4 files changed, 13 insertions, 15 deletions
diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index 561653f3beb..6dab680c979 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -1,5 +1,5 @@
 use crate::hir::{ModuleItems, Owner};
-use crate::ty::TyCtxt;
+use crate::ty::{DefIdTree, TyCtxt};
 use rustc_ast as ast;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
@@ -545,13 +545,12 @@ impl<'hir> Map<'hir> {
         });
     }
 
-    pub fn ty_param_owner(self, id: HirId) -> LocalDefId {
-        match self.get(id) {
-            Node::Item(&Item { kind: ItemKind::Trait(..) | ItemKind::TraitAlias(..), .. }) => {
-                id.expect_owner()
-            }
-            Node::GenericParam(_) => self.get_parent_item(id),
-            _ => bug!("ty_param_owner: {} not a type parameter", self.node_to_string(id)),
+    pub fn ty_param_owner(self, def_id: LocalDefId) -> LocalDefId {
+        let def_kind = self.tcx.def_kind(def_id);
+        match def_kind {
+            DefKind::Trait | DefKind::TraitAlias => def_id,
+            DefKind::TyParam | DefKind::ConstParam => self.tcx.local_parent(def_id).unwrap(),
+            _ => bug!("ty_param_owner: {:?} is a {:?} not a type parameter", def_id, def_kind),
         }
     }
 
diff --git a/compiler/rustc_typeck/src/astconv/mod.rs b/compiler/rustc_typeck/src/astconv/mod.rs
index b6287031665..d46c4bdf98d 100644
--- a/compiler/rustc_typeck/src/astconv/mod.rs
+++ b/compiler/rustc_typeck/src/astconv/mod.rs
@@ -2265,11 +2265,11 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 assert_eq!(opt_self_ty, None);
                 self.prohibit_generics(path.segments);
 
-                let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
-                let item_id = tcx.hir().get_parent_node(hir_id);
-                let item_def_id = tcx.hir().local_def_id(item_id);
+                let def_id = def_id.expect_local();
+                let hir_id = tcx.hir().local_def_id_to_hir_id(def_id);
+                let item_def_id = tcx.hir().ty_param_owner(def_id);
                 let generics = tcx.generics_of(item_def_id);
-                let index = generics.param_def_id_to_index[&def_id];
+                let index = generics.param_def_id_to_index[&def_id.to_def_id()];
                 tcx.mk_ty_param(index, tcx.hir().name(hir_id))
             }
             Res::SelfTy { trait_: Some(_), alias_to: None } => {
diff --git a/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs b/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs
index 55a5eb966c2..77cba1c22c4 100644
--- a/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs
+++ b/compiler/rustc_typeck/src/check/fn_ctxt/mod.rs
@@ -184,8 +184,7 @@ impl<'a, 'tcx> AstConv<'tcx> for FnCtxt<'a, 'tcx> {
         _: Ident,
     ) -> ty::GenericPredicates<'tcx> {
         let tcx = self.tcx;
-        let hir_id = tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
-        let item_def_id = tcx.hir().ty_param_owner(hir_id);
+        let item_def_id = tcx.hir().ty_param_owner(def_id.expect_local());
         let generics = tcx.generics_of(item_def_id);
         let index = generics.param_def_id_to_index[&def_id];
         ty::GenericPredicates {
diff --git a/compiler/rustc_typeck/src/collect.rs b/compiler/rustc_typeck/src/collect.rs
index ec783a16ef7..62187b2bdfc 100644
--- a/compiler/rustc_typeck/src/collect.rs
+++ b/compiler/rustc_typeck/src/collect.rs
@@ -558,7 +558,7 @@ fn type_param_predicates(
     // `where T: Foo`.
 
     let param_id = tcx.hir().local_def_id_to_hir_id(def_id);
-    let param_owner = tcx.hir().ty_param_owner(param_id);
+    let param_owner = tcx.hir().ty_param_owner(def_id);
     let generics = tcx.generics_of(param_owner);
     let index = generics.param_def_id_to_index[&def_id.to_def_id()];
     let ty = tcx.mk_ty_param(index, tcx.hir().ty_param_name(param_id));