diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index 41787ee29420a..280dcae34515f 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -152,7 +152,7 @@ impl<'tcx> InferCtxt<'tcx> {
                 )
                 .into(),
             CanonicalVarKind::Effect => {
-                let vid = self.inner.borrow_mut().effect_unification_table().new_key(None);
+                let vid = self.inner.borrow_mut().effect_unification_table().new_key(None).vid;
                 ty::Const::new_infer(self.tcx, ty::InferConst::EffectVar(vid), self.tcx.types.bool)
                     .into()
             }
diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index ee13eb0271e7e..2a9e20b9f8f1d 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -320,7 +320,7 @@ impl<'tcx> InferCtxt<'tcx> {
     #[instrument(level = "debug", skip(self))]
     fn unify_const_variable(
         &self,
-        target_vid: ty::ConstVid<'tcx>,
+        target_vid: ty::ConstVid,
         ct: ty::Const<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> RelateResult<'tcx, ty::Const<'tcx>> {
@@ -381,7 +381,7 @@ impl<'tcx> InferCtxt<'tcx> {
     fn unify_effect_variable(
         &self,
         vid_is_expected: bool,
-        vid: ty::EffectVid<'tcx>,
+        vid: ty::EffectVid,
         val: EffectVarValue<'tcx>,
     ) -> RelateResult<'tcx, ty::Const<'tcx>> {
         self.inner
diff --git a/compiler/rustc_infer/src/infer/freshen.rs b/compiler/rustc_infer/src/infer/freshen.rs
index 0596ce373cf5b..35204478c54dd 100644
--- a/compiler/rustc_infer/src/infer/freshen.rs
+++ b/compiler/rustc_infer/src/infer/freshen.rs
@@ -42,7 +42,7 @@ pub struct TypeFreshener<'a, 'tcx> {
     ty_freshen_count: u32,
     const_freshen_count: u32,
     ty_freshen_map: FxHashMap<ty::InferTy, Ty<'tcx>>,
-    const_freshen_map: FxHashMap<ty::InferConst<'tcx>, ty::Const<'tcx>>,
+    const_freshen_map: FxHashMap<ty::InferConst, ty::Const<'tcx>>,
 }
 
 impl<'a, 'tcx> TypeFreshener<'a, 'tcx> {
@@ -79,12 +79,12 @@ impl<'a, 'tcx> TypeFreshener<'a, 'tcx> {
     fn freshen_const<F>(
         &mut self,
         opt_ct: Option<ty::Const<'tcx>>,
-        key: ty::InferConst<'tcx>,
+        key: ty::InferConst,
         freshener: F,
         ty: Ty<'tcx>,
     ) -> ty::Const<'tcx>
     where
-        F: FnOnce(u32) -> ty::InferConst<'tcx>,
+        F: FnOnce(u32) -> ty::InferConst,
     {
         if let Some(ct) = opt_ct {
             return ct.fold_with(self);
diff --git a/compiler/rustc_infer/src/infer/fudge.rs b/compiler/rustc_infer/src/infer/fudge.rs
index 2f371c4fe31c1..7e878ac06c7f2 100644
--- a/compiler/rustc_infer/src/infer/fudge.rs
+++ b/compiler/rustc_infer/src/infer/fudge.rs
@@ -1,3 +1,4 @@
+use rustc_middle::infer::unify_key::ConstVidKey;
 use rustc_middle::ty::fold::{TypeFoldable, TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::{self, ConstVid, FloatVid, IntVid, RegionVid, Ty, TyCtxt, TyVid};
 
@@ -23,14 +24,14 @@ where
 }
 
 fn const_vars_since_snapshot<'tcx>(
-    table: &mut UnificationTable<'_, 'tcx, ConstVid<'tcx>>,
+    table: &mut UnificationTable<'_, 'tcx, ConstVidKey<'tcx>>,
     snapshot_var_len: usize,
-) -> (Range<ConstVid<'tcx>>, Vec<ConstVariableOrigin>) {
+) -> (Range<ConstVid>, Vec<ConstVariableOrigin>) {
     let range = vars_since_snapshot(table, snapshot_var_len);
     (
-        range.start..range.end,
-        (range.start.index..range.end.index)
-            .map(|index| table.probe_value(ConstVid::from_index(index)).origin)
+        range.start.vid..range.end.vid,
+        (range.start.index()..range.end.index())
+            .map(|index| table.probe_value(ConstVid::from_u32(index)).origin)
             .collect(),
     )
 }
@@ -172,7 +173,7 @@ pub struct InferenceFudger<'a, 'tcx> {
     int_vars: Range<IntVid>,
     float_vars: Range<FloatVid>,
     region_vars: (Range<RegionVid>, Vec<RegionVariableOrigin>),
-    const_vars: (Range<ConstVid<'tcx>>, Vec<ConstVariableOrigin>),
+    const_vars: (Range<ConstVid>, Vec<ConstVariableOrigin>),
 }
 
 impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for InferenceFudger<'a, 'tcx> {
@@ -235,7 +236,7 @@ impl<'a, 'tcx> TypeFolder<TyCtxt<'tcx>> for InferenceFudger<'a, 'tcx> {
             if self.const_vars.0.contains(&vid) {
                 // This variable was created during the fudging.
                 // Recreate it with a fresh variable here.
-                let idx = (vid.index - self.const_vars.0.start.index) as usize;
+                let idx = (vid.index() - self.const_vars.0.start.index()) as usize;
                 let origin = self.const_vars.1[idx];
                 self.infcx.next_const_var(ct.ty(), origin)
             } else {
diff --git a/compiler/rustc_infer/src/infer/generalize.rs b/compiler/rustc_infer/src/infer/generalize.rs
index c1e65ffe0a652..17fe3aa7b44c1 100644
--- a/compiler/rustc_infer/src/infer/generalize.rs
+++ b/compiler/rustc_infer/src/infer/generalize.rs
@@ -17,7 +17,7 @@ pub(super) fn generalize<'tcx, D: GeneralizerDelegate<'tcx>, T: Into<Term<'tcx>>
     infcx: &InferCtxt<'tcx>,
     delegate: &mut D,
     term: T,
-    for_vid: impl Into<ty::TermVid<'tcx>>,
+    for_vid: impl Into<ty::TermVid>,
     ambient_variance: ty::Variance,
 ) -> RelateResult<'tcx, Generalization<T>> {
     let (for_universe, root_vid) = match for_vid.into() {
@@ -27,7 +27,7 @@ pub(super) fn generalize<'tcx, D: GeneralizerDelegate<'tcx>, T: Into<Term<'tcx>>
         ),
         ty::TermVid::Const(ct_vid) => (
             infcx.probe_const_var(ct_vid).unwrap_err(),
-            ty::TermVid::Const(infcx.inner.borrow_mut().const_unification_table().find(ct_vid)),
+            ty::TermVid::Const(infcx.inner.borrow_mut().const_unification_table().find(ct_vid).vid),
         ),
     };
 
@@ -127,7 +127,7 @@ struct Generalizer<'me, 'tcx, D> {
     /// The vid of the type variable that is in the process of being
     /// instantiated. If we find this within the value we are folding,
     /// that means we would have created a cyclic value.
-    root_vid: ty::TermVid<'tcx>,
+    root_vid: ty::TermVid,
 
     /// The universe of the type variable that is in the process of being
     /// instantiated. If we find anything that this universe cannot name,
@@ -376,7 +376,7 @@ where
                 // `vid` are related and we'd be inferring an infinitely
                 // deep const.
                 if ty::TermVid::Const(
-                    self.infcx.inner.borrow_mut().const_unification_table().find(vid),
+                    self.infcx.inner.borrow_mut().const_unification_table().find(vid).vid,
                 ) == self.root_vid
                 {
                     return Err(self.cyclic_term_error());
@@ -394,10 +394,14 @@ where
                         if self.for_universe.can_name(universe) {
                             Ok(c)
                         } else {
-                            let new_var_id = variable_table.new_key(ConstVarValue {
-                                origin: var_value.origin,
-                                val: ConstVariableValue::Unknown { universe: self.for_universe },
-                            });
+                            let new_var_id = variable_table
+                                .new_key(ConstVarValue {
+                                    origin: var_value.origin,
+                                    val: ConstVariableValue::Unknown {
+                                        universe: self.for_universe,
+                                    },
+                                })
+                                .vid;
                             Ok(ty::Const::new_var(self.tcx(), new_var_id, c.ty()))
                         }
                     }
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index 2198a15d99d4c..4ee897ffe9843 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -6,7 +6,9 @@ pub use self::RegionVariableOrigin::*;
 pub use self::SubregionOrigin::*;
 pub use self::ValuePairs::*;
 pub use combine::ObligationEmittingRelation;
+use rustc_data_structures::captures::Captures;
 use rustc_data_structures::undo_log::UndoLogs;
+use rustc_middle::infer::unify_key::{ConstVidKey, EffectVidKey};
 
 use self::opaque_types::OpaqueTypeStorage;
 pub(crate) use self::undo_log::{InferCtxtUndoLogs, Snapshot, UndoLog};
@@ -40,7 +42,6 @@ use rustc_span::{Span, DUMMY_SP};
 
 use std::cell::{Cell, RefCell};
 use std::fmt;
-use std::marker::PhantomData;
 
 use self::combine::CombineFields;
 use self::error_reporting::TypeErrCtxt;
@@ -85,7 +86,7 @@ pub struct InferOk<'tcx, T> {
 pub type InferResult<'tcx, T> = Result<InferOk<'tcx, T>, TypeError<'tcx>>;
 
 pub type UnitResult<'tcx> = RelateResult<'tcx, ()>; // "unify result"
-pub type FixupResult<'tcx, T> = Result<T, FixupError<'tcx>>; // "fixup result"
+pub type FixupResult<T> = Result<T, FixupError>; // "fixup result"
 
 pub(crate) type UnificationTable<'a, 'tcx, T> = ut::UnificationTable<
     ut::InPlace<T, &'a mut ut::UnificationStorage<T>, &'a mut InferCtxtUndoLogs<'tcx>>,
@@ -108,7 +109,7 @@ pub struct InferCtxtInner<'tcx> {
     type_variable_storage: type_variable::TypeVariableStorage<'tcx>,
 
     /// Map from const parameter variable to the kind of const it represents.
-    const_unification_storage: ut::UnificationTableStorage<ty::ConstVid<'tcx>>,
+    const_unification_storage: ut::UnificationTableStorage<ConstVidKey<'tcx>>,
 
