Auto merge of #105012 - WaffleLapkin:into, r=oli-obk

Make `tcx.mk_const` more permissive wrt `kind` argument (`impl Into`)

r? `@oli-obk` you've asked for this >:)

18 files changed, 64 insertions, 98 deletions

diff --git a/compiler/rustc_infer/src/infer/canonical/mod.rs b/compiler/rustc_infer/src/infer/canonical/mod.rs
index 0794792d8cb..ba0ce16bb81 100644
--- a/compiler/rustc_infer/src/infer/canonical/mod.rs
+++ b/compiler/rustc_infer/src/infer/canonical/mod.rs
@@ -147,7 +147,7 @@ impl<'tcx> InferCtxt<'tcx> {
             CanonicalVarKind::PlaceholderConst(ty::PlaceholderConst { universe, name }, ty) => {
                 let universe_mapped = universe_map(universe);
                 let placeholder_mapped = ty::PlaceholderConst { universe: universe_mapped, name };
-                self.tcx.mk_const(ty::ConstKind::Placeholder(placeholder_mapped), ty).into()
+                self.tcx.mk_const(placeholder_mapped, ty).into()
             }
         }
     }
diff --git a/compiler/rustc_infer/src/infer/combine.rs b/compiler/rustc_infer/src/infer/combine.rs
index eec938cefbb..cf895ed0d3e 100644
--- a/compiler/rustc_infer/src/infer/combine.rs
+++ b/compiler/rustc_infer/src/infer/combine.rs
@@ -753,7 +753,7 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                                 origin: var_value.origin,
                                 val: ConstVariableValue::Unknown { universe: self.for_universe },
                             });
-                            Ok(self.tcx().mk_const_var(new_var_id, c.ty()))
+                            Ok(self.tcx().mk_const(new_var_id, c.ty()))
                         }
                     }
                 }
@@ -765,10 +765,7 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                     substs,
                     substs,
                 )?;
-                Ok(self.tcx().mk_const(
-                    ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }),
-                    c.ty(),
-                ))
+                Ok(self.tcx().mk_const(ty::UnevaluatedConst { def, substs }, c.ty()))
             }
             _ => relate::super_relate_consts(self, c, c),
         }
@@ -975,7 +972,7 @@ impl<'tcx> TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
                                         },
                                     },
                                 );
-                            Ok(self.tcx().mk_const_var(new_var_id, c.ty()))
+                            Ok(self.tcx().mk_const(new_var_id, c.ty()))
                         }
                     }
                 }
@@ -988,10 +985,7 @@ impl<'tcx> TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
                     substs,
                 )?;
 
-                Ok(self.tcx().mk_const(
-                    ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }),
-                    c.ty(),
-                ))
+                Ok(self.tcx().mk_const(ty::UnevaluatedConst { def, substs }, c.ty()))
             }
             _ => relate::super_relate_consts(self, c, c),
         }
diff --git a/compiler/rustc_infer/src/infer/freshen.rs b/compiler/rustc_infer/src/infer/freshen.rs
index 27a94ec5e30..f6946929bd2 100644
--- a/compiler/rustc_infer/src/infer/freshen.rs
+++ b/compiler/rustc_infer/src/infer/freshen.rs
@@ -102,7 +102,7 @@ impl<'a, 'tcx> TypeFreshener<'a, 'tcx> {
             Entry::Vacant(entry) => {
                 let index = self.const_freshen_count;
                 self.const_freshen_count += 1;
-                let ct = self.infcx.tcx.mk_const_infer(freshener(index), ty);
+                let ct = self.infcx.tcx.mk_const(freshener(index), ty);
                 entry.insert(ct);
                 ct
             }
diff --git a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
index d739323de77..817ae10c760 100644
--- a/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
+++ b/compiler/rustc_infer/src/infer/higher_ranked/mod.rs
@@ -94,13 +94,8 @@ impl<'tcx> InferCtxt<'tcx> {
                 }))
             },
             consts: &mut |bound_var: ty::BoundVar, ty| {
-                self.tcx.mk_const(
-                    ty::ConstKind::Placeholder(ty::PlaceholderConst {
-                        universe: next_universe,
-                        name: bound_var,
-                    }),
-                    ty,
-                )
+                self.tcx
+                    .mk_const(ty::PlaceholderConst { universe: next_universe, name: bound_var }, ty)
             },
         };
 
