_then(|b| tcx.lift(c).map(|c| (a, b, c))))
     }
 }
 
 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
     type Lifted = Option<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        match *self {
-            Some(ref x) => tcx.lift(x).map(Some),
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        match self {
+            Some(x) => tcx.lift(x).map(Some),
             None => Some(None),
         }
     }
@@ -357,89 +358,72 @@ impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Option<T> {
 
 impl<'tcx, T: Lift<'tcx>, E: Lift<'tcx>> Lift<'tcx> for Result<T, E> {
     type Lifted = Result<T::Lifted, E::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        match *self {
-            Ok(ref x) => tcx.lift(x).map(Ok),
-            Err(ref e) => tcx.lift(e).map(Err),
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        match self {
+            Ok(x) => tcx.lift(x).map(Ok),
+            Err(e) => tcx.lift(e).map(Err),
         }
     }
 }
 
 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Box<T> {
     type Lifted = Box<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&**self).map(Box::new)
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(*self).map(Box::new)
     }
 }
 
-impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Rc<T> {
+impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Rc<T> {
     type Lifted = Rc<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&**self).map(Rc::new)
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.as_ref().clone()).map(Rc::new)
     }
 }
 
-impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Arc<T> {
+impl<'tcx, T: Lift<'tcx> + Clone> Lift<'tcx> for Arc<T> {
     type Lifted = Arc<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&**self).map(Arc::new)
-    }
-}
-
-impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for [T] {
-    type Lifted = Vec<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        // type annotation needed to inform `projection_must_outlive`
-        let mut result: Vec<<T as Lift<'tcx>>::Lifted> = Vec::with_capacity(self.len());
-        for x in self {
-            if let Some(value) = tcx.lift(x) {
-                result.push(value);
-            } else {
-                return None;
-            }
-        }
-        Some(result)
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.as_ref().clone()).map(Arc::new)
     }
 }
-
 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for Vec<T> {
     type Lifted = Vec<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self[..])
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        self.into_iter().map(|v| tcx.lift(v)).collect()
     }
 }
 
 impl<'tcx, I: Idx, T: Lift<'tcx>> Lift<'tcx> for IndexVec<I, T> {
     type Lifted = IndexVec<I, T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        self.iter().map(|e| tcx.lift(e)).collect()
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        self.into_iter().map(|e| tcx.lift(e)).collect()
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::TraitRef<'a> {
     type Lifted = ty::TraitRef<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.substs).map(|substs| ty::TraitRef { def_id: self.def_id, substs })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialTraitRef<'a> {
     type Lifted = ty::ExistentialTraitRef<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.substs).map(|substs| ty::ExistentialTraitRef { def_id: self.def_id, substs })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
     type Lifted = ty::ExistentialPredicate<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
         match self {
             ty::ExistentialPredicate::Trait(x) => tcx.lift(x).map(ty::ExistentialPredicate::Trait),
             ty::ExistentialPredicate::Projection(x) => {
                 tcx.lift(x).map(ty::ExistentialPredicate::Projection)
             }
             ty::ExistentialPredicate::AutoTrait(def_id) => {
-                Some(ty::ExistentialPredicate::AutoTrait(*def_id))
+                Some(ty::ExistentialPredicate::AutoTrait(def_id))
             }
         }
     }
@@ -447,15 +431,15 @@ impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialPredicate<'a> {
 
 impl<'a, 'tcx> Lift<'tcx> for ty::TraitPredicate<'a> {
     type Lifted = ty::TraitPredicate<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
-        tcx.lift(&self.trait_ref).map(|trait_ref| ty::TraitPredicate { trait_ref })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::TraitPredicate<'tcx>> {
+        tcx.lift(self.trait_ref).map(|trait_ref| ty::TraitPredicate { trait_ref })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
     type Lifted = ty::SubtypePredicate<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
-        tcx.lift(&(self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::SubtypePredicate<'tcx>> {
+        tcx.lift((self.a, self.b)).map(|(a, b)| ty::SubtypePredicate {
             a_is_expected: self.a_is_expected,
             a,
             b,
@@ -465,33 +449,33 @@ impl<'a, 'tcx> Lift<'tcx> for ty::SubtypePredicate<'a> {
 
