Create intermediate enum ty::ConstKind.

28 files changed, 205 insertions, 200 deletions

diff --git a/src/librustc/infer/canonical/canonicalizer.rs b/src/librustc/infer/canonical/canonicalizer.rs
index 49a2c90bdbf..e782ec59295 100644
--- a/src/librustc/infer/canonical/canonicalizer.rs
+++ b/src/librustc/infer/canonical/canonicalizer.rs
@@ -10,7 +10,6 @@ use crate::infer::canonical::{
     OriginalQueryValues,
 };
 use crate::infer::InferCtxt;
-use crate::mir::interpret::ConstValue;
 use std::sync::atomic::Ordering;
 use crate::ty::fold::{TypeFoldable, TypeFolder};
 use crate::ty::subst::GenericArg;
@@ -441,7 +440,7 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
         match ct.val {
-            ConstValue::Infer(InferConst::Var(vid)) => {
+            ty::ConstKind::Infer(InferConst::Var(vid)) => {
                 debug!("canonical: const var found with vid {:?}", vid);
                 match self.infcx.unwrap().probe_const_var(vid) {
                     Ok(c) => {
@@ -465,17 +464,17 @@ impl<'cx, 'tcx> TypeFolder<'tcx> for Canonicalizer<'cx, 'tcx> {
                     }
                 }
             }
-            ConstValue::Infer(InferConst::Fresh(_)) => {
+            ty::ConstKind::Infer(InferConst::Fresh(_)) => {
                 bug!("encountered a fresh const during canonicalization")
             }
-            ConstValue::Bound(debruijn, _) => {
+            ty::ConstKind::Bound(debruijn, _) => {
                 if debruijn >= self.binder_index {
                     bug!("escaping bound type during canonicalization")
                 } else {
                     return ct;
                 }
             }
-            ConstValue::Placeholder(placeholder) => {
+            ty::ConstKind::Placeholder(placeholder) => {
                 return self.canonicalize_const_var(
                     CanonicalVarInfo {
                         kind: CanonicalVarKind::PlaceholderConst(placeholder),
@@ -700,7 +699,7 @@ impl<'cx, 'tcx> Canonicalizer<'cx, 'tcx> {
             let var = self.canonical_var(info, const_var.into());
             self.tcx().mk_const(
                 ty::Const {
-                    val: ConstValue::Bound(self.binder_index, var.into()),
+                    val: ty::ConstKind::Bound(self.binder_index, var.into()),
                     ty: self.fold_ty(const_var.ty),
                 }
             )
diff --git a/src/librustc/infer/canonical/mod.rs b/src/librustc/infer/canonical/mod.rs
index d833feeeb09..4e86cbb2cf6 100644
--- a/src/librustc/infer/canonical/mod.rs
+++ b/src/librustc/infer/canonical/mod.rs
@@ -24,7 +24,6 @@
 use crate::infer::{InferCtxt, RegionVariableOrigin, TypeVariableOrigin, TypeVariableOriginKind};
 use crate::infer::{ConstVariableOrigin, ConstVariableOriginKind};
 use crate::infer::region_constraints::MemberConstraint;
-use crate::mir::interpret::ConstValue;
 use rustc_index::vec::IndexVec;
 use rustc_macros::HashStable;
 use rustc_serialize::UseSpecializedDecodable;
@@ -447,7 +446,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                 };
                 self.tcx.mk_const(
                     ty::Const {
-                        val: ConstValue::Placeholder(placeholder_mapped),
+                        val: ty::ConstKind::Placeholder(placeholder_mapped),
                         ty: self.tcx.types.err, // FIXME(const_generics)
                     }
                 ).into()
@@ -510,7 +509,7 @@ impl<'tcx> CanonicalVarValues<'tcx> {
                     GenericArgKind::Const(ct) => {
                         tcx.mk_const(ty::Const {
                             ty: ct.ty,
-                            val: ConstValue::Bound(ty::INNERMOST, ty::BoundVar::from_u32(i)),
+                            val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from_u32(i)),
                         }).into()
                     }
                 })
diff --git a/src/librustc/infer/canonical/query_response.rs b/src/librustc/infer/canonical/query_response.rs
index 7ad6006012f..825e98cedb9 100644
--- a/src/librustc/infer/canonical/query_response.rs
+++ b/src/librustc/infer/canonical/query_response.rs
@@ -16,7 +16,6 @@ use crate::infer::canonical::{
 use crate::infer::region_constraints::{Constraint, RegionConstraintData};
 use crate::infer::InferCtxtBuilder;
 use crate::infer::{InferCtxt, InferOk, InferResult};
-use crate::mir::interpret::ConstValue;
 use rustc_index::vec::Idx;
 use rustc_index::vec::IndexVec;
 use std::fmt::Debug;
@@ -493,7 +492,7 @@ impl<'cx, 'tcx> InferCtxt<'cx, 'tcx> {
                     }
                 }
                 GenericArgKind::Const(result_value) => {
-                    if let ty::Const { val: ConstValue::Bound(debrujin, b), .. } = result_value {
+                    if let ty::Const { val: ty::ConstKind::Bound(debrujin, b), .. } = result_value {
                         // ...in which case we would set `canonical_vars[0]` to `Some(const X)`.
 
                         // We only allow a `ty::INNERMOST` index in substitutions.
diff --git a/src/librustc/infer/combine.rs b/src/librustc/infer/combine.rs
index 51ae4e49493..a2f0531f0af 100644
--- a/src/librustc/infer/combine.rs
+++ b/src/librustc/infer/combine.rs
@@ -33,7 +33,6 @@ use super::unify_key::{ConstVariableOrigin, ConstVariableOriginKind};
 use super::unify_key::replace_if_possible;
 
 use crate::hir::def_id::DefId;
-use crate::mir::interpret::ConstValue;
 use crate::ty::{IntType, UintType};
 use crate::ty::{self, Ty, TyCtxt, InferConst};
 use crate::ty::error::TypeError;
@@ -137,8 +136,8 @@ impl<'infcx, 'tcx> InferCtxt<'infcx, 'tcx> {
         let a_is_expected = relation.a_is_expected();
 
         match (a.val, b.val) {
-            (ConstValue::Infer(InferConst::Var(a_vid)),
-                ConstValue::Infer(InferConst::Var(b_vid))) => {
+            (ty::ConstKind::Infer(InferConst::Var(a_vid)),
+                ty::ConstKind::Infer(InferConst::Var(b_vid))) => {
                 self.const_unification_table
                     .borrow_mut()
                     .unify_var_var(a_vid, b_vid)
@@ -147,16 +146,16 @@ impl<'infcx, 'tcx> InferCtxt<'infcx, 'tcx> {
             }
 
             // All other cases of inference with other variables are errors.
-            (ConstValue::Infer(InferConst::Var(_)), ConstValue::Infer(_)) |
-            (ConstValue::Infer(_), ConstValue::Infer(InferConst::Var(_))) => {
-                bug!("tried to combine ConstValue::Infer/ConstValue::Infer(InferConst::Var)")
+            (ty::ConstKind::Infer(InferConst::Var(_)), ty::ConstKind::Infer(_)) |
+            (ty::ConstKind::Infer(_), ty::ConstKind::Infer(InferConst::Var(_))) => {
+                bug!("tried to combine ConstKind::Infer/ConstKind::Infer(InferConst::Var)")
             }
 
