Add bound_const_param_default

Author: jackh726

Diff for: compiler/rustc_middle/src/ty/generics.rs

@@ -85,10 +85,10 @@ impl GenericParamDef {
     ) -> Option<EarlyBinder<ty::GenericArg<'tcx>>> {
         match self.kind {
             GenericParamDefKind::Type { has_default, .. } if has_default => {
-                Some(EarlyBinder(tcx.type_of(self.def_id).into()))
+                Some(tcx.bound_type_of(self.def_id).map_bound(|t| t.into()))
             }
             GenericParamDefKind::Const { has_default } if has_default => {
-                Some(EarlyBinder(tcx.const_param_default(self.def_id).into()))
+                Some(tcx.bound_const_param_default(self.def_id).map_bound(|c| c.into()))
             }
             _ => None,
         }

Diff for: compiler/rustc_middle/src/ty/util.rs

@@ -676,6 +676,10 @@ impl<'tcx> TyCtxt<'tcx> {
     ) -> ty::EarlyBinder<&'tcx ty::List<ty::Predicate<'tcx>>> {
         ty::EarlyBinder(self.item_bounds(def_id))
     }
+
+    pub fn bound_const_param_default(self, def_id: DefId) -> ty::EarlyBinder<ty::Const<'tcx>> {
+        ty::EarlyBinder(self.const_param_default(def_id))
+    }
 }
 
 struct OpaqueTypeExpander<'tcx> {

Diff for: compiler/rustc_typeck/src/astconv/mod.rs

@@ -550,7 +550,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     GenericParamDefKind::Const { has_default } => {
                         let ty = tcx.at(self.span).type_of(param.def_id);
                         if !infer_args && has_default {
-                            EarlyBinder(tcx.const_param_default(param.def_id))
+                            tcx.bound_const_param_default(param.def_id)
                                 .subst(tcx, substs.unwrap())
                                 .into()
                         } else {

Diff for: compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -1426,7 +1426,7 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                     }
                     GenericParamDefKind::Const { has_default } => {
                         if !infer_args && has_default {
-                            EarlyBinder(tcx.const_param_default(param.def_id))
+                            tcx.bound_const_param_default(param.def_id)
                                 .subst(tcx, substs.unwrap())
                                 .into()
                         } else {

Diff for: compiler/rustc_typeck/src/check/method/probe.rs

@@ -21,9 +21,7 @@ use rustc_middle::middle::stability;
 use rustc_middle::ty::fast_reject::{simplify_type, TreatParams};
 use rustc_middle::ty::subst::{InternalSubsts, Subst, SubstsRef};
 use rustc_middle::ty::GenericParamDefKind;
-use rustc_middle::ty::{
-    self, EarlyBinder, ParamEnvAnd, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeVisitable,
-};
+use rustc_middle::ty::{self, ParamEnvAnd, ToPredicate, Ty, TyCtxt, TypeFoldable, TypeVisitable};
 use rustc_session::lint;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::lev_distance::{
@@ -713,7 +711,7 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
             }
 
             let (impl_ty, impl_substs) = self.impl_ty_and_substs(impl_def_id);
-            let impl_ty = EarlyBinder(impl_ty).subst(self.tcx, impl_substs);
+            let impl_ty = impl_ty.subst(self.tcx, impl_substs);
 
             debug!("impl_ty: {:?}", impl_ty);
 
@@ -1812,8 +1810,11 @@ impl<'a, 'tcx> ProbeContext<'a, 'tcx> {
     }
 
     /// Gets the type of an impl and generate substitutions with placeholders.
-    fn impl_ty_and_substs(&self, impl_def_id: DefId) -> (Ty<'tcx>, SubstsRef<'tcx>) {
-        (self.tcx.type_of(impl_def_id), self.fresh_item_substs(impl_def_id))
+    fn impl_ty_and_substs(
+        &self,
+        impl_def_id: DefId,
+    ) -> (ty::EarlyBinder<Ty<'tcx>>, SubstsRef<'tcx>) {
+        (self.tcx.bound_type_of(impl_def_id), self.fresh_item_substs(impl_def_id))
     }
 
     fn fresh_item_substs(&self, def_id: DefId) -> SubstsRef<'tcx> {