Track bound types like bound regions

13 files changed, 52 insertions, 38 deletions

diff --git a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
index 3115f5f464a..21e70041810 100644
--- a/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
+++ b/compiler/rustc_hir_analysis/src/check/compare_impl_item.rs
@@ -1930,7 +1930,7 @@ pub(super) fn check_type_bounds<'tcx>(
         smallvec::SmallVec::with_capacity(defs.count());
     InternalSubsts::fill_single(&mut substs, defs, &mut |param, _| match param.kind {
         GenericParamDefKind::Type { .. } => {
-            let kind = ty::BoundTyKind::Param(param.name);
+            let kind = ty::BoundTyKind::Param(param.def_id, param.name);
             let bound_var = ty::BoundVariableKind::Ty(kind);
             bound_vars.push(bound_var);
             tcx.mk_ty(ty::Bound(
diff --git a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
index 817ae10c760..31be107b354 100644
--- a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
+++ b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
@@ -90,7 +90,7 @@ impl<'tcx> InferCtxt<'tcx> {
             types: &mut |bound_ty: ty::BoundTy| {
                 self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                     universe: next_universe,
-                    name: bound_ty.var,
+                    name: bound_ty.kind,
                 }))
             },
             consts: &mut |bound_var: ty::BoundVar, ty| {
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index f0e42c1fce4..f39170bb291 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -2044,7 +2044,7 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
 ) -> SubstsRef<'tcx> {
     struct ReplaceParamAndInferWithPlaceholder<'tcx> {
         tcx: TyCtxt<'tcx>,
-        idx: usize,
+        idx: u32,
     }
 
     impl<'tcx> TypeFolder<'tcx> for ReplaceParamAndInferWithPlaceholder<'tcx> {
@@ -2056,7 +2056,7 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
             if let ty::Infer(_) = t.kind() {
                 self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                     universe: ty::UniverseIndex::ROOT,
-                    name: ty::BoundVar::from_usize({
+                    name: ty::BoundTyKind::Anon({
                         let idx = self.idx;
                         self.idx += 1;
                         idx
@@ -2077,7 +2077,7 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
                 self.tcx.mk_const(
                     ty::PlaceholderConst {
                         universe: ty::UniverseIndex::ROOT,
-                        name: ty::BoundVar::from_usize({
+                        name: ty::BoundVar::from_u32({
                             let idx = self.idx;
                             self.idx += 1;
                             idx
diff --git a/compiler/rustc_middle/src/ty/fold.rs b/compiler/rustc_middle/src/ty/fold.rs
index 6b9a37d848d..1445bc1ed32 100644
--- a/compiler/rustc_middle/src/ty/fold.rs
+++ b/compiler/rustc_middle/src/ty/fold.rs
@@ -610,7 +610,9 @@ impl<'tcx> TyCtxt<'tcx> {
                 let index = entry.index();
                 let var = ty::BoundVar::from_usize(index);
                 let kind = entry
-                    .or_insert_with(|| ty::BoundVariableKind::Ty(ty::BoundTyKind::Anon))
+                    .or_insert_with(|| {
+                        ty::BoundVariableKind::Ty(ty::BoundTyKind::Anon(index as u32))
+                    })
                     .expect_ty();
                 self.tcx.mk_ty(ty::Bound(ty::INNERMOST, BoundTy { var, kind }))
             }
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 25c6777a14c..09c3d5b736c 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1369,7 +1369,7 @@ pub struct Placeholder<T> {
 
 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
 
-pub type PlaceholderType = Placeholder<BoundVar>;
+pub type PlaceholderType = Placeholder<BoundTyKind>;
 
