Auto merge of #108340 - eggyal:remove_traversal_trait_aliases, r=oli-obk

Remove type-traversal trait aliases

#107924 moved the type traversal (folding and visiting) traits into the type library, but created trait aliases in `rustc_middle` to minimise both the API churn for trait consumers and the arising boilerplate.  As mentioned in that PR, an alternative approach of defining subtraits with blanket implementations of the respective supertraits was also considered at that time but was ruled out as not adding much value.

Unfortunately, it has since emerged that rust-analyzer has difficulty with these trait aliases at present, resulting in a degraded contributor experience (see the recent [r-a has become useless](https://rust-lang.zulipchat.com/#narrow/stream/182449-t-compiler.2Fhelp/topic/r-a.20has.20become.20useless) topic on the #t-compiler/help Zulip stream).

This PR removes the trait aliases, and accordingly the underlying type library traits are now used directly; they are parameterised by `TyCtxt<'tcx>` rather than just the `'tcx` lifetime, and imports have been updated to reflect the fact that the trait aliases' explicitly named traits are no longer automatically brought into scope.  These changes also roll-back the (no-longer required) workarounds to #107747 that were made in b409329c62.

Since this PR is just a find+replace together with the changes necessary for compilation & tidy to pass, it's currently just one mega-commit.  Let me know if you'd like it broken up.

r? `@oli-obk`

compiler/rustc_borrowck/src/constraint_generation.rs

@@ -9,7 +9,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::ty::subst::SubstsRef;
 use rustc_middle::ty::visit::TypeVisitable;
-use rustc_middle::ty::{self, RegionVid, Ty};
+use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt};
 
 use crate::{
     borrow_set::BorrowSet, facts::AllFacts, location::LocationTable, nll::ToRegionVid,
@@ -165,7 +165,7 @@ impl<'cx, 'tcx> ConstraintGeneration<'cx, 'tcx> {
     /// `location`.
     fn add_regular_live_constraint<T>(&mut self, live_ty: T, location: Location)
     where
-        T: TypeVisitable<'tcx>,
+        T: TypeVisitable<TyCtxt<'tcx>>,
     {
         debug!("add_regular_live_constraint(live_ty={:?}, location={:?})", live_ty, location);
 

compiler/rustc_borrowck/src/diagnostics/bound_region_errors.rs

@@ -106,7 +106,7 @@ impl<'tcx> ToUniverseInfo<'tcx>
     }
 }
 
-impl<'tcx, T: Copy + fmt::Display + TypeFoldable<'tcx> + 'tcx> ToUniverseInfo<'tcx>
+impl<'tcx, T: Copy + fmt::Display + TypeFoldable<TyCtxt<'tcx>> + 'tcx> ToUniverseInfo<'tcx>
     for Canonical<'tcx, ty::ParamEnvAnd<'tcx, type_op::Normalize<T>>>
 {
     fn to_universe_info(self, base_universe: ty::UniverseIndex) -> UniverseInfo<'tcx> {
@@ -258,7 +258,7 @@ struct NormalizeQuery<'tcx, T> {
 
 impl<'tcx, T> TypeOpInfo<'tcx> for NormalizeQuery<'tcx, T>
 where
-    T: Copy + fmt::Display + TypeFoldable<'tcx> + 'tcx,
+    T: Copy + fmt::Display + TypeFoldable<TyCtxt<'tcx>> + 'tcx,
 {
     fn fallback_error(
         &self,

compiler/rustc_borrowck/src/region_infer/mod.rs

@@ -17,7 +17,7 @@ use rustc_middle::mir::{
 };
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::ObligationCauseCode;
-use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
 use rustc_span::Span;
 
 use crate::{
@@ -1366,7 +1366,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// we use this kind of hacky solution.
     fn normalize_to_scc_representatives<T>(&self, tcx: TyCtxt<'tcx>, value: T) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         tcx.fold_regions(value, |r, _db| {
             let vid = self.to_region_vid(r);