-            (ConstValue::Infer(InferConst::Var(vid)), _) => {
+            (ty::ConstKind::Infer(InferConst::Var(vid)), _) => {
                 return self.unify_const_variable(a_is_expected, vid, b);
             }
 
-            (_, ConstValue::Infer(InferConst::Var(vid))) => {
+            (_, ty::ConstKind::Infer(InferConst::Var(vid))) => {
                 return self.unify_const_variable(!a_is_expected, vid, a);
             }
 
@@ -603,7 +602,7 @@ impl TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
         assert_eq!(c, c2); // we are abusing TypeRelation here; both LHS and RHS ought to be ==
 
         match c.val {
-            ConstValue::Infer(InferConst::Var(vid)) => {
+            ty::ConstKind::Infer(InferConst::Var(vid)) => {
                 let mut variable_table = self.infcx.const_unification_table.borrow_mut();
                 let var_value = variable_table.probe_value(vid);
                 match var_value.val {
diff --git a/src/librustc/infer/freshen.rs b/src/librustc/infer/freshen.rs
index 1841bd9ea64..32b51da920d 100644
--- a/src/librustc/infer/freshen.rs
+++ b/src/librustc/infer/freshen.rs
@@ -31,7 +31,6 @@
 //! variable only once, and it does so as soon as it can, so it is reasonable to ask what the type
 //! inferencer knows "so far".
 
-use crate::mir::interpret::ConstValue;
 use crate::ty::{self, Ty, TyCtxt, TypeFoldable};
 use crate::ty::fold::TypeFolder;
 use crate::util::nodemap::FxHashMap;
@@ -227,7 +226,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
         match ct.val {
-            ConstValue::Infer(ty::InferConst::Var(v)) => {
+            ty::ConstKind::Infer(ty::InferConst::Var(v)) => {
                 let opt_ct = self.infcx.const_unification_table
                     .borrow_mut()
                     .probe_value(v)
@@ -240,7 +239,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
                     ct.ty,
                 );
             }
-            ConstValue::Infer(ty::InferConst::Fresh(i)) => {
+            ty::ConstKind::Infer(ty::InferConst::Fresh(i)) => {
                 if i >= self.const_freshen_count {
                     bug!(
                         "Encountered a freshend const with id {} \
@@ -252,16 +251,14 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
                 return ct;
             }
 
-            ConstValue::Bound(..) |
-            ConstValue::Placeholder(_) => {
+            ty::ConstKind::Bound(..) |
+            ty::ConstKind::Placeholder(_) => {
                 bug!("unexpected const {:?}", ct)
             }
 
-            ConstValue::Param(_) |
-            ConstValue::Scalar(_) |
-            ConstValue::Slice { .. } |
-            ConstValue::ByRef { .. } |
-            ConstValue::Unevaluated(..) => {}
+            ty::ConstKind::Param(_) |
+            ty::ConstKind::Value(_) |
+            ty::ConstKind::Unevaluated(..) => {}
         }
 
         ct.super_fold_with(self)
diff --git a/src/librustc/infer/fudge.rs b/src/librustc/infer/fudge.rs
index e27766f4616..11f86a619b5 100644
--- a/src/librustc/infer/fudge.rs
+++ b/src/librustc/infer/fudge.rs
@@ -1,6 +1,5 @@
 use crate::ty::{self, Ty, TyCtxt, TyVid, IntVid, FloatVid, RegionVid, ConstVid};
 use crate::ty::fold::{TypeFoldable, TypeFolder};
-use crate::mir::interpret::ConstValue;
 
 use super::InferCtxt;
 use super::{RegionVariableOrigin, ConstVariableOrigin};
@@ -198,7 +197,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for InferenceFudger<'a, 'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const { val: ConstValue::Infer(ty::InferConst::Var(vid)), ty } = ct {
+        if let ty::Const { val: ty::ConstKind::Infer(ty::InferConst::Var(vid)), ty } = ct {
             if self.const_vars.0.contains(&vid) {
                 // This variable was created during the fudging.
                 // Recreate it with a fresh variable here.
diff --git a/src/librustc/infer/higher_ranked/mod.rs b/src/librustc/infer/higher_ranked/mod.rs
index 542ac4931ec..49c095c69d6 100644
--- a/src/librustc/infer/higher_ranked/mod.rs
+++ b/src/librustc/infer/higher_ranked/mod.rs
@@ -7,7 +7,6 @@ use super::{HigherRankedType, InferCtxt, PlaceholderMap};
 use crate::infer::CombinedSnapshot;
 use crate::ty::relate::{Relate, RelateResult, TypeRelation};
 use crate::ty::{self, Binder, TypeFoldable};
-use crate::mir::interpret::ConstValue;
 
 impl<'a, 'tcx> CombineFields<'a, 'tcx> {
     pub fn higher_ranked_sub<T>(
@@ -103,7 +102,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
         let fld_c = |bound_var: ty::BoundVar, ty| {
             self.tcx.mk_const(
                 ty::Const {
-                    val: ConstValue::Placeholder(ty::PlaceholderConst {
+                    val: ty::ConstKind::Placeholder(ty::PlaceholderConst {
                         universe: next_universe,
                         name: bound_var,
                     }),
diff --git a/src/librustc/infer/mod.rs b/src/librustc/infer/mod.rs
index e385d576b8c..49fb84a8260 100644
--- a/src/librustc/infer/mod.rs
+++ b/src/librustc/infer/mod.rs
@@ -14,7 +14,6 @@ use crate::infer::unify_key::{ConstVarValue, ConstVariableValue};
 use crate::middle::free_region::RegionRelations;
 use crate::middle::lang_items;
 use crate::middle::region;
-use crate::mir::interpret::ConstValue;
 use crate::session::config::BorrowckMode;
 use crate::traits::{self, ObligationCause, PredicateObligations, TraitEngine};
 use crate::ty::error::{ExpectedFound, TypeError, UnconstrainedNumeric};
@@ -1662,7 +1661,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for ShallowResolver<'a, 'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const { val: ConstValue::Infer(InferConst::Var(vid)), .. } = ct {
+        if let ty::Const { val: ty::ConstKind::Infer(InferConst::Var(vid)), .. } = ct {
                 self.infcx.const_unification_table
                     .borrow_mut()
                     .probe_value(*vid)
diff --git a/src/librustc/infer/nll_relate/mod.rs b/src/librustc/infer/nll_relate/mod.rs
index d6f76e9ee34..1e0feb6a7da 100644
--- a/src/librustc/infer/nll_relate/mod.rs
+++ b/src/librustc/infer/nll_relate/mod.rs
@@ -29,7 +29,6 @@ use crate::ty::relate::{self, Relate, RelateResult, TypeRelation};
 use crate::ty::subst::GenericArg;
 use crate::ty::{self, Ty, TyCtxt, InferConst};
 use crate::infer::{ConstVariableValue, ConstVarValue};
-use crate::mir::interpret::ConstValue;
 use rustc_data_structures::fx::FxHashMap;
 use std::fmt::Debug;
 
