Remove more unused Lift impls.

Author: nnethercote

Diff for: compiler/rustc_infer/src/infer/free_regions.rs

@@ -4,7 +4,7 @@
 //! and use that to decide when one free region outlives another, and so forth.
 
 use rustc_data_structures::transitive_relation::TransitiveRelation;
-use rustc_middle::ty::{Lift, Region, TyCtxt};
+use rustc_middle::ty::{Region, TyCtxt};
 
 /// Combines a `FreeRegionMap` and a `TyCtxt`.
 ///
@@ -101,10 +101,3 @@ impl<'tcx> FreeRegionMap<'tcx> {
         result
     }
 }
-
-impl<'a, 'tcx> Lift<'tcx> for FreeRegionMap<'a> {
-    type Lifted = FreeRegionMap<'tcx>;
-    fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<FreeRegionMap<'tcx>> {
-        self.relation.maybe_map(|fr| tcx.lift(fr)).map(|relation| FreeRegionMap { relation })
-    }
-}

Diff for: compiler/rustc_middle/src/infer/canonical.rs

@@ -432,7 +432,7 @@ impl<'tcx, V> Canonical<'tcx, V> {
 pub type QueryOutlivesConstraint<'tcx> =
     (ty::OutlivesPredicate<GenericArg<'tcx>, Region<'tcx>>, ConstraintCategory<'tcx>);
 
-TrivialTypeTraversalAndLiftImpls! {
+TrivialTypeTraversalImpls! {
     crate::infer::canonical::Certainty,
     crate::infer::canonical::CanonicalTyVarKind,
 }

Diff for: compiler/rustc_middle/src/mir/basic_blocks.rs

@@ -178,7 +178,7 @@ impl<'tcx> graph::WithPredecessors for BasicBlocks<'tcx> {
     }
 }
 
-TrivialTypeTraversalAndLiftImpls! { Cache }
+TrivialTypeTraversalImpls! { Cache }
 
 impl<S: Encoder> Encodable<S> for Cache {
     #[inline]

Diff for: compiler/rustc_middle/src/mir/interpret/error.rs

@@ -67,7 +67,7 @@ impl Into<ErrorGuaranteed> for ReportedErrorInfo {
     }
 }
 
-TrivialTypeTraversalAndLiftImpls! { ErrorHandled }
+TrivialTypeTraversalImpls! { ErrorHandled }
 
 pub type EvalToAllocationRawResult<'tcx> = Result<ConstAlloc<'tcx>, ErrorHandled>;
 pub type EvalToConstValueResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>;

Diff for: compiler/rustc_middle/src/mir/mod.rs

@@ -744,7 +744,7 @@ pub enum BindingForm<'tcx> {
     RefForGuard,
 }
 
-TrivialTypeTraversalAndLiftImpls! { BindingForm<'tcx> }
+TrivialTypeTraversalImpls! { BindingForm<'tcx> }
 
 mod binding_form_impl {
     use rustc_data_structures::stable_hasher::{HashStable, StableHasher};

Diff for: compiler/rustc_middle/src/mir/type_foldable.rs

@@ -5,7 +5,7 @@ use rustc_ast::InlineAsmTemplatePiece;
 use super::*;
 use crate::ty;
 
-TrivialTypeTraversalAndLiftImpls! {
+TrivialTypeTraversalImpls! {
     BlockTailInfo,
     MirPhase,
     SourceInfo,

Diff for: compiler/rustc_middle/src/traits/mod.rs

@@ -13,7 +13,7 @@ use crate::infer::canonical::Canonical;
 use crate::mir::ConstraintCategory;
 use crate::ty::abstract_const::NotConstEvaluatable;
 use crate::ty::GenericArgsRef;
-use crate::ty::{self, AdtKind, Ty, TyCtxt};
+use crate::ty::{self, AdtKind, Ty};
 
 use rustc_data_structures::sync::Lrc;
 use rustc_errors::{Applicability, Diagnostic};
@@ -524,13 +524,6 @@ pub enum StatementAsExpression {
     NeedsBoxing,
 }
 
-impl<'tcx> ty::Lift<'tcx> for StatementAsExpression {
-    type Lifted = StatementAsExpression;
-    fn lift_to_tcx(self, _tcx: TyCtxt<'tcx>) -> Option<StatementAsExpression> {
-        Some(self)
-    }
-}
-
 #[derive(Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable)]
 #[derive(TypeVisitable, TypeFoldable)]
 pub struct MatchExpressionArmCause<'tcx> {
@@ -736,7 +729,7 @@ pub enum BuiltinImplSource {
     TupleUnsizing,
 }
 
-TrivialTypeTraversalAndLiftImpls! { BuiltinImplSource }
+TrivialTypeTraversalImpls! { BuiltinImplSource }
 