 impl<'tcx, A: Copy + Lift<'tcx>, B: Copy + Lift<'tcx>> Lift<'tcx> for ty::OutlivesPredicate<A, B> {
     type Lifted = ty::OutlivesPredicate<A::Lifted, B::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&(self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift((self.0, self.1)).map(|(a, b)| ty::OutlivesPredicate(a, b))
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionTy<'a> {
     type Lifted = ty::ProjectionTy<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
-        tcx.lift(&self.substs)
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionTy<'tcx>> {
+        tcx.lift(self.substs)
             .map(|substs| ty::ProjectionTy { item_def_id: self.item_def_id, substs })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ProjectionPredicate<'a> {
     type Lifted = ty::ProjectionPredicate<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
-        tcx.lift(&(self.projection_ty, self.ty))
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<ty::ProjectionPredicate<'tcx>> {
+        tcx.lift((self.projection_ty, self.ty))
             .map(|(projection_ty, ty)| ty::ProjectionPredicate { projection_ty, ty })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
     type Lifted = ty::ExistentialProjection<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.substs).map(|substs| ty::ExistentialProjection {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.substs).map(|substs| ty::ExistentialProjection {
             substs,
-            ty: tcx.lift(&self.ty).expect("type must lift when substs do"),
+            ty: tcx.lift(self.ty).expect("type must lift when substs do"),
             item_def_id: self.item_def_id,
         })
     }
@@ -499,7 +483,7 @@ impl<'a, 'tcx> Lift<'tcx> for ty::ExistentialProjection<'a> {
 
 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
     type Lifted = ty::PredicateKind<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
         match self {
             ty::PredicateKind::ForAll(binder) => tcx.lift(binder).map(ty::PredicateKind::ForAll),
             ty::PredicateKind::Atom(atom) => tcx.lift(atom).map(ty::PredicateKind::Atom),
@@ -509,24 +493,24 @@ impl<'a, 'tcx> Lift<'tcx> for ty::PredicateKind<'a> {
 
 impl<'a, 'tcx> Lift<'tcx> for ty::PredicateAtom<'a> {
     type Lifted = ty::PredicateAtom<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        match *self {
-            ty::PredicateAtom::Trait(ref data, constness) => {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        match self {
+            ty::PredicateAtom::Trait(data, constness) => {
                 tcx.lift(data).map(|data| ty::PredicateAtom::Trait(data, constness))
             }
-            ty::PredicateAtom::Subtype(ref data) => tcx.lift(data).map(ty::PredicateAtom::Subtype),
-            ty::PredicateAtom::RegionOutlives(ref data) => {
+            ty::PredicateAtom::Subtype(data) => tcx.lift(data).map(ty::PredicateAtom::Subtype),
+            ty::PredicateAtom::RegionOutlives(data) => {
                 tcx.lift(data).map(ty::PredicateAtom::RegionOutlives)
             }
-            ty::PredicateAtom::TypeOutlives(ref data) => {
+            ty::PredicateAtom::TypeOutlives(data) => {
                 tcx.lift(data).map(ty::PredicateAtom::TypeOutlives)
             }
-            ty::PredicateAtom::Projection(ref data) => {
+            ty::PredicateAtom::Projection(data) => {
                 tcx.lift(data).map(ty::PredicateAtom::Projection)
             }
-            ty::PredicateAtom::WellFormed(ty) => tcx.lift(&ty).map(ty::PredicateAtom::WellFormed),
+            ty::PredicateAtom::WellFormed(ty) => tcx.lift(ty).map(ty::PredicateAtom::WellFormed),
             ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind) => {
-                tcx.lift(&closure_substs).map(|closure_substs| {
+                tcx.lift(closure_substs).map(|closure_substs| {
                     ty::PredicateAtom::ClosureKind(closure_def_id, closure_substs, kind)
                 })
             }
@@ -534,13 +518,13 @@ impl<'a, 'tcx> Lift<'tcx> for ty::PredicateAtom<'a> {
                 Some(ty::PredicateAtom::ObjectSafe(trait_def_id))
             }
             ty::PredicateAtom::ConstEvaluatable(def_id, substs) => {
-                tcx.lift(&substs).map(|substs| ty::PredicateAtom::ConstEvaluatable(def_id, substs))
+                tcx.lift(substs).map(|substs| ty::PredicateAtom::ConstEvaluatable(def_id, substs))
             }
             ty::PredicateAtom::ConstEquate(c1, c2) => {
-                tcx.lift(&(c1, c2)).map(|(c1, c2)| ty::PredicateAtom::ConstEquate(c1, c2))
+                tcx.lift((c1, c2)).map(|(c1, c2)| ty::PredicateAtom::ConstEquate(c1, c2))
             }
             ty::PredicateAtom::TypeWellFormedFromEnv(ty) => {
-                tcx.lift(&ty).map(ty::PredicateAtom::TypeWellFormedFromEnv)
+                tcx.lift(ty).map(ty::PredicateAtom::TypeWellFormedFromEnv)
             }
         }
     }
@@ -548,61 +532,62 @@ impl<'a, 'tcx> Lift<'tcx> for ty::PredicateAtom<'a> {
 