@@ -626,7 +625,7 @@ where
         }
 
         match b.val {
-            ConstValue::Infer(InferConst::Var(_)) if D::forbid_inference_vars() => {
+            ty::ConstKind::Infer(InferConst::Var(_)) if D::forbid_inference_vars() => {
                 // Forbid inference variables in the RHS.
                 bug!("unexpected inference var {:?}", b)
             }
@@ -999,13 +998,13 @@ where
         _: &'tcx ty::Const<'tcx>,
     ) -> RelateResult<'tcx, &'tcx ty::Const<'tcx>> {
         match a.val {
-            ConstValue::Infer(InferConst::Var(_)) if D::forbid_inference_vars() => {
+            ty::ConstKind::Infer(InferConst::Var(_)) if D::forbid_inference_vars() => {
                 bug!(
                     "unexpected inference variable encountered in NLL generalization: {:?}",
                     a
                 );
             }
-            ConstValue::Infer(InferConst::Var(vid)) => {
+            ty::ConstKind::Infer(InferConst::Var(vid)) => {
                 let mut variable_table = self.infcx.const_unification_table.borrow_mut();
                 let var_value = variable_table.probe_value(vid);
                 match var_value.val.known() {
diff --git a/src/librustc/infer/opaque_types/mod.rs b/src/librustc/infer/opaque_types/mod.rs
index bd19a002fe8..dc54a273ed0 100644
--- a/src/librustc/infer/opaque_types/mod.rs
+++ b/src/librustc/infer/opaque_types/mod.rs
@@ -4,7 +4,6 @@ use crate::hir::Node;
 use crate::infer::outlives::free_region_map::FreeRegionRelations;
 use crate::infer::{self, InferCtxt, InferOk, TypeVariableOrigin, TypeVariableOriginKind};
 use crate::middle::region;
-use crate::mir::interpret::ConstValue;
 use crate::traits::{self, PredicateObligation};
 use crate::ty::fold::{BottomUpFolder, TypeFoldable, TypeFolder, TypeVisitor};
 use crate::ty::subst::{InternalSubsts, GenericArg, SubstsRef, GenericArgKind};
@@ -945,7 +944,7 @@ impl TypeFolder<'tcx> for ReverseMapper<'tcx> {
         trace!("checking const {:?}", ct);
         // Find a const parameter
         match ct.val {
-            ConstValue::Param(..) => {
+            ty::ConstKind::Param(..) => {
                 // Look it up in the substitution list.
                 match self.map.get(&ct.into()).map(|k| k.unpack()) {
                     // Found it in the substitution list, replace with the parameter from the
diff --git a/src/librustc/infer/resolve.rs b/src/librustc/infer/resolve.rs
index 7c3a338366c..613f66d7ffd 100644
--- a/src/librustc/infer/resolve.rs
+++ b/src/librustc/infer/resolve.rs
@@ -1,6 +1,5 @@
 use super::{InferCtxt, FixupError, FixupResult, Span};
 use super::type_variable::{TypeVariableOrigin, TypeVariableOriginKind};
-use crate::mir::interpret::ConstValue;
 use crate::ty::{self, Ty, Const, TyCtxt, TypeFoldable, InferConst};
 use crate::ty::fold::{TypeFolder, TypeVisitor};
 
@@ -230,11 +229,11 @@ impl<'a, 'tcx> TypeFolder<'tcx> for FullTypeResolver<'a, 'tcx> {
         } else {
             let c = self.infcx.shallow_resolve(c);
             match c.val {
-                ConstValue::Infer(InferConst::Var(vid)) => {
+                ty::ConstKind::Infer(InferConst::Var(vid)) => {
                     self.err = Some(FixupError::UnresolvedConst(vid));
                     return self.tcx().consts.err;
                 }
-                ConstValue::Infer(InferConst::Fresh(_)) => {
+                ty::ConstKind::Infer(InferConst::Fresh(_)) => {
                     bug!("Unexpected const in full const resolver: {:?}", c);
                 }
                 _ => {}
diff --git a/src/librustc/infer/unify_key.rs b/src/librustc/infer/unify_key.rs
index b0b6d971c60..8ad6990a75d 100644
--- a/src/librustc/infer/unify_key.rs
+++ b/src/librustc/infer/unify_key.rs
@@ -1,5 +1,4 @@
 use crate::ty::{self, FloatVarValue, IntVarValue, Ty, TyCtxt, InferConst};
-use crate::mir::interpret::ConstValue;
 use rustc_data_structures::unify::{NoError, EqUnifyValue, UnifyKey, UnifyValue, UnificationTable};
 use rustc_data_structures::unify::InPlace;
 use syntax_pos::{Span, DUMMY_SP};
@@ -180,7 +179,7 @@ pub fn replace_if_possible(
     mut table: RefMut<'_, UnificationTable<InPlace<ty::ConstVid<'tcx>>>>,
     c: &'tcx ty::Const<'tcx>
 ) -> &'tcx ty::Const<'tcx> {
-    if let ty::Const { val: ConstValue::Infer(InferConst::Var(vid)), .. } = c {
+    if let ty::Const { val: ty::ConstKind::Infer(InferConst::Var(vid)), .. } = c {
         match table.probe_value(*vid).val.known() {
             Some(c) => c,
             None => c,
diff --git a/src/librustc/mir/interpret/value.rs b/src/librustc/mir/interpret/value.rs
index 7b29fb26e74..e5778528e38 100644
--- a/src/librustc/mir/interpret/value.rs
+++ b/src/librustc/mir/interpret/value.rs
@@ -2,10 +2,7 @@ use std::fmt;
 use rustc_macros::HashStable;
 use rustc_apfloat::{Float, ieee::{Double, Single}};
 
-use crate::ty::{Ty, InferConst, ParamConst, layout::{HasDataLayout, Size}, subst::SubstsRef};
-use crate::ty::PlaceholderConst;
-use crate::hir::def_id::DefId;
-use crate::ty::{BoundVar, DebruijnIndex};
+use crate::ty::{Ty, layout::{HasDataLayout, Size}};
 
 use super::{InterpResult, Pointer, PointerArithmetic, Allocation, AllocId, sign_extend, truncate};
 
@@ -23,18 +20,6 @@ pub struct RawConst<'tcx> {
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord,
          RustcEncodable, RustcDecodable, Hash, HashStable)]
 pub enum ConstValue<'tcx> {
-    /// A const generic parameter.
-    Param(ParamConst),
-
-    /// Infer the value of the const.
-    Infer(InferConst<'tcx>),
-
-    /// Bound const variable, used only when preparing a trait query.
-    Bound(DebruijnIndex, BoundVar),
-
-    /// A placeholder const - universally quantified higher-ranked const.
-    Placeholder(PlaceholderConst),
-
     /// Used only for types with `layout::abi::Scalar` ABI and ZSTs.
     ///
     /// Not using the enum `Value` to encode that this must not be `Undef`.
@@ -55,10 +40,6 @@ pub enum ConstValue<'tcx> {
         /// Offset into `alloc`
         offset: Size,
     },
-
-    /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other
-    /// variants when the code is monomorphic enough for that.
-    Unevaluated(DefId, SubstsRef<'tcx>),
 }
 