     /// Map from integral variable to the kind of integer it represents.
     int_unification_storage: ut::UnificationTableStorage<ty::IntVid>,
@@ -117,7 +118,7 @@ pub struct InferCtxtInner<'tcx> {
     float_unification_storage: ut::UnificationTableStorage<ty::FloatVid>,
 
     /// Map from effect variable to the effect param it represents.
-    effect_unification_storage: ut::UnificationTableStorage<ty::EffectVid<'tcx>>,
+    effect_unification_storage: ut::UnificationTableStorage<EffectVidKey<'tcx>>,
 
     /// Tracks the set of region variables and the constraints between them.
     ///
@@ -224,11 +225,11 @@ impl<'tcx> InferCtxtInner<'tcx> {
     }
 
     #[inline]
-    fn const_unification_table(&mut self) -> UnificationTable<'_, 'tcx, ty::ConstVid<'tcx>> {
+    fn const_unification_table(&mut self) -> UnificationTable<'_, 'tcx, ConstVidKey<'tcx>> {
         self.const_unification_storage.with_log(&mut self.undo_log)
     }
 
-    fn effect_unification_table(&mut self) -> UnificationTable<'_, 'tcx, ty::EffectVid<'tcx>> {
+    fn effect_unification_table(&mut self) -> UnificationTable<'_, 'tcx, EffectVidKey<'tcx>> {
         self.effect_unification_storage.with_log(&mut self.undo_log)
     }
 
@@ -359,7 +360,7 @@ impl<'tcx> ty::InferCtxtLike for InferCtxt<'tcx> {
         }
     }
 
-    fn universe_of_ct(&self, ct: ty::InferConst<'tcx>) -> Option<ty::UniverseIndex> {
+    fn universe_of_ct(&self, ct: ty::InferConst) -> Option<ty::UniverseIndex> {
         use ty::InferConst::*;
         match ct {
             // Same issue as with `universe_of_ty`
@@ -548,11 +549,11 @@ pub enum NllRegionVariableOrigin {
 
 // FIXME(eddyb) investigate overlap between this and `TyOrConstInferVar`.
 #[derive(Copy, Clone, Debug)]
-pub enum FixupError<'tcx> {
+pub enum FixupError {
     UnresolvedIntTy(IntVid),
     UnresolvedFloatTy(FloatVid),
     UnresolvedTy(TyVid),
-    UnresolvedConst(ConstVid<'tcx>),
+    UnresolvedConst(ConstVid),
 }
 
 /// See the `region_obligations` field for more information.
@@ -563,7 +564,7 @@ pub struct RegionObligation<'tcx> {
     pub origin: SubregionOrigin<'tcx>,
 }
 
-impl<'tcx> fmt::Display for FixupError<'tcx> {
+impl fmt::Display for FixupError {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         use self::FixupError::*;
 
@@ -794,7 +795,7 @@ impl<'tcx> InferCtxt<'tcx> {
         let mut table = inner.effect_unification_table();
 
         (0..table.len())
-            .map(|i| ty::EffectVid { index: i as u32, phantom: PhantomData })
+            .map(|i| ty::EffectVid::from_usize(i))
             .filter(|&vid| table.probe_value(vid).is_none())
             .map(|v| {
                 ty::Const::new_infer(self.tcx, ty::InferConst::EffectVar(v), self.tcx.types.bool)
@@ -1072,15 +1073,20 @@ impl<'tcx> InferCtxt<'tcx> {
             .inner
             .borrow_mut()
             .const_unification_table()
-            .new_key(ConstVarValue { origin, val: ConstVariableValue::Unknown { universe } });
+            .new_key(ConstVarValue { origin, val: ConstVariableValue::Unknown { universe } })
+            .vid;
         ty::Const::new_var(self.tcx, vid, ty)
     }
 
-    pub fn next_const_var_id(&self, origin: ConstVariableOrigin) -> ConstVid<'tcx> {
-        self.inner.borrow_mut().const_unification_table().new_key(ConstVarValue {
-            origin,
-            val: ConstVariableValue::Unknown { universe: self.universe() },
-        })
+    pub fn next_const_var_id(&self, origin: ConstVariableOrigin) -> ConstVid {
+        self.inner
+            .borrow_mut()
+            .const_unification_table()
+            .new_key(ConstVarValue {
+                origin,
+                val: ConstVariableValue::Unknown { universe: self.universe() },
+            })
+            .vid
     }
 
     fn next_int_var_id(&self) -> IntVid {
@@ -1194,11 +1200,15 @@ impl<'tcx> InferCtxt<'tcx> {
                     ),
                     span,
                 };
-                let const_var_id =
-                    self.inner.borrow_mut().const_unification_table().new_key(ConstVarValue {
+                let const_var_id = self
+                    .inner
+                    .borrow_mut()
+                    .const_unification_table()
+                    .new_key(ConstVarValue {
                         origin,
                         val: ConstVariableValue::Unknown { universe: self.universe() },
-                    });
+                    })
+                    .vid;
                 ty::Const::new_var(
                     self.tcx,
                     const_var_id,
@@ -1213,7 +1223,7 @@ impl<'tcx> InferCtxt<'tcx> {
     }
 
     pub fn var_for_effect(&self, param: &ty::GenericParamDef) -> GenericArg<'tcx> {
-        let effect_vid = self.inner.borrow_mut().effect_unification_table().new_key(None);
+        let effect_vid = self.inner.borrow_mut().effect_unification_table().new_key(None).vid;
         let ty = self
             .tcx
             .type_of(param.def_id)
@@ -1333,12 +1343,12 @@ impl<'tcx> InferCtxt<'tcx> {
         self.inner.borrow_mut().type_variables().root_var(var)
     }
 