 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::Binder<T> {
     type Lifted = ty::Binder<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(self.as_ref().skip_binder()).map(|v| self.rebind(v))
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        self.map_bound(|v| tcx.lift(v)).transpose()
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ParamEnv<'a> {
     type Lifted = ty::ParamEnv<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.caller_bounds())
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.caller_bounds())
             .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal()))
     }
 }
 
 impl<'a, 'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::ParamEnvAnd<'a, T> {
     type Lifted = ty::ParamEnvAnd<'tcx, T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.param_env).and_then(|param_env| {
-            tcx.lift(&self.value).map(|value| ty::ParamEnvAnd { param_env, value })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.param_env).and_then(|param_env| {
+            tcx.lift(self.value).map(|value| ty::ParamEnvAnd { param_env, value })
         })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::ClosureSubsts<'a> {
     type Lifted = ty::ClosureSubsts<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.substs).map(|substs| ty::ClosureSubsts { substs })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.substs).map(|substs| ty::ClosureSubsts { substs })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::GeneratorSubsts<'a> {
     type Lifted = ty::GeneratorSubsts<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.substs).map(|substs| ty::GeneratorSubsts { substs })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.substs).map(|substs| ty::GeneratorSubsts { substs })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjustment<'a> {
     type Lifted = ty::adjustment::Adjustment<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.kind).and_then(|kind| {
-            tcx.lift(&self.target).map(|target| ty::adjustment::Adjustment { kind, target })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        let ty::adjustment::Adjustment { kind, target } = self;
+        tcx.lift(kind).and_then(|kind| {
+            tcx.lift(target).map(|target| ty::adjustment::Adjustment { kind, target })
         })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
     type Lifted = ty::adjustment::Adjust<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        match *self {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        match self {
             ty::adjustment::Adjust::NeverToAny => Some(ty::adjustment::Adjust::NeverToAny),
             ty::adjustment::Adjust::Pointer(ptr) => Some(ty::adjustment::Adjust::Pointer(ptr)),
-            ty::adjustment::Adjust::Deref(ref overloaded) => {
+            ty::adjustment::Adjust::Deref(overloaded) => {
                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
             }
-            ty::adjustment::Adjust::Borrow(ref autoref) => {
+            ty::adjustment::Adjust::Borrow(autoref) => {
                 tcx.lift(autoref).map(ty::adjustment::Adjust::Borrow)
             }
         }
@@ -611,8 +596,8 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
 
