Simplify calls to tcx.mk_const

`mk_const(ty::ConstKind::X(...), ty)` can now be simplified to
`mk_cosnt(...,                   ty)`.

I searched with the following regex: \mk_const\([\n\s]*(ty::)?ConstKind\
I've left `ty::ConstKind::{Bound, Error}` as-is, they seem clearer this
way.

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()
             }
         }
     }

compiler/rustc_infer/src/infer/combine.rs

@@ -765,10 +765,7 @@ impl<'tcx> TypeRelation<'tcx> for Generalizer<'_, 'tcx> {
                     substs,
                     substs,
                 )?;
-                Ok(self.tcx().mk_const(
+                Ok(self.tcx().mk_const(ty::UnevaluatedConst { def, substs }, c.ty()))
-                    ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }),
-                    c.ty(),
-                ))
             }
             _ => relate::super_relate_consts(self, c, c),
         }
@@ -988,10 +985,7 @@ impl<'tcx> TypeRelation<'tcx> for ConstInferUnifier<'_, 'tcx> {
                     substs,
                 )?;
 
-                Ok(self.tcx().mk_const(
+                Ok(self.tcx().mk_const(ty::UnevaluatedConst { def, substs }, c.ty()))
-                    ty::ConstKind::Unevaluated(ty::UnevaluatedConst { def, substs }),
-                    c.ty(),
-                ))
             }
             _ => relate::super_relate_consts(self, c, c),
         }

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(
+                self.tcx
-                    ty::ConstKind::Placeholder(ty::PlaceholderConst {
+                    .mk_const(ty::PlaceholderConst { universe: next_universe, name: bound_var }, ty)
-                        universe: next_universe,
-                        name: bound_var,
-                    }),
-                    ty,
-                )
             },
         };
 

compiler/rustc_infer/src/infer/mod.rs

@@ -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()

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 =
+                let ty_const = tcx.mk_const(ty::ParamConst::new(index, name), ty);
-                    tcx.mk_const(ty::ConstKind::Param(ty::ParamConst::new(index, name)), ty);
                 debug!(?ty_const);
 
                 return Self::Ty(ty_const);

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,
             ),
         }
@@ -134,7 +134,7 @@ 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,
         }
@@ -143,7 +143,7 @@ impl<'tcx> Const<'tcx> {
     /// 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)
+        tcx.mk_const(val, ty)
     }
 
     /// Panics if self.kind != ty::ConstKind::Value

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(
+            return Ok(tcx.mk_const(ty::UnevaluatedConst { def: au.def, substs }, a.ty()));
-                ty::ConstKind::Unevaluated(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.

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 }

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),
         }

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
+            let field_consts =
-                .iter()
+                branches.iter().map(|b| tcx.mk_const(*b, *inner_ty)).collect::<Vec<_>>();
-                .map(|b| tcx.mk_const(ty::ConstKind::Value(*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)| {
+                .map(|(elem_ty, elem_valtree)| tcx.mk_const(*elem_valtree, elem_ty))
-                    tcx.mk_const(ty::ConstKind::Value(*elem_valtree), elem_ty)
-                })
                 .collect::<Vec<_>>();
 
             (fields, None)
@@ -137,9 +133,9 @@ fn recurse_build<'tcx>(
         }
         &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];