 #[cfg(target_arch = "x86_64")]
@@ -68,26 +49,21 @@ impl<'tcx> ConstValue<'tcx> {
     #[inline]
     pub fn try_to_scalar(&self) -> Option<Scalar> {
         match *self {
-            ConstValue::Param(_) |
-            ConstValue::Infer(_) |
-            ConstValue::Bound(..) |
-            ConstValue::Placeholder(_) |
             ConstValue::ByRef { .. } |
-            ConstValue::Unevaluated(..) |
             ConstValue::Slice { .. } => None,
             ConstValue::Scalar(val) => Some(val),
         }
     }
-
-    #[inline]
-    pub fn try_to_bits(&self, size: Size) -> Option<u128> {
-        self.try_to_scalar()?.to_bits(size).ok()
-    }
-
-    #[inline]
-    pub fn try_to_ptr(&self) -> Option<Pointer> {
-        self.try_to_scalar()?.to_ptr().ok()
-    }
+//
+//    #[inline]
+//    pub fn try_to_bits(&self, size: Size) -> Option<u128> {
+//        self.try_to_scalar()?.to_bits(size).ok()
+//    }
+//
+//    #[inline]
+//    pub fn try_to_ptr(&self) -> Option<Pointer> {
+//        self.try_to_scalar()?.to_ptr().ok()
+//    }
 }
 
 /// A `Scalar` represents an immediate, primitive value existing outside of a
diff --git a/src/librustc/mir/mod.rs b/src/librustc/mir/mod.rs
index a3ddfec765f..066998a1718 100644
--- a/src/librustc/mir/mod.rs
+++ b/src/librustc/mir/mod.rs
@@ -7,7 +7,7 @@
 use crate::hir::def::{CtorKind, Namespace};
 use crate::hir::def_id::DefId;
 use crate::hir::{self, InlineAsm as HirInlineAsm};
-use crate::mir::interpret::{ConstValue, PanicInfo, Scalar};
+use crate::mir::interpret::{PanicInfo, Scalar};
 use crate::mir::visit::MirVisitable;
 use crate::ty::adjustment::PointerCast;
 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
@@ -1506,10 +1506,11 @@ impl<'tcx> TerminatorKind<'tcx> {
                 values
                     .iter()
                     .map(|&u| {
-                        tcx.mk_const(ty::Const {
-                            val: ConstValue::Scalar(Scalar::from_uint(u, size).into()),
-                            ty: switch_ty,
-                        })
+                        ty::Const::from_scalar(
+                            tcx,
+                            Scalar::from_uint(u, size).into(),
+                            switch_ty,
+                        )
                         .to_string()
                         .into()
                     })
diff --git a/src/librustc/ty/_match.rs b/src/librustc/ty/_match.rs
index a0d22789dae..ea8a6ff2b2e 100644
--- a/src/librustc/ty/_match.rs
+++ b/src/librustc/ty/_match.rs
@@ -1,7 +1,6 @@
 use crate::ty::{self, Ty, TyCtxt, InferConst};
 use crate::ty::error::TypeError;
 use crate::ty::relate::{self, Relate, TypeRelation, RelateResult};
-use crate::mir::interpret::ConstValue;
 
 /// A type "A" *matches* "B" if the fresh types in B could be
 /// substituted with values so as to make it equal to A. Matching is
@@ -92,11 +91,11 @@ impl TypeRelation<'tcx> for Match<'tcx> {
         }
 
         match (a.val, b.val) {
-            (_, ConstValue::Infer(InferConst::Fresh(_))) => {
+            (_, ty::ConstKind::Infer(InferConst::Fresh(_))) => {
                 return Ok(a);
             }
 
-            (ConstValue::Infer(_), _) | (_, ConstValue::Infer(_)) => {
+            (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => {
                 return Err(TypeError::ConstMismatch(relate::expected_found(self, &a, &b)));
             }
 
diff --git a/src/librustc/ty/context.rs b/src/librustc/ty/context.rs
index 04e0f6f4b56..ba014e3002b 100644
--- a/src/librustc/ty/context.rs
+++ b/src/librustc/ty/context.rs
@@ -885,7 +885,7 @@ impl CanonicalUserType<'tcx> {
                         },
 
                         GenericArgKind::Const(ct) => match ct.val {
-                            ConstValue::Bound(debruijn, b) => {
+                            ty::ConstKind::Bound(debruijn, b) => {
                                 // We only allow a `ty::INNERMOST` index in substitutions.
                                 assert_eq!(debruijn, ty::INNERMOST);
                                 cvar == b
@@ -986,7 +986,7 @@ impl<'tcx> CommonConsts<'tcx> {
 
         CommonConsts {
             err: mk_const(ty::Const {
-                val: ConstValue::Scalar(Scalar::zst()),
+                val: ty::ConstKind::Value(ConstValue::Scalar(Scalar::zst())),
                 ty: types.err,
             }),
         }
@@ -2534,7 +2534,7 @@ impl<'tcx> TyCtxt<'tcx> {
     #[inline]
     pub fn mk_const_var(self, v: ConstVid<'tcx>, ty: Ty<'tcx>) -> &'tcx Const<'tcx> {
         self.mk_const(ty::Const {
-            val: ConstValue::Infer(InferConst::Var(v)),
+            val: ty::ConstKind::Infer(InferConst::Var(v)),
             ty,
         })
     }
@@ -2561,7 +2561,7 @@ impl<'tcx> TyCtxt<'tcx> {
         ty: Ty<'tcx>,
     ) -> &'tcx ty::Const<'tcx> {
         self.mk_const(ty::Const {
-            val: ConstValue::Infer(ic),
+            val: ty::ConstKind::Infer(ic),
             ty,
         })
     }
@@ -2579,7 +2579,7 @@ impl<'tcx> TyCtxt<'tcx> {
         ty: Ty<'tcx>
     ) -> &'tcx Const<'tcx> {
         self.mk_const(ty::Const {
-            val: ConstValue::Param(ParamConst { index, name }),
+            val: ty::ConstKind::Param(ParamConst { index, name }),
             ty,
         })
     }
diff --git a/src/librustc/ty/flags.rs b/src/librustc/ty/flags.rs
index d4b7f37b120..aee0ec7806b 100644
--- a/src/librustc/ty/flags.rs
+++ b/src/librustc/ty/flags.rs
@@ -1,6 +1,5 @@
 use crate::ty::subst::{SubstsRef, GenericArgKind};
 use crate::ty::{self, Ty, TypeFlags, InferConst};
-use crate::mir::interpret::ConstValue;
 