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -6,7 +6,7 @@ use rustc_infer::infer::TyCtxtInferExt as _;
 use rustc_infer::infer::{DefiningAnchor, InferCtxt};
 use rustc_infer::traits::{Obligation, ObligationCause};
 use rustc_middle::ty::subst::{GenericArgKind, InternalSubsts};
-use rustc_middle::ty::visit::TypeVisitable;
+use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable};
 use rustc_span::Span;
 use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
@@ -178,7 +178,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
     /// region names in error messages.
     pub(crate) fn name_regions<T>(&self, tcx: TyCtxt<'tcx>, ty: T) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         tcx.fold_regions(ty, |region, _| match *region {
             ty::ReVar(vid) => {

compiler/rustc_borrowck/src/renumber.rs

@@ -38,7 +38,7 @@ pub(crate) fn renumber_regions<'tcx, T, F>(
     get_ctxt_fn: F,
 ) -> T
 where
-    T: TypeFoldable<'tcx>,
+    T: TypeFoldable<TyCtxt<'tcx>>,
     F: Fn() -> RegionCtxt,
 {
     infcx.tcx.fold_regions(value, |_region, _depth| {
@@ -89,7 +89,7 @@ struct NllVisitor<'a, 'tcx> {
 impl<'a, 'tcx> NllVisitor<'a, 'tcx> {
     fn renumber_regions<T, F>(&mut self, value: T, region_ctxt_fn: F) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
         F: Fn() -> RegionCtxt,
     {
         renumber_regions(self.infcx, value, region_ctxt_fn)

compiler/rustc_borrowck/src/type_check/canonical.rs

@@ -2,7 +2,7 @@ use std::fmt;
 
 use rustc_infer::infer::{canonical::Canonical, InferOk};
 use rustc_middle::mir::ConstraintCategory;
-use rustc_middle::ty::{self, ToPredicate, Ty, TypeFoldable};
+use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt, TypeFoldable};
 use rustc_span::def_id::DefId;
 use rustc_span::Span;
 use rustc_trait_selection::traits::query::type_op::{self, TypeOpOutput};
@@ -66,7 +66,7 @@ impl<'a, 'tcx> TypeChecker<'a, 'tcx> {
         canonical: &Canonical<'tcx, T>,
     ) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         let old_universe = self.infcx.universe();
 

compiler/rustc_borrowck/src/type_check/constraint_conversion.rs

@@ -6,8 +6,8 @@ use rustc_infer::infer::region_constraints::{GenericKind, VerifyBound};
 use rustc_infer::infer::{self, InferCtxt, SubregionOrigin};
 use rustc_middle::mir::{ClosureOutlivesSubject, ClosureRegionRequirements, ConstraintCategory};
 use rustc_middle::ty::subst::GenericArgKind;
-use rustc_middle::ty::TypeFoldable;
 use rustc_middle::ty::{self, TyCtxt};
+use rustc_middle::ty::{TypeFoldable, TypeVisitableExt};
 use rustc_span::{Span, DUMMY_SP};
 
 use crate::{
@@ -171,7 +171,7 @@ impl<'a, 'tcx> ConstraintConversion<'a, 'tcx> {
     ///
     /// FIXME: This should get removed once higher ranked region obligations
     /// are dealt with during trait solving.
-    fn replace_placeholders_with_nll<T: TypeFoldable<'tcx>>(&mut self, value: T) -> T {
+    fn replace_placeholders_with_nll<T: TypeFoldable<TyCtxt<'tcx>>>(&mut self, value: T) -> T {
         if value.has_placeholders() {
             self.tcx.fold_regions(value, |r, _| match *r {
                 ty::RePlaceholder(placeholder) => {