 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index f2abec216b7..df4e8c1a52d 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -698,8 +698,10 @@ pub trait PrettyPrinter<'tcx>:
             ty::Error(_) => p!("[type error]"),
             ty::Param(ref param_ty) => p!(print(param_ty)),
             ty::Bound(debruijn, bound_ty) => match bound_ty.kind {
-                ty::BoundTyKind::Anon => self.pretty_print_bound_var(debruijn, bound_ty.var)?,
-                ty::BoundTyKind::Param(p) => p!(write("{}", p)),
+                ty::BoundTyKind::Anon(bv) => {
+                    self.pretty_print_bound_var(debruijn, ty::BoundVar::from_u32(bv))?
+                }
+                ty::BoundTyKind::Param(_, s) => p!(write("{}", s)),
             },
             ty::Adt(def, substs) => {
                 p!(print_def_path(def.did(), substs));
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 034aab0c38e..8df639750c7 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -240,6 +240,7 @@ TrivialTypeTraversalAndLiftImpls! {
     crate::ty::AssocKind,
     crate::ty::AliasKind,
     crate::ty::Placeholder<crate::ty::BoundRegionKind>,
+    crate::ty::Placeholder<crate::ty::BoundTyKind>,
     crate::ty::ClosureKind,
     crate::ty::FreeRegion,
     crate::ty::InferTy,
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index f97d2e753a3..060d864389c 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1504,13 +1504,22 @@ pub struct BoundTy {
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
 #[derive(HashStable)]
 pub enum BoundTyKind {
-    Anon,
-    Param(Symbol),
+    Anon(u32),
+    Param(DefId, Symbol),
+}
+
+impl BoundTyKind {
+    pub fn expect_anon(self) -> u32 {
+        match self {
+            BoundTyKind::Anon(i) => i,
+            _ => bug!(),
+        }
+    }
 }
 
 impl From<BoundVar> for BoundTy {
     fn from(var: BoundVar) -> Self {
-        BoundTy { var, kind: BoundTyKind::Anon }
+        BoundTy { var, kind: BoundTyKind::Anon(var.as_u32()) }
     }
 }
 