 #[derive(Debug)]
 pub struct FlagComputation {
@@ -232,29 +231,27 @@ impl FlagComputation {
     fn add_const(&mut self, c: &ty::Const<'_>) {
         self.add_ty(c.ty);
         match c.val {
-            ConstValue::Unevaluated(_, substs) => {
+            ty::ConstKind::Unevaluated(_, substs) => {
                 self.add_substs(substs);
                 self.add_flags(TypeFlags::HAS_PROJECTION);
             },
-            ConstValue::Infer(infer) => {
+            ty::ConstKind::Infer(infer) => {
                 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES | TypeFlags::HAS_CT_INFER);
                 match infer {
                     InferConst::Fresh(_) => {}
                     InferConst::Var(_) => self.add_flags(TypeFlags::KEEP_IN_LOCAL_TCX),
                 }
             }
-            ConstValue::Bound(debruijn, _) => self.add_binder(debruijn),
-            ConstValue::Param(_) => {
+            ty::ConstKind::Bound(debruijn, _) => self.add_binder(debruijn),
+            ty::ConstKind::Param(_) => {
                 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
                 self.add_flags(TypeFlags::HAS_PARAMS);
             }
-            ConstValue::Placeholder(_) => {
+            ty::ConstKind::Placeholder(_) => {
                 self.add_flags(TypeFlags::HAS_FREE_LOCAL_NAMES);
                 self.add_flags(TypeFlags::HAS_CT_PLACEHOLDER);
             }
-            ConstValue::Scalar(_) => {}
-            ConstValue::Slice { .. } => {}
-            ConstValue::ByRef { .. } => {}
+            ty::ConstKind::Value(_) => {}
         }
     }
 
diff --git a/src/librustc/ty/fold.rs b/src/librustc/ty/fold.rs
index bacf3d42f04..f3480ce5739 100644
--- a/src/librustc/ty/fold.rs
+++ b/src/librustc/ty/fold.rs
@@ -32,7 +32,6 @@
 //! looking for, and does not need to visit anything else.
 
 use crate::hir::def_id::DefId;
-use crate::mir::interpret::ConstValue;
 use crate::ty::{self, Binder, Ty, TyCtxt, TypeFlags, flags::FlagComputation};
 
 use std::collections::BTreeMap;
@@ -521,7 +520,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for BoundVarReplacer<'a, 'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const { val: ConstValue::Bound(debruijn, bound_const), ty } = *ct {
+        if let ty::Const { val: ty::ConstKind::Bound(debruijn, bound_const), ty } = *ct {
             if debruijn == self.current_index {
                 let fld_c = &mut self.fld_c;
                 let ct = fld_c(bound_const, ty);
@@ -568,7 +567,7 @@ impl<'tcx> TyCtxt<'tcx> {
         let fld_t = |bound_ty| self.mk_ty(ty::Bound(ty::INNERMOST, bound_ty));
         let fld_c = |bound_ct, ty| {
             self.mk_const(ty::Const {
-                val: ConstValue::Bound(ty::INNERMOST, bound_ct),
+                val: ty::ConstKind::Bound(ty::INNERMOST, bound_ct),
                 ty,
             })
         };
@@ -801,7 +800,7 @@ impl TypeFolder<'tcx> for Shifter<'tcx> {
     }
 
     fn fold_const(&mut self, ct: &'tcx ty::Const<'tcx>) -> &'tcx ty::Const<'tcx> {
-        if let ty::Const { val: ConstValue::Bound(debruijn, bound_ct), ty } = *ct {
+        if let ty::Const { val: ty::ConstKind::Bound(debruijn, bound_ct), ty } = *ct {
             if self.amount == 0 || debruijn < self.current_index {
                 ct
             } else {
@@ -813,7 +812,7 @@ impl TypeFolder<'tcx> for Shifter<'tcx> {
                     }
                 };
                 self.tcx.mk_const(ty::Const {
-                    val: ConstValue::Bound(debruijn, bound_ct),
+                    val: ty::ConstKind::Bound(debruijn, bound_ct),
                     ty,
                 })
             }
@@ -919,7 +918,7 @@ impl<'tcx> TypeVisitor<'tcx> for HasEscapingVarsVisitor {
         // const, as it has types/regions embedded in a lot of other
         // places.
         match ct.val {
-            ConstValue::Bound(debruijn, _) if debruijn >= self.outer_index => true,
+            ty::ConstKind::Bound(debruijn, _) if debruijn >= self.outer_index => true,
             _ => ct.super_visit_with(self),
         }
     }
diff --git a/src/librustc/ty/mod.rs b/src/librustc/ty/mod.rs
index e4ed1cd198e..8aa212ce310 100644
--- a/src/librustc/ty/mod.rs
+++ b/src/librustc/ty/mod.rs
@@ -63,7 +63,7 @@ pub use self::sty::{InferTy, ParamTy, ParamConst, InferConst, ProjectionTy, Exis
 pub use self::sty::{ClosureSubsts, GeneratorSubsts, UpvarSubsts, TypeAndMut};
 pub use self::sty::{TraitRef, TyKind, PolyTraitRef};
 pub use self::sty::{ExistentialTraitRef, PolyExistentialTraitRef};
-pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const};
+pub use self::sty::{ExistentialProjection, PolyExistentialProjection, Const, ConstKind};
 pub use self::sty::{BoundRegion, EarlyBoundRegion, FreeRegion, Region};
 pub use self::sty::RegionKind;
 pub use self::sty::{TyVid, IntVid, FloatVid, ConstVid, RegionVid};
diff --git a/src/librustc/ty/print/obsolete.rs b/src/librustc/ty/print/obsolete.rs
index 0389218b61d..7eb774849b1 100644
--- a/src/librustc/ty/print/obsolete.rs
+++ b/src/librustc/ty/print/obsolete.rs
@@ -6,7 +6,6 @@
 //! FIXME(eddyb) implement a custom `PrettyPrinter` for this.
 
 use rustc::hir::def_id::DefId;
-use rustc::mir::interpret::ConstValue;
 use rustc::ty::subst::SubstsRef;
 use rustc::ty::{self, Const, Instance, Ty, TyCtxt};
 use rustc::{bug, hir};
@@ -170,21 +169,16 @@ impl DefPathBasedNames<'tcx> {
     // If `debug` is true, usually-unprintable consts (such as `Infer`) will be printed,
     // as well as the unprintable types of constants (see `push_type_name` for more details).
     pub fn push_const_name(&self, c: &Const<'tcx>, output: &mut String, debug: bool) {
-        match c.val {
-            ConstValue::Scalar(..) | ConstValue::Slice { .. } | ConstValue::ByRef { .. } => {
-                // FIXME(const_generics): we could probably do a better job here.
-                write!(output, "{:?}", c).unwrap()
-            }
-            _ => {
-                if debug {
-                    write!(output, "{:?}", c).unwrap()
-                } else {
-                    bug!(
-                        "DefPathBasedNames: trying to create const name for unexpected const: {:?}",
-                        c,
-                    );
-                }
-            }
+        if let ty::ConstKind::Value(_) = c.val {
+            // FIXME(const_generics): we could probably do a better job here.
+            write!(output, "{:?}", c).unwrap()
+        } else if debug {
+            write!(output, "{:?}", c).unwrap()
+        } else {
+            bug!(
+                "DefPathBasedNames: trying to create const name for unexpected const: {:?}",
+                c,
+            );
         }
         output.push_str(": ");
         self.push_type_name(c.ty, output, debug);
diff --git a/src/librustc/ty/print/pretty.rs b/src/librustc/ty/print/pretty.rs
index fdd3a1faaa9..c70bb2552cc 100644
--- a/src/librustc/ty/print/pretty.rs
+++ b/src/librustc/ty/print/pretty.rs
@@ -699,7 +699,7 @@ pub trait PrettyPrinter<'tcx>:
                 p!(write("["), print(ty), write("; "));
                 if self.tcx().sess.verbose() {
                     p!(write("{:?}", sz));
-                } else if let ConstValue::Unevaluated(..) = sz.val {
+                } else if let ty::ConstKind::Unevaluated(..) = sz.val {
                     // do not try to evalute unevaluated constants. If we are const evaluating an
                     // array length anon const, rustc will (with debug assertions) print the
                     // constant's path. Which will end up here again.
@@ -865,7 +865,7 @@ pub trait PrettyPrinter<'tcx>:
 