diff --git a/compiler/rustc_infer/src/infer/mod.rs b/compiler/rustc_infer/src/infer/mod.rs
index cda9299dcb6..2bcb47cc383 100644
--- a/compiler/rustc_infer/src/infer/mod.rs
+++ b/compiler/rustc_infer/src/infer/mod.rs
@@ -1065,7 +1065,7 @@ impl<'tcx> InferCtxt<'tcx> {
     }
 
     pub fn next_const_var(&self, ty: Ty<'tcx>, origin: ConstVariableOrigin) -> ty::Const<'tcx> {
-        self.tcx.mk_const_var(self.next_const_var_id(origin), ty)
+        self.tcx.mk_const(self.next_const_var_id(origin), ty)
     }
 
     pub fn next_const_var_in_universe(
@@ -1079,7 +1079,7 @@ impl<'tcx> InferCtxt<'tcx> {
             .borrow_mut()
             .const_unification_table()
             .new_key(ConstVarValue { origin, val: ConstVariableValue::Unknown { universe } });
-        self.tcx.mk_const_var(vid, ty)
+        self.tcx.mk_const(vid, ty)
     }
 
     pub fn next_const_var_id(&self, origin: ConstVariableOrigin) -> ConstVid<'tcx> {
@@ -1195,7 +1195,7 @@ impl<'tcx> InferCtxt<'tcx> {
                         origin,
                         val: ConstVariableValue::Unknown { universe: self.universe() },
                     });
-                self.tcx.mk_const_var(const_var_id, self.tcx.type_of(param.def_id)).into()
+                self.tcx.mk_const(const_var_id, self.tcx.type_of(param.def_id)).into()
             }
         }
     }
@@ -1580,7 +1580,7 @@ impl<'tcx> InferCtxt<'tcx> {
         span: Option<Span>,
     ) -> Result<ty::Const<'tcx>, ErrorHandled> {
         match self.const_eval_resolve(param_env, unevaluated, span) {
-            Ok(Some(val)) => Ok(ty::Const::from_value(self.tcx, val, ty)),
+            Ok(Some(val)) => Ok(self.tcx.mk_const(val, ty)),
             Ok(None) => {
                 let tcx = self.tcx;
                 let def_id = unevaluated.def.did;
@@ -2049,10 +2049,10 @@ fn replace_param_and_infer_substs_with_placeholder<'tcx>(
                     bug!("const `{ct}`'s type should not reference params or types");
                 }
                 tcx.mk_const(
-                    ty::ConstKind::Placeholder(ty::PlaceholderConst {
+                    ty::PlaceholderConst {
                         universe: ty::UniverseIndex::ROOT,
                         name: ty::BoundVar::from_usize(idx),
-                    }),
+                    },
                     ty,
                 )
                 .into()
diff --git a/compiler/rustc_infer/src/infer/nll_relate/mod.rs b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
index 4f8460955c3..f6bc4db0d59 100644
--- a/compiler/rustc_infer/src/infer/nll_relate/mod.rs
+++ b/compiler/rustc_infer/src/infer/nll_relate/mod.rs
@@ -1087,7 +1087,7 @@ where
                             origin: var_value.origin,
                             val: ConstVariableValue::Unknown { universe: self.universe },
                         });
-                        Ok(self.tcx().mk_const_var(new_var_id, a.ty()))
+                        Ok(self.tcx().mk_const(new_var_id, a.ty()))
                     }
                 }
             }
diff --git a/compiler/rustc_middle/Cargo.toml b/compiler/rustc_middle/Cargo.toml
index fc1167c105a..cf1ab47de86 100644
--- a/compiler/rustc_middle/Cargo.toml
+++ b/compiler/rustc_middle/Cargo.toml
@@ -8,6 +8,7 @@ edition = "2021"
 [dependencies]
 bitflags = "1.2.1"
 chalk-ir = "0.87.0"
+derive_more = "0.99.17"
 either = "1.5.0"
 gsgdt = "0.1.2"
 polonius-engine = "0.13.0"
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index 364c1b375ae..20dde64e51b 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -2527,8 +2527,7 @@ impl<'tcx> ConstantKind<'tcx> {
                 let generics = tcx.generics_of(item_def_id);
                 let index = generics.param_def_id_to_index[&def_id];
                 let name = tcx.item_name(def_id);
-                let ty_const =
-                    tcx.mk_const(ty::ConstKind::Param(ty::ParamConst::new(index, name)), ty);
+                let ty_const = tcx.mk_const(ty::ParamConst::new(index, name), ty);
                 debug!(?ty_const);
 
