1 files changed, 11 insertions, 8 deletions

diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index 527ec9f6e..bcedae233 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -1,10 +1,10 @@
 use crate::middle::resolve_bound_vars as rbv;
 use crate::mir::interpret::LitToConstInput;
-use crate::ty::{self, DefIdTree, InternalSubsts, ParamEnv, ParamEnvAnd, Ty, TyCtxt};
+use crate::ty::{self, InternalSubsts, ParamEnv, ParamEnvAnd, Ty, TyCtxt};
 use rustc_data_structures::intern::Interned;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
-use rustc_hir::def_id::{DefId, LocalDefId};
+use rustc_hir::def_id::LocalDefId;
 use rustc_macros::HashStable;
 use std::fmt;
 
@@ -83,7 +83,7 @@ impl<'tcx> Const<'tcx> {
             None => tcx.mk_const(
                 ty::UnevaluatedConst {
                     def: def.to_global(),
-                    substs: InternalSubsts::identity_for_item(tcx, def.did.to_def_id()),
+                    substs: InternalSubsts::identity_for_item(tcx, def.did),
                 },
                 ty,
             ),
@@ -135,6 +135,9 @@ impl<'tcx> Const<'tcx> {
                 _,
                 &hir::Path { res: Res::Def(DefKind::ConstParam, def_id), .. },
             )) => {
+                // Use the type from the param's definition, since we can resolve it,
+                // not the expected parameter type from WithOptConstParam.
+                let param_ty = tcx.type_of(def_id).subst_identity();
                 match tcx.named_bound_var(expr.hir_id) {
                     Some(rbv::ResolvedArg::EarlyBound(_)) => {
                         // Find the name and index of the const parameter by indexing the generics of
@@ -143,14 +146,14 @@ 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::ParamConst::new(index, name), ty))
+                        Some(tcx.mk_const(ty::ParamConst::new(index, name), param_ty))
                     }
                     Some(rbv::ResolvedArg::LateBound(debruijn, index, _)) => Some(tcx.mk_const(
                         ty::ConstKind::Bound(debruijn, ty::BoundVar::from_u32(index)),
-                        ty,
+                        param_ty,
                     )),
                     Some(rbv::ResolvedArg::Error(guar)) => {
-                        Some(tcx.const_error_with_guaranteed(ty, guar))
+                        Some(tcx.const_error_with_guaranteed(param_ty, guar))
                     }
                     arg => bug!("unexpected bound var resolution for {:?}: {arg:?}", expr.hir_id),
                 }
@@ -262,8 +265,8 @@ impl<'tcx> Const<'tcx> {
     }
 }
 
-pub fn const_param_default(tcx: TyCtxt<'_>, def_id: DefId) -> ty::EarlyBinder<Const<'_>> {
-    let default_def_id = match tcx.hir().get_by_def_id(def_id.expect_local()) {
+pub fn const_param_default(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<Const<'_>> {
+    let default_def_id = match tcx.hir().get_by_def_id(def_id) {
         hir::Node::GenericParam(hir::GenericParam {
             kind: hir::GenericParamKind::Const { default: Some(ac), .. },
             ..