         match (ct.val, &ct.ty.kind) {
             (_,  ty::FnDef(did, substs)) => p!(print_value_path(*did, substs)),
-            (ConstValue::Unevaluated(did, substs), _) => {
+            (ty::ConstKind::Unevaluated(did, substs), _) => {
                 match self.tcx().def_kind(did) {
                     | Some(DefKind::Static)
                     | Some(DefKind::Const)
@@ -882,15 +882,15 @@ pub trait PrettyPrinter<'tcx>:
                     },
                 }
             },
-            (ConstValue::Infer(..), _) =>  p!(write("_: "), print(ct.ty)),
-            (ConstValue::Param(ParamConst { name, .. }), _) => p!(write("{}", name)),
-            (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Bool) =>
+            (ty::ConstKind::Infer(..), _) =>  p!(write("_: "), print(ct.ty)),
+            (ty::ConstKind::Param(ParamConst { name, .. }), _) => p!(write("{}", name)),
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data, .. })), ty::Bool) =>
                 p!(write("{}", if data == 0 { "false" } else { "true" })),
-            (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Float(ast::FloatTy::F32)) =>
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data, .. })), ty::Float(ast::FloatTy::F32)) =>
                 p!(write("{}f32", Single::from_bits(data))),
-            (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Float(ast::FloatTy::F64)) =>
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data, .. })), ty::Float(ast::FloatTy::F64)) =>
                 p!(write("{}f64", Double::from_bits(data))),
-            (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Uint(ui)) => {
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data, .. })), ty::Uint(ui)) => {
                 let bit_size = Integer::from_attr(&self.tcx(), UnsignedInt(*ui)).size();
                 let max = truncate(u128::max_value(), bit_size);
 
@@ -901,7 +901,7 @@ pub trait PrettyPrinter<'tcx>:
                     p!(write("{}{}", data, ui_str))
                 };
             },
-            (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Int(i)) => {
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data, .. })), ty::Int(i)) => {
                 let bit_size = Integer::from_attr(&self.tcx(), SignedInt(*i))
                     .size().bits() as u128;
                 let min = 1u128 << (bit_size - 1);
@@ -918,10 +918,10 @@ pub trait PrettyPrinter<'tcx>:
                     _ => p!(write("{}{}", sign_extend(data, size) as i128, i_str))
                 }
             },
-            (ConstValue::Scalar(Scalar::Raw { data, .. }), ty::Char) =>
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Raw { data, .. })), ty::Char) =>
                 p!(write("{:?}", ::std::char::from_u32(data as u32).unwrap())),
-            (ConstValue::Scalar(_), ty::RawPtr(_)) => p!(write("{{pointer}}")),
-            (ConstValue::Scalar(Scalar::Ptr(ptr)), ty::FnPtr(_)) => {
+            (ty::ConstKind::Value(ConstValue::Scalar(_)), ty::RawPtr(_)) => p!(write("{{pointer}}")),
+            (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Ptr(ptr))), ty::FnPtr(_)) => {
                 let instance = {
                     let alloc_map = self.tcx().alloc_map.lock();
                     alloc_map.unwrap_fn(ptr.alloc_id)
@@ -931,14 +931,14 @@ pub trait PrettyPrinter<'tcx>:
             _ => {
                 let printed = if let ty::Ref(_, ref_ty, _) = ct.ty.kind {
                     let byte_str = match (ct.val, &ref_ty.kind) {
-                        (ConstValue::Scalar(Scalar::Ptr(ptr)), ty::Array(t, n)) if *t == u8 => {
+                        (ty::ConstKind::Value(ConstValue::Scalar(Scalar::Ptr(ptr))), ty::Array(t, n)) if *t == u8 => {
                             let n = n.eval_usize(self.tcx(), ty::ParamEnv::empty());
                             Some(self.tcx()
                                 .alloc_map.lock()
                                 .unwrap_memory(ptr.alloc_id)
                                 .get_bytes(&self.tcx(), ptr, Size::from_bytes(n)).unwrap())
                         },
-                        (ConstValue::Slice { data, start, end }, ty::Slice(t)) if *t == u8 => {
+                        (ty::ConstKind::Value(ConstValue::Slice { data, start, end }), ty::Slice(t)) if *t == u8 => {
                             // The `inspect` here is okay since we checked the bounds, and there are
                             // no relocations (we have an active slice reference here). We don't use
                             // this result to affect interpreter execution.
@@ -956,7 +956,7 @@ pub trait PrettyPrinter<'tcx>:
                         }
                         p!(write("\""));
                         true
-                    } else if let (ConstValue::Slice { data, start, end }, ty::Str) =
+                    } else if let (ty::ConstKind::Value(ConstValue::Slice { data, start, end }), ty::Str) =
                         (ct.val, &ref_ty.kind)
                     {
                         // The `inspect` here is okay since we checked the bounds, and there are no
diff --git a/src/librustc/ty/relate.rs b/src/librustc/ty/relate.rs
index 9b5cdc489a8..49a25347912 100644
--- a/src/librustc/ty/relate.rs
+++ b/src/librustc/ty/relate.rs
@@ -561,51 +561,62 @@ pub fn super_relate_consts<R: TypeRelation<'tcx>>(
     // and those that derive both `PartialEq` and `Eq`, corresponding
     // to `structural_match` types.
     let new_const_val = match (eagerly_eval(a), eagerly_eval(b)) {
-        (ConstValue::Infer(_), _) | (_, ConstValue::Infer(_)) => {
+        (ty::ConstKind::Infer(_), _) | (_, ty::ConstKind::Infer(_)) => {
             // The caller should handle these cases!
             bug!("var types encountered in super_relate_consts: {:?} {:?}", a, b)
         }
-        (ConstValue::Param(a_p), ConstValue::Param(b_p)) if a_p.index == b_p.index => {
+        (ty::ConstKind::Param(a_p), ty::ConstKind::Param(b_p)) if a_p.index == b_p.index => {
             return Ok(a);
         }
-        (ConstValue::Placeholder(p1), ConstValue::Placeholder(p2)) if p1 == p2 => {
+        (ty::ConstKind::Placeholder(p1), ty::ConstKind::Placeholder(p2)) if p1 == p2 => {
             return Ok(a);
         }
-        (ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) if a.ty == b.ty => {
-            if a_val == b_val {
-                Ok(ConstValue::Scalar(a_val))
-            } else if let ty::FnPtr(_) = a.ty.kind {
-                let alloc_map = tcx.alloc_map.lock();
-                let a_instance = alloc_map.unwrap_fn(a_val.to_ptr().unwrap().alloc_id);
-                let b_instance = alloc_map.unwrap_fn(b_val.to_ptr().unwrap().alloc_id);
-                if a_instance == b_instance {
-                    Ok(ConstValue::Scalar(a_val))
-                } else {
-                    Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
+        (ty::ConstKind::Value(a_val), ty::ConstKind::Value(b_val)) => {
+            let new_val = match (a_val, b_val) {
+                (ConstValue::Scalar(a_val), ConstValue::Scalar(b_val)) if a.ty == b.ty => {
+                    if a_val == b_val {
+                        Ok(ConstValue::Scalar(a_val))
+                    } else if let ty::FnPtr(_) = a.ty.kind {
+                        let alloc_map = tcx.alloc_map.lock();
+                        let a_instance = alloc_map.unwrap_fn(a_val.to_ptr().unwrap().alloc_id);
+                        let b_instance = alloc_map.unwrap_fn(b_val.to_ptr().unwrap().alloc_id);
+                        if a_instance == b_instance {
+                            Ok(ConstValue::Scalar(a_val))
+                        } else {
+                            Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
+                        }
+                    } else {
+                        Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
+                    }
                 }
-            } else {
-                Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
-            }
-        }
 