                 return Self::Ty(ty_const);
diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index 9a58a196ed7..c2be08e497e 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -76,10 +76,10 @@ impl<'tcx> Const<'tcx> {
         match Self::try_eval_lit_or_param(tcx, ty, expr) {
             Some(v) => v,
             None => tcx.mk_const(
-                ty::ConstKind::Unevaluated(ty::UnevaluatedConst {
+                ty::UnevaluatedConst {
                     def: def.to_global(),
                     substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
-                }),
+                },
                 ty,
             ),
         }
@@ -134,18 +134,12 @@ impl<'tcx> Const<'tcx> {
                 let generics = tcx.generics_of(item_def_id);
                 let index = generics.param_def_id_to_index[&def_id];
                 let name = tcx.item_name(def_id);
-                Some(tcx.mk_const(ty::ConstKind::Param(ty::ParamConst::new(index, name)), ty))
+                Some(tcx.mk_const(ty::ParamConst::new(index, name), ty))
             }
             _ => None,
         }
     }
 
-    /// Interns the given value as a constant.
-    #[inline]
-    pub fn from_value(tcx: TyCtxt<'tcx>, val: ty::ValTree<'tcx>, ty: Ty<'tcx>) -> Self {
-        tcx.mk_const(ConstKind::Value(val), ty)
-    }
-
     /// Panics if self.kind != ty::ConstKind::Value
     pub fn to_valtree(self) -> ty::ValTree<'tcx> {
         match self.kind() {
@@ -154,11 +148,6 @@ impl<'tcx> Const<'tcx> {
         }
     }
 
-    pub fn from_scalar_int(tcx: TyCtxt<'tcx>, i: ScalarInt, ty: Ty<'tcx>) -> Self {
-        let valtree = ty::ValTree::from_scalar_int(i);
-        Self::from_value(tcx, valtree, ty)
-    }
-
     #[inline]
     /// Creates a constant with the given integer value and interns it.
     pub fn from_bits(tcx: TyCtxt<'tcx>, bits: u128, ty: ParamEnvAnd<'tcx, Ty<'tcx>>) -> Self {
@@ -166,14 +155,16 @@ impl<'tcx> Const<'tcx> {
             .layout_of(ty)
             .unwrap_or_else(|e| panic!("could not compute layout for {:?}: {:?}", ty, e))
             .size;
-        Self::from_scalar_int(tcx, ScalarInt::try_from_uint(bits, size).unwrap(), ty.value)
+        tcx.mk_const(
+            ty::ValTree::from_scalar_int(ScalarInt::try_from_uint(bits, size).unwrap()),
+            ty.value,
+        )
     }
 
     #[inline]
     /// Creates an interned zst constant.
     pub fn zero_sized(tcx: TyCtxt<'tcx>, ty: Ty<'tcx>) -> Self {
-        let valtree = ty::ValTree::zst();
-        Self::from_value(tcx, valtree, ty)
+        tcx.mk_const(ty::ValTree::zst(), ty)
     }
 
