diff --git a/src/librustdoc/clean/inline.rs b/src/librustdoc/clean/inline.rs
index ce10ca9aa3df4..6b37b8e4db46e 100644
--- a/src/librustdoc/clean/inline.rs
+++ b/src/librustdoc/clean/inline.rs
@@ -214,14 +214,7 @@ pub(crate) fn build_external_trait(cx: &mut DocContext<'_>, did: DefId) -> clean
     let generics = clean_ty_generics(cx, cx.tcx.generics_of(did), predicates);
     let generics = filter_non_trait_generics(did, generics);
     let (generics, supertrait_bounds) = separate_supertrait_bounds(generics);
-    let is_auto = cx.tcx.trait_is_auto(did);
-    clean::Trait {
-        unsafety: cx.tcx.trait_def(did).unsafety,
-        generics,
-        items: trait_items,
-        bounds: supertrait_bounds,
-        is_auto,
-    }
+    clean::Trait { def_id: did, generics, items: trait_items, bounds: supertrait_bounds }
 }
 
 fn build_external_function<'tcx>(cx: &mut DocContext<'tcx>, did: DefId) -> clean::Function {
diff --git a/src/librustdoc/clean/mod.rs b/src/librustdoc/clean/mod.rs
index 9865601da5fc7..43ebaab98db60 100644
--- a/src/librustdoc/clean/mod.rs
+++ b/src/librustdoc/clean/mod.rs
@@ -1972,15 +1972,14 @@ fn clean_maybe_renamed_item<'tcx>(
                     source: display_macro_source(cx, name, macro_def, def_id, ty_vis),
                 })
             }
-            ItemKind::Trait(is_auto, unsafety, generics, bounds, item_ids) => {
+            ItemKind::Trait(_, _, generics, bounds, item_ids) => {
                 let items =
                     item_ids.iter().map(|ti| cx.tcx.hir().trait_item(ti.id).clean(cx)).collect();
                 TraitItem(Trait {
-                    unsafety,
+                    def_id,
                     items,
                     generics: generics.clean(cx),
                     bounds: bounds.iter().filter_map(|x| x.clean(cx)).collect(),
-                    is_auto: is_auto.clean(cx),
                 })
             }
             ItemKind::ExternCrate(orig_name) => {
diff --git a/src/librustdoc/clean/types.rs b/src/librustdoc/clean/types.rs
index 8c08f77667904..0381ca2b3d173 100644
--- a/src/librustdoc/clean/types.rs
+++ b/src/librustdoc/clean/types.rs
@@ -1514,11 +1514,19 @@ impl FnRetTy {
 
 #[derive(Clone, Debug)]
 pub(crate) struct Trait {
-    pub(crate) unsafety: hir::Unsafety,
+    pub(crate) def_id: DefId,
     pub(crate) items: Vec<Item>,
     pub(crate) generics: Generics,
     pub(crate) bounds: Vec<GenericBound>,
-    pub(crate) is_auto: bool,
+}
+
+impl Trait {
+    pub(crate) fn is_auto(&self, tcx: TyCtxt<'_>) -> bool {
+        tcx.trait_is_auto(self.def_id)
+    }
+    pub(crate) fn unsafety(&self, tcx: TyCtxt<'_>) -> hir::Unsafety {
+        tcx.trait_def(self.def_id).unsafety
+    }
 }
 
 #[derive(Clone, Debug)]
diff --git a/src/librustdoc/core.rs b/src/librustdoc/core.rs
index 0e9a9e0e50646..f46fde7b35a6d 100644
--- a/src/librustdoc/core.rs
+++ b/src/librustdoc/core.rs
@@ -390,8 +390,7 @@ pub(crate) fn run_global_ctxt(
     //
     // Note that in case of `#![no_core]`, the trait is not available.
     if let Some(sized_trait_did) = ctxt.tcx.lang_items().sized_trait() {
-        let mut sized_trait = build_external_trait(&mut ctxt, sized_trait_did);
-        sized_trait.is_auto = true;
+        let sized_trait = build_external_trait(&mut ctxt, sized_trait_did);
         ctxt.external_traits
             .borrow_mut()
             .insert(sized_trait_did, TraitWithExtraInfo { trait_: sized_trait, is_notable: false });
diff --git a/src/librustdoc/html/render/mod.rs b/src/librustdoc/html/render/mod.rs
index c1fdece9ec6da..89d372da32278 100644
--- a/src/librustdoc/html/render/mod.rs
+++ b/src/librustdoc/html/render/mod.rs
@@ -2295,7 +2295,7 @@ fn sidebar_trait(cx: &Context<'_>, buf: &mut Buffer, it: &clean::Item, t: &clean
     sidebar_assoc_items(cx, buf, it);
 
     print_sidebar_title(buf, "implementors", "Implementors");
-    if t.is_auto {
+    if t.is_auto(cx.tcx()) {
         print_sidebar_title(buf, "synthetic-implementors", "Auto Implementors");
     }
 
diff --git a/src/librustdoc/html/render/print_item.rs b/src/librustdoc/html/render/print_item.rs
index daacc57a55a3a..b035a81e40218 100644
--- a/src/librustdoc/html/render/print_item.rs
+++ b/src/librustdoc/html/render/print_item.rs
@@ -548,8 +548,8 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
                 w,
                 "{}{}{}trait {}{}{}",
                 it.visibility.print_with_space(it.item_id, cx),
-                t.unsafety.print_with_space(),
-                if t.is_auto { "auto " } else { "" },
+                t.unsafety(cx.tcx()).print_with_space(),
+                if t.is_auto(cx.tcx()) { "auto " } else { "" },
                 it.name.unwrap(),
                 t.generics.print(cx),
                 bounds
@@ -883,7 +883,7 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
         }
         w.write_str("</div>");
 
-        if t.is_auto {
+        if t.is_auto(cx.tcx()) {
             write_small_section_header(
                 w,
                 "synthetic-implementors",
@@ -912,7 +912,7 @@ fn item_trait(w: &mut Buffer, cx: &mut Context<'_>, it: &clean::Item, t: &clean:
             "<div class=\"item-list\" id=\"implementors-list\"></div>",
         );
 
-        if t.is_auto {
+        if t.is_auto(cx.tcx()) {
             write_small_section_header(
                 w,
                 "synthetic-implementors",
diff --git a/src/librustdoc/json/conversions.rs b/src/librustdoc/json/conversions.rs
index 9000ab472d96e..e7216a066149b 100644
--- a/src/librustdoc/json/conversions.rs
+++ b/src/librustdoc/json/conversions.rs
@@ -554,10 +554,12 @@ impl FromWithTcx<clean::FnDecl> for FnDecl {
 
 impl FromWithTcx<clean::Trait> for Trait {
     fn from_tcx(trait_: clean::Trait, tcx: TyCtxt<'_>) -> Self {
-        let clean::Trait { unsafety, items, generics, bounds, is_auto } = trait_;
+        let is_auto = trait_.is_auto(tcx);
+        let is_unsafe = trait_.unsafety(tcx) == rustc_hir::Unsafety::Unsafe;
+        let clean::Trait { items, generics, bounds, .. } = trait_;
         Trait {
             is_auto,
-            is_unsafe: unsafety == rustc_hir::Unsafety::Unsafe,
+            is_unsafe,
             items: ids(items, tcx),
             generics: generics.into_tcx(tcx),
             bounds: bounds.into_iter().map(|x| x.into_tcx(tcx)).collect(),