 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
     type Lifted = ty::adjustment::OverloadedDeref<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.region).map(|region| ty::adjustment::OverloadedDeref {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.region).map(|region| ty::adjustment::OverloadedDeref {
             region,
             mutbl: self.mutbl,
             span: self.span,
@@ -622,10 +607,10 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::OverloadedDeref<'a> {
 
 impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
     type Lifted = ty::adjustment::AutoBorrow<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        match *self {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        match self {
             ty::adjustment::AutoBorrow::Ref(r, m) => {
-                tcx.lift(&r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
+                tcx.lift(r).map(|r| ty::adjustment::AutoBorrow::Ref(r, m))
             }
             ty::adjustment::AutoBorrow::RawPtr(m) => Some(ty::adjustment::AutoBorrow::RawPtr(m)),
         }
@@ -634,16 +619,16 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::AutoBorrow<'a> {
 
 impl<'a, 'tcx> Lift<'tcx> for ty::GenSig<'a> {
     type Lifted = ty::GenSig<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&(self.resume_ty, self.yield_ty, self.return_ty))
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift((self.resume_ty, self.yield_ty, self.return_ty))
             .map(|(resume_ty, yield_ty, return_ty)| ty::GenSig { resume_ty, yield_ty, return_ty })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
     type Lifted = ty::FnSig<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.inputs_and_output).map(|x| ty::FnSig {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        tcx.lift(self.inputs_and_output).map(|x| ty::FnSig {
             inputs_and_output: x,
             c_variadic: self.c_variadic,
             unsafety: self.unsafety,
@@ -654,19 +639,20 @@ impl<'a, 'tcx> Lift<'tcx> for ty::FnSig<'a> {
 
 impl<'tcx, T: Lift<'tcx>> Lift<'tcx> for ty::error::ExpectedFound<T> {
     type Lifted = ty::error::ExpectedFound<T::Lifted>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        tcx.lift(&self.expected).and_then(|expected| {
-            tcx.lift(&self.found).map(|found| ty::error::ExpectedFound { expected, found })
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        let ty::error::ExpectedFound { expected, found } = self;
+        tcx.lift(expected).and_then(|expected| {
+            tcx.lift(found).map(|found| ty::error::ExpectedFound { expected, found })
         })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
     type Lifted = ty::error::TypeError<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
         use crate::ty::error::TypeError::*;
 
-        Some(match *self {
+        Some(match self {
             Mismatch => Mismatch,
             UnsafetyMismatch(x) => UnsafetyMismatch(x),
             AbiMismatch(x) => AbiMismatch(x),
@@ -675,51 +661,51 @@ impl<'a, 'tcx> Lift<'tcx> for ty::error::TypeError<'a> {
             FixedArraySize(x) => FixedArraySize(x),
             ArgCount => ArgCount,
             RegionsDoesNotOutlive(a, b) => {
-                return tcx.lift(&(a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
+                return tcx.lift((a, b)).map(|(a, b)| RegionsDoesNotOutlive(a, b));
             }
             RegionsInsufficientlyPolymorphic(a, b) => {
-                return tcx.lift(&b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
+                return tcx.lift(b).map(|b| RegionsInsufficientlyPolymorphic(a, b));
             }
             RegionsOverlyPolymorphic(a, b) => {
-                return tcx.lift(&b).map(|b| RegionsOverlyPolymorphic(a, b));
+                return tcx.lift(b).map(|b| RegionsOverlyPolymorphic(a, b));
             }
             RegionsPlaceholderMismatch => RegionsPlaceholderMismatch,
             IntMismatch(x) => IntMismatch(x),
             FloatMismatch(x) => FloatMismatch(x),
             Traits(x) => Traits(x),
             VariadicMismatch(x) => VariadicMismatch(x),
-            CyclicTy(t) => return tcx.lift(&t).map(|t| CyclicTy(t)),
-            CyclicConst(ct) => return tcx.lift(&ct).map(|ct| CyclicConst(ct)),
+            CyclicTy(t) => return tcx.lift(t).map(|t| CyclicTy(t)),
+            CyclicConst(ct) => return tcx.lift(ct).map(|ct| CyclicConst(ct)),
             ProjectionMismatched(x) => ProjectionMismatched(x),
-            Sorts(ref x) => return tcx.lift(x).map(Sorts),
-            ExistentialMismatch(ref x) => return tcx.lift(x).map(ExistentialMismatch),
-            ConstMismatch(ref x) => return tcx.lift(x).map(ConstMismatch),
+            Sorts(x) => return tcx.lift(x).map(Sorts),
+            ExistentialMismatch(x) => return tcx.lift(x).map(ExistentialMismatch),
+            ConstMismatch(x) => return tcx.lift(x).map(ConstMismatch),
             IntrinsicCast => IntrinsicCast,
-            TargetFeatureCast(ref x) => TargetFeatureCast(*x),
-            ObjectUnsafeCoercion(ref x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
+            TargetFeatureCast(x) => TargetFeatureCast(x),
+            ObjectUnsafeCoercion(x) => return tcx.lift(x).map(ObjectUnsafeCoercion),
         })
     }
 }
 