     #[inline]
@@ -220,7 +211,7 @@ impl<'tcx> Const<'tcx> {
     pub fn eval(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Const<'tcx> {
         if let Some(val) = self.kind().try_eval_for_typeck(tcx, param_env) {
             match val {
-                Ok(val) => Const::from_value(tcx, val, self.ty()),
+                Ok(val) => tcx.mk_const(val, self.ty()),
                 Err(guar) => tcx.const_error_with_guaranteed(self.ty(), guar),
             }
         } else {
diff --git a/compiler/rustc_middle/src/ty/consts/kind.rs b/compiler/rustc_middle/src/ty/consts/kind.rs
index de63dae8a3d..becc2b805dd 100644
--- a/compiler/rustc_middle/src/ty/consts/kind.rs
+++ b/compiler/rustc_middle/src/ty/consts/kind.rs
@@ -49,6 +49,7 @@ impl<'tcx> UnevaluatedConst<'tcx> {
 /// Represents a constant in Rust.
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, TyEncodable, TyDecodable)]
 #[derive(Hash, HashStable, TypeFoldable, TypeVisitable)]
+#[derive(derive_more::From)]
 pub enum ConstKind<'tcx> {
     /// A const generic parameter.
     Param(ty::ParamConst),
@@ -71,12 +72,19 @@ pub enum ConstKind<'tcx> {
 
     /// A placeholder for a const which could not be computed; this is
     /// propagated to avoid useless error messages.
+    #[from(ignore)]
     Error(ErrorGuaranteed),
 
     /// Expr which contains an expression which has partially evaluated items.
     Expr(Expr<'tcx>),
 }
 
+impl<'tcx> From<ty::ConstVid<'tcx>> for ConstKind<'tcx> {
+    fn from(const_vid: ty::ConstVid<'tcx>) -> Self {
+        InferConst::Var(const_vid).into()
+    }
+}
+
 #[derive(Copy, Clone, Debug, Eq, PartialEq, PartialOrd, Ord, Hash)]
 #[derive(HashStable, TyEncodable, TyDecodable, TypeVisitable, TypeFoldable)]
 pub enum Expr<'tcx> {
diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index e802c71c64b..3590aae51c3 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -17,8 +17,8 @@ use crate::traits;
 use crate::ty::query::{self, TyCtxtAt};
 use crate::ty::{
     self, AdtDef, AdtDefData, AdtKind, Binder, BindingMode, BoundVar, CanonicalPolyFnSig,
-    ClosureSizeProfileData, Const, ConstS, ConstVid, DefIdTree, FloatTy, FloatVar, FloatVid,
-    GenericParamDefKind, InferConst, InferTy, IntTy, IntVar, IntVid, List, ParamConst, ParamTy,
+    ClosureSizeProfileData, Const, ConstS, DefIdTree, FloatTy, FloatVar, FloatVid,
+    GenericParamDefKind, InferTy, IntTy, IntVar, IntVid, List, ParamConst, ParamTy,
     PolyExistentialPredicate, PolyFnSig, Predicate, PredicateKind, PredicateS, ProjectionTy,
     Region, RegionKind, ReprOptions, TraitObjectVisitor, Ty, TyKind, TyS, TyVar, TyVid, TypeAndMut,
     UintTy, Visibility,
@@ -2604,13 +2604,8 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     #[inline]
-    pub fn mk_const(self, kind: ty::ConstKind<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
-        self.mk_const_internal(ty::ConstS { kind, ty })
-    }
-
-    #[inline]
-    pub fn mk_const_var(self, v: ConstVid<'tcx>, ty: Ty<'tcx>) -> Const<'tcx> {
-        self.mk_const(ty::ConstKind::Infer(InferConst::Var(v)), ty)
+    pub fn mk_const(self, kind: impl Into<ty::ConstKind<'tcx>>, ty: Ty<'tcx>) -> Const<'tcx> {
+        self.mk_const_internal(ty::ConstS { kind: kind.into(), ty })
     }
 