 #[derive(Clone, Debug, PartialEq, Eq, Hash, HashStable, PartialOrd, Ord)]
 pub enum ObjectSafetyViolation {

Diff for: compiler/rustc_middle/src/traits/select.rs

@@ -305,7 +305,7 @@ impl From<ErrorGuaranteed> for OverflowError {
     }
 }
 
-TrivialTypeTraversalAndLiftImpls! { OverflowError }
+TrivialTypeTraversalImpls! { OverflowError }
 
 impl<'tcx> From<OverflowError> for SelectionError<'tcx> {
     fn from(overflow_error: OverflowError) -> SelectionError<'tcx> {

Diff for: compiler/rustc_middle/src/ty/abstract_const.rs

@@ -27,7 +27,7 @@ impl From<ErrorGuaranteed> for NotConstEvaluatable {
     }
 }
 
-TrivialTypeTraversalAndLiftImpls! { NotConstEvaluatable }
+TrivialTypeTraversalImpls! { NotConstEvaluatable }
 
 pub type BoundAbstractConst<'tcx> = Result<Option<EarlyBinder<ty::Const<'tcx>>>, ErrorGuaranteed>;
 

Diff for: compiler/rustc_middle/src/ty/binding.rs

@@ -6,7 +6,7 @@ pub enum BindingMode {
     BindByValue(Mutability),
 }
 
-TrivialTypeTraversalAndLiftImpls! { BindingMode }
+TrivialTypeTraversalImpls! { BindingMode }
 
 impl BindingMode {
     pub fn convert(BindingAnnotation(by_ref, mutbl): BindingAnnotation) -> BindingMode {

Diff for: compiler/rustc_middle/src/ty/context.rs

@@ -50,7 +50,7 @@ use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LOCAL_CRATE};
 use rustc_hir::definitions::Definitions;
 use rustc_hir::intravisit::Visitor;
 use rustc_hir::lang_items::LangItem;
-use rustc_hir::{Constness, HirId, Node, TraitCandidate};
+use rustc_hir::{HirId, Node, TraitCandidate};
 use rustc_index::IndexVec;
 use rustc_macros::HashStable;
 use rustc_query_system::dep_graph::DepNodeIndex;
@@ -1251,19 +1251,13 @@ nop_lift! {predicate; Clause<'a> => Clause<'tcx>}
 
 nop_list_lift! {type_lists; Ty<'a> => Ty<'tcx>}
 nop_list_lift! {poly_existential_predicates; PolyExistentialPredicate<'a> => PolyExistentialPredicate<'tcx>}
-nop_list_lift! {clauses; Clause<'a> => Clause<'tcx>}
-nop_list_lift! {canonical_var_infos; CanonicalVarInfo<'a> => CanonicalVarInfo<'tcx>}
-nop_list_lift! {projs; ProjectionKind => ProjectionKind}
 nop_list_lift! {bound_variable_kinds; ty::BoundVariableKind => ty::BoundVariableKind}
 
 // This is the impl for `&'a GenericArgs<'a>`.
 nop_list_lift! {args; GenericArg<'a> => GenericArg<'tcx>}
 
 TrivialLiftImpls! {
-    Constness,
-    traits::WellFormedLoc,
     ImplPolarity,
-    crate::mir::ReturnConstraint,
 }
 
 macro_rules! sty_debug_print {

Diff for: compiler/rustc_middle/src/ty/structural_impls.rs

@@ -9,14 +9,11 @@ use crate::ty::print::{with_no_trimmed_paths, FmtPrinter, Printer};
 use crate::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitor};
 use crate::ty::{self, AliasTy, InferConst, Lift, Term, TermKind, Ty, TyCtxt};
 use rustc_hir::def::Namespace;
-use rustc_index::{Idx, IndexVec};
 use rustc_target::abi::TyAndLayout;
 use rustc_type_ir::{ConstKind, DebugWithInfcx, InferCtxtLike, OptWithInfcx};
 
 use std::fmt::{self, Debug};
 use std::ops::ControlFlow;
-use std::rc::Rc;
-use std::sync::Arc;
 