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index a11c5e81969..53cae3e720c 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -783,7 +783,7 @@ impl<'tcx> TypeFolder<'tcx> for BoundVarReplacer<'_, 'tcx> {
             }
             ty::Bound(debruijn, bound_ty) if debruijn >= self.current_index => {
                 let universe = self.universe_for(debruijn);
-                let p = ty::PlaceholderType { universe, name: bound_ty.var };
+                let p = ty::PlaceholderType { universe, name: bound_ty.kind };
                 self.mapped_types.insert(p, bound_ty);
                 self.infcx.tcx.mk_ty(ty::Placeholder(p))
             }
diff --git a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
index 89a8fdbac1c..0a4136dc1cf 100644
--- a/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
+++ b/compiler/rustc_trait_selection/src/traits/select/confirmation.rs
@@ -524,7 +524,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                             .kind
                         {
                             GenericParamDefKind::Type { .. } => {
-                                let kind = ty::BoundTyKind::Param(param.name);
+                                let kind = ty::BoundTyKind::Param(param.def_id, param.name);
                                 let bound_var = ty::BoundVariableKind::Ty(kind);
                                 bound_vars.push(bound_var);
                                 tcx.mk_ty(ty::Bound(
diff --git a/compiler/rustc_traits/src/chalk/db.rs b/compiler/rustc_traits/src/chalk/db.rs
index 84f7e836208..dbd5f13fe4e 100644
--- a/compiler/rustc_traits/src/chalk/db.rs
+++ b/compiler/rustc_traits/src/chalk/db.rs
@@ -725,7 +725,7 @@ fn bound_vars_for_item(tcx: TyCtxt<'_>, def_id: DefId) -> SubstsRef<'_> {
                 ty::INNERMOST,
                 ty::BoundTy {
                     var: ty::BoundVar::from(param.index),
-                    kind: ty::BoundTyKind::Param(param.name),
+                    kind: ty::BoundTyKind::Param(param.def_id, param.name),
                 },
             ))
             .into(),
diff --git a/compiler/rustc_traits/src/chalk/lowering.rs b/compiler/rustc_traits/src/chalk/lowering.rs
index 3a254105162..9c5db3314c5 100644
--- a/compiler/rustc_traits/src/chalk/lowering.rs
+++ b/compiler/rustc_traits/src/chalk/lowering.rs
@@ -370,7 +370,7 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Ty<RustInterner<'tcx>>> for Ty<'tcx> {
             ty::Placeholder(_placeholder) => {
                 chalk_ir::TyKind::Placeholder(chalk_ir::PlaceholderIndex {
                     ui: chalk_ir::UniverseIndex { counter: _placeholder.universe.as_usize() },
-                    idx: _placeholder.name.as_usize(),
+                    idx: _placeholder.name.expect_anon() as usize,
                 })
             }
             ty::Infer(_infer) => unimplemented!(),
@@ -452,10 +452,6 @@ impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
             ),
             TyKind::Foreign(def_id) => ty::Foreign(def_id.0),
             TyKind::Error => return interner.tcx.ty_error(),
-            TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
-                universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
-                name: ty::BoundVar::from_usize(placeholder.idx),
-            }),
             TyKind::Alias(alias_ty) => match alias_ty {
                 chalk_ir::AliasTy::Projection(projection) => ty::Alias(
                     ty::Projection,
@@ -473,13 +469,17 @@ impl<'tcx> LowerInto<'tcx, Ty<'tcx>> for &chalk_ir::Ty<RustInterner<'tcx>> {
                 ),
             },
             TyKind::Function(_quantified_ty) => unimplemented!(),
-            TyKind::BoundVar(_bound) => ty::Bound(
-                ty::DebruijnIndex::from_usize(_bound.debruijn.depth() as usize),
+            TyKind::BoundVar(bound) => ty::Bound(
+                ty::DebruijnIndex::from_usize(bound.debruijn.depth() as usize),
                 ty::BoundTy {
-                    var: ty::BoundVar::from_usize(_bound.index),
-                    kind: ty::BoundTyKind::Anon,
+                    var: ty::BoundVar::from_usize(bound.index),
+                    kind: ty::BoundTyKind::Anon(bound.index as u32),
                 },
             ),
+            TyKind::Placeholder(placeholder) => ty::Placeholder(ty::Placeholder {
+                universe: ty::UniverseIndex::from_usize(placeholder.ui.counter),
+                name: ty::BoundTyKind::Anon(placeholder.idx as u32),
+            }),
             TyKind::InferenceVar(_, _) => unimplemented!(),
             TyKind::Dyn(_) => unimplemented!(),
         };
@@ -504,7 +504,7 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Lifetime<RustInterner<'tcx>>> for Region<'t
             ty::RePlaceholder(placeholder_region) => {
                 chalk_ir::LifetimeData::Placeholder(chalk_ir::PlaceholderIndex {
                     ui: chalk_ir::UniverseIndex { counter: placeholder_region.universe.index() },
-                    idx: 0,
+                    idx: 0, // FIXME: This `idx: 0` is sus.
                 })
                 .intern(interner)
             }
@@ -674,7 +674,7 @@ impl<'tcx> LowerInto<'tcx, chalk_ir::Binders<chalk_ir::QuantifiedWhereClauses<Ru
         let self_ty = interner.tcx.mk_ty(ty::Bound(
             // This is going to be wrapped in a binder
             ty::DebruijnIndex::from_usize(1),
-            ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon },
+            ty::BoundTy { var: ty::BoundVar::from_usize(0), kind: ty::BoundTyKind::Anon(0) },
         ));
         let where_clauses = predicates.into_iter().map(|predicate| {
             let (predicate, binders, _named_regions) =
@@ -1038,7 +1038,7 @@ pub(crate) struct ParamsSubstitutor<'tcx> {
     binder_index: ty::DebruijnIndex,
     list: Vec<rustc_middle::ty::ParamTy>,
     next_ty_placeholder: usize,
-    pub(crate) params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+    pub(crate) params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
     pub(crate) named_regions: BTreeMap<DefId, u32>,
 }
 