     #[inline]
@@ -2629,29 +2624,22 @@ impl<'tcx> TyCtxt<'tcx> {
     }
 
     #[inline]
-    pub fn mk_const_infer(self, ic: InferConst<'tcx>, ty: Ty<'tcx>) -> ty::Const<'tcx> {
-        self.mk_const(ty::ConstKind::Infer(ic), ty)
-    }
-
-    #[inline]
     pub fn mk_ty_param(self, index: u32, name: Symbol) -> Ty<'tcx> {
         self.mk_ty(Param(ParamTy { index, name }))
     }
 
-    #[inline]
-    pub fn mk_const_param(self, index: u32, name: Symbol, ty: Ty<'tcx>) -> Const<'tcx> {
-        self.mk_const(ty::ConstKind::Param(ParamConst { index, name }), ty)
-    }
-
     pub fn mk_param_from_def(self, param: &ty::GenericParamDef) -> GenericArg<'tcx> {
         match param.kind {
             GenericParamDefKind::Lifetime => {
                 self.mk_region(ty::ReEarlyBound(param.to_early_bound_region_data())).into()
             }
             GenericParamDefKind::Type { .. } => self.mk_ty_param(param.index, param.name).into(),
-            GenericParamDefKind::Const { .. } => {
-                self.mk_const_param(param.index, param.name, self.type_of(param.def_id)).into()
-            }
+            GenericParamDefKind::Const { .. } => self
+                .mk_const(
+                    ParamConst { index: param.index, name: param.name },
+                    self.type_of(param.def_id),
+                )
+                .into(),
         }
     }
 
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index bd17f7d34ad..5303341ba44 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -1468,8 +1468,7 @@ pub trait PrettyPrinter<'tcx>:
             }
             // Aggregates, printed as array/tuple/struct/variant construction syntax.
             (ty::ValTree::Branch(_), ty::Array(..) | ty::Tuple(..) | ty::Adt(..)) => {
-                let contents =
-                    self.tcx().destructure_const(ty::Const::from_value(self.tcx(), valtree, ty));
+                let contents = self.tcx().destructure_const(self.tcx().mk_const(valtree, ty));
                 let fields = contents.fields.iter().copied();
                 match *ty.kind() {
                     ty::Array(..) => {
diff --git a/compiler/rustc_middle/src/ty/relate.rs b/compiler/rustc_middle/src/ty/relate.rs
index e6340040e9c..c759fb6d5e4 100644
--- a/compiler/rustc_middle/src/ty/relate.rs
+++ b/compiler/rustc_middle/src/ty/relate.rs
@@ -663,10 +663,7 @@ pub fn super_relate_consts<'tcx, R: TypeRelation<'tcx>>(
                 au.substs,
                 bu.substs,
             )?;
-            return Ok(tcx.mk_const(
-                ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def: au.def, substs }),
-                a.ty(),
-            ));
+            return Ok(tcx.mk_const(ty::UnevaluatedConst { def: au.def, substs }, a.ty()));
         }
         // Before calling relate on exprs, it is necessary to ensure that the nested consts
         // have identical types.
diff --git a/compiler/rustc_mir_build/src/build/expr/as_constant.rs b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
index 7d8a940bde5..32c0207cb68 100644
--- a/compiler/rustc_mir_build/src/build/expr/as_constant.rs
+++ b/compiler/rustc_mir_build/src/build/expr/as_constant.rs
@@ -77,7 +77,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
                 Constant { user_ty, span, literal }
             }
             ExprKind::ConstParam { param, def_id: _ } => {
-                let const_param = tcx.mk_const(ty::ConstKind::Param(param), expr.ty);
+                let const_param = tcx.mk_const(param, expr.ty);
                 let literal = ConstantKind::Ty(const_param);
 