-    pub fn root_const_var(&self, var: ty::ConstVid<'tcx>) -> ty::ConstVid<'tcx> {
-        self.inner.borrow_mut().const_unification_table().find(var)
+    pub fn root_const_var(&self, var: ty::ConstVid) -> ty::ConstVid {
+        self.inner.borrow_mut().const_unification_table().find(var).vid
     }
 
-    pub fn root_effect_var(&self, var: ty::EffectVid<'tcx>) -> ty::EffectVid<'tcx> {
-        self.inner.borrow_mut().effect_unification_table().find(var)
+    pub fn root_effect_var(&self, var: ty::EffectVid) -> ty::EffectVid {
+        self.inner.borrow_mut().effect_unification_table().find(var).vid
     }
 
     /// Resolves an int var to a rigid int type, if it was constrained to one,
@@ -1402,17 +1412,14 @@ impl<'tcx> InferCtxt<'tcx> {
         value.visit_with(&mut resolve::UnresolvedTypeOrConstFinder::new(self)).break_value()
     }
 
-    pub fn probe_const_var(
-        &self,
-        vid: ty::ConstVid<'tcx>,
-    ) -> Result<ty::Const<'tcx>, ty::UniverseIndex> {
+    pub fn probe_const_var(&self, vid: ty::ConstVid) -> Result<ty::Const<'tcx>, ty::UniverseIndex> {
         match self.inner.borrow_mut().const_unification_table().probe_value(vid).val {
             ConstVariableValue::Known { value } => Ok(value),
             ConstVariableValue::Unknown { universe } => Err(universe),
         }
     }
 
-    pub fn probe_effect_var(&self, vid: EffectVid<'tcx>) -> Option<EffectVarValue<'tcx>> {
+    pub fn probe_effect_var(&self, vid: EffectVid) -> Option<EffectVarValue<'tcx>> {
         self.inner.borrow_mut().effect_unification_table().probe_value(vid)
     }
 
@@ -1423,7 +1430,7 @@ impl<'tcx> InferCtxt<'tcx> {
     ///
     /// This method is idempotent, but it not typically not invoked
     /// except during the writeback phase.
-    pub fn fully_resolve<T: TypeFoldable<TyCtxt<'tcx>>>(&self, value: T) -> FixupResult<'tcx, T> {
+    pub fn fully_resolve<T: TypeFoldable<TyCtxt<'tcx>>>(&self, value: T) -> FixupResult<T> {
         match resolve::fully_resolve(self, value) {
             Ok(value) => {
                 if value.has_non_region_infer() {
@@ -1647,11 +1654,11 @@ impl<'tcx> InferCtxt<'tcx> {
     #[inline]
     pub fn is_ty_infer_var_definitely_unchanged<'a>(
         &'a self,
-    ) -> (impl Fn(TyOrConstInferVar<'tcx>) -> bool + 'a) {
+    ) -> (impl Fn(TyOrConstInferVar) -> bool + Captures<'tcx> + 'a) {
         // This hoists the borrow/release out of the loop body.
         let inner = self.inner.try_borrow();
 
-        return move |infer_var: TyOrConstInferVar<'tcx>| match (infer_var, &inner) {
+        return move |infer_var: TyOrConstInferVar| match (infer_var, &inner) {
             (TyOrConstInferVar::Ty(ty_var), Ok(inner)) => {
                 use self::type_variable::TypeVariableValue;
 
@@ -1674,7 +1681,7 @@ impl<'tcx> InferCtxt<'tcx> {
     /// inference variables), and it handles both `Ty` and `ty::Const` without
     /// having to resort to storing full `GenericArg`s in `stalled_on`.
     #[inline(always)]
-    pub fn ty_or_const_infer_var_changed(&self, infer_var: TyOrConstInferVar<'tcx>) -> bool {
+    pub fn ty_or_const_infer_var_changed(&self, infer_var: TyOrConstInferVar) -> bool {
         match infer_var {
             TyOrConstInferVar::Ty(v) => {
                 use self::type_variable::TypeVariableValue;
@@ -1781,7 +1788,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
 /// Helper for [InferCtxt::ty_or_const_infer_var_changed] (see comment on that), currently
 /// used only for `traits::fulfill`'s list of `stalled_on` inference variables.
 #[derive(Copy, Clone, Debug)]
-pub enum TyOrConstInferVar<'tcx> {
+pub enum TyOrConstInferVar {
     /// Equivalent to `ty::Infer(ty::TyVar(_))`.
     Ty(TyVid),
     /// Equivalent to `ty::Infer(ty::IntVar(_))`.
@@ -1790,12 +1797,12 @@ pub enum TyOrConstInferVar<'tcx> {
     TyFloat(FloatVid),
 