@@ -1072,15 +1072,15 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
             ty::Param(param) => match self.list.iter().position(|r| r == &param) {
                 Some(idx) => self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                     universe: ty::UniverseIndex::from_usize(0),
-                    name: ty::BoundVar::from_usize(idx),
+                    name: ty::BoundTyKind::Anon(idx as u32),
                 })),
                 None => {
                     self.list.push(param);
                     let idx = self.list.len() - 1 + self.next_ty_placeholder;
-                    self.params.insert(idx, param);
+                    self.params.insert(idx as u32, param);
                     self.tcx.mk_ty(ty::Placeholder(ty::PlaceholderType {
                         universe: ty::UniverseIndex::from_usize(0),
-                        name: ty::BoundVar::from_usize(idx),
+                        name: ty::BoundTyKind::Anon(idx as u32),
                     }))
                 }
             },
@@ -1119,13 +1119,13 @@ impl<'tcx> TypeFolder<'tcx> for ParamsSubstitutor<'tcx> {
 
 pub(crate) struct ReverseParamsSubstitutor<'tcx> {
     tcx: TyCtxt<'tcx>,
-    params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+    params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
 }
 
 impl<'tcx> ReverseParamsSubstitutor<'tcx> {
     pub(crate) fn new(
         tcx: TyCtxt<'tcx>,
-        params: rustc_data_structures::fx::FxHashMap<usize, rustc_middle::ty::ParamTy>,
+        params: rustc_data_structures::fx::FxHashMap<u32, rustc_middle::ty::ParamTy>,
     ) -> Self {
         Self { tcx, params }
     }
@@ -1139,7 +1139,7 @@ impl<'tcx> TypeFolder<'tcx> for ReverseParamsSubstitutor<'tcx> {
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
         match *t.kind() {
             ty::Placeholder(ty::PlaceholderType { universe: ty::UniverseIndex::ROOT, name }) => {
-                match self.params.get(&name.as_usize()) {
+                match self.params.get(&name.expect_anon()) {
                     Some(param) => self.tcx.mk_ty(ty::Param(*param)),
                     None => t,
                 }
@@ -1171,7 +1171,8 @@ impl<'tcx> TypeVisitor<'tcx> for PlaceholdersCollector {
     fn visit_ty(&mut self, t: Ty<'tcx>) -> ControlFlow<Self::BreakTy> {
         match t.kind() {
             ty::Placeholder(p) if p.universe == self.universe_index => {
-                self.next_ty_placeholder = self.next_ty_placeholder.max(p.name.as_usize() + 1);
+                self.next_ty_placeholder =
+                    self.next_ty_placeholder.max(p.name.expect_anon() as usize + 1);
             }
 
             _ => (),
@@ -1186,6 +1187,7 @@ impl<'tcx> TypeVisitor<'tcx> for PlaceholdersCollector {
                 if let ty::BoundRegionKind::BrAnon(anon, _) = p.name {
                     self.next_anon_region_placeholder = self.next_anon_region_placeholder.max(anon);
                 }
+                // FIXME: This doesn't seem to handle BrNamed at all?
             }
 
             _ => (),
diff --git a/compiler/rustc_traits/src/chalk/mod.rs b/compiler/rustc_traits/src/chalk/mod.rs
index 13d83b92689..5855a8e28dd 100644
--- a/compiler/rustc_traits/src/chalk/mod.rs
+++ b/compiler/rustc_traits/src/chalk/mod.rs
@@ -6,12 +6,10 @@
 pub(crate) mod db;
 pub(crate) mod lowering;
 
-use rustc_data_structures::fx::FxHashMap;
-
 use rustc_middle::infer::canonical::{CanonicalTyVarKind, CanonicalVarKind};
 use rustc_middle::traits::ChalkRustInterner;
 use rustc_middle::ty::query::Providers;
-use rustc_middle::ty::{self, ParamTy, TyCtxt, TypeFoldable, TypeVisitable};
+use rustc_middle::ty::{self, TyCtxt, TypeFoldable, TypeVisitable};
 
 use rustc_infer::infer::canonical::{
     Canonical, CanonicalVarValues, Certainty, QueryRegionConstraints, QueryResponse,
@@ -41,7 +39,7 @@ pub(crate) fn evaluate_goal<'tcx>(
     let mut params_substitutor =
         ParamsSubstitutor::new(tcx, placeholders_collector.next_ty_placeholder);
     let obligation = obligation.fold_with(&mut params_substitutor);
-    let params: FxHashMap<usize, ParamTy> = params_substitutor.params;
+    let params = params_substitutor.params;
 
     let max_universe = obligation.max_universe.index();