 impl<'a, 'tcx> Lift<'tcx> for ty::InstanceDef<'a> {
     type Lifted = ty::InstanceDef<'tcx>;
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
-        match *self {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+        match self {
             ty::InstanceDef::Item(def_id) => Some(ty::InstanceDef::Item(def_id)),
             ty::InstanceDef::VtableShim(def_id) => Some(ty::InstanceDef::VtableShim(def_id)),
             ty::InstanceDef::ReifyShim(def_id) => Some(ty::InstanceDef::ReifyShim(def_id)),
             ty::InstanceDef::Intrinsic(def_id) => Some(ty::InstanceDef::Intrinsic(def_id)),
-            ty::InstanceDef::FnPtrShim(def_id, ref ty) => {
+            ty::InstanceDef::FnPtrShim(def_id, ty) => {
                 Some(ty::InstanceDef::FnPtrShim(def_id, tcx.lift(ty)?))
             }
             ty::InstanceDef::Virtual(def_id, n) => Some(ty::InstanceDef::Virtual(def_id, n)),
             ty::InstanceDef::ClosureOnceShim { call_once } => {
                 Some(ty::InstanceDef::ClosureOnceShim { call_once })
             }
-            ty::InstanceDef::DropGlue(def_id, ref ty) => {
+            ty::InstanceDef::DropGlue(def_id, ty) => {
                 Some(ty::InstanceDef::DropGlue(def_id, tcx.lift(ty)?))
             }
-            ty::InstanceDef::CloneShim(def_id, ref ty) => {
+            ty::InstanceDef::CloneShim(def_id, ty) => {
                 Some(ty::InstanceDef::CloneShim(def_id, tcx.lift(ty)?))
             }
         }
diff --git a/compiler/rustc_middle/src/ty/subst.rs b/compiler/rustc_middle/src/ty/subst.rs
index 7d96adb7c8b..f04144c218e 100644
--- a/compiler/rustc_middle/src/ty/subst.rs
+++ b/compiler/rustc_middle/src/ty/subst.rs
@@ -141,11 +141,11 @@ impl<'tcx> GenericArg<'tcx> {
 impl<'a, 'tcx> Lift<'tcx> for GenericArg<'a> {
     type Lifted = GenericArg<'tcx>;
 
-    fn lift_to_tcx(&self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
+    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
         match self.unpack() {
-            GenericArgKind::Lifetime(lt) => tcx.lift(&lt).map(|lt| lt.into()),
-            GenericArgKind::Type(ty) => tcx.lift(&ty).map(|ty| ty.into()),
-            GenericArgKind::Const(ct) => tcx.lift(&ct).map(|ct| ct.into()),
+            GenericArgKind::Lifetime(lt) => tcx.lift(lt).map(|lt| lt.into()),
+            GenericArgKind::Type(ty) => tcx.lift(ty).map(|ty| ty.into()),
+            GenericArgKind::Const(ct) => tcx.lift(ct).map(|ct| ct.into()),
         }
     }
 }