compiler/rustc_borrowck/src/type_check/liveness/trace.rs

@@ -3,7 +3,7 @@ use rustc_index::bit_set::HybridBitSet;
 use rustc_index::interval::IntervalSet;
 use rustc_infer::infer::canonical::QueryRegionConstraints;
 use rustc_middle::mir::{BasicBlock, Body, ConstraintCategory, Local, Location};
-use rustc_middle::ty::{Ty, TypeVisitable};
+use rustc_middle::ty::{Ty, TyCtxt, TypeVisitable, TypeVisitableExt};
 use rustc_trait_selection::traits::query::dropck_outlives::DropckOutlivesResult;
 use rustc_trait_selection::traits::query::type_op::outlives::DropckOutlives;
 use rustc_trait_selection::traits::query::type_op::{TypeOp, TypeOpOutput};
@@ -477,7 +477,7 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
     /// points `live_at`.
     fn add_use_live_facts_for(
         &mut self,
-        value: impl TypeVisitable<'tcx>,
+        value: impl TypeVisitable<TyCtxt<'tcx>>,
         live_at: &IntervalSet<PointIndex>,
     ) {
         debug!("add_use_live_facts_for(value={:?})", value);
@@ -542,7 +542,7 @@ impl<'tcx> LivenessContext<'_, '_, '_, 'tcx> {
     fn make_all_regions_live(
         elements: &RegionValueElements,
         typeck: &mut TypeChecker<'_, 'tcx>,
-        value: impl TypeVisitable<'tcx>,
+        value: impl TypeVisitable<TyCtxt<'tcx>>,
         live_at: &IntervalSet<PointIndex>,
     ) {
         debug!("make_all_regions_live(value={:?})", value);

compiler/rustc_borrowck/src/type_check/mod.rs

@@ -30,7 +30,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::adjustment::PointerCast;
 use rustc_middle::ty::cast::CastTy;
 use rustc_middle::ty::subst::{SubstsRef, UserSubsts};
-use rustc_middle::ty::visit::TypeVisitable;
+use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{
     self, Binder, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations, Dynamic,
     OpaqueHiddenType, OpaqueTypeKey, RegionVid, Ty, TyCtxt, UserType, UserTypeAnnotationIndex,

compiler/rustc_borrowck/src/universal_regions.rs

@@ -728,7 +728,7 @@ trait InferCtxtExt<'tcx> {
         value: T,
     ) -> T
     where
-        T: TypeFoldable<'tcx>;
+        T: TypeFoldable<TyCtxt<'tcx>>;
 
     fn replace_bound_regions_with_nll_infer_vars<T>(
         &self,
@@ -738,7 +738,7 @@ trait InferCtxtExt<'tcx> {
         indices: &mut UniversalRegionIndices<'tcx>,
     ) -> T
     where
-        T: TypeFoldable<'tcx>;
+        T: TypeFoldable<TyCtxt<'tcx>>;
 
     fn replace_late_bound_regions_with_nll_infer_vars_in_recursive_scope(
         &self,
@@ -761,7 +761,7 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
         value: T,
     ) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         self.infcx.tcx.fold_regions(value, |region, _depth| {
             let name = match region.get_name() {
@@ -785,7 +785,7 @@ impl<'cx, 'tcx> InferCtxtExt<'tcx> for BorrowckInferCtxt<'cx, 'tcx> {
         indices: &mut UniversalRegionIndices<'tcx>,
     ) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         let (value, _map) = self.tcx.replace_late_bound_regions(value, |br| {
             debug!(?br);
@@ -906,7 +906,7 @@ impl<'tcx> UniversalRegionIndices<'tcx> {
     /// returned by `to_region_vid`.
     pub fn fold_to_region_vids<T>(&self, tcx: TyCtxt<'tcx>, value: T) -> T
     where
-        T: TypeFoldable<'tcx>,
+        T: TypeFoldable<TyCtxt<'tcx>>,
     {
         tcx.fold_regions(value, |region, _| tcx.mk_re_var(self.to_region_vid(region)))
     }