     /// Equivalent to `ty::ConstKind::Infer(ty::InferConst::Var(_))`.
-    Const(ConstVid<'tcx>),
+    Const(ConstVid),
     /// Equivalent to `ty::ConstKind::Infer(ty::InferConst::EffectVar(_))`.
-    Effect(EffectVid<'tcx>),
+    Effect(EffectVid),
 }
 
-impl<'tcx> TyOrConstInferVar<'tcx> {
+impl<'tcx> TyOrConstInferVar {
     /// Tries to extract an inference variable from a type or a constant, returns `None`
     /// for types other than `ty::Infer(_)` (or `InferTy::Fresh*`) and
     /// for constants other than `ty::ConstKind::Infer(_)` (or `InferConst::Fresh`).
diff --git a/compiler/rustc_infer/src/infer/resolve.rs b/compiler/rustc_infer/src/infer/resolve.rs
index 3c41e8b37838a..18a9cb6b44b78 100644
--- a/compiler/rustc_infer/src/infer/resolve.rs
+++ b/compiler/rustc_infer/src/infer/resolve.rs
@@ -192,7 +192,7 @@ impl<'a, 'tcx> TypeVisitor<TyCtxt<'tcx>> for UnresolvedTypeOrConstFinder<'a, 'tc
 /// Full type resolution replaces all type and region variables with
 /// their concrete results. If any variable cannot be replaced (never unified, etc)
 /// then an `Err` result is returned.
-pub fn fully_resolve<'tcx, T>(infcx: &InferCtxt<'tcx>, value: T) -> FixupResult<'tcx, T>
+pub fn fully_resolve<'tcx, T>(infcx: &InferCtxt<'tcx>, value: T) -> FixupResult<T>
 where
     T: TypeFoldable<TyCtxt<'tcx>>,
 {
@@ -206,7 +206,7 @@ struct FullTypeResolver<'a, 'tcx> {
 }
 
 impl<'a, 'tcx> FallibleTypeFolder<TyCtxt<'tcx>> for FullTypeResolver<'a, 'tcx> {
-    type Error = FixupError<'tcx>;
+    type Error = FixupError;
 
     fn interner(&self) -> TyCtxt<'tcx> {
         self.infcx.tcx
diff --git a/compiler/rustc_infer/src/infer/undo_log.rs b/compiler/rustc_infer/src/infer/undo_log.rs
index 79144b3e643b0..5655730518e5d 100644
--- a/compiler/rustc_infer/src/infer/undo_log.rs
+++ b/compiler/rustc_infer/src/infer/undo_log.rs
@@ -3,7 +3,7 @@ use std::marker::PhantomData;
 use rustc_data_structures::snapshot_vec as sv;
 use rustc_data_structures::undo_log::{Rollback, UndoLogs};
 use rustc_data_structures::unify as ut;
-use rustc_middle::infer::unify_key::RegionVidKey;
+use rustc_middle::infer::unify_key::{ConstVidKey, EffectVidKey, RegionVidKey};
 use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey};
 
 use crate::{
@@ -21,10 +21,10 @@ pub struct Snapshot<'tcx> {
 pub(crate) enum UndoLog<'tcx> {
     OpaqueTypes(OpaqueTypeKey<'tcx>, Option<OpaqueHiddenType<'tcx>>),
     TypeVariables(type_variable::UndoLog<'tcx>),
-    ConstUnificationTable(sv::UndoLog<ut::Delegate<ty::ConstVid<'tcx>>>),
+    ConstUnificationTable(sv::UndoLog<ut::Delegate<ConstVidKey<'tcx>>>),
     IntUnificationTable(sv::UndoLog<ut::Delegate<ty::IntVid>>),
     FloatUnificationTable(sv::UndoLog<ut::Delegate<ty::FloatVid>>),
-    EffectUnificationTable(sv::UndoLog<ut::Delegate<ty::EffectVid<'tcx>>>),
+    EffectUnificationTable(sv::UndoLog<ut::Delegate<EffectVidKey<'tcx>>>),
     RegionConstraintCollector(region_constraints::UndoLog<'tcx>),
     RegionUnificationTable(sv::UndoLog<ut::Delegate<RegionVidKey<'tcx>>>),
     ProjectionCache(traits::UndoLog<'tcx>),
@@ -56,9 +56,9 @@ impl_from! {
     IntUnificationTable(sv::UndoLog<ut::Delegate<ty::IntVid>>),
 
     FloatUnificationTable(sv::UndoLog<ut::Delegate<ty::FloatVid>>),
-    EffectUnificationTable(sv::UndoLog<ut::Delegate<ty::EffectVid<'tcx>>>),
+    EffectUnificationTable(sv::UndoLog<ut::Delegate<EffectVidKey<'tcx>>>),
 
-    ConstUnificationTable(sv::UndoLog<ut::Delegate<ty::ConstVid<'tcx>>>),
+    ConstUnificationTable(sv::UndoLog<ut::Delegate<ConstVidKey<'tcx>>>),
 
