Create a valid Res in external_path()

The order of the `where` bounds on auto trait impls changed because
rustdoc currently sorts auto trait `where` bounds based on the `Debug`
output for the bound. Now that the bounds have an actual `Res`, they are
being unintentionally sorted by their `DefId` rather than their path.
So, I had to update a test for the change in ordering of the rendered
bounds.

src/librustdoc/clean/mod.rs

@@ -166,7 +166,7 @@ fn clean(&self, cx: &mut DocContext<'_>) -> Type {
         inline::record_extern_fqn(cx, trait_ref.def_id, kind);
         let path = external_path(
             cx,
-            cx.tcx.item_name(trait_ref.def_id),
+            trait_ref.def_id,
             Some(trait_ref.def_id),
             true,
             bounds.to_vec(),
@@ -1448,19 +1448,12 @@ fn clean(&self, cx: &mut DocContext<'_>) -> Type {
                     AdtKind::Enum => ItemType::Enum,
                 };
                 inline::record_extern_fqn(cx, did, kind);
-                let path = external_path(cx, cx.tcx.item_name(did), None, false, vec![], substs);
+                let path = external_path(cx, did, None, false, vec![], substs);
                 ResolvedPath { path, did, is_generic: false }
             }
             ty::Foreign(did) => {
                 inline::record_extern_fqn(cx, did, ItemType::ForeignType);
-                let path = external_path(
-                    cx,
-                    cx.tcx.item_name(did),
-                    None,
-                    false,
-                    vec![],
-                    InternalSubsts::empty(),
-                );
+                let path = external_path(cx, did, None, false, vec![], InternalSubsts::empty());
                 ResolvedPath { path, did, is_generic: false }
             }
             ty::Dynamic(ref obj, ref reg) => {
@@ -1484,8 +1477,7 @@ fn clean(&self, cx: &mut DocContext<'_>) -> Type {
 
                 for did in dids {
                     let empty = cx.tcx.intern_substs(&[]);
-                    let path =
-                        external_path(cx, cx.tcx.item_name(did), Some(did), false, vec![], empty);
+                    let path = external_path(cx, did, Some(did), false, vec![], empty);
                     inline::record_extern_fqn(cx, did, ItemType::Trait);
                     let bound = PolyTrait {
                         trait_: ResolvedPath { path, did, is_generic: false },
@@ -1502,8 +1494,7 @@ fn clean(&self, cx: &mut DocContext<'_>) -> Type {
                     });
                 }
 
-                let path =
-                    external_path(cx, cx.tcx.item_name(did), Some(did), false, bindings, substs);
+                let path = external_path(cx, did, Some(did), false, bindings, substs);
                 bounds.insert(
                     0,
                     PolyTrait {

src/librustdoc/clean/types.rs

@@ -1158,7 +1158,7 @@ impl GenericBound {
     crate fn maybe_sized(cx: &mut DocContext<'_>) -> GenericBound {
         let did = cx.tcx.require_lang_item(LangItem::Sized, None);
         let empty = cx.tcx.intern_substs(&[]);
-        let path = external_path(cx, cx.tcx.item_name(did), Some(did), false, vec![], empty);
+        let path = external_path(cx, did, Some(did), false, vec![], empty);
         inline::record_extern_fqn(cx, did, ItemType::Trait);
         GenericBound::TraitBound(
             PolyTrait {

src/librustdoc/clean/utils.rs

@@ -141,19 +141,21 @@ fn external_generic_args(
     }
 }
 
-// trait_did should be set to a trait's DefId if called on a TraitRef, in order to sugar
-// from Fn<(A, B,), C> to Fn(A, B) -> C
+/// trait_did should be set to a trait's DefId if called on a TraitRef, in order to sugar
+/// from `Fn<(A, B,), C>` to `Fn(A, B) -> C`
 pub(super) fn external_path(
     cx: &mut DocContext<'_>,
-    name: Symbol,
+    did: DefId,
     trait_did: Option<DefId>,
     has_self: bool,
     bindings: Vec<TypeBinding>,
     substs: SubstsRef<'_>,
 ) -> Path {
+    let def_kind = cx.tcx.def_kind(did);
+    let name = cx.tcx.item_name(did);
     Path {
         global: false,
-        res: Res::Err,
+        res: Res::Def(def_kind, did),
         segments: vec![PathSegment {
             name,
             args: external_generic_args(cx, trait_did, has_self, bindings, substs),

src/test/rustdoc/synthetic_auto/no-redundancy.rs

@@ -10,7 +10,7 @@ unsafe impl<T> Send for Inner<T>
 
 // @has no_redundancy/struct.Outer.html
 // @has - '//*[@id="synthetic-implementations-list"]//*[@class="impl has-srclink"]//h3[@class="code-header in-band"]' \
-// "impl<T> Send for Outer<T> where T: Copy + Send"
+// "impl<T> Send for Outer<T> where T: Send + Copy"
 pub struct Outer<T> {
     inner_field: Inner<T>,
 }