Prevent to compute Item attributes twice

Author: GuillaumeGomez

src/librustdoc/clean/inline.rs

@@ -416,7 +416,10 @@ crate fn build_impl(
 
     debug!("build_impl: impl {:?} for {:?}", trait_.def_id(), for_.def_id());
 
-    let mut item = clean::Item::from_def_id_and_parts(
+    let attrs = box merge_attrs(cx, parent_module.into(), load_attrs(cx, did), attrs);
+    debug!("merged_attrs={:?}", attrs);
+
+    ret.push(clean::Item::from_def_id_and_attrs_and_parts(
         did,
         None,
         clean::ImplItem(clean::Impl {
@@ -430,11 +433,9 @@ crate fn build_impl(
             synthetic: false,
             blanket_impl: None,
         }),
+        attrs,
         cx,
-    );
-    item.attrs = box merge_attrs(cx, parent_module.into(), load_attrs(cx, did), attrs);
-    debug!("merged_attrs={:?}", item.attrs);
-    ret.push(item);
+    ));
 }
 
 fn build_module(cx: &DocContext<'_>, did: DefId, visited: &mut FxHashSet<DefId>) -> clean::Module {

src/librustdoc/clean/types.rs

@@ -140,6 +140,22 @@ impl Item {
         name: Option<Symbol>,
         kind: ItemKind,
         cx: &DocContext<'_>,
+    ) -> Item {
+        Self::from_def_id_and_attrs_and_parts(
+            def_id,
+            name,
+            kind,
+            box cx.tcx.get_attrs(def_id).clean(cx),
+            cx,
+        )
+    }
+
+    pub fn from_def_id_and_attrs_and_parts(
+        def_id: DefId,
+        name: Option<Symbol>,
+        kind: ItemKind,
+        attrs: Box<Attributes>,
+        cx: &DocContext<'_>,
     ) -> Item {
         debug!("name={:?}, def_id={:?}", name, def_id);
 
@@ -157,7 +173,7 @@ impl Item {
             kind: box kind,
             name,
             source: source.clean(cx),
-            attrs: box cx.tcx.get_attrs(def_id).clean(cx),
+            attrs,
             visibility: cx.tcx.visibility(def_id).clean(cx),
         }
     }