                 Constant { user_ty: None, span, literal }
diff --git a/compiler/rustc_mir_build/src/thir/constant.rs b/compiler/rustc_mir_build/src/thir/constant.rs
index 85e8801bda3..a9ed945d4a1 100644
--- a/compiler/rustc_mir_build/src/thir/constant.rs
+++ b/compiler/rustc_mir_build/src/thir/constant.rs
@@ -61,5 +61,5 @@ pub(crate) fn lit_to_const<'tcx>(
         _ => return Err(LitToConstError::TypeError),
     };
 
-    Ok(ty::Const::from_value(tcx, valtree, ty))
+    Ok(tcx.mk_const(valtree, ty))
 }
diff --git a/compiler/rustc_trait_selection/src/traits/auto_trait.rs b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
index 88a13f75c7e..8e04da4f9be 100644
--- a/compiler/rustc_trait_selection/src/traits/auto_trait.rs
+++ b/compiler/rustc_trait_selection/src/traits/auto_trait.rs
@@ -799,9 +799,7 @@ impl<'tcx> AutoTraitFinder<'tcx> {
                                 unevaluated,
                                 Some(obligation.cause.span),
                             ) {
-                                Ok(Some(valtree)) => {
-                                    Ok(ty::Const::from_value(selcx.tcx(), valtree, c.ty()))
-                                }
+                                Ok(Some(valtree)) => Ok(selcx.tcx().mk_const(valtree, c.ty())),
                                 Ok(None) => {
                                     let tcx = self.tcx;
                                     let def_id = unevaluated.def.did;
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 18f4379d8f8..e33e89e9c5c 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -818,7 +818,7 @@ impl<'tcx> TypeFolder<'tcx> for BoundVarReplacer<'_, 'tcx> {
                 let universe = self.universe_for(debruijn);
                 let p = ty::PlaceholderConst { universe, name: bound_const };
                 self.mapped_consts.insert(p, bound_const);
-                self.infcx.tcx.mk_const(ty::ConstKind::Placeholder(p), ct.ty())
+                self.infcx.tcx.mk_const(p, ct.ty())
             }
             _ => ct.super_fold_with(self),
         }
diff --git a/compiler/rustc_ty_utils/src/consts.rs b/compiler/rustc_ty_utils/src/consts.rs
index 2b7018bc9c3..f8ff31f971b 100644
--- a/compiler/rustc_ty_utils/src/consts.rs
+++ b/compiler/rustc_ty_utils/src/consts.rs
@@ -5,7 +5,7 @@ use rustc_middle::mir::interpret::{LitToConstError, LitToConstInput};
 use rustc_middle::thir::visit;
 use rustc_middle::thir::visit::Visitor;
 use rustc_middle::ty::abstract_const::CastKind;
-use rustc_middle::ty::{self, ConstKind, Expr, TyCtxt, TypeVisitable};
+use rustc_middle::ty::{self, Expr, TyCtxt, TypeVisitable};
 use rustc_middle::{mir, thir};
 use rustc_span::Span;
 use rustc_target::abi::VariantIdx;
@@ -32,10 +32,8 @@ pub(crate) fn destructure_const<'tcx>(
     let (fields, variant) = match const_.ty().kind() {
         ty::Array(inner_ty, _) | ty::Slice(inner_ty) => {
             // construct the consts for the elements of the array/slice
-            let field_consts = branches
-                .iter()
-                .map(|b| tcx.mk_const(ty::ConstKind::Value(*b), *inner_ty))
-                .collect::<Vec<_>>();
+            let field_consts =
+                branches.iter().map(|b| tcx.mk_const(*b, *inner_ty)).collect::<Vec<_>>();
             debug!(?field_consts);
 
             (field_consts, None)
@@ -53,7 +51,7 @@ pub(crate) fn destructure_const<'tcx>(
 
             for (field, field_valtree) in iter::zip(fields, branches) {
                 let field_ty = field.ty(tcx, substs);
-                let field_const = tcx.mk_const(ty::ConstKind::Value(*field_valtree), field_ty);
+                let field_const = tcx.mk_const(*field_valtree, field_ty);
                 field_consts.push(field_const);
             }
             debug!(?field_consts);
@@ -62,9 +60,7 @@ pub(crate) fn destructure_const<'tcx>(
         }
         ty::Tuple(elem_tys) => {
             let fields = iter::zip(*elem_tys, branches)
-                .map(|(elem_ty, elem_valtree)| {
-                    tcx.mk_const(ty::ConstKind::Value(*elem_valtree), elem_ty)
-                })
+                .map(|(elem_ty, elem_valtree)| tcx.mk_const(*elem_valtree, elem_ty))
                 .collect::<Vec<_>>();
 