-        (a_val @ ConstValue::Slice { .. }, b_val @ ConstValue::Slice { .. }) => {
-            let a_bytes = get_slice_bytes(&tcx, a_val);
-            let b_bytes = get_slice_bytes(&tcx, b_val);
-            if a_bytes == b_bytes {
-                Ok(a_val)
-            } else {
-                Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
-            }
-        }
+                (a_val @ ConstValue::Slice { .. }, b_val @ ConstValue::Slice { .. }) => {
+                    let a_bytes = get_slice_bytes(&tcx, a_val);
+                    let b_bytes = get_slice_bytes(&tcx, b_val);
+                    if a_bytes == b_bytes {
+                        Ok(a_val)
+                    } else {
+                        Err(TypeError::ConstMismatch(expected_found(relation, &a, &b)))
+                    }
+                }
+
+                // FIXME(const_generics): handle `ConstValue::ByRef`.
 
-        // FIXME(const_generics): handle `ConstValue::ByRef`.
+                _ =>  Err(TypeError::ConstMismatch(expected_found(relation, &a, &b))),
+            };
+
+            match new_val {
+                Ok(val) => Ok(ty::ConstKind::Value(val)),
+                Err(err) => Err(err),
+            }
+        },
 
         // FIXME(const_generics): this is wrong, as it is a projection
-        (ConstValue::Unevaluated(a_def_id, a_substs),
-            ConstValue::Unevaluated(b_def_id, b_substs)) if a_def_id == b_def_id => {
+        (ty::ConstKind::Unevaluated(a_def_id, a_substs),
+            ty::ConstKind::Unevaluated(b_def_id, b_substs)) if a_def_id == b_def_id => {
             let substs =
                 relation.relate_with_variance(ty::Variance::Invariant, &a_substs, &b_substs)?;
-            Ok(ConstValue::Unevaluated(a_def_id, &substs))
+            Ok(ty::ConstKind::Unevaluated(a_def_id, &substs))
         }
         _ =>  Err(TypeError::ConstMismatch(expected_found(relation, &a, &b))),
     };
diff --git a/src/librustc/ty/structural_impls.rs b/src/librustc/ty/structural_impls.rs
index 5d78d563e9a..dd92898e434 100644
--- a/src/librustc/ty/structural_impls.rs
+++ b/src/librustc/ty/structural_impls.rs
@@ -5,7 +5,6 @@
 
 use crate::hir::def::Namespace;
 use crate::mir::ProjectionKind;
-use crate::mir::interpret::ConstValue;
 use crate::ty::{self, Lift, Ty, TyCtxt, InferConst};
 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
 use crate::ty::print::{FmtPrinter, Printer};
@@ -1378,26 +1377,25 @@ impl<'tcx> TypeFoldable<'tcx> for &'tcx ty::Const<'tcx> {
     }
 }
 
-impl<'tcx> TypeFoldable<'tcx> for ConstValue<'tcx> {
+impl<'tcx> TypeFoldable<'tcx> for ty::ConstKind<'tcx> {
     fn super_fold_with<F: TypeFolder<'tcx>>(&self, folder: &mut F) -> Self {
         match *self {
-            ConstValue::Infer(ic) => ConstValue::Infer(ic.fold_with(folder)),
-            ConstValue::Param(p) => ConstValue::Param(p.fold_with(folder)),
-            ConstValue::Unevaluated(did, substs)
-                => ConstValue::Unevaluated(did, substs.fold_with(folder)),
-            ConstValue::ByRef { .. } | ConstValue::Bound(..) | ConstValue::Placeholder(..)
-            | ConstValue::Scalar(..) | ConstValue::Slice { .. } => *self,
-
+            ty::ConstKind::Infer(ic) => ty::ConstKind::Infer(ic.fold_with(folder)),
+            ty::ConstKind::Param(p) => ty::ConstKind::Param(p.fold_with(folder)),
+            ty::ConstKind::Unevaluated(did, substs)
+                => ty::ConstKind::Unevaluated(did, substs.fold_with(folder)),
+            ty::ConstKind::Value(_) | ty::ConstKind::Bound(..)
+            | ty::ConstKind::Placeholder(..) => *self,
         }
     }
 
     fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> bool {
         match *self {
-            ConstValue::Infer(ic) => ic.visit_with(visitor),
-            ConstValue::Param(p) => p.visit_with(visitor),
-            ConstValue::Unevaluated(_, substs) => substs.visit_with(visitor),
-            ConstValue::ByRef { .. } | ConstValue::Bound(..) | ConstValue::Placeholder(_)
-            | ConstValue::Scalar(_) | ConstValue::Slice { .. } => false,
+            ty::ConstKind::Infer(ic) => ic.visit_with(visitor),
+            ty::ConstKind::Param(p) => p.visit_with(visitor),
+            ty::ConstKind::Unevaluated(_, substs) => substs.visit_with(visitor),
+            ty::ConstKind::Value(_) | ty::ConstKind::Bound(..)
+            | ty::ConstKind::Placeholder(_) => false,
         }
     }
 }
diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 51cf7550c30..bb2fc9f0131 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -2257,17 +2257,17 @@ impl<'tcx> TyS<'tcx> {
 pub struct Const<'tcx> {
     pub ty: Ty<'tcx>,
 