     RegionUnificationTable(sv::UndoLog<ut::Delegate<RegionVidKey<'tcx>>>),
     ProjectionCache(traits::UndoLog<'tcx>),
diff --git a/compiler/rustc_middle/src/infer/unify_key.rs b/compiler/rustc_middle/src/infer/unify_key.rs
index 7ca9647590a22..041a63776d113 100644
--- a/compiler/rustc_middle/src/infer/unify_key.rs
+++ b/compiler/rustc_middle/src/infer/unify_key.rs
@@ -141,18 +141,30 @@ pub struct ConstVarValue<'tcx> {
     pub val: ConstVariableValue<'tcx>,
 }
 
-impl<'tcx> UnifyKey for ty::ConstVid<'tcx> {
+#[derive(PartialEq, Copy, Clone, Debug)]
+pub struct ConstVidKey<'tcx> {
+    pub vid: ty::ConstVid,
+    pub phantom: PhantomData<ty::Const<'tcx>>,
+}
+
+impl<'tcx> From<ty::ConstVid> for ConstVidKey<'tcx> {
+    fn from(vid: ty::ConstVid) -> Self {
+        ConstVidKey { vid, phantom: PhantomData }
+    }
+}
+
+impl<'tcx> UnifyKey for ConstVidKey<'tcx> {
     type Value = ConstVarValue<'tcx>;
     #[inline]
     fn index(&self) -> u32 {
-        self.index
+        self.vid.as_u32()
     }
     #[inline]
     fn from_index(i: u32) -> Self {
-        ty::ConstVid { index: i, phantom: PhantomData }
+        ConstVidKey::from(ty::ConstVid::from_u32(i))
     }
     fn tag() -> &'static str {
-        "ConstVid"
+        "ConstVidKey"
     }
 }
 
@@ -224,17 +236,29 @@ impl<'tcx> UnifyValue for EffectVarValue<'tcx> {
     }
 }
 
-impl<'tcx> UnifyKey for ty::EffectVid<'tcx> {
+#[derive(PartialEq, Copy, Clone, Debug)]
+pub struct EffectVidKey<'tcx> {
+    pub vid: ty::EffectVid,
+    pub phantom: PhantomData<EffectVarValue<'tcx>>,
+}
+
+impl<'tcx> From<ty::EffectVid> for EffectVidKey<'tcx> {
+    fn from(vid: ty::EffectVid) -> Self {
+        EffectVidKey { vid, phantom: PhantomData }
+    }
+}
+
+impl<'tcx> UnifyKey for EffectVidKey<'tcx> {
     type Value = Option<EffectVarValue<'tcx>>;
     #[inline]
     fn index(&self) -> u32 {
-        self.index
+        self.vid.as_u32()
     }
     #[inline]
     fn from_index(i: u32) -> Self {
-        ty::EffectVid { index: i, phantom: PhantomData }
+        EffectVidKey::from(ty::EffectVid::from_u32(i))
     }
     fn tag() -> &'static str {
-        "EffectVid"
+        "EffectVidKey"
     }
 }
diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index 2518f0cf2e9ce..cfacccd26799e 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -57,7 +57,7 @@ impl<'tcx> Const<'tcx> {
     }
 
     #[inline]
-    pub fn new_var(tcx: TyCtxt<'tcx>, infer: ty::ConstVid<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
+    pub fn new_var(tcx: TyCtxt<'tcx>, infer: ty::ConstVid, ty: Ty<'tcx>) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Infer(ty::InferConst::Var(infer)), ty)
     }
 
@@ -67,7 +67,7 @@ impl<'tcx> Const<'tcx> {
     }
 
     #[inline]
-    pub fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
+    pub fn new_infer(tcx: TyCtxt<'tcx>, infer: ty::InferConst, ty: Ty<'tcx>) -> Const<'tcx> {
         Const::new(tcx, ty::ConstKind::Infer(infer), ty)
     }
 
diff --git a/compiler/rustc_middle/src/ty/consts/kind.rs b/compiler/rustc_middle/src/ty/consts/kind.rs
index 749b54ca0befb..4af841fcf9a5f 100644
--- a/compiler/rustc_middle/src/ty/consts/kind.rs
+++ b/compiler/rustc_middle/src/ty/consts/kind.rs
@@ -80,19 +80,19 @@ static_assert_size!(super::ConstKind<'_>, 32);
 
 /// An inference variable for a const, for use in const generics.
 #[derive(Copy, Clone, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable, Hash)]
-pub enum InferConst<'tcx> {
+pub enum InferConst {
     /// Infer the value of the const.
-    Var(ty::ConstVid<'tcx>),
+    Var(ty::ConstVid),
     /// Infer the value of the effect.
     ///
     /// For why this is separate from the `Var` variant above, see the
     /// documentation on `EffectVid`.
-    EffectVar(ty::EffectVid<'tcx>),
+    EffectVar(ty::EffectVid),
     /// A fresh const variable. See `infer::freshen` for more details.
     Fresh(u32),
 }
 
-impl<CTX> HashStable<CTX> for InferConst<'_> {
+impl<CTX> HashStable<CTX> for InferConst {
     fn hash_stable(&self, hcx: &mut CTX, hasher: &mut StableHasher) {
         match self {
             InferConst::Var(_) | InferConst::EffectVar(_) => {
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 561699d317088..3c8bac2a9d3db 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -100,7 +100,7 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     type PolyFnSig = PolyFnSig<'tcx>;
     type AllocId = crate::mir::interpret::AllocId;
     type Const = ty::Const<'tcx>;
-    type InferConst = ty::InferConst<'tcx>;
+    type InferConst = ty::InferConst;
     type AliasConst = ty::UnevaluatedConst<'tcx>;
     type PlaceholderConst = ty::PlaceholderConst<'tcx>;
     type ParamConst = ty::ParamConst;
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index 91211a048a00e..769b374c793a5 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1084,19 +1084,19 @@ impl ParamTerm {
 }
 