             (fields, None)
@@ -129,17 +125,17 @@ fn recurse_build<'tcx>(
         }
         &ExprKind::NonHirLiteral { lit, user_ty: _ } => {
             let val = ty::ValTree::from_scalar_int(lit);
-            ty::Const::from_value(tcx, val, node.ty)
+            tcx.mk_const(val, node.ty)
         }
         &ExprKind::ZstLiteral { user_ty: _ } => {
             let val = ty::ValTree::zst();
-            ty::Const::from_value(tcx, val, node.ty)
+            tcx.mk_const(val, node.ty)
         }
         &ExprKind::NamedConst { def_id, substs, user_ty: _ } => {
             let uneval = ty::UnevaluatedConst::new(ty::WithOptConstParam::unknown(def_id), substs);
-            tcx.mk_const(ty::ConstKind::Unevaluated(uneval), node.ty)
+            tcx.mk_const(uneval, node.ty)
         }
-        ExprKind::ConstParam { param, .. } => tcx.mk_const(ty::ConstKind::Param(*param), node.ty),
+        ExprKind::ConstParam { param, .. } => tcx.mk_const(*param, node.ty),
 
         ExprKind::Call { fun, args, .. } => {
             let fun = recurse_build(tcx, body, *fun, root_span)?;
@@ -149,16 +145,16 @@ fn recurse_build<'tcx>(
                 new_args.push(recurse_build(tcx, body, id, root_span)?);
             }
             let new_args = tcx.mk_const_list(new_args.iter());
-            tcx.mk_const(ConstKind::Expr(Expr::FunctionCall(fun, new_args)), node.ty)
+            tcx.mk_const(Expr::FunctionCall(fun, new_args), node.ty)
         }
         &ExprKind::Binary { op, lhs, rhs } if check_binop(op) => {
             let lhs = recurse_build(tcx, body, lhs, root_span)?;
             let rhs = recurse_build(tcx, body, rhs, root_span)?;
-            tcx.mk_const(ConstKind::Expr(Expr::Binop(op, lhs, rhs)), node.ty)
+            tcx.mk_const(Expr::Binop(op, lhs, rhs), node.ty)
         }
         &ExprKind::Unary { op, arg } if check_unop(op) => {
             let arg = recurse_build(tcx, body, arg, root_span)?;
-            tcx.mk_const(ConstKind::Expr(Expr::UnOp(op, arg)), node.ty)
+            tcx.mk_const(Expr::UnOp(op, arg), node.ty)
         }
         // This is necessary so that the following compiles:
         //
@@ -179,11 +175,11 @@ fn recurse_build<'tcx>(
         // This is important so that `N as usize as usize` doesnt unify with `N as usize`. (untested)
         &ExprKind::Use { source } => {
             let arg = recurse_build(tcx, body, source, root_span)?;
-            tcx.mk_const(ConstKind::Expr(Expr::Cast(CastKind::Use, arg, node.ty)), node.ty)
+            tcx.mk_const(Expr::Cast(CastKind::Use, arg, node.ty), node.ty)
         }
         &ExprKind::Cast { source } => {
             let arg = recurse_build(tcx, body, source, root_span)?;
-            tcx.mk_const(ConstKind::Expr(Expr::Cast(CastKind::As, arg, node.ty)), node.ty)
+            tcx.mk_const(Expr::Cast(CastKind::As, arg, node.ty), node.ty)
         }
         ExprKind::Borrow { arg, .. } => {
             let arg_node = &body.exprs[*arg];