-    pub val: ConstValue<'tcx>,
+    pub val: ConstKind<'tcx>,
 }
 
 #[cfg(target_arch = "x86_64")]
-static_assert_size!(Const<'_>, 40);
+static_assert_size!(Const<'_>, 48);
 
 impl<'tcx> Const<'tcx> {
     #[inline]
     pub fn from_scalar(tcx: TyCtxt<'tcx>, val: Scalar, ty: Ty<'tcx>) -> &'tcx Self {
         tcx.mk_const(Self {
-            val: ConstValue::Scalar(val),
+            val: ConstKind::Value(ConstValue::Scalar(val)),
             ty,
         })
     }
@@ -2317,7 +2317,7 @@ impl<'tcx> Const<'tcx> {
         // FIXME(const_generics): this doesn't work right now,
         // because it tries to relate an `Infer` to a `Param`.
         match self.val {
-            ConstValue::Unevaluated(did, substs) => {
+            ConstKind::Unevaluated(did, substs) => {
                 // if `substs` has no unresolved components, use and empty param_env
                 let (param_env, substs) = param_env.with_reveal_all().and(substs).into_parts();
                 // try to resolve e.g. associated constants to their definition on an impl
@@ -2363,6 +2363,54 @@ impl<'tcx> Const<'tcx> {
 
 impl<'tcx> rustc_serialize::UseSpecializedDecodable for &'tcx Const<'tcx> {}
 
+/// Represents a constant in Rust.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord,
+         RustcEncodable, RustcDecodable, Hash, HashStable)]
+pub enum ConstKind<'tcx> {
+    /// A const generic parameter.
+    Param(ParamConst),
+
+    /// Infer the value of the const.
+    Infer(InferConst<'tcx>),
+
+    /// Bound const variable, used only when preparing a trait query.
+    Bound(DebruijnIndex, BoundVar),
+
+    /// A placeholder const - universally quantified higher-ranked const.
+    Placeholder(ty::PlaceholderConst),
+
+    /// Used in the HIR by using `Unevaluated` everywhere and later normalizing to one of the other
+    /// variants when the code is monomorphic enough for that.
+    Unevaluated(DefId, SubstsRef<'tcx>),
+
+    /// Used to hold computed value.
+    Value(ConstValue<'tcx>),
+}
+
+#[cfg(target_arch = "x86_64")]
+static_assert_size!(ConstKind<'_>, 40);
+
+impl<'tcx> ConstKind<'tcx> {
+    #[inline]
+    pub fn try_to_scalar(&self) -> Option<Scalar> {
+        if let ConstKind::Value(val) = self {
+            val.try_to_scalar()
+        } else {
+            None
+        }
+    }
+
+    #[inline]
+    pub fn try_to_bits(&self, size: ty::layout::Size) -> Option<u128> {
+        self.try_to_scalar()?.to_bits(size).ok()
+    }
+
+    //#[inline]
+    //pub fn try_to_ptr(&self) -> Option<mir::interpret::Pointer> {
+    //    self.try_to_scalar()?.to_ptr().ok()
+    //}
+}
+
 /// An inference variable for a const, for use in const generics.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd,
          Ord, RustcEncodable, RustcDecodable, Hash, HashStable)]
diff --git a/src/librustc/ty/subst.rs b/src/librustc/ty/subst.rs
index 29721979099..8ba8622704a 100644
--- a/src/librustc/ty/subst.rs
+++ b/src/librustc/ty/subst.rs
@@ -4,7 +4,6 @@ use crate::hir::def_id::DefId;
 use crate::infer::canonical::Canonical;
 use crate::ty::{self, Lift, List, Ty, TyCtxt, ParamConst};
 use crate::ty::fold::{TypeFoldable, TypeFolder, TypeVisitor};
-use crate::mir::interpret::ConstValue;
 use crate::ty::sty::{ClosureSubsts, GeneratorSubsts};
 
 use rustc_serialize::{self, Encodable, Encoder, Decodable, Decoder};
@@ -234,7 +233,7 @@ impl<'a, 'tcx> InternalSubsts<'tcx> {
 
                 ty::GenericParamDefKind::Const => {
                     tcx.mk_const(ty::Const {
-                        val: ConstValue::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
+                        val: ty::ConstKind::Bound(ty::INNERMOST, ty::BoundVar::from(param.index)),
                         ty: tcx.type_of(def_id),
                     }).into()
                 }
@@ -578,7 +577,7 @@ impl<'a, 'tcx> TypeFolder<'tcx> for SubstFolder<'a, 'tcx> {
             return c;
         }
 
-        if let ConstValue::Param(p) = c.val {
+        if let ty::ConstKind::Param(p) = c.val {
             self.const_for_param(p, c)
         } else {
             c.super_fold_with(self)
diff --git a/src/librustc/ty/util.rs b/src/librustc/ty/util.rs
index d46320abff2..76afba220ce 100644
--- a/src/librustc/ty/util.rs
+++ b/src/librustc/ty/util.rs
@@ -12,7 +12,6 @@ use crate::ty::subst::{Subst, InternalSubsts, SubstsRef, GenericArgKind};
 use crate::ty::query::TyCtxtAt;
 use crate::ty::TyKind::*;
 use crate::ty::layout::{Integer, IntegerExt};
-use crate::mir::interpret::ConstValue;
 use crate::util::common::ErrorReported;
 use crate::middle::lang_items;
 
@@ -566,7 +565,7 @@ impl<'tcx> TyCtxt<'tcx> {
                         !impl_generics.type_param(pt, self).pure_wrt_drop
                     }
                     GenericArgKind::Const(&ty::Const {
-                        val: ConstValue::Param(ref pc),
+                        val: ty::ConstKind::Param(ref pc),
                         ..
                     }) => {
                         !impl_generics.const_param(pc, self).pure_wrt_drop
diff --git a/src/librustc/ty/walk.rs b/src/librustc/ty/walk.rs
index f5b1902e3cc..8d0f9a47162 100644
--- a/src/librustc/ty/walk.rs
+++ b/src/librustc/ty/walk.rs
@@ -3,7 +3,6 @@
 
 use crate::ty::{self, Ty};
 use smallvec::{self, SmallVec};
-use crate::mir::interpret::ConstValue;
 
 // The TypeWalker's stack is hot enough that it's worth going to some effort to
 // avoid heap allocations.
@@ -75,7 +74,7 @@ fn push_subtypes<'tcx>(stack: &mut TypeWalkerStack<'tcx>, parent_ty: Ty<'tcx>) {
         ty::Placeholder(..) | ty::Bound(..) | ty::Foreign(..) => {
         }
         ty::Array(ty, len) => {
-            if let ConstValue::Unevaluated(_, substs) = len.val {
+            if let ty::ConstKind::Unevaluated(_, substs) = len.val {
                 stack.extend(substs.types().rev());
             }
             stack.push(len.ty);
diff --git a/src/librustc/ty/wf.rs b/src/librustc/ty/wf.rs
index f9e7a8030a6..aa0456b78af 100644
--- a/src/librustc/ty/wf.rs
+++ b/src/librustc/ty/wf.rs
@@ -8,7 +8,6 @@ use std::iter::once;
 use syntax::symbol::{kw, Ident};
 use syntax_pos::Span;
 use crate::middle::lang_items;
-use crate::mir::interpret::ConstValue;
 
 /// Returns the set of obligations needed to make `ty` well-formed.
 /// If `ty` contains unresolved inference variables, this may include
@@ -363,7 +362,7 @@ impl<'a, 'tcx> WfPredicates<'a, 'tcx> {
     /// Pushes the obligations required for an array length to be WF
     /// into `self.out`.
     fn compute_array_len(&mut self, constant: ty::Const<'tcx>) {
-        if let ConstValue::Unevaluated(def_id, substs) = constant.val {
+        if let ty::ConstKind::Unevaluated(def_id, substs) = constant.val {
             let obligations = self.nominal_obligations(def_id, substs);
             self.out.extend(obligations);