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
-pub enum TermVid<'tcx> {
+pub enum TermVid {
     Ty(ty::TyVid),
-    Const(ty::ConstVid<'tcx>),
+    Const(ty::ConstVid),
 }
 
-impl From<ty::TyVid> for TermVid<'_> {
+impl From<ty::TyVid> for TermVid {
     fn from(value: ty::TyVid) -> Self {
         TermVid::Ty(value)
     }
 }
 
-impl<'tcx> From<ty::ConstVid<'tcx>> for TermVid<'tcx> {
-    fn from(value: ty::ConstVid<'tcx>) -> Self {
+impl From<ty::ConstVid> for TermVid {
+    fn from(value: ty::ConstVid) -> Self {
         TermVid::Const(value)
     }
 }
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index 316370977a426..22648d853f4e6 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1194,7 +1194,7 @@ pub trait PrettyPrinter<'tcx>: Printer<'tcx> + fmt::Write {
         None
     }
 
-    fn const_infer_name(&self, _: ty::ConstVid<'tcx>) -> Option<Symbol> {
+    fn const_infer_name(&self, _: ty::ConstVid) -> Option<Symbol> {
         None
     }
 
@@ -1742,7 +1742,7 @@ pub struct FmtPrinterData<'a, 'tcx> {
     pub region_highlight_mode: RegionHighlightMode<'tcx>,
 
     pub ty_infer_name_resolver: Option<Box<dyn Fn(ty::TyVid) -> Option<Symbol> + 'a>>,
-    pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid<'tcx>) -> Option<Symbol> + 'a>>,
+    pub const_infer_name_resolver: Option<Box<dyn Fn(ty::ConstVid) -> Option<Symbol> + 'a>>,
 }
 
 impl<'a, 'tcx> Deref for FmtPrinter<'a, 'tcx> {
@@ -2082,7 +2082,7 @@ impl<'tcx> PrettyPrinter<'tcx> for FmtPrinter<'_, 'tcx> {
         self.printed_type_count = 0;
     }
 
-    fn const_infer_name(&self, id: ty::ConstVid<'tcx>) -> Option<Symbol> {
+    fn const_infer_name(&self, id: ty::ConstVid) -> Option<Symbol> {
         self.0.const_infer_name_resolver.as_ref().and_then(|func| func(id))
     }
 
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 92fac6fdab40f..967f62cdbca56 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -128,18 +128,6 @@ impl<'tcx> DebugWithInfcx<TyCtxt<'tcx>> for ty::FnSig<'tcx> {
     }
 }
 
-impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "?{}c", self.index)
-    }
-}
-
-impl fmt::Debug for ty::EffectVid<'_> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "?{}e", self.index)
-    }
-}
-
 impl<'tcx> fmt::Debug for ty::TraitRef<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
@@ -251,7 +239,7 @@ impl<'tcx> DebugWithInfcx<TyCtxt<'tcx>> for AliasTy<'tcx> {
     }
 }
 
-impl<'tcx> fmt::Debug for ty::InferConst<'tcx> {
+impl fmt::Debug for ty::InferConst {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
             InferConst::Var(var) => write!(f, "{var:?}"),
@@ -260,7 +248,7 @@ impl<'tcx> fmt::Debug for ty::InferConst<'tcx> {
         }
     }
 }
-impl<'tcx> DebugWithInfcx<TyCtxt<'tcx>> for ty::InferConst<'tcx> {
+impl<'tcx> DebugWithInfcx<TyCtxt<'tcx>> for ty::InferConst {
     fn fmt<Infcx: InferCtxtLike<Interner = TyCtxt<'tcx>>>(
         this: WithInfcx<'_, Infcx, &Self>,
         f: &mut core::fmt::Formatter<'_>,
@@ -269,8 +257,8 @@ impl<'tcx> DebugWithInfcx<TyCtxt<'tcx>> for ty::InferConst<'tcx> {
         match this.infcx.universe_of_ct(*this.data) {
             None => write!(f, "{:?}", this.data),
             Some(universe) => match *this.data {
-                Var(vid) => write!(f, "?{}_{}c", vid.index, universe.index()),
-                EffectVar(vid) => write!(f, "?{}_{}e", vid.index, universe.index()),
+                Var(vid) => write!(f, "?{}_{}c", vid.index(), universe.index()),
+                EffectVar(vid) => write!(f, "?{}_{}e", vid.index(), universe.index()),
                 Fresh(_) => {
                     unreachable!()
                 }
@@ -862,7 +850,7 @@ impl<'tcx> TypeSuperVisitable<TyCtxt<'tcx>> for ty::Const<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for InferConst<'tcx> {
+impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for InferConst {
     fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
         self,
         _folder: &mut F,
@@ -871,7 +859,7 @@ impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for InferConst<'tcx> {
     }
 }
 
-impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for InferConst<'tcx> {
+impl<'tcx> TypeVisitable<TyCtxt<'tcx>> for InferConst {
     fn visit_with<V: TypeVisitor<TyCtxt<'tcx>>>(
         &self,
         _visitor: &mut V,
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index f93a23158fb0f..53260a3996cfb 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -29,7 +29,6 @@ use std::assert_matches::debug_assert_matches;
 use std::borrow::Cow;
 use std::cmp::Ordering;
 use std::fmt;
-use std::marker::PhantomData;
 use std::ops::{ControlFlow, Deref, Range};
 use ty::util::IntTypeExt;
 
@@ -1583,26 +1582,22 @@ impl fmt::Debug for EarlyBoundRegion {
     }
 }
 
-/// A **`const`** **v**ariable **ID**.
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[derive(HashStable, TyEncodable, TyDecodable)]
-pub struct ConstVid<'tcx> {
-    pub index: u32,
-    pub phantom: PhantomData<&'tcx ()>,
+rustc_index::newtype_index! {
+    /// A **`const`** **v**ariable **ID**.
+    #[debug_format = "?{}c"]
+    pub struct ConstVid {}
 }
 
-/// An **effect** **v**ariable **ID**.
-///
-/// Handling effect infer variables happens separately from const infer variables
-/// because we do not want to reuse any of the const infer machinery. If we try to
-/// relate an effect variable with a normal one, we would ICE, which can catch bugs
-/// where we are not correctly using the effect var for an effect param. Fallback
-/// is also implemented on top of having separate effect and normal const variables.
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
-#[derive(TyEncodable, TyDecodable)]
-pub struct EffectVid<'tcx> {
-    pub index: u32,
-    pub phantom: PhantomData<&'tcx ()>,
+rustc_index::newtype_index! {
+    /// An **effect** **v**ariable **ID**.
+    ///
+    /// Handling effect infer variables happens separately from const infer variables
+    /// because we do not want to reuse any of the const infer machinery. If we try to
+    /// relate an effect variable with a normal one, we would ICE, which can catch bugs
+    /// where we are not correctly using the effect var for an effect param. Fallback
+    /// is also implemented on top of having separate effect and normal const variables.
+    #[debug_format = "?{}e"]
+    pub struct EffectVid {}
 }
 
 rustc_index::newtype_index! {
diff --git a/compiler/rustc_trait_selection/src/traits/fulfill.rs b/compiler/rustc_trait_selection/src/traits/fulfill.rs
index 55b5604b16b55..fb9cf51b513bb 100644
--- a/compiler/rustc_trait_selection/src/traits/fulfill.rs
+++ b/compiler/rustc_trait_selection/src/traits/fulfill.rs
@@ -1,4 +1,5 @@
 use crate::infer::{InferCtxt, TyOrConstInferVar};
+use rustc_data_structures::captures::Captures;
 use rustc_data_structures::obligation_forest::ProcessResult;
 use rustc_data_structures::obligation_forest::{Error, ForestObligation, Outcome};
 use rustc_data_structures::obligation_forest::{ObligationForest, ObligationProcessor};
@@ -68,7 +69,7 @@ pub struct PendingPredicateObligation<'tcx> {
     // should mostly optimize for reading speed, while modifying is not as relevant.
     //
     // For whatever reason using a boxed slice is slower than using a `Vec` here.
-    pub stalled_on: Vec<TyOrConstInferVar<'tcx>>,
+    pub stalled_on: Vec<TyOrConstInferVar>,
 }
 
 // `PendingPredicateObligation` is used a lot. Make sure it doesn't unintentionally get bigger.
@@ -669,7 +670,7 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
         &mut self,
         obligation: &PredicateObligation<'tcx>,
         trait_obligation: PolyTraitObligation<'tcx>,
-        stalled_on: &mut Vec<TyOrConstInferVar<'tcx>>,
+        stalled_on: &mut Vec<TyOrConstInferVar>,
     ) -> ProcessResult<PendingPredicateObligation<'tcx>, FulfillmentErrorCode<'tcx>> {
         let infcx = self.selcx.infcx;
         if obligation.predicate.is_global() && !self.selcx.is_intercrate() {
@@ -722,7 +723,7 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
         &mut self,
         obligation: &PredicateObligation<'tcx>,
         project_obligation: PolyProjectionObligation<'tcx>,
-        stalled_on: &mut Vec<TyOrConstInferVar<'tcx>>,
+        stalled_on: &mut Vec<TyOrConstInferVar>,
     ) -> ProcessResult<PendingPredicateObligation<'tcx>, FulfillmentErrorCode<'tcx>> {
         let tcx = self.selcx.tcx();
 
@@ -775,7 +776,7 @@ impl<'a, 'tcx> FulfillProcessor<'a, 'tcx> {
 fn args_infer_vars<'a, 'tcx>(
     selcx: &SelectionContext<'a, 'tcx>,
     args: ty::Binder<'tcx, GenericArgsRef<'tcx>>,
-) -> impl Iterator<Item = TyOrConstInferVar<'tcx>> {
+) -> impl Iterator<Item = TyOrConstInferVar> + Captures<'tcx> {
     selcx
         .infcx
         .resolve_vars_if_possible(args)