 use super::print::PrettyPrinter;
 use super::{GenericArg, GenericArgKind, Region};
@@ -457,21 +454,15 @@ impl<'tcx, T: DebugWithInfcx<TyCtxt<'tcx>>> DebugWithInfcx<TyCtxt<'tcx>> for ty:
 // For things for which the type library provides traversal implementations
 // for all Interners, we only need to provide a Lift implementation:
 TrivialLiftImpls! {
-    (),
-    bool,
-    usize,
-    u16,
-    u32,
-    u64,
-    String,
-    rustc_type_ir::DebruijnIndex,
-}
-
-// For things about which the type library does not know, or does not
-// provide any traversal implementations, we need to provide both a Lift
-// implementation and traversal implementations (the latter only for
-// TyCtxt<'_> interners).
-TrivialTypeTraversalAndLiftImpls! {
+     (),
+     bool,
+     usize,
+}
+
+// For some things about which the type library does not know, or does not
+// provide any traversal implementations, we need to provide a traversal
+// implementation (only for TyCtxt<'_> interners).
+TrivialTypeTraversalImpls! {
     ::rustc_target::abi::FieldIdx,
     ::rustc_target::abi::VariantIdx,
     crate::middle::region::Scope,
@@ -481,14 +472,10 @@ TrivialTypeTraversalAndLiftImpls! {
     ::rustc_ast::NodeId,
     ::rustc_span::symbol::Symbol,
     ::rustc_hir::def::Res,
-    ::rustc_hir::def_id::DefId,
     ::rustc_hir::def_id::LocalDefId,
     ::rustc_hir::HirId,
     ::rustc_hir::MatchSource,
-    ::rustc_hir::Mutability,
-    ::rustc_hir::Unsafety,
     ::rustc_target::asm::InlineAsmRegOrRegClass,
-    ::rustc_target::spec::abi::Abi,
     crate::mir::coverage::CounterId,
     crate::mir::coverage::ExpressionId,
     crate::mir::coverage::MappedExpressionIndex,
@@ -506,50 +493,43 @@ TrivialTypeTraversalAndLiftImpls! {
     crate::ty::AssocItem,
     crate::ty::AssocKind,
     crate::ty::AliasKind,
-    crate::ty::AliasRelationDirection,
     crate::ty::Placeholder<crate::ty::BoundRegion>,
     crate::ty::Placeholder<crate::ty::BoundTy>,
     crate::ty::Placeholder<ty::BoundVar>,
-    crate::ty::ClosureKind,
     crate::ty::FreeRegion,
     crate::ty::InferTy,
     crate::ty::IntVarValue,
-    crate::ty::ParamConst,
-    crate::ty::ParamTy,
     crate::ty::adjustment::PointerCoercion,
     crate::ty::RegionVid,
     crate::ty::UniverseIndex,
     crate::ty::Variance,
     ::rustc_span::Span,
     ::rustc_span::symbol::Ident,
     ::rustc_errors::ErrorGuaranteed,
-    interpret::Scalar,
-    interpret::AllocId,
-    rustc_target::abi::Size,
     ty::BoundVar,
+    ty::ValTree<'tcx>,
 }
-
+// For some things about which the type library does not know, or does not
+// provide any traversal implementations, we need to provide a traversal
+// implementation and a lift implementation (the former only for TyCtxt<'_>
+// interners).
 TrivialTypeTraversalAndLiftImpls! {
-    ty::ValTree<'tcx>,
+    ::rustc_hir::def_id::DefId,
+    ::rustc_hir::Mutability,
+    ::rustc_hir::Unsafety,
+    ::rustc_target::spec::abi::Abi,
+    crate::ty::AliasRelationDirection,
+    crate::ty::ClosureKind,
+    crate::ty::ParamConst,
+    crate::ty::ParamTy,
+    interpret::Scalar,
+    interpret::AllocId,
+    rustc_target::abi::Size,
 }
 
 ///////////////////////////////////////////////////////////////////////////
 // Lift implementations
 
-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> {
-        Some((tcx.lift(self.0)?, tcx.lift(self.1)?))
-    }
-}
-
-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> {
-        Some((tcx.lift(self.0)?, tcx.lift(self.1)?, tcx.lift(self.2)?))
-    }
-}
-
 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> {
@@ -560,50 +540,6 @@ 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(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> {
-        Some(Box::new(tcx.lift(*self)?))
-    }
-}
-
-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> {
-        Some(Rc::new(tcx.lift(self.as_ref().clone())?))
-    }
-}
-
-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> {
-        Some(Arc::new(tcx.lift(self.as_ref().clone())?))
-    }
-}
-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> {
-        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.into_iter().map(|e| tcx.lift(e)).collect()
-    }
-}
-
 impl<'a, 'tcx> Lift<'tcx> for Term<'a> {
     type Lifted = ty::Term<'tcx>;
     fn lift_to_tcx(self, tcx: TyCtxt<'tcx>) -> Option<Self::Lifted> {
@@ -616,13 +552,6 @@ impl<'a, 'tcx> Lift<'tcx> for Term<'a> {
         )
     }
 }
-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())
-            .map(|caller_bounds| ty::ParamEnv::new(caller_bounds, self.reveal()))
-    }
-}
 
 ///////////////////////////////////////////////////////////////////////////
 // Traversal implementations.